[Qemu-block] [RFC v3 02/14] blockjobs: Add status enum

[John Snow]

We're about to add several new states, and booleans are becoming
unwieldly and difficult to reason about. To this end, add a new "status"
field and add our existing states in a redundant manner alongside the
bools they are replacing:

UNDEFINED: Placeholder, default state.
CREATED:   replaces (paused && !busy)
RUNNING:   replaces effectively (!paused && busy)
PAUSED:    Nearly redundant with info->paused, which shows pause_count.
           This reports the actual status of the job, which almost always
           matches the paused request status. It differs in that it is
           strictly only true when the job has actually gone dormant.
READY:     replaces job->ready.

New state additions in coming commits will not be quite so redundant:

WAITING:   Waiting on Transaction. This job has finished all the work
           it can until the transaction converges, fails, or is canceled.
           This status does not feature for non-transactional jobs.
PENDING:   Pending authorization from user. This job has finished all the
           work it can until the job or transaction is finalized via
           block_job_finalize. If this job is in a transaction, it has
           already left the WAITING status.
CONCLUDED: Job has ceased all operations and has a return code available
           for query and may be dismissed via block_job_dismiss.
Signed-off-by: John Snow <address@hidden>
---
 blockjob.c               | 10 ++++++++++
 include/block/blockjob.h |  4 ++++
 qapi/block-core.json     | 17 ++++++++++++++++-
 3 files changed, 30 insertions(+), 1 deletion(-)

diff --git a/blockjob.c b/blockjob.c
index 9850d70cb0..6eb783a354 100644
--- a/blockjob.c
+++ b/blockjob.c
@@ -321,6 +321,7 @@ void block_job_start(BlockJob *job)
     job->pause_count--;
     job->busy = true;
     job->paused = false;
+    job->status = BLOCK_JOB_STATUS_RUNNING;
     bdrv_coroutine_enter(blk_bs(job->blk), job->co);
 }
 
@@ -601,6 +602,10 @@ BlockJobInfo *block_job_query(BlockJob *job, Error **errp)
     info->speed     = job->speed;
     info->io_status = job->iostatus;
     info->ready     = job->ready;
+    if (job->manual) {
+        info->has_status = true;
+        info->status = job->status;
+    }
     return info;
 }
 
@@ -704,6 +709,7 @@ void *block_job_create(const char *job_id, const 
BlockJobDriver *driver,
     job->pause_count   = 1;
     job->refcnt        = 1;
     job->manual        = manual;
+    job->status        = 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);
@@ -808,9 +814,12 @@ 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 = BLOCK_JOB_STATUS_PAUSED;
         job->paused = true;
         block_job_do_yield(job, -1);
         job->paused = false;
+        job->status = status;
     }
 
     if (job->driver->resume) {
@@ -916,6 +925,7 @@ void block_job_iostatus_reset(BlockJob *job)
 
 void block_job_event_ready(BlockJob *job)
 {
+    job->status = BLOCK_JOB_STATUS_READY;
     job->ready = true;
 
     if (block_job_is_internal(job)) {
diff --git a/include/block/blockjob.h b/include/block/blockjob.h
index b94d0c9fa6..d8e7df7e6e 100644
--- a/include/block/blockjob.h
+++ b/include/block/blockjob.h
@@ -146,6 +146,10 @@ typedef struct BlockJob {
      */
     bool manual;
 
+    /* Current state, using 2.12+ state names
+     */
+    BlockJobStatus status;
+
     /** Non-NULL if this job is part of a transaction */
     BlockJobTxn *txn;
     QLIST_ENTRY(BlockJob) txn_list;
diff --git a/qapi/block-core.json b/qapi/block-core.json
index 8225308904..eac89754c1 100644
--- a/qapi/block-core.json
+++ b/qapi/block-core.json
@@ -955,6 +955,18 @@
 { 'enum': 'BlockJobType',
   'data': ['commit', 'stream', 'mirror', 'backup'] }
 
+##
+# @BlockJobStatus:
+#
+# Block Job State
+#
+#
+#
+# Since: 2.12
+##
+{ 'enum': 'BlockJobStatus',
+  'data': ['undefined', 'created', 'running', 'paused', 'ready'] }
+
 ##
 # @BlockJobInfo:
 #
@@ -981,12 +993,15 @@
 #
 # @ready: true if the job may be completed (since 2.2)
 #
+# @status: Current job state/status (since 2.12)
+#
 # Since: 1.1
 ##
 { 'struct': 'BlockJobInfo',
   'data': {'type': 'str', 'device': 'str', 'len': 'int',
            'offset': 'int', 'busy': 'bool', 'paused': 'bool', 'speed': 'int',
-           'io-status': 'BlockDeviceIoStatus', 'ready': 'bool'} }
+           'io-status': 'BlockDeviceIoStatus', 'ready': 'bool',
+           '*status': 'BlockJobStatus' } }
 
 ##
 # @query-block-jobs:
-- 
2.14.3