block: better op and flags encoding

Now that we don't need the common flags to overflow outside the range
of a 32-bit type we can encode them the same way for both the bio and
request fields.  This in addition allows us to place the operation
first (and make some room for more ops while we're at it) and to
stop having to shift around the operation values.

In addition this allows passing around only one value in the block layer
instead of two (and eventuall also in the file systems, but we can do
that later) and thus clean up a lot of code.

Last but not least this allows decreasing the size of the cmd_flags
field in struct request to 32-bits.  Various functions passing this
value could also be updated, but I'd like to avoid the churn for now.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@fb.com>

1 files changed, 11 insertions, 17 deletions

diff --git a/block/blk-mq.c b/block/blk-mq.c
index b49c6658eb05..2da1a0ee3318 100644
--- a/block/blk-mq.c
+++ b/block/blk-mq.c
@@ -139,14 +139,13 @@ bool blk_mq_can_queue(struct blk_mq_hw_ctx *hctx)
 EXPORT_SYMBOL(blk_mq_can_queue);
 
 static void blk_mq_rq_ctx_init(struct request_queue *q, struct blk_mq_ctx *ctx,
-			       struct request *rq, int op,
-			       unsigned int op_flags)
+			       struct request *rq, unsigned int op)
 {
 	INIT_LIST_HEAD(&rq->queuelist);
 	/* csd/requeue_work/fifo_time is initialized before use */
 	rq->q = q;
 	rq->mq_ctx = ctx;
-	req_set_op_attrs(rq, op, op_flags);
+	rq->cmd_flags = op;
 	if (blk_queue_io_stat(q))
 		rq->rq_flags |= RQF_IO_STAT;
 	/* do not touch atomic flags, it needs atomic ops against the timer */
@@ -183,11 +182,11 @@ static void blk_mq_rq_ctx_init(struct request_queue *q, struct blk_mq_ctx *ctx,
 	rq->end_io_data = NULL;
 	rq->next_rq = NULL;
 
-	ctx->rq_dispatched[rw_is_sync(op, op_flags)]++;
+	ctx->rq_dispatched[op_is_sync(op)]++;
 }
 
 static struct request *
-__blk_mq_alloc_request(struct blk_mq_alloc_data *data, int op, int op_flags)
+__blk_mq_alloc_request(struct blk_mq_alloc_data *data, unsigned int op)
 {
 	struct request *rq;
 	unsigned int tag;
@@ -202,7 +201,7 @@ __blk_mq_alloc_request(struct blk_mq_alloc_data *data, int op, int op_flags)
 		}
 
 		rq->tag = tag;
-		blk_mq_rq_ctx_init(data->q, data->ctx, rq, op, op_flags);
+		blk_mq_rq_ctx_init(data->q, data->ctx, rq, op);
 		return rq;
 	}
 
@@ -225,7 +224,7 @@ struct request *blk_mq_alloc_request(struct request_queue *q, int rw,
 	ctx = blk_mq_get_ctx(q);
 	hctx = blk_mq_map_queue(q, ctx->cpu);
 	blk_mq_set_alloc_data(&alloc_data, q, flags, ctx, hctx);
-	rq = __blk_mq_alloc_request(&alloc_data, rw, 0);
+	rq = __blk_mq_alloc_request(&alloc_data, rw);
 	blk_mq_put_ctx(ctx);
 
 	if (!rq) {
@@ -277,7 +276,7 @@ struct request *blk_mq_alloc_request_hctx(struct request_queue *q, int rw,
 	ctx = __blk_mq_get_ctx(q, cpumask_first(hctx->cpumask));
 
 	blk_mq_set_alloc_data(&alloc_data, q, flags, ctx, hctx);
-	rq = __blk_mq_alloc_request(&alloc_data, rw, 0);
+	rq = __blk_mq_alloc_request(&alloc_data, rw);
 	if (!rq) {
 		ret = -EWOULDBLOCK;
 		goto out_queue_exit;
@@ -1196,19 +1195,14 @@ static struct request *blk_mq_map_request(struct request_queue *q,
 	struct blk_mq_hw_ctx *hctx;
 	struct blk_mq_ctx *ctx;
 	struct request *rq;
-	int op = bio_data_dir(bio);
-	int op_flags = 0;
 
 	blk_queue_enter_live(q);
 	ctx = blk_mq_get_ctx(q);
 	hctx = blk_mq_map_queue(q, ctx->cpu);
 
-	if (rw_is_sync(bio_op(bio), bio->bi_opf))
-		op_flags |= REQ_SYNC;
-
-	trace_block_getrq(q, bio, op);
+	trace_block_getrq(q, bio, bio->bi_opf);
 	blk_mq_set_alloc_data(data, q, 0, ctx, hctx);
-	rq = __blk_mq_alloc_request(data, op, op_flags);
+	rq = __blk_mq_alloc_request(data, bio->bi_opf);
 
 	data->hctx->queued++;
 	return rq;
@@ -1256,7 +1250,7 @@ static int blk_mq_direct_issue_request(struct request *rq, blk_qc_t *cookie)
  */
 static blk_qc_t blk_mq_make_request(struct request_queue *q, struct bio *bio)
 {
-	const int is_sync = rw_is_sync(bio_op(bio), bio->bi_opf);
+	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 request *rq;
@@ -1350,7 +1344,7 @@ done:
  */
 static blk_qc_t blk_sq_make_request(struct request_queue *q, struct bio *bio)
 {
-	const int is_sync = rw_is_sync(bio_op(bio), bio->bi_opf);
+	const int is_sync = op_is_sync(bio->bi_opf);
 	const int is_flush_fua = bio->bi_opf & (REQ_PREFLUSH | REQ_FUA);
 	struct blk_plug *plug;
 	unsigned int request_count = 0;