From: Fam Zheng <famz@redhat.com>
Date: Fri, 3 Apr 2015 14:05:18 +0000 (+0800)
Subject: blockjob: Allow nested pause
X-Git-Url: https://repo.jachan.dev/qemu.git/commitdiff_plain/751ebd76e654bd1e65da08ecf694325282b4cfcc
blockjob: Allow nested pause
This patch changes block_job_pause to increase the pause counter and
block_job_resume to decrease it.
The counter will allow calling block_job_pause/block_job_resume
unconditionally on a job when we need to suspend the IO temporarily.
From now on, each block_job_resume must be paired with a block_job_pause
to keep the counter balanced.
The user pause from QMP or HMP will only trigger block_job_pause once
until it's resumed, this is achieved by adding a user_paused flag in
BlockJob.
One occurrence of block_job_resume in mirror_complete is replaced with
block_job_enter which does what is necessary.
In block_job_cancel, the cancel flag is good enough to instruct
coroutines to quit loop, so use block_job_enter to replace the unpaired
block_job_resume.
Upon block job IO error, user is notified about the entering to the
pause state, so this pause belongs to user pause, set the flag
accordingly and expect a matching QMP resume.
[Extended doc comments as suggested by Paolo Bonzini
<pbonzini@redhat.com>.
--Stefan]
Signed-off-by: Fam Zheng <famz@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Reviewed-by: Alberto Garcia <berto@igalia.com>
Message-id: 1428069921-2957-2-git-send-email-famz@redhat.com
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
---
diff --git a/block/mirror.c b/block/mirror.c
index 405616422b..65b1718671 100644
--- a/block/mirror.c
+++ b/block/mirror.c
@@ -634,7 +634,7 @@ static void mirror_complete(BlockJob *job, Error **errp)
}
s->should_complete = true;
- block_job_resume(job);
+ block_job_enter(&s->common);
}
static const BlockJobDriver mirror_job_driver = {
diff --git a/blockdev.c b/blockdev.c
index fbb3a79978..9132d69e09 100644
--- a/blockdev.c
+++ b/blockdev.c
@@ -2699,7 +2699,7 @@ void qmp_block_job_cancel(const char *device,
force = false;
}
- if (job->paused && !force) {
+ if (job->user_paused && !force) {
error_setg(errp, "The block job for device '%s' is currently paused",
device);
goto out;
@@ -2716,10 +2716,11 @@ void qmp_block_job_pause(const char *device, Error **errp)
AioContext *aio_context;
BlockJob *job = find_block_job(device, &aio_context, errp);
- if (!job) {
+ if (!job || job->user_paused) {
return;
}
+ job->user_paused = true;
trace_qmp_block_job_pause(job);
block_job_pause(job);
aio_context_release(aio_context);
@@ -2730,10 +2731,11 @@ void qmp_block_job_resume(const char *device, Error **errp)
AioContext *aio_context;
BlockJob *job = find_block_job(device, &aio_context, errp);
- if (!job) {
+ if (!job || !job->user_paused) {
return;
}
+ job->user_paused = false;
trace_qmp_block_job_resume(job);
block_job_resume(job);
aio_context_release(aio_context);
diff --git a/blockjob.c b/blockjob.c
index ba2255d91f..2755465259 100644
--- a/blockjob.c
+++ b/blockjob.c
@@ -107,7 +107,7 @@ void block_job_set_speed(BlockJob *job, int64_t speed, Error **errp)
void block_job_complete(BlockJob *job, Error **errp)
{
- if (job->paused || job->cancelled || !job->driver->complete) {
+ if (job->pause_count || job->cancelled || !job->driver->complete) {
error_set(errp, QERR_BLOCK_JOB_NOT_READY,
bdrv_get_device_name(job->bs));
return;
@@ -118,17 +118,26 @@ void block_job_complete(BlockJob *job, Error **errp)
void block_job_pause(BlockJob *job)
{
- job->paused = true;
+ job->pause_count++;
}
bool block_job_is_paused(BlockJob *job)
{
- return job->paused;
+ return job->pause_count > 0;
}
void block_job_resume(BlockJob *job)
{
- job->paused = false;
+ assert(job->pause_count > 0);
+ job->pause_count--;
+ if (job->pause_count) {
+ return;
+ }
+ block_job_enter(job);
+}
+
+void block_job_enter(BlockJob *job)
+{
block_job_iostatus_reset(job);
if (job->co && !job->busy) {
qemu_coroutine_enter(job->co, NULL);
@@ -138,7 +147,7 @@ void block_job_resume(BlockJob *job)
void block_job_cancel(BlockJob *job)
{
job->cancelled = true;
- block_job_resume(job);
+ block_job_enter(job);
}
bool block_job_is_cancelled(BlockJob *job)
@@ -258,7 +267,7 @@ BlockJobInfo *block_job_query(BlockJob *job)
info->device = g_strdup(bdrv_get_device_name(job->bs));
info->len = job->len;
info->busy = job->busy;
- info->paused = job->paused;
+ info->paused = job->pause_count > 0;
info->offset = job->offset;
info->speed = job->speed;
info->io_status = job->iostatus;
@@ -335,6 +344,8 @@ BlockErrorAction block_job_error_action(BlockJob *job, BlockDriverState *bs,
IO_OPERATION_TYPE_WRITE,
action, &error_abort);
if (action == BLOCK_ERROR_ACTION_STOP) {
+ /* make the pause user visible, which will be resumed from QMP. */
+ job->user_paused = true;
block_job_pause(job);
block_job_iostatus_set_err(job, error);
if (bs != job->bs) {
diff --git a/include/block/blockjob.h b/include/block/blockjob.h
index b6d4ebbe03..57d8ef13e2 100644
--- a/include/block/blockjob.h
+++ b/include/block/blockjob.h
@@ -79,10 +79,16 @@ struct BlockJob {
bool cancelled;
/**
- * Set to true if the job is either paused, or will pause itself
- * as soon as possible (if busy == true).
+ * Counter for pause request. If non-zero, the block job is either paused,
+ * or if busy == true will pause itself as soon as possible.
*/
- bool paused;
+ int pause_count;
+
+ /**
+ * Set to true if the job is paused by user. Can be unpaused with the
+ * block-job-resume QMP command.
+ */
+ bool user_paused;
/**
* Set to false by the job while it is in a quiescent state, where
@@ -225,10 +231,18 @@ void block_job_pause(BlockJob *job);
* block_job_resume:
* @job: The job to be resumed.
*
- * Resume the specified job.
+ * Resume the specified job. Must be paired with a preceding block_job_pause.
*/
void block_job_resume(BlockJob *job);
+/**
+ * block_job_enter:
+ * @job: The job to enter.
+ *
+ * Continue the specified job by entering the coroutine.
+ */
+void block_job_enter(BlockJob *job);
+
/**
* block_job_event_cancelled:
* @job: The job whose information is requested.