xfs: handle zero entries case in xfs_iext_rebalance_leaf

And also rename fill to nr_entries to match the rest of the code.

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>

1 files changed, 17 insertions, 7 deletions

diff --git a/fs/xfs/libxfs/xfs_iext_tree.c b/fs/xfs/libxfs/xfs_iext_tree.c
index 81e0480822d8..343a94246f5b 100644
--- a/fs/xfs/libxfs/xfs_iext_tree.c
+++ b/fs/xfs/libxfs/xfs_iext_tree.c
@@ -787,13 +787,21 @@ xfs_iext_rebalance_leaf(
         struct xfs_iext_cursor  *cur,
         struct xfs_iext_leaf    *leaf,
         xfs_fileoff_t           offset,
-        int                     fill)
+        int                     nr_entries)
 {
+        /*
+         * If the neighbouring nodes are completely full 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)
+                goto remove_node;
+
         if (leaf->prev) {
                 int nr_prev = xfs_iext_leaf_nr_entries(ifp, leaf->prev, 0), i;
 
-                if (nr_prev + fill <= RECS_PER_LEAF) {
-                        for (i = 0; i < fill; i++)
+                if (nr_prev + nr_entries <= RECS_PER_LEAF) {
+                        for (i = 0; i < nr_entries; i++)
                                 leaf->prev->recs[nr_prev + i] = leaf->recs[i];
 
                         if (cur->leaf == leaf) {
@@ -807,18 +815,20 @@ xfs_iext_rebalance_leaf(
         if (leaf->next) {
                 int nr_next = xfs_iext_leaf_nr_entries(ifp, leaf->next, 0), i;
 
-                if (fill + nr_next <= RECS_PER_LEAF) {
+                if (nr_entries + 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];
+                        for (i = 0; i < nr_next; i++) {
+                                leaf->recs[nr_entries + i] =
+                                        leaf->next->recs[i];
+                        }
 
                         if (cur->leaf == leaf->next) {
                                 cur->leaf = leaf;
-                                cur->pos += fill;
+                                cur->pos += nr_entries;
                         }
 
                         offset = xfs_iext_leaf_key(leaf->next, 0);