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