[deliverable/linux.git] / drivers / block / nvme-core.c

/*
 * NVM Express device driver
 * Copyright (c) 2011, 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/delay.h>
#include <linux/errno.h>
#include <linux/fs.h>
#include <linux/genhd.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/poison.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 NVME_MINORS 64
#define ADMIN_TIMEOUT   (60 * HZ)

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;

/*
 * An NVM Express queue.  Each device has at least two (one for admin
 * commands and one for I/O commands).
 */
struct nvme_queue {
        struct device *q_dmadev;
        struct nvme_dev *dev;
        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 cq_phase;
        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_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;
};

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

/**
 * 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;
        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)

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_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);
}

/*
 * 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;
}

struct nvme_queue *get_nvmeq(struct nvme_dev *dev)
{
        return dev->queues[get_cpu() + 1];
}

void put_nvmeq(struct nvme_queue *nvmeq)
{
        put_cpu();
}

/**
 * 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);
        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;
        }

        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 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_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;
}

struct nvme_bio_pair {
        struct bio b1, b2, *parent;
        struct bio_vec *bv1, *bv2;
        int err;
        atomic_t cnt;
};

static void nvme_bio_pair_endio(struct bio *bio, int err)
{
        struct nvme_bio_pair *bp = bio->bi_private;

        if (err)
                bp->err = err;

        if (atomic_dec_and_test(&bp->cnt)) {
                bio_endio(bp->parent, bp->err);
                if (bp->bv1)
                        kfree(bp->bv1);
                if (bp->bv2)
                        kfree(bp->bv2);
                kfree(bp);
        }
}

static struct nvme_bio_pair *nvme_bio_split(struct bio *bio, int idx,
                                                        int len, int offset)
{
        struct nvme_bio_pair *bp;

        BUG_ON(len > bio->bi_size);
        BUG_ON(idx > bio->bi_vcnt);

        bp = kmalloc(sizeof(*bp), GFP_ATOMIC);
        if (!bp)
                return NULL;
        bp->err = 0;

        bp->b1 = *bio;
        bp->b2 = *bio;

        bp->b1.bi_size = len;
        bp->b2.bi_size -= len;
        bp->b1.bi_vcnt = idx;
        bp->b2.bi_idx = idx;
        bp->b2.bi_sector += len >> 9;

        if (offset) {
                bp->bv1 = kmalloc(bio->bi_max_vecs * sizeof(struct bio_vec),
                                                                GFP_ATOMIC);
                if (!bp->bv1)
                        goto split_fail_1;

                bp->bv2 = kmalloc(bio->bi_max_vecs * sizeof(struct bio_vec),
                                                                GFP_ATOMIC);
                if (!bp->bv2)
                        goto split_fail_2;

                memcpy(bp->bv1, bio->bi_io_vec,
                        bio->bi_max_vecs * sizeof(struct bio_vec));
                memcpy(bp->bv2, bio->bi_io_vec,
                        bio->bi_max_vecs * sizeof(struct bio_vec));

                bp->b1.bi_io_vec = bp->bv1;
                bp->b2.bi_io_vec = bp->bv2;
                bp->b2.bi_io_vec[idx].bv_offset += offset;
                bp->b2.bi_io_vec[idx].bv_len -= offset;
                bp->b1.bi_io_vec[idx].bv_len = offset;
                bp->b1.bi_vcnt++;
        } else
                bp->bv1 = bp->bv2 = NULL;

        bp->b1.bi_private = bp;
        bp->b2.bi_private = bp;

        bp->b1.bi_end_io = nvme_bio_pair_endio;
        bp->b2.bi_end_io = nvme_bio_pair_endio;

        bp->parent = bio;
        atomic_set(&bp->cnt, 2);

        return bp;

 split_fail_2:
        kfree(bp->bv1);
 split_fail_1:
        kfree(bp);
        return NULL;
}

static int nvme_split_and_submit(struct bio *bio, struct nvme_queue *nvmeq,
                                                int idx, int len, int offset)
{
        struct nvme_bio_pair *bp = nvme_bio_split(bio, idx, len, offset);
        if (!bp)
                return -ENOMEM;

        if (bio_list_empty(&nvmeq->sq_cong))
                add_wait_queue(&nvmeq->sq_full, &nvmeq->sq_cong_wait);
        bio_list_add(&nvmeq->sq_cong, &bp->b1);
        bio_list_add(&nvmeq->sq_cong, &bp->b2);

        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 = NULL;
        struct scatterlist *sg = NULL;
        int i, length = 0, nsegs = 0;

        sg_init_table(iod->sg, psegs);
        bio_for_each_segment(bvec, bio, i) {
                if (bvprv && BIOVEC_PHYS_MERGEABLE(bvprv, bvec)) {
                        sg->length += bvec->bv_len;
                } else {
                        if (bvprv && BIOVEC_NOT_VIRT_MERGEABLE(bvprv, bvec))
                                return nvme_split_and_submit(bio, nvmeq, i,
                                                                length, 0);

                        sg = sg ? sg + 1 : iod->sg;
                        sg_set_page(sg, bvec->bv_page, bvec->bv_len,
                                                        bvec->bv_offset);
                        nsegs++;
                }
                length += bvec->bv_len;
                bvprv = bvec;
        }
        iod->nents = nsegs;
        sg_mark_end(sg);
        if (dma_map_sg(nvmeq->q_dmadev, iod->sg, iod->nents, dma_dir) == 0)
                return -ENOMEM;

        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_size >> ns->lba_shift);
        range->slba = cpu_to_le64(nvme_block_nr(ns, bio->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 = -ENOMEM;
        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;
        }

        iod = nvme_alloc_iod(psegs, bio->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_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);

        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 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;

        spin_lock_irq(&nvmeq->q_lock);
        if (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);
        }

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

static irqreturn_t 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 IRQ_NONE;

        writel(head, nvmeq->q_db + (1 << nvmeq->dev->db_stride));
        nvmeq->cq_head = head;
        nvmeq->cq_phase = phase;

        return IRQ_HANDLED;
}

static irqreturn_t nvme_irq(int irq, void *data)
{
        irqreturn_t result;
        struct nvme_queue *nvmeq = data;
        spin_lock(&nvmeq->q_lock);
        result = nvme_process_cq(nvmeq);
        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
 */
int nvme_submit_sync_cmd(struct nvme_queue *nvmeq, struct nvme_command *cmd,
                                                u32 *result, unsigned timeout)
{
        int cmdid;
        struct sync_cmd_info cmdinfo;

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

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

        set_current_state(TASK_KILLABLE);
        nvme_submit_cmd(nvmeq, cmd);
        schedule();

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

        if (result)
                *result = cmdinfo.result;

        return cmdinfo.status;
}

int nvme_submit_admin_cmd(struct nvme_dev *dev, struct nvme_command *cmd,
                                                                u32 *result)
{
        return nvme_submit_sync_cmd(dev->queues[0], cmd, result, 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_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;
                dev_warn(nvmeq->q_dmadev, "Cancelling I/O %d\n", cmdid);
                ctx = cancel_cmdid(nvmeq, cmdid, &fn);
                fn(nvmeq->dev, ctx, &cqe);
        }
}

static void nvme_free_queue_mem(struct nvme_queue *nvmeq)
{
        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);
        kfree(nvmeq);
}

static void nvme_free_queue(struct nvme_dev *dev, int qid)
{
        struct nvme_queue *nvmeq = dev->queues[qid];
        int vector = dev->entry[nvmeq->cq_vector].vector;

        spin_lock_irq(&nvmeq->q_lock);
        nvme_cancel_ios(nvmeq, false);
        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);

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

        /* Don't tell the adapter to delete the admin queue */
        if (qid) {
                adapter_delete_sq(dev, qid);
                adapter_delete_cq(dev, qid);
        }

        nvme_free_queue_mem(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 = DIV_ROUND_UP(depth, 8) + (depth *
                                                sizeof(struct nvme_cmd_info));
        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;

        nvmeq->q_dmadev = dmadev;
        nvmeq->dev = dev;
        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 << (dev->db_stride + 1)];
        nvmeq->q_depth = depth;
        nvmeq->cq_vector = vector;

        return nvmeq;

 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_DISABLED | IRQF_SHARED,
                                        name, nvmeq);
        return request_irq(dev->entry[nvmeq->cq_vector].vector, nvme_irq,
                                IRQF_DISABLED | IRQF_SHARED, name, nvmeq);
}

static struct nvme_queue *nvme_create_queue(struct nvme_dev *dev, int qid,
                                            int cq_size, int vector)
{
        int result;
        struct nvme_queue *nvmeq = nvme_alloc_queue(dev, qid, cq_size, vector);

        if (!nvmeq)
                return ERR_PTR(-ENOMEM);

        result = adapter_alloc_cq(dev, qid, nvmeq);
        if (result < 0)
                goto free_nvmeq;

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

        result = queue_request_irq(dev, nvmeq, "nvme");
        if (result < 0)
                goto release_sq;

        return nvmeq;

 release_sq:
        adapter_delete_sq(dev, qid);
 release_cq:
        adapter_delete_cq(dev, qid);
 free_nvmeq:
        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);
        kfree(nvmeq);
        return ERR_PTR(result);
}

static int nvme_configure_admin_queue(struct nvme_dev *dev)
{
        int result = 0;
        u32 aqa;
        u64 cap;
        unsigned long timeout;
        struct nvme_queue *nvmeq;

        dev->dbs = ((void __iomem *)dev->bar) + 4096;

        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(0, &dev->bar->cc);
        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);

        cap = readq(&dev->bar->cap);
        timeout = ((NVME_CAP_TIMEOUT(cap) + 1) * HZ / 2) + jiffies;
        dev->db_stride = NVME_CAP_STRIDE(cap);

        while (!result && !(readl(&dev->bar->csts) & NVME_CSTS_RDY)) {
                msleep(100);
                if (fatal_signal_pending(current))
                        result = -EINTR;
                if (time_after(jiffies, timeout)) {
                        dev_err(&dev->pci_dev->dev,
                                "Device not ready; aborting initialisation\n");
                        result = -ENODEV;
                }
        }

        if (result)
                goto free_q;

        result = queue_request_irq(dev, nvmeq, "nvme admin");
        if (result)
                goto free_q;

        dev->queues[0] = nvmeq;
        return result;

 free_q:
        nvme_free_queue_mem(nvmeq);
        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)
                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(int, 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_queue *nvmeq;
        struct nvme_user_io io;
        struct nvme_command c;
        unsigned length;
        int status;
        struct nvme_iod *iod;

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

        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);
        /* XXX: metadata */
        length = nvme_setup_prps(dev, &c.common, iod, length, GFP_KERNEL);

        nvmeq = get_nvmeq(dev);
        /*
         * Since nvme_submit_sync_cmd sleeps, we can't keep preemption
         * disabled.  We may be preempted at any point, and be rescheduled
         * to a different CPU.  That will cause cacheline bouncing, but no
         * additional races since q_lock already protects against other CPUs.
         */
        put_nvmeq(nvmeq);
        if (length != (io.nblocks + 1) << ns->lba_shift)
                status = -ENOMEM;
        else
                status = nvme_submit_sync_cmd(nvmeq, &c, NULL, NVME_IO_TIMEOUT);

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

        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);
        }

        if (length != cmd.data_len)
                status = -ENOMEM;
        else
                status = nvme_submit_admin_cmd(dev, &c, &cmd.result);

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

        if (!status && 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:
                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;
        }
}

static const struct block_device_operations nvme_fops = {
        .owner          = THIS_MODULE,
        .ioctl          = nvme_ioctl,
        .compat_ioctl   = nvme_ioctl,
};

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;

        while (!kthread_should_stop()) {
                set_current_state(TASK_INTERRUPTIBLE);
                spin_lock(&dev_list_lock);
                list_for_each_entry(dev, &dev_list, node) {
                        int i;
                        for (i = 0; i < dev->queue_count; i++) {
                                struct nvme_queue *nvmeq = dev->queues[i];
                                if (!nvmeq)
                                        continue;
                                spin_lock_irq(&nvmeq->q_lock);
                                if (nvme_process_cq(nvmeq))
                                        printk("process_cq did something\n");
                                nvme_cancel_ios(nvmeq, true);
                                nvme_resubmit_bios(nvmeq);
                                spin_unlock_irq(&nvmeq->q_lock);
                        }
                }
                spin_unlock(&dev_list_lock);
                schedule_timeout(round_jiffies_relative(HZ));
        }
        return 0;
}

static DEFINE_IDA(nvme_index_ida);

static int nvme_get_ns_idx(void)
{
        int index, error;

        do {
                if (!ida_pre_get(&nvme_index_ida, GFP_KERNEL))
                        return -1;

                spin_lock(&dev_list_lock);
                error = ida_get_new(&nvme_index_ida, &index);
                spin_unlock(&dev_list_lock);
        } while (error == -EAGAIN);

        if (error)
                index = -1;
        return index;
}

static void nvme_put_ns_idx(int index)
{
        spin_lock(&dev_list_lock);
        ida_remove(&nvme_index_ida, index);
        spin_unlock(&dev_list_lock);
}

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, int 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(NVME_MINORS);
        if (!disk)
                goto out_free_queue;
        ns->ns_id = nsid;
        ns->disk = disk;
        lbaf = id->flbas & 0xf;
        ns->lba_shift = id->lbaf[lbaf].ds;
        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->minors = NVME_MINORS;
        disk->first_minor = NVME_MINORS * nvme_get_ns_idx();
        disk->fops = &nvme_fops;
        disk->private_data = ns;
        disk->queue = ns->queue;
        disk->driverfs_dev = &dev->pci_dev->dev;
        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 void nvme_ns_free(struct nvme_ns *ns)
{
        int index = ns->disk->first_minor / NVME_MINORS;
        put_disk(ns->disk);
        nvme_put_ns_idx(index);
        blk_cleanup_queue(ns->queue);
        kfree(ns);
}

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 -EIO;
        return min(result & 0xffff, result >> 16) + 1;
}

static int nvme_setup_io_queues(struct nvme_dev *dev)
{
        int result, cpu, i, nr_io_queues, db_bar_size, q_depth;

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

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

        db_bar_size = 4096 + ((nr_io_queues + 1) << (dev->db_stride + 3));
        if (db_bar_size > 8192) {
                iounmap(dev->bar);
                dev->bar = ioremap(pci_resource_start(dev->pci_dev, 0),
                                                                db_bar_size);
                dev->dbs = ((void __iomem *)dev->bar) + 4096;
                dev->queues[0]->q_db = dev->dbs;
        }

        for (i = 0; i < nr_io_queues; i++)
                dev->entry[i].entry = i;
        for (;;) {
                result = pci_enable_msix(dev->pci_dev, dev->entry,
                                                                nr_io_queues);
                if (result == 0) {
                        break;
                } else if (result > 0) {
                        nr_io_queues = result;
                        continue;
                } else {
                        nr_io_queues = 1;
                        break;
                }
        }

        result = queue_request_irq(dev, dev->queues[0], "nvme admin");
        /* XXX: handle failure here */

        cpu = cpumask_first(cpu_online_mask);
        for (i = 0; i < nr_io_queues; i++) {
                irq_set_affinity_hint(dev->entry[i].vector, get_cpu_mask(cpu));
                cpu = cpumask_next(cpu, cpu_online_mask);
        }

        q_depth = min_t(int, NVME_CAP_MQES(readq(&dev->bar->cap)) + 1,
                                                                NVME_Q_DEPTH);
        for (i = 0; i < nr_io_queues; i++) {
                dev->queues[i + 1] = nvme_create_queue(dev, i + 1, q_depth, i);
                if (IS_ERR(dev->queues[i + 1]))
                        return PTR_ERR(dev->queues[i + 1]);
                dev->queue_count++;
        }

        for (; i < num_possible_cpus(); i++) {
                int target = i % rounddown_pow_of_two(dev->queue_count - 1);
                dev->queues[i + 1] = dev->queues[target + 1];
        }

        return 0;
}

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

        for (i = dev->queue_count - 1; i >= 0; i--)
                nvme_free_queue(dev, i);
}

/*
 * 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)
{
        int res, nn, i;
        struct nvme_ns *ns;
        struct nvme_id_ctrl *ctrl;
        struct nvme_id_ns *id_ns;
        void *mem;
        dma_addr_t dma_addr;

        res = nvme_setup_io_queues(dev);
        if (res)
                return res;

        mem = dma_alloc_coherent(&dev->pci_dev->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);
        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) {
                int shift = NVME_CAP_MPSMIN(readq(&dev->bar->cap)) + 12;
                dev->max_hw_sectors = 1 << (ctrl->mdts + shift - 9);
        }

        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_remove(struct nvme_dev *dev)
{
        struct nvme_ns *ns, *next;

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

        list_for_each_entry_safe(ns, next, &dev->namespaces, list) {
                list_del(&ns->list);
                del_gendisk(ns->disk);
                nvme_ns_free(ns);
        }

        nvme_free_queues(dev);

        return 0;
}

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_dev(struct kref *kref)
{
        struct nvme_dev *dev = container_of(kref, struct nvme_dev, kref);
        nvme_dev_remove(dev);
        pci_disable_msix(dev->pci_dev);
        iounmap(dev->bar);
        nvme_release_instance(dev);
        nvme_release_prp_pools(dev);
        pci_disable_device(dev->pci_dev);
        pci_release_regions(dev->pci_dev);
        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_probe(struct pci_dev *pdev, const struct pci_device_id *id)
{
        int bars, 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;

        if (pci_enable_device_mem(pdev))
                goto free;
        pci_set_master(pdev);
        bars = pci_select_bars(pdev, IORESOURCE_MEM);
        if (pci_request_selected_regions(pdev, bars, "nvme"))
                goto disable;

        INIT_LIST_HEAD(&dev->namespaces);
        dev->pci_dev = pdev;
        pci_set_drvdata(pdev, dev);
        dma_set_mask(&pdev->dev, DMA_BIT_MASK(64));
        dma_set_coherent_mask(&pdev->dev, DMA_BIT_MASK(64));
        result = nvme_set_instance(dev);
        if (result)
                goto disable;

        dev->entry[0].vector = pdev->irq;

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

        dev->bar = ioremap(pci_resource_start(pdev, 0), 8192);
        if (!dev->bar) {
                result = -ENOMEM;
                goto disable_msix;
        }

        result = nvme_configure_admin_queue(dev);
        if (result)
                goto unmap;
        dev->queue_count++;

        spin_lock(&dev_list_lock);
        list_add(&dev->node, &dev_list);
        spin_unlock(&dev_list_lock);

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

        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;

        kref_init(&dev->kref);
        return 0;

 remove:
        nvme_dev_remove(dev);
 delete:
        spin_lock(&dev_list_lock);
        list_del(&dev->node);
        spin_unlock(&dev_list_lock);

        nvme_free_queues(dev);
 unmap:
        iounmap(dev->bar);
 disable_msix:
        pci_disable_msix(pdev);
        nvme_release_instance(dev);
        nvme_release_prp_pools(dev);
 disable:
        pci_disable_device(pdev);
        pci_release_regions(pdev);
 free:
        kfree(dev->queues);
        kfree(dev->entry);
        kfree(dev);
        return result;
}

static void nvme_remove(struct pci_dev *pdev)
{
        struct nvme_dev *dev = pci_get_drvdata(pdev);
        misc_deregister(&dev->miscdev);
        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
#define nvme_suspend NULL
#define nvme_resume NULL

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 DEFINE_PCI_DEVICE_TABLE(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,
        .suspend        = nvme_suspend,
        .resume         = nvme_resume,
        .err_handler    = &nvme_err_handler,
};

static int __init nvme_init(void)
{
        int result;

        nvme_thread = kthread_run(nvme_kthread, NULL, "nvme");
        if (IS_ERR(nvme_thread))
                return PTR_ERR(nvme_thread);

        result = register_blkdev(nvme_major, "nvme");
        if (result < 0)
                goto kill_kthread;
        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_kthread:
        kthread_stop(nvme_thread);
        return result;
}

static void __exit nvme_exit(void)
{
        pci_unregister_driver(&nvme_driver);
        unregister_blkdev(nvme_major, "nvme");
        kthread_stop(nvme_thread);
}

MODULE_AUTHOR("Matthew Wilcox <willy@linux.intel.com>");
MODULE_LICENSE("GPL");
MODULE_VERSION("0.8");
module_init(nvme_init);
module_exit(nvme_exit);