[PATCH v3 2/3] btrfs: block-group: Refactor btrfs_read_block_groups()

Qu Wenruo
2019-10-10T02:39:39Z

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

Signed-off-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: Johannes Thumshirn <jthumshirn@suse.de>
Reviewed-by: Anand Jain <anand.jain@oracle.com>
---
fs/btrfs/block-group.c | 215 +++++++++++++++++++++--------------------
1 file changed, 108 insertions(+), 107 deletions(-)

diff --git a/fs/btrfs/block-group.c b/fs/btrfs/block-group.c
index c906a2b6c2cf..0c5eef0610fa 100644
--- a/fs/btrfs/block-group.c
+++ b/fs/btrfs/block-group.c
@@ -1687,6 +1687,109 @@ 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;
+ int 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, &cache->item,
+ btrfs_item_ptr_offset(leaf, slot),
+ sizeof(cache->item));
+ cache->flags = btrfs_block_group_flags(&cache->item);
+ 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->key.objectid);
+ 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 == btrfs_block_group_used(&cache->item)) {
+ cache->last_byte_to_unpin = (u64)-1;
+ cache->cached = BTRFS_CACHE_FINISHED;
+ btrfs_free_excluded_extents(cache);
+ } else if (btrfs_block_group_used(&cache->item) == 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,
+ btrfs_block_group_used(&cache->item),
+ 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->key.objectid)) {
+ inc_block_group_ro(cache, 1);
+ } else if (btrfs_block_group_used(&cache->item) == 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;
@@ -1694,15 +1797,8 @@ int btrfs_read_block_groups(struct btrfs_fs_info *info)
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;
@@ -1726,108 +1822,13 @@ int btrfs_read_block_groups(struct btrfs_fs_info *info)
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, &cache->item,
- btrfs_item_ptr_offset(leaf, path->slots[0]),
- sizeof(cache->item));
- cache->flags = btrfs_block_group_flags(&cache->item);
- 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->key.objectid);
- ret = -EINVAL;
- btrfs_put_block_group(cache);
+ 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 == btrfs_block_group_used(&cache->item)) {
- cache->last_byte_to_unpin = (u64)-1;
- cache->cached = BTRFS_CACHE_FINISHED;
- btrfs_free_excluded_extents(cache);
- } else if (btrfs_block_group_used(&cache->item) == 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,
- btrfs_block_group_used(&cache->item),
- 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->key.objectid)) {
- inc_block_group_ro(cache, 1);
- } else if (btrfs_block_group_used(&cache->item) == 0) {
- ASSERT(list_empty(&cache->bg_list));
- btrfs_mark_bg_unused(cache);
- }
}

list_for_each_entry_rcu(space_info, &info->space_info, list) {
--
2.23.0