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Re: [PATCH 3/5] xfs_repair: fix dir refcount when '.' missing and dir is

To: Eric Sandeen <sandeen@xxxxxxxxxx>
Subject: Re: [PATCH 3/5] xfs_repair: fix dir refcount when '.' missing and dir is rebuilt
From: Brian Foster <bfoster@xxxxxxxxxx>
Date: Mon, 8 Sep 2014 09:45:25 -0400
Cc: xfs@xxxxxxxxxxx
Delivered-to: xfs@xxxxxxxxxxx
In-reply-to: <1410108065-18156-4-git-send-email-sandeen@xxxxxxxxxx>
References: <1410108065-18156-1-git-send-email-sandeen@xxxxxxxxxx> <1410108065-18156-4-git-send-email-sandeen@xxxxxxxxxx>
User-agent: Mutt/1.5.23 (2014-03-12)
On Sun, Sep 07, 2014 at 11:41:03AM -0500, Eric Sandeen wrote:
> In phase 6's longform_dir2_entry_check, if we never
> find a '.' entry we never add a reference to that entry;
> if we subsequently rebuild it, '.' gets added, but
> no ref to it is ever made.  This leads to Phase 7 doing
> i.e.:
> 
>   Phase 7 - verify and correct link counts...
>   resetting inode 5184 nlinks from 2 to 1
> 
> and the next run will do:
> 
>   Phase 7 - verify and correct link counts...
>   resetting inode 5184 nlinks from 1 to 2
> 
> So if '.' was never found, but the directory got
> rebuilt, manually add the ref for it.
> 
> Signed-off-by: Eric Sandeen <sandeen@xxxxxxxxxx>
> ---
>  repair/phase6.c |    6 ++++++
>  1 files changed, 6 insertions(+), 0 deletions(-)
> 
> diff --git a/repair/phase6.c b/repair/phase6.c
> index f13069f..cc36a9c 100644
> --- a/repair/phase6.c
> +++ b/repair/phase6.c
> @@ -2288,6 +2288,12 @@ out_fix:
>                       if (bplist[i])
>                               libxfs_putbuf(bplist[i]);
>               longform_dir2_rebuild(mp, ino, ip, irec, ino_offset, hashtab);
> +             /*
> +              * If we didn't find a dot, we never added a ref for it;
> +              * it's there now after the rebuild, so mark it as reached.
> +              */
> +             if (*need_dot)
> +                     add_inode_ref(irec, ino_offset);

So if I follow this correctly, we iterate through the dir, add each name
to the hashtable and handle the inode reference count in the first
longform_dir2_entry_check() loop. If something is wrong, we call
longform_dir2_rebuild() to rebuild the dir from the hashtable of
names/inodes. We may or may not have added a reference for dot at that
point, and need_dot is set appropriately.

This seems Ok, but where is the dot entry actually added? Hmm, I see
that we handle dot in the longform_dir2_rebuild() loop by just skipping
over it...

Brian


>               *num_illegal = 0;
>               *need_dot = 0;
>       } else {
> -- 
> 1.7.1
> 
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