Re: [PATCH] common: add proper btrfs log tree detection to _has_metadata_journaling

[Qu Wenruo <wqu@suse.com>]

在 2025/6/30 10:32, Qu Wenruo 写道:
> [BUG]
> With the incoming btrfs shutdown ioctl/remove_bdev callback support,
> btrfs can be tested with the shutdown group.

Forgot to mention, if someone is going to test btrfs with shutdown 
support, here is the branch:

https://github.com/adam900710/linux.git shutdown

Thanks,
Qu

> 
> But test case generic/050 still fails on btrfs with shutdown support:
> 
> generic/050 1s ... - output mismatch (see /home/adam/xfstests/results//generic/050.out.bad)
>      --- tests/generic/050.out	2022-05-11 11:25:30.763333331 +0930
>      +++ /home/adam/xfstests/results//generic/050.out.bad	2025-06-30 10:22:21.752068622 +0930
>      @@ -13,9 +13,7 @@
>       setting device read-only
>       mounting filesystem that needs recovery on a read-only device:
>       mount: device write-protected, mounting read-only
>      -mount: cannot mount device read-only
>       unmounting read-only filesystem
>      -umount: SCRATCH_DEV: not mounted
>       mounting filesystem with -o norecovery on a read-only device:
>      ...
>      (Run 'diff -u /home/adam/xfstests/tests/generic/050.out /home/adam/xfstests/results//generic/050.out.bad'  to see the entire diff)
> Ran: generic/050
> 
> [CAUSE]
> The test case generic/050 has several different golden output depending
> on the fs features.
> 
> For fses which requires data write (e.g. replay the journal) during
> mount, mounting a read-only block device should fail.
> And that is the default golden output.
> 
> However there are cases that the fs doesn't need to write anything, e.g.
> the fs has no metadata journal support at all, or the fs has no dirty
> journal to replay.
> 
> In that case, there is the generic/050.nojournal golden output.
> 
> The test case is using the helper _has_metadata_journaling() to
> determine the feature.
> 
> Unfortunately that helper doesn't support btrfs, thus the default
> behavior is to assume the fs has journal to replay, thus for btrfs it
> always assume there is a journal to replay and results the wrong golden
> output to be used.
> 
> [FIX]
> Add btrfs specific log tree check into _has_metadata_journaling(), so
> that if there is no log tree to replay, expose the "nojournal" feature
> correctly to pass generic/050.
> 
> Signed-off-by: Qu Wenruo <wqu@suse.com>
> ---
>   common/rc | 8 ++++++++
>   1 file changed, 8 insertions(+)
> 
> diff --git a/common/rc b/common/rc
> index 2d8e7167..a78b779a 100644
> --- a/common/rc
> +++ b/common/rc
> @@ -4283,6 +4283,14 @@ _has_metadata_journaling()
>   			return 1
>   		fi
>   		;;
> +	btrfs)
> +		_require_btrfs_command inspect-internal dump-super
> +		if "$BTRFS_UTIL_PROG" inspect-internal dump-super $dev | \
> +		   grep -q "log_root\s\+0" ; then
> +			echo "$FSTYPE on $dev has empty log tree"
> +			return 1
> +		fi
> +		;;
>   	*)
>   		# by default we pass; if you need to, add your fs above!
>   		;;