Re: [PATCH 1/9] btrfs: add a helpers for read repair testing

[Nikolay Borisov <nborisov@suse.com>]

On 24.05.22 г. 10:18 ч., Christoph Hellwig wrote:
> Add a few helpers to consolidate code for btrfs read repair testing:
> 
>   - _btrfs_get_first_logical() gets the btrfs logical address for the
>     first extent in a file
>   - _btrfs_get_device_path and _btrfs_get_physical use the
>     btrfs-map-logical tool to find the device path and physical address
>     for btrfs logical address for a specific mirror
>   - _btrfs_direct_read_on_mirror and _btrfs_buffered_read_on_mirror
>     read the data from a specific mirror
> 
> These will be used to consolidate the read repair tests and avoid
> duplication for new tests.
> 
> Signed-off-by: Christoph Hellwig <hch@lst.de>
> ---
>   common/btrfs  | 75 +++++++++++++++++++++++++++++++++++++++++++++++++++
>   common/config |  1 +
>   2 files changed, 76 insertions(+)
> 
> diff --git a/common/btrfs b/common/btrfs
> index ac597ca4..129a83f7 100644
> --- a/common/btrfs
> +++ b/common/btrfs
> @@ -505,3 +505,78 @@ _btrfs_metadump()
>   	$BTRFS_IMAGE_PROG "$device" "$dumpfile"
>   	[ -n "$DUMP_COMPRESSOR" ] && $DUMP_COMPRESSOR -f "$dumpfile" &> /dev/null
>   }
> +
> +# Return the btrfs logical address for the first block in a file
> +_btrfs_get_first_logical()
> +{
> +	local file=$1
> +	_require_command "$FILEFRAG_PROG" filefrag
> +
> +	${FILEFRAG_PROG} -v $SCRATCH_MNT/foobar >> $seqres.full

Likely you want to print the logical layout of the file for reference 
purposes? Then use $file instead of $SCRATCH_MNT/foobar

<snip>