Recent commits break loop device unmounting

[nokangaroo <nokangaroo@aon.at>]

	commit 08e136ebd193eae7d5eff4c66d576c4a2dabdc3f
	Author: Raphael Pinsonneault-Thibeault <rpthibeault@gmail.com>
	Date:   Wed Dec 17 14:00:40 2025 -0500

	loop: don't change loop device under exclusive opener in loop_set_status

	loop_set_status() is allowed to change the loop device while there
	are other openers of the device, even exclusive ones.

	In this case, it causes a KASAN: slab-out-of-bounds Read in
	ext4_search_dir(), since when looking for an entry in an inlined
	directory, e_value_offs is changed underneath the filesystem by
	loop_set_status().

	Fix the problem by forbidding loop_set_status() from modifying the loop
	device while there are exclusive openers of the device. This is similar
	to the fix in loop_configure() by commit 33ec3e53e7b1 ("loop: Don't
	change loop device under exclusive opener") alongside commit
	ecbe6bc0003b ("block: use bd_prepare_to_claim directly in the loop
	driver").

and the follow-up
	commit 2704024d83fa9eb8e5f16925aae340fd9d246694
	Author: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
	Date:   Wed Jan 7 19:41:43 2026 +0900

	loop: add missing bd_abort_claiming in loop_set_status

break unmounting a loop device by a normal user
(udisksctl unmount -b /dev/loop0).
The device seems to be unmounted, but the path still appears in the file
manager, and if the device is on an external harddisk I cannot unmount the
disk.

Bisecting: 0 revisions left to test after this (roughly 0 steps)
[08e136ebd193eae7d5eff4c66d576c4a2dabdc3f] loop: don't change loop device under
exclusive opener in loop_set_status

As a workaround I reverted this commit (and the follow-up before it).

  git revert -n 2704024d83fa9eb8e5f16925aae340fd9d246694
  git revert -n 08e136ebd193eae7d5eff4c66d576c4a2dabdc3f

If they solve an actual problem it needs to be fixed differently.
Commits 33ec3e53e7b1 and ecbe6bc0003b seem to be correct.

I will supply more information if needed