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qemu/tests/unit/test-bdrv-drain.c
Kevin Wolf 617f3a9635 test-bdrv-drain: Fix incorrrect drain assumptions 
The test case assumes that a drain only happens in one specific place
where it drains explicitly. This assumption happened to hold true until
now, but block layer functions may drain interally (any graph
modifications are going to do that through bdrv_graph_wrlock()), so this
is incorrect. Make sure that the test code in .drained_begin only runs
where we actually want it to run.

When scheduling a BH from .drained_begin, we also need to increase the
in_flight counter to make sure that the operation is actually completed
in time before the node that it works on goes away.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Message-Id: <20221207131838.239125-10-kwolf@redhat.com>
Reviewed-by: Emanuele Giuseppe Esposito <eesposit@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2022-12-15 16:08:23 +01:00

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/*
* Block node draining tests
*
* Copyright (c) 2017 Kevin Wolf <kwolf@redhat.com>
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
* THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
* THE SOFTWARE.
*/
#include "qemu/osdep.h"
#include "block/block.h"
#include "block/blockjob_int.h"
#include "sysemu/block-backend.h"
#include "qapi/error.h"
#include "qemu/main-loop.h"
#include "iothread.h"
static QemuEvent done_event;
typedef struct BDRVTestState {
int drain_count;
AioContext *bh_indirection_ctx;
bool sleep_in_drain_begin;
} BDRVTestState;
static void coroutine_fn sleep_in_drain_begin(void *opaque)
{
BlockDriverState *bs = opaque;
qemu_co_sleep_ns(QEMU_CLOCK_REALTIME, 100000);
bdrv_dec_in_flight(bs);
}
static void bdrv_test_drain_begin(BlockDriverState *bs)
{
BDRVTestState *s = bs->opaque;
s->drain_count++;
if (s->sleep_in_drain_begin) {
Coroutine *co = qemu_coroutine_create(sleep_in_drain_begin, bs);
bdrv_inc_in_flight(bs);
aio_co_enter(bdrv_get_aio_context(bs), co);
}
}
static void bdrv_test_drain_end(BlockDriverState *bs)
{
BDRVTestState *s = bs->opaque;
s->drain_count--;
}
static void bdrv_test_close(BlockDriverState *bs)
{
BDRVTestState *s = bs->opaque;
g_assert_cmpint(s->drain_count, >, 0);
}
static void co_reenter_bh(void *opaque)
{
aio_co_wake(opaque);
}
static int coroutine_fn bdrv_test_co_preadv(BlockDriverState *bs,
int64_t offset, int64_t bytes,
QEMUIOVector *qiov,
BdrvRequestFlags flags)
{
BDRVTestState *s = bs->opaque;
/* We want this request to stay until the polling loop in drain waits for
* it to complete. We need to sleep a while as bdrv_drain_invoke() comes
* first and polls its result, too, but it shouldn't accidentally complete
* this request yet. */
qemu_co_sleep_ns(QEMU_CLOCK_REALTIME, 100000);
if (s->bh_indirection_ctx) {
aio_bh_schedule_oneshot(s->bh_indirection_ctx, co_reenter_bh,
qemu_coroutine_self());
qemu_coroutine_yield();
}
return 0;
}
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),
.supports_backing = true,
.bdrv_close = bdrv_test_close,
.bdrv_co_preadv = bdrv_test_co_preadv,
.bdrv_drain_begin = bdrv_test_drain_begin,
.bdrv_drain_end = bdrv_test_drain_end,
.bdrv_child_perm = bdrv_default_perms,
.bdrv_change_backing_file = bdrv_test_change_backing_file,
};
static void aio_ret_cb(void *opaque, int ret)
{
int *aio_ret = opaque;
*aio_ret = ret;
}
typedef struct CallInCoroutineData {
void (*entry)(void);
bool done;
} CallInCoroutineData;
static coroutine_fn void call_in_coroutine_entry(void *opaque)
{
CallInCoroutineData *data = opaque;
data->entry();
data->done = true;
}
static void call_in_coroutine(void (*entry)(void))
{
Coroutine *co;
CallInCoroutineData data = {
.entry = entry,
.done = false,
};
co = qemu_coroutine_create(call_in_coroutine_entry, &data);
qemu_coroutine_enter(co);
while (!data.done) {
aio_poll(qemu_get_aio_context(), true);
}
}
enum drain_type {
BDRV_DRAIN_ALL,
BDRV_DRAIN,
DRAIN_TYPE_MAX,
};
static void do_drain_begin(enum drain_type drain_type, BlockDriverState *bs)
{
switch (drain_type) {
case BDRV_DRAIN_ALL: bdrv_drain_all_begin(); break;
case BDRV_DRAIN: bdrv_drained_begin(bs); break;
default: g_assert_not_reached();
}
}
static void do_drain_end(enum drain_type drain_type, BlockDriverState *bs)
{
switch (drain_type) {
case BDRV_DRAIN_ALL: bdrv_drain_all_end(); break;
case BDRV_DRAIN: bdrv_drained_end(bs); break;
default: g_assert_not_reached();
}
}
static void do_drain_begin_unlocked(enum drain_type drain_type, BlockDriverState *bs)
{
if (drain_type != BDRV_DRAIN_ALL) {
aio_context_acquire(bdrv_get_aio_context(bs));
}
do_drain_begin(drain_type, bs);
if (drain_type != BDRV_DRAIN_ALL) {
aio_context_release(bdrv_get_aio_context(bs));
}
}
static void do_drain_end_unlocked(enum drain_type drain_type, BlockDriverState *bs)
{
if (drain_type != BDRV_DRAIN_ALL) {
aio_context_acquire(bdrv_get_aio_context(bs));
}
do_drain_end(drain_type, bs);
if (drain_type != BDRV_DRAIN_ALL) {
aio_context_release(bdrv_get_aio_context(bs));
}
}
static void test_drv_cb_common(enum drain_type drain_type, bool recursive)
{
BlockBackend *blk;
BlockDriverState *bs, *backing;
BDRVTestState *s, *backing_s;
BlockAIOCB *acb;
int aio_ret;
QEMUIOVector qiov = QEMU_IOVEC_INIT_BUF(qiov, NULL, 0);
blk = blk_new(qemu_get_aio_context(), BLK_PERM_ALL, BLK_PERM_ALL);
bs = bdrv_new_open_driver(&bdrv_test, "test-node", BDRV_O_RDWR,
&error_abort);
s = bs->opaque;
blk_insert_bs(blk, bs, &error_abort);
backing = bdrv_new_open_driver(&bdrv_test, "backing", 0, &error_abort);
backing_s = backing->opaque;
bdrv_set_backing_hd(bs, backing, &error_abort);
/* Simple bdrv_drain_all_begin/end pair, check that CBs are called */
g_assert_cmpint(s->drain_count, ==, 0);
g_assert_cmpint(backing_s->drain_count, ==, 0);
do_drain_begin(drain_type, bs);
g_assert_cmpint(s->drain_count, ==, 1);
g_assert_cmpint(backing_s->drain_count, ==, !!recursive);
do_drain_end(drain_type, bs);
g_assert_cmpint(s->drain_count, ==, 0);
g_assert_cmpint(backing_s->drain_count, ==, 0);
/* Now do the same while a request is pending */
aio_ret = -EINPROGRESS;
acb = blk_aio_preadv(blk, 0, &qiov, 0, aio_ret_cb, &aio_ret);
g_assert(acb != NULL);
g_assert_cmpint(aio_ret, ==, -EINPROGRESS);
g_assert_cmpint(s->drain_count, ==, 0);
g_assert_cmpint(backing_s->drain_count, ==, 0);
do_drain_begin(drain_type, bs);
g_assert_cmpint(aio_ret, ==, 0);
g_assert_cmpint(s->drain_count, ==, 1);
g_assert_cmpint(backing_s->drain_count, ==, !!recursive);
do_drain_end(drain_type, bs);
g_assert_cmpint(s->drain_count, ==, 0);
g_assert_cmpint(backing_s->drain_count, ==, 0);
bdrv_unref(backing);
bdrv_unref(bs);
blk_unref(blk);
}
static void test_drv_cb_drain_all(void)
{
test_drv_cb_common(BDRV_DRAIN_ALL, true);
}
static void test_drv_cb_drain(void)
{
test_drv_cb_common(BDRV_DRAIN, false);
}
static void test_drv_cb_co_drain_all(void)
{
call_in_coroutine(test_drv_cb_drain_all);
}
static void test_drv_cb_co_drain(void)
{
call_in_coroutine(test_drv_cb_drain);
}
static void test_quiesce_common(enum drain_type drain_type, bool recursive)
{
BlockBackend *blk;
BlockDriverState *bs, *backing;
blk = blk_new(qemu_get_aio_context(), BLK_PERM_ALL, BLK_PERM_ALL);
bs = bdrv_new_open_driver(&bdrv_test, "test-node", BDRV_O_RDWR,
&error_abort);
blk_insert_bs(blk, bs, &error_abort);
backing = bdrv_new_open_driver(&bdrv_test, "backing", 0, &error_abort);
bdrv_set_backing_hd(bs, backing, &error_abort);
g_assert_cmpint(bs->quiesce_counter, ==, 0);
g_assert_cmpint(backing->quiesce_counter, ==, 0);
do_drain_begin(drain_type, bs);
if (drain_type == BDRV_DRAIN_ALL) {
g_assert_cmpint(bs->quiesce_counter, ==, 2);
} else {
g_assert_cmpint(bs->quiesce_counter, ==, 1);
}
g_assert_cmpint(backing->quiesce_counter, ==, !!recursive);
do_drain_end(drain_type, bs);
g_assert_cmpint(bs->quiesce_counter, ==, 0);
g_assert_cmpint(backing->quiesce_counter, ==, 0);
bdrv_unref(backing);
bdrv_unref(bs);
blk_unref(blk);
}
static void test_quiesce_drain_all(void)
{
test_quiesce_common(BDRV_DRAIN_ALL, true);
}
static void test_quiesce_drain(void)
{
test_quiesce_common(BDRV_DRAIN, false);
}
static void test_quiesce_co_drain_all(void)
{
call_in_coroutine(test_quiesce_drain_all);
}
static void test_quiesce_co_drain(void)
{
call_in_coroutine(test_quiesce_drain);
}
static void test_nested(void)
{
BlockBackend *blk;
BlockDriverState *bs, *backing;
BDRVTestState *s, *backing_s;
enum drain_type outer, inner;
blk = blk_new(qemu_get_aio_context(), BLK_PERM_ALL, BLK_PERM_ALL);
bs = bdrv_new_open_driver(&bdrv_test, "test-node", BDRV_O_RDWR,
&error_abort);
s = bs->opaque;
blk_insert_bs(blk, bs, &error_abort);
backing = bdrv_new_open_driver(&bdrv_test, "backing", 0, &error_abort);
backing_s = backing->opaque;
bdrv_set_backing_hd(bs, backing, &error_abort);
for (outer = 0; outer < DRAIN_TYPE_MAX; outer++) {
for (inner = 0; inner < DRAIN_TYPE_MAX; inner++) {
int backing_quiesce = (outer == BDRV_DRAIN_ALL) +
(inner == BDRV_DRAIN_ALL);
g_assert_cmpint(bs->quiesce_counter, ==, 0);
g_assert_cmpint(backing->quiesce_counter, ==, 0);
g_assert_cmpint(s->drain_count, ==, 0);
g_assert_cmpint(backing_s->drain_count, ==, 0);
do_drain_begin(outer, bs);
do_drain_begin(inner, bs);
g_assert_cmpint(bs->quiesce_counter, ==, 2 + !!backing_quiesce);
g_assert_cmpint(backing->quiesce_counter, ==, backing_quiesce);
g_assert_cmpint(s->drain_count, ==, 1);
g_assert_cmpint(backing_s->drain_count, ==, !!backing_quiesce);
do_drain_end(inner, bs);
do_drain_end(outer, bs);
g_assert_cmpint(bs->quiesce_counter, ==, 0);
g_assert_cmpint(backing->quiesce_counter, ==, 0);
g_assert_cmpint(s->drain_count, ==, 0);
g_assert_cmpint(backing_s->drain_count, ==, 0);
}
}
bdrv_unref(backing);
bdrv_unref(bs);
blk_unref(blk);
}
static void test_graph_change_drain_all(void)
{
BlockBackend *blk_a, *blk_b;
BlockDriverState *bs_a, *bs_b;
BDRVTestState *a_s, *b_s;
/* Create node A with a BlockBackend */
blk_a = blk_new(qemu_get_aio_context(), BLK_PERM_ALL, BLK_PERM_ALL);
bs_a = bdrv_new_open_driver(&bdrv_test, "test-node-a", BDRV_O_RDWR,
&error_abort);
a_s = bs_a->opaque;
blk_insert_bs(blk_a, bs_a, &error_abort);
g_assert_cmpint(bs_a->quiesce_counter, ==, 0);
g_assert_cmpint(a_s->drain_count, ==, 0);
/* Call bdrv_drain_all_begin() */
bdrv_drain_all_begin();
g_assert_cmpint(bs_a->quiesce_counter, ==, 1);
g_assert_cmpint(a_s->drain_count, ==, 1);
/* Create node B with a BlockBackend */
blk_b = blk_new(qemu_get_aio_context(), BLK_PERM_ALL, BLK_PERM_ALL);
bs_b = bdrv_new_open_driver(&bdrv_test, "test-node-b", BDRV_O_RDWR,
&error_abort);
b_s = bs_b->opaque;
blk_insert_bs(blk_b, bs_b, &error_abort);
g_assert_cmpint(bs_a->quiesce_counter, ==, 1);
g_assert_cmpint(bs_b->quiesce_counter, ==, 1);
g_assert_cmpint(a_s->drain_count, ==, 1);
g_assert_cmpint(b_s->drain_count, ==, 1);
/* Unref and finally delete node A */
blk_unref(blk_a);
g_assert_cmpint(bs_a->quiesce_counter, ==, 1);
g_assert_cmpint(bs_b->quiesce_counter, ==, 1);
g_assert_cmpint(a_s->drain_count, ==, 1);
g_assert_cmpint(b_s->drain_count, ==, 1);
bdrv_unref(bs_a);
g_assert_cmpint(bs_b->quiesce_counter, ==, 1);
g_assert_cmpint(b_s->drain_count, ==, 1);
/* End the drained section */
bdrv_drain_all_end();
g_assert_cmpint(bs_b->quiesce_counter, ==, 0);
g_assert_cmpint(b_s->drain_count, ==, 0);
g_assert_cmpint(qemu_get_aio_context()->external_disable_cnt, ==, 0);
bdrv_unref(bs_b);
blk_unref(blk_b);
}
struct test_iothread_data {
BlockDriverState *bs;
enum drain_type drain_type;
int *aio_ret;
};
static void test_iothread_drain_entry(void *opaque)
{
struct test_iothread_data *data = opaque;
aio_context_acquire(bdrv_get_aio_context(data->bs));
do_drain_begin(data->drain_type, data->bs);
g_assert_cmpint(*data->aio_ret, ==, 0);
do_drain_end(data->drain_type, data->bs);
aio_context_release(bdrv_get_aio_context(data->bs));
qemu_event_set(&done_event);
}
static void test_iothread_aio_cb(void *opaque, int ret)
{
int *aio_ret = opaque;
*aio_ret = ret;
qemu_event_set(&done_event);
}
static void test_iothread_main_thread_bh(void *opaque)
{
struct test_iothread_data *data = opaque;
/* Test that the AioContext is not yet locked in a random BH that is
* executed during drain, otherwise this would deadlock. */
aio_context_acquire(bdrv_get_aio_context(data->bs));
bdrv_flush(data->bs);
aio_context_release(bdrv_get_aio_context(data->bs));
}
/*
* Starts an AIO request on a BDS that runs in the AioContext of iothread 1.
* The request involves a BH on iothread 2 before it can complete.
*
* @drain_thread = 0 means that do_drain_begin/end are called from the main
* thread, @drain_thread = 1 means that they are called from iothread 1. Drain
* for this BDS cannot be called from iothread 2 because only the main thread
* may do cross-AioContext polling.
*/
static void test_iothread_common(enum drain_type drain_type, int drain_thread)
{
BlockBackend *blk;
BlockDriverState *bs;
BDRVTestState *s;
BlockAIOCB *acb;
int aio_ret;
struct test_iothread_data data;
IOThread *a = iothread_new();
IOThread *b = iothread_new();
AioContext *ctx_a = iothread_get_aio_context(a);
AioContext *ctx_b = iothread_get_aio_context(b);
QEMUIOVector qiov = QEMU_IOVEC_INIT_BUF(qiov, NULL, 0);
/* bdrv_drain_all() may only be called from the main loop thread */
if (drain_type == BDRV_DRAIN_ALL && drain_thread != 0) {
goto out;
}
blk = blk_new(qemu_get_aio_context(), BLK_PERM_ALL, BLK_PERM_ALL);
bs = bdrv_new_open_driver(&bdrv_test, "test-node", BDRV_O_RDWR,
&error_abort);
s = bs->opaque;
blk_insert_bs(blk, bs, &error_abort);
blk_set_disable_request_queuing(blk, true);
blk_set_aio_context(blk, ctx_a, &error_abort);
aio_context_acquire(ctx_a);
s->bh_indirection_ctx = ctx_b;
aio_ret = -EINPROGRESS;
qemu_event_reset(&done_event);
if (drain_thread == 0) {
acb = blk_aio_preadv(blk, 0, &qiov, 0, test_iothread_aio_cb, &aio_ret);
} else {
acb = blk_aio_preadv(blk, 0, &qiov, 0, aio_ret_cb, &aio_ret);
}
g_assert(acb != NULL);
g_assert_cmpint(aio_ret, ==, -EINPROGRESS);
aio_context_release(ctx_a);
data = (struct test_iothread_data) {
.bs = bs,
.drain_type = drain_type,
.aio_ret = &aio_ret,
};
switch (drain_thread) {
case 0:
if (drain_type != BDRV_DRAIN_ALL) {
aio_context_acquire(ctx_a);
}
aio_bh_schedule_oneshot(ctx_a, test_iothread_main_thread_bh, &data);
/* The request is running on the IOThread a. Draining its block device
* will make sure that it has completed as far as the BDS is concerned,
* but the drain in this thread can continue immediately after
* bdrv_dec_in_flight() and aio_ret might be assigned only slightly
* later. */
do_drain_begin(drain_type, bs);
g_assert_cmpint(bs->in_flight, ==, 0);
if (drain_type != BDRV_DRAIN_ALL) {
aio_context_release(ctx_a);
}
qemu_event_wait(&done_event);
if (drain_type != BDRV_DRAIN_ALL) {
aio_context_acquire(ctx_a);
}
g_assert_cmpint(aio_ret, ==, 0);
do_drain_end(drain_type, bs);
if (drain_type != BDRV_DRAIN_ALL) {
aio_context_release(ctx_a);
}
break;
case 1:
aio_bh_schedule_oneshot(ctx_a, test_iothread_drain_entry, &data);
qemu_event_wait(&done_event);
break;
default:
g_assert_not_reached();
}
aio_context_acquire(ctx_a);
blk_set_aio_context(blk, qemu_get_aio_context(), &error_abort);
aio_context_release(ctx_a);
bdrv_unref(bs);
blk_unref(blk);
out:
iothread_join(a);
iothread_join(b);
}
static void test_iothread_drain_all(void)
{
test_iothread_common(BDRV_DRAIN_ALL, 0);
test_iothread_common(BDRV_DRAIN_ALL, 1);
}
static void test_iothread_drain(void)
{
test_iothread_common(BDRV_DRAIN, 0);
test_iothread_common(BDRV_DRAIN, 1);
}
typedef struct TestBlockJob {
BlockJob common;
BlockDriverState *bs;
int run_ret;
int prepare_ret;
bool running;
bool should_complete;
} TestBlockJob;
static int test_job_prepare(Job *job)
{
TestBlockJob *s = container_of(job, TestBlockJob, common.job);
/* Provoke an AIO_WAIT_WHILE() call to verify there is no deadlock */
bdrv_flush(s->bs);
return s->prepare_ret;
}
static void test_job_commit(Job *job)
{
TestBlockJob *s = container_of(job, TestBlockJob, common.job);
/* Provoke an AIO_WAIT_WHILE() call to verify there is no deadlock */
bdrv_flush(s->bs);
}
static void test_job_abort(Job *job)
{
TestBlockJob *s = container_of(job, TestBlockJob, common.job);
/* Provoke an AIO_WAIT_WHILE() call to verify there is no deadlock */
bdrv_flush(s->bs);
}
static int coroutine_fn test_job_run(Job *job, Error **errp)
{
TestBlockJob *s = container_of(job, TestBlockJob, common.job);
/* We are running the actual job code past the pause point in
* job_co_entry(). */
s->running = true;
job_transition_to_ready(&s->common.job);
while (!s->should_complete) {
/* Avoid job_sleep_ns() because it marks the job as !busy. We want to
* emulate some actual activity (probably some I/O) here so that drain
* has to wait for this activity to stop. */
qemu_co_sleep_ns(QEMU_CLOCK_REALTIME, 1000000);
job_pause_point(&s->common.job);
}
return s->run_ret;
}
static void test_job_complete(Job *job, Error **errp)
{
TestBlockJob *s = container_of(job, TestBlockJob, common.job);
s->should_complete = true;
}
BlockJobDriver test_job_driver = {
.job_driver = {
.instance_size = sizeof(TestBlockJob),
.free = block_job_free,
.user_resume = block_job_user_resume,
.run = test_job_run,
.complete = test_job_complete,
.prepare = test_job_prepare,
.commit = test_job_commit,
.abort = test_job_abort,
},
};
enum test_job_result {
TEST_JOB_SUCCESS,
TEST_JOB_FAIL_RUN,
TEST_JOB_FAIL_PREPARE,
};
enum test_job_drain_node {
TEST_JOB_DRAIN_SRC,
TEST_JOB_DRAIN_SRC_CHILD,
};
static void test_blockjob_common_drain_node(enum drain_type drain_type,
bool use_iothread,
enum test_job_result result,
enum test_job_drain_node drain_node)
{
BlockBackend *blk_src, *blk_target;
BlockDriverState *src, *src_backing, *src_overlay, *target, *drain_bs;
BlockJob *job;
TestBlockJob *tjob;
IOThread *iothread = NULL;
AioContext *ctx;
int ret;
src = bdrv_new_open_driver(&bdrv_test, "source", BDRV_O_RDWR,
&error_abort);
src_backing = bdrv_new_open_driver(&bdrv_test, "source-backing",
BDRV_O_RDWR, &error_abort);
src_overlay = bdrv_new_open_driver(&bdrv_test, "source-overlay",
BDRV_O_RDWR, &error_abort);
bdrv_set_backing_hd(src_overlay, src, &error_abort);
bdrv_unref(src);
bdrv_set_backing_hd(src, src_backing, &error_abort);
bdrv_unref(src_backing);
blk_src = blk_new(qemu_get_aio_context(), BLK_PERM_ALL, BLK_PERM_ALL);
blk_insert_bs(blk_src, src_overlay, &error_abort);
switch (drain_node) {
case TEST_JOB_DRAIN_SRC:
drain_bs = src;
break;
case TEST_JOB_DRAIN_SRC_CHILD:
drain_bs = src_backing;
break;
default:
g_assert_not_reached();
}
if (use_iothread) {
iothread = iothread_new();
ctx = iothread_get_aio_context(iothread);
blk_set_aio_context(blk_src, ctx, &error_abort);
} else {
ctx = qemu_get_aio_context();
}
target = bdrv_new_open_driver(&bdrv_test, "target", BDRV_O_RDWR,
&error_abort);
blk_target = blk_new(qemu_get_aio_context(), BLK_PERM_ALL, BLK_PERM_ALL);
blk_insert_bs(blk_target, target, &error_abort);
blk_set_allow_aio_context_change(blk_target, true);
aio_context_acquire(ctx);
tjob = block_job_create("job0", &test_job_driver, NULL, src,
0, BLK_PERM_ALL,
0, 0, NULL, NULL, &error_abort);
tjob->bs = src;
job = &tjob->common;
block_job_add_bdrv(job, "target", target, 0, BLK_PERM_ALL, &error_abort);
switch (result) {
case TEST_JOB_SUCCESS:
break;
case TEST_JOB_FAIL_RUN:
tjob->run_ret = -EIO;
break;
case TEST_JOB_FAIL_PREPARE:
tjob->prepare_ret = -EIO;
break;
}
aio_context_release(ctx);
job_start(&job->job);
if (use_iothread) {
/* job_co_entry() is run in the I/O thread, wait for the actual job
* code to start (we don't want to catch the job in the pause point in
* job_co_entry(). */
while (!tjob->running) {
aio_poll(qemu_get_aio_context(), false);
}
}
WITH_JOB_LOCK_GUARD() {
g_assert_cmpint(job->job.pause_count, ==, 0);
g_assert_false(job->job.paused);
g_assert_true(tjob->running);
g_assert_true(job->job.busy); /* We're in qemu_co_sleep_ns() */
}
do_drain_begin_unlocked(drain_type, drain_bs);
WITH_JOB_LOCK_GUARD() {
if (drain_type == BDRV_DRAIN_ALL) {
/* bdrv_drain_all() drains both src and target */
g_assert_cmpint(job->job.pause_count, ==, 2);
} else {
g_assert_cmpint(job->job.pause_count, ==, 1);
}
g_assert_true(job->job.paused);
g_assert_false(job->job.busy); /* The job is paused */
}
do_drain_end_unlocked(drain_type, drain_bs);
if (use_iothread) {
/*
* Here we are waiting for the paused status to change,
* so don't bother protecting the read every time.
*
* paused is reset in the I/O thread, wait for it
*/
while (job->job.paused) {
aio_poll(qemu_get_aio_context(), false);
}
}
WITH_JOB_LOCK_GUARD() {
g_assert_cmpint(job->job.pause_count, ==, 0);
g_assert_false(job->job.paused);
g_assert_true(job->job.busy); /* We're in qemu_co_sleep_ns() */
}
do_drain_begin_unlocked(drain_type, target);
WITH_JOB_LOCK_GUARD() {
if (drain_type == BDRV_DRAIN_ALL) {
/* bdrv_drain_all() drains both src and target */
g_assert_cmpint(job->job.pause_count, ==, 2);
} else {
g_assert_cmpint(job->job.pause_count, ==, 1);
}
g_assert_true(job->job.paused);
g_assert_false(job->job.busy); /* The job is paused */
}
do_drain_end_unlocked(drain_type, target);
if (use_iothread) {
/*
* Here we are waiting for the paused status to change,
* so don't bother protecting the read every time.
*
* paused is reset in the I/O thread, wait for it
*/
while (job->job.paused) {
aio_poll(qemu_get_aio_context(), false);
}
}
WITH_JOB_LOCK_GUARD() {
g_assert_cmpint(job->job.pause_count, ==, 0);
g_assert_false(job->job.paused);
g_assert_true(job->job.busy); /* We're in qemu_co_sleep_ns() */
}
WITH_JOB_LOCK_GUARD() {
ret = job_complete_sync_locked(&job->job, &error_abort);
}
g_assert_cmpint(ret, ==, (result == TEST_JOB_SUCCESS ? 0 : -EIO));
aio_context_acquire(ctx);
if (use_iothread) {
blk_set_aio_context(blk_src, qemu_get_aio_context(), &error_abort);
assert(blk_get_aio_context(blk_target) == qemu_get_aio_context());
}
aio_context_release(ctx);
blk_unref(blk_src);
blk_unref(blk_target);
bdrv_unref(src_overlay);
bdrv_unref(target);
if (iothread) {
iothread_join(iothread);
}
}
static void test_blockjob_common(enum drain_type drain_type, bool use_iothread,
enum test_job_result result)
{
test_blockjob_common_drain_node(drain_type, use_iothread, result,
TEST_JOB_DRAIN_SRC);
test_blockjob_common_drain_node(drain_type, use_iothread, result,
TEST_JOB_DRAIN_SRC_CHILD);
}
static void test_blockjob_drain_all(void)
{
test_blockjob_common(BDRV_DRAIN_ALL, false, TEST_JOB_SUCCESS);
}
static void test_blockjob_drain(void)
{
test_blockjob_common(BDRV_DRAIN, false, TEST_JOB_SUCCESS);
}
static void test_blockjob_error_drain_all(void)
{
test_blockjob_common(BDRV_DRAIN_ALL, false, TEST_JOB_FAIL_RUN);
test_blockjob_common(BDRV_DRAIN_ALL, false, TEST_JOB_FAIL_PREPARE);
}
static void test_blockjob_error_drain(void)
{
test_blockjob_common(BDRV_DRAIN, false, TEST_JOB_FAIL_RUN);
test_blockjob_common(BDRV_DRAIN, false, TEST_JOB_FAIL_PREPARE);
}
static void test_blockjob_iothread_drain_all(void)
{
test_blockjob_common(BDRV_DRAIN_ALL, true, TEST_JOB_SUCCESS);
}
static void test_blockjob_iothread_drain(void)
{
test_blockjob_common(BDRV_DRAIN, true, TEST_JOB_SUCCESS);
}
static void test_blockjob_iothread_error_drain_all(void)
{
test_blockjob_common(BDRV_DRAIN_ALL, true, TEST_JOB_FAIL_RUN);
test_blockjob_common(BDRV_DRAIN_ALL, true, TEST_JOB_FAIL_PREPARE);
}
static void test_blockjob_iothread_error_drain(void)
{
test_blockjob_common(BDRV_DRAIN, true, TEST_JOB_FAIL_RUN);
test_blockjob_common(BDRV_DRAIN, true, TEST_JOB_FAIL_PREPARE);
}
typedef struct BDRVTestTopState {
BdrvChild *wait_child;
} BDRVTestTopState;
static void bdrv_test_top_close(BlockDriverState *bs)
{
BdrvChild *c, *next_c;
QLIST_FOREACH_SAFE(c, &bs->children, next, next_c) {
bdrv_unref_child(bs, c);
}
}
static int coroutine_fn bdrv_test_top_co_preadv(BlockDriverState *bs,
int64_t offset, int64_t bytes,
QEMUIOVector *qiov,
BdrvRequestFlags flags)
{
BDRVTestTopState *tts = bs->opaque;
return bdrv_co_preadv(tts->wait_child, offset, bytes, qiov, flags);
}
static BlockDriver bdrv_test_top_driver = {
.format_name = "test_top_driver",
.instance_size = sizeof(BDRVTestTopState),
.bdrv_close = bdrv_test_top_close,
.bdrv_co_preadv = bdrv_test_top_co_preadv,
.bdrv_child_perm = bdrv_default_perms,
};
typedef struct TestCoDeleteByDrainData {
BlockBackend *blk;
bool detach_instead_of_delete;
bool done;
} TestCoDeleteByDrainData;
static void coroutine_fn test_co_delete_by_drain(void *opaque)
{
TestCoDeleteByDrainData *dbdd = opaque;
BlockBackend *blk = dbdd->blk;
BlockDriverState *bs = blk_bs(blk);
BDRVTestTopState *tts = bs->opaque;
void *buffer = g_malloc(65536);
QEMUIOVector qiov = QEMU_IOVEC_INIT_BUF(qiov, buffer, 65536);
/* Pretend some internal write operation from parent to child.
* Important: We have to read from the child, not from the parent!
* Draining works by first propagating it all up the tree to the
* root and then waiting for drainage from root to the leaves
* (protocol nodes). If we have a request waiting on the root,
* everything will be drained before we go back down the tree, but
* we do not want that. We want to be in the middle of draining
* when this following requests returns. */
bdrv_co_preadv(tts->wait_child, 0, 65536, &qiov, 0);
g_assert_cmpint(bs->refcnt, ==, 1);
if (!dbdd->detach_instead_of_delete) {
blk_unref(blk);
} else {
BdrvChild *c, *next_c;
QLIST_FOREACH_SAFE(c, &bs->children, next, next_c) {
bdrv_unref_child(bs, c);
}
}
dbdd->done = true;
g_free(buffer);
}
/**
* Test what happens when some BDS has some children, you drain one of
* them and this results in the BDS being deleted.
*
* If @detach_instead_of_delete is set, the BDS is not going to be
* deleted but will only detach all of its children.
*/
static void do_test_delete_by_drain(bool detach_instead_of_delete,
enum drain_type drain_type)
{
BlockBackend *blk;
BlockDriverState *bs, *child_bs, *null_bs;
BDRVTestTopState *tts;
TestCoDeleteByDrainData dbdd;
Coroutine *co;
bs = bdrv_new_open_driver(&bdrv_test_top_driver, "top", BDRV_O_RDWR,
&error_abort);
bs->total_sectors = 65536 >> BDRV_SECTOR_BITS;
tts = bs->opaque;
null_bs = bdrv_open("null-co://", NULL, NULL, BDRV_O_RDWR | BDRV_O_PROTOCOL,
&error_abort);
bdrv_attach_child(bs, null_bs, "null-child", &child_of_bds,
BDRV_CHILD_DATA, &error_abort);
/* This child will be the one to pass to requests through to, and
* it will stall until a drain occurs */
child_bs = bdrv_new_open_driver(&bdrv_test, "child", BDRV_O_RDWR,
&error_abort);
child_bs->total_sectors = 65536 >> BDRV_SECTOR_BITS;
/* Takes our reference to child_bs */
tts->wait_child = bdrv_attach_child(bs, child_bs, "wait-child",
&child_of_bds,
BDRV_CHILD_DATA | BDRV_CHILD_PRIMARY,
&error_abort);
/* This child is just there to be deleted
* (for detach_instead_of_delete == true) */
null_bs = bdrv_open("null-co://", NULL, NULL, BDRV_O_RDWR | BDRV_O_PROTOCOL,
&error_abort);
bdrv_attach_child(bs, null_bs, "null-child", &child_of_bds, BDRV_CHILD_DATA,
&error_abort);
blk = blk_new(qemu_get_aio_context(), BLK_PERM_ALL, BLK_PERM_ALL);
blk_insert_bs(blk, bs, &error_abort);
/* Referenced by blk now */
bdrv_unref(bs);
g_assert_cmpint(bs->refcnt, ==, 1);
g_assert_cmpint(child_bs->refcnt, ==, 1);
g_assert_cmpint(null_bs->refcnt, ==, 1);
dbdd = (TestCoDeleteByDrainData){
.blk = blk,
.detach_instead_of_delete = detach_instead_of_delete,
.done = false,
};
co = qemu_coroutine_create(test_co_delete_by_drain, &dbdd);
qemu_coroutine_enter(co);
/* Drain the child while the read operation is still pending.
* This should result in the operation finishing and
* test_co_delete_by_drain() resuming. Thus, @bs will be deleted
* and the coroutine will exit while this drain operation is still
* in progress. */
switch (drain_type) {
case BDRV_DRAIN:
bdrv_ref(child_bs);
bdrv_drain(child_bs);
bdrv_unref(child_bs);
break;
case BDRV_DRAIN_ALL:
bdrv_drain_all_begin();
bdrv_drain_all_end();
break;
default:
g_assert_not_reached();
}
while (!dbdd.done) {
aio_poll(qemu_get_aio_context(), true);
}
if (detach_instead_of_delete) {
/* Here, the reference has not passed over to the coroutine,
* so we have to delete the BB ourselves */
blk_unref(blk);
}
}
static void test_delete_by_drain(void)
{
do_test_delete_by_drain(false, BDRV_DRAIN);
}
static void test_detach_by_drain_all(void)
{
do_test_delete_by_drain(true, BDRV_DRAIN_ALL);
}
static void test_detach_by_drain(void)
{
do_test_delete_by_drain(true, BDRV_DRAIN);
}
struct detach_by_parent_data {
BlockDriverState *parent_b;
BdrvChild *child_b;
BlockDriverState *c;
BdrvChild *child_c;
bool by_parent_cb;
bool detach_on_drain;
};
static struct detach_by_parent_data detach_by_parent_data;
static void detach_indirect_bh(void *opaque)
{
struct detach_by_parent_data *data = opaque;
bdrv_dec_in_flight(data->child_b->bs);
bdrv_unref_child(data->parent_b, data->child_b);
bdrv_ref(data->c);
data->child_c = bdrv_attach_child(data->parent_b, data->c, "PB-C",
&child_of_bds, BDRV_CHILD_DATA,
&error_abort);
}
static void detach_by_parent_aio_cb(void *opaque, int ret)
{
struct detach_by_parent_data *data = &detach_by_parent_data;
g_assert_cmpint(ret, ==, 0);
if (data->by_parent_cb) {
bdrv_inc_in_flight(data->child_b->bs);
detach_indirect_bh(data);
}
}
static void detach_by_driver_cb_drained_begin(BdrvChild *child)
{
struct detach_by_parent_data *data = &detach_by_parent_data;
if (!data->detach_on_drain) {
return;
}
data->detach_on_drain = false;
bdrv_inc_in_flight(data->child_b->bs);
aio_bh_schedule_oneshot(qemu_get_current_aio_context(),
detach_indirect_bh, &detach_by_parent_data);
child_of_bds.drained_begin(child);
}
static BdrvChildClass detach_by_driver_cb_class;
/*
* Initial graph:
*
* PA PB
* \ / \
* A B C
*
* by_parent_cb == true: Test that parent callbacks don't poll
*
* PA has a pending write request whose callback changes the child nodes of
* PB: It removes B and adds C instead. The subtree of PB is drained, which
* will indirectly drain the write request, too.
*
* by_parent_cb == false: Test that bdrv_drain_invoke() doesn't poll
*
* PA's BdrvChildClass has a .drained_begin callback that schedules a BH
* that does the same graph change. If bdrv_drain_invoke() calls it, the
* state is messed up, but if it is only polled in the single
* BDRV_POLL_WHILE() at the end of the drain, this should work fine.
*/
static void test_detach_indirect(bool by_parent_cb)
{
BlockBackend *blk;
BlockDriverState *parent_a, *parent_b, *a, *b, *c;
BdrvChild *child_a, *child_b;
BlockAIOCB *acb;
QEMUIOVector qiov = QEMU_IOVEC_INIT_BUF(qiov, NULL, 0);
if (!by_parent_cb) {
detach_by_driver_cb_class = child_of_bds;
detach_by_driver_cb_class.drained_begin =
detach_by_driver_cb_drained_begin;
detach_by_driver_cb_class.drained_end = NULL;
detach_by_driver_cb_class.drained_poll = NULL;
}
detach_by_parent_data = (struct detach_by_parent_data) {
.detach_on_drain = false,
};
/* Create all involved nodes */
parent_a = bdrv_new_open_driver(&bdrv_test, "parent-a", BDRV_O_RDWR,
&error_abort);
parent_b = bdrv_new_open_driver(&bdrv_test, "parent-b", 0,
&error_abort);
a = bdrv_new_open_driver(&bdrv_test, "a", BDRV_O_RDWR, &error_abort);
b = bdrv_new_open_driver(&bdrv_test, "b", BDRV_O_RDWR, &error_abort);
c = bdrv_new_open_driver(&bdrv_test, "c", BDRV_O_RDWR, &error_abort);
/* blk is a BB for parent-a */
blk = blk_new(qemu_get_aio_context(), BLK_PERM_ALL, BLK_PERM_ALL);
blk_insert_bs(blk, parent_a, &error_abort);
bdrv_unref(parent_a);
/* If we want to get bdrv_drain_invoke() to call aio_poll(), the driver
* callback must not return immediately. */
if (!by_parent_cb) {
BDRVTestState *s = parent_a->opaque;
s->sleep_in_drain_begin = true;
}
/* Set child relationships */
bdrv_ref(b);
bdrv_ref(a);
child_b = bdrv_attach_child(parent_b, b, "PB-B", &child_of_bds,
BDRV_CHILD_DATA, &error_abort);
child_a = bdrv_attach_child(parent_b, a, "PB-A", &child_of_bds,
BDRV_CHILD_COW, &error_abort);
bdrv_ref(a);
bdrv_attach_child(parent_a, a, "PA-A",
by_parent_cb ? &child_of_bds : &detach_by_driver_cb_class,
BDRV_CHILD_DATA, &error_abort);
g_assert_cmpint(parent_a->refcnt, ==, 1);
g_assert_cmpint(parent_b->refcnt, ==, 1);
g_assert_cmpint(a->refcnt, ==, 3);
g_assert_cmpint(b->refcnt, ==, 2);
g_assert_cmpint(c->refcnt, ==, 1);
g_assert(QLIST_FIRST(&parent_b->children) == child_a);
g_assert(QLIST_NEXT(child_a, next) == child_b);
g_assert(QLIST_NEXT(child_b, next) == NULL);
/* Start the evil write request */
detach_by_parent_data = (struct detach_by_parent_data) {
.parent_b = parent_b,
.child_b = child_b,
.c = c,
.by_parent_cb = by_parent_cb,
.detach_on_drain = true,
};
acb = blk_aio_preadv(blk, 0, &qiov, 0, detach_by_parent_aio_cb, NULL);
g_assert(acb != NULL);
/* Drain and check the expected result */
bdrv_drained_begin(parent_b);
bdrv_drained_begin(a);
bdrv_drained_begin(b);
bdrv_drained_begin(c);
g_assert(detach_by_parent_data.child_c != NULL);
g_assert_cmpint(parent_a->refcnt, ==, 1);
g_assert_cmpint(parent_b->refcnt, ==, 1);
g_assert_cmpint(a->refcnt, ==, 3);
g_assert_cmpint(b->refcnt, ==, 1);
g_assert_cmpint(c->refcnt, ==, 2);
g_assert(QLIST_FIRST(&parent_b->children) == detach_by_parent_data.child_c);
g_assert(QLIST_NEXT(detach_by_parent_data.child_c, next) == child_a);
g_assert(QLIST_NEXT(child_a, next) == NULL);
g_assert_cmpint(parent_a->quiesce_counter, ==, 1);
g_assert_cmpint(parent_b->quiesce_counter, ==, 3);
g_assert_cmpint(a->quiesce_counter, ==, 1);
g_assert_cmpint(b->quiesce_counter, ==, 1);
g_assert_cmpint(c->quiesce_counter, ==, 1);
bdrv_drained_end(parent_b);
bdrv_drained_end(a);
bdrv_drained_end(b);
bdrv_drained_end(c);
bdrv_unref(parent_b);
blk_unref(blk);
g_assert_cmpint(a->refcnt, ==, 1);
g_assert_cmpint(b->refcnt, ==, 1);
g_assert_cmpint(c->refcnt, ==, 1);
bdrv_unref(a);
bdrv_unref(b);
bdrv_unref(c);
}
static void test_detach_by_parent_cb(void)
{
test_detach_indirect(true);
}
static void test_detach_by_driver_cb(void)
{
test_detach_indirect(false);
}
static void test_append_to_drained(void)
{
BlockBackend *blk;
BlockDriverState *base, *overlay;
BDRVTestState *base_s, *overlay_s;
blk = blk_new(qemu_get_aio_context(), BLK_PERM_ALL, BLK_PERM_ALL);
base = bdrv_new_open_driver(&bdrv_test, "base", BDRV_O_RDWR, &error_abort);
base_s = base->opaque;
blk_insert_bs(blk, base, &error_abort);
overlay = bdrv_new_open_driver(&bdrv_test, "overlay", BDRV_O_RDWR,
&error_abort);
overlay_s = overlay->opaque;
do_drain_begin(BDRV_DRAIN, base);
g_assert_cmpint(base->quiesce_counter, ==, 1);
g_assert_cmpint(base_s->drain_count, ==, 1);
g_assert_cmpint(base->in_flight, ==, 0);
bdrv_append(overlay, base, &error_abort);
g_assert_cmpint(base->in_flight, ==, 0);
g_assert_cmpint(overlay->in_flight, ==, 0);
g_assert_cmpint(base->quiesce_counter, ==, 1);
g_assert_cmpint(base_s->drain_count, ==, 1);
g_assert_cmpint(overlay->quiesce_counter, ==, 1);
g_assert_cmpint(overlay_s->drain_count, ==, 1);
do_drain_end(BDRV_DRAIN, base);
g_assert_cmpint(base->quiesce_counter, ==, 0);
g_assert_cmpint(base_s->drain_count, ==, 0);
g_assert_cmpint(overlay->quiesce_counter, ==, 0);
g_assert_cmpint(overlay_s->drain_count, ==, 0);
bdrv_unref(overlay);
bdrv_unref(base);
blk_unref(blk);
}
static void test_set_aio_context(void)
{
BlockDriverState *bs;
IOThread *a = iothread_new();
IOThread *b = iothread_new();
AioContext *ctx_a = iothread_get_aio_context(a);
AioContext *ctx_b = iothread_get_aio_context(b);
bs = bdrv_new_open_driver(&bdrv_test, "test-node", BDRV_O_RDWR,
&error_abort);
bdrv_drained_begin(bs);
bdrv_try_change_aio_context(bs, ctx_a, NULL, &error_abort);
aio_context_acquire(ctx_a);
bdrv_drained_end(bs);
bdrv_drained_begin(bs);
bdrv_try_change_aio_context(bs, ctx_b, NULL, &error_abort);
aio_context_release(ctx_a);
aio_context_acquire(ctx_b);
bdrv_try_change_aio_context(bs, qemu_get_aio_context(), NULL, &error_abort);
aio_context_release(ctx_b);
bdrv_drained_end(bs);
bdrv_unref(bs);
iothread_join(a);
iothread_join(b);
}
typedef struct TestDropBackingBlockJob {
BlockJob common;
bool should_complete;
bool *did_complete;
BlockDriverState *detach_also;
BlockDriverState *bs;
} TestDropBackingBlockJob;
static int coroutine_fn test_drop_backing_job_run(Job *job, Error **errp)
{
TestDropBackingBlockJob *s =
container_of(job, TestDropBackingBlockJob, common.job);
while (!s->should_complete) {
job_sleep_ns(job, 0);
}
return 0;
}
static void test_drop_backing_job_commit(Job *job)
{
TestDropBackingBlockJob *s =
container_of(job, TestDropBackingBlockJob, common.job);
bdrv_set_backing_hd(s->bs, NULL, &error_abort);
bdrv_set_backing_hd(s->detach_also, NULL, &error_abort);
*s->did_complete = true;
}
static const BlockJobDriver test_drop_backing_job_driver = {
.job_driver = {
.instance_size = sizeof(TestDropBackingBlockJob),
.free = block_job_free,
.user_resume = block_job_user_resume,
.run = test_drop_backing_job_run,
.commit = test_drop_backing_job_commit,
}
};
/**
* Creates a child node with three parent nodes on it, and then runs a
* block job on the final one, parent-node-2.
*
* The job is then asked to complete before a section where the child
* is drained.
*
* Ending this section will undrain the child's parents, first
* parent-node-2, then parent-node-1, then parent-node-0 -- the parent
* list is in reverse order of how they were added. Ending the drain
* on parent-node-2 will resume the job, thus completing it and
* scheduling job_exit().
*
* Ending the drain on parent-node-1 will poll the AioContext, which
* lets job_exit() and thus test_drop_backing_job_commit() run. That
* function first removes the child as parent-node-2's backing file.
*
* In old (and buggy) implementations, there are two problems with
* that:
* (A) bdrv_drain_invoke() polls for every node that leaves the
* drained section. This means that job_exit() is scheduled
* before the child has left the drained section. Its
* quiesce_counter is therefore still 1 when it is removed from
* parent-node-2.
*
* (B) bdrv_replace_child_noperm() calls drained_end() on the old
* child's parents as many times as the child is quiesced. This
* means it will call drained_end() on parent-node-2 once.
* Because parent-node-2 is no longer quiesced at this point, this
* will fail.
*
* bdrv_replace_child_noperm() therefore must call drained_end() on
* the parent only if it really is still drained because the child is
* drained.
*
* If removing child from parent-node-2 was successful (as it should
* be), test_drop_backing_job_commit() will then also remove the child
* from parent-node-0.
*
* With an old version of our drain infrastructure ((A) above), that
* resulted in the following flow:
*
* 1. child attempts to leave its drained section. The call recurses
* to its parents.
*
* 2. parent-node-2 leaves the drained section. Polling in
* bdrv_drain_invoke() will schedule job_exit().
*
* 3. parent-node-1 leaves the drained section. Polling in
* bdrv_drain_invoke() will run job_exit(), thus disconnecting
* parent-node-0 from the child node.
*
* 4. bdrv_parent_drained_end() uses a QLIST_FOREACH_SAFE() loop to
* iterate over the parents. Thus, it now accesses the BdrvChild
* object that used to connect parent-node-0 and the child node.
* However, that object no longer exists, so it accesses a dangling
* pointer.
*
* The solution is to only poll once when running a bdrv_drained_end()
* operation, specifically at the end when all drained_end()
* operations for all involved nodes have been scheduled.
* Note that this also solves (A) above, thus hiding (B).
*/
static void test_blockjob_commit_by_drained_end(void)
{
BlockDriverState *bs_child, *bs_parents[3];
TestDropBackingBlockJob *job;
bool job_has_completed = false;
int i;
bs_child = bdrv_new_open_driver(&bdrv_test, "child-node", BDRV_O_RDWR,
&error_abort);
for (i = 0; i < 3; i++) {
char name[32];
snprintf(name, sizeof(name), "parent-node-%i", i);
bs_parents[i] = bdrv_new_open_driver(&bdrv_test, name, BDRV_O_RDWR,
&error_abort);
bdrv_set_backing_hd(bs_parents[i], bs_child, &error_abort);
}
job = block_job_create("job", &test_drop_backing_job_driver, NULL,
bs_parents[2], 0, BLK_PERM_ALL, 0, 0, NULL, NULL,
&error_abort);
job->bs = bs_parents[2];
job->detach_also = bs_parents[0];
job->did_complete = &job_has_completed;
job_start(&job->common.job);
job->should_complete = true;
bdrv_drained_begin(bs_child);
g_assert(!job_has_completed);
bdrv_drained_end(bs_child);
aio_poll(qemu_get_aio_context(), false);
g_assert(job_has_completed);
bdrv_unref(bs_parents[0]);
bdrv_unref(bs_parents[1]);
bdrv_unref(bs_parents[2]);
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,
.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 BdrvChildClass.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
* BdrvChildClass.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 BdrvChildClass chain_child_class;
BlockDriverState *chain[3];
TestSimpleBlockJob *job;
BlockDriverState *job_node;
bool job_has_completed = false;
int i;
int ret;
chain_child_class = child_of_bds;
chain_child_class.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] */
bdrv_attach_child(chain[i], chain[i - 1], "chain",
&chain_child_class, BDRV_CHILD_COW, &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);
aio_poll(qemu_get_aio_context(), false);
g_assert(ret == 0);
g_assert(job_has_completed);
bdrv_unref(chain[2]);
}
typedef struct BDRVReplaceTestState {
bool setup_completed;
bool was_drained;
bool was_undrained;
bool has_read;
int drain_count;
bool yield_before_read;
Coroutine *io_co;
Coroutine *drain_co;
} BDRVReplaceTestState;
static void bdrv_replace_test_close(BlockDriverState *bs)
{
}
/**
* If @bs has a backing file:
* Yield if .yield_before_read is true (and wait for drain_begin to
* wake us up).
* Forward the read to bs->backing. Set .has_read to true.
* If drain_begin has woken us, wake it in turn.
*
* Otherwise:
* Set .has_read to true and return success.
*/
static int coroutine_fn bdrv_replace_test_co_preadv(BlockDriverState *bs,
int64_t offset,
int64_t bytes,
QEMUIOVector *qiov,
BdrvRequestFlags flags)
{
BDRVReplaceTestState *s = bs->opaque;
if (bs->backing) {
int ret;
g_assert(!s->drain_count);
s->io_co = qemu_coroutine_self();
if (s->yield_before_read) {
s->yield_before_read = false;
qemu_coroutine_yield();
}
s->io_co = NULL;
ret = bdrv_co_preadv(bs->backing, offset, bytes, qiov, 0);
s->has_read = true;
/* Wake up drain_co if it runs */
if (s->drain_co) {
aio_co_wake(s->drain_co);
}
return ret;
}
s->has_read = true;
return 0;
}
static void coroutine_fn bdrv_replace_test_drain_co(void *opaque)
{
BlockDriverState *bs = opaque;
BDRVReplaceTestState *s = bs->opaque;
/* Keep waking io_co up until it is done */
while (s->io_co) {
aio_co_wake(s->io_co);
s->io_co = NULL;
qemu_coroutine_yield();
}
s->drain_co = NULL;
bdrv_dec_in_flight(bs);
}
/**
* If .drain_count is 0, wake up .io_co if there is one; and set
* .was_drained.
* Increment .drain_count.
*/
static void bdrv_replace_test_drain_begin(BlockDriverState *bs)
{
BDRVReplaceTestState *s = bs->opaque;
if (!s->setup_completed) {
return;
}
if (!s->drain_count) {
s->drain_co = qemu_coroutine_create(bdrv_replace_test_drain_co, bs);
bdrv_inc_in_flight(bs);
aio_co_enter(bdrv_get_aio_context(bs), s->drain_co);
s->was_drained = true;
}
s->drain_count++;
}
static void coroutine_fn bdrv_replace_test_read_entry(void *opaque)
{
BlockDriverState *bs = opaque;
char data;
QEMUIOVector qiov = QEMU_IOVEC_INIT_BUF(qiov, &data, 1);
int ret;
/* Queue a read request post-drain */
ret = bdrv_replace_test_co_preadv(bs, 0, 1, &qiov, 0);
g_assert(ret >= 0);
bdrv_dec_in_flight(bs);
}
/**
* Reduce .drain_count, set .was_undrained once it reaches 0.
* If .drain_count reaches 0 and the node has a backing file, issue a
* read request.
*/
static void bdrv_replace_test_drain_end(BlockDriverState *bs)
{
BDRVReplaceTestState *s = bs->opaque;
if (!s->setup_completed) {
return;
}
g_assert(s->drain_count > 0);
if (!--s->drain_count) {
s->was_undrained = true;
if (bs->backing) {
Coroutine *co = qemu_coroutine_create(bdrv_replace_test_read_entry,
bs);
bdrv_inc_in_flight(bs);
aio_co_enter(bdrv_get_aio_context(bs), co);
}
}
}
static BlockDriver bdrv_replace_test = {
.format_name = "replace_test",
.instance_size = sizeof(BDRVReplaceTestState),
.supports_backing = true,
.bdrv_close = bdrv_replace_test_close,
.bdrv_co_preadv = bdrv_replace_test_co_preadv,
.bdrv_drain_begin = bdrv_replace_test_drain_begin,
.bdrv_drain_end = bdrv_replace_test_drain_end,
.bdrv_child_perm = bdrv_default_perms,
};
static void coroutine_fn test_replace_child_mid_drain_read_co(void *opaque)
{
int ret;
char data;
ret = blk_co_pread(opaque, 0, 1, &data, 0);
g_assert(ret >= 0);
}
/**
* We test two things:
* (1) bdrv_replace_child_noperm() must not undrain the parent if both
* children are drained.
* (2) bdrv_replace_child_noperm() must never flush I/O requests to a
* drained child. If the old child is drained, it must flush I/O
* requests after the new one has been attached. If the new child
* is drained, it must flush I/O requests before the old one is
* detached.
*
* To do so, we create one parent node and two child nodes; then
* attach one of the children (old_child_bs) to the parent, then
* drain both old_child_bs and new_child_bs according to
* old_drain_count and new_drain_count, respectively, and finally
* we invoke bdrv_replace_node() to replace old_child_bs by
* new_child_bs.
*
* The test block driver we use here (bdrv_replace_test) has a read
* function that:
* - For the parent node, can optionally yield, and then forwards the
* read to bdrv_preadv(),
* - For the child node, just returns immediately.
*
* If the read yields, the drain_begin function will wake it up.
*
* The drain_end function issues a read on the parent once it is fully
* undrained (which simulates requests starting to come in again).
*/
static void do_test_replace_child_mid_drain(int old_drain_count,
int new_drain_count)
{
BlockBackend *parent_blk;
BlockDriverState *parent_bs;
BlockDriverState *old_child_bs, *new_child_bs;
BDRVReplaceTestState *parent_s;
BDRVReplaceTestState *old_child_s, *new_child_s;
Coroutine *io_co;
int i;
parent_bs = bdrv_new_open_driver(&bdrv_replace_test, "parent", 0,
&error_abort);
parent_s = parent_bs->opaque;
parent_blk = blk_new(qemu_get_aio_context(),
BLK_PERM_CONSISTENT_READ, BLK_PERM_ALL);
blk_insert_bs(parent_blk, parent_bs, &error_abort);
old_child_bs = bdrv_new_open_driver(&bdrv_replace_test, "old-child", 0,
&error_abort);
new_child_bs = bdrv_new_open_driver(&bdrv_replace_test, "new-child", 0,
&error_abort);
old_child_s = old_child_bs->opaque;
new_child_s = new_child_bs->opaque;
/* So that we can read something */
parent_bs->total_sectors = 1;
old_child_bs->total_sectors = 1;
new_child_bs->total_sectors = 1;
bdrv_ref(old_child_bs);
bdrv_attach_child(parent_bs, old_child_bs, "child", &child_of_bds,
BDRV_CHILD_COW, &error_abort);
parent_s->setup_completed = true;
for (i = 0; i < old_drain_count; i++) {
bdrv_drained_begin(old_child_bs);
}
for (i = 0; i < new_drain_count; i++) {
bdrv_drained_begin(new_child_bs);
}
if (!old_drain_count) {
/*
* Start a read operation that will yield, so it will not
* complete before the node is drained.
*/
parent_s->yield_before_read = true;
io_co = qemu_coroutine_create(test_replace_child_mid_drain_read_co,
parent_blk);
qemu_coroutine_enter(io_co);
}
/* If we have started a read operation, it should have yielded */
g_assert(!parent_s->has_read);
/* Reset drained status so we can see what bdrv_replace_node() does */
parent_s->was_drained = false;
parent_s->was_undrained = false;
g_assert(parent_bs->quiesce_counter == old_drain_count);
bdrv_replace_node(old_child_bs, new_child_bs, &error_abort);
g_assert(parent_bs->quiesce_counter == new_drain_count);
if (!old_drain_count && !new_drain_count) {
/*
* From undrained to undrained drains and undrains the parent,
* because bdrv_replace_node() contains a drained section for
* @old_child_bs.
*/
g_assert(parent_s->was_drained && parent_s->was_undrained);
} else if (!old_drain_count && new_drain_count) {
/*
* From undrained to drained should drain the parent and keep
* it that way.
*/
g_assert(parent_s->was_drained && !parent_s->was_undrained);
} else if (old_drain_count && !new_drain_count) {
/*
* From drained to undrained should undrain the parent and
* keep it that way.
*/
g_assert(!parent_s->was_drained && parent_s->was_undrained);
} else /* if (old_drain_count && new_drain_count) */ {
/*
* From drained to drained must not undrain the parent at any
* point
*/
g_assert(!parent_s->was_drained && !parent_s->was_undrained);
}
if (!old_drain_count || !new_drain_count) {
/*
* If !old_drain_count, we have started a read request before
* bdrv_replace_node(). If !new_drain_count, the parent must
* have been undrained at some point, and
* bdrv_replace_test_co_drain_end() starts a read request
* then.
*/
g_assert(parent_s->has_read);
} else {
/*
* If the parent was never undrained, there is no way to start
* a read request.
*/
g_assert(!parent_s->has_read);
}
/* A drained child must have not received any request */
g_assert(!(old_drain_count && old_child_s->has_read));
g_assert(!(new_drain_count && new_child_s->has_read));
for (i = 0; i < new_drain_count; i++) {
bdrv_drained_end(new_child_bs);
}
for (i = 0; i < old_drain_count; i++) {
bdrv_drained_end(old_child_bs);
}
/*
* By now, bdrv_replace_test_co_drain_end() must have been called
* at some point while the new child was attached to the parent.
*/
g_assert(parent_s->has_read);
g_assert(new_child_s->has_read);
blk_unref(parent_blk);
bdrv_unref(parent_bs);
bdrv_unref(old_child_bs);
bdrv_unref(new_child_bs);
}
static void test_replace_child_mid_drain(void)
{
int old_drain_count, new_drain_count;
for (old_drain_count = 0; old_drain_count < 2; old_drain_count++) {
for (new_drain_count = 0; new_drain_count < 2; new_drain_count++) {
do_test_replace_child_mid_drain(old_drain_count, new_drain_count);
}
}
}
int main(int argc, char **argv)
{
int ret;
bdrv_init();
qemu_init_main_loop(&error_abort);
g_test_init(&argc, &argv, NULL);
qemu_event_init(&done_event, false);
g_test_add_func("/bdrv-drain/driver-cb/drain_all", test_drv_cb_drain_all);
g_test_add_func("/bdrv-drain/driver-cb/drain", test_drv_cb_drain);
g_test_add_func("/bdrv-drain/driver-cb/co/drain_all",
test_drv_cb_co_drain_all);
g_test_add_func("/bdrv-drain/driver-cb/co/drain", test_drv_cb_co_drain);
g_test_add_func("/bdrv-drain/quiesce/drain_all", test_quiesce_drain_all);
g_test_add_func("/bdrv-drain/quiesce/drain", test_quiesce_drain);
g_test_add_func("/bdrv-drain/quiesce/co/drain_all",
test_quiesce_co_drain_all);
g_test_add_func("/bdrv-drain/quiesce/co/drain", test_quiesce_co_drain);
g_test_add_func("/bdrv-drain/nested", test_nested);
g_test_add_func("/bdrv-drain/graph-change/drain_all",
test_graph_change_drain_all);
g_test_add_func("/bdrv-drain/iothread/drain_all", test_iothread_drain_all);
g_test_add_func("/bdrv-drain/iothread/drain", test_iothread_drain);
g_test_add_func("/bdrv-drain/blockjob/drain_all", test_blockjob_drain_all);
g_test_add_func("/bdrv-drain/blockjob/drain", test_blockjob_drain);
g_test_add_func("/bdrv-drain/blockjob/error/drain_all",
test_blockjob_error_drain_all);
g_test_add_func("/bdrv-drain/blockjob/error/drain",
test_blockjob_error_drain);
g_test_add_func("/bdrv-drain/blockjob/iothread/drain_all",
test_blockjob_iothread_drain_all);
g_test_add_func("/bdrv-drain/blockjob/iothread/drain",
test_blockjob_iothread_drain);
g_test_add_func("/bdrv-drain/blockjob/iothread/error/drain_all",
test_blockjob_iothread_error_drain_all);
g_test_add_func("/bdrv-drain/blockjob/iothread/error/drain",
test_blockjob_iothread_error_drain);
g_test_add_func("/bdrv-drain/deletion/drain", test_delete_by_drain);
g_test_add_func("/bdrv-drain/detach/drain_all", test_detach_by_drain_all);
g_test_add_func("/bdrv-drain/detach/drain", test_detach_by_drain);
g_test_add_func("/bdrv-drain/detach/parent_cb", test_detach_by_parent_cb);
g_test_add_func("/bdrv-drain/detach/driver_cb", test_detach_by_driver_cb);
g_test_add_func("/bdrv-drain/attach/drain", test_append_to_drained);
g_test_add_func("/bdrv-drain/set_aio_context", test_set_aio_context);
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);
g_test_add_func("/bdrv-drain/replace_child/mid-drain",
test_replace_child_mid_drain);
ret = g_test_run();
qemu_event_destroy(&done_event);
return ret;
}
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