Re: [PATCH v2 2/3] xfs: evict all inodes involved with log redo item recovery

[Dave Chinner <david@fromorbit.com>]

On Fri, Aug 11, 2017 at 12:50:10PM -0700, Darrick J. Wong wrote:
> When we introduced the bmap redo log items, we set MS_ACTIVE on the
> mountpoint and XFS_IRECOVERY on the inode to prevent unlinked inodes
> from being truncated prematurely during log recovery.  This also had the
> effect of putting linked inodes on the lru instead of evicting them.
> 
> Unfortunately, we neglected to find all those unreferenced lru inodes
> and evict them after finishing log recovery, which means that we leak
> them if anything goes wrong in the rest of xfs_mountfs, because the lru
> is only cleaned out on unmount.
> 
> Therefore, evict unreferenced inodes in the lru list immediately
> after clearing MS_ACTIVE.
> 
> Fixes: 17c12bcd30 ("xfs: when replaying bmap operations, don't let unlinked inodes get reaped")
> Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
> Cc: viro@ZenIV.linux.org.uk
> ---
> v2: use the vfs evict_inodes instead of duplicating it
> ---
>  fs/inode.c         |    1 +
>  fs/internal.h      |    1 -
>  fs/xfs/xfs_mount.c |   12 ++++++++++++
>  include/linux/fs.h |    1 +
>  4 files changed, 14 insertions(+), 1 deletion(-)
> 
> diff --git a/fs/inode.c b/fs/inode.c
> index 5037059..6a1626e 100644
> --- a/fs/inode.c
> +++ b/fs/inode.c
> @@ -637,6 +637,7 @@ void evict_inodes(struct super_block *sb)
>  
>  	dispose_list(&dispose);
>  }
> +EXPORT_SYMBOL_GPL(evict_inodes);
>  
>  /**
>   * invalidate_inodes	- attempt to free all inodes on a superblock
> diff --git a/fs/internal.h b/fs/internal.h
> index 9676fe1..fedfe94 100644
> --- a/fs/internal.h
> +++ b/fs/internal.h
> @@ -132,7 +132,6 @@ static inline bool atime_needs_update_rcu(const struct path *path,
>  extern void inode_io_list_del(struct inode *inode);
>  
>  extern long get_nr_dirty_inodes(void);
> -extern void evict_inodes(struct super_block *);
>  extern int invalidate_inodes(struct super_block *, bool);
>  
>  /*
> diff --git a/fs/xfs/xfs_mount.c b/fs/xfs/xfs_mount.c
> index a46c9d7..351e2c3 100644
> --- a/fs/xfs/xfs_mount.c
> +++ b/fs/xfs/xfs_mount.c
> @@ -956,10 +956,22 @@ xfs_mountfs(
>  	 * inodes.  Turn it off immediately after xfs_log_mount_finish
>  	 * so that we don't leak the quota inodes if subsequent mount
>  	 * activities fail.
> +	 *
> +	 * We let all inodes involved in redo item processing end up on
> +	 * the LRU instead of being evicted immediately so that if we do
> +	 * something to an unlinked inode, the irele won't cause
> +	 * premature truncation and freeing of the inode, which results
> +	 * in log recovery failure.  We have to evict the unreferenced
> +	 * lru inodes after clearing MS_ACTIVE because we don't
> +	 * otherwise clean up the lru if there's a subsequent failure in
> +	 * xfs_mountfs, which leads to us leaking the inodes if nothing
> +	 * else (e.g. quotacheck) references the inodes before the
> +	 * mount failure occurs.
>  	 */
>  	mp->m_super->s_flags |= MS_ACTIVE;
>  	error = xfs_log_mount_finish(mp);
>  	mp->m_super->s_flags &= ~MS_ACTIVE;
> +	evict_inodes(mp->m_super);

Shouldn't all this MS_ACTIVE flag and inode eviction stuff be put
inside xfs_log_mount_finish()? Seems to me like wrapping it aroudn
the outside is the wrong place to be putting it...

Cheers,

Dave.
-- 
Dave Chinner
david@fromorbit.com