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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org, Jeff Layton <jlayton@kernel.org>,
        "Yan, Zheng" <zyan@redhat.com>, Ilya Dryomov <idryomov@gmail.com>
Subject: [PATCH 3.18 04/86] ceph: ensure d_name stability in ceph_dentry_hash()
Date:   Wed, 15 May 2019 12:54:41 +0200
Message-Id: <20190515090643.214149763@linuxfoundation.org>
In-Reply-To: <20190515090642.339346723@linuxfoundation.org>
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From: Jeff Layton <jlayton@kernel.org>

commit 76a495d666e5043ffc315695f8241f5e94a98849 upstream.

Take the d_lock here to ensure that d_name doesn't change.

Cc: stable@vger.kernel.org
Signed-off-by: Jeff Layton <jlayton@kernel.org>
Reviewed-by: "Yan, Zheng" <zyan@redhat.com>
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 fs/ceph/dir.c |    6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

--- a/fs/ceph/dir.c
+++ b/fs/ceph/dir.c
@@ -1308,6 +1308,7 @@ void ceph_dentry_lru_del(struct dentry *
 unsigned ceph_dentry_hash(struct inode *dir, struct dentry *dn)
 {
 	struct ceph_inode_info *dci = ceph_inode(dir);
+	unsigned hash;
 
 	switch (dci->i_dir_layout.dl_dir_hash) {
 	case 0:	/* for backward compat */
@@ -1315,8 +1316,11 @@ unsigned ceph_dentry_hash(struct inode *
 		return dn->d_name.hash;
 
 	default:
-		return ceph_str_hash(dci->i_dir_layout.dl_dir_hash,
+		spin_lock(&dn->d_lock);
+		hash = ceph_str_hash(dci->i_dir_layout.dl_dir_hash,
 				     dn->d_name.name, dn->d_name.len);
+		spin_unlock(&dn->d_lock);
+		return hash;
 	}
 }