[Qemu-block] [PATCH v2 4/5] block/backup: Pack Notifier within BackupBlockJob

[John Snow]

Instead of relying on peeking at bs->job, we want to explicitly get
a reference to the job that was involved in this notifier callback.

Pack the Notifier inside of the BackupBlockJob so we can use
container_of to get a reference back to the BackupBlockJob object.

This cuts out one more case where we rely unnecessarily on bs->job.

Suggested-by: Paolo Bonzini <address@hidden>
Signed-off-by: John Snow <address@hidden>
---
 block/backup.c | 20 +++++++++++---------
 1 file changed, 11 insertions(+), 9 deletions(-)

diff --git a/block/backup.c b/block/backup.c
index ce96b45..735cbe6 100644
--- a/block/backup.c
+++ b/block/backup.c
@@ -46,6 +46,7 @@ typedef struct BackupBlockJob {
     CoRwlock flush_rwlock;
     uint64_t sectors_read;
     HBitmap *bitmap;
+    NotifierWithReturn before_write;
     QLIST_HEAD(, CowRequest) inflight_reqs;
 } BackupBlockJob;
 
@@ -87,11 +88,11 @@ static void cow_request_end(CowRequest *req)
 }
 
 static int coroutine_fn backup_do_cow(BlockDriverState *bs,
+                                      BackupBlockJob *job,
                                       int64_t sector_num, int nb_sectors,
                                       bool *error_is_read,
                                       bool is_write_notifier)
 {
-    BackupBlockJob *job = (BackupBlockJob *)bs->job;
     CowRequest cow_request;
     struct iovec iov;
     QEMUIOVector bounce_qiov;
@@ -189,6 +190,7 @@ static int coroutine_fn backup_before_write_notify(
         NotifierWithReturn *notifier,
         void *opaque)
 {
+    BackupBlockJob *job = container_of(notifier, BackupBlockJob, before_write);
     BdrvTrackedRequest *req = opaque;
     int64_t sector_num = req->offset >> BDRV_SECTOR_BITS;
     int nb_sectors = req->bytes >> BDRV_SECTOR_BITS;
@@ -196,7 +198,8 @@ static int coroutine_fn backup_before_write_notify(
     assert((req->offset & (BDRV_SECTOR_SIZE - 1)) == 0);
     assert((req->bytes & (BDRV_SECTOR_SIZE - 1)) == 0);
 
-    return backup_do_cow(req->bs, sector_num, nb_sectors, NULL, true);
+    return backup_do_cow(req->bs, job, sector_num,
+                         nb_sectors, NULL, true);
 }
 
 static void backup_set_speed(BlockJob *job, int64_t speed, Error **errp)
@@ -344,7 +347,8 @@ static int coroutine_fn 
backup_run_incremental(BackupBlockJob *job)
                 if (yield_and_check(job)) {
                     return ret;
                 }
-                ret = backup_do_cow(bs, cluster * BACKUP_SECTORS_PER_CLUSTER,
+                ret = backup_do_cow(bs, job,
+                                    cluster * BACKUP_SECTORS_PER_CLUSTER,
                                     BACKUP_SECTORS_PER_CLUSTER, &error_is_read,
                                     false);
                 if ((ret < 0) &&
@@ -380,9 +384,6 @@ static void coroutine_fn backup_run(void *opaque)
     BlockDriverState *bs = job->common.bs;
     BlockDriverState *target = job->target;
     BlockdevOnError on_target_error = job->on_target_error;
-    NotifierWithReturn before_write = {
-        .notify = backup_before_write_notify,
-    };
     int64_t start, end;
     int ret = 0;
 
@@ -400,7 +401,8 @@ static void coroutine_fn backup_run(void *opaque)
         blk_iostatus_enable(target->blk);
     }
 
-    bdrv_add_before_write_notifier(bs, &before_write);
+    job->before_write.notify = backup_before_write_notify;
+    bdrv_add_before_write_notifier(bs, &job->before_write);
 
     if (job->sync_mode == MIRROR_SYNC_MODE_NONE) {
         while (!block_job_is_cancelled(&job->common)) {
@@ -452,7 +454,7 @@ static void coroutine_fn backup_run(void *opaque)
                 }
             }
             /* FULL sync mode we copy the whole drive. */
-            ret = backup_do_cow(bs, start * BACKUP_SECTORS_PER_CLUSTER,
+            ret = backup_do_cow(bs, job, start * BACKUP_SECTORS_PER_CLUSTER,
                     BACKUP_SECTORS_PER_CLUSTER, &error_is_read, false);
             if (ret < 0) {
                 /* Depending on error action, fail now or retry cluster */
@@ -468,7 +470,7 @@ static void coroutine_fn backup_run(void *opaque)
         }
     }
 
-    notifier_with_return_remove(&before_write);
+    notifier_with_return_remove(&job->before_write);
 
     /* wait until pending backup_do_cow() calls have completed */
     qemu_co_rwlock_wrlock(&job->flush_rwlock);
-- 
2.4.3