diff options
author | Linus Torvalds <torvalds@linux-foundation.org> | 2010-06-29 10:42:52 -0700 |
---|---|---|
committer | Linus Torvalds <torvalds@linux-foundation.org> | 2010-06-29 10:42:52 -0700 |
commit | 984bc9601f64fd341b8573021d7c999f1f1499a9 (patch) | |
tree | 06c616a6285b00d1e577902face3e8a986370b34 /fs/fs-writeback.c | |
parent | 57439f878afafefad8836ebf5c49da2a0a746105 (diff) | |
parent | 1b99973f1c82707e46e8cb9416865a1e955e8f8c (diff) |
Merge branch 'for-linus' of git://git.kernel.dk/linux-2.6-block
* 'for-linus' of git://git.kernel.dk/linux-2.6-block:
block: Don't count_vm_events for discard bio in submit_bio.
cfq: fix recursive call in cfq_blkiocg_update_completion_stats()
cfq-iosched: Fixed boot warning with BLK_CGROUP=y and CFQ_GROUP_IOSCHED=n
cfq: Don't allow queue merges for queues that have no process references
block: fix DISCARD_BARRIER requests
cciss: set SCSI max cmd len to 16, as default is wrong
cpqarray: fix two more wrong section type
cpqarray: fix wrong __init type on pci probe function
drbd: Fixed a race between disk-attach and unexpected state changes
writeback: fix pin_sb_for_writeback
writeback: add missing requeue_io in writeback_inodes_wb
writeback: simplify and split bdi_start_writeback
writeback: simplify wakeup_flusher_threads
writeback: fix writeback_inodes_wb from writeback_inodes_sb
writeback: enforce s_umount locking in writeback_inodes_sb
writeback: queue work on stack in writeback_inodes_sb
writeback: fix writeback completion notifications
Diffstat (limited to 'fs/fs-writeback.c')
-rw-r--r-- | fs/fs-writeback.c | 254 |
1 files changed, 107 insertions, 147 deletions
diff --git a/fs/fs-writeback.c b/fs/fs-writeback.c index 1d1088f48bc2..0609607d3955 100644 --- a/fs/fs-writeback.c +++ b/fs/fs-writeback.c @@ -63,24 +63,16 @@ struct bdi_work { }; enum { - WS_USED_B = 0, - WS_ONSTACK_B, + WS_INPROGRESS = 0, + WS_ONSTACK, }; -#define WS_USED (1 << WS_USED_B) -#define WS_ONSTACK (1 << WS_ONSTACK_B) - -static inline bool bdi_work_on_stack(struct bdi_work *work) -{ - return test_bit(WS_ONSTACK_B, &work->state); -} - static inline void bdi_work_init(struct bdi_work *work, struct wb_writeback_args *args) { INIT_RCU_HEAD(&work->rcu_head); work->args = *args; - work->state = WS_USED; + __set_bit(WS_INPROGRESS, &work->state); } /** @@ -95,43 +87,16 @@ int writeback_in_progress(struct backing_dev_info *bdi) return !list_empty(&bdi->work_list); } -static void bdi_work_clear(struct bdi_work *work) -{ - clear_bit(WS_USED_B, &work->state); - smp_mb__after_clear_bit(); - /* - * work can have disappeared at this point. bit waitq functions - * should be able to tolerate this, provided bdi_sched_wait does - * not dereference it's pointer argument. - */ - wake_up_bit(&work->state, WS_USED_B); -} - static void bdi_work_free(struct rcu_head *head) { struct bdi_work *work = container_of(head, struct bdi_work, rcu_head); - if (!bdi_work_on_stack(work)) - kfree(work); - else - bdi_work_clear(work); -} - -static void wb_work_complete(struct bdi_work *work) -{ - const enum writeback_sync_modes sync_mode = work->args.sync_mode; - int onstack = bdi_work_on_stack(work); + clear_bit(WS_INPROGRESS, &work->state); + smp_mb__after_clear_bit(); + wake_up_bit(&work->state, WS_INPROGRESS); - /* - * For allocated work, we can clear the done/seen bit right here. - * For on-stack work, we need to postpone both the clear and free - * to after the RCU grace period, since the stack could be invalidated - * as soon as bdi_work_clear() has done the wakeup. - */ - if (!onstack) - bdi_work_clear(work); - if (sync_mode == WB_SYNC_NONE || onstack) - call_rcu(&work->rcu_head, bdi_work_free); + if (!test_bit(WS_ONSTACK, &work->state)) + kfree(work); } static void wb_clear_pending(struct bdi_writeback *wb, struct bdi_work *work) @@ -147,7 +112,7 @@ static void wb_clear_pending(struct bdi_writeback *wb, struct bdi_work *work) list_del_rcu(&work->list); spin_unlock(&bdi->wb_lock); - wb_work_complete(work); + call_rcu(&work->rcu_head, bdi_work_free); } } @@ -185,9 +150,9 @@ static void bdi_queue_work(struct backing_dev_info *bdi, struct bdi_work *work) * Used for on-stack allocated work items. The caller needs to wait until * the wb threads have acked the work before it's safe to continue. */ -static void bdi_wait_on_work_clear(struct bdi_work *work) +static void bdi_wait_on_work_done(struct bdi_work *work) { - wait_on_bit(&work->state, WS_USED_B, bdi_sched_wait, + wait_on_bit(&work->state, WS_INPROGRESS, bdi_sched_wait, TASK_UNINTERRUPTIBLE); } @@ -213,37 +178,28 @@ static void bdi_alloc_queue_work(struct backing_dev_info *bdi, } /** - * bdi_sync_writeback - start and wait for writeback - * @bdi: the backing device to write from + * bdi_queue_work_onstack - start and wait for writeback * @sb: write inodes from this super_block * * Description: - * This does WB_SYNC_ALL data integrity writeback and waits for the - * IO to complete. Callers must hold the sb s_umount semaphore for + * This function initiates writeback and waits for the operation to + * complete. Callers must hold the sb s_umount semaphore for * reading, to avoid having the super disappear before we are done. */ -static void bdi_sync_writeback(struct backing_dev_info *bdi, - struct super_block *sb) +static void bdi_queue_work_onstack(struct wb_writeback_args *args) { - struct wb_writeback_args args = { - .sb = sb, - .sync_mode = WB_SYNC_ALL, - .nr_pages = LONG_MAX, - .range_cyclic = 0, - }; struct bdi_work work; - bdi_work_init(&work, &args); - work.state |= WS_ONSTACK; + bdi_work_init(&work, args); + __set_bit(WS_ONSTACK, &work.state); - bdi_queue_work(bdi, &work); - bdi_wait_on_work_clear(&work); + bdi_queue_work(args->sb->s_bdi, &work); + bdi_wait_on_work_done(&work); } /** * bdi_start_writeback - start writeback * @bdi: the backing device to write from - * @sb: write inodes from this super_block * @nr_pages: the number of pages to write * * Description: @@ -252,25 +208,34 @@ static void bdi_sync_writeback(struct backing_dev_info *bdi, * completion. Caller need not hold sb s_umount semaphore. * */ -void bdi_start_writeback(struct backing_dev_info *bdi, struct super_block *sb, - long nr_pages) +void bdi_start_writeback(struct backing_dev_info *bdi, long nr_pages) { struct wb_writeback_args args = { - .sb = sb, .sync_mode = WB_SYNC_NONE, .nr_pages = nr_pages, .range_cyclic = 1, }; - /* - * We treat @nr_pages=0 as the special case to do background writeback, - * ie. to sync pages until the background dirty threshold is reached. - */ - if (!nr_pages) { - args.nr_pages = LONG_MAX; - args.for_background = 1; - } + bdi_alloc_queue_work(bdi, &args); +} +/** + * bdi_start_background_writeback - start background writeback + * @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. + */ +void bdi_start_background_writeback(struct backing_dev_info *bdi) +{ + struct wb_writeback_args args = { + .sync_mode = WB_SYNC_NONE, + .nr_pages = LONG_MAX, + .for_background = 1, + .range_cyclic = 1, + }; bdi_alloc_queue_work(bdi, &args); } @@ -561,48 +526,30 @@ select_queue: return ret; } -static void unpin_sb_for_writeback(struct super_block *sb) -{ - up_read(&sb->s_umount); - put_super(sb); -} - -enum sb_pin_state { - SB_PINNED, - SB_NOT_PINNED, - SB_PIN_FAILED -}; - /* - * For WB_SYNC_NONE writeback, the caller does not have the sb pinned + * 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. */ -static enum sb_pin_state pin_sb_for_writeback(struct writeback_control *wbc, - struct super_block *sb) +static bool pin_sb_for_writeback(struct super_block *sb) { - /* - * Caller must already hold the ref for this - */ - if (wbc->sync_mode == WB_SYNC_ALL) { - WARN_ON(!rwsem_is_locked(&sb->s_umount)); - return SB_NOT_PINNED; - } spin_lock(&sb_lock); + if (list_empty(&sb->s_instances)) { + spin_unlock(&sb_lock); + return false; + } + sb->s_count++; + spin_unlock(&sb_lock); + if (down_read_trylock(&sb->s_umount)) { - if (sb->s_root) { - spin_unlock(&sb_lock); - return SB_PINNED; - } - /* - * umounted, drop rwsem again and fall through to failure - */ + if (sb->s_root) + return true; up_read(&sb->s_umount); } - sb->s_count--; - spin_unlock(&sb_lock); - return SB_PIN_FAILED; + + put_super(sb); + return false; } /* @@ -681,24 +628,31 @@ static void writeback_inodes_wb(struct bdi_writeback *wb, struct inode *inode = list_entry(wb->b_io.prev, struct inode, i_list); struct super_block *sb = inode->i_sb; - enum sb_pin_state state; - if (wbc->sb && sb != wbc->sb) { - /* super block given and doesn't - match, skip this inode */ - redirty_tail(inode); - continue; - } - state = pin_sb_for_writeback(wbc, sb); + if (wbc->sb) { + /* + * We are requested to write out inodes for a specific + * superblock. This means we already have s_umount + * taken by the caller which also waits for us to + * complete the writeout. + */ + if (sb != wbc->sb) { + redirty_tail(inode); + continue; + } - if (state == SB_PIN_FAILED) { - requeue_io(inode); - continue; + WARN_ON(!rwsem_is_locked(&sb->s_umount)); + + ret = writeback_sb_inodes(sb, wb, wbc); + } else { + if (!pin_sb_for_writeback(sb)) { + requeue_io(inode); + continue; + } + ret = writeback_sb_inodes(sb, wb, wbc); + drop_super(sb); } - ret = writeback_sb_inodes(sb, wb, wbc); - if (state == SB_PINNED) - unpin_sb_for_writeback(sb); if (ret) break; } @@ -911,7 +865,7 @@ long wb_do_writeback(struct bdi_writeback *wb, int force_wait) * If this isn't a data integrity operation, just notify * that we have seen this work and we are now starting it. */ - if (args.sync_mode == WB_SYNC_NONE) + if (!test_bit(WS_ONSTACK, &work->state)) wb_clear_pending(wb, work); wrote += wb_writeback(wb, &args); @@ -920,7 +874,7 @@ long wb_do_writeback(struct bdi_writeback *wb, int force_wait) * This is a data integrity writeback, so only do the * notification when we have completed the work. */ - if (args.sync_mode == WB_SYNC_ALL) + if (test_bit(WS_ONSTACK, &work->state)) wb_clear_pending(wb, work); } @@ -978,42 +932,32 @@ int bdi_writeback_task(struct bdi_writeback *wb) } /* - * Schedule writeback for all backing devices. This does WB_SYNC_NONE - * writeback, for integrity writeback see bdi_sync_writeback(). + * Start writeback of `nr_pages' pages. If `nr_pages' is zero, write back + * the whole world. */ -static void bdi_writeback_all(struct super_block *sb, long nr_pages) +void wakeup_flusher_threads(long nr_pages) { + struct backing_dev_info *bdi; struct wb_writeback_args args = { - .sb = sb, - .nr_pages = nr_pages, .sync_mode = WB_SYNC_NONE, }; - struct backing_dev_info *bdi; - rcu_read_lock(); + if (nr_pages) { + args.nr_pages = nr_pages; + } else { + args.nr_pages = global_page_state(NR_FILE_DIRTY) + + global_page_state(NR_UNSTABLE_NFS); + } + rcu_read_lock(); list_for_each_entry_rcu(bdi, &bdi_list, bdi_list) { if (!bdi_has_dirty_io(bdi)) continue; - bdi_alloc_queue_work(bdi, &args); } - rcu_read_unlock(); } -/* - * Start writeback of `nr_pages' pages. If `nr_pages' is zero, write back - * the whole world. - */ -void wakeup_flusher_threads(long nr_pages) -{ - if (nr_pages == 0) - nr_pages = global_page_state(NR_FILE_DIRTY) + - global_page_state(NR_UNSTABLE_NFS); - bdi_writeback_all(NULL, nr_pages); -} - static noinline void block_dump___mark_inode_dirty(struct inode *inode) { if (inode->i_ino || strcmp(inode->i_sb->s_id, "bdev")) { @@ -1218,12 +1162,17 @@ void writeback_inodes_sb(struct super_block *sb) { unsigned long nr_dirty = global_page_state(NR_FILE_DIRTY); unsigned long nr_unstable = global_page_state(NR_UNSTABLE_NFS); - long nr_to_write; + struct wb_writeback_args args = { + .sb = sb, + .sync_mode = WB_SYNC_NONE, + }; + + WARN_ON(!rwsem_is_locked(&sb->s_umount)); - nr_to_write = nr_dirty + nr_unstable + + args.nr_pages = nr_dirty + nr_unstable + (inodes_stat.nr_inodes - inodes_stat.nr_unused); - bdi_start_writeback(sb->s_bdi, sb, nr_to_write); + bdi_queue_work_onstack(&args); } EXPORT_SYMBOL(writeback_inodes_sb); @@ -1237,7 +1186,9 @@ EXPORT_SYMBOL(writeback_inodes_sb); int writeback_inodes_sb_if_idle(struct super_block *sb) { if (!writeback_in_progress(sb->s_bdi)) { + down_read(&sb->s_umount); writeback_inodes_sb(sb); + up_read(&sb->s_umount); return 1; } else return 0; @@ -1253,7 +1204,16 @@ EXPORT_SYMBOL(writeback_inodes_sb_if_idle); */ void sync_inodes_sb(struct super_block *sb) { - bdi_sync_writeback(sb->s_bdi, sb); + struct wb_writeback_args args = { + .sb = sb, + .sync_mode = WB_SYNC_ALL, + .nr_pages = LONG_MAX, + .range_cyclic = 0, + }; + + WARN_ON(!rwsem_is_locked(&sb->s_umount)); + + bdi_queue_work_onstack(&args); wait_sb_inodes(sb); } EXPORT_SYMBOL(sync_inodes_sb); |