-chris
diff --git a/fs/btrfs/ctree.c b/fs/btrfs/ctree.c
index 0d1d966..1f393b0 100644
--- a/fs/btrfs/ctree.c
+++ b/fs/btrfs/ctree.c
@@ -2304,12 +2304,17 @@ noinline int btrfs_leaf_free_space(struct btrfs_root *root,
return ret;
}
+/*
+ * min slot controls the lowest index we're willing to push to the
+ * right. We'll push up to and including min_slot, but no lower
+ */
static noinline int __push_leaf_right(struct btrfs_trans_handle *trans,
struct btrfs_root *root,
struct btrfs_path *path,
int data_size, int empty,
struct extent_buffer *right,
- int free_space, u32 left_nritems)
+ int free_space, u32 left_nritems,
+ u32 min_slot)
{
struct extent_buffer *left = path->nodes[0];
struct extent_buffer *upper = path->nodes[1];
@@ -2327,7 +2332,7 @@ static noinline int __push_leaf_right(struct btrfs_trans_handle *trans,
if (empty)
nr = 0;
else
- nr = 1;
+ nr = max_t(u32, 1, min_slot);
if (path->slots[0] >= left_nritems)
push_space += data_size;
@@ -2469,10 +2474,13 @@ out_unlock:
*
* returns 1 if the push failed because the other node didn't have enough
* room, 0 if everything worked out and < 0 if there were major errors.
+ *
+ * this will push starting from min_slot to the end of the leaf. It won't
+ * push any slot lower than min_slot
*/
static int push_leaf_right(struct btrfs_trans_handle *trans, struct btrfs_root
*root, struct btrfs_path *path, int data_size,
- int empty)
+ int empty, u32 min_slot)
{
struct extent_buffer *left = path->nodes[0];
struct extent_buffer *right;
@@ -2515,7 +2523,7 @@ static int push_leaf_right(struct btrfs_trans_handle *trans, struct btrfs_root
goto out_unlock;
return __push_leaf_right(trans, root, path, data_size, empty,
- right, free_space, left_nritems);
+ right, free_space, left_nritems, min_slot);
out_unlock:
btrfs_tree_unlock(right);
free_extent_buffer(right);
@@ -2525,12 +2533,17 @@ out_unlock:
/*
* push some data in the path leaf to the left, trying to free up at
* least data_size bytes. returns zero if the push worked, nonzero otherwise
+ *
+ * max_slot can put a limit on how far into the leaf we'll push items. The
+ * item at 'max_slot' won't be touched. Use (u32)-1 to make us do all the
+ * items
*/
static noinline int __push_leaf_left(struct btrfs_trans_handle *trans,
struct btrfs_root *root,
struct btrfs_path *path, int data_size,
int empty, struct extent_buffer *left,
- int free_space, int right_nritems)
+ int free_space, u32 right_nritems,
+ u32 max_slot)
{
struct btrfs_disk_key disk_key;
struct extent_buffer *right = path->nodes[0];
@@ -2549,9 +2562,9 @@ static noinline int __push_leaf_left(struct btrfs_trans_handle *trans,
slot = path->slots[1];
if (empty)
- nr = right_nritems;
+ nr = min(right_nritems, max_slot);
else
- nr = right_nritems - 1;
+ nr = min(right_nritems - 1, max_slot);
for (i = 0; i < nr; i++) {
item = btrfs_item_nr(right, i);
@@ -2712,10 +2725,14 @@ out:
/*
* push some data in the path leaf to the left, trying to free up at
* least data_size bytes. returns zero if the push worked, nonzero otherwise
+ *
+ * max_slot can put a limit on how far into the leaf we'll push items. The
+ * item at 'max_slot' won't be touched. Use (u32)-1 to make us push all the
+ * items
*/
static int push_leaf_left(struct btrfs_trans_handle *trans, struct btrfs_root
*root, struct btrfs_path *path, int data_size,
- int empty)
+ int empty, u32 max_slot)
{
struct extent_buffer *right = path->nodes[0];
struct extent_buffer *left;
@@ -2762,7 +2779,8 @@ static int push_leaf_left(struct btrfs_trans_handle *trans, struct btrfs_root
}
return __push_leaf_left(trans, root, path, data_size,
- empty, left, free_space, right_nritems);
+ empty, left, free_space, right_nritems,
+ max_slot);
out:
btrfs_tree_unlock(left);
free_extent_buffer(left);
@@ -2855,6 +2873,59 @@ static noinline int copy_for_split(struct btrfs_trans_handle *trans,
}
/*
+ * double splits happen when we need to insert a big item in the middle
+ * of a leaf. A double split can leave us with 3 mostly empty leaves:
+ * leaf: [ slots 0 - N] [ our target ] [ N + 1 - total in leaf ]
+ * A B C
+ *
+ * We avoid this by trying to push the items on either side of our target
+ * into the adjacent leaves. If all goes well we can avoid the double split
+ * completely.
+ */
+static noinline int push_for_double_split(struct btrfs_trans_handle *trans,
+ struct btrfs_root *root,
+ struct btrfs_path *path)
+{
+ int ret;
+ int progress = 0;
+ int slot;
+
+ slot = path->slots[0];
+
+ /*
+ * try to push all the items after our slot into the
+ * right leaf
+ */
+ ret = push_leaf_right(trans, root, path, 1, 0, slot);
+ if (ret < 0)
+ return ret;
+
+ if (ret == 0)
+ progress++;
+
+ /*
+ * our goal is to get our slot at the start or end of a leaf. If
+ * we've done so we're done
+ */
+ if (path->slots[0] == 0 ||
+ path->slots[0] == btrfs_header_nritems(path->nodes[0]))
+ return 0;
+
+ /* try to push all the items before our slot into the next leaf */
+ slot = path->slots[0];
+ ret = push_leaf_left(trans, root, path, 1, 0, slot);
+ if (ret < 0)
+ return ret;
+
+ if (ret == 0)
+ progress++;
+
+ if (progress)
+ return 0;
+ return 1;
+}
+
+/*
* split the path's leaf in two, making sure there is at least data_size
* available for the resulting leaf level of the path.
*
@@ -2876,6 +2947,7 @@ static noinline int split_leaf(struct btrfs_trans_handle *trans,
int wret;
int split;
int num_doubles = 0;
+ int tried_avoid_double = 0;
l = path->nodes[0];
slot = path->slots[0];
@@ -2884,12 +2956,13 @@ static noinline int split_leaf(struct btrfs_trans_handle *trans,
return -EOVERFLOW;
/* first try to make some room by pushing left and right */
- if (data_size && ins_key->type != BTRFS_DIR_ITEM_KEY) {
- wret = push_leaf_right(trans, root, path, data_size, 0);
+ if (data_size) {
+ wret = push_leaf_right(trans, root, path, data_size, 0, 0);
if (wret < 0)
return wret;
if (wret) {
- wret = push_leaf_left(trans, root, path, data_size, 0);
+ wret = push_leaf_left(trans, root, path,
+ data_size, 0, (u32)-1);
if (wret < 0)
return wret;
}
@@ -2923,6 +2996,12 @@ again:
if (mid != nritems &&
leaf_space_used(l, mid, nritems - mid) +
data_size > BTRFS_LEAF_DATA_SIZE(root)) {
+ if (!tried_avoid_double) {
+ push_for_double_split(trans,
+ root, path);
+ tried_avoid_double = 1;
+ goto again;
+ }
split = 2;
}
}
@@ -2939,6 +3018,12 @@ again:
if (mid != nritems &&
leaf_space_used(l, mid, nritems - mid) +
data_size > BTRFS_LEAF_DATA_SIZE(root)) {
+ if (!tried_avoid_double) {
+ push_for_double_split(trans,
+ root, path);
+ tried_avoid_double = 1;
+ goto again;
+ }
split = 2 ;
}
}
@@ -3915,13 +4000,14 @@ int btrfs_del_items(struct btrfs_trans_handle *trans, struct btrfs_root *root,
extent_buffer_get(leaf);
btrfs_set_path_blocking(path);
- wret = push_leaf_left(trans, root, path, 1, 1);
+ wret = push_leaf_left(trans, root, path, 1, 1, (u32)-1);
if (wret < 0 && wret != -ENOSPC)
ret = wret;
if (path->nodes[0] == leaf &&
btrfs_header_nritems(leaf)) {
- wret = push_leaf_right(trans, root, path, 1, 1);
+ wret = push_leaf_right(trans, root, path,
+ 1, 1, 0);
if (wret < 0 && wret != -ENOSPC)
ret = wret;
}
