scsi: core: Add mq_poll support to SCSI layer

Currently IOPOLL support is only available in block layer. This patch
adds mq_poll support to the SCSI layer.

Link: https://lore.kernel.org/r/20210215074048.19424-2-kashyap.desai@broadcom.com
Cc: sumit.saxena@broadcom.com
Cc: chandrakanth.patil@broadcom.com
Cc: linux-block@vger.kernel.org
Reviewed-by: Hannes Reinecke <hare@suse.de>
Reviewed-by: John Garry <john.garry@huawei.com>
Signed-off-by: Kashyap Desai <kashyap.desai@broadcom.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c
index ffe8247..09d09ef 100644 (file)
--- a/drivers/scsi/scsi_lib.c
+++ b/drivers/scsi/scsi_lib.c
@@ -1810,6 +1810,19 @@ 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);
@@ -1877,6 +1890,7 @@ 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,
        .set_rq_budget_token = scsi_mq_set_rq_budget_token,
        .get_rq_budget_token = scsi_mq_get_rq_budget_token,
 };
@@ -1907,6 +1921,7 @@ 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,
        .set_rq_budget_token = scsi_mq_set_rq_budget_token,
        .get_rq_budget_token = scsi_mq_get_rq_budget_token,
 };
@@ -1941,6 +1956,7 @@ 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 0cf2b5c..83f7e52 100644 (file)
--- a/include/scsi/scsi_cmnd.h
+++ b/include/scsi/scsi_cmnd.h
@@ -10,6 +10,7 @@
 #include <linux/timer.h>
 #include <linux/scatterlist.h>
 #include <scsi/scsi_device.h>
+#include <scsi/scsi_host.h>
 #include <scsi/scsi_request.h>
 
 struct Scsi_Host;

diff --git a/include/scsi/scsi_host.h b/include/scsi/scsi_host.h
index f0e8a9e..d95c150 100644 (file)
--- a/include/scsi/scsi_host.h
+++ b/include/scsi/scsi_host.h
@@ -280,6 +280,16 @@ struct scsi_host_template {
         */
        int (* map_queues)(struct Scsi_Host *shost);
 
+       /*
+        * SCSI interface of blk_poll - poll for IO completions.
+        * Only applicable if SCSI LLD exposes multiple h/w queues.
+        *
+        * Return value: 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.
         *
@@ -622,6 +632,7 @@ 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;