nvme: introduce max_integrity_segments ctrl attribute

This patch doesn't change any logic, and is needed as a preparation
for adding PI support for fabrics drivers that will use an extended
LBA format for metadata and will support more than 1 integrity segment.
Signed-off-by: Max Gurtovoy <maxg@mellanox.com>
Signed-off-by: Israel Rukshin <israelr@mellanox.com>
Reviewed-by: Sagi Grimberg <sagi@grimberg.me>
Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com>
Reviewed-by: James Smart <james.smart@broadcom.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>

drivers/nvme/host/core.c

@@ -1693,7 +1693,8 @@ static int nvme_getgeo(struct block_device *bdev, struct hd_geometry *geo)
 }
 
 #ifdef CONFIG_BLK_DEV_INTEGRITY
-static void nvme_init_integrity(struct gendisk *disk, u16 ms, u8 pi_type)
+static void nvme_init_integrity(struct gendisk *disk, u16 ms, u8 pi_type,
+				u32 max_integrity_segments)
 {
 	struct blk_integrity integrity;
 
@@ -1716,10 +1717,11 @@ static void nvme_init_integrity(struct gendisk *disk, u16 ms, u8 pi_type)
 	}
 	integrity.tuple_size = ms;
 	blk_integrity_register(disk, &integrity);
-	blk_queue_max_integrity_segments(disk->queue, 1);
+	blk_queue_max_integrity_segments(disk->queue, max_integrity_segments);
 }
 #else
-static void nvme_init_integrity(struct gendisk *disk, u16 ms, u8 pi_type)
+static void nvme_init_integrity(struct gendisk *disk, u16 ms, u8 pi_type,
+				u32 max_integrity_segments)
 {
 }
 #endif /* CONFIG_BLK_DEV_INTEGRITY */
@@ -1895,7 +1897,8 @@ static void nvme_update_disk_info(struct gendisk *disk,
 	if (ns->ms) {
 		if (IS_ENABLED(CONFIG_BLK_DEV_INTEGRITY) &&
 		    (ns->features & NVME_NS_METADATA_SUPPORTED))
-			nvme_init_integrity(disk, ns->ms, ns->pi_type);
+			nvme_init_integrity(disk, ns->ms, ns->pi_type,
+					    ns->ctrl->max_integrity_segments);
 		else if (!nvme_ns_has_pi(ns))
 			capacity = 0;
 	}

drivers/nvme/host/nvme.h

@@ -229,6 +229,7 @@ struct nvme_ctrl {
 	u32 page_size;
 	u32 max_hw_sectors;
 	u32 max_segments;
+	u32 max_integrity_segments;
 	u16 crdt[3];
 	u16 oncs;
 	u16 oacs;

drivers/nvme/host/pci.c

@@ -2565,6 +2565,12 @@ static void nvme_reset_work(struct work_struct *work)
 		goto out;
 	}
 
+	/*
+	 * We do not support an SGL for metadata (yet), so we are limited to a
+	 * single integrity segment for the separate metadata pointer.
+	 */
+	dev->ctrl.max_integrity_segments = 1;
+
 	result = nvme_init_identify(&dev->ctrl);
 	if (result)
 		goto out;