Ocfs2 devel - Mar 2018 - [PATCH 2/6] ocfs2: Fix quota recovery failure on unmount

When filesystem is unmounted while there is still some recovery work
going on, it can happen that quotas get disabled before quota recovery
is complete resulting in failed quota recovery and inconsistent quota
accounting. Move disabling of recovery in ocfs2_dismount_volume() before
disabling of quotas to fix this race.

Signed-off-by: Jan Kara <jack at suse.cz>
---
 fs/ocfs2/super.c | 10 +++++++---
 1 file changed, 7 insertions(+), 3 deletions(-)

diff --git a/fs/ocfs2/super.c b/fs/ocfs2/super.c
index ffa4952d432b..14c3d5ee6e24 100644
--- a/fs/ocfs2/super.c
+++ b/fs/ocfs2/super.c
@@ -1904,6 +1904,13 @@ static void ocfs2_dismount_volume(struct super_block *sb,
int mnt_err)
 	/* Orphan scan should be stopped as early as possible */
 	ocfs2_orphan_scan_stop(osb);
 
+	/*
+	 * This will disable recovery and flush any recovery work. This needs
+	 * to happen before disabling quotas as quota recovery needs quotas
+	 * enabled.
+	 */
+	ocfs2_recovery_exit(osb);
+
 	ocfs2_disable_quotas(osb);
 
 	/* All dquots should be freed by now */
@@ -1915,9 +1922,6 @@ static void ocfs2_dismount_volume(struct super_block *sb,
int mnt_err)
 
 	ocfs2_truncate_log_shutdown(osb);
 
-	/* This will disable recovery and flush any recovery work. */
-	ocfs2_recovery_exit(osb);
-
 	ocfs2_journal_shutdown(osb);
 
 	ocfs2_sync_blockdev(sb);
-- 
2.13.6

Hi Jan,
    This patch will cause kernel crashes while umounting ocfs2.
    After parsing the core file, I find the root reason is as follows:
    osb->recovery_map is freed when recovery thread exited, but following
functions still access it by calling ocfs2_inode_lock.
    So, we should disable quotas between ocfs2_truncate_log_shutdown and
ocfs2_recovery_exit.
    Am I right?

Thanks
Changkuo
>>>
> When filesystem is unmounted while there is still some recovery work going
> on, it can happen that quotas get disabled before quota recovery is
complete
> resulting in failed quota recovery and inconsistent quota accounting. Move
> disabling of recovery in ocfs2_dismount_volume() before disabling of quotas
> to fix this race.
>
> Signed-off-by: Jan Kara <jack at suse.cz>
> ---
>  fs/ocfs2/super.c | 10 +++++++---
>  1 file changed, 7 insertions(+), 3 deletions(-)
>
> diff --git a/fs/ocfs2/super.c b/fs/ocfs2/super.c index
> ffa4952d432b..14c3d5ee6e24 100644
> --- a/fs/ocfs2/super.c
> +++ b/fs/ocfs2/super.c
> @@ -1904,6 +1904,13 @@ static void ocfs2_dismount_volume(struct
> super_block *sb, int mnt_err)
>       /* Orphan scan should be stopped as early as possible */
>       ocfs2_orphan_scan_stop(osb);
>
> +     /*
> +      * This will disable recovery and flush any recovery work. This needs
> +      * to happen before disabling quotas as quota recovery needs quotas
> +      * enabled.
> +      */
> +     ocfs2_recovery_exit(osb);
> +
>       ocfs2_disable_quotas(osb);
>
>       /* All dquots should be freed by now */ @@ -1915,9 +1922,6 @@
> static void ocfs2_dismount_volume(struct super_block *sb, int mnt_err)
>
>       ocfs2_truncate_log_shutdown(osb);
>
> -     /* This will disable recovery and flush any recovery work. */
> -     ocfs2_recovery_exit(osb);
> -
>       ocfs2_journal_shutdown(osb);
>
>       ocfs2_sync_blockdev(sb);
> --
> 2.13.6
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