ceph: avoid accessing / when mounting a subpath

Accessing / causes failuire if the client has caps that restrict path

Signed-off-by: Yan, Zheng <zyan@redhat.com>

1 files changed, 20 insertions, 29 deletions

diff --git a/fs/ceph/super.c b/fs/ceph/super.c
index e247f6f0feb7..a29ffce98187 100644
--- a/fs/ceph/super.c
+++ b/fs/ceph/super.c
@@ -396,10 +396,12 @@ static int parse_mount_options(struct ceph_mount_options **pfsopt,
          */
         dev_name_end = strchr(dev_name, '/');
         if (dev_name_end) {
-                fsopt->server_path = kstrdup(dev_name_end, GFP_KERNEL);
-                if (!fsopt->server_path) {
-                        err = -ENOMEM;
-                        goto out;
+                if (strlen(dev_name_end) > 1) {
+                        fsopt->server_path = kstrdup(dev_name_end, GFP_KERNEL);
+                        if (!fsopt->server_path) {
+                                err = -ENOMEM;
+                                goto out;
+                        }
                 }
         } else {
                 dev_name_end = dev_name + strlen(dev_name);
@@ -788,15 +790,10 @@ static struct dentry *open_root_dentry(struct ceph_fs_client *fsc,
                 struct inode *inode = req->r_target_inode;
                 req->r_target_inode = NULL;
                 dout("open_root_inode success\n");
-                if (ceph_ino(inode) == CEPH_INO_ROOT &&
-                    fsc->sb->s_root == NULL) {
-                        root = d_make_root(inode);
-                        if (!root) {
-                                root = ERR_PTR(-ENOMEM);
-                                goto out;
-                        }
-                } else {
-                        root = d_obtain_root(inode);
+                root = d_make_root(inode);
+                if (!root) {
+                        root = ERR_PTR(-ENOMEM);
+                        goto out;
                 }
                 ceph_init_dentry(root);
                 dout("open_root_inode success, root dentry is %p\n", root);
@@ -825,17 +822,24 @@ static struct dentry *ceph_real_mount(struct ceph_fs_client *fsc)
         mutex_lock(&fsc->client->mount_mutex);
 
         if (!fsc->sb->s_root) {
+                const char *path;
                 err = __ceph_open_session(fsc->client, started);
                 if (err < 0)
                         goto out;
 
-                dout("mount opening root\n");
-                root = open_root_dentry(fsc, "", started);
+                if (!fsc->mount_options->server_path) {
+                        path = "";
+                        dout("mount opening path \\t\n");
+                } else {
+                        path = fsc->mount_options->server_path + 1;
+                        dout("mount opening path %s\n", path);
+                }
+                root = open_root_dentry(fsc, path, started);
                 if (IS_ERR(root)) {
                         err = PTR_ERR(root);
                         goto out;
                 }
-                fsc->sb->s_root = root;
+                fsc->sb->s_root = dget(root);
                 first = 1;
 
                 err = ceph_fs_debugfs_init(fsc);
@@ -843,19 +847,6 @@ static struct dentry *ceph_real_mount(struct ceph_fs_client *fsc)
                         goto fail;
         }
 
-        if (!fsc->mount_options->server_path) {
-                root = fsc->sb->s_root;
-                dget(root);
-        } else {
-                const char *path = fsc->mount_options->server_path + 1;
-                dout("mount opening path %s\n", path);
-                root = open_root_dentry(fsc, path, started);
-                if (IS_ERR(root)) {
-                        err = PTR_ERR(root);
-                        goto fail;
-                }
-        }
-
         fsc->mount_state = CEPH_MOUNT_MOUNTED;
         dout("mount success\n");
         mutex_unlock(&fsc->client->mount_mutex);