btrfs: switch to refcount_t type for btrfs_trans_handle::use_count
The use_count is a reference counter, we can use the refcount_t type,
though we don't use the atomicity. This is not a performance critical
code and we could catch the underflows. The type is changed from long,
but the number of references will fit an int.
Signed-off-by: David Sterba <dsterba@suse.com>
diff --git a/fs/btrfs/transaction.c b/fs/btrfs/transaction.c
index dac688c..6348573 100644
--- a/fs/btrfs/transaction.c
+++ b/fs/btrfs/transaction.c
@@ -495,8 +495,8 @@ start_transaction(struct btrfs_root *root, unsigned int num_items,
if (current->journal_info) {
WARN_ON(type & TRANS_EXTWRITERS);
h = current->journal_info;
- h->use_count++;
- WARN_ON(h->use_count > 2);
+ refcount_inc(&h->use_count);
+ WARN_ON(refcount_read(&h->use_count) > 2);
h->orig_rsv = h->block_rsv;
h->block_rsv = NULL;
goto got_it;
@@ -567,7 +567,7 @@ start_transaction(struct btrfs_root *root, unsigned int num_items,
h->transid = cur_trans->transid;
h->transaction = cur_trans;
h->root = root;
- h->use_count = 1;
+ refcount_set(&h->use_count, 1);
h->fs_info = root->fs_info;
h->type = type;
@@ -837,8 +837,8 @@ static int __btrfs_end_transaction(struct btrfs_trans_handle *trans,
int err = 0;
int must_run_delayed_refs = 0;
- if (trans->use_count > 1) {
- trans->use_count--;
+ if (refcount_read(&trans->use_count) > 1) {
+ refcount_dec(&trans->use_count);
trans->block_rsv = trans->orig_rsv;
return 0;
}
@@ -1868,7 +1868,7 @@ static void cleanup_transaction(struct btrfs_trans_handle *trans,
struct btrfs_transaction *cur_trans = trans->transaction;
DEFINE_WAIT(wait);
- WARN_ON(trans->use_count > 1);
+ WARN_ON(refcount_read(&trans->use_count) > 1);
btrfs_abort_transaction(trans, err);