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blockjobs: add NULL state 

Add a new state that specifically demarcates when we begin to permanently
demolish a job after it has performed all work. This makes the transition
explicit in the STM table and highlights conditions under which a job may
be demolished.

Alongside this state, add a new helper command "block_job_decommission",
which transitions to the NULL state and puts down our implicit reference.
This separates instances in the code for "block_job_unref" which merely
undo a matching "block_job_ref" with instances intended to initiate the
full destruction of the object.

This decommission action also sets a number of fields to make sure that
block internals or external users that are holding a reference to a job
to see when it "finishes" are convinced that the job object is "done."
This is necessary, for instance, to do a block_job_cancel_sync on a
created object which will not make any progress.

Now, all jobs must go through block_job_decommission prior to being
freed, giving us start-to-finish state machine coverage for jobs.

Transitions:
Created   -> Null: Early failure event before the job is started
Concluded -> Null: Standard transition.

Verbs:
None. This should not ever be visible to the monitor.

             +---------+
             |UNDEFINED|
             +--+------+
                |
             +--v----+
   +---------+CREATED+------------------+
   |         +--+----+                  |
   |            |                       |
   |         +--v----+     +------+     |
   +---------+RUNNING<----->PAUSED|     |
   |         +--+-+--+     +------+     |
   |            | |                     |
   |            | +------------------+  |
   |            |                    |  |
   |         +--v--+       +-------+ |  |
   +---------+READY<------->STANDBY| |  |
   |         +--+--+       +-------+ |  |
   |            |                    |  |
+--v-----+   +--v------+             |  |
|ABORTING+--->CONCLUDED<-------------+  |
+--------+   +--+------+                |
                |                       |
             +--v-+                     |
             |NULL<---------------------+
             +----+

Signed-off-by: John Snow <jsnow@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
This commit is contained in:
John Snow 2018-03-10 03:27:35 -05:00 committed by Kevin Wolf
parent e0cf03647a
commit 3925cd3bc7
2 changed files with 36 additions and 19 deletions
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50
blockjob.c
View File

@ -44,24 +44,25 @@ static QemuMutex block_job_mutex;
/* BlockJob State Transition Table */
bool BlockJobSTT[BLOCK_JOB_STATUS__MAX][BLOCK_JOB_STATUS__MAX] = {
/* U, C, R, P, Y, S, X, E */
/* U: */ [BLOCK_JOB_STATUS_UNDEFINED] = {0, 1, 0, 0, 0, 0, 0, 0},
/* C: */ [BLOCK_JOB_STATUS_CREATED] = {0, 0, 1, 0, 0, 0, 1, 0},
/* R: */ [BLOCK_JOB_STATUS_RUNNING] = {0, 0, 0, 1, 1, 0, 1, 1},
/* P: */ [BLOCK_JOB_STATUS_PAUSED] = {0, 0, 1, 0, 0, 0, 0, 0},
/* Y: */ [BLOCK_JOB_STATUS_READY] = {0, 0, 0, 0, 0, 1, 1, 1},
/* S: */ [BLOCK_JOB_STATUS_STANDBY] = {0, 0, 0, 0, 1, 0, 0, 0},
/* X: */ [BLOCK_JOB_STATUS_ABORTING] = {0, 0, 0, 0, 0, 0, 0, 1},
/* E: */ [BLOCK_JOB_STATUS_CONCLUDED] = {0, 0, 0, 0, 0, 0, 0, 0},
/* U, C, R, P, Y, S, X, E, N */
/* U: */ [BLOCK_JOB_STATUS_UNDEFINED] = {0, 1, 0, 0, 0, 0, 0, 0, 0},
/* C: */ [BLOCK_JOB_STATUS_CREATED] = {0, 0, 1, 0, 0, 0, 1, 0, 1},
/* R: */ [BLOCK_JOB_STATUS_RUNNING] = {0, 0, 0, 1, 1, 0, 1, 1, 0},
/* P: */ [BLOCK_JOB_STATUS_PAUSED] = {0, 0, 1, 0, 0, 0, 0, 0, 0},
/* Y: */ [BLOCK_JOB_STATUS_READY] = {0, 0, 0, 0, 0, 1, 1, 1, 0},
/* S: */ [BLOCK_JOB_STATUS_STANDBY] = {0, 0, 0, 0, 1, 0, 0, 0, 0},
/* X: */ [BLOCK_JOB_STATUS_ABORTING] = {0, 0, 0, 0, 0, 0, 0, 1, 0},
/* E: */ [BLOCK_JOB_STATUS_CONCLUDED] = {0, 0, 0, 0, 0, 0, 0, 0, 1},
/* N: */ [BLOCK_JOB_STATUS_NULL] = {0, 0, 0, 0, 0, 0, 0, 0, 0},
};
bool BlockJobVerbTable[BLOCK_JOB_VERB__MAX][BLOCK_JOB_STATUS__MAX] = {
/* U, C, R, P, Y, S, X, E */
[BLOCK_JOB_VERB_CANCEL] = {0, 1, 1, 1, 1, 1, 0, 0},
[BLOCK_JOB_VERB_PAUSE] = {0, 1, 1, 1, 1, 1, 0, 0},
[BLOCK_JOB_VERB_RESUME] = {0, 1, 1, 1, 1, 1, 0, 0},
[BLOCK_JOB_VERB_SET_SPEED] = {0, 1, 1, 1, 1, 1, 0, 0},
[BLOCK_JOB_VERB_COMPLETE] = {0, 0, 0, 0, 1, 0, 0, 0},
/* U, C, R, P, Y, S, X, E, N */
[BLOCK_JOB_VERB_CANCEL] = {0, 1, 1, 1, 1, 1, 0, 0, 0},
[BLOCK_JOB_VERB_PAUSE] = {0, 1, 1, 1, 1, 1, 0, 0, 0},
[BLOCK_JOB_VERB_RESUME] = {0, 1, 1, 1, 1, 1, 0, 0, 0},
[BLOCK_JOB_VERB_SET_SPEED] = {0, 1, 1, 1, 1, 1, 0, 0, 0},
[BLOCK_JOB_VERB_COMPLETE] = {0, 0, 0, 0, 1, 0, 0, 0, 0},
};
static void block_job_state_transition(BlockJob *job, BlockJobStatus s1)
@ -225,6 +226,7 @@ static void block_job_detach_aio_context(void *opaque);
void block_job_unref(BlockJob *job)
{
if (--job->refcnt == 0) {
assert(job->status == BLOCK_JOB_STATUS_NULL);
BlockDriverState *bs = blk_bs(job->blk);
QLIST_REMOVE(job, job_list);
bs->job = NULL;
@ -378,6 +380,17 @@ void block_job_start(BlockJob *job)
bdrv_coroutine_enter(blk_bs(job->blk), job->co);
}
static void block_job_decommission(BlockJob *job)
{
assert(job);
job->completed = true;
job->busy = false;
job->paused = false;
job->deferred_to_main_loop = true;
block_job_state_transition(job, BLOCK_JOB_STATUS_NULL);
block_job_unref(job);
}
static void block_job_conclude(BlockJob *job)
{
block_job_state_transition(job, BLOCK_JOB_STATUS_CONCLUDED);
@ -424,7 +437,7 @@ static void block_job_completed_single(BlockJob *job)
QLIST_REMOVE(job, txn_list);
block_job_txn_unref(job->txn);
block_job_conclude(job);
block_job_unref(job);
block_job_decommission(job);
}
static void block_job_cancel_async(BlockJob *job)
@ -817,7 +830,7 @@ void *block_job_create(const char *job_id, const BlockJobDriver *driver,
block_job_set_speed(job, speed, &local_err);
if (local_err) {
block_job_unref(job);
block_job_early_fail(job);
error_propagate(errp, local_err);
return NULL;
}
@ -851,7 +864,8 @@ void block_job_pause_all(void)
void block_job_early_fail(BlockJob *job)
{
block_job_unref(job);
assert(job->status == BLOCK_JOB_STATUS_CREATED);
block_job_decommission(job);
}
void block_job_completed(BlockJob *job, int ret)

5
qapi/block-core.json
View File

@ -1006,11 +1006,14 @@
# @concluded: The job has finished all work. If manual was set to true, the job
# will remain in the query list until it is dismissed.
#
# @null: The job is in the process of being dismantled. This state should not
# ever be visible externally.
#
# Since: 2.12
##
{ 'enum': 'BlockJobStatus',
'data': ['undefined', 'created', 'running', 'paused', 'ready', 'standby',
'aborting', 'concluded' ] }
'aborting', 'concluded', 'null' ] }
##
# @BlockJobInfo: