Commit cc0c5538 authored by Chris Mason's avatar Chris Mason
Browse files

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: default avatarChris Mason <chris.mason@oracle.com>
parent 65555a06

fs/btrfs/ctree.c

+27 −51
Original line number Diff line number Diff line
@@ -26,7 +26,7 @@ static int split_node(struct btrfs_trans_handle *trans, struct btrfs_root 
		      *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 @@ int btrfs_search_slot(struct btrfs_trans_handle *trans, struct btrfs_root 
			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 push_leaf_left(struct btrfs_trans_handle *trans, struct btrfs_root 
 */

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 @@ static int split_leaf(struct btrfs_trans_handle *trans, struct btrfs_root 
	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);
@@ -1785,19 +1789,18 @@ static int split_leaf(struct btrfs_trans_handle *trans, struct btrfs_root 
		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]) {

		ret = insert_new_root(trans, root, path, 1);

		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 @@ static int split_leaf(struct btrfs_trans_handle *trans, struct btrfs_root 
	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 @@ static int split_leaf(struct btrfs_trans_handle *trans, struct btrfs_root 
	} 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,
@@ -1863,7 +1865,9 @@ static int split_leaf(struct btrfs_trans_handle *trans, struct btrfs_root 
						ret = wret;

				}

				return ret;

			}

			} else if (extend && slot == 0) {

				mid = 1;

			} else {

				mid = slot;

				if (mid != nritems &&

				    leaf_space_used(l, mid, nritems - mid) +
@@ -1872,6 +1876,7 @@ static int split_leaf(struct btrfs_trans_handle *trans, struct btrfs_root 
				}

			}

		}

	}

	nritems = nritems - mid;

	btrfs_set_header_nritems(right, nritems);

	data_copy_size = btrfs_item_end_nr(l, mid) - leaf_data_end(root, l);
@@ -1931,39 +1936,11 @@ static int split_leaf(struct btrfs_trans_handle *trans, struct btrfs_root 


	BUG_ON(path->slots[0] < 0);



	if (!double_split) {

		return ret;

	}



	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;

	if (double_split) {

		BUG_ON(num_doubles != 0);

		num_doubles++;

		goto again;

	}

	free_extent_buffer(path->nodes[0]);

	path->nodes[0] = right;

	path->slots[0] = 0;

	return ret;

}
@@ -1992,8 +1969,7 @@ int btrfs_truncate_item(struct btrfs_trans_handle *trans, 


	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);