Re: [PATCH 1/3] xfs: clear MS_ACTIVE after finishing log recovery to avoid inode leak

[Brian Foster <bfoster@redhat.com>]

On Tue, Aug 08, 2017 at 06:04:44PM -0700, Darrick J. Wong wrote:
> Way back when we established inode block-map redo log items, it was
> discovered that we needed to prevent the VFS from evicting inodes during
> log recovery because any given inode might be have bmap redo items to
> replay even if the inode has no link count and is ultimately deleted,
> and any eviction of an unlinked inode causes the inode to be truncated
> and freed too early.
> 
> To make this possible, we set MS_ACTIVE so that inodes would not be torn
> down immediately upon release.  Unfortunately, this also results in the
> quota inodes not being released at all if a later part of the mount
> process should fail, because we never reclaim the inodes.  So, clear
> MS_ACTIVE immediately after we finish the log recovery so that the quota
> inodes will be torn down properly if we abort the mount.
> 
> Fixes: 17c12bcd30 ("xfs: when replaying bmap operations, don't let unlinked inodes get reaped")
> Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
> ---
>  fs/xfs/xfs_mount.c |    6 ++++--
>  1 file changed, 4 insertions(+), 2 deletions(-)
> 
> diff --git a/fs/xfs/xfs_mount.c b/fs/xfs/xfs_mount.c
> index 40d4e8b..d463ab3 100644
> --- a/fs/xfs/xfs_mount.c
> +++ b/fs/xfs/xfs_mount.c
> @@ -949,7 +949,9 @@ xfs_mountfs(
>  	 * iput to behave like they do for an active filesystem.
>  	 * xfs_fs_drop_inode needs to be able to prevent the deletion
>  	 * of inodes before we're done replaying log items on those
> -	 * inodes.
> +	 * inodes.  Turn it off immediately after xfs_log_mount_finish
> +	 * so that we don't leak the quota inodes if subsequent mount
> +	 * activities fail.
>  	 */
>  	mp->m_super->s_flags |= MS_ACTIVE;
>  
> @@ -959,6 +961,7 @@ xfs_mountfs(
>  	 * read in.
>  	 */
>  	error = xfs_log_mount_finish(mp);
> +	mp->m_super->s_flags &= ~MS_ACTIVE;

Just an aesthetic nit, but could we combine these two above hunks and
the associated comments so the intent is very obvious? E.g., so it looks
something like this:

	/*
	 * Set MS_ACTIVE around log recovery ...
	 */
	mp->m_super->s_flags |= MS_ACTIVE;
	error = xfs_log_mount_finish(mp);
	mp->m_super->s_flags &= ~MS_ACTIVE;
	...

Otherwise this looks fine:

Reviewed-by: Brian Foster <bfoster@redhat.com>

>  	if (error) {
>  		xfs_warn(mp, "log mount finish failed");
>  		goto out_rtunmount;
> @@ -1028,7 +1031,6 @@ xfs_mountfs(
>   out_quota:
>  	xfs_qm_unmount_quotas(mp);
>   out_rtunmount:
> -	mp->m_super->s_flags &= ~MS_ACTIVE;
>  	xfs_rtunmount_inodes(mp);
>   out_rele_rip:
>  	IRELE(rip);
> --
> To unsubscribe from this list: send the line "unsubscribe linux-xfs" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at  http://vger.kernel.org/majordomo-info.html