vfs: rename: use common code for dir and non-dir

There's actually very little difference between vfs_rename_dir() and
vfs_rename_other() so move both inline into vfs_rename() which still stays
reasonably readable.
Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
Reviewed-by: J. Bruce Fields <bfields@redhat.com>

fs/namei.c

@@ -3973,7 +3973,27 @@ SYSCALL_DEFINE2(link, const char __user *, oldname, const char __user *, newname
 	return sys_linkat(AT_FDCWD, oldname, AT_FDCWD, newname, 0);
 }
 
-/*
+/**
+ * vfs_rename - rename a filesystem object
+ * @old_dir:	parent of source
+ * @old_dentry:	source
+ * @new_dir:	parent of destination
+ * @new_dentry:	destination
+ * @delegated_inode: returns an inode needing a delegation break
+ *
+ * The caller must hold multiple mutexes--see lock_rename()).
+ *
+ * If vfs_rename discovers a delegation in need of breaking at either
+ * the source or destination, it will return -EWOULDBLOCK and return a
+ * reference to the inode in delegated_inode.  The caller should then
+ * break the delegation and retry.  Because breaking a delegation may
+ * take a long time, the caller should drop all locks before doing
+ * so.
+ *
+ * Alternatively, a caller may pass NULL for delegated_inode.  This may
+ * be appropriate for callers that expect the underlying filesystem not
+ * to be NFS exported.
+ *
  * The worst of all namespace operations - renaming directory. "Perverted"
  * doesn't even start to describe it. Somebody in UCB had a heck of a trip...
  * Problems:
@@ -4001,19 +4021,39 @@ SYSCALL_DEFINE2(link, const char __user *, oldname, const char __user *, newname
  *	   ->i_mutex on parents, which works but leads to some truly excessive
  *	   locking].
  */
-static int vfs_rename_dir(struct inode *old_dir, struct dentry *old_dentry,
-			  struct inode *new_dir, struct dentry *new_dentry)
+int vfs_rename(struct inode *old_dir, struct dentry *old_dentry,
+	       struct inode *new_dir, struct dentry *new_dentry,
+	       struct inode **delegated_inode)
 {
-	int error = 0;
+	int error;
+	bool is_dir = d_is_dir(old_dentry);
+	const unsigned char *old_name;
+	struct inode *source = old_dentry->d_inode;
 	struct inode *target = new_dentry->d_inode;
-	unsigned max_links = new_dir->i_sb->s_max_links;
+
+	if (source == target)
+		return 0;
+
+	error = may_delete(old_dir, old_dentry, is_dir);
+	if (error)
+		return error;
+
+	if (!target)
+		error = may_create(new_dir, new_dentry);
+	else
+		error = may_delete(new_dir, new_dentry, is_dir);
+	if (error)
+		return error;
+
+	if (!old_dir->i_op->rename)
+		return -EPERM;
 
 	/*
 	 * If we are going to change the parent - check write permissions,
 	 * we'll need to flip '..'.
 	 */
-	if (new_dir != old_dir) {
-		error = inode_permission(old_dentry->d_inode, MAY_WRITE);
+	if (is_dir && new_dir != old_dir) {
+		error = inode_permission(source, MAY_WRITE);
 		if (error)
 			return error;
 	}
@@ -4022,14 +4062,20 @@ static int vfs_rename_dir(struct inode *old_dir, struct dentry *old_dentry,
 	if (error)
 		return error;
 
+	old_name = fsnotify_oldname_init(old_dentry->d_name.name);
 	dget(new_dentry);
-	if (target)
+	if (!is_dir)
+		lock_two_nondirectories(source, target);
+	else if (target)
 		mutex_lock(&target->i_mutex);
 
 	error = -EBUSY;
 	if (d_mountpoint(old_dentry) || d_mountpoint(new_dentry))
 		goto out;
 
+	if (is_dir) {
+		unsigned max_links = new_dir->i_sb->s_max_links;
+
 		error = -EMLINK;
 		if (max_links && !target && new_dir != old_dir &&
 		    new_dir->i_nlink >= max_links)
@@ -4037,42 +4083,7 @@ static int vfs_rename_dir(struct inode *old_dir, struct dentry *old_dentry,
 
 		if (target)
 			shrink_dcache_parent(new_dentry);
-	error = old_dir->i_op->rename(old_dir, old_dentry, new_dir, new_dentry);
-	if (error)
-		goto out;
-
-	if (target) {
-		target->i_flags |= S_DEAD;
-		dont_mount(new_dentry);
-	}
-	if (!(old_dir->i_sb->s_type->fs_flags & FS_RENAME_DOES_D_MOVE))
-		d_move(old_dentry, new_dentry);
-out:
-	if (target)
-		mutex_unlock(&target->i_mutex);
-	dput(new_dentry);
-	return error;
-}
-
-static int vfs_rename_other(struct inode *old_dir, struct dentry *old_dentry,
-			    struct inode *new_dir, struct dentry *new_dentry,
-			    struct inode **delegated_inode)
-{
-	struct inode *target = new_dentry->d_inode;
-	struct inode *source = old_dentry->d_inode;
-	int error;
-
-	error = security_inode_rename(old_dir, old_dentry, new_dir, new_dentry);
-	if (error)
-		return error;
-
-	dget(new_dentry);
-	lock_two_nondirectories(source, target);
-
-	error = -EBUSY;
-	if (d_mountpoint(old_dentry)||d_mountpoint(new_dentry))
-		goto out;
-
+	} else {
 		error = try_break_deleg(source, delegated_inode);
 		if (error)
 			goto out;
@@ -4081,75 +4092,27 @@ static int vfs_rename_other(struct inode *old_dir, struct dentry *old_dentry,
 			if (error)
 				goto out;
 		}
+	}
 	error = old_dir->i_op->rename(old_dir, old_dentry, new_dir, new_dentry);
 	if (error)
 		goto out;
 
-	if (target)
+	if (target) {
+		if (is_dir)
+			target->i_flags |= S_DEAD;
 		dont_mount(new_dentry);
+	}
 	if (!(old_dir->i_sb->s_type->fs_flags & FS_RENAME_DOES_D_MOVE))
 		d_move(old_dentry, new_dentry);
 out:
+	if (!is_dir)
 		unlock_two_nondirectories(source, target);
+	else if (target)
+		mutex_unlock(&target->i_mutex);
 	dput(new_dentry);
-	return error;
-}
-
-/**
- * vfs_rename - rename a filesystem object
- * @old_dir:	parent of source
- * @old_dentry:	source
- * @new_dir:	parent of destination
- * @new_dentry:	destination
- * @delegated_inode: returns an inode needing a delegation break
- *
- * The caller must hold multiple mutexes--see lock_rename()).
- *
- * If vfs_rename discovers a delegation in need of breaking at either
- * the source or destination, it will return -EWOULDBLOCK and return a
- * reference to the inode in delegated_inode.  The caller should then
- * break the delegation and retry.  Because breaking a delegation may
- * take a long time, the caller should drop all locks before doing
- * so.
- *
- * Alternatively, a caller may pass NULL for delegated_inode.  This may
- * be appropriate for callers that expect the underlying filesystem not
- * to be NFS exported.
- */
-int vfs_rename(struct inode *old_dir, struct dentry *old_dentry,
-	       struct inode *new_dir, struct dentry *new_dentry,
-	       struct inode **delegated_inode)
-{
-	int error;
-	int is_dir = d_is_dir(old_dentry);
-	const unsigned char *old_name;
-
-	if (old_dentry->d_inode == new_dentry->d_inode)
- 		return 0;
- 
-	error = may_delete(old_dir, old_dentry, is_dir);
-	if (error)
-		return error;
-
-	if (!new_dentry->d_inode)
-		error = may_create(new_dir, new_dentry);
-	else
-		error = may_delete(new_dir, new_dentry, is_dir);
-	if (error)
-		return error;
-
-	if (!old_dir->i_op->rename)
-		return -EPERM;
-
-	old_name = fsnotify_oldname_init(old_dentry->d_name.name);
-
-	if (is_dir)
-		error = vfs_rename_dir(old_dir,old_dentry,new_dir,new_dentry);
-	else
-		error = vfs_rename_other(old_dir,old_dentry,new_dir,new_dentry,delegated_inode);
 	if (!error)
 		fsnotify_move(old_dir, new_dir, old_name, is_dir,
-			      new_dentry->d_inode, old_dentry);
+			      target, old_dentry);
 	fsnotify_oldname_free(old_name);
 
 	return error;