From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:45293) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1XgWUN-0006g5-2C for qemu-devel@nongnu.org; Tue, 21 Oct 2014 06:16:32 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1XgWUH-0003ET-Ug for qemu-devel@nongnu.org; Tue, 21 Oct 2014 06:16:27 -0400 Received: from mx1.redhat.com ([209.132.183.28]:33911) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1XgWUH-0003EN-ND for qemu-devel@nongnu.org; Tue, 21 Oct 2014 06:16:21 -0400 Message-ID: <5446326E.7080500@redhat.com> Date: Tue, 21 Oct 2014 12:16:14 +0200 From: Max Reitz MIME-Version: 1.0 References: <1413815733-22829-1-git-send-email-mreitz@redhat.com> <1413815733-22829-10-git-send-email-mreitz@redhat.com> <20141021095937.GF4409@noname.redhat.com> In-Reply-To: <20141021095937.GF4409@noname.redhat.com> Content-Type: text/plain; charset=windows-1252; format=flowed Content-Transfer-Encoding: quoted-printable Subject: Re: [Qemu-devel] [PATCH v6 09/11] qcow2: Clean up after refcount rebuild List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Kevin Wolf Cc: qemu-devel@nongnu.org, Stefan Hajnoczi , =?windows-1252?Q?Beno=EEt_Canet?= On 2014-10-21 at 11:59, Kevin Wolf wrote: > Am 20.10.2014 um 16:35 hat Max Reitz geschrieben: >> Because the old refcount structure will be leaked after having rebuilt >> it, we need to recalculate the refcounts and run a leak-fixing operati= on >> afterwards (if leaks should be fixed at all). >> >> Signed-off-by: Max Reitz >> Reviewed-by: Beno=EEt Canet >> --- >> block/qcow2-refcount.c | 35 +++++++++++++++++++++++++++++++++++ >> 1 file changed, 35 insertions(+) >> >> diff --git a/block/qcow2-refcount.c b/block/qcow2-refcount.c >> index 75e726b..3730be2 100644 >> --- a/block/qcow2-refcount.c >> +++ b/block/qcow2-refcount.c >> @@ -1956,12 +1956,47 @@ int qcow2_check_refcounts(BlockDriverState *bs= , BdrvCheckResult *res, >> nb_clusters); >> =20 >> if (rebuild && (fix & BDRV_FIX_ERRORS)) { >> + BdrvCheckResult old_res =3D *res; >> + >> fprintf(stderr, "Rebuilding refcount structure\n"); >> ret =3D rebuild_refcount_structure(bs, res, &refcount_table, >> &nb_clusters); >> if (ret < 0) { >> goto fail; >> } >> + >> + res->corruptions =3D 0; >> + res->leaks =3D 0; >> + >> + /* Because the old reftable has been exchanged for a new one = the >> + * references have to be recalculated */ >> + rebuild =3D false; >> + memset(refcount_table, 0, nb_clusters * sizeof(uint16_t)); >> + ret =3D calculate_refcounts(bs, res, 0, &rebuild, &refcount_t= able, >> + &nb_clusters); >> + if (ret < 0) { >> + goto fail; >> + } >> + >> + if (fix & BDRV_FIX_LEAKS) { >> + /* The old refcount structures are now leaked, fix it; th= e result >> + * can be ignored */ >> + pre_compare_res =3D *res; > I would prefer using another local variable here. At the first sight > it's not quite clear which references to pre_compare_res correspond to > which state. Why not. >> + compare_refcounts(bs, res, BDRV_FIX_LEAKS, &rebuild, >> + &highest_cluster, refcount_table, nb_cl= usters); >> + if (rebuild) { >> + fprintf(stderr, "ERROR rebuilt refcount structure is = still " >> + "broken\n"); >> + } >> + *res =3D pre_compare_res; >> + } >> + >> + if (res->corruptions < old_res.corruptions) { >> + res->corruptions_fixed +=3D old_res.corruptions - res->co= rruptions; >> + } >> + if (res->leaks < old_res.leaks) { >> + res->leaks_fixed +=3D old_res.leaks - res->leaks; >> + } > For these numbers to be accurate, don't we need to run > compare_refcounts() unconditionally and only make BDRV_FIX_LEAKS > conditional? Actually, there is no difference, because at the point of this patch,=20 you cannot use BDRV_FIX_ERRORS without BDRV_FIX_LEAKS. But it'd be more=20 correct, right. Thanks, Max > Now that I've read the rest of the series, comparing res and old_res > actually makes sense, so maybe it's not necessary to introduce a > Qcow2CheckResult. > >> } else if (fix) { >> if (rebuild) { >> fprintf(stderr, "ERROR need to rebuild refcount structur= es\n"); >> --=20 >> 2.1.2 > Kevin