3:58 a.m.
See 03 commit message for details. 01-02 are preparation docs update.
v4: deprecate drive-backup transaction by squashing
[PATCH v4 5/5] block: Deprecate transaction type drive-backup
Message-Id: <20211025042405.3762351-6-armbru(a)redhat.com>
into PATCH 3
v3: wording fix-ups and improvements suggested by Kashyap
v2: add a lot of documentation changes
v1 was "[PATCH] qapi: deprecate drive-backup"
Vladimir Sementsov-Ogievskiy (3):
docs/block-replication: use blockdev-backup
docs/interop/bitmaps: use blockdev-backup
qapi: deprecate drive-backup
docs/about/deprecated.rst | 11 +
docs/block-replication.txt | 4 +-
docs/interop/bitmaps.rst | 285 +++++++++++++++++++------
docs/interop/live-block-operations.rst | 47 ++--
qapi/block-core.json | 5 +-
qapi/transaction.json | 6 +-
6 files changed, 268 insertions(+), 90 deletions(-)
--
2.31.1
3:58 a.m.
New subject: [PATCH v4 1/3] docs/block-replication: use blockdev-backup
From: Vladimir Sementsov-Ogievskiy <vsementsov(a)virtuozzo.com>
We are going to deprecate drive-backup, so don't mention it here.
Moreover, blockdev-backup seems more correct in the context.
Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov(a)virtuozzo.com>
Reviewed-by: John Snow <jsnow(a)redhat.com>
Signed-off-by: Markus Armbruster <armbru(a)redhat.com>
---
docs/block-replication.txt | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/docs/block-replication.txt b/docs/block-replication.txt
index 108e9166a8..59eb2b33b3 100644
--- a/docs/block-replication.txt
+++ b/docs/block-replication.txt
@@ -79,7 +79,7 @@ Primary | || Secondary disk <--------- hidden-disk 5
<---------
|| | |
|| | |
|| '-------------------------'
- || drive-backup sync=none 6
+ || blockdev-backup sync=none 6
1) The disk on the primary is represented by a block device with two
children, providing replication between a primary disk and the host that
@@ -101,7 +101,7 @@ should support bdrv_make_empty() and backing file.
that is modified by the primary VM. It should also start as an empty disk,
and the driver supports bdrv_make_empty() and backing file.
-6) The drive-backup job (sync=none) is run to allow hidden-disk to buffer
+6) The blockdev-backup job (sync=none) is run to allow hidden-disk to buffer
any state that would otherwise be lost by the speculative write-through
of the NBD server into the secondary disk. So before block replication,
the primary disk and secondary disk should contain the same data.
--
2.31.1
3:58 a.m.
New subject: [PATCH v4 2/3] docs/interop/bitmaps: use blockdev-backup
From: Vladimir Sementsov-Ogievskiy <vsementsov(a)virtuozzo.com>
We are going to deprecate drive-backup, so use modern interface here.
In examples where target image creation is shown, show blockdev-add as
well. If target creation omitted, omit blockdev-add as well.
Reviewed-by: Kashyap Chamarthy <kchamart(a)redhat.com>
Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov(a)virtuozzo.com>
Signed-off-by: Markus Armbruster <armbru(a)redhat.com>
---
docs/interop/bitmaps.rst | 285 +++++++++++++++++++++++++++++----------
1 file changed, 215 insertions(+), 70 deletions(-)
diff --git a/docs/interop/bitmaps.rst b/docs/interop/bitmaps.rst
index 059ad67929..1de46febdc 100644
--- a/docs/interop/bitmaps.rst
+++ b/docs/interop/bitmaps.rst
@@ -539,12 +539,11 @@ other partial disk images on top of a base image to reconstruct a
full backup
from the point in time at which the incremental backup was issued.
The "Push Model" here references the fact that QEMU is "pushing" the
modified
-blocks out to a destination. We will be using the `drive-backup
-<qemu-qmp-ref.html#index-drive_002dbackup>`_ and `blockdev-backup
-<qemu-qmp-ref.html#index-blockdev_002dbackup>`_ QMP commands to create both
+blocks out to a destination. We will be using the `blockdev-backup
+<qemu-qmp-ref.html#index-blockdev_002dbackup>`_ QMP command to create both
full and incremental backups.
-Both of these commands are jobs, which have their own QMP API for querying and
+The command is a background job, which has its own QMP API for querying and
management documented in `Background jobs
<qemu-qmp-ref.html#Background-jobs>`_.
@@ -557,6 +556,10 @@ create a new incremental backup chain attached to a drive.
This example creates a new, full backup of "drive0" and accompanies it with a
new, empty bitmap that records writes from this point in time forward.
+The target can be created with the help of `blockdev-add
+<qemu-qmp-ref.html#index-blockdev_002dadd>`_ or `blockdev-create
+<qemu-qmp-ref.html#index-blockdev_002dcreate>`_ command.
+
.. note:: Any new writes that happen after this command is issued, even while
the backup job runs, will be written locally and not to the backup
destination. These writes will be recorded in the bitmap
@@ -576,12 +579,11 @@ new, empty bitmap that records writes from this point in time
forward.
}
},
{
- "type": "drive-backup",
+ "type": "blockdev-backup",
"data": {
"device": "drive0",
- "target": "/path/to/drive0.full.qcow2",
- "sync": "full",
- "format": "qcow2"
+ "target": "target0",
+ "sync": "full"
}
}
]
@@ -664,12 +666,11 @@ use a transaction to reset the bitmap while making a new full
backup:
}
},
{
- "type": "drive-backup",
+ "type": "blockdev-backup",
"data": {
"device": "drive0",
- "target": "/path/to/drive0.new_full.qcow2",
- "sync": "full",
- "format": "qcow2"
+ "target": "target0",
+ "sync": "full"
}
}
]
@@ -728,19 +729,35 @@ Example: First Incremental Backup
$ qemu-img create -f qcow2 drive0.inc0.qcow2 \
-b drive0.full.qcow2 -F qcow2
+#. Add target block node:
+
+ .. code-block:: QMP
+
+ -> {
+ "execute": "blockdev-add",
+ "arguments": {
+ "node-name": "target0",
+ "driver": "qcow2",
+ "file": {
+ "driver": "file",
+ "filename": "drive0.inc0.qcow2"
+ }
+ }
+ }
+
+ <- { "return": {} }
+
#. Issue an incremental backup command:
.. code-block:: QMP
-> {
- "execute": "drive-backup",
+ "execute": "blockdev-backup",
"arguments": {
"device": "drive0",
"bitmap": "bitmap0",
- "target": "drive0.inc0.qcow2",
- "format": "qcow2",
- "sync": "incremental",
- "mode": "existing"
+ "target": "target0",
+ "sync": "incremental"
}
}
@@ -785,20 +802,36 @@ Example: Second Incremental Backup
$ qemu-img create -f qcow2 drive0.inc1.qcow2 \
-b drive0.inc0.qcow2 -F qcow2
+#. Add target block node:
+
+ .. code-block:: QMP
+
+ -> {
+ "execute": "blockdev-add",
+ "arguments": {
+ "node-name": "target0",
+ "driver": "qcow2",
+ "file": {
+ "driver": "file",
+ "filename": "drive0.inc1.qcow2"
+ }
+ }
+ }
+
+ <- { "return": {} }
+
#. Issue a new incremental backup command. The only difference here is that we
have changed the target image below.
.. code-block:: QMP
-> {
- "execute": "drive-backup",
+ "execute": "blockdev-backup",
"arguments": {
"device": "drive0",
"bitmap": "bitmap0",
- "target": "drive0.inc1.qcow2",
- "format": "qcow2",
- "sync": "incremental",
- "mode": "existing"
+ "target": "target0",
+ "sync": "incremental"
}
}
@@ -866,20 +899,36 @@ image:
file for you, but you lose control over format options like
compatibility and preallocation presets.
+#. Add target block node:
+
+ .. code-block:: QMP
+
+ -> {
+ "execute": "blockdev-add",
+ "arguments": {
+ "node-name": "target0",
+ "driver": "qcow2",
+ "file": {
+ "driver": "file",
+ "filename": "drive0.inc2.qcow2"
+ }
+ }
+ }
+
+ <- { "return": {} }
+
#. Issue a new incremental backup command. Apart from the new destination
image, there is no difference from the last two examples.
.. code-block:: QMP
-> {
- "execute": "drive-backup",
+ "execute": "blockdev-backup",
"arguments": {
"device": "drive0",
"bitmap": "bitmap0",
- "target": "drive0.inc2.qcow2",
- "format": "qcow2",
- "sync": "incremental",
- "mode": "existing"
+ "target": "target0",
+ "sync": "incremental"
}
}
@@ -930,6 +979,38 @@ point in time.
$ qemu-img create -f qcow2 drive0.full.qcow2 64G
$ qemu-img create -f qcow2 drive1.full.qcow2 64G
+#. Add target block nodes:
+
+ .. code-block:: QMP
+
+ -> {
+ "execute": "blockdev-add",
+ "arguments": {
+ "node-name": "target0",
+ "driver": "qcow2",
+ "file": {
+ "driver": "file",
+ "filename": "drive0.full.qcow2"
+ }
+ }
+ }
+
+ <- { "return": {} }
+
+ -> {
+ "execute": "blockdev-add",
+ "arguments": {
+ "node-name": "target1",
+ "driver": "qcow2",
+ "file": {
+ "driver": "file",
+ "filename": "drive1.full.qcow2"
+ }
+ }
+ }
+
+ <- { "return": {} }
+
#. Create a full (anchor) backup for each drive, with accompanying bitmaps:
.. code-block:: QMP
@@ -953,21 +1034,19 @@ point in time.
}
},
{
- "type": "drive-backup",
+ "type": "blockdev-backup",
"data": {
"device": "drive0",
- "target": "/path/to/drive0.full.qcow2",
- "sync": "full",
- "format": "qcow2"
+ "target": "target0",
+ "sync": "full"
}
},
{
- "type": "drive-backup",
+ "type": "blockdev-backup",
"data": {
"device": "drive1",
- "target": "/path/to/drive1.full.qcow2",
- "sync": "full",
- "format": "qcow2"
+ "target": "target1",
+ "sync": "full"
}
}
]
@@ -1016,6 +1095,38 @@ point in time.
$ qemu-img create -f qcow2 drive1.inc0.qcow2 \
-b drive1.full.qcow2 -F qcow2
+#. Add target block nodes:
+
+ .. code-block:: QMP
+
+ -> {
+ "execute": "blockdev-add",
+ "arguments": {
+ "node-name": "target0",
+ "driver": "qcow2",
+ "file": {
+ "driver": "file",
+ "filename": "drive0.inc0.qcow2"
+ }
+ }
+ }
+
+ <- { "return": {} }
+
+ -> {
+ "execute": "blockdev-add",
+ "arguments": {
+ "node-name": "target1",
+ "driver": "qcow2",
+ "file": {
+ "driver": "file",
+ "filename": "drive1.inc0.qcow2"
+ }
+ }
+ }
+
+ <- { "return": {} }
+
#. Issue a multi-drive incremental push backup transaction:
.. code-block:: QMP
@@ -1025,25 +1136,21 @@ point in time.
"arguments": {
"actions": [
{
- "type": "drive-backup",
+ "type": "blockev-backup",
"data": {
"device": "drive0",
"bitmap": "bitmap0",
- "format": "qcow2",
- "mode": "existing",
"sync": "incremental",
- "target": "drive0.inc0.qcow2"
+ "target": "target0"
}
},
{
- "type": "drive-backup",
+ "type": "blockdev-backup",
"data": {
"device": "drive1",
"bitmap": "bitmap0",
- "format": "qcow2",
- "mode": "existing",
"sync": "incremental",
- "target": "drive1.inc0.qcow2"
+ "target": "target1"
}
},
]
@@ -1119,19 +1226,35 @@ described above. This example demonstrates the single-job failure
case:
$ qemu-img create -f qcow2 drive0.inc0.qcow2 \
-b drive0.full.qcow2 -F qcow2
+#. Add target block node:
+
+ .. code-block:: QMP
+
+ -> {
+ "execute": "blockdev-add",
+ "arguments": {
+ "node-name": "target0",
+ "driver": "qcow2",
+ "file": {
+ "driver": "file",
+ "filename": "drive0.inc0.qcow2"
+ }
+ }
+ }
+
+ <- { "return": {} }
+
#. Attempt to create an incremental backup via QMP:
.. code-block:: QMP
-> {
- "execute": "drive-backup",
+ "execute": "blockdev-backup",
"arguments": {
"device": "drive0",
"bitmap": "bitmap0",
- "target": "drive0.inc0.qcow2",
- "format": "qcow2",
- "sync": "incremental",
- "mode": "existing"
+ "target": "target0",
+ "sync": "incremental"
}
}
@@ -1164,6 +1287,19 @@ described above. This example demonstrates the single-job failure
case:
"event": "BLOCK_JOB_COMPLETED"
}
+#. Remove target node:
+
+ .. code-block:: QMP
+
+ -> {
+ "execute": "blockdev-del",
+ "arguments": {
+ "node-name": "target0",
+ }
+ }
+
+ <- { "return": {} }
+
#. Delete the failed image, and re-create it.
.. code:: bash
@@ -1172,20 +1308,36 @@ described above. This example demonstrates the single-job failure
case:
$ qemu-img create -f qcow2 drive0.inc0.qcow2 \
-b drive0.full.qcow2 -F qcow2
+#. Add target block node:
+
+ .. code-block:: QMP
+
+ -> {
+ "execute": "blockdev-add",
+ "arguments": {
+ "node-name": "target0",
+ "driver": "qcow2",
+ "file": {
+ "driver": "file",
+ "filename": "drive0.inc0.qcow2"
+ }
+ }
+ }
+
+ <- { "return": {} }
+
#. Retry the command after fixing the underlying problem, such as
freeing up space on the backup volume:
.. code-block:: QMP
-> {
- "execute": "drive-backup",
+ "execute": "blockdev-backup",
"arguments": {
"device": "drive0",
"bitmap": "bitmap0",
- "target": "drive0.inc0.qcow2",
- "format": "qcow2",
- "sync": "incremental",
- "mode": "existing"
+ "target": "target0",
+ "sync": "incremental"
}
}
@@ -1210,7 +1362,8 @@ described above. This example demonstrates the single-job failure
case:
Example: Partial Transactional Failures
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-QMP commands like `drive-backup <qemu-qmp-ref.html#index-drive_002dbackup>`_
+QMP commands like `blockdev-backup
+<qemu-qmp-ref.html#index-blockdev_002dbackup>`_
conceptually only start a job, and so transactions containing these commands
may succeed even if the job it created later fails. This might have surprising
interactions with notions of how a "transaction" ought to behave.
@@ -1240,25 +1393,21 @@ and one succeeds:
"arguments": {
"actions": [
{
- "type": "drive-backup",
+ "type": "blockdev-backup",
"data": {
"device": "drive0",
"bitmap": "bitmap0",
- "format": "qcow2",
- "mode": "existing",
"sync": "incremental",
- "target": "drive0.inc0.qcow2"
+ "target": "target0"
}
},
{
- "type": "drive-backup",
+ "type": "blockdev-backup",
"data": {
"device": "drive1",
"bitmap": "bitmap0",
- "format": "qcow2",
- "mode": "existing",
"sync": "incremental",
- "target": "drive1.inc0.qcow2"
+ "target": "target1"
}
}]
}
@@ -1375,25 +1524,21 @@ applied:
},
"actions": [
{
- "type": "drive-backup",
+ "type": "blockdev-backup",
"data": {
"device": "drive0",
"bitmap": "bitmap0",
- "format": "qcow2",
- "mode": "existing",
"sync": "incremental",
- "target": "drive0.inc0.qcow2"
+ "target": "target0"
}
},
{
- "type": "drive-backup",
+ "type": "blockdev-backup",
"data": {
"device": "drive1",
"bitmap": "bitmap0",
- "format": "qcow2",
- "mode": "existing",
"sync": "incremental",
- "target": "drive1.inc0.qcow2"
+ "target": "target1"
}
}]
}
--
2.31.1
3:58 a.m.
New subject: [PATCH v4 3/3] qapi: deprecate drive-backup
From: Vladimir Sementsov-Ogievskiy <vsementsov(a)virtuozzo.com>
Modern way is using blockdev-add + blockdev-backup, which provides a
lot more control on how target is opened.
As example of drive-backup problems consider the following:
User of drive-backup expects that target will be opened in the same
cache and aio mode as source. Corresponding logic is in
drive_backup_prepare(), where we take bs->open_flags of source.
It works rather bad if source was added by blockdev-add. Assume source
is qcow2 image. On blockdev-add we should specify aio and cache options
for file child of qcow2 node. What happens next:
drive_backup_prepare() looks at bs->open_flags of qcow2 source node.
But there no BDRV_O_NOCAHE neither BDRV_O_NATIVE_AIO: BDRV_O_NOCAHE is
places in bs->file->bs->open_flags, and BDRV_O_NATIVE_AIO is nowhere,
as file-posix parse options and simply set s->use_linux_aio.
The documentation is updated in a minimal way, so that drive-backup is
noted only as a deprecated command, and blockdev-backup used in most of
places.
Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov(a)virtuozzo.com>
Reviewed-by: Kashyap Chamarthy <kchamart(a)redhat.com>
Signed-off-by: Markus Armbruster <armbru(a)redhat.com>
---
docs/about/deprecated.rst | 11 ++++++
docs/interop/live-block-operations.rst | 47 +++++++++++++++++---------
qapi/block-core.json | 5 ++-
qapi/transaction.json | 6 +++-
4 files changed, 51 insertions(+), 18 deletions(-)
diff --git a/docs/about/deprecated.rst b/docs/about/deprecated.rst
index 56f9ad15ab..e3bdb89c65 100644
--- a/docs/about/deprecated.rst
+++ b/docs/about/deprecated.rst
@@ -239,6 +239,17 @@ single ``bitmap``, the new ``block-export-add`` uses a list of
``bitmaps``.
Member ``values`` in return value elements with meta-type ``enum`` is
deprecated. Use ``members`` instead.
+``drive-backup`` (since 6.2)
+''''''''''''''''''''''''''''
+
+Use ``blockdev-backup`` in combination with ``blockdev-add`` instead.
+This change primarily separates the creation/opening process of the backup
+target with explicit, separate steps. ``blockdev-backup`` uses mostly the
+same arguments as ``drive-backup``, except the ``format`` and ``mode``
+options are removed in favor of using explicit ``blockdev-create`` and
+``blockdev-add`` calls. See :doc:`/interop/live-block-operations` for
+details.
+
System accelerators
-------------------
diff --git a/docs/interop/live-block-operations.rst
b/docs/interop/live-block-operations.rst
index 9e3635b233..d403d96f58 100644
--- a/docs/interop/live-block-operations.rst
+++ b/docs/interop/live-block-operations.rst
@@ -116,8 +116,8 @@ QEMU block layer supports.
(3) ``drive-mirror`` (and ``blockdev-mirror``): Synchronize a running
disk to another image.
-(4) ``drive-backup`` (and ``blockdev-backup``): Point-in-time (live) copy
- of a block device to a destination.
+(4) ``blockdev-backup`` (and the deprecated ``drive-backup``):
+ Point-in-time (live) copy of a block device to a destination.
.. _`Interacting with a QEMU instance`:
@@ -555,13 +555,14 @@ Currently, there are four different kinds:
(3) ``none`` -- Synchronize only the new writes from this point on.
- .. note:: In the case of ``drive-backup`` (or ``blockdev-backup``),
- the behavior of ``none`` synchronization mode is different.
- Normally, a ``backup`` job consists of two parts: Anything
- that is overwritten by the guest is first copied out to
- the backup, and in the background the whole image is
- copied from start to end. With ``sync=none``, it's only
- the first part.
+ .. note:: In the case of ``blockdev-backup`` (or deprecated
+ ``drive-backup``), the behavior of ``none``
+ synchronization mode is different. Normally, a
+ ``backup`` job consists of two parts: Anything that is
+ overwritten by the guest is first copied out to the
+ backup, and in the background the whole image is copied
+ from start to end. With ``sync=none``, it's only the
+ first part.
(4) ``incremental`` -- Synchronize content that is described by the
dirty bitmap
@@ -928,19 +929,22 @@ Shutdown the guest, by issuing the ``quit`` QMP command::
}
-Live disk backup --- ``drive-backup`` and ``blockdev-backup``
--------------------------------------------------------------
+Live disk backup --- ``blockdev-backup`` and the deprecated``drive-backup``
+---------------------------------------------------------------------------
-The ``drive-backup`` (and its newer equivalent ``blockdev-backup``) allows
+The ``blockdev-backup`` (and the deprecated ``drive-backup``) allows
you to create a point-in-time snapshot.
-In this case, the point-in-time is when you *start* the ``drive-backup``
-(or its newer equivalent ``blockdev-backup``) command.
+In this case, the point-in-time is when you *start* the
+``blockdev-backup`` (or deprecated ``drive-backup``) command.
QMP invocation for ``drive-backup``
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+Note that ``drive-backup`` command is deprecated since QEMU 6.1 and
+will be removed in future.
+
Yet again, starting afresh with our example disk image chain::
[A] <-- [B] <-- [C] <-- [D]
@@ -965,11 +969,22 @@ will be issued, indicating the live block device job operation has
completed, and no further action is required.
+Moving from the deprecated ``drive-backup`` to newer ``blockdev-backup``
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+``blockdev-backup`` differs from ``drive-backup`` in how you specify
+the backup target. With ``blockdev-backup`` you can't specify filename
+as a target. Instead you use ``node-name`` of existing block node,
+which you may add by ``blockdev-add`` or ``blockdev-create`` commands.
+Correspondingly, ``blockdev-backup`` doesn't have ``mode`` and
+``format`` arguments which don't apply to an existing block node. See
+following sections for details and examples.
+
+
Notes on ``blockdev-backup``
~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-The ``blockdev-backup`` command is equivalent in functionality to
-``drive-backup``, except that it operates at node-level in a Block Driver
+The ``blockdev-backup`` command operates at node-level in a Block Driver
State (BDS) graph.
E.g. the sequence of actions to create a point-in-time backup
diff --git a/qapi/block-core.json b/qapi/block-core.json
index b290782bf2..f4968d6404 100644
--- a/qapi/block-core.json
+++ b/qapi/block-core.json
@@ -1709,6 +1709,9 @@
# The operation can be stopped before it has completed using the
# block-job-cancel command.
#
+# Features:
+# @deprecated: This command is deprecated. Use @blockdev-backup instead.
+#
# Returns: - nothing on success
# - If @device is not a valid block device, GenericError
#
@@ -1724,7 +1727,7 @@
#
##
{ 'command': 'drive-backup', 'boxed': true,
- 'data': 'DriveBackup' }
+ 'data': 'DriveBackup', 'features': ['deprecated'] }
##
# @blockdev-backup:
diff --git a/qapi/transaction.json b/qapi/transaction.json
index d175b5f863..381a2df782 100644
--- a/qapi/transaction.json
+++ b/qapi/transaction.json
@@ -54,6 +54,10 @@
# @blockdev-snapshot-sync: since 1.1
# @drive-backup: Since 1.6
#
+# Features:
+# @deprecated: Member @drive-backup is deprecated. Use member
+# @blockdev-backup instead.
+#
# Since: 1.1
##
{ 'enum': 'TransactionActionKind',
@@ -62,7 +66,7 @@
'block-dirty-bitmap-disable', 'block-dirty-bitmap-merge',
'blockdev-backup', 'blockdev-snapshot',
'blockdev-snapshot-internal-sync', 'blockdev-snapshot-sync',
- 'drive-backup' ] }
+ { 'name': 'drive-backup', 'features': [
'deprecated' ] } ] }
##
# @AbortWrapper:
--
2.31.1
2:56 p.m.
New subject: [PATCH v4 3/3] qapi: deprecate drive-backup
On Thu, Nov 04, 2021 at 09:58:11AM +0100, Markus Armbruster wrote:
From: Vladimir Sementsov-Ogievskiy <vsementsov(a)virtuozzo.com>
Modern way is using blockdev-add + blockdev-backup, which provides a
lot more control on how target is opened.
As example of drive-backup problems consider the following:
User of drive-backup expects that target will be opened in the same
cache and aio mode as source. Corresponding logic is in
drive_backup_prepare(), where we take bs->open_flags of source.
It works rather bad if source was added by blockdev-add. Assume source
is qcow2 image. On blockdev-add we should specify aio and cache options
for file child of qcow2 node. What happens next:
drive_backup_prepare() looks at bs->open_flags of qcow2 source node.
But there no BDRV_O_NOCAHE neither BDRV_O_NATIVE_AIO: BDRV_O_NOCAHE is
places in bs->file->bs->open_flags, and BDRV_O_NATIVE_AIO is nowhere,
as file-posix parse options and simply set s->use_linux_aio.
The documentation is updated in a minimal way, so that drive-backup is
noted only as a deprecated command, and blockdev-backup used in most of
places.
Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov(a)virtuozzo.com>
Reviewed-by: Kashyap Chamarthy <kchamart(a)redhat.com>
Signed-off-by: Markus Armbruster <armbru(a)redhat.com>
---
Reviewed-by: Eric Blake <eblake(a)redhat.com>
I think this is appropriate for inclusion in 6.2, even if it did not
quite make soft freeze, so that we aren't delaying the deprecation for
an entire cycle.
docs/about/deprecated.rst | 11 ++++++
docs/interop/live-block-operations.rst | 47 +++++++++++++++++---------
qapi/block-core.json | 5 ++-
qapi/transaction.json | 6 +++-
4 files changed, 51 insertions(+), 18 deletions(-)
--
Eric Blake, Principal Software Engineer
Red Hat, Inc. +1-919-301-3266
Virtualization: qemu.org | libvirt.org
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Markus Armbruster