The state transition table has mostly been implied. We're about to make
it a bit more complex, so let's make the STM explicit instead.
Perform state transitions with a function that for now just asserts the
transition is appropriate.
Transitions:
Undefined -> Created: During job initialization.
Created -> Running: Once the job is started.
Jobs cannot transition from "Created" to "Paused"
directly, but will instead synchronously transition
to running to paused immediately.
Running -> Paused: Normal workflow for pauses.
Running -> Ready: Normal workflow for jobs reaching their sync point.
(e.g. mirror)
Ready -> Standby: Normal workflow for pausing ready jobs.
Paused -> Running: Normal resume.
Standby -> Ready: Resume of a Standby job.
+---------+
|UNDEFINED|
+--+------+
|
+--v----+
|CREATED|
+--+----+
|
+--v----+ +------+
|RUNNING<----->PAUSED|
+--+----+ +------+
|
+--v--+ +-------+
|READY<------->STANDBY|
+-----+ +-------+
Notably, there is no state presently defined as of this commit that
deals with a job after the "running" or "ready" states, so this table
will be adjusted alongside the commits that introduce those states.
Signed-off-by: John Snow <js...@redhat.com>
---
block/trace-events | 3 +++
blockjob.c | 42 ++++++++++++++++++++++++++++++++++++------
2 files changed, 39 insertions(+), 6 deletions(-)
diff --git a/block/trace-events b/block/trace-events
index 02dd80ff0c..b75a0c8409 100644
--- a/block/trace-events
+++ b/block/trace-events
@@ -4,6 +4,9 @@
bdrv_open_common(void *bs, const char *filename, int flags, const char
*format_name) "bs %p filename \"%s\" flags 0x%x format_name \"%s\""
bdrv_lock_medium(void *bs, bool locked) "bs %p locked %d"
+# blockjob.c
+block_job_state_transition(void *job, int ret, const char *legal, const char
*s0, const char *s1) "job %p (ret: %d) attempting %s transition (%s-->%s)"
+
# block/block-backend.c
blk_co_preadv(void *blk, void *bs, int64_t offset, unsigned int bytes, int
flags) "blk %p bs %p offset %"PRId64" bytes %u flags 0x%x"
blk_co_pwritev(void *blk, void *bs, int64_t offset, unsigned int bytes, int
flags) "blk %p bs %p offset %"PRId64" bytes %u flags 0x%x"
diff --git a/blockjob.c b/blockjob.c
index 1be9c20cff..d745b3bb69 100644
--- a/blockjob.c
+++ b/blockjob.c
@@ -28,6 +28,7 @@
#include "block/block.h"
#include "block/blockjob_int.h"
#include "block/block_int.h"
+#include "block/trace.h"
#include "sysemu/block-backend.h"
#include "qapi/error.h"
#include "qapi/qmp/qerror.h"
@@ -41,6 +42,34 @@
* block_job_enter. */
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 */
+ /* U: */ [BLOCK_JOB_STATUS_UNDEFINED] = {0, 1, 0, 0, 0, 0},
+ /* C: */ [BLOCK_JOB_STATUS_CREATED] = {0, 0, 1, 0, 0, 0},
+ /* R: */ [BLOCK_JOB_STATUS_RUNNING] = {0, 0, 0, 1, 1, 0},
+ /* P: */ [BLOCK_JOB_STATUS_PAUSED] = {0, 0, 1, 0, 0, 0},
+ /* Y: */ [BLOCK_JOB_STATUS_READY] = {0, 0, 0, 0, 0, 1},
+ /* S: */ [BLOCK_JOB_STATUS_STANDBY] = {0, 0, 0, 0, 1, 0},
+};
+
+static void block_job_state_transition(BlockJob *job, BlockJobStatus s1)
+{
+ BlockJobStatus s0 = job->status;
+ if (s0 == s1) {
+ return;
+ }
+ assert(s1 >= 0 && s1 <= BLOCK_JOB_STATUS__MAX);
+ trace_block_job_state_transition(job, job->ret, BlockJobSTT[s0][s1] ?
+ "allowed" : "disallowed",
+ qapi_enum_lookup(&BlockJobStatus_lookup,
+ s0),
+ qapi_enum_lookup(&BlockJobStatus_lookup,
+ s1));
+ assert(BlockJobSTT[s0][s1]);
+ job->status = s1;
+}
+
static void block_job_lock(void)
{
qemu_mutex_lock(&block_job_mutex);
@@ -320,7 +349,7 @@ void block_job_start(BlockJob *job)
job->pause_count--;
job->busy = true;
job->paused = false;
- job->status = BLOCK_JOB_STATUS_RUNNING;
+ block_job_state_transition(job, BLOCK_JOB_STATUS_RUNNING);
bdrv_coroutine_enter(blk_bs(job->blk), job->co);
}
@@ -704,6 +733,7 @@ void *block_job_create(const char *job_id, const
BlockJobDriver *driver,
job->refcnt = 1;
job->manual = (flags & BLOCK_JOB_MANUAL);
job->status = BLOCK_JOB_STATUS_CREATED;
+ block_job_state_transition(job, BLOCK_JOB_STATUS_CREATED);
aio_timer_init(qemu_get_aio_context(), &job->sleep_timer,
QEMU_CLOCK_REALTIME, SCALE_NS,
block_job_sleep_timer_cb, job);
@@ -818,13 +848,13 @@ void coroutine_fn block_job_pause_point(BlockJob *job)
if (block_job_should_pause(job) && !block_job_is_cancelled(job)) {
BlockJobStatus status = job->status;
- job->status = status == BLOCK_JOB_STATUS_READY ? \
- BLOCK_JOB_STATUS_STANDBY : \
- BLOCK_JOB_STATUS_PAUSED;
+ block_job_state_transition(job, status == BLOCK_JOB_STATUS_READY ? \
+ BLOCK_JOB_STATUS_STANDBY : \
+ BLOCK_JOB_STATUS_PAUSED);
job->paused = true;
block_job_do_yield(job, -1);
job->paused = false;
- job->status = status;
+ block_job_state_transition(job, status);
}
if (job->driver->resume) {
@@ -930,7 +960,7 @@ void block_job_iostatus_reset(BlockJob *job)
void block_job_event_ready(BlockJob *job)
{
- job->status = BLOCK_JOB_STATUS_READY;
+ block_job_state_transition(job, BLOCK_JOB_STATUS_READY);
job->ready = true;
if (block_job_is_internal(job)) {
--
2.14.3
