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Commit 120d66ee authored by Li Zefan's avatar Li Zefan
Browse files

btrfs: Add a helper try_merge_free_space() 



When adding a new extent, we'll firstly see if we can merge
this extent to the left or/and right extent. Extract this as
a helper try_merge_free_space().

As a side effect, we fix a small bug that if the new extent
has non-bitmap left entry but is unmergeble, we'll directly
link the extent without trying to drop it into bitmap.

This also prepares for the next patch.

Reviewed-by: default avatarJosef Bacik <josef@redhat.com>
Signed-off-by: default avatarLi Zefan <lizf@cn.fujitsu.com>
parent 5e71b5d5

fs/btrfs/free-space-cache.c

+43 −32
Original line number Diff line number Diff line
@@ -1363,22 +1363,14 @@ static int insert_into_bitmap(struct btrfs_block_group_cache *block_group, 
	return ret;

}



int btrfs_add_free_space(struct btrfs_block_group_cache *block_group,

			 u64 offset, u64 bytes)

bool try_merge_free_space(struct btrfs_block_group_cache *block_group,

			  struct btrfs_free_space *info)

{

	struct btrfs_free_space *right_info = NULL;

	struct btrfs_free_space *left_info = NULL;

	struct btrfs_free_space *info = NULL;

	int ret = 0;



	info = kzalloc(sizeof(struct btrfs_free_space), GFP_NOFS);

	if (!info)

		return -ENOMEM;



	info->offset = offset;

	info->bytes = bytes;



	spin_lock(&block_group->tree_lock);

	struct btrfs_free_space *left_info;

	struct btrfs_free_space *right_info;

	bool merged = false;

	u64 offset = info->offset;

	u64 bytes = info->bytes;



	/*

	 * first we want to see if there is free space adjacent to the range we
@@ -1392,27 +1384,11 @@ int btrfs_add_free_space(struct btrfs_block_group_cache *block_group, 
	else

		left_info = tree_search_offset(block_group, offset - 1, 0, 0);



	/*

	 * If there was no extent directly to the left or right of this new

	 * extent then we know we're going to have to allocate a new extent, so

	 * before we do that see if we need to drop this into a bitmap

	 */

	if ((!left_info || left_info->bitmap) &&

	    (!right_info || right_info->bitmap)) {

		ret = insert_into_bitmap(block_group, info);



		if (ret < 0) {

			goto out;

		} else if (ret) {

			ret = 0;

			goto out;

		}

	}



	if (right_info && !right_info->bitmap) {

		unlink_free_space(block_group, right_info);

		info->bytes += right_info->bytes;

		kfree(right_info);

		merged = true;

	}



	if (left_info && !left_info->bitmap &&
@@ -1421,8 +1397,43 @@ int btrfs_add_free_space(struct btrfs_block_group_cache *block_group, 
		info->offset = left_info->offset;

		info->bytes += left_info->bytes;

		kfree(left_info);

		merged = true;

	}



	return merged;

}



int btrfs_add_free_space(struct btrfs_block_group_cache *block_group,

			 u64 offset, u64 bytes)

{

	struct btrfs_free_space *info;

	int ret = 0;



	info = kzalloc(sizeof(struct btrfs_free_space), GFP_NOFS);

	if (!info)

		return -ENOMEM;



	info->offset = offset;

	info->bytes = bytes;



	spin_lock(&block_group->tree_lock);



	if (try_merge_free_space(block_group, info))

		goto link;



	/*

	 * There was no extent directly to the left or right of this new

	 * extent then we know we're going to have to allocate a new extent, so

	 * before we do that see if we need to drop this into a bitmap

	 */

	ret = insert_into_bitmap(block_group, info);

	if (ret < 0) {

		goto out;

	} else if (ret) {

		ret = 0;

		goto out;

	}

link:

	ret = link_free_space(block_group, info);

	if (ret)

		kfree(info);