scsi: fnic: Add support for multiqueue (MQ) in fnic driver

Implement support for MQ in fnic driver:

The block multiqueue layer issues IO to the fnic driver with an MQ tag. Use
the mqtag and derive a tag from it.  Derive the hardware queue from the
mqtag and use it in all paths. Modify queuecommand to handle mqtag.

Replace wq and cq indices to support MQ. Replace the zeroth queue with a
hardware queue.  Implement spin locks on a per hardware queue basis.
Replace io_lock with per hardware queue spinlock.  Implement out of range
tag checks.

Allocate an io_req_table to track status of the io_req.

Test the driver by building it, loading it, and configuring 64 queues in
UCSM. Issue IOs using Medusa on multiple fnics. Enable/disable links to
exercise the abort and clean up path.

Reported-by: kernel test robot <[email protected]>
Closes: https://lore.kernel.org/oe-kbuild-all/[email protected]/
Reviewed-by: Sesidhar Baddela <[email protected]>
Reviewed-by: Arulprabhu Ponnusamy <[email protected]>
Tested-by: Karan Tilak Kumar <[email protected]>
Signed-off-by: Karan Tilak Kumar <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Martin K. Petersen <[email protected]>

Author: Karan Tilak Kumar

drivers/scsi/fnic/fnic.h

@@ -36,7 +36,6 @@
 #define FNIC_MIN_IO_REQ			256 /* Min IO throttle count */
 #define FNIC_MAX_IO_REQ		1024 /* scsi_cmnd tag map entries */
 #define FNIC_DFLT_IO_REQ        256 /* Default scsi_cmnd tag map entries */
-#define	FNIC_IO_LOCKS		64 /* IO locks: power of 2 */
 #define FNIC_DFLT_QUEUE_DEPTH	256
 #define	FNIC_STATS_RATE_LIMIT	4 /* limit rate at which stats are pulled up */
 
@@ -300,7 +299,6 @@ struct fnic {
 	struct fnic_host_tag *tags;
 	mempool_t *io_req_pool;
 	mempool_t *io_sgl_pool[FNIC_SGL_NUM_CACHES];
-	spinlock_t io_req_lock[FNIC_IO_LOCKS];	/* locks for scsi cmnds */
 
 	unsigned int copy_wq_base;
 	struct work_struct link_work;

drivers/scsi/fnic/fnic_main.c

@@ -794,11 +794,6 @@ static int fnic_probe(struct pci_dev *pdev, const struct pci_device_id *ent)
 		fnic->fw_ack_index[i] = -1;
 	}
 
-	for (i = 0; i < FNIC_IO_LOCKS; i++)
-		spin_lock_init(&fnic->io_req_lock[i]);
-
-	spin_lock_init(&fnic->sgreset_lock);
-
 	err = -ENOMEM;
 	fnic->io_req_pool = mempool_create_slab_pool(2, fnic_io_req_cache);
 	if (!fnic->io_req_pool)