/*-
 * SPDX-License-Identifier: BSD-2-Clause
 *
 * Copyright (c) 2003 Silicon Graphics International Corp.
 * Copyright (c) 2009-2011 Spectra Logic Corporation
 * Copyright (c) 2012,2021 The FreeBSD Foundation
 * Copyright (c) 2014-2021 Alexander Motin <mav@FreeBSD.org>
 * All rights reserved.
 *
 * Portions of this software were developed by Edward Tomasz Napierala
 * under sponsorship from the FreeBSD Foundation.
 *
 * Portions of this software were developed by Ka Ho Ng <khng@FreeBSD.org>
 * 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_block.c#5 $
 */
/*
 * CAM Target Layer driver backend for block devices.
 *
 * Author: Ken Merry <ken@FreeBSD.org>
 */
#include <sys/param.h>
#include <sys/systm.h>
#include <sys/kernel.h>
#include <sys/types.h>
#include <sys/kthread.h>
#include <sys/bio.h>
#include <sys/fcntl.h>
#include <sys/limits.h>
#include <sys/lock.h>
#include <sys/mutex.h>
#include <sys/condvar.h>
#include <sys/malloc.h>
#include <sys/conf.h>
#include <sys/ioccom.h>
#include <sys/queue.h>
#include <sys/sbuf.h>
#include <sys/endian.h>
#include <sys/uio.h>
#include <sys/buf.h>
#include <sys/taskqueue.h>
#include <sys/vnode.h>
#include <sys/namei.h>
#include <sys/mount.h>
#include <sys/disk.h>
#include <sys/fcntl.h>
#include <sys/filedesc.h>
#include <sys/filio.h>
#include <sys/proc.h>
#include <sys/pcpu.h>
#include <sys/module.h>
#include <sys/sdt.h>
#include <sys/devicestat.h>
#include <sys/sysctl.h>
#include <sys/nv.h>
#include <sys/dnv.h>
#include <sys/sx.h>
#include <sys/unistd.h>

#include <geom/geom.h>

#include <cam/cam.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_backend.h>
#include <cam/ctl/ctl_ioctl.h>
#include <cam/ctl/ctl_ha.h>
#include <cam/ctl/ctl_scsi_all.h>
#include <cam/ctl/ctl_private.h>
#include <cam/ctl/ctl_error.h>

/*
 * The idea here is to allocate enough S/G space to handle at least 1MB I/Os.
 * On systems with small maxphys it can be 8 128KB segments.  On large systems
 * it can be up to 8 1MB segments.  I/Os larger than that we'll split.
 */
#define CTLBLK_MAX_SEGS         8
#define CTLBLK_HALF_SEGS        (CTLBLK_MAX_SEGS / 2)
#define CTLBLK_MIN_SEG          (128 * 1024)
#define CTLBLK_MAX_SEG          MIN(1024 * 1024, MAX(CTLBLK_MIN_SEG, maxphys))
#define CTLBLK_MAX_IO_SIZE      (CTLBLK_MAX_SEG * CTLBLK_MAX_SEGS)

#ifdef CTLBLK_DEBUG
#define DPRINTF(fmt, args...) \
    printf("cbb(%s:%d): " fmt, __FUNCTION__, __LINE__, ##args)
#else
#define DPRINTF(fmt, args...) do {} while(0)
#endif

#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 DSM_RANGE(io)   ((io)->io_hdr.ctl_private[CTL_PRIV_LBA_LEN].integer)

SDT_PROVIDER_DEFINE(cbb);

typedef enum {
        CTL_BE_BLOCK_LUN_UNCONFIGURED   = 0x01,
        CTL_BE_BLOCK_LUN_WAITING        = 0x04,
} ctl_be_block_lun_flags;

typedef enum {
        CTL_BE_BLOCK_NONE,
        CTL_BE_BLOCK_DEV,
        CTL_BE_BLOCK_FILE
} ctl_be_block_type;

struct ctl_be_block_filedata {
        struct ucred *cred;
};

union ctl_be_block_bedata {
        struct ctl_be_block_filedata file;
};

struct ctl_be_block_io;
struct ctl_be_block_lun;

typedef void (*cbb_dispatch_t)(struct ctl_be_block_lun *be_lun,
                               struct ctl_be_block_io *beio);
typedef uint64_t (*cbb_getattr_t)(struct ctl_be_block_lun *be_lun,
                                  const char *attrname);

/*
 * Backend LUN structure.  There is a 1:1 mapping between a block device
 * and a backend block LUN, and between a backend block LUN and a CTL LUN.
 */
struct ctl_be_block_lun {
        struct ctl_be_lun cbe_lun;              /* Must be first element. */
        struct ctl_lun_create_params params;
        char *dev_path;
        ctl_be_block_type dev_type;
        struct vnode *vn;
        union ctl_be_block_bedata backend;
        cbb_dispatch_t dispatch;
        cbb_dispatch_t lun_flush;
        cbb_dispatch_t unmap;
        cbb_dispatch_t get_lba_status;
        cbb_getattr_t getattr;
        uint64_t size_blocks;
        uint64_t size_bytes;
        struct ctl_be_block_softc *softc;
        struct devstat *disk_stats;
        ctl_be_block_lun_flags flags;
        SLIST_ENTRY(ctl_be_block_lun) links;
        struct taskqueue *io_taskqueue;
        struct task io_task;
        int num_threads;
        STAILQ_HEAD(, ctl_io_hdr) input_queue;
        STAILQ_HEAD(, ctl_io_hdr) config_read_queue;
        STAILQ_HEAD(, ctl_io_hdr) config_write_queue;
        STAILQ_HEAD(, ctl_io_hdr) datamove_queue;
        struct mtx_padalign io_lock;
        struct mtx_padalign queue_lock;
};

/*
 * Overall softc structure for the block backend module.
 */
struct ctl_be_block_softc {
        struct sx                        modify_lock;
        struct mtx                       lock;
        int                              num_luns;
        SLIST_HEAD(, ctl_be_block_lun)   lun_list;
        uma_zone_t                       beio_zone;
        uma_zone_t                       bufmin_zone;
        uma_zone_t                       bufmax_zone;
};

static struct ctl_be_block_softc backend_block_softc;

/*
 * Per-I/O information.
 */
struct ctl_be_block_io {
        union ctl_io                    *io;
        struct ctl_sg_entry             sg_segs[CTLBLK_MAX_SEGS];
        struct iovec                    xiovecs[CTLBLK_MAX_SEGS];
        int                             refcnt;
        int                             bio_cmd;
        int                             two_sglists;
        int                             num_segs;
        int                             num_bios_sent;
        int                             num_bios_done;
        int                             send_complete;
        int                             first_error;
        uint64_t                        first_error_offset;
        struct bintime                  ds_t0;
        devstat_tag_type                ds_tag_type;
        devstat_trans_flags             ds_trans_type;
        uint64_t                        io_len;
        uint64_t                        io_offset;
        int                             io_arg;
        struct ctl_be_block_softc       *softc;
        struct ctl_be_block_lun         *lun;
        void (*beio_cont)(struct ctl_be_block_io *beio); /* to continue processing */
};

static int cbb_num_threads = 32;
SYSCTL_NODE(_kern_cam_ctl, OID_AUTO, block, CTLFLAG_RD | CTLFLAG_MPSAFE, 0,
            "CAM Target Layer Block Backend");
SYSCTL_INT(_kern_cam_ctl_block, OID_AUTO, num_threads, CTLFLAG_RWTUN,
           &cbb_num_threads, 0, "Number of threads per backing file");

static struct ctl_be_block_io *ctl_alloc_beio(struct ctl_be_block_softc *softc);
static void ctl_free_beio(struct ctl_be_block_io *beio);
static void ctl_complete_beio(struct ctl_be_block_io *beio);
static int ctl_be_block_move_done(union ctl_io *io, bool samethr);
static void ctl_be_block_biodone(struct bio *bio);
static void ctl_be_block_flush_file(struct ctl_be_block_lun *be_lun,
                                    struct ctl_be_block_io *beio);
static void ctl_be_block_dispatch_file(struct ctl_be_block_lun *be_lun,
                                       struct ctl_be_block_io *beio);
static void ctl_be_block_gls_file(struct ctl_be_block_lun *be_lun,
                                  struct ctl_be_block_io *beio);
static uint64_t ctl_be_block_getattr_file(struct ctl_be_block_lun *be_lun,
                                         const char *attrname);
static void ctl_be_block_unmap_file(struct ctl_be_block_lun *be_lun,
                                    struct ctl_be_block_io *beio);
static void ctl_be_block_flush_dev(struct ctl_be_block_lun *be_lun,
                                   struct ctl_be_block_io *beio);
static void ctl_be_block_unmap_dev(struct ctl_be_block_lun *be_lun,
                                   struct ctl_be_block_io *beio);
static void ctl_be_block_dispatch_dev(struct ctl_be_block_lun *be_lun,
                                      struct ctl_be_block_io *beio);
static uint64_t ctl_be_block_getattr_dev(struct ctl_be_block_lun *be_lun,
                                         const char *attrname);
static void ctl_be_block_cr_dispatch(struct ctl_be_block_lun *be_lun,
                                    union ctl_io *io);
static void ctl_be_block_cw_dispatch(struct ctl_be_block_lun *be_lun,
                                    union ctl_io *io);
static void ctl_be_block_dispatch(struct ctl_be_block_lun *be_lun,
                                  union ctl_io *io);
static void ctl_be_block_worker(void *context, int pending);
static int ctl_be_block_submit(union ctl_io *io);
static int ctl_be_block_ioctl(struct cdev *dev, u_long cmd, caddr_t addr,
                                   int flag, struct thread *td);
static int ctl_be_block_open_file(struct ctl_be_block_lun *be_lun,
                                  struct ctl_lun_req *req);
static int ctl_be_block_open_dev(struct ctl_be_block_lun *be_lun,
                                 struct ctl_lun_req *req);
static int ctl_be_block_close(struct ctl_be_block_lun *be_lun);
static int ctl_be_block_open(struct ctl_be_block_lun *be_lun,
                             struct ctl_lun_req *req);
static int ctl_be_block_create(struct ctl_be_block_softc *softc,
                               struct ctl_lun_req *req);
static int ctl_be_block_rm(struct ctl_be_block_softc *softc,
                           struct ctl_lun_req *req);
static int ctl_be_block_modify(struct ctl_be_block_softc *softc,
                           struct ctl_lun_req *req);
static void ctl_be_block_lun_shutdown(struct ctl_be_lun *cbe_lun);
static int ctl_be_block_config_write(union ctl_io *io);
static int ctl_be_block_config_read(union ctl_io *io);
static int ctl_be_block_lun_info(struct ctl_be_lun *cbe_lun, struct sbuf *sb);
static uint64_t ctl_be_block_lun_attr(struct ctl_be_lun *cbe_lun, const char *attrname);
static int ctl_be_block_init(void);
static int ctl_be_block_shutdown(void);

static struct ctl_backend_driver ctl_be_block_driver = 
{
        .name = "block",
        .flags = CTL_BE_FLAG_HAS_CONFIG,
        .init = ctl_be_block_init,
        .shutdown = ctl_be_block_shutdown,
        .data_submit = ctl_be_block_submit,
        .config_read = ctl_be_block_config_read,
        .config_write = ctl_be_block_config_write,
        .ioctl = ctl_be_block_ioctl,
        .lun_info = ctl_be_block_lun_info,
        .lun_attr = ctl_be_block_lun_attr
};

MALLOC_DEFINE(M_CTLBLK, "ctlblock", "Memory used for CTL block backend");
CTL_BACKEND_DECLARE(cbb, ctl_be_block_driver);

static void
ctl_alloc_seg(struct ctl_be_block_softc *softc, struct ctl_sg_entry *sg,
    size_t len)
{

        if (len <= CTLBLK_MIN_SEG) {
                sg->addr = uma_zalloc(softc->bufmin_zone, M_WAITOK);
        } else {
                KASSERT(len <= CTLBLK_MAX_SEG,
                    ("Too large alloc %zu > %lu", len, CTLBLK_MAX_SEG));
                sg->addr = uma_zalloc(softc->bufmax_zone, M_WAITOK);
        }
        sg->len = len;
}

static void
ctl_free_seg(struct ctl_be_block_softc *softc, struct ctl_sg_entry *sg)
{

        if (sg->len <= CTLBLK_MIN_SEG) {
                uma_zfree(softc->bufmin_zone, sg->addr);
        } else {
                KASSERT(sg->len <= CTLBLK_MAX_SEG,
                    ("Too large free %zu > %lu", sg->len, CTLBLK_MAX_SEG));
                uma_zfree(softc->bufmax_zone, sg->addr);
        }
}

static struct ctl_be_block_io *
ctl_alloc_beio(struct ctl_be_block_softc *softc)
{
        struct ctl_be_block_io *beio;

        beio = uma_zalloc(softc->beio_zone, M_WAITOK | M_ZERO);
        beio->softc = softc;
        beio->refcnt = 1;
        return (beio);
}

static void
ctl_real_free_beio(struct ctl_be_block_io *beio)
{
        struct ctl_be_block_softc *softc = beio->softc;
        int i;

        for (i = 0; i < beio->num_segs; i++) {
                ctl_free_seg(softc, &beio->sg_segs[i]);

                /* For compare we had two equal S/G lists. */
                if (beio->two_sglists) {
                        ctl_free_seg(softc,
                            &beio->sg_segs[i + CTLBLK_HALF_SEGS]);
                }
        }

        uma_zfree(softc->beio_zone, beio);
}

static void
ctl_refcnt_beio(void *arg, int diff)
{
        struct ctl_be_block_io *beio = arg;

        if (atomic_fetchadd_int(&beio->refcnt, diff) + diff == 0)
                ctl_real_free_beio(beio);
}

static void
ctl_free_beio(struct ctl_be_block_io *beio)
{

        ctl_refcnt_beio(beio, -1);
}

static void
ctl_complete_beio(struct ctl_be_block_io *beio)
{
        union ctl_io *io = beio->io;

        if (beio->beio_cont != NULL) {
                beio->beio_cont(beio);
        } else {
                ctl_free_beio(beio);
                ctl_data_submit_done(io);
        }
}

static void
ctl_be_block_io_error(union ctl_io *io, int bio_cmd, uint16_t retry_count)
{
        switch (io->io_hdr.io_type) {
        case CTL_IO_SCSI:
                if (bio_cmd == BIO_FLUSH) {
                        /* XXX KDM is there is a better error here? */
                        ctl_set_internal_failure(&io->scsiio,
                                                 /*sks_valid*/ 1,
                                                 retry_count);
                } else {
                        ctl_set_medium_error(&io->scsiio, bio_cmd == BIO_READ);
                }
                break;
        case CTL_IO_NVME:
                switch (bio_cmd) {
                case BIO_FLUSH:
                case BIO_WRITE:
                        ctl_nvme_set_write_fault(&io->nvmeio);
                        break;
                case BIO_READ:
                        ctl_nvme_set_unrecoverable_read_error(&io->nvmeio);
                        break;
                default:
                        ctl_nvme_set_internal_error(&io->nvmeio);
                        break;
                }
                break;
        default:
                __assert_unreachable();
        }
}

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 void
ctl_be_block_compare(union ctl_io *io)
{
        struct ctl_be_block_io *beio;
        uint64_t off, res;
        int i;

        beio = (struct ctl_be_block_io *)PRIV(io)->ptr;
        off = 0;
        for (i = 0; i < beio->num_segs; i++) {
                res = cmp(beio->sg_segs[i].addr,
                    beio->sg_segs[i + CTLBLK_HALF_SEGS].addr,
                    beio->sg_segs[i].len);
                off += res;
                if (res < beio->sg_segs[i].len)
                        break;
        }
        if (i < beio->num_segs) {
                ctl_io_set_compare_failure(io, off);
        } else
                ctl_io_set_success(io);
}

static int
ctl_be_block_move_done(union ctl_io *io, bool samethr)
{
        struct ctl_be_block_io *beio;
        struct ctl_be_block_lun *be_lun;
        struct ctl_lba_len_flags *lbalen;

        beio = (struct ctl_be_block_io *)PRIV(io)->ptr;

        DPRINTF("entered\n");
        ctl_add_kern_rel_offset(io, ctl_kern_data_len(io));

        /*
         * We set status at this point for read and compare commands.
         */
        if ((io->io_hdr.flags & CTL_FLAG_ABORT) == 0 &&
            (io->io_hdr.status & CTL_STATUS_MASK) == CTL_STATUS_NONE) {
                lbalen = ARGS(io);
                if (lbalen->flags & CTL_LLF_READ) {
                        ctl_io_set_success(io);
                } else if (lbalen->flags & CTL_LLF_COMPARE) {
                        /* We have two data blocks ready for comparison. */
                        ctl_be_block_compare(io);
                }
        }

        /*
         * If this is a read, or a write with errors, it is done.
         */
        if ((beio->bio_cmd == BIO_READ)
         || ((io->io_hdr.flags & CTL_FLAG_ABORT) != 0)
         || ((io->io_hdr.status & CTL_STATUS_MASK) != CTL_STATUS_NONE)) {
                ctl_complete_beio(beio);
                return (0);
        }

        /*
         * At this point, we have a write and the DMA completed successfully.
         * If we were called synchronously in the original thread then just
         * dispatch, otherwise we now have to queue it to the task queue to
         * execute the backend I/O.  That is because we do blocking
         * memory allocations, and in the file backing case, blocking I/O.
         * This move done routine is generally called in the SIM's
         * interrupt context, and therefore we cannot block.
         */
        be_lun = (struct ctl_be_block_lun *)CTL_BACKEND_LUN(io);
        if (samethr) {
                be_lun->dispatch(be_lun, beio);
        } else {
                mtx_lock(&be_lun->queue_lock);
                STAILQ_INSERT_TAIL(&be_lun->datamove_queue, &io->io_hdr, links);
                mtx_unlock(&be_lun->queue_lock);
                taskqueue_enqueue(be_lun->io_taskqueue, &be_lun->io_task);
        }
        return (0);
}

static void
ctl_be_block_biodone(struct bio *bio)
{
        struct ctl_be_block_io *beio = bio->bio_caller1;
        struct ctl_be_block_lun *be_lun = beio->lun;
        struct ctl_be_lun *cbe_lun = &be_lun->cbe_lun;
        union ctl_io *io;
        int error;

        io = beio->io;

        DPRINTF("entered\n");

        error = bio->bio_error;
        mtx_lock(&be_lun->io_lock);
        if (error != 0 &&
            (beio->first_error == 0 ||
             bio->bio_offset < beio->first_error_offset)) {
                beio->first_error = error;
                beio->first_error_offset = bio->bio_offset;
        }

        beio->num_bios_done++;

        /*
         * XXX KDM will this cause WITNESS to complain?  Holding a lock
         * during the free might cause it to complain.
         */
        g_destroy_bio(bio);

        /*
         * If the send complete bit isn't set, or we aren't the last I/O to
         * complete, then we're done.
         */
        if ((beio->send_complete == 0)
         || (beio->num_bios_done < beio->num_bios_sent)) {
                mtx_unlock(&be_lun->io_lock);
                return;
        }

        /*
         * At this point, we've verified that we are the last I/O to
         * complete, so it's safe to drop the lock.
         */
        devstat_end_transaction(beio->lun->disk_stats, beio->io_len,
            beio->ds_tag_type, beio->ds_trans_type,
            /*now*/ NULL, /*then*/&beio->ds_t0);
        mtx_unlock(&be_lun->io_lock);

        /*
         * If there are any errors from the backing device, we fail the
         * entire I/O with a medium error.
         */
        error = beio->first_error;
        if (error != 0) {
                if (error == EOPNOTSUPP) {
                        ctl_io_set_invalid_opcode(io);
                } else if (error == ENOSPC || error == EDQUOT) {
                        ctl_io_set_space_alloc_fail(io);
                } else if (error == EROFS || error == EACCES) {
                        ctl_io_set_hw_write_protected(io);
                } else {
                        ctl_be_block_io_error(io, beio->bio_cmd,
                            /*retry_count*/ 0xbad2);
                }
                ctl_complete_beio(beio);
                return;
        }

        /*
         * If this is a write, a flush, a delete or verify, we're all done.
         * If this is a read, we can now send the data to the user.
         */
        if ((beio->bio_cmd == BIO_WRITE)
         || (beio->bio_cmd == BIO_FLUSH)
         || (beio->bio_cmd == BIO_DELETE)
         || (ARGS(io)->flags & CTL_LLF_VERIFY)) {
                ctl_io_set_success(io);
                ctl_complete_beio(beio);
        } else {
                if ((ARGS(io)->flags & CTL_LLF_READ) &&
                    beio->beio_cont == NULL) {
                        ctl_io_set_success(io);
                        if (cbe_lun->serseq >= CTL_LUN_SERSEQ_SOFT)
                                ctl_serseq_done(io);
                }
                ctl_datamove(io);
        }
}

static void
ctl_be_block_flush_file(struct ctl_be_block_lun *be_lun,
                        struct ctl_be_block_io *beio)
{
        union ctl_io *io = beio->io;
        struct mount *mountpoint;
        int error;

        DPRINTF("entered\n");

        binuptime(&beio->ds_t0);
        devstat_start_transaction(beio->lun->disk_stats, &beio->ds_t0);

        (void) vn_start_write(be_lun->vn, &mountpoint, V_WAIT);

        vn_lock(be_lun->vn, vn_lktype_write(mountpoint, be_lun->vn) |
            LK_RETRY);
        error = VOP_FSYNC(be_lun->vn, beio->io_arg ? MNT_NOWAIT : MNT_WAIT,
            curthread);
        VOP_UNLOCK(be_lun->vn);

        vn_finished_write(mountpoint);

        mtx_lock(&be_lun->io_lock);
        devstat_end_transaction(beio->lun->disk_stats, beio->io_len,
            beio->ds_tag_type, beio->ds_trans_type,
            /*now*/ NULL, /*then*/&beio->ds_t0);
        mtx_unlock(&be_lun->io_lock);

        if (error == 0)
                ctl_io_set_success(io);
        else {
                ctl_be_block_io_error(io, BIO_FLUSH,
                    /*retry_count*/ 0xbad1);
        }

        ctl_complete_beio(beio);
}

SDT_PROBE_DEFINE1(cbb, , read, file_start, "uint64_t");
SDT_PROBE_DEFINE1(cbb, , write, file_start, "uint64_t");
SDT_PROBE_DEFINE1(cbb, , read, file_done,"uint64_t");
SDT_PROBE_DEFINE1(cbb, , write, file_done, "uint64_t");

static void
ctl_be_block_dispatch_file(struct ctl_be_block_lun *be_lun,
                           struct ctl_be_block_io *beio)
{
        struct ctl_be_lun *cbe_lun = &be_lun->cbe_lun;
        struct ctl_be_block_filedata *file_data;
        union ctl_io *io;
        struct uio xuio;
        struct iovec *xiovec;
        size_t s;
        int error, flags, i;

        DPRINTF("entered\n");

        file_data = &be_lun->backend.file;
        io = beio->io;
        flags = 0;
        if (ARGS(io)->flags & CTL_LLF_DPO)
                flags |= IO_DIRECT;
        if (beio->bio_cmd == BIO_WRITE && ARGS(io)->flags & CTL_LLF_FUA)
                flags |= IO_SYNC;

        bzero(&xuio, sizeof(xuio));
        if (beio->bio_cmd == BIO_READ) {
                SDT_PROBE0(cbb, , read, file_start);
                xuio.uio_rw = UIO_READ;
        } else {
                SDT_PROBE0(cbb, , write, file_start);
                xuio.uio_rw = UIO_WRITE;
        }
        xuio.uio_offset = beio->io_offset;
        xuio.uio_resid = beio->io_len;
        xuio.uio_segflg = UIO_SYSSPACE;
        xuio.uio_iov = beio->xiovecs;
        xuio.uio_iovcnt = beio->num_segs;
        xuio.uio_td = curthread;

        for (i = 0, xiovec = xuio.uio_iov; i < xuio.uio_iovcnt; i++, xiovec++) {
                xiovec->iov_base = beio->sg_segs[i].addr;
                xiovec->iov_len = beio->sg_segs[i].len;
        }

        binuptime(&beio->ds_t0);
        devstat_start_transaction(beio->lun->disk_stats, &beio->ds_t0);

        if (beio->bio_cmd == BIO_READ) {
                vn_lock(be_lun->vn, LK_SHARED | LK_RETRY);

                if (beio->beio_cont == NULL &&
                    cbe_lun->serseq == CTL_LUN_SERSEQ_SOFT)
                        ctl_serseq_done(io);
                /*
                 * UFS pays attention to IO_DIRECT for reads.  If the
                 * DIRECTIO option is configured into the kernel, it calls
                 * ffs_rawread().  But that only works for single-segment
                 * uios with user space addresses.  In our case, with a
                 * kernel uio, it still reads into the buffer cache, but it
                 * will just try to release the buffer from the cache later
                 * on in ffs_read().
                 *
                 * ZFS does not pay attention to IO_DIRECT for reads.
                 *
                 * UFS does not pay attention to IO_SYNC for reads.
                 *
                 * ZFS pays attention to IO_SYNC (which translates into the
                 * Solaris define FRSYNC for zfs_read()) for reads.  It
                 * attempts to sync the file before reading.
                 */
                error = VOP_READ(be_lun->vn, &xuio, flags, file_data->cred);

                VOP_UNLOCK(be_lun->vn);
                SDT_PROBE0(cbb, , read, file_done);
                if (error == 0 && xuio.uio_resid > 0) {
                        /*
                         * If we read less then requested (EOF), then
                         * we should clean the rest of the buffer.
                         */
                        s = beio->io_len - xuio.uio_resid;
                        for (i = 0; i < beio->num_segs; i++) {
                                if (s >= beio->sg_segs[i].len) {
                                        s -= beio->sg_segs[i].len;
                                        continue;
                                }
                                bzero((uint8_t *)beio->sg_segs[i].addr + s,
                                    beio->sg_segs[i].len - s);
                                s = 0;
                        }
                }
        } else {
                struct mount *mountpoint;

                (void)vn_start_write(be_lun->vn, &mountpoint, V_WAIT);
                vn_lock(be_lun->vn, vn_lktype_write(mountpoint,
                    be_lun->vn) | LK_RETRY);

                /*
                 * UFS pays attention to IO_DIRECT for writes.  The write
                 * is done asynchronously.  (Normally the write would just
                 * get put into cache.
                 *
                 * UFS pays attention to IO_SYNC for writes.  It will
                 * attempt to write the buffer out synchronously if that
                 * flag is set.
                 *
                 * ZFS does not pay attention to IO_DIRECT for writes.
                 *
                 * ZFS pays attention to IO_SYNC (a.k.a. FSYNC or FRSYNC)
                 * for writes.  It will flush the transaction from the
                 * cache before returning.
                 */
                error = VOP_WRITE(be_lun->vn, &xuio, flags, file_data->cred);
                VOP_UNLOCK(be_lun->vn);

                vn_finished_write(mountpoint);
                SDT_PROBE0(cbb, , write, file_done);
        }

        mtx_lock(&be_lun->io_lock);
        devstat_end_transaction(beio->lun->disk_stats, beio->io_len,
            beio->ds_tag_type, beio->ds_trans_type,
            /*now*/ NULL, /*then*/&beio->ds_t0);
        mtx_unlock(&be_lun->io_lock);

        /*
         * If we got an error, set the sense data to "MEDIUM ERROR" and
         * return the I/O to the user.
         */
        if (error != 0) {
                if (error == ENOSPC || error == EDQUOT) {
                        ctl_io_set_space_alloc_fail(io);
                } else if (error == EROFS || error == EACCES) {
                        ctl_io_set_hw_write_protected(io);
                } else {
                        ctl_be_block_io_error(io, beio->bio_cmd, 0);
                }
                ctl_complete_beio(beio);
                return;
        }

        /*
         * If this is a write or a verify, we're all done.
         * If this is a read, we can now send the data to the user.
         */
        if ((beio->bio_cmd == BIO_WRITE) ||
            (ARGS(io)->flags & CTL_LLF_VERIFY)) {
                ctl_io_set_success(io);
                ctl_complete_beio(beio);
        } else {
                if ((ARGS(io)->flags & CTL_LLF_READ) &&
                    beio->beio_cont == NULL) {
                        ctl_io_set_success(io);
                        if (cbe_lun->serseq > CTL_LUN_SERSEQ_SOFT)
                                ctl_serseq_done(io);
                }
                ctl_datamove(io);
        }
}

static void
ctl_be_block_gls_file(struct ctl_be_block_lun *be_lun,
                        struct ctl_be_block_io *beio)
{
        union ctl_io *io = beio->io;
        struct ctl_lba_len_flags *lbalen = ARGS(io);
        struct scsi_get_lba_status_data *data;
        off_t roff, off;
        int error, status;

        DPRINTF("entered\n");

        CTL_IO_ASSERT(io, SCSI);

        off = roff = ((off_t)lbalen->lba) * be_lun->cbe_lun.blocksize;
        vn_lock(be_lun->vn, LK_SHARED | LK_RETRY);
        error = VOP_IOCTL(be_lun->vn, FIOSEEKHOLE, &off,
            0, curthread->td_ucred, curthread);
        if (error == 0 && off > roff)
                status = 0;     /* mapped up to off */
        else {
                error = VOP_IOCTL(be_lun->vn, FIOSEEKDATA, &off,
                    0, curthread->td_ucred, curthread);
                if (error == 0 && off > roff)
                        status = 1;     /* deallocated up to off */
                else {
                        status = 0;     /* unknown up to the end */
                        off = be_lun->size_bytes;
                }
        }
        VOP_UNLOCK(be_lun->vn);

        data = (struct scsi_get_lba_status_data *)io->scsiio.kern_data_ptr;
        scsi_u64to8b(lbalen->lba, data->descr[0].addr);
        scsi_ulto4b(MIN(UINT32_MAX, off / be_lun->cbe_lun.blocksize -
            lbalen->lba), data->descr[0].length);
        data->descr[0].status = status;

        ctl_complete_beio(beio);
}

static uint64_t
ctl_be_block_getattr_file(struct ctl_be_block_lun *be_lun, const char *attrname)
{
        struct vattr            vattr;
        struct statfs           statfs;
        uint64_t                val;
        int                     error;

        val = UINT64_MAX;
        if (be_lun->vn == NULL)
                return (val);
        vn_lock(be_lun->vn, LK_SHARED | LK_RETRY);
        if (strcmp(attrname, "blocksused") == 0) {
                error = VOP_GETATTR(be_lun->vn, &vattr, curthread->td_ucred);
                if (error == 0)
                        val = vattr.va_bytes / be_lun->cbe_lun.blocksize;
        }
        if (strcmp(attrname, "blocksavail") == 0 &&
            !VN_IS_DOOMED(be_lun->vn)) {
                error = VFS_STATFS(be_lun->vn->v_mount, &statfs);
                if (error == 0)
                        val = statfs.f_bavail * statfs.f_bsize /
                            be_lun->cbe_lun.blocksize;
        }
        VOP_UNLOCK(be_lun->vn);
        return (val);
}

static void
ctl_be_block_unmap_file(struct ctl_be_block_lun *be_lun,
                        struct ctl_be_block_io *beio)
{
        struct ctl_be_block_filedata *file_data;
        union ctl_io *io;
        struct ctl_ptr_len_flags *ptrlen;
        struct scsi_unmap_desc *buf, *end;
        struct mount *mp;
        off_t off, len;
        int error;

        io = beio->io;
        file_data = &be_lun->backend.file;
        mp = NULL;
        error = 0;

        binuptime(&beio->ds_t0);
        devstat_start_transaction(be_lun->disk_stats, &beio->ds_t0);

        (void)vn_start_write(be_lun->vn, &mp, V_WAIT);
        vn_lock(be_lun->vn, vn_lktype_write(mp, be_lun->vn) | LK_RETRY);
        if (beio->io_offset == -1) {
                beio->io_len = 0;
                ptrlen = (struct ctl_ptr_len_flags *)
                    &io->io_hdr.ctl_private[CTL_PRIV_LBA_LEN];
                buf = (struct scsi_unmap_desc *)ptrlen->ptr;
                end = buf + ptrlen->len / sizeof(*buf);
                for (; buf < end; buf++) {
                        off = (off_t)scsi_8btou64(buf->lba) *
                            be_lun->cbe_lun.blocksize;
                        len = (off_t)scsi_4btoul(buf->length) *
                            be_lun->cbe_lun.blocksize;
                        beio->io_len += len;
                        error = vn_deallocate(be_lun->vn, &off, &len,
                            0, IO_NOMACCHECK | IO_NODELOCKED, file_data->cred,
                            NOCRED);
                        if (error != 0)
                                break;
                }
        } else {
                /* WRITE_SAME */
                off = beio->io_offset;
                len = beio->io_len;
                error = vn_deallocate(be_lun->vn, &off, &len, 0,
                    IO_NOMACCHECK | IO_NODELOCKED, file_data->cred, NOCRED);
        }
        VOP_UNLOCK(be_lun->vn);
        vn_finished_write(mp);

        mtx_lock(&be_lun->io_lock);
        devstat_end_transaction(beio->lun->disk_stats, beio->io_len,
            beio->ds_tag_type, beio->ds_trans_type,
            /*now*/ NULL, /*then*/&beio->ds_t0);
        mtx_unlock(&be_lun->io_lock);

        /*
         * If we got an error, set the sense data to "MEDIUM ERROR" and
         * return the I/O to the user.
         */
        switch (error) {
        case 0:
                ctl_io_set_success(io);
                break;
        case ENOSPC:
        case EDQUOT:
                ctl_io_set_space_alloc_fail(io);
                break;
        case EROFS:
        case EACCES:
                ctl_io_set_hw_write_protected(io);
                break;
        default:
                ctl_be_block_io_error(io, BIO_DELETE, 0);
        }
        ctl_complete_beio(beio);
}

static void
ctl_be_block_dispatch_zvol(struct ctl_be_block_lun *be_lun,
                           struct ctl_be_block_io *beio)
{
        struct ctl_be_lun *cbe_lun = &be_lun->cbe_lun;
        union ctl_io *io;
        struct cdevsw *csw;
        struct cdev *dev;
        struct uio xuio;
        struct iovec *xiovec;
        int error, flags, i, ref;

        DPRINTF("entered\n");

        io = beio->io;
        flags = 0;
        if (ARGS(io)->flags & CTL_LLF_DPO)
                flags |= IO_DIRECT;
        if (beio->bio_cmd == BIO_WRITE && ARGS(io)->flags & CTL_LLF_FUA)
                flags |= IO_SYNC;

        bzero(&xuio, sizeof(xuio));
        if (beio->bio_cmd == BIO_READ) {
                SDT_PROBE0(cbb, , read, file_start);
                xuio.uio_rw = UIO_READ;
        } else {
                SDT_PROBE0(cbb, , write, file_start);
                xuio.uio_rw = UIO_WRITE;
        }
        xuio.uio_offset = beio->io_offset;
        xuio.uio_resid = beio->io_len;
        xuio.uio_segflg = UIO_SYSSPACE;
        xuio.uio_iov = beio->xiovecs;
        xuio.uio_iovcnt = beio->num_segs;
        xuio.uio_td = curthread;

        for (i = 0, xiovec = xuio.uio_iov; i < xuio.uio_iovcnt; i++, xiovec++) {
                xiovec->iov_base = beio->sg_segs[i].addr;
                xiovec->iov_len = beio->sg_segs[i].len;
        }

        binuptime(&beio->ds_t0);
        devstat_start_transaction(beio->lun->disk_stats, &beio->ds_t0);

        csw = devvn_refthread(be_lun->vn, &dev, &ref);
        if (csw) {
                if (beio->bio_cmd == BIO_READ) {
                        if (beio->beio_cont == NULL &&
                            cbe_lun->serseq == CTL_LUN_SERSEQ_SOFT)
                                ctl_serseq_done(io);
                        error = csw->d_read(dev, &xuio, flags);
                } else
                        error = csw->d_write(dev, &xuio, flags);
                dev_relthread(dev, ref);
        } else
                error = ENXIO;

        if (beio->bio_cmd == BIO_READ)
                SDT_PROBE0(cbb, , read, file_done);
        else
                SDT_PROBE0(cbb, , write, file_done);

        mtx_lock(&be_lun->io_lock);
        devstat_end_transaction(beio->lun->disk_stats, beio->io_len,
            beio->ds_tag_type, beio->ds_trans_type,
            /*now*/ NULL, /*then*/&beio->ds_t0);
        mtx_unlock(&be_lun->io_lock);

        /*
         * If we got an error, set the sense data to "MEDIUM ERROR" and
         * return the I/O to the user.
         */
        if (error != 0) {
                if (error == ENOSPC || error == EDQUOT) {
                        ctl_io_set_space_alloc_fail(io);
                } else if (error == EROFS || error == EACCES) {
                        ctl_io_set_hw_write_protected(io);
                } else {
                        ctl_be_block_io_error(io, beio->bio_cmd, 0);
                }
                ctl_complete_beio(beio);
                return;
        }

        /*
         * If this is a write or a verify, we're all done.
         * If this is a read, we can now send the data to the user.
         */
        if ((beio->bio_cmd == BIO_WRITE) ||
            (ARGS(io)->flags & CTL_LLF_VERIFY)) {
                ctl_io_set_success(io);
                ctl_complete_beio(beio);
        } else {
                if ((ARGS(io)->flags & CTL_LLF_READ) &&
                    beio->beio_cont == NULL) {
                        ctl_io_set_success(io);
                        if (cbe_lun->serseq > CTL_LUN_SERSEQ_SOFT)
                                ctl_serseq_done(io);
                }
                ctl_datamove(io);
        }
}

static void
ctl_be_block_gls_zvol(struct ctl_be_block_lun *be_lun,
                        struct ctl_be_block_io *beio)
{
        union ctl_io *io = beio->io;
        struct cdevsw *csw;
        struct cdev *dev;
        struct ctl_lba_len_flags *lbalen = ARGS(io);
        struct scsi_get_lba_status_data *data;
        off_t roff, off;
        int error, ref, status;

        DPRINTF("entered\n");

        CTL_IO_ASSERT(io, SCSI);

        csw = devvn_refthread(be_lun->vn, &dev, &ref);
        if (csw == NULL) {
                status = 0;     /* unknown up to the end */
                off = be_lun->size_bytes;
                goto done;
        }
        off = roff = ((off_t)lbalen->lba) * be_lun->cbe_lun.blocksize;
        error = csw->d_ioctl(dev, FIOSEEKHOLE, (caddr_t)&off, FREAD,
            curthread);
        if (error == 0 && off > roff)
                status = 0;     /* mapped up to off */
        else {
                error = csw->d_ioctl(dev, FIOSEEKDATA, (caddr_t)&off, FREAD,
                    curthread);
                if (error == 0 && off > roff)
                        status = 1;     /* deallocated up to off */
                else {
                        status = 0;     /* unknown up to the end */
                        off = be_lun->size_bytes;
                }
        }
        dev_relthread(dev, ref);

done:
        data = (struct scsi_get_lba_status_data *)io->scsiio.kern_data_ptr;
        scsi_u64to8b(lbalen->lba, data->descr[0].addr);
        scsi_ulto4b(MIN(UINT32_MAX, off / be_lun->cbe_lun.blocksize -
            lbalen->lba), data->descr[0].length);
        data->descr[0].status = status;

        ctl_complete_beio(beio);
}

static void
ctl_be_block_flush_dev(struct ctl_be_block_lun *be_lun,
                       struct ctl_be_block_io *beio)
{
        struct bio *bio;
        struct cdevsw *csw;
        struct cdev *dev;
        int ref;

        DPRINTF("entered\n");

        /* This can't fail, it's a blocking allocation. */
        bio = g_alloc_bio();

        bio->bio_cmd        = BIO_FLUSH;
        bio->bio_offset     = 0;
        bio->bio_data       = 0;
        bio->bio_done       = ctl_be_block_biodone;
        bio->bio_caller1    = beio;
        bio->bio_pblkno     = 0;

        /*
         * We don't need to acquire the LUN lock here, because we are only
         * sending one bio, and so there is no other context to synchronize
         * with.
         */
        beio->num_bios_sent = 1;
        beio->send_complete = 1;

        binuptime(&beio->ds_t0);
        devstat_start_transaction(be_lun->disk_stats, &beio->ds_t0);

        csw = devvn_refthread(be_lun->vn, &dev, &ref);
        if (csw) {
                bio->bio_dev = dev;
                csw->d_strategy(bio);
                dev_relthread(dev, ref);
        } else {
                bio->bio_error = ENXIO;
                ctl_be_block_biodone(bio);
        }
}

static void
ctl_be_block_unmap_dev_range(struct ctl_be_block_lun *be_lun,
                       struct ctl_be_block_io *beio,
                       uint64_t off, uint64_t len, int last)
{
        struct bio *bio;
        uint64_t maxlen;
        struct cdevsw *csw;
        struct cdev *dev;
        int ref;

        csw = devvn_refthread(be_lun->vn, &dev, &ref);
        maxlen = LONG_MAX - (LONG_MAX % be_lun->cbe_lun.blocksize);
        while (len > 0) {
                bio = g_alloc_bio();
                bio->bio_cmd        = BIO_DELETE;
                bio->bio_dev        = dev;
                bio->bio_offset     = off;
                bio->bio_length     = MIN(len, maxlen);
                bio->bio_data       = 0;
                bio->bio_done       = ctl_be_block_biodone;
                bio->bio_caller1    = beio;
                bio->bio_pblkno     = off / be_lun->cbe_lun.blocksize;

                off += bio->bio_length;
                len -= bio->bio_length;

                mtx_lock(&be_lun->io_lock);
                beio->num_bios_sent++;
                if (last && len == 0)
                        beio->send_complete = 1;
                mtx_unlock(&be_lun->io_lock);

                if (csw) {
                        csw->d_strategy(bio);
                } else {
                        bio->bio_error = ENXIO;
                        ctl_be_block_biodone(bio);
                }
        }
        if (csw)
                dev_relthread(dev, ref);
}

static void
ctl_be_block_unmap_dev(struct ctl_be_block_lun *be_lun,
                       struct ctl_be_block_io *beio)
{
        union ctl_io *io;
        struct ctl_ptr_len_flags *ptrlen;
        struct scsi_unmap_desc *buf, *end;
        uint64_t len;

        io = beio->io;

        DPRINTF("entered\n");

        binuptime(&beio->ds_t0);
        devstat_start_transaction(be_lun->disk_stats, &beio->ds_t0);

        if (beio->io_offset == -1) {
                beio->io_len = 0;
                ptrlen = (struct ctl_ptr_len_flags *)&io->io_hdr.ctl_private[CTL_PRIV_LBA_LEN];
                buf = (struct scsi_unmap_desc *)ptrlen->ptr;
                end = buf + ptrlen->len / sizeof(*buf);
                for (; buf < end; buf++) {
                        len = (uint64_t)scsi_4btoul(buf->length) *
                            be_lun->cbe_lun.blocksize;
                        beio->io_len += len;
                        ctl_be_block_unmap_dev_range(be_lun, beio,
                            scsi_8btou64(buf->lba) * be_lun->cbe_lun.blocksize,
                            len, (end - buf < 2) ? TRUE : FALSE);
                }
        } else
                ctl_be_block_unmap_dev_range(be_lun, beio,
                    beio->io_offset, beio->io_len, TRUE);
}

static void
ctl_be_block_dispatch_dev(struct ctl_be_block_lun *be_lun,
                          struct ctl_be_block_io *beio)
{
        TAILQ_HEAD(, bio) queue = TAILQ_HEAD_INITIALIZER(queue);
        struct bio *bio;
        struct cdevsw *csw;
        struct cdev *dev;
        off_t cur_offset;
        int i, max_iosize, ref;

        DPRINTF("entered\n");
        csw = devvn_refthread(be_lun->vn, &dev, &ref);

        /*
         * We have to limit our I/O size to the maximum supported by the
         * backend device.
         */
        if (csw) {
                max_iosize = dev->si_iosize_max;
                if (max_iosize <= 0)
                        max_iosize = DFLTPHYS;
        } else
                max_iosize = maxphys;

        cur_offset = beio->io_offset;
        for (i = 0; i < beio->num_segs; i++) {
                size_t cur_size;
                uint8_t *cur_ptr;

                cur_size = beio->sg_segs[i].len;
                cur_ptr = beio->sg_segs[i].addr;

                while (cur_size > 0) {
                        /* This can't fail, it's a blocking allocation. */
                        bio = g_alloc_bio();

                        KASSERT(bio != NULL, ("g_alloc_bio() failed!\n"));

                        bio->bio_cmd = beio->bio_cmd;
                        bio->bio_dev = dev;
                        bio->bio_caller1 = beio;
                        bio->bio_length = min(cur_size, max_iosize);
                        bio->bio_offset = cur_offset;
                        bio->bio_data = cur_ptr;
                        bio->bio_done = ctl_be_block_biodone;
                        bio->bio_pblkno = cur_offset / be_lun->cbe_lun.blocksize;

                        cur_offset += bio->bio_length;
                        cur_ptr += bio->bio_length;
                        cur_size -= bio->bio_length;

                        TAILQ_INSERT_TAIL(&queue, bio, bio_queue);
                        beio->num_bios_sent++;
                }
        }
        beio->send_complete = 1;
        binuptime(&beio->ds_t0);
        devstat_start_transaction(be_lun->disk_stats, &beio->ds_t0);

        /*
         * Fire off all allocated requests!
         */
        while ((bio = TAILQ_FIRST(&queue)) != NULL) {
                TAILQ_REMOVE(&queue, bio, bio_queue);
                if (csw)
                        csw->d_strategy(bio);
                else {
                        bio->bio_error = ENXIO;
                        ctl_be_block_biodone(bio);
                }
        }
        if (csw)
                dev_relthread(dev, ref);
}

static uint64_t
ctl_be_block_getattr_dev(struct ctl_be_block_lun *be_lun, const char *attrname)
{
        struct diocgattr_arg    arg;
        struct cdevsw *csw;
        struct cdev *dev;
        int error, ref;

        csw = devvn_refthread(be_lun->vn, &dev, &ref);
        if (csw == NULL)
                return (UINT64_MAX);
        strlcpy(arg.name, attrname, sizeof(arg.name));
        arg.len = sizeof(arg.value.off);
        if (csw->d_ioctl) {
                error = csw->d_ioctl(dev, DIOCGATTR, (caddr_t)&arg, FREAD,
                    curthread);
        } else
                error = ENODEV;
        dev_relthread(dev, ref);
        if (error != 0)
                return (UINT64_MAX);
        return (arg.value.off);
}

static void
ctl_be_block_namespace_data(struct ctl_be_block_lun *be_lun,
                            union ctl_io *io)
{
        struct ctl_be_lun *cbe_lun = &be_lun->cbe_lun;
        struct nvme_namespace_data *nsdata;

        nsdata = (struct nvme_namespace_data *)io->nvmeio.kern_data_ptr;
        memset(nsdata, 0, sizeof(*nsdata));
        nsdata->nsze = htole64(be_lun->size_blocks);
        nsdata->ncap = nsdata->nsze;
        nsdata->nuse = nsdata->nsze;
        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);
}

static void
ctl_be_block_nvme_ids(struct ctl_be_block_lun *be_lun,
                      union ctl_io *io)
{
        struct ctl_be_lun *cbe_lun = &be_lun->cbe_lun;

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

static void
ctl_be_block_cw_dispatch_sync(struct ctl_be_block_lun *be_lun,
                            union ctl_io *io)
{
        struct ctl_be_lun *cbe_lun = &be_lun->cbe_lun;
        struct ctl_be_block_io *beio;
        struct ctl_lba_len_flags *lbalen;

        DPRINTF("entered\n");
        beio = (struct ctl_be_block_io *)PRIV(io)->ptr;
        lbalen = (struct ctl_lba_len_flags *)&io->io_hdr.ctl_private[CTL_PRIV_LBA_LEN];

        beio->io_len = lbalen->len * cbe_lun->blocksize;
        beio->io_offset = lbalen->lba * cbe_lun->blocksize;
        beio->io_arg = (lbalen->flags & SSC_IMMED) != 0;
        beio->bio_cmd = BIO_FLUSH;
        beio->ds_trans_type = DEVSTAT_NO_DATA;
        DPRINTF("SYNC\n");
        be_lun->lun_flush(be_lun, beio);
}

static void
ctl_be_block_cw_done_ws(struct ctl_be_block_io *beio)
{
        union ctl_io *io;

        io = beio->io;
        ctl_free_beio(beio);
        if ((io->io_hdr.flags & CTL_FLAG_ABORT) ||
            ((io->io_hdr.status & CTL_STATUS_MASK) != CTL_STATUS_NONE &&
             (io->io_hdr.status & CTL_STATUS_MASK) != CTL_SUCCESS)) {
                ctl_config_write_done(io);
                return;
        }

        ctl_be_block_config_write(io);
}

static void
ctl_be_block_cw_dispatch_ws(struct ctl_be_block_lun *be_lun,
                            union ctl_io *io)
{
        struct ctl_be_block_softc *softc = be_lun->softc;
        struct ctl_be_lun *cbe_lun = &be_lun->cbe_lun;
        struct ctl_be_block_io *beio;
        struct ctl_lba_len_flags *lbalen;
        uint64_t len_left, lba;
        uint32_t pb, pbo, adj;
        int i, seglen;
        uint8_t *buf, *end;

        DPRINTF("entered\n");

        CTL_IO_ASSERT(io, SCSI);

        beio = (struct ctl_be_block_io *)PRIV(io)->ptr;
        lbalen = ARGS(io);

        if (lbalen->flags & ~(SWS_LBDATA | SWS_UNMAP | SWS_ANCHOR | SWS_NDOB) ||
            (lbalen->flags & (SWS_UNMAP | SWS_ANCHOR) && be_lun->unmap == NULL)) {
                ctl_free_beio(beio);
                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 | SWS_ANCHOR)) {
                beio->io_offset = lbalen->lba * cbe_lun->blocksize;
                beio->io_len = (uint64_t)lbalen->len * cbe_lun->blocksize;
                beio->bio_cmd = BIO_DELETE;
                beio->ds_trans_type = DEVSTAT_FREE;

                be_lun->unmap(be_lun, beio);
                return;
        }

        beio->bio_cmd = BIO_WRITE;
        beio->ds_trans_type = DEVSTAT_WRITE;

        DPRINTF("WRITE SAME at LBA %jx len %u\n",
               (uintmax_t)lbalen->lba, lbalen->len);

        pb = cbe_lun->blocksize << be_lun->cbe_lun.pblockexp;
        if (be_lun->cbe_lun.pblockoff > 0)
                pbo = pb - cbe_lun->blocksize * be_lun->cbe_lun.pblockoff;
        else
                pbo = 0;
        len_left = (uint64_t)lbalen->len * cbe_lun->blocksize;
        for (i = 0, lba = 0; i < CTLBLK_MAX_SEGS && len_left > 0; i++) {
                /*
                 * Setup the S/G entry for this chunk.
                 */
                seglen = MIN(CTLBLK_MAX_SEG, len_left);
                if (pb > cbe_lun->blocksize) {
                        adj = ((lbalen->lba + lba) * cbe_lun->blocksize +
                            seglen - pbo) % pb;
                        if (seglen > adj)
                                seglen -= adj;
                        else
                                seglen -= seglen % cbe_lun->blocksize;
                } else
                        seglen -= seglen % cbe_lun->blocksize;
                ctl_alloc_seg(softc, &beio->sg_segs[i], seglen);

                DPRINTF("segment %d addr %p len %zd\n", i,
                        beio->sg_segs[i].addr, beio->sg_segs[i].len);

                beio->num_segs++;
                len_left -= seglen;

                buf = beio->sg_segs[i].addr;
                end = buf + seglen;
                for (; buf < end; buf += cbe_lun->blocksize) {
                        if (lbalen->flags & SWS_NDOB) {
                                memset(buf, 0, cbe_lun->blocksize);
                        } else {
                                memcpy(buf, io->scsiio.kern_data_ptr,
                                    cbe_lun->blocksize);
                        }
                        if (lbalen->flags & SWS_LBDATA)
                                scsi_ulto4b(lbalen->lba + lba, buf);
                        lba++;
                }
        }

        beio->io_offset = lbalen->lba * cbe_lun->blocksize;
        beio->io_len = lba * cbe_lun->blocksize;

        /* We can not do all in one run. Correct and schedule rerun. */
        if (len_left > 0) {
                lbalen->lba += lba;
                lbalen->len -= lba;
                beio->beio_cont = ctl_be_block_cw_done_ws;
        }

        be_lun->dispatch(be_lun, beio);
}

static void
ctl_be_block_cw_dispatch_unmap(struct ctl_be_block_lun *be_lun,
                               union ctl_io *io)
{
        struct ctl_be_block_io *beio;
        struct ctl_ptr_len_flags *ptrlen;

        DPRINTF("entered\n");

        CTL_IO_ASSERT(io, SCSI);

        beio = (struct ctl_be_block_io *)PRIV(io)->ptr;
        ptrlen = (struct ctl_ptr_len_flags *)&io->io_hdr.ctl_private[CTL_PRIV_LBA_LEN];

        if ((ptrlen->flags & ~SU_ANCHOR) != 0 || be_lun->unmap == NULL) {
                ctl_free_beio(beio);
                ctl_set_invalid_field(&io->scsiio,
                                      /*sks_valid*/ 0,
                                      /*command*/ 1,
                                      /*field*/ 0,
                                      /*bit_valid*/ 0,
                                      /*bit*/ 0);
                ctl_config_write_done(io);
                return;
        }

        beio->io_len = 0;
        beio->io_offset = -1;
        beio->bio_cmd = BIO_DELETE;
        beio->ds_trans_type = DEVSTAT_FREE;
        DPRINTF("UNMAP\n");
        be_lun->unmap(be_lun, beio);
}

static void
ctl_be_block_cw_dispatch_flush(struct ctl_be_block_lun *be_lun,
                               union ctl_io *io)
{
        struct ctl_be_block_io *beio;

        DPRINTF("entered\n");
        beio = (struct ctl_be_block_io *)PRIV(io)->ptr;

        beio->io_len = be_lun->size_bytes;
        beio->io_offset = 0;
        beio->io_arg = 1;
        beio->bio_cmd = BIO_FLUSH;
        beio->ds_trans_type = DEVSTAT_NO_DATA;
        DPRINTF("FLUSH\n");
        be_lun->lun_flush(be_lun, beio);
}

static void
ctl_be_block_cw_dispatch_wu(struct ctl_be_block_lun *be_lun,
                            union ctl_io *io)
{
        struct ctl_be_lun *cbe_lun = &be_lun->cbe_lun;
        struct ctl_be_block_io *beio;
        struct ctl_lba_len_flags *lbalen;

        CTL_IO_ASSERT(io, NVME);

        beio = (struct ctl_be_block_io *)PRIV(io)->ptr;
        lbalen = ARGS(io);

        /*
         * XXX: Not quite right as reads will return zeroes rather
         * than failing.
         */
        beio->io_offset = lbalen->lba * cbe_lun->blocksize;
        beio->io_len = (uint64_t)lbalen->len * cbe_lun->blocksize;
        beio->bio_cmd = BIO_DELETE;
        beio->ds_trans_type = DEVSTAT_FREE;

        be_lun->unmap(be_lun, beio);
}

static void
ctl_be_block_cw_dispatch_wz(struct ctl_be_block_lun *be_lun,
                            union ctl_io *io)
{
        struct ctl_be_block_softc *softc = be_lun->softc;
        struct ctl_be_lun *cbe_lun = &be_lun->cbe_lun;
        struct ctl_be_block_io *beio;
        struct ctl_lba_len_flags *lbalen;
        uint64_t len_left, lba;
        uint32_t pb, pbo, adj;
        int i, seglen;

        DPRINTF("entered\n");

        CTL_IO_ASSERT(io, NVME);

        beio = (struct ctl_be_block_io *)PRIV(io)->ptr;
        lbalen = ARGS(io);

        if ((le32toh(io->nvmeio.cmd.cdw12) & (1U << 25)) != 0 &&
            be_lun->unmap != NULL) {
                beio->io_offset = lbalen->lba * cbe_lun->blocksize;
                beio->io_len = (uint64_t)lbalen->len * cbe_lun->blocksize;
                beio->bio_cmd = BIO_DELETE;
                beio->ds_trans_type = DEVSTAT_FREE;

                be_lun->unmap(be_lun, beio);
                return;
        }

        beio->bio_cmd = BIO_WRITE;
        beio->ds_trans_type = DEVSTAT_WRITE;

        DPRINTF("WRITE ZEROES at LBA %jx len %u\n",
               (uintmax_t)lbalen->lba, lbalen->len);

        pb = cbe_lun->blocksize << be_lun->cbe_lun.pblockexp;
        if (be_lun->cbe_lun.pblockoff > 0)
                pbo = pb - cbe_lun->blocksize * be_lun->cbe_lun.pblockoff;
        else
                pbo = 0;
        len_left = (uint64_t)lbalen->len * cbe_lun->blocksize;
        for (i = 0, lba = 0; i < CTLBLK_MAX_SEGS && len_left > 0; i++) {
                /*
                 * Setup the S/G entry for this chunk.
                 */
                seglen = MIN(CTLBLK_MAX_SEG, len_left);
                if (pb > cbe_lun->blocksize) {
                        adj = ((lbalen->lba + lba) * cbe_lun->blocksize +
                            seglen - pbo) % pb;
                        if (seglen > adj)
                                seglen -= adj;
                        else
                                seglen -= seglen % cbe_lun->blocksize;
                } else
                        seglen -= seglen % cbe_lun->blocksize;
                ctl_alloc_seg(softc, &beio->sg_segs[i], seglen);

                DPRINTF("segment %d addr %p len %zd\n", i,
                        beio->sg_segs[i].addr, beio->sg_segs[i].len);

                beio->num_segs++;
                len_left -= seglen;

                memset(beio->sg_segs[i].addr, 0, seglen);
                lba += seglen / cbe_lun->blocksize;
        }

        beio->io_offset = lbalen->lba * cbe_lun->blocksize;
        beio->io_len = lba * cbe_lun->blocksize;

        /* We can not do all in one run. Correct and schedule rerun. */
        if (len_left > 0) {
                lbalen->lba += lba;
                lbalen->len -= lba;
                beio->beio_cont = ctl_be_block_cw_done_ws;
        }

        be_lun->dispatch(be_lun, beio);
}

static void
ctl_be_block_cw_dispatch_dsm(struct ctl_be_block_lun *be_lun,
                             union ctl_io *io)
{
        struct ctl_be_lun *cbe_lun = &be_lun->cbe_lun;
        struct ctl_be_block_io *beio;
        struct nvme_dsm_range *r;
        uint64_t lba;
        uint32_t num_blocks;
        u_int i, ranges;

        CTL_IO_ASSERT(io, NVME);

        beio = (struct ctl_be_block_io *)PRIV(io)->ptr;

        if (be_lun->unmap == NULL) {
                ctl_free_beio(beio);
                ctl_nvme_set_success(&io->nvmeio);
                ctl_config_write_done(io);
                return;
        }

        ranges = le32toh(io->nvmeio.cmd.cdw10) & 0xff;
        r = (struct nvme_dsm_range *)io->nvmeio.kern_data_ptr;

        /* Find the next range to delete. */
        for (i = DSM_RANGE(io); i < ranges; i++) {
                if ((le32toh(r[i].attributes) & (1U << 2)) != 0)
                        break;
        }

        /* If no range to delete, complete the operation. */
        if (i == ranges) {
                ctl_free_beio(beio);
                ctl_nvme_set_success(&io->nvmeio);
                ctl_config_write_done(io);
                return;
        }

        /* If this is not the last range, request a rerun after this range. */
        if (i + 1 < ranges) {
                DSM_RANGE(io) = i + 1;
                beio->beio_cont = ctl_be_block_cw_done_ws;
        }

        lba = le64toh(r[i].starting_lba);
        num_blocks = le32toh(r[i].length);

        beio->io_offset = lba * cbe_lun->blocksize;
        beio->io_len = (uint64_t)num_blocks * cbe_lun->blocksize;
        beio->bio_cmd = BIO_DELETE;
        beio->ds_trans_type = DEVSTAT_FREE;

        be_lun->unmap(be_lun, beio);
}

static void
ctl_be_block_scsi_cr_done(struct ctl_be_block_io *beio)
{
        union ctl_io *io;

        io = beio->io;
        ctl_free_beio(beio);
        ctl_config_read_done(io);
}

static void
ctl_be_block_scsi_cr_dispatch(struct ctl_be_block_lun *be_lun,
                              union ctl_io *io)
{
        struct ctl_be_block_io *beio;
        struct ctl_be_block_softc *softc;

        DPRINTF("entered\n");

        softc = be_lun->softc;
        beio = ctl_alloc_beio(softc);
        beio->io = io;
        beio->lun = be_lun;
        beio->beio_cont = ctl_be_block_scsi_cr_done;
        PRIV(io)->ptr = (void *)beio;

        switch (io->scsiio.cdb[0]) {
        case SERVICE_ACTION_IN:         /* GET LBA STATUS */
                beio->bio_cmd = -1;
                beio->ds_trans_type = DEVSTAT_NO_DATA;
                beio->ds_tag_type = DEVSTAT_TAG_ORDERED;
                beio->io_len = 0;
                if (be_lun->get_lba_status)
                        be_lun->get_lba_status(be_lun, beio);
                else
                        ctl_be_block_scsi_cr_done(beio);
                break;
        default:
                panic("Unhandled CDB type %#x", io->scsiio.cdb[0]);
                break;
        }
}

static void
ctl_be_block_nvme_cr_dispatch(struct ctl_be_block_lun *be_lun,
                              union ctl_io *io)
{
        uint8_t cns;

        DPRINTF("entered\n");

        MPASS(io->nvmeio.cmd.opc == NVME_OPC_IDENTIFY);

        cns = le32toh(io->nvmeio.cmd.cdw10) & 0xff;
        switch (cns) {
        case 0:
                ctl_be_block_namespace_data(be_lun, io);
                break;
        case 3:
                ctl_be_block_nvme_ids(be_lun, io);
                break;
        default:
                __assert_unreachable();
        }
}

static void
ctl_be_block_cr_dispatch(struct ctl_be_block_lun *be_lun,
                         union ctl_io *io)
{
        switch (io->io_hdr.io_type) {
        case CTL_IO_SCSI:
                ctl_be_block_scsi_cr_dispatch(be_lun, io);
                break;
        case CTL_IO_NVME_ADMIN:
                ctl_be_block_nvme_cr_dispatch(be_lun, io);
                break;
        default:
                __assert_unreachable();
        }
}

static void
ctl_be_block_cw_done(struct ctl_be_block_io *beio)
{
        union ctl_io *io;

        io = beio->io;
        ctl_free_beio(beio);
        ctl_config_write_done(io);
}

static void
ctl_be_block_scsi_cw_dispatch(struct ctl_be_block_lun *be_lun,
                              union ctl_io *io)
{
        struct ctl_be_block_io *beio;

        DPRINTF("entered\n");

        beio = (struct ctl_be_block_io *)PRIV(io)->ptr;

        switch (io->scsiio.tag_type) {
        case CTL_TAG_ORDERED:
                beio->ds_tag_type = DEVSTAT_TAG_ORDERED;
                break;
        case CTL_TAG_HEAD_OF_QUEUE:
                beio->ds_tag_type = DEVSTAT_TAG_HEAD;
                break;
        case CTL_TAG_UNTAGGED:
        case CTL_TAG_SIMPLE:
        case CTL_TAG_ACA:
        default:
                beio->ds_tag_type = DEVSTAT_TAG_SIMPLE;
                break;
        }

        switch (io->scsiio.cdb[0]) {
        case SYNCHRONIZE_CACHE:
        case SYNCHRONIZE_CACHE_16:
                ctl_be_block_cw_dispatch_sync(be_lun, io);
                break;
        case WRITE_SAME_10:
        case WRITE_SAME_16:
                ctl_be_block_cw_dispatch_ws(be_lun, io);
                break;
        case UNMAP:
                ctl_be_block_cw_dispatch_unmap(be_lun, io);
                break;
        default:
                panic("Unhandled CDB type %#x", io->scsiio.cdb[0]);
                break;
        }
}

static void
ctl_be_block_nvme_cw_dispatch(struct ctl_be_block_lun *be_lun,
                              union ctl_io *io)
{
        struct ctl_be_block_io *beio;

        DPRINTF("entered\n");

        beio = (struct ctl_be_block_io *)PRIV(io)->ptr;
        beio->ds_tag_type = DEVSTAT_TAG_SIMPLE;

        switch (io->nvmeio.cmd.opc) {
        case NVME_OPC_FLUSH:
                ctl_be_block_cw_dispatch_flush(be_lun, io);
                break;
        case NVME_OPC_WRITE_UNCORRECTABLE:
                ctl_be_block_cw_dispatch_wu(be_lun, io);
                break;
        case NVME_OPC_WRITE_ZEROES:
                ctl_be_block_cw_dispatch_wz(be_lun, io);
                break;
        case NVME_OPC_DATASET_MANAGEMENT:
                ctl_be_block_cw_dispatch_dsm(be_lun, io);
                break;
        default:
                __assert_unreachable();
        }
}

static void
ctl_be_block_cw_dispatch(struct ctl_be_block_lun *be_lun,
                         union ctl_io *io)
{
        struct ctl_be_block_io *beio;
        struct ctl_be_block_softc *softc;

        softc = be_lun->softc;
        beio = ctl_alloc_beio(softc);
        beio->io = io;
        beio->lun = be_lun;
        beio->beio_cont = ctl_be_block_cw_done;
        PRIV(io)->ptr = (void *)beio;

        switch (io->io_hdr.io_type) {
        case CTL_IO_SCSI:
                ctl_be_block_scsi_cw_dispatch(be_lun, io);
                break;
        case CTL_IO_NVME:
                ctl_be_block_nvme_cw_dispatch(be_lun, io);
                break;
        default:
                __assert_unreachable();
        }
}

SDT_PROBE_DEFINE1(cbb, , read, start, "uint64_t");
SDT_PROBE_DEFINE1(cbb, , write, start, "uint64_t");
SDT_PROBE_DEFINE1(cbb, , read, alloc_done, "uint64_t");
SDT_PROBE_DEFINE1(cbb, , write, alloc_done, "uint64_t");

static void
ctl_be_block_next(struct ctl_be_block_io *beio)
{
        struct ctl_be_block_lun *be_lun;
        union ctl_io *io;

        io = beio->io;
        be_lun = beio->lun;
        ctl_free_beio(beio);
        if ((io->io_hdr.flags & CTL_FLAG_ABORT) ||
            ((io->io_hdr.status & CTL_STATUS_MASK) != CTL_STATUS_NONE &&
             (io->io_hdr.status & CTL_STATUS_MASK) != CTL_SUCCESS)) {
                ctl_data_submit_done(io);
                return;
        }

        io->io_hdr.status &= ~CTL_STATUS_MASK;
        io->io_hdr.status |= CTL_STATUS_NONE;

        mtx_lock(&be_lun->queue_lock);
        STAILQ_INSERT_TAIL(&be_lun->input_queue, &io->io_hdr, links);
        mtx_unlock(&be_lun->queue_lock);
        taskqueue_enqueue(be_lun->io_taskqueue, &be_lun->io_task);
}

static void
ctl_be_block_dispatch(struct ctl_be_block_lun *be_lun,
                           union ctl_io *io)
{
        struct ctl_be_lun *cbe_lun = &be_lun->cbe_lun;
        struct ctl_be_block_io *beio;
        struct ctl_be_block_softc *softc;
        struct ctl_lba_len_flags *lbalen;
        struct ctl_ptr_len_flags *bptrlen;
        uint64_t len_left, lbas;
        int i;

        softc = be_lun->softc;

        DPRINTF("entered\n");

        lbalen = ARGS(io);
        if (lbalen->flags & CTL_LLF_WRITE) {
                SDT_PROBE0(cbb, , write, start);
        } else {
                SDT_PROBE0(cbb, , read, start);
        }

        beio = ctl_alloc_beio(softc);
        beio->io = io;
        beio->lun = be_lun;
        bptrlen = PRIV(io);
        bptrlen->ptr = (void *)beio;

        switch (io->io_hdr.io_type) {
        case CTL_IO_SCSI:
                switch (io->scsiio.tag_type) {
                case CTL_TAG_ORDERED:
                        beio->ds_tag_type = DEVSTAT_TAG_ORDERED;
                        break;
                case CTL_TAG_HEAD_OF_QUEUE:
                        beio->ds_tag_type = DEVSTAT_TAG_HEAD;
                        break;
                case CTL_TAG_UNTAGGED:
                case CTL_TAG_SIMPLE:
                case CTL_TAG_ACA:
                default:
                        beio->ds_tag_type = DEVSTAT_TAG_SIMPLE;
                        break;
                }
                break;
        case CTL_IO_NVME:
                beio->ds_tag_type = DEVSTAT_TAG_SIMPLE;
                break;
        default:
                __assert_unreachable();
        }

        if (lbalen->flags & CTL_LLF_WRITE) {
                beio->bio_cmd = BIO_WRITE;
                beio->ds_trans_type = DEVSTAT_WRITE;
        } else {
                beio->bio_cmd = BIO_READ;
                beio->ds_trans_type = DEVSTAT_READ;
        }

        DPRINTF("%s at LBA %jx len %u @%ju\n",
               (beio->bio_cmd == BIO_READ) ? "READ" : "WRITE",
               (uintmax_t)lbalen->lba, lbalen->len, bptrlen->len);
        lbas = CTLBLK_MAX_IO_SIZE;
        if (lbalen->flags & CTL_LLF_COMPARE) {
                beio->two_sglists = 1;
                lbas /= 2;
        }
        lbas = MIN(lbalen->len - bptrlen->len, lbas / cbe_lun->blocksize);
        beio->io_offset = (lbalen->lba + bptrlen->len) * cbe_lun->blocksize;
        beio->io_len = lbas * cbe_lun->blocksize;
        bptrlen->len += lbas;

        for (i = 0, len_left = beio->io_len; len_left > 0; i++) {
                KASSERT(i < CTLBLK_MAX_SEGS, ("Too many segs (%d >= %d)",
                    i, CTLBLK_MAX_SEGS));

                /*
                 * Setup the S/G entry for this chunk.
                 */
                ctl_alloc_seg(softc, &beio->sg_segs[i],
                    MIN(CTLBLK_MAX_SEG, len_left));

                DPRINTF("segment %d addr %p len %zd\n", i,
                        beio->sg_segs[i].addr, beio->sg_segs[i].len);

                /* Set up second segment for compare operation. */
                if (beio->two_sglists) {
                        ctl_alloc_seg(softc,
                            &beio->sg_segs[i + CTLBLK_HALF_SEGS],
                            beio->sg_segs[i].len);
                }

                beio->num_segs++;
                len_left -= beio->sg_segs[i].len;
        }
        if (bptrlen->len < lbalen->len)
                beio->beio_cont = ctl_be_block_next;
        ctl_set_be_move_done(io, ctl_be_block_move_done);
        /* For compare we have separate S/G lists for read and datamove. */
        if (beio->two_sglists)
                ctl_set_kern_data_ptr(io, &beio->sg_segs[CTLBLK_HALF_SEGS]);
        else
                ctl_set_kern_data_ptr(io, beio->sg_segs);
        ctl_set_kern_data_len(io, beio->io_len);
        ctl_set_kern_sg_entries(io, beio->num_segs);
        ctl_set_kern_data_ref(io, ctl_refcnt_beio);
        ctl_set_kern_data_arg(io, beio);
        io->io_hdr.flags |= CTL_FLAG_ALLOCATED;

        /*
         * For the read case, we need to read the data into our buffers and
         * then we can send it back to the user.  For the write case, we
         * need to get the data from the user first.
         */
        if (beio->bio_cmd == BIO_READ) {
                SDT_PROBE0(cbb, , read, alloc_done);
                be_lun->dispatch(be_lun, beio);
        } else {
                SDT_PROBE0(cbb, , write, alloc_done);
                ctl_datamove(io);
        }
}

static void
ctl_be_block_worker(void *context, int pending)
{
        struct ctl_be_block_lun *be_lun = (struct ctl_be_block_lun *)context;
        struct ctl_be_lun *cbe_lun = &be_lun->cbe_lun;
        union ctl_io *io;
        struct ctl_be_block_io *beio;

        DPRINTF("entered\n");
        /*
         * Fetch and process I/Os from all queues.  If we detect LUN
         * CTL_LUN_FLAG_NO_MEDIA status here -- it is result of a race,
         * so make response maximally opaque to not confuse initiator.
         */
        for (;;) {
                mtx_lock(&be_lun->queue_lock);
                io = (union ctl_io *)STAILQ_FIRST(&be_lun->datamove_queue);
                if (io != NULL) {
                        DPRINTF("datamove queue\n");
                        STAILQ_REMOVE_HEAD(&be_lun->datamove_queue, links);
                        mtx_unlock(&be_lun->queue_lock);
                        beio = (struct ctl_be_block_io *)PRIV(io)->ptr;
                        if (cbe_lun->flags & CTL_LUN_FLAG_NO_MEDIA) {
                                ctl_io_set_busy(io);
                                ctl_complete_beio(beio);
                                continue;
                        }
                        be_lun->dispatch(be_lun, beio);
                        continue;
                }
                io = (union ctl_io *)STAILQ_FIRST(&be_lun->config_write_queue);
                if (io != NULL) {
                        DPRINTF("config write queue\n");
                        STAILQ_REMOVE_HEAD(&be_lun->config_write_queue, links);
                        mtx_unlock(&be_lun->queue_lock);
                        if (cbe_lun->flags & CTL_LUN_FLAG_NO_MEDIA) {
                                ctl_io_set_busy(io);
                                ctl_config_write_done(io);
                                continue;
                        }
                        ctl_be_block_cw_dispatch(be_lun, io);
                        continue;
                }
                io = (union ctl_io *)STAILQ_FIRST(&be_lun->config_read_queue);
                if (io != NULL) {
                        DPRINTF("config read queue\n");
                        STAILQ_REMOVE_HEAD(&be_lun->config_read_queue, links);
                        mtx_unlock(&be_lun->queue_lock);
                        if (cbe_lun->flags & CTL_LUN_FLAG_NO_MEDIA) {
                                ctl_io_set_busy(io);
                                ctl_config_read_done(io);
                                continue;
                        }
                        ctl_be_block_cr_dispatch(be_lun, io);
                        continue;
                }
                io = (union ctl_io *)STAILQ_FIRST(&be_lun->input_queue);
                if (io != NULL) {
                        DPRINTF("input queue\n");
                        STAILQ_REMOVE_HEAD(&be_lun->input_queue, links);
                        mtx_unlock(&be_lun->queue_lock);
                        if (cbe_lun->flags & CTL_LUN_FLAG_NO_MEDIA) {
                                ctl_io_set_busy(io);
                                ctl_data_submit_done(io);
                                continue;
                        }
                        ctl_be_block_dispatch(be_lun, io);
                        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.
                 */
                mtx_unlock(&be_lun->queue_lock);
                break;
        }
}

/*
 * Entry point from CTL to the backend for I/O.  We queue everything to a
 * work thread, so this just puts the I/O on a queue and wakes up the
 * thread.
 */
static int
ctl_be_block_submit(union ctl_io *io)
{
        struct ctl_be_block_lun *be_lun;

        DPRINTF("entered\n");

        be_lun = (struct ctl_be_block_lun *)CTL_BACKEND_LUN(io);

        CTL_IO_ASSERT(io, SCSI, NVME);

        PRIV(io)->len = 0;

        mtx_lock(&be_lun->queue_lock);
        STAILQ_INSERT_TAIL(&be_lun->input_queue, &io->io_hdr, links);
        mtx_unlock(&be_lun->queue_lock);
        taskqueue_enqueue(be_lun->io_taskqueue, &be_lun->io_task);

        return (CTL_RETVAL_COMPLETE);
}

static int
ctl_be_block_ioctl(struct cdev *dev, u_long cmd, caddr_t addr,
                        int flag, struct thread *td)
{
        struct ctl_be_block_softc *softc = &backend_block_softc;
        int error;

        error = 0;
        switch (cmd) {
        case CTL_LUN_REQ: {
                struct ctl_lun_req *lun_req;

                lun_req = (struct ctl_lun_req *)addr;

                switch (lun_req->reqtype) {
                case CTL_LUNREQ_CREATE:
                        error = ctl_be_block_create(softc, lun_req);
                        break;
                case CTL_LUNREQ_RM:
                        error = ctl_be_block_rm(softc, lun_req);
                        break;
                case CTL_LUNREQ_MODIFY:
                        error = ctl_be_block_modify(softc, lun_req);
                        break;
                default:
                        lun_req->status = CTL_LUN_ERROR;
                        snprintf(lun_req->error_str, sizeof(lun_req->error_str),
                                 "invalid LUN request type %d",
                                 lun_req->reqtype);
                        break;
                }
                break;
        }
        default:
                error = ENOTTY;
                break;
        }

        return (error);
}

static int
ctl_be_block_open_file(struct ctl_be_block_lun *be_lun, struct ctl_lun_req *req)
{
        struct ctl_be_lun *cbe_lun;
        struct ctl_be_block_filedata *file_data;
        struct ctl_lun_create_params *params;
        const char                   *value;
        struct vattr                  vattr;
        off_t                         ps, pss, po, pos, us, uss, uo, uos;
        int                           error;
        long                          pconf;

        cbe_lun = &be_lun->cbe_lun;
        file_data = &be_lun->backend.file;
        params = &be_lun->params;

        be_lun->dev_type = CTL_BE_BLOCK_FILE;
        be_lun->dispatch = ctl_be_block_dispatch_file;
        be_lun->lun_flush = ctl_be_block_flush_file;
        be_lun->get_lba_status = ctl_be_block_gls_file;
        be_lun->getattr = ctl_be_block_getattr_file;
        be_lun->unmap = ctl_be_block_unmap_file;
        cbe_lun->flags &= ~CTL_LUN_FLAG_UNMAP;

        error = VOP_GETATTR(be_lun->vn, &vattr, curthread->td_ucred);
        if (error != 0) {
                snprintf(req->error_str, sizeof(req->error_str),
                         "error calling VOP_GETATTR() for file %s",
                         be_lun->dev_path);
                return (error);
        }

        error = VOP_PATHCONF(be_lun->vn, _PC_DEALLOC_PRESENT, &pconf);
        if (error != 0) {
                snprintf(req->error_str, sizeof(req->error_str),
                    "error calling VOP_PATHCONF() for file %s",
                    be_lun->dev_path);
                return (error);
        }
        if (pconf == 1)
                cbe_lun->flags |= CTL_LUN_FLAG_UNMAP;

        file_data->cred = crhold(curthread->td_ucred);
        if (params->lun_size_bytes != 0)
                be_lun->size_bytes = params->lun_size_bytes;
        else
                be_lun->size_bytes = vattr.va_size;

        /*
         * For files we can use any logical block size.  Prefer 512 bytes
         * for compatibility reasons.  If file's vattr.va_blocksize
         * (preferred I/O block size) is bigger and multiple to chosen
         * logical block size -- report it as physical block size.
         */
        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->size_blocks = be_lun->size_bytes / cbe_lun->blocksize;
        cbe_lun->maxlba = (be_lun->size_blocks == 0) ?
            0 : (be_lun->size_blocks - 1);

        us = ps = vattr.va_blocksize;
        uo = po = 0;

        value = dnvlist_get_string(cbe_lun->options, "pblocksize", NULL);
        if (value != NULL)
                ctl_expand_number(value, &ps);
        value = dnvlist_get_string(cbe_lun->options, "pblockoffset", NULL);
        if (value != NULL)
                ctl_expand_number(value, &po);
        pss = ps / cbe_lun->blocksize;
        pos = po / cbe_lun->blocksize;
        if ((pss > 0) && (pss * cbe_lun->blocksize == ps) && (pss >= pos) &&
            ((pss & (pss - 1)) == 0) && (pos * cbe_lun->blocksize == po)) {
                cbe_lun->pblockexp = fls(pss) - 1;
                cbe_lun->pblockoff = (pss - pos) % pss;
        }

        value = dnvlist_get_string(cbe_lun->options, "ublocksize", NULL);
        if (value != NULL)
                ctl_expand_number(value, &us);
        value = dnvlist_get_string(cbe_lun->options, "ublockoffset", NULL);
        if (value != NULL)
                ctl_expand_number(value, &uo);
        uss = us / cbe_lun->blocksize;
        uos = uo / cbe_lun->blocksize;
        if ((uss > 0) && (uss * cbe_lun->blocksize == us) && (uss >= uos) &&
            ((uss & (uss - 1)) == 0) && (uos * cbe_lun->blocksize == uo)) {
                cbe_lun->ublockexp = fls(uss) - 1;
                cbe_lun->ublockoff = (uss - uos) % uss;
        }

        /*
         * Sanity check.  The media size has to be at least one
         * sector long.
         */
        if (be_lun->size_bytes < cbe_lun->blocksize) {
                error = EINVAL;
                snprintf(req->error_str, sizeof(req->error_str),
                         "file %s size %ju < block size %u", be_lun->dev_path,
                         (uintmax_t)be_lun->size_bytes, cbe_lun->blocksize);
        }

        cbe_lun->opttxferlen = CTLBLK_MAX_IO_SIZE / cbe_lun->blocksize;
        return (error);
}

static int
ctl_be_block_open_dev(struct ctl_be_block_lun *be_lun, struct ctl_lun_req *req)
{
        struct ctl_be_lun *cbe_lun = &be_lun->cbe_lun;
        struct ctl_lun_create_params *params;
        struct cdevsw                *csw;
        struct cdev                  *dev;
        const char                   *value;
        int                           error, atomic, maxio, ref, unmap, tmp;
        off_t                         ps, pss, po, pos, us, uss, uo, uos, otmp;

        params = &be_lun->params;

        be_lun->dev_type = CTL_BE_BLOCK_DEV;
        csw = devvn_refthread(be_lun->vn, &dev, &ref);
        if (csw == NULL)
                return (ENXIO);
        if (strcmp(csw->d_name, "zvol") == 0) {
                be_lun->dispatch = ctl_be_block_dispatch_zvol;
                be_lun->get_lba_status = ctl_be_block_gls_zvol;
                atomic = maxio = CTLBLK_MAX_IO_SIZE;
        } else {
                be_lun->dispatch = ctl_be_block_dispatch_dev;
                be_lun->get_lba_status = NULL;
                atomic = 0;
                maxio = dev->si_iosize_max;
                if (maxio <= 0)
                        maxio = DFLTPHYS;
                if (maxio > CTLBLK_MAX_SEG)
                        maxio = CTLBLK_MAX_SEG;
        }
        be_lun->lun_flush = ctl_be_block_flush_dev;
        be_lun->getattr = ctl_be_block_getattr_dev;
        be_lun->unmap = ctl_be_block_unmap_dev;

        if (!csw->d_ioctl) {
                dev_relthread(dev, ref);
                snprintf(req->error_str, sizeof(req->error_str),
                         "no d_ioctl for device %s!", be_lun->dev_path);
                return (ENODEV);
        }

        error = csw->d_ioctl(dev, DIOCGSECTORSIZE, (caddr_t)&tmp, FREAD,
                               curthread);
        if (error) {
                dev_relthread(dev, ref);
                snprintf(req->error_str, sizeof(req->error_str),
                         "error %d returned for DIOCGSECTORSIZE ioctl "
                         "on %s!", error, be_lun->dev_path);
                return (error);
        }

        /*
         * If the user has asked for a blocksize that is greater than the
         * backing device's blocksize, we can do it only if the blocksize
         * the user is asking for is an even multiple of the underlying 
         * device's blocksize.
         */
        if ((params->blocksize_bytes != 0) &&
            (params->blocksize_bytes >= tmp)) {
                if (params->blocksize_bytes % tmp == 0) {
                        cbe_lun->blocksize = params->blocksize_bytes;
                } else {
                        dev_relthread(dev, ref);
                        snprintf(req->error_str, sizeof(req->error_str),
                                 "requested blocksize %u is not an even "
                                 "multiple of backing device blocksize %u",
                                 params->blocksize_bytes, tmp);
                        return (EINVAL);
                }
        } else if (params->blocksize_bytes != 0) {
                dev_relthread(dev, ref);
                snprintf(req->error_str, sizeof(req->error_str),
                         "requested blocksize %u < backing device "
                         "blocksize %u", params->blocksize_bytes, tmp);
                return (EINVAL);
        } else if (cbe_lun->lun_type == T_CDROM)
                cbe_lun->blocksize = MAX(tmp, 2048);
        else
                cbe_lun->blocksize = tmp;

        error = csw->d_ioctl(dev, DIOCGMEDIASIZE, (caddr_t)&otmp, FREAD,
                             curthread);
        if (error) {
                dev_relthread(dev, ref);
                snprintf(req->error_str, sizeof(req->error_str),
                         "error %d returned for DIOCGMEDIASIZE "
                         " ioctl on %s!", error,
                         be_lun->dev_path);
                return (error);
        }

        if (params->lun_size_bytes != 0) {
                if (params->lun_size_bytes > otmp) {
                        dev_relthread(dev, ref);
                        snprintf(req->error_str, sizeof(req->error_str),
                                 "requested LUN size %ju > backing device "
                                 "size %ju",
                                 (uintmax_t)params->lun_size_bytes,
                                 (uintmax_t)otmp);
                        return (EINVAL);
                }

                be_lun->size_bytes = params->lun_size_bytes;
        } else
                be_lun->size_bytes = otmp;
        be_lun->size_blocks = be_lun->size_bytes / cbe_lun->blocksize;
        cbe_lun->maxlba = (be_lun->size_blocks == 0) ?
            0 : (be_lun->size_blocks - 1);

        error = csw->d_ioctl(dev, DIOCGSTRIPESIZE, (caddr_t)&ps, FREAD,
            curthread);
        if (error)
                ps = po = 0;
        else {
                error = csw->d_ioctl(dev, DIOCGSTRIPEOFFSET, (caddr_t)&po,
                    FREAD, curthread);
                if (error)
                        po = 0;
        }
        us = ps;
        uo = po;

        value = dnvlist_get_string(cbe_lun->options, "pblocksize", NULL);
        if (value != NULL)
                ctl_expand_number(value, &ps);
        value = dnvlist_get_string(cbe_lun->options, "pblockoffset", NULL);
        if (value != NULL)
                ctl_expand_number(value, &po);
        pss = ps / cbe_lun->blocksize;
        pos = po / cbe_lun->blocksize;
        if ((pss > 0) && (pss * cbe_lun->blocksize == ps) && (pss >= pos) &&
            ((pss & (pss - 1)) == 0) && (pos * cbe_lun->blocksize == po)) {
                cbe_lun->pblockexp = fls(pss) - 1;
                cbe_lun->pblockoff = (pss - pos) % pss;
        }

        value = dnvlist_get_string(cbe_lun->options, "ublocksize", NULL);
        if (value != NULL)
                ctl_expand_number(value, &us);
        value = dnvlist_get_string(cbe_lun->options, "ublockoffset", NULL);
        if (value != NULL)
                ctl_expand_number(value, &uo);
        uss = us / cbe_lun->blocksize;
        uos = uo / cbe_lun->blocksize;
        if ((uss > 0) && (uss * cbe_lun->blocksize == us) && (uss >= uos) &&
            ((uss & (uss - 1)) == 0) && (uos * cbe_lun->blocksize == uo)) {
                cbe_lun->ublockexp = fls(uss) - 1;
                cbe_lun->ublockoff = (uss - uos) % uss;
        }

        cbe_lun->atomicblock = atomic / cbe_lun->blocksize;
        cbe_lun->opttxferlen = maxio / cbe_lun->blocksize;

        if (be_lun->dispatch == ctl_be_block_dispatch_zvol) {
                unmap = 1;
        } else {
                struct diocgattr_arg    arg;

                strlcpy(arg.name, "GEOM::candelete", sizeof(arg.name));
                arg.len = sizeof(arg.value.i);
                error = csw->d_ioctl(dev, DIOCGATTR, (caddr_t)&arg, FREAD,
                    curthread);
                unmap = (error == 0) ? arg.value.i : 0;
        }
        value = dnvlist_get_string(cbe_lun->options, "unmap", NULL);
        if (value != NULL)
                unmap = (strcmp(value, "on") == 0);
        if (unmap)
                cbe_lun->flags |= CTL_LUN_FLAG_UNMAP;
        else
                cbe_lun->flags &= ~CTL_LUN_FLAG_UNMAP;

        dev_relthread(dev, ref);
        return (0);
}

static int
ctl_be_block_close(struct ctl_be_block_lun *be_lun)
{
        struct ctl_be_lun *cbe_lun = &be_lun->cbe_lun;
        int flags;

        if (be_lun->vn) {
                flags = FREAD;
                if ((cbe_lun->flags & CTL_LUN_FLAG_READONLY) == 0)
                        flags |= FWRITE;
                (void)vn_close(be_lun->vn, flags, NOCRED, curthread);
                be_lun->vn = NULL;

                switch (be_lun->dev_type) {
                case CTL_BE_BLOCK_DEV:
                        break;
                case CTL_BE_BLOCK_FILE:
                        if (be_lun->backend.file.cred != NULL) {
                                crfree(be_lun->backend.file.cred);
                                be_lun->backend.file.cred = NULL;
                        }
                        break;
                case CTL_BE_BLOCK_NONE:
                        break;
                default:
                        panic("Unexpected backend type %d", be_lun->dev_type);
                        break;
                }
                be_lun->dev_type = CTL_BE_BLOCK_NONE;
        }
        return (0);
}

static int
ctl_be_block_open(struct ctl_be_block_lun *be_lun, struct ctl_lun_req *req)
{
        struct ctl_be_lun *cbe_lun = &be_lun->cbe_lun;
        struct nameidata nd;
        const char      *value;
        int              error, flags;

        error = 0;
        if (rootvnode == NULL) {
                snprintf(req->error_str, sizeof(req->error_str),
                         "Root filesystem is not mounted");
                return (1);
        }
        pwd_ensure_dirs();

        value = dnvlist_get_string(cbe_lun->options, "file", NULL);
        if (value == NULL) {
                snprintf(req->error_str, sizeof(req->error_str),
                         "no file argument specified");
                return (1);
        }
        free(be_lun->dev_path, M_CTLBLK);
        be_lun->dev_path = strdup(value, M_CTLBLK);

        flags = FREAD;
        value = dnvlist_get_string(cbe_lun->options, "readonly", NULL);
        if (value != NULL) {
                if (strcmp(value, "on") != 0)
                        flags |= FWRITE;
        } else if (cbe_lun->lun_type == T_DIRECT)
                flags |= FWRITE;

again:
        NDINIT(&nd, LOOKUP, FOLLOW, UIO_SYSSPACE, be_lun->dev_path);
        error = vn_open(&nd, &flags, 0, NULL);
        if ((error == EROFS || error == EACCES) && (flags & FWRITE)) {
                flags &= ~FWRITE;
                goto again;
        }
        if (error) {
                /*
                 * This is the only reasonable guess we can make as far as
                 * path if the user doesn't give us a fully qualified path.
                 * If they want to specify a file, they need to specify the
                 * full path.
                 */
                if (be_lun->dev_path[0] != '/') {
                        char *dev_name;

                        asprintf(&dev_name, M_CTLBLK, "/dev/%s",
                                be_lun->dev_path);
                        free(be_lun->dev_path, M_CTLBLK);
                        be_lun->dev_path = dev_name;
                        goto again;
                }
                snprintf(req->error_str, sizeof(req->error_str),
                    "error opening %s: %d", be_lun->dev_path, error);
                return (error);
        }
        if (flags & FWRITE)
                cbe_lun->flags &= ~CTL_LUN_FLAG_READONLY;
        else
                cbe_lun->flags |= CTL_LUN_FLAG_READONLY;

        NDFREE_PNBUF(&nd);
        be_lun->vn = nd.ni_vp;

        /* We only support disks and files. */
        if (vn_isdisk_error(be_lun->vn, &error)) {
                error = ctl_be_block_open_dev(be_lun, req);
        } else if (be_lun->vn->v_type == VREG) {
                error = ctl_be_block_open_file(be_lun, req);
        } else {
                error = EINVAL;
                snprintf(req->error_str, sizeof(req->error_str),
                         "%s is not a disk or plain file", be_lun->dev_path);
        }
        VOP_UNLOCK(be_lun->vn);

        if (error != 0)
                ctl_be_block_close(be_lun);
        cbe_lun->serseq = CTL_LUN_SERSEQ_OFF;
        if (be_lun->dispatch != ctl_be_block_dispatch_dev)
                cbe_lun->serseq = CTL_LUN_SERSEQ_SOFT;
        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;
        return (0);
}

static int
ctl_be_block_create(struct ctl_be_block_softc *softc, struct ctl_lun_req *req)
{
        struct ctl_be_lun *cbe_lun;
        struct ctl_be_block_lun *be_lun;
        struct ctl_lun_create_params *params;
        char num_thread_str[16];
        char tmpstr[32];
        const char *value;
        int retval, num_threads;
        int tmp_num_threads;

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

        be_lun = malloc(sizeof(*be_lun), M_CTLBLK, M_ZERO | M_WAITOK);
        cbe_lun = &be_lun->cbe_lun;
        be_lun->params = req->reqdata.create;
        be_lun->softc = softc;
        STAILQ_INIT(&be_lun->input_queue);
        STAILQ_INIT(&be_lun->config_read_queue);
        STAILQ_INIT(&be_lun->config_write_queue);
        STAILQ_INIT(&be_lun->datamove_queue);
        mtx_init(&be_lun->io_lock, "ctlblock io", NULL, MTX_DEF);
        mtx_init(&be_lun->queue_lock, "ctlblock queue", NULL, MTX_DEF);
        cbe_lun->options = nvlist_clone(req->args_nvl);

        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;

        if (cbe_lun->lun_type == T_DIRECT ||
            cbe_lun->lun_type == T_CDROM) {
                be_lun->size_bytes = params->lun_size_bytes;
                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->size_blocks = be_lun->size_bytes / cbe_lun->blocksize;
                cbe_lun->maxlba = (be_lun->size_blocks == 0) ?
                    0 : (be_lun->size_blocks - 1);

                if ((cbe_lun->flags & CTL_LUN_FLAG_PRIMARY) ||
                    control_softc->ha_mode == CTL_HA_MODE_SER_ONLY) {
                        retval = ctl_be_block_open(be_lun, req);
                        if (retval != 0) {
                                retval = 0;
                                req->status = CTL_LUN_WARNING;
                        }
                }
                num_threads = cbb_num_threads;
        } else {
                num_threads = 1;
        }

        value = dnvlist_get_string(cbe_lun->options, "num_threads", NULL);
        if (value != NULL) {
                tmp_num_threads = strtol(value, NULL, 0);

                /*
                 * We don't let the user specify less than one
                 * thread, but hope he's clueful enough not to
                 * specify 1000 threads.
                 */
                if (tmp_num_threads < 1) {
                        snprintf(req->error_str, sizeof(req->error_str),
                                 "invalid number of threads %s",
                                 num_thread_str);
                        goto bailout_error;
                }
                num_threads = tmp_num_threads;
        }

        if (be_lun->vn == NULL)
                cbe_lun->flags |= CTL_LUN_FLAG_NO_MEDIA;
        /* Tell the user the blocksize we ended up using */
        params->lun_size_bytes = be_lun->size_bytes;
        params->blocksize_bytes = cbe_lun->blocksize;
        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_be_block_lun_shutdown;
        cbe_lun->be = &ctl_be_block_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)));
        }

        TASK_INIT(&be_lun->io_task, /*priority*/0, ctl_be_block_worker, be_lun);

        be_lun->io_taskqueue = taskqueue_create("ctlblocktq", M_WAITOK,
            taskqueue_thread_enqueue, /*context*/&be_lun->io_taskqueue);

        if (be_lun->io_taskqueue == NULL) {
                snprintf(req->error_str, sizeof(req->error_str),
                         "unable to create taskqueue");
                goto bailout_error;
        }

        /*
         * Note that we start the same number of threads by default for
         * both the file case and the block device case.  For the file
         * case, we need multiple threads to allow concurrency, because the
         * vnode interface is designed to be a blocking interface.  For the
         * block device case, ZFS zvols at least will block the caller's
         * context in many instances, and so we need multiple threads to
         * overcome that problem.  Other block devices don't need as many
         * threads, but they shouldn't cause too many problems.
         *
         * If the user wants to just have a single thread for a block
         * device, he can specify that when the LUN is created, or change
         * the tunable/sysctl to alter the default number of threads.
         */
        retval = taskqueue_start_threads_in_proc(&be_lun->io_taskqueue,
                                         /*num threads*/num_threads,
                                         /*priority*/PUSER,
                                         /*proc*/control_softc->ctl_proc,
                                         /*thread name*/"block");

        if (retval != 0)
                goto bailout_error;

        be_lun->num_threads = num_threads;

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

        be_lun->disk_stats = devstat_new_entry("cbb", cbe_lun->lun_id,
                                               cbe_lun->blocksize,
                                               DEVSTAT_ALL_SUPPORTED,
                                               cbe_lun->lun_type
                                               | DEVSTAT_TYPE_IF_OTHER,
                                               DEVSTAT_PRIORITY_OTHER);

        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;

        return (retval);

bailout_error:
        req->status = CTL_LUN_ERROR;

        if (be_lun->io_taskqueue != NULL)
                taskqueue_free(be_lun->io_taskqueue);
        ctl_be_block_close(be_lun);
        if (be_lun->dev_path != NULL)
                free(be_lun->dev_path, M_CTLBLK);
        nvlist_destroy(cbe_lun->options);
        mtx_destroy(&be_lun->queue_lock);
        mtx_destroy(&be_lun->io_lock);
        free(be_lun, M_CTLBLK);

        return (retval);
}

static int
ctl_be_block_rm(struct ctl_be_block_softc *softc, struct ctl_lun_req *req)
{
        struct ctl_lun_rm_params *params;
        struct ctl_be_block_lun *be_lun;
        struct ctl_be_lun *cbe_lun;
        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_block_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),
                         "LUN %u is not managed by the block backend",
                         params->lun_id);
                goto bailout_error;
        }
        cbe_lun = &be_lun->cbe_lun;

        if (be_lun->vn != NULL) {
                cbe_lun->flags |= CTL_LUN_FLAG_NO_MEDIA;
                ctl_lun_no_media(cbe_lun);
                taskqueue_drain_all(be_lun->io_taskqueue);
                ctl_be_block_close(be_lun);
        }

        mtx_lock(&softc->lock);
        be_lun->flags |= CTL_BE_BLOCK_LUN_WAITING;
        mtx_unlock(&softc->lock);

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

        mtx_lock(&softc->lock);
        while ((be_lun->flags & CTL_BE_BLOCK_LUN_UNCONFIGURED) == 0) {
                retval = msleep(be_lun, &softc->lock, PCATCH, "ctlblockrm", 0);
                if (retval == EINTR)
                        break;
        }
        be_lun->flags &= ~CTL_BE_BLOCK_LUN_WAITING;
        if (be_lun->flags & CTL_BE_BLOCK_LUN_UNCONFIGURED) {
                mtx_unlock(&softc->lock);
                free(be_lun, M_CTLBLK);
        } else {
                mtx_unlock(&softc->lock);
                return (EINTR);
        }

        req->status = CTL_LUN_OK;
        return (0);

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

static int
ctl_be_block_modify(struct ctl_be_block_softc *softc, struct ctl_lun_req *req)
{
        struct ctl_lun_modify_params *params;
        struct ctl_be_block_lun *be_lun;
        struct ctl_be_lun *cbe_lun;
        const char *value;
        uint64_t oldsize;
        int error, 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),
                         "LUN %u is not managed by the block backend",
                         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);
        }

        oldsize = be_lun->size_blocks;
        if ((cbe_lun->flags & CTL_LUN_FLAG_PRIMARY) ||
            control_softc->ha_mode == CTL_HA_MODE_SER_ONLY) {
                if (be_lun->vn == NULL)
                        error = ctl_be_block_open(be_lun, req);
                else if (vn_isdisk_error(be_lun->vn, &error))
                        error = ctl_be_block_open_dev(be_lun, req);
                else if (be_lun->vn->v_type == VREG) {
                        vn_lock(be_lun->vn, LK_SHARED | LK_RETRY);
                        error = ctl_be_block_open_file(be_lun, req);
                        VOP_UNLOCK(be_lun->vn);
                } else
                        error = EINVAL;
                if ((cbe_lun->flags & CTL_LUN_FLAG_NO_MEDIA) &&
                    be_lun->vn != NULL) {
                        cbe_lun->flags &= ~CTL_LUN_FLAG_NO_MEDIA;
                        ctl_lun_has_media(cbe_lun);
                } else if ((cbe_lun->flags & CTL_LUN_FLAG_NO_MEDIA) == 0 &&
                    be_lun->vn == NULL) {
                        cbe_lun->flags |= CTL_LUN_FLAG_NO_MEDIA;
                        ctl_lun_no_media(cbe_lun);
                }
                cbe_lun->flags &= ~CTL_LUN_FLAG_EJECTED;
        } else {
                if (be_lun->vn != NULL) {
                        cbe_lun->flags |= CTL_LUN_FLAG_NO_MEDIA;
                        ctl_lun_no_media(cbe_lun);
                        taskqueue_drain_all(be_lun->io_taskqueue);
                        error = ctl_be_block_close(be_lun);
                } else
                        error = 0;
        }
        if (be_lun->size_blocks != oldsize)
                ctl_lun_capacity_changed(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 = error ? CTL_LUN_WARNING : CTL_LUN_OK;
        return (0);

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

static void
ctl_be_block_lun_shutdown(struct ctl_be_lun *cbe_lun)
{
        struct ctl_be_block_lun *be_lun = (struct ctl_be_block_lun *)cbe_lun;
        struct ctl_be_block_softc *softc = be_lun->softc;

        taskqueue_drain_all(be_lun->io_taskqueue);
        taskqueue_free(be_lun->io_taskqueue);
        if (be_lun->disk_stats != NULL)
                devstat_remove_entry(be_lun->disk_stats);
        nvlist_destroy(be_lun->cbe_lun.options);
        free(be_lun->dev_path, M_CTLBLK);
        mtx_destroy(&be_lun->queue_lock);
        mtx_destroy(&be_lun->io_lock);

        mtx_lock(&softc->lock);
        be_lun->flags |= CTL_BE_BLOCK_LUN_UNCONFIGURED;
        if (be_lun->flags & CTL_BE_BLOCK_LUN_WAITING)
                wakeup(be_lun);
        else
                free(be_lun, M_CTLBLK);
        mtx_unlock(&softc->lock);
}

static int
ctl_be_block_scsi_config_write(union ctl_io *io)
{
        struct ctl_be_block_lun *be_lun;
        struct ctl_be_lun *cbe_lun;
        int retval;

        DPRINTF("entered\n");

        cbe_lun = CTL_BACKEND_LUN(io);
        be_lun = (struct ctl_be_block_lun *)cbe_lun;

        retval = 0;
        switch (io->scsiio.cdb[0]) {
        case SYNCHRONIZE_CACHE:
        case SYNCHRONIZE_CACHE_16:
        case WRITE_SAME_10:
        case WRITE_SAME_16:
        case UNMAP:
                /*
                 * The upper level CTL code will filter out any CDBs with
                 * the immediate bit set and return the proper error.
                 *
                 * We don't really need to worry about what LBA range the
                 * user asked to be synced out.  When they issue a sync
                 * cache command, we'll sync out the whole thing.
                 */
                mtx_lock(&be_lun->queue_lock);
                STAILQ_INSERT_TAIL(&be_lun->config_write_queue, &io->io_hdr,
                                   links);
                mtx_unlock(&be_lun->queue_lock);
                taskqueue_enqueue(be_lun->io_taskqueue, &be_lun->io_task);
                break;
        case START_STOP_UNIT: {
                struct scsi_start_stop_unit *cdb;
                struct ctl_lun_req req;

                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) && be_lun->vn == NULL) {
                                retval = ctl_be_block_open(be_lun, &req);
                                cbe_lun->flags &= ~CTL_LUN_FLAG_EJECTED;
                                if (retval == 0) {
                                        cbe_lun->flags &= ~CTL_LUN_FLAG_NO_MEDIA;
                                        ctl_lun_has_media(cbe_lun);
                                } else {
                                        cbe_lun->flags |= CTL_LUN_FLAG_NO_MEDIA;
                                        ctl_lun_no_media(cbe_lun);
                                }
                        }
                        ctl_start_lun(cbe_lun);
                } else {
                        ctl_stop_lun(cbe_lun);
                        if (cdb->how & SSS_LOEJ) {
                                cbe_lun->flags |= CTL_LUN_FLAG_NO_MEDIA;
                                cbe_lun->flags |= CTL_LUN_FLAG_EJECTED;
                                ctl_lun_ejected(cbe_lun);
                                if (be_lun->vn != NULL)
                                        ctl_be_block_close(be_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;
        default:
                ctl_set_invalid_opcode(&io->scsiio);
                ctl_config_write_done(io);
                retval = CTL_RETVAL_COMPLETE;
                break;
        }

        return (retval);
}

static int
ctl_be_block_nvme_config_write(union ctl_io *io)
{
        struct ctl_be_block_lun *be_lun;

        DPRINTF("entered\n");

        be_lun = (struct ctl_be_block_lun *)CTL_BACKEND_LUN(io);

        switch (io->nvmeio.cmd.opc) {
        case NVME_OPC_DATASET_MANAGEMENT:
                DSM_RANGE(io) = 0;
                /* FALLTHROUGH */
        case NVME_OPC_FLUSH:
        case NVME_OPC_WRITE_UNCORRECTABLE:
        case NVME_OPC_WRITE_ZEROES:
                mtx_lock(&be_lun->queue_lock);
                STAILQ_INSERT_TAIL(&be_lun->config_write_queue, &io->io_hdr,
                                   links);
                mtx_unlock(&be_lun->queue_lock);
                taskqueue_enqueue(be_lun->io_taskqueue, &be_lun->io_task);
                break;
        default:
                ctl_nvme_set_invalid_opcode(&io->nvmeio);
                ctl_config_write_done(io);
                break;
        }
        return (CTL_RETVAL_COMPLETE);
}

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

static int
ctl_be_block_scsi_config_read(union ctl_io *io)
{
        struct ctl_be_block_lun *be_lun;
        int retval = 0;

        DPRINTF("entered\n");

        be_lun = (struct ctl_be_block_lun *)CTL_BACKEND_LUN(io);

        switch (io->scsiio.cdb[0]) {
        case SERVICE_ACTION_IN:
                if (io->scsiio.cdb[1] == SGLS_SERVICE_ACTION) {
                        mtx_lock(&be_lun->queue_lock);
                        STAILQ_INSERT_TAIL(&be_lun->config_read_queue,
                            &io->io_hdr, links);
                        mtx_unlock(&be_lun->queue_lock);
                        taskqueue_enqueue(be_lun->io_taskqueue,
                            &be_lun->io_task);
                        retval = CTL_RETVAL_QUEUED;
                        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
ctl_be_block_nvme_config_read(union ctl_io *io)
{
        struct ctl_be_block_lun *be_lun;

        DPRINTF("entered\n");

        be_lun = (struct ctl_be_block_lun *)CTL_BACKEND_LUN(io);

        switch (io->nvmeio.cmd.opc) {
        case NVME_OPC_IDENTIFY:
        {
                uint8_t cns;

                cns = le32toh(io->nvmeio.cmd.cdw10) & 0xff;
                switch (cns) {
                case 0:
                case 3:
                        mtx_lock(&be_lun->queue_lock);
                        STAILQ_INSERT_TAIL(&be_lun->config_read_queue,
                            &io->io_hdr, links);
                        mtx_unlock(&be_lun->queue_lock);
                        taskqueue_enqueue(be_lun->io_taskqueue,
                            &be_lun->io_task);
                        return (CTL_RETVAL_QUEUED);
                default:
                        ctl_nvme_set_invalid_field(&io->nvmeio);
                        ctl_config_read_done(io);
                        break;
                }
                break;
        }
        default:
                ctl_nvme_set_invalid_opcode(&io->nvmeio);
                ctl_config_read_done(io);
                break;
        }
        return (CTL_RETVAL_COMPLETE);
}

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

static int
ctl_be_block_lun_info(struct ctl_be_lun *cbe_lun, struct sbuf *sb)
{
        struct ctl_be_block_lun *lun = (struct ctl_be_block_lun *)cbe_lun;
        int retval;

        retval = sbuf_cat(sb, "\t<num_threads>");
        if (retval != 0)
                goto bailout;
        retval = sbuf_printf(sb, "%d", lun->num_threads);
        if (retval != 0)
                goto bailout;
        retval = sbuf_cat(sb, "</num_threads>\n");

bailout:
        return (retval);
}

static uint64_t
ctl_be_block_lun_attr(struct ctl_be_lun *cbe_lun, const char *attrname)
{
        struct ctl_be_block_lun *lun = (struct ctl_be_block_lun *)cbe_lun;

        if (lun->getattr == NULL)
                return (UINT64_MAX);
        return (lun->getattr(lun, attrname));
}

static int
ctl_be_block_init(void)
{
        struct ctl_be_block_softc *softc = &backend_block_softc;

        sx_init(&softc->modify_lock, "ctlblock modify");
        mtx_init(&softc->lock, "ctlblock", NULL, MTX_DEF);
        softc->beio_zone = uma_zcreate("beio", sizeof(struct ctl_be_block_io),
            NULL, NULL, NULL, NULL, UMA_ALIGN_PTR, 0);
        softc->bufmin_zone = uma_zcreate("ctlblockmin", CTLBLK_MIN_SEG,
            NULL, NULL, NULL, NULL, /*align*/ 0, /*flags*/0);
        if (CTLBLK_MIN_SEG < CTLBLK_MAX_SEG)
                softc->bufmax_zone = uma_zcreate("ctlblockmax", CTLBLK_MAX_SEG,
                    NULL, NULL, NULL, NULL, /*align*/ 0, /*flags*/0);
        SLIST_INIT(&softc->lun_list);
        return (0);
}

static int
ctl_be_block_shutdown(void)
{
        struct ctl_be_block_softc *softc = &backend_block_softc;
        struct ctl_be_block_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);
        uma_zdestroy(softc->bufmin_zone);
        if (CTLBLK_MIN_SEG < CTLBLK_MAX_SEG)
                uma_zdestroy(softc->bufmax_zone);
        uma_zdestroy(softc->beio_zone);
        mtx_destroy(&softc->lock);
        sx_destroy(&softc->modify_lock);
        return (0);
}