[PATCH 1/3] add io_uring with IOPOLL support in scsi layer

[Kashyap Desai <kashyap.desai@broadcom.com>]

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io_uring with IOPOLL is not currently supported in scsi mid layer.
Outside of that everything else should work and no extra support in the driver is needed.
Currently io_uring with IOPOLL support is only available in block layer.
This patch is to extend support of mq_poll in scsi layer.

Signed-off-by: Kashyap Desai <kashyap.desai@broadcom.com>
Cc: sumit.saxena@broadcom.com
Cc: chandrakanth.patil@broadcom.com
Cc: linux-block@vger.kernel.org
---
 drivers/scsi/scsi_lib.c  | 16 ++++++++++++++++
 include/scsi/scsi_cmnd.h |  1 +
 include/scsi/scsi_host.h | 11 +++++++++++
 3 files changed, 28 insertions(+)

diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c
index a89478a0c588..0140d9aac64b 100644
--- a/drivers/scsi/scsi_lib.c
+++ b/drivers/scsi/scsi_lib.c
@@ -1757,6 +1757,19 @@ static void scsi_mq_exit_request(struct blk_mq_tag_set *set, struct request *rq,
 			       cmd->sense_buffer);
 }
 
+
+static int scsi_mq_poll(struct blk_mq_hw_ctx *hctx)
+{
+	struct request_queue *q = hctx->queue;
+	struct scsi_device *sdev = q->queuedata;
+	struct Scsi_Host *shost = sdev->host;
+
+	if (shost->hostt->mq_poll)
+		return shost->hostt->mq_poll(shost, hctx->queue_num);
+
+	return 0;
+}
+
 static int scsi_map_queues(struct blk_mq_tag_set *set)
 {
 	struct Scsi_Host *shost = container_of(set, struct Scsi_Host, tag_set);
@@ -1824,6 +1837,7 @@ static const struct blk_mq_ops scsi_mq_ops_no_commit = {
 	.cleanup_rq	= scsi_cleanup_rq,
 	.busy		= scsi_mq_lld_busy,
 	.map_queues	= scsi_map_queues,
+	.poll		= scsi_mq_poll,
 };
 
 
@@ -1852,6 +1866,7 @@ static const struct blk_mq_ops scsi_mq_ops = {
 	.cleanup_rq	= scsi_cleanup_rq,
 	.busy		= scsi_mq_lld_busy,
 	.map_queues	= scsi_map_queues,
+	.poll		= scsi_mq_poll,
 };
 
 struct request_queue *scsi_mq_alloc_queue(struct scsi_device *sdev)
@@ -1884,6 +1899,7 @@ int scsi_mq_setup_tags(struct Scsi_Host *shost)
 	else
 		tag_set->ops = &scsi_mq_ops_no_commit;
 	tag_set->nr_hw_queues = shost->nr_hw_queues ? : 1;
+	tag_set->nr_maps = shost->nr_maps ? : 1;
 	tag_set->queue_depth = shost->can_queue;
 	tag_set->cmd_size = cmd_size;
 	tag_set->numa_node = NUMA_NO_NODE;
diff --git a/include/scsi/scsi_cmnd.h b/include/scsi/scsi_cmnd.h
index e76bac4d14c5..5844374a85b1 100644
--- a/include/scsi/scsi_cmnd.h
+++ b/include/scsi/scsi_cmnd.h
@@ -9,6 +9,7 @@
 #include <linux/types.h>
 #include <linux/timer.h>
 #include <linux/scatterlist.h>
+#include <scsi/scsi_host.h>
 #include <scsi/scsi_device.h>
 #include <scsi/scsi_request.h>
 
diff --git a/include/scsi/scsi_host.h b/include/scsi/scsi_host.h
index 701f178b20ae..905ee6b00c55 100644
--- a/include/scsi/scsi_host.h
+++ b/include/scsi/scsi_host.h
@@ -270,6 +270,16 @@ struct scsi_host_template {
 	 */
 	int (* map_queues)(struct Scsi_Host *shost);
 
+	/*
+	 * SCSI interface of blk_poll - poll for IO completions.
+	 * Possible interface only if scsi LLD expose multiple h/w queues.
+	 *
+	 * Return values: Number of completed entries found.
+	 *
+	 * Status: OPTIONAL
+	 */
+	int (* mq_poll)(struct Scsi_Host *shost, unsigned int queue_num);
+
 	/*
 	 * Check if scatterlists need to be padded for DMA draining.
 	 *
@@ -610,6 +620,7 @@ struct Scsi_Host {
 	 * the total queue depth is can_queue.
 	 */
 	unsigned nr_hw_queues;
+	unsigned nr_maps;
 	unsigned active_mode:2;
 	unsigned unchecked_isa_dma:1;
 
-- 
2.18.1


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