From patchwork Mon Mar 7 15:27:33 2011 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Jes Sorensen X-Patchwork-Id: 85760 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Received: from lists.gnu.org (lists.gnu.org [199.232.76.165]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (Client did not present a certificate) by ozlabs.org (Postfix) with ESMTPS id A3678B70DC for ; Tue, 8 Mar 2011 02:28:34 +1100 (EST) Received: from localhost ([127.0.0.1]:51004 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1PwcMG-0003ms-P9 for incoming@patchwork.ozlabs.org; Mon, 07 Mar 2011 10:28:28 -0500 Received: from [140.186.70.92] (port=40144 helo=eggs.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1PwcLe-0003ma-2N for qemu-devel@nongnu.org; Mon, 07 Mar 2011 10:27:51 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1PwcLc-0002Jh-Sr for qemu-devel@nongnu.org; Mon, 07 Mar 2011 10:27:49 -0500 Received: from mx1.redhat.com ([209.132.183.28]:13249) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1PwcLc-0002JN-ID for qemu-devel@nongnu.org; Mon, 07 Mar 2011 10:27:48 -0500 Received: from int-mx02.intmail.prod.int.phx2.redhat.com (int-mx02.intmail.prod.int.phx2.redhat.com [10.5.11.12]) by mx1.redhat.com (8.14.4/8.14.4) with ESMTP id p27FRleD023835 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=OK); Mon, 7 Mar 2011 10:27:47 -0500 Received: from red-feather.redhat.com (ovpn-113-81.phx2.redhat.com [10.3.113.81]) by int-mx02.intmail.prod.int.phx2.redhat.com (8.13.8/8.13.8) with ESMTP id p27FRjPo019703; Mon, 7 Mar 2011 10:27:45 -0500 From: Jes.Sorensen@redhat.com To: qemu-devel@nongnu.org Date: Mon, 7 Mar 2011 16:27:33 +0100 Message-Id: <1299511653-11357-1-git-send-email-Jes.Sorensen@redhat.com> X-Scanned-By: MIMEDefang 2.67 on 10.5.11.12 X-detected-operating-system: by eggs.gnu.org: Genre and OS details not recognized. X-Received-From: 209.132.183.28 Cc: kwolf@redhat.com, stefanha@linux.vnet.ibm.com Subject: [Qemu-devel] [PATCH v3] Improve error handling in do_snapshot_blkdev() X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: qemu-devel.nongnu.org List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org Errors-To: qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org From: Jes Sorensen In case we cannot open the newly created snapshot image, try to fall back to the original image file and continue running on that, which should prevent the guest from aborting. This is a corner case which can happen if the admin by mistake specifies the snapshot file on a virtual file system which does not support O_DIRECT. bdrv_create() does not use O_DIRECT, but the following open in bdrv_open() does and will then fail. Signed-off-by: Jes Sorensen --- blockdev.c | 29 +++++++++++++++++++++++------ 1 files changed, 23 insertions(+), 6 deletions(-) diff --git a/blockdev.c b/blockdev.c index 0690cc8..d52eef0 100644 --- a/blockdev.c +++ b/blockdev.c @@ -574,9 +574,10 @@ int do_snapshot_blkdev(Monitor *mon, const QDict *qdict, QObject **ret_data) const char *filename = qdict_get_try_str(qdict, "snapshot_file"); const char *format = qdict_get_try_str(qdict, "format"); BlockDriverState *bs; - BlockDriver *drv, *proto_drv; + BlockDriver *drv, *old_drv, *proto_drv; int ret = 0; int flags; + char old_filename[1024]; if (!filename) { qerror_report(QERR_MISSING_PARAMETER, "snapshot_file"); @@ -591,6 +592,11 @@ int do_snapshot_blkdev(Monitor *mon, const QDict *qdict, QObject **ret_data) goto out; } + pstrcpy(old_filename, sizeof(old_filename), bs->filename); + + old_drv = bs->drv; + flags = bs->open_flags; + if (!format) { format = "qcow2"; } @@ -610,7 +616,7 @@ int do_snapshot_blkdev(Monitor *mon, const QDict *qdict, QObject **ret_data) } ret = bdrv_img_create(filename, format, bs->filename, - bs->drv->format_name, NULL, -1, bs->open_flags); + bs->drv->format_name, NULL, -1, flags); if (ret) { goto out; } @@ -618,15 +624,26 @@ int do_snapshot_blkdev(Monitor *mon, const QDict *qdict, QObject **ret_data) qemu_aio_flush(); bdrv_flush(bs); - flags = bs->open_flags; bdrv_close(bs); ret = bdrv_open(bs, filename, flags, drv); /* - * If reopening the image file we just created fails, we really - * are in trouble :( + * If reopening the image file we just created fails, fall back + * and try to re-open the original image. If that fails too, we + * are in serious trouble. */ if (ret != 0) { - abort(); + qerror_report(QERR_OPEN_FILE_FAILED, filename); + error_printf("do_snapshot_blkdev(): Unable to open newly created " + "snapshot file: \n"); + error_printf("%s. Attempting to revert to original image: %s\n", + filename, old_filename); + ret = bdrv_open(bs, old_filename, flags, old_drv); + if (ret != 0) { + error_printf("do_snapshot_blkdev(): Unable to re-open " + "original image - aborting!\n"); + qerror_report(QERR_OPEN_FILE_FAILED, old_filename); + abort(); + } } out: if (ret) {