linux-ext4 - [PATCH 05/13] hfsplus: switch to rcu-delayed unloading of nls and freeing ->s_fs

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Date: Sun,  4 Feb 2024 02:17:31 +0000
From: Al Viro <viro@...iv.linux.org.uk>
To: linux-fsdevel@...r.kernel.org
Cc: Linus Torvalds <torvalds@...ux-foundation.org>,
	Christian Brauner <brauner@...nel.org>,
	linux-ext4@...r.kernel.org,
	linux-nfs@...r.kernel.org,
	Miklos Szeredi <miklos@...redi.hu>,
	linux-cifs@...r.kernel.org
Subject: [PATCH 05/13] hfsplus: switch to rcu-delayed unloading of nls and freeing ->s_fs_info

->d_hash() and ->d_compare() use those, so we need to delay freeing
them.

Signed-off-by: Al Viro <viro@...iv.linux.org.uk>
---
 fs/hfsplus/hfsplus_fs.h |  1 +
 fs/hfsplus/super.c      | 12 +++++++++---
 2 files changed, 10 insertions(+), 3 deletions(-)

diff --git a/fs/hfsplus/hfsplus_fs.h b/fs/hfsplus/hfsplus_fs.h
index 7ededcb720c1..012a3d003fbe 100644
--- a/fs/hfsplus/hfsplus_fs.h
+++ b/fs/hfsplus/hfsplus_fs.h
@@ -190,6 +190,7 @@ struct hfsplus_sb_info {
 	int work_queued;               /* non-zero delayed work is queued */
 	struct delayed_work sync_work; /* FS sync delayed work */
 	spinlock_t work_lock;          /* protects sync_work and work_queued */
+	struct rcu_head rcu;
 };
 
 #define HFSPLUS_SB_WRITEBACKUP	0
diff --git a/fs/hfsplus/super.c b/fs/hfsplus/super.c
index 1986b4f18a90..97920202790f 100644
--- a/fs/hfsplus/super.c
+++ b/fs/hfsplus/super.c
@@ -277,6 +277,14 @@ void hfsplus_mark_mdb_dirty(struct super_block *sb)
 	spin_unlock(&sbi->work_lock);
 }
 
+static void delayed_free(struct rcu_head *p)
+{
+	struct hfsplus_sb_info *sbi = container_of(p, struct hfsplus_sb_info, rcu);
+
+	unload_nls(sbi->nls);
+	kfree(sbi);
+}
+
 static void hfsplus_put_super(struct super_block *sb)
 {
 	struct hfsplus_sb_info *sbi = HFSPLUS_SB(sb);
@@ -302,9 +310,7 @@ static void hfsplus_put_super(struct super_block *sb)
 	hfs_btree_close(sbi->ext_tree);
 	kfree(sbi->s_vhdr_buf);
 	kfree(sbi->s_backup_vhdr_buf);
-	unload_nls(sbi->nls);
-	kfree(sb->s_fs_info);
-	sb->s_fs_info = NULL;
+	call_rcu(&sbi->rcu, delayed_free);
 }
 
 static int hfsplus_statfs(struct dentry *dentry, struct kstatfs *buf)
-- 
2.39.2