Flaky test: generic/085

["Theodore Ts'o" <tytso@mit.edu>]

Hi, I've recently found a flaky test, generic/085 on 6.10-rc2 and
fs-next.  It's failing on both ext4 and xfs, and it reproduces more
easiy with the dax config:

xfs/4k: 20 tests, 1 failures, 137 seconds
  Flaky: generic/085:  5% (1/20)
xfs/dax: 20 tests, 11 failures, 71 seconds
  Flaky: generic/085: 55% (11/20)
ext4/4k: 20 tests, 111 seconds
ext4/dax: 20 tests, 8 failures, 69 seconds
  Flaky: generic/085: 40% (8/20)
Totals: 80 tests, 0 skipped, 20 failures, 0 errors, 388s

The failure is caused by a WARN_ON in fs_bdev_thaw() in fs/super.c:

static int fs_bdev_thaw(struct block_device *bdev)
{
	...
	sb = get_bdev_super(bdev);
	if (WARN_ON_ONCE(!sb))
		return -EINVAL;


The generic/085 test which exercises races between the fs
freeze/unfeeze and mount/umount code paths, so this appears to be
either a VFS-level or block device layer bug.  Modulo the warning, it
looks relatively harmless, so I'll just exclude generic/085 from my
test appliance, at least for now.  Hopefully someone will have a
chance to take a look at it?

Thanks,

					- Ted