ceph: fix dentry leak when failing to init debugfs

When failing from ceph_fs_debugfs_init() in ceph_real_mount(),
there is lack of dput of root_dentry and it causes slab errors,
so change the calling order of ceph_fs_debugfs_init() and
open_root_dentry() and do some cleanups to avoid this issue.

Signed-off-by: Chengguang Xu <cgxu519@icloud.com>
Reviewed-by: "Yan, Zheng" <zyan@redhat.com>
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>

1 files changed, 5 insertions, 11 deletions

diff --git a/fs/ceph/super.c b/fs/ceph/super.c
index bfc85b22a190..1c470b453a9e 100644
--- a/fs/ceph/super.c
+++ b/fs/ceph/super.c
@@ -838,7 +838,6 @@ static struct dentry *ceph_real_mount(struct ceph_fs_client *fsc)
         int err;
         unsigned long started = jiffies;  /* note the start time */
         struct dentry *root;
-        int first = 0;   /* first vfsmount for this super_block */
 
         dout("mount start %p\n", fsc);
         mutex_lock(&fsc->client->mount_mutex);
@@ -863,17 +862,17 @@ static struct dentry *ceph_real_mount(struct ceph_fs_client *fsc)
                         path = fsc->mount_options->server_path + 1;
                         dout("mount opening path %s\n", path);
                 }
+
+                err = ceph_fs_debugfs_init(fsc);
+                if (err < 0)
+                        goto out;
+
                 root = open_root_dentry(fsc, path, started);
                 if (IS_ERR(root)) {
                         err = PTR_ERR(root);
                         goto out;
                 }
                 fsc->sb->s_root = dget(root);
-                first = 1;
-
-                err = ceph_fs_debugfs_init(fsc);
-                if (err < 0)
-                        goto fail;
         } else {
                 root = dget(fsc->sb->s_root);
         }
@@ -883,11 +882,6 @@ static struct dentry *ceph_real_mount(struct ceph_fs_client *fsc)
         mutex_unlock(&fsc->client->mount_mutex);
         return root;
 
-fail:
-        if (first) {
-                dput(fsc->sb->s_root);
-                fsc->sb->s_root = NULL;
-        }
 out:
         mutex_unlock(&fsc->client->mount_mutex);
         return ERR_PTR(err);