From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:54019) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1YxB4d-0005gt-VJ for qemu-devel@nongnu.org; Tue, 26 May 2015 05:23:01 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1YxB4Z-0007ci-0D for qemu-devel@nongnu.org; Tue, 26 May 2015 05:22:59 -0400 Message-ID: <55643B5B.4000905@redhat.com> Date: Tue, 26 May 2015 11:22:35 +0200 From: Paolo Bonzini MIME-Version: 1.0 References: <1432611383-3779-1-git-send-email-famz@redhat.com> <1432611383-3779-2-git-send-email-famz@redhat.com> In-Reply-To: <1432611383-3779-2-git-send-email-famz@redhat.com> Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: quoted-printable Subject: Re: [Qemu-devel] [PATCH v5 1/8] block: Add bdrv_get_block_status_above List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Fam Zheng , qemu-devel@nongnu.org Cc: Kevin Wolf , qemu-block@nongnu.org, Jeff Cody , qemu-stable@nongnu.org, Stefan Hajnoczi , jsnow@redhat.com, wangxiaolong@ucloud.cn On 26/05/2015 05:36, Fam Zheng wrote: > Like bdrv_is_allocated_above, this function follows the backing chain u= ntil seeing > BDRV_BLOCK_ALLOCATED. Base is not included. >=20 > Reimplement bdrv_is_allocated on top. >=20 > Signed-off-by: Fam Zheng > --- > block/io.c | 53 ++++++++++++++++++++++++++++++++++++++++---= -------- > include/block/block.h | 4 ++++ > 2 files changed, 46 insertions(+), 11 deletions(-) >=20 > diff --git a/block/io.c b/block/io.c > index e394d92..a0d9990 100644 > --- a/block/io.c > +++ b/block/io.c > @@ -1560,28 +1560,51 @@ static int64_t coroutine_fn bdrv_co_get_block_s= tatus(BlockDriverState *bs, > return ret; > } > =20 > -/* Coroutine wrapper for bdrv_get_block_status() */ > -static void coroutine_fn bdrv_get_block_status_co_entry(void *opaque) > +static int64_t coroutine_fn bdrv_co_get_block_status_above(BlockDriver= State *bs, > + BlockDriverState *base, > + int64_t sector_num, > + int nb_sectors, > + int *pnum) > +{ > + BlockDriverState *p; > + int64_t ret; > + > + assert(bs !=3D base); > + for (p =3D bs; p !=3D base; p =3D p->backing_hd) { > + ret =3D bdrv_co_get_block_status(p, sector_num, nb_sectors, pn= um); Since pnum is an output parameter only, *pnum will be set by the last call in the loop. This is not what bdrv_is_allocated_above does: you have to set *pnum (roughly) to the _smallest_ value returned by the calls. Consider this case (base =3D=3D NULL, bs->backing_hd->backing_hd =3D=3D NULL): 1 2 3 123456789012345678901234567890 bs ...........AAAAAAAAAAAA....... bs->backing_hd ...............AAAAAAAAAAAAAAA Your code would return *pnum =3D=3D 15, but the right result is *pnum =3D= =3D 11. Paolo > + if (ret < 0 || ret & BDRV_BLOCK_ALLOCATED) { > + break; > + } > + } > + return ret; > +} > + > +/* Coroutine wrapper for bdrv_get_block_status_above() */ > +static void coroutine_fn bdrv_get_block_status_above_co_entry(void *op= aque) > { > BdrvCoGetBlockStatusData *data =3D opaque; > - BlockDriverState *bs =3D data->bs; > =20 > - data->ret =3D bdrv_co_get_block_status(bs, data->sector_num, data-= >nb_sectors, > - data->pnum); > + data->ret =3D bdrv_co_get_block_status_above(data->bs, data->base, > + data->sector_num, > + data->nb_sectors, > + data->pnum); > data->done =3D true; > } > =20 > /* > - * Synchronous wrapper around bdrv_co_get_block_status(). > + * Synchronous wrapper around bdrv_co_get_block_status_above(). > * > - * See bdrv_co_get_block_status() for details. > + * See bdrv_co_get_block_status_above() for details. > */ > -int64_t bdrv_get_block_status(BlockDriverState *bs, int64_t sector_num= , > - int nb_sectors, int *pnum) > +int64_t bdrv_get_block_status_above(BlockDriverState *bs, > + BlockDriverState *base, > + int64_t sector_num, > + int nb_sectors, int *pnum) > { > Coroutine *co; > BdrvCoGetBlockStatusData data =3D { > .bs =3D bs, > + .base =3D base, > .sector_num =3D sector_num, > .nb_sectors =3D nb_sectors, > .pnum =3D pnum, > @@ -1590,11 +1613,11 @@ int64_t bdrv_get_block_status(BlockDriverState = *bs, int64_t sector_num, > =20 > if (qemu_in_coroutine()) { > /* Fast-path if already in coroutine context */ > - bdrv_get_block_status_co_entry(&data); > + bdrv_get_block_status_above_co_entry(&data); > } else { > AioContext *aio_context =3D bdrv_get_aio_context(bs); > =20 > - co =3D qemu_coroutine_create(bdrv_get_block_status_co_entry); > + co =3D qemu_coroutine_create(bdrv_get_block_status_above_co_en= try); > qemu_coroutine_enter(co, &data); > while (!data.done) { > aio_poll(aio_context, true); > @@ -1603,6 +1626,14 @@ int64_t bdrv_get_block_status(BlockDriverState *= bs, int64_t sector_num, > return data.ret; > } > =20 > +int64_t bdrv_get_block_status(BlockDriverState *bs, > + int64_t sector_num, > + int nb_sectors, int *pnum) > +{ > + return bdrv_get_block_status_above(bs, bs->backing_hd, > + sector_num, nb_sectors, pnum); > +} > + > int coroutine_fn bdrv_is_allocated(BlockDriverState *bs, int64_t secto= r_num, > int nb_sectors, int *pnum) > { > diff --git a/include/block/block.h b/include/block/block.h > index c1c963e..8a13bed 100644 > --- a/include/block/block.h > +++ b/include/block/block.h > @@ -361,6 +361,10 @@ bool bdrv_unallocated_blocks_are_zero(BlockDriverS= tate *bs); > bool bdrv_can_write_zeroes_with_unmap(BlockDriverState *bs); > int64_t bdrv_get_block_status(BlockDriverState *bs, int64_t sector_num= , > int nb_sectors, int *pnum); > +int64_t bdrv_get_block_status_above(BlockDriverState *bs, > + BlockDriverState *base, > + int64_t sector_num, > + int nb_sectors, int *pnum); > int bdrv_is_allocated(BlockDriverState *bs, int64_t sector_num, int nb= _sectors, > int *pnum); > int bdrv_is_allocated_above(BlockDriverState *top, BlockDriverState *b= ase, >=20