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tests: Test polling in bdrv_drop_intermediate()

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Signed-off-by: Max Reitz <mreitz@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
This commit is contained in:
Max Reitz 2019-07-22 15:33:45 +02:00 committed by Kevin Wolf
parent debc292767
commit 9746b35cf3
1 changed files with 167 additions and 0 deletions
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167
tests/test-bdrv-drain.c
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@ -100,6 +100,13 @@ static void bdrv_test_child_perm(BlockDriverState *bs, BdrvChild *c,
nperm, nshared);
}
static int bdrv_test_change_backing_file(BlockDriverState *bs,
const char *backing_file,
const char *backing_fmt)
{
return 0;
}
static BlockDriver bdrv_test = {
.format_name = "test",
.instance_size = sizeof(BDRVTestState),
@ -111,6 +118,8 @@ static BlockDriver bdrv_test = {
.bdrv_co_drain_end = bdrv_test_co_drain_end,
.bdrv_child_perm = bdrv_test_child_perm,
.bdrv_change_backing_file = bdrv_test_change_backing_file,
};
static void aio_ret_cb(void *opaque, int ret)
@ -1671,6 +1680,161 @@ static void test_blockjob_commit_by_drained_end(void)
bdrv_unref(bs_child);
}
typedef struct TestSimpleBlockJob {
BlockJob common;
bool should_complete;
bool *did_complete;
} TestSimpleBlockJob;
static int coroutine_fn test_simple_job_run(Job *job, Error **errp)
{
TestSimpleBlockJob *s = container_of(job, TestSimpleBlockJob, common.job);
while (!s->should_complete) {
job_sleep_ns(job, 0);
}
return 0;
}
static void test_simple_job_clean(Job *job)
{
TestSimpleBlockJob *s = container_of(job, TestSimpleBlockJob, common.job);
*s->did_complete = true;
}
static const BlockJobDriver test_simple_job_driver = {
.job_driver = {
.instance_size = sizeof(TestSimpleBlockJob),
.free = block_job_free,
.user_resume = block_job_user_resume,
.drain = block_job_drain,
.run = test_simple_job_run,
.clean = test_simple_job_clean,
},
};
static int drop_intermediate_poll_update_filename(BdrvChild *child,
BlockDriverState *new_base,
const char *filename,
Error **errp)
{
/*
* We are free to poll here, which may change the block graph, if
* it is not drained.
*/
/* If the job is not drained: Complete it, schedule job_exit() */
aio_poll(qemu_get_current_aio_context(), false);
/* If the job is not drained: Run job_exit(), finish the job */
aio_poll(qemu_get_current_aio_context(), false);
return 0;
}
/**
* Test a poll in the midst of bdrv_drop_intermediate().
*
* bdrv_drop_intermediate() calls BdrvChildRole.update_filename(),
* which can yield or poll. This may lead to graph changes, unless
* the whole subtree in question is drained.
*
* We test this on the following graph:
*
* Job
*
* |
* job-node
* |
* v
*
* job-node
*
* |
* backing
* |
* v
*
* node-2 --chain--> node-1 --chain--> node-0
*
* We drop node-1 with bdrv_drop_intermediate(top=node-1, base=node-0).
*
* This first updates node-2's backing filename by invoking
* drop_intermediate_poll_update_filename(), which polls twice. This
* causes the job to finish, which in turns causes the job-node to be
* deleted.
*
* bdrv_drop_intermediate() uses a QLIST_FOREACH_SAFE() loop, so it
* already has a pointer to the BdrvChild edge between job-node and
* node-1. When it tries to handle that edge, we probably get a
* segmentation fault because the object no longer exists.
*
*
* The solution is for bdrv_drop_intermediate() to drain top's
* subtree. This prevents graph changes from happening just because
* BdrvChildRole.update_filename() yields or polls. Thus, the block
* job is paused during that drained section and must finish before or
* after.
*
* (In addition, bdrv_replace_child() must keep the job paused.)
*/
static void test_drop_intermediate_poll(void)
{
static BdrvChildRole chain_child_role;
BlockDriverState *chain[3];
TestSimpleBlockJob *job;
BlockDriverState *job_node;
bool job_has_completed = false;
int i;
int ret;
chain_child_role = child_backing;
chain_child_role.update_filename = drop_intermediate_poll_update_filename;
for (i = 0; i < 3; i++) {
char name[32];
snprintf(name, 32, "node-%i", i);
chain[i] = bdrv_new_open_driver(&bdrv_test, name, 0, &error_abort);
}
job_node = bdrv_new_open_driver(&bdrv_test, "job-node", BDRV_O_RDWR,
&error_abort);
bdrv_set_backing_hd(job_node, chain[1], &error_abort);
/*
* Establish the chain last, so the chain links are the first
* elements in the BDS.parents lists
*/
for (i = 0; i < 3; i++) {
if (i) {
/* Takes the reference to chain[i - 1] */
chain[i]->backing = bdrv_attach_child(chain[i], chain[i - 1],
"chain", &chain_child_role,
&error_abort);
}
}
job = block_job_create("job", &test_simple_job_driver, NULL, job_node,
0, BLK_PERM_ALL, 0, 0, NULL, NULL, &error_abort);
/* The job has a reference now */
bdrv_unref(job_node);
job->did_complete = &job_has_completed;
job_start(&job->common.job);
job->should_complete = true;
g_assert(!job_has_completed);
ret = bdrv_drop_intermediate(chain[1], chain[0], NULL);
g_assert(ret == 0);
g_assert(job_has_completed);
bdrv_unref(chain[2]);
}
int main(int argc, char **argv)
{
int ret;
@ -1757,6 +1921,9 @@ int main(int argc, char **argv)
g_test_add_func("/bdrv-drain/blockjob/commit_by_drained_end",
test_blockjob_commit_by_drained_end);
g_test_add_func("/bdrv-drain/bdrv_drop_intermediate/poll",
test_drop_intermediate_poll);
ret = g_test_run();
qemu_event_destroy(&done_event);
return ret;