ext4: destroy ext4_fc_dentry_cachep kmemcache on module removal

stable inclusion
from stable-v5.10.94
commit d60e9daba29e44e0f277333e46fff90c74509398
bugzilla: https://gitee.com/openeuler/kernel/issues/I531X9

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=d60e9daba29e44e0f277333e46fff90c74509398

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

commit ab047d51 upstream.

The kmemcache for ext4_fc_dentry_cachep remains registered after module
removal.

Destroy ext4_fc_dentry_cachep kmemcache on module removal.

Fixes: aa75f4d3 ("ext4: main fast-commit commit path")
Signed-off-by: NSebastian Andrzej Siewior <bigeasy@linutronix.de>
Reviewed-by: NLukas Czerner <lczerner@redhat.com>
Reviewed-by: NHarshad Shirwadkar <harshadshirwadkar@gmail.com>
Link: https://lore.kernel.org/r/20211110134640.lyku5vklvdndw6uk@linutronix.de
Link: https://lore.kernel.org/r/YbiK3JetFFl08bd7@linutronix.de
Link: https://lore.kernel.org/r/20211223164436.2628390-1-bigeasy@linutronix.deSigned-off-by: NTheodore Ts'o <tytso@mit.edu>
Cc: stable@kernel.org
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: NZheng Zengkai <zhengzengkai@huawei.com>
Acked-by: NXie XiuQi <xiexiuqi@huawei.com>

fs/ext4/ext4.h

@@ -2808,6 +2808,7 @@ bool ext4_fc_replay_check_excluded(struct super_block *sb, ext4_fsblk_t block);
 void ext4_fc_replay_cleanup(struct super_block *sb);
 int ext4_fc_commit(journal_t *journal, tid_t commit_tid);
 int __init ext4_fc_init_dentry_cache(void);
+void ext4_fc_destroy_dentry_cache(void);
 
 /* mballoc.c */
 extern const struct seq_operations ext4_mb_seq_groups_ops;

fs/ext4/fast_commit.c

@@ -2169,3 +2169,8 @@ int __init ext4_fc_init_dentry_cache(void)
 
 	return 0;
 }
+
+void ext4_fc_destroy_dentry_cache(void)
+{
+	kmem_cache_destroy(ext4_fc_dentry_cachep);
+}

fs/ext4/super.c

@@ -6830,6 +6830,7 @@ static int __init ext4_init_fs(void)
 out:
 	unregister_as_ext2();
 	unregister_as_ext3();
+	ext4_fc_destroy_dentry_cache();
 out05:
 	destroy_inodecache();
 out1:
@@ -6856,6 +6857,7 @@ static void __exit ext4_exit_fs(void)
 	unregister_as_ext2();
 	unregister_as_ext3();
 	unregister_filesystem(&ext4_fs_type);
+	ext4_fc_destroy_dentry_cache();
 	destroy_inodecache();
 	ext4_exit_mballoc();
 	ext4_exit_sysfs();