xfs: add some comments to xfs_iext_insert/xfs_iext_insert_node

Reported-by: Brian Foster <bfoster@redhat.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Brian Foster <bfoster@redhat.com>
Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>

diff --git a/fs/xfs/libxfs/xfs_iext_tree.c b/fs/xfs/libxfs/xfs_iext_tree.c
index 85d7f70..c28a24a 100644 (file)
--- a/fs/xfs/libxfs/xfs_iext_tree.c
+++ b/fs/xfs/libxfs/xfs_iext_tree.c
@@ -525,6 +525,10 @@ again:
        if (nr_entries == KEYS_PER_NODE)
                new = xfs_iext_split_node(&node, &pos, &nr_entries);
 
+       /*
+        * Update the pointers in higher levels if the first entry changes
+        * in an existing node.
+        */
        if (node != new && pos == 0 && nr_entries > 0)
                xfs_iext_update_node(ifp, node->keys[0], offset, level, node);
 
@@ -643,6 +647,10 @@ xfs_iext_insert(
        if (nr_entries == RECS_PER_LEAF)
                new = xfs_iext_split_leaf(cur, &nr_entries);
 
+       /*
+        * Update the pointers in higher levels if the first entry changes
+        * in an existing node.
+        */
        if (cur->leaf != new && cur->pos == 0 && nr_entries > 0) {
                xfs_iext_update_node(ifp, xfs_iext_leaf_key(cur->leaf, 0),
                                offset, 1, cur->leaf);