diff options
Diffstat (limited to 'fs/fs-writeback.c')
| -rw-r--r-- | fs/fs-writeback.c | 1064 |
1 files changed, 631 insertions, 433 deletions
diff --git a/fs/fs-writeback.c b/fs/fs-writeback.c index 3d06ccc953a..be568b7311d 100644 --- a/fs/fs-writeback.c +++ b/fs/fs-writeback.c @@ -14,49 +14,45 @@ */ #include <linux/kernel.h> -#include <linux/module.h> +#include <linux/export.h> #include <linux/spinlock.h> #include <linux/slab.h> #include <linux/sched.h> #include <linux/fs.h> #include <linux/mm.h> +#include <linux/pagemap.h> #include <linux/kthread.h> -#include <linux/freezer.h> #include <linux/writeback.h> #include <linux/blkdev.h> #include <linux/backing-dev.h> -#include <linux/buffer_head.h> #include <linux/tracepoint.h> +#include <linux/device.h> #include "internal.h" /* + * 4MB minimal write chunk size + */ +#define MIN_WRITEBACK_PAGES (4096UL >> (PAGE_CACHE_SHIFT - 10)) + +/* * Passed into wb_writeback(), essentially a subset of writeback_control */ struct wb_writeback_work { long nr_pages; struct super_block *sb; + unsigned long *older_than_this; enum writeback_sync_modes sync_mode; + unsigned int tagged_writepages:1; unsigned int for_kupdate:1; unsigned int range_cyclic:1; unsigned int for_background:1; + unsigned int for_sync:1; /* sync(2) WB_SYNC_ALL writeback */ + enum wb_reason reason; /* why was writeback initiated? */ struct list_head list; /* pending work list */ struct completion *done; /* set if the caller waits */ }; -/* - * Include the creation of the trace points after defining the - * wb_writeback_work structure so that the definition remains local to this - * file. - */ -#define CREATE_TRACE_POINTS -#include <trace/events/writeback.h> - -/* - * We don't actually have pdflush, but this one is exported though /proc... - */ -int nr_pdflush_threads; - /** * writeback_in_progress - determine whether there is writeback in progress * @bdi: the device's backing_dev_info structure. @@ -68,12 +64,13 @@ int writeback_in_progress(struct backing_dev_info *bdi) { return test_bit(BDI_writeback_running, &bdi->state); } +EXPORT_SYMBOL(writeback_in_progress); static inline struct backing_dev_info *inode_to_bdi(struct inode *inode) { struct super_block *sb = inode->i_sb; - if (strcmp(sb->s_type->name, "bdev") == 0) + if (sb_is_blkdev_sb(sb)) return inode->i_mapping->backing_dev_info; return sb->s_bdi; @@ -84,29 +81,44 @@ static inline struct inode *wb_inode(struct list_head *head) return list_entry(head, struct inode, i_wb_list); } +/* + * Include the creation of the trace points after defining the + * wb_writeback_work structure and inline functions so that the definition + * remains local to this file. + */ +#define CREATE_TRACE_POINTS +#include <trace/events/writeback.h> + +EXPORT_TRACEPOINT_SYMBOL_GPL(wbc_writepage); + +static void bdi_wakeup_thread(struct backing_dev_info *bdi) +{ + spin_lock_bh(&bdi->wb_lock); + if (test_bit(BDI_registered, &bdi->state)) + mod_delayed_work(bdi_wq, &bdi->wb.dwork, 0); + spin_unlock_bh(&bdi->wb_lock); +} + static void bdi_queue_work(struct backing_dev_info *bdi, - struct wb_writeback_work *work) + struct wb_writeback_work *work) { trace_writeback_queue(bdi, work); spin_lock_bh(&bdi->wb_lock); - list_add_tail(&work->list, &bdi->work_list); - if (bdi->wb.task) { - wake_up_process(bdi->wb.task); - } else { - /* - * The bdi thread isn't there, wake up the forker thread which - * will create and run it. - */ - trace_writeback_nothread(bdi, work); - wake_up_process(default_backing_dev_info.wb.task); + if (!test_bit(BDI_registered, &bdi->state)) { + if (work->done) + complete(work->done); + goto out_unlock; } + list_add_tail(&work->list, &bdi->work_list); + mod_delayed_work(bdi_wq, &bdi->wb.dwork, 0); +out_unlock: spin_unlock_bh(&bdi->wb_lock); } static void __bdi_start_writeback(struct backing_dev_info *bdi, long nr_pages, - bool range_cyclic, bool for_background) + bool range_cyclic, enum wb_reason reason) { struct wb_writeback_work *work; @@ -116,17 +128,15 @@ __bdi_start_writeback(struct backing_dev_info *bdi, long nr_pages, */ work = kzalloc(sizeof(*work), GFP_ATOMIC); if (!work) { - if (bdi->wb.task) { - trace_writeback_nowork(bdi); - wake_up_process(bdi->wb.task); - } + trace_writeback_nowork(bdi); + bdi_wakeup_thread(bdi); return; } work->sync_mode = WB_SYNC_NONE; work->nr_pages = nr_pages; work->range_cyclic = range_cyclic; - work->for_background = for_background; + work->reason = reason; bdi_queue_work(bdi, work); } @@ -135,16 +145,18 @@ __bdi_start_writeback(struct backing_dev_info *bdi, long nr_pages, * bdi_start_writeback - start writeback * @bdi: the backing device to write from * @nr_pages: the number of pages to write + * @reason: reason why some writeback work was initiated * * Description: * This does WB_SYNC_NONE opportunistic writeback. The IO is only - * started when this function returns, we make no guarentees on + * started when this function returns, we make no guarantees on * completion. Caller need not hold sb s_umount semaphore. * */ -void bdi_start_writeback(struct backing_dev_info *bdi, long nr_pages) +void bdi_start_writeback(struct backing_dev_info *bdi, long nr_pages, + enum wb_reason reason) { - __bdi_start_writeback(bdi, nr_pages, true, false); + __bdi_start_writeback(bdi, nr_pages, true, reason); } /** @@ -152,13 +164,31 @@ void bdi_start_writeback(struct backing_dev_info *bdi, long nr_pages) * @bdi: the backing device to write from * * Description: - * This does WB_SYNC_NONE background writeback. The IO is only - * started when this function returns, we make no guarentees on - * completion. Caller need not hold sb s_umount semaphore. + * This makes sure WB_SYNC_NONE background writeback happens. When + * this function returns, it is only guaranteed that for given BDI + * some IO is happening if we are over background dirty threshold. + * Caller need not hold sb s_umount semaphore. */ void bdi_start_background_writeback(struct backing_dev_info *bdi) { - __bdi_start_writeback(bdi, LONG_MAX, true, true); + /* + * We just wake up the flusher thread. It will perform background + * writeback as soon as there is no other work to do. + */ + trace_writeback_wake_background(bdi); + bdi_wakeup_thread(bdi); +} + +/* + * Remove the inode from the writeback list it is on. + */ +void inode_wb_list_del(struct inode *inode) +{ + struct backing_dev_info *bdi = inode_to_bdi(inode); + + spin_lock(&bdi->wb.list_lock); + list_del_init(&inode->i_wb_list); + spin_unlock(&bdi->wb.list_lock); } /* @@ -170,10 +200,9 @@ void bdi_start_background_writeback(struct backing_dev_info *bdi) * the case then the inode must have been redirtied while it was being written * out and we don't reset its dirtied_when. */ -static void redirty_tail(struct inode *inode) +static void redirty_tail(struct inode *inode, struct bdi_writeback *wb) { - struct bdi_writeback *wb = &inode_to_bdi(inode)->wb; - + assert_spin_locked(&wb->list_lock); if (!list_empty(&wb->b_dirty)) { struct inode *tail; @@ -187,18 +216,18 @@ static void redirty_tail(struct inode *inode) /* * requeue inode for re-scanning after bdi->b_io list is exhausted. */ -static void requeue_io(struct inode *inode) +static void requeue_io(struct inode *inode, struct bdi_writeback *wb) { - struct bdi_writeback *wb = &inode_to_bdi(inode)->wb; - + assert_spin_locked(&wb->list_lock); list_move(&inode->i_wb_list, &wb->b_more_io); } static void inode_sync_complete(struct inode *inode) { - /* - * Prevent speculative execution through spin_unlock(&inode_lock); - */ + inode->i_state &= ~I_SYNC; + /* If inode is clean an unused, put it into LRU now... */ + inode_add_lru(inode); + /* Waiters must see I_SYNC cleared before being woken up */ smp_mb(); wake_up_bit(&inode->i_state, __I_SYNC); } @@ -219,33 +248,38 @@ static bool inode_dirtied_after(struct inode *inode, unsigned long t) } /* - * Move expired dirty inodes from @delaying_queue to @dispatch_queue. + * Move expired (dirtied before work->older_than_this) dirty inodes from + * @delaying_queue to @dispatch_queue. */ -static void move_expired_inodes(struct list_head *delaying_queue, +static int move_expired_inodes(struct list_head *delaying_queue, struct list_head *dispatch_queue, - unsigned long *older_than_this) + struct wb_writeback_work *work) { LIST_HEAD(tmp); struct list_head *pos, *node; struct super_block *sb = NULL; struct inode *inode; int do_sb_sort = 0; + int moved = 0; while (!list_empty(delaying_queue)) { inode = wb_inode(delaying_queue->prev); - if (older_than_this && - inode_dirtied_after(inode, *older_than_this)) + if (work->older_than_this && + inode_dirtied_after(inode, *work->older_than_this)) break; + list_move(&inode->i_wb_list, &tmp); + moved++; + if (sb_is_blkdev_sb(inode->i_sb)) + continue; if (sb && sb != inode->i_sb) do_sb_sort = 1; sb = inode->i_sb; - list_move(&inode->i_wb_list, &tmp); } /* just one sb in list, splice to dispatch_queue and we're done */ if (!do_sb_sort) { list_splice(&tmp, dispatch_queue); - return; + goto out; } /* Move inodes from one superblock together */ @@ -257,6 +291,8 @@ static void move_expired_inodes(struct list_head *delaying_queue, list_move(&inode->i_wb_list, dispatch_queue); } } +out: + return moved; } /* @@ -270,95 +306,167 @@ static void move_expired_inodes(struct list_head *delaying_queue, * | * +--> dequeue for IO */ -static void queue_io(struct bdi_writeback *wb, unsigned long *older_than_this) +static void queue_io(struct bdi_writeback *wb, struct wb_writeback_work *work) { + int moved; + assert_spin_locked(&wb->list_lock); list_splice_init(&wb->b_more_io, &wb->b_io); - move_expired_inodes(&wb->b_dirty, &wb->b_io, older_than_this); + moved = move_expired_inodes(&wb->b_dirty, &wb->b_io, work); + trace_writeback_queue_io(wb, work, moved); } static int write_inode(struct inode *inode, struct writeback_control *wbc) { - if (inode->i_sb->s_op->write_inode && !is_bad_inode(inode)) - return inode->i_sb->s_op->write_inode(inode, wbc); + int ret; + + if (inode->i_sb->s_op->write_inode && !is_bad_inode(inode)) { + trace_writeback_write_inode_start(inode, wbc); + ret = inode->i_sb->s_op->write_inode(inode, wbc); + trace_writeback_write_inode(inode, wbc); + return ret; + } return 0; } /* - * Wait for writeback on an inode to complete. + * Wait for writeback on an inode to complete. Called with i_lock held. + * Caller must make sure inode cannot go away when we drop i_lock. */ -static void inode_wait_for_writeback(struct inode *inode) +static void __inode_wait_for_writeback(struct inode *inode) + __releases(inode->i_lock) + __acquires(inode->i_lock) { DEFINE_WAIT_BIT(wq, &inode->i_state, __I_SYNC); wait_queue_head_t *wqh; wqh = bit_waitqueue(&inode->i_state, __I_SYNC); - while (inode->i_state & I_SYNC) { - spin_unlock(&inode_lock); + while (inode->i_state & I_SYNC) { + spin_unlock(&inode->i_lock); __wait_on_bit(wqh, &wq, inode_wait, TASK_UNINTERRUPTIBLE); - spin_lock(&inode_lock); + spin_lock(&inode->i_lock); } } /* - * Write out an inode's dirty pages. Called under inode_lock. Either the - * caller has ref on the inode (either via __iget or via syscall against an fd) - * or the inode has I_WILL_FREE set (via generic_forget_inode) - * - * If `wait' is set, wait on the writeout. - * - * The whole writeout design is quite complex and fragile. We want to avoid - * starvation of particular inodes when others are being redirtied, prevent - * livelocks, etc. - * - * Called under inode_lock. + * Wait for writeback on an inode to complete. Caller must have inode pinned. */ -static int -writeback_single_inode(struct inode *inode, struct writeback_control *wbc) +void inode_wait_for_writeback(struct inode *inode) { - struct address_space *mapping = inode->i_mapping; - unsigned dirty; - int ret; + spin_lock(&inode->i_lock); + __inode_wait_for_writeback(inode); + spin_unlock(&inode->i_lock); +} - if (!atomic_read(&inode->i_count)) - WARN_ON(!(inode->i_state & (I_WILL_FREE|I_FREEING))); - else - WARN_ON(inode->i_state & I_WILL_FREE); +/* + * Sleep until I_SYNC is cleared. This function must be called with i_lock + * held and drops it. It is aimed for callers not holding any inode reference + * so once i_lock is dropped, inode can go away. + */ +static void inode_sleep_on_writeback(struct inode *inode) + __releases(inode->i_lock) +{ + DEFINE_WAIT(wait); + wait_queue_head_t *wqh = bit_waitqueue(&inode->i_state, __I_SYNC); + int sleep; + + prepare_to_wait(wqh, &wait, TASK_UNINTERRUPTIBLE); + sleep = inode->i_state & I_SYNC; + spin_unlock(&inode->i_lock); + if (sleep) + schedule(); + finish_wait(wqh, &wait); +} - if (inode->i_state & I_SYNC) { +/* + * Find proper writeback list for the inode depending on its current state and + * possibly also change of its state while we were doing writeback. Here we + * handle things such as livelock prevention or fairness of writeback among + * inodes. This function can be called only by flusher thread - noone else + * processes all inodes in writeback lists and requeueing inodes behind flusher + * thread's back can have unexpected consequences. + */ +static void requeue_inode(struct inode *inode, struct bdi_writeback *wb, + struct writeback_control *wbc) +{ + if (inode->i_state & I_FREEING) + return; + + /* + * Sync livelock prevention. Each inode is tagged and synced in one + * shot. If still dirty, it will be redirty_tail()'ed below. Update + * the dirty time to prevent enqueue and sync it again. + */ + if ((inode->i_state & I_DIRTY) && + (wbc->sync_mode == WB_SYNC_ALL || wbc->tagged_writepages)) + inode->dirtied_when = jiffies; + + if (wbc->pages_skipped) { /* - * If this inode is locked for writeback and we are not doing - * writeback-for-data-integrity, move it to b_more_io so that - * writeback can proceed with the other inodes on s_io. - * - * We'll have another go at writing back this inode when we - * completed a full scan of b_io. + * writeback is not making progress due to locked + * buffers. Skip this inode for now. */ - if (wbc->sync_mode != WB_SYNC_ALL) { - requeue_io(inode); - return 0; - } + redirty_tail(inode, wb); + return; + } + if (mapping_tagged(inode->i_mapping, PAGECACHE_TAG_DIRTY)) { /* - * It's a data-integrity sync. We must wait. + * We didn't write back all the pages. nfs_writepages() + * sometimes bales out without doing anything. */ - inode_wait_for_writeback(inode); + if (wbc->nr_to_write <= 0) { + /* Slice used up. Queue for next turn. */ + requeue_io(inode, wb); + } else { + /* + * Writeback blocked by something other than + * congestion. Delay the inode for some time to + * avoid spinning on the CPU (100% iowait) + * retrying writeback of the dirty page/inode + * that cannot be performed immediately. + */ + redirty_tail(inode, wb); + } + } else if (inode->i_state & I_DIRTY) { + /* + * Filesystems can dirty the inode during writeback operations, + * such as delayed allocation during submission or metadata + * updates after data IO completion. + */ + redirty_tail(inode, wb); + } else { + /* The inode is clean. Remove from writeback lists. */ + list_del_init(&inode->i_wb_list); } +} - BUG_ON(inode->i_state & I_SYNC); +/* + * Write out an inode and its dirty pages. Do not update the writeback list + * linkage. That is left to the caller. The caller is also responsible for + * setting I_SYNC flag and calling inode_sync_complete() to clear it. + */ +static int +__writeback_single_inode(struct inode *inode, struct writeback_control *wbc) +{ + struct address_space *mapping = inode->i_mapping; + long nr_to_write = wbc->nr_to_write; + unsigned dirty; + int ret; - /* Set I_SYNC, reset I_DIRTY_PAGES */ - inode->i_state |= I_SYNC; - inode->i_state &= ~I_DIRTY_PAGES; - spin_unlock(&inode_lock); + WARN_ON(!(inode->i_state & I_SYNC)); + + trace_writeback_single_inode_start(inode, wbc, nr_to_write); ret = do_writepages(mapping, wbc); /* * Make sure to wait on the data before writing out the metadata. * This is important for filesystems that modify metadata on data - * I/O completion. + * I/O completion. We don't do it for sync(2) writeback because it has a + * separate, external IO completion path and ->sync_fs for guaranteeing + * inode metadata is written back correctly. */ - if (wbc->sync_mode == WB_SYNC_ALL) { + if (wbc->sync_mode == WB_SYNC_ALL && !wbc->for_sync) { int err = filemap_fdatawait(mapping); if (ret == 0) ret = err; @@ -369,113 +477,151 @@ writeback_single_inode(struct inode *inode, struct writeback_control *wbc) * due to delalloc, clear dirty metadata flags right before * write_inode() */ - spin_lock(&inode_lock); + spin_lock(&inode->i_lock); + /* Clear I_DIRTY_PAGES if we've written out all dirty pages */ + if (!mapping_tagged(mapping, PAGECACHE_TAG_DIRTY)) + inode->i_state &= ~I_DIRTY_PAGES; dirty = inode->i_state & I_DIRTY; inode->i_state &= ~(I_DIRTY_SYNC | I_DIRTY_DATASYNC); - spin_unlock(&inode_lock); + spin_unlock(&inode->i_lock); /* Don't write the inode if only I_DIRTY_PAGES was set */ if (dirty & (I_DIRTY_SYNC | I_DIRTY_DATASYNC)) { int err = write_inode(inode, wbc); if (ret == 0) ret = err; } - - spin_lock(&inode_lock); - inode->i_state &= ~I_SYNC; - if (!(inode->i_state & I_FREEING)) { - if (mapping_tagged(mapping, PAGECACHE_TAG_DIRTY)) { - /* - * We didn't write back all the pages. nfs_writepages() - * sometimes bales out without doing anything. - */ - inode->i_state |= I_DIRTY_PAGES; - if (wbc->nr_to_write <= 0) { - /* - * slice used up: queue for next turn - */ - requeue_io(inode); - } else { - /* - * Writeback blocked by something other than - * congestion. Delay the inode for some time to - * avoid spinning on the CPU (100% iowait) - * retrying writeback of the dirty page/inode - * that cannot be performed immediately. - */ - redirty_tail(inode); - } - } else if (inode->i_state & I_DIRTY) { - /* - * Filesystems can dirty the inode during writeback - * operations, such as delayed allocation during - * submission or metadata updates after data IO - * completion. - */ - redirty_tail(inode); - } else { - /* - * The inode is clean. At this point we either have - * a reference to the inode or it's on it's way out. - * No need to add it back to the LRU. - */ - list_del_init(&inode->i_wb_list); - } - } - inode_sync_complete(inode); + trace_writeback_single_inode(inode, wbc, nr_to_write); return ret; } /* - * For background writeback the caller does not have the sb pinned - * before calling writeback. So make sure that we do pin it, so it doesn't - * go away while we are writing inodes from it. + * Write out an inode's dirty pages. Either the caller has an active reference + * on the inode or the inode has I_WILL_FREE set. + * + * This function is designed to be called for writing back one inode which + * we go e.g. from filesystem. Flusher thread uses __writeback_single_inode() + * and does more profound writeback list handling in writeback_sb_inodes(). */ -static bool pin_sb_for_writeback(struct super_block *sb) +static int +writeback_single_inode(struct inode *inode, struct bdi_writeback *wb, + struct writeback_control *wbc) { - spin_lock(&sb_lock); - if (list_empty(&sb->s_instances)) { - spin_unlock(&sb_lock); - return false; + int ret = 0; + + spin_lock(&inode->i_lock); + if (!atomic_read(&inode->i_count)) + WARN_ON(!(inode->i_state & (I_WILL_FREE|I_FREEING))); + else + WARN_ON(inode->i_state & I_WILL_FREE); + + if (inode->i_state & I_SYNC) { + if (wbc->sync_mode != WB_SYNC_ALL) + goto out; + /* + * It's a data-integrity sync. We must wait. Since callers hold + * inode reference or inode has I_WILL_FREE set, it cannot go + * away under us. + */ + __inode_wait_for_writeback(inode); } + WARN_ON(inode->i_state & I_SYNC); + /* + * Skip inode if it is clean and we have no outstanding writeback in + * WB_SYNC_ALL mode. We don't want to mess with writeback lists in this + * function since flusher thread may be doing for example sync in + * parallel and if we move the inode, it could get skipped. So here we + * make sure inode is on some writeback list and leave it there unless + * we have completely cleaned the inode. + */ + if (!(inode->i_state & I_DIRTY) && + (wbc->sync_mode != WB_SYNC_ALL || + !mapping_tagged(inode->i_mapping, PAGECACHE_TAG_WRITEBACK))) + goto out; + inode->i_state |= I_SYNC; + spin_unlock(&inode->i_lock); + + ret = __writeback_single_inode(inode, wbc); + + spin_lock(&wb->list_lock); + spin_lock(&inode->i_lock); + /* + * If inode is clean, remove it from writeback lists. Otherwise don't + * touch it. See comment above for explanation. + */ + if (!(inode->i_state & I_DIRTY)) + list_del_init(&inode->i_wb_list); + spin_unlock(&wb->list_lock); + inode_sync_complete(inode); +out: + spin_unlock(&inode->i_lock); + return ret; +} - sb->s_count++; - spin_unlock(&sb_lock); +static long writeback_chunk_size(struct backing_dev_info *bdi, + struct wb_writeback_work *work) +{ + long pages; - if (down_read_trylock(&sb->s_umount)) { - if (sb->s_root) - return true; - up_read(&sb->s_umount); + /* + * WB_SYNC_ALL mode does livelock avoidance by syncing dirty + * inodes/pages in one big loop. Setting wbc.nr_to_write=LONG_MAX + * here avoids calling into writeback_inodes_wb() more than once. + * + * The intended call sequence for WB_SYNC_ALL writeback is: + * + * wb_writeback() + * writeback_sb_inodes() <== called only once + * write_cache_pages() <== called once for each inode + * (quickly) tag currently dirty pages + * (maybe slowly) sync all tagged pages + */ + if (work->sync_mode == WB_SYNC_ALL || work->tagged_writepages) + pages = LONG_MAX; + else { + pages = min(bdi->avg_write_bandwidth / 2, + global_dirty_limit / DIRTY_SCOPE); + pages = min(pages, work->nr_pages); + pages = round_down(pages + MIN_WRITEBACK_PAGES, + MIN_WRITEBACK_PAGES); } - put_super(sb); - return false; + return pages; } /* * Write a portion of b_io inodes which belong to @sb. * - * If @only_this_sb is true, then find and write all such - * inodes. Otherwise write only ones which go sequentially - * in reverse order. - * - * Return 1, if the caller writeback routine should be - * interrupted. Otherwise return 0. + * Return the number of pages and/or inodes written. */ -static int writeback_sb_inodes(struct super_block *sb, struct bdi_writeback *wb, - struct writeback_control *wbc, bool only_this_sb) +static long writeback_sb_inodes(struct super_block *sb, + struct bdi_writeback *wb, + struct wb_writeback_work *work) { + struct writeback_control wbc = { + .sync_mode = work->sync_mode, + .tagged_writepages = work->tagged_writepages, + .for_kupdate = work->for_kupdate, + .for_background = work->for_background, + .for_sync = work->for_sync, + .range_cyclic = work->range_cyclic, + .range_start = 0, + .range_end = LLONG_MAX, + }; + unsigned long start_time = jiffies; + long write_chunk; + long wrote = 0; /* count both pages and inodes */ + while (!list_empty(&wb->b_io)) { - long pages_skipped; struct inode *inode = wb_inode(wb->b_io.prev); if (inode->i_sb != sb) { - if (only_this_sb) { + if (work->sb) { /* * We only want to write back data for this * superblock, move all inodes not belonging * to it back onto the dirty list. */ - redirty_tail(inode); + redirty_tail(inode, wb); continue; } @@ -484,109 +630,164 @@ static int writeback_sb_inodes(struct super_block *sb, struct bdi_writeback *wb, * Bounce back to the caller to unpin this and * pin the next superblock. */ - return 0; + break; } /* - * Don't bother with new inodes or inodes beeing freed, first - * kind does not need peridic writeout yet, and for the latter + * Don't bother with new inodes or inodes being freed, first + * kind does not need periodic writeout yet, and for the latter * kind writeout is handled by the freer. */ + spin_lock(&inode->i_lock); if (inode->i_state & (I_NEW | I_FREEING | I_WILL_FREE)) { - requeue_io(inode); + spin_unlock(&inode->i_lock); + redirty_tail(inode, wb); continue; } + if ((inode->i_state & I_SYNC) && wbc.sync_mode != WB_SYNC_ALL) { + /* + * If this inode is locked for writeback and we are not + * doing writeback-for-data-integrity, move it to + * b_more_io so that writeback can proceed with the + * other inodes on s_io. + * + * We'll have another go at writing back this inode + * when we completed a full scan of b_io. + */ + spin_unlock(&inode->i_lock); + requeue_io(inode, wb); + trace_writeback_sb_inodes_requeue(inode); + continue; + } + spin_unlock(&wb->list_lock); /* - * Was this inode dirtied after sync_sb_inodes was called? - * This keeps sync from extra jobs and livelock. + * We already requeued the inode if it had I_SYNC set and we + * are doing WB_SYNC_NONE writeback. So this catches only the + * WB_SYNC_ALL case. */ - if (inode_dirtied_after(inode, wbc->wb_start)) - return 1; - - __iget(inode); - pages_skipped = wbc->pages_skipped; - writeback_single_inode(inode, wbc); - if (wbc->pages_skipped != pages_skipped) { - /* - * writeback is not making progress due to locked - * buffers. Skip this inode for now. - */ - redirty_tail(inode); + if (inode->i_state & I_SYNC) { + /* Wait for I_SYNC. This function drops i_lock... */ + inode_sleep_on_writeback(inode); + /* Inode may be gone, start again */ + spin_lock(&wb->list_lock); + continue; } - spin_unlock(&inode_lock); - iput(inode); - cond_resched(); - spin_lock(&inode_lock); - if (wbc->nr_to_write <= 0) { - wbc->more_io = 1; - return 1; + inode->i_state |= I_SYNC; + spin_unlock(&inode->i_lock); + + write_chunk = writeback_chunk_size(wb->bdi, work); + wbc.nr_to_write = write_chunk; + wbc.pages_skipped = 0; + + /* + * We use I_SYNC to pin the inode in memory. While it is set + * evict_inode() will wait so the inode cannot be freed. + */ + __writeback_single_inode(inode, &wbc); + + work->nr_pages -= write_chunk - wbc.nr_to_write; + wrote += write_chunk - wbc.nr_to_write; + spin_lock(&wb->list_lock); + spin_lock(&inode->i_lock); + if (!(inode->i_state & I_DIRTY)) + wrote++; + requeue_inode(inode, wb, &wbc); + inode_sync_complete(inode); + spin_unlock(&inode->i_lock); + cond_resched_lock(&wb->list_lock); + /* + * bail out to wb_writeback() often enough to check + * background threshold and other termination conditions. + */ + if (wrote) { + if (time_is_before_jiffies(start_time + HZ / 10UL)) + break; + if (work->nr_pages <= 0) + break; } - if (!list_empty(&wb->b_more_io)) - wbc->more_io = 1; } - /* b_io is empty */ - return 1; + return wrote; } -void writeback_inodes_wb(struct bdi_writeback *wb, - struct writeback_control *wbc) +static long __writeback_inodes_wb(struct bdi_writeback *wb, + struct wb_writeback_work *work) { - int ret = 0; - - if (!wbc->wb_start) - wbc->wb_start = jiffies; /* livelock avoidance */ - spin_lock(&inode_lock); - if (!wbc->for_kupdate || list_empty(&wb->b_io)) - queue_io(wb, wbc->older_than_this); + unsigned long start_time = jiffies; + long wrote = 0; while (!list_empty(&wb->b_io)) { struct inode *inode = wb_inode(wb->b_io.prev); struct super_block *sb = inode->i_sb; - if (!pin_sb_for_writeback(sb)) { - requeue_io(inode); + if (!grab_super_passive(sb)) { + /* + * grab_super_passive() may fail consistently due to + * s_umount being grabbed by someone else. Don't use + * requeue_io() to avoid busy retrying the inode/sb. + */ + redirty_tail(inode, wb); continue; } - ret = writeback_sb_inodes(sb, wb, wbc, false); + wrote += writeback_sb_inodes(sb, wb, work); drop_super(sb); - if (ret) - break; + /* refer to the same tests at the end of writeback_sb_inodes */ + if (wrote) { + if (time_is_before_jiffies(start_time + HZ / 10UL)) + break; + if (work->nr_pages <= 0) + break; + } } - spin_unlock(&inode_lock); /* Leave any unwritten inodes on b_io */ + return wrote; } -static void __writeback_inodes_sb(struct super_block *sb, - struct bdi_writeback *wb, struct writeback_control *wbc) +static long writeback_inodes_wb(struct bdi_writeback *wb, long nr_pages, + enum wb_reason reason) { - WARN_ON(!rwsem_is_locked(&sb->s_umount)); + struct wb_writeback_work work = { + .nr_pages = nr_pages, + .sync_mode = WB_SYNC_NONE, + .range_cyclic = 1, + .reason = reason, + }; - spin_lock(&inode_lock); - if (!wbc->for_kupdate || list_empty(&wb->b_io)) - queue_io(wb, wbc->older_than_this); - writeback_sb_inodes(sb, wb, wbc, true); - spin_unlock(&inode_lock); -} + spin_lock(&wb->list_lock); + if (list_empty(&wb->b_io)) + queue_io(wb, &work); + __writeback_inodes_wb(wb, &work); + spin_unlock(&wb->list_lock); -/* - * The maximum number of pages to writeout in a single bdi flush/kupdate - * operation. We do this so we don't hold I_SYNC against an inode for - * enormous amounts of time, which would block a userspace task which has - * been forced to throttle against that inode. Also, the code reevaluates - * the dirty each time it has written this many pages. - */ -#define MAX_WRITEBACK_PAGES 1024 + return nr_pages - work.nr_pages; +} -static inline bool over_bground_thresh(void) +static bool over_bground_thresh(struct backing_dev_info *bdi) { unsigned long background_thresh, dirty_thresh; global_dirty_limits(&background_thresh, &dirty_thresh); - return (global_page_state(NR_FILE_DIRTY) + - global_page_state(NR_UNSTABLE_NFS) > background_thresh); + if (global_page_state(NR_FILE_DIRTY) + + global_page_state(NR_UNSTABLE_NFS) > background_thresh) + return true; + + if (bdi_stat(bdi, BDI_RECLAIMABLE) > + bdi_dirty_limit(bdi, background_thresh)) + return true; + + return false; +} + +/* + * Called under wb->list_lock. If there are multiple wb per bdi, + * only the flusher working on the first wb should do it. + */ +static void wb_update_bandwidth(struct bdi_writeback *wb, + unsigned long start_time) +{ + __bdi_update_bandwidth(wb->bdi, 0, 0, 0, 0, 0, start_time); } /* @@ -607,28 +808,16 @@ static inline bool over_bground_thresh(void) static long wb_writeback(struct bdi_writeback *wb, struct wb_writeback_work *work) { - struct writeback_control wbc = { - .sync_mode = work->sync_mode, - .older_than_this = NULL, - .for_kupdate = work->for_kupdate, - .for_background = work->for_background, - .range_cyclic = work->range_cyclic, - }; + unsigned long wb_start = jiffies; + long nr_pages = work->nr_pages; unsigned long oldest_jif; - long wrote = 0; struct inode *inode; + long progress; - if (wbc.for_kupdate) { - wbc.older_than_this = &oldest_jif; - oldest_jif = jiffies - - msecs_to_jiffies(dirty_expire_interval * 10); - } - if (!wbc.range_cyclic) { - wbc.range_start = 0; - wbc.range_end = LLONG_MAX; - } + oldest_jif = jiffies; + work->older_than_this = &oldest_jif; - wbc.wb_start = jiffies; /* livelock avoidance */ + spin_lock(&wb->list_lock); for (;;) { /* * Stop writeback when nr_pages has been consumed @@ -637,56 +826,78 @@ static long wb_writeback(struct bdi_writeback *wb, break; /* + * Background writeout and kupdate-style writeback may + * run forever. Stop them if there is other work to do + * so that e.g. sync can proceed. They'll be restarted + * after the other works are all done. + */ + if ((work->for_background || work->for_kupdate) && + !list_empty(&wb->bdi->work_list)) + break; + + /* * For background writeout, stop when we are below the * background dirty threshold */ - if (work->for_background && !over_bground_thresh()) + if (work->for_background && !over_bground_thresh(wb->bdi)) break; - wbc.more_io = 0; - wbc.nr_to_write = MAX_WRITEBACK_PAGES; - wbc.pages_skipped = 0; + /* + * Kupdate and background works are special and we want to + * include all inodes that need writing. Livelock avoidance is + * handled by these works yielding to any other work so we are + * safe. + */ + if (work->for_kupdate) { + oldest_jif = jiffies - + msecs_to_jiffies(dirty_expire_interval * 10); + } else if (work->for_background) + oldest_jif = jiffies; - trace_wbc_writeback_start(&wbc, wb->bdi); + trace_writeback_start(wb->bdi, work); + if (list_empty(&wb->b_io)) + queue_io(wb, work); if (work->sb) - __writeback_inodes_sb(work->sb, wb, &wbc); + progress = writeback_sb_inodes(work->sb, wb, work); else - writeback_inodes_wb(wb, &wbc); - trace_wbc_writeback_written(&wbc, wb->bdi); + progress = __writeback_inodes_wb(wb, work); + trace_writeback_written(wb->bdi, work); - work->nr_pages -= MAX_WRITEBACK_PAGES - wbc.nr_to_write; - wrote += MAX_WRITEBACK_PAGES - wbc.nr_to_write; + wb_update_bandwidth(wb, wb_start); /* - * If we consumed everything, see if we have more + * Did we write something? Try for more + * + * Dirty inodes are moved to b_io for writeback in batches. + * The completion of the current batch does not necessarily + * mean the overall work is done. So we keep looping as long + * as made some progress on cleaning pages or inodes. */ - if (wbc.nr_to_write <= 0) + if (progress) continue; /* - * Didn't write everything and we don't have more IO, bail + * No more inodes for IO, bail */ - if (!wbc.more_io) + if (list_empty(&wb->b_more_io)) break; /* - * Did we write something? Try for more - */ - if (wbc.nr_to_write < MAX_WRITEBACK_PAGES) - continue; - /* * Nothing written. Wait for some inode to * become available for writeback. Otherwise * we'll just busyloop. */ - spin_lock(&inode_lock); if (!list_empty(&wb->b_more_io)) { + trace_writeback_wait(wb->bdi, work); inode = wb_inode(wb->b_more_io.prev); - trace_wbc_writeback_wait(&wbc, wb->bdi); - inode_wait_for_writeback(inode); + spin_lock(&inode->i_lock); + spin_unlock(&wb->list_lock); + /* This function drops i_lock... */ + inode_sleep_on_writeback(inode); + spin_lock(&wb->list_lock); } - spin_unlock(&inode_lock); } + spin_unlock(&wb->list_lock); - return wrote; + return nr_pages - work->nr_pages; } /* @@ -718,6 +929,24 @@ static unsigned long get_nr_dirty_pages(void) get_nr_dirty_inodes(); } +static long wb_check_background_flush(struct bdi_writeback *wb) +{ + if (over_bground_thresh(wb->bdi)) { + + struct wb_writeback_work work = { + .nr_pages = LONG_MAX, + .sync_mode = WB_SYNC_NONE, + .for_background = 1, + .range_cyclic = 1, + .reason = WB_REASON_BACKGROUND, + }; + + return wb_writeback(wb, &work); + } + + return 0; +} + static long wb_check_old_data_flush(struct bdi_writeback *wb) { unsigned long expired; @@ -743,6 +972,7 @@ static long wb_check_old_data_flush(struct bdi_writeback *wb) .sync_mode = WB_SYNC_NONE, .for_kupdate = 1, .range_cyclic = 1, + .reason = WB_REASON_PERIODIC, }; return wb_writeback(wb, &work); @@ -754,7 +984,7 @@ static long wb_check_old_data_flush(struct bdi_writeback *wb) /* * Retrieve work items and do the writeback they describe */ -long wb_do_writeback(struct bdi_writeback *wb, int force_wait) +static long wb_do_writeback(struct bdi_writeback *wb) { struct backing_dev_info *bdi = wb->bdi; struct wb_writeback_work *work; @@ -762,12 +992,6 @@ long wb_do_writeback(struct bdi_writeback *wb, int force_wait) set_bit(BDI_writeback_running, &wb->bdi->state); while ((work = get_next_work_item(bdi)) != NULL) { - /* - * Override sync mode, in case we must wait for completion - * because this thread is exiting now. - */ - if (force_wait) - work->sync_mode = WB_SYNC_ALL; trace_writeback_exec(bdi, work); @@ -787,6 +1011,7 @@ long wb_do_writeback(struct bdi_writeback *wb, int force_wait) * Check for periodic writeback, kupdated() style */ wrote += wb_check_old_data_flush(wb); + wrote += wb_check_background_flush(wb); clear_bit(BDI_writeback_running, &wb->bdi->state); return wrote; @@ -794,86 +1019,65 @@ long wb_do_writeback(struct bdi_writeback *wb, int force_wait) /* * Handle writeback of dirty data for the device backed by this bdi. Also - * wakes up periodically and does kupdated style flushing. + * reschedules periodically and does kupdated style flushing. */ -int bdi_writeback_thread(void *data) +void bdi_writeback_workfn(struct work_struct *work) { - struct bdi_writeback *wb = data; + struct bdi_writeback *wb = container_of(to_delayed_work(work), + struct bdi_writeback, dwork); struct backing_dev_info *bdi = wb->bdi; long pages_written; + set_worker_desc("flush-%s", dev_name(bdi->dev)); current->flags |= PF_SWAPWRITE; - set_freezable(); - wb->last_active = jiffies; - /* - * Our parent may run at a different priority, just set us to normal - */ - set_user_nice(current, 0); - - trace_writeback_thread_start(bdi); - - while (!kthread_should_stop()) { + if (likely(!current_is_workqueue_rescuer() || + !test_bit(BDI_registered, &bdi->state))) { /* - * Remove own delayed wake-up timer, since we are already awake - * and we'll take care of the preriodic write-back. + * The normal path. Keep writing back @bdi until its + * work_list is empty. Note that this path is also taken + * if @bdi is shutting down even when we're running off the + * rescuer as work_list needs to be drained. */ - del_timer(&wb->wakeup_timer); - - pages_written = wb_do_writeback(wb, 0); - + do { + pages_written = wb_do_writeback(wb); + trace_writeback_pages_written(pages_written); + } while (!list_empty(&bdi->work_list)); + } else { + /* + * bdi_wq can't get enough workers and we're running off + * the emergency worker. Don't hog it. Hopefully, 1024 is + * enough for efficient IO. + */ + pages_written = writeback_inodes_wb(&bdi->wb, 1024, + WB_REASON_FORKER_THREAD); trace_writeback_pages_written(pages_written); - - if (pages_written) - wb->last_active = jiffies; - - set_current_state(TASK_INTERRUPTIBLE); - if (!list_empty(&bdi->work_list) || kthread_should_stop()) { - __set_current_state(TASK_RUNNING); - continue; - } - - if (wb_has_dirty_io(wb) && dirty_writeback_interval) - schedule_timeout(msecs_to_jiffies(dirty_writeback_interval * 10)); - else { - /* - * We have nothing to do, so can go sleep without any - * timeout and save power. When a work is queued or - * something is made dirty - we will be woken up. - */ - schedule(); - } - - try_to_freeze(); } - /* Flush any work that raced with us exiting */ if (!list_empty(&bdi->work_list)) - wb_do_writeback(wb, 1); + mod_delayed_work(bdi_wq, &wb->dwork, 0); + else if (wb_has_dirty_io(wb) && dirty_writeback_interval) + bdi_wakeup_thread_delayed(bdi); - trace_writeback_thread_stop(bdi); - return 0; + current->flags &= ~PF_SWAPWRITE; } - /* * Start writeback of `nr_pages' pages. If `nr_pages' is zero, write back * the whole world. */ -void wakeup_flusher_threads(long nr_pages) +void wakeup_flusher_threads(long nr_pages, enum wb_reason reason) { struct backing_dev_info *bdi; - if (!nr_pages) { - nr_pages = global_page_state(NR_FILE_DIRTY) + - global_page_state(NR_UNSTABLE_NFS); - } + if (!nr_pages) + nr_pages = get_nr_dirty_pages(); rcu_read_lock(); list_for_each_entry_rcu(bdi, &bdi_list, bdi_list) { if (!bdi_has_dirty_io(bdi)) continue; - __bdi_start_writeback(bdi, nr_pages, false, false); + __bdi_start_writeback(bdi, nr_pages, false, reason); } rcu_read_unlock(); } @@ -917,9 +1121,6 @@ static noinline void block_dump___mark_inode_dirty(struct inode *inode) * In short, make sure you hash any inodes _before_ you start marking * them dirty. * - * This function *must* be atomic for the I_DIRTY_PAGES case - - * set_page_dirty() is called under spinlock in several places. - * * Note that for blockdevs, inode->dirtied_when represents the dirtying time of * the block-special inode (/dev/hda1) itself. And the ->dirtied_when field of * the kernel-internal blockdev inode represents the dirtying time of the @@ -931,15 +1132,18 @@ void __mark_inode_dirty(struct inode *inode, int flags) { struct super_block *sb = inode->i_sb; struct backing_dev_info *bdi = NULL; - bool wakeup_bdi = false; /* * Don't do this for I_DIRTY_PAGES - that doesn't actually * dirty the inode itself */ if (flags & (I_DIRTY_SYNC | I_DIRTY_DATASYNC)) { + trace_writeback_dirty_inode_start(inode, flags); + if (sb->s_op->dirty_inode) - sb->s_op->dirty_inode(inode); + sb->s_op->dirty_inode(inode, flags); + + trace_writeback_dirty_inode(inode, flags); } /* @@ -955,7 +1159,7 @@ void __mark_inode_dirty(struct inode *inode, int flags) if (unlikely(block_dump)) block_dump___mark_inode_dirty(inode); - spin_lock(&inode_lock); + spin_lock(&inode->i_lock); if ((inode->i_state & flags) != flags) { const int was_dirty = inode->i_state & I_DIRTY; @@ -967,7 +1171,7 @@ void __mark_inode_dirty(struct inode *inode, int flags) * superblock list, based upon its state. */ if (inode->i_state & I_SYNC) - goto out; + goto out_unlock_inode; /* * Only add valid (hashed) inodes to the superblock's @@ -975,18 +1179,21 @@ void __mark_inode_dirty(struct inode *inode, int flags) */ if (!S_ISBLK(inode->i_mode)) { if (inode_unhashed(inode)) - goto out; + goto out_unlock_inode; } if (inode->i_state & I_FREEING) - goto out; + goto out_unlock_inode; /* * If the inode was already on b_dirty/b_io/b_more_io, don't * reposition it (that would break b_dirty time-ordering). */ if (!was_dirty) { + bool wakeup_bdi = false; bdi = inode_to_bdi(inode); + spin_unlock(&inode->i_lock); + spin_lock(&bdi->wb.list_lock); if (bdi_cap_writeback_dirty(bdi)) { WARN(!test_bit(BDI_registered, &bdi->state), "bdi-%s not registered\n", bdi->name); @@ -1003,33 +1210,19 @@ void __mark_inode_dirty(struct inode *inode, int flags) inode->dirtied_when = jiffies; list_move(&inode->i_wb_list, &bdi->wb.b_dirty); + spin_unlock(&bdi->wb.list_lock); + + if (wakeup_bdi) + bdi_wakeup_thread_delayed(bdi); + return; } } -out: - spin_unlock(&inode_lock); +out_unlock_inode: + spin_unlock(&inode->i_lock); - if (wakeup_bdi) - bdi_wakeup_thread_delayed(bdi); } EXPORT_SYMBOL(__mark_inode_dirty); -/* - * Write out a superblock's list of dirty inodes. A wait will be performed - * upon no inodes, all inodes or the final one, depending upon sync_mode. - * - * If older_than_this is non-NULL, then only write out inodes which - * had their first dirtying at a time earlier than *older_than_this. - * - * If `bdi' is non-zero then we're being asked to writeback a specific queue. - * This function assumes that the blockdev superblock's inodes are backed by - * a variety of queues, so all inodes are searched. For other superblocks, - * assume that all inodes are backed by the same queue. - * - * The inodes to be written are parked on bdi->b_io. They are moved back onto - * bdi->b_dirty as they are selected for writing. This way, none can be missed - * on the writer throttling path, and we get decent balancing between many - * throttled threads: we don't want them all piling up on inode_sync_wait. - */ static void wait_sb_inodes(struct super_block *sb) { struct inode *inode, *old_inode = NULL; @@ -1040,7 +1233,7 @@ static void wait_sb_inodes(struct super_block *sb) */ WARN_ON(!rwsem_is_locked(&sb->s_umount)); - spin_lock(&inode_lock); + spin_lock(&inode_sb_list_lock); /* * Data integrity sync. Must wait for all pages under writeback, @@ -1050,22 +1243,25 @@ static void wait_sb_inodes(struct super_block *sb) * we still have to wait for that writeout. */ list_for_each_entry(inode, &sb->s_inodes, i_sb_list) { - struct address_space *mapping; + struct address_space *mapping = inode->i_mapping; - if (inode->i_state & (I_FREEING|I_WILL_FREE|I_NEW)) - continue; - mapping = inode->i_mapping; - if (mapping->nrpages == 0) + spin_lock(&inode->i_lock); + if ((inode->i_state & (I_FREEING|I_WILL_FREE|I_NEW)) || + (mapping->nrpages == 0)) { + spin_unlock(&inode->i_lock); continue; + } __iget(inode); - spin_unlock(&inode_lock); + spin_unlock(&inode->i_lock); + spin_unlock(&inode_sb_list_lock); + /* - * We hold a reference to 'inode' so it couldn't have - * been removed from s_inodes list while we dropped the - * inode_lock. We cannot iput the inode now as we can - * be holding the last reference and we cannot iput it - * under inode_lock. So we keep the reference and iput - * it later. + * We hold a reference to 'inode' so it couldn't have been + * removed from s_inodes list while we dropped the + * inode_sb_list_lock. We cannot iput the inode now as we can + * be holding the last reference and we cannot iput it under + * inode_sb_list_lock. So we keep the reference and iput it + * later. */ iput(old_inode); old_inode = inode; @@ -1074,9 +1270,9 @@ static void wait_sb_inodes(struct super_block *sb) cond_resched(); - spin_lock(&inode_lock); + spin_lock(&inode_sb_list_lock); } - spin_unlock(&inode_lock); + spin_unlock(&inode_sb_list_lock); iput(old_inode); } @@ -1084,21 +1280,28 @@ static void wait_sb_inodes(struct super_block *sb) * writeback_inodes_sb_nr - writeback dirty inodes from given super_block * @sb: the superblock * @nr: the number of pages to write + * @reason: reason why some writeback work initiated * * Start writeback on some inodes on this super_block. No guarantees are made * on how many (if any) will be written, and this function does not wait * for IO completion of submitted IO. */ -void writeback_inodes_sb_nr(struct super_block *sb, unsigned long nr) +void writeback_inodes_sb_nr(struct super_block *sb, + unsigned long nr, + enum wb_reason reason) { DECLARE_COMPLETION_ONSTACK(done); struct wb_writeback_work work = { - .sb = sb, - .sync_mode = WB_SYNC_NONE, - .done = &done, - .nr_pages = nr, + .sb = sb, + .sync_mode = WB_SYNC_NONE, + .tagged_writepages = 1, + .done = &done, + .nr_pages = nr, + .reason = reason, }; + if (sb->s_bdi == &noop_backing_dev_info) + return; WARN_ON(!rwsem_is_locked(&sb->s_umount)); bdi_queue_work(sb->s_bdi, &work); wait_for_completion(&done); @@ -1108,63 +1311,63 @@ EXPORT_SYMBOL(writeback_inodes_sb_nr); /** * writeback_inodes_sb - writeback dirty inodes from given super_block * @sb: the superblock + * @reason: reason why some writeback work was initiated * * Start writeback on some inodes on this super_block. No guarantees are made * on how many (if any) will be written, and this function does not wait * for IO completion of submitted IO. */ -void writeback_inodes_sb(struct super_block *sb) +void writeback_inodes_sb(struct super_block *sb, enum wb_reason reason) { - return writeback_inodes_sb_nr(sb, get_nr_dirty_pages()); + return writeback_inodes_sb_nr(sb, get_nr_dirty_pages(), reason); } EXPORT_SYMBOL(writeback_inodes_sb); /** - * writeback_inodes_sb_if_idle - start writeback if none underway + * try_to_writeback_inodes_sb_nr - try to start writeback if none underway * @sb: the superblock + * @nr: the number of pages to write + * @reason: the reason of writeback * - * Invoke writeback_inodes_sb if no writeback is currently underway. + * Invoke writeback_inodes_sb_nr if no writeback is currently underway. * Returns 1 if writeback was started, 0 if not. */ -int writeback_inodes_sb_if_idle(struct super_block *sb) +int try_to_writeback_inodes_sb_nr(struct super_block *sb, + unsigned long nr, + enum wb_reason reason) { - if (!writeback_in_progress(sb->s_bdi)) { - down_read(&sb->s_umount); - writeback_inodes_sb(sb); - up_read(&sb->s_umount); + if (writeback_in_progress(sb->s_bdi)) return 1; - } else + + if (!down_read_trylock(&sb->s_umount)) return 0; + + writeback_inodes_sb_nr(sb, nr, reason); + up_read(&sb->s_umount); + return 1; } -EXPORT_SYMBOL(writeback_inodes_sb_if_idle); +EXPORT_SYMBOL(try_to_writeback_inodes_sb_nr); /** - * writeback_inodes_sb_if_idle - start writeback if none underway + * try_to_writeback_inodes_sb - try to start writeback if none underway * @sb: the superblock - * @nr: the number of pages to write + * @reason: reason why some writeback work was initiated * - * Invoke writeback_inodes_sb if no writeback is currently underway. + * Implement by try_to_writeback_inodes_sb_nr() * Returns 1 if writeback was started, 0 if not. */ -int writeback_inodes_sb_nr_if_idle(struct super_block *sb, - unsigned long nr) +int try_to_writeback_inodes_sb(struct super_block *sb, enum wb_reason reason) { - if (!writeback_in_progress(sb->s_bdi)) { - down_read(&sb->s_umount); - writeback_inodes_sb_nr(sb, nr); - up_read(&sb->s_umount); - return 1; - } else - return 0; + return try_to_writeback_inodes_sb_nr(sb, get_nr_dirty_pages(), reason); } -EXPORT_SYMBOL(writeback_inodes_sb_nr_if_idle); +EXPORT_SYMBOL(try_to_writeback_inodes_sb); /** * sync_inodes_sb - sync sb inode pages * @sb: the superblock * * This function writes and waits on any dirty inode belonging to this - * super_block. The number of pages synced is returned. + * super_block. */ void sync_inodes_sb(struct super_block *sb) { @@ -1175,8 +1378,13 @@ void sync_inodes_sb(struct super_block *sb) .nr_pages = LONG_MAX, .range_cyclic = 0, .done = &done, + .reason = WB_REASON_SYNC, + .for_sync = 1, }; + /* Nothing to do? */ + if (sb->s_bdi == &noop_backing_dev_info) + return; WARN_ON(!rwsem_is_locked(&sb->s_umount)); bdi_queue_work(sb->s_bdi, &work); @@ -1198,7 +1406,7 @@ EXPORT_SYMBOL(sync_inodes_sb); */ int write_inode_now(struct inode *inode, int sync) { - int ret; + struct bdi_writeback *wb = &inode_to_bdi(inode)->wb; struct writeback_control wbc = { .nr_to_write = LONG_MAX, .sync_mode = sync ? WB_SYNC_ALL : WB_SYNC_NONE, @@ -1210,12 +1418,7 @@ int write_inode_now(struct inode *inode, int sync) wbc.nr_to_write = 0; might_sleep(); - spin_lock(&inode_lock); - ret = writeback_single_inode(inode, &wbc); - spin_unlock(&inode_lock); - if (sync) - inode_sync_wait(inode); - return ret; + return writeback_single_inode(inode, wb, &wbc); } EXPORT_SYMBOL(write_inode_now); @@ -1232,21 +1435,16 @@ EXPORT_SYMBOL(write_inode_now); */ int sync_inode(struct inode *inode, struct writeback_control *wbc) { - int ret; - - spin_lock(&inode_lock); - ret = writeback_single_inode(inode, wbc); - spin_unlock(&inode_lock); - return ret; + return writeback_single_inode(inode, &inode_to_bdi(inode)->wb, wbc); } EXPORT_SYMBOL(sync_inode); /** - * sync_inode - write an inode to disk + * sync_inode_metadata - write an inode to disk * @inode: the inode to sync * @wait: wait for I/O to complete. * - * Write an inode to disk and adjust it's dirty state after completion. + * Write an inode to disk and adjust its dirty state after completion. * * Note: only writes the actual inode, no associated data or other metadata. */ |