mbcache: automatically delete entries from cache on freeing

stable inclusion
from stable-v4.19.270
commit 61dc6cdfc85000e305a58553d41036716b427a0d
category: bugfix
bugzilla: https://gitee.com/openeuler/kernel/issues/I6DPF8


CVE: NA

--------------------------------

[ Upstream commit 307af6c8 ]

Use the fact that entries with elevated refcount are not removed from
the hash and just move removal of the entry from the hash to the entry
freeing time. When doing this we also change the generic code to hold
one reference to the cache entry, not two of them, which makes code
somewhat more obvious.

Signed-off-by: Jan Kara <jack@suse.cz>
Link: https://lore.kernel.org/r/20220712105436.32204-10-jack@suse.cz


Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Stable-dep-of: a44e84a9 ("ext4: fix deadlock due to mbcache entry corruption")
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Yongqiang Liu <liuyongqiang13@huawei.com>