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authorJohn Snow <jsnow@redhat.com>2018-03-10 03:27:30 -0500
committerKevin Wolf <kwolf@redhat.com>2018-03-19 12:01:24 +0100
commitc9de40505f257a325e76f630c203432c77795461 (patch)
treeae91d8a3b13c7fa03c14cde589dcee016ed33210 /blockjob.c
parent58b295ba52c97a8d9e8cb526961a43b701dd2730 (diff)
blockjobs: add state transition table
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 <jsnow@redhat.com> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Diffstat (limited to 'blockjob.c')
-rw-r--r--blockjob.c40
1 files changed, 33 insertions, 7 deletions
diff --git a/blockjob.c b/blockjob.c
index 719169cccd..442426e27b 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/qapi-events-block-core.h"
@@ -41,6 +42,31 @@
* 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;
+ 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 +346,7 @@ 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);
}
@@ -702,7 +728,7 @@ void *block_job_create(const char *job_id, const BlockJobDriver *driver,
job->paused = true;
job->pause_count = 1;
job->refcnt = 1;
- 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);
@@ -817,13 +843,13 @@ 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) {
@@ -929,7 +955,7 @@ 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)) {