Introduce Virtio-loopback epsilon release:

Epsilon release introduces a new compatibility layer which make virtio-loopback
design to work with QEMU and rust-vmm vhost-user backend without require any
changes.

Signed-off-by: Timos Ampelikiotis <t.ampelikiotis@virtualopensystems.com>
Change-Id: I52e57563e08a7d0bdc002f8e928ee61ba0c53dd9

1 files changed, 2507 insertions, 0 deletions

diff --git a/block/iscsi.c b/block/iscsi.c
new file mode 100644
index 000000000..57aa07a40
--- /dev/null
+++ b/block/iscsi.c
@@ -0,0 +1,2507 @@
+/*
+ * QEMU Block driver for iSCSI images
+ *
+ * Copyright (c) 2010-2011 Ronnie Sahlberg <ronniesahlberg@gmail.com>
+ * Copyright (c) 2012-2017 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 "qemu/osdep.h"
+
+#include <poll.h>
+#include <math.h>
+#include <arpa/inet.h>
+#include "qemu-common.h"
+#include "qemu/config-file.h"
+#include "qemu/error-report.h"
+#include "qemu/bitops.h"
+#include "qemu/bitmap.h"
+#include "block/block_int.h"
+#include "block/qdict.h"
+#include "scsi/constants.h"
+#include "qemu/iov.h"
+#include "qemu/module.h"
+#include "qemu/option.h"
+#include "qemu/uuid.h"
+#include "sysemu/replay.h"
+#include "qapi/error.h"
+#include "qapi/qapi-commands-machine.h"
+#include "qapi/qmp/qdict.h"
+#include "qapi/qmp/qstring.h"
+#include "crypto/secret.h"
+#include "scsi/utils.h"
+#include "trace.h"
+
+/* Conflict between scsi/utils.h and libiscsi! :( */
+#define SCSI_XFER_NONE ISCSI_XFER_NONE
+#include <iscsi/iscsi.h>
+#define inline __attribute__((gnu_inline))  /* required for libiscsi v1.9.0 */
+#include <iscsi/scsi-lowlevel.h>
+#undef inline
+#undef SCSI_XFER_NONE
+QEMU_BUILD_BUG_ON((int)SCSI_XFER_NONE != (int)ISCSI_XFER_NONE);
+
+#ifdef __linux__
+#include <scsi/sg.h>
+#endif
+
+typedef struct IscsiLun {
+    struct iscsi_context *iscsi;
+    AioContext *aio_context;
+    int lun;
+    enum scsi_inquiry_peripheral_device_type type;
+    int block_size;
+    uint64_t num_blocks;
+    int events;
+    QEMUTimer *nop_timer;
+    QEMUTimer *event_timer;
+    QemuMutex mutex;
+    struct scsi_inquiry_logical_block_provisioning lbp;
+    struct scsi_inquiry_block_limits bl;
+    struct scsi_inquiry_device_designator *dd;
+    unsigned char *zeroblock;
+    /* The allocmap tracks which clusters (pages) on the iSCSI target are
+     * allocated and which are not. In case a target returns zeros for
+     * unallocated pages (iscsilun->lprz) we can directly return zeros instead
+     * of reading zeros over the wire if a read request falls within an
+     * unallocated block. As there are 3 possible states we need 2 bitmaps to
+     * track. allocmap_valid keeps track if QEMU's information about a page is
+     * valid. allocmap tracks if a page is allocated or not. In case QEMU has no
+     * valid information about a page the corresponding allocmap entry should be
+     * switched to unallocated as well to force a new lookup of the allocation
+     * status as lookups are generally skipped if a page is suspect to be
+     * allocated. If a iSCSI target is opened with cache.direct = on the
+     * allocmap_valid does not exist turning all cached information invalid so
+     * that a fresh lookup is made for any page even if allocmap entry returns
+     * it's unallocated. */
+    unsigned long *allocmap;
+    unsigned long *allocmap_valid;
+    long allocmap_size;
+    int cluster_size;
+    bool use_16_for_rw;
+    bool write_protected;
+    bool lbpme;
+    bool lbprz;
+    bool dpofua;
+    bool has_write_same;
+    bool request_timed_out;
+} IscsiLun;
+
+typedef struct IscsiTask {
+    int status;
+    int complete;
+    int retries;
+    int do_retry;
+    struct scsi_task *task;
+    Coroutine *co;
+    IscsiLun *iscsilun;
+    QEMUTimer retry_timer;
+    int err_code;
+    char *err_str;
+} IscsiTask;
+
+typedef struct IscsiAIOCB {
+    BlockAIOCB common;
+    QEMUBH *bh;
+    IscsiLun *iscsilun;
+    struct scsi_task *task;
+    int status;
+    int64_t sector_num;
+    int nb_sectors;
+    int ret;
+#ifdef __linux__
+    sg_io_hdr_t *ioh;
+#endif
+    bool cancelled;
+} IscsiAIOCB;
+
+/* libiscsi uses time_t so its enough to process events every second */
+#define EVENT_INTERVAL 1000
+#define NOP_INTERVAL 5000
+#define MAX_NOP_FAILURES 3
+#define ISCSI_CMD_RETRIES ARRAY_SIZE(iscsi_retry_times)
+static const unsigned iscsi_retry_times[] = {8, 32, 128, 512, 2048, 8192, 32768};
+
+/* this threshold is a trade-off knob to choose between
+ * the potential additional overhead of an extra GET_LBA_STATUS request
+ * vs. unnecessarily reading a lot of zero sectors over the wire.
+ * If a read request is greater or equal than ISCSI_CHECKALLOC_THRES
+ * sectors we check the allocation status of the area covered by the
+ * request first if the allocationmap indicates that the area might be
+ * unallocated. */
+#define ISCSI_CHECKALLOC_THRES 64
+
+#ifdef __linux__
+
+static void
+iscsi_bh_cb(void *p)
+{
+    IscsiAIOCB *acb = p;
+
+    qemu_bh_delete(acb->bh);
+
+    acb->common.cb(acb->common.opaque, acb->status);
+
+    if (acb->task != NULL) {
+        scsi_free_scsi_task(acb->task);
+        acb->task = NULL;
+    }
+
+    qemu_aio_unref(acb);
+}
+
+static void
+iscsi_schedule_bh(IscsiAIOCB *acb)
+{
+    if (acb->bh) {
+        return;
+    }
+    acb->bh = aio_bh_new(acb->iscsilun->aio_context, iscsi_bh_cb, acb);
+    qemu_bh_schedule(acb->bh);
+}
+
+#endif
+
+static void iscsi_co_generic_bh_cb(void *opaque)
+{
+    struct IscsiTask *iTask = opaque;
+
+    iTask->complete = 1;
+    aio_co_wake(iTask->co);
+}
+
+static void iscsi_retry_timer_expired(void *opaque)
+{
+    struct IscsiTask *iTask = opaque;
+    iTask->complete = 1;
+    if (iTask->co) {
+        aio_co_wake(iTask->co);
+    }
+}
+
+static inline unsigned exp_random(double mean)
+{
+    return -mean * log((double)rand() / RAND_MAX);
+}
+
+/* SCSI_SENSE_ASCQ_INVALID_FIELD_IN_PARAMETER_LIST was introduced in
+ * libiscsi 1.10.0, together with other constants we need.  Use it as
+ * a hint that we have to define them ourselves if needed, to keep the
+ * minimum required libiscsi version at 1.9.0.  We use an ASCQ macro for
+ * the test because SCSI_STATUS_* is an enum.
+ *
+ * To guard against future changes where SCSI_SENSE_ASCQ_* also becomes
+ * an enum, check against the LIBISCSI_API_VERSION macro, which was
+ * introduced in 1.11.0.  If it is present, there is no need to define
+ * anything.
+ */
+#if !defined(SCSI_SENSE_ASCQ_INVALID_FIELD_IN_PARAMETER_LIST) && \
+    !defined(LIBISCSI_API_VERSION)
+#define SCSI_STATUS_TASK_SET_FULL                          0x28
+#define SCSI_STATUS_TIMEOUT                                0x0f000002
+#define SCSI_SENSE_ASCQ_INVALID_FIELD_IN_PARAMETER_LIST    0x2600
+#define SCSI_SENSE_ASCQ_PARAMETER_LIST_LENGTH_ERROR        0x1a00
+#endif
+
+#ifndef LIBISCSI_API_VERSION
+#define LIBISCSI_API_VERSION 20130701
+#endif
+
+static int iscsi_translate_sense(struct scsi_sense *sense)
+{
+    return scsi_sense_to_errno(sense->key,
+                               (sense->ascq & 0xFF00) >> 8,
+                               sense->ascq & 0xFF);
+}
+
+/* Called (via iscsi_service) with QemuMutex held.  */
+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->status = status;
+    iTask->do_retry = 0;
+    iTask->err_code = 0;
+    iTask->task = task;
+
+    if (status != SCSI_STATUS_GOOD) {
+        iTask->err_code = -EIO;
+        if (iTask->retries++ < ISCSI_CMD_RETRIES) {
+            if (status == SCSI_STATUS_BUSY ||
+                status == SCSI_STATUS_TIMEOUT ||
+                status == SCSI_STATUS_TASK_SET_FULL) {
+                unsigned retry_time =
+                    exp_random(iscsi_retry_times[iTask->retries - 1]);
+                if (status == SCSI_STATUS_TIMEOUT) {
+                    /* make sure the request is rescheduled AFTER the
+                     * reconnect is initiated */
+                    retry_time = EVENT_INTERVAL * 2;
+                    iTask->iscsilun->request_timed_out = true;
+                }
+                error_report("iSCSI Busy/TaskSetFull/TimeOut"
+                             " (retry #%u in %u ms): %s",
+                             iTask->retries, retry_time,
+                             iscsi_get_error(iscsi));
+                aio_timer_init(iTask->iscsilun->aio_context,
+                               &iTask->retry_timer, QEMU_CLOCK_REALTIME,
+                               SCALE_MS, iscsi_retry_timer_expired, iTask);
+                timer_mod(&iTask->retry_timer,
+                          qemu_clock_get_ms(QEMU_CLOCK_REALTIME) + retry_time);
+                iTask->do_retry = 1;
+            } else if (status == SCSI_STATUS_CHECK_CONDITION) {
+                int error = iscsi_translate_sense(&task->sense);
+                if (error == EAGAIN) {
+                    error_report("iSCSI CheckCondition: %s",
+                                 iscsi_get_error(iscsi));
+                    iTask->do_retry = 1;
+                } else {
+                    iTask->err_code = -error;
+                    iTask->err_str = g_strdup(iscsi_get_error(iscsi));
+                }
+            }
+        }
+    }
+
+    if (iTask->co) {
+        replay_bh_schedule_oneshot_event(iTask->iscsilun->aio_context,
+                                         iscsi_co_generic_bh_cb, iTask);
+    } else {
+        iTask->complete = 1;
+    }
+}
+
+static void iscsi_co_init_iscsitask(IscsiLun *iscsilun, struct IscsiTask *iTask)
+{
+    *iTask = (struct IscsiTask) {
+        .co         = qemu_coroutine_self(),
+        .iscsilun   = iscsilun,
+    };
+}
+
+#ifdef __linux__
+
+/* Called (via iscsi_service) with QemuMutex held. */
+static void
+iscsi_abort_task_cb(struct iscsi_context *iscsi, int status, void *command_data,
+                    void *private_data)
+{
+    IscsiAIOCB *acb = private_data;
+
+    /* If the command callback hasn't been called yet, drop the task */
+    if (!acb->bh) {
+        /* Call iscsi_aio_ioctl_cb() with SCSI_STATUS_CANCELLED */
+        iscsi_scsi_cancel_task(iscsi, acb->task);
+    }
+
+    qemu_aio_unref(acb); /* acquired in iscsi_aio_cancel() */
+}
+
+static void
+iscsi_aio_cancel(BlockAIOCB *blockacb)
+{
+    IscsiAIOCB *acb = (IscsiAIOCB *)blockacb;
+    IscsiLun *iscsilun = acb->iscsilun;
+
+    WITH_QEMU_LOCK_GUARD(&iscsilun->mutex) {
+
+        /* If it was cancelled or completed already, our work is done here */
+        if (acb->cancelled || acb->status != -EINPROGRESS) {
+            return;
+        }
+
+        acb->cancelled = true;
+
+        qemu_aio_ref(acb); /* released in iscsi_abort_task_cb() */
+
+        /* send a task mgmt call to the target to cancel the task on the target */
+        if (iscsi_task_mgmt_abort_task_async(iscsilun->iscsi, acb->task,
+                                             iscsi_abort_task_cb, acb) < 0) {
+            qemu_aio_unref(acb); /* since iscsi_abort_task_cb() won't be called */
+        }
+    }
+}
+
+static const AIOCBInfo iscsi_aiocb_info = {
+    .aiocb_size         = sizeof(IscsiAIOCB),
+    .cancel_async       = iscsi_aio_cancel,
+};
+
+#endif
+
+static void iscsi_process_read(void *arg);
+static void iscsi_process_write(void *arg);
+
+/* Called with QemuMutex held.  */
+static void
+iscsi_set_events(IscsiLun *iscsilun)
+{
+    struct iscsi_context *iscsi = iscsilun->iscsi;
+    int ev = iscsi_which_events(iscsi);
+
+    if (ev != iscsilun->events) {
+        aio_set_fd_handler(iscsilun->aio_context, iscsi_get_fd(iscsi),
+                           false,
+                           (ev & POLLIN) ? iscsi_process_read : NULL,
+                           (ev & POLLOUT) ? iscsi_process_write : NULL,
+                           NULL,
+                           iscsilun);
+        iscsilun->events = ev;
+    }
+}
+
+static void iscsi_timed_check_events(void *opaque)
+{
+    IscsiLun *iscsilun = opaque;
+
+    WITH_QEMU_LOCK_GUARD(&iscsilun->mutex) {
+        /* check for timed out requests */
+        iscsi_service(iscsilun->iscsi, 0);
+
+        if (iscsilun->request_timed_out) {
+            iscsilun->request_timed_out = false;
+            iscsi_reconnect(iscsilun->iscsi);
+        }
+
+        /*
+         * newer versions of libiscsi may return zero events. Ensure we are
+         * able to return to service once this situation changes.
+         */
+        iscsi_set_events(iscsilun);
+    }
+
+    timer_mod(iscsilun->event_timer,
+              qemu_clock_get_ms(QEMU_CLOCK_REALTIME) + EVENT_INTERVAL);
+}
+
+static void
+iscsi_process_read(void *arg)
+{
+    IscsiLun *iscsilun = arg;
+    struct iscsi_context *iscsi = iscsilun->iscsi;
+
+    qemu_mutex_lock(&iscsilun->mutex);
+    iscsi_service(iscsi, POLLIN);
+    iscsi_set_events(iscsilun);
+    qemu_mutex_unlock(&iscsilun->mutex);
+}
+
+static void
+iscsi_process_write(void *arg)
+{
+    IscsiLun *iscsilun = arg;
+    struct iscsi_context *iscsi = iscsilun->iscsi;
+
+    qemu_mutex_lock(&iscsilun->mutex);
+    iscsi_service(iscsi, POLLOUT);
+    iscsi_set_events(iscsilun);
+    qemu_mutex_unlock(&iscsilun->mutex);
+}
+
+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_byte_request_lun_aligned(int64_t offset, int64_t bytes,
+                                        IscsiLun *iscsilun)
+{
+    if (offset % iscsilun->block_size || bytes % iscsilun->block_size) {
+        error_report("iSCSI misaligned request: "
+                     "iscsilun->block_size %u, offset %" PRIi64
+                     ", bytes %" PRIi64,
+                     iscsilun->block_size, offset, bytes);
+        return false;
+    }
+    return true;
+}
+
+static bool is_sector_request_lun_aligned(int64_t sector_num, int nb_sectors,
+                                          IscsiLun *iscsilun)
+{
+    assert(nb_sectors <= BDRV_REQUEST_MAX_SECTORS);
+    return is_byte_request_lun_aligned(sector_num << BDRV_SECTOR_BITS,
+                                       nb_sectors << BDRV_SECTOR_BITS,
+                                       iscsilun);
+}
+
+static void iscsi_allocmap_free(IscsiLun *iscsilun)
+{
+    g_free(iscsilun->allocmap);
+    g_free(iscsilun->allocmap_valid);
+    iscsilun->allocmap = NULL;
+    iscsilun->allocmap_valid = NULL;
+}
+
+
+static int iscsi_allocmap_init(IscsiLun *iscsilun, int open_flags)
+{
+    iscsi_allocmap_free(iscsilun);
+
+    assert(iscsilun->cluster_size);
+    iscsilun->allocmap_size =
+        DIV_ROUND_UP(iscsilun->num_blocks * iscsilun->block_size,
+                     iscsilun->cluster_size);
+
+    iscsilun->allocmap = bitmap_try_new(iscsilun->allocmap_size);
+    if (!iscsilun->allocmap) {
+        return -ENOMEM;
+    }
+
+    if (open_flags & BDRV_O_NOCACHE) {
+        /* when cache.direct = on all allocmap entries are
+         * treated as invalid to force a relookup of the block
+         * status on every read request */
+        return 0;
+    }
+
+    iscsilun->allocmap_valid = bitmap_try_new(iscsilun->allocmap_size);
+    if (!iscsilun->allocmap_valid) {
+        /* if we are under memory pressure free the allocmap as well */
+        iscsi_allocmap_free(iscsilun);
+        return -ENOMEM;
+    }
+
+    return 0;
+}
+
+static void
+iscsi_allocmap_update(IscsiLun *iscsilun, int64_t offset,
+                      int64_t bytes, bool allocated, bool valid)
+{
+    int64_t cl_num_expanded, nb_cls_expanded, cl_num_shrunk, nb_cls_shrunk;
+
+    if (iscsilun->allocmap == NULL) {
+        return;
+    }
+    /* expand to entirely contain all affected clusters */
+    assert(iscsilun->cluster_size);
+    cl_num_expanded = offset / iscsilun->cluster_size;
+    nb_cls_expanded = DIV_ROUND_UP(offset + bytes,
+                                   iscsilun->cluster_size) - cl_num_expanded;
+    /* shrink to touch only completely contained clusters */
+    cl_num_shrunk = DIV_ROUND_UP(offset, iscsilun->cluster_size);
+    nb_cls_shrunk = (offset + bytes) / iscsilun->cluster_size - cl_num_shrunk;
+    if (allocated) {
+        bitmap_set(iscsilun->allocmap, cl_num_expanded, nb_cls_expanded);
+    } else {
+        if (nb_cls_shrunk > 0) {
+            bitmap_clear(iscsilun->allocmap, cl_num_shrunk, nb_cls_shrunk);
+        }
+    }
+
+    if (iscsilun->allocmap_valid == NULL) {
+        return;
+    }
+    if (valid) {
+        if (nb_cls_shrunk > 0) {
+            bitmap_set(iscsilun->allocmap_valid, cl_num_shrunk, nb_cls_shrunk);
+        }
+    } else {
+        bitmap_clear(iscsilun->allocmap_valid, cl_num_expanded,
+                     nb_cls_expanded);
+    }
+}
+
+static void
+iscsi_allocmap_set_allocated(IscsiLun *iscsilun, int64_t offset,
+                             int64_t bytes)
+{
+    iscsi_allocmap_update(iscsilun, offset, bytes, true, true);
+}
+
+static void
+iscsi_allocmap_set_unallocated(IscsiLun *iscsilun, int64_t offset,
+                               int64_t bytes)
+{
+    /* Note: if cache.direct=on the fifth argument to iscsi_allocmap_update
+     * is ignored, so this will in effect be an iscsi_allocmap_set_invalid.
+     */
+    iscsi_allocmap_update(iscsilun, offset, bytes, false, true);
+}
+
+static void iscsi_allocmap_set_invalid(IscsiLun *iscsilun, int64_t offset,
+                                       int64_t bytes)
+{
+    iscsi_allocmap_update(iscsilun, offset, bytes, false, false);
+}
+
+static void iscsi_allocmap_invalidate(IscsiLun *iscsilun)
+{
+    if (iscsilun->allocmap) {
+        bitmap_zero(iscsilun->allocmap, iscsilun->allocmap_size);
+    }
+    if (iscsilun->allocmap_valid) {
+        bitmap_zero(iscsilun->allocmap_valid, iscsilun->allocmap_size);
+    }
+}
+
+static inline bool
+iscsi_allocmap_is_allocated(IscsiLun *iscsilun, int64_t offset,
+                            int64_t bytes)
+{
+    unsigned long size;
+    if (iscsilun->allocmap == NULL) {
+        return true;
+    }
+    assert(iscsilun->cluster_size);
+    size = DIV_ROUND_UP(offset + bytes, iscsilun->cluster_size);
+    return !(find_next_bit(iscsilun->allocmap, size,
+                           offset / iscsilun->cluster_size) == size);
+}
+
+static inline bool iscsi_allocmap_is_valid(IscsiLun *iscsilun,
+                                           int64_t offset, int64_t bytes)
+{
+    unsigned long size;
+    if (iscsilun->allocmap_valid == NULL) {
+        return false;
+    }
+    assert(iscsilun->cluster_size);
+    size = DIV_ROUND_UP(offset + bytes, iscsilun->cluster_size);
+    return (find_next_zero_bit(iscsilun->allocmap_valid, size,
+                               offset / iscsilun->cluster_size) == size);
+}
+
+static void coroutine_fn iscsi_co_wait_for_task(IscsiTask *iTask,
+                                                IscsiLun *iscsilun)
+{
+    while (!iTask->complete) {
+        iscsi_set_events(iscsilun);
+        qemu_mutex_unlock(&iscsilun->mutex);
+        qemu_coroutine_yield();
+        qemu_mutex_lock(&iscsilun->mutex);
+    }
+}
+
+static int coroutine_fn
+iscsi_co_writev(BlockDriverState *bs, int64_t sector_num, int nb_sectors,
+                QEMUIOVector *iov, int flags)
+{
+    IscsiLun *iscsilun = bs->opaque;
+    struct IscsiTask iTask;
+    uint64_t lba;
+    uint32_t num_sectors;
+    bool fua = flags & BDRV_REQ_FUA;
+    int r = 0;
+
+    if (fua) {
+        assert(iscsilun->dpofua);
+    }
+    if (!is_sector_request_lun_aligned(sector_num, nb_sectors, iscsilun)) {
+        return -EINVAL;
+    }
+
+    if (bs->bl.max_transfer) {
+        assert(nb_sectors << BDRV_SECTOR_BITS <= bs->bl.max_transfer);
+    }
+
+    lba = sector_qemu2lun(sector_num, iscsilun);
+    num_sectors = sector_qemu2lun(nb_sectors, iscsilun);
+    iscsi_co_init_iscsitask(iscsilun, &iTask);
+    qemu_mutex_lock(&iscsilun->mutex);
+retry:
+    if (iscsilun->use_16_for_rw) {
+#if LIBISCSI_API_VERSION >= (20160603)
+        iTask.task = iscsi_write16_iov_task(iscsilun->iscsi, iscsilun->lun, lba,
+                                            NULL, num_sectors * iscsilun->block_size,
+                                            iscsilun->block_size, 0, 0, fua, 0, 0,
+                                            iscsi_co_generic_cb, &iTask,
+                                            (struct scsi_iovec *)iov->iov, iov->niov);
+    } else {
+        iTask.task = iscsi_write10_iov_task(iscsilun->iscsi, iscsilun->lun, lba,
+                                            NULL, num_sectors * iscsilun->block_size,
+                                            iscsilun->block_size, 0, 0, fua, 0, 0,
+                                            iscsi_co_generic_cb, &iTask,
+                                            (struct scsi_iovec *)iov->iov, iov->niov);
+    }
+#else
+        iTask.task = iscsi_write16_task(iscsilun->iscsi, iscsilun->lun, lba,
+                                        NULL, num_sectors * iscsilun->block_size,
+                                        iscsilun->block_size, 0, 0, fua, 0, 0,
+                                        iscsi_co_generic_cb, &iTask);
+    } else {
+        iTask.task = iscsi_write10_task(iscsilun->iscsi, iscsilun->lun, lba,
+                                        NULL, num_sectors * iscsilun->block_size,
+                                        iscsilun->block_size, 0, 0, fua, 0, 0,
+                                        iscsi_co_generic_cb, &iTask);
+    }
+#endif
+    if (iTask.task == NULL) {
+        qemu_mutex_unlock(&iscsilun->mutex);
+        return -ENOMEM;
+    }
+#if LIBISCSI_API_VERSION < (20160603)
+    scsi_task_set_iov_out(iTask.task, (struct scsi_iovec *) iov->iov,
+                          iov->niov);
+#endif
+    iscsi_co_wait_for_task(&iTask, iscsilun);
+
+    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) {
+        iscsi_allocmap_set_invalid(iscsilun, sector_num * BDRV_SECTOR_SIZE,
+                                   nb_sectors * BDRV_SECTOR_SIZE);
+        error_report("iSCSI WRITE10/16 failed at lba %" PRIu64 ": %s", lba,
+                     iTask.err_str);
+        r = iTask.err_code;
+        goto out_unlock;
+    }
+
+    iscsi_allocmap_set_allocated(iscsilun, sector_num * BDRV_SECTOR_SIZE,
+                                 nb_sectors * BDRV_SECTOR_SIZE);
+
+out_unlock:
+    qemu_mutex_unlock(&iscsilun->mutex);
+    g_free(iTask.err_str);
+    return r;
+}
+
+
+
+static int coroutine_fn iscsi_co_block_status(BlockDriverState *bs,
+                                              bool want_zero, int64_t offset,
+                                              int64_t bytes, int64_t *pnum,
+                                              int64_t *map,
+                                              BlockDriverState **file)
+{
+    IscsiLun *iscsilun = bs->opaque;
+    struct scsi_get_lba_status *lbas = NULL;
+    struct scsi_lba_status_descriptor *lbasd = NULL;
+    struct IscsiTask iTask;
+    uint64_t lba, max_bytes;
+    int ret;
+
+    iscsi_co_init_iscsitask(iscsilun, &iTask);
+
+    assert(QEMU_IS_ALIGNED(offset | bytes, iscsilun->block_size));
+
+    /* default to all sectors allocated */
+    ret = BDRV_BLOCK_DATA | BDRV_BLOCK_OFFSET_VALID;
+    if (map) {
+        *map = offset;
+    }
+    *pnum = bytes;
+
+    /* LUN does not support logical block provisioning */
+    if (!iscsilun->lbpme) {
+        goto out;
+    }
+
+    lba = offset / iscsilun->block_size;
+    max_bytes = (iscsilun->num_blocks - lba) * iscsilun->block_size;
+
+    qemu_mutex_lock(&iscsilun->mutex);
+retry:
+    if (iscsi_get_lba_status_task(iscsilun->iscsi, iscsilun->lun,
+                                  lba, 8 + 16, iscsi_co_generic_cb,
+                                  &iTask) == NULL) {
+        ret = -ENOMEM;
+        goto out_unlock;
+    }
+    iscsi_co_wait_for_task(&iTask, iscsilun);
+
+    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 */
+        error_report("iSCSI GET_LBA_STATUS failed at lba %" PRIu64 ": %s",
+                     lba, iTask.err_str);
+        goto out_unlock;
+    }
+
+    lbas = scsi_datain_unmarshall(iTask.task);
+    if (lbas == NULL || lbas->num_descriptors == 0) {
+        ret = -EIO;
+        goto out_unlock;
+    }
+
+    lbasd = &lbas->descriptors[0];
+
+    if (lba != lbasd->lba) {
+        ret = -EIO;
+        goto out_unlock;
+    }
+
+    *pnum = MIN((int64_t) lbasd->num_blocks * iscsilun->block_size, max_bytes);
+
+    if (lbasd->provisioning == SCSI_PROVISIONING_TYPE_DEALLOCATED ||
+        lbasd->provisioning == SCSI_PROVISIONING_TYPE_ANCHORED) {
+        ret &= ~BDRV_BLOCK_DATA;
+        if (iscsilun->lbprz) {
+            ret |= BDRV_BLOCK_ZERO;
+        }
+    }
+
+    if (ret & BDRV_BLOCK_ZERO) {
+        iscsi_allocmap_set_unallocated(iscsilun, offset, *pnum);
+    } else {
+        iscsi_allocmap_set_allocated(iscsilun, offset, *pnum);
+    }
+
+out_unlock:
+    qemu_mutex_unlock(&iscsilun->mutex);
+    g_free(iTask.err_str);
+out:
+    if (iTask.task != NULL) {
+        scsi_free_scsi_task(iTask.task);
+    }
+    if (ret > 0 && ret & BDRV_BLOCK_OFFSET_VALID && file) {
+        *file = bs;
+    }
+    return ret;
+}
+
+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;
+    int r = 0;
+
+    if (!is_sector_request_lun_aligned(sector_num, nb_sectors, iscsilun)) {
+        return -EINVAL;
+    }
+
+    if (bs->bl.max_transfer) {
+        assert(nb_sectors << BDRV_SECTOR_BITS <= bs->bl.max_transfer);
+    }
+
+    /* if cache.direct is off and we have a valid entry in our allocation map
+     * we can skip checking the block status and directly return zeroes if
+     * the request falls within an unallocated area */
+    if (iscsi_allocmap_is_valid(iscsilun, sector_num * BDRV_SECTOR_SIZE,
+                                nb_sectors * BDRV_SECTOR_SIZE) &&
+        !iscsi_allocmap_is_allocated(iscsilun, sector_num * BDRV_SECTOR_SIZE,
+                                     nb_sectors * BDRV_SECTOR_SIZE)) {
+            qemu_iovec_memset(iov, 0, 0x00, iov->size);
+            return 0;
+    }
+
+    if (nb_sectors >= ISCSI_CHECKALLOC_THRES &&
+        !iscsi_allocmap_is_valid(iscsilun, sector_num * BDRV_SECTOR_SIZE,
+                                 nb_sectors * BDRV_SECTOR_SIZE) &&
+        !iscsi_allocmap_is_allocated(iscsilun, sector_num * BDRV_SECTOR_SIZE,
+                                     nb_sectors * BDRV_SECTOR_SIZE)) {
+        int64_t pnum;
+        /* check the block status from the beginning of the cluster
+         * containing the start sector */
+        int64_t head;
+        int ret;
+
+        assert(iscsilun->cluster_size);
+        head = (sector_num * BDRV_SECTOR_SIZE) % iscsilun->cluster_size;
+        ret = iscsi_co_block_status(bs, true,
+                                    sector_num * BDRV_SECTOR_SIZE - head,
+                                    BDRV_REQUEST_MAX_BYTES, &pnum, NULL, NULL);
+        if (ret < 0) {
+            return ret;
+        }
+        /* if the whole request falls into an unallocated area we can avoid
+         * reading and directly return zeroes instead */
+        if (ret & BDRV_BLOCK_ZERO &&
+            pnum >= nb_sectors * BDRV_SECTOR_SIZE + head) {
+            qemu_iovec_memset(iov, 0, 0x00, iov->size);
+            return 0;
+        }
+    }
+
+    lba = sector_qemu2lun(sector_num, iscsilun);
+    num_sectors = sector_qemu2lun(nb_sectors, iscsilun);
+
+    iscsi_co_init_iscsitask(iscsilun, &iTask);
+    qemu_mutex_lock(&iscsilun->mutex);
+retry:
+    if (iscsilun->use_16_for_rw) {
+#if LIBISCSI_API_VERSION >= (20160603)
+        iTask.task = iscsi_read16_iov_task(iscsilun->iscsi, iscsilun->lun, lba,
+                                           num_sectors * iscsilun->block_size,
+                                           iscsilun->block_size, 0, 0, 0, 0, 0,
+                                           iscsi_co_generic_cb, &iTask,
+                                           (struct scsi_iovec *)iov->iov, iov->niov);
+    } else {
+        iTask.task = iscsi_read10_iov_task(iscsilun->iscsi, iscsilun->lun, lba,
+                                           num_sectors * iscsilun->block_size,
+                                           iscsilun->block_size,
+                                           0, 0, 0, 0, 0,
+                                           iscsi_co_generic_cb, &iTask,
+                                           (struct scsi_iovec *)iov->iov, iov->niov);
+    }
+#else
+        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);
+    } else {
+        iTask.task = iscsi_read10_task(iscsilun->iscsi, iscsilun->lun, lba,
+                                       num_sectors * iscsilun->block_size,
+                                       iscsilun->block_size,
+                                       0, 0, 0, 0, 0,
+                                       iscsi_co_generic_cb, &iTask);
+    }
+#endif
+    if (iTask.task == NULL) {
+        qemu_mutex_unlock(&iscsilun->mutex);
+        return -ENOMEM;
+    }
+#if LIBISCSI_API_VERSION < (20160603)
+    scsi_task_set_iov_in(iTask.task, (struct scsi_iovec *) iov->iov, iov->niov);
+#endif
+
+    iscsi_co_wait_for_task(&iTask, iscsilun);
+    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) {
+        error_report("iSCSI READ10/16 failed at lba %" PRIu64 ": %s",
+                     lba, iTask.err_str);
+        r = iTask.err_code;
+    }
+
+    qemu_mutex_unlock(&iscsilun->mutex);
+    g_free(iTask.err_str);
+    return r;
+}
+
+static int coroutine_fn iscsi_co_flush(BlockDriverState *bs)
+{
+    IscsiLun *iscsilun = bs->opaque;
+    struct IscsiTask iTask;
+    int r = 0;
+
+    iscsi_co_init_iscsitask(iscsilun, &iTask);
+    qemu_mutex_lock(&iscsilun->mutex);
+retry:
+    if (iscsi_synchronizecache10_task(iscsilun->iscsi, iscsilun->lun, 0, 0, 0,
+                                      0, iscsi_co_generic_cb, &iTask) == NULL) {
+        qemu_mutex_unlock(&iscsilun->mutex);
+        return -ENOMEM;
+    }
+
+    iscsi_co_wait_for_task(&iTask, iscsilun);
+
+    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) {
+        error_report("iSCSI SYNCHRONIZECACHE10 failed: %s", iTask.err_str);
+        r = iTask.err_code;
+    }
+
+    qemu_mutex_unlock(&iscsilun->mutex);
+    g_free(iTask.err_str);
+    return r;
+}
+
+#ifdef __linux__
+/* Called (via iscsi_service) with QemuMutex held.  */
+static void
+iscsi_aio_ioctl_cb(struct iscsi_context *iscsi, int status,
+                     void *command_data, void *opaque)
+{
+    IscsiAIOCB *acb = opaque;
+
+    if (status == SCSI_STATUS_CANCELLED) {
+        if (!acb->bh) {
+            acb->status = -ECANCELED;
+            iscsi_schedule_bh(acb);
+        }
+        return;
+    }
+
+    acb->status = 0;
+    if (status < 0) {
+        error_report("Failed to ioctl(SG_IO) to iSCSI lun. %s",
+                     iscsi_get_error(iscsi));
+        acb->status = -iscsi_translate_sense(&acb->task->sense);
+    }
+
+    acb->ioh->driver_status = 0;
+    acb->ioh->host_status   = 0;
+    acb->ioh->resid         = 0;
+    acb->ioh->status        = status;
+
+#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 = MIN(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 void iscsi_ioctl_bh_completion(void *opaque)
+{
+    IscsiAIOCB *acb = opaque;
+
+    qemu_bh_delete(acb->bh);
+    acb->common.cb(acb->common.opaque, acb->ret);
+    qemu_aio_unref(acb);
+}
+
+static void iscsi_ioctl_handle_emulated(IscsiAIOCB *acb, int req, void *buf)
+{
+    BlockDriverState *bs = acb->common.bs;
+    IscsiLun *iscsilun = bs->opaque;
+    int ret = 0;
+
+    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;
+    default:
+        ret = -EINVAL;
+    }
+    assert(!acb->bh);
+    acb->bh = aio_bh_new(bdrv_get_aio_context(bs),
+                         iscsi_ioctl_bh_completion, acb);
+    acb->ret = ret;
+    qemu_bh_schedule(acb->bh);
+}
+
+static BlockAIOCB *iscsi_aio_ioctl(BlockDriverState *bs,
+        unsigned long int req, void *buf,
+        BlockCompletionFunc *cb, void *opaque)
+{
+    IscsiLun *iscsilun = bs->opaque;
+    struct iscsi_context *iscsi = iscsilun->iscsi;
+    struct iscsi_data data;
+    IscsiAIOCB *acb;
+
+    acb = qemu_aio_get(&iscsi_aiocb_info, bs, cb, opaque);
+
+    acb->iscsilun = iscsilun;
+    acb->bh          = NULL;
+    acb->status      = -EINPROGRESS;
+    acb->ioh         = buf;
+    acb->cancelled   = false;
+
+    if (req != SG_IO) {
+        iscsi_ioctl_handle_emulated(acb, req, buf);
+        return &acb->common;
+    }
+
+    if (acb->ioh->cmd_len > SCSI_CDB_MAX_SIZE) {
+        error_report("iSCSI: ioctl error CDB exceeds max size (%d > %d)",
+                     acb->ioh->cmd_len, SCSI_CDB_MAX_SIZE);
+        qemu_aio_unref(acb);
+        return NULL;
+    }
+
+    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_unref(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;
+    qemu_mutex_lock(&iscsilun->mutex);
+    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 {
+            scsi_task_set_iov_out(acb->task,
+                                 (struct scsi_iovec *) acb->ioh->dxferp,
+                                 acb->ioh->iovec_count);
+        }
+    }
+
+    if (iscsi_scsi_command_async(iscsi, iscsilun->lun, acb->task,
+                                 iscsi_aio_ioctl_cb,
+                                 (data.size > 0) ? &data : NULL,
+                                 acb) != 0) {
+        qemu_mutex_unlock(&iscsilun->mutex);
+        scsi_free_scsi_task(acb->task);
+        qemu_aio_unref(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 {
+            scsi_task_set_iov_in(acb->task,
+                                 (struct scsi_iovec *) acb->ioh->dxferp,
+                                 acb->ioh->iovec_count);
+        }
+    }
+
+    iscsi_set_events(iscsilun);
+    qemu_mutex_unlock(&iscsilun->mutex);
+
+    return &acb->common;
+}
+
+#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;
+}
+
+static int
+coroutine_fn iscsi_co_pdiscard(BlockDriverState *bs, int64_t offset,
+                               int64_t bytes)
+{
+    IscsiLun *iscsilun = bs->opaque;
+    struct IscsiTask iTask;
+    struct unmap_list list;
+    int r = 0;
+
+    if (!is_byte_request_lun_aligned(offset, bytes, iscsilun)) {
+        return -ENOTSUP;
+    }
+
+    if (!iscsilun->lbp.lbpu) {
+        /* UNMAP is not supported by the target */
+        return 0;
+    }
+
+    /*
+     * We don't want to overflow list.num which is uint32_t.
+     * We rely on our max_pdiscard.
+     */
+    assert(bytes / iscsilun->block_size <= UINT32_MAX);
+
+    list.lba = offset / iscsilun->block_size;
+    list.num = bytes / iscsilun->block_size;
+
+    iscsi_co_init_iscsitask(iscsilun, &iTask);
+    qemu_mutex_lock(&iscsilun->mutex);
+retry:
+    if (iscsi_unmap_task(iscsilun->iscsi, iscsilun->lun, 0, 0, &list, 1,
+                         iscsi_co_generic_cb, &iTask) == NULL) {
+        r = -ENOMEM;
+        goto out_unlock;
+    }
+
+    iscsi_co_wait_for_task(&iTask, iscsilun);
+
+    if (iTask.task != NULL) {
+        scsi_free_scsi_task(iTask.task);
+        iTask.task = NULL;
+    }
+
+    if (iTask.do_retry) {
+        iTask.complete = 0;
+        goto retry;
+    }
+
+    iscsi_allocmap_set_invalid(iscsilun, offset, bytes);
+
+    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 */
+        goto out_unlock;
+    }
+
+    if (iTask.status != SCSI_STATUS_GOOD) {
+        error_report("iSCSI UNMAP failed at lba %" PRIu64 ": %s",
+                     list.lba, iTask.err_str);
+        r = iTask.err_code;
+        goto out_unlock;
+    }
+
+out_unlock:
+    qemu_mutex_unlock(&iscsilun->mutex);
+    g_free(iTask.err_str);
+    return r;
+}
+
+static int
+coroutine_fn iscsi_co_pwrite_zeroes(BlockDriverState *bs, int64_t offset,
+                                    int64_t bytes, BdrvRequestFlags flags)
+{
+    IscsiLun *iscsilun = bs->opaque;
+    struct IscsiTask iTask;
+    uint64_t lba;
+    uint64_t nb_blocks;
+    bool use_16_for_ws = iscsilun->use_16_for_rw;
+    int r = 0;
+
+    if (!is_byte_request_lun_aligned(offset, bytes, iscsilun)) {
+        return -ENOTSUP;
+    }
+
+    if (flags & BDRV_REQ_MAY_UNMAP) {
+        if (!use_16_for_ws && !iscsilun->lbp.lbpws10) {
+            /* WRITESAME10 with UNMAP is unsupported try WRITESAME16 */
+            use_16_for_ws = true;
+        }
+        if (use_16_for_ws && !iscsilun->lbp.lbpws) {
+            /* WRITESAME16 with UNMAP is not supported by the target,
+             * fall back and try WRITESAME10/16 without UNMAP */
+            flags &= ~BDRV_REQ_MAY_UNMAP;
+            use_16_for_ws = iscsilun->use_16_for_rw;
+        }
+    }
+
+    if (!(flags & BDRV_REQ_MAY_UNMAP) && !iscsilun->has_write_same) {
+        /* WRITESAME without UNMAP is not supported by the target */
+        return -ENOTSUP;
+    }
+
+    lba = offset / iscsilun->block_size;
+    nb_blocks = bytes / iscsilun->block_size;
+
+    if (iscsilun->zeroblock == NULL) {
+        iscsilun->zeroblock = g_try_malloc0(iscsilun->block_size);
+        if (iscsilun->zeroblock == NULL) {
+            return -ENOMEM;
+        }
+    }
+
+    qemu_mutex_lock(&iscsilun->mutex);
+    iscsi_co_init_iscsitask(iscsilun, &iTask);
+retry:
+    if (use_16_for_ws) {
+        /*
+         * iscsi_writesame16_task num_blocks argument is uint32_t. We rely here
+         * on our max_pwrite_zeroes limit.
+         */
+        assert(nb_blocks <= UINT32_MAX);
+        iTask.task = 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);
+    } else {
+        /*
+         * iscsi_writesame10_task num_blocks argument is uint16_t. We rely here
+         * on our max_pwrite_zeroes limit.
+         */
+        assert(nb_blocks <= UINT16_MAX);
+        iTask.task = iscsi_writesame10_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);
+    }
+    if (iTask.task == NULL) {
+        qemu_mutex_unlock(&iscsilun->mutex);
+        return -ENOMEM;
+    }
+
+    iscsi_co_wait_for_task(&iTask, iscsilun);
+
+    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 ||
+         iTask.task->sense.ascq == SCSI_SENSE_ASCQ_INVALID_FIELD_IN_CDB)) {
+        /* WRITE SAME is not supported by the target */
+        iscsilun->has_write_same = false;
+        scsi_free_scsi_task(iTask.task);
+        r = -ENOTSUP;
+        goto out_unlock;
+    }
+
+    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) {
+        iscsi_allocmap_set_invalid(iscsilun, offset, bytes);
+        error_report("iSCSI WRITESAME10/16 failed at lba %" PRIu64 ": %s",
+                     lba, iTask.err_str);
+        r = iTask.err_code;
+        goto out_unlock;
+    }
+
+    if (flags & BDRV_REQ_MAY_UNMAP) {
+        iscsi_allocmap_set_invalid(iscsilun, offset, bytes);
+    } else {
+        iscsi_allocmap_set_allocated(iscsilun, offset, bytes);
+    }
+
+out_unlock:
+    qemu_mutex_unlock(&iscsilun->mutex);
+    g_free(iTask.err_str);
+    return r;
+}
+
+static void apply_chap(struct iscsi_context *iscsi, QemuOpts *opts,
+                       Error **errp)
+{
+    const char *user = NULL;
+    const char *password = NULL;
+    const char *secretid;
+    char *secret = NULL;
+
+    user = qemu_opt_get(opts, "user");
+    if (!user) {
+        return;
+    }
+
+    secretid = qemu_opt_get(opts, "password-secret");
+    password = qemu_opt_get(opts, "password");
+    if (secretid && password) {
+        error_setg(errp, "'password' and 'password-secret' properties are "
+                   "mutually exclusive");
+        return;
+    }
+    if (secretid) {
+        secret = qcrypto_secret_lookup_as_utf8(secretid, errp);
+        if (!secret) {
+            return;
+        }
+        password = secret;
+    } else 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");
+    }
+
+    g_free(secret);
+}
+
+static void apply_header_digest(struct iscsi_context *iscsi, QemuOpts *opts,
+                                Error **errp)
+{
+    const char *digest = NULL;
+
+    digest = qemu_opt_get(opts, "header-digest");
+    if (!digest) {
+        iscsi_set_header_digest(iscsi, ISCSI_HEADER_DIGEST_NONE_CRC32C);
+    } else 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 *get_initiator_name(QemuOpts *opts)
+{
+    const char *name;
+    char *iscsi_name;
+    UuidInfo *uuid_info;
+
+    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;
+}
+
+static void iscsi_nop_timed_event(void *opaque)
+{
+    IscsiLun *iscsilun = opaque;
+
+    QEMU_LOCK_GUARD(&iscsilun->mutex);
+    if (iscsi_get_nops_in_flight(iscsilun->iscsi) >= MAX_NOP_FAILURES) {
+        error_report("iSCSI: NOP timeout. Reconnecting...");
+        iscsilun->request_timed_out = true;
+    } else 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);
+}
+
+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;
+                    iscsilun->use_16_for_rw = (rc16->returned_lba > 0xffffffff);
+                }
+                break;
+            }
+            if (task != NULL && task->status == SCSI_STATUS_CHECK_CONDITION
+                && task->sense.key == SCSI_SENSE_UNIT_ATTENTION) {
+                break;
+            }
+            /* Fall through and try READ CAPACITY(10) instead.  */
+        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 readcapacity10/16 command");
+    } else if (!iscsilun->block_size ||
+               iscsilun->block_size % BDRV_SECTOR_SIZE) {
+        error_setg(errp, "iSCSI: the target returned an invalid "
+                   "block size of %d.", iscsilun->block_size);
+    }
+    if (task) {
+        scsi_free_scsi_task(task);
+    }
+}
+
+static struct scsi_task *iscsi_do_inquiry(struct iscsi_context *iscsi, int lun,
+                                          int evpd, int pc, void **inq, 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;
+        }
+    }
+
+    *inq = scsi_datain_unmarshall(task);
+    if (*inq == NULL) {
+        error_setg(errp, "iSCSI: failed to unmarshall inquiry datain blob");
+        goto fail_with_err;
+    }
+
+    return task;
+
+fail:
+    error_setg(errp, "iSCSI: Inquiry command failed : %s",
+               iscsi_get_error(iscsi));
+fail_with_err:
+    if (task != NULL) {
+        scsi_free_scsi_task(task);
+    }
+    return NULL;
+}
+
+static void iscsi_detach_aio_context(BlockDriverState *bs)
+{
+    IscsiLun *iscsilun = bs->opaque;
+
+    aio_set_fd_handler(iscsilun->aio_context, iscsi_get_fd(iscsilun->iscsi),
+                       false, NULL, NULL, NULL, NULL);
+    iscsilun->events = 0;
+
+    if (iscsilun->nop_timer) {
+        timer_free(iscsilun->nop_timer);
+        iscsilun->nop_timer = NULL;
+    }
+    if (iscsilun->event_timer) {
+        timer_free(iscsilun->event_timer);
+        iscsilun->event_timer = NULL;
+    }
+}
+
+static void iscsi_attach_aio_context(BlockDriverState *bs,
+                                     AioContext *new_context)
+{
+    IscsiLun *iscsilun = bs->opaque;
+
+    iscsilun->aio_context = new_context;
+    iscsi_set_events(iscsilun);
+
+    /* Set up a timer for sending out iSCSI NOPs */
+    iscsilun->nop_timer = aio_timer_new(iscsilun->aio_context,
+                                        QEMU_CLOCK_REALTIME, SCALE_MS,
+                                        iscsi_nop_timed_event, iscsilun);
+    timer_mod(iscsilun->nop_timer,
+              qemu_clock_get_ms(QEMU_CLOCK_REALTIME) + NOP_INTERVAL);
+
+    /* Set up a timer for periodic calls to iscsi_set_events and to
+     * scan for command timeout */
+    iscsilun->event_timer = aio_timer_new(iscsilun->aio_context,
+                                          QEMU_CLOCK_REALTIME, SCALE_MS,
+                                          iscsi_timed_check_events, iscsilun);
+    timer_mod(iscsilun->event_timer,
+              qemu_clock_get_ms(QEMU_CLOCK_REALTIME) + EVENT_INTERVAL);
+}
+
+static void iscsi_modesense_sync(IscsiLun *iscsilun)
+{
+    struct scsi_task *task;
+    struct scsi_mode_sense *ms = NULL;
+    iscsilun->write_protected = false;
+    iscsilun->dpofua = false;
+
+    task = iscsi_modesense6_sync(iscsilun->iscsi, iscsilun->lun,
+                                 1, SCSI_MODESENSE_PC_CURRENT,
+                                 0x3F, 0, 255);
+    if (task == NULL) {
+        error_report("iSCSI: Failed to send MODE_SENSE(6) command: %s",
+                     iscsi_get_error(iscsilun->iscsi));
+        goto out;
+    }
+
+    if (task->status != SCSI_STATUS_GOOD) {
+        error_report("iSCSI: Failed MODE_SENSE(6), LUN assumed writable");
+        goto out;
+    }
+    ms = scsi_datain_unmarshall(task);
+    if (!ms) {
+        error_report("iSCSI: Failed to unmarshall MODE_SENSE(6) data: %s",
+                     iscsi_get_error(iscsilun->iscsi));
+        goto out;
+    }
+    iscsilun->write_protected = ms->device_specific_parameter & 0x80;
+    iscsilun->dpofua          = ms->device_specific_parameter & 0x10;
+
+out:
+    if (task) {
+        scsi_free_scsi_task(task);
+    }
+}
+
+static void iscsi_parse_iscsi_option(const char *target, QDict *options)
+{
+    QemuOptsList *list;
+    QemuOpts *opts;
+    const char *user, *password, *password_secret, *initiator_name,
+               *header_digest, *timeout;
+
+    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) {
+        qdict_set_default_str(options, "user", user);
+    }
+
+    password = qemu_opt_get(opts, "password");
+    if (password) {
+        qdict_set_default_str(options, "password", password);
+    }
+
+    password_secret = qemu_opt_get(opts, "password-secret");
+    if (password_secret) {
+        qdict_set_default_str(options, "password-secret", password_secret);
+    }
+
+    initiator_name = qemu_opt_get(opts, "initiator-name");
+    if (initiator_name) {
+        qdict_set_default_str(options, "initiator-name", initiator_name);
+    }
+
+    header_digest = qemu_opt_get(opts, "header-digest");
+    if (header_digest) {
+        /* -iscsi takes upper case values, but QAPI only supports lower case
+         * enum constant names, so we have to convert here. */
+        char *qapi_value = g_ascii_strdown(header_digest, -1);
+        qdict_set_default_str(options, "header-digest", qapi_value);
+        g_free(qapi_value);
+    }
+
+    timeout = qemu_opt_get(opts, "timeout");
+    if (timeout) {
+        qdict_set_default_str(options, "timeout", timeout);
+    }
+}
+
+/*
+ * We support iscsi url's on the form
+ * iscsi://[<username>%<password>@]<host>[:<port>]/<targetname>/<lun>
+ */
+static void iscsi_parse_filename(const char *filename, QDict *options,
+                                 Error **errp)
+{
+    struct iscsi_url *iscsi_url;
+    const char *transport_name;
+    char *lun_str;
+
+    iscsi_url = iscsi_parse_full_url(NULL, filename);
+    if (iscsi_url == NULL) {
+        error_setg(errp, "Failed to parse URL : %s", filename);
+        return;
+    }
+
+#if LIBISCSI_API_VERSION >= (20160603)
+    switch (iscsi_url->transport) {
+    case TCP_TRANSPORT:
+        transport_name = "tcp";
+        break;
+    case ISER_TRANSPORT:
+        transport_name = "iser";
+        break;
+    default:
+        error_setg(errp, "Unknown transport type (%d)",
+                   iscsi_url->transport);
+        return;
+    }
+#else
+    transport_name = "tcp";
+#endif
+
+    qdict_set_default_str(options, "transport", transport_name);
+    qdict_set_default_str(options, "portal", iscsi_url->portal);
+    qdict_set_default_str(options, "target", iscsi_url->target);
+
+    lun_str = g_strdup_printf("%d", iscsi_url->lun);
+    qdict_set_default_str(options, "lun", lun_str);
+    g_free(lun_str);
+
+    /* User/password from -iscsi take precedence over those from the URL */
+    iscsi_parse_iscsi_option(iscsi_url->target, options);
+
+    if (iscsi_url->user[0] != '\0') {
+        qdict_set_default_str(options, "user", iscsi_url->user);
+        qdict_set_default_str(options, "password", iscsi_url->passwd);
+    }
+
+    iscsi_destroy_url(iscsi_url);
+}
+
+static QemuOptsList runtime_opts = {
+    .name = "iscsi",
+    .head = QTAILQ_HEAD_INITIALIZER(runtime_opts.head),
+    .desc = {
+        {
+            .name = "transport",
+            .type = QEMU_OPT_STRING,
+        },
+        {
+            .name = "portal",
+            .type = QEMU_OPT_STRING,
+        },
+        {
+            .name = "target",
+            .type = QEMU_OPT_STRING,
+        },
+        {
+            .name = "user",
+            .type = QEMU_OPT_STRING,
+        },
+        {
+            .name = "password",
+            .type = QEMU_OPT_STRING,
+        },
+        {
+            .name = "password-secret",
+            .type = QEMU_OPT_STRING,
+        },
+        {
+            .name = "lun",
+            .type = QEMU_OPT_NUMBER,
+        },
+        {
+            .name = "initiator-name",
+            .type = QEMU_OPT_STRING,
+        },
+        {
+            .name = "header-digest",
+            .type = QEMU_OPT_STRING,
+        },
+        {
+            .name = "timeout",
+            .type = QEMU_OPT_NUMBER,
+        },
+        { /* end of list */ }
+    },
+};
+
+static void iscsi_save_designator(IscsiLun *lun,
+                                  struct scsi_inquiry_device_identification *inq_di)
+{
+    struct scsi_inquiry_device_designator *desig, *copy = NULL;
+
+    for (desig = inq_di->designators; desig; desig = desig->next) {
+        if (desig->association ||
+            desig->designator_type > SCSI_DESIGNATOR_TYPE_NAA) {
+            continue;
+        }
+        /* NAA works better than T10 vendor ID based designator. */
+        if (!copy || copy->designator_type < desig->designator_type) {
+            copy = desig;
+        }
+    }
+    if (copy) {
+        lun->dd = g_new(struct scsi_inquiry_device_designator, 1);
+        *lun->dd = *copy;
+        lun->dd->next = NULL;
+        lun->dd->designator = g_malloc(copy->designator_length);
+        memcpy(lun->dd->designator, copy->designator, copy->designator_length);
+    }
+}
+
+static int iscsi_open(BlockDriverState *bs, QDict *options, int flags,
+                      Error **errp)
+{
+    IscsiLun *iscsilun = bs->opaque;
+    struct iscsi_context *iscsi = NULL;
+    struct scsi_task *task = NULL;
+    struct scsi_inquiry_standard *inq = NULL;
+    struct scsi_inquiry_supported_pages *inq_vpd;
+    char *initiator_name = NULL;
+    QemuOpts *opts;
+    Error *local_err = NULL;
+    const char *transport_name, *portal, *target;
+#if LIBISCSI_API_VERSION >= (20160603)
+    enum iscsi_transport_type transport;
+#endif
+    int i, ret = 0, timeout = 0, lun;
+
+    opts = qemu_opts_create(&runtime_opts, NULL, 0, &error_abort);
+    if (!qemu_opts_absorb_qdict(opts, options, errp)) {
+        ret = -EINVAL;
+        goto out;
+    }
+
+    transport_name = qemu_opt_get(opts, "transport");
+    portal = qemu_opt_get(opts, "portal");
+    target = qemu_opt_get(opts, "target");
+    lun = qemu_opt_get_number(opts, "lun", 0);
+
+    if (!transport_name || !portal || !target) {
+        error_setg(errp, "Need all of transport, portal and target options");
+        ret = -EINVAL;
+        goto out;
+    }
+
+    if (!strcmp(transport_name, "tcp")) {
+#if LIBISCSI_API_VERSION >= (20160603)
+        transport = TCP_TRANSPORT;
+    } else if (!strcmp(transport_name, "iser")) {
+        transport = ISER_TRANSPORT;
+#else
+        /* TCP is what older libiscsi versions always use */
+#endif
+    } else {
+        error_setg(errp, "Unknown transport: %s", transport_name);
+        ret = -EINVAL;
+        goto out;
+    }
+
+    memset(iscsilun, 0, sizeof(IscsiLun));
+
+    initiator_name = get_initiator_name(opts);
+
+    iscsi = iscsi_create_context(initiator_name);
+    if (iscsi == NULL) {
+        error_setg(errp, "iSCSI: Failed to create iSCSI context.");
+        ret = -ENOMEM;
+        goto out;
+    }
+#if LIBISCSI_API_VERSION >= (20160603)
+    if (iscsi_init_transport(iscsi, transport)) {
+        error_setg(errp, ("Error initializing transport."));
+        ret = -EINVAL;
+        goto out;
+    }
+#endif
+    if (iscsi_set_targetname(iscsi, target)) {
+        error_setg(errp, "iSCSI: Failed to set target name.");
+        ret = -EINVAL;
+        goto out;
+    }
+
+    /* check if we got CHAP username/password via the options */
+    apply_chap(iscsi, opts, &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;
+    }
+
+    /* check if we got HEADER_DIGEST via the options */
+    apply_header_digest(iscsi, opts, &local_err);
+    if (local_err != NULL) {
+        error_propagate(errp, local_err);
+        ret = -EINVAL;
+        goto out;
+    }
+
+    /* timeout handling is broken in libiscsi before 1.15.0 */
+    timeout = qemu_opt_get_number(opts, "timeout", 0);
+#if LIBISCSI_API_VERSION >= 20150621
+    iscsi_set_timeout(iscsi, timeout);
+#else
+    if (timeout) {
+        warn_report("iSCSI: ignoring timeout value for libiscsi <1.15.0");
+    }
+#endif
+
+    if (iscsi_full_connect_sync(iscsi, portal, lun) != 0) {
+        error_setg(errp, "iSCSI: Failed to connect to LUN : %s",
+            iscsi_get_error(iscsi));
+        ret = -EINVAL;
+        goto out;
+    }
+
+    iscsilun->iscsi = iscsi;
+    iscsilun->aio_context = bdrv_get_aio_context(bs);
+    iscsilun->lun = lun;
+    iscsilun->has_write_same = true;
+
+    task = iscsi_do_inquiry(iscsilun->iscsi, iscsilun->lun, 0, 0,
+                            (void **) &inq, errp);
+    if (task == NULL) {
+        ret = -EINVAL;
+        goto out;
+    }
+    iscsilun->type = inq->periperal_device_type;
+    scsi_free_scsi_task(task);
+    task = NULL;
+
+    iscsi_modesense_sync(iscsilun);
+    if (iscsilun->dpofua) {
+        bs->supported_write_flags = BDRV_REQ_FUA;
+    }
+
+    /* Check the write protect flag of the LUN if we want to write */
+    if (iscsilun->type == TYPE_DISK && (flags & BDRV_O_RDWR) &&
+        iscsilun->write_protected) {
+        ret = bdrv_apply_auto_read_only(bs, "LUN is write protected", errp);
+        if (ret < 0) {
+            goto out;
+        }
+        flags &= ~BDRV_O_RDWR;
+    }
+
+    iscsi_readcapacity_sync(iscsilun, &local_err);
+    if (local_err != NULL) {
+        error_propagate(errp, local_err);
+        ret = -EINVAL;
+        goto out;
+    }
+    bs->total_sectors = sector_lun2qemu(iscsilun->num_blocks, iscsilun);
+
+    /* We don't have any emulation for devices other than disks and CD-ROMs, 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_DISK && iscsilun->type != TYPE_ROM) {
+        bs->sg = true;
+    }
+
+    task = iscsi_do_inquiry(iscsilun->iscsi, iscsilun->lun, 1,
+                            SCSI_INQUIRY_PAGECODE_SUPPORTED_VPD_PAGES,
+                            (void **) &inq_vpd, errp);
+    if (task == NULL) {
+        ret = -EINVAL;
+        goto out;
+    }
+    for (i = 0; i < inq_vpd->num_pages; i++) {
+        struct scsi_task *inq_task;
+        struct scsi_inquiry_logical_block_provisioning *inq_lbp;
+        struct scsi_inquiry_block_limits *inq_bl;
+        struct scsi_inquiry_device_identification *inq_di;
+        switch (inq_vpd->pages[i]) {
+        case SCSI_INQUIRY_PAGECODE_LOGICAL_BLOCK_PROVISIONING:
+            inq_task = iscsi_do_inquiry(iscsilun->iscsi, iscsilun->lun, 1,
+                                        SCSI_INQUIRY_PAGECODE_LOGICAL_BLOCK_PROVISIONING,
+                                        (void **) &inq_lbp, errp);
+            if (inq_task == NULL) {
+                ret = -EINVAL;
+                goto out;
+            }
+            memcpy(&iscsilun->lbp, inq_lbp,
+                   sizeof(struct scsi_inquiry_logical_block_provisioning));
+            scsi_free_scsi_task(inq_task);
+            break;
+        case SCSI_INQUIRY_PAGECODE_BLOCK_LIMITS:
+            inq_task = iscsi_do_inquiry(iscsilun->iscsi, iscsilun->lun, 1,
+                                    SCSI_INQUIRY_PAGECODE_BLOCK_LIMITS,
+                                    (void **) &inq_bl, errp);
+            if (inq_task == NULL) {
+                ret = -EINVAL;
+                goto out;
+            }
+            memcpy(&iscsilun->bl, inq_bl,
+                   sizeof(struct scsi_inquiry_block_limits));
+            scsi_free_scsi_task(inq_task);
+            break;
+        case SCSI_INQUIRY_PAGECODE_DEVICE_IDENTIFICATION:
+            inq_task = iscsi_do_inquiry(iscsilun->iscsi, iscsilun->lun, 1,
+                                    SCSI_INQUIRY_PAGECODE_DEVICE_IDENTIFICATION,
+                                    (void **) &inq_di, errp);
+            if (inq_task == NULL) {
+                ret = -EINVAL;
+                goto out;
+            }
+            iscsi_save_designator(iscsilun, inq_di);
+            scsi_free_scsi_task(inq_task);
+            break;
+        default:
+            break;
+        }
+    }
+    scsi_free_scsi_task(task);
+    task = NULL;
+
+    qemu_mutex_init(&iscsilun->mutex);
+    iscsi_attach_aio_context(bs, iscsilun->aio_context);
+
+    /* 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 */
+    if (iscsilun->bl.opt_unmap_gran * iscsilun->block_size >= 4 * 1024 &&
+        iscsilun->bl.opt_unmap_gran * iscsilun->block_size <= 16 * 1024 * 1024) {
+        iscsilun->cluster_size = iscsilun->bl.opt_unmap_gran *
+            iscsilun->block_size;
+        if (iscsilun->lbprz) {
+            ret = iscsi_allocmap_init(iscsilun, flags);
+        }
+    }
+
+    if (iscsilun->lbprz && iscsilun->lbp.lbpws) {
+        bs->supported_zero_flags = BDRV_REQ_MAY_UNMAP;
+    }
+
+out:
+    qemu_opts_del(opts);
+    g_free(initiator_name);
+    if (task != NULL) {
+        scsi_free_scsi_task(task);
+    }
+
+    if (ret) {
+        if (iscsi != NULL) {
+            if (iscsi_is_logged_in(iscsi)) {
+                iscsi_logout_sync(iscsi);
+            }
+            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;
+
+    iscsi_detach_aio_context(bs);
+    if (iscsi_is_logged_in(iscsi)) {
+        iscsi_logout_sync(iscsi);
+    }
+    iscsi_destroy_context(iscsi);
+    if (iscsilun->dd) {
+        g_free(iscsilun->dd->designator);
+        g_free(iscsilun->dd);
+    }
+    g_free(iscsilun->zeroblock);
+    iscsi_allocmap_free(iscsilun);
+    qemu_mutex_destroy(&iscsilun->mutex);
+    memset(iscsilun, 0, sizeof(IscsiLun));
+}
+
+static void iscsi_refresh_limits(BlockDriverState *bs, Error **errp)
+{
+    /* We don't actually refresh here, but just return data queried in
+     * iscsi_open(): iscsi targets don't change their limits. */
+
+    IscsiLun *iscsilun = bs->opaque;
+    uint64_t max_xfer_len = iscsilun->use_16_for_rw ? 0xffffffff : 0xffff;
+    unsigned int block_size = MAX(BDRV_SECTOR_SIZE, iscsilun->block_size);
+
+    assert(iscsilun->block_size >= BDRV_SECTOR_SIZE || bs->sg);
+
+    bs->bl.request_alignment = block_size;
+
+    if (iscsilun->bl.max_xfer_len) {
+        max_xfer_len = MIN(max_xfer_len, iscsilun->bl.max_xfer_len);
+    }
+
+    if (max_xfer_len * block_size < INT_MAX) {
+        bs->bl.max_transfer = max_xfer_len * iscsilun->block_size;
+    }
+
+    if (iscsilun->lbp.lbpu) {
+        bs->bl.max_pdiscard =
+            MIN_NON_ZERO(iscsilun->bl.max_unmap * iscsilun->block_size,
+                         (uint64_t)UINT32_MAX * iscsilun->block_size);
+        bs->bl.pdiscard_alignment =
+            iscsilun->bl.opt_unmap_gran * iscsilun->block_size;
+    } else {
+        bs->bl.pdiscard_alignment = iscsilun->block_size;
+    }
+
+    bs->bl.max_pwrite_zeroes =
+        MIN_NON_ZERO(iscsilun->bl.max_ws_len * iscsilun->block_size,
+                     max_xfer_len * iscsilun->block_size);
+
+    if (iscsilun->lbp.lbpws) {
+        bs->bl.pwrite_zeroes_alignment =
+            iscsilun->bl.opt_unmap_gran * iscsilun->block_size;
+    } else {
+        bs->bl.pwrite_zeroes_alignment = iscsilun->block_size;
+    }
+    if (iscsilun->bl.opt_xfer_len &&
+        iscsilun->bl.opt_xfer_len < INT_MAX / block_size) {
+        bs->bl.opt_transfer = pow2floor(iscsilun->bl.opt_xfer_len *
+                                        iscsilun->block_size);
+    }
+}
+
+/* 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)
+{
+    IscsiLun *iscsilun = state->bs->opaque;
+
+    if (state->flags & BDRV_O_RDWR && iscsilun->write_protected) {
+        error_setg(errp, "Cannot open a write protected LUN as read-write");
+        return -EACCES;
+    }
+    return 0;
+}
+
+static void iscsi_reopen_commit(BDRVReopenState *reopen_state)
+{
+    IscsiLun *iscsilun = reopen_state->bs->opaque;
+
+    /* the cache.direct status might have changed */
+    if (iscsilun->allocmap != NULL) {
+        iscsi_allocmap_init(iscsilun, reopen_state->flags);
+    }
+}
+
+static int coroutine_fn iscsi_co_truncate(BlockDriverState *bs, int64_t offset,
+                                          bool exact, PreallocMode prealloc,
+                                          BdrvRequestFlags flags, Error **errp)
+{
+    IscsiLun *iscsilun = bs->opaque;
+    int64_t cur_length;
+    Error *local_err = NULL;
+
+    if (prealloc != PREALLOC_MODE_OFF) {
+        error_setg(errp, "Unsupported preallocation mode '%s'",
+                   PreallocMode_str(prealloc));
+        return -ENOTSUP;
+    }
+
+    if (iscsilun->type != TYPE_DISK) {
+        error_setg(errp, "Cannot resize non-disk iSCSI devices");
+        return -ENOTSUP;
+    }
+
+    iscsi_readcapacity_sync(iscsilun, &local_err);
+    if (local_err != NULL) {
+        error_propagate(errp, local_err);
+        return -EIO;
+    }
+
+    cur_length = iscsi_getlength(bs);
+    if (offset != cur_length && exact) {
+        error_setg(errp, "Cannot resize iSCSI devices");
+        return -ENOTSUP;
+    } else if (offset > cur_length) {
+        error_setg(errp, "Cannot grow iSCSI devices");
+        return -EINVAL;
+    }
+
+    if (iscsilun->allocmap != NULL) {
+        iscsi_allocmap_init(iscsilun, bs->open_flags);
+    }
+
+    return 0;
+}
+
+static int iscsi_get_info(BlockDriverState *bs, BlockDriverInfo *bdi)
+{
+    IscsiLun *iscsilun = bs->opaque;
+    bdi->cluster_size = iscsilun->cluster_size;
+    return 0;
+}
+
+static void coroutine_fn iscsi_co_invalidate_cache(BlockDriverState *bs,
+                                                   Error **errp)
+{
+    IscsiLun *iscsilun = bs->opaque;
+    iscsi_allocmap_invalidate(iscsilun);
+}
+
+static int coroutine_fn iscsi_co_copy_range_from(BlockDriverState *bs,
+                                                 BdrvChild *src,
+                                                 int64_t src_offset,
+                                                 BdrvChild *dst,
+                                                 int64_t dst_offset,
+                                                 int64_t bytes,
+                                                 BdrvRequestFlags read_flags,
+                                                 BdrvRequestFlags write_flags)
+{
+    return bdrv_co_copy_range_to(src, src_offset, dst, dst_offset, bytes,
+                                 read_flags, write_flags);
+}
+
+static struct scsi_task *iscsi_xcopy_task(int param_len)
+{
+    struct scsi_task *task;
+
+    task = g_new0(struct scsi_task, 1);
+
+    task->cdb[0]     = EXTENDED_COPY;
+    task->cdb[10]    = (param_len >> 24) & 0xFF;
+    task->cdb[11]    = (param_len >> 16) & 0xFF;
+    task->cdb[12]    = (param_len >> 8) & 0xFF;
+    task->cdb[13]    = param_len & 0xFF;
+    task->cdb_size   = 16;
+    task->xfer_dir   = SCSI_XFER_WRITE;
+    task->expxferlen = param_len;
+
+    return task;
+}
+
+static void iscsi_populate_target_desc(unsigned char *desc, IscsiLun *lun)
+{
+    struct scsi_inquiry_device_designator *dd = lun->dd;
+
+    memset(desc, 0, 32);
+    desc[0] = 0xE4; /* IDENT_DESCR_TGT_DESCR */
+    desc[4] = dd->code_set;
+    desc[5] = (dd->designator_type & 0xF)
+        | ((dd->association & 3) << 4);
+    desc[7] = dd->designator_length;
+    memcpy(desc + 8, dd->designator, MIN(dd->designator_length, 20));
+
+    desc[28] = 0;
+    desc[29] = (lun->block_size >> 16) & 0xFF;
+    desc[30] = (lun->block_size >> 8) & 0xFF;
+    desc[31] = lun->block_size & 0xFF;
+}
+
+static void iscsi_xcopy_desc_hdr(uint8_t *hdr, int dc, int cat, int src_index,
+                                 int dst_index)
+{
+    hdr[0] = 0x02; /* BLK_TO_BLK_SEG_DESCR */
+    hdr[1] = ((dc << 1) | cat) & 0xFF;
+    hdr[2] = (XCOPY_BLK2BLK_SEG_DESC_SIZE >> 8) & 0xFF;
+    /* don't account for the first 4 bytes in descriptor header*/
+    hdr[3] = (XCOPY_BLK2BLK_SEG_DESC_SIZE - 4 /* SEG_DESC_SRC_INDEX_OFFSET */) & 0xFF;
+    hdr[4] = (src_index >> 8) & 0xFF;
+    hdr[5] = src_index & 0xFF;
+    hdr[6] = (dst_index >> 8) & 0xFF;
+    hdr[7] = dst_index & 0xFF;
+}
+
+static void iscsi_xcopy_populate_desc(uint8_t *desc, int dc, int cat,
+                                      int src_index, int dst_index, int num_blks,
+                                      uint64_t src_lba, uint64_t dst_lba)
+{
+    iscsi_xcopy_desc_hdr(desc, dc, cat, src_index, dst_index);
+
+    /* The caller should verify the request size */
+    assert(num_blks < 65536);
+    desc[10] = (num_blks >> 8) & 0xFF;
+    desc[11] = num_blks & 0xFF;
+    desc[12] = (src_lba >> 56) & 0xFF;
+    desc[13] = (src_lba >> 48) & 0xFF;
+    desc[14] = (src_lba >> 40) & 0xFF;
+    desc[15] = (src_lba >> 32) & 0xFF;
+    desc[16] = (src_lba >> 24) & 0xFF;
+    desc[17] = (src_lba >> 16) & 0xFF;
+    desc[18] = (src_lba >> 8) & 0xFF;
+    desc[19] = src_lba & 0xFF;
+    desc[20] = (dst_lba >> 56) & 0xFF;
+    desc[21] = (dst_lba >> 48) & 0xFF;
+    desc[22] = (dst_lba >> 40) & 0xFF;
+    desc[23] = (dst_lba >> 32) & 0xFF;
+    desc[24] = (dst_lba >> 24) & 0xFF;
+    desc[25] = (dst_lba >> 16) & 0xFF;
+    desc[26] = (dst_lba >> 8) & 0xFF;
+    desc[27] = dst_lba & 0xFF;
+}
+
+static void iscsi_xcopy_populate_header(unsigned char *buf, int list_id, int str,
+                                        int list_id_usage, int prio,
+                                        int tgt_desc_len,
+                                        int seg_desc_len, int inline_data_len)
+{
+    buf[0] = list_id;
+    buf[1] = ((str & 1) << 5) | ((list_id_usage & 3) << 3) | (prio & 7);
+    buf[2] = (tgt_desc_len >> 8) & 0xFF;
+    buf[3] = tgt_desc_len & 0xFF;
+    buf[8] = (seg_desc_len >> 24) & 0xFF;
+    buf[9] = (seg_desc_len >> 16) & 0xFF;
+    buf[10] = (seg_desc_len >> 8) & 0xFF;
+    buf[11] = seg_desc_len & 0xFF;
+    buf[12] = (inline_data_len >> 24) & 0xFF;
+    buf[13] = (inline_data_len >> 16) & 0xFF;
+    buf[14] = (inline_data_len >> 8) & 0xFF;
+    buf[15] = inline_data_len & 0xFF;
+}
+
+static void iscsi_xcopy_data(struct iscsi_data *data,
+                             IscsiLun *src, int64_t src_lba,
+                             IscsiLun *dst, int64_t dst_lba,
+                             uint16_t num_blocks)
+{
+    uint8_t *buf;
+    const int src_offset = XCOPY_DESC_OFFSET;
+    const int dst_offset = XCOPY_DESC_OFFSET + IDENT_DESCR_TGT_DESCR_SIZE;
+    const int seg_offset = dst_offset + IDENT_DESCR_TGT_DESCR_SIZE;
+
+    data->size = XCOPY_DESC_OFFSET +
+                 IDENT_DESCR_TGT_DESCR_SIZE * 2 +
+                 XCOPY_BLK2BLK_SEG_DESC_SIZE;
+    data->data = g_malloc0(data->size);
+    buf = data->data;
+
+    /* Initialise the parameter list header */
+    iscsi_xcopy_populate_header(buf, 1, 0, 2 /* LIST_ID_USAGE_DISCARD */,
+                                0, 2 * IDENT_DESCR_TGT_DESCR_SIZE,
+                                XCOPY_BLK2BLK_SEG_DESC_SIZE,
+                                0);
+
+    /* Initialise CSCD list with one src + one dst descriptor */
+    iscsi_populate_target_desc(&buf[src_offset], src);
+    iscsi_populate_target_desc(&buf[dst_offset], dst);
+
+    /* Initialise one segment descriptor */
+    iscsi_xcopy_populate_desc(&buf[seg_offset], 0, 0, 0, 1, num_blocks,
+                              src_lba, dst_lba);
+}
+
+static int coroutine_fn iscsi_co_copy_range_to(BlockDriverState *bs,
+                                               BdrvChild *src,
+                                               int64_t src_offset,
+                                               BdrvChild *dst,
+                                               int64_t dst_offset,
+                                               int64_t bytes,
+                                               BdrvRequestFlags read_flags,
+                                               BdrvRequestFlags write_flags)
+{
+    IscsiLun *dst_lun = dst->bs->opaque;
+    IscsiLun *src_lun;
+    struct IscsiTask iscsi_task;
+    struct iscsi_data data;
+    int r = 0;
+    int block_size;
+
+    if (src->bs->drv->bdrv_co_copy_range_to != iscsi_co_copy_range_to) {
+        return -ENOTSUP;
+    }
+    src_lun = src->bs->opaque;
+
+    if (!src_lun->dd || !dst_lun->dd) {
+        return -ENOTSUP;
+    }
+    if (!is_byte_request_lun_aligned(dst_offset, bytes, dst_lun)) {
+        return -ENOTSUP;
+    }
+    if (!is_byte_request_lun_aligned(src_offset, bytes, src_lun)) {
+        return -ENOTSUP;
+    }
+    if (dst_lun->block_size != src_lun->block_size ||
+        !dst_lun->block_size) {
+        return -ENOTSUP;
+    }
+
+    block_size = dst_lun->block_size;
+    if (bytes / block_size > 65535) {
+        return -ENOTSUP;
+    }
+
+    iscsi_xcopy_data(&data,
+                     src_lun, src_offset / block_size,
+                     dst_lun, dst_offset / block_size,
+                     bytes / block_size);
+
+    iscsi_co_init_iscsitask(dst_lun, &iscsi_task);
+
+    qemu_mutex_lock(&dst_lun->mutex);
+    iscsi_task.task = iscsi_xcopy_task(data.size);
+retry:
+    if (iscsi_scsi_command_async(dst_lun->iscsi, dst_lun->lun,
+                                 iscsi_task.task, iscsi_co_generic_cb,
+                                 &data,
+                                 &iscsi_task) != 0) {
+        r = -EIO;
+        goto out_unlock;
+    }
+
+    iscsi_co_wait_for_task(&iscsi_task, dst_lun);
+
+    if (iscsi_task.do_retry) {
+        iscsi_task.complete = 0;
+        goto retry;
+    }
+
+    if (iscsi_task.status != SCSI_STATUS_GOOD) {
+        r = iscsi_task.err_code;
+        goto out_unlock;
+    }
+
+out_unlock:
+
+    trace_iscsi_xcopy(src_lun, src_offset, dst_lun, dst_offset, bytes, r);
+    g_free(iscsi_task.task);
+    qemu_mutex_unlock(&dst_lun->mutex);
+    g_free(iscsi_task.err_str);
+    return r;
+}
+
+
+static const char *const iscsi_strong_runtime_opts[] = {
+    "transport",
+    "portal",
+    "target",
+    "user",
+    "password",
+    "password-secret",
+    "lun",
+    "initiator-name",
+    "header-digest",
+
+    NULL
+};
+
+static BlockDriver bdrv_iscsi = {
+    .format_name     = "iscsi",
+    .protocol_name   = "iscsi",
+
+    .instance_size          = sizeof(IscsiLun),
+    .bdrv_parse_filename    = iscsi_parse_filename,
+    .bdrv_file_open         = iscsi_open,
+    .bdrv_close             = iscsi_close,
+    .bdrv_co_create_opts    = bdrv_co_create_opts_simple,
+    .create_opts            = &bdrv_create_opts_simple,
+    .bdrv_reopen_prepare    = iscsi_reopen_prepare,
+    .bdrv_reopen_commit     = iscsi_reopen_commit,
+    .bdrv_co_invalidate_cache = iscsi_co_invalidate_cache,
+
+    .bdrv_getlength  = iscsi_getlength,
+    .bdrv_get_info   = iscsi_get_info,
+    .bdrv_co_truncate    = iscsi_co_truncate,
+    .bdrv_refresh_limits = iscsi_refresh_limits,
+
+    .bdrv_co_block_status  = iscsi_co_block_status,
+    .bdrv_co_pdiscard      = iscsi_co_pdiscard,
+    .bdrv_co_copy_range_from = iscsi_co_copy_range_from,
+    .bdrv_co_copy_range_to  = iscsi_co_copy_range_to,
+    .bdrv_co_pwrite_zeroes = iscsi_co_pwrite_zeroes,
+    .bdrv_co_readv         = iscsi_co_readv,
+    .bdrv_co_writev        = iscsi_co_writev,
+    .bdrv_co_flush_to_disk = iscsi_co_flush,
+
+#ifdef __linux__
+    .bdrv_aio_ioctl   = iscsi_aio_ioctl,
+#endif
+
+    .bdrv_detach_aio_context = iscsi_detach_aio_context,
+    .bdrv_attach_aio_context = iscsi_attach_aio_context,
+
+    .strong_runtime_opts = iscsi_strong_runtime_opts,
+};
+
+#if LIBISCSI_API_VERSION >= (20160603)
+static BlockDriver bdrv_iser = {
+    .format_name     = "iser",
+    .protocol_name   = "iser",
+
+    .instance_size          = sizeof(IscsiLun),
+    .bdrv_parse_filename    = iscsi_parse_filename,
+    .bdrv_file_open         = iscsi_open,
+    .bdrv_close             = iscsi_close,
+    .bdrv_co_create_opts    = bdrv_co_create_opts_simple,
+    .create_opts            = &bdrv_create_opts_simple,
+    .bdrv_reopen_prepare    = iscsi_reopen_prepare,
+    .bdrv_reopen_commit     = iscsi_reopen_commit,
+    .bdrv_co_invalidate_cache  = iscsi_co_invalidate_cache,
+
+    .bdrv_getlength  = iscsi_getlength,
+    .bdrv_get_info   = iscsi_get_info,
+    .bdrv_co_truncate    = iscsi_co_truncate,
+    .bdrv_refresh_limits = iscsi_refresh_limits,
+
+    .bdrv_co_block_status  = iscsi_co_block_status,
+    .bdrv_co_pdiscard      = iscsi_co_pdiscard,
+    .bdrv_co_copy_range_from = iscsi_co_copy_range_from,
+    .bdrv_co_copy_range_to  = iscsi_co_copy_range_to,
+    .bdrv_co_pwrite_zeroes = iscsi_co_pwrite_zeroes,
+    .bdrv_co_readv         = iscsi_co_readv,
+    .bdrv_co_writev        = iscsi_co_writev,
+    .bdrv_co_flush_to_disk = iscsi_co_flush,
+
+#ifdef __linux__
+    .bdrv_aio_ioctl   = iscsi_aio_ioctl,
+#endif
+
+    .bdrv_detach_aio_context = iscsi_detach_aio_context,
+    .bdrv_attach_aio_context = iscsi_attach_aio_context,
+
+    .strong_runtime_opts = iscsi_strong_runtime_opts,
+};
+#endif
+
+static void iscsi_block_init(void)
+{
+    bdrv_register(&bdrv_iscsi);
+#if LIBISCSI_API_VERSION >= (20160603)
+    bdrv_register(&bdrv_iser);
+#endif
+}
+
+block_init(iscsi_block_init);