mirrors/linux
1
0
Fork 0
mirror of https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git synced 2026-05-03 18:12:25 -04:00
Code Issues Packages Projects Releases Wiki Activity

Btrfs: wake up @scrub_pause_wait as much as we can

Browse Source 
check if @scrubs_running=@scrubs_paused condition inside wait_event()
is not an atomic operation which means we may inc/dec @scrub_running/
paused at any time. Let's wake up @scrub_pause_wait as much as we can
to let commit transaction blocked less.

An example below:

Thread1				Thread2
|->scrub_blocked_if_needed()	|->scrub_pending_trans_workers_inc
  |->increase @scrub_paused
                                       |->increase @scrub_running
  |->wake up scrub_pause_wait list
                                       |->scrub blocked
                                       |->increase @scrub_paused

Thread3 is commiting transaction which is blocked at btrfs_scrub_pause().
So after Thread2 increase @scrub_paused, we meet the condition
@scrub_paused=@scrub_running, but transaction will be still blocked until
another calling to wake up @scrub_pause_wait.

Signed-off-by: Wang Shilong <wangsl.fnst@cn.fujitsu.com>
Signed-off-by: Miao Xie <miaox@cn.fujitsu.com>
Signed-off-by: Josef Bacik <jbacik@fb.com>
This commit is contained in:
Wang Shilong
2014-02-19 19:24:19 +08:00
committed by Josef Bacik
parent c0af8f0b1c
commit 32a447896c
1 changed files with 10 additions and 0 deletions
Download Patch File Download Diff File Expand all files Collapse all files

10
fs/btrfs/scrub.c
View File

@@ -315,6 +315,16 @@ static void scrub_pending_trans_workers_inc(struct scrub_ctx *sctx)
atomic_inc(&fs_info->scrubs_running);
atomic_inc(&fs_info->scrubs_paused);
mutex_unlock(&fs_info->scrub_lock);
/*
* check if @scrubs_running=@scrubs_paused condition
* inside wait_event() is not an atomic operation.
* which means we may inc/dec @scrub_running/paused
* at any time. Let's wake up @scrub_pause_wait as
* much as we can to let commit transaction blocked less.
*/
wake_up(&fs_info->scrub_pause_wait);
atomic_inc(&sctx->workers_pending);
}