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blockjob: introduce block_job_cancel_async, check iostatus invariants

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The new functions helps respecting the invariant that the coroutine
is entered with false user_resume, zero pause count and no error
recorded in the iostatus.

Resetting the iostatus is now common to all of block_job_cancel_async,
block_job_user_resume and block_job_iostatus_reset, albeit with slight
differences:

- block_job_cancel_async resets the iostatus, and resumes the job if
there was an error, but the coroutine is not restarted immediately.
For example the caller may continue with a call to block_job_finish_sync.

- block_job_user_resume resets the iostatus.  It wants to resume the job
unconditionally, even if there was no error.

- block_job_iostatus_reset doesn't resume the job at all.  Maybe that's
a bug but it should be fixed separately.

block_job_iostatus_reset does the least common denominator, so add some
checking but otherwise leave it as the entry point for resetting the
iostatus.

Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Message-id: 20170508141310.8674-8-pbonzini@redhat.com
Signed-off-by: Jeff Cody <jcody@redhat.com>
This commit is contained in:
Paolo Bonzini 2017-05-08 16:13:06 +02:00 committed by Jeff Cody
parent 2caf63a903
commit 4c241cf5d6
1 changed files with 20 additions and 4 deletions
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24
blockjob.c
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@ -304,6 +304,19 @@ static void block_job_completed_single(BlockJob *job)
block_job_unref(job);
}
static void block_job_cancel_async(BlockJob *job)
{
if (job->iostatus != BLOCK_DEVICE_IO_STATUS_OK) {
block_job_iostatus_reset(job);
}
if (job->user_paused) {
/* Do not call block_job_enter here, the caller will handle it. */
job->user_paused = false;
job->pause_count--;
}
job->cancelled = true;
}
static void block_job_completed_txn_abort(BlockJob *job)
{
AioContext *ctx;
@ -328,7 +341,7 @@ static void block_job_completed_txn_abort(BlockJob *job)
* them; this job, however, may or may not be cancelled, depending
* on the caller, so leave it. */
if (other_job != job) {
other_job->cancelled = true;
block_job_cancel_async(other_job);
}
continue;
}
@ -411,8 +424,8 @@ bool block_job_user_paused(BlockJob *job)
void block_job_user_resume(BlockJob *job)
{
if (job && job->user_paused && job->pause_count > 0) {
job->user_paused = false;
block_job_iostatus_reset(job);
job->user_paused = false;
block_job_resume(job);
}
}
@ -420,8 +433,7 @@ void block_job_user_resume(BlockJob *job)
void block_job_cancel(BlockJob *job)
{
if (block_job_started(job)) {
job->cancelled = true;
block_job_iostatus_reset(job);
block_job_cancel_async(job);
block_job_enter(job);
} else {
block_job_completed(job, -ECANCELED);
@ -765,6 +777,10 @@ void block_job_yield(BlockJob *job)
void block_job_iostatus_reset(BlockJob *job)
{
if (job->iostatus == BLOCK_DEVICE_IO_STATUS_OK) {
return;
}
assert(job->user_paused && job->pause_count > 0);
job->iostatus = BLOCK_DEVICE_IO_STATUS_OK;
}