Btrfs: Fix split_leaf to detect when it is extending an item
When making room for a new item, it is ok to create an empty leaf, but
when making room to extend an item, split_leaf needs to make sure it
keeps the item we're extending in the path and make sure we don't end up
with an empty leaf.
Signed-off-by: Chris Mason <chris.mason@oracle.com>
diff --git a/fs/btrfs/ctree.c b/fs/btrfs/ctree.c
index 53e40b5..3eb5a9f 100644
--- a/fs/btrfs/ctree.c
+++ b/fs/btrfs/ctree.c
@@ -26,7 +26,7 @@
*root, struct btrfs_path *path, int level);
static int split_leaf(struct btrfs_trans_handle *trans, struct btrfs_root
*root, struct btrfs_key *ins_key,
- struct btrfs_path *path, int data_size);
+ struct btrfs_path *path, int data_size, int extend);
static int push_node_left(struct btrfs_trans_handle *trans,
struct btrfs_root *root, struct extent_buffer *dst,
struct extent_buffer *src);
@@ -1049,7 +1049,7 @@
if (ins_len > 0 && btrfs_leaf_free_space(root, b) <
sizeof(struct btrfs_item) + ins_len) {
int sret = split_leaf(trans, root, key,
- p, ins_len);
+ p, ins_len, ret == 0);
BUG_ON(sret > 0);
if (sret)
return sret;
@@ -1755,7 +1755,7 @@
*/
static int split_leaf(struct btrfs_trans_handle *trans, struct btrfs_root
*root, struct btrfs_key *ins_key,
- struct btrfs_path *path, int data_size)
+ struct btrfs_path *path, int data_size, int extend)
{
struct extent_buffer *l;
u32 nritems;
@@ -1768,9 +1768,13 @@
int i;
int ret = 0;
int wret;
- int double_split = 0;
+ int double_split;
+ int num_doubles = 0;
struct btrfs_disk_key disk_key;
+ if (extend)
+ space_needed = data_size;
+
/* first try to make some room by pushing left and right */
if (ins_key->type != BTRFS_DIR_ITEM_KEY) {
wret = push_leaf_right(trans, root, path, data_size);
@@ -1785,12 +1789,8 @@
l = path->nodes[0];
/* did the pushes work? */
- if (btrfs_leaf_free_space(root, l) >=
- sizeof(struct btrfs_item) + data_size) {
+ if (btrfs_leaf_free_space(root, l) >= space_needed)
return 0;
- }
- } else {
- l = path->nodes[0];
}
if (!path->nodes[1]) {
@@ -1798,6 +1798,9 @@
if (ret)
return ret;
}
+again:
+ double_split = 0;
+ l = path->nodes[0];
slot = path->slots[0];
nritems = btrfs_header_nritems(l);
mid = (nritems + 1)/ 2;
@@ -1815,7 +1818,6 @@
write_extent_buffer(right, root->fs_info->fsid,
(unsigned long)btrfs_header_fsid(right),
BTRFS_FSID_SIZE);
-
if (mid <= slot) {
if (nritems == 1 ||
leaf_space_used(l, mid, nritems - mid) + space_needed >
@@ -1844,7 +1846,7 @@
} else {
if (leaf_space_used(l, 0, mid + 1) + space_needed >
BTRFS_LEAF_DATA_SIZE(root)) {
- if (slot == 0) {
+ if (!extend && slot == 0) {
btrfs_cpu_key_to_disk(&disk_key, ins_key);
btrfs_set_header_nritems(right, 0);
wret = insert_ptr(trans, root, path,
@@ -1863,12 +1865,15 @@
ret = wret;
}
return ret;
- }
- mid = slot;
- if (mid != nritems &&
- leaf_space_used(l, mid, nritems - mid) +
- space_needed > BTRFS_LEAF_DATA_SIZE(root)) {
- double_split = 1;
+ } else if (extend && slot == 0) {
+ mid = 1;
+ } else {
+ mid = slot;
+ if (mid != nritems &&
+ leaf_space_used(l, mid, nritems - mid) +
+ space_needed > BTRFS_LEAF_DATA_SIZE(root)) {
+ double_split = 1;
+ }
}
}
}
@@ -1931,39 +1936,11 @@
BUG_ON(path->slots[0] < 0);
- if (!double_split) {
- return ret;
+ if (double_split) {
+ BUG_ON(num_doubles != 0);
+ num_doubles++;
+ goto again;
}
-
- right = btrfs_alloc_free_block(trans, root, root->leafsize,
- l->start, 0);
- if (IS_ERR(right))
- return PTR_ERR(right);
-
- memset_extent_buffer(right, 0, 0, sizeof(struct btrfs_header));
- btrfs_set_header_bytenr(right, right->start);
- btrfs_set_header_generation(right, trans->transid);
- btrfs_set_header_owner(right, root->root_key.objectid);
- btrfs_set_header_level(right, 0);
- write_extent_buffer(right, root->fs_info->fsid,
- (unsigned long)btrfs_header_fsid(right),
- BTRFS_FSID_SIZE);
-
- btrfs_cpu_key_to_disk(&disk_key, ins_key);
- btrfs_set_header_nritems(right, 0);
- wret = insert_ptr(trans, root, path,
- &disk_key, right->start,
- path->slots[1], 1);
- if (wret)
- ret = wret;
- if (path->slots[1] == 0) {
- wret = fixup_low_keys(trans, root, path, &disk_key, 1);
- if (wret)
- ret = wret;
- }
- free_extent_buffer(path->nodes[0]);
- path->nodes[0] = right;
- path->slots[0] = 0;
return ret;
}
@@ -1992,8 +1969,7 @@
slot = path->slots[0];
old_data_start = btrfs_item_offset_nr(leaf, slot);
- old_size = btrfs_item_size_nr(leaf, slot);
- BUG_ON(old_size <= new_size);
+ old_size = btrfs_item_size_nr(leaf, slot); BUG_ON(old_size <= new_size);
size_diff = old_size - new_size;
BUG_ON(slot < 0);