linux-kernel - [PATCH 5.10 5/5] kernfs: dont call d_splice

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Message-ID: <20250521015336.3450911-6-dqfext@gmail.com>
Date: Wed, 21 May 2025 09:53:35 +0800
From: Qingfang Deng <dqfext@...il.com>
To: stable@...r.kernel.org,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	Tejun Heo <tj@...nel.org>,
	linux-kernel@...r.kernel.org
Cc: Ian Kent <raven@...maw.net>,
	Miklos Szeredi <mszeredi@...hat.com>
Subject: [PATCH 5.10 5/5] kernfs: dont call d_splice_alias() under kernfs node lock

From: Ian Kent <raven@...maw.net>

Commit df6192f47d2311cf40cd4321cc59863a5853b665 upstream.

The call to d_splice_alias() in kernfs_iop_lookup() doesn't depend on
any kernfs node so there's no reason to hold the kernfs node lock when
calling it.

Reviewed-by: Miklos Szeredi <mszeredi@...hat.com>
Signed-off-by: Ian Kent <raven@...maw.net>
Link: https://lore.kernel.org/r/162642772000.63632.10672683419693513226.stgit@web.messagingengine.com
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
 fs/kernfs/dir.c | 6 ++----
 1 file changed, 2 insertions(+), 4 deletions(-)

diff --git a/fs/kernfs/dir.c b/fs/kernfs/dir.c
index 0443a9cd72a3..f301605d70b0 100644
--- a/fs/kernfs/dir.c
+++ b/fs/kernfs/dir.c
@@ -1122,7 +1122,6 @@ static struct dentry *kernfs_iop_lookup(struct inode *dir,
 					struct dentry *dentry,
 					unsigned int flags)
 {
-	struct dentry *ret;
 	struct kernfs_node *parent = dir->i_private;
 	struct kernfs_node *kn;
 	struct inode *inode = NULL;
@@ -1142,11 +1141,10 @@ static struct dentry *kernfs_iop_lookup(struct inode *dir,
 	/* Needed only for negative dentry validation */
 	if (!inode)
 		kernfs_set_rev(parent, dentry);
-	/* instantiate and hash (possibly negative) dentry */
-	ret = d_splice_alias(inode, dentry);
 	up_read(&kernfs_rwsem);
 
-	return ret;
+	/* instantiate and hash (possibly negative) dentry */
+	return d_splice_alias(inode, dentry);
 }
 
 static int kernfs_iop_mkdir(struct inode *dir, struct dentry *dentry,
-- 
2.43.0