On Tue, Jun 27, 2017 at 02:24:57PM -0500, Eric Blake wrote: > bdrv_is_allocated_above() was relying on intermediate->total_sectors, > which is a field that can have stale contents depending on the value > of intermediate->has_variable_length. An audit shows that we are safe > (we were first calling through bdrv_co_get_block_status() which in > turn calls bdrv_nb_sectors() and therefore just refreshed the current > length), but it's nicer to favor our accessor functions to avoid having > to repeat such an audit, even if it means refresh_total_sectors() is > called more frequently. > > Suggested-by: John Snow <js...@redhat.com> > Signed-off-by: Eric Blake <ebl...@redhat.com> >
Reviewed-by: Jeff Cody <jc...@redhat.com> > --- > v2: new patch > --- > block/io.c | 12 +++++++----- > 1 file changed, 7 insertions(+), 5 deletions(-) > > diff --git a/block/io.c b/block/io.c > index 0545180..5bbf153 100644 > --- a/block/io.c > +++ b/block/io.c > @@ -1924,6 +1924,7 @@ int bdrv_is_allocated_above(BlockDriverState *top, > intermediate = top; > while (intermediate && intermediate != base) { > int64_t pnum_inter; > + int64_t size_inter; > int psectors_inter; > > ret = bdrv_is_allocated(intermediate, sector_num * BDRV_SECTOR_SIZE, > @@ -1941,13 +1942,14 @@ int bdrv_is_allocated_above(BlockDriverState *top, > > /* > * [sector_num, nb_sectors] is unallocated on top but intermediate > - * might have > - * > - * [sector_num+x, nr_sectors] allocated. > + * might have [sector_num+x, nb_sectors-x] allocated. > */ > + size_inter = bdrv_nb_sectors(intermediate); > + if (size_inter < 0) { > + return size_inter; > + } > if (n > psectors_inter && > - (intermediate == top || > - sector_num + psectors_inter < intermediate->total_sectors)) { > + (intermediate == top || sector_num + psectors_inter < > size_inter)) { > n = psectors_inter; > } > > -- > 2.9.4 > >