[deliverable/linux.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.
 *
 * You should have received a copy of the GNU General Public License along with
 * this program; if not, write to the Free Software Foundation, Inc.,
 * 51 Franklin St - Fifth Floor, Boston, MA 02110-1301 USA.
 */

#include <linux/nvme.h>
#include <linux/bio.h>
#include <linux/bitops.h>
#include <linux/blkdev.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/mm.h>
#include <linux/module.h>
#include <linux/moduleparam.h>
#include <linux/pci.h>
#include <linux/percpu.h>
#include <linux/poison.h>
#include <linux/ptrace.h>
#include <linux/sched.h>
#include <linux/slab.h>
#include <linux/types.h>
#include <scsi/sg.h>
#include <asm-generic/io-64-nonatomic-lo-hi.h>

#define NVME_Q_DEPTH 1024
#define SQ_SIZE(depth)          (depth * sizeof(struct nvme_command))
#define CQ_SIZE(depth)          (depth * sizeof(struct nvme_completion))
#define ADMIN_TIMEOUT   (60 * HZ)

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

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

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

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 void nvme_reset_failed_dev(struct work_struct *ws);

struct async_cmd_info {
        struct kthread_work work;
        struct kthread_worker *worker;
        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 rcu_head r_head;
        struct device *q_dmadev;
        struct nvme_dev *dev;
        char irqname[24];       /* nvme4294967295-65535\0 */
        spinlock_t q_lock;
        struct nvme_command *sq_cmds;
        volatile struct nvme_completion *cqes;
        dma_addr_t sq_dma_addr;
        dma_addr_t cq_dma_addr;
        wait_queue_head_t sq_full;
        wait_queue_t sq_cong_wait;
        struct bio_list sq_cong;
        u32 __iomem *q_db;
        u16 q_depth;
        u16 cq_vector;
        u16 sq_head;
        u16 sq_tail;
        u16 cq_head;
        u16 qid;
        u8 cq_phase;
        u8 cqe_seen;
        u8 q_suspended;
        cpumask_var_t cpu_mask;
        struct async_cmd_info cmdinfo;
        unsigned long cmdid_data[];
};

/*
 * 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_dev *, void *,
                                                struct nvme_completion *);

struct nvme_cmd_info {
        nvme_completion_fn fn;
        void *ctx;
        unsigned long timeout;
        int aborted;
};

static struct nvme_cmd_info *nvme_cmd_info(struct nvme_queue *nvmeq)
{
        return (void *)&nvmeq->cmdid_data[BITS_TO_LONGS(nvmeq->q_depth)];
}

static unsigned nvme_queue_extra(int depth)
{
        return DIV_ROUND_UP(depth, 8) + (depth * sizeof(struct nvme_cmd_info));
}

/**
 * alloc_cmdid() - Allocate a Command ID
 * @nvmeq: The queue that will be used for this command
 * @ctx: A pointer that will be passed to the handler
 * @handler: The function to call on completion
 *
 * Allocate a Command ID for a queue.  The data passed in will
 * be passed to the completion handler.  This is implemented by using
 * the bottom two bits of the ctx pointer to store the handler ID.
 * Passing in a pointer that's not 4-byte aligned will cause a BUG.
 * We can change this if it becomes a problem.
 *
 * May be called with local interrupts disabled and the q_lock held,
 * or with interrupts enabled and no locks held.
 */
static int alloc_cmdid(struct nvme_queue *nvmeq, void *ctx,
                                nvme_completion_fn handler, unsigned timeout)
{
        int depth = nvmeq->q_depth - 1;
        struct nvme_cmd_info *info = nvme_cmd_info(nvmeq);
        int cmdid;

        do {
                cmdid = find_first_zero_bit(nvmeq->cmdid_data, depth);
                if (cmdid >= depth)
                        return -EBUSY;
        } while (test_and_set_bit(cmdid, nvmeq->cmdid_data));

        info[cmdid].fn = handler;
        info[cmdid].ctx = ctx;
        info[cmdid].timeout = jiffies + timeout;
        info[cmdid].aborted = 0;
        return cmdid;
}

static int alloc_cmdid_killable(struct nvme_queue *nvmeq, void *ctx,
                                nvme_completion_fn handler, unsigned timeout)
{
        int cmdid;
        wait_event_killable(nvmeq->sq_full,
                (cmdid = alloc_cmdid(nvmeq, ctx, handler, timeout)) >= 0);
        return (cmdid < 0) ? -EINTR : cmdid;
}

/* 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)
#define CMD_CTX_FLUSH           (0x318 + CMD_CTX_BASE)
#define CMD_CTX_ABORT           (0x31C + CMD_CTX_BASE)

static void special_completion(struct nvme_dev *dev, void *ctx,
                                                struct nvme_completion *cqe)
{
        if (ctx == CMD_CTX_CANCELLED)
                return;
        if (ctx == CMD_CTX_FLUSH)
                return;
        if (ctx == CMD_CTX_ABORT) {
                ++dev->abort_limit;
                return;
        }
        if (ctx == CMD_CTX_COMPLETED) {
                dev_warn(&dev->pci_dev->dev,
                                "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(&dev->pci_dev->dev,
                                "invalid id %d completed on queue %d\n",
                                cqe->command_id, le16_to_cpup(&cqe->sq_id));
                return;
        }

        dev_warn(&dev->pci_dev->dev, "Unknown special completion %p\n", ctx);
}

static void async_completion(struct nvme_dev *dev, 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);
}

/*
 * Called with local interrupts disabled and the q_lock held.  May not sleep.
 */
static void *free_cmdid(struct nvme_queue *nvmeq, int cmdid,
                                                nvme_completion_fn *fn)
{
        void *ctx;
        struct nvme_cmd_info *info = nvme_cmd_info(nvmeq);

        if (cmdid >= nvmeq->q_depth) {
                *fn = special_completion;
                return CMD_CTX_INVALID;
        }
        if (fn)
                *fn = info[cmdid].fn;
        ctx = info[cmdid].ctx;
        info[cmdid].fn = special_completion;
        info[cmdid].ctx = CMD_CTX_COMPLETED;
        clear_bit(cmdid, nvmeq->cmdid_data);
        wake_up(&nvmeq->sq_full);
        return ctx;
}

static void *cancel_cmdid(struct nvme_queue *nvmeq, int cmdid,
                                                nvme_completion_fn *fn)
{
        void *ctx;
        struct nvme_cmd_info *info = nvme_cmd_info(nvmeq);
        if (fn)
                *fn = info[cmdid].fn;
        ctx = info[cmdid].ctx;
        info[cmdid].fn = special_completion;
        info[cmdid].ctx = CMD_CTX_CANCELLED;
        return ctx;
}

static struct nvme_queue *raw_nvmeq(struct nvme_dev *dev, int qid)
{
        return rcu_dereference_raw(dev->queues[qid]);
}

static struct nvme_queue *get_nvmeq(struct nvme_dev *dev) __acquires(RCU)
{
        unsigned queue_id = get_cpu_var(*dev->io_queue);
        rcu_read_lock();
        return rcu_dereference(dev->queues[queue_id]);
}

static void put_nvmeq(struct nvme_queue *nvmeq) __releases(RCU)
{
        rcu_read_unlock();
        put_cpu_var(nvmeq->dev->io_queue);
}

static struct nvme_queue *lock_nvmeq(struct nvme_dev *dev, int q_idx)
                                                        __acquires(RCU)
{
        rcu_read_lock();
        return rcu_dereference(dev->queues[q_idx]);
}

static void unlock_nvmeq(struct nvme_queue *nvmeq) __releases(RCU)
{
        rcu_read_unlock();
}

/**
 * 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 int nvme_submit_cmd(struct nvme_queue *nvmeq, struct nvme_command *cmd)
{
        unsigned long flags;
        u16 tail;
        spin_lock_irqsave(&nvmeq->q_lock, flags);
        if (nvmeq->q_suspended) {
                spin_unlock_irqrestore(&nvmeq->q_lock, flags);
                return -EBUSY;
        }
        tail = nvmeq->sq_tail;
        memcpy(&nvmeq->sq_cmds[tail], cmd, sizeof(*cmd));
        if (++tail == nvmeq->q_depth)
                tail = 0;
        writel(tail, nvmeq->q_db);
        nvmeq->sq_tail = tail;
        spin_unlock_irqrestore(&nvmeq->q_lock, flags);

        return 0;
}

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

/*
 * 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)
{
        unsigned nprps = DIV_ROUND_UP(size + PAGE_SIZE, PAGE_SIZE);
        return DIV_ROUND_UP(8 * nprps, PAGE_SIZE - 8);
}

static struct nvme_iod *
nvme_alloc_iod(unsigned nseg, unsigned nbytes, gfp_t gfp)
{
        struct nvme_iod *iod = kmalloc(sizeof(struct nvme_iod) +
                                sizeof(__le64 *) * nvme_npages(nbytes) +
                                sizeof(struct scatterlist) * nseg, gfp);

        if (iod) {
                iod->offset = offsetof(struct nvme_iod, sg[nseg]);
                iod->npages = -1;
                iod->length = nbytes;
                iod->nents = 0;
                iod->start_time = jiffies;
        }

        return iod;
}

void nvme_free_iod(struct nvme_dev *dev, struct nvme_iod *iod)
{
        const int last_prp = 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;
        }
        kfree(iod);
}

static void nvme_start_io_acct(struct bio *bio)
{
        struct gendisk *disk = bio->bi_bdev->bd_disk;
        const int rw = bio_data_dir(bio);
        int cpu = part_stat_lock();
        part_round_stats(cpu, &disk->part0);
        part_stat_inc(cpu, &disk->part0, ios[rw]);
        part_stat_add(cpu, &disk->part0, sectors[rw], bio_sectors(bio));
        part_inc_in_flight(&disk->part0, rw);
        part_stat_unlock();
}

static void nvme_end_io_acct(struct bio *bio, unsigned long start_time)
{
        struct gendisk *disk = bio->bi_bdev->bd_disk;
        const int rw = bio_data_dir(bio);
        unsigned long duration = jiffies - start_time;
        int cpu = part_stat_lock();
        part_stat_add(cpu, &disk->part0, ticks[rw], duration);
        part_round_stats(cpu, &disk->part0);
        part_dec_in_flight(&disk->part0, rw);
        part_stat_unlock();
}

static void bio_completion(struct nvme_dev *dev, void *ctx,
                                                struct nvme_completion *cqe)
{
        struct nvme_iod *iod = ctx;
        struct bio *bio = iod->private;
        u16 status = le16_to_cpup(&cqe->status) >> 1;

        if (iod->nents) {
                dma_unmap_sg(&dev->pci_dev->dev, iod->sg, iod->nents,
                        bio_data_dir(bio) ? DMA_TO_DEVICE : DMA_FROM_DEVICE);
                nvme_end_io_acct(bio, iod->start_time);
        }
        nvme_free_iod(dev, iod);
        if (status)
                bio_endio(bio, -EIO);
        else
                bio_endio(bio, 0);
}

/* length is in bytes.  gfp flags indicates whether we may sleep. */
int nvme_setup_prps(struct nvme_dev *dev, struct nvme_common_command *cmd,
                        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);
        int offset = offset_in_page(dma_addr);
        __le64 *prp_list;
        __le64 **list = iod_list(iod);
        dma_addr_t prp_dma;
        int nprps, i;

        cmd->prp1 = cpu_to_le64(dma_addr);
        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) {
                cmd->prp2 = cpu_to_le64(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) {
                cmd->prp2 = cpu_to_le64(dma_addr);
                iod->npages = -1;
                return (total_len - length) + PAGE_SIZE;
        }
        list[0] = prp_list;
        iod->first_dma = prp_dma;
        cmd->prp2 = cpu_to_le64(prp_dma);
        i = 0;
        for (;;) {
                if (i == PAGE_SIZE / 8) {
                        __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 int nvme_split_and_submit(struct bio *bio, struct nvme_queue *nvmeq,
                                 int len)
{
        struct bio *split = bio_split(bio, len >> 9, GFP_ATOMIC, NULL);
        if (!split)
                return -ENOMEM;

        bio_chain(split, bio);

        if (bio_list_empty(&nvmeq->sq_cong))
                add_wait_queue(&nvmeq->sq_full, &nvmeq->sq_cong_wait);
        bio_list_add(&nvmeq->sq_cong, split);
        bio_list_add(&nvmeq->sq_cong, bio);

        return 0;
}

/* NVMe scatterlists require no holes in the virtual address */
#define BIOVEC_NOT_VIRT_MERGEABLE(vec1, vec2)   ((vec2)->bv_offset || \
                        (((vec1)->bv_offset + (vec1)->bv_len) % PAGE_SIZE))

static int nvme_map_bio(struct nvme_queue *nvmeq, struct nvme_iod *iod,
                struct bio *bio, enum dma_data_direction dma_dir, int psegs)
{
        struct bio_vec bvec, bvprv;
        struct bvec_iter iter;
        struct scatterlist *sg = NULL;
        int length = 0, nsegs = 0, split_len = bio->bi_iter.bi_size;
        int first = 1;

        if (nvmeq->dev->stripe_size)
                split_len = nvmeq->dev->stripe_size -
                        ((bio->bi_iter.bi_sector << 9) &
                         (nvmeq->dev->stripe_size - 1));

        sg_init_table(iod->sg, psegs);
        bio_for_each_segment(bvec, bio, iter) {
                if (!first && BIOVEC_PHYS_MERGEABLE(&bvprv, &bvec)) {
                        sg->length += bvec.bv_len;
                } else {
                        if (!first && BIOVEC_NOT_VIRT_MERGEABLE(&bvprv, &bvec))
                                return nvme_split_and_submit(bio, nvmeq,
                                                             length);

                        sg = sg ? sg + 1 : iod->sg;
                        sg_set_page(sg, bvec.bv_page,
                                    bvec.bv_len, bvec.bv_offset);
                        nsegs++;
                }

                if (split_len - length < bvec.bv_len)
                        return nvme_split_and_submit(bio, nvmeq, split_len);
                length += bvec.bv_len;
                bvprv = bvec;
                first = 0;
        }
        iod->nents = nsegs;
        sg_mark_end(sg);
        if (dma_map_sg(nvmeq->q_dmadev, iod->sg, iod->nents, dma_dir) == 0)
                return -ENOMEM;

        BUG_ON(length != bio->bi_iter.bi_size);
        return length;
}

/*
 * 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 int nvme_submit_discard(struct nvme_queue *nvmeq, struct nvme_ns *ns,
                struct bio *bio, struct nvme_iod *iod, int cmdid)
{
        struct nvme_dsm_range *range;
        struct nvme_command *cmnd = &nvmeq->sq_cmds[nvmeq->sq_tail];

        range = dma_pool_alloc(nvmeq->dev->prp_small_pool, GFP_ATOMIC,
                                                        &iod->first_dma);
        if (!range)
                return -ENOMEM;

        iod_list(iod)[0] = (__le64 *)range;
        iod->npages = 0;

        range->cattr = cpu_to_le32(0);
        range->nlb = cpu_to_le32(bio->bi_iter.bi_size >> ns->lba_shift);
        range->slba = cpu_to_le64(nvme_block_nr(ns, bio->bi_iter.bi_sector));

        memset(cmnd, 0, sizeof(*cmnd));
        cmnd->dsm.opcode = nvme_cmd_dsm;
        cmnd->dsm.command_id = cmdid;
        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);

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

        return 0;
}

static int nvme_submit_flush(struct nvme_queue *nvmeq, struct nvme_ns *ns,
                                                                int cmdid)
{
        struct nvme_command *cmnd = &nvmeq->sq_cmds[nvmeq->sq_tail];

        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);

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

        return 0;
}

int nvme_submit_flush_data(struct nvme_queue *nvmeq, struct nvme_ns *ns)
{
        int cmdid = alloc_cmdid(nvmeq, (void *)CMD_CTX_FLUSH,
                                        special_completion, NVME_IO_TIMEOUT);
        if (unlikely(cmdid < 0))
                return cmdid;

        return nvme_submit_flush(nvmeq, ns, cmdid);
}

/*
 * Called with local interrupts disabled and the q_lock held.  May not sleep.
 */
static int nvme_submit_bio_queue(struct nvme_queue *nvmeq, struct nvme_ns *ns,
                                                                struct bio *bio)
{
        struct nvme_command *cmnd;
        struct nvme_iod *iod;
        enum dma_data_direction dma_dir;
        int cmdid, length, result;
        u16 control;
        u32 dsmgmt;
        int psegs = bio_phys_segments(ns->queue, bio);

        if ((bio->bi_rw & REQ_FLUSH) && psegs) {
                result = nvme_submit_flush_data(nvmeq, ns);
                if (result)
                        return result;
        }

        result = -ENOMEM;
        iod = nvme_alloc_iod(psegs, bio->bi_iter.bi_size, GFP_ATOMIC);
        if (!iod)
                goto nomem;
        iod->private = bio;

        result = -EBUSY;
        cmdid = alloc_cmdid(nvmeq, iod, bio_completion, NVME_IO_TIMEOUT);
        if (unlikely(cmdid < 0))
                goto free_iod;

        if (bio->bi_rw & REQ_DISCARD) {
                result = nvme_submit_discard(nvmeq, ns, bio, iod, cmdid);
                if (result)
                        goto free_cmdid;
                return result;
        }
        if ((bio->bi_rw & REQ_FLUSH) && !psegs)
                return nvme_submit_flush(nvmeq, ns, cmdid);

        control = 0;
        if (bio->bi_rw & REQ_FUA)
                control |= NVME_RW_FUA;
        if (bio->bi_rw & (REQ_FAILFAST_DEV | REQ_RAHEAD))
                control |= NVME_RW_LR;

        dsmgmt = 0;
        if (bio->bi_rw & REQ_RAHEAD)
                dsmgmt |= NVME_RW_DSM_FREQ_PREFETCH;

        cmnd = &nvmeq->sq_cmds[nvmeq->sq_tail];

        memset(cmnd, 0, sizeof(*cmnd));
        if (bio_data_dir(bio)) {
                cmnd->rw.opcode = nvme_cmd_write;
                dma_dir = DMA_TO_DEVICE;
        } else {
                cmnd->rw.opcode = nvme_cmd_read;
                dma_dir = DMA_FROM_DEVICE;
        }

        result = nvme_map_bio(nvmeq, iod, bio, dma_dir, psegs);
        if (result <= 0)
                goto free_cmdid;
        length = result;

        cmnd->rw.command_id = cmdid;
        cmnd->rw.nsid = cpu_to_le32(ns->ns_id);
        length = nvme_setup_prps(nvmeq->dev, &cmnd->common, iod, length,
                                                                GFP_ATOMIC);
        cmnd->rw.slba = cpu_to_le64(nvme_block_nr(ns, bio->bi_iter.bi_sector));
        cmnd->rw.length = cpu_to_le16((length >> ns->lba_shift) - 1);
        cmnd->rw.control = cpu_to_le16(control);
        cmnd->rw.dsmgmt = cpu_to_le32(dsmgmt);

        nvme_start_io_acct(bio);
        if (++nvmeq->sq_tail == nvmeq->q_depth)
                nvmeq->sq_tail = 0;
        writel(nvmeq->sq_tail, nvmeq->q_db);

        return 0;

 free_cmdid:
        free_cmdid(nvmeq, cmdid, NULL);
 free_iod:
        nvme_free_iod(nvmeq->dev, iod);
 nomem:
        return result;
}

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 = free_cmdid(nvmeq, cqe.command_id, &fn);
                fn(nvmeq->dev, 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 void nvme_make_request(struct request_queue *q, struct bio *bio)
{
        struct nvme_ns *ns = q->queuedata;
        struct nvme_queue *nvmeq = get_nvmeq(ns->dev);
        int result = -EBUSY;

        if (!nvmeq) {
                put_nvmeq(NULL);
                bio_endio(bio, -EIO);
                return;
        }

        spin_lock_irq(&nvmeq->q_lock);
        if (!nvmeq->q_suspended && bio_list_empty(&nvmeq->sq_cong))
                result = nvme_submit_bio_queue(nvmeq, ns, bio);
        if (unlikely(result)) {
                if (bio_list_empty(&nvmeq->sq_cong))
                        add_wait_queue(&nvmeq->sq_full, &nvmeq->sq_cong_wait);
                bio_list_add(&nvmeq->sq_cong, bio);
        }

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

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;
}

static void nvme_abort_command(struct nvme_queue *nvmeq, int cmdid)
{
        spin_lock_irq(&nvmeq->q_lock);
        cancel_cmdid(nvmeq, cmdid, NULL);
        spin_unlock_irq(&nvmeq->q_lock);
}

struct sync_cmd_info {
        struct task_struct *task;
        u32 result;
        int status;
};

static void sync_completion(struct nvme_dev *dev, void *ctx,
                                                struct nvme_completion *cqe)
{
        struct sync_cmd_info *cmdinfo = ctx;
        cmdinfo->result = le32_to_cpup(&cqe->result);
        cmdinfo->status = le16_to_cpup(&cqe->status) >> 1;
        wake_up_process(cmdinfo->task);
}

/*
 * 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
 */
static int nvme_submit_sync_cmd(struct nvme_dev *dev, int q_idx,
                                                struct nvme_command *cmd,
                                                u32 *result, unsigned timeout)
{
        int cmdid, ret;
        struct sync_cmd_info cmdinfo;
        struct nvme_queue *nvmeq;

        nvmeq = lock_nvmeq(dev, q_idx);
        if (!nvmeq) {
                unlock_nvmeq(nvmeq);
                return -ENODEV;
        }

        cmdinfo.task = current;
        cmdinfo.status = -EINTR;

        cmdid = alloc_cmdid(nvmeq, &cmdinfo, sync_completion, timeout);
        if (cmdid < 0) {
                unlock_nvmeq(nvmeq);
                return cmdid;
        }
        cmd->common.command_id = cmdid;

        set_current_state(TASK_KILLABLE);
        ret = nvme_submit_cmd(nvmeq, cmd);
        if (ret) {
                free_cmdid(nvmeq, cmdid, NULL);
                unlock_nvmeq(nvmeq);
                set_current_state(TASK_RUNNING);
                return ret;
        }
        unlock_nvmeq(nvmeq);
        schedule_timeout(timeout);

        if (cmdinfo.status == -EINTR) {
                nvmeq = lock_nvmeq(dev, q_idx);
                if (nvmeq)
                        nvme_abort_command(nvmeq, cmdid);
                unlock_nvmeq(nvmeq);
                return -EINTR;
        }

        if (result)
                *result = cmdinfo.result;

        return cmdinfo.status;
}

static int nvme_submit_async_cmd(struct nvme_queue *nvmeq,
                        struct nvme_command *cmd,
                        struct async_cmd_info *cmdinfo, unsigned timeout)
{
        int cmdid;

        cmdid = alloc_cmdid_killable(nvmeq, cmdinfo, async_completion, timeout);
        if (cmdid < 0)
                return cmdid;
        cmdinfo->status = -EINTR;
        cmd->common.command_id = cmdid;
        return nvme_submit_cmd(nvmeq, cmd);
}

int nvme_submit_admin_cmd(struct nvme_dev *dev, struct nvme_command *cmd,
                                                                u32 *result)
{
        return nvme_submit_sync_cmd(dev, 0, cmd, result, ADMIN_TIMEOUT);
}

int nvme_submit_io_cmd(struct nvme_dev *dev, struct nvme_command *cmd,
                                                                u32 *result)
{
        return nvme_submit_sync_cmd(dev, smp_processor_id() + 1, cmd, result,
                                                        NVME_IO_TIMEOUT);
}

static int nvme_submit_admin_cmd_async(struct nvme_dev *dev,
                struct nvme_command *cmd, struct async_cmd_info *cmdinfo)
{
        return nvme_submit_async_cmd(raw_nvmeq(dev, 0), cmd, cmdinfo,
                                                                ADMIN_TIMEOUT);
}

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

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

        status = nvme_submit_admin_cmd(dev, &c, NULL);
        if (status)
                return -EIO;
        return 0;
}

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

        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);

        status = nvme_submit_admin_cmd(dev, &c, NULL);
        if (status)
                return -EIO;
        return 0;
}

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

        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);

        status = nvme_submit_admin_cmd(dev, &c, NULL);
        if (status)
                return -EIO;
        return 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(struct nvme_dev *dev, unsigned nsid, unsigned cns,
                                                        dma_addr_t dma_addr)
{
        struct nvme_command c;

        memset(&c, 0, sizeof(c));
        c.identify.opcode = nvme_admin_identify;
        c.identify.nsid = cpu_to_le32(nsid);
        c.identify.prp1 = cpu_to_le64(dma_addr);
        c.identify.cns = cpu_to_le32(cns);

        return nvme_submit_admin_cmd(dev, &c, NULL);
}

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_admin_cmd(dev, &c, result);
}

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_admin_cmd(dev, &c, result);
}

/**
 * nvme_abort_cmd - Attempt aborting a command
 * @cmdid: Command id of a timed out IO
 * @queue: The queue with timed out IO
 *
 * 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_cmd(int cmdid, struct nvme_queue *nvmeq)
{
        int a_cmdid;
        struct nvme_command cmd;
        struct nvme_dev *dev = nvmeq->dev;
        struct nvme_cmd_info *info = nvme_cmd_info(nvmeq);
        struct nvme_queue *adminq;

        if (!nvmeq->qid || info[cmdid].aborted) {
                if (work_busy(&dev->reset_work))
                        return;
                list_del_init(&dev->node);
                dev_warn(&dev->pci_dev->dev,
                        "I/O %d QID %d timeout, reset controller\n", cmdid,
                                                                nvmeq->qid);
                PREPARE_WORK(&dev->reset_work, nvme_reset_failed_dev);
                queue_work(nvme_workq, &dev->reset_work);
                return;
        }

        if (!dev->abort_limit)
                return;

        adminq = rcu_dereference(dev->queues[0]);
        a_cmdid = alloc_cmdid(adminq, CMD_CTX_ABORT, special_completion,
                                                                ADMIN_TIMEOUT);
        if (a_cmdid < 0)
                return;

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

        --dev->abort_limit;
        info[cmdid].aborted = 1;
        info[cmdid].timeout = jiffies + ADMIN_TIMEOUT;

        dev_warn(nvmeq->q_dmadev, "Aborting I/O %d QID %d\n", cmdid,
                                                        nvmeq->qid);
        nvme_submit_cmd(adminq, &cmd);
}

/**
 * nvme_cancel_ios - Cancel outstanding I/Os
 * @queue: The queue to cancel I/Os on
 * @timeout: True to only cancel I/Os which have timed out
 */
static void nvme_cancel_ios(struct nvme_queue *nvmeq, bool timeout)
{
        int depth = nvmeq->q_depth - 1;
        struct nvme_cmd_info *info = nvme_cmd_info(nvmeq);
        unsigned long now = jiffies;
        int cmdid;

        for_each_set_bit(cmdid, nvmeq->cmdid_data, depth) {
                void *ctx;
                nvme_completion_fn fn;
                static struct nvme_completion cqe = {
                        .status = cpu_to_le16(NVME_SC_ABORT_REQ << 1),
                };

                if (timeout && !time_after(now, info[cmdid].timeout))
                        continue;
                if (info[cmdid].ctx == CMD_CTX_CANCELLED)
                        continue;
                if (timeout && nvmeq->dev->initialized) {
                        nvme_abort_cmd(cmdid, nvmeq);
                        continue;
                }
                dev_warn(nvmeq->q_dmadev, "Cancelling I/O %d QID %d\n", cmdid,
                                                                nvmeq->qid);
                ctx = cancel_cmdid(nvmeq, cmdid, &fn);
                fn(nvmeq->dev, ctx, &cqe);
        }
}

static void nvme_free_queue(struct rcu_head *r)
{
        struct nvme_queue *nvmeq = container_of(r, struct nvme_queue, r_head);

        spin_lock_irq(&nvmeq->q_lock);
        while (bio_list_peek(&nvmeq->sq_cong)) {
                struct bio *bio = bio_list_pop(&nvmeq->sq_cong);
                bio_endio(bio, -EIO);
        }
        spin_unlock_irq(&nvmeq->q_lock);

        dma_free_coherent(nvmeq->q_dmadev, CQ_SIZE(nvmeq->q_depth),
                                (void *)nvmeq->cqes, nvmeq->cq_dma_addr);
        dma_free_coherent(nvmeq->q_dmadev, SQ_SIZE(nvmeq->q_depth),
                                        nvmeq->sq_cmds, nvmeq->sq_dma_addr);
        if (nvmeq->qid)
                free_cpumask_var(nvmeq->cpu_mask);
        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 = raw_nvmeq(dev, i);
                rcu_assign_pointer(dev->queues[i], NULL);
                call_rcu(&nvmeq->r_head, nvme_free_queue);
                dev->queue_count--;
        }
}

/**
 * nvme_suspend_queue - put queue into suspended state
 * @nvmeq - queue to suspend
 *
 * Returns 1 if already suspended, 0 otherwise.
 */
static int nvme_suspend_queue(struct nvme_queue *nvmeq)
{
        int vector = nvmeq->dev->entry[nvmeq->cq_vector].vector;

        spin_lock_irq(&nvmeq->q_lock);
        if (nvmeq->q_suspended) {
                spin_unlock_irq(&nvmeq->q_lock);
                return 1;
        }
        nvmeq->q_suspended = 1;
        nvmeq->dev->online_queues--;
        spin_unlock_irq(&nvmeq->q_lock);

        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);
        nvme_process_cq(nvmeq);
        nvme_cancel_ios(nvmeq, false);
        spin_unlock_irq(&nvmeq->q_lock);
}

static void nvme_disable_queue(struct nvme_dev *dev, int qid)
{
        struct nvme_queue *nvmeq = raw_nvmeq(dev, 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);
        }
        nvme_clear_queue(nvmeq);
}

static struct nvme_queue *nvme_alloc_queue(struct nvme_dev *dev, int qid,
                                                        int depth, int vector)
{
        struct device *dmadev = &dev->pci_dev->dev;
        unsigned extra = nvme_queue_extra(depth);
        struct nvme_queue *nvmeq = kzalloc(sizeof(*nvmeq) + extra, GFP_KERNEL);
        if (!nvmeq)
                return NULL;

        nvmeq->cqes = dma_alloc_coherent(dmadev, CQ_SIZE(depth),
                                        &nvmeq->cq_dma_addr, GFP_KERNEL);
        if (!nvmeq->cqes)
                goto free_nvmeq;
        memset((void *)nvmeq->cqes, 0, CQ_SIZE(depth));

        nvmeq->sq_cmds = dma_alloc_coherent(dmadev, SQ_SIZE(depth),
                                        &nvmeq->sq_dma_addr, GFP_KERNEL);
        if (!nvmeq->sq_cmds)
                goto free_cqdma;

        if (qid && !zalloc_cpumask_var(&nvmeq->cpu_mask, GFP_KERNEL))
                goto free_sqdma;

        nvmeq->q_dmadev = dmadev;
        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;
        init_waitqueue_head(&nvmeq->sq_full);
        init_waitqueue_entry(&nvmeq->sq_cong_wait, nvme_thread);
        bio_list_init(&nvmeq->sq_cong);
        nvmeq->q_db = &dev->dbs[qid * 2 * dev->db_stride];
        nvmeq->q_depth = depth;
        nvmeq->cq_vector = vector;
        nvmeq->qid = qid;
        nvmeq->q_suspended = 1;
        dev->queue_count++;
        rcu_assign_pointer(dev->queues[qid], nvmeq);

        return nvmeq;

 free_sqdma:
        dma_free_coherent(dmadev, SQ_SIZE(depth), (void *)nvmeq->sq_cmds,
                                                        nvmeq->sq_dma_addr);
 free_cqdma:
        dma_free_coherent(dmadev, 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;
        unsigned extra = nvme_queue_extra(nvmeq->q_depth);

        nvmeq->sq_tail = 0;
        nvmeq->cq_head = 0;
        nvmeq->cq_phase = 1;
        nvmeq->q_db = &dev->dbs[qid * 2 * dev->db_stride];
        memset(nvmeq->cmdid_data, 0, extra);
        memset((void *)nvmeq->cqes, 0, CQ_SIZE(nvmeq->q_depth));
        nvme_cancel_ios(nvmeq, false);
        nvmeq->q_suspended = 0;
        dev->online_queues++;
}

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

        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;

        spin_lock_irq(&nvmeq->q_lock);
        nvme_init_queue(nvmeq, qid);
        spin_unlock_irq(&nvmeq->q_lock);

        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->pci_dev->dev,
                                "Device not ready; aborting initialisation\n");
                        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)
{
        u32 cc = readl(&dev->bar->cc);

        if (cc & NVME_CC_ENABLE)
                writel(cc & ~NVME_CC_ENABLE, &dev->bar->cc);
        return nvme_wait_ready(dev, cap, false);
}

static int nvme_enable_ctrl(struct nvme_dev *dev, u64 cap)
{
        return nvme_wait_ready(dev, cap, true);
}

static int nvme_shutdown_ctrl(struct nvme_dev *dev)
{
        unsigned long timeout;
        u32 cc;

        cc = (readl(&dev->bar->cc) & ~NVME_CC_SHN_MASK) | NVME_CC_SHN_NORMAL;
        writel(cc, &dev->bar->cc);

        timeout = 2 * HZ + 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->pci_dev->dev,
                                "Device shutdown incomplete; abort shutdown\n");
                        return -ENODEV;
                }
        }

        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;

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

        nvmeq = raw_nvmeq(dev, 0);
        if (!nvmeq) {
                nvmeq = nvme_alloc_queue(dev, 0, 64, 0);
                if (!nvmeq)
                        return -ENOMEM;
        }

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

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

        result = nvme_enable_ctrl(dev, cap);
        if (result)
                return result;

        result = queue_request_irq(dev, nvmeq, nvmeq->irqname);
        if (result)
                return result;

        spin_lock_irq(&nvmeq->q_lock);
        nvme_init_queue(nvmeq, 0);
        spin_unlock_irq(&nvmeq->q_lock);
        return result;
}

struct nvme_iod *nvme_map_user_pages(struct nvme_dev *dev, int write,
                                unsigned long addr, unsigned length)
{
        int i, err, count, nents, offset;
        struct scatterlist *sg;
        struct page **pages;
        struct nvme_iod *iod;

        if (addr & 3)
                return ERR_PTR(-EINVAL);
        if (!length || length > INT_MAX - PAGE_SIZE)
                return ERR_PTR(-EINVAL);

        offset = offset_in_page(addr);
        count = DIV_ROUND_UP(offset + length, PAGE_SIZE);
        pages = kcalloc(count, sizeof(*pages), GFP_KERNEL);
        if (!pages)
                return ERR_PTR(-ENOMEM);

        err = get_user_pages_fast(addr, count, 1, pages);
        if (err < count) {
                count = err;
                err = -EFAULT;
                goto put_pages;
        }

        iod = nvme_alloc_iod(count, length, GFP_KERNEL);
        sg = iod->sg;
        sg_init_table(sg, count);
        for (i = 0; i < count; i++) {
                sg_set_page(&sg[i], pages[i],
                            min_t(unsigned, length, PAGE_SIZE - offset),
                            offset);
                length -= (PAGE_SIZE - offset);
                offset = 0;
        }
        sg_mark_end(&sg[i - 1]);
        iod->nents = count;

        err = -ENOMEM;
        nents = dma_map_sg(&dev->pci_dev->dev, sg, count,
                                write ? DMA_TO_DEVICE : DMA_FROM_DEVICE);
        if (!nents)
                goto free_iod;

        kfree(pages);
        return iod;

 free_iod:
        kfree(iod);
 put_pages:
        for (i = 0; i < count; i++)
                put_page(pages[i]);
        kfree(pages);
        return ERR_PTR(err);
}

void nvme_unmap_user_pages(struct nvme_dev *dev, int write,
                        struct nvme_iod *iod)
{
        int i;

        dma_unmap_sg(&dev->pci_dev->dev, iod->sg, iod->nents,
                                write ? DMA_TO_DEVICE : DMA_FROM_DEVICE);

        for (i = 0; i < iod->nents; i++)
                put_page(sg_page(&iod->sg[i]));
}

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, i;
        struct nvme_iod *iod, *meta_iod = NULL;
        dma_addr_t meta_dma_addr;
        void *meta, *uninitialized_var(meta_mem);

        if (copy_from_user(&io, uio, sizeof(io)))
                return -EFAULT;
        length = (io.nblocks + 1) << ns->lba_shift;
        meta_len = (io.nblocks + 1) * ns->ms;

        if (meta_len && ((io.metadata & 3) || !io.metadata))
                return -EINVAL;

        switch (io.opcode) {
        case nvme_cmd_write:
        case nvme_cmd_read:
        case nvme_cmd_compare:
                iod = nvme_map_user_pages(dev, io.opcode & 1, io.addr, length);
                break;
        default:
                return -EINVAL;
        }

        if (IS_ERR(iod))
                return PTR_ERR(iod);

        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);

        if (meta_len) {
                meta_iod = nvme_map_user_pages(dev, io.opcode & 1, io.metadata,
                                                                meta_len);
                if (IS_ERR(meta_iod)) {
                        status = PTR_ERR(meta_iod);
                        meta_iod = NULL;
                        goto unmap;
                }

                meta_mem = dma_alloc_coherent(&dev->pci_dev->dev, meta_len,
                                                &meta_dma_addr, GFP_KERNEL);
                if (!meta_mem) {
                        status = -ENOMEM;
                        goto unmap;
                }

                if (io.opcode & 1) {
                        int meta_offset = 0;

                        for (i = 0; i < meta_iod->nents; i++) {
                                meta = kmap_atomic(sg_page(&meta_iod->sg[i])) +
                                                meta_iod->sg[i].offset;
                                memcpy(meta_mem + meta_offset, meta,
                                                meta_iod->sg[i].length);
                                kunmap_atomic(meta);
                                meta_offset += meta_iod->sg[i].length;
                        }
                }

                c.rw.metadata = cpu_to_le64(meta_dma_addr);
        }

        length = nvme_setup_prps(dev, &c.common, iod, length, GFP_KERNEL);

        if (length != (io.nblocks + 1) << ns->lba_shift)
                status = -ENOMEM;
        else
                status = nvme_submit_io_cmd(dev, &c, NULL);

        if (meta_len) {
                if (status == NVME_SC_SUCCESS && !(io.opcode & 1)) {
                        int meta_offset = 0;

                        for (i = 0; i < meta_iod->nents; i++) {
                                meta = kmap_atomic(sg_page(&meta_iod->sg[i])) +
                                                meta_iod->sg[i].offset;
                                memcpy(meta, meta_mem + meta_offset,
                                                meta_iod->sg[i].length);
                                kunmap_atomic(meta);
                                meta_offset += meta_iod->sg[i].length;
                        }
                }

                dma_free_coherent(&dev->pci_dev->dev, meta_len, meta_mem,
                                                                meta_dma_addr);
        }

 unmap:
        nvme_unmap_user_pages(dev, io.opcode & 1, iod);
        nvme_free_iod(dev, iod);

        if (meta_iod) {
                nvme_unmap_user_pages(dev, io.opcode & 1, meta_iod);
                nvme_free_iod(dev, meta_iod);
        }

        return status;
}

static int nvme_user_admin_cmd(struct nvme_dev *dev,
                                        struct nvme_admin_cmd __user *ucmd)
{
        struct nvme_admin_cmd cmd;
        struct nvme_command c;
        int status, length;
        struct nvme_iod *uninitialized_var(iod);
        unsigned timeout;

        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);

        length = cmd.data_len;
        if (cmd.data_len) {
                iod = nvme_map_user_pages(dev, cmd.opcode & 1, cmd.addr,
                                                                length);
                if (IS_ERR(iod))
                        return PTR_ERR(iod);
                length = nvme_setup_prps(dev, &c.common, iod, length,
                                                                GFP_KERNEL);
        }

        timeout = cmd.timeout_ms ? msecs_to_jiffies(cmd.timeout_ms) :
                                                                ADMIN_TIMEOUT;
        if (length != cmd.data_len)
                status = -ENOMEM;
        else
                status = nvme_submit_sync_cmd(dev, 0, &c, &cmd.result, timeout);

        if (cmd.data_len) {
                nvme_unmap_user_pages(dev, cmd.opcode & 1, iod);
                nvme_free_iod(dev, iod);
        }

        if ((status >= 0) && copy_to_user(&ucmd->result, &cmd.result,
                                                        sizeof(cmd.result)))
                status = -EFAULT;

        return status;
}

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_admin_cmd(ns->dev, (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)
{
        struct nvme_ns *ns = bdev->bd_disk->private_data;

        switch (cmd) {
        case SG_IO:
                return nvme_sg_io32(ns, arg);
        }
        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)
{
        struct nvme_ns *ns = bdev->bd_disk->private_data;
        struct nvme_dev *dev = ns->dev;

        kref_get(&dev->kref);
        return 0;
}

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 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,
};

static void nvme_resubmit_bios(struct nvme_queue *nvmeq)
{
        while (bio_list_peek(&nvmeq->sq_cong)) {
                struct bio *bio = bio_list_pop(&nvmeq->sq_cong);
                struct nvme_ns *ns = bio->bi_bdev->bd_disk->private_data;

                if (bio_list_empty(&nvmeq->sq_cong))
                        remove_wait_queue(&nvmeq->sq_full,
                                                        &nvmeq->sq_cong_wait);
                if (nvme_submit_bio_queue(nvmeq, ns, bio)) {
                        if (bio_list_empty(&nvmeq->sq_cong))
                                add_wait_queue(&nvmeq->sq_full,
                                                        &nvmeq->sq_cong_wait);
                        bio_list_add_head(&nvmeq->sq_cong, bio);
                        break;
                }
        }
}

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;
                        if (readl(&dev->bar->csts) & NVME_CSTS_CFS &&
                                                        dev->initialized) {
                                if (work_busy(&dev->reset_work))
                                        continue;
                                list_del_init(&dev->node);
                                dev_warn(&dev->pci_dev->dev,
                                        "Failed status, reset controller\n");
                                PREPARE_WORK(&dev->reset_work,
                                                        nvme_reset_failed_dev);
                                queue_work(nvme_workq, &dev->reset_work);
                                continue;
                        }
                        rcu_read_lock();
                        for (i = 0; i < dev->queue_count; i++) {
                                struct nvme_queue *nvmeq =
                                                rcu_dereference(dev->queues[i]);
                                if (!nvmeq)
                                        continue;
                                spin_lock_irq(&nvmeq->q_lock);
                                if (nvmeq->q_suspended)
                                        goto unlock;
                                nvme_process_cq(nvmeq);
                                nvme_cancel_ios(nvmeq, true);
                                nvme_resubmit_bios(nvmeq);
 unlock:
                                spin_unlock_irq(&nvmeq->q_lock);
                        }
                        rcu_read_unlock();
                }
                spin_unlock(&dev_list_lock);
                schedule_timeout(round_jiffies_relative(HZ));
        }
        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;
        ns->queue->limits.max_discard_sectors = 0xffffffff;
        queue_flag_set_unlocked(QUEUE_FLAG_DISCARD, ns->queue);
}

static struct nvme_ns *nvme_alloc_ns(struct nvme_dev *dev, unsigned nsid,
                        struct nvme_id_ns *id, struct nvme_lba_range_type *rt)
{
        struct nvme_ns *ns;
        struct gendisk *disk;
        int lbaf;

        if (rt->attributes & NVME_LBART_ATTRIB_HIDE)
                return NULL;

        ns = kzalloc(sizeof(*ns), GFP_KERNEL);
        if (!ns)
                return NULL;
        ns->queue = blk_alloc_queue(GFP_KERNEL);
        if (!ns->queue)
                goto out_free_ns;
        ns->queue->queue_flags = QUEUE_FLAG_DEFAULT;
        queue_flag_set_unlocked(QUEUE_FLAG_NOMERGES, ns->queue);
        queue_flag_set_unlocked(QUEUE_FLAG_NONROT, ns->queue);
        blk_queue_make_request(ns->queue, nvme_make_request);
        ns->dev = dev;
        ns->queue->queuedata = ns;

        disk = alloc_disk(0);
        if (!disk)
                goto out_free_queue;
        ns->ns_id = nsid;
        ns->disk = disk;
        lbaf = id->flbas & 0xf;
        ns->lba_shift = id->lbaf[lbaf].ds;
        ns->ms = le16_to_cpu(id->lbaf[lbaf].ms);
        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);

        disk->major = nvme_major;
        disk->first_minor = 0;
        disk->fops = &nvme_fops;
        disk->private_data = ns;
        disk->queue = ns->queue;
        disk->driverfs_dev = &dev->pci_dev->dev;
        disk->flags = GENHD_FL_EXT_DEVT;
        sprintf(disk->disk_name, "nvme%dn%d", dev->instance, nsid);
        set_capacity(disk, le64_to_cpup(&id->nsze) << (ns->lba_shift - 9));

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

        return ns;

 out_free_queue:
        blk_cleanup_queue(ns->queue);
 out_free_ns:
        kfree(ns);
        return NULL;
}

static int nvme_find_closest_node(int node)
{
        int n, val, min_val = INT_MAX, best_node = node;

        for_each_online_node(n) {
                if (n == node)
                        continue;
                val = node_distance(node, n);
                if (val < min_val) {
                        min_val = val;
                        best_node = n;
                }
        }
        return best_node;
}

static void nvme_set_queue_cpus(cpumask_t *qmask, struct nvme_queue *nvmeq,
                                                                int count)
{
        int cpu;
        for_each_cpu(cpu, qmask) {
                if (cpumask_weight(nvmeq->cpu_mask) >= count)
                        break;
                if (!cpumask_test_and_set_cpu(cpu, nvmeq->cpu_mask))
                        *per_cpu_ptr(nvmeq->dev->io_queue, cpu) = nvmeq->qid;
        }
}

static void nvme_add_cpus(cpumask_t *mask, const cpumask_t *unassigned_cpus,
        const cpumask_t *new_mask, struct nvme_queue *nvmeq, int cpus_per_queue)
{
        int next_cpu;
        for_each_cpu(next_cpu, new_mask) {
                cpumask_or(mask, mask, get_cpu_mask(next_cpu));
                cpumask_or(mask, mask, topology_thread_cpumask(next_cpu));
                cpumask_and(mask, mask, unassigned_cpus);
                nvme_set_queue_cpus(mask, nvmeq, cpus_per_queue);
        }
}

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

        max = min(dev->max_qid, num_online_cpus());
        for (i = dev->queue_count; i <= max; i++)
                if (!nvme_alloc_queue(dev, i, dev->q_depth, i - 1))
                        break;

        max = min(dev->queue_count - 1, num_online_cpus());
        for (i = dev->online_queues; i <= max; i++)
                if (nvme_create_queue(raw_nvmeq(dev, i), i))
                        break;
}

/*
 * If there are fewer queues than online cpus, this will try to optimally
 * assign a queue to multiple cpus by grouping cpus that are "close" together:
 * thread siblings, core, socket, closest node, then whatever else is
 * available.
 */
static void nvme_assign_io_queues(struct nvme_dev *dev)
{
        unsigned cpu, cpus_per_queue, queues, remainder, i;
        cpumask_var_t unassigned_cpus;

        nvme_create_io_queues(dev);

        queues = min(dev->online_queues - 1, num_online_cpus());
        if (!queues)
                return;

        cpus_per_queue = num_online_cpus() / queues;
        remainder = queues - (num_online_cpus() - queues * cpus_per_queue);

        if (!alloc_cpumask_var(&unassigned_cpus, GFP_KERNEL))
                return;

        cpumask_copy(unassigned_cpus, cpu_online_mask);
        cpu = cpumask_first(unassigned_cpus);
        for (i = 1; i <= queues; i++) {
                struct nvme_queue *nvmeq = lock_nvmeq(dev, i);
                cpumask_t mask;

                cpumask_clear(nvmeq->cpu_mask);
                if (!cpumask_weight(unassigned_cpus)) {
                        unlock_nvmeq(nvmeq);
                        break;
                }

                mask = *get_cpu_mask(cpu);
                nvme_set_queue_cpus(&mask, nvmeq, cpus_per_queue);
                if (cpus_weight(mask) < cpus_per_queue)
                        nvme_add_cpus(&mask, unassigned_cpus,
                                topology_thread_cpumask(cpu),
                                nvmeq, cpus_per_queue);
                if (cpus_weight(mask) < cpus_per_queue)
                        nvme_add_cpus(&mask, unassigned_cpus,
                                topology_core_cpumask(cpu),
                                nvmeq, cpus_per_queue);
                if (cpus_weight(mask) < cpus_per_queue)
                        nvme_add_cpus(&mask, unassigned_cpus,
                                cpumask_of_node(cpu_to_node(cpu)),
                                nvmeq, cpus_per_queue);
                if (cpus_weight(mask) < cpus_per_queue)
                        nvme_add_cpus(&mask, unassigned_cpus,
                                cpumask_of_node(
                                        nvme_find_closest_node(
                                                cpu_to_node(cpu))),
                                nvmeq, cpus_per_queue);
                if (cpus_weight(mask) < cpus_per_queue)
                        nvme_add_cpus(&mask, unassigned_cpus,
                                unassigned_cpus,
                                nvmeq, cpus_per_queue);

                WARN(cpumask_weight(nvmeq->cpu_mask) != cpus_per_queue,
                        "nvme%d qid:%d mis-matched queue-to-cpu assignment\n",
                        dev->instance, i);

                irq_set_affinity_hint(dev->entry[nvmeq->cq_vector].vector,
                                                        nvmeq->cpu_mask);
                cpumask_andnot(unassigned_cpus, unassigned_cpus,
                                                nvmeq->cpu_mask);
                cpu = cpumask_next(cpu, unassigned_cpus);
                if (remainder && !--remainder)
                        cpus_per_queue++;
                unlock_nvmeq(nvmeq);
        }
        WARN(cpumask_weight(unassigned_cpus), "nvme%d unassigned online cpus\n",
                                                                dev->instance);
        i = 0;
        cpumask_andnot(unassigned_cpus, cpu_possible_mask, cpu_online_mask);
        for_each_cpu(cpu, unassigned_cpus)
                *per_cpu_ptr(dev->io_queue, cpu) = (i++ % queues) + 1;
        free_cpumask_var(unassigned_cpus);
}

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)
                return status < 0 ? -EIO : -EBUSY;
        return min(result & 0xffff, result >> 16) + 1;
}

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_cpu_notify(struct notifier_block *self,
                                unsigned long action, void *hcpu)
{
        struct nvme_dev *dev = container_of(self, struct nvme_dev, nb);
        switch (action) {
        case CPU_ONLINE:
        case CPU_DEAD:
                nvme_assign_io_queues(dev);
                break;
        }
        return NOTIFY_OK;
}

static int nvme_setup_io_queues(struct nvme_dev *dev)
{
        struct nvme_queue *adminq = raw_nvmeq(dev, 0);
        struct pci_dev *pdev = dev->pci_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;

        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);

        vecs = nr_io_queues;
        for (i = 0; i < vecs; i++)
                dev->entry[i].entry = i;
        for (;;) {
                result = pci_enable_msix(pdev, dev->entry, vecs);
                if (result <= 0)
                        break;
                vecs = result;
        }

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

        /*
         * 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->q_suspended = 1;
                goto free_queues;
        }

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

        dev->nb.notifier_call = &nvme_cpu_notify;
        result = register_hotcpu_notifier(&dev->nb);
        if (result)
                goto free_queues;

        return 0;

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

/*
 * 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 = dev->pci_dev;
        int res;
        unsigned nn, i;
        struct nvme_ns *ns;
        struct nvme_id_ctrl *ctrl;
        struct nvme_id_ns *id_ns;
        void *mem;
        dma_addr_t dma_addr;
        int shift = NVME_CAP_MPSMIN(readq(&dev->bar->cap)) + 12;

        mem = dma_alloc_coherent(&pdev->dev, 8192, &dma_addr, GFP_KERNEL);
        if (!mem)
                return -ENOMEM;

        res = nvme_identify(dev, 0, 1, dma_addr);
        if (res) {
                res = -EIO;
                goto out;
        }

        ctrl = mem;
        nn = le32_to_cpup(&ctrl->nn);
        dev->oncs = le16_to_cpup(&ctrl->oncs);
        dev->abort_limit = ctrl->acl + 1;
        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])
                dev->stripe_size = 1 << (ctrl->vs[3] + shift);

        id_ns = mem;
        for (i = 1; i <= nn; i++) {
                res = nvme_identify(dev, i, 0, dma_addr);
                if (res)
                        continue;

                if (id_ns->ncap == 0)
                        continue;

                res = nvme_get_features(dev, NVME_FEAT_LBA_RANGE, i,
                                                        dma_addr + 4096, NULL);
                if (res)
                        memset(mem + 4096, 0, 4096);

                ns = nvme_alloc_ns(dev, i, mem, mem + 4096);
                if (ns)
                        list_add_tail(&ns->list, &dev->namespaces);
        }
        list_for_each_entry(ns, &dev->namespaces, list)
                add_disk(ns->disk);
        res = 0;

 out:
        dma_free_coherent(&dev->pci_dev->dev, 8192, mem, dma_addr);
        return res;
}

static int nvme_dev_map(struct nvme_dev *dev)
{
        u64 cap;
        int bars, result = -ENOMEM;
        struct pci_dev *pdev = dev->pci_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 (pci_request_selected_regions(pdev, bars, "nvme"))
                goto disable_pci;

        if (dma_set_mask_and_coherent(&pdev->dev, DMA_BIT_MASK(64)) &&
            dma_set_mask_and_coherent(&pdev->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;
        }
        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;

        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)
{
        if (dev->pci_dev->msi_enabled)
                pci_disable_msi(dev->pci_dev);
        else if (dev->pci_dev->msix_enabled)
                pci_disable_msix(dev->pci_dev);

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

        if (pci_is_enabled(dev->pci_dev))
                pci_disable_device(dev->pci_dev);
}

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)) {
                        set_current_state(TASK_RUNNING);

                        nvme_disable_ctrl(dev, readq(&dev->bar->cap));
                        nvme_disable_queue(dev, 0);

                        send_sig(SIGKILL, dq->worker->task, 1);
                        flush_kthread_worker(dq->worker);
                        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_clear_queue(nvmeq);
        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_cmd_async(nvmeq->dev, &c, &nvmeq->cmdinfo);
}

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);
        allow_signal(SIGKILL);
        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->pci_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 = raw_nvmeq(dev, 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_dev_shutdown(struct nvme_dev *dev)
{
        int i;

        dev->initialized = 0;
        unregister_hotcpu_notifier(&dev->nb);

        nvme_dev_list_remove(dev);

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

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

        list_for_each_entry(ns, &dev->namespaces, list) {
                if (ns->disk->flags & GENHD_FL_UP)
                        del_gendisk(ns->disk);
                if (!blk_queue_dying(ns->queue))
                        blk_cleanup_queue(ns->queue);
        }
}

static int nvme_setup_prp_pools(struct nvme_dev *dev)
{
        struct device *dmadev = &dev->pci_dev->dev;
        dev->prp_page_pool = dma_pool_create("prp list page", dmadev,
                                                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", dmadev,
                                                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) {
                list_del(&ns->list);
                put_disk(ns->disk);
                kfree(ns);
        }
}

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

        nvme_free_namespaces(dev);
        free_percpu(dev->io_queue);
        kfree(dev->queues);
        kfree(dev->entry);
        kfree(dev);
}

static int nvme_dev_open(struct inode *inode, struct file *f)
{
        struct nvme_dev *dev = container_of(f->private_data, struct nvme_dev,
                                                                miscdev);
        kref_get(&dev->kref);
        f->private_data = dev;
        return 0;
}

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;
        switch (cmd) {
        case NVME_IOCTL_ADMIN_CMD:
                return nvme_user_admin_cmd(dev, (void __user *)arg);
        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 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(&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;
        }

        result = nvme_setup_io_queues(dev);
        if (result && result != -EBUSY)
                goto disable;

        return result;

 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 = dev->pci_dev;

        if (pci_get_drvdata(pdev))
                pci_stop_and_remove_bus_device(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_dev_remove(dev);
        nvme_free_queues(dev, 1);
}

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

        ret = nvme_dev_start(dev);
        if (ret && ret != -EBUSY)
                return ret;
        if (ret == -EBUSY) {
                spin_lock(&dev_list_lock);
                PREPARE_WORK(&dev->reset_work, nvme_remove_disks);
                queue_work(nvme_workq, &dev->reset_work);
                spin_unlock(&dev_list_lock);
        }
        dev->initialized = 1;
        return 0;
}

static void nvme_dev_reset(struct nvme_dev *dev)
{
        nvme_dev_shutdown(dev);
        if (nvme_dev_resume(dev)) {
                dev_err(&dev->pci_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->pci_dev->dev,
                                "Failed to start controller remove task\n");
                        kref_put(&dev->kref, nvme_free_dev);
                }
        }
}

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 int nvme_probe(struct pci_dev *pdev, const struct pci_device_id *id)
{
        int result = -ENOMEM;
        struct nvme_dev *dev;

        dev = kzalloc(sizeof(*dev), GFP_KERNEL);
        if (!dev)
                return -ENOMEM;
        dev->entry = kcalloc(num_possible_cpus(), sizeof(*dev->entry),
                                                                GFP_KERNEL);
        if (!dev->entry)
                goto free;
        dev->queues = kcalloc(num_possible_cpus() + 1, sizeof(void *),
                                                                GFP_KERNEL);
        if (!dev->queues)
                goto free;
        dev->io_queue = alloc_percpu(unsigned short);
        if (!dev->io_queue)
                goto free;

        INIT_LIST_HEAD(&dev->namespaces);
        INIT_WORK(&dev->reset_work, nvme_reset_failed_dev);
        dev->pci_dev = pdev;
        pci_set_drvdata(pdev, dev);
        result = nvme_set_instance(dev);
        if (result)
                goto free;

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

        kref_init(&dev->kref);
        result = nvme_dev_start(dev);
        if (result) {
                if (result == -EBUSY)
                        goto create_cdev;
                goto release_pools;
        }

        result = nvme_dev_add(dev);
        if (result)
                goto shutdown;

 create_cdev:
        scnprintf(dev->name, sizeof(dev->name), "nvme%d", dev->instance);
        dev->miscdev.minor = MISC_DYNAMIC_MINOR;
        dev->miscdev.parent = &pdev->dev;
        dev->miscdev.name = dev->name;
        dev->miscdev.fops = &nvme_dev_fops;
        result = misc_register(&dev->miscdev);
        if (result)
                goto remove;

        dev->initialized = 1;
        return 0;

 remove:
        nvme_dev_remove(dev);
        nvme_free_namespaces(dev);
 shutdown:
        nvme_dev_shutdown(dev);
 release_pools:
        nvme_free_queues(dev, 0);
        nvme_release_prp_pools(dev);
 release:
        nvme_release_instance(dev);
 free:
        free_percpu(dev->io_queue);
        kfree(dev->queues);
        kfree(dev->entry);
        kfree(dev);
        return result;
}

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->reset_work);
        misc_deregister(&dev->miscdev);
        nvme_dev_remove(dev);
        nvme_dev_shutdown(dev);
        nvme_free_queues(dev, 0);
        rcu_barrier();
        nvme_release_instance(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)) {
                PREPARE_WORK(&ndev->reset_work, 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,
};

/* 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 = pci_register_driver(&nvme_driver);
        if (result)
                goto unregister_blkdev;
        return 0;

 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);
        BUG_ON(nvme_thread && !IS_ERR(nvme_thread));
}

MODULE_AUTHOR("Matthew Wilcox <willy@linux.intel.com>");
MODULE_LICENSE("GPL");
MODULE_VERSION("0.9");
module_init(nvme_init);
module_exit(nvme_exit);