From 3259f8bed2f0f57c2fdcdac1b510c3fa319ef97e Mon Sep 17 00:00:00 2001 From: Chris Mason Date: Fri, 29 Oct 2010 11:16:17 -0400 Subject: Add new functions for triggering inode writeback When btrfs is running low on metadata space, it needs to force delayed allocation pages to disk. It currently does this with a suboptimal walk of a private list of inodes with delayed allocation, and it would be much better if we used the generic flusher threads. writeback_inodes_sb_if_idle would be ideal, but it waits for the flusher thread to start IO on all the dirty pages in the FS before it returns. This adds variants of writeback_inodes_sb* that allow the caller to control how many pages get sent down. Signed-off-by: Chris Mason --- fs/fs-writeback.c | 52 ++++++++++++++++++++++++++++++++++++++++++---------- 1 file changed, 42 insertions(+), 10 deletions(-) (limited to 'fs/fs-writeback.c') diff --git a/fs/fs-writeback.c b/fs/fs-writeback.c index ab38fef1c9a1..1e23c33ea5cf 100644 --- a/fs/fs-writeback.c +++ b/fs/fs-writeback.c @@ -1069,33 +1069,44 @@ static void wait_sb_inodes(struct super_block *sb) } /** - * writeback_inodes_sb - writeback dirty inodes from given super_block + * writeback_inodes_sb_nr - writeback dirty inodes from given super_block * @sb: the superblock + * @nr: the number of pages to write * * 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. The number of pages submitted is - * returned. + * for IO completion of submitted IO. */ -void writeback_inodes_sb(struct super_block *sb) +void writeback_inodes_sb_nr(struct super_block *sb, unsigned long nr) { - unsigned long nr_dirty = global_page_state(NR_FILE_DIRTY); - unsigned long nr_unstable = global_page_state(NR_UNSTABLE_NFS); DECLARE_COMPLETION_ONSTACK(done); struct wb_writeback_work work = { .sb = sb, .sync_mode = WB_SYNC_NONE, .done = &done, + .nr_pages = nr, }; WARN_ON(!rwsem_is_locked(&sb->s_umount)); - - work.nr_pages = nr_dirty + nr_unstable + - (inodes_stat.nr_inodes - inodes_stat.nr_unused); - bdi_queue_work(sb->s_bdi, &work); wait_for_completion(&done); } +EXPORT_SYMBOL(writeback_inodes_sb_nr); + +/** + * writeback_inodes_sb - writeback dirty inodes from given super_block + * @sb: the superblock + * + * 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) +{ + return writeback_inodes_sb_nr(sb, global_page_state(NR_FILE_DIRTY) + + global_page_state(NR_UNSTABLE_NFS) + + (inodes_stat.nr_inodes - inodes_stat.nr_unused)); +} EXPORT_SYMBOL(writeback_inodes_sb); /** @@ -1117,6 +1128,27 @@ int writeback_inodes_sb_if_idle(struct super_block *sb) } EXPORT_SYMBOL(writeback_inodes_sb_if_idle); +/** + * writeback_inodes_sb_if_idle - start writeback if none underway + * @sb: the superblock + * @nr: the number of pages to write + * + * Invoke writeback_inodes_sb if no writeback is currently underway. + * Returns 1 if writeback was started, 0 if not. + */ +int writeback_inodes_sb_nr_if_idle(struct super_block *sb, + unsigned long nr) +{ + 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; +} +EXPORT_SYMBOL(writeback_inodes_sb_nr_if_idle); + /** * sync_inodes_sb - sync sb inode pages * @sb: the superblock -- cgit v1.2.2