diff options
| -rw-r--r-- | fs/btrfs/Makefile | 2 | ||||
| -rw-r--r-- | fs/btrfs/TODO | 20 | ||||
| -rw-r--r-- | fs/btrfs/async-thread.c | 10 | ||||
| -rw-r--r-- | fs/btrfs/async-thread.h | 7 | ||||
| -rw-r--r-- | fs/btrfs/bit-radix.c | 130 | ||||
| -rw-r--r-- | fs/btrfs/bit-radix.h | 33 | ||||
| -rw-r--r-- | fs/btrfs/btrfs_inode.h | 54 | ||||
| -rw-r--r-- | fs/btrfs/crc32c.h | 18 | ||||
| -rw-r--r-- | fs/btrfs/ctree.c | 127 | ||||
| -rw-r--r-- | fs/btrfs/ctree.h | 1 | ||||
| -rw-r--r-- | fs/btrfs/dir-item.c | 41 | ||||
| -rw-r--r-- | fs/btrfs/disk-io.c | 33 | ||||
| -rw-r--r-- | fs/btrfs/extent_io.c | 34 | ||||
| -rw-r--r-- | fs/btrfs/extent_map.c | 10 | ||||
| -rw-r--r-- | fs/btrfs/file.c | 44 | ||||
| -rw-r--r-- | fs/btrfs/inode.c | 189 | ||||
| -rw-r--r-- | fs/btrfs/locking.c | 13 | ||||
| -rw-r--r-- | fs/btrfs/ordered-data.c | 19 | ||||
| -rw-r--r-- | fs/btrfs/ref-cache.c | 26 | ||||
| -rw-r--r-- | fs/btrfs/ref-cache.h | 3 | ||||
| -rw-r--r-- | fs/btrfs/root-tree.c | 21 | ||||
| -rw-r--r-- | fs/btrfs/struct-funcs.c | 21 | ||||
| -rw-r--r-- | fs/btrfs/super.c | 3 | ||||
| -rw-r--r-- | fs/btrfs/transaction.c | 67 | ||||
| -rw-r--r-- | fs/btrfs/tree-defrag.c | 4 |
25 files changed, 653 insertions, 277 deletions
diff --git a/fs/btrfs/Makefile b/fs/btrfs/Makefile index d5c28557fba..48b7909ca8d 100644 --- a/fs/btrfs/Makefile +++ b/fs/btrfs/Makefile @@ -4,7 +4,7 @@ ifneq ($(KERNELRELEASE),) obj-m := btrfs.o btrfs-y := super.o ctree.o extent-tree.o print-tree.o root-tree.o dir-item.o \ file-item.o inode-item.o inode-map.o disk-io.o \ - transaction.o bit-radix.o inode.o file.o tree-defrag.o \ + transaction.o inode.o file.o tree-defrag.o \ extent_map.o sysfs.o struct-funcs.o xattr.o ordered-data.o \ extent_io.o volumes.o async-thread.o ioctl.o locking.o orphan.o \ ref-cache.o export.o tree-log.o acl.o free-space-cache.o diff --git a/fs/btrfs/TODO b/fs/btrfs/TODO deleted file mode 100644 index d9b6d38c603..00000000000 --- a/fs/btrfs/TODO +++ /dev/null @@ -1,20 +0,0 @@ -* cleanup, add more error checking, get rid of BUG_ONs -* Fix ENOSPC handling -* Make allocator smarter -* add a block group to struct inode -* Do actual block accounting -* Check compat and incompat flags on the inode -* Get rid of struct ctree_path, limiting tree levels held at one time -* Add generation number to key pointer in nodes -* Add generation number to inode -* forbid cross subvolume renames and hardlinks -* Release -* Do real tree locking -* Add extent mirroring (backup copies of blocks) -* Add fancy interface to get access to incremental backups -* Add fancy striped extents to make big reads faster -* Use relocation to try and fix write errors -* Make allocator much smarter -* xattrs (directory streams for regular files) -* Scrub & defrag - diff --git a/fs/btrfs/async-thread.c b/fs/btrfs/async-thread.c index 4e780b279de..04fb9702d14 100644 --- a/fs/btrfs/async-thread.c +++ b/fs/btrfs/async-thread.c @@ -231,17 +231,25 @@ static struct btrfs_worker_thread *next_worker(struct btrfs_workers *workers) /* * if we pick a busy task, move the task to the end of the list. - * hopefully this will keep things somewhat evenly balanced + * hopefully this will keep things somewhat evenly balanced. + * Do the move in batches based on the sequence number. This groups + * requests submitted at roughly the same time onto the same worker. */ next = workers->worker_list.next; worker = list_entry(next, struct btrfs_worker_thread, worker_list); atomic_inc(&worker->num_pending); worker->sequence++; + if (worker->sequence % workers->idle_thresh == 0) list_move_tail(next, &workers->worker_list); return worker; } +/* + * selects a worker thread to take the next job. This will either find + * an idle worker, start a new worker up to the max count, or just return + * one of the existing busy workers. + */ static struct btrfs_worker_thread *find_worker(struct btrfs_workers *workers) { struct btrfs_worker_thread *worker; diff --git a/fs/btrfs/async-thread.h b/fs/btrfs/async-thread.h index 43e44d115dd..4ec9a2ee0f9 100644 --- a/fs/btrfs/async-thread.h +++ b/fs/btrfs/async-thread.h @@ -63,14 +63,17 @@ struct btrfs_workers { /* once a worker has this many requests or fewer, it is idle */ int idle_thresh; - /* list with all the work threads */ + /* list with all the work threads. The workers on the idle thread + * may be actively servicing jobs, but they haven't yet hit the + * idle thresh limit above. + */ struct list_head worker_list; struct list_head idle_list; /* lock for finding the next worker thread to queue on */ spinlock_t lock; - /* extra name for this worker */ + /* extra name for this worker, used for current->name */ char *name; }; diff --git a/fs/btrfs/bit-radix.c b/fs/btrfs/bit-radix.c deleted file mode 100644 index e8bf876db39..00000000000 --- a/fs/btrfs/bit-radix.c +++ /dev/null @@ -1,130 +0,0 @@ -/* - * Copyright (C) 2007 Oracle. All rights reserved. - * - * This program is free software; you can redistribute it and/or - * modify it under the terms of the GNU General Public - * License v2 as published by the Free Software Foundation. - * - * This program is distributed in the hope that it will be useful, - * but WITHOUT ANY WARRANTY; without even the implied warranty of - * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU - * General Public License for more details. - * - * You should have received a copy of the GNU General Public - * License along with this program; if not, write to the - * Free Software Foundation, Inc., 59 Temple Place - Suite 330, - * Boston, MA 021110-1307, USA. - */ - -#include "bit-radix.h" - -#define BIT_ARRAY_BYTES 256 -#define BIT_RADIX_BITS_PER_ARRAY ((BIT_ARRAY_BYTES - sizeof(unsigned long)) * 8) - -extern struct kmem_cache *btrfs_bit_radix_cachep; -int set_radix_bit(struct radix_tree_root *radix, unsigned long bit) -{ - unsigned long *bits; - unsigned long slot; - int bit_slot; - int ret; - - slot = bit / BIT_RADIX_BITS_PER_ARRAY; - bit_slot = bit % BIT_RADIX_BITS_PER_ARRAY; - - bits = radix_tree_lookup(radix, slot); - if (!bits) { - bits = kmem_cache_alloc(btrfs_bit_radix_cachep, GFP_NOFS); - if (!bits) - return -ENOMEM; - memset(bits + 1, 0, BIT_ARRAY_BYTES - sizeof(unsigned long)); - bits[0] = slot; - ret = radix_tree_insert(radix, slot, bits); - if (ret) - return ret; - } - ret = test_and_set_bit(bit_slot, bits + 1); - if (ret < 0) - ret = 1; - return ret; -} - -int test_radix_bit(struct radix_tree_root *radix, unsigned long bit) -{ - unsigned long *bits; - unsigned long slot; - int bit_slot; - - slot = bit / BIT_RADIX_BITS_PER_ARRAY; - bit_slot = bit % BIT_RADIX_BITS_PER_ARRAY; - - bits = radix_tree_lookup(radix, slot); - if (!bits) - return 0; - return test_bit(bit_slot, bits + 1); -} - -int clear_radix_bit(struct radix_tree_root *radix, unsigned long bit) -{ - unsigned long *bits; - unsigned long slot; - int bit_slot; - int i; - int empty = 1; - - slot = bit / BIT_RADIX_BITS_PER_ARRAY; - bit_slot = bit % BIT_RADIX_BITS_PER_ARRAY; - - bits = radix_tree_lookup(radix, slot); - if (!bits) - return 0; - clear_bit(bit_slot, bits + 1); - for (i = 1; i < BIT_ARRAY_BYTES / sizeof(unsigned long); i++) { - if (bits[i]) { - empty = 0; - break; - } - } - if (empty) { - bits = radix_tree_delete(radix, slot); - BUG_ON(!bits); - kmem_cache_free(btrfs_bit_radix_cachep, bits); - } - return 0; -} - -int find_first_radix_bit(struct radix_tree_root *radix, unsigned long *retbits, - unsigned long start, int nr) -{ - unsigned long *bits; - unsigned long *gang[4]; - int found; - int ret; - int i; - int total_found = 0; - unsigned long slot; - - slot = start / BIT_RADIX_BITS_PER_ARRAY; - ret = radix_tree_gang_lookup(radix, (void **)gang, slot, - ARRAY_SIZE(gang)); - found = start % BIT_RADIX_BITS_PER_ARRAY; - for (i = 0; i < ret && nr > 0; i++) { - bits = gang[i]; - while(nr > 0) { - found = find_next_bit(bits + 1, - BIT_RADIX_BITS_PER_ARRAY, - found); - if (found < BIT_RADIX_BITS_PER_ARRAY) { - *retbits = bits[0] * - BIT_RADIX_BITS_PER_ARRAY + found; - retbits++; - nr--; - total_found++; - found++; - } else - break; - } - found = 0; - } - return total_found; -} diff --git a/fs/btrfs/bit-radix.h b/fs/btrfs/bit-radix.h deleted file mode 100644 index c100f54d5c3..00000000000 --- a/fs/btrfs/bit-radix.h +++ /dev/null @@ -1,33 +0,0 @@ -/* - * Copyright (C) 2007 Oracle. All rights reserved. - * - * This program is free software; you can redistribute it and/or - * modify it under the terms of the GNU General Public - * License v2 as published by the Free Software Foundation. - * - * This program is distributed in the hope that it will be useful, - * but WITHOUT ANY WARRANTY; without even the implied warranty of - * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU - * General Public License for more details. - * - * You should have received a copy of the GNU General Public - * License along with this program; if not, write to the - * Free Software Foundation, Inc., 59 Temple Place - Suite 330, - * Boston, MA 021110-1307, USA. - */ - -#ifndef __BIT_RADIX__ -#define __BIT_RADIX__ -#include <linux/radix-tree.h> - -int set_radix_bit(struct radix_tree_root *radix, unsigned long bit); -int test_radix_bit(struct radix_tree_root *radix, unsigned long bit); -int clear_radix_bit(struct radix_tree_root *radix, unsigned long bit); -int find_first_radix_bit(struct radix_tree_root *radix, unsigned long *retbits, - unsigned long start, int nr); - -static inline void init_bit_radix(struct radix_tree_root *radix) -{ - INIT_RADIX_TREE(radix, GFP_NOFS); -} -#endif diff --git a/fs/btrfs/btrfs_inode.h b/fs/btrfs/btrfs_inode.h index 0577fda2168..0b2e623cf42 100644 --- a/fs/btrfs/btrfs_inode.h +++ b/fs/btrfs/btrfs_inode.h @@ -25,27 +25,58 @@ /* in memory btrfs inode */ struct btrfs_inode { + /* which subvolume this inode belongs to */ struct btrfs_root *root; + + /* the block group preferred for allocations. This pointer is buggy + * and needs to be replaced with a bytenr instead + */ struct btrfs_block_group_cache *block_group; + + /* key used to find this inode on disk. This is used by the code + * to read in roots of subvolumes + */ struct btrfs_key location; + + /* the extent_tree has caches of all the extent mappings to disk */ struct extent_map_tree extent_tree; + + /* the io_tree does range state (DIRTY, LOCKED etc) */ struct extent_io_tree io_tree; + + /* special utility tree used to record which mirrors have already been + * tried when checksums fail for a given block + */ struct extent_io_tree io_failure_tree; + + /* held while inserting checksums to avoid races */ struct mutex csum_mutex; + + /* held while inesrting or deleting extents from files */ struct mutex extent_mutex; + + /* held while logging the inode in tree-log.c */ struct mutex log_mutex; - struct inode vfs_inode; + + /* used to order data wrt metadata */ struct btrfs_ordered_inode_tree ordered_tree; + /* standard acl pointers */ struct posix_acl *i_acl; struct posix_acl *i_default_acl; /* for keeping track of orphaned inodes */ struct list_head i_orphan; + /* list of all the delalloc inodes in the FS. There are times we need + * to write all the delalloc pages to disk, and this list is used + * to walk them all. + */ struct list_head delalloc_inodes; - /* full 64 bit generation number */ + /* full 64 bit generation number, struct vfs_inode doesn't have a big + * enough field for this. + */ u64 generation; /* @@ -57,10 +88,25 @@ struct btrfs_inode { */ u64 logged_trans; - /* trans that last made a change that should be fully fsync'd */ + /* + * trans that last made a change that should be fully fsync'd. This + * gets reset to zero each time the inode is logged + */ u64 log_dirty_trans; + + /* total number of bytes pending delalloc, used by stat to calc the + * real block usage of the file + */ u64 delalloc_bytes; + + /* + * the size of the file stored in the metadata on disk. data=ordered + * means the in-memory i_size might be larger than the size on disk + * because not all the blocks are written yet. + */ u64 disk_i_size; + + /* flags field from the on disk inode */ u32 flags; /* @@ -68,6 +114,8 @@ struct btrfs_inode { * number for new files that are created */ u64 index_cnt; + + struct inode vfs_inode; }; static inline struct btrfs_inode *BTRFS_I(struct inode *inode) diff --git a/fs/btrfs/crc32c.h b/fs/btrfs/crc32c.h index 4f0fefed132..1eaf11d334f 100644 --- a/fs/btrfs/crc32c.h +++ b/fs/btrfs/crc32c.h @@ -1,3 +1,21 @@ +/* + * Copyright (C) 2008 Oracle. All rights reserved. + * + * This program is free software; you can redistribute it and/or + * modify it under the terms of the GNU General Public + * License v2 as published by the Free Software Foundation. + * + * This program is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU + * General Public License for more details. + * + * You should have received a copy of the GNU General Public + * License along with this program; if not, write to the + * Free Software Foundation, Inc., 59 Temple Place - Suite 330, + * Boston, MA 021110-1307, USA. + */ + #ifndef __BTRFS_CRC32C__ #define __BTRFS_CRC32C__ #include <asm/byteorder.h> diff --git a/fs/btrfs/ctree.c b/fs/btrfs/ctree.c index 50e81f43e6d..ff3261ff2e1 100644 --- a/fs/btrfs/ctree.c +++ b/fs/btrfs/ctree.c @@ -1,5 +1,5 @@ /* - * Copyright (C) 2007 Oracle. All rights reserved. + * Copyright (C) 2007,2008 Oracle. All rights reserved. * * This program is free software; you can redistribute it and/or * modify it under the terms of the GNU General Public @@ -54,12 +54,19 @@ struct btrfs_path *btrfs_alloc_path(void) return path; } +/* this also releases the path */ void btrfs_free_path(struct btrfs_path *p) { btrfs_release_path(NULL, p); kmem_cache_free(btrfs_path_cachep, p); } +/* + * path release drops references on the extent buffers in the path + * and it drops any locks held by this path + * + * It is safe to call this on paths that no locks or extent buffers held. + */ void noinline btrfs_release_path(struct btrfs_root *root, struct btrfs_path *p) { int i; @@ -77,6 +84,16 @@ void noinline btrfs_release_path(struct btrfs_root *root, struct btrfs_path *p) } } +/* + * safely gets a reference on the root node of a tree. A lock + * is not taken, so a concurrent writer may put a different node + * at the root of the tree. See btrfs_lock_root_node for the + * looping required. + * + * The extent buffer returned by this has a reference taken, so + * it won't disappear. It may stop being the root of the tree + * at any time because there are no locks held. + */ struct extent_buffer *btrfs_root_node(struct btrfs_root *root) { struct extent_buffer *eb; @@ -87,6 +104,10 @@ struct extent_buffer *btrfs_root_node(struct btrfs_root *root) return eb; } +/* loop around taking references on and locking the root node of the + * tree until you end up with a lock on the root. A locked buffer + * is returned, with a reference held. + */ struct extent_buffer *btrfs_lock_root_node(struct btrfs_root *root) { struct extent_buffer *eb; @@ -108,6 +129,10 @@ struct extent_buffer *btrfs_lock_root_node(struct btrfs_root *root) return eb; } +/* cowonly root (everything not a reference counted cow subvolume), just get + * put onto a simple dirty list. transaction.c walks this to make sure they + * get properly updated on disk. + */ static void add_root_to_dirty_list(struct btrfs_root *root) { if (root->track_dirty && list_empty(&root->dirty_list)) { @@ -116,6 +141,11 @@ static void add_root_to_dirty_list(struct btrfs_root *root) } } +/* + * used by snapshot creation to make a copy of a root for a tree with + * a given objectid. The buffer with the new root node is returned in + * cow_ret, and this func returns zero on success or a negative error code. + */ int btrfs_copy_root(struct btrfs_trans_handle *trans, struct btrfs_root *root, struct extent_buffer *buf, @@ -167,6 +197,22 @@ int btrfs_copy_root(struct btrfs_trans_handle *trans, return 0; } +/* + * does the dirty work in cow of a single block. The parent block + * (if supplied) is updated to point to the new cow copy. The new + * buffer is marked dirty and returned locked. If you modify the block + * it needs to be marked dirty again. + * + * search_start -- an allocation hint for the new block + * + * empty_size -- a hint that you plan on doing more cow. This is the size in bytes + * the allocator should try to find free next to the block it returns. This is + * just a hint and may be ignored by the allocator. + * + * prealloc_dest -- if you have already reserved a destination for the cow, + * this uses that block instead of allocating a new one. btrfs_alloc_reserved_extent + * is used to finish the allocation. + */ int noinline __btrfs_cow_block(struct btrfs_trans_handle *trans, struct btrfs_root *root, struct extent_buffer *buf, @@ -311,6 +357,11 @@ int noinline __btrfs_cow_block(struct btrfs_trans_handle *trans, return 0; } +/* + * cows a single block, see __btrfs_cow_block for the real work. + * This version of it has extra checks so that a block isn't cow'd more than + * once per transaction, as long as it hasn't been written yet + */ int noinline btrfs_cow_block(struct btrfs_trans_handle *trans, struct btrfs_root *root, struct extent_buffer *buf, struct extent_buffer *parent, int parent_slot, @@ -347,6 +398,10 @@ int noinline btrfs_cow_block(struct btrfs_trans_handle *trans, return ret; } +/* + * helper function for defrag to decide if two blocks pointed to by a + * node are actually close by + */ static int close_blocks(u64 blocknr, u64 other, u32 blocksize) { if (blocknr < other && other - (blocknr + blocksize) < 32768) @@ -381,6 +436,11 @@ static int comp_keys(struct btrfs_disk_key *disk, struct btrfs_key *k2) } +/* + * this is used by the defrag code to go through all the + * leaves pointed to by a node and reallocate them so that + * disk order is close to key order + */ int btrfs_realloc_node(struct btrfs_trans_handle *trans, struct btrfs_root *root, struct extent_buffer *parent, int start_slot, int cache_only, u64 *last_ret, @@ -521,6 +581,10 @@ static inline unsigned int leaf_data_end(struct btrfs_root *root, return btrfs_item_offset_nr(leaf, nr - 1); } +/* + * extra debugging checks to make sure all the items in a key are + * well formed and in the proper order + */ static int check_node(struct btrfs_root *root, struct btrfs_path *path, int level) { @@ -561,6 +625,10 @@ static int check_node(struct btrfs_root *root, struct btrfs_path *path, return 0; } +/* + * extra checking to make sure all the items in a leaf are + * well formed and in the proper order + */ static int check_leaf(struct btrfs_root *root, struct btrfs_path *path, int level) { @@ -782,6 +850,10 @@ static int bin_search(struct extent_buffer *eb, struct btrfs_key *key, return -1; } +/* given a node and slot number, this reads the blocks it points to. The + * extent buffer is returned with a reference taken (but unlocked). + * NULL is returned on error. + */ static noinline struct extent_buffer *read_node_slot(struct btrfs_root *root, struct extent_buffer *parent, int slot) { @@ -798,6 +870,11 @@ static noinline struct extent_buffer *read_node_slot(struct btrfs_root *root, btrfs_node_ptr_generation(parent, slot)); } +/* + * node level balancing, used to make sure nodes are in proper order for + * item deletion. We balance from the top down, so we have to make sure + * that a deletion won't leave an node completely empty later on. + */ static noinline int balance_level(struct btrfs_trans_handle *trans, struct btrfs_root *root, struct btrfs_path *path, int level) @@ -1024,7 +1101,10 @@ enospc: return ret; } -/* returns zero if the push worked, non-zero otherwise */ +/* Node balancing for insertion. Here we only split or push nodes around + * when they are completely full. This is also done top down, so we + * have to be pessimistic. + */ static int noinline push_nodes_for_insert(struct btrfs_trans_handle *trans, struct btrfs_root *root, struct btrfs_path *path, int level) @@ -1150,7 +1230,8 @@ static int noinline push_nodes_for_insert(struct btrfs_trans_handle *trans, } /* - * readahead one full node of leaves + * readahead one full node of leaves, finding things that are close + * to the block in 'slot', and triggering ra on them. */ static noinline void reada_for_search(struct btrfs_root *root, struct btrfs_path *path, @@ -1226,6 +1307,19 @@ static noinline void reada_for_search(struct btrfs_root *root, } } +/* + * when we walk down the tree, it is usually safe to unlock the higher layers in + * the tree. The exceptions are when our path goes through slot 0, because operations + * on the tree might require changing key pointers higher up in the tree. + * + * callers might also have set path->keep_locks, which tells this code to + * keep the lock if the path points to the last slot in the block. This is + * part of walking through the tree, and selecting the next slot in the higher + * block. + * + * lowest_unlock sets the lowest level in the tree we're allowed to unlock. + * so if lowest_unlock is 1, level 0 won't be unlocked + */ static noinline void unlock_up(struct btrfs_path *path, int level, int lowest_unlock) { @@ -2705,6 +2799,12 @@ again: return ret; } +/* + * make the item pointed to by the path smaller. new_size indicates + * how small to make it, and from_end tells us if we just chop bytes + * off the end of the item or if we shift the item to chop bytes off + * the front. + */ int btrfs_truncate_item(struct btrfs_trans_handle *trans, struct btrfs_root *root, struct btrfs_path *path, @@ -2818,6 +2918,9 @@ int btrfs_truncate_item(struct btrfs_trans_handle *trans, return ret; } +/* + * make the item pointed to by the path bigger, data_size is the new size. + */ int btrfs_extend_item(struct btrfs_trans_handle *trans, struct btrfs_root *root, struct btrfs_path *path, u32 data_size) @@ -2897,7 +3000,7 @@ int btrfs_extend_item(struct btrfs_trans_handle *trans, } /* - * Given a key and some data, insert an item into the tree. + * Given a key and some data, insert items into the tree. * This does all the path init required, making room in the tree if needed. */ int btrfs_insert_empty_items(struct btrfs_trans_handle *trans, @@ -3046,9 +3149,8 @@ int btrfs_insert_item(struct btrfs_trans_handle *trans, struct btrfs_root /* * delete the pointer from a given node. * - * If the delete empties a node, the node is removed from the tree, - * continuing all the way the root if required. The root is converted into - * a leaf if all the nodes are emptied. + * the tree should have been previously balanced so the deletion does not + * empty a node. */ static int del_ptr(struct btrfs_trans_handle *trans, struct btrfs_root *root, struct btrfs_path *path, int level, int slot) @@ -3233,6 +3335,9 @@ int btrfs_del_items(struct btrfs_trans_handle *trans, struct btrfs_root *root, * search the tree again to find a leaf with lesser keys * returns 0 if it found something or 1 if there are no lesser leaves. * returns < 0 on io errors. + * + * This may release the path, and so you may lose any locks held at the + * time you call it. */ int btrfs_prev_leaf(struct btrfs_root *root, struct btrfs_path *path) { @@ -3265,9 +3370,7 @@ int btrfs_prev_leaf(struct btrfs_root *root, struct btrfs_path *path) /* * A helper function to walk down the tree starting at min_key, and looking * for nodes or leaves that are either in cache or have a minimum - * transaction id. This is used by the btree defrag code, but could - * also be used to search for blocks that have changed since a given - * transaction id. + * transaction id. This is used by the btree defrag code, and tree logging * * This does not cow, but it does stuff the starting key it finds back * into min_key, so you can call btrfs_search_slot with cow=1 on the @@ -3279,6 +3382,10 @@ int btrfs_prev_leaf(struct btrfs_root *root, struct btrfs_path *path) * This honors path->lowest_level to prevent descent past a given level * of the tree. * + * min_trans indicates the oldest transaction that you are interested + * in walking through. Any nodes or leaves older than min_trans are + * skipped over (without reading them). + * * returns zero if something useful was found, < 0 on error and 1 if there * was nothing in the tree that matched the search criteria. */ diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h index 0079b60b18f..ded1643c027 100644 --- a/fs/btrfs/ctree.h +++ b/fs/btrfs/ctree.h @@ -27,7 +27,6 @@ #include <linux/backing-dev.h> #include <linux/wait.h> #include <asm/kmap_types.h> -#include "bit-radix.h" #include "extent_io.h" #include "extent_map.h" #include "async-thread.h" diff --git a/fs/btrfs/dir-item.c b/fs/btrfs/dir-item.c index e4f30090d64..5040b71f190 100644 --- a/fs/btrfs/dir-item.c +++ b/fs/btrfs/dir-item.c @@ -21,6 +21,14 @@ #include "hash.h" #include "transaction.h" +/* + * insert a name into a directory, doing overflow properly if there is a hash + * collision. data_size indicates how big the item inserted should be. On + * success a struct btrfs_dir_item pointer is returned, otherwise it is + * an ERR_PTR. + * + * The name is not copied into the dir item, you have to do that yourself. + */ static struct btrfs_dir_item *insert_with_overflow(struct btrfs_trans_handle *trans, struct btrfs_root *root, @@ -55,6 +63,10 @@ static struct btrfs_dir_item *insert_with_overflow(struct btrfs_trans_handle return (struct btrfs_dir_item *)ptr; } +/* + * xattrs work a lot like directories, this inserts an xattr item + * into the tree + */ int btrfs_insert_xattr_item(struct btrfs_trans_handle *trans, struct btrfs_root *root, const char *name, u16 name_len, const void *data, u16 data_len, @@ -109,6 +121,13 @@ int btrfs_insert_xattr_item(struct btrfs_trans_handle *trans, return ret; } +/* + * insert a directory item in the tree, doing all the magic for + * both indexes. 'dir' indicates which objectid to insert it into, + * 'location' is the key to stuff into the directory item, 'type' is the + * type of the inode we're pointing to, and 'index' is the sequence number + * to use for the second index (if one is created). + */ int btrfs_insert_dir_item(struct btrfs_trans_handle *trans, struct btrfs_root *root, const char *name, int name_len, u64 dir, struct btrfs_key *location, u8 type, u64 index) @@ -184,6 +203,11 @@ out: return 0; } +/* + * lookup a directory item based on name. 'dir' is the objectid + * we're searching in, and 'mod' tells us if you plan on deleting the + * item (use mod < 0) or changing the options (use mod > 0) + */ struct btrfs_dir_item *btrfs_lookup_dir_item(struct btrfs_trans_handle *trans, struct btrfs_root *root, struct btrfs_path *path, u64 dir, @@ -222,6 +246,14 @@ struct btrfs_dir_item *btrfs_lookup_dir_item(struct btrfs_trans_handle *trans, return btrfs_match_dir_item_name(root, path, name, name_len); } +/* + * lookup a directory item based on index. 'dir' is the objectid + * we're searching in, and 'mod' tells us if you plan on deleting the + * item (use mod < 0) or changing the options (use mod > 0) + * + * The name is used to make sure the index really points to the name you were + * looking for. + */ struct btrfs_dir_item * btrfs_lookup_dir_index_item(struct btrfs_trans_handle *trans, struct btrfs_root *root, @@ -282,6 +314,11 @@ struct btrfs_dir_item *btrfs_lookup_xattr(struct btrfs_trans_handle *trans, return btrfs_match_dir_item_name(root, path, name, name_len); } +/* + * helper function to look at the directory item pointed to by 'path' + * this walks through all the entries in a dir item and finds one + * for a specific name. + */ struct btrfs_dir_item *btrfs_match_dir_item_name(struct btrfs_root *root, struct btrfs_path *path, const char *name, int name_len) @@ -313,6 +350,10 @@ struct btrfs_dir_item *btrfs_match_dir_item_name(struct btrfs_root *root, return NULL; } +/* + * given a pointer into a directory item, delete it. This + * handles items that have more than one entry in them. + */ int btrfs_delete_one_dir_name(struct btrfs_trans_handle *trans, struct btrfs_root *root, struct btrfs_path *path, diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c index 45b4f728527..5ee10d3136f 100644 --- a/fs/btrfs/disk-io.c +++ b/fs/btrfs/disk-io.c @@ -55,6 +55,11 @@ static int check_tree_block(struct btrfs_root *root, struct extent_buffer *buf) static struct extent_io_ops btree_extent_io_ops; static void end_workqueue_fn(struct btrfs_work *work); +/* + * end_io_wq structs are used to do processing in task context when an IO is + * complete. This is used during reads to verify checksums, and it is used + * by writes to insert metadata for new file extents after IO is complete. + */ struct end_io_wq { struct bio *bio; bio_end_io_t *end_io; @@ -66,6 +71,11 @@ struct end_io_wq { struct btrfs_work work; }; +/* + * async submit bios are used to offload expensive checksumming + * onto the worker threads. They checksum file and metadata bios + * just before they are sent down the IO stack. + */ struct async_submit_bio { struct inode *inode; struct bio *bio; @@ -76,6 +86,10 @@ struct async_submit_bio { struct btrfs_work work; }; +/* + * extents on the btree inode are pretty simple, there's one extent + * that covers the entire device + */ struct extent_map *btree_get_extent(struct inode *inode, struct page *page, size_t page_offset, u64 start, u64 len, int create) @@ -151,6 +165,10 @@ void btrfs_csum_final(u32 crc, char *result) *(__le32 *)result = ~cpu_to_le32(crc); } +/* + * compute the csum for a btree block, and either verify it or write it + * into the csum field of the block. + */ static int csum_tree_block(struct btrfs_root *root, struct extent_buffer *buf, int verify) { @@ -204,6 +222,12 @@ static int csum_tree_block(struct btrfs_root *root, struct extent_buffer *buf, return 0; } +/* + * we can't consider a given block up to date unless the transid of the + * block matches the transid in the parent node's pointer. This is how we + * detect blocks that either didn't get written at all or got written + * in the wrong place. + */ static int verify_parent_transid(struct extent_io_tree *io_tree, struct extent_buffer *eb, u64 parent_transid) { @@ -228,9 +252,12 @@ out: unlock_extent(io_tree, eb->start, eb->start + eb->len - 1, GFP_NOFS); return ret; - } +/* + * helper to read a given tree block, |