iscsi/qemu-img/block-migration enhancements

index 0bbf0b1..c802e38 100644
@@ -49,6 +49,12 @@ typedef struct IscsiLun {
     uint64_t num_blocks;
     int events;
     QEMUTimer *nop_timer;
+    uint8_t lbpme;
+    uint8_t lbprz;
+    uint8_t lbpu;
+    uint8_t lbpws;
+    uint8_t lbpws10;
+    uint32_t max_unmap;
 } IscsiLun;
 
 typedef struct IscsiAIOCB {

@@ -73,6 +79,7 @@ typedef struct IscsiAIOCB {
 #define NOP_INTERVAL 5000
 #define MAX_NOP_FAILURES 3
 #define ISCSI_CMD_RETRIES 5
+#define ISCSI_MAX_UNMAP 131072
 
 static void
 iscsi_bh_cb(void *p)

@@ -948,6 +955,8 @@ static int iscsi_readcapacity_sync(IscsiLun *iscsilun)
                 } else {
                     iscsilun->block_size = rc16->block_length;
                     iscsilun->num_blocks = rc16->returned_lba + 1;
+                    iscsilun->lbpme = rc16->lbpme;
+                    iscsilun->lbprz = rc16->lbprz;
                 }
             }
             break;

@@ -1000,6 +1009,37 @@ static QemuOptsList runtime_opts = {
     },
 };
 
+static struct scsi_task *iscsi_do_inquiry(struct iscsi_context *iscsi,
+                                          int lun, int evpd, int pc) {
+        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_report("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>

@@ -1130,6 +1170,49 @@ static int iscsi_open(BlockDriverState *bs, QDict *options, int flags)
         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);
+        if (task == NULL) {
+            ret = -EINVAL;
+            goto out;
+        }
+        inq_lbp = scsi_datain_unmarshall(task);
+        if (inq_lbp == NULL) {
+            error_report("iSCSI: failed to unmarshall inquiry datain blob");
+            ret = -EINVAL;
+            goto out;
+        }
+        iscsilun->lbpu = inq_lbp->lbpu;
+        iscsilun->lbpws = inq_lbp->lbpws;
+        iscsilun->lbpws10 = inq_lbp->lbpws10;
+        scsi_free_scsi_task(task);
+        task = NULL;
+    }
+
+    if (iscsilun->lbpu) {
+        struct scsi_inquiry_block_limits *inq_bl;
+        task = iscsi_do_inquiry(iscsilun->iscsi, iscsilun->lun, 1,
+                                SCSI_INQUIRY_PAGECODE_BLOCK_LIMITS);
+        if (task == NULL) {
+            ret = -EINVAL;
+            goto out;
+        }
+        inq_bl = scsi_datain_unmarshall(task);
+        if (inq_bl == NULL) {
+            error_report("iSCSI: failed to unmarshall inquiry datain blob");
+            ret = -EINVAL;
+            goto out;
+        }
+        iscsilun->max_unmap = inq_bl->max_unmap;
+        if (iscsilun->max_unmap == 0xffffffff) {
+            iscsilun->max_unmap = ISCSI_MAX_UNMAP;
+        }
+        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 = qemu_new_timer_ms(rt_clock, iscsi_nop_timed_event, iscsilun);

index c802e38..6400bc2 100644
@@ -57,6 +57,15 @@ typedef struct IscsiLun {
     uint32_t max_unmap;
 } IscsiLun;
 
+typedef struct IscsiTask {
+    int status;
+    int complete;
+    int retries;
+    int do_retry;
+    struct scsi_task *task;
+    Coroutine *co;
+} IscsiTask;
+
 typedef struct IscsiAIOCB {
     BlockDriverAIOCB common;
     QEMUIOVector *qiov;

@@ -113,6 +122,41 @@ iscsi_schedule_bh(IscsiAIOCB *acb)
     qemu_bh_schedule(acb->bh);
 }
 
+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) {
+        iTask->do_retry = 1;
+        goto out;
+    }
+
+    if (status != SCSI_STATUS_GOOD) {
+        error_report("iSCSI: Failure. %s", iscsi_get_error(iscsi));
+    }
+
+out:
+    if (iTask->co) {
+        qemu_coroutine_enter(iTask->co, NULL);
+    }
+}
+
+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,

@@ -807,6 +851,90 @@ iscsi_getlength(BlockDriverState *bs)
     return len;
 }
 
+static int coroutine_fn iscsi_co_is_allocated(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;
+    int ret;
+
+    /* default to all sectors allocated */
+    ret = 1;
+    *pnum = nb_sectors;
+
+    /* LUN does not support logical block provisioning */
+    if (iscsilun->lbpme == 0) {
+        goto out;
+    }
+
+    iscsi_co_init_iscsitask(iscsilun, &iTask);
+
+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 = 0;
+        *pnum = 0;
+        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;
+        }
+        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 compatiblity */
+        goto out;
+    }
+
+    lbas = scsi_datain_unmarshall(iTask.task);
+    if (lbas == NULL) {
+        ret = 0;
+        *pnum = 0;
+        goto out;
+    }
+
+    lbasd = &lbas->descriptors[0];
+
+    if (sector_qemu2lun(sector_num, iscsilun) != lbasd->lba) {
+        ret = 0;
+        *pnum = 0;
+        goto out;
+    }
+
+    *pnum = lbasd->num_blocks * (iscsilun->block_size / BDRV_SECTOR_SIZE);
+    if (*pnum > nb_sectors) {
+        *pnum = nb_sectors;
+    }
+
+    if (lbasd->provisioning == SCSI_PROVISIONING_TYPE_DEALLOCATED ||
+        lbasd->provisioning == SCSI_PROVISIONING_TYPE_ANCHORED) {
+        ret = 0;
+    }
+
+out:
+    if (iTask.task != NULL) {
+        scsi_free_scsi_task(iTask.task);
+    }
+    return ret;
+}
+
 static int parse_chap(struct iscsi_context *iscsi, const char *target)
 {
     QemuOptsList *list;

@@ -1351,6 +1479,8 @@ static BlockDriver bdrv_iscsi = {
     .bdrv_getlength  = iscsi_getlength,
     .bdrv_truncate   = iscsi_truncate,
 
+    .bdrv_co_is_allocated = iscsi_co_is_allocated,
+
     .bdrv_aio_readv  = iscsi_aio_readv,
     .bdrv_aio_writev = iscsi_aio_writev,
     .bdrv_aio_flush  = iscsi_aio_flush,

index 6400bc2..60f2fd0 100644
@@ -613,88 +613,6 @@ iscsi_aio_flush(BlockDriverState *bs,
     return &acb->common;
 }
 
-static int iscsi_aio_discard_acb(IscsiAIOCB *acb);
-
-static void
-iscsi_unmap_cb(struct iscsi_context *iscsi, int status,
-                     void *command_data, void *opaque)
-{
-    IscsiAIOCB *acb = opaque;
-
-    if (acb->canceled != 0) {
-        return;
-    }
-
-    acb->status = 0;
-    if (status != 0) {
-        if (status == SCSI_STATUS_CHECK_CONDITION
-            && acb->task->sense.key == SCSI_SENSE_UNIT_ATTENTION
-            && acb->retries-- > 0) {
-            scsi_free_scsi_task(acb->task);
-            acb->task = NULL;
-            if (iscsi_aio_discard_acb(acb) == 0) {
-                iscsi_set_events(acb->iscsilun);
-                return;
-            }
-        }
-        error_report("Failed to unmap data on iSCSI lun. %s",
-                     iscsi_get_error(iscsi));
-        acb->status = -EIO;
-    }
-
-    iscsi_schedule_bh(acb);
-}
-
-static int iscsi_aio_discard_acb(IscsiAIOCB *acb) {
-    struct iscsi_context *iscsi = acb->iscsilun->iscsi;
-    struct unmap_list list[1];
-
-    acb->canceled   = 0;
-    acb->bh         = NULL;
-    acb->status     = -EINPROGRESS;
-    acb->buf        = NULL;
-
-    list[0].lba = sector_qemu2lun(acb->sector_num, acb->iscsilun);
-    list[0].num = acb->nb_sectors * BDRV_SECTOR_SIZE / acb->iscsilun->block_size;
-
-    acb->task = iscsi_unmap_task(iscsi, acb->iscsilun->lun,
-                                 0, 0, &list[0], 1,
-                                 iscsi_unmap_cb,
-                                 acb);
-    if (acb->task == NULL) {
-        error_report("iSCSI: Failed to send unmap command. %s",
-                     iscsi_get_error(iscsi));
-        return -1;
-    }
-
-    return 0;
-}
-
-static BlockDriverAIOCB *
-iscsi_aio_discard(BlockDriverState *bs,
-                  int64_t sector_num, int nb_sectors,
-                  BlockDriverCompletionFunc *cb, void *opaque)
-{
-    IscsiLun *iscsilun = bs->opaque;
-    IscsiAIOCB *acb;
-
-    acb = qemu_aio_get(&iscsi_aiocb_info, bs, cb, opaque);
-
-    acb->iscsilun    = iscsilun;
-    acb->nb_sectors  = nb_sectors;
-    acb->sector_num  = sector_num;
-    acb->retries     = ISCSI_CMD_RETRIES;
-
-    if (iscsi_aio_discard_acb(acb) != 0) {
-        qemu_aio_release(acb);
-        return NULL;
-    }
-
-    iscsi_set_events(iscsilun);
-
-    return &acb->common;
-}
-
 #ifdef __linux__
 static void
 iscsi_aio_ioctl_cb(struct iscsi_context *iscsi, int status,

@@ -935,6 +853,59 @@ out:
     return ret;
 }
 
+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;
+    uint32_t nb_blocks;
+
+    if (!iscsilun->lbpu) {
+        return 0;
+    }
+
+    list.lba = sector_qemu2lun(sector_num, iscsilun);
+    nb_blocks = sector_qemu2lun(nb_sectors, iscsilun);
+
+    while (nb_blocks > 0) {
+        iscsi_co_init_iscsitask(iscsilun, &iTask);
+        list.num = nb_blocks;
+        if (list.num > iscsilun->max_unmap) {
+            list.num = iscsilun->max_unmap;
+        }
+retry:
+        if (iscsi_unmap_task(iscsilun->iscsi, iscsilun->lun, 0, 0, &list, 1,
+                         iscsi_co_generic_cb, &iTask) == NULL) {
+            return -EIO;
+        }
+
+        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) {
+            goto retry;
+        }
+
+        if (iTask.status != SCSI_STATUS_GOOD) {
+            return -EIO;
+        }
+
+        list.lba += list.num;
+        nb_blocks -= list.num;
+    }
+
+    return 0;
+}
+
 static int parse_chap(struct iscsi_context *iscsi, const char *target)
 {
     QemuOptsList *list;

@@ -1480,12 +1451,12 @@ static BlockDriver bdrv_iscsi = {
     .bdrv_truncate   = iscsi_truncate,
 
     .bdrv_co_is_allocated = iscsi_co_is_allocated,
+    .bdrv_co_discard      = iscsi_co_discard,
 
     .bdrv_aio_readv  = iscsi_aio_readv,
     .bdrv_aio_writev = iscsi_aio_writev,
     .bdrv_aio_flush  = iscsi_aio_flush,
 
-    .bdrv_aio_discard = iscsi_aio_discard,
     .bdrv_has_zero_init = iscsi_has_zero_init,
 
 #ifdef __linux__

index 60f2fd0..64554bc 100644
@@ -906,6 +906,21 @@ retry:
     return 0;
 }
 
+static int
+coroutine_fn iscsi_co_write_zeroes(BlockDriverState *bs, int64_t sector_num,
+                                   int nb_sectors)
+{
+    IscsiLun *iscsilun = bs->opaque;
+
+    if (!iscsilun->lbprz || !iscsilun->lbpu ||
+        !(bs->open_flags & BDRV_O_UNMAP)) {
+        /* fall back to writev */
+        return -ENOTSUP;
+    }
+
+    return iscsi_co_discard(bs, sector_num, nb_sectors);
+}
+
 static int parse_chap(struct iscsi_context *iscsi, const char *target)
 {
     QemuOptsList *list;

@@ -1452,6 +1467,7 @@ static BlockDriver bdrv_iscsi = {
 
     .bdrv_co_is_allocated = iscsi_co_is_allocated,
     .bdrv_co_discard      = iscsi_co_discard,
+    .bdrv_co_write_zeroes = iscsi_co_write_zeroes,
 
     .bdrv_aio_readv  = iscsi_aio_readv,
     .bdrv_aio_writev = iscsi_aio_writev,

index 183fec8..bce1909 100644
@@ -2155,6 +2155,7 @@ typedef struct RwCo {
     QEMUIOVector *qiov;
     bool is_write;
     int ret;
+    BdrvRequestFlags flags;
 } RwCo;
 
 static void coroutine_fn bdrv_rw_co_entry(void *opaque)

@@ -2163,10 +2164,12 @@ static void coroutine_fn bdrv_rw_co_entry(void *opaque)
 
     if (!rwco->is_write) {
         rwco->ret = bdrv_co_do_readv(rwco->bs, rwco->sector_num,
-                                     rwco->nb_sectors, rwco->qiov, 0);
+                                     rwco->nb_sectors, rwco->qiov,
+                                     rwco->flags);
     } else {
         rwco->ret = bdrv_co_do_writev(rwco->bs, rwco->sector_num,
-                                      rwco->nb_sectors, rwco->qiov, 0);
+                                      rwco->nb_sectors, rwco->qiov,
+                                      rwco->flags);
     }
 }
 

@@ -2174,7 +2177,8 @@ static void coroutine_fn bdrv_rw_co_entry(void *opaque)
  * Process a vectored synchronous request using coroutines
  */
 static int bdrv_rwv_co(BlockDriverState *bs, int64_t sector_num,
-                       QEMUIOVector *qiov, bool is_write)
+                       QEMUIOVector *qiov, bool is_write,
+                       BdrvRequestFlags flags)
 {
     Coroutine *co;
     RwCo rwco = {

@@ -2184,6 +2188,7 @@ static int bdrv_rwv_co(BlockDriverState *bs, int64_t sector_num,
         .qiov = qiov,
         .is_write = is_write,
         .ret = NOT_DONE,
+        .flags = flags,
     };
     assert((qiov->size & (BDRV_SECTOR_SIZE - 1)) == 0);
 

@@ -2215,7 +2220,7 @@ static int bdrv_rwv_co(BlockDriverState *bs, int64_t sector_num,
  * Process a synchronous request using coroutines
  */
 static int bdrv_rw_co(BlockDriverState *bs, int64_t sector_num, uint8_t *buf,
-                      int nb_sectors, bool is_write)
+                      int nb_sectors, bool is_write, BdrvRequestFlags flags)
 {
     QEMUIOVector qiov;
     struct iovec iov = {

@@ -2224,14 +2229,14 @@ static int bdrv_rw_co(BlockDriverState *bs, int64_t sector_num, uint8_t *buf,
     };
 
     qemu_iovec_init_external(&qiov, &iov, 1);
-    return bdrv_rwv_co(bs, sector_num, &qiov, is_write);
+    return bdrv_rwv_co(bs, sector_num, &qiov, is_write, flags);
 }
 
 /* return < 0 if error. See bdrv_write() for the return codes */
 int bdrv_read(BlockDriverState *bs, int64_t sector_num,
               uint8_t *buf, int nb_sectors)
 {
-    return bdrv_rw_co(bs, sector_num, buf, nb_sectors, false);
+    return bdrv_rw_co(bs, sector_num, buf, nb_sectors, false, 0);
 }
 
 /* Just like bdrv_read(), but with I/O throttling temporarily disabled */

@@ -2257,12 +2262,18 @@ int bdrv_read_unthrottled(BlockDriverState *bs, int64_t sector_num,
 int bdrv_write(BlockDriverState *bs, int64_t sector_num,
                const uint8_t *buf, int nb_sectors)
 {
-    return bdrv_rw_co(bs, sector_num, (uint8_t *)buf, nb_sectors, true);
+    return bdrv_rw_co(bs, sector_num, (uint8_t *)buf, nb_sectors, true, 0);
 }
 
 int bdrv_writev(BlockDriverState *bs, int64_t sector_num, QEMUIOVector *qiov)
 {
-    return bdrv_rwv_co(bs, sector_num, qiov, true);
+    return bdrv_rwv_co(bs, sector_num, qiov, true, 0);
+}
+
+int bdrv_write_zeroes(BlockDriverState *bs, int64_t sector_num, int nb_sectors)
+{
+    return bdrv_rw_co(bs, sector_num, NULL, nb_sectors, true,
+                      BDRV_REQ_ZERO_WRITE);
 }
 
 int bdrv_pread(BlockDriverState *bs, int64_t offset,

index dd8eca1..297ec1e 100644
@@ -156,6 +156,8 @@ int bdrv_read_unthrottled(BlockDriverState *bs, int64_t sector_num,
                           uint8_t *buf, int nb_sectors);
 int bdrv_write(BlockDriverState *bs, int64_t sector_num,
                const uint8_t *buf, int nb_sectors);
+int bdrv_write_zeroes(BlockDriverState *bs, int64_t sector_num,
+               int nb_sectors);
 int bdrv_writev(BlockDriverState *bs, int64_t sector_num, QEMUIOVector *qiov);
 int bdrv_pread(BlockDriverState *bs, int64_t offset,
                void *buf, int count);

index ce10422..8c81de9 100644
@@ -42,6 +42,13 @@ static int coroutine_fn raw_co_is_allocated(BlockDriverState *bs,
     return bdrv_co_is_allocated(bs->file, sector_num, nb_sectors, pnum);
 }
 
+static int coroutine_fn raw_co_write_zeroes(BlockDriverState *bs,
+                                            int64_t sector_num,
+                                            int nb_sectors)
+{
+    return bdrv_co_write_zeroes(bs->file, sector_num, nb_sectors);
+}
+
 static int64_t raw_getlength(BlockDriverState *bs)
 {
     return bdrv_getlength(bs->file);

@@ -128,6 +135,7 @@ static BlockDriver bdrv_raw = {
     .bdrv_co_readv          = raw_co_readv,
     .bdrv_co_writev         = raw_co_writev,
     .bdrv_co_is_allocated   = raw_co_is_allocated,
+    .bdrv_co_write_zeroes   = raw_co_write_zeroes,
     .bdrv_co_discard        = raw_co_discard,
 
     .bdrv_probe         = raw_probe,

index 64554bc..6cdd182 100644
@@ -1432,6 +1432,7 @@ static int iscsi_create(const char *filename, QEMUOptionParameter *options)
     }
     if (bs.total_sectors < total_size) {
         ret = -ENOSPC;
+        goto out;
     }
 
     ret = 0;

index 6cdd182..bc62a7e 100644
@@ -289,6 +289,11 @@ static int64_t sector_qemu2lun(int64_t sector, IscsiLun *iscsilun)
     return sector * BDRV_SECTOR_SIZE / iscsilun->block_size;
 }
 
+static int64_t sector_lun2qemu(int64_t sector, IscsiLun *iscsilun)
+{
+    return sector * iscsilun->block_size / BDRV_SECTOR_SIZE;
+}
+
 static int
 iscsi_aio_writev_acb(IscsiAIOCB *acb)
 {

@@ -336,7 +341,7 @@ iscsi_aio_writev_acb(IscsiAIOCB *acb)
     lba = sector_qemu2lun(acb->sector_num, acb->iscsilun);
     *(uint32_t *)&acb->task->cdb[2]  = htonl(lba >> 32);
     *(uint32_t *)&acb->task->cdb[6]  = htonl(lba & 0xffffffff);
-    num_sectors = size / acb->iscsilun->block_size;
+    num_sectors = sector_qemu2lun(acb->nb_sectors, acb->iscsilun);
     *(uint32_t *)&acb->task->cdb[10] = htonl(num_sectors);
     acb->task->expxferlen = size;
 

@@ -836,7 +841,7 @@ retry:
         goto out;
     }
 
-    *pnum = lbasd->num_blocks * (iscsilun->block_size / BDRV_SECTOR_SIZE);
+    *pnum = sector_lun2qemu(lbasd->num_blocks, iscsilun);
     if (*pnum > nb_sectors) {
         *pnum = nb_sectors;
     }

@@ -1272,8 +1277,7 @@ static int iscsi_open(BlockDriverState *bs, QDict *options, int flags)
     if ((ret = iscsi_readcapacity_sync(iscsilun)) != 0) {
         goto out;
     }
-    bs->total_sectors    = iscsilun->num_blocks *
-                           iscsilun->block_size / BDRV_SECTOR_SIZE ;
+    bs->total_sectors    = sector_lun2qemu(iscsilun->num_blocks, iscsilun);
 
     /* 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

index bc62a7e..903f2fb 100644
@@ -76,8 +76,6 @@ typedef struct IscsiAIOCB {
     int status;
     int canceled;
     int retries;
-    size_t read_size;
-    size_t read_offset;
     int64_t sector_num;
     int nb_sectors;
 #ifdef __linux__

@@ -435,6 +433,7 @@ static int
 iscsi_aio_readv_acb(IscsiAIOCB *acb)
 {
     struct iscsi_context *iscsi = acb->iscsilun->iscsi;
+    size_t size;
     uint64_t lba;
     uint32_t num_sectors;
     int ret;

@@ -447,20 +446,7 @@ iscsi_aio_readv_acb(IscsiAIOCB *acb)
     acb->status      = -EINPROGRESS;
     acb->buf         = NULL;
 
-    /* If LUN blocksize is bigger than BDRV_BLOCK_SIZE a read from QEMU
-     * may be misaligned to the LUN, so we may need to read some extra
-     * data.
-     */
-    acb->read_offset = 0;
-    if (acb->iscsilun->block_size > BDRV_SECTOR_SIZE) {
-        uint64_t bdrv_offset = BDRV_SECTOR_SIZE * acb->sector_num;
-
-        acb->read_offset  = bdrv_offset % acb->iscsilun->block_size;
-    }
-
-    num_sectors  = (acb->read_size + acb->iscsilun->block_size
-                    + acb->read_offset - 1)
-                    / acb->iscsilun->block_size;
+    size = acb->nb_sectors * BDRV_SECTOR_SIZE;
 
     acb->task = malloc(sizeof(struct scsi_task));
     if (acb->task == NULL) {

@@ -471,8 +457,9 @@ iscsi_aio_readv_acb(IscsiAIOCB *acb)
     memset(acb->task, 0, sizeof(struct scsi_task));
 
     acb->task->xfer_dir = SCSI_XFER_READ;
+    acb->task->expxferlen = size;
     lba = sector_qemu2lun(acb->sector_num, acb->iscsilun);
-    acb->task->expxferlen = acb->read_size;
+    num_sectors = sector_qemu2lun(acb->nb_sectors, acb->iscsilun);
 
     switch (acb->iscsilun->type) {
     case TYPE_DISK:

@@ -527,7 +514,6 @@ iscsi_aio_readv(BlockDriverState *bs, int64_t sector_num,
     acb->sector_num  = sector_num;
     acb->iscsilun    = iscsilun;
     acb->qiov        = qiov;
-    acb->read_size   = BDRV_SECTOR_SIZE * (size_t)acb->nb_sectors;
     acb->retries     = ISCSI_CMD_RETRIES;
 
     if (iscsi_aio_readv_acb(acb) != 0) {

index 903f2fb..2b8fab9 100644
@@ -292,6 +292,18 @@ static int64_t sector_lun2qemu(int64_t sector, IscsiLun *iscsilun)
     return sector * iscsilun->block_size / BDRV_SECTOR_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 %ld, nb_sectors %d",
+                         iscsilun->block_size, sector_num, nb_sectors);
+            return 0;
+    }
+    return 1;
+}
+
 static int
 iscsi_aio_writev_acb(IscsiAIOCB *acb)
 {

@@ -376,6 +388,10 @@ iscsi_aio_writev(BlockDriverState *bs, int64_t sector_num,
     IscsiLun *iscsilun = bs->opaque;
     IscsiAIOCB *acb;
 
+    if (!is_request_lun_aligned(sector_num, nb_sectors, iscsilun)) {
+        return NULL;
+    }
+
     acb = qemu_aio_get(&iscsi_aiocb_info, bs, cb, opaque);
     trace_iscsi_aio_writev(iscsilun->iscsi, sector_num, nb_sectors, opaque, acb);
 

@@ -507,6 +523,10 @@ iscsi_aio_readv(BlockDriverState *bs, int64_t sector_num,
     IscsiLun *iscsilun = bs->opaque;
     IscsiAIOCB *acb;
 
+    if (!is_request_lun_aligned(sector_num, nb_sectors, iscsilun)) {
+        return NULL;
+    }
+
     acb = qemu_aio_get(&iscsi_aiocb_info, bs, cb, opaque);
     trace_iscsi_aio_readv(iscsilun->iscsi, sector_num, nb_sectors, opaque, acb);
 

@@ -774,6 +794,12 @@ static int coroutine_fn iscsi_co_is_allocated(BlockDriverState *bs,
     ret = 1;
     *pnum = nb_sectors;
 
+    if (!is_request_lun_aligned(sector_num, nb_sectors, iscsilun)) {
+        ret = 0;
+        *pnum = 0;
+        goto out;
+    }
+
     /* LUN does not support logical block provisioning */
     if (iscsilun->lbpme == 0) {
         goto out;

@@ -853,6 +879,10 @@ coroutine_fn iscsi_co_discard(BlockDriverState *bs, int64_t sector_num,
     struct unmap_list list;
     uint32_t nb_blocks;
 
+    if (!is_request_lun_aligned(sector_num, nb_sectors, iscsilun)) {
+        return -EINVAL;
+    }
+
     if (!iscsilun->lbpu) {
         return 0;
     }

@@ -903,6 +933,10 @@ coroutine_fn iscsi_co_write_zeroes(BlockDriverState *bs, int64_t sector_num,
 {
     IscsiLun *iscsilun = bs->opaque;
 
+    if (!is_request_lun_aligned(sector_num, nb_sectors, iscsilun)) {
+        return -EINVAL;
+    }
+
     if (!iscsilun->lbprz || !iscsilun->lbpu ||
         !(bs->open_flags & BDRV_O_UNMAP)) {
         /* fall back to writev */