Reported-by: Brian Foster <bfoster@xxxxxxxxxx>
Signed-off-by: Christoph Hellwig <hch@xxxxxx>
---
fs/xfs/libxfs/xfs_iext_tree.c | 24 ++++++++++++++++++++++++
1 file changed, 24 insertions(+)
diff --git a/fs/xfs/libxfs/xfs_iext_tree.c b/fs/xfs/libxfs/xfs_iext_tree.c
index 3974989b0929..81e0480822d8 100644
--- a/fs/xfs/libxfs/xfs_iext_tree.c
+++ b/fs/xfs/libxfs/xfs_iext_tree.c
@@ -672,6 +672,11 @@ xfs_iext_rebalance_node(
struct xfs_iext_node *node,
int nr_entries)
{
+ /*
+ * If the neighbouring nodes are completely full, or have different
+ * parents, we might never be able to merge our node, and will only
+ * delete it once the number of entries hits zero.
+ */
if (nr_entries == 0)
return node;
@@ -693,6 +698,11 @@ xfs_iext_rebalance_node(
int nr_next = xfs_iext_node_nr_entries(next, 0), i;
if (nr_entries + nr_next <= KEYS_PER_NODE) {
+ /*
+ * Merge the next node into this node so that we don't
+ * have to do an additional update of the keys in the
+ * higher levels.
+ */
for (i = 0; i < nr_next; i++) {
node->keys[nr_entries + i] = next->keys[i];
node->ptrs[nr_entries + i] = next->ptrs[i];
@@ -741,6 +751,11 @@ xfs_iext_remove_node(
return;
if (level < ifp->if_height) {
+ /*
+ * If we aren't at the root yet try to find a neighbour node to
+ * merge with (or delete the node if it is empty), and then
+ * recurse up to the next level.
+ */
level++;
parent = xfs_iext_find_level(ifp, offset, level);
pos = xfs_iext_node_pos(parent, offset);
@@ -755,6 +770,10 @@ xfs_iext_remove_node(
goto again;
}
} else if (nr_entries == 1) {
+ /*
+ * If we are at the root and only one entry is left we can just
+ * free this node and update the root pointer.
+ */
ASSERT(node == ifp->if_u1.if_root);
ifp->if_u1.if_root = node->ptrs[0];
ifp->if_height--;
@@ -789,6 +808,11 @@ xfs_iext_rebalance_leaf(
int nr_next = xfs_iext_leaf_nr_entries(ifp, leaf->next, 0), i;
if (fill + nr_next <= RECS_PER_LEAF) {
+ /*
+ * Merge the next node into this node so that we don't
+ * have to do an additional update of the keys in the
+ * higher levels.
+ */
for (i = 0; i < nr_next; i++)
leaf->recs[fill + i] = leaf->next->recs[i];
--
2.14.2
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