[PATCH v3 2/3] nvmet: Export NVMe namespace attributes

[bvanassche@acm.org (Bart Van Assche)]

Make the NVMe NAWUN, NAWUPF, NACWU, NPWG, NPWA, NPDG and NOWS attributes
available to initator systems.

Cc: Keith Busch <kbusch at kernel.org>
Cc: Sagi Grimberg <sagi at grimberg.me>
Cc: Martin K. Petersen <martin.petersen at oracle.com>
Cc: Hannes Reinecke <hare at suse.com>
Cc: Chaitanya Kulkarni <chaitanya.kulkarni at wdc.com>
Signed-off-by: Bart Van Assche <bvanassche at acm.org>
---
 drivers/nvme/target/admin-cmd.c   |  5 ++++
 drivers/nvme/target/io-cmd-bdev.c | 45 +++++++++++++++++++++++++++++++
 drivers/nvme/target/io-cmd-file.c | 37 +++++++++++++++++++++++++
 drivers/nvme/target/nvmet.h       |  2 ++
 4 files changed, 89 insertions(+)

diff --git a/drivers/nvme/target/admin-cmd.c b/drivers/nvme/target/admin-cmd.c
index 9f72d515fc4b..2558ed333d29 100644
--- a/drivers/nvme/target/admin-cmd.c
+++ b/drivers/nvme/target/admin-cmd.c
@@ -442,6 +442,11 @@ static void nvmet_execute_identify_ns(struct nvmet_req *req)
 		break;
         }
 
+	if (ns->file)
+		nvmet_file_set_limits(ns->file, id);
+	else if (ns->bdev)
+		nvmet_bdev_set_limits(ns->bdev, id);
+
 	/*
 	 * We just provide a single LBA format that matches what the
 	 * underlying device reports.
diff --git a/drivers/nvme/target/io-cmd-bdev.c b/drivers/nvme/target/io-cmd-bdev.c
index 3efc52f9c309..5fe51e5d2f1b 100644
--- a/drivers/nvme/target/io-cmd-bdev.c
+++ b/drivers/nvme/target/io-cmd-bdev.c
@@ -8,6 +8,51 @@
 #include <linux/module.h>
 #include "nvmet.h"
 
+/* Convert a 32-bit number to a 16-bit 0's based number */
+static __le16 to0based(u32 a)
+{
+	return cpu_to_le16(max(1U, min(1U << 16, a)) - 1);
+}
+
+void nvmet_bdev_set_limits(struct block_device *bdev, struct nvme_id_ns *id)
+{
+	const struct queue_limits *ql = &bdev_get_queue(bdev)->limits;
+	/* Number of physical blocks per logical block. */
+	const u32 ppl = ql->physical_block_size / ql->logical_block_size;
+	/* Physical blocks per logical block, 0's based. */
+	const __le16 ppl0b = to0based(ppl);
+
+	/*
+	 * For NVMe 1.2 and later, bit 1 indicates that the fields NAWUN,
+	 * NAWUPF, and NACWU are defined for this namespace and should be
+	 * used by the host for this namespace instead of the AWUN, AWUPF,
+	 * and ACWU fields in the Identify Controller data structure. If
+	 * any of these fields are zero that means that the corresponding
+	 * field from the identify controller data structure should be used.
+	 */
+	id->nsfeat |= 1 << 1;
+	id->nawun = ppl0b;
+	id->nawupf = ppl0b;
+	id->nacwu = ppl0b;
+
+	/*
+	 * For NVMe 1.4 and later, bit 4 indicates that the fields NPWG,
+	 * NPWA, NPDG, NPDA, and NOWS are defined for this namespace and
+	 * should be used by the host for I/O optimization.
+	 */
+	id->nsfeat |= 1 << 4;
+	/* NPWG = Namespace Preferred Write Granularity. 0's based */
+	id->npwg = ppl0b;
+	/* NPWA = Namespace Preferred Write Alignment. 0's based */
+	id->npwa = id->npwg;
+	/* NPDG = Namespace Preferred Deallocate Granularity. 0's based */
+	id->npdg = to0based(ql->discard_granularity / ql->logical_block_size);
+	/* NPDG = Namespace Preferred Deallocate Alignment */
+	id->npda = id->npdg;
+	/* NOWS = Namespace Optimal Write Size */
+	id->nows = to0based(ql->io_opt / ql->logical_block_size);
+}
+
 int nvmet_bdev_ns_enable(struct nvmet_ns *ns)
 {
 	int ret;
diff --git a/drivers/nvme/target/io-cmd-file.c b/drivers/nvme/target/io-cmd-file.c
index 05453f5d1448..268dfc678567 100644
--- a/drivers/nvme/target/io-cmd-file.c
+++ b/drivers/nvme/target/io-cmd-file.c
@@ -13,6 +13,43 @@
 #define NVMET_MAX_MPOOL_BVEC		16
 #define NVMET_MIN_MPOOL_OBJ		16
 
+void nvmet_file_set_limits(struct file *file, struct nvme_id_ns *id)
+{
+	/*
+	 * Physical blocks per logical block, 0's based. Is it possible to
+	 * extract this information from the filesystem properties?
+	 */
+	const __le16 ppl0b = cpu_to_le16(0);
+
+	/*
+	 * For NVMe 1.2 and later, bit 1 indicates that the fields NAWUN,
+	 * NAWUPF, and NACWU are defined for this namespace and should be
+	 * used by the host for this namespace instead of the AWUN, AWUPF,
+	 * and ACWU fields in the Identify Controller data structure.
+	 */
+	id->nsfeat |= 1 << 1;
+	id->nawun = ppl0b;
+	id->nawupf = ppl0b;
+	id->nacwu = ppl0b;
+
+	/*
+	 * For NVMe 1.4 and later, bit 4 indicates that the fields NPWG,
+	 * NPWA, NPDG, NPDA, and NOWS are defined for this namespace and
+	 * should be used by the host for I/O optimization.
+	 */
+	id->nsfeat |= 1 << 4;
+	/* NPWG = Namespace Preferred Write Granularity. 0's based */
+	id->npwg = ppl0b;
+	/* NPWA = Namespace Preferred Write Alignment. 0's based */
+	id->npwa = id->npwg;
+	/* NPDG = Namespace Preferred Deallocate Granularity. 0's based */
+	id->npdg = ppl0b;
+	/* NPDG = Namespace Preferred Deallocate Alignment */
+	id->npda = id->npdg;
+	/* NOWS = Namespace Optimal Write Size */
+	id->nows = ppl0b;
+}
+
 void nvmet_file_ns_disable(struct nvmet_ns *ns)
 {
 	if (ns->file) {
diff --git a/drivers/nvme/target/nvmet.h b/drivers/nvme/target/nvmet.h
index c25d88fc9dec..ed0362544932 100644
--- a/drivers/nvme/target/nvmet.h
+++ b/drivers/nvme/target/nvmet.h
@@ -363,6 +363,8 @@ u16 nvmet_set_feat_async_event(struct nvmet_req *req, u32 mask);
 void nvmet_execute_async_event(struct nvmet_req *req);
 
 u16 nvmet_parse_connect_cmd(struct nvmet_req *req);
+void nvmet_bdev_set_limits(struct block_device *bdev, struct nvme_id_ns *id);
+void nvmet_file_set_limits(struct file *file, struct nvme_id_ns *id);
 u16 nvmet_bdev_parse_io_cmd(struct nvmet_req *req);
 u16 nvmet_file_parse_io_cmd(struct nvmet_req *req);
 u16 nvmet_parse_admin_cmd(struct nvmet_req *req);
-- 
2.22.0.rc3