Re: [PATCH] fstests: generic/730: exclude btrfs for now

[Christoph Hellwig <hch@infradead.org>]

On Wed, Jun 04, 2025 at 06:47:41PM +0930, Qu Wenruo wrote:
> Right, the ext4/xfs can go a superblock shutdown because they are single
> device fs (except the external journal device),

XFS also has a RT device in addition to that.

> and fs_holder_ops handles
> the single device failure by calling back into the super block shutdown call
> back.
> 
> For a multi-device fs, it should go through the blk_holder_ops, which btrfs
> doesn't provide when opening the devices.

Yes, btrfs would need it's own fs_ops.  Alternatively we could add a new
->devloss super_operations method and change fs_bdev_mark_dead to
something like:

	if (sb->s_op->devloss && sb->s_op->devloss(sb, bdev, surprise))
		goto done;

	<sync fs and stuff)
	if (sb->s_op->shutdown)
		sb->s_op->shutdown(sb);
done:
	super_unlock_shared(sb);

so that btrfs or other multi-device file systems don't have to duplicate
the logic.

> I guess it means, if a fs supports per-bdev shutdown, it won't hurt to also
> provide a full-fs shutdown ioctl?

Supporting it is a good idea in general as it enables a lot of good test
coverage in xfstests.