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From: Eric Blake <eblake@redhat.com>
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Date: Thu, 30 Nov 2017 17:17:14 -0600
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Subject: Re: [Qemu-devel] [PATCH v4 12/20] qed: Switch to
 .bdrv_co_block_status()
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To: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>, qemu-devel@nongnu.org
Cc: kwolf@redhat.com, famz@redhat.com, qemu-block@nongnu.org, Max Reitz <mreitz@redhat.com>, Stefan Hajnoczi <stefanha@redhat.com>, jsnow@redhat.com

On 11/30/2017 04:27 AM, Vladimir Sementsov-Ogievskiy wrote:
> 12.10.2017 21:59, Eric Blake wrote:
>> We are gradually moving away from sector-based interfaces, towards
>> byte-based.=C2=A0 Update the qed driver accordingly, taking the opport=
unity
>> to inline qed_is_allocated_cb() into its lone caller (the callback
>> used to be important, until we switched qed to coroutines).=C2=A0 Ther=
e is
>> no intent to optimize based on the want_zero flag for this format.
>>
>> Signed-off-by: Eric Blake <eblake@redhat.com>
>>

>> =C2=A0 {
>> =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 BDRVQEDState *s =3D bs->opaque;
>> -=C2=A0=C2=A0=C2=A0 size_t len =3D (size_t)nb_sectors * BDRV_SECTOR_SI=
ZE;
>> -=C2=A0=C2=A0=C2=A0 QEDIsAllocatedCB cb =3D {
>> -=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 .bs =3D bs,
>> -=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 .pos =3D (uint64_t)sector_=
num * BDRV_SECTOR_SIZE,
>> -=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 .status =3D BDRV_BLOCK_OFF=
SET_MASK,
>> -=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 .pnum =3D pnum,
>> -=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 .file =3D file,
>> -=C2=A0=C2=A0=C2=A0 };
>> +=C2=A0=C2=A0=C2=A0 size_t len;
>=20
> size_t len =3D bytes;
>=20

Or rather, size_t len =3D MIN(bytes, SIZE_MAX); thanks to 32-bit platform=
s.

> with that:
> Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
>=20
>> +=C2=A0=C2=A0=C2=A0 int status;
>> =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 QEDRequest request =3D { .l2_table =3D =
NULL };
>> =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 uint64_t offset;
>> =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 int ret;
>>
>> =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 qemu_co_mutex_lock(&s->table_lock);
>> -=C2=A0=C2=A0=C2=A0 ret =3D qed_find_cluster(s, &request, cb.pos, &len=
, &offset);
>> -=C2=A0=C2=A0=C2=A0 qed_is_allocated_cb(&cb, ret, offset, len);
>> +=C2=A0=C2=A0=C2=A0 ret =3D qed_find_cluster(s, &request, pos, &len, &=
offset);
>=20
> len is in-out parameter, you can't use it uninitialized.

Good catch.

--=20
Eric Blake, Principal Software Engineer
Red Hat, Inc.           +1-919-301-3266
Virtualization:  qemu.org | libvirt.org