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btrfs: block-group: Refactor btrfs_read_block_groups()
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Refactor the work inside the loop of btrfs_read_block_groups() into one
separate function, read_one_block_group().

This allows read_one_block_group to be reused for later BG_TREE feature.

The refactor does the following extra fix:
- Use btrfs_fs_incompat() to replace open-coded feature check

Reviewed-by: Johannes Thumshirn <jthumshirn@suse.de>
Reviewed-by: Anand Jain <anand.jain@oracle.com>
Signed-off-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
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Qu Wenruo authored and David Sterba committed Nov 18, 2019
1 parent d4e253b commit ffb9e0f
Showing 1 changed file with 108 additions and 111 deletions.
219 changes: 108 additions & 111 deletions fs/btrfs/block-group.c
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Original file line number Diff line number Diff line change
Expand Up @@ -1686,22 +1686,118 @@ static int check_chunk_block_group_mappings(struct btrfs_fs_info *fs_info)
return ret;
}

static int read_one_block_group(struct btrfs_fs_info *info,
struct btrfs_path *path,
int need_clear)
{
struct extent_buffer *leaf = path->nodes[0];
struct btrfs_block_group_cache *cache;
struct btrfs_space_info *space_info;
struct btrfs_key key;
struct btrfs_block_group_item bgi;
const bool mixed = btrfs_fs_incompat(info, MIXED_GROUPS);
int slot = path->slots[0];
int ret;

btrfs_item_key_to_cpu(leaf, &key, slot);
ASSERT(key.type == BTRFS_BLOCK_GROUP_ITEM_KEY);

cache = btrfs_create_block_group_cache(info, key.objectid, key.offset);
if (!cache)
return -ENOMEM;

if (need_clear) {
/*
* When we mount with old space cache, we need to
* set BTRFS_DC_CLEAR and set dirty flag.
*
* a) Setting 'BTRFS_DC_CLEAR' makes sure that we
* truncate the old free space cache inode and
* setup a new one.
* b) Setting 'dirty flag' makes sure that we flush
* the new space cache info onto disk.
*/
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,
"bg %llu is a mixed block group but filesystem hasn't enabled mixed block groups",
cache->start);
ret = -EINVAL;
goto error;
}

/*
* We need to exclude the super stripes now so that the space info has
* super bytes accounted for, otherwise we'll think we have more space
* than we actually do.
*/
ret = exclude_super_stripes(cache);
if (ret) {
/* We may have excluded something, so call this just in case. */
btrfs_free_excluded_extents(cache);
goto error;
}

/*
* Check for two cases, either we are full, and therefore don't need
* to bother with the caching work since we won't find any space, or we
* 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) {
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);
btrfs_free_excluded_extents(cache);
}

ret = btrfs_add_block_group_cache(info, cache);
if (ret) {
btrfs_remove_free_space_cache(cache);
goto error;
}
trace_btrfs_add_block_group(info, cache, 0);
btrfs_update_space_info(info, cache->flags, key.offset,
cache->used, cache->bytes_super, &space_info);

cache->space_info = space_info;

link_block_group(cache);

set_avail_alloc_bits(info, cache->flags);
if (btrfs_chunk_readonly(info, cache->start)) {
inc_block_group_ro(cache, 1);
} else if (cache->used == 0) {
ASSERT(list_empty(&cache->bg_list));
btrfs_mark_bg_unused(cache);
}
return 0;
error:
btrfs_put_block_group(cache);
return ret;
}

int btrfs_read_block_groups(struct btrfs_fs_info *info)
{
struct btrfs_path *path;
int ret;
struct btrfs_block_group_cache *cache;
struct btrfs_space_info *space_info;
struct btrfs_key key;
struct btrfs_key found_key;
struct extent_buffer *leaf;
int need_clear = 0;
u64 cache_gen;
u64 feature;
int mixed;

feature = btrfs_super_incompat_flags(info->super_copy);
mixed = !!(feature & BTRFS_FEATURE_INCOMPAT_MIXED_GROUPS);

key.objectid = 0;
key.offset = 0;
Expand All @@ -1719,118 +1815,19 @@ int btrfs_read_block_groups(struct btrfs_fs_info *info)
need_clear = 1;

while (1) {
struct btrfs_block_group_item bgi;

ret = find_first_block_group(info, path, &key);
if (ret > 0)
break;
if (ret != 0)
goto error;

leaf = path->nodes[0];
btrfs_item_key_to_cpu(leaf, &found_key, path->slots[0]);

cache = btrfs_create_block_group_cache(info, found_key.objectid,
found_key.offset);
if (!cache) {
ret = -ENOMEM;
goto error;
}

if (need_clear) {
/*
* When we mount with old space cache, we need to
* set BTRFS_DC_CLEAR and set dirty flag.
*
* a) Setting 'BTRFS_DC_CLEAR' makes sure that we
* truncate the old free space cache inode and
* setup a new one.
* b) Setting 'dirty flag' makes sure that we flush
* the new space cache info onto disk.
*/
if (btrfs_test_opt(info, SPACE_CACHE))
cache->disk_cache_state = BTRFS_DC_CLEAR;
}

read_extent_buffer(leaf, &bgi,
btrfs_item_ptr_offset(leaf, path->slots[0]),
sizeof(bgi));
/* cache::chunk_objectid is unused */
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,
"bg %llu is a mixed block group but filesystem hasn't enabled mixed block groups",
cache->start);
btrfs_put_block_group(cache);
ret = -EINVAL;
btrfs_item_key_to_cpu(path->nodes[0], &key, path->slots[0]);
ret = read_one_block_group(info, path, need_clear);
if (ret < 0)
goto error;
}

key.objectid = found_key.objectid + found_key.offset;
key.objectid += key.offset;
key.offset = 0;
btrfs_release_path(path);

/*
* We need to exclude the super stripes now so that the space
* info has super bytes accounted for, otherwise we'll think
* we have more space than we actually do.
*/
ret = exclude_super_stripes(cache);
if (ret) {
/*
* We may have excluded something, so call this just in
* case.
*/
btrfs_free_excluded_extents(cache);
btrfs_put_block_group(cache);
goto error;
}

/*
* Check for two cases, either we are full, and therefore
* don't need to bother with the caching work since we won't
* find any space, or we 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 (found_key.offset == 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, found_key.objectid,
found_key.objectid +
found_key.offset);
btrfs_free_excluded_extents(cache);
}

ret = btrfs_add_block_group_cache(info, cache);
if (ret) {
btrfs_remove_free_space_cache(cache);
btrfs_put_block_group(cache);
goto error;
}

trace_btrfs_add_block_group(info, cache, 0);
btrfs_update_space_info(info, cache->flags, found_key.offset,
cache->used,
cache->bytes_super, &space_info);

cache->space_info = space_info;

link_block_group(cache);

set_avail_alloc_bits(info, cache->flags);
if (btrfs_chunk_readonly(info, cache->start)) {
inc_block_group_ro(cache, 1);
} else if (cache->used == 0) {
ASSERT(list_empty(&cache->bg_list));
btrfs_mark_bg_unused(cache);
}
}

list_for_each_entry_rcu(space_info, &info->space_info, list) {
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