[PATCH 5/8] fs: introduce struct super_operations::destroy_super() callback

From: Qi Zheng <qi.zheng@linux.dev>
To: akpm@linux-foundation.org, tkhai@ya.ru, roman.gushchin@linux.dev,
	vbabka@suse.cz, viro@zeniv.linux.org.uk, brauner@kernel.org,
	djwong@kernel.org, hughd@google.com, paulmck@kernel.org,
	muchun.song@linux.dev
Cc: linux-mm@kvack.org, linux-fsdevel@vger.kernel.org,
	linux-xfs@vger.kernel.org, linux-kernel@vger.kernel.org,
	Qi Zheng <zhengqi.arch@bytedance.com>
Subject: [PATCH 5/8] fs: introduce struct super_operations::destroy_super() callback
Date: Wed, 31 May 2023 09:57:39 +0000	[thread overview]
Message-ID: <20230531095742.2480623-6-qi.zheng@linux.dev> (raw)
In-Reply-To: <20230531095742.2480623-1-qi.zheng@linux.dev>

From: Kirill Tkhai <tkhai@ya.ru>

The patch introduces a new callback, which will be called
asynchronous from delayed work.

This will allows to make ::nr_cached_objects() safe
to be called on destroying superblock in next patches,
and to split unregister_shrinker() into two primitives.

Signed-off-by: Kirill Tkhai <tkhai@ya.ru>
Signed-off-by: Qi Zheng <zhengqi.arch@bytedance.com>
---
 fs/super.c         | 3 +++
 include/linux/fs.h | 1 +
 2 files changed, 4 insertions(+)

diff --git a/fs/super.c b/fs/super.c
index 2ce54561e82e..4e9d08224f86 100644
--- a/fs/super.c
+++ b/fs/super.c
@@ -170,6 +170,9 @@ static void destroy_super_work(struct work_struct *work)
 	list_lru_destroy(&s->s_dentry_lru);
 	list_lru_destroy(&s->s_inode_lru);
 
+	if (s->s_op->destroy_super)
+		s->s_op->destroy_super(s);
+
 	for (i = 0; i < SB_FREEZE_LEVELS; i++)
 		percpu_free_rwsem(&s->s_writers.rw_sem[i]);
 	kfree(s);
diff --git a/include/linux/fs.h b/include/linux/fs.h
index 0b54ac1d331b..30b46d0facfc 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -1910,6 +1910,7 @@ struct super_operations {
 	int (*drop_inode) (struct inode *);
 	void (*evict_inode) (struct inode *);
 	void (*put_super) (struct super_block *);
+	void (*destroy_super) (struct super_block *);
 	int (*sync_fs)(struct super_block *sb, int wait);
 	int (*freeze_super) (struct super_block *);
 	int (*freeze_fs) (struct super_block *);
-- 
2.30.2

