| Date | Thu, 22 Apr 2010 12:10:30 -0700 | From | Greg KH <> | Subject | [179/197] fs-writeback: Add helper function to start writeback if idle |
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2.6.32-stable review patch. If anyone has any objections, please let us know.
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From: Eric Sandeen <sandeen@redhat.com>
commit 17bd55d037a02b04d9119511cfd1a4b985d20f63 upstream.
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 <sandeen@redhat.com> Acked-by: Jan Kara <jack@suse.cz> Cc: maximilian attems <max@stro.at> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
--- fs/fs-writeback.c | 17 +++++++++++++++++ include/linux/writeback.h | 1 + 2 files changed, 18 insertions(+)
--- a/fs/fs-writeback.c +++ b/fs/fs-writeback.c @@ -1213,6 +1213,23 @@ void writeback_inodes_sb(struct super_bl 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 * --- a/include/linux/writeback.h +++ b/include/linux/writeback.h @@ -69,6 +69,7 @@ struct writeback_control { struct bdi_writeback; int inode_wait(void *); void writeback_inodes_sb(struct super_block *); +int writeback_inodes_sb_if_idle(struct super_block *); void sync_inodes_sb(struct super_block *); void writeback_inodes_wbc(struct writeback_control *wbc); long wb_do_writeback(struct bdi_writeback *wb, int force_wait);
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