qemu-e2k/block/iscsi.c

/*
 * QEMU Block driver for iSCSI images
 *
 * Copyright (c) 2010-2011 Ronnie Sahlberg <ronniesahlberg@gmail.com>
 * Copyright (c) 2012-2013 Peter Lieven <pl@kamp.de>
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
 * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 * THE SOFTWARE.
 */

#include "config-host.h"

#include <poll.h>
#include <arpa/inet.h>
#include "qemu-common.h"
#include "qemu/config-file.h"
#include "qemu/error-report.h"
#include "block/block_int.h"
#include "trace.h"
#include "block/scsi.h"
#include "qemu/iov.h"
#include "sysemu/sysemu.h"
#include "qmp-commands.h"

#include <iscsi/iscsi.h>
#include <iscsi/scsi-lowlevel.h>

#ifdef __linux__
#include <scsi/sg.h>
#include <block/scsi.h>
#endif

typedef struct IscsiLun {
    struct iscsi_context *iscsi;
    int lun;
    enum scsi_inquiry_peripheral_device_type type;
    int block_size;
    uint64_t num_blocks;
    int events;
    QEMUTimer *nop_timer;
    uint8_t lbpme;
    uint8_t lbprz;
    uint8_t has_write_same;
    struct scsi_inquiry_logical_block_provisioning lbp;
    struct scsi_inquiry_block_limits bl;
    unsigned char *zeroblock;
} IscsiLun;

typedef struct IscsiTask {
    int status;
    int complete;
    int retries;
    int do_retry;
    struct scsi_task *task;
    Coroutine *co;
    QEMUBH *bh;
} IscsiTask;

typedef struct IscsiAIOCB {
    BlockDriverAIOCB common;
    QEMUIOVector *qiov;
    QEMUBH *bh;
    IscsiLun *iscsilun;
    struct scsi_task *task;
    uint8_t *buf;
    int status;
    int canceled;
    int retries;
    int64_t sector_num;
    int nb_sectors;
#ifdef __linux__
    sg_io_hdr_t *ioh;
#endif
} IscsiAIOCB;

#define NOP_INTERVAL 5000
#define MAX_NOP_FAILURES 3
#define ISCSI_CMD_RETRIES 5

static void
iscsi_bh_cb(void *p)
{
    IscsiAIOCB *acb = p;

    qemu_bh_delete(acb->bh);

    g_free(acb->buf);
    acb->buf = NULL;

    if (acb->canceled == 0) {
        acb->common.cb(acb->common.opaque, acb->status);
    }

    if (acb->task != NULL) {
        scsi_free_scsi_task(acb->task);
        acb->task = NULL;
    }

    qemu_aio_release(acb);
}

static void
iscsi_schedule_bh(IscsiAIOCB *acb)
{
    if (acb->bh) {
        return;
    }
    acb->bh = qemu_bh_new(iscsi_bh_cb, acb);
    qemu_bh_schedule(acb->bh);
}

static void iscsi_co_generic_bh_cb(void *opaque)
{
    struct IscsiTask *iTask = opaque;
    qemu_bh_delete(iTask->bh);
    qemu_coroutine_enter(iTask->co, NULL);
}

static void
iscsi_co_generic_cb(struct iscsi_context *iscsi, int status,
                        void *command_data, void *opaque)
{
    struct IscsiTask *iTask = opaque;
    struct scsi_task *task = command_data;

    iTask->complete = 1;
    iTask->status = status;
    iTask->do_retry = 0;
    iTask->task = task;

    if (iTask->retries-- > 0 && status == SCSI_STATUS_CHECK_CONDITION
        && task->sense.key == SCSI_SENSE_UNIT_ATTENTION) {
        error_report("iSCSI CheckCondition: %s", iscsi_get_error(iscsi));
        iTask->do_retry = 1;
        goto out;
    }

    if (status != SCSI_STATUS_GOOD) {
        error_report("iSCSI Failure: %s", iscsi_get_error(iscsi));
    }

out:
    if (iTask->co) {
        iTask->bh = qemu_bh_new(iscsi_co_generic_bh_cb, iTask);
        qemu_bh_schedule(iTask->bh);
    }
}

static void iscsi_co_init_iscsitask(IscsiLun *iscsilun, struct IscsiTask *iTask)
{
    *iTask = (struct IscsiTask) {
        .co         = qemu_coroutine_self(),
        .retries    = ISCSI_CMD_RETRIES,
    };
}

static void
iscsi_abort_task_cb(struct iscsi_context *iscsi, int status, void *command_data,
                    void *private_data)
{
    IscsiAIOCB *acb = private_data;

    acb->status = -ECANCELED;
    iscsi_schedule_bh(acb);
}

static void
iscsi_aio_cancel(BlockDriverAIOCB *blockacb)
{
    IscsiAIOCB *acb = (IscsiAIOCB *)blockacb;
    IscsiLun *iscsilun = acb->iscsilun;

    if (acb->status != -EINPROGRESS) {
        return;
    }

    acb->canceled = 1;

    /* send a task mgmt call to the target to cancel the task on the target */
    iscsi_task_mgmt_abort_task_async(iscsilun->iscsi, acb->task,
                                     iscsi_abort_task_cb, acb);

    while (acb->status == -EINPROGRESS) {
        qemu_aio_wait();
    }
}

static const AIOCBInfo iscsi_aiocb_info = {
    .aiocb_size         = sizeof(IscsiAIOCB),
    .cancel             = iscsi_aio_cancel,
};


static void iscsi_process_read(void *arg);
static void iscsi_process_write(void *arg);

static void
iscsi_set_events(IscsiLun *iscsilun)
{
    struct iscsi_context *iscsi = iscsilun->iscsi;
    int ev;

    /* We always register a read handler.  */
    ev = POLLIN;
    ev |= iscsi_which_events(iscsi);
    if (ev != iscsilun->events) {
        qemu_aio_set_fd_handler(iscsi_get_fd(iscsi),
                      iscsi_process_read,
                      (ev & POLLOUT) ? iscsi_process_write : NULL,
                      iscsilun);

    }

    iscsilun->events = ev;
}

static void
iscsi_process_read(void *arg)
{
    IscsiLun *iscsilun = arg;
    struct iscsi_context *iscsi = iscsilun->iscsi;

    iscsi_service(iscsi, POLLIN);
    iscsi_set_events(iscsilun);
}

static void
iscsi_process_write(void *arg)
{
    IscsiLun *iscsilun = arg;
    struct iscsi_context *iscsi = iscsilun->iscsi;

    iscsi_service(iscsi, POLLOUT);
    iscsi_set_events(iscsilun);
}

static int64_t sector_lun2qemu(int64_t sector, IscsiLun *iscsilun)
{
    return sector * iscsilun->block_size / BDRV_SECTOR_SIZE;
}

static int64_t sector_qemu2lun(int64_t sector, IscsiLun *iscsilun)
{
    return sector * BDRV_SECTOR_SIZE / iscsilun->block_size;
}

static bool is_request_lun_aligned(int64_t sector_num, int nb_sectors,
                                      IscsiLun *iscsilun)
{
    if ((sector_num * BDRV_SECTOR_SIZE) % iscsilun->block_size ||
        (nb_sectors * BDRV_SECTOR_SIZE) % iscsilun->block_size) {
            error_report("iSCSI misaligned request: "
                         "iscsilun->block_size %u, sector_num %" PRIi64
                         ", nb_sectors %d",
                         iscsilun->block_size, sector_num, nb_sectors);
            return 0;
    }
    return 1;
}

static int coroutine_fn iscsi_co_writev(BlockDriverState *bs,
                                        int64_t sector_num, int nb_sectors,
                                        QEMUIOVector *iov)
{
    IscsiLun *iscsilun = bs->opaque;
    struct IscsiTask iTask;
    uint64_t lba;
    uint32_t num_sectors;
    uint8_t *data = NULL;
    uint8_t *buf = NULL;

    if (!is_request_lun_aligned(sector_num, nb_sectors, iscsilun)) {
        return -EINVAL;
    }

    lba = sector_qemu2lun(sector_num, iscsilun);
    num_sectors = sector_qemu2lun(nb_sectors, iscsilun);
#if !defined(LIBISCSI_FEATURE_IOVECTOR)
    /* if the iovec only contains one buffer we can pass it directly */
    if (iov->niov == 1) {
        data = iov->iov[0].iov_base;
    } else {
        size_t size = MIN(nb_sectors * BDRV_SECTOR_SIZE, iov->size);
        buf = g_malloc(size);
        qemu_iovec_to_buf(iov, 0, buf, size);
        data = buf;
    }
#endif
    iscsi_co_init_iscsitask(iscsilun, &iTask);
retry:
    iTask.task = iscsi_write16_task(iscsilun->iscsi, iscsilun->lun, lba,
                                    data, num_sectors * iscsilun->block_size,
                                    iscsilun->block_size, 0, 0, 0, 0, 0,
                                    iscsi_co_generic_cb, &iTask);
    if (iTask.task == NULL) {
        g_free(buf);
        return -ENOMEM;
    }
#if defined(LIBISCSI_FEATURE_IOVECTOR)
    scsi_task_set_iov_out(iTask.task, (struct scsi_iovec *) iov->iov,
                          iov->niov);
#endif
    while (!iTask.complete) {
        iscsi_set_events(iscsilun);
        qemu_coroutine_yield();
    }

    if (iTask.task != NULL) {
        scsi_free_scsi_task(iTask.task);
        iTask.task = NULL;
    }

    if (iTask.do_retry) {
        iTask.complete = 0;
        goto retry;
    }

    g_free(buf);

    if (iTask.status != SCSI_STATUS_GOOD) {
        return -EIO;
    }

    return 0;
}

static int coroutine_fn iscsi_co_readv(BlockDriverState *bs,
                                       int64_t sector_num, int nb_sectors,
                                       QEMUIOVector *iov)
{
    IscsiLun *iscsilun = bs->opaque;
    struct IscsiTask iTask;
    uint64_t lba;
    uint32_t num_sectors;
#if !defined(LIBISCSI_FEATURE_IOVECTOR)
    int i;
#endif

    if (!is_request_lun_aligned(sector_num, nb_sectors, iscsilun)) {
        return -EINVAL;
    }

    lba = sector_qemu2lun(sector_num, iscsilun);
    num_sectors = sector_qemu2lun(nb_sectors, iscsilun);

    iscsi_co_init_iscsitask(iscsilun, &iTask);
retry:
    switch (iscsilun->type) {
    case TYPE_DISK:
        iTask.task = iscsi_read16_task(iscsilun->iscsi, iscsilun->lun, lba,
                                       num_sectors * iscsilun->block_size,
                                       iscsilun->block_size, 0, 0, 0, 0, 0,
                                       iscsi_co_generic_cb, &iTask);
        break;
    default:
        iTask.task = iscsi_read10_task(iscsilun->iscsi, iscsilun->lun, lba,
                                       num_sectors * iscsilun->block_size,
                                       iscsilun->block_size,
#if !defined(CONFIG_LIBISCSI_1_4) /* API change from 1.4.0 to 1.5.0 */
                                       0, 0, 0, 0, 0,
#endif
                                       iscsi_co_generic_cb, &iTask);
        break;
    }
    if (iTask.task == NULL) {
        return -ENOMEM;
    }
#if defined(LIBISCSI_FEATURE_IOVECTOR)
    scsi_task_set_iov_in(iTask.task, (struct scsi_iovec *) iov->iov, iov->niov);
#else
    for (i = 0; i < iov->niov; i++) {
        scsi_task_add_data_in_buffer(iTask.task,
                                     iov->iov[i].iov_len,
                                     iov->iov[i].iov_base);
    }
#endif

    while (!iTask.complete) {
        iscsi_set_events(iscsilun);
        qemu_coroutine_yield();
    }

    if (iTask.task != NULL) {
        scsi_free_scsi_task(iTask.task);
        iTask.task = NULL;
    }

    if (iTask.do_retry) {
        iTask.complete = 0;
        goto retry;
    }

    if (iTask.status != SCSI_STATUS_GOOD) {
        return -EIO;
    }

    return 0;
}

static int coroutine_fn iscsi_co_flush(BlockDriverState *bs)
{
    IscsiLun *iscsilun = bs->opaque;
    struct IscsiTask iTask;

    iscsi_co_init_iscsitask(iscsilun, &iTask);

retry:
    if (iscsi_synchronizecache10_task(iscsilun->iscsi, iscsilun->lun, 0, 0, 0,
                                      0, iscsi_co_generic_cb, &iTask) == NULL) {
        return -ENOMEM;
    }

    while (!iTask.complete) {
        iscsi_set_events(iscsilun);
        qemu_coroutine_yield();
    }

    if (iTask.task != NULL) {
        scsi_free_scsi_task(iTask.task);
        iTask.task = NULL;
    }

    if (iTask.do_retry) {
        iTask.complete = 0;
        goto retry;
    }

    if (iTask.status != SCSI_STATUS_GOOD) {
        return -EIO;
    }

    return 0;
}

#ifdef __linux__
static void
iscsi_aio_ioctl_cb(struct iscsi_context *iscsi, int status,
                     void *command_data, void *opaque)
{
    IscsiAIOCB *acb = opaque;

    g_free(acb->buf);
    acb->buf = NULL;

    if (acb->canceled != 0) {
        return;
    }

    acb->status = 0;
    if (status < 0) {
        error_report("Failed to ioctl(SG_IO) to iSCSI lun. %s",
                     iscsi_get_error(iscsi));
        acb->status = -EIO;
    }

    acb->ioh->driver_status = 0;
    acb->ioh->host_status   = 0;
    acb->ioh->resid         = 0;

#define SG_ERR_DRIVER_SENSE    0x08

    if (status == SCSI_STATUS_CHECK_CONDITION && acb->task->datain.size >= 2) {
        int ss;

        acb->ioh->driver_status |= SG_ERR_DRIVER_SENSE;

        acb->ioh->sb_len_wr = acb->task->datain.size - 2;
        ss = (acb->ioh->mx_sb_len >= acb->ioh->sb_len_wr) ?
             acb->ioh->mx_sb_len : acb->ioh->sb_len_wr;
        memcpy(acb->ioh->sbp, &acb->task->datain.data[2], ss);
    }

    iscsi_schedule_bh(acb);
}

static BlockDriverAIOCB *iscsi_aio_ioctl(BlockDriverState *bs,
        unsigned long int req, void *buf,
        BlockDriverCompletionFunc *cb, void *opaque)
{
    IscsiLun *iscsilun = bs->opaque;
    struct iscsi_context *iscsi = iscsilun->iscsi;
    struct iscsi_data data;
    IscsiAIOCB *acb;

    assert(req == SG_IO);

    acb = qemu_aio_get(&iscsi_aiocb_info, bs, cb, opaque);

    acb->iscsilun = iscsilun;
    acb->canceled    = 0;
    acb->bh          = NULL;
    acb->status      = -EINPROGRESS;
    acb->buf         = NULL;
    acb->ioh         = buf;

    acb->task = malloc(sizeof(struct scsi_task));
    if (acb->task == NULL) {
        error_report("iSCSI: Failed to allocate task for scsi command. %s",
                     iscsi_get_error(iscsi));
        qemu_aio_release(acb);
        return NULL;
    }
    memset(acb->task, 0, sizeof(struct scsi_task));

    switch (acb->ioh->dxfer_direction) {
    case SG_DXFER_TO_DEV:
        acb->task->xfer_dir = SCSI_XFER_WRITE;
        break;
    case SG_DXFER_FROM_DEV:
        acb->task->xfer_dir = SCSI_XFER_READ;
        break;
    default:
        acb->task->xfer_dir = SCSI_XFER_NONE;
        break;
    }

    acb->task->cdb_size = acb->ioh->cmd_len;
    memcpy(&acb->task->cdb[0], acb->ioh->cmdp, acb->ioh->cmd_len);
    acb->task->expxferlen = acb->ioh->dxfer_len;

    data.size = 0;
    if (acb->task->xfer_dir == SCSI_XFER_WRITE) {
        if (acb->ioh->iovec_count == 0) {
            data.data = acb->ioh->dxferp;
            data.size = acb->ioh->dxfer_len;
        } else {
#if defined(LIBISCSI_FEATURE_IOVECTOR)
            scsi_task_set_iov_out(acb->task,
                                 (struct scsi_iovec *) acb->ioh->dxferp,
                                 acb->ioh->iovec_count);
#else
            struct iovec *iov = (struct iovec *)acb->ioh->dxferp;

            acb->buf = g_malloc(acb->ioh->dxfer_len);
            data.data = acb->buf;
            data.size = iov_to_buf(iov, acb->ioh->iovec_count, 0,
                                   acb->buf, acb->ioh->dxfer_len);
#endif
        }
    }

    if (iscsi_scsi_command_async(iscsi, iscsilun->lun, acb->task,
                                 iscsi_aio_ioctl_cb,
                                 (data.size > 0) ? &data : NULL,
                                 acb) != 0) {
        scsi_free_scsi_task(acb->task);
        qemu_aio_release(acb);
        return NULL;
    }

    /* tell libiscsi to read straight into the buffer we got from ioctl */
    if (acb->task->xfer_dir == SCSI_XFER_READ) {
        if (acb->ioh->iovec_count == 0) {
            scsi_task_add_data_in_buffer(acb->task,
                                         acb->ioh->dxfer_len,
                                         acb->ioh->dxferp);
        } else {
#if defined(LIBISCSI_FEATURE_IOVECTOR)
            scsi_task_set_iov_in(acb->task,
                                 (struct scsi_iovec *) acb->ioh->dxferp,
                                 acb->ioh->iovec_count);
#else
            int i;
            for (i = 0; i < acb->ioh->iovec_count; i++) {
                struct iovec *iov = (struct iovec *)acb->ioh->dxferp;

                scsi_task_add_data_in_buffer(acb->task,
                    iov[i].iov_len,
                    iov[i].iov_base);
            }
#endif
        }
    }

    iscsi_set_events(iscsilun);

    return &acb->common;
}


static void ioctl_cb(void *opaque, int status)
{
    int *p_status = opaque;
    *p_status = status;
}

static int iscsi_ioctl(BlockDriverState *bs, unsigned long int req, void *buf)
{
    IscsiLun *iscsilun = bs->opaque;
    int status;

    switch (req) {
    case SG_GET_VERSION_NUM:
        *(int *)buf = 30000;
        break;
    case SG_GET_SCSI_ID:
        ((struct sg_scsi_id *)buf)->scsi_type = iscsilun->type;
        break;
    case SG_IO:
        status = -EINPROGRESS;
        iscsi_aio_ioctl(bs, req, buf, ioctl_cb, &status);

        while (status == -EINPROGRESS) {
            qemu_aio_wait();
        }

        return 0;
    default:
        return -1;
    }
    return 0;
}
#endif

static int64_t
iscsi_getlength(BlockDriverState *bs)
{
    IscsiLun *iscsilun = bs->opaque;
    int64_t len;

    len  = iscsilun->num_blocks;
    len *= iscsilun->block_size;

    return len;
}

#if defined(LIBISCSI_FEATURE_IOVECTOR)

static int64_t coroutine_fn iscsi_co_get_block_status(BlockDriverState *bs,
                                                  int64_t sector_num,
                                                  int nb_sectors, int *pnum)
{
    IscsiLun *iscsilun = bs->opaque;
    struct scsi_get_lba_status *lbas = NULL;
    struct scsi_lba_status_descriptor *lbasd = NULL;
    struct IscsiTask iTask;
    int64_t ret;

    iscsi_co_init_iscsitask(iscsilun, &iTask);

    if (!is_request_lun_aligned(sector_num, nb_sectors, iscsilun)) {
        ret = -EINVAL;
        goto out;
    }

    /* default to all sectors allocated */
    ret = BDRV_BLOCK_DATA;
    ret |= (sector_num << BDRV_SECTOR_BITS) | BDRV_BLOCK_OFFSET_VALID;
    *pnum = nb_sectors;

    /* LUN does not support logical block provisioning */
    if (iscsilun->lbpme == 0) {
        goto out;
    }

retry:
    if (iscsi_get_lba_status_task(iscsilun->iscsi, iscsilun->lun,
                                  sector_qemu2lun(sector_num, iscsilun),
                                  8 + 16, iscsi_co_generic_cb,
                                  &iTask) == NULL) {
        ret = -ENOMEM;
        goto out;
    }

    while (!iTask.complete) {
        iscsi_set_events(iscsilun);
        qemu_coroutine_yield();
    }

    if (iTask.do_retry) {
        if (iTask.task != NULL) {
            scsi_free_scsi_task(iTask.task);
            iTask.task = NULL;
        }
        iTask.complete = 0;
        goto retry;
    }

    if (iTask.status != SCSI_STATUS_GOOD) {
        /* in case the get_lba_status_callout fails (i.e.
         * because the device is busy or the cmd is not
         * supported) we pretend all blocks are allocated
         * for backwards compatibility */
        goto out;
    }

    lbas = scsi_datain_unmarshall(iTask.task);
    if (lbas == NULL) {
        ret = -EIO;
        goto out;
    }

    lbasd = &lbas->descriptors[0];

    if (sector_qemu2lun(sector_num, iscsilun) != lbasd->lba) {
        ret = -EIO;
        goto out;
    }

    *pnum = sector_lun2qemu(lbasd->num_blocks, iscsilun);
    if (*pnum > nb_sectors) {
        *pnum = nb_sectors;
    }

    if (lbasd->provisioning == SCSI_PROVISIONING_TYPE_DEALLOCATED ||
        lbasd->provisioning == SCSI_PROVISIONING_TYPE_ANCHORED) {
        ret &= ~BDRV_BLOCK_DATA;
        if (iscsilun->lbprz) {
            ret |= BDRV_BLOCK_ZERO;
        }
    }

out:
    if (iTask.task != NULL) {
        scsi_free_scsi_task(iTask.task);
    }
    return ret;
}

#endif /* LIBISCSI_FEATURE_IOVECTOR */

static int
coroutine_fn iscsi_co_discard(BlockDriverState *bs, int64_t sector_num,
                                   int nb_sectors)
{
    IscsiLun *iscsilun = bs->opaque;
    struct IscsiTask iTask;
    struct unmap_list list;

    if (!is_request_lun_aligned(sector_num, nb_sectors, iscsilun)) {
        return -EINVAL;
    }

    if (!iscsilun->lbp.lbpu) {
        /* UNMAP is not supported by the target */
        return 0;
    }

    list.lba = sector_qemu2lun(sector_num, iscsilun);
    list.num = sector_qemu2lun(nb_sectors, iscsilun);

    iscsi_co_init_iscsitask(iscsilun, &iTask);
retry:
    if (iscsi_unmap_task(iscsilun->iscsi, iscsilun->lun, 0, 0, &list, 1,
                     iscsi_co_generic_cb, &iTask) == NULL) {
        return -ENOMEM;
    }

    while (!iTask.complete) {
        iscsi_set_events(iscsilun);
        qemu_coroutine_yield();
    }

    if (iTask.task != NULL) {
        scsi_free_scsi_task(iTask.task);
        iTask.task = NULL;
    }

    if (iTask.do_retry) {
        iTask.complete = 0;
        goto retry;
    }

    if (iTask.status == SCSI_STATUS_CHECK_CONDITION) {
        /* the target might fail with a check condition if it
           is not happy with the alignment of the UNMAP request
           we silently fail in this case */
        return 0;
    }

    if (iTask.status != SCSI_STATUS_GOOD) {
        return -EIO;
    }

    return 0;
}

#if defined(SCSI_SENSE_ASCQ_CAPACITY_DATA_HAS_CHANGED)

static int
coroutine_fn iscsi_co_write_zeroes(BlockDriverState *bs, int64_t sector_num,
                                   int nb_sectors, BdrvRequestFlags flags)
{
    IscsiLun *iscsilun = bs->opaque;
    struct IscsiTask iTask;
    uint64_t lba;
    uint32_t nb_blocks;

    if (!is_request_lun_aligned(sector_num, nb_sectors, iscsilun)) {
        return -EINVAL;
    }

    if (!(flags & BDRV_REQ_MAY_UNMAP) && !iscsilun->has_write_same) {
        /* WRITE SAME without UNMAP is not supported by the target */
        return -ENOTSUP;
    }

    if ((flags & BDRV_REQ_MAY_UNMAP) && !iscsilun->lbp.lbpws) {
        /* WRITE SAME with UNMAP is not supported by the target */
        return -ENOTSUP;
    }

    lba = sector_qemu2lun(sector_num, iscsilun);
    nb_blocks = sector_qemu2lun(nb_sectors, iscsilun);

    if (iscsilun->zeroblock == NULL) {
        iscsilun->zeroblock = g_malloc0(iscsilun->block_size);
    }

    iscsi_co_init_iscsitask(iscsilun, &iTask);
retry:
    if (iscsi_writesame16_task(iscsilun->iscsi, iscsilun->lun, lba,
                               iscsilun->zeroblock, iscsilun->block_size,
                               nb_blocks, 0, !!(flags & BDRV_REQ_MAY_UNMAP),
                               0, 0, iscsi_co_generic_cb, &iTask) == NULL) {
        return -ENOMEM;
    }

    while (!iTask.complete) {
        iscsi_set_events(iscsilun);
        qemu_coroutine_yield();
    }

    if (iTask.task != NULL) {
        scsi_free_scsi_task(iTask.task);
        iTask.task = NULL;
    }

    if (iTask.do_retry) {
        iTask.complete = 0;
        goto retry;
    }

    if (iTask.status != SCSI_STATUS_GOOD) {
        if (iTask.status == SCSI_STATUS_CHECK_CONDITION &&
            iTask.task->sense.key == SCSI_SENSE_ILLEGAL_REQUEST &&
            iTask.task->sense.ascq == SCSI_SENSE_ASCQ_INVALID_OPERATION_CODE) {
            /* WRITE SAME is not supported by the target */
            iscsilun->has_write_same = false;
            return -ENOTSUP;
        }

        return -EIO;
    }

    return 0;
}

#endif /* SCSI_SENSE_ASCQ_CAPACITY_DATA_HAS_CHANGED */

static void parse_chap(struct iscsi_context *iscsi, const char *target,
                       Error **errp)
{
    QemuOptsList *list;
    QemuOpts *opts;
    const char *user = NULL;
    const char *password = NULL;

    list = qemu_find_opts("iscsi");
    if (!list) {
        return;
    }

    opts = qemu_opts_find(list, target);
    if (opts == NULL) {
        opts = QTAILQ_FIRST(&list->head);
        if (!opts) {
            return;
        }
    }

    user = qemu_opt_get(opts, "user");
    if (!user) {
        return;
    }

    password = qemu_opt_get(opts, "password");
    if (!password) {
        error_setg(errp, "CHAP username specified but no password was given");
        return;
    }

    if (iscsi_set_initiator_username_pwd(iscsi, user, password)) {
        error_setg(errp, "Failed to set initiator username and password");
    }
}

static void parse_header_digest(struct iscsi_context *iscsi, const char *target,
                                Error **errp)
{
    QemuOptsList *list;
    QemuOpts *opts;
    const char *digest = NULL;

    list = qemu_find_opts("iscsi");
    if (!list) {
        return;
    }

    opts = qemu_opts_find(list, target);
    if (opts == NULL) {
        opts = QTAILQ_FIRST(&list->head);
        if (!opts) {
            return;
        }
    }

    digest = qemu_opt_get(opts, "header-digest");
    if (!digest) {
        return;
    }

    if (!strcmp(digest, "CRC32C")) {
        iscsi_set_header_digest(iscsi, ISCSI_HEADER_DIGEST_CRC32C);
    } else if (!strcmp(digest, "NONE")) {
        iscsi_set_header_digest(iscsi, ISCSI_HEADER_DIGEST_NONE);
    } else if (!strcmp(digest, "CRC32C-NONE")) {
        iscsi_set_header_digest(iscsi, ISCSI_HEADER_DIGEST_CRC32C_NONE);
    } else if (!strcmp(digest, "NONE-CRC32C")) {
        iscsi_set_header_digest(iscsi, ISCSI_HEADER_DIGEST_NONE_CRC32C);
    } else {
        error_setg(errp, "Invalid header-digest setting : %s", digest);
    }
}

static char *parse_initiator_name(const char *target)
{
    QemuOptsList *list;
    QemuOpts *opts;
    const char *name;
    char *iscsi_name;
    UuidInfo *uuid_info;

    list = qemu_find_opts("iscsi");
    if (list) {
        opts = qemu_opts_find(list, target);
        if (!opts) {
            opts = QTAILQ_FIRST(&list->head);
        }
        if (opts) {
            name = qemu_opt_get(opts, "initiator-name");
            if (name) {
                return g_strdup(name);
            }
        }
    }

    uuid_info = qmp_query_uuid(NULL);
    if (strcmp(uuid_info->UUID, UUID_NONE) == 0) {
        name = qemu_get_vm_name();
    } else {
        name = uuid_info->UUID;
    }
    iscsi_name = g_strdup_printf("iqn.2008-11.org.linux-kvm%s%s",
                                 name ? ":" : "", name ? name : "");
    qapi_free_UuidInfo(uuid_info);
    return iscsi_name;
}

#if defined(LIBISCSI_FEATURE_NOP_COUNTER)
static void iscsi_nop_timed_event(void *opaque)
{
    IscsiLun *iscsilun = opaque;

    if (iscsi_get_nops_in_flight(iscsilun->iscsi) > MAX_NOP_FAILURES) {
        error_report("iSCSI: NOP timeout. Reconnecting...");
        iscsi_reconnect(iscsilun->iscsi);
    }

    if (iscsi_nop_out_async(iscsilun->iscsi, NULL, NULL, 0, NULL) != 0) {
        error_report("iSCSI: failed to sent NOP-Out. Disabling NOP messages.");
        return;
    }

    timer_mod(iscsilun->nop_timer, qemu_clock_get_ms(QEMU_CLOCK_REALTIME) + NOP_INTERVAL);
    iscsi_set_events(iscsilun);
}
#endif

static void iscsi_readcapacity_sync(IscsiLun *iscsilun, Error **errp)
{
    struct scsi_task *task = NULL;
    struct scsi_readcapacity10 *rc10 = NULL;
    struct scsi_readcapacity16 *rc16 = NULL;
    int retries = ISCSI_CMD_RETRIES; 

    do {
        if (task != NULL) {
            scsi_free_scsi_task(task);
            task = NULL;
        }

        switch (iscsilun->type) {
        case TYPE_DISK:
            task = iscsi_readcapacity16_sync(iscsilun->iscsi, iscsilun->lun);
            if (task != NULL && task->status == SCSI_STATUS_GOOD) {
                rc16 = scsi_datain_unmarshall(task);
                if (rc16 == NULL) {
                    error_setg(errp, "iSCSI: Failed to unmarshall readcapacity16 data.");
                } else {
                    iscsilun->block_size = rc16->block_length;
                    iscsilun->num_blocks = rc16->returned_lba + 1;
                    iscsilun->lbpme = rc16->lbpme;
                    iscsilun->lbprz = rc16->lbprz;
                }
            }
            break;
        case TYPE_ROM:
            task = iscsi_readcapacity10_sync(iscsilun->iscsi, iscsilun->lun, 0, 0);
            if (task != NULL && task->status == SCSI_STATUS_GOOD) {
                rc10 = scsi_datain_unmarshall(task);
                if (rc10 == NULL) {
                    error_setg(errp, "iSCSI: Failed to unmarshall readcapacity10 data.");
                } else {
                    iscsilun->block_size = rc10->block_size;
                    if (rc10->lba == 0) {
                        /* blank disk loaded */
                        iscsilun->num_blocks = 0;
                    } else {
                        iscsilun->num_blocks = rc10->lba + 1;
                    }
                }
            }
            break;
        default:
            return;
        }
    } while (task != NULL && task->status == SCSI_STATUS_CHECK_CONDITION
             && task->sense.key == SCSI_SENSE_UNIT_ATTENTION
             && retries-- > 0);

    if (task == NULL || task->status != SCSI_STATUS_GOOD) {
        error_setg(errp, "iSCSI: failed to send readcapacity10 command.");
    }
    if (task) {
        scsi_free_scsi_task(task);
    }
}

/* TODO Convert to fine grained options */
static QemuOptsList runtime_opts = {
    .name = "iscsi",
    .head = QTAILQ_HEAD_INITIALIZER(runtime_opts.head),
    .desc = {
        {
            .name = "filename",
            .type = QEMU_OPT_STRING,
            .help = "URL to the iscsi image",
        },
        { /* end of list */ }
    },
};

static struct scsi_task *iscsi_do_inquiry(struct iscsi_context *iscsi, int lun,
                                          int evpd, int pc, Error **errp)
{
    int full_size;
    struct scsi_task *task = NULL;
    task = iscsi_inquiry_sync(iscsi, lun, evpd, pc, 64);
    if (task == NULL || task->status != SCSI_STATUS_GOOD) {
        goto fail;
    }
    full_size = scsi_datain_getfullsize(task);
    if (full_size > task->datain.size) {
        scsi_free_scsi_task(task);

        /* we need more data for the full list */
        task = iscsi_inquiry_sync(iscsi, lun, evpd, pc, full_size);
        if (task == NULL || task->status != SCSI_STATUS_GOOD) {
            goto fail;
        }
    }

    return task;

fail:
    error_setg(errp, "iSCSI: Inquiry command failed : %s",
               iscsi_get_error(iscsi));
    if (task) {
        scsi_free_scsi_task(task);
        return NULL;
    }
    return NULL;
}

/*
 * We support iscsi url's on the form
 * iscsi://[<username>%<password>@]<host>[:<port>]/<targetname>/<lun>
 *
 * Note: flags are currently not used by iscsi_open.  If this function
 * is changed such that flags are used, please examine iscsi_reopen_prepare()
 * to see if needs to be changed as well.
 */
static int iscsi_open(BlockDriverState *bs, QDict *options, int flags,
                      Error **errp)
{
    IscsiLun *iscsilun = bs->opaque;
    struct iscsi_context *iscsi = NULL;
    struct iscsi_url *iscsi_url = NULL;
    struct scsi_task *task = NULL;
    struct scsi_inquiry_standard *inq = NULL;
    char *initiator_name = NULL;
    QemuOpts *opts;
    Error *local_err = NULL;
    const char *filename;
    int ret;

    if ((BDRV_SECTOR_SIZE % 512) != 0) {
        error_setg(errp, "iSCSI: Invalid BDRV_SECTOR_SIZE. "
                   "BDRV_SECTOR_SIZE(%lld) is not a multiple "
                   "of 512", BDRV_SECTOR_SIZE);
        return -EINVAL;
    }

    opts = qemu_opts_create(&runtime_opts, NULL, 0, &error_abort);
    qemu_opts_absorb_qdict(opts, options, &local_err);
    if (local_err) {
        error_propagate(errp, local_err);
        ret = -EINVAL;
        goto out;
    }

    filename = qemu_opt_get(opts, "filename");

    iscsi_url = iscsi_parse_full_url(iscsi, filename);
    if (iscsi_url == NULL) {
        error_setg(errp, "Failed to parse URL : %s", filename);
        ret = -EINVAL;
        goto out;
    }

    memset(iscsilun, 0, sizeof(IscsiLun));

    initiator_name = parse_initiator_name(iscsi_url->target);

    iscsi = iscsi_create_context(initiator_name);
    if (iscsi == NULL) {
        error_setg(errp, "iSCSI: Failed to create iSCSI context.");
        ret = -ENOMEM;
        goto out;
    }

    if (iscsi_set_targetname(iscsi, iscsi_url->target)) {
        error_setg(errp, "iSCSI: Failed to set target name.");
        ret = -EINVAL;
        goto out;
    }

    if (iscsi_url->user != NULL) {
        ret = iscsi_set_initiator_username_pwd(iscsi, iscsi_url->user,
                                              iscsi_url->passwd);
        if (ret != 0) {
            error_setg(errp, "Failed to set initiator username and password");
            ret = -EINVAL;
            goto out;
        }
    }

    /* check if we got CHAP username/password via the options */
    parse_chap(iscsi, iscsi_url->target, &local_err);
    if (local_err != NULL) {
        error_propagate(errp, local_err);
        ret = -EINVAL;
        goto out;
    }

    if (iscsi_set_session_type(iscsi, ISCSI_SESSION_NORMAL) != 0) {
        error_setg(errp, "iSCSI: Failed to set session type to normal.");
        ret = -EINVAL;
        goto out;
    }

    iscsi_set_header_digest(iscsi, ISCSI_HEADER_DIGEST_NONE_CRC32C);

    /* check if we got HEADER_DIGEST via the options */
    parse_header_digest(iscsi, iscsi_url->target, &local_err);
    if (local_err != NULL) {
        error_propagate(errp, local_err);
        ret = -EINVAL;
        goto out;
    }

    if (iscsi_full_connect_sync(iscsi, iscsi_url->portal, iscsi_url->lun) != 0) {
        error_setg(errp, "iSCSI: Failed to connect to LUN : %s",
            iscsi_get_error(iscsi));
        ret = -EINVAL;
        goto out;
    }

    iscsilun->iscsi = iscsi;
    iscsilun->lun   = iscsi_url->lun;

    task = iscsi_inquiry_sync(iscsi, iscsilun->lun, 0, 0, 36);

    if (task == NULL || task->status != SCSI_STATUS_GOOD) {
        error_setg(errp, "iSCSI: failed to send inquiry command.");
        ret = -EINVAL;
        goto out;
    }

    inq = scsi_datain_unmarshall(task);
    if (inq == NULL) {
        error_setg(errp, "iSCSI: Failed to unmarshall inquiry data.");
        ret = -EINVAL;
        goto out;
    }

    iscsilun->type = inq->periperal_device_type;
    iscsilun->has_write_same = true;

    iscsi_readcapacity_sync(iscsilun, &local_err);
    if (local_err != NULL) {
        error_propagate(errp, local_err);
        goto out;
    }
    bs->total_sectors = sector_lun2qemu(iscsilun->num_blocks, iscsilun);
    bs->request_alignment = iscsilun->block_size;

    /* Medium changer or tape. We dont have any emulation for this so this must
     * be sg ioctl compatible. We force it to be sg, otherwise qemu will try
     * to read from the device to guess the image format.
     */
    if (iscsilun->type == TYPE_MEDIUM_CHANGER ||
        iscsilun->type == TYPE_TAPE) {
        bs->sg = 1;
    }

    if (iscsilun->lbpme) {
        struct scsi_inquiry_logical_block_provisioning *inq_lbp;
        task = iscsi_do_inquiry(iscsilun->iscsi, iscsilun->lun, 1,
                                SCSI_INQUIRY_PAGECODE_LOGICAL_BLOCK_PROVISIONING,
                                errp);
        if (task == NULL) {
            ret = -EINVAL;
            goto out;
        }
        inq_lbp = scsi_datain_unmarshall(task);
        if (inq_lbp == NULL) {
            error_setg(errp, "iSCSI: failed to unmarshall inquiry datain blob");
            ret = -EINVAL;
            goto out;
        }
        memcpy(&iscsilun->lbp, inq_lbp,
               sizeof(struct scsi_inquiry_logical_block_provisioning));
        scsi_free_scsi_task(task);
        task = NULL;
    }

    if (iscsilun->lbp.lbpu || iscsilun->lbp.lbpws) {
        struct scsi_inquiry_block_limits *inq_bl;
        task = iscsi_do_inquiry(iscsilun->iscsi, iscsilun->lun, 1,
                                SCSI_INQUIRY_PAGECODE_BLOCK_LIMITS, errp);
        if (task == NULL) {
            ret = -EINVAL;
            goto out;
        }
        inq_bl = scsi_datain_unmarshall(task);
        if (inq_bl == NULL) {
            error_setg(errp, "iSCSI: failed to unmarshall inquiry datain blob");
            ret = -EINVAL;
            goto out;
        }
        memcpy(&iscsilun->bl, inq_bl,
               sizeof(struct scsi_inquiry_block_limits));
        scsi_free_scsi_task(task);
        task = NULL;
    }

#if defined(LIBISCSI_FEATURE_NOP_COUNTER)
    /* Set up a timer for sending out iSCSI NOPs */
    iscsilun->nop_timer = timer_new_ms(QEMU_CLOCK_REALTIME, iscsi_nop_timed_event, iscsilun);
    timer_mod(iscsilun->nop_timer, qemu_clock_get_ms(QEMU_CLOCK_REALTIME) + NOP_INTERVAL);
#endif

out:
    qemu_opts_del(opts);
    if (initiator_name != NULL) {
        g_free(initiator_name);
    }
    if (iscsi_url != NULL) {
        iscsi_destroy_url(iscsi_url);
    }
    if (task != NULL) {
        scsi_free_scsi_task(task);
    }

    if (ret) {
        if (iscsi != NULL) {
            iscsi_destroy_context(iscsi);
        }
        memset(iscsilun, 0, sizeof(IscsiLun));
    }
    return ret;
}

static void iscsi_close(BlockDriverState *bs)
{
    IscsiLun *iscsilun = bs->opaque;
    struct iscsi_context *iscsi = iscsilun->iscsi;

    if (iscsilun->nop_timer) {
        timer_del(iscsilun->nop_timer);
        timer_free(iscsilun->nop_timer);
    }
    qemu_aio_set_fd_handler(iscsi_get_fd(iscsi), NULL, NULL, NULL);
    iscsi_destroy_context(iscsi);
    g_free(iscsilun->zeroblock);
    memset(iscsilun, 0, sizeof(IscsiLun));
}

static int iscsi_refresh_limits(BlockDriverState *bs)
{
    IscsiLun *iscsilun = bs->opaque;

    /* We don't actually refresh here, but just return data queried in
     * iscsi_open(): iscsi targets don't change their limits. */
    if (iscsilun->lbp.lbpu || iscsilun->lbp.lbpws) {
        if (iscsilun->bl.max_unmap < 0xffffffff) {
            bs->bl.max_discard = sector_lun2qemu(iscsilun->bl.max_unmap,
                                                 iscsilun);
        }
        bs->bl.discard_alignment = sector_lun2qemu(iscsilun->bl.opt_unmap_gran,
                                                   iscsilun);

        if (iscsilun->bl.max_ws_len < 0xffffffff) {
            bs->bl.max_write_zeroes = sector_lun2qemu(iscsilun->bl.max_ws_len,
                                                      iscsilun);
        }
        bs->bl.write_zeroes_alignment = sector_lun2qemu(iscsilun->bl.opt_unmap_gran,
                                                        iscsilun);
    }
    bs->bl.opt_transfer_length = sector_lun2qemu(iscsilun->bl.opt_xfer_len,
                                                 iscsilun);
    return 0;
}

/* Since iscsi_open() ignores bdrv_flags, there is nothing to do here in
 * prepare.  Note that this will not re-establish a connection with an iSCSI
 * target - it is effectively a NOP.  */
static int iscsi_reopen_prepare(BDRVReopenState *state,
                                BlockReopenQueue *queue, Error **errp)
{
    /* NOP */
    return 0;
}

static int iscsi_truncate(BlockDriverState *bs, int64_t offset)
{
    IscsiLun *iscsilun = bs->opaque;
    Error *local_err = NULL;

    if (iscsilun->type != TYPE_DISK) {
        return -ENOTSUP;
    }

    iscsi_readcapacity_sync(iscsilun, &local_err);
    if (local_err != NULL) {
        error_free(local_err);
        return -EIO;
    }

    if (offset > iscsi_getlength(bs)) {
        return -EINVAL;
    }

    return 0;
}

static int iscsi_create(const char *filename, QEMUOptionParameter *options,
                        Error **errp)
{
    int ret = 0;
    int64_t total_size = 0;
    BlockDriverState *bs;
    IscsiLun *iscsilun = NULL;
    QDict *bs_options;

    bs = bdrv_new("");

    /* Read out options */
    while (options && options->name) {
        if (!strcmp(options->name, "size")) {
            total_size = options->value.n / BDRV_SECTOR_SIZE;
        }
        options++;
    }

    bs->opaque = g_malloc0(sizeof(struct IscsiLun));
    iscsilun = bs->opaque;

    bs_options = qdict_new();
    qdict_put(bs_options, "filename", qstring_from_str(filename));
    ret = iscsi_open(bs, bs_options, 0, NULL);
    QDECREF(bs_options);

    if (ret != 0) {
        goto out;
    }
    if (iscsilun->nop_timer) {
        timer_del(iscsilun->nop_timer);
        timer_free(iscsilun->nop_timer);
    }
    if (iscsilun->type != TYPE_DISK) {
        ret = -ENODEV;
        goto out;
    }
    if (bs->total_sectors < total_size) {
        ret = -ENOSPC;
        goto out;
    }

    ret = 0;
out:
    if (iscsilun->iscsi != NULL) {
        iscsi_destroy_context(iscsilun->iscsi);
    }
    g_free(bs->opaque);
    bs->opaque = NULL;
    bdrv_unref(bs);
    return ret;
}

static int iscsi_get_info(BlockDriverState *bs, BlockDriverInfo *bdi)
{
    IscsiLun *iscsilun = bs->opaque;
    bdi->unallocated_blocks_are_zero = !!iscsilun->lbprz;
    bdi->can_write_zeroes_with_unmap = iscsilun->lbprz && iscsilun->lbp.lbpws;
    /* Guess the internal cluster (page) size of the iscsi target by the means
     * of opt_unmap_gran. Transfer the unmap granularity only if it has a
     * reasonable size for bdi->cluster_size */
    if (iscsilun->bl.opt_unmap_gran * iscsilun->block_size >= 64 * 1024 &&
        iscsilun->bl.opt_unmap_gran * iscsilun->block_size <= 16 * 1024 * 1024) {
        bdi->cluster_size = iscsilun->bl.opt_unmap_gran * iscsilun->block_size;
    }
    return 0;
}

static QEMUOptionParameter iscsi_create_options[] = {
    {
        .name = BLOCK_OPT_SIZE,
        .type = OPT_SIZE,
        .help = "Virtual disk size"
    },
    { NULL }
};

static BlockDriver bdrv_iscsi = {
    .format_name     = "iscsi",
    .protocol_name   = "iscsi",

    .instance_size   = sizeof(IscsiLun),
    .bdrv_needs_filename = true,
    .bdrv_file_open  = iscsi_open,
    .bdrv_close      = iscsi_close,
    .bdrv_create     = iscsi_create,
    .create_options  = iscsi_create_options,
    .bdrv_reopen_prepare  = iscsi_reopen_prepare,

    .bdrv_getlength  = iscsi_getlength,
    .bdrv_get_info   = iscsi_get_info,
    .bdrv_truncate   = iscsi_truncate,
    .bdrv_refresh_limits = iscsi_refresh_limits,

#if defined(LIBISCSI_FEATURE_IOVECTOR)
    .bdrv_co_get_block_status = iscsi_co_get_block_status,
#endif
    .bdrv_co_discard      = iscsi_co_discard,
#if defined(SCSI_SENSE_ASCQ_CAPACITY_DATA_HAS_CHANGED)
    .bdrv_co_write_zeroes = iscsi_co_write_zeroes,
#endif
    .bdrv_co_readv         = iscsi_co_readv,
    .bdrv_co_writev        = iscsi_co_writev,
    .bdrv_co_flush_to_disk = iscsi_co_flush,

#ifdef __linux__
    .bdrv_ioctl       = iscsi_ioctl,
    .bdrv_aio_ioctl   = iscsi_aio_ioctl,
#endif
};

static QemuOptsList qemu_iscsi_opts = {
    .name = "iscsi",
    .head = QTAILQ_HEAD_INITIALIZER(qemu_iscsi_opts.head),
    .desc = {
        {
            .name = "user",
            .type = QEMU_OPT_STRING,
            .help = "username for CHAP authentication to target",
        },{
            .name = "password",
            .type = QEMU_OPT_STRING,
            .help = "password for CHAP authentication to target",
        },{
            .name = "header-digest",
            .type = QEMU_OPT_STRING,
            .help = "HeaderDigest setting. "
                    "{CRC32C|CRC32C-NONE|NONE-CRC32C|NONE}",
        },{
            .name = "initiator-name",
            .type = QEMU_OPT_STRING,
            .help = "Initiator iqn name to use when connecting",
        },
        { /* end of list */ }
    },
};

static void iscsi_block_init(void)
{
    bdrv_register(&bdrv_iscsi);
    qemu_add_opts(&qemu_iscsi_opts);
}

block_init(iscsi_block_init);