06.03.2019 18:59, John Snow wrote: > > > On 3/6/19 7:58 AM, Eric Blake wrote: >> On 3/5/19 5:43 PM, John Snow wrote: >>> Usually, we only write out bitmaps when we're about to close out the file, >>> so we always remove the bitmaps after to make it easier to determine the >>> source of truth for migration purposes. >>> >>> However, there may be times we want to flush bitmap data more aggressively, >>> like after a truncate event where we need to make the metadata consistent >>> again. >> >> Or, as I've mentioned in other threads, after every >> bitmap-add/bitmap-delete operation, so that 'qemu-img info -U' can see >> which persistent bitmaps exist. But that's one step further than this >> series, so I won't insist on it today. >> > > Yes, I was keeping that in mind as I wrote this. I think it extends to > those cases trivially, so long as Vladimir is OK with what I'm trying to do. >
I still don't see the point of flushing bitmaps, the only thing is optimizing qemu-img info --force-share, which should never used except for debugging. So, at least, if we'll have it, I'd prefer bitmap flushing to be optional, and other code should not rely on it. -- Best regards, Vladimir
