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block/block-copy: fix progress calculation

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Assume we have two regions, A and B, and region B is in-flight now,
region A is not yet touched, but it is unallocated and should be
skipped.

Correspondingly, as progress we have

  total = A + B
  current = 0

If we reset unallocated region A and call progress_reset_callback,
it will calculate 0 bytes dirty in the bitmap and call
job_progress_set_remaining, which will set

   total = current + 0 = 0 + 0 = 0

So, B bytes are actually removed from total accounting. When job
finishes we'll have

   total = 0
   current = B

, which doesn't sound good.

This is because we didn't considered in-flight bytes, actually when
calculating remaining, we should have set (in_flight + dirty_bytes)
as remaining, not only dirty_bytes.

To fix it, let's refactor progress calculation, moving it to block-copy
itself instead of fixing callback. And, of course, track in_flight
bytes count.

We still have to keep one callback, to maintain backup job bytes_read
calculation, but it will go on soon, when we turn the whole backup
process into one block_copy call.

Cc: qemu-stable@nongnu.org
Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Reviewed-by: Andrey Shinkevich <andrey.shinkevich@virtuozzo.com>
Message-Id: <20200311103004.7649-3-vsementsov@virtuozzo.com>
Signed-off-by: Max Reitz <mreitz@redhat.com>
This commit is contained in:
Vladimir Sementsov-Ogievskiy 2020-03-11 13:29:57 +03:00 • committed by Max Reitz
parent 01fe1ca945
commit d0ebeca14a
3 changed files with 19 additions and 25 deletions
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13
block/backup.c
View file

@ -57,15 +57,6 @@ static void backup_progress_bytes_callback(int64_t bytes, void *opaque)
BackupBlockJob *s = opaque;
s->bytes_read += bytes;
job_progress_update(&s->common.job, bytes);
}
static void backup_progress_reset_callback(void *opaque)
{
BackupBlockJob *s = opaque;
uint64_t estimate = bdrv_get_dirty_count(s->bcs->copy_bitmap);
job_progress_set_remaining(&s->common.job, estimate);
}
static int coroutine_fn backup_do_cow(BackupBlockJob *job,
@ -464,8 +455,8 @@ BlockJob *backup_job_create(const char *job_id, BlockDriverState *bs,
job->cluster_size = cluster_size;
job->len = len;
block_copy_set_callbacks(bcs, backup_progress_bytes_callback,
backup_progress_reset_callback, job);
block_copy_set_progress_callback(bcs, backup_progress_bytes_callback, job);
block_copy_set_progress_meter(bcs, &job->common.job.progress);
/* Required permissions are already taken by backup-top target */
block_job_add_bdrv(&job->common, "target", target, 0, BLK_PERM_ALL,