nvmet: add a generic NVMe target

This patch introduces a implementation of NVMe subsystems,
controllers and discovery service which allows to export
NVMe namespaces across fabrics such as Ethernet, FC etc.

The implementation conforms to the NVMe 1.2.1 specification
and interoperates with NVMe over fabrics host implementations.

Configuration works using configfs, and is best performed using
the nvmetcli tool from http://git.infradead.org/users/hch/nvmetcli.git,
which also has a detailed explanation of the required steps in the
README file.

Signed-off-by: Armen Baloyan <armenx.baloyan@intel.com>
Signed-off-by: Anthony Knapp <anthony.j.knapp@intel.com>
Signed-off-by: Jay Freyensee <james.p.freyensee@intel.com>
Signed-off-by: Ming Lin <ming.l@ssi.samsung.com>
Signed-off-by: Sagi Grimberg <sagi@grimberg.me>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Steve Wise <swise@opengridcomputing.com>
Signed-off-by: Jens Axboe <axboe@fb.com>

1 files changed, 215 insertions, 0 deletions

diff --git a/drivers/nvme/target/io-cmd.c b/drivers/nvme/target/io-cmd.c
new file mode 100644
index 000000000000..2cd069b691ae
--- /dev/null
+++ b/drivers/nvme/target/io-cmd.c
@@ -0,0 +1,215 @@
+/*
+ * NVMe I/O command implementation.
+ * Copyright (c) 2015-2016 HGST, a Western Digital Company.
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms and conditions of the GNU General Public License,
+ * version 2, as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
+ * more details.
+ */
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+#include <linux/blkdev.h>
+#include <linux/module.h>
+#include "nvmet.h"
+
+static void nvmet_bio_done(struct bio *bio)
+{
+	struct nvmet_req *req = bio->bi_private;
+
+	nvmet_req_complete(req,
+		bio->bi_error ? NVME_SC_INTERNAL | NVME_SC_DNR : 0);
+
+	if (bio != &req->inline_bio)
+		bio_put(bio);
+}
+
+static inline u32 nvmet_rw_len(struct nvmet_req *req)
+{
+	return ((u32)le16_to_cpu(req->cmd->rw.length) + 1) <<
+			req->ns->blksize_shift;
+}
+
+static void nvmet_inline_bio_init(struct nvmet_req *req)
+{
+	struct bio *bio = &req->inline_bio;
+
+	bio_init(bio);
+	bio->bi_max_vecs = NVMET_MAX_INLINE_BIOVEC;
+	bio->bi_io_vec = req->inline_bvec;
+}
+
+static void nvmet_execute_rw(struct nvmet_req *req)
+{
+	int sg_cnt = req->sg_cnt;
+	struct scatterlist *sg;
+	struct bio *bio;
+	sector_t sector;
+	blk_qc_t cookie;
+	int op, op_flags = 0, i;
+
+	if (!req->sg_cnt) {
+		nvmet_req_complete(req, 0);
+		return;
+	}
+
+	if (req->cmd->rw.opcode == nvme_cmd_write) {
+		op = REQ_OP_WRITE;
+		if (req->cmd->rw.control & cpu_to_le16(NVME_RW_FUA))
+			op_flags |= REQ_FUA;
+	} else {
+		op = REQ_OP_READ;
+	}
+
+	sector = le64_to_cpu(req->cmd->rw.slba);
+	sector <<= (req->ns->blksize_shift - 9);
+
+	nvmet_inline_bio_init(req);
+	bio = &req->inline_bio;
+	bio->bi_bdev = req->ns->bdev;
+	bio->bi_iter.bi_sector = sector;
+	bio->bi_private = req;
+	bio->bi_end_io = nvmet_bio_done;
+	bio_set_op_attrs(bio, op, op_flags);
+
+	for_each_sg(req->sg, sg, req->sg_cnt, i) {
+		while (bio_add_page(bio, sg_page(sg), sg->length, sg->offset)
+				!= sg->length) {
+			struct bio *prev = bio;
+
+			bio = bio_alloc(GFP_KERNEL, min(sg_cnt, BIO_MAX_PAGES));
+			bio->bi_bdev = req->ns->bdev;
+			bio->bi_iter.bi_sector = sector;
+			bio_set_op_attrs(bio, op, op_flags);
+
+			bio_chain(bio, prev);
+			cookie = submit_bio(prev);
+		}
+
+		sector += sg->length >> 9;
+		sg_cnt--;
+	}
+
+	cookie = submit_bio(bio);
+
+	blk_poll(bdev_get_queue(req->ns->bdev), cookie);
+}
+
+static void nvmet_execute_flush(struct nvmet_req *req)
+{
+	struct bio *bio;
+
+	nvmet_inline_bio_init(req);
+	bio = &req->inline_bio;
+
+	bio->bi_bdev = req->ns->bdev;
+	bio->bi_private = req;
+	bio->bi_end_io = nvmet_bio_done;
+	bio_set_op_attrs(bio, REQ_OP_WRITE, WRITE_FLUSH);
+
+	submit_bio(bio);
+}
+
+static u16 nvmet_discard_range(struct nvmet_ns *ns,
+		struct nvme_dsm_range *range, struct bio **bio)
+{
+	if (__blkdev_issue_discard(ns->bdev,
+			le64_to_cpu(range->slba) << (ns->blksize_shift - 9),
+			le32_to_cpu(range->nlb) << (ns->blksize_shift - 9),
+			GFP_KERNEL, 0, bio))
+		return NVME_SC_INTERNAL | NVME_SC_DNR;
+	return 0;
+}
+
+static void nvmet_execute_discard(struct nvmet_req *req)
+{
+	struct nvme_dsm_range range;
+	struct bio *bio = NULL;
+	int i;
+	u16 status;
+
+	for (i = 0; i <= le32_to_cpu(req->cmd->dsm.nr); i++) {
+		status = nvmet_copy_from_sgl(req, i * sizeof(range), &range,
+				sizeof(range));
+		if (status)
+			break;
+
+		status = nvmet_discard_range(req->ns, &range, &bio);
+		if (status)
+			break;
+	}
+
+	if (bio) {
+		bio->bi_private = req;
+		bio->bi_end_io = nvmet_bio_done;
+		if (status) {
+			bio->bi_error = -EIO;
+			bio_endio(bio);
+		} else {
+			submit_bio(bio);
+		}
+	} else {
+		nvmet_req_complete(req, status);
+	}
+}
+
+static void nvmet_execute_dsm(struct nvmet_req *req)
+{
+	switch (le32_to_cpu(req->cmd->dsm.attributes)) {
+	case NVME_DSMGMT_AD:
+		nvmet_execute_discard(req);
+		return;
+	case NVME_DSMGMT_IDR:
+	case NVME_DSMGMT_IDW:
+	default:
+		/* Not supported yet */
+		nvmet_req_complete(req, 0);
+		return;
+	}
+}
+
+int nvmet_parse_io_cmd(struct nvmet_req *req)
+{
+	struct nvme_command *cmd = req->cmd;
+
+	if (unlikely(!(req->sq->ctrl->cc & NVME_CC_ENABLE))) {
+		pr_err("nvmet: got io cmd %d while CC.EN == 0\n",
+				cmd->common.opcode);
+		req->ns = NULL;
+		return NVME_SC_CMD_SEQ_ERROR | NVME_SC_DNR;
+	}
+
+	if (unlikely(!(req->sq->ctrl->csts & NVME_CSTS_RDY))) {
+		pr_err("nvmet: got io cmd %d while CSTS.RDY == 0\n",
+				cmd->common.opcode);
+		req->ns = NULL;
+		return NVME_SC_CMD_SEQ_ERROR | NVME_SC_DNR;
+	}
+
+	req->ns = nvmet_find_namespace(req->sq->ctrl, cmd->rw.nsid);
+	if (!req->ns)
+		return NVME_SC_INVALID_NS | NVME_SC_DNR;
+
+	switch (cmd->common.opcode) {
+	case nvme_cmd_read:
+	case nvme_cmd_write:
+		req->execute = nvmet_execute_rw;
+		req->data_len = nvmet_rw_len(req);
+		return 0;
+	case nvme_cmd_flush:
+		req->execute = nvmet_execute_flush;
+		req->data_len = 0;
+		return 0;
+	case nvme_cmd_dsm:
+		req->execute = nvmet_execute_dsm;
+		req->data_len = le32_to_cpu(cmd->dsm.nr) *
+			sizeof(struct nvme_dsm_range);
+		return 0;
+	default:
+		pr_err("nvmet: unhandled cmd %d\n", cmd->common.opcode);
+		return NVME_SC_INVALID_OPCODE | NVME_SC_DNR;
+	}
+}