Btrfs: Fix balance_level to free the middle block if there is room in the left one
balance level starts by trying to empty the middle block, and then
pushes from the right to the middle. This might empty the right block
and leave a small number of pointers in the middle.
Signed-off-by: Chris Mason <chris.mason@oracle.com>
diff --git a/fs/btrfs/ctree.c b/fs/btrfs/ctree.c
index 319f9f9..29e5674 100644
--- a/fs/btrfs/ctree.c
+++ b/fs/btrfs/ctree.c
@@ -789,7 +789,7 @@
/* first, try to make some room in the middle buffer */
if (left) {
orig_slot += btrfs_header_nritems(left);
- wret = push_node_left(trans, root, left, mid, 0);
+ wret = push_node_left(trans, root, left, mid, 1);
if (wret < 0)
ret = wret;
if (btrfs_header_nritems(mid) < 2)
@@ -844,6 +844,11 @@
ret = wret;
goto enospc;
}
+ if (wret == 1) {
+ wret = push_node_left(trans, root, left, mid, 1);
+ if (wret < 0)
+ ret = wret;
+ }
BUG_ON(wret == 1);
}
if (btrfs_header_nritems(mid) == 0) {
@@ -1252,17 +1257,27 @@
WARN_ON(btrfs_header_generation(src) != trans->transid);
WARN_ON(btrfs_header_generation(dst) != trans->transid);
- if (!empty && src_nritems <= 2)
+ if (!empty && src_nritems <= 8)
return 1;
if (push_items <= 0) {
return 1;
}
- if (empty)
+ if (empty) {
push_items = min(src_nritems, push_items);
- else
- push_items = min(src_nritems - 2, push_items);
+ if (push_items < src_nritems) {
+ /* leave at least 8 pointers in the node if
+ * we aren't going to empty it
+ */
+ if (src_nritems - push_items < 8) {
+ if (push_items <= 8)
+ return 1;
+ push_items -= 8;
+ }
+ }
+ } else
+ push_items = min(src_nritems - 8, push_items);
copy_extent_buffer(dst, src,
btrfs_node_key_ptr_offset(dst_nritems),
@@ -1308,13 +1323,19 @@
src_nritems = btrfs_header_nritems(src);
dst_nritems = btrfs_header_nritems(dst);
push_items = BTRFS_NODEPTRS_PER_BLOCK(root) - dst_nritems;
- if (push_items <= 0)
+ if (push_items <= 0) {
return 1;
+ }
+
+ if (src_nritems < 4) {
+ return 1;
+ }
max_push = src_nritems / 2 + 1;
/* don't try to empty the node */
- if (max_push >= src_nritems)
+ if (max_push >= src_nritems) {
return 1;
+ }
if (max_push < push_items)
push_items = max_push;