Re: [PATCH] shared/298: run xfs_db against the loop device instead of the image file

["Darrick J. Wong" <djwong@kernel.org>]

On Fri, Mar 01, 2024 at 08:28:20AM -0700, Christoph Hellwig wrote:
> xfs_db fails to properly detect the device sector size and thus segfaults
> when run again an image file with 4k sector size.  While that's something
> we should fix in xfs_db it will require a fair amount of refactoring of
> the libxfs init code.  For now just change shared/298 to run xfs_db
> against the loop device created on the image file that is used for I/O,
> which feels like the right thing to do anyway to avoid cache coherency
> issues.
> 
> Signed-off-by: Christoph Hellwig <hch@lst.de>
> ---
>  tests/shared/298 | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/tests/shared/298 b/tests/shared/298
> index 071c03dee..f657578c7 100755
> --- a/tests/shared/298
> +++ b/tests/shared/298
> @@ -69,7 +69,7 @@ get_free_sectors()
>  	agsize=`$XFS_INFO_PROG $loop_mnt | $SED_PROG -n 's/.*agsize=\(.*\) blks.*/\1/p'`
>  	# Convert free space (agno, block, length) to (start sector, end sector)
>  	_umount $loop_mnt
> -	$XFS_DB_PROG -r -c "freesp -d" $img_file | $SED_PROG '/^.*from/,$d'| \
> +	$XFS_DB_PROG -r -c "freesp -d" $loop_dev | $SED_PROG '/^.*from/,$d'| \

Might want to leave a comment here about why xfs uses $loop_dev unlike
the other clauses that use $img_file

# Use $loop_dev to work around sector size misdetection bugs in xfs_db
$XFS_DB_PROG...

With that changed,
Reviewed-by: Darrick J. Wong <djwong@kernel.org>

--D

>  		 $AWK_PROG -v spb=$sectors_per_block -v agsize=$agsize \
>  		'{ print spb * ($1 * agsize + $2), spb * ($1 * agsize + $2 + $3) - 1 }'
>  	;;
> -- 
> 2.39.2
> 
>