btrfs: rename do_setxattr to btrfs_setxattr

When trans is not NULL btrfs_setxattr() calls do_setxattr() directly
with a check for readonly root. Rename do_setxattr() btrfs_setxattr() in
preparation to call do_setxattr() directly instead.  Preparatory patch,
no functional changes.
Signed-off-by: Anand Jain <anand.jain@oracle.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

fs/btrfs/xattr.c

@@ -76,9 +76,9 @@ int btrfs_getxattr(struct inode *inode, const char *name,
 	return ret;
 }
 
-static int do_setxattr(struct btrfs_trans_handle *trans,
-		       struct inode *inode, const char *name,
-		       const void *value, size_t size, int flags)
+static int btrfs_setxattr(struct btrfs_trans_handle *trans,
+			  struct inode *inode, const char *name,
+			  const void *value, size_t size, int flags)
 {
 	struct btrfs_dir_item *di = NULL;
 	struct btrfs_root *root = BTRFS_I(inode)->root;
@@ -231,13 +231,13 @@ int btrfs_setxattr_trans(struct btrfs_trans_handle *trans,
 		return -EROFS;
 
 	if (trans)
-		return do_setxattr(trans, inode, name, value, size, flags);
+		return btrfs_setxattr(trans, inode, name, value, size, flags);
 
 	trans = btrfs_start_transaction(root, 2);
 	if (IS_ERR(trans))
 		return PTR_ERR(trans);
 
-	ret = do_setxattr(trans, inode, name, value, size, flags);
+	ret = btrfs_setxattr(trans, inode, name, value, size, flags);
 	if (ret)
 		goto out;