From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:32908) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1XctuJ-0006uo-1H for qemu-devel@nongnu.org; Sat, 11 Oct 2014 06:28:15 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1XctuC-0007OV-28 for qemu-devel@nongnu.org; Sat, 11 Oct 2014 06:28:14 -0400 Received: from mx1.redhat.com ([209.132.183.28]:24863) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1XctuB-0007OP-QG for qemu-devel@nongnu.org; Sat, 11 Oct 2014 06:28:08 -0400 Message-ID: <54390627.4010606@redhat.com> Date: Sat, 11 Oct 2014 12:27:51 +0200 From: Max Reitz MIME-Version: 1.0 References: <1409348463-16627-1-git-send-email-mreitz@redhat.com> <1409348463-16627-2-git-send-email-mreitz@redhat.com> <20141010122928.GD22893@nodalink.com> In-Reply-To: <20141010122928.GD22893@nodalink.com> Content-Type: text/plain; charset=windows-1252; format=flowed Content-Transfer-Encoding: quoted-printable Subject: Re: [Qemu-devel] [PATCH v5 01/11] qcow2: Calculate refcount block entry count List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: =?windows-1252?Q?Beno=EEt_Canet?= Cc: Kevin Wolf , qemu-devel@nongnu.org, Stefan Hajnoczi Am 10.10.2014 um 14:29 schrieb Beno=EEt Canet: > On Fri, Aug 29, 2014 at 11:40:53PM +0200, Max Reitz wrote: >> The size of a refblock entry is (in theory) variable; calculate >> therefore the number of entries per refblock and the according bit shi= ft >> (1 << x =3D=3D entry count) when opening an image. >> >> Signed-off-by: Max Reitz >> --- >> block/qcow2.c | 2 ++ >> block/qcow2.h | 2 ++ >> 2 files changed, 4 insertions(+) >> >> diff --git a/block/qcow2.c b/block/qcow2.c >> index f9e045f..172ad00 100644 >> --- a/block/qcow2.c >> +++ b/block/qcow2.c >> @@ -689,6 +689,8 @@ static int qcow2_open(BlockDriverState *bs, QDict = *options, int flags, >> =20 >> s->l2_bits =3D s->cluster_bits - 3; /* L2 is always one cluster = */ >> s->l2_size =3D 1 << s->l2_bits; >> + s->refcount_block_bits =3D s->cluster_bits - (s->refcount_order -= 3); > After carefull examination (s->refcount_order - 3) =3D=3D REFCOUNT_SHIF= T. > Why not also creating s->refcount_shift and make use of it in order to = avoid > torturing the mind of the next reader. I'm sorry. *g* Well, I'm against creating s->refcount_shift, because that name implies=20 you could use it for shifts. But you shouldn't do that, because it may=20 be both negative and positive. > Or simply recall in a comment that there is 2^3 bits in a byte. I like this more. :-) Max > Best regards > > Beno=EEt > >> + s->refcount_block_size =3D 1 << s->refcount_block_bits; >> bs->total_sectors =3D header.size / 512; >> s->csize_shift =3D (62 - (s->cluster_bits - 8)); >> s->csize_mask =3D (1 << (s->cluster_bits - 8)) - 1; >> diff --git a/block/qcow2.h b/block/qcow2.h >> index 6aeb7ea..7c01fb7 100644 >> --- a/block/qcow2.h >> +++ b/block/qcow2.h >> @@ -222,6 +222,8 @@ typedef struct BDRVQcowState { >> int l2_size; >> int l1_size; >> int l1_vm_state_index; >> + int refcount_block_bits; >> + int refcount_block_size; >> int csize_shift; >> int csize_mask; >> uint64_t cluster_offset_mask; >> --=20 >> 2.1.0 >>