6 files changed, 54 insertions, 31 deletions

diff --git a/fs/btrfs/super.c b/fs/btrfs/super.c
index 8e16bca69c56..67b48b9a03e0 100644
--- a/fs/btrfs/super.c
+++ b/fs/btrfs/super.c
@@ -851,7 +851,6 @@ static struct dentry *get_default_root(struct super_block *sb,
         struct btrfs_path *path;
         struct btrfs_key location;
         struct inode *inode;
-        struct dentry *dentry;
         u64 dir_id;
         int new = 0;
 
@@ -922,13 +921,7 @@ setup_root:
                 return dget(sb->s_root);
         }
 
-        dentry = d_obtain_alias(inode);
-        if (!IS_ERR(dentry)) {
-                spin_lock(&dentry->d_lock);
-                dentry->d_flags &= ~DCACHE_DISCONNECTED;
-                spin_unlock(&dentry->d_lock);
-        }
-        return dentry;
+        return d_obtain_root(inode);
 }
 
 static int btrfs_fill_super(struct super_block *sb,
diff --git a/fs/ceph/super.c b/fs/ceph/super.c
index 06150fd745ac..f6e12377335c 100644
--- a/fs/ceph/super.c
+++ b/fs/ceph/super.c
@@ -755,7 +755,7 @@ static struct dentry *open_root_dentry(struct ceph_fs_client *fsc,
                                 goto out;
                         }
                 } else {
-                        root = d_obtain_alias(inode);
+                        root = d_obtain_root(inode);
                 }
                 ceph_init_dentry(root);
                 dout("open_root_inode success, root dentry is %p\n", root);
diff --git a/fs/dcache.c b/fs/dcache.c
index 3ed095363997..63d556c0e698 100644
--- a/fs/dcache.c
+++ b/fs/dcache.c
@@ -1781,25 +1781,7 @@ struct dentry *d_find_any_alias(struct inode *inode)
 }
 EXPORT_SYMBOL(d_find_any_alias);
 
-/**
- * d_obtain_alias - find or allocate a dentry for a given inode
- * @inode: inode to allocate the dentry for
- *
- * Obtain a dentry for an inode resulting from NFS filehandle conversion or
- * similar open by handle operations.  The returned dentry may be anonymous,
- * or may have a full name (if the inode was already in the cache).
- *
- * When called on a directory inode, we must ensure that the inode only ever
- * has one dentry.  If a dentry is found, that is returned instead of
- * allocating a new one.
- *
- * On successful return, the reference to the inode has been transferred
- * to the dentry.  In case of an error the reference on the inode is released.
- * To make it easier to use in export operations a %NULL or IS_ERR inode may
- * be passed in and will be the error will be propagate to the return value,
- * with a %NULL @inode replaced by ERR_PTR(-ESTALE).
- */
-struct dentry *d_obtain_alias(struct inode *inode)
+struct dentry *__d_obtain_alias(struct inode *inode, int disconnected)
 {
         static const struct qstr anonstring = QSTR_INIT("/", 1);
         struct dentry *tmp;
@@ -1830,7 +1812,10 @@ struct dentry *d_obtain_alias(struct inode *inode)
         }
 
         /* attach a disconnected dentry */
-        add_flags = d_flags_for_inode(inode) | DCACHE_DISCONNECTED;
+        add_flags = d_flags_for_inode(inode);
+
+        if (disconnected)
+                add_flags |= DCACHE_DISCONNECTED;
 
         spin_lock(&tmp->d_lock);
         tmp->d_inode = inode;
@@ -1851,9 +1836,53 @@ struct dentry *d_obtain_alias(struct inode *inode)
         iput(inode);
         return res;
 }
+
+/**
+ * d_obtain_alias - find or allocate a DISCONNECTED dentry for a given inode
+ * @inode: inode to allocate the dentry for
+ *
+ * Obtain a dentry for an inode resulting from NFS filehandle conversion or
+ * similar open by handle operations.  The returned dentry may be anonymous,
+ * or may have a full name (if the inode was already in the cache).
+ *
+ * When called on a directory inode, we must ensure that the inode only ever
+ * has one dentry.  If a dentry is found, that is returned instead of
+ * allocating a new one.
+ *
+ * On successful return, the reference to the inode has been transferred
+ * to the dentry.  In case of an error the reference on the inode is released.
+ * To make it easier to use in export operations a %NULL or IS_ERR inode may
+ * be passed in and the error will be propagated to the return value,
+ * with a %NULL @inode replaced by ERR_PTR(-ESTALE).
+ */
+struct dentry *d_obtain_alias(struct inode *inode)
+{
+        return __d_obtain_alias(inode, 1);
+}
 EXPORT_SYMBOL(d_obtain_alias);
 
 /**
+ * d_obtain_root - find or allocate a dentry for a given inode
+ * @inode: inode to allocate the dentry for
+ *
+ * Obtain an IS_ROOT dentry for the root of a filesystem.
+ *
+ * We must ensure that directory inodes only ever have one dentry.  If a
+ * dentry is found, that is returned instead of allocating a new one.
+ *
+ * On successful return, the reference to the inode has been transferred
+ * to the dentry.  In case of an error the reference on the inode is
+ * released.  A %NULL or IS_ERR inode may be passed in and will be the
+ * error will be propagate to the return value, with a %NULL @inode
+ * replaced by ERR_PTR(-ESTALE).
+ */
+struct dentry *d_obtain_root(struct inode *inode)
+{
+        return __d_obtain_alias(inode, 0);
+}
+EXPORT_SYMBOL(d_obtain_root);
+
+/**
  * d_add_ci - lookup or allocate new dentry with case-exact name
  * @inode:  the inode case-insensitive lookup has found
  * @dentry: the negative dentry that was passed to the parent's lookup func
diff --git a/fs/nfs/getroot.c b/fs/nfs/getroot.c
index b94f80420a58..880618a8b048 100644
--- a/fs/nfs/getroot.c
+++ b/fs/nfs/getroot.c
@@ -112,7 +112,7 @@ struct dentry *nfs_get_root(struct super_block *sb, struct nfs_fh *mntfh,
          * if the dentry tree reaches them; however if the dentry already
          * exists, we'll pick it up at this point and use it as the root
          */
-        ret = d_obtain_alias(inode);
+        ret = d_obtain_root(inode);
         if (IS_ERR(ret)) {
                 dprintk("nfs_get_root: get root dentry failed\n");
                 goto out;
diff --git a/fs/nilfs2/super.c b/fs/nilfs2/super.c
index 8c532b2ca3ab..ac914994dfed 100644
--- a/fs/nilfs2/super.c
+++ b/fs/nilfs2/super.c
@@ -942,7 +942,7 @@ static int nilfs_get_root_dentry(struct super_block *sb,
                         iput(inode);
                 }
         } else {
-                dentry = d_obtain_alias(inode);
+                dentry = d_obtain_root(inode);
                 if (IS_ERR(dentry)) {
                         ret = PTR_ERR(dentry);
                         goto failed_dentry;
diff --git a/include/linux/dcache.h b/include/linux/dcache.h
index 3c7ec327ebd2..e4ae2ad48d07 100644
--- a/include/linux/dcache.h
+++ b/include/linux/dcache.h
@@ -249,6 +249,7 @@ extern struct dentry * d_splice_alias(struct inode *, struct dentry *);
 extern struct dentry * d_add_ci(struct dentry *, struct inode *, struct qstr *);
 extern struct dentry *d_find_any_alias(struct inode *inode);
 extern struct dentry * d_obtain_alias(struct inode *);
+extern struct dentry * d_obtain_root(struct inode *);
 extern void shrink_dcache_sb(struct super_block *);
 extern void shrink_dcache_parent(struct dentry *);
 extern void shrink_dcache_for_umount(struct super_block *);