[PATCH 1/2][v2] btrfs: convert block group refcount to refcount_t

Josef Bacik
2020-07-06T13:14:17Z

We have refcount_t now with the associated library to handle refcounts,
which gives us extra debugging around reference count mistakes that may
be made. For example it'll warn on any transition from 0->1 or 0->-1,
which is handy for noticing cases where we've messed up reference
counting. Convert the block group ref counting from an atomic_t to
refcount_t and use the appropriate helpers.

Reviewed-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
---
- rename ->count to ->refs.
- updated commit message.

fs/btrfs/block-group.c | 8 ++++----
fs/btrfs/block-group.h | 3 +--
2 files changed, 5 insertions(+), 6 deletions(-)

diff --git a/fs/btrfs/block-group.c b/fs/btrfs/block-group.c
index 3aa78952a2b7..0a67a50f448a 100644
--- a/fs/btrfs/block-group.c
+++ b/fs/btrfs/block-group.c
@@ -118,12 +118,12 @@ u64 btrfs_get_alloc_profile(struct btrfs_fs_info *fs_info, u64 orig_flags)

void btrfs_get_block_group(struct btrfs_block_group *cache)
{
- atomic_inc(&cache->count);
+ refcount_inc(&cache->refs);
}

void btrfs_put_block_group(struct btrfs_block_group *cache)
{
- if (atomic_dec_and_test(&cache->count)) {
+ if (refcount_dec_and_test(&cache->refs)) {
WARN_ON(cache->pinned > 0);
WARN_ON(cache->reserved > 0);

@@ -1805,7 +1805,7 @@ static struct btrfs_block_group *btrfs_create_block_group_cache(

cache->discard_index = BTRFS_DISCARD_INDEX_UNUSED;

- atomic_set(&cache->count, 1);
+ refcount_set(&cache->refs, 1);
spin_lock_init(&cache->lock);
init_rwsem(&cache->data_rwsem);
INIT_LIST_HEAD(&cache->list);
@@ -3428,7 +3428,7 @@ int btrfs_free_block_groups(struct btrfs_fs_info *info)
ASSERT(list_empty(&block_group->dirty_list));
ASSERT(list_empty(&block_group->io_list));
ASSERT(list_empty(&block_group->bg_list));
- ASSERT(atomic_read(&block_group->count) == 1);
+ ASSERT(refcount_read(&block_group->refs) == 1);
btrfs_put_block_group(block_group);

spin_lock(&info->block_group_cache_lock);
diff --git a/fs/btrfs/block-group.h b/fs/btrfs/block-group.h
index b6ee70a039c7..adfd7583a17b 100644
--- a/fs/btrfs/block-group.h
+++ b/fs/btrfs/block-group.h
@@ -114,8 +114,7 @@ struct btrfs_block_group {
/* For block groups in the same raid type */
struct list_head list;

- /* Usage count */
- atomic_t count;
+ refcount_t refs;

/*
* List of struct btrfs_free_clusters for this block group.
--
2.24.1