NVMe:Remove unreachable code in nvme_abort_req

[mirror_ubuntu-bionic-kernel.git] / drivers / block / nvme-core.c

/*
 * NVM Express device driver
 * Copyright (c) 2011-2014, Intel Corporation.
 *
 * 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.
 */

#include <linux/nvme.h>
#include <linux/bitops.h>
#include <linux/blkdev.h>
#include <linux/blk-mq.h>
#include <linux/cpu.h>
#include <linux/delay.h>
#include <linux/errno.h>
#include <linux/fs.h>
#include <linux/genhd.h>
#include <linux/hdreg.h>
#include <linux/idr.h>
#include <linux/init.h>
#include <linux/interrupt.h>
#include <linux/io.h>
#include <linux/kdev_t.h>
#include <linux/kthread.h>
#include <linux/kernel.h>
#include <linux/list_sort.h>
#include <linux/mm.h>
#include <linux/module.h>
#include <linux/moduleparam.h>
#include <linux/pci.h>
#include <linux/poison.h>
#include <linux/ptrace.h>
#include <linux/sched.h>
#include <linux/slab.h>
#include <linux/t10-pi.h>
#include <linux/types.h>
#include <scsi/sg.h>
#include <asm-generic/io-64-nonatomic-lo-hi.h>

#define NVME_MINORS             (1U << MINORBITS)
#define NVME_Q_DEPTH            1024
#define NVME_AQ_DEPTH           256
#define SQ_SIZE(depth)          (depth * sizeof(struct nvme_command))
#define CQ_SIZE(depth)          (depth * sizeof(struct nvme_completion))
#define ADMIN_TIMEOUT           (admin_timeout * HZ)
#define SHUTDOWN_TIMEOUT        (shutdown_timeout * HZ)

static unsigned char admin_timeout = 60;
module_param(admin_timeout, byte, 0644);
MODULE_PARM_DESC(admin_timeout, "timeout in seconds for admin commands");

unsigned char nvme_io_timeout = 30;
module_param_named(io_timeout, nvme_io_timeout, byte, 0644);
MODULE_PARM_DESC(io_timeout, "timeout in seconds for I/O");

static unsigned char shutdown_timeout = 5;
module_param(shutdown_timeout, byte, 0644);
MODULE_PARM_DESC(shutdown_timeout, "timeout in seconds for controller shutdown");

static int nvme_major;
module_param(nvme_major, int, 0);

static int nvme_char_major;
module_param(nvme_char_major, int, 0);

static int use_threaded_interrupts;
module_param(use_threaded_interrupts, int, 0);

static bool use_cmb_sqes = true;
module_param(use_cmb_sqes, bool, 0644);
MODULE_PARM_DESC(use_cmb_sqes, "use controller's memory buffer for I/O SQes");

static DEFINE_SPINLOCK(dev_list_lock);
static LIST_HEAD(dev_list);
static struct task_struct *nvme_thread;
static struct workqueue_struct *nvme_workq;
static wait_queue_head_t nvme_kthread_wait;

static struct class *nvme_class;

static void nvme_reset_failed_dev(struct work_struct *ws);
static int nvme_reset(struct nvme_dev *dev);
static int nvme_process_cq(struct nvme_queue *nvmeq);

struct async_cmd_info {
        struct kthread_work work;
        struct kthread_worker *worker;
        struct request *req;
        u32 result;
        int status;
        void *ctx;
};

/*
 * An NVM Express queue.  Each device has at least two (one for admin
 * commands and one for I/O commands).
 */
struct nvme_queue {
        struct device *q_dmadev;
        struct nvme_dev *dev;
        char irqname[24];       /* nvme4294967295-65535\0 */
        spinlock_t q_lock;
        struct nvme_command *sq_cmds;
        struct nvme_command __iomem *sq_cmds_io;
        volatile struct nvme_completion *cqes;
        struct blk_mq_tags **tags;
        dma_addr_t sq_dma_addr;
        dma_addr_t cq_dma_addr;
        u32 __iomem *q_db;
        u16 q_depth;
        s16 cq_vector;
        u16 sq_head;
        u16 sq_tail;
        u16 cq_head;
        u16 qid;
        u8 cq_phase;
        u8 cqe_seen;
        struct async_cmd_info cmdinfo;
};

/*
 * Check we didin't inadvertently grow the command struct
 */
static inline void _nvme_check_size(void)
{
        BUILD_BUG_ON(sizeof(struct nvme_rw_command) != 64);
        BUILD_BUG_ON(sizeof(struct nvme_create_cq) != 64);
        BUILD_BUG_ON(sizeof(struct nvme_create_sq) != 64);
        BUILD_BUG_ON(sizeof(struct nvme_delete_queue) != 64);
        BUILD_BUG_ON(sizeof(struct nvme_features) != 64);
        BUILD_BUG_ON(sizeof(struct nvme_format_cmd) != 64);
        BUILD_BUG_ON(sizeof(struct nvme_abort_cmd) != 64);
        BUILD_BUG_ON(sizeof(struct nvme_command) != 64);
        BUILD_BUG_ON(sizeof(struct nvme_id_ctrl) != 4096);
        BUILD_BUG_ON(sizeof(struct nvme_id_ns) != 4096);
        BUILD_BUG_ON(sizeof(struct nvme_lba_range_type) != 64);
        BUILD_BUG_ON(sizeof(struct nvme_smart_log) != 512);
}

typedef void (*nvme_completion_fn)(struct nvme_queue *, void *,
                                                struct nvme_completion *);

struct nvme_cmd_info {
        nvme_completion_fn fn;
        void *ctx;
        int aborted;
        struct nvme_queue *nvmeq;
        struct nvme_iod iod[0];
};

/*
 * Max size of iod being embedded in the request payload
 */
#define NVME_INT_PAGES          2
#define NVME_INT_BYTES(dev)     (NVME_INT_PAGES * (dev)->page_size)
#define NVME_INT_MASK           0x01

/*
 * Will slightly overestimate the number of pages needed.  This is OK
 * as it only leads to a small amount of wasted memory for the lifetime of
 * the I/O.
 */
static int nvme_npages(unsigned size, struct nvme_dev *dev)
{
        unsigned nprps = DIV_ROUND_UP(size + dev->page_size, dev->page_size);
        return DIV_ROUND_UP(8 * nprps, PAGE_SIZE - 8);
}

static unsigned int nvme_cmd_size(struct nvme_dev *dev)
{
        unsigned int ret = sizeof(struct nvme_cmd_info);

        ret += sizeof(struct nvme_iod);
        ret += sizeof(__le64 *) * nvme_npages(NVME_INT_BYTES(dev), dev);
        ret += sizeof(struct scatterlist) * NVME_INT_PAGES;

        return ret;
}

static int nvme_admin_init_hctx(struct blk_mq_hw_ctx *hctx, void *data,
                                unsigned int hctx_idx)
{
        struct nvme_dev *dev = data;
        struct nvme_queue *nvmeq = dev->queues[0];

        WARN_ON(hctx_idx != 0);
        WARN_ON(dev->admin_tagset.tags[0] != hctx->tags);
        WARN_ON(nvmeq->tags);

        hctx->driver_data = nvmeq;
        nvmeq->tags = &dev->admin_tagset.tags[0];
        return 0;
}

static void nvme_admin_exit_hctx(struct blk_mq_hw_ctx *hctx, unsigned int hctx_idx)
{
        struct nvme_queue *nvmeq = hctx->driver_data;

        nvmeq->tags = NULL;
}

static int nvme_admin_init_request(void *data, struct request *req,
                                unsigned int hctx_idx, unsigned int rq_idx,
                                unsigned int numa_node)
{
        struct nvme_dev *dev = data;
        struct nvme_cmd_info *cmd = blk_mq_rq_to_pdu(req);
        struct nvme_queue *nvmeq = dev->queues[0];

        BUG_ON(!nvmeq);
        cmd->nvmeq = nvmeq;
        return 0;
}

static int nvme_init_hctx(struct blk_mq_hw_ctx *hctx, void *data,
                          unsigned int hctx_idx)
{
        struct nvme_dev *dev = data;
        struct nvme_queue *nvmeq = dev->queues[hctx_idx + 1];

        if (!nvmeq->tags)
                nvmeq->tags = &dev->tagset.tags[hctx_idx];

        WARN_ON(dev->tagset.tags[hctx_idx] != hctx->tags);
        hctx->driver_data = nvmeq;
        return 0;
}

static int nvme_init_request(void *data, struct request *req,
                                unsigned int hctx_idx, unsigned int rq_idx,
                                unsigned int numa_node)
{
        struct nvme_dev *dev = data;
        struct nvme_cmd_info *cmd = blk_mq_rq_to_pdu(req);
        struct nvme_queue *nvmeq = dev->queues[hctx_idx + 1];

        BUG_ON(!nvmeq);
        cmd->nvmeq = nvmeq;
        return 0;
}

static void nvme_set_info(struct nvme_cmd_info *cmd, void *ctx,
                                nvme_completion_fn handler)
{
        cmd->fn = handler;
        cmd->ctx = ctx;
        cmd->aborted = 0;
        blk_mq_start_request(blk_mq_rq_from_pdu(cmd));
}

static void *iod_get_private(struct nvme_iod *iod)
{
        return (void *) (iod->private & ~0x1UL);
}

/*
 * If bit 0 is set, the iod is embedded in the request payload.
 */
static bool iod_should_kfree(struct nvme_iod *iod)
{
        return (iod->private & NVME_INT_MASK) == 0;
}

/* Special values must be less than 0x1000 */
#define CMD_CTX_BASE            ((void *)POISON_POINTER_DELTA)
#define CMD_CTX_CANCELLED       (0x30C + CMD_CTX_BASE)
#define CMD_CTX_COMPLETED       (0x310 + CMD_CTX_BASE)
#define CMD_CTX_INVALID         (0x314 + CMD_CTX_BASE)

static void special_completion(struct nvme_queue *nvmeq, void *ctx,
                                                struct nvme_completion *cqe)
{
        if (ctx == CMD_CTX_CANCELLED)
                return;
        if (ctx == CMD_CTX_COMPLETED) {
                dev_warn(nvmeq->q_dmadev,
                                "completed id %d twice on queue %d\n",
                                cqe->command_id, le16_to_cpup(&cqe->sq_id));
                return;
        }
        if (ctx == CMD_CTX_INVALID) {
                dev_warn(nvmeq->q_dmadev,
                                "invalid id %d completed on queue %d\n",
                                cqe->command_id, le16_to_cpup(&cqe->sq_id));
                return;
        }
        dev_warn(nvmeq->q_dmadev, "Unknown special completion %p\n", ctx);
}

static void *cancel_cmd_info(struct nvme_cmd_info *cmd, nvme_completion_fn *fn)
{
        void *ctx;

        if (fn)
                *fn = cmd->fn;
        ctx = cmd->ctx;
        cmd->fn = special_completion;
        cmd->ctx = CMD_CTX_CANCELLED;
        return ctx;
}

static void async_req_completion(struct nvme_queue *nvmeq, void *ctx,
                                                struct nvme_completion *cqe)
{
        u32 result = le32_to_cpup(&cqe->result);
        u16 status = le16_to_cpup(&cqe->status) >> 1;

        if (status == NVME_SC_SUCCESS || status == NVME_SC_ABORT_REQ)
                ++nvmeq->dev->event_limit;
        if (status != NVME_SC_SUCCESS)
                return;

        switch (result & 0xff07) {
        case NVME_AER_NOTICE_NS_CHANGED:
                dev_info(nvmeq->q_dmadev, "rescanning\n");
                schedule_work(&nvmeq->dev->scan_work);
        default:
                dev_warn(nvmeq->q_dmadev, "async event result %08x\n", result);
        }
}

static void abort_completion(struct nvme_queue *nvmeq, void *ctx,
                                                struct nvme_completion *cqe)
{
        struct request *req = ctx;

        u16 status = le16_to_cpup(&cqe->status) >> 1;
        u32 result = le32_to_cpup(&cqe->result);

        blk_mq_free_request(req);

        dev_warn(nvmeq->q_dmadev, "Abort status:%x result:%x", status, result);
        ++nvmeq->dev->abort_limit;
}

static void async_completion(struct nvme_queue *nvmeq, void *ctx,
                                                struct nvme_completion *cqe)
{
        struct async_cmd_info *cmdinfo = ctx;
        cmdinfo->result = le32_to_cpup(&cqe->result);
        cmdinfo->status = le16_to_cpup(&cqe->status) >> 1;
        queue_kthread_work(cmdinfo->worker, &cmdinfo->work);
        blk_mq_free_request(cmdinfo->req);
}

static inline struct nvme_cmd_info *get_cmd_from_tag(struct nvme_queue *nvmeq,
                                  unsigned int tag)
{
        struct request *req = blk_mq_tag_to_rq(*nvmeq->tags, tag);

        return blk_mq_rq_to_pdu(req);
}

/*
 * Called with local interrupts disabled and the q_lock held.  May not sleep.
 */
static void *nvme_finish_cmd(struct nvme_queue *nvmeq, int tag,
                                                nvme_completion_fn *fn)
{
        struct nvme_cmd_info *cmd = get_cmd_from_tag(nvmeq, tag);
        void *ctx;
        if (tag >= nvmeq->q_depth) {
                *fn = special_completion;
                return CMD_CTX_INVALID;
        }
        if (fn)
                *fn = cmd->fn;
        ctx = cmd->ctx;
        cmd->fn = special_completion;
        cmd->ctx = CMD_CTX_COMPLETED;
        return ctx;
}

/**
 * nvme_submit_cmd() - Copy a command into a queue and ring the doorbell
 * @nvmeq: The queue to use
 * @cmd: The command to send
 *
 * Safe to use from interrupt context
 */
static void __nvme_submit_cmd(struct nvme_queue *nvmeq,
                                                struct nvme_command *cmd)
{
        u16 tail = nvmeq->sq_tail;

        if (nvmeq->sq_cmds_io)
                memcpy_toio(&nvmeq->sq_cmds_io[tail], cmd, sizeof(*cmd));
        else
                memcpy(&nvmeq->sq_cmds[tail], cmd, sizeof(*cmd));

        if (++tail == nvmeq->q_depth)
                tail = 0;
        writel(tail, nvmeq->q_db);
        nvmeq->sq_tail = tail;
}

static void nvme_submit_cmd(struct nvme_queue *nvmeq, struct nvme_command *cmd)
{
        unsigned long flags;
        spin_lock_irqsave(&nvmeq->q_lock, flags);
        __nvme_submit_cmd(nvmeq, cmd);
        spin_unlock_irqrestore(&nvmeq->q_lock, flags);
}

static __le64 **iod_list(struct nvme_iod *iod)
{
        return ((void *)iod) + iod->offset;
}

static inline void iod_init(struct nvme_iod *iod, unsigned nbytes,
                            unsigned nseg, unsigned long private)
{
        iod->private = private;
        iod->offset = offsetof(struct nvme_iod, sg[nseg]);
        iod->npages = -1;
        iod->length = nbytes;
        iod->nents = 0;
}

static struct nvme_iod *
__nvme_alloc_iod(unsigned nseg, unsigned bytes, struct nvme_dev *dev,
                 unsigned long priv, gfp_t gfp)
{
        struct nvme_iod *iod = kmalloc(sizeof(struct nvme_iod) +
                                sizeof(__le64 *) * nvme_npages(bytes, dev) +
                                sizeof(struct scatterlist) * nseg, gfp);

        if (iod)
                iod_init(iod, bytes, nseg, priv);

        return iod;
}

static struct nvme_iod *nvme_alloc_iod(struct request *rq, struct nvme_dev *dev,
                                       gfp_t gfp)
{
        unsigned size = !(rq->cmd_flags & REQ_DISCARD) ? blk_rq_bytes(rq) :
                                                sizeof(struct nvme_dsm_range);
        struct nvme_iod *iod;

        if (rq->nr_phys_segments <= NVME_INT_PAGES &&
            size <= NVME_INT_BYTES(dev)) {
                struct nvme_cmd_info *cmd = blk_mq_rq_to_pdu(rq);

                iod = cmd->iod;
                iod_init(iod, size, rq->nr_phys_segments,
                                (unsigned long) rq | NVME_INT_MASK);
                return iod;
        }

        return __nvme_alloc_iod(rq->nr_phys_segments, size, dev,
                                (unsigned long) rq, gfp);
}

static void nvme_free_iod(struct nvme_dev *dev, struct nvme_iod *iod)
{
        const int last_prp = dev->page_size / 8 - 1;
        int i;
        __le64 **list = iod_list(iod);
        dma_addr_t prp_dma = iod->first_dma;

        if (iod->npages == 0)
                dma_pool_free(dev->prp_small_pool, list[0], prp_dma);
        for (i = 0; i < iod->npages; i++) {
                __le64 *prp_list = list[i];
                dma_addr_t next_prp_dma = le64_to_cpu(prp_list[last_prp]);
                dma_pool_free(dev->prp_page_pool, prp_list, prp_dma);
                prp_dma = next_prp_dma;
        }

        if (iod_should_kfree(iod))
                kfree(iod);
}

static int nvme_error_status(u16 status)
{
        switch (status & 0x7ff) {
        case NVME_SC_SUCCESS:
                return 0;
        case NVME_SC_CAP_EXCEEDED:
                return -ENOSPC;
        default:
                return -EIO;
        }
}

#ifdef CONFIG_BLK_DEV_INTEGRITY
static void nvme_dif_prep(u32 p, u32 v, struct t10_pi_tuple *pi)
{
        if (be32_to_cpu(pi->ref_tag) == v)
                pi->ref_tag = cpu_to_be32(p);
}

static void nvme_dif_complete(u32 p, u32 v, struct t10_pi_tuple *pi)
{
        if (be32_to_cpu(pi->ref_tag) == p)
                pi->ref_tag = cpu_to_be32(v);
}

/**
 * nvme_dif_remap - remaps ref tags to bip seed and physical lba
 *
 * The virtual start sector is the one that was originally submitted by the
 * block layer. Due to partitioning, MD/DM cloning, etc. the actual physical
 * start sector may be different. Remap protection information to match the
 * physical LBA on writes, and back to the original seed on reads.
 *
 * Type 0 and 3 do not have a ref tag, so no remapping required.
 */
static void nvme_dif_remap(struct request *req,
                        void (*dif_swap)(u32 p, u32 v, struct t10_pi_tuple *pi))
{
        struct nvme_ns *ns = req->rq_disk->private_data;
        struct bio_integrity_payload *bip;
        struct t10_pi_tuple *pi;
        void *p, *pmap;
        u32 i, nlb, ts, phys, virt;

        if (!ns->pi_type || ns->pi_type == NVME_NS_DPS_PI_TYPE3)
                return;

        bip = bio_integrity(req->bio);
        if (!bip)
                return;

        pmap = kmap_atomic(bip->bip_vec->bv_page) + bip->bip_vec->bv_offset;

        p = pmap;
        virt = bip_get_seed(bip);
        phys = nvme_block_nr(ns, blk_rq_pos(req));
        nlb = (blk_rq_bytes(req) >> ns->lba_shift);
        ts = ns->disk->integrity->tuple_size;

        for (i = 0; i < nlb; i++, virt++, phys++) {
                pi = (struct t10_pi_tuple *)p;
                dif_swap(phys, virt, pi);
                p += ts;
        }
        kunmap_atomic(pmap);
}

static int nvme_noop_verify(struct blk_integrity_iter *iter)
{
        return 0;
}

static int nvme_noop_generate(struct blk_integrity_iter *iter)
{
        return 0;
}

struct blk_integrity nvme_meta_noop = {
        .name                   = "NVME_META_NOOP",
        .generate_fn            = nvme_noop_generate,
        .verify_fn              = nvme_noop_verify,
};

static void nvme_init_integrity(struct nvme_ns *ns)
{
        struct blk_integrity integrity;

        switch (ns->pi_type) {
        case NVME_NS_DPS_PI_TYPE3:
                integrity = t10_pi_type3_crc;
                break;
        case NVME_NS_DPS_PI_TYPE1:
        case NVME_NS_DPS_PI_TYPE2:
                integrity = t10_pi_type1_crc;
                break;
        default:
                integrity = nvme_meta_noop;
                break;
        }
        integrity.tuple_size = ns->ms;
        blk_integrity_register(ns->disk, &integrity);
        blk_queue_max_integrity_segments(ns->queue, 1);
}
#else /* CONFIG_BLK_DEV_INTEGRITY */
static void nvme_dif_remap(struct request *req,
                        void (*dif_swap)(u32 p, u32 v, struct t10_pi_tuple *pi))
{
}
static void nvme_dif_prep(u32 p, u32 v, struct t10_pi_tuple *pi)
{
}
static void nvme_dif_complete(u32 p, u32 v, struct t10_pi_tuple *pi)
{
}
static void nvme_init_integrity(struct nvme_ns *ns)
{
}
#endif

static void req_completion(struct nvme_queue *nvmeq, void *ctx,
                                                struct nvme_completion *cqe)
{
        struct nvme_iod *iod = ctx;
        struct request *req = iod_get_private(iod);
        struct nvme_cmd_info *cmd_rq = blk_mq_rq_to_pdu(req);

        u16 status = le16_to_cpup(&cqe->status) >> 1;

        if (unlikely(status)) {
                if (!(status & NVME_SC_DNR || blk_noretry_request(req))
                    && (jiffies - req->start_time) < req->timeout) {
                        unsigned long flags;

                        blk_mq_requeue_request(req);
                        spin_lock_irqsave(req->q->queue_lock, flags);
                        if (!blk_queue_stopped(req->q))
                                blk_mq_kick_requeue_list(req->q);
                        spin_unlock_irqrestore(req->q->queue_lock, flags);
                        return;
                }
                if (req->cmd_type == REQ_TYPE_DRV_PRIV) {
                        if (cmd_rq->ctx == CMD_CTX_CANCELLED)
                                req->errors = -EINTR;
                        else
                                req->errors = status;
                } else {
                        req->errors = nvme_error_status(status);
                }
        } else
                req->errors = 0;
        if (req->cmd_type == REQ_TYPE_DRV_PRIV) {
                u32 result = le32_to_cpup(&cqe->result);
                req->special = (void *)(uintptr_t)result;
        }

        if (cmd_rq->aborted)
                dev_warn(nvmeq->dev->dev,
                        "completing aborted command with status:%04x\n",
                        status);

        if (iod->nents) {
                dma_unmap_sg(nvmeq->dev->dev, iod->sg, iod->nents,
                        rq_data_dir(req) ? DMA_TO_DEVICE : DMA_FROM_DEVICE);
                if (blk_integrity_rq(req)) {
                        if (!rq_data_dir(req))
                                nvme_dif_remap(req, nvme_dif_complete);
                        dma_unmap_sg(nvmeq->dev->dev, iod->meta_sg, 1,
                                rq_data_dir(req) ? DMA_TO_DEVICE : DMA_FROM_DEVICE);
                }
        }
        nvme_free_iod(nvmeq->dev, iod);

        blk_mq_complete_request(req);
}

/* length is in bytes.  gfp flags indicates whether we may sleep. */
static int nvme_setup_prps(struct nvme_dev *dev, struct nvme_iod *iod,
                int total_len, gfp_t gfp)
{
        struct dma_pool *pool;
        int length = total_len;
        struct scatterlist *sg = iod->sg;
        int dma_len = sg_dma_len(sg);
        u64 dma_addr = sg_dma_address(sg);
        u32 page_size = dev->page_size;
        int offset = dma_addr & (page_size - 1);
        __le64 *prp_list;
        __le64 **list = iod_list(iod);
        dma_addr_t prp_dma;
        int nprps, i;

        length -= (page_size - offset);
        if (length <= 0)
                return total_len;

        dma_len -= (page_size - offset);
        if (dma_len) {
                dma_addr += (page_size - offset);
        } else {
                sg = sg_next(sg);
                dma_addr = sg_dma_address(sg);
                dma_len = sg_dma_len(sg);
        }

        if (length <= page_size) {
                iod->first_dma = dma_addr;
                return total_len;
        }

        nprps = DIV_ROUND_UP(length, page_size);
        if (nprps <= (256 / 8)) {
                pool = dev->prp_small_pool;
                iod->npages = 0;
        } else {
                pool = dev->prp_page_pool;
                iod->npages = 1;
        }

        prp_list = dma_pool_alloc(pool, gfp, &prp_dma);
        if (!prp_list) {
                iod->first_dma = dma_addr;
                iod->npages = -1;
                return (total_len - length) + page_size;
        }
        list[0] = prp_list;
        iod->first_dma = prp_dma;
        i = 0;
        for (;;) {
                if (i == page_size >> 3) {
                        __le64 *old_prp_list = prp_list;
                        prp_list = dma_pool_alloc(pool, gfp, &prp_dma);
                        if (!prp_list)
                                return total_len - length;
                        list[iod->npages++] = prp_list;
                        prp_list[0] = old_prp_list[i - 1];
                        old_prp_list[i - 1] = cpu_to_le64(prp_dma);
                        i = 1;
                }
                prp_list[i++] = cpu_to_le64(dma_addr);
                dma_len -= page_size;
                dma_addr += page_size;
                length -= page_size;
                if (length <= 0)
                        break;
                if (dma_len > 0)
                        continue;
                BUG_ON(dma_len < 0);
                sg = sg_next(sg);
                dma_addr = sg_dma_address(sg);
                dma_len = sg_dma_len(sg);
        }

        return total_len;
}

static void nvme_submit_priv(struct nvme_queue *nvmeq, struct request *req,
                struct nvme_iod *iod)
{
        struct nvme_command cmnd;

        memcpy(&cmnd, req->cmd, sizeof(cmnd));
        cmnd.rw.command_id = req->tag;
        if (req->nr_phys_segments) {
                cmnd.rw.prp1 = cpu_to_le64(sg_dma_address(iod->sg));
                cmnd.rw.prp2 = cpu_to_le64(iod->first_dma);
        }

        __nvme_submit_cmd(nvmeq, &cmnd);
}

/*
 * We reuse the small pool to allocate the 16-byte range here as it is not
 * worth having a special pool for these or additional cases to handle freeing
 * the iod.
 */
static void nvme_submit_discard(struct nvme_queue *nvmeq, struct nvme_ns *ns,
                struct request *req, struct nvme_iod *iod)
{
        struct nvme_dsm_range *range =
                                (struct nvme_dsm_range *)iod_list(iod)[0];
        struct nvme_command cmnd;

        range->cattr = cpu_to_le32(0);
        range->nlb = cpu_to_le32(blk_rq_bytes(req) >> ns->lba_shift);
        range->slba = cpu_to_le64(nvme_block_nr(ns, blk_rq_pos(req)));

        memset(&cmnd, 0, sizeof(cmnd));
        cmnd.dsm.opcode = nvme_cmd_dsm;
        cmnd.dsm.command_id = req->tag;
        cmnd.dsm.nsid = cpu_to_le32(ns->ns_id);
        cmnd.dsm.prp1 = cpu_to_le64(iod->first_dma);
        cmnd.dsm.nr = 0;
        cmnd.dsm.attributes = cpu_to_le32(NVME_DSMGMT_AD);

        __nvme_submit_cmd(nvmeq, &cmnd);
}

static void nvme_submit_flush(struct nvme_queue *nvmeq, struct nvme_ns *ns,
                                                                int cmdid)
{
        struct nvme_command cmnd;

        memset(&cmnd, 0, sizeof(cmnd));
        cmnd.common.opcode = nvme_cmd_flush;
        cmnd.common.command_id = cmdid;
        cmnd.common.nsid = cpu_to_le32(ns->ns_id);

        __nvme_submit_cmd(nvmeq, &cmnd);
}

static int nvme_submit_iod(struct nvme_queue *nvmeq, struct nvme_iod *iod,
                                                        struct nvme_ns *ns)
{
        struct request *req = iod_get_private(iod);
        struct nvme_command cmnd;
        u16 control = 0;
        u32 dsmgmt = 0;

        if (req->cmd_flags & REQ_FUA)
                control |= NVME_RW_FUA;
        if (req->cmd_flags & (REQ_FAILFAST_DEV | REQ_RAHEAD))
                control |= NVME_RW_LR;

        if (req->cmd_flags & REQ_RAHEAD)
                dsmgmt |= NVME_RW_DSM_FREQ_PREFETCH;

        memset(&cmnd, 0, sizeof(cmnd));
        cmnd.rw.opcode = (rq_data_dir(req) ? nvme_cmd_write : nvme_cmd_read);
        cmnd.rw.command_id = req->tag;
        cmnd.rw.nsid = cpu_to_le32(ns->ns_id);
        cmnd.rw.prp1 = cpu_to_le64(sg_dma_address(iod->sg));
        cmnd.rw.prp2 = cpu_to_le64(iod->first_dma);
        cmnd.rw.slba = cpu_to_le64(nvme_block_nr(ns, blk_rq_pos(req)));
        cmnd.rw.length = cpu_to_le16((blk_rq_bytes(req) >> ns->lba_shift) - 1);

        if (blk_integrity_rq(req)) {
                cmnd.rw.metadata = cpu_to_le64(sg_dma_address(iod->meta_sg));
                switch (ns->pi_type) {
                case NVME_NS_DPS_PI_TYPE3:
                        control |= NVME_RW_PRINFO_PRCHK_GUARD;
                        break;
                case NVME_NS_DPS_PI_TYPE1:
                case NVME_NS_DPS_PI_TYPE2:
                        control |= NVME_RW_PRINFO_PRCHK_GUARD |
                                        NVME_RW_PRINFO_PRCHK_REF;
                        cmnd.rw.reftag = cpu_to_le32(
                                        nvme_block_nr(ns, blk_rq_pos(req)));
                        break;
                }
        } else if (ns->ms)
                control |= NVME_RW_PRINFO_PRACT;

        cmnd.rw.control = cpu_to_le16(control);
        cmnd.rw.dsmgmt = cpu_to_le32(dsmgmt);

        __nvme_submit_cmd(nvmeq, &cmnd);

        return 0;
}

/*
 * NOTE: ns is NULL when called on the admin queue.
 */
static int nvme_queue_rq(struct blk_mq_hw_ctx *hctx,
                         const struct blk_mq_queue_data *bd)
{
        struct nvme_ns *ns = hctx->queue->queuedata;
        struct nvme_queue *nvmeq = hctx->driver_data;
        struct nvme_dev *dev = nvmeq->dev;
        struct request *req = bd->rq;
        struct nvme_cmd_info *cmd = blk_mq_rq_to_pdu(req);
        struct nvme_iod *iod;
        enum dma_data_direction dma_dir;

        /*
         * If formated with metadata, require the block layer provide a buffer
         * unless this namespace is formated such that the metadata can be
         * stripped/generated by the controller with PRACT=1.
         */
        if (ns && ns->ms && !blk_integrity_rq(req)) {
                if (!(ns->pi_type && ns->ms == 8) &&
                                        req->cmd_type != REQ_TYPE_DRV_PRIV) {
                        req->errors = -EFAULT;
                        blk_mq_complete_request(req);
                        return BLK_MQ_RQ_QUEUE_OK;
                }
        }

        iod = nvme_alloc_iod(req, dev, GFP_ATOMIC);
        if (!iod)
                return BLK_MQ_RQ_QUEUE_BUSY;

        if (req->cmd_flags & REQ_DISCARD) {
                void *range;
                /*
                 * We reuse the small pool to allocate the 16-byte range here
                 * as it is not worth having a special pool for these or
                 * additional cases to handle freeing the iod.
                 */
                range = dma_pool_alloc(dev->prp_small_pool, GFP_ATOMIC,
                                                &iod->first_dma);
                if (!range)
                        goto retry_cmd;
                iod_list(iod)[0] = (__le64 *)range;
                iod->npages = 0;
        } else if (req->nr_phys_segments) {
                dma_dir = rq_data_dir(req) ? DMA_TO_DEVICE : DMA_FROM_DEVICE;

                sg_init_table(iod->sg, req->nr_phys_segments);
                iod->nents = blk_rq_map_sg(req->q, req, iod->sg);
                if (!iod->nents)
                        goto error_cmd;

                if (!dma_map_sg(nvmeq->q_dmadev, iod->sg, iod->nents, dma_dir))
                        goto retry_cmd;

                if (blk_rq_bytes(req) !=
                    nvme_setup_prps(dev, iod, blk_rq_bytes(req), GFP_ATOMIC)) {
                        dma_unmap_sg(dev->dev, iod->sg, iod->nents, dma_dir);
                        goto retry_cmd;
                }
                if (blk_integrity_rq(req)) {
                        if (blk_rq_count_integrity_sg(req->q, req->bio) != 1)
                                goto error_cmd;

                        sg_init_table(iod->meta_sg, 1);
                        if (blk_rq_map_integrity_sg(
                                        req->q, req->bio, iod->meta_sg) != 1)
                                goto error_cmd;

                        if (rq_data_dir(req))
                                nvme_dif_remap(req, nvme_dif_prep);

                        if (!dma_map_sg(nvmeq->q_dmadev, iod->meta_sg, 1, dma_dir))
                                goto error_cmd;
                }
        }

        nvme_set_info(cmd, iod, req_completion);
        spin_lock_irq(&nvmeq->q_lock);
        if (req->cmd_type == REQ_TYPE_DRV_PRIV)
                nvme_submit_priv(nvmeq, req, iod);
        else if (req->cmd_flags & REQ_DISCARD)
                nvme_submit_discard(nvmeq, ns, req, iod);
        else if (req->cmd_flags & REQ_FLUSH)
                nvme_submit_flush(nvmeq, ns, req->tag);
        else
                nvme_submit_iod(nvmeq, iod, ns);

        nvme_process_cq(nvmeq);
        spin_unlock_irq(&nvmeq->q_lock);
        return BLK_MQ_RQ_QUEUE_OK;

 error_cmd:
        nvme_free_iod(dev, iod);
        return BLK_MQ_RQ_QUEUE_ERROR;
 retry_cmd:
        nvme_free_iod(dev, iod);
        return BLK_MQ_RQ_QUEUE_BUSY;
}

static int nvme_process_cq(struct nvme_queue *nvmeq)
{
        u16 head, phase;

        head = nvmeq->cq_head;
        phase = nvmeq->cq_phase;

        for (;;) {
                void *ctx;
                nvme_completion_fn fn;
                struct nvme_completion cqe = nvmeq->cqes[head];
                if ((le16_to_cpu(cqe.status) & 1) != phase)
                        break;
                nvmeq->sq_head = le16_to_cpu(cqe.sq_head);
                if (++head == nvmeq->q_depth) {
                        head = 0;
                        phase = !phase;
                }
                ctx = nvme_finish_cmd(nvmeq, cqe.command_id, &fn);
                fn(nvmeq, ctx, &cqe);
        }

        /* If the controller ignores the cq head doorbell and continuously
         * writes to the queue, it is theoretically possible to wrap around
         * the queue twice and mistakenly return IRQ_NONE.  Linux only
         * requires that 0.1% of your interrupts are handled, so this isn't
         * a big problem.
         */
        if (head == nvmeq->cq_head && phase == nvmeq->cq_phase)
                return 0;

        writel(head, nvmeq->q_db + nvmeq->dev->db_stride);
        nvmeq->cq_head = head;
        nvmeq->cq_phase = phase;

        nvmeq->cqe_seen = 1;
        return 1;
}

static irqreturn_t nvme_irq(int irq, void *data)
{
        irqreturn_t result;
        struct nvme_queue *nvmeq = data;
        spin_lock(&nvmeq->q_lock);
        nvme_process_cq(nvmeq);
        result = nvmeq->cqe_seen ? IRQ_HANDLED : IRQ_NONE;
        nvmeq->cqe_seen = 0;
        spin_unlock(&nvmeq->q_lock);
        return result;
}

static irqreturn_t nvme_irq_check(int irq, void *data)
{
        struct nvme_queue *nvmeq = data;
        struct nvme_completion cqe = nvmeq->cqes[nvmeq->cq_head];
        if ((le16_to_cpu(cqe.status) & 1) != nvmeq->cq_phase)
                return IRQ_NONE;
        return IRQ_WAKE_THREAD;
}

/*
 * Returns 0 on success.  If the result is negative, it's a Linux error code;
 * if the result is positive, it's an NVM Express status code
 */
int __nvme_submit_sync_cmd(struct request_queue *q, struct nvme_command *cmd,
                void *buffer, void __user *ubuffer, unsigned bufflen,
                u32 *result, unsigned timeout)
{
        bool write = cmd->common.opcode & 1;
        struct bio *bio = NULL;
        struct request *req;
        int ret;

        req = blk_mq_alloc_request(q, write, GFP_KERNEL, false);
        if (IS_ERR(req))
                return PTR_ERR(req);

        req->cmd_type = REQ_TYPE_DRV_PRIV;
        req->cmd_flags |= REQ_FAILFAST_DRIVER;
        req->__data_len = 0;
        req->__sector = (sector_t) -1;
        req->bio = req->biotail = NULL;

        req->timeout = timeout ? timeout : ADMIN_TIMEOUT;

        req->cmd = (unsigned char *)cmd;
        req->cmd_len = sizeof(struct nvme_command);
        req->special = (void *)0;

        if (buffer && bufflen) {
                ret = blk_rq_map_kern(q, req, buffer, bufflen, __GFP_WAIT);
                if (ret)
                        goto out;
        } else if (ubuffer && bufflen) {
                ret = blk_rq_map_user(q, req, NULL, ubuffer, bufflen, __GFP_WAIT);
                if (ret)
                        goto out;
                bio = req->bio;
        }

        blk_execute_rq(req->q, NULL, req, 0);
        if (bio)
                blk_rq_unmap_user(bio);
        if (result)
                *result = (u32)(uintptr_t)req->special;
        ret = req->errors;
 out:
        blk_mq_free_request(req);
        return ret;
}

int nvme_submit_sync_cmd(struct request_queue *q, struct nvme_command *cmd,
                void *buffer, unsigned bufflen)
{
        return __nvme_submit_sync_cmd(q, cmd, buffer, NULL, bufflen, NULL, 0);
}

static int nvme_submit_async_admin_req(struct nvme_dev *dev)
{
        struct nvme_queue *nvmeq = dev->queues[0];
        struct nvme_command c;
        struct nvme_cmd_info *cmd_info;
        struct request *req;

        req = blk_mq_alloc_request(dev->admin_q, WRITE, GFP_ATOMIC, true);
        if (IS_ERR(req))
                return PTR_ERR(req);

        req->cmd_flags |= REQ_NO_TIMEOUT;
        cmd_info = blk_mq_rq_to_pdu(req);
        nvme_set_info(cmd_info, NULL, async_req_completion);

        memset(&c, 0, sizeof(c));
        c.common.opcode = nvme_admin_async_event;
        c.common.command_id = req->tag;

        blk_mq_free_request(req);
        __nvme_submit_cmd(nvmeq, &c);
        return 0;
}

static int nvme_submit_admin_async_cmd(struct nvme_dev *dev,
                        struct nvme_command *cmd,
                        struct async_cmd_info *cmdinfo, unsigned timeout)
{
        struct nvme_queue *nvmeq = dev->queues[0];
        struct request *req;
        struct nvme_cmd_info *cmd_rq;

        req = blk_mq_alloc_request(dev->admin_q, WRITE, GFP_KERNEL, false);
        if (IS_ERR(req))
                return PTR_ERR(req);

        req->timeout = timeout;
        cmd_rq = blk_mq_rq_to_pdu(req);
        cmdinfo->req = req;
        nvme_set_info(cmd_rq, cmdinfo, async_completion);
        cmdinfo->status = -EINTR;

        cmd->common.command_id = req->tag;

        nvme_submit_cmd(nvmeq, cmd);
        return 0;
}

static int adapter_delete_queue(struct nvme_dev *dev, u8 opcode, u16 id)
{
        struct nvme_command c;

        memset(&c, 0, sizeof(c));
        c.delete_queue.opcode = opcode;
        c.delete_queue.qid = cpu_to_le16(id);

        return nvme_submit_sync_cmd(dev->admin_q, &c, NULL, 0);
}

static int adapter_alloc_cq(struct nvme_dev *dev, u16 qid,
                                                struct nvme_queue *nvmeq)
{
        struct nvme_command c;
        int flags = NVME_QUEUE_PHYS_CONTIG | NVME_CQ_IRQ_ENABLED;

        /*
         * Note: we (ab)use the fact the the prp fields survive if no data
         * is attached to the request.
         */
        memset(&c, 0, sizeof(c));
        c.create_cq.opcode = nvme_admin_create_cq;
        c.create_cq.prp1 = cpu_to_le64(nvmeq->cq_dma_addr);
        c.create_cq.cqid = cpu_to_le16(qid);
        c.create_cq.qsize = cpu_to_le16(nvmeq->q_depth - 1);
        c.create_cq.cq_flags = cpu_to_le16(flags);
        c.create_cq.irq_vector = cpu_to_le16(nvmeq->cq_vector);

        return nvme_submit_sync_cmd(dev->admin_q, &c, NULL, 0);
}

static int adapter_alloc_sq(struct nvme_dev *dev, u16 qid,
                                                struct nvme_queue *nvmeq)
{
        struct nvme_command c;
        int flags = NVME_QUEUE_PHYS_CONTIG | NVME_SQ_PRIO_MEDIUM;

        /*
         * Note: we (ab)use the fact the the prp fields survive if no data
         * is attached to the request.
         */
        memset(&c, 0, sizeof(c));
        c.create_sq.opcode = nvme_admin_create_sq;
        c.create_sq.prp1 = cpu_to_le64(nvmeq->sq_dma_addr);
        c.create_sq.sqid = cpu_to_le16(qid);
        c.create_sq.qsize = cpu_to_le16(nvmeq->q_depth - 1);
        c.create_sq.sq_flags = cpu_to_le16(flags);
        c.create_sq.cqid = cpu_to_le16(qid);

        return nvme_submit_sync_cmd(dev->admin_q, &c, NULL, 0);
}

static int adapter_delete_cq(struct nvme_dev *dev, u16 cqid)
{
        return adapter_delete_queue(dev, nvme_admin_delete_cq, cqid);
}

static int adapter_delete_sq(struct nvme_dev *dev, u16 sqid)
{
        return adapter_delete_queue(dev, nvme_admin_delete_sq, sqid);
}

int nvme_identify_ctrl(struct nvme_dev *dev, struct nvme_id_ctrl **id)
{
        struct nvme_command c = { };
        int error;

        /* gcc-4.4.4 (at least) has issues with initializers and anon unions */
        c.identify.opcode = nvme_admin_identify;
        c.identify.cns = cpu_to_le32(1);

        *id = kmalloc(sizeof(struct nvme_id_ctrl), GFP_KERNEL);
        if (!*id)
                return -ENOMEM;

        error = nvme_submit_sync_cmd(dev->admin_q, &c, *id,
                        sizeof(struct nvme_id_ctrl));
        if (error)
                kfree(*id);
        return error;
}

int nvme_identify_ns(struct nvme_dev *dev, unsigned nsid,
                struct nvme_id_ns **id)
{
        struct nvme_command c = { };
        int error;

        /* gcc-4.4.4 (at least) has issues with initializers and anon unions */
        c.identify.opcode = nvme_admin_identify,
        c.identify.nsid = cpu_to_le32(nsid),

        *id = kmalloc(sizeof(struct nvme_id_ns), GFP_KERNEL);
        if (!*id)
                return -ENOMEM;

        error = nvme_submit_sync_cmd(dev->admin_q, &c, *id,
                        sizeof(struct nvme_id_ns));
        if (error)
                kfree(*id);
        return error;
}

int nvme_get_features(struct nvme_dev *dev, unsigned fid, unsigned nsid,
                                        dma_addr_t dma_addr, u32 *result)
{
        struct nvme_command c;

        memset(&c, 0, sizeof(c));
        c.features.opcode = nvme_admin_get_features;
        c.features.nsid = cpu_to_le32(nsid);
        c.features.prp1 = cpu_to_le64(dma_addr);
        c.features.fid = cpu_to_le32(fid);

        return __nvme_submit_sync_cmd(dev->admin_q, &c, NULL, NULL, 0,
                        result, 0);
}

int nvme_set_features(struct nvme_dev *dev, unsigned fid, unsigned dword11,
                                        dma_addr_t dma_addr, u32 *result)
{
        struct nvme_command c;

        memset(&c, 0, sizeof(c));
        c.features.opcode = nvme_admin_set_features;
        c.features.prp1 = cpu_to_le64(dma_addr);
        c.features.fid = cpu_to_le32(fid);
        c.features.dword11 = cpu_to_le32(dword11);

        return __nvme_submit_sync_cmd(dev->admin_q, &c, NULL, NULL, 0,
                        result, 0);
}

int nvme_get_log_page(struct nvme_dev *dev, struct nvme_smart_log **log)
{
        struct nvme_command c = { };
        int error;

        c.common.opcode = nvme_admin_get_log_page,
        c.common.nsid = cpu_to_le32(0xFFFFFFFF),
        c.common.cdw10[0] = cpu_to_le32(
                        (((sizeof(struct nvme_smart_log) / 4) - 1) << 16) |
                         NVME_LOG_SMART),

        *log = kmalloc(sizeof(struct nvme_smart_log), GFP_KERNEL);
        if (!*log)
                return -ENOMEM;

        error = nvme_submit_sync_cmd(dev->admin_q, &c, *log,
                        sizeof(struct nvme_smart_log));
        if (error)
                kfree(*log);
        return error;
}

/**
 * nvme_abort_req - Attempt aborting a request
 *
 * Schedule controller reset if the command was already aborted once before and
 * still hasn't been returned to the driver, or if this is the admin queue.
 */
static void nvme_abort_req(struct request *req)
{
        struct nvme_cmd_info *cmd_rq = blk_mq_rq_to_pdu(req);
        struct nvme_queue *nvmeq = cmd_rq->nvmeq;
        struct nvme_dev *dev = nvmeq->dev;
        struct request *abort_req;
        struct nvme_cmd_info *abort_cmd;
        struct nvme_command cmd;

        if (!nvmeq->qid || cmd_rq->aborted) {
                unsigned long flags;

                spin_lock_irqsave(&dev_list_lock, flags);
                if (work_busy(&dev->reset_work))
                        goto out;
                list_del_init(&dev->node);
                dev_warn(dev->dev, "I/O %d QID %d timeout, reset controller\n",
                                                        req->tag, nvmeq->qid);
                dev->reset_workfn = nvme_reset_failed_dev;
                queue_work(nvme_workq, &dev->reset_work);
 out:
                spin_unlock_irqrestore(&dev_list_lock, flags);
                return;
        }

        if (!dev->abort_limit)
                return;

        abort_req = blk_mq_alloc_request(dev->admin_q, WRITE, GFP_ATOMIC,
                                                                        false);
        if (IS_ERR(abort_req))
                return;

        abort_cmd = blk_mq_rq_to_pdu(abort_req);
        nvme_set_info(abort_cmd, abort_req, abort_completion);

        memset(&cmd, 0, sizeof(cmd));
        cmd.abort.opcode = nvme_admin_abort_cmd;
        cmd.abort.cid = req->tag;
        cmd.abort.sqid = cpu_to_le16(nvmeq->qid);
        cmd.abort.command_id = abort_req->tag;

        --dev->abort_limit;
        cmd_rq->aborted = 1;

        dev_warn(nvmeq->q_dmadev, "Aborting I/O %d QID %d\n", req->tag,
                                                        nvmeq->qid);
        nvme_submit_cmd(dev->queues[0], &cmd);
}

static void nvme_cancel_queue_ios(struct request *req, void *data, bool reserved)
{
        struct nvme_queue *nvmeq = data;
        void *ctx;
        nvme_completion_fn fn;
        struct nvme_cmd_info *cmd;
        struct nvme_completion cqe;

        if (!blk_mq_request_started(req))
                return;

        cmd = blk_mq_rq_to_pdu(req);

        if (cmd->ctx == CMD_CTX_CANCELLED)
                return;

        if (blk_queue_dying(req->q))
                cqe.status = cpu_to_le16((NVME_SC_ABORT_REQ | NVME_SC_DNR) << 1);
        else
                cqe.status = cpu_to_le16(NVME_SC_ABORT_REQ << 1);


        dev_warn(nvmeq->q_dmadev, "Cancelling I/O %d QID %d\n",
                                                req->tag, nvmeq->qid);
        ctx = cancel_cmd_info(cmd, &fn);
        fn(nvmeq, ctx, &cqe);
}

static enum blk_eh_timer_return nvme_timeout(struct request *req, bool reserved)
{
        struct nvme_cmd_info *cmd = blk_mq_rq_to_pdu(req);
        struct nvme_queue *nvmeq = cmd->nvmeq;

        dev_warn(nvmeq->q_dmadev, "Timeout I/O %d QID %d\n", req->tag,
                                                        nvmeq->qid);
        spin_lock_irq(&nvmeq->q_lock);
        nvme_abort_req(req);
        spin_unlock_irq(&nvmeq->q_lock);

        /*
         * The aborted req will be completed on receiving the abort req.
         * We enable the timer again. If hit twice, it'll cause a device reset,
         * as the device then is in a faulty state.
         */
        return BLK_EH_RESET_TIMER;
}

static void nvme_free_queue(struct nvme_queue *nvmeq)
{
        dma_free_coherent(nvmeq->q_dmadev, CQ_SIZE(nvmeq->q_depth),
                                (void *)nvmeq->cqes, nvmeq->cq_dma_addr);
        if (nvmeq->sq_cmds)
                dma_free_coherent(nvmeq->q_dmadev, SQ_SIZE(nvmeq->q_depth),
                                        nvmeq->sq_cmds, nvmeq->sq_dma_addr);
        kfree(nvmeq);
}

static void nvme_free_queues(struct nvme_dev *dev, int lowest)
{
        int i;

        for (i = dev->queue_count - 1; i >= lowest; i--) {
                struct nvme_queue *nvmeq = dev->queues[i];
                dev->queue_count--;
                dev->queues[i] = NULL;
                nvme_free_queue(nvmeq);
        }
}

/**
 * nvme_suspend_queue - put queue into suspended state
 * @nvmeq - queue to suspend
 */
static int nvme_suspend_queue(struct nvme_queue *nvmeq)
{
        int vector;

        spin_lock_irq(&nvmeq->q_lock);
        if (nvmeq->cq_vector == -1) {
                spin_unlock_irq(&nvmeq->q_lock);
                return 1;
        }
        vector = nvmeq->dev->entry[nvmeq->cq_vector].vector;
        nvmeq->dev->online_queues--;
        nvmeq->cq_vector = -1;
        spin_unlock_irq(&nvmeq->q_lock);

        if (!nvmeq->qid && nvmeq->dev->admin_q)
                blk_mq_freeze_queue_start(nvmeq->dev->admin_q);

        irq_set_affinity_hint(vector, NULL);
        free_irq(vector, nvmeq);

        return 0;
}

static void nvme_clear_queue(struct nvme_queue *nvmeq)
{
        spin_lock_irq(&nvmeq->q_lock);
        if (nvmeq->tags && *nvmeq->tags)
                blk_mq_all_tag_busy_iter(*nvmeq->tags, nvme_cancel_queue_ios, nvmeq);
        spin_unlock_irq(&nvmeq->q_lock);
}

static void nvme_disable_queue(struct nvme_dev *dev, int qid)
{
        struct nvme_queue *nvmeq = dev->queues[qid];

        if (!nvmeq)
                return;
        if (nvme_suspend_queue(nvmeq))
                return;

        /* Don't tell the adapter to delete the admin queue.
         * Don't tell a removed adapter to delete IO queues. */
        if (qid && readl(&dev->bar->csts) != -1) {
                adapter_delete_sq(dev, qid);
                adapter_delete_cq(dev, qid);
        }

        spin_lock_irq(&nvmeq->q_lock);
        nvme_process_cq(nvmeq);
        spin_unlock_irq(&nvmeq->q_lock);
}

static int nvme_cmb_qdepth(struct nvme_dev *dev, int nr_io_queues,
                                int entry_size)
{
        int q_depth = dev->q_depth;
        unsigned q_size_aligned = roundup(q_depth * entry_size, dev->page_size);

        if (q_size_aligned * nr_io_queues > dev->cmb_size) {
                u64 mem_per_q = div_u64(dev->cmb_size, nr_io_queues);
                mem_per_q = round_down(mem_per_q, dev->page_size);
                q_depth = div_u64(mem_per_q, entry_size);

                /*
                 * Ensure the reduced q_depth is above some threshold where it
                 * would be better to map queues in system memory with the
                 * original depth
                 */
                if (q_depth < 64)
                        return -ENOMEM;
        }

        return q_depth;
}

static int nvme_alloc_sq_cmds(struct nvme_dev *dev, struct nvme_queue *nvmeq,
                                int qid, int depth)
{
        if (qid && dev->cmb && use_cmb_sqes && NVME_CMB_SQS(dev->cmbsz)) {
                unsigned offset = (qid - 1) *
                                        roundup(SQ_SIZE(depth), dev->page_size);
                nvmeq->sq_dma_addr = dev->cmb_dma_addr + offset;
                nvmeq->sq_cmds_io = dev->cmb + offset;
        } else {
                nvmeq->sq_cmds = dma_alloc_coherent(dev->dev, SQ_SIZE(depth),
                                        &nvmeq->sq_dma_addr, GFP_KERNEL);
                if (!nvmeq->sq_cmds)
                        return -ENOMEM;
        }

        return 0;
}

static struct nvme_queue *nvme_alloc_queue(struct nvme_dev *dev, int qid,
                                                        int depth)
{
        struct nvme_queue *nvmeq = kzalloc(sizeof(*nvmeq), GFP_KERNEL);
        if (!nvmeq)
                return NULL;

        nvmeq->cqes = dma_zalloc_coherent(dev->dev, CQ_SIZE(depth),
                                          &nvmeq->cq_dma_addr, GFP_KERNEL);
        if (!nvmeq->cqes)
                goto free_nvmeq;

        if (nvme_alloc_sq_cmds(dev, nvmeq, qid, depth))
                goto free_cqdma;

        nvmeq->q_dmadev = dev->dev;
        nvmeq->dev = dev;
        snprintf(nvmeq->irqname, sizeof(nvmeq->irqname), "nvme%dq%d",
                        dev->instance, qid);
        spin_lock_init(&nvmeq->q_lock);
        nvmeq->cq_head = 0;
        nvmeq->cq_phase = 1;
        nvmeq->q_db = &dev->dbs[qid * 2 * dev->db_stride];
        nvmeq->q_depth = depth;
        nvmeq->qid = qid;
        nvmeq->cq_vector = -1;
        dev->queues[qid] = nvmeq;

        /* make sure queue descriptor is set before queue count, for kthread */
        mb();
        dev->queue_count++;

        return nvmeq;

 free_cqdma:
        dma_free_coherent(dev->dev, CQ_SIZE(depth), (void *)nvmeq->cqes,
                                                        nvmeq->cq_dma_addr);
 free_nvmeq:
        kfree(nvmeq);
        return NULL;
}

static int queue_request_irq(struct nvme_dev *dev, struct nvme_queue *nvmeq,
                                                        const char *name)
{
        if (use_threaded_interrupts)
                return request_threaded_irq(dev->entry[nvmeq->cq_vector].vector,
                                        nvme_irq_check, nvme_irq, IRQF_SHARED,
                                        name, nvmeq);
        return request_irq(dev->entry[nvmeq->cq_vector].vector, nvme_irq,
                                IRQF_SHARED, name, nvmeq);
}

static void nvme_init_queue(struct nvme_queue *nvmeq, u16 qid)
{
        struct nvme_dev *dev = nvmeq->dev;

        spin_lock_irq(&nvmeq->q_lock);
        nvmeq->sq_tail = 0;
        nvmeq->cq_head = 0;
        nvmeq->cq_phase = 1;
        nvmeq->q_db = &dev->dbs[qid * 2 * dev->db_stride];
        memset((void *)nvmeq->cqes, 0, CQ_SIZE(nvmeq->q_depth));
        dev->online_queues++;
        spin_unlock_irq(&nvmeq->q_lock);
}

static int nvme_create_queue(struct nvme_queue *nvmeq, int qid)
{
        struct nvme_dev *dev = nvmeq->dev;
        int result;

        nvmeq->cq_vector = qid - 1;
        result = adapter_alloc_cq(dev, qid, nvmeq);
        if (result < 0)
                return result;

        result = adapter_alloc_sq(dev, qid, nvmeq);
        if (result < 0)
                goto release_cq;

        result = queue_request_irq(dev, nvmeq, nvmeq->irqname);
        if (result < 0)
                goto release_sq;

        nvme_init_queue(nvmeq, qid);
        return result;

 release_sq:
        adapter_delete_sq(dev, qid);
 release_cq:
        adapter_delete_cq(dev, qid);
        return result;
}

static int nvme_wait_ready(struct nvme_dev *dev, u64 cap, bool enabled)
{
        unsigned long timeout;
        u32 bit = enabled ? NVME_CSTS_RDY : 0;

        timeout = ((NVME_CAP_TIMEOUT(cap) + 1) * HZ / 2) + jiffies;

        while ((readl(&dev->bar->csts) & NVME_CSTS_RDY) != bit) {
                msleep(100);
                if (fatal_signal_pending(current))
                        return -EINTR;
                if (time_after(jiffies, timeout)) {
                        dev_err(dev->dev,
                                "Device not ready; aborting %s\n", enabled ?
                                                "initialisation" : "reset");
                        return -ENODEV;
                }
        }

        return 0;
}

/*
 * If the device has been passed off to us in an enabled state, just clear
 * the enabled bit.  The spec says we should set the 'shutdown notification
 * bits', but doing so may cause the device to complete commands to the
 * admin queue ... and we don't know what memory that might be pointing at!
 */
static int nvme_disable_ctrl(struct nvme_dev *dev, u64 cap)
{
        dev->ctrl_config &= ~NVME_CC_SHN_MASK;
        dev->ctrl_config &= ~NVME_CC_ENABLE;
        writel(dev->ctrl_config, &dev->bar->cc);

        return nvme_wait_ready(dev, cap, false);
}

static int nvme_enable_ctrl(struct nvme_dev *dev, u64 cap)
{
        dev->ctrl_config &= ~NVME_CC_SHN_MASK;
        dev->ctrl_config |= NVME_CC_ENABLE;
        writel(dev->ctrl_config, &dev->bar->cc);

        return nvme_wait_ready(dev, cap, true);
}

static int nvme_shutdown_ctrl(struct nvme_dev *dev)
{
        unsigned long timeout;

        dev->ctrl_config &= ~NVME_CC_SHN_MASK;
        dev->ctrl_config |= NVME_CC_SHN_NORMAL;

        writel(dev->ctrl_config, &dev->bar->cc);

        timeout = SHUTDOWN_TIMEOUT + jiffies;
        while ((readl(&dev->bar->csts) & NVME_CSTS_SHST_MASK) !=
                                                        NVME_CSTS_SHST_CMPLT) {
                msleep(100);
                if (fatal_signal_pending(current))
                        return -EINTR;
                if (time_after(jiffies, timeout)) {
                        dev_err(dev->dev,
                                "Device shutdown incomplete; abort shutdown\n");
                        return -ENODEV;
                }
        }

        return 0;
}

static struct blk_mq_ops nvme_mq_admin_ops = {
        .queue_rq       = nvme_queue_rq,
        .map_queue      = blk_mq_map_queue,
        .init_hctx      = nvme_admin_init_hctx,
        .exit_hctx      = nvme_admin_exit_hctx,
        .init_request   = nvme_admin_init_request,
        .timeout        = nvme_timeout,
};

static struct blk_mq_ops nvme_mq_ops = {
        .queue_rq       = nvme_queue_rq,
        .map_queue      = blk_mq_map_queue,
        .init_hctx      = nvme_init_hctx,
        .init_request   = nvme_init_request,
        .timeout        = nvme_timeout,
};

static void nvme_dev_remove_admin(struct nvme_dev *dev)
{
        if (dev->admin_q && !blk_queue_dying(dev->admin_q)) {
                blk_cleanup_queue(dev->admin_q);
                blk_mq_free_tag_set(&dev->admin_tagset);
        }
}

static int nvme_alloc_admin_tags(struct nvme_dev *dev)
{
        if (!dev->admin_q) {
                dev->admin_tagset.ops = &nvme_mq_admin_ops;
                dev->admin_tagset.nr_hw_queues = 1;
                dev->admin_tagset.queue_depth = NVME_AQ_DEPTH - 1;
                dev->admin_tagset.reserved_tags = 1;
                dev->admin_tagset.timeout = ADMIN_TIMEOUT;
                dev->admin_tagset.numa_node = dev_to_node(dev->dev);
                dev->admin_tagset.cmd_size = nvme_cmd_size(dev);
                dev->admin_tagset.driver_data = dev;

                if (blk_mq_alloc_tag_set(&dev->admin_tagset))
                        return -ENOMEM;

                dev->admin_q = blk_mq_init_queue(&dev->admin_tagset);
                if (IS_ERR(dev->admin_q)) {
                        blk_mq_free_tag_set(&dev->admin_tagset);
                        return -ENOMEM;
                }
                if (!blk_get_queue(dev->admin_q)) {
                        nvme_dev_remove_admin(dev);
                        dev->admin_q = NULL;
                        return -ENODEV;
                }
        } else
                blk_mq_unfreeze_queue(dev->admin_q);

        return 0;
}

static int nvme_configure_admin_queue(struct nvme_dev *dev)
{
        int result;
        u32 aqa;
        u64 cap = readq(&dev->bar->cap);
        struct nvme_queue *nvmeq;
        unsigned page_shift = PAGE_SHIFT;
        unsigned dev_page_min = NVME_CAP_MPSMIN(cap) + 12;
        unsigned dev_page_max = NVME_CAP_MPSMAX(cap) + 12;

        if (page_shift < dev_page_min) {
                dev_err(dev->dev,
                                "Minimum device page size (%u) too large for "
                                "host (%u)\n", 1 << dev_page_min,
                                1 << page_shift);
                return -ENODEV;
        }
        if (page_shift > dev_page_max) {
                dev_info(dev->dev,
                                "Device maximum page size (%u) smaller than "
                                "host (%u); enabling work-around\n",
                                1 << dev_page_max, 1 << page_shift);
                page_shift = dev_page_max;
        }

        dev->subsystem = readl(&dev->bar->vs) >= NVME_VS(1, 1) ?
                                                NVME_CAP_NSSRC(cap) : 0;

        if (dev->subsystem && (readl(&dev->bar->csts) & NVME_CSTS_NSSRO))
                writel(NVME_CSTS_NSSRO, &dev->bar->csts);

        result = nvme_disable_ctrl(dev, cap);
        if (result < 0)
                return result;

        nvmeq = dev->queues[0];
        if (!nvmeq) {
                nvmeq = nvme_alloc_queue(dev, 0, NVME_AQ_DEPTH);
                if (!nvmeq)
                        return -ENOMEM;
        }

        aqa = nvmeq->q_depth - 1;
        aqa |= aqa << 16;

        dev->page_size = 1 << page_shift;

        dev->ctrl_config = NVME_CC_CSS_NVM;
        dev->ctrl_config |= (page_shift - 12) << NVME_CC_MPS_SHIFT;
        dev->ctrl_config |= NVME_CC_ARB_RR | NVME_CC_SHN_NONE;
        dev->ctrl_config |= NVME_CC_IOSQES | NVME_CC_IOCQES;

        writel(aqa, &dev->bar->aqa);
        writeq(nvmeq->sq_dma_addr, &dev->bar->asq);
        writeq(nvmeq->cq_dma_addr, &dev->bar->acq);

        result = nvme_enable_ctrl(dev, cap);
        if (result)
                goto free_nvmeq;

        nvmeq->cq_vector = 0;
        result = queue_request_irq(dev, nvmeq, nvmeq->irqname);
        if (result) {
                nvmeq->cq_vector = -1;
                goto free_nvmeq;
        }

        return result;

 free_nvmeq:
        nvme_free_queues(dev, 0);
        return result;
}

static int nvme_submit_io(struct nvme_ns *ns, struct nvme_user_io __user *uio)
{
        struct nvme_dev *dev = ns->dev;
        struct nvme_user_io io;
        struct nvme_command c;
        unsigned length, meta_len;
        int status, write;
        dma_addr_t meta_dma = 0;
        void *meta = NULL;
        void __user *metadata;

        if (copy_from_user(&io, uio, sizeof(io)))
                return -EFAULT;

        switch (io.opcode) {
        case nvme_cmd_write:
        case nvme_cmd_read:
        case nvme_cmd_compare:
                break;
        default:
                return -EINVAL;
        }

        length = (io.nblocks + 1) << ns->lba_shift;
        meta_len = (io.nblocks + 1) * ns->ms;
        metadata = (void __user *)(unsigned long)io.metadata;
        write = io.opcode & 1;

        if (ns->ext) {
                length += meta_len;
                meta_len = 0;
        }
        if (meta_len) {
                if (((io.metadata & 3) || !io.metadata) && !ns->ext)
                        return -EINVAL;

                meta = dma_alloc_coherent(dev->dev, meta_len,
                                                &meta_dma, GFP_KERNEL);

                if (!meta) {
                        status = -ENOMEM;
                        goto unmap;
                }
                if (write) {
                        if (copy_from_user(meta, metadata, meta_len)) {
                                status = -EFAULT;
                                goto unmap;
                        }
                }
        }

        memset(&c, 0, sizeof(c));
        c.rw.opcode = io.opcode;
        c.rw.flags = io.flags;
        c.rw.nsid = cpu_to_le32(ns->ns_id);
        c.rw.slba = cpu_to_le64(io.slba);
        c.rw.length = cpu_to_le16(io.nblocks);
        c.rw.control = cpu_to_le16(io.control);
        c.rw.dsmgmt = cpu_to_le32(io.dsmgmt);
        c.rw.reftag = cpu_to_le32(io.reftag);
        c.rw.apptag = cpu_to_le16(io.apptag);
        c.rw.appmask = cpu_to_le16(io.appmask);
        c.rw.metadata = cpu_to_le64(meta_dma);

        status = __nvme_submit_sync_cmd(ns->queue, &c, NULL,
                        (void __user *)io.addr, length, NULL, 0);
 unmap:
        if (meta) {
                if (status == NVME_SC_SUCCESS && !write) {
                        if (copy_to_user(metadata, meta, meta_len))
                                status = -EFAULT;
                }
                dma_free_coherent(dev->dev, meta_len, meta, meta_dma);
        }
        return status;
}

static int nvme_user_cmd(struct nvme_dev *dev, struct nvme_ns *ns,
                        struct nvme_passthru_cmd __user *ucmd)
{
        struct nvme_passthru_cmd cmd;
        struct nvme_command c;
        unsigned timeout = 0;
        int status;

        if (!capable(CAP_SYS_ADMIN))
                return -EACCES;
        if (copy_from_user(&cmd, ucmd, sizeof(cmd)))
                return -EFAULT;

        memset(&c, 0, sizeof(c));
        c.common.opcode = cmd.opcode;
        c.common.flags = cmd.flags;
        c.common.nsid = cpu_to_le32(cmd.nsid);
        c.common.cdw2[0] = cpu_to_le32(cmd.cdw2);
        c.common.cdw2[1] = cpu_to_le32(cmd.cdw3);
        c.common.cdw10[0] = cpu_to_le32(cmd.cdw10);
        c.common.cdw10[1] = cpu_to_le32(cmd.cdw11);
        c.common.cdw10[2] = cpu_to_le32(cmd.cdw12);
        c.common.cdw10[3] = cpu_to_le32(cmd.cdw13);
        c.common.cdw10[4] = cpu_to_le32(cmd.cdw14);
        c.common.cdw10[5] = cpu_to_le32(cmd.cdw15);

        if (cmd.timeout_ms)
                timeout = msecs_to_jiffies(cmd.timeout_ms);

        status = __nvme_submit_sync_cmd(ns ? ns->queue : dev->admin_q, &c,
                        NULL, (void __user *)cmd.addr, cmd.data_len,
                        &cmd.result, timeout);
        if (status >= 0) {
                if (put_user(cmd.result, &ucmd->result))
                        return -EFAULT;
        }

        return status;
}

static int nvme_subsys_reset(struct nvme_dev *dev)
{
        if (!dev->subsystem)
                return -ENOTTY;

        writel(0x4E564D65, &dev->bar->nssr); /* "NVMe" */
        return 0;
}

static int nvme_ioctl(struct block_device *bdev, fmode_t mode, unsigned int cmd,
                                                        unsigned long arg)
{
        struct nvme_ns *ns = bdev->bd_disk->private_data;

        switch (cmd) {
        case NVME_IOCTL_ID:
                force_successful_syscall_return();
                return ns->ns_id;
        case NVME_IOCTL_ADMIN_CMD:
                return nvme_user_cmd(ns->dev, NULL, (void __user *)arg);
        case NVME_IOCTL_IO_CMD:
                return nvme_user_cmd(ns->dev, ns, (void __user *)arg);
        case NVME_IOCTL_SUBMIT_IO:
                return nvme_submit_io(ns, (void __user *)arg);
        case SG_GET_VERSION_NUM:
                return nvme_sg_get_version_num((void __user *)arg);
        case SG_IO:
                return nvme_sg_io(ns, (void __user *)arg);
        default:
                return -ENOTTY;
        }
}

#ifdef CONFIG_COMPAT
static int nvme_compat_ioctl(struct block_device *bdev, fmode_t mode,
                                        unsigned int cmd, unsigned long arg)
{
        switch (cmd) {
        case SG_IO:
                return -ENOIOCTLCMD;
        }
        return nvme_ioctl(bdev, mode, cmd, arg);
}
#else
#define nvme_compat_ioctl       NULL
#endif

static int nvme_open(struct block_device *bdev, fmode_t mode)
{
        int ret = 0;
        struct nvme_ns *ns;

        spin_lock(&dev_list_lock);
        ns = bdev->bd_disk->private_data;
        if (!ns)
                ret = -ENXIO;
        else if (!kref_get_unless_zero(&ns->dev->kref))
                ret = -ENXIO;
        spin_unlock(&dev_list_lock);

        return ret;
}

static void nvme_free_dev(struct kref *kref);

static void nvme_release(struct gendisk *disk, fmode_t mode)
{
        struct nvme_ns *ns = disk->private_data;
        struct nvme_dev *dev = ns->dev;

        kref_put(&dev->kref, nvme_free_dev);
}

static int nvme_getgeo(struct block_device *bd, struct hd_geometry *geo)
{
        /* some standard values */
        geo->heads = 1 << 6;
        geo->sectors = 1 << 5;
        geo->cylinders = get_capacity(bd->bd_disk) >> 11;
        return 0;
}

static void nvme_config_discard(struct nvme_ns *ns)
{
        u32 logical_block_size = queue_logical_block_size(ns->queue);
        ns->queue->limits.discard_zeroes_data = 0;
        ns->queue->limits.discard_alignment = logical_block_size;
        ns->queue->limits.discard_granularity = logical_block_size;
        blk_queue_max_discard_sectors(ns->queue, 0xffffffff);
        queue_flag_set_unlocked(QUEUE_FLAG_DISCARD, ns->queue);
}

static int nvme_revalidate_disk(struct gendisk *disk)
{
        struct nvme_ns *ns = disk->private_data;
        struct nvme_dev *dev = ns->dev;
        struct nvme_id_ns *id;
        u8 lbaf, pi_type;
        u16 old_ms;
        unsigned short bs;

        if (nvme_identify_ns(dev, ns->ns_id, &id)) {
                dev_warn(dev->dev, "%s: Identify failure nvme%dn%d\n", __func__,
                                                dev->instance, ns->ns_id);
                return -ENODEV;
        }
        if (id->ncap == 0) {
                kfree(id);
                return -ENODEV;
        }

        old_ms = ns->ms;
        lbaf = id->flbas & NVME_NS_FLBAS_LBA_MASK;
        ns->lba_shift = id->lbaf[lbaf].ds;
        ns->ms = le16_to_cpu(id->lbaf[lbaf].ms);
        ns->ext = ns->ms && (id->flbas & NVME_NS_FLBAS_META_EXT);

        /*
         * If identify namespace failed, use default 512 byte block size so
         * block layer can use before failing read/write for 0 capacity.
         */
        if (ns->lba_shift == 0)
                ns->lba_shift = 9;
        bs = 1 << ns->lba_shift;

        /* XXX: PI implementation requires metadata equal t10 pi tuple size */
        pi_type = ns->ms == sizeof(struct t10_pi_tuple) ?
                                        id->dps & NVME_NS_DPS_PI_MASK : 0;

        if (blk_get_integrity(disk) && (ns->pi_type != pi_type ||
                                ns->ms != old_ms ||
                                bs != queue_logical_block_size(disk->queue) ||
                                (ns->ms && ns->ext)))
                blk_integrity_unregister(disk);

        ns->pi_type = pi_type;
        blk_queue_logical_block_size(ns->queue, bs);

        if (ns->ms && !blk_get_integrity(disk) && (disk->flags & GENHD_FL_UP) &&
                                                                !ns->ext)
                nvme_init_integrity(ns);

        if (ns->ms && !blk_get_integrity(disk))
                set_capacity(disk, 0);
        else
                set_capacity(disk, le64_to_cpup(&id->nsze) << (ns->lba_shift - 9));

        if (dev->oncs & NVME_CTRL_ONCS_DSM)
                nvme_config_discard(ns);

        kfree(id);
        return 0;
}

static const struct block_device_operations nvme_fops = {
        .owner          = THIS_MODULE,
        .ioctl          = nvme_ioctl,
        .compat_ioctl   = nvme_compat_ioctl,
        .open           = nvme_open,
        .release        = nvme_release,
        .getgeo         = nvme_getgeo,
        .revalidate_disk= nvme_revalidate_disk,
};

static int nvme_kthread(void *data)
{
        struct nvme_dev *dev, *next;

        while (!kthread_should_stop()) {
                set_current_state(TASK_INTERRUPTIBLE);
                spin_lock(&dev_list_lock);
                list_for_each_entry_safe(dev, next, &dev_list, node) {
                        int i;
                        u32 csts = readl(&dev->bar->csts);

                        if ((dev->subsystem && (csts & NVME_CSTS_NSSRO)) ||
                                                        csts & NVME_CSTS_CFS) {
                                if (work_busy(&dev->reset_work))
                                        continue;
                                list_del_init(&dev->node);
                                dev_warn(dev->dev,
                                        "Failed status: %x, reset controller\n",
                                        readl(&dev->bar->csts));
                                dev->reset_workfn = nvme_reset_failed_dev;
                                queue_work(nvme_workq, &dev->reset_work);
                                continue;
                        }
                        for (i = 0; i < dev->queue_count; i++) {
                                struct nvme_queue *nvmeq = dev->queues[i];
                                if (!nvmeq)
                                        continue;
                                spin_lock_irq(&nvmeq->q_lock);
                                nvme_process_cq(nvmeq);

                                while ((i == 0) && (dev->event_limit > 0)) {
                                        if (nvme_submit_async_admin_req(dev))
                                                break;
                                        dev->event_limit--;
                                }
                                spin_unlock_irq(&nvmeq->q_lock);
                        }
                }
                spin_unlock(&dev_list_lock);
                schedule_timeout(round_jiffies_relative(HZ));
        }
        return 0;
}

static void nvme_alloc_ns(struct nvme_dev *dev, unsigned nsid)
{
        struct nvme_ns *ns;
        struct gendisk *disk;
        int node = dev_to_node(dev->dev);

        ns = kzalloc_node(sizeof(*ns), GFP_KERNEL, node);
        if (!ns)
                return;

        ns->queue = blk_mq_init_queue(&dev->tagset);
        if (IS_ERR(ns->queue))
                goto out_free_ns;
        queue_flag_set_unlocked(QUEUE_FLAG_NOMERGES, ns->queue);
        queue_flag_set_unlocked(QUEUE_FLAG_NONROT, ns->queue);
        queue_flag_set_unlocked(QUEUE_FLAG_SG_GAPS, ns->queue);
        ns->dev = dev;
        ns->queue->queuedata = ns;

        disk = alloc_disk_node(0, node);
        if (!disk)
                goto out_free_queue;

        ns->ns_id = nsid;
        ns->disk = disk;
        ns->lba_shift = 9; /* set to a default value for 512 until disk is validated */
        list_add_tail(&ns->list, &dev->namespaces);

        blk_queue_logical_block_size(ns->queue, 1 << ns->lba_shift);
        if (dev->max_hw_sectors) {
                blk_queue_max_hw_sectors(ns->queue, dev->max_hw_sectors);
                blk_queue_max_segments(ns->queue,
                        ((dev->max_hw_sectors << 9) / dev->page_size) + 1);
        }
        if (dev->stripe_size)
                blk_queue_chunk_sectors(ns->queue, dev->stripe_size >> 9);
        if (dev->vwc & NVME_CTRL_VWC_PRESENT)
                blk_queue_flush(ns->queue, REQ_FLUSH | REQ_FUA);

        disk->major = nvme_major;
        disk->first_minor = 0;
        disk->fops = &nvme_fops;
        disk->private_data = ns;
        disk->queue = ns->queue;
        disk->driverfs_dev = dev->device;
        disk->flags = GENHD_FL_EXT_DEVT;
        sprintf(disk->disk_name, "nvme%dn%d", dev->instance, nsid);

        /*
         * Initialize capacity to 0 until we establish the namespace format and
         * setup integrity extentions if necessary. The revalidate_disk after
         * add_disk allows the driver to register with integrity if the format
         * requires it.
         */
        set_capacity(disk, 0);
        if (nvme_revalidate_disk(ns->disk))
                goto out_free_disk;

        add_disk(ns->disk);
        if (ns->ms) {
                struct block_device *bd = bdget_disk(ns->disk, 0);
                if (!bd)
                        return;
                if (blkdev_get(bd, FMODE_READ, NULL)) {
                        bdput(bd);
                        return;
                }
                blkdev_reread_part(bd);
                blkdev_put(bd, FMODE_READ);
        }
        return;
 out_free_disk:
        kfree(disk);
        list_del(&ns->list);
 out_free_queue:
        blk_cleanup_queue(ns->queue);
 out_free_ns:
        kfree(ns);
}

static void nvme_create_io_queues(struct nvme_dev *dev)
{
        unsigned i;

        for (i = dev->queue_count; i <= dev->max_qid; i++)
                if (!nvme_alloc_queue(dev, i, dev->q_depth))
                        break;

        for (i = dev->online_queues; i <= dev->queue_count - 1; i++)
                if (nvme_create_queue(dev->queues[i], i))
                        break;
}

static int set_queue_count(struct nvme_dev *dev, int count)
{
        int status;
        u32 result;
        u32 q_count = (count - 1) | ((count - 1) << 16);

        status = nvme_set_features(dev, NVME_FEAT_NUM_QUEUES, q_count, 0,
                                                                &result);
        if (status < 0)
                return status;
        if (status > 0) {
                dev_err(dev->dev, "Could not set queue count (%d)\n", status);
                return 0;
        }
        return min(result & 0xffff, result >> 16) + 1;
}

static void __iomem *nvme_map_cmb(struct nvme_dev *dev)
{
        u64 szu, size, offset;
        u32 cmbloc;
        resource_size_t bar_size;
        struct pci_dev *pdev = to_pci_dev(dev->dev);
        void __iomem *cmb;
        dma_addr_t dma_addr;

        if (!use_cmb_sqes)
                return NULL;

        dev->cmbsz = readl(&dev->bar->cmbsz);
        if (!(NVME_CMB_SZ(dev->cmbsz)))
                return NULL;

        cmbloc = readl(&dev->bar->cmbloc);

        szu = (u64)1 << (12 + 4 * NVME_CMB_SZU(dev->cmbsz));
        size = szu * NVME_CMB_SZ(dev->cmbsz);
        offset = szu * NVME_CMB_OFST(cmbloc);
        bar_size = pci_resource_len(pdev, NVME_CMB_BIR(cmbloc));

        if (offset > bar_size)
                return NULL;

        /*
         * Controllers may support a CMB size larger than their BAR,
         * for example, due to being behind a bridge. Reduce the CMB to
         * the reported size of the BAR
         */
        if (size > bar_size - offset)
                size = bar_size - offset;

        dma_addr = pci_resource_start(pdev, NVME_CMB_BIR(cmbloc)) + offset;
        cmb = ioremap_wc(dma_addr, size);
        if (!cmb)
                return NULL;

        dev->cmb_dma_addr = dma_addr;
        dev->cmb_size = size;
        return cmb;
}

static inline void nvme_release_cmb(struct nvme_dev *dev)
{
        if (dev->cmb) {
                iounmap(dev->cmb);
                dev->cmb = NULL;
        }
}

static size_t db_bar_size(struct nvme_dev *dev, unsigned nr_io_queues)
{
        return 4096 + ((nr_io_queues + 1) * 8 * dev->db_stride);
}

static int nvme_setup_io_queues(struct nvme_dev *dev)
{
        struct nvme_queue *adminq = dev->queues[0];
        struct pci_dev *pdev = to_pci_dev(dev->dev);
        int result, i, vecs, nr_io_queues, size;

        nr_io_queues = num_possible_cpus();
        result = set_queue_count(dev, nr_io_queues);
        if (result <= 0)
                return result;
        if (result < nr_io_queues)
                nr_io_queues = result;

        if (dev->cmb && NVME_CMB_SQS(dev->cmbsz)) {
                result = nvme_cmb_qdepth(dev, nr_io_queues,
                                sizeof(struct nvme_command));
                if (result > 0)
                        dev->q_depth = result;
                else
                        nvme_release_cmb(dev);
        }

        size = db_bar_size(dev, nr_io_queues);
        if (size > 8192) {
                iounmap(dev->bar);
                do {
                        dev->bar = ioremap(pci_resource_start(pdev, 0), size);
                        if (dev->bar)
                                break;
                        if (!--nr_io_queues)
                                return -ENOMEM;
                        size = db_bar_size(dev, nr_io_queues);
                } while (1);
                dev->dbs = ((void __iomem *)dev->bar) + 4096;
                adminq->q_db = dev->dbs;
        }

        /* Deregister the admin queue's interrupt */
        free_irq(dev->entry[0].vector, adminq);

        /*
         * If we enable msix early due to not intx, disable it again before
         * setting up the full range we need.
         */
        if (!pdev->irq)
                pci_disable_msix(pdev);

        for (i = 0; i < nr_io_queues; i++)
                dev->entry[i].entry = i;
        vecs = pci_enable_msix_range(pdev, dev->entry, 1, nr_io_queues);
        if (vecs < 0) {
                vecs = pci_enable_msi_range(pdev, 1, min(nr_io_queues, 32));
                if (vecs < 0) {
                        vecs = 1;
                } else {
                        for (i = 0; i < vecs; i++)
                                dev->entry[i].vector = i + pdev->irq;
                }
        }

        /*
         * Should investigate if there's a performance win from allocating
         * more queues than interrupt vectors; it might allow the submission
         * path to scale better, even if the receive path is limited by the
         * number of interrupts.
         */
        nr_io_queues = vecs;
        dev->max_qid = nr_io_queues;

        result = queue_request_irq(dev, adminq, adminq->irqname);
        if (result) {
                adminq->cq_vector = -1;
                goto free_queues;
        }

        /* Free previously allocated queues that are no longer usable */
        nvme_free_queues(dev, nr_io_queues + 1);
        nvme_create_io_queues(dev);

        return 0;

 free_queues:
        nvme_free_queues(dev, 1);
        return result;
}

static void nvme_free_namespace(struct nvme_ns *ns)
{
        list_del(&ns->list);

        spin_lock(&dev_list_lock);
        ns->disk->private_data = NULL;
        spin_unlock(&dev_list_lock);

        put_disk(ns->disk);
        kfree(ns);
}

static int ns_cmp(void *priv, struct list_head *a, struct list_head *b)
{
        struct nvme_ns *nsa = container_of(a, struct nvme_ns, list);
        struct nvme_ns *nsb = container_of(b, struct nvme_ns, list);

        return nsa->ns_id - nsb->ns_id;
}

static struct nvme_ns *nvme_find_ns(struct nvme_dev *dev, unsigned nsid)
{
        struct nvme_ns *ns;

        list_for_each_entry(ns, &dev->namespaces, list) {
                if (ns->ns_id == nsid)
                        return ns;
                if (ns->ns_id > nsid)
                        break;
        }
        return NULL;
}

static inline bool nvme_io_incapable(struct nvme_dev *dev)
{
        return (!dev->bar || readl(&dev->bar->csts) & NVME_CSTS_CFS ||
                                                        dev->online_queues < 2);
}

static void nvme_ns_remove(struct nvme_ns *ns)
{
        bool kill = nvme_io_incapable(ns->dev) && !blk_queue_dying(ns->queue);

        if (kill)
                blk_set_queue_dying(ns->queue);
        if (ns->disk->flags & GENHD_FL_UP) {
                if (blk_get_integrity(ns->disk))
                        blk_integrity_unregister(ns->disk);
                del_gendisk(ns->disk);
        }
        if (kill || !blk_queue_dying(ns->queue)) {
                blk_mq_abort_requeue_list(ns->queue);
                blk_cleanup_queue(ns->queue);
        }
}

static void nvme_scan_namespaces(struct nvme_dev *dev, unsigned nn)
{
        struct nvme_ns *ns, *next;
        unsigned i;

        for (i = 1; i <= nn; i++) {
                ns = nvme_find_ns(dev, i);
                if (ns) {
                        if (revalidate_disk(ns->disk)) {
                                nvme_ns_remove(ns);
                                nvme_free_namespace(ns);
                        }
                } else
                        nvme_alloc_ns(dev, i);
        }
        list_for_each_entry_safe(ns, next, &dev->namespaces, list) {
                if (ns->ns_id > nn) {
                        nvme_ns_remove(ns);
                        nvme_free_namespace(ns);
                }
        }
        list_sort(NULL, &dev->namespaces, ns_cmp);
}

static void nvme_dev_scan(struct work_struct *work)
{
        struct nvme_dev *dev = container_of(work, struct nvme_dev, scan_work);
        struct nvme_id_ctrl *ctrl;

        if (!dev->tagset.tags)
                return;
        if (nvme_identify_ctrl(dev, &ctrl))
                return;
        nvme_scan_namespaces(dev, le32_to_cpup(&ctrl->nn));
        kfree(ctrl);
}

/*
 * Return: error value if an error occurred setting up the queues or calling
 * Identify Device.  0 if these succeeded, even if adding some of the
 * namespaces failed.  At the moment, these failures are silent.  TBD which
 * failures should be reported.
 */
static int nvme_dev_add(struct nvme_dev *dev)
{
        struct pci_dev *pdev = to_pci_dev(dev->dev);
        int res;
        struct nvme_id_ctrl *ctrl;
        int shift = NVME_CAP_MPSMIN(readq(&dev->bar->cap)) + 12;

        res = nvme_identify_ctrl(dev, &ctrl);
        if (res) {
                dev_err(dev->dev, "Identify Controller failed (%d)\n", res);
                return -EIO;
        }

        dev->oncs = le16_to_cpup(&ctrl->oncs);
        dev->abort_limit = ctrl->acl + 1;
        dev->vwc = ctrl->vwc;
        memcpy(dev->serial, ctrl->sn, sizeof(ctrl->sn));
        memcpy(dev->model, ctrl->mn, sizeof(ctrl->mn));
        memcpy(dev->firmware_rev, ctrl->fr, sizeof(ctrl->fr));
        if (ctrl->mdts)
                dev->max_hw_sectors = 1 << (ctrl->mdts + shift - 9);
        if ((pdev->vendor == PCI_VENDOR_ID_INTEL) &&
                        (pdev->device == 0x0953) && ctrl->vs[3]) {
                unsigned int max_hw_sectors;

                dev->stripe_size = 1 << (ctrl->vs[3] + shift);
                max_hw_sectors = dev->stripe_size >> (shift - 9);
                if (dev->max_hw_sectors) {
                        dev->max_hw_sectors = min(max_hw_sectors,
                                                        dev->max_hw_sectors);
                } else
                        dev->max_hw_sectors = max_hw_sectors;
        }
        kfree(ctrl);

        if (!dev->tagset.tags) {
                dev->tagset.ops = &nvme_mq_ops;
                dev->tagset.nr_hw_queues = dev->online_queues - 1;
                dev->tagset.timeout = NVME_IO_TIMEOUT;
                dev->tagset.numa_node = dev_to_node(dev->dev);
                dev->tagset.queue_depth =
                                min_t(int, dev->q_depth, BLK_MQ_MAX_DEPTH) - 1;
                dev->tagset.cmd_size = nvme_cmd_size(dev);
                dev->tagset.flags = BLK_MQ_F_SHOULD_MERGE;
                dev->tagset.driver_data = dev;

                if (blk_mq_alloc_tag_set(&dev->tagset))
                        return 0;
        }
        schedule_work(&dev->scan_work);
        return 0;
}

static int nvme_dev_map(struct nvme_dev *dev)
{
        u64 cap;
        int bars, result = -ENOMEM;
        struct pci_dev *pdev = to_pci_dev(dev->dev);

        if (pci_enable_device_mem(pdev))
                return result;

        dev->entry[0].vector = pdev->irq;
        pci_set_master(pdev);
        bars = pci_select_bars(pdev, IORESOURCE_MEM);
        if (!bars)
                goto disable_pci;

        if (pci_request_selected_regions(pdev, bars, "nvme"))
                goto disable_pci;

        if (dma_set_mask_and_coherent(dev->dev, DMA_BIT_MASK(64)) &&
            dma_set_mask_and_coherent(dev->dev, DMA_BIT_MASK(32)))
                goto disable;

        dev->bar = ioremap(pci_resource_start(pdev, 0), 8192);
        if (!dev->bar)
                goto disable;

        if (readl(&dev->bar->csts) == -1) {
                result = -ENODEV;
                goto unmap;
        }

        /*
         * Some devices don't advertse INTx interrupts, pre-enable a single
         * MSIX vec for setup. We'll adjust this later.
         */
        if (!pdev->irq) {
                result = pci_enable_msix(pdev, dev->entry, 1);
                if (result < 0)
                        goto unmap;
        }

        cap = readq(&dev->bar->cap);
        dev->q_depth = min_t(int, NVME_CAP_MQES(cap) + 1, NVME_Q_DEPTH);
        dev->db_stride = 1 << NVME_CAP_STRIDE(cap);
        dev->dbs = ((void __iomem *)dev->bar) + 4096;
        if (readl(&dev->bar->vs) >= NVME_VS(1, 2))
                dev->cmb = nvme_map_cmb(dev);

        return 0;

 unmap:
        iounmap(dev->bar);
        dev->bar = NULL;
 disable:
        pci_release_regions(pdev);
 disable_pci:
        pci_disable_device(pdev);
        return result;
}

static void nvme_dev_unmap(struct nvme_dev *dev)
{
        struct pci_dev *pdev = to_pci_dev(dev->dev);

        if (pdev->msi_enabled)
                pci_disable_msi(pdev);
        else if (pdev->msix_enabled)
                pci_disable_msix(pdev);

        if (dev->bar) {
                iounmap(dev->bar);
                dev->bar = NULL;
                pci_release_regions(pdev);
        }

        if (pci_is_enabled(pdev))
                pci_disable_device(pdev);
}

struct nvme_delq_ctx {
        struct task_struct *waiter;
        struct kthread_worker *worker;
        atomic_t refcount;
};

static void nvme_wait_dq(struct nvme_delq_ctx *dq, struct nvme_dev *dev)
{
        dq->waiter = current;
        mb();

        for (;;) {
                set_current_state(TASK_KILLABLE);
                if (!atomic_read(&dq->refcount))
                        break;
                if (!schedule_timeout(ADMIN_TIMEOUT) ||
                                        fatal_signal_pending(current)) {
                        /*
                         * Disable the controller first since we can't trust it
                         * at this point, but leave the admin queue enabled
                         * until all queue deletion requests are flushed.
                         * FIXME: This may take a while if there are more h/w
                         * queues than admin tags.
                         */
                        set_current_state(TASK_RUNNING);
                        nvme_disable_ctrl(dev, readq(&dev->bar->cap));
                        nvme_clear_queue(dev->queues[0]);
                        flush_kthread_worker(dq->worker);
                        nvme_disable_queue(dev, 0);
                        return;
                }
        }
        set_current_state(TASK_RUNNING);
}

static void nvme_put_dq(struct nvme_delq_ctx *dq)
{
        atomic_dec(&dq->refcount);
        if (dq->waiter)
                wake_up_process(dq->waiter);
}

static struct nvme_delq_ctx *nvme_get_dq(struct nvme_delq_ctx *dq)
{
        atomic_inc(&dq->refcount);
        return dq;
}

static void nvme_del_queue_end(struct nvme_queue *nvmeq)
{
        struct nvme_delq_ctx *dq = nvmeq->cmdinfo.ctx;
        nvme_put_dq(dq);
}

static int adapter_async_del_queue(struct nvme_queue *nvmeq, u8 opcode,
                                                kthread_work_func_t fn)
{
        struct nvme_command c;

        memset(&c, 0, sizeof(c));
        c.delete_queue.opcode = opcode;
        c.delete_queue.qid = cpu_to_le16(nvmeq->qid);

        init_kthread_work(&nvmeq->cmdinfo.work, fn);
        return nvme_submit_admin_async_cmd(nvmeq->dev, &c, &nvmeq->cmdinfo,
                                                                ADMIN_TIMEOUT);
}

static void nvme_del_cq_work_handler(struct kthread_work *work)
{
        struct nvme_queue *nvmeq = container_of(work, struct nvme_queue,
                                                        cmdinfo.work);
        nvme_del_queue_end(nvmeq);
}

static int nvme_delete_cq(struct nvme_queue *nvmeq)
{
        return adapter_async_del_queue(nvmeq, nvme_admin_delete_cq,
                                                nvme_del_cq_work_handler);
}

static void nvme_del_sq_work_handler(struct kthread_work *work)
{
        struct nvme_queue *nvmeq = container_of(work, struct nvme_queue,
                                                        cmdinfo.work);
        int status = nvmeq->cmdinfo.status;

        if (!status)
                status = nvme_delete_cq(nvmeq);
        if (status)
                nvme_del_queue_end(nvmeq);
}

static int nvme_delete_sq(struct nvme_queue *nvmeq)
{
        return adapter_async_del_queue(nvmeq, nvme_admin_delete_sq,
                                                nvme_del_sq_work_handler);
}

static void nvme_del_queue_start(struct kthread_work *work)
{
        struct nvme_queue *nvmeq = container_of(work, struct nvme_queue,
                                                        cmdinfo.work);
        if (nvme_delete_sq(nvmeq))
                nvme_del_queue_end(nvmeq);
}

static void nvme_disable_io_queues(struct nvme_dev *dev)
{
        int i;
        DEFINE_KTHREAD_WORKER_ONSTACK(worker);
        struct nvme_delq_ctx dq;
        struct task_struct *kworker_task = kthread_run(kthread_worker_fn,
                                        &worker, "nvme%d", dev->instance);

        if (IS_ERR(kworker_task)) {
                dev_err(dev->dev,
                        "Failed to create queue del task\n");
                for (i = dev->queue_count - 1; i > 0; i--)
                        nvme_disable_queue(dev, i);
                return;
        }

        dq.waiter = NULL;
        atomic_set(&dq.refcount, 0);
        dq.worker = &worker;
        for (i = dev->queue_count - 1; i > 0; i--) {
                struct nvme_queue *nvmeq = dev->queues[i];

                if (nvme_suspend_queue(nvmeq))
                        continue;
                nvmeq->cmdinfo.ctx = nvme_get_dq(&dq);
                nvmeq->cmdinfo.worker = dq.worker;
                init_kthread_work(&nvmeq->cmdinfo.work, nvme_del_queue_start);
                queue_kthread_work(dq.worker, &nvmeq->cmdinfo.work);
        }
        nvme_wait_dq(&dq, dev);
        kthread_stop(kworker_task);
}

/*
* Remove the node from the device list and check
* for whether or not we need to stop the nvme_thread.
*/
static void nvme_dev_list_remove(struct nvme_dev *dev)
{
        struct task_struct *tmp = NULL;

        spin_lock(&dev_list_lock);
        list_del_init(&dev->node);
        if (list_empty(&dev_list) && !IS_ERR_OR_NULL(nvme_thread)) {
                tmp = nvme_thread;
                nvme_thread = NULL;
        }
        spin_unlock(&dev_list_lock);

        if (tmp)
                kthread_stop(tmp);
}

static void nvme_freeze_queues(struct nvme_dev *dev)
{
        struct nvme_ns *ns;

        list_for_each_entry(ns, &dev->namespaces, list) {
                blk_mq_freeze_queue_start(ns->queue);

                spin_lock_irq(ns->queue->queue_lock);
                queue_flag_set(QUEUE_FLAG_STOPPED, ns->queue);
                spin_unlock_irq(ns->queue->queue_lock);

                blk_mq_cancel_requeue_work(ns->queue);
                blk_mq_stop_hw_queues(ns->queue);
        }
}

static void nvme_unfreeze_queues(struct nvme_dev *dev)
{
        struct nvme_ns *ns;

        list_for_each_entry(ns, &dev->namespaces, list) {
                queue_flag_clear_unlocked(QUEUE_FLAG_STOPPED, ns->queue);
                blk_mq_unfreeze_queue(ns->queue);
                blk_mq_start_stopped_hw_queues(ns->queue, true);
                blk_mq_kick_requeue_list(ns->queue);
        }
}

static void nvme_dev_shutdown(struct nvme_dev *dev)
{
        int i;
        u32 csts = -1;

        nvme_dev_list_remove(dev);

        if (dev->bar) {
                nvme_freeze_queues(dev);
                csts = readl(&dev->bar->csts);
        }
        if (csts & NVME_CSTS_CFS || !(csts & NVME_CSTS_RDY)) {
                for (i = dev->queue_count - 1; i >= 0; i--) {
                        struct nvme_queue *nvmeq = dev->queues[i];
                        nvme_suspend_queue(nvmeq);
                }
        } else {
                nvme_disable_io_queues(dev);
                nvme_shutdown_ctrl(dev);
                nvme_disable_queue(dev, 0);
        }
        nvme_dev_unmap(dev);

        for (i = dev->queue_count - 1; i >= 0; i--)
                nvme_clear_queue(dev->queues[i]);
}

static void nvme_dev_remove(struct nvme_dev *dev)
{
        struct nvme_ns *ns;

        list_for_each_entry(ns, &dev->namespaces, list)
                nvme_ns_remove(ns);
}

static int nvme_setup_prp_pools(struct nvme_dev *dev)
{
        dev->prp_page_pool = dma_pool_create("prp list page", dev->dev,
                                                PAGE_SIZE, PAGE_SIZE, 0);
        if (!dev->prp_page_pool)
                return -ENOMEM;

        /* Optimisation for I/Os between 4k and 128k */
        dev->prp_small_pool = dma_pool_create("prp list 256", dev->dev,
                                                256, 256, 0);
        if (!dev->prp_small_pool) {
                dma_pool_destroy(dev->prp_page_pool);
                return -ENOMEM;
        }
        return 0;
}

static void nvme_release_prp_pools(struct nvme_dev *dev)
{
        dma_pool_destroy(dev->prp_page_pool);
        dma_pool_destroy(dev->prp_small_pool);
}

static DEFINE_IDA(nvme_instance_ida);

static int nvme_set_instance(struct nvme_dev *dev)
{
        int instance, error;

        do {
                if (!ida_pre_get(&nvme_instance_ida, GFP_KERNEL))
                        return -ENODEV;

                spin_lock(&dev_list_lock);
                error = ida_get_new(&nvme_instance_ida, &instance);
                spin_unlock(&dev_list_lock);
        } while (error == -EAGAIN);

        if (error)
                return -ENODEV;

        dev->instance = instance;
        return 0;
}

static void nvme_release_instance(struct nvme_dev *dev)
{
        spin_lock(&dev_list_lock);
        ida_remove(&nvme_instance_ida, dev->instance);
        spin_unlock(&dev_list_lock);
}

static void nvme_free_namespaces(struct nvme_dev *dev)
{
        struct nvme_ns *ns, *next;

        list_for_each_entry_safe(ns, next, &dev->namespaces, list)
                nvme_free_namespace(ns);
}

static void nvme_free_dev(struct kref *kref)
{
        struct nvme_dev *dev = container_of(kref, struct nvme_dev, kref);

        put_device(dev->dev);
        put_device(dev->device);
        nvme_free_namespaces(dev);
        nvme_release_instance(dev);
        if (dev->tagset.tags)
                blk_mq_free_tag_set(&dev->tagset);
        if (dev->admin_q)
                blk_put_queue(dev->admin_q);
        kfree(dev->queues);
        kfree(dev->entry);
        kfree(dev);
}

static int nvme_dev_open(struct inode *inode, struct file *f)
{
        struct nvme_dev *dev;
        int instance = iminor(inode);
        int ret = -ENODEV;

        spin_lock(&dev_list_lock);
        list_for_each_entry(dev, &dev_list, node) {
                if (dev->instance == instance) {
                        if (!dev->admin_q) {
                                ret = -EWOULDBLOCK;
                                break;
                        }
                        if (!kref_get_unless_zero(&dev->kref))
                                break;
                        f->private_data = dev;
                        ret = 0;
                        break;
                }
        }
        spin_unlock(&dev_list_lock);

        return ret;
}

static int nvme_dev_release(struct inode *inode, struct file *f)
{
        struct nvme_dev *dev = f->private_data;
        kref_put(&dev->kref, nvme_free_dev);
        return 0;
}

static long nvme_dev_ioctl(struct file *f, unsigned int cmd, unsigned long arg)
{
        struct nvme_dev *dev = f->private_data;
        struct nvme_ns *ns;

        switch (cmd) {
        case NVME_IOCTL_ADMIN_CMD:
                return nvme_user_cmd(dev, NULL, (void __user *)arg);
        case NVME_IOCTL_IO_CMD:
                if (list_empty(&dev->namespaces))
                        return -ENOTTY;
                ns = list_first_entry(&dev->namespaces, struct nvme_ns, list);
                return nvme_user_cmd(dev, ns, (void __user *)arg);
        case NVME_IOCTL_RESET:
                dev_warn(dev->dev, "resetting controller\n");
                return nvme_reset(dev);
        case NVME_IOCTL_SUBSYS_RESET:
                return nvme_subsys_reset(dev);
        default:
                return -ENOTTY;
        }
}

static const struct file_operations nvme_dev_fops = {
        .owner          = THIS_MODULE,
        .open           = nvme_dev_open,
        .release        = nvme_dev_release,
        .unlocked_ioctl = nvme_dev_ioctl,
        .compat_ioctl   = nvme_dev_ioctl,
};

static void nvme_set_irq_hints(struct nvme_dev *dev)
{
        struct nvme_queue *nvmeq;
        int i;

        for (i = 0; i < dev->online_queues; i++) {
                nvmeq = dev->queues[i];

                if (!nvmeq->tags || !(*nvmeq->tags))
                        continue;

                irq_set_affinity_hint(dev->entry[nvmeq->cq_vector].vector,
                                        blk_mq_tags_cpumask(*nvmeq->tags));
        }
}

static int nvme_dev_start(struct nvme_dev *dev)
{
        int result;
        bool start_thread = false;

        result = nvme_dev_map(dev);
        if (result)
                return result;

        result = nvme_configure_admin_queue(dev);
        if (result)
                goto unmap;

        spin_lock(&dev_list_lock);
        if (list_empty(&dev_list) && IS_ERR_OR_NULL(nvme_thread)) {
                start_thread = true;
                nvme_thread = NULL;
        }
        list_add(&dev->node, &dev_list);
        spin_unlock(&dev_list_lock);

        if (start_thread) {
                nvme_thread = kthread_run(nvme_kthread, NULL, "nvme");
                wake_up_all(&nvme_kthread_wait);
        } else
                wait_event_killable(nvme_kthread_wait, nvme_thread);

        if (IS_ERR_OR_NULL(nvme_thread)) {
                result = nvme_thread ? PTR_ERR(nvme_thread) : -EINTR;
                goto disable;
        }

        nvme_init_queue(dev->queues[0], 0);
        result = nvme_alloc_admin_tags(dev);
        if (result)
                goto disable;

        result = nvme_setup_io_queues(dev);
        if (result)
                goto free_tags;

        nvme_set_irq_hints(dev);

        dev->event_limit = 1;
        return result;

 free_tags:
        nvme_dev_remove_admin(dev);
        blk_put_queue(dev->admin_q);
        dev->admin_q = NULL;
        dev->queues[0]->tags = NULL;
 disable:
        nvme_disable_queue(dev, 0);
        nvme_dev_list_remove(dev);
 unmap:
        nvme_dev_unmap(dev);
        return result;
}

static int nvme_remove_dead_ctrl(void *arg)
{
        struct nvme_dev *dev = (struct nvme_dev *)arg;
        struct pci_dev *pdev = to_pci_dev(dev->dev);

        if (pci_get_drvdata(pdev))
                pci_stop_and_remove_bus_device_locked(pdev);
        kref_put(&dev->kref, nvme_free_dev);
        return 0;
}

static void nvme_remove_disks(struct work_struct *ws)
{
        struct nvme_dev *dev = container_of(ws, struct nvme_dev, reset_work);

        nvme_free_queues(dev, 1);
        nvme_dev_remove(dev);
}

static int nvme_dev_resume(struct nvme_dev *dev)
{
        int ret;

        ret = nvme_dev_start(dev);
        if (ret)
                return ret;
        if (dev->online_queues < 2) {
                spin_lock(&dev_list_lock);
                dev->reset_workfn = nvme_remove_disks;
                queue_work(nvme_workq, &dev->reset_work);
                spin_unlock(&dev_list_lock);
        } else {
                nvme_unfreeze_queues(dev);
                nvme_dev_add(dev);
                nvme_set_irq_hints(dev);
        }
        return 0;
}

static void nvme_dead_ctrl(struct nvme_dev *dev)
{
        dev_warn(dev->dev, "Device failed to resume\n");
        kref_get(&dev->kref);
        if (IS_ERR(kthread_run(nvme_remove_dead_ctrl, dev, "nvme%d",
                                                dev->instance))) {
                dev_err(dev->dev,
                        "Failed to start controller remove task\n");
                kref_put(&dev->kref, nvme_free_dev);
        }
}

static void nvme_dev_reset(struct nvme_dev *dev)
{
        bool in_probe = work_busy(&dev->probe_work);

        nvme_dev_shutdown(dev);

        /* Synchronize with device probe so that work will see failure status
         * and exit gracefully without trying to schedule another reset */
        flush_work(&dev->probe_work);

        /* Fail this device if reset occured during probe to avoid
         * infinite initialization loops. */
        if (in_probe) {
                nvme_dead_ctrl(dev);
                return;
        }
        /* Schedule device resume asynchronously so the reset work is available
         * to cleanup errors that may occur during reinitialization */
        schedule_work(&dev->probe_work);
}

static void nvme_reset_failed_dev(struct work_struct *ws)
{
        struct nvme_dev *dev = container_of(ws, struct nvme_dev, reset_work);
        nvme_dev_reset(dev);
}

static void nvme_reset_workfn(struct work_struct *work)
{
        struct nvme_dev *dev = container_of(work, struct nvme_dev, reset_work);
        dev->reset_workfn(work);
}

static int nvme_reset(struct nvme_dev *dev)
{
        int ret = -EBUSY;

        if (!dev->admin_q || blk_queue_dying(dev->admin_q))
                return -ENODEV;

        spin_lock(&dev_list_lock);
        if (!work_pending(&dev->reset_work)) {
                dev->reset_workfn = nvme_reset_failed_dev;
                queue_work(nvme_workq, &dev->reset_work);
                ret = 0;
        }
        spin_unlock(&dev_list_lock);

        if (!ret) {
                flush_work(&dev->reset_work);
                flush_work(&dev->probe_work);
                return 0;
        }

        return ret;
}

static ssize_t nvme_sysfs_reset(struct device *dev,
                                struct device_attribute *attr, const char *buf,
                                size_t count)
{
        struct nvme_dev *ndev = dev_get_drvdata(dev);
        int ret;

        ret = nvme_reset(ndev);
        if (ret < 0)
                return ret;

        return count;
}
static DEVICE_ATTR(reset_controller, S_IWUSR, NULL, nvme_sysfs_reset);

static void nvme_async_probe(struct work_struct *work);
static int nvme_probe(struct pci_dev *pdev, const struct pci_device_id *id)
{
        int node, result = -ENOMEM;
        struct nvme_dev *dev;

        node = dev_to_node(&pdev->dev);
        if (node == NUMA_NO_NODE)
                set_dev_node(&pdev->dev, 0);

        dev = kzalloc_node(sizeof(*dev), GFP_KERNEL, node);
        if (!dev)
                return -ENOMEM;
        dev->entry = kzalloc_node(num_possible_cpus() * sizeof(*dev->entry),
                                                        GFP_KERNEL, node);
        if (!dev->entry)
                goto free;
        dev->queues = kzalloc_node((num_possible_cpus() + 1) * sizeof(void *),
                                                        GFP_KERNEL, node);
        if (!dev->queues)
                goto free;

        INIT_LIST_HEAD(&dev->namespaces);
        dev->reset_workfn = nvme_reset_failed_dev;
        INIT_WORK(&dev->reset_work, nvme_reset_workfn);
        dev->dev = get_device(&pdev->dev);
        pci_set_drvdata(pdev, dev);
        result = nvme_set_instance(dev);
        if (result)
                goto put_pci;

        result = nvme_setup_prp_pools(dev);
        if (result)
                goto release;

        kref_init(&dev->kref);
        dev->device = device_create(nvme_class, &pdev->dev,
                                MKDEV(nvme_char_major, dev->instance),
                                dev, "nvme%d", dev->instance);
        if (IS_ERR(dev->device)) {
                result = PTR_ERR(dev->device);
                goto release_pools;
        }
        get_device(dev->device);
        dev_set_drvdata(dev->device, dev);

        result = device_create_file(dev->device, &dev_attr_reset_controller);
        if (result)
                goto put_dev;

        INIT_LIST_HEAD(&dev->node);
        INIT_WORK(&dev->scan_work, nvme_dev_scan);
        INIT_WORK(&dev->probe_work, nvme_async_probe);
        schedule_work(&dev->probe_work);
        return 0;

 put_dev:
        device_destroy(nvme_class, MKDEV(nvme_char_major, dev->instance));
        put_device(dev->device);
 release_pools:
        nvme_release_prp_pools(dev);
 release:
        nvme_release_instance(dev);
 put_pci:
        put_device(dev->dev);
 free:
        kfree(dev->queues);
        kfree(dev->entry);
        kfree(dev);
        return result;
}

static void nvme_async_probe(struct work_struct *work)
{
        struct nvme_dev *dev = container_of(work, struct nvme_dev, probe_work);

        if (nvme_dev_resume(dev) && !work_busy(&dev->reset_work))
                nvme_dead_ctrl(dev);
}

static void nvme_reset_notify(struct pci_dev *pdev, bool prepare)
{
        struct nvme_dev *dev = pci_get_drvdata(pdev);

        if (prepare)
                nvme_dev_shutdown(dev);
        else
                nvme_dev_resume(dev);
}

static void nvme_shutdown(struct pci_dev *pdev)
{
        struct nvme_dev *dev = pci_get_drvdata(pdev);
        nvme_dev_shutdown(dev);
}

static void nvme_remove(struct pci_dev *pdev)
{
        struct nvme_dev *dev = pci_get_drvdata(pdev);

        spin_lock(&dev_list_lock);
        list_del_init(&dev->node);
        spin_unlock(&dev_list_lock);

        pci_set_drvdata(pdev, NULL);
        flush_work(&dev->probe_work);
        flush_work(&dev->reset_work);
        flush_work(&dev->scan_work);
        device_remove_file(dev->device, &dev_attr_reset_controller);
        nvme_dev_remove(dev);
        nvme_dev_shutdown(dev);
        nvme_dev_remove_admin(dev);
        device_destroy(nvme_class, MKDEV(nvme_char_major, dev->instance));
        nvme_free_queues(dev, 0);
        nvme_release_cmb(dev);
        nvme_release_prp_pools(dev);
        kref_put(&dev->kref, nvme_free_dev);
}

/* These functions are yet to be implemented */
#define nvme_error_detected NULL
#define nvme_dump_registers NULL
#define nvme_link_reset NULL
#define nvme_slot_reset NULL
#define nvme_error_resume NULL

#ifdef CONFIG_PM_SLEEP
static int nvme_suspend(struct device *dev)
{
        struct pci_dev *pdev = to_pci_dev(dev);
        struct nvme_dev *ndev = pci_get_drvdata(pdev);

        nvme_dev_shutdown(ndev);
        return 0;
}

static int nvme_resume(struct device *dev)
{
        struct pci_dev *pdev = to_pci_dev(dev);
        struct nvme_dev *ndev = pci_get_drvdata(pdev);

        if (nvme_dev_resume(ndev) && !work_busy(&ndev->reset_work)) {
                ndev->reset_workfn = nvme_reset_failed_dev;
                queue_work(nvme_workq, &ndev->reset_work);
        }
        return 0;
}
#endif

static SIMPLE_DEV_PM_OPS(nvme_dev_pm_ops, nvme_suspend, nvme_resume);

static const struct pci_error_handlers nvme_err_handler = {
        .error_detected = nvme_error_detected,
        .mmio_enabled   = nvme_dump_registers,
        .link_reset     = nvme_link_reset,
        .slot_reset     = nvme_slot_reset,
        .resume         = nvme_error_resume,
        .reset_notify   = nvme_reset_notify,
};

/* Move to pci_ids.h later */
#define PCI_CLASS_STORAGE_EXPRESS       0x010802

static const struct pci_device_id nvme_id_table[] = {
        { PCI_DEVICE_CLASS(PCI_CLASS_STORAGE_EXPRESS, 0xffffff) },
        { 0, }
};
MODULE_DEVICE_TABLE(pci, nvme_id_table);

static struct pci_driver nvme_driver = {
        .name           = "nvme",
        .id_table       = nvme_id_table,
        .probe          = nvme_probe,
        .remove         = nvme_remove,
        .shutdown       = nvme_shutdown,
        .driver         = {
                .pm     = &nvme_dev_pm_ops,
        },
        .err_handler    = &nvme_err_handler,
};

static int __init nvme_init(void)
{
        int result;

        init_waitqueue_head(&nvme_kthread_wait);

        nvme_workq = create_singlethread_workqueue("nvme");
        if (!nvme_workq)
                return -ENOMEM;

        result = register_blkdev(nvme_major, "nvme");
        if (result < 0)
                goto kill_workq;
        else if (result > 0)
                nvme_major = result;

        result = __register_chrdev(nvme_char_major, 0, NVME_MINORS, "nvme",
                                                        &nvme_dev_fops);
        if (result < 0)
                goto unregister_blkdev;
        else if (result > 0)
                nvme_char_major = result;

        nvme_class = class_create(THIS_MODULE, "nvme");
        if (IS_ERR(nvme_class)) {
                result = PTR_ERR(nvme_class);
                goto unregister_chrdev;
        }

        result = pci_register_driver(&nvme_driver);
        if (result)
                goto destroy_class;
        return 0;

 destroy_class:
        class_destroy(nvme_class);
 unregister_chrdev:
        __unregister_chrdev(nvme_char_major, 0, NVME_MINORS, "nvme");
 unregister_blkdev:
        unregister_blkdev(nvme_major, "nvme");
 kill_workq:
        destroy_workqueue(nvme_workq);
        return result;
}

static void __exit nvme_exit(void)
{
        pci_unregister_driver(&nvme_driver);
        unregister_blkdev(nvme_major, "nvme");
        destroy_workqueue(nvme_workq);
        class_destroy(nvme_class);
        __unregister_chrdev(nvme_char_major, 0, NVME_MINORS, "nvme");
        BUG_ON(nvme_thread && !IS_ERR(nvme_thread));
        _nvme_check_size();
}

MODULE_AUTHOR("Matthew Wilcox <willy@linux.intel.com>");
MODULE_LICENSE("GPL");
MODULE_VERSION("1.0");
module_init(nvme_init);
module_exit(nvme_exit);