linux-kernel - [PATCH 5.15 066/189] cifs: release cached dentries only if mount is complete

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Date:   Mon, 18 Apr 2022 14:11:26 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Shyam Prasad N <sprasad@...rosoft.com>,
        Ronnie Sahlberg <lsahlber@...hat.com>,
        Steve French <stfrench@...rosoft.com>,
        Sasha Levin <sashal@...nel.org>
Subject: [PATCH 5.15 066/189] cifs: release cached dentries only if mount is complete

From: Shyam Prasad N <sprasad@...rosoft.com>

[ Upstream commit d788e51636462e61c6883f7d96b07b06bc291650 ]

During cifs_kill_sb, we first dput all the dentries that we have cached.
However this function can also get called for mount failures.
So dput the cached dentries only if the filesystem mount is complete.
i.e. cifs_sb->root is populated.

Fixes: 5e9c89d43fa6 ("cifs: Grab a reference for the dentry of the cached directory during the lifetime of the cache")
Signed-off-by: Shyam Prasad N <sprasad@...rosoft.com>
Reviewed-by: Ronnie Sahlberg <lsahlber@...hat.com>
Signed-off-by: Steve French <stfrench@...rosoft.com>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 fs/cifs/cifsfs.c | 28 +++++++++++++++-------------
 1 file changed, 15 insertions(+), 13 deletions(-)

diff --git a/fs/cifs/cifsfs.c b/fs/cifs/cifsfs.c
index ed220daca3e1..92fd1a7e83dc 100644
--- a/fs/cifs/cifsfs.c
+++ b/fs/cifs/cifsfs.c
@@ -266,22 +266,24 @@ static void cifs_kill_sb(struct super_block *sb)
 	 * before we kill the sb.
 	 */
 	if (cifs_sb->root) {
+		node = rb_first(root);
+		while (node != NULL) {
+			tlink = rb_entry(node, struct tcon_link, tl_rbnode);
+			tcon = tlink_tcon(tlink);
+			cfid = &tcon->crfid;
+			mutex_lock(&cfid->fid_mutex);
+			if (cfid->dentry) {
+				dput(cfid->dentry);
+				cfid->dentry = NULL;
+			}
+			mutex_unlock(&cfid->fid_mutex);
+			node = rb_next(node);
+		}
+
+		/* finally release root dentry */
 		dput(cifs_sb->root);
 		cifs_sb->root = NULL;
 	}
-	node = rb_first(root);
-	while (node != NULL) {
-		tlink = rb_entry(node, struct tcon_link, tl_rbnode);
-		tcon = tlink_tcon(tlink);
-		cfid = &tcon->crfid;
-		mutex_lock(&cfid->fid_mutex);
-		if (cfid->dentry) {
-			dput(cfid->dentry);
-			cfid->dentry = NULL;
-		}
-		mutex_unlock(&cfid->fid_mutex);
-		node = rb_next(node);
-	}
 
 	kill_anon_super(sb);
 	cifs_umount(cifs_sb);
-- 
2.35.1