On Fri, Sep 09, 2016 at 03:31:48PM +0300, Denis V. Lunev wrote: > bdrv_is_allocated_above() returns true in the case even for completel > zeroed areas as BDRV_BLOCK_ALLOCATED flag is set in both cases. > > The patch stops using bdrv_is_allocated_above() wrapper and switches to > bdrv_get_block_status_above() to distinguish zeroed areas and areas with > data to avoid extra IO operations if possible. > > Signed-off-by: Denis V. Lunev <d...@openvz.org> > CC: Stefan Hajnoczi <stefa...@redhat.com> > CC: Fam Zheng <f...@redhat.com> > CC: Kevin Wolf <kw...@redhat.com> > CC: Max Reitz <mre...@redhat.com> > CC: Jeff Cody <jc...@redhat.com> > --- > block/mirror.c | 18 ++++++++++++------ > 1 file changed, 12 insertions(+), 6 deletions(-) > > diff --git a/block/mirror.c b/block/mirror.c > index e0b3f41..da55375 100644 > --- a/block/mirror.c > +++ b/block/mirror.c > @@ -548,14 +548,15 @@ static void mirror_throttle(MirrorBlockJob *s) > > static int coroutine_fn mirror_dirty_init(MirrorBlockJob *s) > { > - int64_t sector_num, end; > + int64_t sector_num, end, alloc_mask; > BlockDriverState *base = s->base; > BlockDriverState *bs = blk_bs(s->common.blk); > BlockDriverState *target_bs = blk_bs(s->target); > - int ret, n; > + int n; > > end = s->bdev_length / BDRV_SECTOR_SIZE; > > + alloc_mask = BDRV_BLOCK_ALLOCATED; > if (base == NULL && !bdrv_has_zero_init(target_bs)) { > if (!bdrv_can_write_zeroes_with_unmap(target_bs)) { > bdrv_set_dirty_bitmap(s->dirty_bitmap, 0, end); > @@ -583,6 +584,8 @@ static int coroutine_fn mirror_dirty_init(MirrorBlockJob > *s) > } > > mirror_drain(s); > + > + alloc_mask = BDRV_BLOCK_DATA;
What about when base == NULL, and bdrv_has_zero_init(target_bs) == true? In that case we also know the target image is zeroed, but this does not take advantage of that. > } > > /* First part, loop on the sectors and initialize the dirty bitmap. */ > @@ -590,6 +593,8 @@ static int coroutine_fn mirror_dirty_init(MirrorBlockJob > *s) > /* Just to make sure we are not exceeding int limit. */ > int nb_sectors = MIN(INT_MAX >> BDRV_SECTOR_BITS, > end - sector_num); > + int64_t status; > + BlockDriverState *file; > > mirror_throttle(s); > > @@ -597,13 +602,14 @@ static int coroutine_fn > mirror_dirty_init(MirrorBlockJob *s) > return 0; > } > > - ret = bdrv_is_allocated_above(bs, base, sector_num, nb_sectors, &n); > - if (ret < 0) { > - return ret; > + status = bdrv_get_block_status_above(bs, base, sector_num, > + nb_sectors, &n, &file); > + if (status < 0) { > + return status; > } > > assert(n > 0); > - if (ret == 1) { > + if (status & alloc_mask) { > bdrv_set_dirty_bitmap(s->dirty_bitmap, sector_num, n); > } > sector_num += n; -Jeff