John Snow <js...@redhat.com> writes: > On 08/07/2017 10:45 AM, Markus Armbruster wrote: >> Block dirty bitmaps represent granularity in bytes as uint32_t. It >> must be a power of two and a multiple of BDRV_SECTOR_SIZE. >> >> The trouble with uint32_t is computations like this one in >> mirror_do_read(): >> >> uint64_t max_bytes; >> >> max_bytes = s->granularity * s->max_iov; >> >> The operands of * are uint32_t and int, so the product is computed in >> uint32_t (assuming 32 bit int), then zero-extended to uint64_t. >> >> Since granularity is generally combined with 64 bit file offsets, it's >> best to make it 64 bits, too. Less opportunity to screw up. >> >> Signed-off-by: Markus Armbruster <arm...@redhat.com> > > [bweeooop] > >> --- a/block/dirty-bitmap.c >> +++ b/block/dirty-bitmap.c > > [buuuuweeeep] > >> @@ -506,16 +506,11 @@ uint32_t >> bdrv_get_default_bitmap_granularity(BlockDriverState *bs) >> return granularity; >> } >> >> -uint32_t bdrv_dirty_bitmap_granularity(const BdrvDirtyBitmap *bitmap) >> +uint64_t bdrv_dirty_bitmap_granularity(const BdrvDirtyBitmap *bitmap) >> { >> return BDRV_SECTOR_SIZE << hbitmap_granularity(bitmap->bitmap); >> } >> >> -uint32_t bdrv_dirty_bitmap_meta_granularity(BdrvDirtyBitmap *bitmap) >> -{ >> - return BDRV_SECTOR_SIZE << hbitmap_granularity(bitmap->meta); >> -} > > Why? Unused? Not cool enough to mention?
I didn't feel like fixing an unused function, so I dropped it. Can mention this in the commit message.