xfs: Add helpers xfs_attr_is_shortform and xfs_attr_set_shortform

In this patch, we hoist code from xfs_attr_set_args into two new helpers
xfs_attr_is_shortform and xfs_attr_set_shortform.  These two will help
to simplify xfs_attr_set_args when we get into delayed attrs later.
Signed-off-by: Allison Collins <allison.henderson@oracle.com>
Reviewed-by: Brian Foster <bfoster@redhat.com>
Reviewed-by: Chandan Rajendra <chandanrlinux@gmail.com>
Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Acked-by: Dave Chinner <dchinner@redhat.com>

fs/xfs/libxfs/xfs_attr.c

@@ -204,23 +204,30 @@ xfs_attr_try_sf_addname(
 }
 
 /*
- * Set the attribute specified in @args.
+ * Check to see if the attr should be upgraded from non-existent or shortform to
+ * single-leaf-block attribute list.
  */
-int
-xfs_attr_set_args(
-	struct xfs_da_args	*args)
+static inline bool
+xfs_attr_is_shortform(
+	struct xfs_inode    *ip)
 {
-	struct xfs_inode	*dp = args->dp;
-	struct xfs_buf          *leaf_bp = NULL;
-	int			error, error2 = 0;
+	return ip->i_afp->if_format == XFS_DINODE_FMT_LOCAL ||
+	       (ip->i_afp->if_format == XFS_DINODE_FMT_EXTENTS &&
+		ip->i_afp->if_nextents == 0);
+}
 
-	/*
-	 * If the attribute list is non-existent or a shortform list,
-	 * upgrade it to a single-leaf-block attribute list.
+/*
+ * 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.
  */
-	if (dp->i_afp->if_format == XFS_DINODE_FMT_LOCAL ||
-	    (dp->i_afp->if_format == XFS_DINODE_FMT_EXTENTS &&
-	     dp->i_afp->if_nextents == 0)) {
+STATIC int
+xfs_attr_set_shortform(
+	struct xfs_da_args	*args,
+	struct xfs_buf		**leaf_bp)
+{
+	struct xfs_inode	*dp = args->dp;
+	int			error, error2 = 0;
 
 	/*
 	 * Try to add the attr to the attribute list in the inode.
@@ -231,29 +238,59 @@ xfs_attr_set_args(
 		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.
+	 * 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.
+	 * 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.
 	 */
-		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;
+}
+
+/*
+ * Set the attribute specified in @args.
+ */
+int
+xfs_attr_set_args(
+	struct xfs_da_args	*args)
+{
+	struct xfs_inode	*dp = args->dp;
+	struct xfs_buf          *leaf_bp = NULL;
+	int			error = 0;
+
+	/*
+	 * If the attribute list is already in leaf format, jump straight to
+	 * leaf handling.  Otherwise, try to add the attribute to the shortform
+	 * list; if there's no room then convert the list to leaf format and try
+	 * 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)
+			return error;
 	}
 
 	if (xfs_bmap_one_block(dp, XFS_ATTR_FORK)) {