From 17bd55d037a02b04d9119511cfd1a4b985d20f63 Mon Sep 17 00:00:00 2001 From: Eric Sandeen Date: Wed, 23 Dec 2009 07:57:07 -0500 Subject: fs-writeback: Add helper function to start writeback if idle ext4, at least, would like to start pushing on writeback if it starts to get close to ENOSPC when reserving worst-case blocks for delalloc writes. Writing out delalloc data will convert those worst-case predictions into usually smaller actual usage, freeing up space before we hit ENOSPC based on this speculation. Thanks to Jens for the suggestion for the helper function, & the naming help. I've made the helper return status on whether writeback was started even though I don't plan to use it in the ext4 patch; it seems like it would be potentially useful to test this in some cases. Signed-off-by: Eric Sandeen Acked-by: Jan Kara --- fs/fs-writeback.c | 17 +++++++++++++++++ 1 file changed, 17 insertions(+) (limited to 'fs') diff --git a/fs/fs-writeback.c b/fs/fs-writeback.c index 49bc1b8e8f1..f6c2155e002 100644 --- a/fs/fs-writeback.c +++ b/fs/fs-writeback.c @@ -1186,6 +1186,23 @@ void writeback_inodes_sb(struct super_block *sb) } EXPORT_SYMBOL(writeback_inodes_sb); +/** + * writeback_inodes_sb_if_idle - start writeback if none underway + * @sb: the superblock + * + * Invoke writeback_inodes_sb 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) +{ + if (!writeback_in_progress(sb->s_bdi)) { + writeback_inodes_sb(sb); + return 1; + } else + return 0; +} +EXPORT_SYMBOL(writeback_inodes_sb_if_idle); + /** * sync_inodes_sb - sync sb inode pages * @sb: the superblock -- cgit v1.2.3