Hi,

xfstest/generic/650 trigger btrfs deadlock.

Linux kernel: 5.15.0-rc4
	https://kojipkgs.fedoraproject.org/packages/kernel/5.15.0/0.rc4.33.eln112/

Reproduce frequency: about 50%

This is the first time that we tested xfstest/generic/650, and it is the
first time that we tested kernel 5.15.x too. so it maybe a known problem
of btrfs.

When the deadlock happen, /mnt/test is fully used.
/dev/sdb1               btrfs   14G   14G     0 100% /mnt/test

When /mnt/test is NOT fully used (although nearly full ),
this deadlock seems to NOT happen.

#df -h
Filesystem      Size  Used Avail Use% Mounted on
/dev/sdb1               btrfs   14G   14G   72K 100% /mnt/test

Best Regards
Wang Yugui (wangyugui@e16-tech.com)
2021/10/07