* [Qemu-devel] [PATCH] block: early check for blockers on drive-mirror
@ 2018-02-07 16:29 Paolo Bonzini
2018-02-08 1:17 ` Fam Zheng
` (4 more replies)
0 siblings, 5 replies; 11+ messages in thread
From: Paolo Bonzini @ 2018-02-07 16:29 UTC (permalink / raw)
To: qemu-devel; +Cc: qemu-block, jsnow
Even if an op blocker is present for BLOCK_OP_TYPE_MIRROR_SOURCE,
it is checked a bit late and the result is that the target is
created even if drive-mirror subsequently fails. Add an early
check to avoid this.
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
---
blockdev.c | 5 +++++
1 file changed, 5 insertions(+)
diff --git a/blockdev.c b/blockdev.c
index 8e977eef11..c7e2e0a00e 100644
--- a/blockdev.c
+++ b/blockdev.c
@@ -3565,6 +3565,11 @@ void qmp_drive_mirror(DriveMirror *arg, Error **errp)
return;
}
+ /* Early check to avoid creating target */
+ if (bdrv_op_is_blocked(bs, BLOCK_OP_TYPE_MIRROR_SOURCE, errp)) {
+ return;
+ }
+
aio_context = bdrv_get_aio_context(bs);
aio_context_acquire(aio_context);
--
2.14.3
^ permalink raw reply related [flat|nested] 11+ messages in thread
* Re: [Qemu-devel] [PATCH] block: early check for blockers on drive-mirror
2018-02-07 16:29 [Qemu-devel] [PATCH] block: early check for blockers on drive-mirror Paolo Bonzini
@ 2018-02-08 1:17 ` Fam Zheng
2018-02-08 10:10 ` [Qemu-devel] [Qemu-block] " Alberto Garcia
` (3 subsequent siblings)
4 siblings, 0 replies; 11+ messages in thread
From: Fam Zheng @ 2018-02-08 1:17 UTC (permalink / raw)
To: Paolo Bonzini; +Cc: qemu-devel, jsnow, qemu-block
On Wed, 02/07 17:29, Paolo Bonzini wrote:
> Even if an op blocker is present for BLOCK_OP_TYPE_MIRROR_SOURCE,
> it is checked a bit late and the result is that the target is
> created even if drive-mirror subsequently fails. Add an early
> check to avoid this.
>
> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
> ---
> blockdev.c | 5 +++++
> 1 file changed, 5 insertions(+)
>
> diff --git a/blockdev.c b/blockdev.c
> index 8e977eef11..c7e2e0a00e 100644
> --- a/blockdev.c
> +++ b/blockdev.c
> @@ -3565,6 +3565,11 @@ void qmp_drive_mirror(DriveMirror *arg, Error **errp)
> return;
> }
>
> + /* Early check to avoid creating target */
> + if (bdrv_op_is_blocked(bs, BLOCK_OP_TYPE_MIRROR_SOURCE, errp)) {
> + return;
> + }
> +
> aio_context = bdrv_get_aio_context(bs);
> aio_context_acquire(aio_context);
>
> --
> 2.14.3
>
>
Reviewed-by: Fam Zheng <famz@redhat.com>
^ permalink raw reply [flat|nested] 11+ messages in thread
* Re: [Qemu-devel] [Qemu-block] [PATCH] block: early check for blockers on drive-mirror
2018-02-07 16:29 [Qemu-devel] [PATCH] block: early check for blockers on drive-mirror Paolo Bonzini
2018-02-08 1:17 ` Fam Zheng
@ 2018-02-08 10:10 ` Alberto Garcia
2018-02-08 10:38 ` Paolo Bonzini
2018-02-08 12:41 ` Alberto Garcia
` (2 subsequent siblings)
4 siblings, 1 reply; 11+ messages in thread
From: Alberto Garcia @ 2018-02-08 10:10 UTC (permalink / raw)
To: Paolo Bonzini, qemu-devel; +Cc: qemu-block
On Wed 07 Feb 2018 05:29:20 PM CET, Paolo Bonzini wrote:
> Even if an op blocker is present for BLOCK_OP_TYPE_MIRROR_SOURCE,
> it is checked a bit late and the result is that the target is
> created even if drive-mirror subsequently fails. Add an early
> check to avoid this.
>
> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
> ---
> blockdev.c | 5 +++++
> 1 file changed, 5 insertions(+)
>
> diff --git a/blockdev.c b/blockdev.c
> index 8e977eef11..c7e2e0a00e 100644
> --- a/blockdev.c
> +++ b/blockdev.c
> @@ -3565,6 +3565,11 @@ void qmp_drive_mirror(DriveMirror *arg, Error **errp)
> return;
> }
>
> + /* Early check to avoid creating target */
> + if (bdrv_op_is_blocked(bs, BLOCK_OP_TYPE_MIRROR_SOURCE, errp)) {
> + return;
> + }
> +
> aio_context = bdrv_get_aio_context(bs);
> aio_context_acquire(aio_context);
Do we need to hold the AioContext in order to check for op blockers?
Berto
^ permalink raw reply [flat|nested] 11+ messages in thread
* Re: [Qemu-devel] [Qemu-block] [PATCH] block: early check for blockers on drive-mirror
2018-02-08 10:10 ` [Qemu-devel] [Qemu-block] " Alberto Garcia
@ 2018-02-08 10:38 ` Paolo Bonzini
0 siblings, 0 replies; 11+ messages in thread
From: Paolo Bonzini @ 2018-02-08 10:38 UTC (permalink / raw)
To: Alberto Garcia, qemu-devel; +Cc: qemu-block
On 08/02/2018 11:10, Alberto Garcia wrote:
> On Wed 07 Feb 2018 05:29:20 PM CET, Paolo Bonzini wrote:
>> Even if an op blocker is present for BLOCK_OP_TYPE_MIRROR_SOURCE,
>> it is checked a bit late and the result is that the target is
>> created even if drive-mirror subsequently fails. Add an early
>> check to avoid this.
>>
>> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
>> ---
>> blockdev.c | 5 +++++
>> 1 file changed, 5 insertions(+)
>>
>> diff --git a/blockdev.c b/blockdev.c
>> index 8e977eef11..c7e2e0a00e 100644
>> --- a/blockdev.c
>> +++ b/blockdev.c
>> @@ -3565,6 +3565,11 @@ void qmp_drive_mirror(DriveMirror *arg, Error **errp)
>> return;
>> }
>>
>> + /* Early check to avoid creating target */
>> + if (bdrv_op_is_blocked(bs, BLOCK_OP_TYPE_MIRROR_SOURCE, errp)) {
>> + return;
>> + }
>> +
>> aio_context = bdrv_get_aio_context(bs);
>> aio_context_acquire(aio_context);
>
> Do we need to hold the AioContext in order to check for op blockers?
In include/block/block_int.h, they are not in the "Protected by
AioContext lock" section.
Paolo
^ permalink raw reply [flat|nested] 11+ messages in thread
* Re: [Qemu-devel] [Qemu-block] [PATCH] block: early check for blockers on drive-mirror
2018-02-07 16:29 [Qemu-devel] [PATCH] block: early check for blockers on drive-mirror Paolo Bonzini
2018-02-08 1:17 ` Fam Zheng
2018-02-08 10:10 ` [Qemu-devel] [Qemu-block] " Alberto Garcia
@ 2018-02-08 12:41 ` Alberto Garcia
2018-02-09 15:36 ` Kevin Wolf
2018-02-09 23:07 ` [Qemu-devel] " John Snow
4 siblings, 0 replies; 11+ messages in thread
From: Alberto Garcia @ 2018-02-08 12:41 UTC (permalink / raw)
To: Paolo Bonzini, qemu-devel; +Cc: qemu-block
On Wed 07 Feb 2018 05:29:20 PM CET, Paolo Bonzini wrote:
> Even if an op blocker is present for BLOCK_OP_TYPE_MIRROR_SOURCE,
> it is checked a bit late and the result is that the target is
> created even if drive-mirror subsequently fails. Add an early
> check to avoid this.
>
> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Reviewed-by: Alberto Garcia <berto@igalia.com>
Berto
^ permalink raw reply [flat|nested] 11+ messages in thread
* Re: [Qemu-devel] [Qemu-block] [PATCH] block: early check for blockers on drive-mirror
2018-02-07 16:29 [Qemu-devel] [PATCH] block: early check for blockers on drive-mirror Paolo Bonzini
` (2 preceding siblings ...)
2018-02-08 12:41 ` Alberto Garcia
@ 2018-02-09 15:36 ` Kevin Wolf
2018-02-09 23:07 ` [Qemu-devel] " John Snow
4 siblings, 0 replies; 11+ messages in thread
From: Kevin Wolf @ 2018-02-09 15:36 UTC (permalink / raw)
To: Paolo Bonzini; +Cc: qemu-devel, qemu-block
Am 07.02.2018 um 17:29 hat Paolo Bonzini geschrieben:
> Even if an op blocker is present for BLOCK_OP_TYPE_MIRROR_SOURCE,
> it is checked a bit late and the result is that the target is
> created even if drive-mirror subsequently fails. Add an early
> check to avoid this.
>
> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Thanks, applied to the block branch.
Kevin
^ permalink raw reply [flat|nested] 11+ messages in thread
* Re: [Qemu-devel] [PATCH] block: early check for blockers on drive-mirror
2018-02-07 16:29 [Qemu-devel] [PATCH] block: early check for blockers on drive-mirror Paolo Bonzini
` (3 preceding siblings ...)
2018-02-09 15:36 ` Kevin Wolf
@ 2018-02-09 23:07 ` John Snow
2018-02-12 9:58 ` Paolo Bonzini
4 siblings, 1 reply; 11+ messages in thread
From: John Snow @ 2018-02-09 23:07 UTC (permalink / raw)
To: Paolo Bonzini, qemu-devel; +Cc: qemu-block
On 02/07/2018 11:29 AM, Paolo Bonzini wrote:
> Even if an op blocker is present for BLOCK_OP_TYPE_MIRROR_SOURCE,
> it is checked a bit late and the result is that the target is
> created even if drive-mirror subsequently fails. Add an early
> check to avoid this.
>
> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
> ---
> blockdev.c | 5 +++++
> 1 file changed, 5 insertions(+)
>
> diff --git a/blockdev.c b/blockdev.c
> index 8e977eef11..c7e2e0a00e 100644
> --- a/blockdev.c
> +++ b/blockdev.c
> @@ -3565,6 +3565,11 @@ void qmp_drive_mirror(DriveMirror *arg, Error **errp)
> return;
> }
>
> + /* Early check to avoid creating target */
> + if (bdrv_op_is_blocked(bs, BLOCK_OP_TYPE_MIRROR_SOURCE, errp)) {
> + return;
> + }
> +
> aio_context = bdrv_get_aio_context(bs);
> aio_context_acquire(aio_context);
>
>
What's the implication of the temporarily-extant target node that it
needs to be avoided so strictly?
^ permalink raw reply [flat|nested] 11+ messages in thread
* Re: [Qemu-devel] [PATCH] block: early check for blockers on drive-mirror
2018-02-09 23:07 ` [Qemu-devel] " John Snow
@ 2018-02-12 9:58 ` Paolo Bonzini
2018-02-12 10:02 ` Daniel P. Berrangé
0 siblings, 1 reply; 11+ messages in thread
From: Paolo Bonzini @ 2018-02-12 9:58 UTC (permalink / raw)
To: John Snow, qemu-devel; +Cc: qemu-block
On 10/02/2018 00:07, John Snow wrote:
>> + /* Early check to avoid creating target */
>> + if (bdrv_op_is_blocked(bs, BLOCK_OP_TYPE_MIRROR_SOURCE, errp)) {
>> + return;
>> + }
>> +
>> aio_context = bdrv_get_aio_context(bs);
>> aio_context_acquire(aio_context);
>>
>>
> What's the implication of the temporarily-extant target node that it
> needs to be avoided so strictly?
>
Creating a file on disk, that no one will ever remvoe. :)
Paolo
^ permalink raw reply [flat|nested] 11+ messages in thread
* Re: [Qemu-devel] [PATCH] block: early check for blockers on drive-mirror
2018-02-12 9:58 ` Paolo Bonzini
@ 2018-02-12 10:02 ` Daniel P. Berrangé
2018-02-12 12:42 ` [Qemu-devel] [Qemu-block] " Kevin Wolf
0 siblings, 1 reply; 11+ messages in thread
From: Daniel P. Berrangé @ 2018-02-12 10:02 UTC (permalink / raw)
To: Paolo Bonzini; +Cc: John Snow, qemu-devel, qemu-block
On Mon, Feb 12, 2018 at 10:58:31AM +0100, Paolo Bonzini wrote:
> On 10/02/2018 00:07, John Snow wrote:
> >> + /* Early check to avoid creating target */
> >> + if (bdrv_op_is_blocked(bs, BLOCK_OP_TYPE_MIRROR_SOURCE, errp)) {
> >> + return;
> >> + }
> >> +
> >> aio_context = bdrv_get_aio_context(bs);
> >> aio_context_acquire(aio_context);
> >>
> >>
> > What's the implication of the temporarily-extant target node that it
> > needs to be avoided so strictly?
> >
>
> Creating a file on disk, that no one will ever remvoe. :)
Fortunately libvirt's SELinux policy will probably prevent QEMU creating
it in the first place :-)
Regards,
Daniel
--
|: https://berrange.com -o- https://www.flickr.com/photos/dberrange :|
|: https://libvirt.org -o- https://fstop138.berrange.com :|
|: https://entangle-photo.org -o- https://www.instagram.com/dberrange :|
^ permalink raw reply [flat|nested] 11+ messages in thread
* Re: [Qemu-devel] [Qemu-block] [PATCH] block: early check for blockers on drive-mirror
2018-02-12 10:02 ` Daniel P. Berrangé
@ 2018-02-12 12:42 ` Kevin Wolf
2018-02-12 12:49 ` Daniel P. Berrangé
0 siblings, 1 reply; 11+ messages in thread
From: Kevin Wolf @ 2018-02-12 12:42 UTC (permalink / raw)
To: Daniel P. Berrangé; +Cc: Paolo Bonzini, qemu-devel, qemu-block
Am 12.02.2018 um 11:02 hat Daniel P. Berrangé geschrieben:
> On Mon, Feb 12, 2018 at 10:58:31AM +0100, Paolo Bonzini wrote:
> > On 10/02/2018 00:07, John Snow wrote:
> > >> + /* Early check to avoid creating target */
> > >> + if (bdrv_op_is_blocked(bs, BLOCK_OP_TYPE_MIRROR_SOURCE, errp)) {
> > >> + return;
> > >> + }
> > >> +
> > >> aio_context = bdrv_get_aio_context(bs);
> > >> aio_context_acquire(aio_context);
> > >>
> > >>
> > > What's the implication of the temporarily-extant target node that it
> > > needs to be avoided so strictly?
> > >
> >
> > Creating a file on disk, that no one will ever remvoe. :)
>
> Fortunately libvirt's SELinux policy will probably prevent QEMU creating
> it in the first place :-)
Well, calling drive-mirror without allowing QEMU to create the target
image would be a bit pointless, so I think we can assume that libvirt
did set up the file permission so that QEMU can create it. (Unless
mode=existing is used, but I understand that libvirt doesn't want to
create images with qemu-img, so that doesn't seem to be the case...)
I don't know if libvirt takes care to remove a potentially already
created file if the command then fails, but hopefully it does and the
patch is not actually needed with libvirt.
Kevin
^ permalink raw reply [flat|nested] 11+ messages in thread
* Re: [Qemu-devel] [Qemu-block] [PATCH] block: early check for blockers on drive-mirror
2018-02-12 12:42 ` [Qemu-devel] [Qemu-block] " Kevin Wolf
@ 2018-02-12 12:49 ` Daniel P. Berrangé
0 siblings, 0 replies; 11+ messages in thread
From: Daniel P. Berrangé @ 2018-02-12 12:49 UTC (permalink / raw)
To: Kevin Wolf; +Cc: Paolo Bonzini, qemu-devel, qemu-block
On Mon, Feb 12, 2018 at 01:42:11PM +0100, Kevin Wolf wrote:
> Am 12.02.2018 um 11:02 hat Daniel P. Berrangé geschrieben:
> > On Mon, Feb 12, 2018 at 10:58:31AM +0100, Paolo Bonzini wrote:
> > > On 10/02/2018 00:07, John Snow wrote:
> > > >> + /* Early check to avoid creating target */
> > > >> + if (bdrv_op_is_blocked(bs, BLOCK_OP_TYPE_MIRROR_SOURCE, errp)) {
> > > >> + return;
> > > >> + }
> > > >> +
> > > >> aio_context = bdrv_get_aio_context(bs);
> > > >> aio_context_acquire(aio_context);
> > > >>
> > > >>
> > > > What's the implication of the temporarily-extant target node that it
> > > > needs to be avoided so strictly?
> > > >
> > >
> > > Creating a file on disk, that no one will ever remvoe. :)
> >
> > Fortunately libvirt's SELinux policy will probably prevent QEMU creating
> > it in the first place :-)
>
> Well, calling drive-mirror without allowing QEMU to create the target
> image would be a bit pointless, so I think we can assume that libvirt
> did set up the file permission so that QEMU can create it. (Unless
> mode=existing is used, but I understand that libvirt doesn't want to
> create images with qemu-img, so that doesn't seem to be the case...)
We use either mode=existing or mode=absolute-paths depending on what
the mgmt app asked for in the API call to libvirt. I'm still kind of
suprised if mode=absolute-paths will work because we ought to be
blocking the creation of the file AFAIK and we can't pre-label a file
that doesn't exist yet.
Regards,
Daniel
--
|: https://berrange.com -o- https://www.flickr.com/photos/dberrange :|
|: https://libvirt.org -o- https://fstop138.berrange.com :|
|: https://entangle-photo.org -o- https://www.instagram.com/dberrange :|
^ permalink raw reply [flat|nested] 11+ messages in thread
end of thread, other threads:[~2018-02-12 12:49 UTC | newest]
Thread overview: 11+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2018-02-07 16:29 [Qemu-devel] [PATCH] block: early check for blockers on drive-mirror Paolo Bonzini
2018-02-08 1:17 ` Fam Zheng
2018-02-08 10:10 ` [Qemu-devel] [Qemu-block] " Alberto Garcia
2018-02-08 10:38 ` Paolo Bonzini
2018-02-08 12:41 ` Alberto Garcia
2018-02-09 15:36 ` Kevin Wolf
2018-02-09 23:07 ` [Qemu-devel] " John Snow
2018-02-12 9:58 ` Paolo Bonzini
2018-02-12 10:02 ` Daniel P. Berrangé
2018-02-12 12:42 ` [Qemu-devel] [Qemu-block] " Kevin Wolf
2018-02-12 12:49 ` Daniel P. Berrangé
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