Re: [PATCH] ovl: skip overlayfs superblocks at global sync

[Miklos Szeredi]

On Thu, Apr 9, 2020 at 10:29 AM Konstantin Khlebnikov
<khlebnikov@xxxxxxxxxxxxxx> wrote:
>
> Stacked filesystems like overlayfs has no own writeback, but they have to
> forward syncfs() requests to backend for keeping data integrity.
>
> During global sync() each overlayfs instance calls method ->sync_fs()
> for backend although it itself is in global list of superblocks too.
> As a result one syscall sync() could write one superblock several times
> and send multiple disk barriers.
>
> This patch adds flag SB_I_SKIP_SYNC into sb->sb_iflags to avoid that.
>
> Reported-by: Dmitry Monakhov <dmtrmonakhov@xxxxxxxxxxxxxx>
> Signed-off-by: Konstantin Khlebnikov <khlebnikov@xxxxxxxxxxxxxx>

Thanks, applied.

Miklos