Re: [PATCH] xfs: properly handle free inodes in extent hint validators

["Darrick J. Wong" <darrick.wong@oracle.com>]

On Tue, Jul 24, 2018 at 11:00:39AM -0700, Eric Sandeen wrote:
> When inodes are freed in xfs_ifree(), di_flags is cleared (so extent size
> hints are removed) but the actual extent size fields are left intact.
> This causes the extent hint validators to fail on freed inodes which once
> had extent size hints. 
> 
> This can be observed (for example) by running xfs/229 twice on a
> non-crc xfs filesystem, or presumably on V5 with ikeep.

I couldn't get it to reproduce by running x/229 twice, but I did see
x/242 blow up on the same problem overnight.  Which is funny since it
hadn't blown up until now.

> Fixes: 7d71a67 ("xfs: verify extent size hint is valid in inode verifier")
> Fixes: 02a0fda ("xfs: verify COW extent size hint is valid in inode verifier")
> Signed-off-by: Eric Sandeen <sandeen@redhat.com>

Separate patch, but can you also modify xfs_ifree to zero the
extsize/cowextsize fields so that 4.16-4.17 kernels without this patch
are less likely to trip over this?

Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>

--D

> ---
> 
> diff --git a/fs/xfs/libxfs/xfs_inode_buf.c b/fs/xfs/libxfs/xfs_inode_buf.c
> index 33dc34655ac3..30d1d60f1d46 100644
> --- a/fs/xfs/libxfs/xfs_inode_buf.c
> +++ b/fs/xfs/libxfs/xfs_inode_buf.c
> @@ -731,7 +731,8 @@ xfs_inode_validate_extsize(
>  	if ((hint_flag || inherit_flag) && extsize == 0)
>  		return __this_address;
>  
> -	if (!(hint_flag || inherit_flag) && extsize != 0)
> +	/* free inodes get flags set to zero but extsize remains */
> +	if (mode && !(hint_flag || inherit_flag) && extsize != 0)
>  		return __this_address;
>  
>  	if (extsize_bytes % blocksize_bytes)
> @@ -777,7 +778,8 @@ xfs_inode_validate_cowextsize(
>  	if (hint_flag && cowextsize == 0)
>  		return __this_address;
>  
> -	if (!hint_flag && cowextsize != 0)
> +	/* free inodes get flags set to zero but cowextsize remains */
> +	if (mode && !hint_flag && cowextsize != 0)
>  		return __this_address;
>  
>  	if (hint_flag && rt_flag)
> 
> 
> --
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