[PATCH] xfs_repair: fix max block offset test

[Brian Foster]

On Thu, Dec 11, 2014 at 11:54:03AM -0600, Eric Sandeen wrote:
> Eryu pointed out that in fstest xfs/071, we find corruption
> reported at the end.  This test attempts to do IO at the
> maximum possible offsets, and repair yields:
> 
> inode 1027 - extent offset too large - start 70, count 1, offset 2251799813685247
> correcting nextents for inode 1027
> bad data fork in inode 1027
> would have cleared inode 1027
> 
> Repair is complaining that an extent *starts* at the maximum
> block, but AFAICT, starting there is just fine, as long as
> we also end there.  i.e. a one-block extent at the limit
> is just fine.
> 
> So change the xfs_repair test to allow this situation.
> 
> Reported-by: Eryu Guan <eguan at redhat.com>
> Signed-off-by: Eric Sandeen <sandeen at redhat.com>
> ---

Thought this looked familiar:

http://oss.sgi.com/archives/xfs/2014-09/msg00524.html

Either one is fine with me. If we use the fix below, I think we should
update the error message since it technically refers to the extent
offset and we slightly tweak the meaning of the failure.

Brian

> 
> diff --git a/repair/dinode.c b/repair/dinode.c
> index 38a6562..ca57a61 100644
> --- a/repair/dinode.c
> +++ b/repair/dinode.c
> @@ -667,7 +667,9 @@ _("inode %" PRIu64 " - bad extent overflows - start %" PRIu64 ", "
>  					irec.br_startoff);
>  				goto done;
>  		}
> -		if (irec.br_startoff >= fs_max_file_offset)  {
> +		/* Ensure this extent does not extend beyond the max offset */
> +		if (irec.br_startoff + irec.br_blockcount - 1 >
> +							fs_max_file_offset) {
>  			do_warn(
>  _("inode %" PRIu64 " - extent offset too large - start %" PRIu64 ", "
>    "count %" PRIu64 ", offset %" PRIu64 "\n"),
> 
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