ceph: ensure d_name stability in ceph_dentry_hash()

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>

diff --git a/fs/ceph/dir.c b/fs/ceph/dir.c
index cec25691cbae9de126fdd1e8890a9083e0596d80..2ffc7fe8da52f272b5d6bf56da7e75f58a85cbda 100644 (file)
--- a/fs/ceph/dir.c
+++ b/fs/ceph/dir.c
@@ -1471,6 +1471,7 @@ void ceph_dentry_lru_del(struct dentry *dn)
 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 */
@@ -1478,8 +1479,11 @@ unsigned ceph_dentry_hash(struct inode *dir, struct dentry *dn)
                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;
        }
 }