/*-
 * SPDX-License-Identifier: BSD-2-Clause
 *
 * Copyright (c) 2003, 2008 Silicon Graphics International Corp.
 * Copyright (c) 2012 The FreeBSD Foundation
 * Copyright (c) 2014-2017 Alexander Motin <mav@FreeBSD.org>
 * All rights reserved.
 *
 * Portions of this software were developed by Edward Tomasz Napierala
 * under sponsorship from the FreeBSD Foundation.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions, and the following disclaimer,
 *    without modification.
 * 2. Redistributions in binary form must reproduce at minimum a disclaimer
 *    substantially similar to the "NO WARRANTY" disclaimer below
 *    ("Disclaimer") and any redistribution must be conditioned upon
 *    including a substantially similar Disclaimer requirement for further
 *    binary redistribution.
 *
 * NO WARRANTY
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTIBILITY AND FITNESS FOR
 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
 * HOLDERS OR CONTRIBUTORS BE LIABLE FOR SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
 * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING
 * IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGES.
 *
 * $Id: //depot/users/kenm/FreeBSD-test2/sys/cam/ctl/ctl_backend_ramdisk.c#3 $
 */
/*
 * CAM Target Layer black hole and RAM disk backend.
 *
 * Author: Ken Merry <ken@FreeBSD.org>
 */

#include <sys/param.h>
#include <sys/systm.h>
#include <sys/kernel.h>
#include <sys/condvar.h>
#include <sys/types.h>
#include <sys/limits.h>
#include <sys/lock.h>
#include <sys/mutex.h>
#include <sys/malloc.h>
#include <sys/sx.h>
#include <sys/taskqueue.h>
#include <sys/time.h>
#include <sys/queue.h>
#include <sys/conf.h>
#include <sys/ioccom.h>
#include <sys/module.h>
#include <sys/sysctl.h>
#include <sys/nv.h>
#include <sys/dnv.h>

#include <cam/scsi/scsi_all.h>
#include <cam/scsi/scsi_da.h>
#include <cam/ctl/ctl_io.h>
#include <cam/ctl/ctl.h>
#include <cam/ctl/ctl_util.h>
#include <cam/ctl/ctl_backend.h>
#include <cam/ctl/ctl_debug.h>
#include <cam/ctl/ctl_ioctl.h>
#include <cam/ctl/ctl_ha.h>
#include <cam/ctl/ctl_private.h>
#include <cam/ctl/ctl_error.h>

#define PRIV(io)        \
    ((struct ctl_ptr_len_flags *)&(io)->io_hdr.ctl_private[CTL_PRIV_BACKEND])
#define ARGS(io)        \
    ((struct ctl_lba_len_flags *)&(io)->io_hdr.ctl_private[CTL_PRIV_LBA_LEN])

#define PPP     (PAGE_SIZE / sizeof(uint8_t **))
#ifdef __LP64__
#define PPPS    (PAGE_SHIFT - 3)
#else
#define PPPS    (PAGE_SHIFT - 2)
#endif
#define SGPP    (PAGE_SIZE / sizeof(struct ctl_sg_entry))

#define P_UNMAPPED      NULL                    /* Page is unmapped. */
#define P_ANCHORED      ((void *)(uintptr_t)1)  /* Page is anchored. */

typedef enum {
        GP_READ,        /* Return data page or zero page. */
        GP_WRITE,       /* Return data page, try allocate if none. */
        GP_ANCHOR,      /* Return data page, try anchor if none. */
        GP_OTHER,       /* Return what present, do not allocate/anchor. */
} getpage_op_t;

typedef enum {
        CTL_BE_RAMDISK_LUN_UNCONFIGURED = 0x01,
        CTL_BE_RAMDISK_LUN_WAITING      = 0x04
} ctl_be_ramdisk_lun_flags;

struct ctl_be_ramdisk_lun {
        struct ctl_be_lun       cbe_lun;        /* Must be first element. */
        struct ctl_lun_create_params params;
        int                     indir;
        uint8_t                 **pages;
        uint8_t                 *zero_page;
        struct sx               page_lock;
        u_int                   pblocksize;
        u_int                   pblockmul;
        uint64_t                size_bytes;
        uint64_t                size_blocks;
        uint64_t                cap_bytes;
        uint64_t                cap_used;
        struct ctl_be_ramdisk_softc *softc;
        ctl_be_ramdisk_lun_flags flags;
        SLIST_ENTRY(ctl_be_ramdisk_lun) links;
        struct taskqueue        *io_taskqueue;
        struct task             io_task;
        STAILQ_HEAD(, ctl_io_hdr) cont_queue;
        struct mtx_padalign     queue_lock;
};

struct ctl_be_ramdisk_softc {
        struct sx modify_lock;
        struct mtx lock;
        int num_luns;
        SLIST_HEAD(, ctl_be_ramdisk_lun) lun_list;
};

static struct ctl_be_ramdisk_softc rd_softc;

static int ctl_backend_ramdisk_init(void);
static int ctl_backend_ramdisk_shutdown(void);
static int ctl_backend_ramdisk_move_done(union ctl_io *io, bool samethr);
static void ctl_backend_ramdisk_compare(union ctl_io *io);
static void ctl_backend_ramdisk_rw(union ctl_io *io);
static int ctl_backend_ramdisk_submit(union ctl_io *io);
static void ctl_backend_ramdisk_worker(void *context, int pending);
static int ctl_backend_ramdisk_config_read(union ctl_io *io);
static int ctl_backend_ramdisk_config_write(union ctl_io *io);
static uint64_t ctl_backend_ramdisk_lun_attr(struct ctl_be_lun *cbe_lun, const char *attrname);
static int ctl_backend_ramdisk_ioctl(struct cdev *dev, u_long cmd,
                                     caddr_t addr, int flag, struct thread *td);
static int ctl_backend_ramdisk_rm(struct ctl_be_ramdisk_softc *softc,
                                  struct ctl_lun_req *req);
static int ctl_backend_ramdisk_create(struct ctl_be_ramdisk_softc *softc,
                                      struct ctl_lun_req *req);
static int ctl_backend_ramdisk_modify(struct ctl_be_ramdisk_softc *softc,
                                  struct ctl_lun_req *req);
static void ctl_backend_ramdisk_lun_shutdown(struct ctl_be_lun *cbe_lun);

static struct ctl_backend_driver ctl_be_ramdisk_driver = 
{
        .name = "ramdisk",
        .flags = CTL_BE_FLAG_HAS_CONFIG,
        .init = ctl_backend_ramdisk_init,
        .shutdown = ctl_backend_ramdisk_shutdown,
        .data_submit = ctl_backend_ramdisk_submit,
        .config_read = ctl_backend_ramdisk_config_read,
        .config_write = ctl_backend_ramdisk_config_write,
        .ioctl = ctl_backend_ramdisk_ioctl,
        .lun_attr = ctl_backend_ramdisk_lun_attr,
};

MALLOC_DEFINE(M_RAMDISK, "ctlramdisk", "Memory used for CTL RAMdisk");
CTL_BACKEND_DECLARE(cbr, ctl_be_ramdisk_driver);

static int
ctl_backend_ramdisk_init(void)
{
        struct ctl_be_ramdisk_softc *softc = &rd_softc;

        memset(softc, 0, sizeof(*softc));
        sx_init(&softc->modify_lock, "ctlrammod");
        mtx_init(&softc->lock, "ctlram", NULL, MTX_DEF);
        SLIST_INIT(&softc->lun_list);
        return (0);
}

static int
ctl_backend_ramdisk_shutdown(void)
{
        struct ctl_be_ramdisk_softc *softc = &rd_softc;
        struct ctl_be_ramdisk_lun *lun;

        mtx_lock(&softc->lock);
        while ((lun = SLIST_FIRST(&softc->lun_list)) != NULL) {
                SLIST_REMOVE_HEAD(&softc->lun_list, links);
                softc->num_luns--;
                /*
                 * Drop our lock here.  Since ctl_remove_lun() can call
                 * back into us, this could potentially lead to a recursive
                 * lock of the same mutex, which would cause a hang.
                 */
                mtx_unlock(&softc->lock);
                ctl_remove_lun(&lun->cbe_lun);
                mtx_lock(&softc->lock);
        }
        mtx_unlock(&softc->lock);
        mtx_destroy(&softc->lock);
        sx_destroy(&softc->modify_lock);
        return (0);
}

static uint8_t *
ctl_backend_ramdisk_getpage(struct ctl_be_ramdisk_lun *be_lun, off_t pn,
    getpage_op_t op)
{
        uint8_t **p, ***pp;
        off_t i;
        int s;

        if (be_lun->cap_bytes == 0) {
                switch (op) {
                case GP_READ:
                        return (be_lun->zero_page);
                case GP_WRITE:
                        return ((uint8_t *)be_lun->pages);
                case GP_ANCHOR:
                        return (P_ANCHORED);
                default:
                        return (P_UNMAPPED);
                }
        }
        if (op == GP_WRITE || op == GP_ANCHOR) {
                sx_xlock(&be_lun->page_lock);
                pp = &be_lun->pages;
                for (s = (be_lun->indir - 1) * PPPS; s >= 0; s -= PPPS) {
                        if (*pp == NULL) {
                                *pp = malloc(PAGE_SIZE, M_RAMDISK,
                                    M_WAITOK|M_ZERO);
                        }
                        i = pn >> s;
                        pp = (uint8_t ***)&(*pp)[i];
                        pn -= i << s;
                }
                if (*pp == P_UNMAPPED && be_lun->cap_used < be_lun->cap_bytes) {
                        if (op == GP_WRITE) {
                                *pp = malloc(be_lun->pblocksize, M_RAMDISK,
                                    M_WAITOK|M_ZERO);
                        } else
                                *pp = P_ANCHORED;
                        be_lun->cap_used += be_lun->pblocksize;
                } else if (*pp == P_ANCHORED && op == GP_WRITE) {
                        *pp = malloc(be_lun->pblocksize, M_RAMDISK,
                            M_WAITOK|M_ZERO);
                }
                sx_xunlock(&be_lun->page_lock);
                return ((uint8_t *)*pp);
        } else {
                sx_slock(&be_lun->page_lock);
                p = be_lun->pages;
                for (s = (be_lun->indir - 1) * PPPS; s >= 0; s -= PPPS) {
                        if (p == NULL)
                                break;
                        i = pn >> s;
                        p = (uint8_t **)p[i];
                        pn -= i << s;
                }
                sx_sunlock(&be_lun->page_lock);
                if ((p == P_UNMAPPED || p == P_ANCHORED) && op == GP_READ)
                        return (be_lun->zero_page);
                return ((uint8_t *)p);
        }
};

static void
ctl_backend_ramdisk_unmappage(struct ctl_be_ramdisk_lun *be_lun, off_t pn)
{
        uint8_t ***pp;
        off_t i;
        int s;

        if (be_lun->cap_bytes == 0)
                return;
        sx_xlock(&be_lun->page_lock);
        pp = &be_lun->pages;
        for (s = (be_lun->indir - 1) * PPPS; s >= 0; s -= PPPS) {
                if (*pp == NULL)
                        goto noindir;
                i = pn >> s;
                pp = (uint8_t ***)&(*pp)[i];
                pn -= i << s;
        }
        if (*pp == P_ANCHORED) {
                be_lun->cap_used -= be_lun->pblocksize;
                *pp = P_UNMAPPED;
        } else if (*pp != P_UNMAPPED) {
                free(*pp, M_RAMDISK);
                be_lun->cap_used -= be_lun->pblocksize;
                *pp = P_UNMAPPED;
        }
noindir:
        sx_xunlock(&be_lun->page_lock);
};

static void
ctl_backend_ramdisk_anchorpage(struct ctl_be_ramdisk_lun *be_lun, off_t pn)
{
        uint8_t ***pp;
        off_t i;
        int s;

        if (be_lun->cap_bytes == 0)
                return;
        sx_xlock(&be_lun->page_lock);
        pp = &be_lun->pages;
        for (s = (be_lun->indir - 1) * PPPS; s >= 0; s -= PPPS) {
                if (*pp == NULL)
                        goto noindir;
                i = pn >> s;
                pp = (uint8_t ***)&(*pp)[i];
                pn -= i << s;
        }
        if (*pp == P_UNMAPPED && be_lun->cap_used < be_lun->cap_bytes) {
                be_lun->cap_used += be_lun->pblocksize;
                *pp = P_ANCHORED;
        } else if (*pp != P_ANCHORED) {
                free(*pp, M_RAMDISK);
                *pp = P_ANCHORED;
        }
noindir:
        sx_xunlock(&be_lun->page_lock);
};

static void
ctl_backend_ramdisk_freeallpages(uint8_t **p, int indir)
{
        int i;

        if (p == NULL)
                return;
        if (indir == 0) {
                free(p, M_RAMDISK);
                return;
        }
        for (i = 0; i < PPP; i++) {
                if (p[i] == NULL)
                        continue;
                ctl_backend_ramdisk_freeallpages((uint8_t **)p[i], indir - 1);
        }
        free(p, M_RAMDISK);
};

static size_t
cmp(uint8_t *a, uint8_t *b, size_t size)
{
        size_t i;

        for (i = 0; i < size; i++) {
                if (a[i] != b[i])
                        break;
        }
        return (i);
}

static int
ctl_backend_ramdisk_cmp(union ctl_io *io)
{
        struct ctl_be_lun *cbe_lun = CTL_BACKEND_LUN(io);
        struct ctl_be_ramdisk_lun *be_lun = (struct ctl_be_ramdisk_lun *)cbe_lun;
        uint8_t *page;
        uint64_t lba;
        u_int lbaoff, lbas, res, off;

        lbas = ctl_kern_data_len(io) / cbe_lun->blocksize;
        lba = ARGS(io)->lba + PRIV(io)->len - lbas;
        off = 0;
        for (; lbas > 0; lbas--, lba++) {
                page = ctl_backend_ramdisk_getpage(be_lun,
                    lba >> cbe_lun->pblockexp, GP_READ);
                lbaoff = lba & ~(UINT_MAX << cbe_lun->pblockexp);
                page += lbaoff * cbe_lun->blocksize;
                res = cmp(ctl_kern_data_ptr(io) + off, page,
                    cbe_lun->blocksize);
                off += res;
                if (res < cbe_lun->blocksize)
                        break;
        }
        free(io->scsiio.kern_data_ptr, M_RAMDISK);
        if (lbas > 0) {
                off += ctl_kern_rel_offset(io) - ctl_kern_data_len(io);
                ctl_io_set_compare_failure(io, off);
                return (1);
        }
        return (0);
}

static int
ctl_backend_ramdisk_move_done(union ctl_io *io, bool samethr)
{
        struct ctl_be_ramdisk_lun *be_lun =
            (struct ctl_be_ramdisk_lun *)CTL_BACKEND_LUN(io);

        CTL_DEBUG_PRINT(("ctl_backend_ramdisk_move_done\n"));
        if (ctl_kern_sg_entries(io) > 0)
                free(ctl_kern_data_ptr(io), M_RAMDISK);
        ctl_add_kern_rel_offset(io, ctl_kern_data_len(io));
        if ((io->io_hdr.flags & CTL_FLAG_ABORT) == 0 &&
            (io->io_hdr.status & CTL_STATUS_MASK) == CTL_STATUS_NONE) {
                if (ARGS(io)->flags & CTL_LLF_COMPARE) {
                        /* We have data block ready for comparison. */
                        if (ctl_backend_ramdisk_cmp(io))
                                goto done;
                }
                if (ARGS(io)->len > PRIV(io)->len) {
                        mtx_lock(&be_lun->queue_lock);
                        STAILQ_INSERT_TAIL(&be_lun->cont_queue,
                            &io->io_hdr, links);
                        mtx_unlock(&be_lun->queue_lock);
                        taskqueue_enqueue(be_lun->io_taskqueue,
                            &be_lun->io_task);
                        return (0);
                }
                ctl_io_set_success(io);
        }
done:
        ctl_data_submit_done(io);
        return(0);
}

static void
ctl_backend_ramdisk_compare(union ctl_io *io)
{
        struct ctl_be_lun *cbe_lun = CTL_BACKEND_LUN(io);
        u_int lbas, len;

        lbas = ARGS(io)->len - PRIV(io)->len;
        lbas = MIN(lbas, 131072 / cbe_lun->blocksize);
        len = lbas * cbe_lun->blocksize;

        ctl_set_be_move_done(io, ctl_backend_ramdisk_move_done);
        ctl_set_kern_data_ptr(io, malloc(len, M_RAMDISK, M_WAITOK));
        ctl_set_kern_data_len(io, len);
        ctl_set_kern_sg_entries(io, 0);
        io->io_hdr.flags |= CTL_FLAG_ALLOCATED;
        PRIV(io)->len += lbas;
        ctl_datamove(io);
}

static void
ctl_backend_ramdisk_rw(union ctl_io *io)
{
        struct ctl_be_lun *cbe_lun = CTL_BACKEND_LUN(io);
        struct ctl_be_ramdisk_lun *be_lun = (struct ctl_be_ramdisk_lun *)cbe_lun;
        struct ctl_sg_entry *sg_entries;
        uint8_t *page;
        uint64_t lba;
        u_int i, len, lbaoff, lbas, sgs, off;
        getpage_op_t op;

        lba = ARGS(io)->lba + PRIV(io)->len;
        lbaoff = lba & ~(UINT_MAX << cbe_lun->pblockexp);
        lbas = ARGS(io)->len - PRIV(io)->len;
        lbas = MIN(lbas, (SGPP << cbe_lun->pblockexp) - lbaoff);
        sgs = (lbas + lbaoff + be_lun->pblockmul - 1) >> cbe_lun->pblockexp;
        off = lbaoff * cbe_lun->blocksize;
        op = (ARGS(io)->flags & CTL_LLF_WRITE) ? GP_WRITE : GP_READ;
        if (sgs > 1) {
                sg_entries = malloc(sizeof(struct ctl_sg_entry) * sgs,
                    M_RAMDISK, M_WAITOK);
                ctl_set_kern_data_ptr(io, sg_entries);
                len = lbas * cbe_lun->blocksize;
                for (i = 0; i < sgs; i++) {
                        page = ctl_backend_ramdisk_getpage(be_lun,
                            (lba >> cbe_lun->pblockexp) + i, op);
                        if (page == P_UNMAPPED || page == P_ANCHORED) {
                                free(sg_entries, M_RAMDISK);
nospc:
                                ctl_io_set_space_alloc_fail(io);
                                ctl_data_submit_done(io);
                                return;
                        }
                        sg_entries[i].addr = page + off;
                        sg_entries[i].len = MIN(len, be_lun->pblocksize - off);
                        len -= sg_entries[i].len;
                        off = 0;
                }
        } else {
                page = ctl_backend_ramdisk_getpage(be_lun,
                    lba >> cbe_lun->pblockexp, op);
                if (page == P_UNMAPPED || page == P_ANCHORED)
                        goto nospc;
                sgs = 0;
                ctl_set_kern_data_ptr(io, page + off);
        }

        ctl_set_be_move_done(io, ctl_backend_ramdisk_move_done);
        ctl_set_kern_data_len(io, lbas * cbe_lun->blocksize);
        ctl_set_kern_sg_entries(io, sgs);
        io->io_hdr.flags |= CTL_FLAG_ALLOCATED;
        PRIV(io)->len += lbas;
        if ((ARGS(io)->flags & CTL_LLF_READ) &&
            ARGS(io)->len <= PRIV(io)->len) {
                ctl_io_set_success(io);
                if (cbe_lun->serseq >= CTL_LUN_SERSEQ_SOFT)
                        ctl_serseq_done(io);
        }
        ctl_datamove(io);
}

static int
ctl_backend_ramdisk_submit(union ctl_io *io)
{
        struct ctl_lba_len_flags *lbalen = ARGS(io);

        if (lbalen->flags & CTL_LLF_VERIFY) {
                ctl_io_set_success(io);
                ctl_data_submit_done(io);
                return (CTL_RETVAL_COMPLETE);
        }
        PRIV(io)->len = 0;
        if (lbalen->flags & CTL_LLF_COMPARE)
                ctl_backend_ramdisk_compare(io);
        else
                ctl_backend_ramdisk_rw(io);
        return (CTL_RETVAL_COMPLETE);
}

static void
ctl_backend_ramdisk_worker(void *context, int pending)
{
        struct ctl_be_ramdisk_lun *be_lun;
        union ctl_io *io;

        be_lun = (struct ctl_be_ramdisk_lun *)context;
        mtx_lock(&be_lun->queue_lock);
        for (;;) {
                io = (union ctl_io *)STAILQ_FIRST(&be_lun->cont_queue);
                if (io != NULL) {
                        STAILQ_REMOVE_HEAD(&be_lun->cont_queue, links);
                        mtx_unlock(&be_lun->queue_lock);
                        if (ARGS(io)->flags & CTL_LLF_COMPARE)
                                ctl_backend_ramdisk_compare(io);
                        else
                                ctl_backend_ramdisk_rw(io);
                        mtx_lock(&be_lun->queue_lock);
                        continue;
                }

                /*
                 * If we get here, there is no work left in the queues, so
                 * just break out and let the task queue go to sleep.
                 */
                break;
        }
        mtx_unlock(&be_lun->queue_lock);
}

static int
ctl_backend_ramdisk_gls(union ctl_io *io)
{
        struct ctl_be_lun *cbe_lun = CTL_BACKEND_LUN(io);
        struct ctl_be_ramdisk_lun *be_lun = (struct ctl_be_ramdisk_lun *)cbe_lun;
        struct scsi_get_lba_status_data *data;
        uint8_t *page;
        u_int lbaoff;

        data = (struct scsi_get_lba_status_data *)io->scsiio.kern_data_ptr;
        scsi_u64to8b(ARGS(io)->lba, data->descr[0].addr);
        lbaoff = ARGS(io)->lba & ~(UINT_MAX << cbe_lun->pblockexp);
        scsi_ulto4b(be_lun->pblockmul - lbaoff, data->descr[0].length);
        page = ctl_backend_ramdisk_getpage(be_lun,
            ARGS(io)->lba >> cbe_lun->pblockexp, GP_OTHER);
        if (page == P_UNMAPPED)
                data->descr[0].status = 1;
        else if (page == P_ANCHORED)
                data->descr[0].status = 2;
        else
                data->descr[0].status = 0;
        ctl_config_read_done(io);
        return (CTL_RETVAL_COMPLETE);
}

static int
ctl_backend_ramdisk_scsi_config_read(union ctl_io *io)
{
        int retval = 0;

        switch (io->scsiio.cdb[0]) {
        case SERVICE_ACTION_IN:
                if (io->scsiio.cdb[1] == SGLS_SERVICE_ACTION) {
                        retval = ctl_backend_ramdisk_gls(io);
                        break;
                }
                ctl_set_invalid_field(&io->scsiio,
                                      /*sks_valid*/ 1,
                                      /*command*/ 1,
                                      /*field*/ 1,
                                      /*bit_valid*/ 1,
                                      /*bit*/ 4);
                ctl_config_read_done(io);
                retval = CTL_RETVAL_COMPLETE;
                break;
        default:
                ctl_set_invalid_opcode(&io->scsiio);
                ctl_config_read_done(io);
                retval = CTL_RETVAL_COMPLETE;
                break;
        }
        return (retval);
}

static int
ramdisk_namespace_data(union ctl_io *io)
{
        struct ctl_be_lun *cbe_lun = CTL_BACKEND_LUN(io);
        struct ctl_be_ramdisk_lun *be_lun = (struct ctl_be_ramdisk_lun *)cbe_lun;
        struct nvme_namespace_data *nsdata;

        if (io->nvmeio.kern_data_len != sizeof(struct nvme_namespace_data) ||
            io->nvmeio.kern_sg_entries != 0)
                return (CTL_RETVAL_ERROR);

        nsdata = (struct nvme_namespace_data *)io->nvmeio.kern_data_ptr;
        memset(nsdata, 0, sizeof(*nsdata));
        nsdata->nsze = htole64(be_lun->size_blocks);
        nsdata->ncap = htole64(be_lun->cap_bytes / cbe_lun->blocksize);
        nsdata->nuse = htole64(be_lun->cap_used / cbe_lun->blocksize);
        nsdata->nsfeat = NVMEM(NVME_NS_DATA_NSFEAT_THIN_PROV) |
            NVMEM(NVME_NS_DATA_NSFEAT_DEALLOC);
        nsdata->nlbaf = 1 - 1;
        nsdata->dlfeat = NVMEM(NVME_NS_DATA_DLFEAT_DWZ) |
            NVMEF(NVME_NS_DATA_DLFEAT_READ, NVME_NS_DATA_DLFEAT_READ_00);
        nsdata->flbas = NVMEF(NVME_NS_DATA_FLBAS_FORMAT, 0);
        nsdata->lbaf[0] = NVMEF(NVME_NS_DATA_LBAF_LBADS,
            ffs(cbe_lun->blocksize) - 1);

        ctl_lun_nsdata_ids(cbe_lun, nsdata);
        ctl_config_read_done(io);
        return (CTL_RETVAL_COMPLETE);
}

static int
ramdisk_nvme_ids(union ctl_io *io)
{
        struct ctl_be_lun *cbe_lun = CTL_BACKEND_LUN(io);

        if (io->nvmeio.kern_data_len != 4096 || io->nvmeio.kern_sg_entries != 0)
                return (CTL_RETVAL_ERROR);

        ctl_lun_nvme_ids(cbe_lun, io->nvmeio.kern_data_ptr);
        ctl_config_read_done(io);
        return (CTL_RETVAL_COMPLETE);
}

static int
ctl_backend_ramdisk_nvme_config_read(union ctl_io *io)
{
        switch (io->nvmeio.cmd.opc) {
        case NVME_OPC_IDENTIFY:
        {
                uint8_t cns;

                cns = le32toh(io->nvmeio.cmd.cdw10) & 0xff;
                switch (cns) {
                case 0:
                        return (ramdisk_namespace_data(io));
                case 3:
                        return (ramdisk_nvme_ids(io));
                default:
                        ctl_nvme_set_invalid_field(&io->nvmeio);
                        ctl_config_read_done(io);
                        return (CTL_RETVAL_COMPLETE);
                }
        }
        default:
                ctl_nvme_set_invalid_opcode(&io->nvmeio);
                ctl_config_read_done(io);
                return (CTL_RETVAL_COMPLETE);
        }
}

static int
ctl_backend_ramdisk_config_read(union ctl_io *io)
{
        switch (io->io_hdr.io_type) {
        case CTL_IO_SCSI:
                return (ctl_backend_ramdisk_scsi_config_read(io));
        case CTL_IO_NVME_ADMIN:
                return (ctl_backend_ramdisk_nvme_config_read(io));
        default:
                __assert_unreachable();
        }
}

static void
ctl_backend_ramdisk_delete(struct ctl_be_lun *cbe_lun, off_t lba, off_t len,
    int anchor)
{
        struct ctl_be_ramdisk_lun *be_lun = (struct ctl_be_ramdisk_lun *)cbe_lun;
        uint8_t *page;
        uint64_t p, lp;
        u_int lbaoff;
        getpage_op_t op = anchor ? GP_ANCHOR : GP_OTHER;

        /* Partially zero first partial page. */
        p = lba >> cbe_lun->pblockexp;
        lbaoff = lba & ~(UINT_MAX << cbe_lun->pblockexp);
        if (lbaoff != 0) {
                page = ctl_backend_ramdisk_getpage(be_lun, p, op);
                if (page != P_UNMAPPED && page != P_ANCHORED) {
                        memset(page + lbaoff * cbe_lun->blocksize, 0,
                            min(len, be_lun->pblockmul - lbaoff) *
                            cbe_lun->blocksize);
                }
                p++;
        }

        /* Partially zero last partial page. */
        lp = (lba + len) >> cbe_lun->pblockexp;
        lbaoff = (lba + len) & ~(UINT_MAX << cbe_lun->pblockexp);
        if (p <= lp && lbaoff != 0) {
                page = ctl_backend_ramdisk_getpage(be_lun, lp, op);
                if (page != P_UNMAPPED && page != P_ANCHORED)
                        memset(page, 0, lbaoff * cbe_lun->blocksize);
        }

        /* Delete remaining full pages. */
        if (anchor) {
                for (; p < lp; p++)
                        ctl_backend_ramdisk_anchorpage(be_lun, p);
        } else {
                for (; p < lp; p++)
                        ctl_backend_ramdisk_unmappage(be_lun, p);
        }
}

static void
ctl_backend_ramdisk_ws(union ctl_io *io)
{
        struct ctl_be_lun *cbe_lun = CTL_BACKEND_LUN(io);
        struct ctl_be_ramdisk_lun *be_lun = (struct ctl_be_ramdisk_lun *)cbe_lun;
        struct ctl_lba_len_flags *lbalen = ARGS(io);
        uint8_t *page;
        uint64_t lba;
        u_int lbaoff, lbas;

        CTL_IO_ASSERT(io, SCSI);

        if (lbalen->flags & ~(SWS_LBDATA | SWS_UNMAP | SWS_ANCHOR | SWS_NDOB)) {
                ctl_set_invalid_field(&io->scsiio,
                                      /*sks_valid*/ 1,
                                      /*command*/ 1,
                                      /*field*/ 1,
                                      /*bit_valid*/ 0,
                                      /*bit*/ 0);
                ctl_config_write_done(io);
                return;
        }
        if (lbalen->flags & SWS_UNMAP) {
                ctl_backend_ramdisk_delete(cbe_lun, lbalen->lba, lbalen->len,
                    (lbalen->flags & SWS_ANCHOR) != 0);
                ctl_set_success(&io->scsiio);
                ctl_config_write_done(io);
                return;
        }

        for (lba = lbalen->lba, lbas = lbalen->len; lbas > 0; lba++, lbas--) {
                page = ctl_backend_ramdisk_getpage(be_lun,
                    lba >> cbe_lun->pblockexp, GP_WRITE);
                if (page == P_UNMAPPED || page == P_ANCHORED) {
                        ctl_set_space_alloc_fail(&io->scsiio);
                        ctl_data_submit_done(io);
                        return;
                }
                lbaoff = lba & ~(UINT_MAX << cbe_lun->pblockexp);
                page += lbaoff * cbe_lun->blocksize;
                if (lbalen->flags & SWS_NDOB) {
                        memset(page, 0, cbe_lun->blocksize);
                } else {
                        memcpy(page, io->scsiio.kern_data_ptr,
                            cbe_lun->blocksize);
                }
                if (lbalen->flags & SWS_LBDATA)
                        scsi_ulto4b(lba, page);
        }
        ctl_set_success(&io->scsiio);
        ctl_config_write_done(io);
}

static void
ctl_backend_ramdisk_unmap(union ctl_io *io)
{
        struct ctl_be_lun *cbe_lun = CTL_BACKEND_LUN(io);
        struct ctl_ptr_len_flags *ptrlen = (struct ctl_ptr_len_flags *)ARGS(io);
        struct scsi_unmap_desc *buf, *end;

        CTL_IO_ASSERT(io, SCSI);

        if ((ptrlen->flags & ~SU_ANCHOR) != 0) {
                ctl_set_invalid_field(&io->scsiio,
                                      /*sks_valid*/ 0,
                                      /*command*/ 0,
                                      /*field*/ 0,
                                      /*bit_valid*/ 0,
                                      /*bit*/ 0);
                ctl_config_write_done(io);
                return;
        }

        buf = (struct scsi_unmap_desc *)ptrlen->ptr;
        end = buf + ptrlen->len / sizeof(*buf);
        for (; buf < end; buf++) {
                ctl_backend_ramdisk_delete(cbe_lun,
                    scsi_8btou64(buf->lba), scsi_4btoul(buf->length),
                    (ptrlen->flags & SU_ANCHOR) != 0);
        }

        ctl_set_success(&io->scsiio);
        ctl_config_write_done(io);
}

static int
ctl_backend_ramdisk_scsi_config_write(union ctl_io *io)
{
        struct ctl_be_lun *cbe_lun = CTL_BACKEND_LUN(io);
        int retval = 0;

        switch (io->scsiio.cdb[0]) {
        case SYNCHRONIZE_CACHE:
        case SYNCHRONIZE_CACHE_16:
                /* We have no cache to flush. */
                ctl_set_success(&io->scsiio);
                ctl_config_write_done(io);
                break;
        case START_STOP_UNIT: {
                struct scsi_start_stop_unit *cdb;

                cdb = (struct scsi_start_stop_unit *)io->scsiio.cdb;
                if ((cdb->how & SSS_PC_MASK) != 0) {
                        ctl_set_success(&io->scsiio);
                        ctl_config_write_done(io);
                        break;
                }
                if (cdb->how & SSS_START) {
                        if (cdb->how & SSS_LOEJ)
                                ctl_lun_has_media(cbe_lun);
                        ctl_start_lun(cbe_lun);
                } else {
                        ctl_stop_lun(cbe_lun);
                        if (cdb->how & SSS_LOEJ)
                                ctl_lun_ejected(cbe_lun);
                }
                ctl_set_success(&io->scsiio);
                ctl_config_write_done(io);
                break;
        }
        case PREVENT_ALLOW:
                ctl_set_success(&io->scsiio);
                ctl_config_write_done(io);
                break;
        case WRITE_SAME_10:
        case WRITE_SAME_16:
                ctl_backend_ramdisk_ws(io);
                break;
        case UNMAP:
                ctl_backend_ramdisk_unmap(io);
                break;
        default:
                ctl_set_invalid_opcode(&io->scsiio);
                ctl_config_write_done(io);
                retval = CTL_RETVAL_COMPLETE;
                break;
        }

        return (retval);
}

static void
ctl_backend_ramdisk_wu(union ctl_io *io)
{
        struct ctl_be_lun *cbe_lun = CTL_BACKEND_LUN(io);
        struct ctl_lba_len_flags *lbalen = ARGS(io);

        CTL_IO_ASSERT(io, NVME);

        /*
         * XXX: Not quite right as reads will return zeroes rather
         * than failing.
         */
        ctl_backend_ramdisk_delete(cbe_lun, lbalen->lba, lbalen->len, 1);
        ctl_nvme_set_success(&io->nvmeio);
        ctl_config_write_done(io);
}

static void
ctl_backend_ramdisk_wz(union ctl_io *io)
{
        struct ctl_be_lun *cbe_lun = CTL_BACKEND_LUN(io);
        struct ctl_be_ramdisk_lun *be_lun = (struct ctl_be_ramdisk_lun *)cbe_lun;
        struct ctl_lba_len_flags *lbalen = ARGS(io);
        uint8_t *page;
        uint64_t lba;
        u_int lbaoff, lbas;

        CTL_IO_ASSERT(io, NVME);

        if ((le32toh(io->nvmeio.cmd.cdw12) & (1U << 25)) != 0) {
                ctl_backend_ramdisk_delete(cbe_lun, lbalen->lba, lbalen->len,
                    0);
                ctl_nvme_set_success(&io->nvmeio);
                ctl_config_write_done(io);
                return;
        }

        for (lba = lbalen->lba, lbas = lbalen->len; lbas > 0; lba++, lbas--) {
                page = ctl_backend_ramdisk_getpage(be_lun,
                    lba >> cbe_lun->pblockexp, GP_WRITE);
                if (page == P_UNMAPPED || page == P_ANCHORED) {
                        ctl_nvme_set_space_alloc_fail(&io->nvmeio);
                        ctl_data_submit_done(io);
                        return;
                }
                lbaoff = lba & ~(UINT_MAX << cbe_lun->pblockexp);
                page += lbaoff * cbe_lun->blocksize;
                memset(page, 0, cbe_lun->blocksize);
        }
        ctl_nvme_set_success(&io->nvmeio);
        ctl_config_write_done(io);
}

static void
ctl_backend_ramdisk_dsm(union ctl_io *io)
{
        struct ctl_be_lun *cbe_lun = CTL_BACKEND_LUN(io);
        struct nvme_dsm_range *r;
        uint64_t lba;
        uint32_t num_blocks;
        u_int i, ranges;

        CTL_IO_ASSERT(io, NVME);

        ranges = le32toh(io->nvmeio.cmd.cdw10) & 0xff;
        r = (struct nvme_dsm_range *)io->nvmeio.kern_data_ptr;
        for (i = 0; i < ranges; i++) {
                lba = le64toh(r[i].starting_lba);
                num_blocks = le32toh(r[i].length);
                if ((le32toh(r[i].attributes) & (1U << 2)) != 0)
                        ctl_backend_ramdisk_delete(cbe_lun, lba, num_blocks, 0);
        }

        ctl_nvme_set_success(&io->nvmeio);
        ctl_config_write_done(io);
}

static int
ctl_backend_ramdisk_nvme_config_write(union ctl_io *io)
{
        switch (io->nvmeio.cmd.opc) {
        case NVME_OPC_FLUSH:
                /* We have no cache to flush. */
                ctl_nvme_set_success(&io->nvmeio);
                ctl_config_write_done(io);
                break;
        case NVME_OPC_WRITE_UNCORRECTABLE:
                ctl_backend_ramdisk_wu(io);
                break;
        case NVME_OPC_WRITE_ZEROES:
                ctl_backend_ramdisk_wz(io);
                break;
        case NVME_OPC_DATASET_MANAGEMENT:
                ctl_backend_ramdisk_dsm(io);
                break;
        default:
                ctl_nvme_set_invalid_opcode(&io->nvmeio);
                ctl_config_write_done(io);
                break;
        }
        return (CTL_RETVAL_COMPLETE);
}

static int
ctl_backend_ramdisk_config_write(union ctl_io *io)
{
        switch (io->io_hdr.io_type) {
        case CTL_IO_SCSI:
                return (ctl_backend_ramdisk_scsi_config_write(io));
        case CTL_IO_NVME:
                return (ctl_backend_ramdisk_nvme_config_write(io));
        default:
                __assert_unreachable();
        }
}

static uint64_t
ctl_backend_ramdisk_lun_attr(struct ctl_be_lun *cbe_lun, const char *attrname)
{
        struct ctl_be_ramdisk_lun *be_lun = (struct ctl_be_ramdisk_lun *)cbe_lun;
        uint64_t                val;

        val = UINT64_MAX;
        if (be_lun->cap_bytes == 0)
                return (val);
        sx_slock(&be_lun->page_lock);
        if (strcmp(attrname, "blocksused") == 0) {
                val = be_lun->cap_used / be_lun->cbe_lun.blocksize;
        } else if (strcmp(attrname, "blocksavail") == 0) {
                val = (be_lun->cap_bytes - be_lun->cap_used) /
                    be_lun->cbe_lun.blocksize;
        }
        sx_sunlock(&be_lun->page_lock);
        return (val);
}

static int
ctl_backend_ramdisk_ioctl(struct cdev *dev, u_long cmd, caddr_t addr,
                          int flag, struct thread *td)
{
        struct ctl_be_ramdisk_softc *softc = &rd_softc;
        struct ctl_lun_req *lun_req;
        int retval;

        retval = 0;
        switch (cmd) {
        case CTL_LUN_REQ:
                lun_req = (struct ctl_lun_req *)addr;
                switch (lun_req->reqtype) {
                case CTL_LUNREQ_CREATE:
                        retval = ctl_backend_ramdisk_create(softc, lun_req);
                        break;
                case CTL_LUNREQ_RM:
                        retval = ctl_backend_ramdisk_rm(softc, lun_req);
                        break;
                case CTL_LUNREQ_MODIFY:
                        retval = ctl_backend_ramdisk_modify(softc, lun_req);
                        break;
                default:
                        lun_req->status = CTL_LUN_ERROR;
                        snprintf(lun_req->error_str, sizeof(lun_req->error_str),
                                 "%s: invalid LUN request type %d", __func__,
                                 lun_req->reqtype);
                        break;
                }
                break;
        default:
                retval = ENOTTY;
                break;
        }

        return (retval);
}

static int
ctl_backend_ramdisk_rm(struct ctl_be_ramdisk_softc *softc,
                       struct ctl_lun_req *req)
{
        struct ctl_be_ramdisk_lun *be_lun;
        struct ctl_lun_rm_params *params;
        int retval;

        params = &req->reqdata.rm;
        sx_xlock(&softc->modify_lock);
        mtx_lock(&softc->lock);
        SLIST_FOREACH(be_lun, &softc->lun_list, links) {
                if (be_lun->cbe_lun.lun_id == params->lun_id) {
                        SLIST_REMOVE(&softc->lun_list, be_lun,
                            ctl_be_ramdisk_lun, links);
                        softc->num_luns--;
                        break;
                }
        }
        mtx_unlock(&softc->lock);
        sx_xunlock(&softc->modify_lock);
        if (be_lun == NULL) {
                snprintf(req->error_str, sizeof(req->error_str),
                         "%s: LUN %u is not managed by the ramdisk backend",
                         __func__, params->lun_id);
                goto bailout_error;
        }

        /*
         * Set the waiting flag before we invalidate the LUN.  Our shutdown
         * routine can be called any time after we invalidate the LUN,
         * and can be called from our context.
         *
         * This tells the shutdown routine that we're waiting, or we're
         * going to wait for the shutdown to happen.
         */
        mtx_lock(&softc->lock);
        be_lun->flags |= CTL_BE_RAMDISK_LUN_WAITING;
        mtx_unlock(&softc->lock);

        retval = ctl_remove_lun(&be_lun->cbe_lun);
        if (retval != 0) {
                snprintf(req->error_str, sizeof(req->error_str),
                         "%s: error %d returned from ctl_remove_lun() for "
                         "LUN %d", __func__, retval, params->lun_id);
                mtx_lock(&softc->lock);
                be_lun->flags &= ~CTL_BE_RAMDISK_LUN_WAITING;
                mtx_unlock(&softc->lock);
                goto bailout_error;
        }

        mtx_lock(&softc->lock);
        while ((be_lun->flags & CTL_BE_RAMDISK_LUN_UNCONFIGURED) == 0) {
                retval = msleep(be_lun, &softc->lock, PCATCH, "ctlramrm", 0);
                if (retval == EINTR)
                        break;
        }
        be_lun->flags &= ~CTL_BE_RAMDISK_LUN_WAITING;
        if (be_lun->flags & CTL_BE_RAMDISK_LUN_UNCONFIGURED) {
                mtx_unlock(&softc->lock);
                free(be_lun, M_RAMDISK);
        } else {
                mtx_unlock(&softc->lock);
                return (EINTR);
        }

        req->status = CTL_LUN_OK;
        return (retval);

bailout_error:
        req->status = CTL_LUN_ERROR;
        return (0);
}

static int
ctl_backend_ramdisk_create(struct ctl_be_ramdisk_softc *softc,
                           struct ctl_lun_req *req)
{
        struct ctl_be_ramdisk_lun *be_lun;
        struct ctl_be_lun *cbe_lun;
        struct ctl_lun_create_params *params;
        const char *value;
        char tmpstr[32];
        uint64_t t;
        int retval;

        retval = 0;
        params = &req->reqdata.create;

        be_lun = malloc(sizeof(*be_lun), M_RAMDISK, M_ZERO | M_WAITOK);
        cbe_lun = &be_lun->cbe_lun;
        cbe_lun->options = nvlist_clone(req->args_nvl);
        be_lun->params = req->reqdata.create;
        be_lun->softc = softc;

        if (params->flags & CTL_LUN_FLAG_DEV_TYPE)
                cbe_lun->lun_type = params->device_type;
        else
                cbe_lun->lun_type = T_DIRECT;
        be_lun->flags = 0;
        cbe_lun->flags = 0;
        value = dnvlist_get_string(cbe_lun->options, "ha_role", NULL);
        if (value != NULL) {
                if (strcmp(value, "primary") == 0)
                        cbe_lun->flags |= CTL_LUN_FLAG_PRIMARY;
        } else if (control_softc->flags & CTL_FLAG_ACTIVE_SHELF)
                cbe_lun->flags |= CTL_LUN_FLAG_PRIMARY;

        be_lun->pblocksize = PAGE_SIZE;
        value = dnvlist_get_string(cbe_lun->options, "pblocksize", NULL);
        if (value != NULL) {
                ctl_expand_number(value, &t);
                be_lun->pblocksize = t;
        }
        if (be_lun->pblocksize < 512 || be_lun->pblocksize > 131072) {
                snprintf(req->error_str, sizeof(req->error_str),
                         "%s: unsupported pblocksize %u", __func__,
                         be_lun->pblocksize);
                goto bailout_error;
        }

        if (cbe_lun->lun_type == T_DIRECT ||
            cbe_lun->lun_type == T_CDROM) {
                if (params->blocksize_bytes != 0)
                        cbe_lun->blocksize = params->blocksize_bytes;
                else if (cbe_lun->lun_type == T_CDROM)
                        cbe_lun->blocksize = 2048;
                else
                        cbe_lun->blocksize = 512;
                be_lun->pblockmul = be_lun->pblocksize / cbe_lun->blocksize;
                if (be_lun->pblockmul < 1 || !powerof2(be_lun->pblockmul)) {
                        snprintf(req->error_str, sizeof(req->error_str),
                                 "%s: pblocksize %u not exp2 of blocksize %u",
                                 __func__,
                                 be_lun->pblocksize, cbe_lun->blocksize);
                        goto bailout_error;
                }
                if (params->lun_size_bytes < cbe_lun->blocksize) {
                        snprintf(req->error_str, sizeof(req->error_str),
                                 "%s: LUN size %ju < blocksize %u", __func__,
                                 params->lun_size_bytes, cbe_lun->blocksize);
                        goto bailout_error;
                }
                be_lun->size_blocks = params->lun_size_bytes / cbe_lun->blocksize;
                be_lun->size_bytes = be_lun->size_blocks * cbe_lun->blocksize;
                be_lun->indir = 0;
                t = be_lun->size_bytes / be_lun->pblocksize;
                while (t > 1) {
                        t /= PPP;
                        be_lun->indir++;
                }
                cbe_lun->maxlba = be_lun->size_blocks - 1;
                cbe_lun->pblockexp = fls(be_lun->pblockmul) - 1;
                cbe_lun->pblockoff = 0;
                cbe_lun->ublockexp = cbe_lun->pblockexp;
                cbe_lun->ublockoff = 0;
                cbe_lun->atomicblock = be_lun->pblocksize;
                cbe_lun->opttxferlen = SGPP * be_lun->pblocksize;
                value = dnvlist_get_string(cbe_lun->options, "capacity", NULL);
                if (value != NULL)
                        ctl_expand_number(value, &be_lun->cap_bytes);
        } else {
                be_lun->pblockmul = 1;
                cbe_lun->pblockexp = 0;
        }

        /* Tell the user the blocksize we ended up using */
        params->blocksize_bytes = cbe_lun->blocksize;
        params->lun_size_bytes = be_lun->size_bytes;

        value = dnvlist_get_string(cbe_lun->options, "unmap", NULL);
        if (value == NULL || strcmp(value, "off") != 0)
                cbe_lun->flags |= CTL_LUN_FLAG_UNMAP;
        value = dnvlist_get_string(cbe_lun->options, "readonly", NULL);
        if (value != NULL) {
                if (strcmp(value, "on") == 0)
                        cbe_lun->flags |= CTL_LUN_FLAG_READONLY;
        } else if (cbe_lun->lun_type != T_DIRECT)
                cbe_lun->flags |= CTL_LUN_FLAG_READONLY;
        cbe_lun->serseq = CTL_LUN_SERSEQ_OFF;
        value = dnvlist_get_string(cbe_lun->options, "serseq", NULL);
        if (value != NULL && strcmp(value, "on") == 0)
                cbe_lun->serseq = CTL_LUN_SERSEQ_ON;
        else if (value != NULL && strcmp(value, "read") == 0)
                cbe_lun->serseq = CTL_LUN_SERSEQ_READ;
        else if (value != NULL && strcmp(value, "soft") == 0)
                cbe_lun->serseq = CTL_LUN_SERSEQ_SOFT;
        else if (value != NULL && strcmp(value, "off") == 0)
                cbe_lun->serseq = CTL_LUN_SERSEQ_OFF;

        if (params->flags & CTL_LUN_FLAG_ID_REQ) {
                cbe_lun->req_lun_id = params->req_lun_id;
                cbe_lun->flags |= CTL_LUN_FLAG_ID_REQ;
        } else
                cbe_lun->req_lun_id = 0;

        cbe_lun->lun_shutdown = ctl_backend_ramdisk_lun_shutdown;
        cbe_lun->be = &ctl_be_ramdisk_driver;
        if ((params->flags & CTL_LUN_FLAG_SERIAL_NUM) == 0) {
                snprintf(tmpstr, sizeof(tmpstr), "MYSERIAL%04d",
                         softc->num_luns);
                strncpy((char *)cbe_lun->serial_num, tmpstr,
                        MIN(sizeof(cbe_lun->serial_num), sizeof(tmpstr)));

                /* Tell the user what we used for a serial number */
                strncpy((char *)params->serial_num, tmpstr,
                        MIN(sizeof(params->serial_num), sizeof(tmpstr)));
        } else { 
                strncpy((char *)cbe_lun->serial_num, params->serial_num,
                        MIN(sizeof(cbe_lun->serial_num),
                            sizeof(params->serial_num)));
        }
        if ((params->flags & CTL_LUN_FLAG_DEVID) == 0) {
                snprintf(tmpstr, sizeof(tmpstr), "MYDEVID%04d", softc->num_luns);
                strncpy((char *)cbe_lun->device_id, tmpstr,
                        MIN(sizeof(cbe_lun->device_id), sizeof(tmpstr)));

                /* Tell the user what we used for a device ID */
                strncpy((char *)params->device_id, tmpstr,
                        MIN(sizeof(params->device_id), sizeof(tmpstr)));
        } else {
                strncpy((char *)cbe_lun->device_id, params->device_id,
                        MIN(sizeof(cbe_lun->device_id),
                            sizeof(params->device_id)));
        }

        STAILQ_INIT(&be_lun->cont_queue);
        sx_init(&be_lun->page_lock, "ctlram page");
        if (be_lun->cap_bytes == 0) {
                be_lun->indir = 0;
                be_lun->pages = malloc(be_lun->pblocksize, M_RAMDISK, M_WAITOK);
        }
        be_lun->zero_page = malloc(be_lun->pblocksize, M_RAMDISK,
            M_WAITOK|M_ZERO);
        mtx_init(&be_lun->queue_lock, "ctlram queue", NULL, MTX_DEF);
        TASK_INIT(&be_lun->io_task, /*priority*/0, ctl_backend_ramdisk_worker,
            be_lun);

        be_lun->io_taskqueue = taskqueue_create("ctlramtq", M_WAITOK,
            taskqueue_thread_enqueue, /*context*/&be_lun->io_taskqueue);
        if (be_lun->io_taskqueue == NULL) {
                snprintf(req->error_str, sizeof(req->error_str),
                         "%s: Unable to create taskqueue", __func__);
                goto bailout_error;
        }

        retval = taskqueue_start_threads_in_proc(&be_lun->io_taskqueue,
                                         /*num threads*/1,
                                         /*priority*/PUSER,
                                         /*proc*/control_softc->ctl_proc,
                                         /*thread name*/"ramdisk");
        if (retval != 0)
                goto bailout_error;

        retval = ctl_add_lun(&be_lun->cbe_lun);
        if (retval != 0) {
                snprintf(req->error_str, sizeof(req->error_str),
                         "%s: ctl_add_lun() returned error %d, see dmesg for "
                        "details", __func__, retval);
                retval = 0;
                goto bailout_error;
        }

        mtx_lock(&softc->lock);
        softc->num_luns++;
        SLIST_INSERT_HEAD(&softc->lun_list, be_lun, links);
        mtx_unlock(&softc->lock);

        params->req_lun_id = cbe_lun->lun_id;

        req->status = CTL_LUN_OK;
        return (retval);

bailout_error:
        req->status = CTL_LUN_ERROR;
        if (be_lun != NULL) {
                if (be_lun->io_taskqueue != NULL)
                        taskqueue_free(be_lun->io_taskqueue);
                nvlist_destroy(cbe_lun->options);
                free(be_lun->zero_page, M_RAMDISK);
                ctl_backend_ramdisk_freeallpages(be_lun->pages, be_lun->indir);
                sx_destroy(&be_lun->page_lock);
                mtx_destroy(&be_lun->queue_lock);
                free(be_lun, M_RAMDISK);
        }
        return (retval);
}

static int
ctl_backend_ramdisk_modify(struct ctl_be_ramdisk_softc *softc,
                       struct ctl_lun_req *req)
{
        struct ctl_be_ramdisk_lun *be_lun;
        struct ctl_be_lun *cbe_lun;
        struct ctl_lun_modify_params *params;
        const char *value;
        uint32_t blocksize;
        int wasprim;

        params = &req->reqdata.modify;
        sx_xlock(&softc->modify_lock);
        mtx_lock(&softc->lock);
        SLIST_FOREACH(be_lun, &softc->lun_list, links) {
                if (be_lun->cbe_lun.lun_id == params->lun_id)
                        break;
        }
        mtx_unlock(&softc->lock);
        if (be_lun == NULL) {
                snprintf(req->error_str, sizeof(req->error_str),
                         "%s: LUN %u is not managed by the ramdisk backend",
                         __func__, params->lun_id);
                goto bailout_error;
        }
        cbe_lun = &be_lun->cbe_lun;

        if (params->lun_size_bytes != 0)
                be_lun->params.lun_size_bytes = params->lun_size_bytes;

        if (req->args_nvl != NULL) {
                nvlist_destroy(cbe_lun->options);
                cbe_lun->options = nvlist_clone(req->args_nvl);
        }

        wasprim = (cbe_lun->flags & CTL_LUN_FLAG_PRIMARY);
        value = dnvlist_get_string(cbe_lun->options, "ha_role", NULL);
        if (value != NULL) {
                if (strcmp(value, "primary") == 0)
                        cbe_lun->flags |= CTL_LUN_FLAG_PRIMARY;
                else
                        cbe_lun->flags &= ~CTL_LUN_FLAG_PRIMARY;
        } else if (control_softc->flags & CTL_FLAG_ACTIVE_SHELF)
                cbe_lun->flags |= CTL_LUN_FLAG_PRIMARY;
        else
                cbe_lun->flags &= ~CTL_LUN_FLAG_PRIMARY;
        if (wasprim != (cbe_lun->flags & CTL_LUN_FLAG_PRIMARY)) {
                if (cbe_lun->flags & CTL_LUN_FLAG_PRIMARY)
                        ctl_lun_primary(cbe_lun);
                else
                        ctl_lun_secondary(cbe_lun);
        }

        blocksize = be_lun->cbe_lun.blocksize;
        if (be_lun->params.lun_size_bytes < blocksize) {
                snprintf(req->error_str, sizeof(req->error_str),
                        "%s: LUN size %ju < blocksize %u", __func__,
                        be_lun->params.lun_size_bytes, blocksize);
                goto bailout_error;
        }
        be_lun->size_blocks = be_lun->params.lun_size_bytes / blocksize;
        be_lun->size_bytes = be_lun->size_blocks * blocksize;
        be_lun->cbe_lun.maxlba = be_lun->size_blocks - 1;
        ctl_lun_capacity_changed(&be_lun->cbe_lun);

        /* Tell the user the exact size we ended up using */
        params->lun_size_bytes = be_lun->size_bytes;

        sx_xunlock(&softc->modify_lock);
        req->status = CTL_LUN_OK;
        return (0);

bailout_error:
        sx_xunlock(&softc->modify_lock);
        req->status = CTL_LUN_ERROR;
        return (0);
}

static void
ctl_backend_ramdisk_lun_shutdown(struct ctl_be_lun *cbe_lun)
{
        struct ctl_be_ramdisk_lun *be_lun = (struct ctl_be_ramdisk_lun *)cbe_lun;
        struct ctl_be_ramdisk_softc *softc = be_lun->softc;

        taskqueue_drain_all(be_lun->io_taskqueue);
        taskqueue_free(be_lun->io_taskqueue);
        nvlist_destroy(be_lun->cbe_lun.options);
        free(be_lun->zero_page, M_RAMDISK);
        ctl_backend_ramdisk_freeallpages(be_lun->pages, be_lun->indir);
        sx_destroy(&be_lun->page_lock);
        mtx_destroy(&be_lun->queue_lock);

        mtx_lock(&softc->lock);
        be_lun->flags |= CTL_BE_RAMDISK_LUN_UNCONFIGURED;
        if (be_lun->flags & CTL_BE_RAMDISK_LUN_WAITING)
                wakeup(be_lun);
        else
                free(be_lun, M_RAMDISK);
        mtx_unlock(&softc->lock);
}