blk-mq: don't lose flags passed in to blk_mq_alloc_request()

If we come in from blk_mq_alloc_requst() with NOWAIT set in flags,
we must ensure that we don't later overwrite that in
blk_mq_sched_get_request(). Initialize alloc_data->flags before
passing it in.

Reported-by: Bart Van Assche <bart.vanassche@sandisk.com>
Signed-off-by: Jens Axboe <axboe@fb.com>

block/blk-mq-sched.c

@@ -117,7 +117,7 @@ struct request *blk_mq_sched_get_request(struct request_queue *q,
 	ctx = blk_mq_get_ctx(q);
 	hctx = blk_mq_map_queue(q, ctx->cpu);
 
-	blk_mq_set_alloc_data(data, q, 0, ctx, hctx);
+	blk_mq_set_alloc_data(data, q, data->flags, ctx, hctx);
 
 	if (e) {
 		data->flags |= BLK_MQ_REQ_INTERNAL;

block/blk-mq.c

@@ -253,7 +253,7 @@ EXPORT_SYMBOL_GPL(__blk_mq_alloc_request);
 struct request *blk_mq_alloc_request(struct request_queue *q, int rw,
 		unsigned int flags)
 {
-	struct blk_mq_alloc_data alloc_data;
+	struct blk_mq_alloc_data alloc_data = { .flags = flags };
 	struct request *rq;
 	int ret;
 
@@ -1382,7 +1382,7 @@ static blk_qc_t blk_mq_make_request(struct request_queue *q, struct bio *bio)
 {
 	const int is_sync = op_is_sync(bio->bi_opf);
 	const int is_flush_fua = bio->bi_opf & (REQ_PREFLUSH | REQ_FUA);
-	struct blk_mq_alloc_data data;
+	struct blk_mq_alloc_data data = { .flags = 0 };
 	struct request *rq;
 	unsigned int request_count = 0, srcu_idx;
 	struct blk_plug *plug;
@@ -1504,7 +1504,7 @@ static blk_qc_t blk_sq_make_request(struct request_queue *q, struct bio *bio)
 	const int is_flush_fua = bio->bi_opf & (REQ_PREFLUSH | REQ_FUA);
 	struct blk_plug *plug;
 	unsigned int request_count = 0;
-	struct blk_mq_alloc_data data;
+	struct blk_mq_alloc_data data = { .flags = 0 };
 	struct request *rq;
 	blk_qc_t cookie;
 	unsigned int wb_acct;