mirrors
/
qemu
mirror of https://gitlab.com/qemu-project/qemu
1
0
Fork 0
Code Issues Packages Projects Releases Wiki Activity

backup: Copy only dirty areas 

The backup job must only copy areas that the copy_bitmap reports as
dirty.  This is always the case when using traditional non-offloading
backup, because it copies each cluster separately.  When offloading the
copy operation, we sometimes copy more than one cluster at a time, but
we only check whether the first one is dirty.

Therefore, whenever copy offloading is possible, the backup job
currently produces wrong output when the guest writes to an area of
which an inner part has already been backed up, because that inner part
will be re-copied.

Fixes: 9ded4a0114
Signed-off-by: Max Reitz <mreitz@redhat.com>
Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Message-id: 20190801173900.23851-2-mreitz@redhat.com
Cc: qemu-stable@nongnu.org
Signed-off-by: Max Reitz <mreitz@redhat.com>
This commit is contained in:
Max Reitz 2019-08-01 19:38:59 +02:00
parent 9bb68d34dd
commit 4a5b91ca02
1 changed files with 11 additions and 2 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

13
block/backup.c
View File

@ -202,22 +202,31 @@ static int coroutine_fn backup_do_cow(BackupBlockJob *job,
cow_request_begin(&cow_request, job, start, end);
while (start < end) {
int64_t dirty_end;
if (!hbitmap_get(job->copy_bitmap, start)) {
trace_backup_do_cow_skip(job, start);
start += job->cluster_size;
continue; /* already copied */
}
dirty_end = hbitmap_next_zero(job->copy_bitmap, start, (end - start));
if (dirty_end < 0) {
dirty_end = end;
}
trace_backup_do_cow_process(job, start);
if (job->use_copy_range) {
ret = backup_cow_with_offload(job, start, end, is_write_notifier);
ret = backup_cow_with_offload(job, start, dirty_end,
is_write_notifier);
if (ret < 0) {
job->use_copy_range = false;
}
}
if (!job->use_copy_range) {
ret = backup_cow_with_bounce_buffer(job, start, end, is_write_notifier,
ret = backup_cow_with_bounce_buffer(job, start, dirty_end,
is_write_notifier,
error_is_read, &bounce_buffer);
}
if (ret < 0) {