From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from list by lists.gnu.org with archive (Exim 4.71) id 1Xgud9-0000lw-TU for mharc-qemu-trivial@gnu.org; Wed, 22 Oct 2014 08:03:07 -0400 Received: from eggs.gnu.org ([2001:4830:134:3::10]:41246) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1Xgud4-0000kF-2b for qemu-trivial@nongnu.org; Wed, 22 Oct 2014 08:03:06 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1Xgucu-0003jW-Dv for qemu-trivial@nongnu.org; Wed, 22 Oct 2014 08:03:02 -0400 Received: from mx1.redhat.com ([209.132.183.28]:2129) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1Xgucu-0003i9-6N; Wed, 22 Oct 2014 08:02:52 -0400 Received: from int-mx13.intmail.prod.int.phx2.redhat.com (int-mx13.intmail.prod.int.phx2.redhat.com [10.5.11.26]) by mx1.redhat.com (8.14.4/8.14.4) with ESMTP id s9MC2lmw024335 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=FAIL); Wed, 22 Oct 2014 08:02:48 -0400 Received: from dresden.str.redhat.com (dhcp-192-247.str.redhat.com [10.33.192.247]) by int-mx13.intmail.prod.int.phx2.redhat.com (8.14.4/8.14.4) with ESMTP id s9MC2jbZ006475 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES128-SHA bits=128 verify=NO); Wed, 22 Oct 2014 08:02:46 -0400 Message-ID: <54479CE5.7040406@redhat.com> Date: Wed, 22 Oct 2014 14:02:45 +0200 From: Max Reitz User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:31.0) Gecko/20100101 Thunderbird/31.2.0 MIME-Version: 1.0 To: Gonglei , Zhang Haoyu References: <201410221945053926307@sangfor.com> <54479C3E.1070803@huawei.com> <54479C8A.9000407@redhat.com> In-Reply-To: <54479C8A.9000407@redhat.com> Content-Type: text/plain; charset=windows-1252; format=flowed Content-Transfer-Encoding: 7bit X-Scanned-By: MIMEDefang 2.68 on 10.5.11.26 X-detected-operating-system: by eggs.gnu.org: GNU/Linux 3.x X-Received-From: 209.132.183.28 Cc: qemu-trivial , Kevin Wolf , qemu-devel , Stefan Hajnoczi Subject: Re: [Qemu-trivial] [Qemu-devel] [PATCH v4] snapshot: use local variable to bdrv_pwrite_sync L1 table X-BeenThere: qemu-trivial@nongnu.org X-Mailman-Version: 2.1.14 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Wed, 22 Oct 2014 12:03:06 -0000 On 2014-10-22 at 14:01, Max Reitz wrote: > On 2014-10-22 at 13:59, Gonglei wrote: >> On 2014/10/22 19:45, Zhang Haoyu wrote: >> >>> Use local variable to bdrv_pwrite_sync L1 table, >>> needless to make conversion of cached L1 table between >>> big-endian and host style. >>> >>> Signed-off-by: Zhang Haoyu >>> Reviewed-by: Max Reitz >>> --- >>> v3 -> v4: >>> - convert local L1 table to host-style before copy it >>> back to s->l1_table >>> >>> v2 -> v3: >>> - replace g_try_malloc0 with qemu_try_blockalign >>> - copy the latest local L1 table back to s->l1_table >>> after successfully bdrv_pwrite_sync L1 table >>> >>> v1 -> v2: >>> - remove the superflous assignment, l1_table = NULL; >>> - replace 512 with BDRV_SECTOR_SIZE, and align_offset with ROUND_UP >>> - remove needless check of if (l1_table) before g_free(l1_table) >>> >>> block/qcow2-refcount.c | 28 ++++++++++++---------------- >>> 1 file changed, 12 insertions(+), 16 deletions(-) >>> >>> diff --git a/block/qcow2-refcount.c b/block/qcow2-refcount.c >>> index 2bcaaf9..3e4050a 100644 >>> --- a/block/qcow2-refcount.c >>> +++ b/block/qcow2-refcount.c >>> @@ -881,14 +881,17 @@ int >>> qcow2_update_snapshot_refcount(BlockDriverState *bs, >>> { >>> BDRVQcowState *s = bs->opaque; >>> uint64_t *l1_table, *l2_table, l2_offset, offset, l1_size2; >>> - bool l1_allocated = false; >>> int64_t old_offset, old_l2_offset; >>> int i, j, l1_modified = 0, nb_csectors, refcount; >>> int ret; >>> l2_table = NULL; >>> - l1_table = NULL; >>> l1_size2 = l1_size * sizeof(uint64_t); >>> + l1_table = qemu_try_blockalign(bs->file, l1_size2); >>> + if (l1_size2 && l1_table == NULL) { >> I think this check has a logic problem. If l1_size2 != 0 and >> l1_table == NULL, >> What will happen? > > Then this condition is met and you return with -ENOMEM...? Oh, but I see something different: qemu_try_blockalign() never returns NULL, not even when you request 0 bytes. Therefore, just "if (l1_table == NULL)" is sufficient. Max From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:41276) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1XgudD-0000pg-5Z for qemu-devel@nongnu.org; Wed, 22 Oct 2014 08:03:15 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1Xgud8-0003nG-KE for qemu-devel@nongnu.org; Wed, 22 Oct 2014 08:03:11 -0400 Message-ID: <54479CE5.7040406@redhat.com> Date: Wed, 22 Oct 2014 14:02:45 +0200 From: Max Reitz MIME-Version: 1.0 References: <201410221945053926307@sangfor.com> <54479C3E.1070803@huawei.com> <54479C8A.9000407@redhat.com> In-Reply-To: <54479C8A.9000407@redhat.com> Content-Type: text/plain; charset=windows-1252; format=flowed Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] [PATCH v4] snapshot: use local variable to bdrv_pwrite_sync L1 table List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Gonglei , Zhang Haoyu Cc: qemu-trivial , Kevin Wolf , qemu-devel , Stefan Hajnoczi On 2014-10-22 at 14:01, Max Reitz wrote: > On 2014-10-22 at 13:59, Gonglei wrote: >> On 2014/10/22 19:45, Zhang Haoyu wrote: >> >>> Use local variable to bdrv_pwrite_sync L1 table, >>> needless to make conversion of cached L1 table between >>> big-endian and host style. >>> >>> Signed-off-by: Zhang Haoyu >>> Reviewed-by: Max Reitz >>> --- >>> v3 -> v4: >>> - convert local L1 table to host-style before copy it >>> back to s->l1_table >>> >>> v2 -> v3: >>> - replace g_try_malloc0 with qemu_try_blockalign >>> - copy the latest local L1 table back to s->l1_table >>> after successfully bdrv_pwrite_sync L1 table >>> >>> v1 -> v2: >>> - remove the superflous assignment, l1_table = NULL; >>> - replace 512 with BDRV_SECTOR_SIZE, and align_offset with ROUND_UP >>> - remove needless check of if (l1_table) before g_free(l1_table) >>> >>> block/qcow2-refcount.c | 28 ++++++++++++---------------- >>> 1 file changed, 12 insertions(+), 16 deletions(-) >>> >>> diff --git a/block/qcow2-refcount.c b/block/qcow2-refcount.c >>> index 2bcaaf9..3e4050a 100644 >>> --- a/block/qcow2-refcount.c >>> +++ b/block/qcow2-refcount.c >>> @@ -881,14 +881,17 @@ int >>> qcow2_update_snapshot_refcount(BlockDriverState *bs, >>> { >>> BDRVQcowState *s = bs->opaque; >>> uint64_t *l1_table, *l2_table, l2_offset, offset, l1_size2; >>> - bool l1_allocated = false; >>> int64_t old_offset, old_l2_offset; >>> int i, j, l1_modified = 0, nb_csectors, refcount; >>> int ret; >>> l2_table = NULL; >>> - l1_table = NULL; >>> l1_size2 = l1_size * sizeof(uint64_t); >>> + l1_table = qemu_try_blockalign(bs->file, l1_size2); >>> + if (l1_size2 && l1_table == NULL) { >> I think this check has a logic problem. If l1_size2 != 0 and >> l1_table == NULL, >> What will happen? > > Then this condition is met and you return with -ENOMEM...? Oh, but I see something different: qemu_try_blockalign() never returns NULL, not even when you request 0 bytes. Therefore, just "if (l1_table == NULL)" is sufficient. Max