Commit 9afc6649 authored by Qu Wenruo's avatar Qu Wenruo Committed by David Sterba
Browse files

btrfs: block-group: refactor how we read one block group item 



Structure btrfs_block_group has the following members which are
currently read from on-disk block group item and key:

- length - from item key
- used
- flags - from block group item

However for incoming skinny block group tree, we are going to read those
members from different sources.

This patch will refactor such read by:

- Don't initialize btrfs_block_group::length at allocation
  Caller should initialize them manually.
  Also to avoid possible (well, only two callers) missing
  initialization, add extra ASSERT() in btrfs_add_block_group_cache().

- Refactor length/used/flags initialization into one function
  The new function, fill_one_block_group() will handle the
  initialization of such members.

- Use btrfs_block_group::length to replace key::offset
  Since skinny block group item would have a different meaning for its
  key offset.

Signed-off-by: default avatarQu Wenruo <wqu@suse.com>
Reviewed-by: default avatarDavid Sterba <dsterba@suse.com>
Signed-off-by: default avatarDavid Sterba <dsterba@suse.com>
parent 83fe9e12

fs/btrfs/block-group.c

+32 −15
Original line number Diff line number Diff line
@@ -161,6 +161,8 @@ static int btrfs_add_block_group_cache(struct btrfs_fs_info *info, 
	struct rb_node *parent = NULL;

	struct btrfs_block_group *cache;



	ASSERT(block_group->length != 0);



	spin_lock(&info->block_group_cache_lock);

	p = &info->block_group_cache_tree.rb_node;
@@ -1771,7 +1773,7 @@ static void link_block_group(struct btrfs_block_group *cache) 
}



static struct btrfs_block_group *btrfs_create_block_group_cache(

		struct btrfs_fs_info *fs_info, u64 start, u64 size)

		struct btrfs_fs_info *fs_info, u64 start)

{

	struct btrfs_block_group *cache;
@@ -1787,7 +1789,6 @@ static struct btrfs_block_group *btrfs_create_block_group_cache( 
	}



	cache->start = start;

	cache->length = size;



	cache->fs_info = fs_info;

	cache->full_stripe_len = btrfs_full_stripe_len(fs_info, start);
@@ -1867,25 +1868,44 @@ static int check_chunk_block_group_mappings(struct btrfs_fs_info *fs_info) 
	return ret;

}



static int read_block_group_item(struct btrfs_block_group *cache,

				 struct btrfs_path *path,

				 const struct btrfs_key *key)

{

	struct extent_buffer *leaf = path->nodes[0];

	struct btrfs_block_group_item bgi;

	int slot = path->slots[0];



	cache->length = key->offset;



	read_extent_buffer(leaf, &bgi, btrfs_item_ptr_offset(leaf, slot),

			   sizeof(bgi));

	cache->used = btrfs_stack_block_group_used(&bgi);

	cache->flags = btrfs_stack_block_group_flags(&bgi);



	return 0;

}



static int read_one_block_group(struct btrfs_fs_info *info,

				struct btrfs_path *path,

				const struct btrfs_key *key,

				int need_clear)

{

	struct extent_buffer *leaf = path->nodes[0];

	struct btrfs_block_group *cache;

	struct btrfs_space_info *space_info;

	struct btrfs_block_group_item bgi;

	const bool mixed = btrfs_fs_incompat(info, MIXED_GROUPS);

	int slot = path->slots[0];

	int ret;



	ASSERT(key->type == BTRFS_BLOCK_GROUP_ITEM_KEY);



	cache = btrfs_create_block_group_cache(info, key->objectid, key->offset);

	cache = btrfs_create_block_group_cache(info, key->objectid);

	if (!cache)

		return -ENOMEM;



	ret = read_block_group_item(cache, path, key);

	if (ret < 0)

		goto error;



	if (need_clear) {

		/*

		 * When we mount with old space cache, we need to
@@ -1900,10 +1920,6 @@ static int read_one_block_group(struct btrfs_fs_info *info, 
		if (btrfs_test_opt(info, SPACE_CACHE))

			cache->disk_cache_state = BTRFS_DC_CLEAR;

	}

	read_extent_buffer(leaf, &bgi, btrfs_item_ptr_offset(leaf, slot),

			   sizeof(bgi));

	cache->used = btrfs_stack_block_group_used(&bgi);

	cache->flags = btrfs_stack_block_group_flags(&bgi);

	if (!mixed && ((cache->flags & BTRFS_BLOCK_GROUP_METADATA) &&

	    (cache->flags & BTRFS_BLOCK_GROUP_DATA))) {

			btrfs_err(info,
@@ -1931,15 +1947,15 @@ static int read_one_block_group(struct btrfs_fs_info *info, 
	 * are empty, and we can just add all the space in and be done with it.

	 * This saves us _a_lot_ of time, particularly in the full case.

	 */

	if (key->offset == cache->used) {

	if (cache->length == cache->used) {

		cache->last_byte_to_unpin = (u64)-1;

		cache->cached = BTRFS_CACHE_FINISHED;

		btrfs_free_excluded_extents(cache);

	} else if (cache->used == 0) {

		cache->last_byte_to_unpin = (u64)-1;

		cache->cached = BTRFS_CACHE_FINISHED;

		add_new_free_space(cache, key->objectid,

				   key->objectid + key->offset);

		add_new_free_space(cache, cache->start,

				   cache->start + cache->length);

		btrfs_free_excluded_extents(cache);

	}
@@ -1949,7 +1965,7 @@ static int read_one_block_group(struct btrfs_fs_info *info, 
		goto error;

	}

	trace_btrfs_add_block_group(info, cache, 0);

	btrfs_update_space_info(info, cache->flags, key->offset,

	btrfs_update_space_info(info, cache->flags, cache->length,

				cache->used, cache->bytes_super, &space_info);



	cache->space_info = space_info;
@@ -2096,10 +2112,11 @@ int btrfs_make_block_group(struct btrfs_trans_handle *trans, u64 bytes_used, 


	btrfs_set_log_full_commit(trans);



	cache = btrfs_create_block_group_cache(fs_info, chunk_offset, size);

	cache = btrfs_create_block_group_cache(fs_info, chunk_offset);

	if (!cache)

		return -ENOMEM;



	cache->length = size;

	cache->used = bytes_used;

	cache->flags = type;

	cache->last_byte_to_unpin = (u64)-1;

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