btrfs: sink wait_for_unblock parameter to async commit

There's only one caller left btrfs_ioctl_start_sync that passes 0, so we
can remove the switch in btrfs_commit_transaction_async.

A cleanup 9babda9f ("btrfs: Remove async_transid from
btrfs_mksubvol/create_subvol/create_snapshot") removed calls that passed
1, so this is a followup.

As this removes last call of wait_current_trans_commit_start_and_unblock,
remove the function as well.
Reviewed-by: Anand Jain <anand.jain@oracle.com>
Signed-off-by: David Sterba <dsterba@suse.com>

fs/btrfs/ioctl.c

@@ -3643,7 +3643,7 @@ static noinline long btrfs_ioctl_start_sync(struct btrfs_root *root,
 		goto out;
 	}
 	transid = trans->transid;
-	ret = btrfs_commit_transaction_async(trans, 0);
+	ret = btrfs_commit_transaction_async(trans);
 	if (ret) {
 		btrfs_end_transaction(trans);
 		return ret;

fs/btrfs/transaction.c

@@ -1882,19 +1882,6 @@ static void wait_current_trans_commit_start(struct btrfs_fs_info *fs_info,
 		   TRANS_ABORTED(trans));
 }
 
-/*
- * wait for the current transaction to start and then become unblocked.
- * caller holds ref.
- */
-static void wait_current_trans_commit_start_and_unblock(
-					struct btrfs_fs_info *fs_info,
-					struct btrfs_transaction *trans)
-{
-	wait_event(fs_info->transaction_wait,
-		   trans->state >= TRANS_STATE_UNBLOCKED ||
-		   TRANS_ABORTED(trans));
-}
-
 /*
  * commit transactions asynchronously. once btrfs_commit_transaction_async
  * returns, any subsequent transaction will not be allowed to join.
@@ -1922,8 +1909,7 @@ static void do_async_commit(struct work_struct *work)
 	kfree(ac);
 }
 
-int btrfs_commit_transaction_async(struct btrfs_trans_handle *trans,
-				   int wait_for_unblock)
+int btrfs_commit_transaction_async(struct btrfs_trans_handle *trans)
 {
 	struct btrfs_fs_info *fs_info = trans->fs_info;
 	struct btrfs_async_commit *ac;
@@ -1955,13 +1941,7 @@ int btrfs_commit_transaction_async(struct btrfs_trans_handle *trans,
 		__sb_writers_release(fs_info->sb, SB_FREEZE_FS);
 
 	schedule_work(&ac->work);
-
-	/* wait for transaction to start and unblock */
-	if (wait_for_unblock)
-		wait_current_trans_commit_start_and_unblock(fs_info, cur_trans);
-	else
 	wait_current_trans_commit_start(fs_info, cur_trans);
-
 	if (current->journal_info == trans)
 		current->journal_info = NULL;
 

fs/btrfs/transaction.h

@@ -226,8 +226,7 @@ void btrfs_add_dead_root(struct btrfs_root *root);
 int btrfs_defrag_root(struct btrfs_root *root);
 int btrfs_clean_one_deleted_snapshot(struct btrfs_root *root);
 int btrfs_commit_transaction(struct btrfs_trans_handle *trans);
-int btrfs_commit_transaction_async(struct btrfs_trans_handle *trans,
-				   int wait_for_unblock);
+int btrfs_commit_transaction_async(struct btrfs_trans_handle *trans);
 int btrfs_end_transaction_throttle(struct btrfs_trans_handle *trans);
 bool btrfs_should_end_transaction(struct btrfs_trans_handle *trans);
 void btrfs_throttle(struct btrfs_fs_info *fs_info);