Btrfs: remove no longer used 'sync' member from transaction handle

Commit db2462a6 ("btrfs: don't run delayed refs in the end transaction
logic") removed its last use, so now it does absolutely nothing, therefore
remove it.
Reviewed-by: NNikolay Borisov <nborisov@suse.com>
Signed-off-by: NFilipe Manana <fdmanana@suse.com>
Reviewed-by: NDavid Sterba <dsterba@suse.com>
Signed-off-by: NDavid Sterba <dsterba@suse.com>

fs/btrfs/extent-tree.c

@@ -2910,12 +2910,6 @@ static void delayed_ref_async_start(struct btrfs_work *work)
 		goto done;
 	}
 
-	/*
-	 * trans->sync means that when we call end_transaction, we won't
-	 * wait on delayed refs
-	 */
-	trans->sync = true;
-
 	/* Don't bother flushing if we got into a different transaction */
 	if (trans->transid > async->transid)
 		goto end;

fs/btrfs/file.c

@@ -2165,7 +2165,6 @@ int btrfs_sync_file(struct file *file, loff_t start, loff_t end, int datasync)
 		inode_unlock(inode);
 		goto out;
 	}
-	trans->sync = true;
 
 	ret = btrfs_log_dentry_safe(trans, dentry, start, end, &ctx);
 	if (ret < 0) {

fs/btrfs/transaction.h

@@ -120,7 +120,6 @@ struct btrfs_trans_handle {
 	bool allocating_chunk;
 	bool can_flush_pending_bgs;
 	bool reloc_reserved;
-	bool sync;
 	bool dirty;
 	struct btrfs_root *root;
 	struct btrfs_fs_info *fs_info;