Am 19.12.2019 um 10:24 hat Vladimir Sementsov-Ogievskiy geschrieben: > 10.12.2019 20:46, Kevin Wolf wrote: > > Am 22.11.2019 um 17:05 hat Kevin Wolf geschrieben: > >> See patch 4 for the description of the bug fixed. > > > > I'm applying patches 3 and 5-7 to the block branch because they make > > sense on their own. > > > > The real fix will need another approach because the error handling is > > broken in this one: If zeroing out fails (either because of NO_FALLBACK > > or because of some other I/O error), bdrv_co_truncate() will return > > failure, but the image size has already been increased, with potentially > > incorrect data in the new area. > > > > To fix this, we need to make sure that zeros will be read before we > > commit the new image size to the image file (e.g. qcow2 header) and to > > bs->total_sectors. In other words, it must become the responsibility of > > the block driver. > > > > To this effect, I'm planning to introduce a PREALLOC_MODE_ZERO_INIT flag > > that can be or'ed to the preallocation mode. This will fail by default > > because it looks like just another unimplemented preallocation mode to > > block drivers. It will be requested explicitly by commit jobs and > > automatically added by bdrv_co_truncate() if the backing file would > > become visible (like in this series, but now for all preallocation > > modes). I'm planning to implement it for qcow2 and file-posix for now, > > which should cover most interesting cases. > > > > Does this make sense to you? > > This should work. Do you still have this plan in a timeline?
Still planning to do this, but tomorrow is my last working day for this year. So I guess I'll get to it sometime in January. Kevin
