From 70365466a45a381ebb54e49cb03579b5fd6c76ef Mon Sep 17 00:00:00 2001
From: Kevin Wolf <kwolf@redhat.com>
Date: Fri, 14 Sep 2018 10:55:05 +0200
Subject: [PATCH 14/49] block: Really pause block jobs on drain
RH-Author: Kevin Wolf <kwolf@redhat.com>
Message-id: <20180914105540.18077-8-kwolf@redhat.com>
Patchwork-id: 82160
O-Subject: [RHV-7.6 qemu-kvm-rhev PATCH 07/42] block: Really pause block jobs on drain
Bugzilla: 1601212
RH-Acked-by: John Snow <jsnow@redhat.com>
RH-Acked-by: Max Reitz <mreitz@redhat.com>
RH-Acked-by: Fam Zheng <famz@redhat.com>
We already requested that block jobs be paused in .bdrv_drained_begin,
but no guarantee was made that the job was actually inactive at the
point where bdrv_drained_begin() returned.
This introduces a new callback BdrvChildRole.bdrv_drained_poll() and
uses it to make bdrv_drain_poll() consider block jobs using the node to
be drained.
For the test case to work as expected, we have to switch from
block_job_sleep_ns() to qemu_co_sleep_ns() so that the test job is even
considered active and must be waited for when draining the node.
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
(cherry picked from commit 89bd030533e3592ca0a995450dcfc5d53e459e20)
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Miroslav Rezanina <mrezanin@redhat.com>
---
block.c | 9 +++++++++
block/io.c | 40 ++++++++++++++++++++++++++++++++++------
block/mirror.c | 8 ++++++++
blockjob.c | 23 +++++++++++++++++++++++
include/block/block.h | 8 ++++++++
include/block/block_int.h | 7 +++++++
include/block/blockjob_int.h | 8 ++++++++
tests/test-bdrv-drain.c | 18 ++++++++++--------
8 files changed, 107 insertions(+), 14 deletions(-)
diff --git a/block.c b/block.c
index 10a1ece..0d9698a 100644
--- a/block.c
+++ b/block.c
@@ -821,6 +821,12 @@ static void bdrv_child_cb_drained_begin(BdrvChild *child)
bdrv_drained_begin(bs);
}
+static bool bdrv_child_cb_drained_poll(BdrvChild *child)
+{
+ BlockDriverState *bs = child->opaque;
+ return bdrv_drain_poll(bs, NULL);
+}
+
static void bdrv_child_cb_drained_end(BdrvChild *child)
{
BlockDriverState *bs = child->opaque;
@@ -905,6 +911,7 @@ const BdrvChildRole child_file = {
.get_parent_desc = bdrv_child_get_parent_desc,
.inherit_options = bdrv_inherited_options,
.drained_begin = bdrv_child_cb_drained_begin,
+ .drained_poll = bdrv_child_cb_drained_poll,
.drained_end = bdrv_child_cb_drained_end,
.attach = bdrv_child_cb_attach,
.detach = bdrv_child_cb_detach,
@@ -929,6 +936,7 @@ const BdrvChildRole child_format = {
.get_parent_desc = bdrv_child_get_parent_desc,
.inherit_options = bdrv_inherited_fmt_options,
.drained_begin = bdrv_child_cb_drained_begin,
+ .drained_poll = bdrv_child_cb_drained_poll,
.drained_end = bdrv_child_cb_drained_end,
.attach = bdrv_child_cb_attach,
.detach = bdrv_child_cb_detach,
@@ -1048,6 +1056,7 @@ const BdrvChildRole child_backing = {
.detach = bdrv_backing_detach,
.inherit_options = bdrv_backing_options,
.drained_begin = bdrv_child_cb_drained_begin,
+ .drained_poll = bdrv_child_cb_drained_poll,
.drained_end = bdrv_child_cb_drained_end,
.inactivate = bdrv_child_cb_inactivate,
.update_filename = bdrv_backing_update_filename,
diff --git a/block/io.c b/block/io.c
index 4d332c3..e260394 100644
--- a/block/io.c
+++ b/block/io.c
@@ -69,6 +69,23 @@ void bdrv_parent_drained_end(BlockDriverState *bs, BdrvChild *ignore)
}
}
+static bool bdrv_parent_drained_poll(BlockDriverState *bs, BdrvChild *ignore)
+{
+ BdrvChild *c, *next;
+ bool busy = false;
+
+ QLIST_FOREACH_SAFE(c, &bs->parents, next_parent, next) {
+ if (c == ignore) {
+ continue;
+ }
+ if (c->role->drained_poll) {
+ busy |= c->role->drained_poll(c);
+ }
+ }
+
+ return busy;
+}
+
static void bdrv_merge_limits(BlockLimits *dst, const BlockLimits *src)
{
dst->opt_transfer = MAX(dst->opt_transfer, src->opt_transfer);
@@ -182,21 +199,32 @@ static void bdrv_drain_invoke(BlockDriverState *bs, bool begin)
}
/* Returns true if BDRV_POLL_WHILE() should go into a blocking aio_poll() */
-static bool bdrv_drain_poll(BlockDriverState *bs)
+bool bdrv_drain_poll(BlockDriverState *bs, BdrvChild *ignore_parent)
+{
+ if (bdrv_parent_drained_poll(bs, ignore_parent)) {
+ return true;
+ }
+
+ return atomic_read(&bs->in_flight);
+}
+
+static bool bdrv_drain_poll_top_level(BlockDriverState *bs,
+ BdrvChild *ignore_parent)
{
/* Execute pending BHs first and check everything else only after the BHs
* have executed. */
while (aio_poll(bs->aio_context, false));
- return atomic_read(&bs->in_flight);
+
+ return bdrv_drain_poll(bs, ignore_parent);
}
-static bool bdrv_drain_recurse(BlockDriverState *bs)
+static bool bdrv_drain_recurse(BlockDriverState *bs, BdrvChild *parent)
{
BdrvChild *child, *tmp;
bool waited;
/* Wait for drained requests to finish */
- waited = BDRV_POLL_WHILE(bs, bdrv_drain_poll(bs));
+ waited = BDRV_POLL_WHILE(bs, bdrv_drain_poll_top_level(bs, parent));
QLIST_FOREACH_SAFE(child, &bs->children, next, tmp) {
BlockDriverState *bs = child->bs;
@@ -213,7 +241,7 @@ static bool bdrv_drain_recurse(BlockDriverState *bs)
*/
bdrv_ref(bs);
}
- waited |= bdrv_drain_recurse(bs);
+ waited |= bdrv_drain_recurse(bs, child);
if (in_main_loop) {
bdrv_unref(bs);
}
@@ -289,7 +317,7 @@ void bdrv_do_drained_begin(BlockDriverState *bs, bool recursive,
bdrv_parent_drained_begin(bs, parent);
bdrv_drain_invoke(bs, true);
- bdrv_drain_recurse(bs);
+ bdrv_drain_recurse(bs, parent);
if (recursive) {
bs->recursive_quiesce_counter++;
diff --git a/block/mirror.c b/block/mirror.c
index 313e6e9..4b27f71 100644
--- a/block/mirror.c
+++ b/block/mirror.c
@@ -976,6 +976,12 @@ static void mirror_pause(Job *job)
mirror_wait_for_all_io(s);
}
+static bool mirror_drained_poll(BlockJob *job)
+{
+ MirrorBlockJob *s = container_of(job, MirrorBlockJob, common);
+ return !!s->in_flight;
+}
+
static void mirror_attached_aio_context(BlockJob *job, AioContext *new_context)
{
MirrorBlockJob *s = container_of(job, MirrorBlockJob, common);
@@ -1011,6 +1017,7 @@ static const BlockJobDriver mirror_job_driver = {
.pause = mirror_pause,
.complete = mirror_complete,
},
+ .drained_poll = mirror_drained_poll,
.attached_aio_context = mirror_attached_aio_context,
.drain = mirror_drain,
};
@@ -1028,6 +1035,7 @@ static const BlockJobDriver commit_active_job_driver = {
.pause = mirror_pause,
.complete = mirror_complete,
},
+ .drained_poll = mirror_drained_poll,
.attached_aio_context = mirror_attached_aio_context,
.drain = mirror_drain,
};
diff --git a/blockjob.c b/blockjob.c
index 0306533..be5903a 100644
--- a/blockjob.c
+++ b/blockjob.c
@@ -155,6 +155,28 @@ static void child_job_drained_begin(BdrvChild *c)
job_pause(&job->job);
}
+static bool child_job_drained_poll(BdrvChild *c)
+{
+ BlockJob *bjob = c->opaque;
+ Job *job = &bjob->job;
+ const BlockJobDriver *drv = block_job_driver(bjob);
+
+ /* An inactive or completed job doesn't have any pending requests. Jobs
+ * with !job->busy are either already paused or have a pause point after
+ * being reentered, so no job driver code will run before they pause. */
+ if (!job->busy || job_is_completed(job) || job->deferred_to_main_loop) {
+ return false;
+ }
+
+ /* Otherwise, assume that it isn't fully stopped yet, but allow the job to
+ * override this assumption. */
+ if (drv->drained_poll) {
+ return drv->drained_poll(bjob);
+ } else {
+ return true;
+ }
+}
+
static void child_job_drained_end(BdrvChild *c)
{
BlockJob *job = c->opaque;
@@ -164,6 +186,7 @@ static void child_job_drained_end(BdrvChild *c)
static const BdrvChildRole child_job = {
.get_parent_desc = child_job_get_parent_desc,
.drained_begin = child_job_drained_begin,
+ .drained_poll = child_job_drained_poll,
.drained_end = child_job_drained_end,
.stay_at_node = true,
};
diff --git a/include/block/block.h b/include/block/block.h
index 8f87eea..8c91d4c 100644
--- a/include/block/block.h
+++ b/include/block/block.h
@@ -596,6 +596,14 @@ void bdrv_parent_drained_begin(BlockDriverState *bs, BdrvChild *ignore);
void bdrv_parent_drained_end(BlockDriverState *bs, BdrvChild *ignore);
/**
+ * bdrv_drain_poll:
+ *
+ * Poll for pending requests in @bs and its parents (except for
+ * @ignore_parent). This is part of bdrv_drained_begin.
+ */
+bool bdrv_drain_poll(BlockDriverState *bs, BdrvChild *ignore_parent);
+
+/**
* bdrv_drained_begin:
*
* Begin a quiesced section for exclusive access to the BDS, by disabling
diff --git a/include/block/block_int.h b/include/block/block_int.h
index 341cbe8..beeacde 100644
--- a/include/block/block_int.h
+++ b/include/block/block_int.h
@@ -610,6 +610,13 @@ struct BdrvChildRole {
void (*drained_begin)(BdrvChild *child);
void (*drained_end)(BdrvChild *child);
+ /*
+ * Returns whether the parent has pending requests for the child. This
+ * callback is polled after .drained_begin() has been called until all
+ * activity on the child has stopped.
+ */
+ bool (*drained_poll)(BdrvChild *child);
+
/* Notifies the parent that the child has been activated/inactivated (e.g.
* when migration is completing) and it can start/stop requesting
* permissions and doing I/O on it. */
diff --git a/include/block/blockjob_int.h b/include/block/blockjob_int.h
index 5cd50c6..e4a318d 100644
--- a/include/block/blockjob_int.h
+++ b/include/block/blockjob_int.h
@@ -39,6 +39,14 @@ struct BlockJobDriver {
JobDriver job_driver;
/*
+ * Returns whether the job has pending requests for the child or will
+ * submit new requests before the next pause point. This callback is polled
+ * in the context of draining a job node after requesting that the job be
+ * paused, until all activity on the child has stopped.
+ */
+ bool (*drained_poll)(BlockJob *job);
+
+ /*
* If the callback is not NULL, it will be invoked before the job is
* resumed in a new AioContext. This is the place to move any resources
* besides job->blk to the new AioContext.
diff --git a/tests/test-bdrv-drain.c b/tests/test-bdrv-drain.c
index f5d85c9..49786ea 100644
--- a/tests/test-bdrv-drain.c
+++ b/tests/test-bdrv-drain.c
@@ -681,7 +681,11 @@ static int coroutine_fn test_job_run(Job *job, Error **errp)
job_transition_to_ready(&s->common.job);
while (!s->should_complete) {
- job_sleep_ns(&s->common.job, 100000);
+ /* Avoid block_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 acitivity to stop. */
+ qemu_co_sleep_ns(QEMU_CLOCK_REALTIME, 100000);
+ job_pause_point(&s->common.job);
}
return 0;
@@ -728,7 +732,7 @@ static void test_blockjob_common(enum drain_type drain_type)
g_assert_cmpint(job->job.pause_count, ==, 0);
g_assert_false(job->job.paused);
- g_assert_false(job->job.busy); /* We're in job_sleep_ns() */
+ g_assert_true(job->job.busy); /* We're in job_sleep_ns() */
do_drain_begin(drain_type, src);
@@ -738,15 +742,14 @@ static void test_blockjob_common(enum drain_type drain_type)
} else {
g_assert_cmpint(job->job.pause_count, ==, 1);
}
- /* XXX We don't wait until the job is actually paused. Is this okay? */
- /* g_assert_true(job->job.paused); */
+ g_assert_true(job->job.paused);
g_assert_false(job->job.busy); /* The job is paused */
do_drain_end(drain_type, src);
g_assert_cmpint(job->job.pause_count, ==, 0);
g_assert_false(job->job.paused);
- g_assert_false(job->job.busy); /* We're in job_sleep_ns() */
+ g_assert_true(job->job.busy); /* We're in qemu_co_sleep_ns() */
do_drain_begin(drain_type, target);
@@ -756,15 +759,14 @@ static void test_blockjob_common(enum drain_type drain_type)
} else {
g_assert_cmpint(job->job.pause_count, ==, 1);
}
- /* XXX We don't wait until the job is actually paused. Is this okay? */
- /* g_assert_true(job->job.paused); */
+ g_assert_true(job->job.paused);
g_assert_false(job->job.busy); /* The job is paused */
do_drain_end(drain_type, target);
g_assert_cmpint(job->job.pause_count, ==, 0);
g_assert_false(job->job.paused);
- g_assert_false(job->job.busy); /* We're in job_sleep_ns() */
+ g_assert_true(job->job.busy); /* We're in job_sleep_ns() */
ret = job_complete_sync(&job->job, &error_abort);
g_assert_cmpint(ret, ==, 0);
--
1.8.3.1