scsi: core: Add a device_configure method to the host template

This is a version of ->slave_configure that also takes a queue_limits
structure that the caller applies, and thus allows drivers to reconfigure
the queue using the atomic queue limits API.

In the long run it should also replace ->slave_configure entirely as there
is no need to have two different methods here, and the slave name in
addition to being politically charged also has no basis in the SCSI
standards or the kernel code.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20240409143748.980206-11-hch@lst.de
Reviewed-by: Bart Van Assche <bvanassche@acm.org>
Reviewed-by: Damien Le Moal <dlemoal@kernel.org>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

Author: Christoph Hellwig

drivers/scsi/scsi_scan.c

@@ -227,7 +227,7 @@ static int scsi_realloc_sdev_budget_map(struct scsi_device *sdev,
 
 	/*
 	 * realloc if new shift is calculated, which is caused by setting
-	 * up one new default queue depth after calling ->slave_configure
+	 * up one new default queue depth after calling ->device_configure
 	 */
 	if (!need_alloc && new_shift != sdev->budget_map.shift)
 		need_alloc = need_free = true;
@@ -874,6 +874,7 @@ static int scsi_probe_lun(struct scsi_device *sdev, unsigned char *inq_result,
 static int scsi_add_lun(struct scsi_device *sdev, unsigned char *inq_result,
 		blist_flags_t *bflags, int async)
 {
+	const struct scsi_host_template *hostt = sdev->host->hostt;
 	struct queue_limits lim;
 	int ret;
 
@@ -1073,33 +1074,37 @@ static int scsi_add_lun(struct scsi_device *sdev, unsigned char *inq_result,
 		lim.max_hw_sectors = 512;
 	else if (*bflags & BLIST_MAX_1024)
 		lim.max_hw_sectors = 1024;
+
+	if (hostt->device_configure)
+		ret = hostt->device_configure(sdev, &lim);
+	else if (hostt->slave_configure)
+		ret = hostt->slave_configure(sdev);
+	if (ret) {
+		queue_limits_cancel_update(sdev->request_queue);
+		/*
+		 * If the LLDD reports device not present, don't clutter the
+		 * console with failure messages.
+		 */
+		if (ret != -ENXIO)
+			sdev_printk(KERN_ERR, sdev,
+				"failed to configure device\n");
+		return SCSI_SCAN_NO_RESPONSE;
+	}
+
 	ret = queue_limits_commit_update(sdev->request_queue, &lim);
 	if (ret) {
 		sdev_printk(KERN_ERR, sdev, "failed to apply queue limits.\n");
 		return SCSI_SCAN_NO_RESPONSE;
 	}
 
-	if (sdev->host->hostt->slave_configure) {
-		ret = sdev->host->hostt->slave_configure(sdev);
-		if (ret) {
-			/*
-			 * if LLDD reports slave not present, don't clutter
-			 * console with alloc failure messages
-			 */
-			if (ret != -ENXIO) {
-				sdev_printk(KERN_ERR, sdev,
-					"failed to configure device\n");
-			}
-			return SCSI_SCAN_NO_RESPONSE;
-		}
-
-		/*
-		 * The queue_depth is often changed in ->slave_configure.
-		 * Set up budget map again since memory consumption of
-		 * the map depends on actual queue depth.
-		 */
+	/*
+	 * The queue_depth is often changed in ->device_configure.
+	 *
+	 * Set up budget map again since memory consumption of the map depends
+	 * on actual queue depth.
+	 */
+	if (hostt->device_configure || hostt->slave_configure)
 		scsi_realloc_sdev_budget_map(sdev, sdev->queue_depth);
-	}
 
 	if (sdev->scsi_level >= SCSI_3)
 		scsi_attach_vpd(sdev);

include/scsi/scsi_host.h

@@ -211,7 +211,11 @@ struct scsi_host_template {
 	 *     up after yourself before returning non-0
 	 *
 	 * Status: OPTIONAL
+	 *
+	 * Note: slave_configure is the legacy version, use device_configure for
+	 * all new code.  A driver must never define both.
 	 */
+	int (* device_configure)(struct scsi_device *, struct queue_limits *lim);
 	int (* slave_configure)(struct scsi_device *);
 
 	/*