Re: [PATCH] qapi: deprecate drive-backup
On Fri, Apr 23, 2021 at 03:59:00PM +0300, Vladimir Sementsov-Ogievskiy wrote:
> 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.
>
> Signed-off-by: Vladimir Sementsov-Ogievskiy
> ---
>
> Hi all! I remember, I suggested to deprecate drive-backup some time ago,
> and nobody complain.. But that old patch was inside the series with
> other more questionable deprecations and it did not landed.
>
> Let's finally deprecate what should be deprecated long ago.
>
> We now faced a problem in our downstream, described in commit message.
> In downstream I've fixed it by simply enabling O_DIRECT and linux_aio
> unconditionally for drive_backup target. But actually this just shows
> that using drive-backup in blockdev era is a bad idea. So let's motivate
> everyone (including Virtuozzo of course) to move to new interfaces and
> avoid problems with all that outdated option inheritance.
>
> docs/system/deprecated.rst | 5 +
> qapi/block-core.json | 5 -
> 2 files changed, 9 insertions(+), 1 deletion(-)
>
> diff --git a/docs/system/deprecated.rst b/docs/system/deprecated.rst
> index 80cae86252..b6f5766e17 100644
> --- a/docs/system/deprecated.rst
> +++ b/docs/system/deprecated.rst
> @@ -186,6 +186,11 @@ Use the more generic commands ``block-export-add`` and
> ``block-export-del``
> instead. As part of this deprecation, where ``nbd-server-add`` used a
> single ``bitmap``, the new ``block-export-add`` uses a list of ``bitmaps``.
>
> +``drive-backup`` (since 6.0)
NB, it'll need to be 6.1 by time this patch has a chance to merge
> +
> +
> +Use ``blockdev-backup`` in pair with ``blockdev-add`` instead.
> +
> System accelerators
> ---
>
> diff --git a/qapi/block-core.json b/qapi/block-core.json
> index 6d227924d0..8e2c6e1622 100644
> --- a/qapi/block-core.json
> +++ b/qapi/block-core.json
> @@ -1642,6 +1642,9 @@
> # 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
> #
> @@ -1657,7 +1660,7 @@
> #
> ##
> { 'command': 'drive-backup', 'boxed': true,
> - 'data': 'DriveBackup' }
> + 'data': 'DriveBackup', 'features': ['deprecated'] }
>
> ##
> # @blockdev-backup:
> --
> 2.29.2
>
>
Regards,
Daniel
--
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Re: [PATCH] qapi: deprecate drive-backup
23.04.2021 16:09, Daniel P. Berrangé wrote: On Fri, Apr 23, 2021 at 03:59:00PM +0300, Vladimir Sementsov-Ogievskiy wrote: 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. Signed-off-by: Vladimir Sementsov-Ogievskiy --- Hi all! I remember, I suggested to deprecate drive-backup some time ago, and nobody complain.. But that old patch was inside the series with other more questionable deprecations and it did not landed. Let's finally deprecate what should be deprecated long ago. We now faced a problem in our downstream, described in commit message. In downstream I've fixed it by simply enabling O_DIRECT and linux_aio unconditionally for drive_backup target. But actually this just shows that using drive-backup in blockdev era is a bad idea. So let's motivate everyone (including Virtuozzo of course) to move to new interfaces and avoid problems with all that outdated option inheritance. docs/system/deprecated.rst | 5 + qapi/block-core.json | 5 - 2 files changed, 9 insertions(+), 1 deletion(-) diff --git a/docs/system/deprecated.rst b/docs/system/deprecated.rst index 80cae86252..b6f5766e17 100644 --- a/docs/system/deprecated.rst +++ b/docs/system/deprecated.rst @@ -186,6 +186,11 @@ Use the more generic commands ``block-export-add`` and ``block-export-del`` instead. As part of this deprecation, where ``nbd-server-add`` used a single ``bitmap``, the new ``block-export-add`` uses a list of ``bitmaps``. +``drive-backup`` (since 6.0) NB, it'll need to be 6.1 by time this patch has a chance to merge Oops yes. -- Best regards, Vladimir
Re: [PATCH] qapi: deprecate drive-backup
On Fri, Apr 23, 2021 at 15:59:00 +0300, Vladimir Sementsov-Ogievskiy wrote: > 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. > > Signed-off-by: Vladimir Sementsov-Ogievskiy > --- > > Hi all! I remember, I suggested to deprecate drive-backup some time ago, > and nobody complain.. But that old patch was inside the series with > other more questionable deprecations and it did not landed. > > Let's finally deprecate what should be deprecated long ago. > > We now faced a problem in our downstream, described in commit message. > In downstream I've fixed it by simply enabling O_DIRECT and linux_aio > unconditionally for drive_backup target. But actually this just shows > that using drive-backup in blockdev era is a bad idea. So let's motivate > everyone (including Virtuozzo of course) to move to new interfaces and > avoid problems with all that outdated option inheritance. libvirt never used 'drive-backup' thus Reviewed-by: Peter Krempa
Re: [PATCH] qapi: deprecate drive-backup
On 4/23/21 8:59 AM, Vladimir Sementsov-Ogievskiy wrote:
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.
No complaints from me, especially if Virtuozzo is on board. I would like
to see some documentation changes alongside this deprecation, though.
Signed-off-by: Vladimir Sementsov-Ogievskiy
---
Hi all! I remember, I suggested to deprecate drive-backup some time ago,
and nobody complain.. But that old patch was inside the series with
other more questionable deprecations and it did not landed.
Let's finally deprecate what should be deprecated long ago.
We now faced a problem in our downstream, described in commit message.
In downstream I've fixed it by simply enabling O_DIRECT and linux_aio
unconditionally for drive_backup target. But actually this just shows
that using drive-backup in blockdev era is a bad idea. So let's motivate
everyone (including Virtuozzo of course) to move to new interfaces and
avoid problems with all that outdated option inheritance.
docs/system/deprecated.rst | 5 +
qapi/block-core.json | 5 -
2 files changed, 9 insertions(+), 1 deletion(-)
diff --git a/docs/system/deprecated.rst b/docs/system/deprecated.rst
index 80cae86252..b6f5766e17 100644
--- a/docs/system/deprecated.rst
+++ b/docs/system/deprecated.rst
@@ -186,6 +186,11 @@ Use the more generic commands ``block-export-add`` and
``block-export-del``
instead. As part of this deprecation, where ``nbd-server-add`` used a
single ``bitmap``, the new ``block-export-add`` uses a list of ``bitmaps``.
+``drive-backup`` (since 6.0)
+
+
+Use ``blockdev-backup`` in pair with ``blockdev-add`` instead.
+
1) Let's add a sphinx reference to
https://qemu-project.gitlab.io/qemu/interop/live-block-operations.html#live-disk-backup-drive-backup-and-blockdev-backup
2) Just a thought, not a request: We also may wish to update
https://qemu-project.gitlab.io/qemu/interop/bitmaps.html to use the new,
preferred method. However, this doc is a bit old and is in need of an
overhaul anyway (Especially to add the NBD pull workflow.) Since the doc
is in need of an overhaul anyway, can we ask Kashyap to help us here, if
he has time?
3) Let's add a small explanation here that outlines the differences in
using these two commands. Here's a suggestion:
This change primarily separates the creation/opening process of the
backup target with explicit, separate steps. BlockdevBackup uses mostly
the same arguments as DriveBackup, except the "format" and "mode"
options are removed in favor of using explicit "blockdev-create" and
"blockdev-add" calls.
The "target" argument changes semantics. It no longer accepts filenames,
and will now additionally accept arbitrary node names in addition to
device names.
4) Also not a request: If we want to go above and beyond, it might be
nice to spell out the exact steps required to transition from the old
interface to the new one. Here's a (hasty) suggestion for how that might
look:
- The MODE argument is deprecated.
- "existing" is replaced by using "blockdev-add" commands.
- "absolute-paths" is replaced by using "blockdev-add" and
"blockdev-create" commands.
- The FORMAT argument is deprecated.
- Format information is given to "blockdev-add"/"blockdev-create".
- The TARGET argument has new semantics:
- Filenames are no longer supported, use blockdev-add/blockdev-create
as necessary instead.
- Device targets remain supported.
Example:
drive-backup $ARGS format=$FORMAT mode=$MODE target=$FILENAME becomes:
(taking some liberties with syntax to just illustrate the idea ...)
blockdev-create options={
"driver": "file",
"filename": $FILENAME,
"size": 0,
}
blockdev-add arguments={
"driver": "file",
"filename": $FILENAME,
"node-name": "Example_Filenode0"
}
blockdev-create options={
"driver": $FORMAT,
"file": "Example_Filenode0",
"size": $SIZE,
}
blockdev-add arguments={
"driver": $FORMAT,
"file": "Example_Filenode0",
"node-name": "Example_Formatnode0",
}
blockdev-backup arguments={
$ARGS ...,
"target": "Example_Formatnode0",
}
System accelerators
---
diff --git a/qapi/bloc
Re: [PATCH] qapi: deprecate drive-backup
26.04.2021 20:34, John Snow wrote:
On 4/23/21 8:59 AM, Vladimir Sementsov-Ogievskiy wrote:
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.
No complaints from me, especially if Virtuozzo is on board. I would like to see
some documentation changes alongside this deprecation, though.
Signed-off-by: Vladimir Sementsov-Ogievskiy
---
Hi all! I remember, I suggested to deprecate drive-backup some time ago,
and nobody complain.. But that old patch was inside the series with
other more questionable deprecations and it did not landed.
Let's finally deprecate what should be deprecated long ago.
We now faced a problem in our downstream, described in commit message.
In downstream I've fixed it by simply enabling O_DIRECT and linux_aio
unconditionally for drive_backup target. But actually this just shows
that using drive-backup in blockdev era is a bad idea. So let's motivate
everyone (including Virtuozzo of course) to move to new interfaces and
avoid problems with all that outdated option inheritance.
docs/system/deprecated.rst | 5 +
qapi/block-core.json | 5 -
2 files changed, 9 insertions(+), 1 deletion(-)
diff --git a/docs/system/deprecated.rst b/docs/system/deprecated.rst
index 80cae86252..b6f5766e17 100644
--- a/docs/system/deprecated.rst
+++ b/docs/system/deprecated.rst
@@ -186,6 +186,11 @@ Use the more generic commands ``block-export-add`` and
``block-export-del``
instead. As part of this deprecation, where ``nbd-server-add`` used a
single ``bitmap``, the new ``block-export-add`` uses a list of ``bitmaps``.
+``drive-backup`` (since 6.0)
+
+
+Use ``blockdev-backup`` in pair with ``blockdev-add`` instead.
+
1) Let's add a sphinx reference to
https://qemu-project.gitlab.io/qemu/interop/live-block-operations.html#live-disk-backup-drive-backup-and-blockdev-backup
2) Just a thought, not a request: We also may wish to update
https://qemu-project.gitlab.io/qemu/interop/bitmaps.html to use the new,
preferred method. However, this doc is a bit old and is in need of an overhaul
anyway (Especially to add the NBD pull workflow.) Since the doc is in need of
an overhaul anyway, can we ask Kashyap to help us here, if he has time?
3) Let's add a small explanation here that outlines the differences in using
these two commands. Here's a suggestion:
This change primarily separates the creation/opening process of the backup target with explicit, separate steps.
BlockdevBackup uses mostly the same arguments as DriveBackup, except the "format" and "mode"
options are removed in favor of using explicit "blockdev-create" and "blockdev-add" calls.
The "target" argument changes semantics. It no longer accepts filenames, and
will now additionally accept arbitrary node names in addition to device names.
4) Also not a request: If we want to go above and beyond, it might be nice to
spell out the exact steps required to transition from the old interface to the
new one. Here's a (hasty) suggestion for how that might look:
- The MODE argument is deprecated.
- "existing" is replaced by using "blockdev-add" commands.
- "absolute-paths" is replaced by using "blockdev-add" and
"blockdev-create" commands.
- The FORMAT argument is deprecated.
- Format information is given to "blockdev-add"/"blockdev-create".
- The TARGET argument has new semantics:
- Filenames are no longer supported, use blockdev-add/blockdev-create
as necessary instead.
- Device targets remain supported.
Example:
drive-backup $ARGS format=$FORMAT mode=$MODE target=$FILENAME becomes:
(taking some liberties with syntax to just illustrate the idea ...)
blockdev-create options={
"driver": "file",
"filename": $FILENAME,
"size": 0,
}
blockdev-add arguments={
"driver": "file",
"filename": $FILENAME,
"node-name": "Example_Filenode0"
}
blockdev-create options={
"driver": $FORMAT,
"file": "Example_Filenode0",
"size": $SIZE,
}
blockdev-add arguments={
"driver": $FORMAT,
"file": "Example_Filenode0",
"node-name": "Example_Formatnode0",
}
blockdev-backup arguments={
$ARGS ...,
"target": "Example_Formatnode0",
}
Good ideas. Hmm. Do you think that the whole expl
Re: [PATCH] qapi: deprecate drive-backup
On Mon, Apr 26, 2021 at 09:00:36PM +0300, Vladimir Sementsov-Ogievskiy wrote: > 26.04.2021 20:34, John Snow wrote: > > On 4/23/21 8:59 AM, Vladimir Sementsov-Ogievskiy wrote: > > > 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. > > > > > > > No complaints from me, especially if Virtuozzo is on board. I would like to > > see some documentation changes alongside this deprecation, though. > > > > > Signed-off-by: Vladimir Sementsov-Ogievskiy > > > --- > > > > > > Hi all! I remember, I suggested to deprecate drive-backup some time ago, > > > and nobody complain.. But that old patch was inside the series with > > > other more questionable deprecations and it did not landed. > > > > > > Let's finally deprecate what should be deprecated long ago. > > > > > > We now faced a problem in our downstream, described in commit message. > > > In downstream I've fixed it by simply enabling O_DIRECT and linux_aio > > > unconditionally for drive_backup target. But actually this just shows > > > that using drive-backup in blockdev era is a bad idea. So let's motivate > > > everyone (including Virtuozzo of course) to move to new interfaces and > > > avoid problems with all that outdated option inheritance. > > > > > > docs/system/deprecated.rst | 5 + > > > qapi/block-core.json | 5 - > > > 2 files changed, 9 insertions(+), 1 deletion(-) > > > > > > diff --git a/docs/system/deprecated.rst b/docs/system/deprecated.rst > > > index 80cae86252..b6f5766e17 100644 > > > --- a/docs/system/deprecated.rst > > > +++ b/docs/system/deprecated.rst > > > @@ -186,6 +186,11 @@ Use the more generic commands ``block-export-add`` > > > and ``block-export-del`` > > > instead. As part of this deprecation, where ``nbd-server-add`` used a > > > single ``bitmap``, the new ``block-export-add`` uses a list of > > > ``bitmaps``. > > > +``drive-backup`` (since 6.0) > > > + > > > + > > > +Use ``blockdev-backup`` in pair with ``blockdev-add`` instead. > > > + > > > > 1) Let's add a sphinx reference to > > https://qemu-project.gitlab.io/qemu/interop/live-block-operations.html#live-disk-backup-drive-backup-and-blockdev-backup > > > > > > 2) Just a thought, not a request: We also may wish to update > > https://qemu-project.gitlab.io/qemu/interop/bitmaps.html to use the new, > > preferred method. However, this doc is a bit old and is in need of an > > overhaul anyway (Especially to add the NBD pull workflow.) Since the doc is > > in need of an overhaul anyway, can we ask Kashyap to help us here, if he > > has time? > > > > > > 3) Let's add a small explanation here that outlines the differences in > > using these two commands. Here's a suggestion: > > > > This change primarily separates the creation/opening process of the backup > > target with explicit, separate steps. BlockdevBackup uses mostly the same > > arguments as DriveBackup, except the "format" and "mode" options are > > removed in favor of using explicit "blockdev-create" and "blockdev-add" > > calls. > > > > The "target" argument changes semantics. It no longer accepts filenames, > > and will now additionally accept arbitrary node names in addition to device > > names. > > > > > > 4) Also not a request: If we want to go above and beyond, it might be nice > > to spell out the exact steps required to transition from the old interface > > to the new one. Here's a (hasty) suggestion for how that might look: > > > > - The MODE argument is deprecated. > > - "existing" is replaced by using "blockdev-add" commands. > > - "absolute-paths" is replaced by using "blockdev-add" and > > "blockdev-create" commands. > > > > - The FORMAT argument is deprecated. > > - Format information is given to "blockdev-add"/"blockdev-create". > > > > - The TARGET argument has new semantics: > > - Filenames are no longer supported, use blockdev-add/blockdev-create > > as necessary instead. > > - Device targets remain supported. > > > > > > Example: > > > > drive-backup $ARGS format=$FORMAT mode=$MODE target=$FILENAME becomes: > > > > (taking some liberties with
Re: [PATCH] qapi: deprecate drive-backup
On 4/26/21 2:05 PM, Daniel P. Berrangé wrote:
On Mon, Apr 26, 2021 at 09:00:36PM +0300, Vladimir Sementsov-Ogievskiy wrote:
26.04.2021 20:34, John Snow wrote:
On 4/23/21 8:59 AM, Vladimir Sementsov-Ogievskiy wrote:
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.
No complaints from me, especially if Virtuozzo is on board. I would like to see
some documentation changes alongside this deprecation, though.
Signed-off-by: Vladimir Sementsov-Ogievskiy
---
Hi all! I remember, I suggested to deprecate drive-backup some time ago,
and nobody complain.. But that old patch was inside the series with
other more questionable deprecations and it did not landed.
Let's finally deprecate what should be deprecated long ago.
We now faced a problem in our downstream, described in commit message.
In downstream I've fixed it by simply enabling O_DIRECT and linux_aio
unconditionally for drive_backup target. But actually this just shows
that using drive-backup in blockdev era is a bad idea. So let's motivate
everyone (including Virtuozzo of course) to move to new interfaces and
avoid problems with all that outdated option inheritance.
docs/system/deprecated.rst | 5 +
qapi/block-core.json | 5 -
2 files changed, 9 insertions(+), 1 deletion(-)
diff --git a/docs/system/deprecated.rst b/docs/system/deprecated.rst
index 80cae86252..b6f5766e17 100644
--- a/docs/system/deprecated.rst
+++ b/docs/system/deprecated.rst
@@ -186,6 +186,11 @@ Use the more generic commands ``block-export-add`` and
``block-export-del``
instead. As part of this deprecation, where ``nbd-server-add`` used a
single ``bitmap``, the new ``block-export-add`` uses a list of ``bitmaps``.
+``drive-backup`` (since 6.0)
+
+
+Use ``blockdev-backup`` in pair with ``blockdev-add`` instead.
+
1) Let's add a sphinx reference to
https://qemu-project.gitlab.io/qemu/interop/live-block-operations.html#live-disk-backup-drive-backup-and-blockdev-backup
2) Just a thought, not a request: We also may wish to update
https://qemu-project.gitlab.io/qemu/interop/bitmaps.html to use the new,
preferred method. However, this doc is a bit old and is in need of an overhaul
anyway (Especially to add the NBD pull workflow.) Since the doc is in need of
an overhaul anyway, can we ask Kashyap to help us here, if he has time?
3) Let's add a small explanation here that outlines the differences in using
these two commands. Here's a suggestion:
This change primarily separates the creation/opening process of the backup target with explicit, separate steps.
BlockdevBackup uses mostly the same arguments as DriveBackup, except the "format" and "mode"
options are removed in favor of using explicit "blockdev-create" and "blockdev-add" calls.
The "target" argument changes semantics. It no longer accepts filenames, and
will now additionally accept arbitrary node names in addition to device names.
4) Also not a request: If we want to go above and beyond, it might be nice to
spell out the exact steps required to transition from the old interface to the
new one. Here's a (hasty) suggestion for how that might look:
- The MODE argument is deprecated.
- "existing" is replaced by using "blockdev-add" commands.
- "absolute-paths" is replaced by using "blockdev-add" and
"blockdev-create" commands.
- The FORMAT argument is deprecated.
- Format information is given to "blockdev-add"/"blockdev-create".
- The TARGET argument has new semantics:
- Filenames are no longer supported, use blockdev-add/blockdev-create
as necessary instead.
- Device targets remain supported.
Example:
drive-backup $ARGS format=$FORMAT mode=$MODE target=$FILENAME becomes:
(taking some liberties with syntax to just illustrate the idea ...)
blockdev-create options={
"driver": "file",
"filename": $FILENAME,
"size": 0,
}
blockdev-add arguments={
"driver": "file",
"filename": $FILENAME,
"node-name": "Example_Filenode0"
}
blockdev-create options={
"driver": $FORMAT,
"file": "Example_Filenode0",
"size": $SIZE,
}
blockdev-add arguments={
"driver": $FORMAT,
"file": "Example_Filenode0",
"node-name": "Example_F
Re: [PATCH] qapi: deprecate drive-backup
On 4/26/21 2:41 PM, Vladimir Sementsov-Ogievskiy wrote:
26.04.2021 21:30, John Snow wrote:
On 4/26/21 2:05 PM, Daniel P. Berrangé wrote:
On Mon, Apr 26, 2021 at 09:00:36PM +0300, Vladimir
Sementsov-Ogievskiy wrote:
26.04.2021 20:34, John Snow wrote:
On 4/23/21 8:59 AM, Vladimir Sementsov-Ogievskiy wrote:
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.
No complaints from me, especially if Virtuozzo is on board. I would
like to see some documentation changes alongside this deprecation,
though.
Signed-off-by: Vladimir Sementsov-Ogievskiy
---
Hi all! I remember, I suggested to deprecate drive-backup some
time ago,
and nobody complain.. But that old patch was inside the series with
other more questionable deprecations and it did not landed.
Let's finally deprecate what should be deprecated long ago.
We now faced a problem in our downstream, described in commit
message.
In downstream I've fixed it by simply enabling O_DIRECT and linux_aio
unconditionally for drive_backup target. But actually this just shows
that using drive-backup in blockdev era is a bad idea. So let's
motivate
everyone (including Virtuozzo of course) to move to new interfaces
and
avoid problems with all that outdated option inheritance.
docs/system/deprecated.rst | 5 +
qapi/block-core.json | 5 -
2 files changed, 9 insertions(+), 1 deletion(-)
diff --git a/docs/system/deprecated.rst b/docs/system/deprecated.rst
index 80cae86252..b6f5766e17 100644
--- a/docs/system/deprecated.rst
+++ b/docs/system/deprecated.rst
@@ -186,6 +186,11 @@ Use the more generic commands
``block-export-add`` and ``block-export-del``
instead. As part of this deprecation, where ``nbd-server-add``
used a
single ``bitmap``, the new ``block-export-add`` uses a list of
``bitmaps``.
+``drive-backup`` (since 6.0)
+
+
+Use ``blockdev-backup`` in pair with ``blockdev-add`` instead.
+
1) Let's add a sphinx reference to
https://qemu-project.gitlab.io/qemu/interop/live-block-operations.html#live-disk-backup-drive-backup-and-blockdev-backup
2) Just a thought, not a request: We also may wish to update
https://qemu-project.gitlab.io/qemu/interop/bitmaps.html to use the
new, preferred method. However, this doc is a bit old and is in
need of an overhaul anyway (Especially to add the NBD pull
workflow.) Since the doc is in need of an overhaul anyway, can we
ask Kashyap to help us here, if he has time?
3) Let's add a small explanation here that outlines the differences
in using these two commands. Here's a suggestion:
This change primarily separates the creation/opening process of the
backup target with explicit, separate steps. BlockdevBackup uses
mostly the same arguments as DriveBackup, except the "format" and
"mode" options are removed in favor of using explicit
"blockdev-create" and "blockdev-add" calls.
(Here, I accidentally used the names of the argument objects instead of
the names of the commands. It's likely better to spell out the names of
the commands instead.)
The "target" argument changes semantics. It no longer accepts
filenames, and will now additionally accept arbitrary node names in
addition to device names.
4) Also not a request: If we want to go above and beyond, it might
be nice to spell out the exact steps required to transition from
the old interface to the new one. Here's a (hasty) suggestion for
how that might look:
- The MODE argument is deprecated.
- "existing" is replaced by using "blockdev-add" commands.
- "absolute-paths" is replaced by using "blockdev-add" and
"blockdev-create" commands.
- The FORMAT argument is deprecated.
- Format information is given to "blockdev-add"/"blockdev-create".
- The TARGET argument has new semantics:
- Filenames are no longer supported, use
blockdev-add/blockdev-create
as necessary instead.
- Device targets remain supported.
Example:
drive-backup $ARGS format=$FORMAT mode=$MODE target=$FILENAME becomes:
(taking some liberties with syntax to just illustrate the idea ...)
blockdev-create options={
"driver": "file",
"filename": $FILENAME,
"size": 0,
}
blockdev-add arguments={
"drive
Re: [PATCH] qapi: deprecate drive-backup
26.04.2021 21:30, John Snow wrote:
On 4/26/21 2:05 PM, Daniel P. Berrangé wrote:
On Mon, Apr 26, 2021 at 09:00:36PM +0300, Vladimir Sementsov-Ogievskiy wrote:
26.04.2021 20:34, John Snow wrote:
On 4/23/21 8:59 AM, Vladimir Sementsov-Ogievskiy wrote:
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.
No complaints from me, especially if Virtuozzo is on board. I would like to see
some documentation changes alongside this deprecation, though.
Signed-off-by: Vladimir Sementsov-Ogievskiy
---
Hi all! I remember, I suggested to deprecate drive-backup some time ago,
and nobody complain.. But that old patch was inside the series with
other more questionable deprecations and it did not landed.
Let's finally deprecate what should be deprecated long ago.
We now faced a problem in our downstream, described in commit message.
In downstream I've fixed it by simply enabling O_DIRECT and linux_aio
unconditionally for drive_backup target. But actually this just shows
that using drive-backup in blockdev era is a bad idea. So let's motivate
everyone (including Virtuozzo of course) to move to new interfaces and
avoid problems with all that outdated option inheritance.
docs/system/deprecated.rst | 5 +
qapi/block-core.json | 5 -
2 files changed, 9 insertions(+), 1 deletion(-)
diff --git a/docs/system/deprecated.rst b/docs/system/deprecated.rst
index 80cae86252..b6f5766e17 100644
--- a/docs/system/deprecated.rst
+++ b/docs/system/deprecated.rst
@@ -186,6 +186,11 @@ Use the more generic commands ``block-export-add`` and
``block-export-del``
instead. As part of this deprecation, where ``nbd-server-add`` used a
single ``bitmap``, the new ``block-export-add`` uses a list of ``bitmaps``.
+``drive-backup`` (since 6.0)
+
+
+Use ``blockdev-backup`` in pair with ``blockdev-add`` instead.
+
1) Let's add a sphinx reference to
https://qemu-project.gitlab.io/qemu/interop/live-block-operations.html#live-disk-backup-drive-backup-and-blockdev-backup
2) Just a thought, not a request: We also may wish to update
https://qemu-project.gitlab.io/qemu/interop/bitmaps.html to use the new,
preferred method. However, this doc is a bit old and is in need of an overhaul
anyway (Especially to add the NBD pull workflow.) Since the doc is in need of
an overhaul anyway, can we ask Kashyap to help us here, if he has time?
3) Let's add a small explanation here that outlines the differences in using
these two commands. Here's a suggestion:
This change primarily separates the creation/opening process of the backup target with explicit, separate steps.
BlockdevBackup uses mostly the same arguments as DriveBackup, except the "format" and "mode"
options are removed in favor of using explicit "blockdev-create" and "blockdev-add" calls.
The "target" argument changes semantics. It no longer accepts filenames, and
will now additionally accept arbitrary node names in addition to device names.
4) Also not a request: If we want to go above and beyond, it might be nice to
spell out the exact steps required to transition from the old interface to the
new one. Here's a (hasty) suggestion for how that might look:
- The MODE argument is deprecated.
- "existing" is replaced by using "blockdev-add" commands.
- "absolute-paths" is replaced by using "blockdev-add" and
"blockdev-create" commands.
- The FORMAT argument is deprecated.
- Format information is given to "blockdev-add"/"blockdev-create".
- The TARGET argument has new semantics:
- Filenames are no longer supported, use blockdev-add/blockdev-create
as necessary instead.
- Device targets remain supported.
Example:
drive-backup $ARGS format=$FORMAT mode=$MODE target=$FILENAME becomes:
(taking some liberties with syntax to just illustrate the idea ...)
blockdev-create options={
"driver": "file",
"filename": $FILENAME,
"size": 0,
}
blockdev-add arguments={
"driver": "file",
"filename": $FILENAME,
"node-name": "Example_Filenode0"
}
blockdev-create options={
"driver": $FORMAT,
"file": "Example_Filenode0",
"size": $SIZE,
}
blockdev-add arguments={
"driver": $FORMAT,
"file": "Example_File
Re: [PATCH] qapi: deprecate drive-backup
On Mon, Apr 26, 2021 at 01:34:17PM -0400, John Snow wrote: > On 4/23/21 8:59 AM, Vladimir Sementsov-Ogievskiy wrote: > > Modern way is using blockdev-add + blockdev-backup, which provides a > > lot more control on how target is opened. [...] > 1) Let's add a sphinx reference to > https://qemu-project.gitlab.io/qemu/interop/live-block-operations.html#live-disk-backup-drive-backup-and-blockdev-backup > > > 2) Just a thought, not a request: We also may wish to update > https://qemu-project.gitlab.io/qemu/interop/bitmaps.html to use the > new, preferred method. However, this doc is a bit old and is in need > of an overhaul anyway (Especially to add the NBD pull workflow.) Since > the doc is in need of an overhaul anyway, can we ask Kashyap to help > us here, if he has time? Yes, I should be able to make time and help here; been putting it off on the back burner. Thanks for the reminder. :) I'd like to update both these: https://qemu-project.gitlab.io/qemu/interop/bitmaps.html https://qemu-project.gitlab.io/qemu/interop/live-block-operations.html Both of them, as you know, refer to 'drive-backup'. They also need other adjustments / additions. Also perhaps break the larger doc into a couple of smaller ones. I'll start working on it the end of this week. First I need to tinker with some of the recent improvements to refresh my memory and get a sense of the modifications involved. So please bear with me. > 3) Let's add a small explanation here that outlines the differences in > using these two commands. Here's a suggestion: > > This change primarily separates the creation/opening process of the > backup target with explicit, separate steps. BlockdevBackup uses > mostly the same arguments as DriveBackup, except the "format" and > "mode" options are removed in favor of using explicit > "blockdev-create" and "blockdev-add" calls. > > The "target" argument changes semantics. It no longer accepts > filenames, and will now additionally accept arbitrary node names in > addition to device names. Yeah; this is something I had figure out by some trial-and-error when I was playing with it in the past. > 4) Also not a request: If we want to go above and beyond, it might be nice > to spell out the exact steps required to transition from the old interface > to the new one. Here's a (hasty) suggestion for how that might look: > > - The MODE argument is deprecated. > - "existing" is replaced by using "blockdev-add" commands. > - "absolute-paths" is replaced by using "blockdev-add" and > "blockdev-create" commands. > > - The FORMAT argument is deprecated. > - Format information is given to "blockdev-add"/"blockdev-create". > > - The TARGET argument has new semantics: > - Filenames are no longer supported, use blockdev-add/blockdev-create > as necessary instead. > - Device targets remain supported. Agreed; docs like these can be useful for management tools that rely on the old behaviour and are not as up-to-date as libvirt in keeping track of QEMU developments. [...] -- /kashyap
