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> --- 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 9ab89cb..20d3ebd 100644 --- a/block/io.c +++ b/block/io.c @@ -1939,6 +1939,7 @@ 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, @@ -1956,13 +1957,14 @@ 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; } -- 2.9.3