ceph: ensure d_name stability in ceph_dentry_hash()

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>

diff --git a/fs/ceph/dir.c b/fs/ceph/dir.c
index a8f4298..0637149 100644 (file)
--- a/fs/ceph/dir.c
+++ b/fs/ceph/dir.c
@@ -1766,6 +1766,7 @@ static ssize_t ceph_read_dir(struct file *file, char __user *buf, size_t size,
 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 */
@@ -1773,8 +1774,11 @@ 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;
        }
 }