On 04.07.19 19:43, Max Reitz wrote: > On 03.07.19 23:55, John Snow wrote: >> This adds an "always" policy for bitmap synchronization. Regardless of if >> the job succeeds or fails, the bitmap is *always* synchronized. This means >> that for backups that fail part-way through, the bitmap retains a record of >> which sectors need to be copied out to accomplish a new backup using the >> old, partial result. >> >> In effect, this allows us to "resume" a failed backup; however the new backup >> will be from the new point in time, so it isn't a "resume" as much as it is >> an "incremental retry." This can be useful in the case of extremely large >> backups that fail considerably through the operation and we'd like to not >> waste >> the work that was already performed. >> >> Signed-off-by: John Snow <js...@redhat.com> >> --- >> block/backup.c | 25 +++++++++++++++++-------- >> qapi/block-core.json | 5 ++++- >> 2 files changed, 21 insertions(+), 9 deletions(-) >> >> diff --git a/block/backup.c b/block/backup.c >> index 9cc5a7f6ca..495d8f71aa 100644 >> --- a/block/backup.c >> +++ b/block/backup.c >> @@ -266,16 +266,25 @@ static void backup_cleanup_sync_bitmap(BackupBlockJob >> *job, int ret)
[...] >> + /* If we failed and synced, merge in the bits we didn't copy: */ >> + bdrv_dirty_bitmap_merge_internal(bm, job->copy_bitmap, >> + NULL, true); > > I presume this is for sync=full? Ah, no. This is necessary because the original sync bitmap was discarded by bdrv_dirty_bitmap_abdicate(). So yep, these bits need to go back into the sync bitmap then. Max
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