vfs: Add inode uid,gid,mode init helper

Signed-off-by: NDmitry Monakhov <dmonakhov@openvz.org>
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>

fs/inode.c

@@ -1606,3 +1606,23 @@ void init_special_inode(struct inode *inode, umode_t mode, dev_t rdev)
 				  inode->i_ino);
 }
 EXPORT_SYMBOL(init_special_inode);
+
+/**
+ * Init uid,gid,mode for new inode according to posix standards
+ * @inode: New inode
+ * @dir: Directory inode
+ * @mode: mode of the new inode
+ */
+void inode_init_owner(struct inode *inode, const struct inode *dir,
+			mode_t mode)
+{
+	inode->i_uid = current_fsuid();
+	if (dir && dir->i_mode & S_ISGID) {
+		inode->i_gid = dir->i_gid;
+		if (S_ISDIR(mode))
+			mode |= S_ISGID;
+	} else
+		inode->i_gid = current_fsgid();
+	inode->i_mode = mode;
+}
+EXPORT_SYMBOL(inode_init_owner);

include/linux/fs.h

@@ -1428,7 +1428,8 @@ extern void dentry_unhash(struct dentry *dentry);
  * VFS file helper functions.
  */
 extern int file_permission(struct file *, int);
-
+extern void inode_init_owner(struct inode *inode, const struct inode *dir,
+			mode_t mode);
 /*
  * VFS FS_IOC_FIEMAP helper definitions.
  */