scsi: core: introduce force_blk_mq

BugLink: http://bugs.launchpad.net/bugs/1759723
This patch introduces 'force_blk_mq' to the scsi_host_template so that
drivers that have no desire to support the legacy I/O path can signal
blk-mq only support.

[mkp: commit desc]

Cc: Omar Sandoval <osandov@fb.com>,
Cc: "Martin K. Petersen" <martin.petersen@oracle.com>,
Cc: James Bottomley <james.bottomley@hansenpartnership.com>,
Cc: Christoph Hellwig <hch@lst.de>,
Cc: Don Brace <don.brace@microsemi.com>
Cc: Kashyap Desai <kashyap.desai@broadcom.com>
Cc: Mike Snitzer <snitzer@redhat.com>
Cc: Laurence Oberman <loberman@redhat.com>
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
(cherry picked from commit 2f31115e940c4afd49b99c33123534e2ac924ffb)
Signed-off-by: Jose Ricardo Ziviani <joserz@linux.ibm.com>
Acked-by: Kleber Sacilotto de Souza <kleber.souza@canonical.com>
Acked-by: Stefan Bader <stefan.bader@canonical.com>
Signed-off-by: Khalid Elmously <khalid.elmously@canonical.com>

diff --git a/drivers/scsi/hosts.c b/drivers/scsi/hosts.c
index dd9464920456fd550f8da9bab2e345ae843d1d15..ef22b275d0505b5bd9580182b2c67730f3181dc8 100644 (file)
--- a/drivers/scsi/hosts.c
+++ b/drivers/scsi/hosts.c
@@ -474,6 +474,7 @@ struct Scsi_Host *scsi_host_alloc(struct scsi_host_template *sht, int privsize)
                shost->dma_boundary = 0xffffffff;
 
        shost->use_blk_mq = scsi_use_blk_mq;
+       shost->use_blk_mq = scsi_use_blk_mq || shost->hostt->force_blk_mq;
 
        device_initialize(&shost->shost_gendev);
        dev_set_name(&shost->shost_gendev, "host%d", shost->host_no);

diff --git a/include/scsi/scsi_host.h b/include/scsi/scsi_host.h
index a8b7bf879cede4240d921a42f915a230163e5e4e..9c1e4bad6581d39bb4bcafc9205b38ed43e541cf 100644 (file)
--- a/include/scsi/scsi_host.h
+++ b/include/scsi/scsi_host.h
@@ -452,6 +452,9 @@ struct scsi_host_template {
        /* True if the controller does not support WRITE SAME */
        unsigned no_write_same:1;
 
+       /* True if the low-level driver supports blk-mq only */
+       unsigned force_blk_mq:1;
+
        /*
         * Countdown for host blocking with no commands outstanding.
         */