nvmet: add metadata characteristics for a namespace

Fill those namespace fields from the block device format for adding
metadata (T10-PI) over fabric support with block devices.
Signed-off-by: Israel Rukshin <israelr@mellanox.com>
Signed-off-by: Max Gurtovoy <maxg@mellanox.com>
Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>

drivers/nvme/target/Kconfig

@@ -4,6 +4,7 @@ config NVME_TARGET
 	tristate "NVMe Target support"
 	depends on BLOCK
 	depends on CONFIGFS_FS
+	select BLK_DEV_INTEGRITY_T10 if BLK_DEV_INTEGRITY
 	select SGL_ALLOC
 	help
 	  This enabled target side support for the NVMe protocol, that is

drivers/nvme/target/io-cmd-bdev.c

@@ -47,6 +47,22 @@ void nvmet_bdev_set_limits(struct block_device *bdev, struct nvme_id_ns *id)
 	id->nows = to0based(ql->io_opt / ql->logical_block_size);
 }
 
+static void nvmet_bdev_ns_enable_integrity(struct nvmet_ns *ns)
+{
+	struct blk_integrity *bi = bdev_get_integrity(ns->bdev);
+
+	if (bi) {
+		ns->metadata_size = bi->tuple_size;
+		if (bi->profile == &t10_pi_type1_crc)
+			ns->pi_type = NVME_NS_DPS_PI_TYPE1;
+		else if (bi->profile == &t10_pi_type3_crc)
+			ns->pi_type = NVME_NS_DPS_PI_TYPE3;
+		else
+			/* Unsupported metadata type */
+			ns->metadata_size = 0;
+	}
+}
+
 int nvmet_bdev_ns_enable(struct nvmet_ns *ns)
 {
 	int ret;
@@ -64,6 +80,12 @@ int nvmet_bdev_ns_enable(struct nvmet_ns *ns)
 	}
 	ns->size = i_size_read(ns->bdev->bd_inode);
 	ns->blksize_shift = blksize_bits(bdev_logical_block_size(ns->bdev));
+
+	ns->pi_type = 0;
+	ns->metadata_size = 0;
+	if (IS_ENABLED(CONFIG_BLK_DEV_INTEGRITY_T10))
+		nvmet_bdev_ns_enable_integrity(ns);
+
 	return 0;
 }
 

drivers/nvme/target/nvmet.h

@@ -19,6 +19,7 @@
 #include <linux/rcupdate.h>
 #include <linux/blkdev.h>
 #include <linux/radix-tree.h>
+#include <linux/t10-pi.h>
 
 #define NVMET_ASYNC_EVENTS		4
 #define NVMET_ERROR_LOG_SLOTS		128
@@ -77,6 +78,8 @@ struct nvmet_ns {
 
 	int			use_p2pmem;
 	struct pci_dev		*p2p_dev;
+	int			pi_type;
+	int			metadata_size;
 };
 
 static inline struct nvmet_ns *to_nvmet_ns(struct config_item *item)