[pve-devel] [PATCH] PVE: fix and clean up error handling for create_backup_jobs

[Stefan Reiter <s.reiter@proxmox.com>]

No more weird bool returns, just the standard "errp" format used
everywhere else too. With this, if backup_job_create fails, the error
message is actually returned over QMP and can be shown to the user.

Also add a job_cancel_sync before job_unref, since a job must be in
STATUS_NULL to be deleted by unref, which could trigger an assert
before.

Signed-off-by: Stefan Reiter <s.reiter@proxmox.com>
---

Another small fix, which went under the radar since testing error handling is
obviously unnecessary considering our code is perfect and never fails ;)

 pve-backup.c | 23 ++++++++++-------------
 1 file changed, 10 insertions(+), 13 deletions(-)

diff --git a/pve-backup.c b/pve-backup.c
index af2db0d4b9..1a013afd89 100644
--- a/pve-backup.c
+++ b/pve-backup.c
@@ -450,7 +450,7 @@ static int coroutine_fn pvebackup_co_add_config(
  * struct and starting the jobs, and from within a QMP call. This means that no
  * other QMP call can interrupt, and no background job is running yet.
  */
-static bool create_backup_jobs(void) {
+static void create_backup_jobs(Error **errp) {
 
     assert(!qemu_in_coroutine());
 
@@ -487,12 +487,9 @@ static bool create_backup_jobs(void) {
 
         aio_context_release(aio_context);
 
-        if (!job || local_err != NULL) {
-            Error *create_job_err = NULL;
-            error_setg(&create_job_err, "backup_job_create failed: %s",
+        if (!job || *errp != NULL) {
+            error_setg(errp, "backup_job_create failed: %s",
                        local_err ? error_get_pretty(local_err) : "null");
-
-            pvebackup_propagate_error(create_job_err);
             break;
         }
 
@@ -502,9 +499,7 @@ static bool create_backup_jobs(void) {
         di->target = NULL;
     }
 
-    bool errors = pvebackup_error_or_canceled();
-
-    if (errors) {
+    if (*errp) {
         l = backup_state.di_list;
         while (l) {
             PVEBackupDevInfo *di = (PVEBackupDevInfo *)l->data;
@@ -516,12 +511,14 @@ static bool create_backup_jobs(void) {
             }
 
             if (di->job) {
+                AioContext *ctx = di->job->job.aio_context;
+                aio_context_acquire(ctx);
+                job_cancel_sync(&di->job->job);
                 job_unref(&di->job->job);
+                aio_context_release(ctx);
             }
         }
     }
-
-    return errors;
 }
 
 typedef struct QmpBackupTask {
@@ -1002,9 +999,9 @@ UuidInfo *qmp_backup(
     block_on_coroutine_fn(pvebackup_co_prepare, &task);
 
     if (*errp == NULL) {
-        bool errors = create_backup_jobs();
+        create_backup_jobs(errp);
 
-        if (!errors) {
+        if (*errp == NULL) {
             // start the first job in the transaction
             job_txn_start_seq(backup_state.txn);
         }
-- 
2.20.1