Btrfs: Fixup the code to merge during path walks
Add a bulk insert/remove test to random-test
Add the quick-test code back as another regression test
Signed-off-by: Chris Mason <chris.mason@oracle.com>
diff --git a/fs/btrfs/ctree.c b/fs/btrfs/ctree.c
index df4a19d..afa5bc5 100644
--- a/fs/btrfs/ctree.c
+++ b/fs/btrfs/ctree.c
@@ -12,6 +12,9 @@
int data_size);
static int push_node_left(struct ctree_root *root, struct tree_buffer *dst,
struct tree_buffer *src);
+static int balance_node_right(struct ctree_root *root,
+ struct tree_buffer *dst_buf,
+ struct tree_buffer *src_buf);
static int del_ptr(struct ctree_root *root, struct ctree_path *path, int level,
int slot);
@@ -217,15 +220,16 @@
int ret = 0;
int wret;
int pslot;
- int used = 0;
- int count;
int orig_slot = path->slots[level];
+ u64 orig_ptr;
if (level == 0)
return 0;
mid_buf = path->nodes[level];
mid = &mid_buf->node;
+ orig_ptr = mid->blockptrs[orig_slot];
+
if (level < MAX_LEVEL - 1)
parent_buf = path->nodes[level + 1];
pslot = path->slots[level + 1];
@@ -253,24 +257,26 @@
if (mid->header.nritems > NODEPTRS_PER_BLOCK / 4)
return 0;
- // print_tree(root, root->node);
left_buf = read_node_slot(root, parent_buf, pslot - 1);
right_buf = read_node_slot(root, parent_buf, pslot + 1);
- if (right_buf) {
- right = &right_buf->node;
- used = right->header.nritems;
- count = 1;
- }
+
+ /* first, try to make some room in the middle buffer */
if (left_buf) {
left = &left_buf->node;
- used += left->header.nritems;
orig_slot += left->header.nritems;
- count++;
+ wret = push_node_left(root, left_buf, mid_buf);
+ if (wret < 0)
+ ret = wret;
}
- if (left_buf)
- push_node_left(root, left_buf, mid_buf);
+
+ /*
+ * then try to empty the right most buffer into the middle
+ */
if (right_buf) {
- push_node_left(root, mid_buf, right_buf);
+ right = &right_buf->node;
+ wret = push_node_left(root, mid_buf, right_buf);
+ if (wret < 0)
+ ret = wret;
if (right->header.nritems == 0) {
u64 blocknr = right_buf->blocknr;
tree_block_release(root, right_buf);
@@ -285,9 +291,29 @@
} else {
memcpy(parent->keys + pslot + 1, right->keys,
sizeof(struct key));
+ wret = write_tree_block(root, parent_buf);
+ if (wret)
+ ret = wret;
}
}
+ if (mid->header.nritems == 1) {
+ /*
+ * we're not allowed to leave a node with one item in the
+ * tree during a delete. A deletion from lower in the tree
+ * could try to delete the only pointer in this node.
+ * So, pull some keys from the left.
+ * There has to be a left pointer at this point because
+ * otherwise we would have pulled some pointers from the
+ * right
+ */
+ BUG_ON(!left_buf);
+ wret = balance_node_right(root, mid_buf, left_buf);
+ if (wret < 0)
+ ret = wret;
+ BUG_ON(wret == 1);
+ }
if (mid->header.nritems == 0) {
+ /* we've managed to empty the middle node, drop it */
u64 blocknr = mid_buf->blocknr;
tree_block_release(root, mid_buf);
mid_buf = NULL;
@@ -298,11 +324,17 @@
wret = free_extent(root, blocknr, 1);
if (wret)
ret = wret;
- } else
+ } else {
+ /* update the parent key to reflect our changes */
memcpy(parent->keys + pslot, mid->keys, sizeof(struct key));
+ wret = write_tree_block(root, parent_buf);
+ if (wret)
+ ret = wret;
+ }
+ /* update the path */
if (left_buf) {
- if (left->header.nritems >= orig_slot) {
+ if (left->header.nritems > orig_slot) {
left_buf->count++; // released below
path->nodes[level] = left_buf;
path->slots[level + 1] -= 1;
@@ -314,12 +346,15 @@
path->slots[level] = orig_slot;
}
}
+ /* double check we haven't messed things up */
+ check_block(path, level);
+ if (orig_ptr != path->nodes[level]->node.blockptrs[path->slots[level]])
+ BUG();
if (right_buf)
tree_block_release(root, right_buf);
if (left_buf)
tree_block_release(root, left_buf);
-
return ret;
}
@@ -378,6 +413,7 @@
goto again;
c = &b->node;
slot = p->slots[level];
+ BUG_ON(c->header.nritems == 1);
}
b = read_tree_block(root, c->blockptrs[slot]);
} else {
@@ -433,13 +469,7 @@
/*
* try to push data from one node into the next node left in the
- * tree. The src node is found at specified level in the path.
- * If some bytes were pushed, return 0, otherwise return 1.
- *
- * Lower nodes/leaves in the path are not touched, higher nodes may
- * be modified to reflect the push.
- *
- * The path is altered to reflect the push.
+ * tree.
*
* returns 0 if some ptrs were pushed left, < 0 if there was some horrible
* error, and > 0 if there was no room in the left hand block.
@@ -463,7 +493,8 @@
}
if (src_nritems < push_items)
- push_items =src_nritems;
+ push_items = src_nritems;
+
memcpy(dst->keys + dst_nritems, src->keys,
push_items * sizeof(struct key));
memcpy(dst->blockptrs + dst_nritems, src->blockptrs,
@@ -488,6 +519,64 @@
}
/*
+ * try to push data from one node into the next node right in the
+ * tree.
+ *
+ * returns 0 if some ptrs were pushed, < 0 if there was some horrible
+ * error, and > 0 if there was no room in the right hand block.
+ *
+ * this will only push up to 1/2 the contents of the left node over
+ */
+static int balance_node_right(struct ctree_root *root,
+ struct tree_buffer *dst_buf,
+ struct tree_buffer *src_buf)
+{
+ struct node *src = &src_buf->node;
+ struct node *dst = &dst_buf->node;
+ int push_items = 0;
+ int max_push;
+ int src_nritems;
+ int dst_nritems;
+ int ret = 0;
+ int wret;
+
+ src_nritems = src->header.nritems;
+ dst_nritems = dst->header.nritems;
+ push_items = NODEPTRS_PER_BLOCK - dst_nritems;
+ if (push_items <= 0) {
+ return 1;
+ }
+
+ max_push = src_nritems / 2 + 1;
+ /* don't try to empty the node */
+ if (max_push > src_nritems)
+ return 1;
+ if (max_push < push_items)
+ push_items = max_push;
+
+ memmove(dst->keys + push_items, dst->keys,
+ dst_nritems * sizeof(struct key));
+ memmove(dst->blockptrs + push_items, dst->blockptrs,
+ dst_nritems * sizeof(u64));
+ memcpy(dst->keys, src->keys + src_nritems - push_items,
+ push_items * sizeof(struct key));
+ memcpy(dst->blockptrs, src->blockptrs + src_nritems - push_items,
+ push_items * sizeof(u64));
+
+ src->header.nritems -= push_items;
+ dst->header.nritems += push_items;
+
+ wret = write_tree_block(root, src_buf);
+ if (wret < 0)
+ ret = wret;
+
+ wret = write_tree_block(root, dst_buf);
+ if (wret < 0)
+ ret = wret;
+ return ret;
+}
+
+/*
* helper function to insert a new root level in the tree.
* A new node is allocated, and a single item is inserted to
* point to the existing root
