[Qemu-devel] [PATCH 0/8] iscsi/qemu-img/block-migration enhancements

[Qemu-devel] [PATCH 0/8] iscsi/qemu-img/block-migration enhancements

[Peter Lieven]

this series adds logical block provisioning functions to the iscsi layer.
it adds the ability to write sparse images to iscsi targets which
support UNMAP and LBPRZ via qemu-img. additional block-migration is
enhanced to support an encoding for zero blocks on the network
and efficiently writing those zero blocks at the destination if
the driver supports it.

many thanks to Paolo, Kevin and Ronnie for their useful comments.

Peter

Peter Lieven (8):
  iscsi: add logical block provisioning information to iscsilun
  iscsi: add bdrv_co_is_allocated
  iscsi: add bdrv_co_write_zeroes
  block: add bdrv_write_zeroes()
  block/raw: add bdrv_co_write_zeroes
  qemu-img: use bdrv_write_zeroes to write zeroes
  iscsi: assert that sectors are aligned to LUN blocksize
  block-migration: efficiently encode zero blocks

 block-migration.c             |   29 ++++--
 block.c                       |   27 +++--
 block/iscsi.c                 |  220 +++++++++++++++++++++++++++++++++++++++++
 block/raw.c                   |    8 ++
 include/block/block.h         |    2 +
 include/migration/qemu-file.h |    1 +
 qemu-img.c                    |   10 +-
 savevm.c                      |    2 +-
 8 files changed, 281 insertions(+), 18 deletions(-)

-- 
1.7.9.5

[Qemu-devel] [PATCH 1/8] iscsi: add logical block provisioning information to iscsilun

[Peter Lieven]

Signed-off-by: Peter Lieven <pl@kamp.de>
---
 block/iscsi.c |   47 +++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 47 insertions(+)

diff --git a/block/iscsi.c b/block/iscsi.c
index 0bbf0b1..a38a1bf 100644
--- a/block/iscsi.c
+++ b/block/iscsi.c
@@ -49,6 +49,11 @@ 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;
 } IscsiLun;
 
 typedef struct IscsiAIOCB {
@@ -948,6 +953,8 @@ 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;
@@ -1130,6 +1137,46 @@ static int iscsi_open(BlockDriverState *bs, QDict *options, int flags)
         bs->sg = 1;
     }
 
+    if (iscsilun->lbpme) {
+        struct scsi_inquiry_logical_block_provisioning *inq_lbp;
+        int full_size;
+
+        task = iscsi_inquiry_sync(iscsi, iscsilun->lun, 1,
+                                  SCSI_INQUIRY_PAGECODE_LOGICAL_BLOCK_PROVISIONING,
+                                  64);
+        if (task == NULL || task->status != SCSI_STATUS_GOOD) {
+            error_report("iSCSI: Inquiry command failed : %s",
+                   iscsi_get_error(iscsilun->iscsi));
+            ret = -EINVAL;
+            goto out;
+        }
+        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, iscsilun->lun, 1,
+                                      SCSI_INQUIRY_PAGECODE_LOGICAL_BLOCK_PROVISIONING,
+                                      full_size);
+            if (task == NULL || task->status != SCSI_STATUS_GOOD) {
+                error_report("iSCSI: Inquiry command failed : %s",
+                             iscsi_get_error(iscsilun->iscsi));
+                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;
+    }
+
 #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);
-- 
1.7.9.5

Re: [Qemu-devel] [PATCH 1/8] iscsi: add logical block provisioning information to iscsilun

[Paolo Bonzini]

Il 22/06/2013 22:58, Peter Lieven ha scritto:
> Signed-off-by: Peter Lieven <pl@kamp.de>
> ---
>  block/iscsi.c |   47 +++++++++++++++++++++++++++++++++++++++++++++++
>  1 file changed, 47 insertions(+)
> 
> diff --git a/block/iscsi.c b/block/iscsi.c
> index 0bbf0b1..a38a1bf 100644
> --- a/block/iscsi.c
> +++ b/block/iscsi.c
> @@ -49,6 +49,11 @@ 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;
>  } IscsiLun;
>  
>  typedef struct IscsiAIOCB {
> @@ -948,6 +953,8 @@ 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;
> @@ -1130,6 +1137,46 @@ static int iscsi_open(BlockDriverState *bs, QDict *options, int flags)
>          bs->sg = 1;
>      }
>  
> +    if (iscsilun->lbpme) {
> +        struct scsi_inquiry_logical_block_provisioning *inq_lbp;
> +        int full_size;
> +
> +        task = iscsi_inquiry_sync(iscsi, iscsilun->lun, 1,
> +                                  SCSI_INQUIRY_PAGECODE_LOGICAL_BLOCK_PROVISIONING,
> +                                  64);
> +        if (task == NULL || task->status != SCSI_STATUS_GOOD) {
> +            error_report("iSCSI: Inquiry command failed : %s",
> +                   iscsi_get_error(iscsilun->iscsi));
> +            ret = -EINVAL;
> +            goto out;
> +        }
> +        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, iscsilun->lun, 1,
> +                                      SCSI_INQUIRY_PAGECODE_LOGICAL_BLOCK_PROVISIONING,
> +                                      full_size);
> +            if (task == NULL || task->status != SCSI_STATUS_GOOD) {
> +                error_report("iSCSI: Inquiry command failed : %s",
> +                             iscsi_get_error(iscsilun->iscsi));
> +                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;
> +    }
> +
>  #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);
> 

Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>

[Qemu-devel] [PATCH 2/8] iscsi: add bdrv_co_is_allocated

[Peter Lieven]

Signed-off-by: Peter Lieven <pl@kamp.de>
---
 block/iscsi.c |  103 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 103 insertions(+)

diff --git a/block/iscsi.c b/block/iscsi.c
index a38a1bf..98be71e 100644
--- a/block/iscsi.c
+++ b/block/iscsi.c
@@ -56,6 +56,15 @@ typedef struct IscsiLun {
     uint8_t lbpws10;
 } IscsiLun;
 
+typedef struct IscsiTask {
+    IscsiLun *iscsilun;
+    BlockDriverState *bs;
+    int status;
+    int complete;
+    Coroutine *co;
+    struct scsi_lba_status_descriptor lbasd;
+} IscsiTask;
+
 typedef struct IscsiAIOCB {
     BlockDriverAIOCB common;
     QEMUIOVector *qiov;
@@ -805,6 +814,98 @@ iscsi_getlength(BlockDriverState *bs)
     return len;
 }
 
+static void
+iscsi_co_is_allocated_cb(struct iscsi_context *iscsi, int status,
+                        void *command_data, void *opaque)
+{
+    struct IscsiTask *iTask = opaque;
+    struct scsi_task *task = command_data;
+    struct scsi_get_lba_status *lbas = NULL;
+
+    iTask->complete = 1;
+
+    if (status != 0) {
+        error_report("iSCSI: Failed to get_lba_status on iSCSI lun. %s",
+                     iscsi_get_error(iscsi));
+        iTask->status   = 1;
+        goto out;
+    }
+
+    lbas = scsi_datain_unmarshall(task);
+    if (lbas == NULL) {
+        iTask->status   = 1;
+        goto out;
+    }
+
+    memcpy(&iTask->lbasd, &lbas->descriptors[0],
+           sizeof(struct scsi_lba_status_descriptor));
+
+    iTask->status   = 0;
+
+out:
+    scsi_free_scsi_task(task);
+
+    if (iTask->co) {
+        qemu_coroutine_enter(iTask->co, NULL);
+    }
+}
+
+static int coroutine_fn iscsi_co_is_allocated(BlockDriverState *bs,
+                                              int64_t sector_num,
+                                              int nb_sectors, int *pnum)
+{
+    IscsiLun *iscsilun = bs->opaque;
+    struct IscsiTask iTask;
+    int ret;
+
+    *pnum = nb_sectors;
+
+    if (iscsilun->lbpme == 0) {
+        return 1;
+    }
+
+    iTask.iscsilun = iscsilun;
+    iTask.status = 0;
+    iTask.complete = 0;
+    iTask.bs = bs;
+
+    if (iscsi_get_lba_status_task(iscsilun->iscsi, iscsilun->lun,
+                                  sector_qemu2lun(sector_num, iscsilun),
+                                  8 + 16, iscsi_co_is_allocated_cb,
+                                  &iTask) == NULL) {
+        *pnum = 0;
+        return 0;
+    }
+
+    while (!iTask.complete) {
+        iscsi_set_events(iscsilun);
+        iTask.co = qemu_coroutine_self();
+        qemu_coroutine_yield();
+    }
+
+    if (iTask.status != 0) {
+        /* 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 */
+        return 1;
+    }
+
+    if (sector_qemu2lun(sector_num, iscsilun) != iTask.lbasd.lba) {
+        *pnum = 0;
+        return 0;
+    }
+
+    *pnum = iTask.lbasd.num_blocks * (iscsilun->block_size / BDRV_SECTOR_SIZE);
+    if (*pnum > nb_sectors) {
+        *pnum = nb_sectors;
+    }
+
+    return (iTask.lbasd.provisioning == SCSI_PROVISIONING_TYPE_MAPPED) ? 1 : 0;
+
+    return ret;
+}
+
 static int parse_chap(struct iscsi_context *iscsi, const char *target)
 {
     QemuOptsList *list;
@@ -1315,6 +1416,8 @@ 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,
-- 
1.7.9.5

Re: [Qemu-devel] [PATCH 2/8] iscsi: add bdrv_co_is_allocated

[Paolo Bonzini]

Il 22/06/2013 22:58, Peter Lieven ha scritto:
> Signed-off-by: Peter Lieven <pl@kamp.de>
> ---
>  block/iscsi.c |  103 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++
>  1 file changed, 103 insertions(+)
> 
> diff --git a/block/iscsi.c b/block/iscsi.c
> index a38a1bf..98be71e 100644
> --- a/block/iscsi.c
> +++ b/block/iscsi.c
> @@ -56,6 +56,15 @@ typedef struct IscsiLun {
>      uint8_t lbpws10;
>  } IscsiLun;
>  
> +typedef struct IscsiTask {
> +    IscsiLun *iscsilun;
> +    BlockDriverState *bs;
> +    int status;
> +    int complete;
> +    Coroutine *co;
> +    struct scsi_lba_status_descriptor lbasd;
> +} IscsiTask;
> +
>  typedef struct IscsiAIOCB {
>      BlockDriverAIOCB common;
>      QEMUIOVector *qiov;
> @@ -805,6 +814,98 @@ iscsi_getlength(BlockDriverState *bs)
>      return len;
>  }
>  
> +static void
> +iscsi_co_is_allocated_cb(struct iscsi_context *iscsi, int status,
> +                        void *command_data, void *opaque)
> +{
> +    struct IscsiTask *iTask = opaque;
> +    struct scsi_task *task = command_data;
> +    struct scsi_get_lba_status *lbas = NULL;
> +
> +    iTask->complete = 1;
> +
> +    if (status != 0) {
> +        error_report("iSCSI: Failed to get_lba_status on iSCSI lun. %s",
> +                     iscsi_get_error(iscsi));
> +        iTask->status   = 1;
> +        goto out;
> +    }
> +
> +    lbas = scsi_datain_unmarshall(task);
> +    if (lbas == NULL) {
> +        iTask->status   = 1;
> +        goto out;
> +    }
> +
> +    memcpy(&iTask->lbasd, &lbas->descriptors[0],
> +           sizeof(struct scsi_lba_status_descriptor));
> +
> +    iTask->status   = 0;
> +
> +out:
> +    scsi_free_scsi_task(task);
> +
> +    if (iTask->co) {
> +        qemu_coroutine_enter(iTask->co, NULL);
> +    }
> +}
> +
> +static int coroutine_fn iscsi_co_is_allocated(BlockDriverState *bs,
> +                                              int64_t sector_num,
> +                                              int nb_sectors, int *pnum)
> +{
> +    IscsiLun *iscsilun = bs->opaque;
> +    struct IscsiTask iTask;
> +    int ret;
> +
> +    *pnum = nb_sectors;
> +
> +    if (iscsilun->lbpme == 0) {
> +        return 1;
> +    }
> +
> +    iTask.iscsilun = iscsilun;
> +    iTask.status = 0;
> +    iTask.complete = 0;
> +    iTask.bs = bs;
> +
> +    if (iscsi_get_lba_status_task(iscsilun->iscsi, iscsilun->lun,
> +                                  sector_qemu2lun(sector_num, iscsilun),
> +                                  8 + 16, iscsi_co_is_allocated_cb,
> +                                  &iTask) == NULL) {
> +        *pnum = 0;
> +        return 0;
> +    }
> +
> +    while (!iTask.complete) {
> +        iscsi_set_events(iscsilun);
> +        iTask.co = qemu_coroutine_self();
> +        qemu_coroutine_yield();
> +    }
> +
> +    if (iTask.status != 0) {
> +        /* 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 */
> +        return 1;
> +    }
> +
> +    if (sector_qemu2lun(sector_num, iscsilun) != iTask.lbasd.lba) {
> +        *pnum = 0;
> +        return 0;
> +    }
> +
> +    *pnum = iTask.lbasd.num_blocks * (iscsilun->block_size / BDRV_SECTOR_SIZE);
> +    if (*pnum > nb_sectors) {
> +        *pnum = nb_sectors;
> +    }
> +
> +    return (iTask.lbasd.provisioning == SCSI_PROVISIONING_TYPE_MAPPED) ? 1 : 0;
> +
> +    return ret;
> +}
> +
>  static int parse_chap(struct iscsi_context *iscsi, const char *target)
>  {
>      QemuOptsList *list;
> @@ -1315,6 +1416,8 @@ 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,
> 

Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>

[Qemu-devel] [PATCH 3/8] iscsi: add bdrv_co_write_zeroes

[Peter Lieven]

write zeroes is emulated by unmap if the
target supports unmapping an unmapped blocks
read as zero.

Signed-off-by: Peter Lieven <pl@kamp.de>
---
 block/iscsi.c |   63 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 63 insertions(+)

diff --git a/block/iscsi.c b/block/iscsi.c
index 98be71e..683692a 100644
--- a/block/iscsi.c
+++ b/block/iscsi.c
@@ -906,6 +906,68 @@ static int coroutine_fn iscsi_co_is_allocated(BlockDriverState *bs,
     return ret;
 }
 
+static void
+iscsi_co_write_zeroes_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   = 0;
+
+    if (status != 0) {
+        error_report("iSCSI: Failed to unmap data on iSCSI lun. %s",
+                     iscsi_get_error(iscsi));
+        iTask->status   = 1;
+    }
+
+    scsi_free_scsi_task(task);
+
+    if (iTask->co) {
+        qemu_coroutine_enter(iTask->co, NULL);
+    }
+}
+
+static int
+coroutine_fn iscsi_co_write_zeroes(BlockDriverState *bs, int64_t sector_num,
+                                   int nb_sectors)
+{
+    IscsiLun *iscsilun = bs->opaque;
+    struct IscsiTask iTask;
+    struct unmap_list list[1];
+
+    if (!iscsilun->lbprz || !iscsilun->lbpu) {
+        /* fall back to writev */
+        return -ENOTSUP;
+    }
+
+    iTask.iscsilun = iscsilun;
+    iTask.status = 0;
+    iTask.complete = 0;
+    iTask.bs = bs;
+
+    list[0].lba = sector_qemu2lun(sector_num, iscsilun);
+    list[0].num = nb_sectors * BDRV_SECTOR_SIZE / iscsilun->block_size;
+
+    if (iscsi_unmap_task(iscsilun->iscsi, iscsilun->lun, 0, 0, &list[0], 1,
+                         iscsi_co_write_zeroes_cb, &iTask) == NULL) {
+        return -EIO;
+    }
+
+    while (!iTask.complete) {
+        iscsi_set_events(iscsilun);
+        iTask.co = qemu_coroutine_self();
+        qemu_coroutine_yield();
+    }
+
+    if (iTask.status != 0) {
+        return -EIO;
+    }
+
+    return 0;
+}
+
 static int parse_chap(struct iscsi_context *iscsi, const char *target)
 {
     QemuOptsList *list;
@@ -1417,6 +1479,7 @@ static BlockDriver bdrv_iscsi = {
     .bdrv_truncate   = iscsi_truncate,
 
     .bdrv_co_is_allocated = iscsi_co_is_allocated,
+    .bdrv_co_write_zeroes = iscsi_co_write_zeroes,
 
     .bdrv_aio_readv  = iscsi_aio_readv,
     .bdrv_aio_writev = iscsi_aio_writev,
-- 
1.7.9.5

Re: [Qemu-devel] [PATCH 3/8] iscsi: add bdrv_co_write_zeroes

[Paolo Bonzini]

Il 22/06/2013 22:58, Peter Lieven ha scritto:
> write zeroes is emulated by unmap if the
> target supports unmapping an unmapped blocks
> read as zero.

I think you should check BDRV_O_UNMAP in bs->open_flags, and not do this
optimization if it is not set.

Paolo

> Signed-off-by: Peter Lieven <pl@kamp.de>
> ---
>  block/iscsi.c |   63 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++
>  1 file changed, 63 insertions(+)
> 
> diff --git a/block/iscsi.c b/block/iscsi.c
> index 98be71e..683692a 100644
> --- a/block/iscsi.c
> +++ b/block/iscsi.c
> @@ -906,6 +906,68 @@ static int coroutine_fn iscsi_co_is_allocated(BlockDriverState *bs,
>      return ret;
>  }
>  
> +static void
> +iscsi_co_write_zeroes_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   = 0;
> +
> +    if (status != 0) {
> +        error_report("iSCSI: Failed to unmap data on iSCSI lun. %s",
> +                     iscsi_get_error(iscsi));
> +        iTask->status   = 1;
> +    }
> +
> +    scsi_free_scsi_task(task);
> +
> +    if (iTask->co) {
> +        qemu_coroutine_enter(iTask->co, NULL);
> +    }
> +}
> +
> +static int
> +coroutine_fn iscsi_co_write_zeroes(BlockDriverState *bs, int64_t sector_num,
> +                                   int nb_sectors)
> +{
> +    IscsiLun *iscsilun = bs->opaque;
> +    struct IscsiTask iTask;
> +    struct unmap_list list[1];
> +
> +    if (!iscsilun->lbprz || !iscsilun->lbpu) {
> +        /* fall back to writev */
> +        return -ENOTSUP;
> +    }
> +
> +    iTask.iscsilun = iscsilun;
> +    iTask.status = 0;
> +    iTask.complete = 0;
> +    iTask.bs = bs;
> +
> +    list[0].lba = sector_qemu2lun(sector_num, iscsilun);
> +    list[0].num = nb_sectors * BDRV_SECTOR_SIZE / iscsilun->block_size;
> +
> +    if (iscsi_unmap_task(iscsilun->iscsi, iscsilun->lun, 0, 0, &list[0], 1,
> +                         iscsi_co_write_zeroes_cb, &iTask) == NULL) {
> +        return -EIO;
> +    }
> +
> +    while (!iTask.complete) {
> +        iscsi_set_events(iscsilun);
> +        iTask.co = qemu_coroutine_self();
> +        qemu_coroutine_yield();
> +    }
> +
> +    if (iTask.status != 0) {
> +        return -EIO;
> +    }
> +
> +    return 0;
> +}
> +
>  static int parse_chap(struct iscsi_context *iscsi, const char *target)
>  {
>      QemuOptsList *list;
> @@ -1417,6 +1479,7 @@ static BlockDriver bdrv_iscsi = {
>      .bdrv_truncate   = iscsi_truncate,
>  
>      .bdrv_co_is_allocated = iscsi_co_is_allocated,
> +    .bdrv_co_write_zeroes = iscsi_co_write_zeroes,
>  
>      .bdrv_aio_readv  = iscsi_aio_readv,
>      .bdrv_aio_writev = iscsi_aio_writev,
> 

Re: [Qemu-devel] [PATCH 3/8] iscsi: add bdrv_co_write_zeroes

[Peter Lieven]

Am 24.06.2013 16:34, schrieb Paolo Bonzini:
> Il 22/06/2013 22:58, Peter Lieven ha scritto:
>> write zeroes is emulated by unmap if the
>> target supports unmapping an unmapped blocks
>> read as zero.
> I think you should check BDRV_O_UNMAP in bs->open_flags, and not do this
> optimization if it is not set.
Ok, I will change this. I will also patch iSCSI to return 0 if bdrv_co_discard
is called and the target does not support unmap.

In this case its save to set discard=on for iSCSI.

Peter
>
> Paolo
>
>> Signed-off-by: Peter Lieven <pl@kamp.de>
>> ---
>>  block/iscsi.c |   63 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++
>>  1 file changed, 63 insertions(+)
>>
>> diff --git a/block/iscsi.c b/block/iscsi.c
>> index 98be71e..683692a 100644
>> --- a/block/iscsi.c
>> +++ b/block/iscsi.c
>> @@ -906,6 +906,68 @@ static int coroutine_fn iscsi_co_is_allocated(BlockDriverState *bs,
>>      return ret;
>>  }
>>  
>> +static void
>> +iscsi_co_write_zeroes_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   = 0;
>> +
>> +    if (status != 0) {
>> +        error_report("iSCSI: Failed to unmap data on iSCSI lun. %s",
>> +                     iscsi_get_error(iscsi));
>> +        iTask->status   = 1;
>> +    }
>> +
>> +    scsi_free_scsi_task(task);
>> +
>> +    if (iTask->co) {
>> +        qemu_coroutine_enter(iTask->co, NULL);
>> +    }
>> +}
>> +
>> +static int
>> +coroutine_fn iscsi_co_write_zeroes(BlockDriverState *bs, int64_t sector_num,
>> +                                   int nb_sectors)
>> +{
>> +    IscsiLun *iscsilun = bs->opaque;
>> +    struct IscsiTask iTask;
>> +    struct unmap_list list[1];
>> +
>> +    if (!iscsilun->lbprz || !iscsilun->lbpu) {
>> +        /* fall back to writev */
>> +        return -ENOTSUP;
>> +    }
>> +
>> +    iTask.iscsilun = iscsilun;
>> +    iTask.status = 0;
>> +    iTask.complete = 0;
>> +    iTask.bs = bs;
>> +
>> +    list[0].lba = sector_qemu2lun(sector_num, iscsilun);
>> +    list[0].num = nb_sectors * BDRV_SECTOR_SIZE / iscsilun->block_size;
>> +
>> +    if (iscsi_unmap_task(iscsilun->iscsi, iscsilun->lun, 0, 0, &list[0], 1,
>> +                         iscsi_co_write_zeroes_cb, &iTask) == NULL) {
>> +        return -EIO;
>> +    }
>> +
>> +    while (!iTask.complete) {
>> +        iscsi_set_events(iscsilun);
>> +        iTask.co = qemu_coroutine_self();
>> +        qemu_coroutine_yield();
>> +    }
>> +
>> +    if (iTask.status != 0) {
>> +        return -EIO;
>> +    }
>> +
>> +    return 0;
>> +}
>> +
>>  static int parse_chap(struct iscsi_context *iscsi, const char *target)
>>  {
>>      QemuOptsList *list;
>> @@ -1417,6 +1479,7 @@ static BlockDriver bdrv_iscsi = {
>>      .bdrv_truncate   = iscsi_truncate,
>>  
>>      .bdrv_co_is_allocated = iscsi_co_is_allocated,
>> +    .bdrv_co_write_zeroes = iscsi_co_write_zeroes,
>>  
>>      .bdrv_aio_readv  = iscsi_aio_readv,
>>      .bdrv_aio_writev = iscsi_aio_writev,
>>

[Qemu-devel] [PATCH 4/8] block: add bdrv_write_zeroes()

[Peter Lieven]

Signed-off-by: Peter Lieven <pl@kamp.de>
---
 block.c               |   27 +++++++++++++++++++--------
 include/block/block.h |    2 ++
 2 files changed, 21 insertions(+), 8 deletions(-)

diff --git a/block.c b/block.c
index b88ad2f..e32b8cf 100644
--- a/block.c
+++ b/block.c
@@ -2163,6 +2163,7 @@ typedef struct RwCo {
     QEMUIOVector *qiov;
     bool is_write;
     int ret;
+    BdrvRequestFlags flags;
 } RwCo;
 
 static void coroutine_fn bdrv_rw_co_entry(void *opaque)
@@ -2171,10 +2172,12 @@ 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);
     }
 }
 
@@ -2182,7 +2185,8 @@ 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 = {
@@ -2192,6 +2196,7 @@ 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);
 
@@ -2223,7 +2228,7 @@ 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 = {
@@ -2232,14 +2237,14 @@ 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 */
@@ -2265,12 +2270,18 @@ 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,
diff --git a/include/block/block.h b/include/block/block.h
index 2307f67..5a062fa 100644
--- a/include/block/block.h
+++ b/include/block/block.h
@@ -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);
-- 
1.7.9.5

[Qemu-devel] [PATCH 5/8] block/raw: add bdrv_co_write_zeroes

[Peter Lieven]

Signed-off-by: Peter Lieven <pl@kamp.de>
---
 block/raw.c |    8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/block/raw.c b/block/raw.c
index ce10422..8c81de9 100644
--- a/block/raw.c
+++ b/block/raw.c
@@ -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,
-- 
1.7.9.5

[Qemu-devel] [PATCH 6/8] qemu-img: use bdrv_write_zeroes to write zeroes

[Peter Lieven]

Signed-off-by: Peter Lieven <pl@kamp.de>
---
 qemu-img.c |   10 +++++++---
 1 file changed, 7 insertions(+), 3 deletions(-)

diff --git a/qemu-img.c b/qemu-img.c
index 809b4f1..5aa53ab 100644
--- a/qemu-img.c
+++ b/qemu-img.c
@@ -1513,9 +1513,13 @@ static int img_convert(int argc, char **argv)
                    If the output is to a host device, we also write out
                    sectors that are entirely 0, since whatever data was
                    already there is garbage, not 0s. */
-                if (!has_zero_init || out_baseimg ||
-                    is_allocated_sectors_min(buf1, n, &n1, min_sparse)) {
-                    ret = bdrv_write(out_bs, sector_num, buf1, n1);
+                int allocated = is_allocated_sectors_min(buf1, n, &n1, min_sparse);
+                if (!has_zero_init || out_baseimg || allocated) {
+                    if (allocated || out_baseimg) {
+                        ret = bdrv_write(out_bs, sector_num, buf1, n1);
+                    } else {
+                        ret = bdrv_write_zeroes(out_bs, sector_num, n1);
+                    }
                     if (ret < 0) {
                         error_report("error while writing sector %" PRId64
                                      ": %s", sector_num, strerror(-ret));
-- 
1.7.9.5

Re: [Qemu-devel] [PATCH 6/8] qemu-img: use bdrv_write_zeroes to write zeroes

[Paolo Bonzini]

Il 22/06/2013 22:58, Peter Lieven ha scritto:
> Signed-off-by: Peter Lieven <pl@kamp.de>
> ---
>  qemu-img.c |   10 +++++++---
>  1 file changed, 7 insertions(+), 3 deletions(-)
> 
> diff --git a/qemu-img.c b/qemu-img.c
> index 809b4f1..5aa53ab 100644
> --- a/qemu-img.c
> +++ b/qemu-img.c
> @@ -1513,9 +1513,13 @@ static int img_convert(int argc, char **argv)
>                     If the output is to a host device, we also write out
>                     sectors that are entirely 0, since whatever data was
>                     already there is garbage, not 0s. */
> -                if (!has_zero_init || out_baseimg ||
> -                    is_allocated_sectors_min(buf1, n, &n1, min_sparse)) {
> -                    ret = bdrv_write(out_bs, sector_num, buf1, n1);
> +                int allocated = is_allocated_sectors_min(buf1, n, &n1, min_sparse);
> +                if (!has_zero_init || out_baseimg || allocated) {
> +                    if (allocated || out_baseimg) {
> +                        ret = bdrv_write(out_bs, sector_num, buf1, n1);
> +                    } else {
> +                        ret = bdrv_write_zeroes(out_bs, sector_num, n1);

I think it should still do the write only if !has_zero_init.

Paolo

> +                    }
>                      if (ret < 0) {
>                          error_report("error while writing sector %" PRId64
>                                       ": %s", sector_num, strerror(-ret));
> 

Re: [Qemu-devel] [PATCH 6/8] qemu-img: use bdrv_write_zeroes to write zeroes

[Peter Lieven]

Am 24.06.2013 16:33, schrieb Paolo Bonzini:
> Il 22/06/2013 22:58, Peter Lieven ha scritto:
>> Signed-off-by: Peter Lieven <pl@kamp.de>
>> ---
>>  qemu-img.c |   10 +++++++---
>>  1 file changed, 7 insertions(+), 3 deletions(-)
>>
>> diff --git a/qemu-img.c b/qemu-img.c
>> index 809b4f1..5aa53ab 100644
>> --- a/qemu-img.c
>> +++ b/qemu-img.c
>> @@ -1513,9 +1513,13 @@ static int img_convert(int argc, char **argv)
>>                     If the output is to a host device, we also write out
>>                     sectors that are entirely 0, since whatever data was
>>                     already there is garbage, not 0s. */
>> -                if (!has_zero_init || out_baseimg ||
>> -                    is_allocated_sectors_min(buf1, n, &n1, min_sparse)) {
>> -                    ret = bdrv_write(out_bs, sector_num, buf1, n1);
>> +                int allocated = is_allocated_sectors_min(buf1, n, &n1, min_sparse);
>> +                if (!has_zero_init || out_baseimg || allocated) {
>> +                    if (allocated || out_baseimg) {
>> +                        ret = bdrv_write(out_bs, sector_num, buf1, n1);
>> +                    } else {
>> +                        ret = bdrv_write_zeroes(out_bs, sector_num, n1);
> I think it should still do the write only if !has_zero_init.
With this I am still in trouble with iSCSI, but Kevin pointed out another
possible solution for the allocating everything problem.

a) let iscsi_create discard the whole device if lbpz && lbprz
b) return 1 for has_zero_init if lbprz.

What do you think?

Peter
>
> Paolo
>
>> +                    }
>>                      if (ret < 0) {
>>                          error_report("error while writing sector %" PRId64
>>                                       ": %s", sector_num, strerror(-ret));
>>

Re: [Qemu-devel] [PATCH 6/8] qemu-img: use bdrv_write_zeroes to write zeroes

[Paolo Bonzini]

Il 24/06/2013 18:17, Peter Lieven ha scritto:
> Am 24.06.2013 16:33, schrieb Paolo Bonzini:
>> Il 22/06/2013 22:58, Peter Lieven ha scritto:
>>> Signed-off-by: Peter Lieven <pl@kamp.de>
>>> ---
>>>  qemu-img.c |   10 +++++++---
>>>  1 file changed, 7 insertions(+), 3 deletions(-)
>>>
>>> diff --git a/qemu-img.c b/qemu-img.c
>>> index 809b4f1..5aa53ab 100644
>>> --- a/qemu-img.c
>>> +++ b/qemu-img.c
>>> @@ -1513,9 +1513,13 @@ static int img_convert(int argc, char **argv)
>>>                     If the output is to a host device, we also write out
>>>                     sectors that are entirely 0, since whatever data was
>>>                     already there is garbage, not 0s. */
>>> -                if (!has_zero_init || out_baseimg ||
>>> -                    is_allocated_sectors_min(buf1, n, &n1, min_sparse)) {
>>> -                    ret = bdrv_write(out_bs, sector_num, buf1, n1);
>>> +                int allocated = is_allocated_sectors_min(buf1, n, &n1, min_sparse);
>>> +                if (!has_zero_init || out_baseimg || allocated) {
>>> +                    if (allocated || out_baseimg) {
>>> +                        ret = bdrv_write(out_bs, sector_num, buf1, n1);
>>> +                    } else {
>>> +                        ret = bdrv_write_zeroes(out_bs, sector_num, n1);
>> I think it should still do the write only if !has_zero_init.
> With this I am still in trouble with iSCSI, but Kevin pointed out another
> possible solution for the allocating everything problem.
> 
> a) let iscsi_create discard the whole device if lbpz && lbprz
> b) return 1 for has_zero_init if lbprz.
> 
> What do you think?

Fine by me (but the discard may take a looong time! :)).

Paolo

Re: [Qemu-devel] [PATCH 6/8] qemu-img: use bdrv_write_zeroes to write zeroes

[Peter Lieven]

Am 24.06.2013 18:25, schrieb Paolo Bonzini:
> Il 24/06/2013 18:17, Peter Lieven ha scritto:
>> Am 24.06.2013 16:33, schrieb Paolo Bonzini:
>>> Il 22/06/2013 22:58, Peter Lieven ha scritto:
>>>> Signed-off-by: Peter Lieven <pl@kamp.de>
>>>> ---
>>>>  qemu-img.c |   10 +++++++---
>>>>  1 file changed, 7 insertions(+), 3 deletions(-)
>>>>
>>>> diff --git a/qemu-img.c b/qemu-img.c
>>>> index 809b4f1..5aa53ab 100644
>>>> --- a/qemu-img.c
>>>> +++ b/qemu-img.c
>>>> @@ -1513,9 +1513,13 @@ static int img_convert(int argc, char **argv)
>>>>                     If the output is to a host device, we also write out
>>>>                     sectors that are entirely 0, since whatever data was
>>>>                     already there is garbage, not 0s. */
>>>> -                if (!has_zero_init || out_baseimg ||
>>>> -                    is_allocated_sectors_min(buf1, n, &n1, min_sparse)) {
>>>> -                    ret = bdrv_write(out_bs, sector_num, buf1, n1);
>>>> +                int allocated = is_allocated_sectors_min(buf1, n, &n1, min_sparse);
>>>> +                if (!has_zero_init || out_baseimg || allocated) {
>>>> +                    if (allocated || out_baseimg) {
>>>> +                        ret = bdrv_write(out_bs, sector_num, buf1, n1);
>>>> +                    } else {
>>>> +                        ret = bdrv_write_zeroes(out_bs, sector_num, n1);
>>> I think it should still do the write only if !has_zero_init.
>> With this I am still in trouble with iSCSI, but Kevin pointed out another
>> possible solution for the allocating everything problem.
>>
>> a) let iscsi_create discard the whole device if lbpz && lbprz
>> b) return 1 for has_zero_init if lbprz.
>>
>> What do you think?
> Fine by me (but the discard may take a looong time! :)).
This was also my concern, but if a target advertises logical block
provisioning it should be able to discard blocks fast (and not overwrite all of
them or sth like that).

Peter
>
> Paolo
>

Re: [Qemu-devel] [PATCH 6/8] qemu-img: use bdrv_write_zeroes to write zeroes

[Peter Lieven]

Am 24.06.2013 18:25, schrieb Paolo Bonzini:
> Il 24/06/2013 18:17, Peter Lieven ha scritto:
>> Am 24.06.2013 16:33, schrieb Paolo Bonzini:
>>> Il 22/06/2013 22:58, Peter Lieven ha scritto:
>>>> Signed-off-by: Peter Lieven <pl@kamp.de>
>>>> ---
>>>>  qemu-img.c |   10 +++++++---
>>>>  1 file changed, 7 insertions(+), 3 deletions(-)
>>>>
>>>> diff --git a/qemu-img.c b/qemu-img.c
>>>> index 809b4f1..5aa53ab 100644
>>>> --- a/qemu-img.c
>>>> +++ b/qemu-img.c
>>>> @@ -1513,9 +1513,13 @@ static int img_convert(int argc, char **argv)
>>>>                     If the output is to a host device, we also write out
>>>>                     sectors that are entirely 0, since whatever data was
>>>>                     already there is garbage, not 0s. */
>>>> -                if (!has_zero_init || out_baseimg ||
>>>> -                    is_allocated_sectors_min(buf1, n, &n1, min_sparse)) {
>>>> -                    ret = bdrv_write(out_bs, sector_num, buf1, n1);
>>>> +                int allocated = is_allocated_sectors_min(buf1, n, &n1, min_sparse);
>>>> +                if (!has_zero_init || out_baseimg || allocated) {
>>>> +                    if (allocated || out_baseimg) {
>>>> +                        ret = bdrv_write(out_bs, sector_num, buf1, n1);
>>>> +                    } else {
>>>> +                        ret = bdrv_write_zeroes(out_bs, sector_num, n1);
>>> I think it should still do the write only if !has_zero_init.
>> With this I am still in trouble with iSCSI, but Kevin pointed out another
>> possible solution for the allocating everything problem.
>>
>> a) let iscsi_create discard the whole device if lbpz && lbprz
>> b) return 1 for has_zero_init if lbprz.
>>
>> What do you think?
> Fine by me (but the discard may take a looong time! :)).
fyi: i have created an optimized unmap function which transmits the
maximum allowed unmap_list length (read from block_limits page).

for 1TB it takes approx. 1 minute on my storage.

i will include this in v2 of the series and also add the optimization
to the other unmap calls (which currently do not check max_unmap
size at all).

Peter

[Qemu-devel] [PATCH 7/8] iscsi: assert that sectors are aligned to LUN blocksize

[Peter Lieven]

if the blocksize of an iSCSI LUN is bigger than the BDRV_SECTOR_SIZE
it is possible that sector_num or nb_sectors are not correctly
alligned.

for now assert that there is no misalignment to avoid data
corruption.

Signed-off-by: Peter Lieven <pl@kamp.de>
---
 block/iscsi.c |    7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/block/iscsi.c b/block/iscsi.c
index 683692a..2c410b1 100644
--- a/block/iscsi.c
+++ b/block/iscsi.c
@@ -249,6 +249,7 @@ iscsi_aio_write16_cb(struct iscsi_context *iscsi, int status,
 
 static int64_t sector_qemu2lun(int64_t sector, IscsiLun *iscsilun)
 {
+    assert((sector * BDRV_SECTOR_SIZE) % iscsilun->block_size == 0);
     return sector * BDRV_SECTOR_SIZE / iscsilun->block_size;
 }
 
@@ -269,6 +270,8 @@ iscsi_aio_writev_acb(IscsiAIOCB *acb)
     acb->status     = -EINPROGRESS;
     acb->buf        = NULL;
 
+    assert((acb->nb_sectors * BDRV_SECTOR_SIZE) % acb->iscsilun->block_size == 0);
+
     /* this will allow us to get rid of 'buf' completely */
     size = acb->nb_sectors * BDRV_SECTOR_SIZE;
 
@@ -618,6 +621,8 @@ static int iscsi_aio_discard_acb(IscsiAIOCB *acb) {
     acb->buf        = NULL;
 
     list[0].lba = sector_qemu2lun(acb->sector_num, acb->iscsilun);
+
+    assert((acb->nb_sectors * BDRV_SECTOR_SIZE) % acb->iscsilun->block_size == 0);
     list[0].num = acb->nb_sectors * BDRV_SECTOR_SIZE / acb->iscsilun->block_size;
 
     acb->task = iscsi_unmap_task(iscsi, acb->iscsilun->lun,
@@ -947,6 +952,8 @@ coroutine_fn iscsi_co_write_zeroes(BlockDriverState *bs, int64_t sector_num,
     iTask.complete = 0;
     iTask.bs = bs;
 
+    assert((nb_sectors * BDRV_SECTOR_SIZE) % iscsilun->block_size == 0);
+
     list[0].lba = sector_qemu2lun(sector_num, iscsilun);
     list[0].num = nb_sectors * BDRV_SECTOR_SIZE / iscsilun->block_size;
 
-- 
1.7.9.5

Re: [Qemu-devel] [PATCH 7/8] iscsi: assert that sectors are aligned to LUN blocksize

[Paolo Bonzini]

Il 22/06/2013 22:58, Peter Lieven ha scritto:
> if the blocksize of an iSCSI LUN is bigger than the BDRV_SECTOR_SIZE
> it is possible that sector_num or nb_sectors are not correctly
> alligned.
> 
> for now assert that there is no misalignment to avoid data
> corruption.

You should just fail to open the LUN instead.

Paolo

> Signed-off-by: Peter Lieven <pl@kamp.de>
> ---
>  block/iscsi.c |    7 +++++++
>  1 file changed, 7 insertions(+)
> 
> diff --git a/block/iscsi.c b/block/iscsi.c
> index 683692a..2c410b1 100644
> --- a/block/iscsi.c
> +++ b/block/iscsi.c
> @@ -249,6 +249,7 @@ iscsi_aio_write16_cb(struct iscsi_context *iscsi, int status,
>  
>  static int64_t sector_qemu2lun(int64_t sector, IscsiLun *iscsilun)
>  {
> +    assert((sector * BDRV_SECTOR_SIZE) % iscsilun->block_size == 0);
>      return sector * BDRV_SECTOR_SIZE / iscsilun->block_size;
>  }
>  
> @@ -269,6 +270,8 @@ iscsi_aio_writev_acb(IscsiAIOCB *acb)
>      acb->status     = -EINPROGRESS;
>      acb->buf        = NULL;
>  
> +    assert((acb->nb_sectors * BDRV_SECTOR_SIZE) % acb->iscsilun->block_size == 0);
> +
>      /* this will allow us to get rid of 'buf' completely */
>      size = acb->nb_sectors * BDRV_SECTOR_SIZE;
>  
> @@ -618,6 +621,8 @@ static int iscsi_aio_discard_acb(IscsiAIOCB *acb) {
>      acb->buf        = NULL;
>  
>      list[0].lba = sector_qemu2lun(acb->sector_num, acb->iscsilun);
> +
> +    assert((acb->nb_sectors * BDRV_SECTOR_SIZE) % acb->iscsilun->block_size == 0);
>      list[0].num = acb->nb_sectors * BDRV_SECTOR_SIZE / acb->iscsilun->block_size;
>  
>      acb->task = iscsi_unmap_task(iscsi, acb->iscsilun->lun,
> @@ -947,6 +952,8 @@ coroutine_fn iscsi_co_write_zeroes(BlockDriverState *bs, int64_t sector_num,
>      iTask.complete = 0;
>      iTask.bs = bs;
>  
> +    assert((nb_sectors * BDRV_SECTOR_SIZE) % iscsilun->block_size == 0);
> +
>      list[0].lba = sector_qemu2lun(sector_num, iscsilun);
>      list[0].num = nb_sectors * BDRV_SECTOR_SIZE / iscsilun->block_size;
>  
> 

Re: [Qemu-devel] [PATCH 7/8] iscsi: assert that sectors are aligned to LUN blocksize

[Peter Lieven]

Am 24.06.2013 16:30, schrieb Paolo Bonzini:
> Il 22/06/2013 22:58, Peter Lieven ha scritto:
>> if the blocksize of an iSCSI LUN is bigger than the BDRV_SECTOR_SIZE
>> it is possible that sector_num or nb_sectors are not correctly
>> alligned.
>>
>> for now assert that there is no misalignment to avoid data
>> corruption.
> You should just fail to open the LUN instead.
Ronnie added support for reading fragments of blocksize if the
offset is aligned. I don't know what the idea was, maybe for qemu
reading the boot sector. If the OS does only read multiple of
blocksize at aligned offsets everything should work. I now that
our storages support 4K blocksize. I can check if it is usable.
I could also just fail the operations instead of asserting.

Peter
>
> Paolo
>
>> Signed-off-by: Peter Lieven <pl@kamp.de>
>> ---
>>  block/iscsi.c |    7 +++++++
>>  1 file changed, 7 insertions(+)
>>
>> diff --git a/block/iscsi.c b/block/iscsi.c
>> index 683692a..2c410b1 100644
>> --- a/block/iscsi.c
>> +++ b/block/iscsi.c
>> @@ -249,6 +249,7 @@ iscsi_aio_write16_cb(struct iscsi_context *iscsi, int status,
>>  
>>  static int64_t sector_qemu2lun(int64_t sector, IscsiLun *iscsilun)
>>  {
>> +    assert((sector * BDRV_SECTOR_SIZE) % iscsilun->block_size == 0);
>>      return sector * BDRV_SECTOR_SIZE / iscsilun->block_size;
>>  }
>>  
>> @@ -269,6 +270,8 @@ iscsi_aio_writev_acb(IscsiAIOCB *acb)
>>      acb->status     = -EINPROGRESS;
>>      acb->buf        = NULL;
>>  
>> +    assert((acb->nb_sectors * BDRV_SECTOR_SIZE) % acb->iscsilun->block_size == 0);
>> +
>>      /* this will allow us to get rid of 'buf' completely */
>>      size = acb->nb_sectors * BDRV_SECTOR_SIZE;
>>  
>> @@ -618,6 +621,8 @@ static int iscsi_aio_discard_acb(IscsiAIOCB *acb) {
>>      acb->buf        = NULL;
>>  
>>      list[0].lba = sector_qemu2lun(acb->sector_num, acb->iscsilun);
>> +
>> +    assert((acb->nb_sectors * BDRV_SECTOR_SIZE) % acb->iscsilun->block_size == 0);
>>      list[0].num = acb->nb_sectors * BDRV_SECTOR_SIZE / acb->iscsilun->block_size;
>>  
>>      acb->task = iscsi_unmap_task(iscsi, acb->iscsilun->lun,
>> @@ -947,6 +952,8 @@ coroutine_fn iscsi_co_write_zeroes(BlockDriverState *bs, int64_t sector_num,
>>      iTask.complete = 0;
>>      iTask.bs = bs;
>>  
>> +    assert((nb_sectors * BDRV_SECTOR_SIZE) % iscsilun->block_size == 0);
>> +
>>      list[0].lba = sector_qemu2lun(sector_num, iscsilun);
>>      list[0].num = nb_sectors * BDRV_SECTOR_SIZE / iscsilun->block_size;
>>  
>>

Re: [Qemu-devel] [PATCH 7/8] iscsi: assert that sectors are aligned to LUN blocksize

[Paolo Bonzini]

Il 24/06/2013 18:10, Peter Lieven ha scritto:
> Am 24.06.2013 16:30, schrieb Paolo Bonzini:
>> Il 22/06/2013 22:58, Peter Lieven ha scritto:
>>> if the blocksize of an iSCSI LUN is bigger than the BDRV_SECTOR_SIZE
>>> it is possible that sector_num or nb_sectors are not correctly
>>> alligned.
>>>
>>> for now assert that there is no misalignment to avoid data
>>> corruption.
>> You should just fail to open the LUN instead.
> Ronnie added support for reading fragments of blocksize if the
> offset is aligned. I don't know what the idea was, maybe for qemu
> reading the boot sector. If the OS does only read multiple of
> blocksize at aligned offsets everything should work. I now that
> our storages support 4K blocksize. I can check if it is usable.
> I could also just fail the operations instead of asserting.

So far, 4K blocksize is usable if you also specify the same block size
for the guest device.  I have posted once the patches to do
read-modify-write, but I never really pursued inclusion of those.

In any case, the right place to fix this is the block layer;
driver-specific hacks are... hacks. :)

Paolo

Re: [Qemu-devel] [PATCH 7/8] iscsi: assert that sectors are aligned to LUN blocksize

[Peter Lieven]

Am 24.06.2013 18:13, schrieb Paolo Bonzini:
> Il 24/06/2013 18:10, Peter Lieven ha scritto:
>> Am 24.06.2013 16:30, schrieb Paolo Bonzini:
>>> Il 22/06/2013 22:58, Peter Lieven ha scritto:
>>>> if the blocksize of an iSCSI LUN is bigger than the BDRV_SECTOR_SIZE
>>>> it is possible that sector_num or nb_sectors are not correctly
>>>> alligned.
>>>>
>>>> for now assert that there is no misalignment to avoid data
>>>> corruption.
>>> You should just fail to open the LUN instead.
>> Ronnie added support for reading fragments of blocksize if the
>> offset is aligned. I don't know what the idea was, maybe for qemu
>> reading the boot sector. If the OS does only read multiple of
>> blocksize at aligned offsets everything should work. I now that
>> our storages support 4K blocksize. I can check if it is usable.
>> I could also just fail the operations instead of asserting.
> So far, 4K blocksize is usable if you also specify the same block size
> for the guest device.  I have posted once the patches to do
> read-modify-write, but I never really pursued inclusion of those.
>
> In any case, the right place to fix this is the block layer;
> driver-specific hacks are... hacks. :)
Where do I find the sector size if not in BDRV_SECTOR_SIZE?
Is there a dynamic field or is the answer qemu only support 512 Byte
sector size at the moment?

So you would go for fail to open a device if the LUN blocksize is
not equal to BDRV_SECTOR_SIZE?

Peter

Re: [Qemu-devel] [PATCH 7/8] iscsi: assert that sectors are aligned to LUN blocksize

[Paolo Bonzini]

Il 24/06/2013 18:24, Peter Lieven ha scritto:
>> > So far, 4K blocksize is usable if you also specify the same block size
>> > for the guest device.  I have posted once the patches to do
>> > read-modify-write, but I never really pursued inclusion of those.
>> >
>> > In any case, the right place to fix this is the block layer;
>> > driver-specific hacks are... hacks. :)
> Where do I find the sector size if not in BDRV_SECTOR_SIZE?
> Is there a dynamic field or is the answer qemu only support 512 Byte
> sector size at the moment?

bdrv_read/write and friends are always in 512-byte units.

There is bs->buffer_alignment for the guest sector size, but it is not
set at bdrv_open, only later.  So I think QEMU support for bigger
sectors is too sparse to be useful.

> So you would go for fail to open a device if the LUN blocksize is
> not equal to BDRV_SECTOR_SIZE?

Either that, or fails reads/writes that are not aligned.

Paolo

Re: [Qemu-devel] [PATCH 7/8] iscsi: assert that sectors are aligned to LUN blocksize

[Peter Lieven]

Am 24.06.2013 18:27, schrieb Paolo Bonzini:
> Il 24/06/2013 18:24, Peter Lieven ha scritto:
>>>> So far, 4K blocksize is usable if you also specify the same block size
>>>> for the guest device.  I have posted once the patches to do
>>>> read-modify-write, but I never really pursued inclusion of those.
>>>>
>>>> In any case, the right place to fix this is the block layer;
>>>> driver-specific hacks are... hacks. :)
>> Where do I find the sector size if not in BDRV_SECTOR_SIZE?
>> Is there a dynamic field or is the answer qemu only support 512 Byte
>> sector size at the moment?
> bdrv_read/write and friends are always in 512-byte units.
>
> There is bs->buffer_alignment for the guest sector size, but it is not
> set at bdrv_open, only later.  So I think QEMU support for bigger
> sectors is too sparse to be useful.
>
>> So you would go for fail to open a device if the LUN blocksize is
>> not equal to BDRV_SECTOR_SIZE?
> Either that, or fails reads/writes that are not aligned.
It would be the easiest. Maybe Ronnie can point out what the hack
with the acb->buffer_offset in aio_read was meant for. All other
functions have the requirement to be properly aligned regarding
to the xfersize. I am also not sure if the e.g. reading of 512 byte
at sector 0 from a 4K block device does still work with the
iovector patches we added earlier.

Peter
>
> Paolo

[Qemu-devel] [PATCH 8/8] block-migration: efficiently encode zero blocks

[Peter Lieven]

this patch adds a efficient encoding for zero blocks by
adding a new flag indiciating a block is completly zero.

additionally bdrv_write_zeros() is used at the destination
to efficiently write these zeroes. if the driver supports
it this avoids blindly allocating all sectors consumed by
zero blocks effectively re-thinning the device.

Signed-off-by: Peter Lieven <pl@kamp.de>
---
 block-migration.c             |   29 +++++++++++++++++++++++------
 include/migration/qemu-file.h |    1 +
 savevm.c                      |    2 +-
 3 files changed, 25 insertions(+), 7 deletions(-)

diff --git a/block-migration.c b/block-migration.c
index 2fd7699..99b3757 100644
--- a/block-migration.c
+++ b/block-migration.c
@@ -29,6 +29,7 @@
 #define BLK_MIG_FLAG_DEVICE_BLOCK       0x01
 #define BLK_MIG_FLAG_EOS                0x02
 #define BLK_MIG_FLAG_PROGRESS           0x04
+#define BLK_MIG_FLAG_ZERO_BLOCK         0x08
 
 #define MAX_IS_ALLOCATED_SEARCH 65536
 
@@ -114,16 +115,29 @@ static void blk_mig_unlock(void)
 static void blk_send(QEMUFile *f, BlkMigBlock * blk)
 {
     int len;
+    int flags = BLK_MIG_FLAG_DEVICE_BLOCK;
+    
+    if (buffer_is_zero(blk->buf, BLOCK_SIZE)) {
+        flags |= BLK_MIG_FLAG_ZERO_BLOCK;
+    }
 
     /* sector number and flags */
     qemu_put_be64(f, (blk->sector << BDRV_SECTOR_BITS)
-                     | BLK_MIG_FLAG_DEVICE_BLOCK);
+                     | flags);
 
     /* device name */
     len = strlen(blk->bmds->bs->device_name);
     qemu_put_byte(f, len);
     qemu_put_buffer(f, (uint8_t *)blk->bmds->bs->device_name, len);
 
+    /* if a block is zero we need to flush here since the network
+     * bandwidth is now a lot higher than the storage device bandwidth.
+     * thus if we queue zero blocks we slow down the migration */
+    if (flags & BLK_MIG_FLAG_ZERO_BLOCK) {
+        qemu_fflush(f);
+        return;
+    }
+
     qemu_put_buffer(f, blk->buf, BLOCK_SIZE);
 }
 
@@ -762,12 +776,15 @@ static int block_load(QEMUFile *f, void *opaque, int version_id)
                 nr_sectors = BDRV_SECTORS_PER_DIRTY_CHUNK;
             }
 
-            buf = g_malloc(BLOCK_SIZE);
-
-            qemu_get_buffer(f, buf, BLOCK_SIZE);
-            ret = bdrv_write(bs, addr, buf, nr_sectors);
+            if (flags & BLK_MIG_FLAG_ZERO_BLOCK) {
+                ret = bdrv_write_zeroes(bs, addr, nr_sectors);
+            } else {
+                buf = g_malloc(BLOCK_SIZE);
+                qemu_get_buffer(f, buf, BLOCK_SIZE);
+                ret = bdrv_write(bs, addr, buf, nr_sectors);
+                g_free(buf);
+            }
 
-            g_free(buf);
             if (ret < 0) {
                 return ret;
             }
diff --git a/include/migration/qemu-file.h b/include/migration/qemu-file.h
index 7519464..b73298d 100644
--- a/include/migration/qemu-file.h
+++ b/include/migration/qemu-file.h
@@ -71,6 +71,7 @@ QEMUFile *qemu_fdopen(int fd, const char *mode);
 QEMUFile *qemu_fopen_socket(int fd, const char *mode);
 QEMUFile *qemu_popen_cmd(const char *command, const char *mode);
 int qemu_get_fd(QEMUFile *f);
+void qemu_fflush(QEMUFile *f);
 int qemu_fclose(QEMUFile *f);
 int64_t qemu_ftell(QEMUFile *f);
 void qemu_put_buffer(QEMUFile *f, const uint8_t *buf, int size);
diff --git a/savevm.c b/savevm.c
index ff5ece6..4d12d92 100644
--- a/savevm.c
+++ b/savevm.c
@@ -610,7 +610,7 @@ static inline bool qemu_file_is_writable(QEMUFile *f)
  * If there is writev_buffer QEMUFileOps it uses it otherwise uses
  * put_buffer ops.
  */
-static void qemu_fflush(QEMUFile *f)
+void qemu_fflush(QEMUFile *f)
 {
     ssize_t ret = 0;
 
-- 
1.7.9.5

Re: [Qemu-devel] [PATCH 8/8] block-migration: efficiently encode zero blocks

[Paolo Bonzini]

Il 22/06/2013 22:58, Peter Lieven ha scritto:
> this patch adds a efficient encoding for zero blocks by
> adding a new flag indiciating a block is completly zero.
> 
> additionally bdrv_write_zeros() is used at the destination
> to efficiently write these zeroes. if the driver supports
> it this avoids blindly allocating all sectors consumed by
> zero blocks effectively re-thinning the device.
> 
> Signed-off-by: Peter Lieven <pl@kamp.de>

This is a bit ugly because it doesn't work with drive-mirror.  Perhaps
we can add a write-zeroes opcode to NBD, too.

Paolo

> ---
>  block-migration.c             |   29 +++++++++++++++++++++++------
>  include/migration/qemu-file.h |    1 +
>  savevm.c                      |    2 +-
>  3 files changed, 25 insertions(+), 7 deletions(-)
> 
> diff --git a/block-migration.c b/block-migration.c
> index 2fd7699..99b3757 100644
> --- a/block-migration.c
> +++ b/block-migration.c
> @@ -29,6 +29,7 @@
>  #define BLK_MIG_FLAG_DEVICE_BLOCK       0x01
>  #define BLK_MIG_FLAG_EOS                0x02
>  #define BLK_MIG_FLAG_PROGRESS           0x04
> +#define BLK_MIG_FLAG_ZERO_BLOCK         0x08
>  
>  #define MAX_IS_ALLOCATED_SEARCH 65536
>  
> @@ -114,16 +115,29 @@ static void blk_mig_unlock(void)
>  static void blk_send(QEMUFile *f, BlkMigBlock * blk)
>  {
>      int len;
> +    int flags = BLK_MIG_FLAG_DEVICE_BLOCK;
> +    
> +    if (buffer_is_zero(blk->buf, BLOCK_SIZE)) {
> +        flags |= BLK_MIG_FLAG_ZERO_BLOCK;
> +    }
>  
>      /* sector number and flags */
>      qemu_put_be64(f, (blk->sector << BDRV_SECTOR_BITS)
> -                     | BLK_MIG_FLAG_DEVICE_BLOCK);
> +                     | flags);
>  
>      /* device name */
>      len = strlen(blk->bmds->bs->device_name);
>      qemu_put_byte(f, len);
>      qemu_put_buffer(f, (uint8_t *)blk->bmds->bs->device_name, len);
>  
> +    /* if a block is zero we need to flush here since the network
> +     * bandwidth is now a lot higher than the storage device bandwidth.
> +     * thus if we queue zero blocks we slow down the migration */
> +    if (flags & BLK_MIG_FLAG_ZERO_BLOCK) {
> +        qemu_fflush(f);
> +        return;
> +    }
> +
>      qemu_put_buffer(f, blk->buf, BLOCK_SIZE);
>  }
>  
> @@ -762,12 +776,15 @@ static int block_load(QEMUFile *f, void *opaque, int version_id)
>                  nr_sectors = BDRV_SECTORS_PER_DIRTY_CHUNK;
>              }
>  
> -            buf = g_malloc(BLOCK_SIZE);
> -
> -            qemu_get_buffer(f, buf, BLOCK_SIZE);
> -            ret = bdrv_write(bs, addr, buf, nr_sectors);
> +            if (flags & BLK_MIG_FLAG_ZERO_BLOCK) {
> +                ret = bdrv_write_zeroes(bs, addr, nr_sectors);
> +            } else {
> +                buf = g_malloc(BLOCK_SIZE);
> +                qemu_get_buffer(f, buf, BLOCK_SIZE);
> +                ret = bdrv_write(bs, addr, buf, nr_sectors);
> +                g_free(buf);
> +            }
>  
> -            g_free(buf);
>              if (ret < 0) {
>                  return ret;
>              }
> diff --git a/include/migration/qemu-file.h b/include/migration/qemu-file.h
> index 7519464..b73298d 100644
> --- a/include/migration/qemu-file.h
> +++ b/include/migration/qemu-file.h
> @@ -71,6 +71,7 @@ QEMUFile *qemu_fdopen(int fd, const char *mode);
>  QEMUFile *qemu_fopen_socket(int fd, const char *mode);
>  QEMUFile *qemu_popen_cmd(const char *command, const char *mode);
>  int qemu_get_fd(QEMUFile *f);
> +void qemu_fflush(QEMUFile *f);
>  int qemu_fclose(QEMUFile *f);
>  int64_t qemu_ftell(QEMUFile *f);
>  void qemu_put_buffer(QEMUFile *f, const uint8_t *buf, int size);
> diff --git a/savevm.c b/savevm.c
> index ff5ece6..4d12d92 100644
> --- a/savevm.c
> +++ b/savevm.c
> @@ -610,7 +610,7 @@ static inline bool qemu_file_is_writable(QEMUFile *f)
>   * If there is writev_buffer QEMUFileOps it uses it otherwise uses
>   * put_buffer ops.
>   */
> -static void qemu_fflush(QEMUFile *f)
> +void qemu_fflush(QEMUFile *f)
>  {
>      ssize_t ret = 0;
>  
> 

Re: [Qemu-devel] [PATCH 8/8] block-migration: efficiently encode zero blocks

[Peter Lieven]

Am 24.06.2013 16:32, schrieb Paolo Bonzini:
> Il 22/06/2013 22:58, Peter Lieven ha scritto:
>> this patch adds a efficient encoding for zero blocks by
>> adding a new flag indiciating a block is completly zero.
>>
>> additionally bdrv_write_zeros() is used at the destination
>> to efficiently write these zeroes. if the driver supports
>> it this avoids blindly allocating all sectors consumed by
>> zero blocks effectively re-thinning the device.
>>
>> Signed-off-by: Peter Lieven <pl@kamp.de>
> This is a bit ugly because it doesn't work with drive-mirror.  Perhaps
> we can add a write-zeroes opcode to NBD, too.
That is the exact problem with NBD. If write zeroes is not supported
the routine falls back to write zeros with writev.

Peter
>
> Paolo
>
>> ---
>>  block-migration.c             |   29 +++++++++++++++++++++++------
>>  include/migration/qemu-file.h |    1 +
>>  savevm.c                      |    2 +-
>>  3 files changed, 25 insertions(+), 7 deletions(-)
>>
>> diff --git a/block-migration.c b/block-migration.c
>> index 2fd7699..99b3757 100644
>> --- a/block-migration.c
>> +++ b/block-migration.c
>> @@ -29,6 +29,7 @@
>>  #define BLK_MIG_FLAG_DEVICE_BLOCK       0x01
>>  #define BLK_MIG_FLAG_EOS                0x02
>>  #define BLK_MIG_FLAG_PROGRESS           0x04
>> +#define BLK_MIG_FLAG_ZERO_BLOCK         0x08
>>  
>>  #define MAX_IS_ALLOCATED_SEARCH 65536
>>  
>> @@ -114,16 +115,29 @@ static void blk_mig_unlock(void)
>>  static void blk_send(QEMUFile *f, BlkMigBlock * blk)
>>  {
>>      int len;
>> +    int flags = BLK_MIG_FLAG_DEVICE_BLOCK;
>> +    
>> +    if (buffer_is_zero(blk->buf, BLOCK_SIZE)) {
>> +        flags |= BLK_MIG_FLAG_ZERO_BLOCK;
>> +    }
>>  
>>      /* sector number and flags */
>>      qemu_put_be64(f, (blk->sector << BDRV_SECTOR_BITS)
>> -                     | BLK_MIG_FLAG_DEVICE_BLOCK);
>> +                     | flags);
>>  
>>      /* device name */
>>      len = strlen(blk->bmds->bs->device_name);
>>      qemu_put_byte(f, len);
>>      qemu_put_buffer(f, (uint8_t *)blk->bmds->bs->device_name, len);
>>  
>> +    /* if a block is zero we need to flush here since the network
>> +     * bandwidth is now a lot higher than the storage device bandwidth.
>> +     * thus if we queue zero blocks we slow down the migration */
>> +    if (flags & BLK_MIG_FLAG_ZERO_BLOCK) {
>> +        qemu_fflush(f);
>> +        return;
>> +    }
>> +
>>      qemu_put_buffer(f, blk->buf, BLOCK_SIZE);
>>  }
>>  
>> @@ -762,12 +776,15 @@ static int block_load(QEMUFile *f, void *opaque, int version_id)
>>                  nr_sectors = BDRV_SECTORS_PER_DIRTY_CHUNK;
>>              }
>>  
>> -            buf = g_malloc(BLOCK_SIZE);
>> -
>> -            qemu_get_buffer(f, buf, BLOCK_SIZE);
>> -            ret = bdrv_write(bs, addr, buf, nr_sectors);
>> +            if (flags & BLK_MIG_FLAG_ZERO_BLOCK) {
>> +                ret = bdrv_write_zeroes(bs, addr, nr_sectors);
>> +            } else {
>> +                buf = g_malloc(BLOCK_SIZE);
>> +                qemu_get_buffer(f, buf, BLOCK_SIZE);
>> +                ret = bdrv_write(bs, addr, buf, nr_sectors);
>> +                g_free(buf);
>> +            }
>>  
>> -            g_free(buf);
>>              if (ret < 0) {
>>                  return ret;
>>              }
>> diff --git a/include/migration/qemu-file.h b/include/migration/qemu-file.h
>> index 7519464..b73298d 100644
>> --- a/include/migration/qemu-file.h
>> +++ b/include/migration/qemu-file.h
>> @@ -71,6 +71,7 @@ QEMUFile *qemu_fdopen(int fd, const char *mode);
>>  QEMUFile *qemu_fopen_socket(int fd, const char *mode);
>>  QEMUFile *qemu_popen_cmd(const char *command, const char *mode);
>>  int qemu_get_fd(QEMUFile *f);
>> +void qemu_fflush(QEMUFile *f);
>>  int qemu_fclose(QEMUFile *f);
>>  int64_t qemu_ftell(QEMUFile *f);
>>  void qemu_put_buffer(QEMUFile *f, const uint8_t *buf, int size);
>> diff --git a/savevm.c b/savevm.c
>> index ff5ece6..4d12d92 100644
>> --- a/savevm.c
>> +++ b/savevm.c
>> @@ -610,7 +610,7 @@ static inline bool qemu_file_is_writable(QEMUFile *f)
>>   * If there is writev_buffer QEMUFileOps it uses it otherwise uses
>>   * put_buffer ops.
>>   */
>> -static void qemu_fflush(QEMUFile *f)
>> +void qemu_fflush(QEMUFile *f)
>>  {
>>      ssize_t ret = 0;
>>  
>>