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

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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: Qu Wenruo <wqu@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
This commit is contained in:
Qu Wenruo 2020-05-05 07:58:20 +08:00 committed by David Sterba
parent 83fe9e12b0
commit 9afc66498a
1 changed files with 32 additions and 15 deletions
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47
fs/btrfs/block-group.c
View file

@ -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;