block/commit.c | 3 +++ block/mirror.c | 3 +++ block/qapi.c | 13 ++++++++++++- include/block/block_int.h | 1 + qapi/block-core.json | 6 ++++-- tests/qemu-iotests/041 | 23 +++++++++++++++++++++++ tests/qemu-iotests/041.out | 4 ++-- 7 files changed, 48 insertions(+), 5 deletions(-)
Commits 0db832f and 6cdbceb introduced the automatic insertion of filter
nodes above the top layer of mirror and commit block jobs. The
assumption made there was that since libvirt doesn't do node-level
management of the block layer yet, it shouldn't be affected by added
nodes.
This is true as far as commands issued by libvirt are concerned. It only
uses BlockBackend names to address nodes, so any operations it performs
still operate on the root of the tree as intended.
However, the assumption breaks down when you consider query commands,
which return data for the wrong node now. These commands also return
information on some child nodes (bs->file and/or bs->backing), which
libvirt does make use of, and which refer to the wrong nodes, too.
One of the consequences is that oVirt gets wrong information about the
image size and stops the VM in response as long as a mirror or commit
job is running:
https://bugzilla.redhat.com/show_bug.cgi?id=1470634
This patch fixes the problem by hiding the implict nodes created
automatically by the mirror and commit block jobs in the output of
query-block and BlockBackend-based query-blockstats as long as the user
doesn't indicate that they are aware of those nodes by providing a node
name for them in the QMP command to start the block job.
The node-based commands query-named-block-nodes and query-blockstats
with query-nodes=true still show all nodes, including implicit ones.
This ensures that users that are capable of node-level management can
still access the full information; users that only know BlockBackends
won't use these commands.
Cc: qemu-stable@nongnu.org
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
---
block/commit.c | 3 +++
block/mirror.c | 3 +++
block/qapi.c | 13 ++++++++++++-
include/block/block_int.h | 1 +
qapi/block-core.json | 6 ++++--
tests/qemu-iotests/041 | 23 +++++++++++++++++++++++
tests/qemu-iotests/041.out | 4 ++--
7 files changed, 48 insertions(+), 5 deletions(-)
diff --git a/block/commit.c b/block/commit.c
index 5cc910f..c7857c3 100644
--- a/block/commit.c
+++ b/block/commit.c
@@ -346,6 +346,9 @@ void commit_start(const char *job_id, BlockDriverState *bs,
if (commit_top_bs == NULL) {
goto fail;
}
+ if (!filter_node_name) {
+ commit_top_bs->implicit = true;
+ }
commit_top_bs->total_sectors = top->total_sectors;
bdrv_set_aio_context(commit_top_bs, bdrv_get_aio_context(top));
diff --git a/block/mirror.c b/block/mirror.c
index 8583b76..c9a6a3c 100644
--- a/block/mirror.c
+++ b/block/mirror.c
@@ -1168,6 +1168,9 @@ static void mirror_start_job(const char *job_id, BlockDriverState *bs,
if (mirror_top_bs == NULL) {
return;
}
+ if (!filter_node_name) {
+ mirror_top_bs->implicit = true;
+ }
mirror_top_bs->total_sectors = bs->total_sectors;
bdrv_set_aio_context(mirror_top_bs, bdrv_get_aio_context(bs));
diff --git a/block/qapi.c b/block/qapi.c
index 95b2e2d..0ed23b8 100644
--- a/block/qapi.c
+++ b/block/qapi.c
@@ -324,6 +324,11 @@ static void bdrv_query_info(BlockBackend *blk, BlockInfo **p_info,
BlockDriverState *bs = blk_bs(blk);
char *qdev;
+ /* Skip automatically inserted nodes that the user isn't aware of */
+ while (bs && bs->drv && bs->implicit) {
+ bs = backing_bs(bs);
+ }
+
info->device = g_strdup(blk_name(blk));
info->type = g_strdup("unknown");
info->locked = blk_dev_is_medium_locked(blk);
@@ -518,12 +523,18 @@ BlockStatsList *qmp_query_blockstats(bool has_query_nodes,
}
} else {
for (blk = blk_next(NULL); blk; blk = blk_next(blk)) {
+ BlockDriverState *bs = blk_bs(blk);
BlockStatsList *info = g_malloc0(sizeof(*info));
AioContext *ctx = blk_get_aio_context(blk);
BlockStats *s;
+ /* Skip automatically inserted nodes that the user isn't aware of */
+ while (bs && bs->drv && bs->implicit) {
+ bs = backing_bs(bs);
+ }
+
aio_context_acquire(ctx);
- s = bdrv_query_bds_stats(blk_bs(blk), true);
+ s = bdrv_query_bds_stats(bs, true);
s->has_device = true;
s->device = g_strdup(blk_name(blk));
bdrv_query_blk_stats(s->stats, blk);
diff --git a/include/block/block_int.h b/include/block/block_int.h
index 5c6b761..d4f4ea7 100644
--- a/include/block/block_int.h
+++ b/include/block/block_int.h
@@ -549,6 +549,7 @@ struct BlockDriverState {
bool sg; /* if true, the device is a /dev/sg* */
bool probed; /* if true, format was probed rather than specified */
bool force_share; /* if true, always allow all shared permissions */
+ bool implicit; /* if true, this filter node was automatically inserted */
BlockDriver *drv; /* NULL means no media */
void *opaque;
diff --git a/qapi/block-core.json b/qapi/block-core.json
index ff8e2ba..006e048 100644
--- a/qapi/block-core.json
+++ b/qapi/block-core.json
@@ -520,7 +520,8 @@
#
# Get a list of BlockInfo for all virtual block devices.
#
-# Returns: a list of @BlockInfo describing each virtual block device
+# Returns: a list of @BlockInfo describing each virtual block device. Filter
+# nodes that were created implicitly are skipped over.
#
# Since: 0.14.0
#
@@ -780,7 +781,8 @@
# information, but not "backing".
# If false or omitted, the behavior is as before - query all the
# device backends, recursively including their "parent" and
-# "backing". (Since 2.3)
+# "backing". Filter nodes that were created implicitly are
+# skipped over in this mode. (Since 2.3)
#
# Returns: A list of @BlockStats for each virtual block devices.
#
diff --git a/tests/qemu-iotests/041 b/tests/qemu-iotests/041
index 2f54986..b798cca 100755
--- a/tests/qemu-iotests/041
+++ b/tests/qemu-iotests/041
@@ -169,6 +169,29 @@ class TestSingleDrive(iotests.QMPTestCase):
self.assertTrue(iotests.compare_images(test_img, target_img),
'target image does not match source after mirroring')
+ # Tests that the insertion of the mirror_top filter node doesn't make a
+ # difference to query-block
+ def test_implicit_node(self):
+ self.assert_no_active_block_jobs()
+
+ result = self.vm.qmp(self.qmp_cmd, device='drive0', sync='full',
+ target=self.qmp_target)
+ self.assert_qmp(result, 'return', {})
+
+ result = self.vm.qmp('query-block')
+ self.assert_qmp(result, 'return[0]/inserted/file', test_img)
+ self.assert_qmp(result, 'return[0]/inserted/drv', iotests.imgfmt)
+ self.assert_qmp(result, 'return[0]/inserted/backing_file', backing_img)
+ self.assert_qmp(result, 'return[0]/inserted/backing_file_depth', 1)
+
+ self.cancel_and_wait(force=True)
+ result = self.vm.qmp('query-block')
+ self.assert_qmp(result, 'return[0]/inserted/file', test_img)
+ self.assert_qmp(result, 'return[0]/inserted/drv', iotests.imgfmt)
+ self.assert_qmp(result, 'return[0]/inserted/backing_file', backing_img)
+ self.assert_qmp(result, 'return[0]/inserted/backing_file_depth', 1)
+ self.vm.shutdown()
+
def test_medium_not_found(self):
if iotests.qemu_default_machine != 'pc':
return
diff --git a/tests/qemu-iotests/041.out b/tests/qemu-iotests/041.out
index e30fd3b..c28b392 100644
--- a/tests/qemu-iotests/041.out
+++ b/tests/qemu-iotests/041.out
@@ -1,5 +1,5 @@
-...............................................................................
+.....................................................................................
----------------------------------------------------------------------
-Ran 79 tests
+Ran 85 tests
OK
--
1.8.3.1
On Wed, Jul 19, 2017 at 10:44:47AM +0200, Kevin Wolf wrote: >Commits 0db832f and 6cdbceb introduced the automatic insertion of filter >nodes above the top layer of mirror and commit block jobs. The >assumption made there was that since libvirt doesn't do node-level >management of the block layer yet, it shouldn't be affected by added >nodes. > >This is true as far as commands issued by libvirt are concerned. It only >uses BlockBackend names to address nodes, so any operations it performs >still operate on the root of the tree as intended. > >However, the assumption breaks down when you consider query commands, >which return data for the wrong node now. These commands also return >information on some child nodes (bs->file and/or bs->backing), which >libvirt does make use of, and which refer to the wrong nodes, too. > >One of the consequences is that oVirt gets wrong information about the >image size and stops the VM in response as long as a mirror or commit >job is running: > >https://bugzilla.redhat.com/show_bug.cgi?id=1470634 > >This patch fixes the problem by hiding the implict nodes created s/implict/implicit Also, it seems like qemu-stable wasn't successfully CC'd (the patch is not in the list archives either). Reviewed-by: Manos Pitsidianakis <el13635@mail.ntua.gr>
[ Cc: qemu-stable ] Am 19.07.2017 um 11:21 hat Manos Pitsidianakis geschrieben: > On Wed, Jul 19, 2017 at 10:44:47AM +0200, Kevin Wolf wrote: > >Commits 0db832f and 6cdbceb introduced the automatic insertion of filter > >nodes above the top layer of mirror and commit block jobs. The > >assumption made there was that since libvirt doesn't do node-level > >management of the block layer yet, it shouldn't be affected by added > >nodes. > > > >This is true as far as commands issued by libvirt are concerned. It only > >uses BlockBackend names to address nodes, so any operations it performs > >still operate on the root of the tree as intended. > > > >However, the assumption breaks down when you consider query commands, > >which return data for the wrong node now. These commands also return > >information on some child nodes (bs->file and/or bs->backing), which > >libvirt does make use of, and which refer to the wrong nodes, too. > > > >One of the consequences is that oVirt gets wrong information about the > >image size and stops the VM in response as long as a mirror or commit > >job is running: > > > >https://bugzilla.redhat.com/show_bug.cgi?id=1470634 > > > >This patch fixes the problem by hiding the implict nodes created > s/implict/implicit Fixed. > Also, it seems like qemu-stable wasn't successfully CC'd (the patch > is not in the list archives either). Ah yes, forgot to actually CC it on the mail. Adding it to this mail. > Reviewed-by: Manos Pitsidianakis <el13635@mail.ntua.gr> Thanks! Kevin
On Wed, Jul 19, 2017 at 10:44:47 +0200, Kevin Wolf wrote:
> Commits 0db832f and 6cdbceb introduced the automatic insertion of filter
> nodes above the top layer of mirror and commit block jobs. The
> assumption made there was that since libvirt doesn't do node-level
> management of the block layer yet, it shouldn't be affected by added
> nodes.
>
> This is true as far as commands issued by libvirt are concerned. It only
> uses BlockBackend names to address nodes, so any operations it performs
> still operate on the root of the tree as intended.
>
> However, the assumption breaks down when you consider query commands,
> which return data for the wrong node now. These commands also return
> information on some child nodes (bs->file and/or bs->backing), which
> libvirt does make use of, and which refer to the wrong nodes, too.
>
> One of the consequences is that oVirt gets wrong information about the
> image size and stops the VM in response as long as a mirror or commit
> job is running:
>
> https://bugzilla.redhat.com/show_bug.cgi?id=1470634
>
> This patch fixes the problem by hiding the implict nodes created
> automatically by the mirror and commit block jobs in the output of
> query-block and BlockBackend-based query-blockstats as long as the user
> doesn't indicate that they are aware of those nodes by providing a node
> name for them in the QMP command to start the block job.
>
> The node-based commands query-named-block-nodes and query-blockstats
> with query-nodes=true still show all nodes, including implicit ones.
> This ensures that users that are capable of node-level management can
> still access the full information; users that only know BlockBackends
> won't use these commands.
>
> Cc: qemu-stable@nongnu.org
> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
> ---
> block/commit.c | 3 +++
> block/mirror.c | 3 +++
> block/qapi.c | 13 ++++++++++++-
> include/block/block_int.h | 1 +
> qapi/block-core.json | 6 ++++--
> tests/qemu-iotests/041 | 23 +++++++++++++++++++++++
> tests/qemu-iotests/041.out | 4 ++--
> 7 files changed, 48 insertions(+), 5 deletions(-)
Fails to apply to master, thus I didn't do a functional check, but from
reading the code ...
> diff --git a/block/qapi.c b/block/qapi.c
> index 95b2e2d..0ed23b8 100644
> --- a/block/qapi.c
> +++ b/block/qapi.c
> @@ -324,6 +324,11 @@ static void bdrv_query_info(BlockBackend *blk, BlockInfo **p_info,
> BlockDriverState *bs = blk_bs(blk);
> char *qdev;
>
> + /* Skip automatically inserted nodes that the user isn't aware of */
> + while (bs && bs->drv && bs->implicit) {
> + bs = backing_bs(bs);
> + }
So bdrv_query_info then calls bdrv_block_device_info, which also
populates the backing chain for that bs. That function does not do this
trick of skipping the implicit nodes.
From what I've understood from the 'commit' job, it's possible to have
the implicit node inserted even at the @top bs of the commit job, so it
looks to me as if bdrv_block_device_info will need such a tweak too.
> +
> info->device = g_strdup(blk_name(blk));
> info->type = g_strdup("unknown");
> info->locked = blk_dev_is_medium_locked(blk);
> @@ -518,12 +523,18 @@ BlockStatsList *qmp_query_blockstats(bool has_query_nodes,
> }
> } else {
> for (blk = blk_next(NULL); blk; blk = blk_next(blk)) {
> + BlockDriverState *bs = blk_bs(blk);
> BlockStatsList *info = g_malloc0(sizeof(*info));
> AioContext *ctx = blk_get_aio_context(blk);
> BlockStats *s;
>
> + /* Skip automatically inserted nodes that the user isn't aware of */
> + while (bs && bs->drv && bs->implicit) {
> + bs = backing_bs(bs);
> + }
> +
> aio_context_acquire(ctx);
> - s = bdrv_query_bds_stats(blk_bs(blk), true);
> + s = bdrv_query_bds_stats(bs, true);
Same here. The recursive call in bdrv_query_bds_stats does not skip the
implicitly added layers IIUC.
> s->has_device = true;
> s->device = g_strdup(blk_name(blk));
> bdrv_query_blk_stats(s->stats, blk);
Feel free to add a 'Reviewed-by' if I did not understand what's
happening in the commit job properly, or if you add the skipping into
the gathering functions as well.
Peter
Am 19.07.2017 um 13:15 hat Peter Krempa geschrieben:
> On Wed, Jul 19, 2017 at 10:44:47 +0200, Kevin Wolf wrote:
> > Commits 0db832f and 6cdbceb introduced the automatic insertion of filter
> > nodes above the top layer of mirror and commit block jobs. The
> > assumption made there was that since libvirt doesn't do node-level
> > management of the block layer yet, it shouldn't be affected by added
> > nodes.
> >
> > This is true as far as commands issued by libvirt are concerned. It only
> > uses BlockBackend names to address nodes, so any operations it performs
> > still operate on the root of the tree as intended.
> >
> > However, the assumption breaks down when you consider query commands,
> > which return data for the wrong node now. These commands also return
> > information on some child nodes (bs->file and/or bs->backing), which
> > libvirt does make use of, and which refer to the wrong nodes, too.
> >
> > One of the consequences is that oVirt gets wrong information about the
> > image size and stops the VM in response as long as a mirror or commit
> > job is running:
> >
> > https://bugzilla.redhat.com/show_bug.cgi?id=1470634
> >
> > This patch fixes the problem by hiding the implict nodes created
> > automatically by the mirror and commit block jobs in the output of
> > query-block and BlockBackend-based query-blockstats as long as the user
> > doesn't indicate that they are aware of those nodes by providing a node
> > name for them in the QMP command to start the block job.
> >
> > The node-based commands query-named-block-nodes and query-blockstats
> > with query-nodes=true still show all nodes, including implicit ones.
> > This ensures that users that are capable of node-level management can
> > still access the full information; users that only know BlockBackends
> > won't use these commands.
> >
> > Cc: qemu-stable@nongnu.org
> > Signed-off-by: Kevin Wolf <kwolf@redhat.com>
> > ---
> > block/commit.c | 3 +++
> > block/mirror.c | 3 +++
> > block/qapi.c | 13 ++++++++++++-
> > include/block/block_int.h | 1 +
> > qapi/block-core.json | 6 ++++--
> > tests/qemu-iotests/041 | 23 +++++++++++++++++++++++
> > tests/qemu-iotests/041.out | 4 ++--
> > 7 files changed, 48 insertions(+), 5 deletions(-)
>
> Fails to apply to master, thus I didn't do a functional check, but from
> reading the code ...
My last pull request was just merged into master, so now it should apply
cleanly.
> > diff --git a/block/qapi.c b/block/qapi.c
> > index 95b2e2d..0ed23b8 100644
> > --- a/block/qapi.c
> > +++ b/block/qapi.c
> > @@ -324,6 +324,11 @@ static void bdrv_query_info(BlockBackend *blk, BlockInfo **p_info,
> > BlockDriverState *bs = blk_bs(blk);
> > char *qdev;
> >
> > + /* Skip automatically inserted nodes that the user isn't aware of */
> > + while (bs && bs->drv && bs->implicit) {
> > + bs = backing_bs(bs);
> > + }
>
> So bdrv_query_info then calls bdrv_block_device_info, which also
> populates the backing chain for that bs. That function does not do this
> trick of skipping the implicit nodes.
>
> From what I've understood from the 'commit' job, it's possible to have
> the implicit node inserted even at the @top bs of the commit job, so it
> looks to me as if bdrv_block_device_info will need such a tweak too.
Ah, yes, I missed the recursive calls. I will add another loop as you
suggest.
> > +
> > info->device = g_strdup(blk_name(blk));
> > info->type = g_strdup("unknown");
> > info->locked = blk_dev_is_medium_locked(blk);
> > @@ -518,12 +523,18 @@ BlockStatsList *qmp_query_blockstats(bool has_query_nodes,
> > }
> > } else {
> > for (blk = blk_next(NULL); blk; blk = blk_next(blk)) {
> > + BlockDriverState *bs = blk_bs(blk);
> > BlockStatsList *info = g_malloc0(sizeof(*info));
> > AioContext *ctx = blk_get_aio_context(blk);
> > BlockStats *s;
> >
> > + /* Skip automatically inserted nodes that the user isn't aware of */
> > + while (bs && bs->drv && bs->implicit) {
> > + bs = backing_bs(bs);
> > + }
> > +
> > aio_context_acquire(ctx);
> > - s = bdrv_query_bds_stats(blk_bs(blk), true);
> > + s = bdrv_query_bds_stats(bs, true);
>
> Same here. The recursive call in bdrv_query_bds_stats does not skip the
> implicitly added layers IIUC.
Indeed.
> > s->has_device = true;
> > s->device = g_strdup(blk_name(blk));
> > bdrv_query_blk_stats(s->stats, blk);
>
> Feel free to add a 'Reviewed-by' if I did not understand what's
> happening in the commit job properly, or if you add the skipping into
> the gathering functions as well.
I'll send a v2 for this, it doesn't seem trivial enough to just add
Reviewed-by.
Kevin
On 07/19/2017 03:44 AM, Kevin Wolf wrote: > Commits 0db832f and 6cdbceb introduced the automatic insertion of filter > nodes above the top layer of mirror and commit block jobs. The > assumption made there was that since libvirt doesn't do node-level > management of the block layer yet, it shouldn't be affected by added > nodes. Those both landed in 2.9. So this is a regression we're trying to fix. > > This is true as far as commands issued by libvirt are concerned. It only > uses BlockBackend names to address nodes, so any operations it performs > still operate on the root of the tree as intended. > > However, the assumption breaks down when you consider query commands, > which return data for the wrong node now. These commands also return > information on some child nodes (bs->file and/or bs->backing), which > libvirt does make use of, and which refer to the wrong nodes, too. > > One of the consequences is that oVirt gets wrong information about the > image size and stops the VM in response as long as a mirror or commit > job is running: > > https://bugzilla.redhat.com/show_bug.cgi?id=1470634 > > This patch fixes the problem by hiding the implict nodes created > automatically by the mirror and commit block jobs in the output of > query-block and BlockBackend-based query-blockstats as long as the user > doesn't indicate that they are aware of those nodes by providing a node > name for them in the QMP command to start the block job. The approach makes sense to me. I see from the rest of this thread that you'll need a v2 to get the implementation of the approach correct, but I think you're on the right track. > > The node-based commands query-named-block-nodes and query-blockstats > with query-nodes=true still show all nodes, including implicit ones. > This ensures that users that are capable of node-level management can > still access the full information; users that only know BlockBackends > won't use these commands. > > Cc: qemu-stable@nongnu.org > Signed-off-by: Kevin Wolf <kwolf@redhat.com> > --- -- Eric Blake, Principal Software Engineer Red Hat, Inc. +1-919-301-3266 Virtualization: qemu.org | libvirt.org
Kevin Wolf <kwolf@redhat.com> writes:
> Commits 0db832f and 6cdbceb introduced the automatic insertion of filter
> nodes above the top layer of mirror and commit block jobs. The
> assumption made there was that since libvirt doesn't do node-level
> management of the block layer yet, it shouldn't be affected by added
> nodes.
>
> This is true as far as commands issued by libvirt are concerned. It only
> uses BlockBackend names to address nodes, so any operations it performs
> still operate on the root of the tree as intended.
>
> However, the assumption breaks down when you consider query commands,
> which return data for the wrong node now. These commands also return
> information on some child nodes (bs->file and/or bs->backing), which
> libvirt does make use of, and which refer to the wrong nodes, too.
>
> One of the consequences is that oVirt gets wrong information about the
> image size and stops the VM in response as long as a mirror or commit
> job is running:
>
> https://bugzilla.redhat.com/show_bug.cgi?id=1470634
>
> This patch fixes the problem by hiding the implict nodes created
> automatically by the mirror and commit block jobs in the output of
> query-block and BlockBackend-based query-blockstats as long as the user
> doesn't indicate that they are aware of those nodes by providing a node
> name for them in the QMP command to start the block job.
>
> The node-based commands query-named-block-nodes and query-blockstats
> with query-nodes=true still show all nodes, including implicit ones.
The only other query-FOO in block*.json is query-block-jobs. Good.
> This ensures that users that are capable of node-level management can
> still access the full information; users that only know BlockBackends
> won't use these commands.
I think I can follow your reasoning, but I could use a concrete example.
A small reproducer with output before and after the patch, and an
explanation what exactly makes the output before the patch problematic.
> Cc: qemu-stable@nongnu.org
> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
> ---
> block/commit.c | 3 +++
> block/mirror.c | 3 +++
> block/qapi.c | 13 ++++++++++++-
> include/block/block_int.h | 1 +
> qapi/block-core.json | 6 ++++--
> tests/qemu-iotests/041 | 23 +++++++++++++++++++++++
> tests/qemu-iotests/041.out | 4 ++--
> 7 files changed, 48 insertions(+), 5 deletions(-)
>
> diff --git a/block/commit.c b/block/commit.c
> index 5cc910f..c7857c3 100644
> --- a/block/commit.c
> +++ b/block/commit.c
> @@ -346,6 +346,9 @@ void commit_start(const char *job_id, BlockDriverState *bs,
> if (commit_top_bs == NULL) {
> goto fail;
> }
> + if (!filter_node_name) {
> + commit_top_bs->implicit = true;
> + }
> commit_top_bs->total_sectors = top->total_sectors;
> bdrv_set_aio_context(commit_top_bs, bdrv_get_aio_context(top));
>
> diff --git a/block/mirror.c b/block/mirror.c
> index 8583b76..c9a6a3c 100644
> --- a/block/mirror.c
> +++ b/block/mirror.c
> @@ -1168,6 +1168,9 @@ static void mirror_start_job(const char *job_id, BlockDriverState *bs,
> if (mirror_top_bs == NULL) {
> return;
> }
> + if (!filter_node_name) {
> + mirror_top_bs->implicit = true;
> + }
> mirror_top_bs->total_sectors = bs->total_sectors;
> bdrv_set_aio_context(mirror_top_bs, bdrv_get_aio_context(bs));
>
> diff --git a/block/qapi.c b/block/qapi.c
> index 95b2e2d..0ed23b8 100644
> --- a/block/qapi.c
> +++ b/block/qapi.c
> @@ -324,6 +324,11 @@ static void bdrv_query_info(BlockBackend *blk, BlockInfo **p_info,
> BlockDriverState *bs = blk_bs(blk);
> char *qdev;
>
> + /* Skip automatically inserted nodes that the user isn't aware of */
> + while (bs && bs->drv && bs->implicit) {
> + bs = backing_bs(bs);
> + }
> +
> info->device = g_strdup(blk_name(blk));
> info->type = g_strdup("unknown");
> info->locked = blk_dev_is_medium_locked(blk);
> @@ -518,12 +523,18 @@ BlockStatsList *qmp_query_blockstats(bool has_query_nodes,
> }
> } else {
> for (blk = blk_next(NULL); blk; blk = blk_next(blk)) {
> + BlockDriverState *bs = blk_bs(blk);
> BlockStatsList *info = g_malloc0(sizeof(*info));
> AioContext *ctx = blk_get_aio_context(blk);
> BlockStats *s;
>
> + /* Skip automatically inserted nodes that the user isn't aware of */
> + while (bs && bs->drv && bs->implicit) {
> + bs = backing_bs(bs);
> + }
> +
> aio_context_acquire(ctx);
> - s = bdrv_query_bds_stats(blk_bs(blk), true);
> + s = bdrv_query_bds_stats(bs, true);
> s->has_device = true;
> s->device = g_strdup(blk_name(blk));
> bdrv_query_blk_stats(s->stats, blk);
The result types of query-block and query-blockstats are recursive. How
can I convince myself that we're skipping everywhere we need to?
> diff --git a/include/block/block_int.h b/include/block/block_int.h
> index 5c6b761..d4f4ea7 100644
> --- a/include/block/block_int.h
> +++ b/include/block/block_int.h
> @@ -549,6 +549,7 @@ struct BlockDriverState {
> bool sg; /* if true, the device is a /dev/sg* */
> bool probed; /* if true, format was probed rather than specified */
> bool force_share; /* if true, always allow all shared permissions */
> + bool implicit; /* if true, this filter node was automatically inserted */
Makes sense. How can I convince myself that your patch marks them all?
>
> BlockDriver *drv; /* NULL means no media */
> void *opaque;
> diff --git a/qapi/block-core.json b/qapi/block-core.json
> index ff8e2ba..006e048 100644
> --- a/qapi/block-core.json
> +++ b/qapi/block-core.json
> @@ -520,7 +520,8 @@
> #
> # Get a list of BlockInfo for all virtual block devices.
> #
> -# Returns: a list of @BlockInfo describing each virtual block device
> +# Returns: a list of @BlockInfo describing each virtual block device. Filter
> +# nodes that were created implicitly are skipped over.
> #
> # Since: 0.14.0
> #
> @@ -780,7 +781,8 @@
> # information, but not "backing".
> # If false or omitted, the behavior is as before - query all the
> # device backends, recursively including their "parent" and
> -# "backing". (Since 2.3)
> +# "backing". Filter nodes that were created implicitly are
> +# skipped over in this mode. (Since 2.3)
> #
> # Returns: A list of @BlockStats for each virtual block devices.
> #
> diff --git a/tests/qemu-iotests/041 b/tests/qemu-iotests/041
> index 2f54986..b798cca 100755
> --- a/tests/qemu-iotests/041
> +++ b/tests/qemu-iotests/041
> @@ -169,6 +169,29 @@ class TestSingleDrive(iotests.QMPTestCase):
> self.assertTrue(iotests.compare_images(test_img, target_img),
> 'target image does not match source after mirroring')
>
> + # Tests that the insertion of the mirror_top filter node doesn't make a
> + # difference to query-block
> + def test_implicit_node(self):
> + self.assert_no_active_block_jobs()
> +
> + result = self.vm.qmp(self.qmp_cmd, device='drive0', sync='full',
> + target=self.qmp_target)
> + self.assert_qmp(result, 'return', {})
> +
> + result = self.vm.qmp('query-block')
> + self.assert_qmp(result, 'return[0]/inserted/file', test_img)
> + self.assert_qmp(result, 'return[0]/inserted/drv', iotests.imgfmt)
> + self.assert_qmp(result, 'return[0]/inserted/backing_file', backing_img)
> + self.assert_qmp(result, 'return[0]/inserted/backing_file_depth', 1)
> +
> + self.cancel_and_wait(force=True)
> + result = self.vm.qmp('query-block')
> + self.assert_qmp(result, 'return[0]/inserted/file', test_img)
> + self.assert_qmp(result, 'return[0]/inserted/drv', iotests.imgfmt)
> + self.assert_qmp(result, 'return[0]/inserted/backing_file', backing_img)
> + self.assert_qmp(result, 'return[0]/inserted/backing_file_depth', 1)
> + self.vm.shutdown()
> +
> def test_medium_not_found(self):
> if iotests.qemu_default_machine != 'pc':
> return
> diff --git a/tests/qemu-iotests/041.out b/tests/qemu-iotests/041.out
> index e30fd3b..c28b392 100644
> --- a/tests/qemu-iotests/041.out
> +++ b/tests/qemu-iotests/041.out
> @@ -1,5 +1,5 @@
> -...............................................................................
> +.....................................................................................
> ----------------------------------------------------------------------
> -Ran 79 tests
> +Ran 85 tests
>
> OK
The patch makes sense to me. The hard part is judging whether it's
complete. I could use a bit of help with that.
On Wed, Jul 19, 2017 at 4:05 PM Markus Armbruster <armbru@redhat.com> wrote:
> Kevin Wolf <kwolf@redhat.com> writes:
>
> > Commits 0db832f and 6cdbceb introduced the automatic insertion of filter
> > nodes above the top layer of mirror and commit block jobs. The
> > assumption made there was that since libvirt doesn't do node-level
> > management of the block layer yet, it shouldn't be affected by added
> > nodes.
> >
> > This is true as far as commands issued by libvirt are concerned. It only
> > uses BlockBackend names to address nodes, so any operations it performs
> > still operate on the root of the tree as intended.
> >
> > However, the assumption breaks down when you consider query commands,
> > which return data for the wrong node now. These commands also return
> > information on some child nodes (bs->file and/or bs->backing), which
> > libvirt does make use of, and which refer to the wrong nodes, too.
> >
> > One of the consequences is that oVirt gets wrong information about the
> > image size and stops the VM in response as long as a mirror or commit
> > job is running:
> >
> > https://bugzilla.redhat.com/show_bug.cgi?id=1470634
> >
> > This patch fixes the problem by hiding the implict nodes created
> > automatically by the mirror and commit block jobs in the output of
> > query-block and BlockBackend-based query-blockstats as long as the user
> > doesn't indicate that they are aware of those nodes by providing a node
> > name for them in the QMP command to start the block job.
> >
> > The node-based commands query-named-block-nodes and query-blockstats
> > with query-nodes=true still show all nodes, including implicit ones.
>
> The only other query-FOO in block*.json is query-block-jobs. Good.
>
> > This ensures that users that are capable of node-level management can
> > still access the full information; users that only know BlockBackends
> > won't use these commands.
>
> I think I can follow your reasoning, but I could use a concrete example.
> A small reproducer with output before and after the patch, and an
> explanation what exactly makes the output before the patch problematic.
>
You can find a reproducer and example output here:
https://bugzilla.redhat.com/show_bug.cgi?id=1470634#c28
>
> > Cc: qemu-stable@nongnu.org
> > Signed-off-by: Kevin Wolf <kwolf@redhat.com>
> > ---
> > block/commit.c | 3 +++
> > block/mirror.c | 3 +++
> > block/qapi.c | 13 ++++++++++++-
> > include/block/block_int.h | 1 +
> > qapi/block-core.json | 6 ++++--
> > tests/qemu-iotests/041 | 23 +++++++++++++++++++++++
> > tests/qemu-iotests/041.out | 4 ++--
> > 7 files changed, 48 insertions(+), 5 deletions(-)
> >
> > diff --git a/block/commit.c b/block/commit.c
> > index 5cc910f..c7857c3 100644
> > --- a/block/commit.c
> > +++ b/block/commit.c
> > @@ -346,6 +346,9 @@ void commit_start(const char *job_id,
> BlockDriverState *bs,
> > if (commit_top_bs == NULL) {
> > goto fail;
> > }
> > + if (!filter_node_name) {
> > + commit_top_bs->implicit = true;
> > + }
> > commit_top_bs->total_sectors = top->total_sectors;
> > bdrv_set_aio_context(commit_top_bs, bdrv_get_aio_context(top));
> >
> > diff --git a/block/mirror.c b/block/mirror.c
> > index 8583b76..c9a6a3c 100644
> > --- a/block/mirror.c
> > +++ b/block/mirror.c
> > @@ -1168,6 +1168,9 @@ static void mirror_start_job(const char *job_id,
> BlockDriverState *bs,
> > if (mirror_top_bs == NULL) {
> > return;
> > }
> > + if (!filter_node_name) {
> > + mirror_top_bs->implicit = true;
> > + }
> > mirror_top_bs->total_sectors = bs->total_sectors;
> > bdrv_set_aio_context(mirror_top_bs, bdrv_get_aio_context(bs));
> >
> > diff --git a/block/qapi.c b/block/qapi.c
> > index 95b2e2d..0ed23b8 100644
> > --- a/block/qapi.c
> > +++ b/block/qapi.c
> > @@ -324,6 +324,11 @@ static void bdrv_query_info(BlockBackend *blk,
> BlockInfo **p_info,
> > BlockDriverState *bs = blk_bs(blk);
> > char *qdev;
> >
> > + /* Skip automatically inserted nodes that the user isn't aware of */
> > + while (bs && bs->drv && bs->implicit) {
> > + bs = backing_bs(bs);
> > + }
> > +
> > info->device = g_strdup(blk_name(blk));
> > info->type = g_strdup("unknown");
> > info->locked = blk_dev_is_medium_locked(blk);
> > @@ -518,12 +523,18 @@ BlockStatsList *qmp_query_blockstats(bool
> has_query_nodes,
> > }
> > } else {
> > for (blk = blk_next(NULL); blk; blk = blk_next(blk)) {
> > + BlockDriverState *bs = blk_bs(blk);
> > BlockStatsList *info = g_malloc0(sizeof(*info));
> > AioContext *ctx = blk_get_aio_context(blk);
> > BlockStats *s;
> >
> > + /* Skip automatically inserted nodes that the user isn't
> aware of */
> > + while (bs && bs->drv && bs->implicit) {
> > + bs = backing_bs(bs);
> > + }
> > +
> > aio_context_acquire(ctx);
> > - s = bdrv_query_bds_stats(blk_bs(blk), true);
> > + s = bdrv_query_bds_stats(bs, true);
> > s->has_device = true;
> > s->device = g_strdup(blk_name(blk));
> > bdrv_query_blk_stats(s->stats, blk);
>
> The result types of query-block and query-blockstats are recursive. How
> can I convince myself that we're skipping everywhere we need to?
>
> > diff --git a/include/block/block_int.h b/include/block/block_int.h
> > index 5c6b761..d4f4ea7 100644
> > --- a/include/block/block_int.h
> > +++ b/include/block/block_int.h
> > @@ -549,6 +549,7 @@ struct BlockDriverState {
> > bool sg; /* if true, the device is a /dev/sg* */
> > bool probed; /* if true, format was probed rather than specified
> */
> > bool force_share; /* if true, always allow all shared permissions */
> > + bool implicit; /* if true, this filter node was automatically
> inserted */
>
> Makes sense. How can I convince myself that your patch marks them all?
>
> >
> > BlockDriver *drv; /* NULL means no media */
> > void *opaque;
> > diff --git a/qapi/block-core.json b/qapi/block-core.json
> > index ff8e2ba..006e048 100644
> > --- a/qapi/block-core.json
> > +++ b/qapi/block-core.json
> > @@ -520,7 +520,8 @@
> > #
> > # Get a list of BlockInfo for all virtual block devices.
> > #
> > -# Returns: a list of @BlockInfo describing each virtual block device
> > +# Returns: a list of @BlockInfo describing each virtual block device.
> Filter
> > +# nodes that were created implicitly are skipped over.
> > #
> > # Since: 0.14.0
> > #
> > @@ -780,7 +781,8 @@
> > # information, but not "backing".
> > # If false or omitted, the behavior is as before - query
> all the
> > # device backends, recursively including their "parent"
> and
> > -# "backing". (Since 2.3)
> > +# "backing". Filter nodes that were created implicitly are
> > +# skipped over in this mode. (Since 2.3)
> > #
> > # Returns: A list of @BlockStats for each virtual block devices.
> > #
> > diff --git a/tests/qemu-iotests/041 b/tests/qemu-iotests/041
> > index 2f54986..b798cca 100755
> > --- a/tests/qemu-iotests/041
> > +++ b/tests/qemu-iotests/041
> > @@ -169,6 +169,29 @@ class TestSingleDrive(iotests.QMPTestCase):
> > self.assertTrue(iotests.compare_images(test_img, target_img),
> > 'target image does not match source after
> mirroring')
> >
> > + # Tests that the insertion of the mirror_top filter node doesn't
> make a
> > + # difference to query-block
> > + def test_implicit_node(self):
> > + self.assert_no_active_block_jobs()
> > +
> > + result = self.vm.qmp(self.qmp_cmd, device='drive0', sync='full',
> > + target=self.qmp_target)
> > + self.assert_qmp(result, 'return', {})
> > +
> > + result = self.vm.qmp('query-block')
> > + self.assert_qmp(result, 'return[0]/inserted/file', test_img)
> > + self.assert_qmp(result, 'return[0]/inserted/drv',
> iotests.imgfmt)
> > + self.assert_qmp(result, 'return[0]/inserted/backing_file',
> backing_img)
> > + self.assert_qmp(result,
> 'return[0]/inserted/backing_file_depth', 1)
> > +
> > + self.cancel_and_wait(force=True)
> > + result = self.vm.qmp('query-block')
> > + self.assert_qmp(result, 'return[0]/inserted/file', test_img)
> > + self.assert_qmp(result, 'return[0]/inserted/drv',
> iotests.imgfmt)
> > + self.assert_qmp(result, 'return[0]/inserted/backing_file',
> backing_img)
> > + self.assert_qmp(result,
> 'return[0]/inserted/backing_file_depth', 1)
> > + self.vm.shutdown()
> > +
> > def test_medium_not_found(self):
> > if iotests.qemu_default_machine != 'pc':
> > return
> > diff --git a/tests/qemu-iotests/041.out b/tests/qemu-iotests/041.out
> > index e30fd3b..c28b392 100644
> > --- a/tests/qemu-iotests/041.out
> > +++ b/tests/qemu-iotests/041.out
> > @@ -1,5 +1,5 @@
> >
> -...............................................................................
> >
> +.....................................................................................
> > ----------------------------------------------------------------------
> > -Ran 79 tests
> > +Ran 85 tests
> >
> > OK
>
> The patch makes sense to me. The hard part is judging whether it's
> complete. I could use a bit of help with that.
>
Am 19.07.2017 um 15:05 hat Markus Armbruster geschrieben:
> Kevin Wolf <kwolf@redhat.com> writes:
>
> > Commits 0db832f and 6cdbceb introduced the automatic insertion of filter
> > nodes above the top layer of mirror and commit block jobs. The
> > assumption made there was that since libvirt doesn't do node-level
> > management of the block layer yet, it shouldn't be affected by added
> > nodes.
> >
> > This is true as far as commands issued by libvirt are concerned. It only
> > uses BlockBackend names to address nodes, so any operations it performs
> > still operate on the root of the tree as intended.
> >
> > However, the assumption breaks down when you consider query commands,
> > which return data for the wrong node now. These commands also return
> > information on some child nodes (bs->file and/or bs->backing), which
> > libvirt does make use of, and which refer to the wrong nodes, too.
> >
> > One of the consequences is that oVirt gets wrong information about the
> > image size and stops the VM in response as long as a mirror or commit
> > job is running:
> >
> > https://bugzilla.redhat.com/show_bug.cgi?id=1470634
> >
> > This patch fixes the problem by hiding the implict nodes created
> > automatically by the mirror and commit block jobs in the output of
> > query-block and BlockBackend-based query-blockstats as long as the user
> > doesn't indicate that they are aware of those nodes by providing a node
> > name for them in the QMP command to start the block job.
> >
> > The node-based commands query-named-block-nodes and query-blockstats
> > with query-nodes=true still show all nodes, including implicit ones.
>
> The only other query-FOO in block*.json is query-block-jobs. Good.
>
> > This ensures that users that are capable of node-level management can
> > still access the full information; users that only know BlockBackends
> > won't use these commands.
>
> I think I can follow your reasoning, but I could use a concrete example.
> A small reproducer with output before and after the patch, and an
> explanation what exactly makes the output before the patch problematic.
Nir already replied with a link to comment 28 in the referenced BZ.
Thanks!
In short, the management tool is interested in "actual-size" of the
top-level image (as far as I can tell in order to check whether the
target device is large enough), but while the block job is running, it
gets the results for the filter node instead, where "actual-size" isn't
even present.
> > Cc: qemu-stable@nongnu.org
> > Signed-off-by: Kevin Wolf <kwolf@redhat.com>
> > ---
> > block/commit.c | 3 +++
> > block/mirror.c | 3 +++
> > block/qapi.c | 13 ++++++++++++-
> > include/block/block_int.h | 1 +
> > qapi/block-core.json | 6 ++++--
> > tests/qemu-iotests/041 | 23 +++++++++++++++++++++++
> > tests/qemu-iotests/041.out | 4 ++--
> > 7 files changed, 48 insertions(+), 5 deletions(-)
> >
> > diff --git a/block/commit.c b/block/commit.c
> > index 5cc910f..c7857c3 100644
> > --- a/block/commit.c
> > +++ b/block/commit.c
> > @@ -346,6 +346,9 @@ void commit_start(const char *job_id, BlockDriverState *bs,
> > if (commit_top_bs == NULL) {
> > goto fail;
> > }
> > + if (!filter_node_name) {
> > + commit_top_bs->implicit = true;
> > + }
> > commit_top_bs->total_sectors = top->total_sectors;
> > bdrv_set_aio_context(commit_top_bs, bdrv_get_aio_context(top));
> >
> > diff --git a/block/mirror.c b/block/mirror.c
> > index 8583b76..c9a6a3c 100644
> > --- a/block/mirror.c
> > +++ b/block/mirror.c
> > @@ -1168,6 +1168,9 @@ static void mirror_start_job(const char *job_id, BlockDriverState *bs,
> > if (mirror_top_bs == NULL) {
> > return;
> > }
> > + if (!filter_node_name) {
> > + mirror_top_bs->implicit = true;
> > + }
> > mirror_top_bs->total_sectors = bs->total_sectors;
> > bdrv_set_aio_context(mirror_top_bs, bdrv_get_aio_context(bs));
> >
> > diff --git a/block/qapi.c b/block/qapi.c
> > index 95b2e2d..0ed23b8 100644
> > --- a/block/qapi.c
> > +++ b/block/qapi.c
> > @@ -324,6 +324,11 @@ static void bdrv_query_info(BlockBackend *blk, BlockInfo **p_info,
> > BlockDriverState *bs = blk_bs(blk);
> > char *qdev;
> >
> > + /* Skip automatically inserted nodes that the user isn't aware of */
> > + while (bs && bs->drv && bs->implicit) {
> > + bs = backing_bs(bs);
> > + }
> > +
> > info->device = g_strdup(blk_name(blk));
> > info->type = g_strdup("unknown");
> > info->locked = blk_dev_is_medium_locked(blk);
> > @@ -518,12 +523,18 @@ BlockStatsList *qmp_query_blockstats(bool has_query_nodes,
> > }
> > } else {
> > for (blk = blk_next(NULL); blk; blk = blk_next(blk)) {
> > + BlockDriverState *bs = blk_bs(blk);
> > BlockStatsList *info = g_malloc0(sizeof(*info));
> > AioContext *ctx = blk_get_aio_context(blk);
> > BlockStats *s;
> >
> > + /* Skip automatically inserted nodes that the user isn't aware of */
> > + while (bs && bs->drv && bs->implicit) {
> > + bs = backing_bs(bs);
> > + }
> > +
> > aio_context_acquire(ctx);
> > - s = bdrv_query_bds_stats(blk_bs(blk), true);
> > + s = bdrv_query_bds_stats(bs, true);
> > s->has_device = true;
> > s->device = g_strdup(blk_name(blk));
> > bdrv_query_blk_stats(s->stats, blk);
>
> The result types of query-block and query-blockstats are recursive. How
> can I convince myself that we're skipping everywhere we need to?
As Peter already commented, the recursive calls aren't covered. I'll
send out a v2 soon.
> > diff --git a/include/block/block_int.h b/include/block/block_int.h
> > index 5c6b761..d4f4ea7 100644
> > --- a/include/block/block_int.h
> > +++ b/include/block/block_int.h
> > @@ -549,6 +549,7 @@ struct BlockDriverState {
> > bool sg; /* if true, the device is a /dev/sg* */
> > bool probed; /* if true, format was probed rather than specified */
> > bool force_share; /* if true, always allow all shared permissions */
> > + bool implicit; /* if true, this filter node was automatically inserted */
>
> Makes sense. How can I convince myself that your patch marks them all?
Tough question. The real answer is probably that you have to check all
(direct and indirect) callers of bdrv_open_driver().
The lazier answer is that we just know that bdrv_open_common() is never
called to create implicit nodes and we can restrict ourselves to calls
of bdrv_new_open_driver().
We have four calls of this function:
* In commit_start() and mirror_start_job(): Covered by this patch
* In bdrv_commit(): We could add it to commit_top_bs there, but it's a
temporary node that is removed again before the function returns, and
we're running under BQL, so it doesn't make a difference
* In vvfat: There an internal node is created, but it is not a filter
driver, but a weird protocol driver. It is used as the backing file of
the "qcow" child node of a vvfat node, so not accessible when
following only bs->file and bs->backing edges
Kevin
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