xfs: Refactor xfs_attr_set_shortform

This patch is actually the combination of patches from the previous
version (v18).  Initially patch 3 hoisted xfs_attr_set_shortform, and
the next added the helper xfs_attr_set_fmt. xfs_attr_set_fmt is similar
the old xfs_attr_set_shortform. It returns 0 when the attr has been set
and no further action is needed. It returns -EAGAIN when shortform has
been transformed to leaf, and the calling function should proceed the
set the attr in leaf form.
Signed-off-by: Allison Henderson <allison.henderson@oracle.com>
Reviewed-by: Brian Foster <bfoster@redhat.com>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Chandan Babu R <chandanrlinux@gmail.com>

fs/xfs/libxfs/xfs_attr.c

@@ -236,16 +236,11 @@ xfs_attr_is_shortform(
 		ip->i_afp->if_nextents == 0);
 }
 
-/*
- * Attempts to set an attr in shortform, or converts short form to leaf form if
- * there is not enough room.  If the attr is set, the transaction is committed
- * and set to NULL.
- */
 STATIC int
-xfs_attr_set_shortform(
-	struct xfs_da_args	*args,
-	struct xfs_buf		**leaf_bp)
+xfs_attr_set_fmt(
+	struct xfs_da_args	*args)
 {
+	struct xfs_buf          *leaf_bp = NULL;
 	struct xfs_inode	*dp = args->dp;
 	int			error, error2 = 0;
 
@@ -258,29 +253,29 @@ xfs_attr_set_shortform(
 		args->trans = NULL;
 		return error ? error : error2;
 	}
+
 	/*
 	 * It won't fit in the shortform, transform to a leaf block.  GROT:
 	 * another possible req'mt for a double-split btree op.
 	 */
-	error = xfs_attr_shortform_to_leaf(args, leaf_bp);
+	error = xfs_attr_shortform_to_leaf(args, &leaf_bp);
 	if (error)
 		return error;
 
 	/*
 	 * Prevent the leaf buffer from being unlocked so that a concurrent AIL
 	 * push cannot grab the half-baked leaf buffer and run into problems
-	 * with the write verifier. Once we're done rolling the transaction we
-	 * can release the hold and add the attr to the leaf.
+	 * with the write verifier.
 	 */
-	xfs_trans_bhold(args->trans, *leaf_bp);
+	xfs_trans_bhold(args->trans, leaf_bp);
 	error = xfs_defer_finish(&args->trans);
-	xfs_trans_bhold_release(args->trans, *leaf_bp);
+	xfs_trans_bhold_release(args->trans, leaf_bp);
 	if (error) {
-		xfs_trans_brelse(args->trans, *leaf_bp);
+		xfs_trans_brelse(args->trans, leaf_bp);
 		return error;
 	}
 
-	return 0;
+	return -EAGAIN;
 }
 
 /*
@@ -291,8 +286,7 @@ xfs_attr_set_args(
 	struct xfs_da_args	*args)
 {
 	struct xfs_inode	*dp = args->dp;
-	struct xfs_buf          *leaf_bp = NULL;
-	int			error = 0;
+	int			error;
 
 	/*
 	 * If the attribute list is already in leaf format, jump straight to
@@ -301,15 +295,8 @@ xfs_attr_set_args(
 	 * again.
 	 */
 	if (xfs_attr_is_shortform(dp)) {
-
-		/*
-		 * If the attr was successfully set in shortform, the
-		 * transaction is committed and set to NULL.  Otherwise, is it
-		 * converted from shortform to leaf, and the transaction is
-		 * retained.
-		 */
-		error = xfs_attr_set_shortform(args, &leaf_bp);
-		if (error || !args->trans)
+		error = xfs_attr_set_fmt(args);
+		if (error != -EAGAIN)
 			return error;
 	}
 
@@ -344,8 +331,7 @@ xfs_attr_set_args(
 			return error;
 	}
 
-	error = xfs_attr_node_addname(args);
-	return error;
+	return xfs_attr_node_addname(args);
 }
 
 /*