On Fri 20-04-18 16:59:04, Luis R. Rodriguez wrote:
> freeze_bdev() will bail but leave the bd_fsfreeze_count incremented
> if the get_active_super() does not find the superblock on our
> super_blocks list to match.
>
> This issue has been present since v2.6.29 during the introduction of the
> ioctl_fsfreeze() and ioctl_fsthaw() via commit fcccf502540e3 ("filesystem
> freeze: implement generic freeze feature").
>
> I am not aware of any existing races which have triggered this
> situation, however, if it does trigger it could mean leaving a
> superblock with bd_fsfreeze_count always positive.
>
> Fixes: fcccf502540e3 ("filesystem freeze: implement generic freeze feature")
> Signed-off-by: Luis R. Rodriguez <mcgrof@xxxxxxxxxx>
Looks good to me. You can add:
Reviewed-by: Jan Kara <jack@xxxxxxx>
Honza
> ---
> fs/block_dev.c | 4 +++-
> 1 file changed, 3 insertions(+), 1 deletion(-)
>
> diff --git a/fs/block_dev.c b/fs/block_dev.c
> index b54966679833..7a532aa58c07 100644
> --- a/fs/block_dev.c
> +++ b/fs/block_dev.c
> @@ -507,8 +507,10 @@ struct super_block *freeze_bdev(struct block_device *bdev)
> }
>
> sb = get_active_super(bdev);
> - if (!sb)
> + if (!sb) {
> + bdev->bd_fsfreeze_count--;
> goto out;
> + }
> if (sb->s_op->freeze_super)
> error = sb->s_op->freeze_super(sb);
> else
> --
> 2.16.3
>
--
Jan Kara <jack@xxxxxxxx>
SUSE Labs, CR
