Re: [PATCH] btrfs: fix _require_btrfs_send_version to detect btrfs-progs support

[Qu Wenruo <quwenruo.btrfs@gmx.com>]

在 2024/7/12 09:35, fdmanana@kernel.org 写道:
> From: Filipe Manana <fdmanana@suse.com>
>
> Commit 199d0a992536df3702a0c4843d2a449d54f399c2 ("common/btrfs: introduce
> _require_btrfs_send_version") turned _require_btrfs_send_v2 into a generic
> helper to detect support for any send stream version, however it's only
> working for detecting kernel support, it misses detecting the support from
> btrfs-progs - it always checks only that it supports v2 (the send command
> supports the --compressed-data option).
>
> Fix that by verifying that btrfs-progs supports the requested version.
>
> Signed-off-by: Filipe Manana <fdmanana@suse.com>
> ---
>   common/btrfs | 21 +++++++++++++++++----
>   1 file changed, 17 insertions(+), 4 deletions(-)
>
> diff --git a/common/btrfs b/common/btrfs
> index be5948db..953dc2a0 100644
> --- a/common/btrfs
> +++ b/common/btrfs
> @@ -777,17 +777,30 @@ _require_btrfs_corrupt_block()
>   _require_btrfs_send_version()
>   {
>   	local version=$1
> +	local ret
>
> -	# Check first if btrfs-progs supports the v2 stream.
> -	_require_btrfs_command send --compressed-data
> -
> -	# Now check the kernel support. If send_stream_version does not exists,
> +	# Check the kernel support. If send_stream_version does not exists,
>   	# then it's a kernel that only supports v1.
>   	[ -f /sys/fs/btrfs/features/send_stream_version ] || \
>   		_notrun "kernel does not support send stream $version"
>
>   	[ $(cat /sys/fs/btrfs/features/send_stream_version) -ge $version ] || \
>   		_notrun "kernel does not support send stream $version"
> +
> +	# Now check that btrfs-progs supports the requested stream version.
> +	_scratch_mkfs &> /dev/null || \
> +		_fail "mkfs failed at _require_btrfs_send_version"
> +	_scratch_mount
> +	$BTRFS_UTIL_PROG subvolume snapshot -r $SCRATCH_MNT \
> +			 $SCRATCH_MNT/snap &> /dev/null
> +	$BTRFS_UTIL_PROG send --proto $version -f /dev/null \
> +			 $SCRATCH_MNT/snap 2> /dev/null

IHMO we can just skip the -f option and redirect both stderr and stdout
into /dev/null.

Otherwise looks good to me.

Reviewed-by: Qu Wenruo <wqu@suse.com>

Thanks,
Qu

> +	ret=$?
> +	_scratch_unmount
> +
> +	if [ $ret -ne 0 ]; then
> +		_notrun "btrfs-progs does not support send stream version $version"
> +	fi
>   }
>
>   # Get the bytenr associated to a file extent item at a given file offset.