diff options
Diffstat (limited to 'fs/jbd')
| -rw-r--r-- | fs/jbd/Makefile | 7 | ||||
| -rw-r--r-- | fs/jbd/checkpoint.c | 636 | ||||
| -rw-r--r-- | fs/jbd/commit.c | 844 | ||||
| -rw-r--r-- | fs/jbd/journal.c | 2003 | ||||
| -rw-r--r-- | fs/jbd/recovery.c | 591 | ||||
| -rw-r--r-- | fs/jbd/revoke.c | 702 | ||||
| -rw-r--r-- | fs/jbd/transaction.c | 2062 |
7 files changed, 6845 insertions, 0 deletions
diff --git a/fs/jbd/Makefile b/fs/jbd/Makefile new file mode 100644 index 00000000000..54aca4868a3 --- /dev/null +++ b/fs/jbd/Makefile @@ -0,0 +1,7 @@ +# +# Makefile for the linux journaling routines. +# + +obj-$(CONFIG_JBD) += jbd.o + +jbd-objs := transaction.o commit.o recovery.o checkpoint.o revoke.o journal.o diff --git a/fs/jbd/checkpoint.c b/fs/jbd/checkpoint.c new file mode 100644 index 00000000000..98d830401c5 --- /dev/null +++ b/fs/jbd/checkpoint.c @@ -0,0 +1,636 @@ +/* + * linux/fs/checkpoint.c + * + * Written by Stephen C. Tweedie <sct@redhat.com>, 1999 + * + * Copyright 1999 Red Hat Software --- All Rights Reserved + * + * This file is part of the Linux kernel and is made available under + * the terms of the GNU General Public License, version 2, or at your + * option, any later version, incorporated herein by reference. + * + * Checkpoint routines for the generic filesystem journaling code. + * Part of the ext2fs journaling system. + * + * Checkpointing is the process of ensuring that a section of the log is + * committed fully to disk, so that that portion of the log can be + * reused. + */ + +#include <linux/time.h> +#include <linux/fs.h> +#include <linux/jbd.h> +#include <linux/errno.h> +#include <linux/slab.h> + +/* + * Unlink a buffer from a transaction. + * + * Called with j_list_lock held. + */ + +static inline void __buffer_unlink(struct journal_head *jh) +{ + transaction_t *transaction; + + transaction = jh->b_cp_transaction; + jh->b_cp_transaction = NULL; + + jh->b_cpnext->b_cpprev = jh->b_cpprev; + jh->b_cpprev->b_cpnext = jh->b_cpnext; + if (transaction->t_checkpoint_list == jh) + transaction->t_checkpoint_list = jh->b_cpnext; + if (transaction->t_checkpoint_list == jh) + transaction->t_checkpoint_list = NULL; +} + +/* + * Try to release a checkpointed buffer from its transaction. + * Returns 1 if we released it. + * Requires j_list_lock + * Called under jbd_lock_bh_state(jh2bh(jh)), and drops it + */ +static int __try_to_free_cp_buf(struct journal_head *jh) +{ + int ret = 0; + struct buffer_head *bh = jh2bh(jh); + + if (jh->b_jlist == BJ_None && !buffer_locked(bh) && !buffer_dirty(bh)) { + JBUFFER_TRACE(jh, "remove from checkpoint list"); + __journal_remove_checkpoint(jh); + jbd_unlock_bh_state(bh); + journal_remove_journal_head(bh); + BUFFER_TRACE(bh, "release"); + __brelse(bh); + ret = 1; + } else { + jbd_unlock_bh_state(bh); + } + return ret; +} + +/* + * __log_wait_for_space: wait until there is space in the journal. + * + * Called under j-state_lock *only*. It will be unlocked if we have to wait + * for a checkpoint to free up some space in the log. + */ +void __log_wait_for_space(journal_t *journal) +{ + int nblocks; + assert_spin_locked(&journal->j_state_lock); + + nblocks = jbd_space_needed(journal); + while (__log_space_left(journal) < nblocks) { + if (journal->j_flags & JFS_ABORT) + return; + spin_unlock(&journal->j_state_lock); + down(&journal->j_checkpoint_sem); + + /* + * Test again, another process may have checkpointed while we + * were waiting for the checkpoint lock + */ + spin_lock(&journal->j_state_lock); + nblocks = jbd_space_needed(journal); + if (__log_space_left(journal) < nblocks) { + spin_unlock(&journal->j_state_lock); + log_do_checkpoint(journal); + spin_lock(&journal->j_state_lock); + } + up(&journal->j_checkpoint_sem); + } +} + +/* + * We were unable to perform jbd_trylock_bh_state() inside j_list_lock. + * The caller must restart a list walk. Wait for someone else to run + * jbd_unlock_bh_state(). + */ +static void jbd_sync_bh(journal_t *journal, struct buffer_head *bh) +{ + get_bh(bh); + spin_unlock(&journal->j_list_lock); + jbd_lock_bh_state(bh); + jbd_unlock_bh_state(bh); + put_bh(bh); +} + +/* + * Clean up a transaction's checkpoint list. + * + * We wait for any pending IO to complete and make sure any clean + * buffers are removed from the transaction. + * + * Return 1 if we performed any actions which might have destroyed the + * checkpoint. (journal_remove_checkpoint() deletes the transaction when + * the last checkpoint buffer is cleansed) + * + * Called with j_list_lock held. + */ +static int __cleanup_transaction(journal_t *journal, transaction_t *transaction) +{ + struct journal_head *jh, *next_jh, *last_jh; + struct buffer_head *bh; + int ret = 0; + + assert_spin_locked(&journal->j_list_lock); + jh = transaction->t_checkpoint_list; + if (!jh) + return 0; + + last_jh = jh->b_cpprev; + next_jh = jh; + do { + jh = next_jh; + bh = jh2bh(jh); + if (buffer_locked(bh)) { + atomic_inc(&bh->b_count); + spin_unlock(&journal->j_list_lock); + wait_on_buffer(bh); + /* the journal_head may have gone by now */ + BUFFER_TRACE(bh, "brelse"); + __brelse(bh); + goto out_return_1; + } + + /* + * This is foul + */ + if (!jbd_trylock_bh_state(bh)) { + jbd_sync_bh(journal, bh); + goto out_return_1; + } + + if (jh->b_transaction != NULL) { + transaction_t *t = jh->b_transaction; + tid_t tid = t->t_tid; + + spin_unlock(&journal->j_list_lock); + jbd_unlock_bh_state(bh); + log_start_commit(journal, tid); + log_wait_commit(journal, tid); + goto out_return_1; + } + + /* + * AKPM: I think the buffer_jbddirty test is redundant - it + * shouldn't have NULL b_transaction? + */ + next_jh = jh->b_cpnext; + if (!buffer_dirty(bh) && !buffer_jbddirty(bh)) { + BUFFER_TRACE(bh, "remove from checkpoint"); + __journal_remove_checkpoint(jh); + jbd_unlock_bh_state(bh); + journal_remove_journal_head(bh); + __brelse(bh); + ret = 1; + } else { + jbd_unlock_bh_state(bh); + } + jh = next_jh; + } while (jh != last_jh); + + return ret; +out_return_1: + spin_lock(&journal->j_list_lock); + return 1; +} + +#define NR_BATCH 64 + +static void +__flush_batch(journal_t *journal, struct buffer_head **bhs, int *batch_count) +{ + int i; + + spin_unlock(&journal->j_list_lock); + ll_rw_block(WRITE, *batch_count, bhs); + spin_lock(&journal->j_list_lock); + for (i = 0; i < *batch_count; i++) { + struct buffer_head *bh = bhs[i]; + clear_buffer_jwrite(bh); + BUFFER_TRACE(bh, "brelse"); + __brelse(bh); + } + *batch_count = 0; +} + +/* + * Try to flush one buffer from the checkpoint list to disk. + * + * Return 1 if something happened which requires us to abort the current + * scan of the checkpoint list. + * + * Called with j_list_lock held. + * Called under jbd_lock_bh_state(jh2bh(jh)), and drops it + */ +static int __flush_buffer(journal_t *journal, struct journal_head *jh, + struct buffer_head **bhs, int *batch_count, + int *drop_count) +{ + struct buffer_head *bh = jh2bh(jh); + int ret = 0; + + if (buffer_dirty(bh) && !buffer_locked(bh) && jh->b_jlist == BJ_None) { + J_ASSERT_JH(jh, jh->b_transaction == NULL); + + /* + * Important: we are about to write the buffer, and + * possibly block, while still holding the journal lock. + * We cannot afford to let the transaction logic start + * messing around with this buffer before we write it to + * disk, as that would break recoverability. + */ + BUFFER_TRACE(bh, "queue"); + get_bh(bh); + J_ASSERT_BH(bh, !buffer_jwrite(bh)); + set_buffer_jwrite(bh); + bhs[*batch_count] = bh; + jbd_unlock_bh_state(bh); + (*batch_count)++; + if (*batch_count == NR_BATCH) { + __flush_batch(journal, bhs, batch_count); + ret = 1; + } + } else { + int last_buffer = 0; + if (jh->b_cpnext == jh) { + /* We may be about to drop the transaction. Tell the + * caller that the lists have changed. + */ + last_buffer = 1; + } + if (__try_to_free_cp_buf(jh)) { + (*drop_count)++; + ret = last_buffer; + } + } + return ret; +} + +/* + * Perform an actual checkpoint. We don't write out only enough to + * satisfy the current blocked requests: rather we submit a reasonably + * sized chunk of the outstanding data to disk at once for + * efficiency. __log_wait_for_space() will retry if we didn't free enough. + * + * However, we _do_ take into account the amount requested so that once + * the IO has been queued, we can return as soon as enough of it has + * completed to disk. + * + * The journal should be locked before calling this function. + */ +int log_do_checkpoint(journal_t *journal) +{ + int result; + int batch_count = 0; + struct buffer_head *bhs[NR_BATCH]; + + jbd_debug(1, "Start checkpoint\n"); + + /* + * First thing: if there are any transactions in the log which + * don't need checkpointing, just eliminate them from the + * journal straight away. + */ + result = cleanup_journal_tail(journal); + jbd_debug(1, "cleanup_journal_tail returned %d\n", result); + if (result <= 0) + return result; + + /* + * OK, we need to start writing disk blocks. Try to free up a + * quarter of the log in a single checkpoint if we can. + */ + /* + * AKPM: check this code. I had a feeling a while back that it + * degenerates into a busy loop at unmount time. + */ + spin_lock(&journal->j_list_lock); + while (journal->j_checkpoint_transactions) { + transaction_t *transaction; + struct journal_head *jh, *last_jh, *next_jh; + int drop_count = 0; + int cleanup_ret, retry = 0; + tid_t this_tid; + + transaction = journal->j_checkpoint_transactions; + this_tid = transaction->t_tid; + jh = transaction->t_checkpoint_list; + last_jh = jh->b_cpprev; + next_jh = jh; + do { + struct buffer_head *bh; + + jh = next_jh; + next_jh = jh->b_cpnext; + bh = jh2bh(jh); + if (!jbd_trylock_bh_state(bh)) { + jbd_sync_bh(journal, bh); + spin_lock(&journal->j_list_lock); + retry = 1; + break; + } + retry = __flush_buffer(journal, jh, bhs, &batch_count, &drop_count); + if (cond_resched_lock(&journal->j_list_lock)) { + retry = 1; + break; + } + } while (jh != last_jh && !retry); + + if (batch_count) + __flush_batch(journal, bhs, &batch_count); + + /* + * If someone cleaned up this transaction while we slept, we're + * done + */ + if (journal->j_checkpoint_transactions != transaction) + break; + if (retry) + continue; + /* + * Maybe it's a new transaction, but it fell at the same + * address + */ + if (transaction->t_tid != this_tid) + continue; + /* + * We have walked the whole transaction list without + * finding anything to write to disk. We had better be + * able to make some progress or we are in trouble. + */ + cleanup_ret = __cleanup_transaction(journal, transaction); + J_ASSERT(drop_count != 0 || cleanup_ret != 0); + if (journal->j_checkpoint_transactions != transaction) + break; + } + spin_unlock(&journal->j_list_lock); + result = cleanup_journal_tail(journal); + if (result < 0) + return result; + + return 0; +} + +/* + * Check the list of checkpoint transactions for the journal to see if + * we have already got rid of any since the last update of the log tail + * in the journal superblock. If so, we can instantly roll the + * superblock forward to remove those transactions from the log. + * + * Return <0 on error, 0 on success, 1 if there was nothing to clean up. + * + * Called with the journal lock held. + * + * This is the only part of the journaling code which really needs to be + * aware of transaction aborts. Checkpointing involves writing to the + * main filesystem area rather than to the journal, so it can proceed + * even in abort state, but we must not update the journal superblock if + * we have an abort error outstanding. + */ + +int cleanup_journal_tail(journal_t *journal) +{ + transaction_t * transaction; + tid_t first_tid; + unsigned long blocknr, freed; + + /* OK, work out the oldest transaction remaining in the log, and + * the log block it starts at. + * + * If the log is now empty, we need to work out which is the + * next transaction ID we will write, and where it will + * start. */ + + spin_lock(&journal->j_state_lock); + spin_lock(&journal->j_list_lock); + transaction = journal->j_checkpoint_transactions; + if (transaction) { + first_tid = transaction->t_tid; + blocknr = transaction->t_log_start; + } else if ((transaction = journal->j_committing_transaction) != NULL) { + first_tid = transaction->t_tid; + blocknr = transaction->t_log_start; + } else if ((transaction = journal->j_running_transaction) != NULL) { + first_tid = transaction->t_tid; + blocknr = journal->j_head; + } else { + first_tid = journal->j_transaction_sequence; + blocknr = journal->j_head; + } + spin_unlock(&journal->j_list_lock); + J_ASSERT(blocknr != 0); + + /* If the oldest pinned transaction is at the tail of the log + already then there's not much we can do right now. */ + if (journal->j_tail_sequence == first_tid) { + spin_unlock(&journal->j_state_lock); + return 1; + } + + /* OK, update the superblock to recover the freed space. + * Physical blocks come first: have we wrapped beyond the end of + * the log? */ + freed = blocknr - journal->j_tail; + if (blocknr < journal->j_tail) + freed = freed + journal->j_last - journal->j_first; + + jbd_debug(1, + "Cleaning journal tail from %d to %d (offset %lu), " + "freeing %lu\n", + journal->j_tail_sequence, first_tid, blocknr, freed); + + journal->j_free += freed; + journal->j_tail_sequence = first_tid; + journal->j_tail = blocknr; + spin_unlock(&journal->j_state_lock); + if (!(journal->j_flags & JFS_ABORT)) + journal_update_superblock(journal, 1); + return 0; +} + + +/* Checkpoint list management */ + +/* + * journal_clean_checkpoint_list + * + * Find all the written-back checkpoint buffers in the journal and release them. + * + * Called with the journal locked. + * Called with j_list_lock held. + * Returns number of bufers reaped (for debug) + */ + +int __journal_clean_checkpoint_list(journal_t *journal) +{ + transaction_t *transaction, *last_transaction, *next_transaction; + int ret = 0; + + transaction = journal->j_checkpoint_transactions; + if (transaction == 0) + goto out; + + last_transaction = transaction->t_cpprev; + next_transaction = transaction; + do { + struct journal_head *jh; + + transaction = next_transaction; + next_transaction = transaction->t_cpnext; + jh = transaction->t_checkpoint_list; + if (jh) { + struct journal_head *last_jh = jh->b_cpprev; + struct journal_head *next_jh = jh; + + do { + jh = next_jh; + next_jh = jh->b_cpnext; + /* Use trylock because of the ranknig */ + if (jbd_trylock_bh_state(jh2bh(jh))) + ret += __try_to_free_cp_buf(jh); + /* + * This function only frees up some memory + * if possible so we dont have an obligation + * to finish processing. Bail out if preemption + * requested: + */ + if (need_resched()) + goto out; + } while (jh != last_jh); + } + } while (transaction != last_transaction); +out: + return ret; +} + +/* + * journal_remove_checkpoint: called after a buffer has been committed + * to disk (either by being write-back flushed to disk, or being + * committed to the log). + * + * We cannot safely clean a transaction out of the log until all of the + * buffer updates committed in that transaction have safely been stored + * elsewhere on disk. To achieve this, all of the buffers in a + * transaction need to be maintained on the transaction's checkpoint + * list until they have been rewritten, at which point this function is + * called to remove the buffer from the existing transaction's + * checkpoint list. + * + * This function is called with the journal locked. + * This function is called with j_list_lock held. + */ + +void __journal_remove_checkpoint(struct journal_head *jh) +{ + transaction_t *transaction; + journal_t *journal; + + JBUFFER_TRACE(jh, "entry"); + + if ((transaction = jh->b_cp_transaction) == NULL) { + JBUFFER_TRACE(jh, "not on transaction"); + goto out; + } + journal = transaction->t_journal; + + __buffer_unlink(jh); + + if (transaction->t_checkpoint_list != NULL) + goto out; + JBUFFER_TRACE(jh, "transaction has no more buffers"); + + /* + * There is one special case to worry about: if we have just pulled the + * buffer off a committing transaction's forget list, then even if the + * checkpoint list is empty, the transaction obviously cannot be + * dropped! + * + * The locking here around j_committing_transaction is a bit sleazy. + * See the comment at the end of journal_commit_transaction(). + */ + if (transaction == journal->j_committing_transaction) { + JBUFFER_TRACE(jh, "belongs to committing transaction"); + goto out; + } + + /* OK, that was the last buffer for the transaction: we can now + safely remove this transaction from the log */ + + __journal_drop_transaction(journal, transaction); + + /* Just in case anybody was waiting for more transactions to be + checkpointed... */ + wake_up(&journal->j_wait_logspace); +out: + JBUFFER_TRACE(jh, "exit"); +} + +/* + * journal_insert_checkpoint: put a committed buffer onto a checkpoint + * list so that we know when it is safe to clean the transaction out of + * the log. + * + * Called with the journal locked. + * Called with j_list_lock held. + */ +void __journal_insert_checkpoint(struct journal_head *jh, + transaction_t *transaction) +{ + JBUFFER_TRACE(jh, "entry"); + J_ASSERT_JH(jh, buffer_dirty(jh2bh(jh)) || buffer_jbddirty(jh2bh(jh))); + J_ASSERT_JH(jh, jh->b_cp_transaction == NULL); + + jh->b_cp_transaction = transaction; + + if (!transaction->t_checkpoint_list) { + jh->b_cpnext = jh->b_cpprev = jh; + } else { + jh->b_cpnext = transaction->t_checkpoint_list; + jh->b_cpprev = transaction->t_checkpoint_list->b_cpprev; + jh->b_cpprev->b_cpnext = jh; + jh->b_cpnext->b_cpprev = jh; + } + transaction->t_checkpoint_list = jh; +} + +/* + * We've finished with this transaction structure: adios... + * + * The transaction must have no links except for the checkpoint by this + * point. + * + * Called with the journal locked. + * Called with j_list_lock held. + */ + +void __journal_drop_transaction(journal_t *journal, transaction_t *transaction) +{ + assert_spin_locked(&journal->j_list_lock); + if (transaction->t_cpnext) { + transaction->t_cpnext->t_cpprev = transaction->t_cpprev; + transaction->t_cpprev->t_cpnext = transaction->t_cpnext; + if (journal->j_checkpoint_transactions == transaction) + journal->j_checkpoint_transactions = + transaction->t_cpnext; + if (journal->j_checkpoint_transactions == transaction) + journal->j_checkpoint_transactions = NULL; + } + + J_ASSERT(transaction->t_state == T_FINISHED); + J_ASSERT(transaction->t_buffers == NULL); + J_ASSERT(transaction->t_sync_datalist == NULL); + J_ASSERT(transaction->t_forget == NULL); + J_ASSERT(transaction->t_iobuf_list == NULL); + J_ASSERT(transaction->t_shadow_list == NULL); + J_ASSERT(transaction->t_log_list == NULL); + J_ASSERT(transaction->t_checkpoint_list == NULL); + J_ASSERT(transaction->t_updates == 0); + J_ASSERT(journal->j_committing_transaction != transaction); + J_ASSERT(journal->j_running_transaction != transaction); + + jbd_debug(1, "Dropping transaction %d, all done\n", transaction->t_tid); + kfree(transaction); +} diff --git a/fs/jbd/commit.c b/fs/jbd/commit.c new file mode 100644 index 00000000000..dac720c837a --- /dev/null +++ b/fs/jbd/commit.c @@ -0,0 +1,844 @@ +/* + * linux/fs/commit.c + * + * Written by Stephen C. Tweedie <sct@redhat.com>, 1998 + * + * Copyright 1998 Red Hat corp --- All Rights Reserved + * + * This file is part of the Linux kernel and is made available under + * the terms of the GNU General Public License, version 2, or at your + * option, any later version, incorporated herein by reference. + * + * Journal commit routines for the generic filesystem journaling code; + * part of the ext2fs journaling system. + */ + +#include <linux/time.h> +#include <linux/fs.h> +#include <linux/jbd.h> +#include <linux/errno.h> +#include <linux/slab.h> +#include <linux/mm.h> +#include <linux/pagemap.h> +#include <linux/smp_lock.h> + +/* + * Default IO end handler for temporary BJ_IO buffer_heads. + */ +static void journal_end_buffer_io_sync(struct buffer_head *bh, int uptodate) +{ + BUFFER_TRACE(bh, ""); + if (uptodate) + set_buffer_uptodate(bh); + else + clear_buffer_uptodate(bh); + unlock_buffer(bh); +} + +/* + * When an ext3-ordered file is truncated, it is possible that many pages are + * not sucessfully freed, because they are attached to a committing transaction. + * After the transaction commits, these pages are left on the LRU, with no + * ->mapping, and with attached buffers. These pages are trivially reclaimable + * by the VM, but their apparent absence upsets the VM accounting, and it makes + * the numbers in /proc/meminfo look odd. + * + * So here, we have a buffer which has just come off the forget list. Look to + * see if we can strip all buffers from the backing page. + * + * Called under lock_journal(), and possibly under journal_datalist_lock. The + * caller provided us with a ref against the buffer, and we drop that here. + */ +static void release_buffer_page(struct buffer_head *bh) +{ + struct page *page; + + if (buffer_dirty(bh)) + goto nope; + if (atomic_read(&bh->b_count) != 1) + goto nope; + page = bh->b_page; + if (!page) + goto nope; + if (page->mapping) + goto nope; + + /* OK, it's a truncated page */ + if (TestSetPageLocked(page)) + goto nope; + + page_cache_get(page); + __brelse(bh); + try_to_free_buffers(page); + unlock_page(page); + page_cache_release(page); + return; + +nope: + __brelse(bh); +} + +/* + * Try to acquire jbd_lock_bh_state() against the buffer, when j_list_lock is + * held. For ranking reasons we must trylock. If we lose, schedule away and + * return 0. j_list_lock is dropped in this case. + */ +static int inverted_lock(journal_t *journal, struct buffer_head *bh) +{ + if (!jbd_trylock_bh_state(bh)) { + spin_unlock(&journal->j_list_lock); + schedule(); + return 0; + } + return 1; +} + +/* Done it all: now write the commit record. We should have + * cleaned up our previous buffers by now, so if we are in abort + * mode we can now just skip the rest of the journal write + * entirely. + * + * Returns 1 if the journal needs to be aborted or 0 on success + */ +static int journal_write_commit_record(journal_t *journal, + transaction_t *commit_transaction) +{ + struct journal_head *descriptor; + struct buffer_head *bh; + int i, ret; + int barrier_done = 0; + + if (is_journal_aborted(journal)) + return 0; + + descriptor = journal_get_descriptor_buffer(journal); + if (!descriptor) + return 1; + + bh = jh2bh(descriptor); + + /* AKPM: buglet - add `i' to tmp! */ + for (i = 0; i < bh->b_size; i += 512) { + journal_header_t *tmp = (journal_header_t*)bh->b_data; + tmp->h_magic = cpu_to_be32(JFS_MAGIC_NUMBER); + tmp->h_blocktype = cpu_to_be32(JFS_COMMIT_BLOCK); + tmp->h_sequence = cpu_to_be32(commit_transaction->t_tid); + } + + JBUFFER_TRACE(descriptor, "write commit block"); + set_buffer_dirty(bh); + if (journal->j_flags & JFS_BARRIER) { + set_buffer_ordered(bh); + barrier_done = 1; + } + ret = sync_dirty_buffer(bh); + /* is it possible for another commit to fail at roughly + * the same time as this one? If so, we don't want to + * trust the barrier flag in the super, but instead want + * to remember if we sent a barrier request + */ + if (ret == -EOPNOTSUPP && barrier_done) { + char b[BDEVNAME_SIZE]; + + printk(KERN_WARNING + "JBD: barrier-based sync failed on %s - " + "disabling barriers\n", + bdevname(journal->j_dev, b)); + spin_lock(&journal->j_state_lock); + journal->j_flags &= ~JFS_BARRIER; + spin_unlock(&journal->j_state_lock); + + /* And try again, without the barrier */ + clear_buffer_ordered(bh); + set_buffer_uptodate(bh); + set_buffer_dirty(bh); + ret = sync_dirty_buffer(bh); + } + put_bh(bh); /* One for getblk() */ + journal_put_journal_head(descriptor); + + return (ret == -EIO); +} + +/* + * journal_commit_transaction + * + * The primary function for committing a transaction to the log. This + * function is called by the journal thread to begin a complete commit. + */ +void journal_commit_transaction(journal_t *journal) +{ + transaction_t *commit_transaction; + struct journal_head *jh, *new_jh, *descriptor; + struct buffer_head **wbuf = journal->j_wbuf; + int bufs; + int flags; + int err; + unsigned long blocknr; + char *tagp = NULL; + journal_header_t *header; + journal_block_tag_t *tag = NULL; + int space_left = 0; + int first_tag = 0; + int tag_flag; + int i; + + /* + * First job: lock down the current transaction and wait for + * all outstanding updates to complete. + */ + +#ifdef COMMIT_STATS + spin_lock(&journal->j_list_lock); + summarise_journal_usage(journal); + spin_unlock(&journal->j_list_lock); +#endif + + /* Do we need to erase the effects of a prior journal_flush? */ + if (journal->j_flags & JFS_FLUSHED) { + jbd_debug(3, "super block updated\n"); + journal_update_superblock(journal, 1); + } else { + jbd_debug(3, "superblock not updated\n"); + } + + J_ASSERT(journal->j_running_transaction != NULL); + J_ASSERT(journal->j_committing_transaction == NULL); + + commit_transaction = journal->j_running_transaction; + J_ASSERT(commit_transaction->t_state == T_RUNNING); + + jbd_debug(1, "JBD: starting commit of transaction %d\n", + commit_transaction->t_tid); + + spin_lock(&journal->j_state_lock); + commit_transaction->t_state = T_LOCKED; + + spin_lock(&commit_transaction->t_handle_lock); + while (commit_transaction->t_updates) { + DEFINE_WAIT(wait); + + prepare_to_wait(&journal->j_wait_updates, &wait, + TASK_UNINTERRUPTIBLE); + if (commit_transaction->t_updates) { + spin_unlock(&commit_transaction->t_handle_lock); + spin_unlock(&journal->j_state_lock); + schedule(); + spin_lock(&journal->j_state_lock); + spin_lock(&commit_transaction->t_handle_lock); + } + finish_wait(&journal->j_wait_updates, &wait); + } + spin_unlock(&commit_transaction->t_handle_lock); + + J_ASSERT (commit_transaction->t_outstanding_credits <= + journal->j_max_transaction_buffers); + + /* + * First thing we are allowed to do is to discard any remaining + * BJ_Reserved buffers. Note, it is _not_ permissible to assume + * that there are no such buffers: if a large filesystem + * operation like a truncate needs to split itself over multiple + * transactions, then it may try to do a journal_restart() while + * there are still BJ_Reserved buffers outstanding. These must + * be released cleanly from the current transaction. + * + * In this case, the filesystem must still reserve write access + * again before modifying the buffer in the new transaction, but + * we do not require it to remember exactly which old buffers it + * has reserved. This is consistent with the existing behaviour + * that multiple journal_get_write_access() calls to the same + * buffer are perfectly permissable. + */ + while (commit_transaction->t_reserved_list) { + jh = commit_transaction->t_reserved_list; + JBUFFER_TRACE(jh, "reserved, unused: refile"); + /* + * A journal_get_undo_access()+journal_release_buffer() may + * leave undo-committed data. + */ + if (jh->b_committed_data) { + struct buffer_head *bh = jh2bh(jh); + + jbd_lock_bh_state(bh); + if (jh->b_committed_data) { + kfree(jh->b_committed_data); + jh->b_committed_data = NULL; + } + jbd_unlock_bh_state(bh); + } + journal_refile_buffer(journal, jh); + } + + /* + * Now try to drop any written-back buffers from the journal's + * checkpoint lists. We do this *before* commit because it potentially + * frees some memory + */ + spin_lock(&journal->j_list_lock); + __journal_clean_checkpoint_list(journal); + spin_unlock(&journal->j_list_lock); + + jbd_debug (3, "JBD: commit phase 1\n"); + + /* + * Switch to a new revoke table. + */ + journal_switch_revoke_table(journal); + + commit_transaction->t_state = T_FLUSH; + journal->j_committing_transaction = commit_transaction; + journal->j_running_transaction = NULL; + commit_transaction->t_log_start = journal->j_head; + wake_up(&journal->j_wait_transaction_locked); + spin_unlock(&journal->j_state_lock); + + jbd_debug (3, "JBD: commit phase 2\n"); + + /* + * First, drop modified flag: all accesses to the buffers + * will be tracked for a new trasaction only -bzzz + */ + spin_lock(&journal->j_list_lock); + if (commit_transaction->t_buffers) { + new_jh = jh = commit_transaction->t_buffers->b_tnext; + do { + J_ASSERT_JH(new_jh, new_jh->b_modified == 1 || + new_jh->b_modified == 0); + new_jh->b_modified = 0; + new_jh = new_jh->b_tnext; + } while (new_jh != jh); + } + spin_unlock(&journal->j_list_lock); + + /* + * Now start flushing things to disk, in the order they appear + * on the transaction lists. Data blocks go first. + */ + + err = 0; + /* + * Whenever we unlock the journal and sleep, things can get added + * onto ->t_sync_datalist, so we have to keep looping back to + * write_out_data until we *know* that the list is empty. + */ + bufs = 0; + /* + * Cleanup any flushed data buffers from the data list. Even in + * abort mode, we want to flush this out as soon as possible. + */ +write_out_data: + cond_resched(); + spin_lock(&journal->j_list_lock); + + while (commit_transaction->t_sync_datalist) { + struct buffer_head *bh; + + jh = commit_transaction->t_sync_datalist; + commit_transaction->t_sync_datalist = jh->b_tnext; + bh = jh2bh(jh); + if (buffer_locked(bh)) { + BUFFER_TRACE(bh, "locked"); + if (!inverted_lock(journal, bh)) + goto write_out_data; + __journal_temp_unlink_buffer(jh); + __journal_file_buffer(jh, commit_transaction, + BJ_Locked); + jbd_unlock_bh_state(bh); + if (lock_need_resched(&journal->j_list_lock)) { + spin_unlock(&journal->j_list_lock); + goto write_out_data; + } + } else { + if (buffer_dirty(bh)) { + BUFFER_TRACE(bh, "start journal writeout"); + get_bh(bh); + wbuf[bufs++] = bh; + if (bufs == journal->j_wbufsize) { + jbd_debug(2, "submit %d writes\n", + bufs); + spin_unlock(&journal->j_list_lock); + ll_rw_block(WRITE, bufs, wbuf); + journal_brelse_array(wbuf, bufs); + bufs = 0; + goto write_out_data; + } + } else { + BUFFER_TRACE(bh, "writeout complete: unfile"); + if (!inverted_lock(journal, bh)) + goto write_out_data; + __journal_unfile_buffer(jh); + jbd_unlock_bh_state(bh); + journal_remove_journal_head(bh); + put_bh(bh); + if (lock_need_resched(&journal->j_list_lock)) { + spin_unlock(&journal->j_list_lock); + goto write_out_data; + } + } + } + } + + if (bufs) { + spin_unlock(&journal->j_list_lock); + ll_rw_block(WRITE, bufs, wbuf); + journal_brelse_array(wbuf, bufs); + spin_lock(&journal->j_list_lock); + } + + /* + * Wait for all previously submitted IO to complete. + */ + while (commit_transaction->t_locked_list) { + struct buffer_head *bh; + + jh = commit_transaction->t_locked_list->b_tprev; + bh = jh2bh(jh); + get_bh(bh); + if (buffer_locked(bh)) { + spin_unlock(&journal->j_list_lock); + wait_on_buffer(bh); + if (unlikely(!buffer_uptodate(bh))) + err = -EIO; + spin_lock(&journal->j_list_lock); + } + if (!inverted_lock(journal, bh)) { + put_bh(bh); + spin_lock(&journal->j_list_lock); + continue; + } + if (buffer_jbd(bh) && jh->b_jlist == BJ_Locked) { + __journal_unfile_buffer(jh); + jbd_unlock_bh_state(bh); + journal_remove_journal_head(bh); + put_bh(bh); + } else { + jbd_unlock_bh_state(bh); + } + put_bh(bh); + cond_resched_lock(&journal->j_list_lock); + } + spin_unlock(&journal->j_list_lock); + + if (err) + __journal_abort_hard(journal); + + journal_write_revoke_records(journal, commit_transaction); + + jbd_debug(3, "JBD: commit phase 2\n"); + + /* + * If we found any dirty or locked buffers, then we should have + * looped back up to the write_out_data label. If there weren't + * any then journal_clean_data_list should have wiped the list + * clean by now, so check that it is in fact empty. + */ + J_ASSERT (commit_transaction->t_sync_datalist == NULL); + + jbd_debug (3, "JBD: commit phase 3\n"); + + /* + * Way to go: we have now written out all of the data for a + * transaction! Now comes the tricky part: we need to write out + * metadata. Loop over the transaction's entire buffer list: + */ + commit_transaction->t_state = T_COMMIT; + + descriptor = NULL; + bufs = 0; + while (commit_transaction->t_buffers) { + + /* Find the next buffer to be journaled... */ + + jh = commit_transaction->t_buffers; + + /* If we're in abort mode, we just un-journal the buffer and + release it for background writing. */ + + if (is_journal_aborted(journal)) { + JBUFFER_TRACE(jh, "journal is aborting: refile"); + journal_refile_buffer(journal, jh); + /* If that was the last one, we need to clean up + * any descriptor buffers which may have been + * already allocated, even if we are now + * aborting. */ + if (!commit_transaction->t_buffers) + goto start_journal_io; + continue; + } + + /* Make sure we have a descriptor block in which to + record the metadata buffer. */ + + if (!descriptor) { + struct buffer_head *bh; + + J_ASSERT (bufs == 0); + + jbd_debug(4, "JBD: get descriptor\n"); + + descriptor = journal_get_descriptor_buffer(journal); + if (!descriptor) { + __journal_abort_hard(journal); + continue; + } + + bh = jh2bh(descriptor); + jbd_debug(4, "JBD: got buffer %llu (%p)\n", + (unsigned long long)bh->b_blocknr, bh->b_data); + header = (journal_header_t *)&bh->b_data[0]; + header->h_magic = cpu_to_be32(JFS_MAGIC_NUMBER); + header->h_blocktype = cpu_to_be32(JFS_DESCRIPTOR_BLOCK); + header->h_sequence = cpu_to_be32(commit_transaction->t_tid); + + tagp = &bh->b_data[sizeof(journal_header_t)]; + space_left = bh->b_size - sizeof(journal_header_t); + first_tag = 1; + set_buffer_jwrite(bh); + set_buffer_dirty(bh); + wbuf[bufs++] = bh; + + /* Record it so that we can wait for IO + completion later */ + BUFFER_TRACE(bh, "ph3: file as descriptor"); + journal_file_buffer(descriptor, commit_transaction, + BJ_LogCtl); + } + + /* Where is the buffer to be written? */ + + err = journal_next_log_block(journal, &blocknr); + /* If the block mapping failed, just abandon the buffer + and repeat this loop: we'll fall into the + refile-on-abort condition above. */ + if (err) { + __journal_abort_hard(journal); + continue; + } + + /* + * start_this_handle() uses t_outstanding_credits to determine + * the free space in the log, but this counter is changed + * by journal_next_log_block() also. + */ + commit_transaction->t_outstanding_credits--; + + /* Bump b_count to prevent truncate from stumbling over + the shadowed buffer! @@@ This can go if we ever get + rid of the BJ_IO/BJ_Shadow pairing of buffers. */ + atomic_inc(&jh2bh(jh)->b_count); + + /* Make a temporary IO buffer with which to write it out + (this will requeue both the metadata buffer and the + temporary IO buffer). new_bh goes on BJ_IO*/ + + set_bit(BH_JWrite, &jh2bh(jh)->b_state); + /* + * akpm: journal_write_metadata_buffer() sets + * new_bh->b_transaction to commit_transaction. + * We need to clean this up before we release new_bh + * (which is of type BJ_IO) + */ + JBUFFER_TRACE(jh, "ph3: write metadata"); + flags = journal_write_metadata_buffer(commit_transaction, + jh, &new_jh, blocknr); + set_bit(BH_JWrite, &jh2bh(new_jh)->b_state); + wbuf[bufs++] = jh2bh(new_jh); + + /* Record the new block's tag in the current descriptor + buffer */ + + tag_flag = 0; + if (flags & 1) + tag_flag |= JFS_FLAG_ESCAPE; + if (!first_tag) + tag_flag |= JFS_FLAG_SAME_UUID; + + tag = (journal_block_tag_t *) tagp; + tag->t_blocknr = cpu_to_be32(jh2bh(jh)->b_blocknr); + tag->t_flags = cpu_to_be32(tag_flag); + tagp += sizeof(journal_block_tag_t); + space_left -= sizeof(journal_block_tag_t); + + if (first_tag) { + memcpy (tagp, journal->j_uuid, 16); + tagp += 16; + space_left -= 16; + first_tag = 0; + } + + /* If there's no more to do, or if the descriptor is full, + let the IO rip! */ + + if (bufs == journal->j_wbufsize || + commit_transaction->t_buffers == NULL || + space_left < sizeof(journal_block_tag_t) + 16) { + + jbd_debug(4, "JBD: Submit %d IOs\n", bufs); + + /* Write an end-of-descriptor marker before + submitting the IOs. "tag" still points to + the last tag we set up. */ + + tag->t_flags |= cpu_to_be32(JFS_FLAG_LAST_TAG); + +start_journal_io: + for (i = 0; i < bufs; i++) { + struct buffer_head *bh = wbuf[i]; + lock_buffer(bh); + clear_buffer_dirty(bh); + set_buffer_uptodate(bh); + bh->b_end_io = journal_end_buffer_io_sync; + submit_bh(WRITE, bh); + } + cond_resched(); + + /* Force a new descriptor to be generated next + time round the loop. */ + descriptor = NULL; + bufs = 0; + } + } + + /* Lo and behold: we have just managed to send a transaction to + the log. Before we can commit it, wait for the IO so far to + complete. Control buffers being written are on the + transaction's t_log_list queue, and metadata buffers are on + the t_iobuf_list queue. + + Wait for the buffers in reverse order. That way we are + less likely to be woken up until all IOs have completed, and + so we incur less scheduling load. + */ + + jbd_debug(3, "JBD: commit phase 4\n"); + + /* + * akpm: these are BJ_IO, and j_list_lock is not needed. + * See __journal_try_to_free_buffer. + */ +wait_for_iobuf: + while (commit_transaction->t_iobuf_list != NULL) { + struct buffer_head *bh; + + jh = commit_transaction->t_iobuf_list->b_tprev; + bh = jh2bh(jh); + if (buffer_locked(bh)) { + wait_on_buffer(bh); + goto wait_for_iobuf; + } + if (cond_resched()) + goto wait_for_iobuf; + + if (unlikely(!buffer_uptodate(bh))) + err = -EIO; + + clear_buffer_jwrite(bh); + + JBUFFER_TRACE(jh, "ph4: unfile after journal write"); + journal_unfile_buffer(journal, jh); + + /* + * ->t_iobuf_list should contain only dummy buffer_heads + * which were created by journal_write_metadata_buffer(). + */ + BUFFER_TRACE(bh, "dumping temporary bh"); + journal_put_journal_head(jh); + __brelse(bh); + J_ASSERT_BH(bh, atomic_read(&bh->b_count) == 0); + free_buffer_head(bh); + + /* We also have to unlock and free the corresponding + shadowed buffer */ + jh = commit_transaction->t_shadow_list->b_tprev; + bh = jh2bh(jh); + clear_bit(BH_JWrite, &bh->b_state); + J_ASSERT_BH(bh, buffer_jbddirty(bh)); + + /* The metadata is now released for reuse, but we need + to remember it against this transaction so that when + we finally commit, we can do any checkpointing + required. */ + JBUFFER_TRACE(jh, "file as BJ_Forget"); + journal_file_buffer(jh, commit_transaction, BJ_Forget); + /* Wake up any transactions which were waiting for this + IO to complete */ + wake_up_bit(&bh->b_state, BH_Unshadow); + JBUFFER_TRACE(jh, "brelse shadowed buffer"); + __brelse(bh); + } + + J_ASSERT (commit_transaction->t_shadow_list == NULL); + + jbd_debug(3, "JBD: commit phase 5\n"); + + /* Here we wait for the revoke record and descriptor record buffers */ + wait_for_ctlbuf: + while (commit_transaction->t_log_list != NULL) { + struct buffer_head *bh; + + jh = commit_transaction->t_log_list->b_tprev; + bh = jh2bh(jh); + if (buffer_locked(bh)) { + wait_on_buffer(bh); + goto wait_for_ctlbuf; + } + if (cond_resched()) + goto wait_for_ctlbuf; + + if (unlikely(!buffer_uptodate(bh))) + err = -EIO; + + BUFFER_TRACE(bh, "ph5: control buffer writeout done: unfile"); + clear_buffer_jwrite(bh); + journal_unfile_buffer(journal, jh); + journal_put_journal_head(jh); + __brelse(bh); /* One for getblk */ + /* AKPM: bforget here */ + } + + jbd_debug(3, "JBD: commit phase 6\n"); + + if (journal_write_commit_record(journal, commit_transaction)) + err = -EIO; + + if (err) + __journal_abort_hard(journal); + + /* End of a transaction! Finally, we can do checkpoint + processing: any buffers committed as a result of this + transaction can be removed from any checkpoint list it was on + before. */ + + jbd_debug(3, "JBD: commit phase 7\n"); + + J_ASSERT(commit_transaction->t_sync_datalist == NULL); + J_ASSERT(commit_transaction->t_buffers == NULL); + J_ASSERT(commit_transaction->t_checkpoint_list == NULL); + J_ASSERT(commit_transaction->t_iobuf_list == NULL); + J_ASSERT(commit_transaction->t_shadow_list == NULL); + J_ASSERT(commit_transaction->t_log_list == NULL); + +restart_loop: + while (commit_transaction->t_forget) { + transaction_t *cp_transaction; + struct buffer_head *bh; + + jh = commit_transaction->t_forget; + bh = jh2bh(jh); + jbd_lock_bh_state(bh); + J_ASSERT_JH(jh, jh->b_transaction == commit_transaction || + jh->b_transaction == journal->j_running_transaction); + + /* + * If there is undo-protected committed data against + * this buffer, then we can remove it now. If it is a + * buffer needing such protection, the old frozen_data + * field now points to a committed version of the + * buffer, so rotate that field to the new committed + * data. + * + * Otherwise, we can just throw away the frozen data now. + */ + if (jh->b_committed_data) { + kfree(jh->b_committed_data); + jh->b_committed_data = NULL; + if (jh->b_frozen_data) { + jh->b_committed_data = jh->b_frozen_data; + jh->b_frozen_data = NULL; + } + } else if (jh->b_frozen_data) { + kfree(jh->b_frozen_data); + jh->b_frozen_data = NULL; + } + + spin_lock(&journal->j_list_lock); + cp_transaction = jh->b_cp_transaction; + if (cp_transaction) { + JBUFFER_TRACE(jh, "remove from old cp transaction"); + __journal_remove_checkpoint(jh); + } + + /* Only re-checkpoint the buffer_head if it is marked + * dirty. If the buffer was added to the BJ_Forget list + * by journal_forget, it may no longer be dirty and + * there's no point in keeping a checkpoint record for + * it. */ + + /* A buffer which has been freed while still being + * journaled by a previous transaction may end up still + * being dirty here, but we want to avoid writing back + * that buffer in the future now that the last use has + * been committed. That's not only a performance gain, + * it also stops aliasing problems if the buffer is left + * behind for writeback and gets reallocated for another + * use in a different page. */ + if (buffer_freed(bh)) { + clear_buffer_freed(bh); + clear_buffer_jbddirty(bh); + } + + if (buffer_jbddirty(bh)) { + JBUFFER_TRACE(jh, "add to new checkpointing trans"); + __journal_insert_checkpoint(jh, commit_transaction); + JBUFFER_TRACE(jh, "refile for checkpoint writeback"); + __journal_refile_buffer(jh); + jbd_unlock_bh_state(bh); + } else { + J_ASSERT_BH(bh, !buffer_dirty(bh)); + J_ASSERT_JH(jh, jh->b_next_transaction == NULL); + __journal_unfile_buffer(jh); + jbd_unlock_bh_state(bh); + journal_remove_journal_head(bh); /* needs a brelse */ + release_buffer_page(bh); + } + spin_unlock(&journal->j_list_lock); + if (cond_resched()) + goto restart_loop; + } + + /* Done with this transaction! */ + + jbd_debug(3, "JBD: commit phase 8\n"); + + J_ASSERT(commit_transaction->t_state == T_COMMIT); + + /* + * This is a bit sleazy. We borrow j_list_lock to protect + * journal->j_committing_transaction in __journal_remove_checkpoint. + * Really, __jornal_remove_checkpoint should be using j_state_lock but + * it's a bit hassle to hold that across __journal_remove_checkpoint + */ + spin_lock(&journal->j_state_lock); + spin_lock(&journal->j_list_lock); + commit_transaction->t_state = T_FINISHED; + J_ASSERT(commit_transaction == journal->j_committing_transaction); + journal->j_commit_sequence = commit_transaction->t_tid; + journal->j_committing_transaction = NULL; + spin_unlock(&journal->j_state_lock); + + if (commit_transaction->t_checkpoint_list == NULL) { + __journal_drop_transaction(journal, commit_transaction); + } else { + if (journal->j_checkpoint_transactions == NULL) { + journal->j_checkpoint_transactions = commit_transaction; + commit_transaction->t_cpnext = commit_transaction; + commit_transaction->t_cpprev = commit_transaction; + } else { + commit_transaction->t_cpnext = + journal->j_checkpoint_transactions; + commit_transaction->t_cpprev = + commit_transaction->t_cpnext->t_cpprev; + commit_transaction->t_cpnext->t_cpprev = + commit_transaction; + commit_transaction->t_cpprev->t_cpnext = + commit_transaction; + } + } + spin_unlock(&journal->j_list_lock); + + jbd_debug(1, "JBD: commit %d complete, head %d\n", + journal->j_commit_sequence, journal->j_tail_sequence); + + wake_up(&journal->j_wait_done_commit); +} diff --git a/fs/jbd/journal.c b/fs/jbd/journal.c new file mode 100644 index 00000000000..1e6f2e2ad4a --- /dev/null +++ b/fs/jbd/journal.c @@ -0,0 +1,2003 @@ +/* + * linux/fs/journal.c + * + * Written by Stephen C. Tweedie <sct@redhat.com>, 1998 + * + * Copyright 1998 Red Hat corp --- All Rights Reserved + * + * This file is part of the Linux kernel and is made available under + * the terms of the GNU General Public License, version 2, or at your + * option, any later version, incorporated herein by reference. + * + * Generic filesystem journal-writing code; part of the ext2fs + * journaling system. + * + * This file manages journals: areas of disk reserved for logging + * transactional updates. This includes the kernel journaling thread + * which is responsible for scheduling updates to the log. + * + * We do not actually manage the physical storage of the journal in this + * file: that is left to a per-journal policy function, which allows us + * to store the journal within a filesystem-specified area for ext2 + * journaling (ext2 can use a reserved inode for storing the log). + */ + +#include <linux/module.h> +#include <linux/time.h> +#include <linux/fs.h> +#include <linux/jbd.h> +#include <linux/errno.h> +#include <linux/slab.h> +#include <linux/smp_lock.h> +#include <linux/init.h> +#include <linux/mm.h> +#include <linux/suspend.h> +#include <linux/pagemap.h> +#include <asm/uaccess.h> +#include <asm/page.h> +#include <linux/proc_fs.h> + +EXPORT_SYMBOL(journal_start); +EXPORT_SYMBOL(journal_restart); +EXPORT_SYMBOL(journal_extend); +EXPORT_SYMBOL(journal_stop); +EXPORT_SYMBOL(journal_lock_updates); +EXPORT_SYMBOL(journal_unlock_updates); +EXPORT_SYMBOL(journal_get_write_access); +EXPORT_SYMBOL(journal_get_create_access); +EXPORT_SYMBOL(journal_get_undo_access); +EXPORT_SYMBOL(journal_dirty_data); +EXPORT_SYMBOL(journal_dirty_metadata); +EXPORT_SYMBOL(journal_release_buffer); +EXPORT_SYMBOL(journal_forget); +#if 0 +EXPORT_SYMBOL(journal_sync_buffer); +#endif +EXPORT_SYMBOL(journal_flush); +EXPORT_SYMBOL(journal_revoke); + +EXPORT_SYMBOL(journal_init_dev); +EXPORT_SYMBOL(journal_init_inode); +EXPORT_SYMBOL(journal_update_format); +EXPORT_SYMBOL(journal_check_used_features); +EXPORT_SYMBOL(journal_check_available_features); +EXPORT_SYMBOL(journal_set_features); +EXPORT_SYMBOL(journal_create); +EXPORT_SYMBOL(journal_load); +EXPORT_SYMBOL(journal_destroy); +EXPORT_SYMBOL(journal_recover); +EXPORT_SYMBOL(journal_update_superblock); +EXPORT_SYMBOL(journal_abort); +EXPORT_SYMBOL(journal_errno); +EXPORT_SYMBOL(journal_ack_err); +EXPORT_SYMBOL(journal_clear_err); +EXPORT_SYMBOL(log_wait_commit); +EXPORT_SYMBOL(journal_start_commit); +EXPORT_SYMBOL(journal_force_commit_nested); +EXPORT_SYMBOL(journal_wipe); +EXPORT_SYMBOL(journal_blocks_per_page); +EXPORT_SYMBOL(journal_invalidatepage); +EXPORT_SYMBOL(journal_try_to_free_buffers); +EXPORT_SYMBOL(journal_force_commit); + +static int journal_convert_superblock_v1(journal_t *, journal_superblock_t *); + +/* + * Helper function used to manage commit timeouts + */ + +static void commit_timeout(unsigned long __data) +{ + struct task_struct * p = (struct task_struct *) __data; + + wake_up_process(p); +} + +/* Static check for data structure consistency. There's no code + * invoked --- we'll just get a linker failure if things aren't right. + */ +void __journal_internal_check(void) +{ + extern void journal_bad_superblock_size(void); + if (sizeof(struct journal_superblock_s) != 1024) + journal_bad_superblock_size(); +} + +/* + * kjournald: The main thread function used to manage a logging device + * journal. + * + * This kernel thread is responsible for two things: + * + * 1) COMMIT: Every so often we need to commit the current state of the + * filesystem to disk. The journal thread is responsible for writing + * all of the metadata buffers to disk. + * + * 2) CHECKPOINT: We cannot reuse a used section of the log file until all + * of the data in that part of the log has been rewritten elsewhere on + * the disk. Flushing these old buffers to reclaim space in the log is + * known as checkpointing, and this thread is responsible for that job. + */ + +journal_t *current_journal; // AKPM: debug + +int kjournald(void *arg) +{ + journal_t *journal = (journal_t *) arg; + transaction_t *transaction; + struct timer_list timer; + + current_journal = journal; + + daemonize("kjournald"); + + /* Set up an interval timer which can be used to trigger a + commit wakeup after the commit interval expires */ + init_timer(&timer); + timer.data = (unsigned long) current; + timer.function = commit_timeout; + journal->j_commit_timer = &timer; + + /* Record that the journal thread is running */ + journal->j_task = current; + wake_up(&journal->j_wait_done_commit); + + printk(KERN_INFO "kjournald starting. Commit interval %ld seconds\n", + journal->j_commit_interval / HZ); + + /* + * And now, wait forever for commit wakeup events. + */ + spin_lock(&journal->j_state_lock); + +loop: + if (journal->j_flags & JFS_UNMOUNT) + goto end_loop; + + jbd_debug(1, "commit_sequence=%d, commit_request=%d\n", + journal->j_commit_sequence, journal->j_commit_request); + + if (journal->j_commit_sequence != journal->j_commit_request) { + jbd_debug(1, "OK, requests differ\n"); + spin_unlock(&journal->j_state_lock); + del_timer_sync(journal->j_commit_timer); + journal_commit_transaction(journal); + spin_lock(&journal->j_state_lock); + goto loop; + } + + wake_up(&journal->j_wait_done_commit); + if (current->flags & PF_FREEZE) { + /* + * The simpler the better. Flushing journal isn't a + * good idea, because that depends on threads that may + * be already stopped. + */ + jbd_debug(1, "Now suspending kjournald\n"); + spin_unlock(&journal->j_state_lock); + refrigerator(PF_FREEZE); + spin_lock(&journal->j_state_lock); + } else { + /* + * We assume on resume that commits are already there, + * so we don't sleep + */ + DEFINE_WAIT(wait); + int should_sleep = 1; + + prepare_to_wait(&journal->j_wait_commit, &wait, + TASK_INTERRUPTIBLE); + if (journal->j_commit_sequence != journal->j_commit_request) + should_sleep = 0; + transaction = journal->j_running_transaction; + if (transaction && time_after_eq(jiffies, + transaction->t_expires)) + should_sleep = 0; + if (should_sleep) { + spin_unlock(&journal->j_state_lock); + schedule(); + spin_lock(&journal->j_state_lock); + } + finish_wait(&journal->j_wait_commit, &wait); + } + + jbd_debug(1, "kjournald wakes\n"); + + /* + * Were we woken up by a commit wakeup event? + */ + transaction = journal->j_running_transaction; + if (transaction && time_after_eq(jiffies, transaction->t_expires)) { + journal->j_commit_request = transaction->t_tid; + jbd_debug(1, "woke because of timeout\n"); + } + goto loop; + +end_loop: + spin_unlock(&journal->j_state_lock); + del_timer_sync(journal->j_commit_timer); + journal->j_task = NULL; + wake_up(&journal->j_wait_done_commit); + jbd_debug(1, "Journal thread exiting.\n"); + return 0; +} + +static void journal_start_thread(journal_t *journal) +{ + kernel_thread(kjournald, journal, CLONE_VM|CLONE_FS|CLONE_FILES); + wait_event(journal->j_wait_done_commit, journal->j_task != 0); +} + +static void journal_kill_thread(journal_t *journal) +{ + spin_lock(&journal->j_state_lock); + journal->j_flags |= JFS_UNMOUNT; + + while (journal->j_task) { + wake_up(&journal->j_wait_commit); + spin_unlock(&journal->j_state_lock); + wait_event(journal->j_wait_done_commit, journal->j_task == 0); + spin_lock(&journal->j_state_lock); + } + spin_unlock(&journal->j_state_lock); +} + +/* + * journal_write_metadata_buffer: write a metadata buffer to the journal. + * + * Writes a metadata buffer to a given disk block. The actual IO is not + * performed but a new buffer_head is constructed which labels the data + * to be written with the correct destination disk block. + * + * Any magic-number escaping which needs to be done will cause a + * copy-out here. If the buffer happens to start with the + * JFS_MAGIC_NUMBER, then we can't write it to the log directly: the + * magic number is only written to the log for descripter blocks. In + * this case, we copy the data and replace the first word with 0, and we + * return a result code which indicates that this buffer needs to be + * marked as an escaped buffer in the corresponding log descriptor + * block. The missing word can then be restored when the block is read + * during recovery. + * + * If the source buffer has already been modified by a new transaction + * since we took the last commit snapshot, we use the frozen copy of + * that data for IO. If we end up using the existing buffer_head's data + * for the write, then we *have* to lock the buffer to prevent anyone + * else from using and possibly modifying it while the IO is in + * progress. + * + * The function returns a pointer to the buffer_heads to be used for IO. + * + * We assume that the journal has already been locked in this function. + * + * Return value: + * <0: Error + * >=0: Finished OK + * + * On success: + * Bit 0 set == escape performed on the data + * Bit 1 set == buffer copy-out performed (kfree the data after IO) + */ + +int journal_write_metadata_buffer(transaction_t *transaction, + struct journal_head *jh_in, + struct journal_head **jh_out, + int blocknr) +{ + int need_copy_out = 0; + int done_copy_out = 0; + int do_escape = 0; + char *mapped_data; + struct buffer_head *new_bh; + struct journal_head *new_jh; + struct page *new_page; + unsigned int new_offset; + struct buffer_head *bh_in = jh2bh(jh_in); + + /* + * The buffer really shouldn't be locked: only the current committing + * transaction is allowed to write it, so nobody else is allowed + * to do any IO. + * + * akpm: except if we're journalling data, and write() output is + * also part of a shared mapping, and another thread has + * decided to launch a writepage() against this buffer. + */ + J_ASSERT_BH(bh_in, buffer_jbddirty(bh_in)); + + new_bh = alloc_buffer_head(GFP_NOFS|__GFP_NOFAIL); + + /* + * If a new transaction has already done a buffer copy-out, then + * we use that version of the data for the commit. + */ + jbd_lock_bh_state(bh_in); +repeat: + if (jh_in->b_frozen_data) { + done_copy_out = 1; + new_page = virt_to_page(jh_in->b_frozen_data); + new_offset = offset_in_page(jh_in->b_frozen_data); + } else { + new_page = jh2bh(jh_in)->b_page; + new_offset = offset_in_page(jh2bh(jh_in)->b_data); + } + + mapped_data = kmap_atomic(new_page, KM_USER0); + /* + * Check for escaping + */ + if (*((__be32 *)(mapped_data + new_offset)) == + cpu_to_be32(JFS_MAGIC_NUMBER)) { + need_copy_out = 1; + do_escape = 1; + } + kunmap_atomic(mapped_data, KM_USER0); + + /* + * Do we need to do a data copy? + */ + if (need_copy_out && !done_copy_out) { + char *tmp; + + jbd_unlock_bh_state(bh_in); + tmp = jbd_rep_kmalloc(bh_in->b_size, GFP_NOFS); + jbd_lock_bh_state(bh_in); + if (jh_in->b_frozen_data) { + kfree(tmp); + goto repeat; + } + + jh_in->b_frozen_data = tmp; + mapped_data = kmap_atomic(new_page, KM_USER0); + memcpy(tmp, mapped_data + new_offset, jh2bh(jh_in)->b_size); + kunmap_atomic(mapped_data, KM_USER0); + + new_page = virt_to_page(tmp); + new_offset = offset_in_page(tmp); + done_copy_out = 1; + } + + /* + * Did we need to do an escaping? Now we've done all the + * copying, we can finally do so. + */ + if (do_escape) { + mapped_data = kmap_atomic(new_page, KM_USER0); + *((unsigned int *)(mapped_data + new_offset)) = 0; + kunmap_atomic(mapped_data, KM_USER0); + } + + /* keep subsequent assertions sane */ + new_bh->b_state = 0; + init_buffer(new_bh, NULL, NULL); + atomic_set(&new_bh->b_count, 1); + jbd_unlock_bh_state(bh_in); + + new_jh = journal_add_journal_head(new_bh); /* This sleeps */ + + set_bh_page(new_bh, new_page, new_offset); + new_jh->b_transaction = NULL; + new_bh->b_size = jh2bh(jh_in)->b_size; + new_bh->b_bdev = transaction->t_journal->j_dev; + new_bh->b_blocknr = blocknr; + set_buffer_mapped(new_bh); + set_buffer_dirty(new_bh); + + *jh_out = new_jh; + + /* + * The to-be-written buffer needs to get moved to the io queue, + * and the original buffer whose contents we are shadowing or + * copying is moved to the transaction's shadow queue. + */ + JBUFFER_TRACE(jh_in, "file as BJ_Shadow"); + journal_file_buffer(jh_in, transaction, BJ_Shadow); + JBUFFER_TRACE(new_jh, "file as BJ_IO"); + journal_file_buffer(new_jh, transaction, BJ_IO); + + return do_escape | (done_copy_out << 1); +} + +/* + * Allocation code for the journal file. Manage the space left in the + * journal, so that we can begin checkpointing when appropriate. + */ + +/* + * __log_space_left: Return the number of free blocks left in the journal. + * + * Called with the journal already locked. + * + * Called under j_state_lock + */ + +int __log_space_left(journal_t *journal) +{ + int left = journal->j_free; + + assert_spin_locked(&journal->j_state_lock); + + /* + * Be pessimistic here about the number of those free blocks which + * might be required for log descriptor control blocks. + */ + +#define MIN_LOG_RESERVED_BLOCKS 32 /* Allow for rounding errors */ + + left -= MIN_LOG_RESERVED_BLOCKS; + + if (left <= 0) + return 0; + left -= (left >> 3); + return left; +} + +/* + * Called under j_state_lock. Returns true if a transaction was started. + */ +int __log_start_commit(journal_t *journal, tid_t target) +{ + /* + * Are we already doing a recent enough commit? + */ + if (!tid_geq(journal->j_commit_request, target)) { + /* + * We want a new commit: OK, mark the request and wakup the + * commit thread. We do _not_ do the commit ourselves. + */ + + journal->j_commit_request = target; + jbd_debug(1, "JBD: requesting commit %d/%d\n", + journal->j_commit_request, + journal->j_commit_sequence); + wake_up(&journal->j_wait_commit); + return 1; + } + return 0; +} + +int log_start_commit(journal_t *journal, tid_t tid) +{ + int ret; + + spin_lock(&journal->j_state_lock); + ret = __log_start_commit(journal, tid); + spin_unlock(&journal->j_state_lock); + return ret; +} + +/* + * Force and wait upon a commit if the calling process is not within + * transaction. This is used for forcing out undo-protected data which contains + * bitmaps, when the fs is running out of space. + * + * We can only force the running transaction if we don't have an active handle; + * otherwise, we will deadlock. + * + * Returns true if a transaction was started. + */ +int journal_force_commit_nested(journal_t *journal) +{ + transaction_t *transaction = NULL; + tid_t tid; + + spin_lock(&journal->j_state_lock); + if (journal->j_running_transaction && !current->journal_info) { + transaction = journal->j_running_transaction; + __log_start_commit(journal, transaction->t_tid); + } else if (journal->j_committing_transaction) + transaction = journal->j_committing_transaction; + + if (!transaction) { + spin_unlock(&journal->j_state_lock); + return 0; /* Nothing to retry */ + } + + tid = transaction->t_tid; + spin_unlock(&journal->j_state_lock); + log_wait_commit(journal, tid); + return 1; +} + +/* + * Start a commit of the current running transaction (if any). Returns true + * if a transaction was started, and fills its tid in at *ptid + */ +int journal_start_commit(journal_t *journal, tid_t *ptid) +{ + int ret = 0; + + spin_lock(&journal->j_state_lock); + if (journal->j_running_transaction) { + tid_t tid = journal->j_running_transaction->t_tid; + + ret = __log_start_commit(journal, tid); + if (ret && ptid) + *ptid = tid; + } else if (journal->j_committing_transaction && ptid) { + /* + * If ext3_write_super() recently started a commit, then we + * have to wait for completion of that transaction + */ + *ptid = journal->j_committing_transaction->t_tid; + ret = 1; + } + spin_unlock(&journal->j_state_lock); + return ret; +} + +/* + * Wait for a specified commit to complete. + * The caller may not hold the journal lock. + */ +int log_wait_commit(journal_t *journal, tid_t tid) +{ + int err = 0; + +#ifdef CONFIG_JBD_DEBUG + spin_lock(&journal->j_state_lock); + if (!tid_geq(journal->j_commit_request, tid)) { + printk(KERN_EMERG + "%s: error: j_commit_request=%d, tid=%d\n", + __FUNCTION__, journal->j_commit_request, tid); + } + spin_unlock(&journal->j_state_lock); +#endif + spin_lock(&journal->j_state_lock); + while (tid_gt(tid, journal->j_commit_sequence)) { + jbd_debug(1, "JBD: want %d, j_commit_sequence=%d\n", + tid, journal->j_commit_sequence); + wake_up(&journal->j_wait_commit); + spin_unlock(&journal->j_state_lock); + wait_event(journal->j_wait_done_commit, + !tid_gt(tid, journal->j_commit_sequence)); + spin_lock(&journal->j_state_lock); + } + spin_unlock(&journal->j_state_lock); + + if (unlikely(is_journal_aborted(journal))) { + printk(KERN_EMERG "journal commit I/O error\n"); + err = -EIO; + } + return err; +} + +/* + * Log buffer allocation routines: + */ + +int journal_next_log_block(journal_t *journal, unsigned long *retp) +{ + unsigned long blocknr; + + spin_lock(&journal->j_state_lock); + J_ASSERT(journal->j_free > 1); + + blocknr = journal->j_head; + journal->j_head++; + journal->j_free--; + if (journal->j_head == journal->j_last) + journal->j_head = journal->j_first; + spin_unlock(&journal->j_state_lock); + return journal_bmap(journal, blocknr, retp); +} + +/* + * Conversion of logical to physical block numbers for the journal + * + * On external journals the journal blocks are identity-mapped, so + * this is a no-op. If needed, we can use j_blk_offset - everything is + * ready. + */ +int journal_bmap(journal_t *journal, unsigned long blocknr, + unsigned long *retp) +{ + int err = 0; + unsigned long ret; + + if (journal->j_inode) { + ret = bmap(journal->j_inode, blocknr); + if (ret) + *retp = ret; + else { + char b[BDEVNAME_SIZE]; + + printk(KERN_ALERT "%s: journal block not found " + "at offset %lu on %s\n", + __FUNCTION__, + blocknr, + bdevname(journal->j_dev, b)); + err = -EIO; + __journal_abort_soft(journal, err); + } + } else { + *retp = blocknr; /* +journal->j_blk_offset */ + } + return err; +} + +/* + * We play buffer_head aliasing tricks to write data/metadata blocks to + * the journal without copying their contents, but for journal + * descriptor blocks we do need to generate bona fide buffers. + * + * After the caller of journal_get_descriptor_buffer() has finished modifying + * the buffer's contents they really should run flush_dcache_page(bh->b_page). + * But we don't bother doing that, so there will be coherency problems with + * mmaps of blockdevs which hold live JBD-controlled filesystems. + */ +struct journal_head *journal_get_descriptor_buffer(journal_t *journal) +{ + struct buffer_head *bh; + unsigned long blocknr; + int err; + + err = journal_next_log_block(journal, &blocknr); + + if (err) + return NULL; + + bh = __getblk(journal->j_dev, blocknr, journal->j_blocksize); + lock_buffer(bh); + memset(bh->b_data, 0, journal->j_blocksize); + set_buffer_uptodate(bh); + unlock_buffer(bh); + BUFFER_TRACE(bh, "return this buffer"); + return journal_add_journal_head(bh); +} + +/* + * Management for journal control blocks: functions to create and + * destroy journal_t structures, and to initialise and read existing + * journal blocks from disk. */ + +/* First: create and setup a journal_t object in memory. We initialise + * very few fields yet: that has to wait until we have created the + * journal structures from from scratch, or loaded them from disk. */ + +static journal_t * journal_init_common (void) +{ + journal_t *journal; + int err; + + journal = jbd_kmalloc(sizeof(*journal), GFP_KERNEL); + if (!journal) + goto fail; + memset(journal, 0, sizeof(*journal)); + + init_waitqueue_head(&journal->j_wait_transaction_locked); + init_waitqueue_head(&journal->j_wait_logspace); + init_waitqueue_head(&journal->j_wait_done_commit); + init_waitqueue_head(&journal->j_wait_checkpoint); + init_waitqueue_head(&journal->j_wait_commit); + init_waitqueue_head(&journal->j_wait_updates); + init_MUTEX(&journal->j_barrier); + init_MUTEX(&journal->j_checkpoint_sem); + spin_lock_init(&journal->j_revoke_lock); + spin_lock_init(&journal->j_list_lock); + spin_lock_init(&journal->j_state_lock); + + journal->j_commit_interval = (HZ * JBD_DEFAULT_MAX_COMMIT_AGE); + + /* The journal is marked for error until we succeed with recovery! */ + journal->j_flags = JFS_ABORT; + + /* Set up a default-sized revoke table for the new mount. */ + err = journal_init_revoke(journal, JOURNAL_REVOKE_DEFAULT_HASH); + if (err) { + kfree(journal); + goto fail; + } + return journal; +fail: + return NULL; +} + +/* journal_init_dev and journal_init_inode: + * + * Create a journal structure assigned some fixed set of disk blocks to + * the journal. We don't actually touch those disk blocks yet, but we + * need to set up all of the mapping information to tell the journaling + * system where the journal blocks are. + * + */ + +/** + * journal_t * journal_init_dev() - creates an initialises a journal structure + * @bdev: Block device on which to create the journal + * @fs_dev: Device which hold journalled filesystem for this journal. + * @start: Block nr Start of journal. + * @len: Lenght of the journal in blocks. + * @blocksize: blocksize of journalling device + * @returns: a newly created journal_t * + * + * journal_init_dev creates a journal which maps a fixed contiguous + * range of blocks on an arbitrary block device. + * + */ +journal_t * journal_init_dev(struct block_device *bdev, + struct block_device *fs_dev, + int start, int len, int blocksize) +{ + journal_t *journal = journal_init_common(); + struct buffer_head *bh; + int n; + + if (!journal) + return NULL; + + journal->j_dev = bdev; + journal->j_fs_dev = fs_dev; + journal->j_blk_offset = start; + journal->j_maxlen = len; + journal->j_blocksize = blocksize; + + bh = __getblk(journal->j_dev, start, journal->j_blocksize); + J_ASSERT(bh != NULL); + journal->j_sb_buffer = bh; + journal->j_superblock = (journal_superblock_t *)bh->b_data; + + /* journal descriptor can store up to n blocks -bzzz */ + n = journal->j_blocksize / sizeof(journal_block_tag_t); + journal->j_wbufsize = n; + journal->j_wbuf = kmalloc(n * sizeof(struct buffer_head*), GFP_KERNEL); + if (!journal->j_wbuf) { + printk(KERN_ERR "%s: Cant allocate bhs for commit thread\n", + __FUNCTION__); + kfree(journal); + journal = NULL; + } + + return journal; +} + +/** + * journal_t * journal_init_inode () - creates a journal which maps to a inode. + * @inode: An inode to create the journal in + * + * journal_init_inode creates a journal which maps an on-disk inode as + * the journal. The inode must exist already, must support bmap() and + * must have all data blocks preallocated. + */ +journal_t * journal_init_inode (struct inode *inode) +{ + struct buffer_head *bh; + journal_t *journal = journal_init_common(); + int err; + int n; + unsigned long blocknr; + + if (!journal) + return NULL; + + journal->j_dev = journal->j_fs_dev = inode->i_sb->s_bdev; + journal->j_inode = inode; + jbd_debug(1, + "journal %p: inode %s/%ld, size %Ld, bits %d, blksize %ld\n", + journal, inode->i_sb->s_id, inode->i_ino, + (long long) inode->i_size, + inode->i_sb->s_blocksize_bits, inode->i_sb->s_blocksize); + + journal->j_maxlen = inode->i_size >> inode->i_sb->s_blocksize_bits; + journal->j_blocksize = inode->i_sb->s_blocksize; + + /* journal descriptor can store up to n blocks -bzzz */ + n = journal->j_blocksize / sizeof(journal_block_tag_t); + journal->j_wbufsize = n; + journal->j_wbuf = kmalloc(n * sizeof(struct buffer_head*), GFP_KERNEL); + if (!journal->j_wbuf) { + printk(KERN_ERR "%s: Cant allocate bhs for commit thread\n", + __FUNCTION__); + kfree(journal); + return NULL; + } + + err = journal_bmap(journal, 0, &blocknr); + /* If that failed, give up */ + if (err) { + printk(KERN_ERR "%s: Cannnot locate journal superblock\n", + __FUNCTION__); + kfree(journal); + return NULL; + } + + bh = __getblk(journal->j_dev, blocknr, journal->j_blocksize); + J_ASSERT(bh != NULL); + journal->j_sb_buffer = bh; + journal->j_superblock = (journal_superblock_t *)bh->b_data; + + return journal; +} + +/* + * If the journal init or create aborts, we need to mark the journal + * superblock as being NULL to prevent the journal destroy from writing + * back a bogus superblock. + */ +static void journal_fail_superblock (journal_t *journal) +{ + struct buffer_head *bh = journal->j_sb_buffer; + brelse(bh); + journal->j_sb_buffer = NULL; +} + +/* + * Given a journal_t structure, initialise the various fields for + * startup of a new journaling session. We use this both when creating + * a journal, and after recovering an old journal to reset it for + * subsequent use. + */ + +static int journal_reset(journal_t *journal) +{ + journal_superblock_t *sb = journal->j_superblock; + unsigned int first, last; + + first = be32_to_cpu(sb->s_first); + last = be32_to_cpu(sb->s_maxlen); + + journal->j_first = first; + journal->j_last = last; + + journal->j_head = first; + journal->j_tail = first; + journal->j_free = last - first; + + journal->j_tail_sequence = journal->j_transaction_sequence; + journal->j_commit_sequence = journal->j_transaction_sequence - 1; + journal->j_commit_request = journal->j_commit_sequence; + + journal->j_max_transaction_buffers = journal->j_maxlen / 4; + + /* Add the dynamic fields and write it to disk. */ + journal_update_superblock(journal, 1); + journal_start_thread(journal); + return 0; +} + +/** + * int journal_create() - Initialise the new journal file + * @journal: Journal to create. This structure must have been initialised + * + * Given a journal_t structure which tells us which disk blocks we can + * use, create a new journal superblock and initialise all of the + * journal fields from scratch. + **/ +int journal_create(journal_t *journal) +{ + unsigned long blocknr; + struct buffer_head *bh; + journal_superblock_t *sb; + int i, err; + + if (journal->j_maxlen < JFS_MIN_JOURNAL_BLOCKS) { + printk (KERN_ERR "Journal length (%d blocks) too short.\n", + journal->j_maxlen); + journal_fail_superblock(journal); + return -EINVAL; + } + + if (journal->j_inode == NULL) { + /* + * We don't know what block to start at! + */ + printk(KERN_EMERG + "%s: creation of journal on external device!\n", + __FUNCTION__); + BUG(); + } + + /* Zero out the entire journal on disk. We cannot afford to + have any blocks on disk beginning with JFS_MAGIC_NUMBER. */ + jbd_debug(1, "JBD: Zeroing out journal blocks...\n"); + for (i = 0; i < journal->j_maxlen; i++) { + err = journal_bmap(journal, i, &blocknr); + if (err) + return err; + bh = __getblk(journal->j_dev, blocknr, journal->j_blocksize); + lock_buffer(bh); + memset (bh->b_data, 0, journal->j_blocksize); + BUFFER_TRACE(bh, "marking dirty"); + mark_buffer_dirty(bh); + BUFFER_TRACE(bh, "marking uptodate"); + set_buffer_uptodate(bh); + unlock_buffer(bh); + __brelse(bh); + } + + sync_blockdev(journal->j_dev); + jbd_debug(1, "JBD: journal cleared.\n"); + + /* OK, fill in the initial static fields in the new superblock */ + sb = journal->j_superblock; + + sb->s_header.h_magic = cpu_to_be32(JFS_MAGIC_NUMBER); + sb->s_header.h_blocktype = cpu_to_be32(JFS_SUPERBLOCK_V2); + + sb->s_blocksize = cpu_to_be32(journal->j_blocksize); + sb->s_maxlen = cpu_to_be32(journal->j_maxlen); + sb->s_first = cpu_to_be32(1); + + journal->j_transaction_sequence = 1; + + journal->j_flags &= ~JFS_ABORT; + journal->j_format_version = 2; + + return journal_reset(journal); +} + +/** + * void journal_update_superblock() - Update journal sb on disk. + * @journal: The journal to update. + * @wait: Set to '0' if you don't want to wait for IO completion. + * + * Update a journal's dynamic superblock fields and write it to disk, + * optionally waiting for the IO to complete. + */ +void journal_update_superblock(journal_t *journal, int wait) +{ + journal_superblock_t *sb = journal->j_superblock; + struct buffer_head *bh = journal->j_sb_buffer; + + /* + * As a special case, if the on-disk copy is already marked as needing + * no recovery (s_start == 0) and there are no outstanding transactions + * in the filesystem, then we can safely defer the superblock update + * until the next commit by setting JFS_FLUSHED. This avoids + * attempting a write to a potential-readonly device. + */ + if (sb->s_start == 0 && journal->j_tail_sequence == + journal->j_transaction_sequence) { + jbd_debug(1,"JBD: Skipping superblock update on recovered sb " + "(start %ld, seq %d, errno %d)\n", + journal->j_tail, journal->j_tail_sequence, + journal->j_errno); + goto out; + } + + spin_lock(&journal->j_state_lock); + jbd_debug(1,"JBD: updating superblock (start %ld, seq %d, errno %d)\n", + journal->j_tail, journal->j_tail_sequence, journal->j_errno); + + sb->s_sequence = cpu_to_be32(journal->j_tail_sequence); + sb->s_start = cpu_to_be32(journal->j_tail); + sb->s_errno = cpu_to_be32(journal->j_errno); + spin_unlock(&journal->j_state_lock); + + BUFFER_TRACE(bh, "marking dirty"); + mark_buffer_dirty(bh); + if (wait) + sync_dirty_buffer(bh); + else + ll_rw_block(WRITE, 1, &bh); + +out: + /* If we have just flushed the log (by marking s_start==0), then + * any future commit will have to be careful to update the + * superblock again to re-record the true start of the log. */ + + spin_lock(&journal->j_state_lock); + if (sb->s_start) + journal->j_flags &= ~JFS_FLUSHED; + else + journal->j_flags |= JFS_FLUSHED; + spin_unlock(&journal->j_state_lock); +} + +/* + * Read the superblock for a given journal, performing initial + * validation of the format. + */ + +static int journal_get_superblock(journal_t *journal) +{ + struct buffer_head *bh; + journal_superblock_t *sb; + int err = -EIO; + + bh = journal->j_sb_buffer; + + J_ASSERT(bh != NULL); + if (!buffer_uptodate(bh)) { + ll_rw_block(READ, 1, &bh); + wait_on_buffer(bh); + if (!buffer_uptodate(bh)) { + printk (KERN_ERR + "JBD: IO error reading journal superblock\n"); + goto out; + } + } + + sb = journal->j_superblock; + + err = -EINVAL; + + if (sb->s_header.h_magic != cpu_to_be32(JFS_MAGIC_NUMBER) || + sb->s_blocksize != cpu_to_be32(journal->j_blocksize)) { + printk(KERN_WARNING "JBD: no valid journal superblock found\n"); + goto out; + } + + switch(be32_to_cpu(sb->s_header.h_blocktype)) { + case JFS_SUPERBLOCK_V1: + journal->j_format_version = 1; + break; + case JFS_SUPERBLOCK_V2: + journal->j_format_version = 2; + break; + default: + printk(KERN_WARNING "JBD: unrecognised superblock format ID\n"); + goto out; + } + + if (be32_to_cpu(sb->s_maxlen) < journal->j_maxlen) + journal->j_maxlen = be32_to_cpu(sb->s_maxlen); + else if (be32_to_cpu(sb->s_maxlen) > journal->j_maxlen) { + printk (KERN_WARNING "JBD: journal file too short\n"); + goto out; + } + + return 0; + +out: + journal_fail_superblock(journal); + return err; +} + +/* + * Load the on-disk journal superblock and read the key fields into the + * journal_t. + */ + +static int load_superblock(journal_t *journal) +{ + int err; + journal_superblock_t *sb; + + err = journal_get_superblock(journal); + if (err) + return err; + + sb = journal->j_superblock; + + journal->j_tail_sequence = be32_to_cpu(sb->s_sequence); + journal->j_tail = be32_to_cpu(sb->s_start); + journal->j_first = be32_to_cpu(sb->s_first); + journal->j_last = be32_to_cpu(sb->s_maxlen); + journal->j_errno = be32_to_cpu(sb->s_errno); + + return 0; +} + + +/** + * int journal_load() - Read journal from disk. + * @journal: Journal to act on. + * + * Given a journal_t structure which tells us which disk blocks contain + * a journal, read the journal from disk to initialise the in-memory + * structures. + */ +int journal_load(journal_t *journal) +{ + int err; + + err = load_superblock(journal); + if (err) + return err; + + /* If this is a V2 superblock, then we have to check the + * features flags on it. */ + + if (journal->j_format_version >= 2) { + journal_superblock_t *sb = journal->j_superblock; + + if ((sb->s_feature_ro_compat & + ~cpu_to_be32(JFS_KNOWN_ROCOMPAT_FEATURES)) || + (sb->s_feature_incompat & + ~cpu_to_be32(JFS_KNOWN_INCOMPAT_FEATURES))) { + printk (KERN_WARNING + "JBD: Unrecognised features on journal\n"); + return -EINVAL; + } + } + + /* Let the recovery code check whether it needs to recover any + * data from the journal. */ + if (journal_recover(journal)) + goto recovery_error; + + /* OK, we've finished with the dynamic journal bits: + * reinitialise the dynamic contents of the superblock in memory + * and reset them on disk. */ + if (journal_reset(journal)) + goto recovery_error; + + journal->j_flags &= ~JFS_ABORT; + journal->j_flags |= JFS_LOADED; + return 0; + +recovery_error: + printk (KERN_WARNING "JBD: recovery failed\n"); + return -EIO; +} + +/** + * void journal_destroy() - Release a journal_t structure. + * @journal: Journal to act on. + * + * Release a journal_t structure once it is no longer in use by the + * journaled object. + */ +void journal_destroy(journal_t *journal) +{ + /* Wait for the commit thread to wake up and die. */ + journal_kill_thread(journal); + + /* Force a final log commit */ + if (journal->j_running_transaction) + journal_commit_transaction(journal); + + /* Force any old transactions to disk */ + + /* Totally anal locking here... */ + spin_lock(&journal->j_list_lock); + while (journal->j_checkpoint_transactions != NULL) { + spin_unlock(&journal->j_list_lock); + log_do_checkpoint(journal); + spin_lock(&journal->j_list_lock); + } + + J_ASSERT(journal->j_running_transaction == NULL); + J_ASSERT(journal->j_committing_transaction == NULL); + J_ASSERT(journal->j_checkpoint_transactions == NULL); + spin_unlock(&journal->j_list_lock); + + /* We can now mark the journal as empty. */ + journal->j_tail = 0; + journal->j_tail_sequence = ++journal->j_transaction_sequence; + if (journal->j_sb_buffer) { + journal_update_superblock(journal, 1); + brelse(journal->j_sb_buffer); + } + + if (journal->j_inode) + iput(journal->j_inode); + if (journal->j_revoke) + journal_destroy_revoke(journal); + kfree(journal->j_wbuf); + kfree(journal); +} + + +/** + *int journal_check_used_features () - Check if features specified are used. + * @journal: Journal to check. + * @compat: bitmask of compatible features + * @ro: bitmask of features that force read-only mount + * @incompat: bitmask of incompatible features + * + * Check whether the journal uses all of a given set of + * features. Return true (non-zero) if it does. + **/ + +int journal_check_used_features (journal_t *journal, unsigned long compat, + unsigned long ro, unsigned long incompat) +{ + journal_superblock_t *sb; + + if (!compat && !ro && !incompat) + return 1; + if (journal->j_format_version == 1) + return 0; + + sb = journal->j_superblock; + + if (((be32_to_cpu(sb->s_feature_compat) & compat) == compat) && + ((be32_to_cpu(sb->s_feature_ro_compat) & ro) == ro) && + ((be32_to_cpu(sb->s_feature_incompat) & incompat) == incompat)) + return 1; + + return 0; +} + +/** + * int journal_check_available_features() - Check feature set in journalling layer + * @journal: Journal to check. + * @compat: bitmask of compatible features + * @ro: bitmask of features that force read-only mount + * @incompat: bitmask of incompatible features + * + * Check whether the journaling code supports the use of + * all of a given set of features on this journal. Return true + * (non-zero) if it can. */ + +int journal_check_available_features (journal_t *journal, unsigned long compat, + unsigned long ro, unsigned long incompat) +{ + journal_superblock_t *sb; + + if (!compat && !ro && !incompat) + return 1; + + sb = journal->j_superblock; + + /* We can support any known requested features iff the + * superblock is in version 2. Otherwise we fail to support any + * extended sb features. */ + + if (journal->j_format_version != 2) + return 0; + + if ((compat & JFS_KNOWN_COMPAT_FEATURES) == compat && + (ro & JFS_KNOWN_ROCOMPAT_FEATURES) == ro && + (incompat & JFS_KNOWN_INCOMPAT_FEATURES) == incompat) + return 1; + + return 0; +} + +/** + * int journal_set_features () - Mark a given journal feature in the superblock + * @journal: Journal to act on. + * @compat: bitmask of compatible features + * @ro: bitmask of features that force read-only mount + * @incompat: bitmask of incompatible features + * + * Mark a given journal feature as present on the + * superblock. Returns true if the requested features could be set. + * + */ + +int journal_set_features (journal_t *journal, unsigned long compat, + unsigned long ro, unsigned long incompat) +{ + journal_superblock_t *sb; + + if (journal_check_used_features(journal, compat, ro, incompat)) + return 1; + + if (!journal_check_available_features(journal, compat, ro, incompat)) + return 0; + + jbd_debug(1, "Setting new features 0x%lx/0x%lx/0x%lx\n", + compat, ro, incompat); + + sb = journal->j_superblock; + + sb->s_feature_compat |= cpu_to_be32(compat); + sb->s_feature_ro_compat |= cpu_to_be32(ro); + sb->s_feature_incompat |= cpu_to_be32(incompat); + + return 1; +} + + +/** + * int journal_update_format () - Update on-disk journal structure. + * @journal: Journal to act on. + * + * Given an initialised but unloaded journal struct, poke about in the + * on-disk structure to update it to the most recent supported version. + */ +int journal_update_format (journal_t *journal) +{ + journal_superblock_t *sb; + int err; + + err = journal_get_superblock(journal); + if (err) + return err; + + sb = journal->j_superblock; + + switch (be32_to_cpu(sb->s_header.h_blocktype)) { + case JFS_SUPERBLOCK_V2: + return 0; + case JFS_SUPERBLOCK_V1: + return journal_convert_superblock_v1(journal, sb); + default: + break; + } + return -EINVAL; +} + +static int journal_convert_superblock_v1(journal_t *journal, + journal_superblock_t *sb) +{ + int offset, blocksize; + struct buffer_head *bh; + + printk(KERN_WARNING + "JBD: Converting superblock from version 1 to 2.\n"); + + /* Pre-initialise new fields to zero */ + offset = ((char *) &(sb->s_feature_compat)) - ((char *) sb); + blocksize = be32_to_cpu(sb->s_blocksize); + memset(&sb->s_feature_compat, 0, blocksize-offset); + + sb->s_nr_users = cpu_to_be32(1); + sb->s_header.h_blocktype = cpu_to_be32(JFS_SUPERBLOCK_V2); + journal->j_format_version = 2; + + bh = journal->j_sb_buffer; + BUFFER_TRACE(bh, "marking dirty"); + mark_buffer_dirty(bh); + sync_dirty_buffer(bh); + return 0; +} + + +/** + * int journal_flush () - Flush journal + * @journal: Journal to act on. + * + * Flush all data for a given journal to disk and empty the journal. + * Filesystems can use this when remounting readonly to ensure that + * recovery does not need to happen on remount. + */ + +int journal_flush(journal_t *journal) +{ + int err = 0; + transaction_t *transaction = NULL; + unsigned long old_tail; + + spin_lock(&journal->j_state_lock); + + /* Force everything buffered to the log... */ + if (journal->j_running_transaction) { + transaction = journal->j_running_transaction; + __log_start_commit(journal, transaction->t_tid); + } else if (journal->j_committing_transaction) + transaction = journal->j_committing_transaction; + + /* Wait for the log commit to complete... */ + if (transaction) { + tid_t tid = transaction->t_tid; + + spin_unlock(&journal->j_state_lock); + log_wait_commit(journal, tid); + } else { + spin_unlock(&journal->j_state_lock); + } + + /* ...and flush everything in the log out to disk. */ + spin_lock(&journal->j_list_lock); + while (!err && journal->j_checkpoint_transactions != NULL) { + spin_unlock(&journal->j_list_lock); + err = log_do_checkpoint(journal); + spin_lock(&journal->j_list_lock); + } + spin_unlock(&journal->j_list_lock); + cleanup_journal_tail(journal); + + /* Finally, mark the journal as really needing no recovery. + * This sets s_start==0 in the underlying superblock, which is + * the magic code for a fully-recovered superblock. Any future + * commits of data to the journal will restore the current + * s_start value. */ + spin_lock(&journal->j_state_lock); + old_tail = journal->j_tail; + journal->j_tail = 0; + spin_unlock(&journal->j_state_lock); + journal_update_superblock(journal, 1); + spin_lock(&journal->j_state_lock); + journal->j_tail = old_tail; + + J_ASSERT(!journal->j_running_transaction); + J_ASSERT(!journal->j_committing_transaction); + J_ASSERT(!journal->j_checkpoint_transactions); + J_ASSERT(journal->j_head == journal->j_tail); + J_ASSERT(journal->j_tail_sequence == journal->j_transaction_sequence); + spin_unlock(&journal->j_state_lock); + return err; +} + +/** + * int journal_wipe() - Wipe journal contents + * @journal: Journal to act on. + * @write: flag (see below) + * + * Wipe out all of the contents of a journal, safely. This will produce + * a warning if the journal contains any valid recovery information. + * Must be called between journal_init_*() and journal_load(). + * + * If 'write' is non-zero, then we wipe out the journal on disk; otherwise + * we merely suppress recovery. + */ + +int journal_wipe(journal_t *journal, int write) +{ + journal_superblock_t *sb; + int err = 0; + + J_ASSERT (!(journal->j_flags & JFS_LOADED)); + + err = load_superblock(journal); + if (err) + return err; + + sb = journal->j_superblock; + + if (!journal->j_tail) + goto no_recovery; + + printk (KERN_WARNING "JBD: %s recovery information on journal\n", + write ? "Clearing" : "Ignoring"); + + err = journal_skip_recovery(journal); + if (write) + journal_update_superblock(journal, 1); + + no_recovery: + return err; +} + +/* + * journal_dev_name: format a character string to describe on what + * device this journal is present. + */ + +const char *journal_dev_name(journal_t *journal, char *buffer) +{ + struct block_device *bdev; + + if (journal->j_inode) + bdev = journal->j_inode->i_sb->s_bdev; + else + bdev = journal->j_dev; + + return bdevname(bdev, buffer); +} + +/* + * Journal abort has very specific semantics, which we describe + * for journal abort. + * + * Two internal function, which provide abort to te jbd layer + * itself are here. + */ + +/* + * Quick version for internal journal use (doesn't lock the journal). + * Aborts hard --- we mark the abort as occurred, but do _nothing_ else, + * and don't attempt to make any other journal updates. + */ +void __journal_abort_hard(journal_t *journal) +{ + transaction_t *transaction; + char b[BDEVNAME_SIZE]; + + if (journal->j_flags & JFS_ABORT) + return; + + printk(KERN_ERR "Aborting journal on device %s.\n", + journal_dev_name(journal, b)); + + spin_lock(&journal->j_state_lock); + journal->j_flags |= JFS_ABORT; + transaction = journal->j_running_transaction; + if (transaction) + __log_start_commit(journal, transaction->t_tid); + spin_unlock(&journal->j_state_lock); +} + +/* Soft abort: record the abort error status in the journal superblock, + * but don't do any other IO. */ +void __journal_abort_soft (journal_t *journal, int errno) +{ + if (journal->j_flags & JFS_ABORT) + return; + + if (!journal->j_errno) + journal->j_errno = errno; + + __journal_abort_hard(journal); + + if (errno) + journal_update_superblock(journal, 1); +} + +/** + * void journal_abort () - Shutdown the journal immediately. + * @journal: the journal to shutdown. + * @errno: an error number to record in the journal indicating + * the reason for the shutdown. + * + * Perform a complete, immediate shutdown of the ENTIRE + * journal (not of a single transaction). This operation cannot be + * undone without closing and reopening the journal. + * + * The journal_abort function is intended to support higher level error + * recovery mechanisms such as the ext2/ext3 remount-readonly error + * mode. + * + * Journal abort has very specific semantics. Any existing dirty, + * unjournaled buffers in the main filesystem will still be written to + * disk by bdflush, but the journaling mechanism will be suspended + * immediately and no further transaction commits will be honoured. + * + * Any dirty, journaled buffers will be written back to disk without + * hitting the journal. Atomicity cannot be guaranteed on an aborted + * filesystem, but we _do_ attempt to leave as much data as possible + * behind for fsck to use for cleanup. + * + * Any attempt to get a new transaction handle on a journal which is in + * ABORT state will just result in an -EROFS error return. A + * journal_stop on an existing handle will return -EIO if we have + * entered abort state during the update. + * + * Recursive transactions are not disturbed by journal abort until the + * final journal_stop, which will receive the -EIO error. + * + * Finally, the journal_abort call allows the caller to supply an errno + * which will be recorded (if possible) in the journal superblock. This + * allows a client to record failure conditions in the middle of a + * transaction without having to complete the transaction to record the + * failure to disk. ext3_error, for example, now uses this + * functionality. + * + * Errors which originate from within the journaling layer will NOT + * supply an errno; a null errno implies that absolutely no further + * writes are done to the journal (unless there are any already in + * progress). + * + */ + +void journal_abort(journal_t *journal, int errno) +{ + __journal_abort_soft(journal, errno); +} + +/** + * int journal_errno () - returns the journal's error state. + * @journal: journal to examine. + * + * This is the errno numbet set with journal_abort(), the last + * time the journal was mounted - if the journal was stopped + * without calling abort this will be 0. + * + * If the journal has been aborted on this mount time -EROFS will + * be returned. + */ +int journal_errno(journal_t *journal) +{ + int err; + + spin_lock(&journal->j_state_lock); + if (journal->j_flags & JFS_ABORT) + err = -EROFS; + else + err = journal->j_errno; + spin_unlock(&journal->j_state_lock); + return err; +} + +/** + * int journal_clear_err () - clears the journal's error state + * @journal: journal to act on. + * + * An error must be cleared or Acked to take a FS out of readonly + * mode. + */ +int journal_clear_err(journal_t *journal) +{ + int err = 0; + + spin_lock(&journal->j_state_lock); + if (journal->j_flags & JFS_ABORT) + err = -EROFS; + else + journal->j_errno = 0; + spin_unlock(&journal->j_state_lock); + return err; +} + +/** + * void journal_ack_err() - Ack journal err. + * @journal: journal to act on. + * + * An error must be cleared or Acked to take a FS out of readonly + * mode. + */ +void journal_ack_err(journal_t *journal) +{ + spin_lock(&journal->j_state_lock); + if (journal->j_errno) + journal->j_flags |= JFS_ACK_ERR; + spin_unlock(&journal->j_state_lock); +} + +int journal_blocks_per_page(struct inode *inode) +{ + return 1 << (PAGE_CACHE_SHIFT - inode->i_sb->s_blocksize_bits); +} + +/* + * Simple support for retrying memory allocations. Introduced to help to + * debug different VM deadlock avoidance strategies. + */ +void * __jbd_kmalloc (const char *where, size_t size, int flags, int retry) +{ + return kmalloc(size, flags | (retry ? __GFP_NOFAIL : 0)); +} + +/* + * Journal_head storage management + */ +static kmem_cache_t *journal_head_cache; +#ifdef CONFIG_JBD_DEBUG +static atomic_t nr_journal_heads = ATOMIC_INIT(0); +#endif + +static int journal_init_journal_head_cache(void) +{ + int retval; + + J_ASSERT(journal_head_cache == 0); + journal_head_cache = kmem_cache_create("journal_head", + sizeof(struct journal_head), + 0, /* offset */ + 0, /* flags */ + NULL, /* ctor */ + NULL); /* dtor */ + retval = 0; + if (journal_head_cache == 0) { + retval = -ENOMEM; + printk(KERN_EMERG "JBD: no memory for journal_head cache\n"); + } + return retval; +} + +static void journal_destroy_journal_head_cache(void) +{ + J_ASSERT(journal_head_cache != NULL); + kmem_cache_destroy(journal_head_cache); + journal_head_cache = NULL; +} + +/* + * journal_head splicing and dicing + */ +static struct journal_head *journal_alloc_journal_head(void) +{ + struct journal_head *ret; + static unsigned long last_warning; + +#ifdef CONFIG_JBD_DEBUG + atomic_inc(&nr_journal_heads); +#endif + ret = kmem_cache_alloc(journal_head_cache, GFP_NOFS); + if (ret == 0) { + jbd_debug(1, "out of memory for journal_head\n"); + if (time_after(jiffies, last_warning + 5*HZ)) { + printk(KERN_NOTICE "ENOMEM in %s, retrying.\n", + __FUNCTION__); + last_warning = jiffies; + } + while (ret == 0) { + yield(); + ret = kmem_cache_alloc(journal_head_cache, GFP_NOFS); + } + } + return ret; +} + +static void journal_free_journal_head(struct journal_head *jh) +{ +#ifdef CONFIG_JBD_DEBUG + atomic_dec(&nr_journal_heads); + memset(jh, 0x5b, sizeof(*jh)); +#endif + kmem_cache_free(journal_head_cache, jh); +} + +/* + * A journal_head is attached to a buffer_head whenever JBD has an + * interest in the buffer. + * + * Whenever a buffer has an attached journal_head, its ->b_state:BH_JBD bit + * is set. This bit is tested in core kernel code where we need to take + * JBD-specific actions. Testing the zeroness of ->b_private is not reliable + * there. + * + * When a buffer has its BH_JBD bit set, its ->b_count is elevated by one. + * + * When a buffer has its BH_JBD bit set it is immune from being released by + * core kernel code, mainly via ->b_count. + * + * A journal_head may be detached from its buffer_head when the journal_head's + * b_transaction, b_cp_transaction and b_next_transaction pointers are NULL. + * Various places in JBD call journal_remove_journal_head() to indicate that the + * journal_head can be dropped if needed. + * + * Various places in the kernel want to attach a journal_head to a buffer_head + * _before_ attaching the journal_head to a transaction. To protect the + * journal_head in this situation, journal_add_journal_head elevates the + * journal_head's b_jcount refcount by one. The caller must call + * journal_put_journal_head() to undo this. + * + * So the typical usage would be: + * + * (Attach a journal_head if needed. Increments b_jcount) + * struct journal_head *jh = journal_add_journal_head(bh); + * ... + * jh->b_transaction = xxx; + * journal_put_journal_head(jh); + * + * Now, the journal_head's b_jcount is zero, but it is safe from being released + * because it has a non-zero b_transaction. + */ + +/* + * Give a buffer_head a journal_head. + * + * Doesn't need the journal lock. + * May sleep. + */ +struct journal_head *journal_add_journal_head(struct buffer_head *bh) +{ + struct journal_head *jh; + struct journal_head *new_jh = NULL; + +repeat: + if (!buffer_jbd(bh)) { + new_jh = journal_alloc_journal_head(); + memset(new_jh, 0, sizeof(*new_jh)); + } + + jbd_lock_bh_journal_head(bh); + if (buffer_jbd(bh)) { + jh = bh2jh(bh); + } else { + J_ASSERT_BH(bh, + (atomic_read(&bh->b_count) > 0) || + (bh->b_page && bh->b_page->mapping)); + + if (!new_jh) { + jbd_unlock_bh_journal_head(bh); + goto repeat; + } + + jh = new_jh; + new_jh = NULL; /* We consumed it */ + set_buffer_jbd(bh); + bh->b_private = jh; + jh->b_bh = bh; + get_bh(bh); + BUFFER_TRACE(bh, "added journal_head"); + } + jh->b_jcount++; + jbd_unlock_bh_journal_head(bh); + if (new_jh) + journal_free_journal_head(new_jh); + return bh->b_private; +} + +/* + * Grab a ref against this buffer_head's journal_head. If it ended up not + * having a journal_head, return NULL + */ +struct journal_head *journal_grab_journal_head(struct buffer_head *bh) +{ + struct journal_head *jh = NULL; + + jbd_lock_bh_journal_head(bh); + if (buffer_jbd(bh)) { + jh = bh2jh(bh); + jh->b_jcount++; + } + jbd_unlock_bh_journal_head(bh); + return jh; +} + +static void __journal_remove_journal_head(struct buffer_head *bh) +{ + struct journal_head *jh = bh2jh(bh); + + J_ASSERT_JH(jh, jh->b_jcount >= 0); + + get_bh(bh); + if (jh->b_jcount == 0) { + if (jh->b_transaction == NULL && + jh->b_next_transaction == NULL && + jh->b_cp_transaction == NULL) { + J_ASSERT_JH(jh, jh->b_jlist == BJ_None); + J_ASSERT_BH(bh, buffer_jbd(bh)); + J_ASSERT_BH(bh, jh2bh(jh) == bh); + BUFFER_TRACE(bh, "remove journal_head"); + if (jh->b_frozen_data) { + printk(KERN_WARNING "%s: freeing " + "b_frozen_data\n", + __FUNCTION__); + kfree(jh->b_frozen_data); + } + if (jh->b_committed_data) { + printk(KERN_WARNING "%s: freeing " + "b_committed_data\n", + __FUNCTION__); + kfree(jh->b_committed_data); + } + bh->b_private = NULL; + jh->b_bh = NULL; /* debug, really */ + clear_buffer_jbd(bh); + __brelse(bh); + journal_free_journal_head(jh); + } else { + BUFFER_TRACE(bh, "journal_head was locked"); + } + } +} + +/* + * journal_remove_journal_head(): if the buffer isn't attached to a transaction + * and has a zero b_jcount then remove and release its journal_head. If we did + * see that the buffer is not used by any transaction we also "logically" + * decrement ->b_count. + * + * We in fact take an additional increment on ->b_count as a convenience, + * because the caller usually wants to do additional things with the bh + * after calling here. + * The caller of journal_remove_journal_head() *must* run __brelse(bh) at some + * time. Once the caller has run __brelse(), the buffer is eligible for + * reaping by try_to_free_buffers(). + */ +void journal_remove_journal_head(struct buffer_head *bh) +{ + jbd_lock_bh_journal_head(bh); + __journal_remove_journal_head(bh); + jbd_unlock_bh_journal_head(bh); +} + +/* + * Drop a reference on the passed journal_head. If it fell to zero then try to + * release the journal_head from the buffer_head. + */ +void journal_put_journal_head(struct journal_head *jh) +{ + struct buffer_head *bh = jh2bh(jh); + + jbd_lock_bh_journal_head(bh); + J_ASSERT_JH(jh, jh->b_jcount > 0); + --jh->b_jcount; + if (!jh->b_jcount && !jh->b_transaction) { + __journal_remove_journal_head(bh); + __brelse(bh); + } + jbd_unlock_bh_journal_head(bh); +} + +/* + * /proc tunables + */ +#if defined(CONFIG_JBD_DEBUG) +int journal_enable_debug; +EXPORT_SYMBOL(journal_enable_debug); +#endif + +#if defined(CONFIG_JBD_DEBUG) && defined(CONFIG_PROC_FS) + +static struct proc_dir_entry *proc_jbd_debug; + +int read_jbd_debug(char *page, char **start, off_t off, + int count, int *eof, void *data) +{ + int ret; + + ret = sprintf(page + off, "%d\n", journal_enable_debug); + *eof = 1; + return ret; +} + +int write_jbd_debug(struct file *file, const char __user *buffer, + unsigned long count, void *data) +{ + char buf[32]; + + if (count > ARRAY_SIZE(buf) - 1) + count = ARRAY_SIZE(buf) - 1; + if (copy_from_user(buf, buffer, count)) + return -EFAULT; + buf[ARRAY_SIZE(buf) - 1] = '\0'; + journal_enable_debug = simple_strtoul(buf, NULL, 10); + return count; +} + +#define JBD_PROC_NAME "sys/fs/jbd-debug" + +static void __init create_jbd_proc_entry(void) +{ + proc_jbd_debug = create_proc_entry(JBD_PROC_NAME, 0644, NULL); + if (proc_jbd_debug) { + /* Why is this so hard? */ + proc_jbd_debug->read_proc = read_jbd_debug; + proc_jbd_debug->write_proc = write_jbd_debug; + } +} + +static void __exit remove_jbd_proc_entry(void) +{ + if (proc_jbd_debug) + remove_proc_entry(JBD_PROC_NAME, NULL); +} + +#else + +#define create_jbd_proc_entry() do {} while (0) +#define remove_jbd_proc_entry() do {} while (0) + +#endif + +kmem_cache_t *jbd_handle_cache; + +static int __init journal_init_handle_cache(void) +{ + jbd_handle_cache = kmem_cache_create("journal_handle", + sizeof(handle_t), + 0, /* offset */ + 0, /* flags */ + NULL, /* ctor */ + NULL); /* dtor */ + if (jbd_handle_cache == NULL) { + printk(KERN_EMERG "JBD: failed to create handle cache\n"); + return -ENOMEM; + } + return 0; +} + +static void journal_destroy_handle_cache(void) +{ + if (jbd_handle_cache) + kmem_cache_destroy(jbd_handle_cache); +} + +/* + * Module startup and shutdown + */ + +static int __init journal_init_caches(void) +{ + int ret; + + ret = journal_init_revoke_caches(); + if (ret == 0) + ret = journal_init_journal_head_cache(); + if (ret == 0) + ret = journal_init_handle_cache(); + return ret; +} + +static void journal_destroy_caches(void) +{ + journal_destroy_revoke_caches(); + journal_destroy_journal_head_cache(); + journal_destroy_handle_cache(); +} + +static int __init journal_init(void) +{ + int ret; + + ret = journal_init_caches(); + if (ret != 0) + journal_destroy_caches(); + create_jbd_proc_entry(); + return ret; +} + +static void __exit journal_exit(void) +{ +#ifdef CONFIG_JBD_DEBUG + int n = atomic_read(&nr_journal_heads); + if (n) + printk(KERN_EMERG "JBD: leaked %d journal_heads!\n", n); +#endif + remove_jbd_proc_entry(); + journal_destroy_caches(); +} + +MODULE_LICENSE("GPL"); +module_init(journal_init); +module_exit(journal_exit); + diff --git a/fs/jbd/recovery.c b/fs/jbd/recovery.c new file mode 100644 index 00000000000..103c34e4fb2 --- /dev/null +++ b/fs/jbd/recovery.c @@ -0,0 +1,591 @@ +/* + * linux/fs/recovery.c + * + * Written by Stephen C. Tweedie <sct@redhat.com>, 1999 + * + * Copyright 1999-2000 Red Hat Software --- All Rights Reserved + * + * This file is part of the Linux kernel and is made available under + * the terms of the GNU General Public License, version 2, or at your + * option, any later version, incorporated herein by reference. + * + * Journal recovery routines for the generic filesystem journaling code; + * part of the ext2fs journaling system. + */ + +#ifndef __KERNEL__ +#include "jfs_user.h" +#else +#include <linux/time.h> +#include <linux/fs.h> +#include <linux/jbd.h> +#include <linux/errno.h> +#include <linux/slab.h> +#endif + +/* + * Maintain information about the progress of the recovery job, so that + * the different passes can carry information between them. + */ +struct recovery_info +{ + tid_t start_transaction; + tid_t end_transaction; + + int nr_replays; + int nr_revokes; + int nr_revoke_hits; +}; + +enum passtype {PASS_SCAN, PASS_REVOKE, PASS_REPLAY}; +static int do_one_pass(journal_t *journal, + struct recovery_info *info, enum passtype pass); +static int scan_revoke_records(journal_t *, struct buffer_head *, + tid_t, struct recovery_info *); + +#ifdef __KERNEL__ + +/* Release readahead buffers after use */ +void journal_brelse_array(struct buffer_head *b[], int n) +{ + while (--n >= 0) + brelse (b[n]); +} + + +/* + * When reading from the journal, we are going through the block device + * layer directly and so there is no readahead being done for us. We + * need to implement any readahead ourselves if we want it to happen at + * all. Recovery is basically one long sequential read, so make sure we + * do the IO in reasonably large chunks. + * + * This is not so critical that we need to be enormously clever about + * the readahead size, though. 128K is a purely arbitrary, good-enough + * fixed value. + */ + +#define MAXBUF 8 +static int do_readahead(journal_t *journal, unsigned int start) +{ + int err; + unsigned int max, nbufs, next; + unsigned long blocknr; + struct buffer_head *bh; + + struct buffer_head * bufs[MAXBUF]; + + /* Do up to 128K of readahead */ + max = start + (128 * 1024 / journal->j_blocksize); + if (max > journal->j_maxlen) + max = journal->j_maxlen; + + /* Do the readahead itself. We'll submit MAXBUF buffer_heads at + * a time to the block device IO layer. */ + + nbufs = 0; + + for (next = start; next < max; next++) { + err = journal_bmap(journal, next, &blocknr); + + if (err) { + printk (KERN_ERR "JBD: bad block at offset %u\n", + next); + goto failed; + } + + bh = __getblk(journal->j_dev, blocknr, journal->j_blocksize); + if (!bh) { + err = -ENOMEM; + goto failed; + } + + if (!buffer_uptodate(bh) && !buffer_locked(bh)) { + bufs[nbufs++] = bh; + if (nbufs == MAXBUF) { + ll_rw_block(READ, nbufs, bufs); + journal_brelse_array(bufs, nbufs); + nbufs = 0; + } + } else + brelse(bh); + } + + if (nbufs) + ll_rw_block(READ, nbufs, bufs); + err = 0; + +failed: + if (nbufs) + journal_brelse_array(bufs, nbufs); + return err; +} + +#endif /* __KERNEL__ */ + + +/* + * Read a block from the journal + */ + +static int jread(struct buffer_head **bhp, journal_t *journal, + unsigned int offset) +{ + int err; + unsigned long blocknr; + struct buffer_head *bh; + + *bhp = NULL; + + if (offset >= journal->j_maxlen) { + printk(KERN_ERR "JBD: corrupted journal superblock\n"); + return -EIO; + } + + err = journal_bmap(journal, offset, &blocknr); + + if (err) { + printk (KERN_ERR "JBD: bad block at offset %u\n", + offset); + return err; + } + + bh = __getblk(journal->j_dev, blocknr, journal->j_blocksize); + if (!bh) + return -ENOMEM; + + if (!buffer_uptodate(bh)) { + /* If this is a brand new buffer, start readahead. + Otherwise, we assume we are already reading it. */ + if (!buffer_req(bh)) + do_readahead(journal, offset); + wait_on_buffer(bh); + } + + if (!buffer_uptodate(bh)) { + printk (KERN_ERR "JBD: Failed to read block at offset %u\n", + offset); + brelse(bh); + return -EIO; + } + + *bhp = bh; + return 0; +} + + +/* + * Count the number of in-use tags in a journal descriptor block. + */ + +static int count_tags(struct buffer_head *bh, int size) +{ + char * tagp; + journal_block_tag_t * tag; + int nr = 0; + + tagp = &bh->b_data[sizeof(journal_header_t)]; + + while ((tagp - bh->b_data + sizeof(journal_block_tag_t)) <= size) { + tag = (journal_block_tag_t *) tagp; + + nr++; + tagp += sizeof(journal_block_tag_t); + if (!(tag->t_flags & cpu_to_be32(JFS_FLAG_SAME_UUID))) + tagp += 16; + + if (tag->t_flags & cpu_to_be32(JFS_FLAG_LAST_TAG)) + break; + } + + return nr; +} + + +/* Make sure we wrap around the log correctly! */ +#define wrap(journal, var) \ +do { \ + if (var >= (journal)->j_last) \ + var -= ((journal)->j_last - (journal)->j_first); \ +} while (0) + +/** + * int journal_recover(journal_t *journal) - recovers a on-disk journal + * @journal: the journal to recover + * + * The primary function for recovering the log contents when mounting a + * journaled device. + * + * Recovery is done in three passes. In the first pass, we look for the + * end of the log. In the second, we assemble the list of revoke + * blocks. In the third and final pass, we replay any un-revoked blocks + * in the log. + */ +int journal_recover(journal_t *journal) +{ + int err; + journal_superblock_t * sb; + + struct recovery_info info; + + memset(&info, 0, sizeof(info)); + sb = journal->j_superblock; + + /* + * The journal superblock's s_start field (the current log head) + * is always zero if, and only if, the journal was cleanly + * unmounted. + */ + + if (!sb->s_start) { + jbd_debug(1, "No recovery required, last transaction %d\n", + be32_to_cpu(sb->s_sequence)); + journal->j_transaction_sequence = be32_to_cpu(sb->s_sequence) + 1; + return 0; + } + + err = do_one_pass(journal, &info, PASS_SCAN); + if (!err) + err = do_one_pass(journal, &info, PASS_REVOKE); + if (!err) + err = do_one_pass(journal, &info, PASS_REPLAY); + + jbd_debug(0, "JBD: recovery, exit status %d, " + "recovered transactions %u to %u\n", + err, info.start_transaction, info.end_transaction); + jbd_debug(0, "JBD: Replayed %d and revoked %d/%d blocks\n", + info.nr_replays, info.nr_revoke_hits, info.nr_revokes); + + /* Restart the log at the next transaction ID, thus invalidating + * any existing commit records in the log. */ + journal->j_transaction_sequence = ++info.end_transaction; + + journal_clear_revoke(journal); + sync_blockdev(journal->j_fs_dev); + return err; +} + +/** + * int journal_skip_recovery() - Start journal and wipe exiting records + * @journal: journal to startup + * + * Locate any valid recovery information from the journal and set up the + * journal structures in memory to ignore it (presumably because the + * caller has evidence that it is out of date). + * This function does'nt appear to be exorted.. + * + * We perform one pass over the journal to allow us to tell the user how + * much recovery information is being erased, and to let us initialise + * the journal transaction sequence numbers to the next unused ID. + */ +int journal_skip_recovery(journal_t *journal) +{ + int err; + journal_superblock_t * sb; + + struct recovery_info info; + + memset (&info, 0, sizeof(info)); + sb = journal->j_superblock; + + err = do_one_pass(journal, &info, PASS_SCAN); + + if (err) { + printk(KERN_ERR "JBD: error %d scanning journal\n", err); + ++journal->j_transaction_sequence; + } else { +#ifdef CONFIG_JBD_DEBUG + int dropped = info.end_transaction - be32_to_cpu(sb->s_sequence); +#endif + jbd_debug(0, + "JBD: ignoring %d transaction%s from the journal.\n", + dropped, (dropped == 1) ? "" : "s"); + journal->j_transaction_sequence = ++info.end_transaction; + } + + journal->j_tail = 0; + return err; +} + +static int do_one_pass(journal_t *journal, + struct recovery_info *info, enum passtype pass) +{ + unsigned int first_commit_ID, next_commit_ID; + unsigned long next_log_block; + int err, success = 0; + journal_superblock_t * sb; + journal_header_t * tmp; + struct buffer_head * bh; + unsigned int sequence; + int blocktype; + + /* Precompute the maximum metadata descriptors in a descriptor block */ + int MAX_BLOCKS_PER_DESC; + MAX_BLOCKS_PER_DESC = ((journal->j_blocksize-sizeof(journal_header_t)) + / sizeof(journal_block_tag_t)); + + /* + * First thing is to establish what we expect to find in the log + * (in terms of transaction IDs), and where (in terms of log + * block offsets): query the superblock. + */ + + sb = journal->j_superblock; + next_commit_ID = be32_to_cpu(sb->s_sequence); + next_log_block = be32_to_cpu(sb->s_start); + + first_commit_ID = next_commit_ID; + if (pass == PASS_SCAN) + info->start_transaction = first_commit_ID; + + jbd_debug(1, "Starting recovery pass %d\n", pass); + + /* + * Now we walk through the log, transaction by transaction, + * making sure that each transaction has a commit block in the + * expected place. Each complete transaction gets replayed back + * into the main filesystem. + */ + + while (1) { + int flags; + char * tagp; + journal_block_tag_t * tag; + struct buffer_head * obh; + struct buffer_head * nbh; + + cond_resched(); /* We're under lock_kernel() */ + + /* If we already know where to stop the log traversal, + * check right now that we haven't gone past the end of + * the log. */ + + if (pass != PASS_SCAN) + if (tid_geq(next_commit_ID, info->end_transaction)) + break; + + jbd_debug(2, "Scanning for sequence ID %u at %lu/%lu\n", + next_commit_ID, next_log_block, journal->j_last); + + /* Skip over each chunk of the transaction looking + * either the next descriptor block or the final commit + * record. */ + + jbd_debug(3, "JBD: checking block %ld\n", next_log_block); + err = jread(&bh, journal, next_log_block); + if (err) + goto failed; + + next_log_block++; + wrap(journal, next_log_block); + + /* What kind of buffer is it? + * + * If it is a descriptor block, check that it has the + * expected sequence number. Otherwise, we're all done + * here. */ + + tmp = (journal_header_t *)bh->b_data; + + if (tmp->h_magic != cpu_to_be32(JFS_MAGIC_NUMBER)) { + brelse(bh); + break; + } + + blocktype = be32_to_cpu(tmp->h_blocktype); + sequence = be32_to_cpu(tmp->h_sequence); + jbd_debug(3, "Found magic %d, sequence %d\n", + blocktype, sequence); + + if (sequence != next_commit_ID) { + brelse(bh); + break; + } + + /* OK, we have a valid descriptor block which matches + * all of the sequence number checks. What are we going + * to do with it? That depends on the pass... */ + + switch(blocktype) { + case JFS_DESCRIPTOR_BLOCK: + /* If it is a valid descriptor block, replay it + * in pass REPLAY; otherwise, just skip over the + * blocks it describes. */ + if (pass != PASS_REPLAY) { + next_log_block += + count_tags(bh, journal->j_blocksize); + wrap(journal, next_log_block); + brelse(bh); + continue; + } + + /* A descriptor block: we can now write all of + * the data blocks. Yay, useful work is finally + * getting done here! */ + + tagp = &bh->b_data[sizeof(journal_header_t)]; + while ((tagp - bh->b_data +sizeof(journal_block_tag_t)) + <= journal->j_blocksize) { + unsigned long io_block; + + tag = (journal_block_tag_t *) tagp; + flags = be32_to_cpu(tag->t_flags); + + io_block = next_log_block++; + wrap(journal, next_log_block); + err = jread(&obh, journal, io_block); + if (err) { + /* Recover what we can, but + * report failure at the end. */ + success = err; + printk (KERN_ERR + "JBD: IO error %d recovering " + "block %ld in log\n", + err, io_block); + } else { + unsigned long blocknr; + + J_ASSERT(obh != NULL); + blocknr = be32_to_cpu(tag->t_blocknr); + + /* If the block has been + * revoked, then we're all done + * here. */ + if (journal_test_revoke + (journal, blocknr, + next_commit_ID)) { + brelse(obh); + ++info->nr_revoke_hits; + goto skip_write; + } + + /* Find a buffer for the new + * data being restored */ + nbh = __getblk(journal->j_fs_dev, + blocknr, + journal->j_blocksize); + if (nbh == NULL) { + printk(KERN_ERR + "JBD: Out of memory " + "during recovery.\n"); + err = -ENOMEM; + brelse(bh); + brelse(obh); + goto failed; + } + + lock_buffer(nbh); + memcpy(nbh->b_data, obh->b_data, + journal->j_blocksize); + if (flags & JFS_FLAG_ESCAPE) { + *((__be32 *)bh->b_data) = + cpu_to_be32(JFS_MAGIC_NUMBER); + } + + BUFFER_TRACE(nbh, "marking dirty"); + set_buffer_uptodate(nbh); + mark_buffer_dirty(nbh); + BUFFER_TRACE(nbh, "marking uptodate"); + ++info->nr_replays; + /* ll_rw_block(WRITE, 1, &nbh); */ + unlock_buffer(nbh); + brelse(obh); + brelse(nbh); + } + + skip_write: + tagp += sizeof(journal_block_tag_t); + if (!(flags & JFS_FLAG_SAME_UUID)) + tagp += 16; + + if (flags & JFS_FLAG_LAST_TAG) + break; + } + + brelse(bh); + continue; + + case JFS_COMMIT_BLOCK: + /* Found an expected commit block: not much to + * do other than move on to the next sequence + * number. */ + brelse(bh); + next_commit_ID++; + continue; + + case JFS_REVOKE_BLOCK: + /* If we aren't in the REVOKE pass, then we can + * just skip over this block. */ + if (pass != PASS_REVOKE) { + brelse(bh); + continue; + } + + err = scan_revoke_records(journal, bh, + next_commit_ID, info); + brelse(bh); + if (err) + goto failed; + continue; + + default: + jbd_debug(3, "Unrecognised magic %d, end of scan.\n", + blocktype); + goto done; + } + } + + done: + /* + * We broke out of the log scan loop: either we came to the + * known end of the log or we found an unexpected block in the + * log. If the latter happened, then we know that the "current" + * transaction marks the end of the valid log. + */ + + if (pass == PASS_SCAN) + info->end_transaction = next_commit_ID; + else { + /* It's really bad news if different passes end up at + * different places (but possible due to IO errors). */ + if (info->end_transaction != next_commit_ID) { + printk (KERN_ERR "JBD: recovery pass %d ended at " + "transaction %u, expected %u\n", + pass, next_commit_ID, info->end_transaction); + if (!success) + success = -EIO; + } + } + + return success; + + failed: + return err; +} + + +/* Scan a revoke record, marking all blocks mentioned as revoked. */ + +static int scan_revoke_records(journal_t *journal, struct buffer_head *bh, + tid_t sequence, struct recovery_info *info) +{ + journal_revoke_header_t *header; + int offset, max; + + header = (journal_revoke_header_t *) bh->b_data; + offset = sizeof(journal_revoke_header_t); + max = be32_to_cpu(header->r_count); + + while (offset < max) { + unsigned long blocknr; + int err; + + blocknr = be32_to_cpu(* ((__be32 *) (bh->b_data+offset))); + offset += 4; + err = journal_set_revoke(journal, blocknr, sequence); + if (err) + return err; + ++info->nr_revokes; + } + return 0; +} diff --git a/fs/jbd/revoke.c b/fs/jbd/revoke.c new file mode 100644 index 00000000000..d327a598f86 --- /dev/null +++ b/fs/jbd/revoke.c @@ -0,0 +1,702 @@ +/* + * linux/fs/revoke.c + * + * Written by Stephen C. Tweedie <sct@redhat.com>, 2000 + * + * Copyright 2000 Red Hat corp --- All Rights Reserved + * + * This file is part of the Linux kernel and is made available under + * the terms of the GNU General Public License, version 2, or at your + * option, any later version, incorporated herein by reference. + * + * Journal revoke routines for the generic filesystem journaling code; + * part of the ext2fs journaling system. + * + * Revoke is the mechanism used to prevent old log records for deleted + * metadata from being replayed on top of newer data using the same + * blocks. The revoke mechanism is used in two separate places: + * + * + Commit: during commit we write the entire list of the current + * transaction's revoked blocks to the journal + * + * + Recovery: during recovery we record the transaction ID of all + * revoked blocks. If there are multiple revoke records in the log + * for a single block, only the last one counts, and if there is a log + * entry for a block beyond the last revoke, then that log entry still + * gets replayed. + * + * We can get interactions between revokes and new log data within a + * single transaction: + * + * Block is revoked and then journaled: + * The desired end result is the journaling of the new block, so we + * cancel the revoke before the transaction commits. + * + * Block is journaled and then revoked: + * The revoke must take precedence over the write of the block, so we + * need either to cancel the journal entry or to write the revoke + * later in the log than the log block. In this case, we choose the + * latter: journaling a block cancels any revoke record for that block + * in the current transaction, so any revoke for that block in the + * transaction must have happened after the block was journaled and so + * the revoke must take precedence. + * + * Block is revoked and then written as data: + * The data write is allowed to succeed, but the revoke is _not_ + * cancelled. We still need to prevent old log records from + * overwriting the new data. We don't even need to clear the revoke + * bit here. + * + * Revoke information on buffers is a tri-state value: + * + * RevokeValid clear: no cached revoke status, need to look it up + * RevokeValid set, Revoked clear: + * buffer has not been revoked, and cancel_revoke + * need do nothing. + * RevokeValid set, Revoked set: + * buffer has been revoked. + */ + +#ifndef __KERNEL__ +#include "jfs_user.h" +#else +#include <linux/time.h> +#include <linux/fs.h> +#include <linux/jbd.h> +#include <linux/errno.h> +#include <linux/slab.h> +#include <linux/list.h> +#include <linux/smp_lock.h> +#include <linux/init.h> +#endif + +static kmem_cache_t *revoke_record_cache; +static kmem_cache_t *revoke_table_cache; + +/* Each revoke record represents one single revoked block. During + journal replay, this involves recording the transaction ID of the + last transaction to revoke this block. */ + +struct jbd_revoke_record_s +{ + struct list_head hash; + tid_t sequence; /* Used for recovery only */ + unsigned long blocknr; +}; + + +/* The revoke table is just a simple hash table of revoke records. */ +struct jbd_revoke_table_s +{ + /* It is conceivable that we might want a larger hash table + * for recovery. Must be a power of two. */ + int hash_size; + int hash_shift; + struct list_head *hash_table; +}; + + +#ifdef __KERNEL__ +static void write_one_revoke_record(journal_t *, transaction_t *, + struct journal_head **, int *, + struct jbd_revoke_record_s *); +static void flush_descriptor(journal_t *, struct journal_head *, int); +#endif + +/* Utility functions to maintain the revoke table */ + +/* Borrowed from buffer.c: this is a tried and tested block hash function */ +static inline int hash(journal_t *journal, unsigned long block) +{ + struct jbd_revoke_table_s *table = journal->j_revoke; + int hash_shift = table->hash_shift; + + return ((block << (hash_shift - 6)) ^ + (block >> 13) ^ + (block << (hash_shift - 12))) & (table->hash_size - 1); +} + +int insert_revoke_hash(journal_t *journal, unsigned long blocknr, tid_t seq) +{ + struct list_head *hash_list; + struct jbd_revoke_record_s *record; + +repeat: + record = kmem_cache_alloc(revoke_record_cache, GFP_NOFS); + if (!record) + goto oom; + + record->sequence = seq; + record->blocknr = blocknr; + hash_list = &journal->j_revoke->hash_table[hash(journal, blocknr)]; + spin_lock(&journal->j_revoke_lock); + list_add(&record->hash, hash_list); + spin_unlock(&journal->j_revoke_lock); + return 0; + +oom: + if (!journal_oom_retry) + return -ENOMEM; + jbd_debug(1, "ENOMEM in %s, retrying\n", __FUNCTION__); + yield(); + goto repeat; +} + +/* Find a revoke record in the journal's hash table. */ + +static struct jbd_revoke_record_s *find_revoke_record(journal_t *journal, + unsigned long blocknr) +{ + struct list_head *hash_list; + struct jbd_revoke_record_s *record; + + hash_list = &journal->j_revoke->hash_table[hash(journal, blocknr)]; + + spin_lock(&journal->j_revoke_lock); + record = (struct jbd_revoke_record_s *) hash_list->next; + while (&(record->hash) != hash_list) { + if (record->blocknr == blocknr) { + spin_unlock(&journal->j_revoke_lock); + return record; + } + record = (struct jbd_revoke_record_s *) record->hash.next; + } + spin_unlock(&journal->j_revoke_lock); + return NULL; +} + +int __init journal_init_revoke_caches(void) +{ + revoke_record_cache = kmem_cache_create("revoke_record", + sizeof(struct jbd_revoke_record_s), + 0, SLAB_HWCACHE_ALIGN, NULL, NULL); + if (revoke_record_cache == 0) + return -ENOMEM; + + revoke_table_cache = kmem_cache_create("revoke_table", + sizeof(struct jbd_revoke_table_s), + 0, 0, NULL, NULL); + if (revoke_table_cache == 0) { + kmem_cache_destroy(revoke_record_cache); + revoke_record_cache = NULL; + return -ENOMEM; + } + return 0; +} + +void journal_destroy_revoke_caches(void) +{ + kmem_cache_destroy(revoke_record_cache); + revoke_record_cache = NULL; + kmem_cache_destroy(revoke_table_cache); + revoke_table_cache = NULL; +} + +/* Initialise the revoke table for a given journal to a given size. */ + +int journal_init_revoke(journal_t *journal, int hash_size) +{ + int shift, tmp; + + J_ASSERT (journal->j_revoke_table[0] == NULL); + + shift = 0; + tmp = hash_size; + while((tmp >>= 1UL) != 0UL) + shift++; + + journal->j_revoke_table[0] = kmem_cache_alloc(revoke_table_cache, GFP_KERNEL); + if (!journal->j_revoke_table[0]) + return -ENOMEM; + journal->j_revoke = journal->j_revoke_table[0]; + + /* Check that the hash_size is a power of two */ + J_ASSERT ((hash_size & (hash_size-1)) == 0); + + journal->j_revoke->hash_size = hash_size; + + journal->j_revoke->hash_shift = shift; + + journal->j_revoke->hash_table = + kmalloc(hash_size * sizeof(struct list_head), GFP_KERNEL); + if (!journal->j_revoke->hash_table) { + kmem_cache_free(revoke_table_cache, journal->j_revoke_table[0]); + journal->j_revoke = NULL; + return -ENOMEM; + } + + for (tmp = 0; tmp < hash_size; tmp++) + INIT_LIST_HEAD(&journal->j_revoke->hash_table[tmp]); + + journal->j_revoke_table[1] = kmem_cache_alloc(revoke_table_cache, GFP_KERNEL); + if (!journal->j_revoke_table[1]) { + kfree(journal->j_revoke_table[0]->hash_table); + kmem_cache_free(revoke_table_cache, journal->j_revoke_table[0]); + return -ENOMEM; + } + + journal->j_revoke = journal->j_revoke_table[1]; + + /* Check that the hash_size is a power of two */ + J_ASSERT ((hash_size & (hash_size-1)) == 0); + + journal->j_revoke->hash_size = hash_size; + + journal->j_revoke->hash_shift = shift; + + journal->j_revoke->hash_table = + kmalloc(hash_size * sizeof(struct list_head), GFP_KERNEL); + if (!journal->j_revoke->hash_table) { + kfree(journal->j_revoke_table[0]->hash_table); + kmem_cache_free(revoke_table_cache, journal->j_revoke_table[0]); + kmem_cache_free(revoke_table_cache, journal->j_revoke_table[1]); + journal->j_revoke = NULL; + return -ENOMEM; + } + + for (tmp = 0; tmp < hash_size; tmp++) + INIT_LIST_HEAD(&journal->j_revoke->hash_table[tmp]); + + spin_lock_init(&journal->j_revoke_lock); + + return 0; +} + +/* Destoy a journal's revoke table. The table must already be empty! */ + +void journal_destroy_revoke(journal_t *journal) +{ + struct jbd_revoke_table_s *table; + struct list_head *hash_list; + int i; + + table = journal->j_revoke_table[0]; + if (!table) + return; + + for (i=0; i<table->hash_size; i++) { + hash_list = &table->hash_table[i]; + J_ASSERT (list_empty(hash_list)); + } + + kfree(table->hash_table); + kmem_cache_free(revoke_table_cache, table); + journal->j_revoke = NULL; + + table = journal->j_revoke_table[1]; + if (!table) + return; + + for (i=0; i<table->hash_size; i++) { + hash_list = &table->hash_table[i]; + J_ASSERT (list_empty(hash_list)); + } + + kfree(table->hash_table); + kmem_cache_free(revoke_table_cache, table); + journal->j_revoke = NULL; +} + + +#ifdef __KERNEL__ + +/* + * journal_revoke: revoke a given buffer_head from the journal. This + * prevents the block from being replayed during recovery if we take a + * crash after this current transaction commits. Any subsequent + * metadata writes of the buffer in this transaction cancel the + * revoke. + * + * Note that this call may block --- it is up to the caller to make + * sure that there are no further calls to journal_write_metadata + * before the revoke is complete. In ext3, this implies calling the + * revoke before clearing the block bitmap when we are deleting + * metadata. + * + * Revoke performs a journal_forget on any buffer_head passed in as a + * parameter, but does _not_ forget the buffer_head if the bh was only + * found implicitly. + * + * bh_in may not be a journalled buffer - it may have come off + * the hash tables without an attached journal_head. + * + * If bh_in is non-zero, journal_revoke() will decrement its b_count + * by one. + */ + +int journal_revoke(handle_t *handle, unsigned long blocknr, + struct buffer_head *bh_in) +{ + struct buffer_head *bh = NULL; + journal_t *journal; + struct block_device *bdev; + int err; + + might_sleep(); + if (bh_in) + BUFFER_TRACE(bh_in, "enter"); + + journal = handle->h_transaction->t_journal; + if (!journal_set_features(journal, 0, 0, JFS_FEATURE_INCOMPAT_REVOKE)){ + J_ASSERT (!"Cannot set revoke feature!"); + return -EINVAL; + } + + bdev = journal->j_fs_dev; + bh = bh_in; + + if (!bh) { + bh = __find_get_block(bdev, blocknr, journal->j_blocksize); + if (bh) + BUFFER_TRACE(bh, "found on hash"); + } +#ifdef JBD_EXPENSIVE_CHECKING + else { + struct buffer_head *bh2; + + /* If there is a different buffer_head lying around in + * memory anywhere... */ + bh2 = __find_get_block(bdev, blocknr, journal->j_blocksize); + if (bh2) { + /* ... and it has RevokeValid status... */ + if (bh2 != bh && buffer_revokevalid(bh2)) + /* ...then it better be revoked too, + * since it's illegal to create a revoke + * record against a buffer_head which is + * not marked revoked --- that would + * risk missing a subsequent revoke + * cancel. */ + J_ASSERT_BH(bh2, buffer_revoked(bh2)); + put_bh(bh2); + } + } +#endif + + /* We really ought not ever to revoke twice in a row without + first having the revoke cancelled: it's illegal to free a + block twice without allocating it in between! */ + if (bh) { + if (!J_EXPECT_BH(bh, !buffer_revoked(bh), + "inconsistent data on disk")) { + if (!bh_in) + brelse(bh); + return -EIO; + } + set_buffer_revoked(bh); + set_buffer_revokevalid(bh); + if (bh_in) { + BUFFER_TRACE(bh_in, "call journal_forget"); + journal_forget(handle, bh_in); + } else { + BUFFER_TRACE(bh, "call brelse"); + __brelse(bh); + } + } + + jbd_debug(2, "insert revoke for block %lu, bh_in=%p\n", blocknr, bh_in); + err = insert_revoke_hash(journal, blocknr, + handle->h_transaction->t_tid); + BUFFER_TRACE(bh_in, "exit"); + return err; +} + +/* + * Cancel an outstanding revoke. For use only internally by the + * journaling code (called from journal_get_write_access). + * + * We trust buffer_revoked() on the buffer if the buffer is already + * being journaled: if there is no revoke pending on the buffer, then we + * don't do anything here. + * + * This would break if it were possible for a buffer to be revoked and + * discarded, and then reallocated within the same transaction. In such + * a case we would have lost the revoked bit, but when we arrived here + * the second time we would still have a pending revoke to cancel. So, + * do not trust the Revoked bit on buffers unless RevokeValid is also + * set. + * + * The caller must have the journal locked. + */ +int journal_cancel_revoke(handle_t *handle, struct journal_head *jh) +{ + struct jbd_revoke_record_s *record; + journal_t *journal = handle->h_transaction->t_journal; + int need_cancel; + int did_revoke = 0; /* akpm: debug */ + struct buffer_head *bh = jh2bh(jh); + + jbd_debug(4, "journal_head %p, cancelling revoke\n", jh); + + /* Is the existing Revoke bit valid? If so, we trust it, and + * only perform the full cancel if the revoke bit is set. If + * not, we can't trust the revoke bit, and we need to do the + * full search for a revoke record. */ + if (test_set_buffer_revokevalid(bh)) { + need_cancel = test_clear_buffer_revoked(bh); + } else { + need_cancel = 1; + clear_buffer_revoked(bh); + } + + if (need_cancel) { + record = find_revoke_record(journal, bh->b_blocknr); + if (record) { + jbd_debug(4, "cancelled existing revoke on " + "blocknr %llu\n", (unsigned long long)bh->b_blocknr); + spin_lock(&journal->j_revoke_lock); + list_del(&record->hash); + spin_unlock(&journal->j_revoke_lock); + kmem_cache_free(revoke_record_cache, record); + did_revoke = 1; + } + } + +#ifdef JBD_EXPENSIVE_CHECKING + /* There better not be one left behind by now! */ + record = find_revoke_record(journal, bh->b_blocknr); + J_ASSERT_JH(jh, record == NULL); +#endif + + /* Finally, have we just cleared revoke on an unhashed + * buffer_head? If so, we'd better make sure we clear the + * revoked status on any hashed alias too, otherwise the revoke + * state machine will get very upset later on. */ + if (need_cancel) { + struct buffer_head *bh2; + bh2 = __find_get_block(bh->b_bdev, bh->b_blocknr, bh->b_size); + if (bh2) { + if (bh2 != bh) + clear_buffer_revoked(bh2); + __brelse(bh2); + } + } + return did_revoke; +} + +/* journal_switch_revoke table select j_revoke for next transaction + * we do not want to suspend any processing until all revokes are + * written -bzzz + */ +void journal_switch_revoke_table(journal_t *journal) +{ + int i; + + if (journal->j_revoke == journal->j_revoke_table[0]) + journal->j_revoke = journal->j_revoke_table[1]; + else + journal->j_revoke = journal->j_revoke_table[0]; + + for (i = 0; i < journal->j_revoke->hash_size; i++) + INIT_LIST_HEAD(&journal->j_revoke->hash_table[i]); +} + +/* + * Write revoke records to the journal for all entries in the current + * revoke hash, deleting the entries as we go. + * + * Called with the journal lock held. + */ + +void journal_write_revoke_records(journal_t *journal, + transaction_t *transaction) +{ + struct journal_head *descriptor; + struct jbd_revoke_record_s *record; + struct jbd_revoke_table_s *revoke; + struct list_head *hash_list; + int i, offset, count; + + descriptor = NULL; + offset = 0; + count = 0; + + /* select revoke table for committing transaction */ + revoke = journal->j_revoke == journal->j_revoke_table[0] ? + journal->j_revoke_table[1] : journal->j_revoke_table[0]; + + for (i = 0; i < revoke->hash_size; i++) { + hash_list = &revoke->hash_table[i]; + + while (!list_empty(hash_list)) { + record = (struct jbd_revoke_record_s *) + hash_list->next; + write_one_revoke_record(journal, transaction, + &descriptor, &offset, + record); + count++; + list_del(&record->hash); + kmem_cache_free(revoke_record_cache, record); + } + } + if (descriptor) + flush_descriptor(journal, descriptor, offset); + jbd_debug(1, "Wrote %d revoke records\n", count); +} + +/* + * Write out one revoke record. We need to create a new descriptor + * block if the old one is full or if we have not already created one. + */ + +static void write_one_revoke_record(journal_t *journal, + transaction_t *transaction, + struct journal_head **descriptorp, + int *offsetp, + struct jbd_revoke_record_s *record) +{ + struct journal_head *descriptor; + int offset; + journal_header_t *header; + + /* If we are already aborting, this all becomes a noop. We + still need to go round the loop in + journal_write_revoke_records in order to free all of the + revoke records: only the IO to the journal is omitted. */ + if (is_journal_aborted(journal)) + return; + + descriptor = *descriptorp; + offset = *offsetp; + + /* Make sure we have a descriptor with space left for the record */ + if (descriptor) { + if (offset == journal->j_blocksize) { + flush_descriptor(journal, descriptor, offset); + descriptor = NULL; + } + } + + if (!descriptor) { + descriptor = journal_get_descriptor_buffer(journal); + if (!descriptor) + return; + header = (journal_header_t *) &jh2bh(descriptor)->b_data[0]; + header->h_magic = cpu_to_be32(JFS_MAGIC_NUMBER); + header->h_blocktype = cpu_to_be32(JFS_REVOKE_BLOCK); + header->h_sequence = cpu_to_be32(transaction->t_tid); + + /* Record it so that we can wait for IO completion later */ + JBUFFER_TRACE(descriptor, "file as BJ_LogCtl"); + journal_file_buffer(descriptor, transaction, BJ_LogCtl); + + offset = sizeof(journal_revoke_header_t); + *descriptorp = descriptor; + } + + * ((__be32 *)(&jh2bh(descriptor)->b_data[offset])) = + cpu_to_be32(record->blocknr); + offset += 4; + *offsetp = offset; +} + +/* + * Flush a revoke descriptor out to the journal. If we are aborting, + * this is a noop; otherwise we are generating a buffer which needs to + * be waited for during commit, so it has to go onto the appropriate + * journal buffer list. + */ + +static void flush_descriptor(journal_t *journal, + struct journal_head *descriptor, + int offset) +{ + journal_revoke_header_t *header; + struct buffer_head *bh = jh2bh(descriptor); + + if (is_journal_aborted(journal)) { + put_bh(bh); + return; + } + + header = (journal_revoke_header_t *) jh2bh(descriptor)->b_data; + header->r_count = cpu_to_be32(offset); + set_buffer_jwrite(bh); + BUFFER_TRACE(bh, "write"); + set_buffer_dirty(bh); + ll_rw_block(WRITE, 1, &bh); +} +#endif + +/* + * Revoke support for recovery. + * + * Recovery needs to be able to: + * + * record all revoke records, including the tid of the latest instance + * of each revoke in the journal + * + * check whether a given block in a given transaction should be replayed + * (ie. has not been revoked by a revoke record in that or a subsequent + * transaction) + * + * empty the revoke table after recovery. + */ + +/* + * First, setting revoke records. We create a new revoke record for + * every block ever revoked in the log as we scan it for recovery, and + * we update the existing records if we find multiple revokes for a + * single block. + */ + +int journal_set_revoke(journal_t *journal, + unsigned long blocknr, + tid_t sequence) +{ + struct jbd_revoke_record_s *record; + + record = find_revoke_record(journal, blocknr); + if (record) { + /* If we have multiple occurrences, only record the + * latest sequence number in the hashed record */ + if (tid_gt(sequence, record->sequence)) + record->sequence = sequence; + return 0; + } + return insert_revoke_hash(journal, blocknr, sequence); +} + +/* + * Test revoke records. For a given block referenced in the log, has + * that block been revoked? A revoke record with a given transaction + * sequence number revokes all blocks in that transaction and earlier + * ones, but later transactions still need replayed. + */ + +int journal_test_revoke(journal_t *journal, + unsigned long blocknr, + tid_t sequence) +{ + struct jbd_revoke_record_s *record; + + record = find_revoke_record(journal, blocknr); + if (!record) + return 0; + if (tid_gt(sequence, record->sequence)) + return 0; + return 1; +} + +/* + * Finally, once recovery is over, we need to clear the revoke table so + * that it can be reused by the running filesystem. + */ + +void journal_clear_revoke(journal_t *journal) +{ + int i; + struct list_head *hash_list; + struct jbd_revoke_record_s *record; + struct jbd_revoke_table_s *revoke; + + revoke = journal->j_revoke; + + for (i = 0; i < revoke->hash_size; i++) { + hash_list = &revoke->hash_table[i]; + while (!list_empty(hash_list)) { + record = (struct jbd_revoke_record_s*) hash_list->next; + list_del(&record->hash); + kmem_cache_free(revoke_record_cache, record); + } + } +} diff --git a/fs/jbd/transaction.c b/fs/jbd/transaction.c new file mode 100644 index 00000000000..932e7c1ef4a --- /dev/null +++ b/fs/jbd/transaction.c @@ -0,0 +1,2062 @@ +/* + * linux/fs/transaction.c + * + * Written by Stephen C. Tweedie <sct@redhat.com>, 1998 + * + * Copyright 1998 Red Hat corp --- All Rights Reserved + * + * This file is part of the Linux kernel and is made available under + * the terms of the GNU General Public License, version 2, or at your + * option, any later version, incorporated herein by reference. + * + * Generic filesystem transaction handling code; part of the ext2fs + * journaling system. + * + * This file manages transactions (compound commits managed by the + * journaling code) and handles (individual atomic operations by the + * filesystem). + */ + +#include <linux/time.h> +#include <linux/fs.h> +#include <linux/jbd.h> +#include <linux/errno.h> +#include <linux/slab.h> +#include <linux/timer.h> +#include <linux/smp_lock.h> +#include <linux/mm.h> +#include <linux/highmem.h> + +/* + * get_transaction: obtain a new transaction_t object. + * + * Simply allocate and initialise a new transaction. Create it in + * RUNNING state and add it to the current journal (which should not + * have an existing running transaction: we only make a new transaction + * once we have started to commit the old one). + * + * Preconditions: + * The journal MUST be locked. We don't perform atomic mallocs on the + * new transaction and we can't block without protecting against other + * processes trying to touch the journal while it is in transition. + * + * Called under j_state_lock + */ + +static transaction_t * +get_transaction(journal_t *journal, transaction_t *transaction) +{ + transaction->t_journal = journal; + transaction->t_state = T_RUNNING; + transaction->t_tid = journal->j_transaction_sequence++; + transaction->t_expires = jiffies + journal->j_commit_interval; + spin_lock_init(&transaction->t_handle_lock); + + /* Set up the commit timer for the new transaction. */ + journal->j_commit_timer->expires = transaction->t_expires; + add_timer(journal->j_commit_timer); + + J_ASSERT(journal->j_running_transaction == NULL); + journal->j_running_transaction = transaction; + + return transaction; +} + +/* + * Handle management. + * + * A handle_t is an object which represents a single atomic update to a + * filesystem, and which tracks all of the modifications which form part + * of that one update. + */ + +/* + * start_this_handle: Given a handle, deal with any locking or stalling + * needed to make sure that there is enough journal space for the handle + * to begin. Attach the handle to a transaction and set up the + * transaction's buffer credits. + */ + +static int start_this_handle(journal_t *journal, handle_t *handle) +{ + transaction_t *transaction; + int needed; + int nblocks = handle->h_buffer_credits; + transaction_t *new_transaction = NULL; + int ret = 0; + + if (nblocks > journal->j_max_transaction_buffers) { + printk(KERN_ERR "JBD: %s wants too many credits (%d > %d)\n", + current->comm, nblocks, + journal->j_max_transaction_buffers); + ret = -ENOSPC; + goto out; + } + +alloc_transaction: + if (!journal->j_running_transaction) { + new_transaction = jbd_kmalloc(sizeof(*new_transaction), + GFP_NOFS); + if (!new_transaction) { + ret = -ENOMEM; + goto out; + } + memset(new_transaction, 0, sizeof(*new_transaction)); + } + + jbd_debug(3, "New handle %p going live.\n", handle); + +repeat: + + /* + * We need to hold j_state_lock until t_updates has been incremented, + * for proper journal barrier handling + */ + spin_lock(&journal->j_state_lock); +repeat_locked: + if (is_journal_aborted(journal) || + (journal->j_errno != 0 && !(journal->j_flags & JFS_ACK_ERR))) { + spin_unlock(&journal->j_state_lock); + ret = -EROFS; + goto out; + } + + /* Wait on the journal's transaction barrier if necessary */ + if (journal->j_barrier_count) { + spin_unlock(&journal->j_state_lock); + wait_event(journal->j_wait_transaction_locked, + journal->j_barrier_count == 0); + goto repeat; + } + + if (!journal->j_running_transaction) { + if (!new_transaction) { + spin_unlock(&journal->j_state_lock); + goto alloc_transaction; + } + get_transaction(journal, new_transaction); + new_transaction = NULL; + } + + transaction = journal->j_running_transaction; + + /* + * If the current transaction is locked down for commit, wait for the + * lock to be released. + */ + if (transaction->t_state == T_LOCKED) { + DEFINE_WAIT(wait); + + prepare_to_wait(&journal->j_wait_transaction_locked, + &wait, TASK_UNINTERRUPTIBLE); + spin_unlock(&journal->j_state_lock); + schedule(); + finish_wait(&journal->j_wait_transaction_locked, &wait); + goto repeat; + } + + /* + * If there is not enough space left in the log to write all potential + * buffers requested by this operation, we need to stall pending a log + * checkpoint to free some more log space. + */ + spin_lock(&transaction->t_handle_lock); + needed = transaction->t_outstanding_credits + nblocks; + + if (needed > journal->j_max_transaction_buffers) { + /* + * If the current transaction is already too large, then start + * to commit it: we can then go back and attach this handle to + * a new transaction. + */ + DEFINE_WAIT(wait); + + jbd_debug(2, "Handle %p starting new commit...\n", handle); + spin_unlock(&transaction->t_handle_lock); + prepare_to_wait(&journal->j_wait_transaction_locked, &wait, + TASK_UNINTERRUPTIBLE); + __log_start_commit(journal, transaction->t_tid); + spin_unlock(&journal->j_state_lock); + schedule(); + finish_wait(&journal->j_wait_transaction_locked, &wait); + goto repeat; + } + + /* + * The commit code assumes that it can get enough log space + * without forcing a checkpoint. This is *critical* for + * correctness: a checkpoint of a buffer which is also + * associated with a committing transaction creates a deadlock, + * so commit simply cannot force through checkpoints. + * + * We must therefore ensure the necessary space in the journal + * *before* starting to dirty potentially checkpointed buffers + * in the new transaction. + * + * The worst part is, any transaction currently committing can + * reduce the free space arbitrarily. Be careful to account for + * those buffers when checkpointing. + */ + + /* + * @@@ AKPM: This seems rather over-defensive. We're giving commit + * a _lot_ of headroom: 1/4 of the journal plus the size of + * the committing transaction. Really, we only need to give it + * committing_transaction->t_outstanding_credits plus "enough" for + * the log control blocks. + * Also, this test is inconsitent with the matching one in + * journal_extend(). + */ + if (__log_space_left(journal) < jbd_space_needed(journal)) { + jbd_debug(2, "Handle %p waiting for checkpoint...\n", handle); + spin_unlock(&transaction->t_handle_lock); + __log_wait_for_space(journal); + goto repeat_locked; + } + + /* OK, account for the buffers that this operation expects to + * use and add the handle to the running transaction. */ + + handle->h_transaction = transaction; + transaction->t_outstanding_credits += nblocks; + transaction->t_updates++; + transaction->t_handle_count++; + jbd_debug(4, "Handle %p given %d credits (total %d, free %d)\n", + handle, nblocks, transaction->t_outstanding_credits, + __log_space_left(journal)); + spin_unlock(&transaction->t_handle_lock); + spin_unlock(&journal->j_state_lock); +out: + if (new_transaction) + kfree(new_transaction); + return ret; +} + +/* Allocate a new handle. This should probably be in a slab... */ +static handle_t *new_handle(int nblocks) +{ + handle_t *handle = jbd_alloc_handle(GFP_NOFS); + if (!handle) + return NULL; + memset(handle, 0, sizeof(*handle)); + handle->h_buffer_credits = nblocks; + handle->h_ref = 1; + + return handle; +} + +/** + * handle_t *journal_start() - Obtain a new handle. + * @journal: Journal to start transaction on. + * @nblocks: number of block buffer we might modify + * + * We make sure that the transaction can guarantee at least nblocks of + * modified buffers in the log. We block until the log can guarantee + * that much space. + * + * This function is visible to journal users (like ext3fs), so is not + * called with the journal already locked. + * + * Return a pointer to a newly allocated handle, or NULL on failure + */ +handle_t *journal_start(journal_t *journal, int nblocks) +{ + handle_t *handle = journal_current_handle(); + int err; + + if (!journal) + return ERR_PTR(-EROFS); + + if (handle) { + J_ASSERT(handle->h_transaction->t_journal == journal); + handle->h_ref++; + return handle; + } + + handle = new_handle(nblocks); + if (!handle) + return ERR_PTR(-ENOMEM); + + current->journal_info = handle; + + err = start_this_handle(journal, handle); + if (err < 0) { + jbd_free_handle(handle); + current->journal_info = NULL; + handle = ERR_PTR(err); + } + return handle; +} + +/** + * int journal_extend() - extend buffer credits. + * @handle: handle to 'extend' + * @nblocks: nr blocks to try to extend by. + * + * Some transactions, such as large extends and truncates, can be done + * atomically all at once or in several stages. The operation requests + * a credit for a number of buffer modications in advance, but can + * extend its credit if it needs more. + * + * journal_extend tries to give the running handle more buffer credits. + * It does not guarantee that allocation - this is a best-effort only. + * The calling process MUST be able to deal cleanly with a failure to + * extend here. + * + * Return 0 on success, non-zero on failure. + * + * return code < 0 implies an error + * return code > 0 implies normal transaction-full status. + */ +int journal_extend(handle_t *handle, int nblocks) +{ + transaction_t *transaction = handle->h_transaction; + journal_t *journal = transaction->t_journal; + int result; + int wanted; + + result = -EIO; + if (is_handle_aborted(handle)) + goto out; + + result = 1; + + spin_lock(&journal->j_state_lock); + + /* Don't extend a locked-down transaction! */ + if (handle->h_transaction->t_state != T_RUNNING) { + jbd_debug(3, "denied handle %p %d blocks: " + "transaction not running\n", handle, nblocks); + goto error_out; + } + + spin_lock(&transaction->t_handle_lock); + wanted = transaction->t_outstanding_credits + nblocks; + + if (wanted > journal->j_max_transaction_buffers) { + jbd_debug(3, "denied handle %p %d blocks: " + "transaction too large\n", handle, nblocks); + goto unlock; + } + + if (wanted > __log_space_left(journal)) { + jbd_debug(3, "denied handle %p %d blocks: " + "insufficient log space\n", handle, nblocks); + goto unlock; + } + + handle->h_buffer_credits += nblocks; + transaction->t_outstanding_credits += nblocks; + result = 0; + + jbd_debug(3, "extended handle %p by %d\n", handle, nblocks); +unlock: + spin_unlock(&transaction->t_handle_lock); +error_out: + spin_unlock(&journal->j_state_lock); +out: + return result; +} + + +/** + * int journal_restart() - restart a handle . + * @handle: handle to restart + * @nblocks: nr credits requested + * + * Restart a handle for a multi-transaction filesystem + * operation. + * + * If the journal_extend() call above fails to grant new buffer credits + * to a running handle, a call to journal_restart will commit the + * handle's transaction so far and reattach the handle to a new + * transaction capabable of guaranteeing the requested number of + * credits. + */ + +int journal_restart(handle_t *handle, int nblocks) +{ + transaction_t *transaction = handle->h_transaction; + journal_t *journal = transaction->t_journal; + int ret; + + /* If we've had an abort of any type, don't even think about + * actually doing the restart! */ + if (is_handle_aborted(handle)) + return 0; + + /* + * First unlink the handle from its current transaction, and start the + * commit on that. + */ + J_ASSERT(transaction->t_updates > 0); + J_ASSERT(journal_current_handle() == handle); + + spin_lock(&journal->j_state_lock); + spin_lock(&transaction->t_handle_lock); + transaction->t_outstanding_credits -= handle->h_buffer_credits; + transaction->t_updates--; + + if (!transaction->t_updates) + wake_up(&journal->j_wait_updates); + spin_unlock(&transaction->t_handle_lock); + + jbd_debug(2, "restarting handle %p\n", handle); + __log_start_commit(journal, transaction->t_tid); + spin_unlock(&journal->j_state_lock); + + handle->h_buffer_credits = nblocks; + ret = start_this_handle(journal, handle); + return ret; +} + + +/** + * void journal_lock_updates () - establish a transaction barrier. + * @journal: Journal to establish a barrier on. + * + * This locks out any further updates from being started, and blocks + * until all existing updates have completed, returning only once the + * journal is in a quiescent state with no updates running. + * + * The journal lock should not be held on entry. + */ +void journal_lock_updates(journal_t *journal) +{ + DEFINE_WAIT(wait); + + spin_lock(&journal->j_state_lock); + ++journal->j_barrier_count; + + /* Wait until there are no running updates */ + while (1) { + transaction_t *transaction = journal->j_running_transaction; + + if (!transaction) + break; + + spin_lock(&transaction->t_handle_lock); + if (!transaction->t_updates) { + spin_unlock(&transaction->t_handle_lock); + break; + } + prepare_to_wait(&journal->j_wait_updates, &wait, + TASK_UNINTERRUPTIBLE); + spin_unlock(&transaction->t_handle_lock); + spin_unlock(&journal->j_state_lock); + schedule(); + finish_wait(&journal->j_wait_updates, &wait); + spin_lock(&journal->j_state_lock); + } + spin_unlock(&journal->j_state_lock); + + /* + * We have now established a barrier against other normal updates, but + * we also need to barrier against other journal_lock_updates() calls + * to make sure that we serialise special journal-locked operations + * too. + */ + down(&journal->j_barrier); +} + +/** + * void journal_unlock_updates (journal_t* journal) - release barrier + * @journal: Journal to release the barrier on. + * + * Release a transaction barrier obtained with journal_lock_updates(). + * + * Should be called without the journal lock held. + */ +void journal_unlock_updates (journal_t *journal) +{ + J_ASSERT(journal->j_barrier_count != 0); + + up(&journal->j_barrier); + spin_lock(&journal->j_state_lock); + --journal->j_barrier_count; + spin_unlock(&journal->j_state_lock); + wake_up(&journal->j_wait_transaction_locked); +} + +/* + * Report any unexpected dirty buffers which turn up. Normally those + * indicate an error, but they can occur if the user is running (say) + * tune2fs to modify the live filesystem, so we need the option of + * continuing as gracefully as possible. # + * + * The caller should already hold the journal lock and + * j_list_lock spinlock: most callers will need those anyway + * in order to probe the buffer's journaling state safely. + */ +static void jbd_unexpected_dirty_buffer(struct journal_head *jh) +{ + struct buffer_head *bh = jh2bh(jh); + int jlist; + + if (buffer_dirty(bh)) { + /* If this buffer is one which might reasonably be dirty + * --- ie. data, or not part of this journal --- then + * we're OK to leave it alone, but otherwise we need to + * move the dirty bit to the journal's own internal + * JBDDirty bit. */ + jlist = jh->b_jlist; + + if (jlist == BJ_Metadata || jlist == BJ_Reserved || + jlist == BJ_Shadow || jlist == BJ_Forget) { + if (test_clear_buffer_dirty(jh2bh(jh))) { + set_bit(BH_JBDDirty, &jh2bh(jh)->b_state); + } + } + } +} + +/* + * If the buffer is already part of the current transaction, then there + * is nothing we need to do. If it is already part of a prior + * transaction which we are still committing to disk, then we need to + * make sure that we do not overwrite the old copy: we do copy-out to + * preserve the copy going to disk. We also account the buffer against + * the handle's metadata buffer credits (unless the buffer is already + * part of the transaction, that is). + * + */ +static int +do_get_write_access(handle_t *handle, struct journal_head *jh, + int force_copy) +{ + struct buffer_head *bh; + transaction_t *transaction; + journal_t *journal; + int error; + char *frozen_buffer = NULL; + int need_copy = 0; + + if (is_handle_aborted(handle)) + return -EROFS; + + transaction = handle->h_transaction; + journal = transaction->t_journal; + + jbd_debug(5, "buffer_head %p, force_copy %d\n", jh, force_copy); + + JBUFFER_TRACE(jh, "entry"); +repeat: + bh = jh2bh(jh); + + /* @@@ Need to check for errors here at some point. */ + + lock_buffer(bh); + jbd_lock_bh_state(bh); + + /* We now hold the buffer lock so it is safe to query the buffer + * state. Is the buffer dirty? + * + * If so, there are two possibilities. The buffer may be + * non-journaled, and undergoing a quite legitimate writeback. + * Otherwise, it is journaled, and we don't expect dirty buffers + * in that state (the buffers should be marked JBD_Dirty + * instead.) So either the IO is being done under our own + * control and this is a bug, or it's a third party IO such as + * dump(8) (which may leave the buffer scheduled for read --- + * ie. locked but not dirty) or tune2fs (which may actually have + * the buffer dirtied, ugh.) */ + + if (buffer_dirty(bh)) { + /* + * First question: is this buffer already part of the current + * transaction or the existing committing transaction? + */ + if (jh->b_transaction) { + J_ASSERT_JH(jh, + jh->b_transaction == transaction || + jh->b_transaction == + journal->j_committing_transaction); + if (jh->b_next_transaction) + J_ASSERT_JH(jh, jh->b_next_transaction == + transaction); + JBUFFER_TRACE(jh, "Unexpected dirty buffer"); + jbd_unexpected_dirty_buffer(jh); + } + } + + unlock_buffer(bh); + + error = -EROFS; + if (is_handle_aborted(handle)) { + jbd_unlock_bh_state(bh); + goto out; + } + error = 0; + + /* + * The buffer is already part of this transaction if b_transaction or + * b_next_transaction points to it + */ + if (jh->b_transaction == transaction || + jh->b_next_transaction == transaction) + goto done; + + /* + * If there is already a copy-out version of this buffer, then we don't + * need to make another one + */ + if (jh->b_frozen_data) { + JBUFFER_TRACE(jh, "has frozen data"); + J_ASSERT_JH(jh, jh->b_next_transaction == NULL); + jh->b_next_transaction = transaction; + goto done; + } + + /* Is there data here we need to preserve? */ + + if (jh->b_transaction && jh->b_transaction != transaction) { + JBUFFER_TRACE(jh, "owned by older transaction"); + J_ASSERT_JH(jh, jh->b_next_transaction == NULL); + J_ASSERT_JH(jh, jh->b_transaction == + journal->j_committing_transaction); + + /* There is one case we have to be very careful about. + * If the committing transaction is currently writing + * this buffer out to disk and has NOT made a copy-out, + * then we cannot modify the buffer contents at all + * right now. The essence of copy-out is that it is the + * extra copy, not the primary copy, which gets + * journaled. If the primary copy is already going to + * disk then we cannot do copy-out here. */ + + if (jh->b_jlist == BJ_Shadow) { + DEFINE_WAIT_BIT(wait, &bh->b_state, BH_Unshadow); + wait_queue_head_t *wqh; + + wqh = bit_waitqueue(&bh->b_state, BH_Unshadow); + + JBUFFER_TRACE(jh, "on shadow: sleep"); + jbd_unlock_bh_state(bh); + /* commit wakes up all shadow buffers after IO */ + for ( ; ; ) { + prepare_to_wait(wqh, &wait.wait, + TASK_UNINTERRUPTIBLE); + if (jh->b_jlist != BJ_Shadow) + break; + schedule(); + } + finish_wait(wqh, &wait.wait); + goto repeat; + } + + /* Only do the copy if the currently-owning transaction + * still needs it. If it is on the Forget list, the + * committing transaction is past that stage. The + * buffer had better remain locked during the kmalloc, + * but that should be true --- we hold the journal lock + * still and the buffer is already on the BUF_JOURNAL + * list so won't be flushed. + * + * Subtle point, though: if this is a get_undo_access, + * then we will be relying on the frozen_data to contain + * the new value of the committed_data record after the + * transaction, so we HAVE to force the frozen_data copy + * in that case. */ + + if (jh->b_jlist != BJ_Forget || force_copy) { + JBUFFER_TRACE(jh, "generate frozen data"); + if (!frozen_buffer) { + JBUFFER_TRACE(jh, "allocate memory for buffer"); + jbd_unlock_bh_state(bh); + frozen_buffer = jbd_kmalloc(jh2bh(jh)->b_size, + GFP_NOFS); + if (!frozen_buffer) { + printk(KERN_EMERG + "%s: OOM for frozen_buffer\n", + __FUNCTION__); + JBUFFER_TRACE(jh, "oom!"); + error = -ENOMEM; + jbd_lock_bh_state(bh); + goto done; + } + goto repeat; + } + jh->b_frozen_data = frozen_buffer; + frozen_buffer = NULL; + need_copy = 1; + } + jh->b_next_transaction = transaction; + } + + + /* + * Finally, if the buffer is not journaled right now, we need to make + * sure it doesn't get written to disk before the caller actually + * commits the new data + */ + if (!jh->b_transaction) { + JBUFFER_TRACE(jh, "no transaction"); + J_ASSERT_JH(jh, !jh->b_next_transaction); + jh->b_transaction = transaction; + JBUFFER_TRACE(jh, "file as BJ_Reserved"); + spin_lock(&journal->j_list_lock); + __journal_file_buffer(jh, transaction, BJ_Reserved); + spin_unlock(&journal->j_list_lock); + } + +done: + if (need_copy) { + struct page *page; + int offset; + char *source; + + J_EXPECT_JH(jh, buffer_uptodate(jh2bh(jh)), + "Possible IO failure.\n"); + page = jh2bh(jh)->b_page; + offset = ((unsigned long) jh2bh(jh)->b_data) & ~PAGE_MASK; + source = kmap_atomic(page, KM_USER0); + memcpy(jh->b_frozen_data, source+offset, jh2bh(jh)->b_size); + kunmap_atomic(source, KM_USER0); + } + jbd_unlock_bh_state(bh); + + /* + * If we are about to journal a buffer, then any revoke pending on it is + * no longer valid + */ + journal_cancel_revoke(handle, jh); + +out: + if (frozen_buffer) + kfree(frozen_buffer); + + JBUFFER_TRACE(jh, "exit"); + return error; +} + +/** + * int journal_get_write_access() - notify intent to modify a buffer for metadata (not data) update. + * @handle: transaction to add buffer modifications to + * @bh: bh to be used for metadata writes + * @credits: variable that will receive credits for the buffer + * + * Returns an error code or 0 on success. + * + * In full data journalling mode the buffer may be of type BJ_AsyncData, + * because we're write()ing a buffer which is also part of a shared mapping. + */ + +int journal_get_write_access(handle_t *handle, struct buffer_head *bh) +{ + struct journal_head *jh = journal_add_journal_head(bh); + int rc; + + /* We do not want to get caught playing with fields which the + * log thread also manipulates. Make sure that the buffer + * completes any outstanding IO before proceeding. */ + rc = do_get_write_access(handle, jh, 0); + journal_put_journal_head(jh); + return rc; +} + + +/* + * When the user wants to journal a newly created buffer_head + * (ie. getblk() returned a new buffer and we are going to populate it + * manually rather than reading off disk), then we need to keep the + * buffer_head locked until it has been completely filled with new + * data. In this case, we should be able to make the assertion that + * the bh is not already part of an existing transaction. + * + * The buffer should already be locked by the caller by this point. + * There is no lock ranking violation: it was a newly created, + * unlocked buffer beforehand. */ + +/** + * int journal_get_create_access () - notify intent to use newly created bh + * @handle: transaction to new buffer to + * @bh: new buffer. + * + * Call this if you create a new bh. + */ +int journal_get_create_access(handle_t *handle, struct buffer_head *bh) +{ + transaction_t *transaction = handle->h_transaction; + journal_t *journal = transaction->t_journal; + struct journal_head *jh = journal_add_journal_head(bh); + int err; + + jbd_debug(5, "journal_head %p\n", jh); + err = -EROFS; + if (is_handle_aborted(handle)) + goto out; + err = 0; + + JBUFFER_TRACE(jh, "entry"); + /* + * The buffer may already belong to this transaction due to pre-zeroing + * in the filesystem's new_block code. It may also be on the previous, + * committing transaction's lists, but it HAS to be in Forget state in + * that case: the transaction must have deleted the buffer for it to be + * reused here. + */ + jbd_lock_bh_state(bh); + spin_lock(&journal->j_list_lock); + J_ASSERT_JH(jh, (jh->b_transaction == transaction || + jh->b_transaction == NULL || + (jh->b_transaction == journal->j_committing_transaction && + jh->b_jlist == BJ_Forget))); + + J_ASSERT_JH(jh, jh->b_next_transaction == NULL); + J_ASSERT_JH(jh, buffer_locked(jh2bh(jh))); + + if (jh->b_transaction == NULL) { + jh->b_transaction = transaction; + JBUFFER_TRACE(jh, "file as BJ_Reserved"); + __journal_file_buffer(jh, transaction, BJ_Reserved); + } else if (jh->b_transaction == journal->j_committing_transaction) { + JBUFFER_TRACE(jh, "set next transaction"); + jh->b_next_transaction = transaction; + } + spin_unlock(&journal->j_list_lock); + jbd_unlock_bh_state(bh); + + /* + * akpm: I added this. ext3_alloc_branch can pick up new indirect + * blocks which contain freed but then revoked metadata. We need + * to cancel the revoke in case we end up freeing it yet again + * and the reallocating as data - this would cause a second revoke, + * which hits an assertion error. + */ + JBUFFER_TRACE(jh, "cancelling revoke"); + journal_cancel_revoke(handle, jh); + journal_put_journal_head(jh); +out: + return err; +} + +/** + * int journal_get_undo_access() - Notify intent to modify metadata with + * non-rewindable consequences + * @handle: transaction + * @bh: buffer to undo + * @credits: store the number of taken credits here (if not NULL) + * + * Sometimes there is a need to distinguish between metadata which has + * been committed to disk and that which has not. The ext3fs code uses + * this for freeing and allocating space, we have to make sure that we + * do not reuse freed space until the deallocation has been committed, + * since if we overwrote that space we would make the delete + * un-rewindable in case of a crash. + * + * To deal with that, journal_get_undo_access requests write access to a + * buffer for parts of non-rewindable operations such as delete + * operations on the bitmaps. The journaling code must keep a copy of + * the buffer's contents prior to the undo_access call until such time + * as we know that the buffer has definitely been committed to disk. + * + * We never need to know which transaction the committed data is part + * of, buffers touched here are guaranteed to be dirtied later and so + * will be committed to a new transaction in due course, at which point + * we can discard the old committed data pointer. + * + * Returns error number or 0 on success. + */ +int journal_get_undo_access(handle_t *handle, struct buffer_head *bh) +{ + int err; + struct journal_head *jh = journal_add_journal_head(bh); + char *committed_data = NULL; + + JBUFFER_TRACE(jh, "entry"); + + /* + * Do this first --- it can drop the journal lock, so we want to + * make sure that obtaining the committed_data is done + * atomically wrt. completion of any outstanding commits. + */ + err = do_get_write_access(handle, jh, 1); + if (err) + goto out; + +repeat: + if (!jh->b_committed_data) { + committed_data = jbd_kmalloc(jh2bh(jh)->b_size, GFP_NOFS); + if (!committed_data) { + printk(KERN_EMERG "%s: No memory for committed data\n", + __FUNCTION__); + err = -ENOMEM; + goto out; + } + } + + jbd_lock_bh_state(bh); + if (!jh->b_committed_data) { + /* Copy out the current buffer contents into the + * preserved, committed copy. */ + JBUFFER_TRACE(jh, "generate b_committed data"); + if (!committed_data) { + jbd_unlock_bh_state(bh); + goto repeat; + } + + jh->b_committed_data = committed_data; + committed_data = NULL; + memcpy(jh->b_committed_data, bh->b_data, bh->b_size); + } + jbd_unlock_bh_state(bh); +out: + journal_put_journal_head(jh); + if (committed_data) + kfree(committed_data); + return err; +} + +/** + * int journal_dirty_data() - mark a buffer as containing dirty data which + * needs to be flushed before we can commit the + * current transaction. + * @handle: transaction + * @bh: bufferhead to mark + * + * The buffer is placed on the transaction's data list and is marked as + * belonging to the transaction. + * + * Returns error number or 0 on success. + * + * journal_dirty_data() can be called via page_launder->ext3_writepage + * by kswapd. + */ +int journal_dirty_data(handle_t *handle, struct buffer_head *bh) +{ + journal_t *journal = handle->h_transaction->t_journal; + int need_brelse = 0; + struct journal_head *jh; + + if (is_handle_aborted(handle)) + return 0; + + jh = journal_add_journal_head(bh); + JBUFFER_TRACE(jh, "entry"); + + /* + * The buffer could *already* be dirty. Writeout can start + * at any time. + */ + jbd_debug(4, "jh: %p, tid:%d\n", jh, handle->h_transaction->t_tid); + + /* + * What if the buffer is already part of a running transaction? + * + * There are two cases: + * 1) It is part of the current running transaction. Refile it, + * just in case we have allocated it as metadata, deallocated + * it, then reallocated it as data. + * 2) It is part of the previous, still-committing transaction. + * If all we want to do is to guarantee that the buffer will be + * written to disk before this new transaction commits, then + * being sure that the *previous* transaction has this same + * property is sufficient for us! Just leave it on its old + * transaction. + * + * In case (2), the buffer must not already exist as metadata + * --- that would violate write ordering (a transaction is free + * to write its data at any point, even before the previous + * committing transaction has committed). The caller must + * never, ever allow this to happen: there's nothing we can do + * about it in this layer. + */ + jbd_lock_bh_state(bh); + spin_lock(&journal->j_list_lock); + if (jh->b_transaction) { + JBUFFER_TRACE(jh, "has transaction"); + if (jh->b_transaction != handle->h_transaction) { + JBUFFER_TRACE(jh, "belongs to older transaction"); + J_ASSERT_JH(jh, jh->b_transaction == + journal->j_committing_transaction); + + /* @@@ IS THIS TRUE ? */ + /* + * Not any more. Scenario: someone does a write() + * in data=journal mode. The buffer's transaction has + * moved into commit. Then someone does another + * write() to the file. We do the frozen data copyout + * and set b_next_transaction to point to j_running_t. + * And while we're in that state, someone does a + * writepage() in an attempt to pageout the same area + * of the file via a shared mapping. At present that + * calls journal_dirty_data(), and we get right here. + * It may be too late to journal the data. Simply + * falling through to the next test will suffice: the + * data will be dirty and wil be checkpointed. The + * ordering comments in the next comment block still + * apply. + */ + //J_ASSERT_JH(jh, jh->b_next_transaction == NULL); + + /* + * If we're journalling data, and this buffer was + * subject to a write(), it could be metadata, forget + * or shadow against the committing transaction. Now, + * someone has dirtied the same darn page via a mapping + * and it is being writepage()'d. + * We *could* just steal the page from commit, with some + * fancy locking there. Instead, we just skip it - + * don't tie the page's buffers to the new transaction + * at all. + * Implication: if we crash before the writepage() data + * is written into the filesystem, recovery will replay + * the write() data. + */ + if (jh->b_jlist != BJ_None && + jh->b_jlist != BJ_SyncData && + jh->b_jlist != BJ_Locked) { + JBUFFER_TRACE(jh, "Not stealing"); + goto no_journal; + } + + /* + * This buffer may be undergoing writeout in commit. We + * can't return from here and let the caller dirty it + * again because that can cause the write-out loop in + * commit to never terminate. + */ + if (buffer_dirty(bh)) { + get_bh(bh); + spin_unlock(&journal->j_list_lock); + jbd_unlock_bh_state(bh); + need_brelse = 1; + sync_dirty_buffer(bh); + jbd_lock_bh_state(bh); + spin_lock(&journal->j_list_lock); + /* The buffer may become locked again at any + time if it is redirtied */ + } + + /* journal_clean_data_list() may have got there first */ + if (jh->b_transaction != NULL) { + JBUFFER_TRACE(jh, "unfile from commit"); + __journal_temp_unlink_buffer(jh); + /* It still points to the committing + * transaction; move it to this one so + * that the refile assert checks are + * happy. */ + jh->b_transaction = handle->h_transaction; + } + /* The buffer will be refiled below */ + + } + /* + * Special case --- the buffer might actually have been + * allocated and then immediately deallocated in the previous, + * committing transaction, so might still be left on that + * transaction's metadata lists. + */ + if (jh->b_jlist != BJ_SyncData && jh->b_jlist != BJ_Locked) { + JBUFFER_TRACE(jh, "not on correct data list: unfile"); + J_ASSERT_JH(jh, jh->b_jlist != BJ_Shadow); + __journal_temp_unlink_buffer(jh); + jh->b_transaction = handle->h_transaction; + JBUFFER_TRACE(jh, "file as data"); + __journal_file_buffer(jh, handle->h_transaction, + BJ_SyncData); + } + } else { + JBUFFER_TRACE(jh, "not on a transaction"); + __journal_file_buffer(jh, handle->h_transaction, BJ_SyncData); + } +no_journal: + spin_unlock(&journal->j_list_lock); + jbd_unlock_bh_state(bh); + if (need_brelse) { + BUFFER_TRACE(bh, "brelse"); + __brelse(bh); + } + JBUFFER_TRACE(jh, "exit"); + journal_put_journal_head(jh); + return 0; +} + +/** + * int journal_dirty_metadata() - mark a buffer as containing dirty metadata + * @handle: transaction to add buffer to. + * @bh: buffer to mark + * + * mark dirty metadata which needs to be journaled as part of the current + * transaction. + * + * The buffer is placed on the transaction's metadata list and is marked + * as belonging to the transaction. + * + * Returns error number or 0 on success. + * + * Special care needs to be taken if the buffer already belongs to the + * current committing transaction (in which case we should have frozen + * data present for that commit). In that case, we don't relink the + * buffer: that only gets done when the old transaction finally + * completes its commit. + */ +int journal_dirty_metadata(handle_t *handle, struct buffer_head *bh) +{ + transaction_t *transaction = handle->h_transaction; + journal_t *journal = transaction->t_journal; + struct journal_head *jh = bh2jh(bh); + + jbd_debug(5, "journal_head %p\n", jh); + JBUFFER_TRACE(jh, "entry"); + if (is_handle_aborted(handle)) + goto out; + + jbd_lock_bh_state(bh); + + if (jh->b_modified == 0) { + /* + * This buffer's got modified and becoming part + * of the transaction. This needs to be done + * once a transaction -bzzz + */ + jh->b_modified = 1; + J_ASSERT_JH(jh, handle->h_buffer_credits > 0); + handle->h_buffer_credits--; + } + + /* + * fastpath, to avoid expensive locking. If this buffer is already + * on the running transaction's metadata list there is nothing to do. + * Nobody can take it off again because there is a handle open. + * I _think_ we're OK here with SMP barriers - a mistaken decision will + * result in this test being false, so we go in and take the locks. + */ + if (jh->b_transaction == transaction && jh->b_jlist == BJ_Metadata) { + JBUFFER_TRACE(jh, "fastpath"); + J_ASSERT_JH(jh, jh->b_transaction == + journal->j_running_transaction); + goto out_unlock_bh; + } + + set_buffer_jbddirty(bh); + + /* + * Metadata already on the current transaction list doesn't + * need to be filed. Metadata on another transaction's list must + * be committing, and will be refiled once the commit completes: + * leave it alone for now. + */ + if (jh->b_transaction != transaction) { + JBUFFER_TRACE(jh, "already on other transaction"); + J_ASSERT_JH(jh, jh->b_transaction == + journal->j_committing_transaction); + J_ASSERT_JH(jh, jh->b_next_transaction == transaction); + /* And this case is illegal: we can't reuse another + * transaction's data buffer, ever. */ + goto out_unlock_bh; + } + + /* That test should have eliminated the following case: */ + J_ASSERT_JH(jh, jh->b_frozen_data == 0); + + JBUFFER_TRACE(jh, "file as BJ_Metadata"); + spin_lock(&journal->j_list_lock); + __journal_file_buffer(jh, handle->h_transaction, BJ_Metadata); + spin_unlock(&journal->j_list_lock); +out_unlock_bh: + jbd_unlock_bh_state(bh); +out: + JBUFFER_TRACE(jh, "exit"); + return 0; +} + +/* + * journal_release_buffer: undo a get_write_access without any buffer + * updates, if the update decided in the end that it didn't need access. + * + */ +void +journal_release_buffer(handle_t *handle, struct buffer_head *bh) +{ + BUFFER_TRACE(bh, "entry"); +} + +/** + * void journal_forget() - bforget() for potentially-journaled buffers. + * @handle: transaction handle + * @bh: bh to 'forget' + * + * We can only do the bforget if there are no commits pending against the + * buffer. If the buffer is dirty in the current running transaction we + * can safely unlink it. + * + * bh may not be a journalled buffer at all - it may be a non-JBD + * buffer which came off the hashtable. Check for this. + * + * Decrements bh->b_count by one. + * + * Allow this call even if the handle has aborted --- it may be part of + * the caller's cleanup after an abort. + */ +int journal_forget (handle_t *handle, struct buffer_head *bh) +{ + transaction_t *transaction = handle->h_transaction; + journal_t *journal = transaction->t_journal; + struct journal_head *jh; + int drop_reserve = 0; + int err = 0; + + BUFFER_TRACE(bh, "entry"); + + jbd_lock_bh_state(bh); + spin_lock(&journal->j_list_lock); + + if (!buffer_jbd(bh)) + goto not_jbd; + jh = bh2jh(bh); + + /* Critical error: attempting to delete a bitmap buffer, maybe? + * Don't do any jbd operations, and return an error. */ + if (!J_EXPECT_JH(jh, !jh->b_committed_data, + "inconsistent data on disk")) { + err = -EIO; + goto not_jbd; + } + + /* + * The buffer's going from the transaction, we must drop + * all references -bzzz + */ + jh->b_modified = 0; + + if (jh->b_transaction == handle->h_transaction) { + J_ASSERT_JH(jh, !jh->b_frozen_data); + + /* If we are forgetting a buffer which is already part + * of this transaction, then we can just drop it from + * the transaction immediately. */ + clear_buffer_dirty(bh); + clear_buffer_jbddirty(bh); + + JBUFFER_TRACE(jh, "belongs to current transaction: unfile"); + + drop_reserve = 1; + + /* + * We are no longer going to journal this buffer. + * However, the commit of this transaction is still + * important to the buffer: the delete that we are now + * processing might obsolete an old log entry, so by + * committing, we can satisfy the buffer's checkpoint. + * + * So, if we have a checkpoint on the buffer, we should + * now refile the buffer on our BJ_Forget list so that + * we know to remove the checkpoint after we commit. + */ + + if (jh->b_cp_transaction) { + __journal_temp_unlink_buffer(jh); + __journal_file_buffer(jh, transaction, BJ_Forget); + } else { + __journal_unfile_buffer(jh); + journal_remove_journal_head(bh); + __brelse(bh); + if (!buffer_jbd(bh)) { + spin_unlock(&journal->j_list_lock); + jbd_unlock_bh_state(bh); + __bforget(bh); + goto drop; + } + } + } else if (jh->b_transaction) { + J_ASSERT_JH(jh, (jh->b_transaction == + journal->j_committing_transaction)); + /* However, if the buffer is still owned by a prior + * (committing) transaction, we can't drop it yet... */ + JBUFFER_TRACE(jh, "belongs to older transaction"); + /* ... but we CAN drop it from the new transaction if we + * have also modified it since the original commit. */ + + if (jh->b_next_transaction) { + J_ASSERT(jh->b_next_transaction == transaction); + jh->b_next_transaction = NULL; + drop_reserve = 1; + } + } + +not_jbd: + spin_unlock(&journal->j_list_lock); + jbd_unlock_bh_state(bh); + __brelse(bh); +drop: + if (drop_reserve) { + /* no need to reserve log space for this block -bzzz */ + handle->h_buffer_credits++; + } + return err; +} + +/** + * int journal_stop() - complete a transaction + * @handle: tranaction to complete. + * + * All done for a particular handle. + * + * There is not much action needed here. We just return any remaining + * buffer credits to the transaction and remove the handle. The only + * complication is that we need to start a commit operation if the + * filesystem is marked for synchronous update. + * + * journal_stop itself will not usually return an error, but it may + * do so in unusual circumstances. In particular, expect it to + * return -EIO if a journal_abort has been executed since the + * transaction began. + */ +int journal_stop(handle_t *handle) +{ + transaction_t *transaction = handle->h_transaction; + journal_t *journal = transaction->t_journal; + int old_handle_count, err; + + J_ASSERT(transaction->t_updates > 0); + J_ASSERT(journal_current_handle() == handle); + + if (is_handle_aborted(handle)) + err = -EIO; + else + err = 0; + + if (--handle->h_ref > 0) { + jbd_debug(4, "h_ref %d -> %d\n", handle->h_ref + 1, + handle->h_ref); + return err; + } + + jbd_debug(4, "Handle %p going down\n", handle); + + /* + * Implement synchronous transaction batching. If the handle + * was synchronous, don't force a commit immediately. Let's + * yield and let another thread piggyback onto this transaction. + * Keep doing that while new threads continue to arrive. + * It doesn't cost much - we're about to run a commit and sleep + * on IO anyway. Speeds up many-threaded, many-dir operations + * by 30x or more... + */ + if (handle->h_sync) { + do { + old_handle_count = transaction->t_handle_count; + set_current_state(TASK_UNINTERRUPTIBLE); + schedule_timeout(1); + } while (old_handle_count != transaction->t_handle_count); + } + + current->journal_info = NULL; + spin_lock(&journal->j_state_lock); + spin_lock(&transaction->t_handle_lock); + transaction->t_outstanding_credits -= handle->h_buffer_credits; + transaction->t_updates--; + if (!transaction->t_updates) { + wake_up(&journal->j_wait_updates); + if (journal->j_barrier_count) + wake_up(&journal->j_wait_transaction_locked); + } + + /* + * If the handle is marked SYNC, we need to set another commit + * going! We also want to force a commit if the current + * transaction is occupying too much of the log, or if the + * transaction is too old now. + */ + if (handle->h_sync || + transaction->t_outstanding_credits > + journal->j_max_transaction_buffers || + time_after_eq(jiffies, transaction->t_expires)) { + /* Do this even for aborted journals: an abort still + * completes the commit thread, it just doesn't write + * anything to disk. */ + tid_t tid = transaction->t_tid; + + spin_unlock(&transaction->t_handle_lock); + jbd_debug(2, "transaction too old, requesting commit for " + "handle %p\n", handle); + /* This is non-blocking */ + __log_start_commit(journal, transaction->t_tid); + spin_unlock(&journal->j_state_lock); + + /* + * Special case: JFS_SYNC synchronous updates require us + * to wait for the commit to complete. + */ + if (handle->h_sync && !(current->flags & PF_MEMALLOC)) + err = log_wait_commit(journal, tid); + } else { + spin_unlock(&transaction->t_handle_lock); + spin_unlock(&journal->j_state_lock); + } + + jbd_free_handle(handle); + return err; +} + +/**int journal_force_commit() - force any uncommitted transactions + * @journal: journal to force + * + * For synchronous operations: force any uncommitted transactions + * to disk. May seem kludgy, but it reuses all the handle batching + * code in a very simple manner. + */ +int journal_force_commit(journal_t *journal) +{ + handle_t *handle; + int ret; + + handle = journal_start(journal, 1); + if (IS_ERR(handle)) { + ret = PTR_ERR(handle); + } else { + handle->h_sync = 1; + ret = journal_stop(handle); + } + return ret; +} + +/* + * + * List management code snippets: various functions for manipulating the + * transaction buffer lists. + * + */ + +/* + * Append a buffer to a transaction list, given the transaction's list head + * pointer. + * + * j_list_lock is held. + * + * jbd_lock_bh_state(jh2bh(jh)) is held. + */ + +static inline void +__blist_add_buffer(struct journal_head **list, struct journal_head *jh) +{ + if (!*list) { + jh->b_tnext = jh->b_tprev = jh; + *list = jh; + } else { + /* Insert at the tail of the list to preserve order */ + struct journal_head *first = *list, *last = first->b_tprev; + jh->b_tprev = last; + jh->b_tnext = first; + last->b_tnext = first->b_tprev = jh; + } +} + +/* + * Remove a buffer from a transaction list, given the transaction's list + * head pointer. + * + * Called with j_list_lock held, and the journal may not be locked. + * + * jbd_lock_bh_state(jh2bh(jh)) is held. + */ + +static inline void +__blist_del_buffer(struct journal_head **list, struct journal_head *jh) +{ + if (*list == jh) { + *list = jh->b_tnext; + if (*list == jh) + *list = NULL; + } + jh->b_tprev->b_tnext = jh->b_tnext; + jh->b_tnext->b_tprev = jh->b_tprev; +} + +/* + * Remove a buffer from the appropriate transaction list. + * + * Note that this function can *change* the value of + * bh->b_transaction->t_sync_datalist, t_buffers, t_forget, + * t_iobuf_list, t_shadow_list, t_log_list or t_reserved_list. If the caller + * is holding onto a copy of one of thee pointers, it could go bad. + * Generally the caller needs to re-read the pointer from the transaction_t. + * + * Called under j_list_lock. The journal may not be locked. + */ +void __journal_temp_unlink_buffer(struct journal_head *jh) +{ + struct journal_head **list = NULL; + transaction_t *transaction; + struct buffer_head *bh = jh2bh(jh); + + J_ASSERT_JH(jh, jbd_is_locked_bh_state(bh)); + transaction = jh->b_transaction; + if (transaction) + assert_spin_locked(&transaction->t_journal->j_list_lock); + + J_ASSERT_JH(jh, jh->b_jlist < BJ_Types); + if (jh->b_jlist != BJ_None) + J_ASSERT_JH(jh, transaction != 0); + + switch (jh->b_jlist) { + case BJ_None: + return; + case BJ_SyncData: + list = &transaction->t_sync_datalist; + break; + case BJ_Metadata: + transaction->t_nr_buffers--; + J_ASSERT_JH(jh, transaction->t_nr_buffers >= 0); + list = &transaction->t_buffers; + break; + case BJ_Forget: + list = &transaction->t_forget; + break; + case BJ_IO: + list = &transaction->t_iobuf_list; + break; + case BJ_Shadow: + list = &transaction->t_shadow_list; + break; + case BJ_LogCtl: + list = &transaction->t_log_list; + break; + case BJ_Reserved: + list = &transaction->t_reserved_list; + break; + case BJ_Locked: + list = &transaction->t_locked_list; + break; + } + + __blist_del_buffer(list, jh); + jh->b_jlist = BJ_None; + if (test_clear_buffer_jbddirty(bh)) + mark_buffer_dirty(bh); /* Expose it to the VM */ +} + +void __journal_unfile_buffer(struct journal_head *jh) +{ + __journal_temp_unlink_buffer(jh); + jh->b_transaction = NULL; +} + +void journal_unfile_buffer(journal_t *journal, struct journal_head *jh) +{ + jbd_lock_bh_state(jh2bh(jh)); + spin_lock(&journal->j_list_lock); + __journal_unfile_buffer(jh); + spin_unlock(&journal->j_list_lock); + jbd_unlock_bh_state(jh2bh(jh)); +} + +/* + * Called from journal_try_to_free_buffers(). + * + * Called under jbd_lock_bh_state(bh) + */ +static void +__journal_try_to_free_buffer(journal_t *journal, struct buffer_head *bh) +{ + struct journal_head *jh; + + jh = bh2jh(bh); + + if (buffer_locked(bh) || buffer_dirty(bh)) + goto out; + + if (jh->b_next_transaction != 0) + goto out; + + spin_lock(&journal->j_list_lock); + if (jh->b_transaction != 0 && jh->b_cp_transaction == 0) { + if (jh->b_jlist == BJ_SyncData || jh->b_jlist == BJ_Locked) { + /* A written-back ordered data buffer */ + JBUFFER_TRACE(jh, "release data"); + __journal_unfile_buffer(jh); + journal_remove_journal_head(bh); + __brelse(bh); + } + } else if (jh->b_cp_transaction != 0 && jh->b_transaction == 0) { + /* written-back checkpointed metadata buffer */ + if (jh->b_jlist == BJ_None) { + JBUFFER_TRACE(jh, "remove from checkpoint list"); + __journal_remove_checkpoint(jh); + journal_remove_journal_head(bh); + __brelse(bh); + } + } + spin_unlock(&journal->j_list_lock); +out: + return; +} + + +/** + * int journal_try_to_free_buffers() - try to free page buffers. + * @journal: journal for operation + * @page: to try and free + * @unused_gfp_mask: unused + * + * + * For all the buffers on this page, + * if they are fully written out ordered data, move them onto BUF_CLEAN + * so try_to_free_buffers() can reap them. + * + * This function returns non-zero if we wish try_to_free_buffers() + * to be called. We do this if the page is releasable by try_to_free_buffers(). + * We also do it if the page has locked or dirty buffers and the caller wants + * us to perform sync or async writeout. + * + * This complicates JBD locking somewhat. We aren't protected by the + * BKL here. We wish to remove the buffer from its committing or + * running transaction's ->t_datalist via __journal_unfile_buffer. + * + * This may *change* the value of transaction_t->t_datalist, so anyone + * who looks at t_datalist needs to lock against this function. + * + * Even worse, someone may be doing a journal_dirty_data on this + * buffer. So we need to lock against that. journal_dirty_data() + * will come out of the lock with the buffer dirty, which makes it + * ineligible for release here. + * + * Who else is affected by this? hmm... Really the only contender + * is do_get_write_access() - it could be looking at the buffer while + * journal_try_to_free_buffer() is changing its state. But that + * cannot happen because we never reallocate freed data as metadata + * while the data is part of a transaction. Yes? + */ +int journal_try_to_free_buffers(journal_t *journal, + struct page *page, int unused_gfp_mask) +{ + struct buffer_head *head; + struct buffer_head *bh; + int ret = 0; + + J_ASSERT(PageLocked(page)); + + head = page_buffers(page); + bh = head; + do { + struct journal_head *jh; + + /* + * We take our own ref against the journal_head here to avoid + * having to add tons of locking around each instance of + * journal_remove_journal_head() and journal_put_journal_head(). + */ + jh = journal_grab_journal_head(bh); + if (!jh) + continue; + + jbd_lock_bh_state(bh); + __journal_try_to_free_buffer(journal, bh); + journal_put_journal_head(jh); + jbd_unlock_bh_state(bh); + if (buffer_jbd(bh)) + goto busy; + } while ((bh = bh->b_this_page) != head); + ret = try_to_free_buffers(page); +busy: + return ret; +} + +/* + * This buffer is no longer needed. If it is on an older transaction's + * checkpoint list we need to record it on this transaction's forget list + * to pin this buffer (and hence its checkpointing transaction) down until + * this transaction commits. If the buffer isn't on a checkpoint list, we + * release it. + * Returns non-zero if JBD no longer has an interest in the buffer. + * + * Called under j_list_lock. + * + * Called under jbd_lock_bh_state(bh). + */ +static int __dispose_buffer(struct journal_head *jh, transaction_t *transaction) +{ + int may_free = 1; + struct buffer_head *bh = jh2bh(jh); + + __journal_unfile_buffer(jh); + + if (jh->b_cp_transaction) { + JBUFFER_TRACE(jh, "on running+cp transaction"); + __journal_file_buffer(jh, transaction, BJ_Forget); + clear_buffer_jbddirty(bh); + may_free = 0; + } else { + JBUFFER_TRACE(jh, "on running transaction"); + journal_remove_journal_head(bh); + __brelse(bh); + } + return may_free; +} + +/* + * journal_invalidatepage + * + * This code is tricky. It has a number of cases to deal with. + * + * There are two invariants which this code relies on: + * + * i_size must be updated on disk before we start calling invalidatepage on the + * data. + * + * This is done in ext3 by defining an ext3_setattr method which + * updates i_size before truncate gets going. By maintaining this + * invariant, we can be sure that it is safe to throw away any buffers + * attached to the current transaction: once the transaction commits, + * we know that the data will not be needed. + * + * Note however that we can *not* throw away data belonging to the + * previous, committing transaction! + * + * Any disk blocks which *are* part of the previous, committing + * transaction (and which therefore cannot be discarded immediately) are + * not going to be reused in the new running transaction + * + * The bitmap committed_data images guarantee this: any block which is + * allocated in one transaction and removed in the next will be marked + * as in-use in the committed_data bitmap, so cannot be reused until + * the next transaction to delete the block commits. This means that + * leaving committing buffers dirty is quite safe: the disk blocks + * cannot be reallocated to a different file and so buffer aliasing is + * not possible. + * + * + * The above applies mainly to ordered data mode. In writeback mode we + * don't make guarantees about the order in which data hits disk --- in + * particular we don't guarantee that new dirty data is flushed before + * transaction commit --- so it is always safe just to discard data + * immediately in that mode. --sct + */ + +/* + * The journal_unmap_buffer helper function returns zero if the buffer + * concerned remains pinned as an anonymous buffer belonging to an older + * transaction. + * + * We're outside-transaction here. Either or both of j_running_transaction + * and j_committing_transaction may be NULL. + */ +static int journal_unmap_buffer(journal_t *journal, struct buffer_head *bh) +{ + transaction_t *transaction; + struct journal_head *jh; + int may_free = 1; + int ret; + + BUFFER_TRACE(bh, "entry"); + + /* + * It is safe to proceed here without the j_list_lock because the + * buffers cannot be stolen by try_to_free_buffers as long as we are + * holding the page lock. --sct + */ + + if (!buffer_jbd(bh)) + goto zap_buffer_unlocked; + + spin_lock(&journal->j_state_lock); + jbd_lock_bh_state(bh); + spin_lock(&journal->j_list_lock); + + jh = journal_grab_journal_head(bh); + if (!jh) + goto zap_buffer_no_jh; + + transaction = jh->b_transaction; + if (transaction == NULL) { + /* First case: not on any transaction. If it + * has no checkpoint link, then we can zap it: + * it's a writeback-mode buffer so we don't care + * if it hits disk safely. */ + if (!jh->b_cp_transaction) { + JBUFFER_TRACE(jh, "not on any transaction: zap"); + goto zap_buffer; + } + + if (!buffer_dirty(bh)) { + /* bdflush has written it. We can drop it now */ + goto zap_buffer; + } + + /* OK, it must be in the journal but still not + * written fully to disk: it's metadata or + * journaled data... */ + + if (journal->j_running_transaction) { + /* ... and once the current transaction has + * committed, the buffer won't be needed any + * longer. */ + JBUFFER_TRACE(jh, "checkpointed: add to BJ_Forget"); + ret = __dispose_buffer(jh, + journal->j_running_transaction); + journal_put_journal_head(jh); + spin_unlock(&journal->j_list_lock); + jbd_unlock_bh_state(bh); + spin_unlock(&journal->j_state_lock); + return ret; + } else { + /* There is no currently-running transaction. So the + * orphan record which we wrote for this file must have + * passed into commit. We must attach this buffer to + * the committing transaction, if it exists. */ + if (journal->j_committing_transaction) { + JBUFFER_TRACE(jh, "give to committing trans"); + ret = __dispose_buffer(jh, + journal->j_committing_transaction); + journal_put_journal_head(jh); + spin_unlock(&journal->j_list_lock); + jbd_unlock_bh_state(bh); + spin_unlock(&journal->j_state_lock); + return ret; + } else { + /* The orphan record's transaction has + * committed. We can cleanse this buffer */ + clear_buffer_jbddirty(bh); + goto zap_buffer; + } + } + } else if (transaction == journal->j_committing_transaction) { + /* If it is committing, we simply cannot touch it. We + * can remove it's next_transaction pointer from the + * running transaction if that is set, but nothing + * else. */ + JBUFFER_TRACE(jh, "on committing transaction"); + set_buffer_freed(bh); + if (jh->b_next_transaction) { + J_ASSERT(jh->b_next_transaction == + journal->j_running_transaction); + jh->b_next_transaction = NULL; + } + journal_put_journal_head(jh); + spin_unlock(&journal->j_list_lock); + jbd_unlock_bh_state(bh); + spin_unlock(&journal->j_state_lock); + return 0; + } else { + /* Good, the buffer belongs to the running transaction. + * We are writing our own transaction's data, not any + * previous one's, so it is safe to throw it away + * (remember that we expect the filesystem to have set + * i_size already for this truncate so recovery will not + * expose the disk blocks we are discarding here.) */ + J_ASSERT_JH(jh, transaction == journal->j_running_transaction); + may_free = __dispose_buffer(jh, transaction); + } + +zap_buffer: + journal_put_journal_head(jh); +zap_buffer_no_jh: + spin_unlock(&journal->j_list_lock); + jbd_unlock_bh_state(bh); + spin_unlock(&journal->j_state_lock); +zap_buffer_unlocked: + clear_buffer_dirty(bh); + J_ASSERT_BH(bh, !buffer_jbddirty(bh)); + clear_buffer_mapped(bh); + clear_buffer_req(bh); + clear_buffer_new(bh); + bh->b_bdev = NULL; + return may_free; +} + +/** + * int journal_invalidatepage() + * @journal: journal to use for flush... + * @page: page to flush + * @offset: length of page to invalidate. + * + * Reap page buffers containing data after offset in page. + * + * Return non-zero if the page's buffers were successfully reaped. + */ +int journal_invalidatepage(journal_t *journal, + struct page *page, + unsigned long offset) +{ + struct buffer_head *head, *bh, *next; + unsigned int curr_off = 0; + int may_free = 1; + + if (!PageLocked(page)) + BUG(); + if (!page_has_buffers(page)) + return 1; + + /* We will potentially be playing with lists other than just the + * data lists (especially for journaled data mode), so be + * cautious in our locking. */ + + head = bh = page_buffers(page); + do { + unsigned int next_off = curr_off + bh->b_size; + next = bh->b_this_page; + + /* AKPM: doing lock_buffer here may be overly paranoid */ + if (offset <= curr_off) { + /* This block is wholly outside the truncation point */ + lock_buffer(bh); + may_free &= journal_unmap_buffer(journal, bh); + unlock_buffer(bh); + } + curr_off = next_off; + bh = next; + + } while (bh != head); + + if (!offset) { + if (!may_free || !try_to_free_buffers(page)) + return 0; + J_ASSERT(!page_has_buffers(page)); + } + return 1; +} + +/* + * File a buffer on the given transaction list. + */ +void __journal_file_buffer(struct journal_head *jh, + transaction_t *transaction, int jlist) +{ + struct journal_head **list = NULL; + int was_dirty = 0; + struct buffer_head *bh = jh2bh(jh); + + J_ASSERT_JH(jh, jbd_is_locked_bh_state(bh)); + assert_spin_locked(&transaction->t_journal->j_list_lock); + + J_ASSERT_JH(jh, jh->b_jlist < BJ_Types); + J_ASSERT_JH(jh, jh->b_transaction == transaction || + jh->b_transaction == 0); + + if (jh->b_transaction && jh->b_jlist == jlist) + return; + + /* The following list of buffer states needs to be consistent + * with __jbd_unexpected_dirty_buffer()'s handling of dirty + * state. */ + + if (jlist == BJ_Metadata || jlist == BJ_Reserved || + jlist == BJ_Shadow || jlist == BJ_Forget) { + if (test_clear_buffer_dirty(bh) || + test_clear_buffer_jbddirty(bh)) + was_dirty = 1; + } + + if (jh->b_transaction) + __journal_temp_unlink_buffer(jh); + jh->b_transaction = transaction; + + switch (jlist) { + case BJ_None: + J_ASSERT_JH(jh, !jh->b_committed_data); + J_ASSERT_JH(jh, !jh->b_frozen_data); + return; + case BJ_SyncData: + list = &transaction->t_sync_datalist; + break; + case BJ_Metadata: + transaction->t_nr_buffers++; + list = &transaction->t_buffers; + break; + case BJ_Forget: + list = &transaction->t_forget; + break; + case BJ_IO: + list = &transaction->t_iobuf_list; + break; + case BJ_Shadow: + list = &transaction->t_shadow_list; + break; + case BJ_LogCtl: + list = &transaction->t_log_list; + break; + case BJ_Reserved: + list = &transaction->t_reserved_list; + break; + case BJ_Locked: + list = &transaction->t_locked_list; + break; + } + + __blist_add_buffer(list, jh); + jh->b_jlist = jlist; + + if (was_dirty) + set_buffer_jbddirty(bh); +} + +void journal_file_buffer(struct journal_head *jh, + transaction_t *transaction, int jlist) +{ + jbd_lock_bh_state(jh2bh(jh)); + spin_lock(&transaction->t_journal->j_list_lock); + __journal_file_buffer(jh, transaction, jlist); + spin_unlock(&transaction->t_journal->j_list_lock); + jbd_unlock_bh_state(jh2bh(jh)); +} + +/* + * Remove a buffer from its current buffer list in preparation for + * dropping it from its current transaction entirely. If the buffer has + * already started to be used by a subsequent transaction, refile the + * buffer on that transaction's metadata list. + * + * Called under journal->j_list_lock + * + * Called under jbd_lock_bh_state(jh2bh(jh)) + */ +void __journal_refile_buffer(struct journal_head *jh) +{ + int was_dirty; + struct buffer_head *bh = jh2bh(jh); + + J_ASSERT_JH(jh, jbd_is_locked_bh_state(bh)); + if (jh->b_transaction) + assert_spin_locked(&jh->b_transaction->t_journal->j_list_lock); + + /* If the buffer is now unused, just drop it. */ + if (jh->b_next_transaction == NULL) { + __journal_unfile_buffer(jh); + return; + } + + /* + * It has been modified by a later transaction: add it to the new + * transaction's metadata list. + */ + + was_dirty = test_clear_buffer_jbddirty(bh); + __journal_temp_unlink_buffer(jh); + jh->b_transaction = jh->b_next_transaction; + jh->b_next_transaction = NULL; + __journal_file_buffer(jh, jh->b_transaction, BJ_Metadata); + J_ASSERT_JH(jh, jh->b_transaction->t_state == T_RUNNING); + + if (was_dirty) + set_buffer_jbddirty(bh); +} + +/* + * For the unlocked version of this call, also make sure that any + * hanging journal_head is cleaned up if necessary. + * + * __journal_refile_buffer is usually called as part of a single locked + * operation on a buffer_head, in which the caller is probably going to + * be hooking the journal_head onto other lists. In that case it is up + * to the caller to remove the journal_head if necessary. For the + * unlocked journal_refile_buffer call, the caller isn't going to be + * doing anything else to the buffer so we need to do the cleanup + * ourselves to avoid a jh leak. + * + * *** The journal_head may be freed by this call! *** + */ +void journal_refile_buffer(journal_t *journal, struct journal_head *jh) +{ + struct buffer_head *bh = jh2bh(jh); + + jbd_lock_bh_state(bh); + spin_lock(&journal->j_list_lock); + + __journal_refile_buffer(jh); + jbd_unlock_bh_state(bh); + journal_remove_journal_head(bh); + + spin_unlock(&journal->j_list_lock); + __brelse(bh); +} |