xfs: refactor extended attribute list operation

When we're iterating the attribute list and we can't find our previous
location based off the attribute cursor, we'll instead walk down the
attribute btree from the root trying to find where we left off.  Move
this code into a separate function for later cleanups.
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Brian Foster <bfoster@redhat.com>

fs/xfs/xfs_attr_list.c

@@ -204,19 +204,83 @@ xfs_attr_shortform_list(xfs_attr_list_context_t *context)
 	return 0;
 }
 
+/*
+ * We didn't find the block & hash mentioned in the cursor state, so
+ * walk down the attr btree looking for the hash.
+ */
 STATIC int
-xfs_attr_node_list(xfs_attr_list_context_t *context)
+xfs_attr_node_list_lookup(
+	struct xfs_attr_list_context	*context,
+	struct attrlist_cursor_kern	*cursor,
+	struct xfs_buf			**pbp)
 {
-	attrlist_cursor_kern_t *cursor;
-	xfs_attr_leafblock_t *leaf;
-	xfs_da_intnode_t *node;
-	struct xfs_attr3_icleaf_hdr leafhdr;
-	struct xfs_da3_icnode_hdr nodehdr;
-	struct xfs_da_node_entry *btree;
-	int error, i;
-	struct xfs_buf *bp;
-	struct xfs_inode	*dp = context->dp;
-	struct xfs_mount	*mp = dp->i_mount;
+	struct xfs_da3_icnode_hdr	nodehdr;
+	struct xfs_da_intnode		*node;
+	struct xfs_da_node_entry	*btree;
+	struct xfs_inode		*dp = context->dp;
+	struct xfs_mount		*mp = dp->i_mount;
+	struct xfs_trans		*tp = context->tp;
+	struct xfs_buf			*bp;
+	int				i;
+	int				error = 0;
+	uint16_t			magic;
+
+	ASSERT(*pbp == NULL);
+	cursor->blkno = 0;
+	for (;;) {
+		error = xfs_da3_node_read(tp, dp, cursor->blkno, -1, &bp,
+				XFS_ATTR_FORK);
+		if (error)
+			return error;
+		node = bp->b_addr;
+		magic = be16_to_cpu(node->hdr.info.magic);
+		if (magic == XFS_ATTR_LEAF_MAGIC ||
+		    magic == XFS_ATTR3_LEAF_MAGIC)
+			break;
+		if (magic != XFS_DA_NODE_MAGIC &&
+		    magic != XFS_DA3_NODE_MAGIC) {
+			XFS_CORRUPTION_ERROR(__func__, XFS_ERRLEVEL_LOW, mp,
+					node);
+			goto out_corruptbuf;
+		}
+
+		dp->d_ops->node_hdr_from_disk(&nodehdr, node);
+
+		btree = dp->d_ops->node_tree_p(node);
+		for (i = 0; i < nodehdr.count; btree++, i++) {
+			if (cursor->hashval <= be32_to_cpu(btree->hashval)) {
+				cursor->blkno = be32_to_cpu(btree->before);
+				trace_xfs_attr_list_node_descend(context,
+						btree);
+				break;
+			}
+		}
+		xfs_trans_brelse(tp, bp);
+
+		if (i == nodehdr.count)
+			return 0;
+	}
+
+	*pbp = bp;
+	return 0;
+
+out_corruptbuf:
+	xfs_trans_brelse(tp, bp);
+	return -EFSCORRUPTED;
+}
+
+STATIC int
+xfs_attr_node_list(
+	struct xfs_attr_list_context	*context)
+{
+	struct xfs_attr3_icleaf_hdr	leafhdr;
+	struct attrlist_cursor_kern	*cursor;
+	struct xfs_attr_leafblock	*leaf;
+	struct xfs_da_intnode		*node;
+	struct xfs_buf			*bp;
+	struct xfs_inode		*dp = context->dp;
+	struct xfs_mount		*mp = dp->i_mount;
+	int				error;
 
 	trace_xfs_attr_node_list(context);
 
@@ -277,47 +341,9 @@ xfs_attr_node_list(xfs_attr_list_context_t *context)
 	 * Note that start of node block is same as start of leaf block.
 	 */
 	if (bp == NULL) {
-		cursor->blkno = 0;
-		for (;;) {
-			uint16_t magic;
-
-			error = xfs_da3_node_read(context->tp, dp,
-						      cursor->blkno, -1, &bp,
-						      XFS_ATTR_FORK);
-			if (error)
-				return error;
-			node = bp->b_addr;
-			magic = be16_to_cpu(node->hdr.info.magic);
-			if (magic == XFS_ATTR_LEAF_MAGIC ||
-			    magic == XFS_ATTR3_LEAF_MAGIC)
-				break;
-			if (magic != XFS_DA_NODE_MAGIC &&
-			    magic != XFS_DA3_NODE_MAGIC) {
-				XFS_CORRUPTION_ERROR("xfs_attr_node_list(3)",
-						     XFS_ERRLEVEL_LOW,
-						     context->dp->i_mount,
-						     node);
-				xfs_trans_brelse(context->tp, bp);
-				return -EFSCORRUPTED;
-			}
-
-			dp->d_ops->node_hdr_from_disk(&nodehdr, node);
-			btree = dp->d_ops->node_tree_p(node);
-			for (i = 0; i < nodehdr.count; btree++, i++) {
-				if (cursor->hashval
-						<= be32_to_cpu(btree->hashval)) {
-					cursor->blkno = be32_to_cpu(btree->before);
-					trace_xfs_attr_list_node_descend(context,
-									 btree);
-					break;
-				}
-			}
-			if (i == nodehdr.count) {
-				xfs_trans_brelse(context->tp, bp);
-				return 0;
-			}
-			xfs_trans_brelse(context->tp, bp);
-		}
+		error = xfs_attr_node_list_lookup(context, cursor, &bp);
+		if (error || !bp)
+			return error;
 	}
 	ASSERT(bp != NULL);