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tests: Test mid-drain bdrv_replace_child_noperm()

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Add a test for what happens when you call bdrv_replace_child_noperm()
for various drain situations ({old,new} child {drained,not drained}).

Most importantly, if both the old and the new child are drained, the
parent must not be undrained at any point.

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 15:33:46 +02:00 committed by Kevin Wolf
parent 9746b35cf3
commit 0513f9841f
1 changed files with 308 additions and 0 deletions
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308
tests/test-bdrv-drain.c
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@ -1835,6 +1835,311 @@ static void test_drop_intermediate_poll(void)
bdrv_unref(chain[2]);
}
typedef struct BDRVReplaceTestState {
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,
uint64_t offset,
uint64_t bytes,
QEMUIOVector *qiov,
int 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_preadv(bs->backing, offset, qiov);
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;
}
/**
* If .drain_count is 0, wake up .io_co if there is one; and set
* .was_drained.
* Increment .drain_count.
*/
static void coroutine_fn bdrv_replace_test_co_drain_begin(BlockDriverState *bs)
{
BDRVReplaceTestState *s = bs->opaque;
if (!s->drain_count) {
/* Keep waking io_co up until it is done */
s->drain_co = qemu_coroutine_self();
while (s->io_co) {
aio_co_wake(s->io_co);
s->io_co = NULL;
qemu_coroutine_yield();
}
s->drain_co = NULL;
s->was_drained = true;
}
s->drain_count++;
}
/**
* 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 coroutine_fn bdrv_replace_test_co_drain_end(BlockDriverState *bs)
{
BDRVReplaceTestState *s = bs->opaque;
g_assert(s->drain_count > 0);
if (!--s->drain_count) {
int ret;
s->was_undrained = true;
if (bs->backing) {
char data;
QEMUIOVector qiov = QEMU_IOVEC_INIT_BUF(qiov, &data, 1);
/* Queue a read request post-drain */
ret = bdrv_replace_test_co_preadv(bs, 0, 1, &qiov, 0);
g_assert(ret >= 0);
}
}
}
static BlockDriver bdrv_replace_test = {
.format_name = "replace_test",
.instance_size = sizeof(BDRVReplaceTestState),
.bdrv_close = bdrv_replace_test_close,
.bdrv_co_preadv = bdrv_replace_test_co_preadv,
.bdrv_co_drain_begin = bdrv_replace_test_co_drain_begin,
.bdrv_co_drain_end = bdrv_replace_test_co_drain_end,
.bdrv_child_perm = bdrv_format_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);
parent_bs->backing = bdrv_attach_child(parent_bs, old_child_bs, "child",
&child_backing, &error_abort);
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;
@ -1924,6 +2229,9 @@ int main(int argc, char **argv)
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;