fs: make aio plug

Signed-off-by: Shaohua Li <shaohua.li@intel.com>
Signed-off-by: Jens Axboe <jaxboe@fusionio.com>

fs/aio.c

@@ -1660,6 +1660,7 @@ long do_io_submit(aio_context_t ctx_id, long nr,
 	long ret = 0;
 	int i;
 	struct hlist_head batch_hash[AIO_BATCH_HASH_SIZE] = { { 0, }, };
+	struct blk_plug plug;
 
 	if (unlikely(nr < 0))
 		return -EINVAL;
@@ -1676,6 +1677,8 @@ long do_io_submit(aio_context_t ctx_id, long nr,
 		return -EINVAL;
 	}
 
+	blk_start_plug(&plug);
+
 	/*
 	 * AKPM: should this return a partial result if some of the IOs were
 	 * successfully submitted?
@@ -1698,6 +1701,7 @@ long do_io_submit(aio_context_t ctx_id, long nr,
 		if (ret)
 			break;
 	}
+	blk_finish_plug(&plug);
 	aio_batch_free(batch_hash);
 
 	put_ioctx(ctx);