Am 19.09.2023 um 18:58 hat Andrey Drobyshev geschrieben: > Add @chsize param to the function which, if non-zero, would represent > the chunk size to be used for comparison. If it's zero, then > BDRV_SECTOR_SIZE is used as default chunk size, which is the previous > behaviour. > > In particular, we're going to use this param in img_rebase() to make the > write requests aligned to a predefined alignment value. > > Signed-off-by: Andrey Drobyshev <andrey.drobys...@virtuozzo.com> > Reviewed-by: Eric Blake <ebl...@redhat.com> > Reviewed-by: Hanna Czenczek <hre...@redhat.com> > --- > qemu-img.c | 24 +++++++++++++++--------- > 1 file changed, 15 insertions(+), 9 deletions(-) > > diff --git a/qemu-img.c b/qemu-img.c > index 4dc91505bf..0f67b021f7 100644 > --- a/qemu-img.c > +++ b/qemu-img.c > @@ -1274,23 +1274,29 @@ static int is_allocated_sectors_min(const uint8_t > *buf, int n, int *pnum, > } > > /* > - * Compares two buffers sector by sector. Returns 0 if the first > - * sector of each buffer matches, non-zero otherwise. > + * Compares two buffers chunk by chunk, where @chsize is the chunk size. > + * If @chsize is 0, default chunk size of BDRV_SECTOR_SIZE is used. > + * Returns 0 if the first chunk of each buffer matches, non-zero otherwise. > * > - * pnum is set to the sector-aligned size of the buffer prefix that > - * has the same matching status as the first sector. > + * @pnum is set to the size of the buffer prefix aligned to @chsize that > + * has the same matching status as the first chunk. > */ > static int compare_buffers(const uint8_t *buf1, const uint8_t *buf2, > - int64_t bytes, int64_t *pnum) > + int64_t bytes, uint64_t chsize, int64_t *pnum)
uint64_t might be too large, depending on the platform. memcmp() takes size_t, so in theory we can get truncation. I assume that we won't see a problem in practice because you'll never pass that large values, but I'd prefer making chsize size_t here. Kevin