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Re: [PATCH v7 4/4] block: apply COR-filter to block-stream jobs
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From: |
Vladimir Sementsov-Ogievskiy |
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Subject: |
Re: [PATCH v7 4/4] block: apply COR-filter to block-stream jobs |
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Date: |
Mon, 24 Aug 2020 14:30:00 +0300 |
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User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.11.0 |
24.08.2020 11:31, Andrey Shinkevich wrote:
This patch completes the series with the COR-filter insertion for
block-stream operations. Adding the filter makes it possible for copied
regions to be discarded in backing files during the block-stream job,
what will reduce the disk overuse.
The COR-filter insertion incurs changes in the iotests case
245:test_block_stream_4 that reopens the backing chain during a
block-stream job. There are changes in the iotests #030 as well.
The iotests case 030:test_stream_parallel was deleted due to multiple
conflicts between the concurrent job operations over the same backing
chain. The base backing node for one job is the top node for another
job. It may change due to the filter node inserted into the backing
chain while both jobs are running. Another issue is that the parts of
the backing chain are being frozen by the running job and may not be
changed by the concurrent job when needed. The concept of the parallel
jobs with common nodes is considered vital no more.
Signed-off-by: Andrey Shinkevich <andrey.shinkevich@virtuozzo.com>
---
block/stream.c | 58 +++++++++++++++++++++++++++++++++++-----------
tests/qemu-iotests/030 | 50 ++++-----------------------------------
tests/qemu-iotests/030.out | 4 ++--
tests/qemu-iotests/245 | 19 +++++++++++----
4 files changed, 65 insertions(+), 66 deletions(-)
diff --git a/block/stream.c b/block/stream.c
index 8bf6b6d..e927fed 100644
--- a/block/stream.c
+++ b/block/stream.c
@@ -19,6 +19,7 @@
#include "qapi/qmp/qerror.h"
#include "qemu/ratelimit.h"
#include "sysemu/block-backend.h"
+#include "block/copy-on-read.h"
enum {
/*
@@ -33,6 +34,8 @@ typedef struct StreamBlockJob {
BlockJob common;
BlockDriverState *base_overlay; /* COW overlay (stream from this) */
BlockDriverState *above_base; /* Node directly above the base */
+ BlockDriverState *cor_filter_bs;
+ BlockDriverState *target_bs;
BlockdevOnError on_error;
char *backing_file_str;
bool bs_read_only;
@@ -53,22 +56,20 @@ static void stream_abort(Job *job)
StreamBlockJob *s = container_of(job, StreamBlockJob, common.job);
if (s->chain_frozen) {
- BlockJob *bjob = &s->common;
- bdrv_unfreeze_backing_chain(blk_bs(bjob->blk), s->above_base);
+ bdrv_unfreeze_backing_chain(s->cor_filter_bs, s->above_base);
}
}
static int stream_prepare(Job *job)
{
StreamBlockJob *s = container_of(job, StreamBlockJob, common.job);
- BlockJob *bjob = &s->common;
- BlockDriverState *bs = blk_bs(bjob->blk);
+ BlockDriverState *bs = s->target_bs;
BlockDriverState *unfiltered_bs = bdrv_skip_filters(bs);
variable bs is used only here, we can directly use s->target_bs instead
BlockDriverState *base = bdrv_filter_or_cow_bs(s->above_base);
Error *local_err = NULL;
int ret = 0;
- bdrv_unfreeze_backing_chain(bs, s->above_base);
+ bdrv_unfreeze_backing_chain(s->cor_filter_bs, s->above_base);
s->chain_frozen = false;
if (bdrv_cow_child(unfiltered_bs)) {
@@ -94,7 +95,9 @@ static void stream_clean(Job *job)
{
StreamBlockJob *s = container_of(job, StreamBlockJob, common.job);
BlockJob *bjob = &s->common;
- BlockDriverState *bs = blk_bs(bjob->blk);
+ BlockDriverState *bs = s->target_bs;
Here as well, I'd drop extra local bs variable
+
+ bdrv_cor_filter_drop(s->cor_filter_bs);
/* Reopen the image back in read-only mode if necessary */
if (s->bs_read_only) {
@@ -110,7 +113,7 @@ static int coroutine_fn stream_run(Job *job, Error **errp)
{
StreamBlockJob *s = container_of(job, StreamBlockJob, common.job);
BlockBackend *blk = s->common.blk;
- BlockDriverState *bs = blk_bs(blk);
+ BlockDriverState *bs = s->target_bs;
Now we have both bdrv_enable_copy_on_read(bs) and cor-filter, which doesn't seem correct.
Also, we'll need "base" parameter for cor filter to not copy-on-read extra
chunks.
BlockDriverState *unfiltered_bs = bdrv_skip_filters(bs);
bool enable_cor = !bdrv_cow_child(s->base_overlay);
int64_t len;
@@ -231,6 +234,7 @@ void stream_start(const char *job_id, BlockDriverState *bs,
int basic_flags = BLK_PERM_CONSISTENT_READ | BLK_PERM_WRITE_UNCHANGED;
BlockDriverState *base_overlay = bdrv_find_overlay(bs, base);
BlockDriverState *above_base;
+ BlockDriverState *cor_filter_bs = NULL;
if (!base_overlay) {
error_setg(errp, "'%s' is not in the backing chain of '%s'",
@@ -264,17 +268,36 @@ void stream_start(const char *job_id, BlockDriverState
*bs,
}
}
- /* Prevent concurrent jobs trying to modify the graph structure here, we
- * already have our own plans. Also don't allow resize as the image size is
- * queried only at the job start and then cached. */
- s = block_job_create(job_id, &stream_job_driver, NULL, bs,
- basic_flags | BLK_PERM_GRAPH_MOD,
- basic_flags | BLK_PERM_WRITE,
+ cor_filter_bs = bdrv_cor_filter_append(bs, filter_node_name, errp);
+ if (cor_filter_bs == NULL) {
+ goto fail;
+ }
+
+ if (bdrv_freeze_backing_chain(cor_filter_bs, bs, errp) < 0) {
+ bdrv_cor_filter_drop(cor_filter_bs);
+ cor_filter_bs = NULL;
+ goto fail;
+ }
+
+ s = block_job_create(job_id, &stream_job_driver, NULL, cor_filter_bs,
+ BLK_PERM_CONSISTENT_READ,
+ basic_flags | BLK_PERM_WRITE | BLK_PERM_GRAPH_MOD,
speed, creation_flags, NULL, NULL, errp);
if (!s) {
goto fail;
}
+ /*
+ * Prevent concurrent jobs trying to modify the graph structure here, we
+ * already have our own plans. Also don't allow resize as the image size is
+ * queried only at the job start and then cached.
+ */
+ if (block_job_add_bdrv(&s->common, "active node", bs,
+ basic_flags | BLK_PERM_GRAPH_MOD,
+ basic_flags | BLK_PERM_WRITE, &error_abort)) {
+ goto fail;
+ }
+
/* Block all intermediate nodes between bs and base, because they will
* disappear from the chain after this operation. The streaming job reads
* every block only once, assuming that it doesn't change, so forbid
writes
@@ -294,6 +317,8 @@ void stream_start(const char *job_id, BlockDriverState *bs,
s->base_overlay = base_overlay;
s->above_base = above_base;
+ s->cor_filter_bs = cor_filter_bs;
+ s->target_bs = bs;
s->backing_file_str = g_strdup(backing_file_str);
s->bs_read_only = bs_read_only;
s->chain_frozen = true;
@@ -307,5 +332,10 @@ fail:
if (bs_read_only) {
bdrv_reopen_set_read_only(bs, true, NULL);
}
- bdrv_unfreeze_backing_chain(bs, above_base);
+ if (cor_filter_bs) {
+ bdrv_unfreeze_backing_chain(cor_filter_bs, above_base);
+ bdrv_cor_filter_drop(cor_filter_bs);
+ } else {
+ bdrv_unfreeze_backing_chain(bs, above_base);
as I see, in this case chain is not yet frozen
+ }
}
diff --git a/tests/qemu-iotests/030 b/tests/qemu-iotests/030
index 1cdd7e2..fec9d89 100755
--- a/tests/qemu-iotests/030
+++ b/tests/qemu-iotests/030
@@ -221,60 +221,20 @@ class TestParallelOps(iotests.QMPTestCase):
for img in self.imgs:
os.remove(img)
- # Test that it's possible to run several block-stream operations
- # in parallel in the same snapshot chain
- def test_stream_parallel(self):
- self.assert_no_active_block_jobs()
-
- # Check that the maps don't match before the streaming operations
- for i in range(2, self.num_imgs, 2):
- self.assertNotEqual(qemu_io('-f', iotests.imgfmt, '-rU', '-c',
'map', self.imgs[i]),
- qemu_io('-f', iotests.imgfmt, '-rU', '-c',
'map', self.imgs[i-1]),
- 'image file map matches backing file before
streaming')
-
- # Create all streaming jobs
- pending_jobs = []
- for i in range(2, self.num_imgs, 2):
- node_name = 'node%d' % i
- job_id = 'stream-%s' % node_name
- pending_jobs.append(job_id)
- result = self.vm.qmp('block-stream', device=node_name,
job_id=job_id, base=self.imgs[i-2], speed=512*1024)
- self.assert_qmp(result, 'return', {})
-
- for job in pending_jobs:
- result = self.vm.qmp('block-job-set-speed', device=job, speed=0)
- self.assert_qmp(result, 'return', {})
-
- # Wait for all jobs to be finished.
- while len(pending_jobs) > 0:
- for event in self.vm.get_qmp_events(wait=True):
- if event['event'] == 'BLOCK_JOB_COMPLETED':
- job_id = self.dictpath(event, 'data/device')
- self.assertTrue(job_id in pending_jobs)
- self.assert_qmp_absent(event, 'data/error')
- pending_jobs.remove(job_id)
-
- self.assert_no_active_block_jobs()
- self.vm.shutdown()
-
- # Check that all maps match now
- for i in range(2, self.num_imgs, 2):
- self.assertEqual(qemu_io('-f', iotests.imgfmt, '-c', 'map',
self.imgs[i]),
- qemu_io('-f', iotests.imgfmt, '-c', 'map',
self.imgs[i-1]),
- 'image file map does not match backing file after
streaming')
-
# Test that it's not possible to perform two block-stream
# operations if there are nodes involved in both.
def test_overlapping_1(self):
self.assert_no_active_block_jobs()
# Set a speed limit to make sure that this job blocks the rest
- result = self.vm.qmp('block-stream', device='node4',
job_id='stream-node4', base=self.imgs[1], speed=1024*1024)
+ result = self.vm.qmp('block-stream', device='node4',
+ job_id='stream-node4', base=self.imgs[1],
+ filter_node_name='stream-filter', speed=1024*1024)
self.assert_qmp(result, 'return', {})
result = self.vm.qmp('block-stream', device='node5', job_id='stream-node5', base=self.imgs[2])
self.assert_qmp(result, 'error/desc',
- "Node 'node4' is busy: block device is in use by block job:
stream")
+ "Node 'stream-filter' is busy: block device is in use by block job:
stream")
result = self.vm.qmp('block-stream', device='node3', job_id='stream-node3', base=self.imgs[2])
self.assert_qmp(result, 'error/desc',
@@ -287,7 +247,7 @@ class TestParallelOps(iotests.QMPTestCase):
# block-commit should also fail if it touches nodes used by the
stream job
result = self.vm.qmp('block-commit', device='drive0',
base=self.imgs[4], job_id='commit-node4')
self.assert_qmp(result, 'error/desc',
- "Node 'node4' is busy: block device is in use by block job:
stream")
+ "Node 'stream-filter' is busy: block device is in use by block job:
stream")
result = self.vm.qmp('block-commit', device='drive0', base=self.imgs[1], top=self.imgs[3], job_id='commit-node1')
self.assert_qmp(result, 'error/desc',
diff --git a/tests/qemu-iotests/030.out b/tests/qemu-iotests/030.out
index 6d9bee1..5eb508d 100644
--- a/tests/qemu-iotests/030.out
+++ b/tests/qemu-iotests/030.out
@@ -1,5 +1,5 @@
-...........................
+..........................
----------------------------------------------------------------------
-Ran 27 tests
+Ran 26 tests
OK
diff --git a/tests/qemu-iotests/245 b/tests/qemu-iotests/245
index 5035763..6c262a0 100755
--- a/tests/qemu-iotests/245
+++ b/tests/qemu-iotests/245
@@ -898,17 +898,26 @@ class TestBlockdevReopen(iotests.QMPTestCase):
# make hd1 read-only and block-stream requires it to be read-write
# (Which error message appears depends on whether the stream job is
# already done with copying at this point.)
- self.reopen(opts, {},
+ # As the COR-filter node is inserted into the backing chain with the
+ # 'block-stream' operation, we move the options to their proper nodes.
+ opts = hd_opts(1)
+ opts['backing'] = hd_opts(2)
+ opts['backing']['backing'] = None
+ self.reopen(opts, {'read-only': True},
["Can't set node 'hd1' to r/o with copy-on-read enabled",
"Cannot make block node read-only, there is a writer on it"])
# We can't remove hd2 while the stream job is ongoing
- opts['backing']['backing'] = None
- self.reopen(opts, {'backing.read-only': False}, "Cannot change 'backing'
link from 'hd1' to 'hd2'")
+ opts['backing'] = None
+ self.reopen(opts, {'read-only': False},
+ "Cannot change 'backing' link from 'hd1' to 'hd2'")
- # We can detach hd1 from hd0 because it doesn't affect the stream job
+ # We can't detach hd1 from hd0 because there is the COR-filter implicit
+ # node in between.
+ opts = hd_opts(0)
opts['backing'] = None
- self.reopen(opts)
+ self.reopen(opts, {},
+ "Cannot change backing link if 'hd0' has an implicit backing
file")
self.vm.run_job('stream0', auto_finalize = False, auto_dismiss = True)
--
Best regards,
Vladimir