From patchwork Fri Nov 18 18:29:01 2011 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Kevin Wolf X-Patchwork-Id: 126466 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Received: from lists.gnu.org (lists.gnu.org [140.186.70.17]) (using TLSv1 with cipher AES256-SHA (256/256 bits)) (Client did not present a certificate) by ozlabs.org (Postfix) with ESMTPS id 87F92B7232 for ; Sat, 19 Nov 2011 05:27:24 +1100 (EST) Received: from localhost ([::1]:54144 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1RRT9g-0000nE-IQ for incoming@patchwork.ozlabs.org; Fri, 18 Nov 2011 13:27:16 -0500 Received: from eggs.gnu.org ([140.186.70.92]:38292) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1RRT8b-0006Iz-OD for qemu-devel@nongnu.org; Fri, 18 Nov 2011 13:26:10 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1RRT8Z-0006d4-Gs for qemu-devel@nongnu.org; Fri, 18 Nov 2011 13:26:09 -0500 Received: from mx1.redhat.com ([209.132.183.28]:20217) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1RRT8Z-0006cq-2O for qemu-devel@nongnu.org; Fri, 18 Nov 2011 13:26:07 -0500 Received: from int-mx01.intmail.prod.int.phx2.redhat.com (int-mx01.intmail.prod.int.phx2.redhat.com [10.5.11.11]) by mx1.redhat.com (8.14.4/8.14.4) with ESMTP id pAIIQ5gR018022 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=OK); Fri, 18 Nov 2011 13:26:05 -0500 Received: from dhcp-5-188.str.redhat.com (vpn1-6-61.ams2.redhat.com [10.36.6.61]) by int-mx01.intmail.prod.int.phx2.redhat.com (8.13.8/8.13.8) with ESMTP id pAIIPuJb031078; Fri, 18 Nov 2011 13:26:04 -0500 From: Kevin Wolf To: qemu-devel@nongnu.org Date: Fri, 18 Nov 2011 19:29:01 +0100 Message-Id: <1321640945-9827-6-git-send-email-kwolf@redhat.com> In-Reply-To: <1321640945-9827-1-git-send-email-kwolf@redhat.com> References: <1321640945-9827-1-git-send-email-kwolf@redhat.com> X-Scanned-By: MIMEDefang 2.67 on 10.5.11.11 X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.6 (newer, 3) X-Received-From: 209.132.183.28 Cc: kwolf@redhat.com, stefanha@gmail.com Subject: [Qemu-devel] [PATCH v2 5/9] qcow2: Rework qcow2_snapshot_create error handling X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.14 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org Sender: qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org Increase refcounts only after allocating a new L1 table has succeeded in order to make leaks less likely. If writing the snapshot table fails, revert in-memory state to be consistent with that on disk. While at it, make it return the real error codes instead of -1. Signed-off-by: Kevin Wolf --- block/qcow2-snapshot.c | 55 +++++++++++++++++++++++++++++++++++------------ 1 files changed, 41 insertions(+), 14 deletions(-) diff --git a/block/qcow2-snapshot.c b/block/qcow2-snapshot.c index 53d9233..b433f47 100644 --- a/block/qcow2-snapshot.c +++ b/block/qcow2-snapshot.c @@ -277,7 +277,9 @@ static int find_snapshot_by_id_or_name(BlockDriverState *bs, const char *name) int qcow2_snapshot_create(BlockDriverState *bs, QEMUSnapshotInfo *sn_info) { BDRVQcowState *s = bs->opaque; - QCowSnapshot *snapshots1, sn1, *sn = &sn1; + QCowSnapshot *new_snapshot_list = NULL; + QCowSnapshot *old_snapshot_list = NULL; + QCowSnapshot sn1, *sn = &sn1; int i, ret; uint64_t *l1_table = NULL; int64_t l1_table_offset; @@ -303,16 +305,12 @@ int qcow2_snapshot_create(BlockDriverState *bs, QEMUSnapshotInfo *sn_info) sn->date_nsec = sn_info->date_nsec; sn->vm_clock_nsec = sn_info->vm_clock_nsec; - ret = qcow2_update_snapshot_refcount(bs, s->l1_table_offset, s->l1_size, 1); - if (ret < 0) - goto fail; - /* Allocate the L1 table of the snapshot and copy the current one there. */ l1_table_offset = qcow2_alloc_clusters(bs, s->l1_size * sizeof(uint64_t)); if (l1_table_offset < 0) { + ret = l1_table_offset; goto fail; } - bdrv_flush(bs->file); sn->l1_table_offset = l1_table_offset; sn->l1_size = s->l1_size; @@ -321,22 +319,50 @@ int qcow2_snapshot_create(BlockDriverState *bs, QEMUSnapshotInfo *sn_info) for(i = 0; i < s->l1_size; i++) { l1_table[i] = cpu_to_be64(s->l1_table[i]); } - if (bdrv_pwrite_sync(bs->file, sn->l1_table_offset, - l1_table, s->l1_size * sizeof(uint64_t)) < 0) + + ret = bdrv_pwrite(bs->file, sn->l1_table_offset, l1_table, + s->l1_size * sizeof(uint64_t)); + if (ret < 0) { goto fail; + } + g_free(l1_table); l1_table = NULL; - snapshots1 = g_malloc((s->nb_snapshots + 1) * sizeof(QCowSnapshot)); + /* + * Increase the refcounts of all clusters and make sure everything is + * stable on disk before updating the snapshot table to contain a pointer + * to the new L1 table. + */ + ret = qcow2_update_snapshot_refcount(bs, s->l1_table_offset, s->l1_size, 1); + if (ret < 0) { + goto fail; + } + + ret = bdrv_flush(bs->file); + if (ret < 0) { + goto fail; + } + + /* Append the new snapshot to the snapshot list */ + new_snapshot_list = g_malloc((s->nb_snapshots + 1) * sizeof(QCowSnapshot)); if (s->snapshots) { - memcpy(snapshots1, s->snapshots, s->nb_snapshots * sizeof(QCowSnapshot)); - g_free(s->snapshots); + memcpy(new_snapshot_list, s->snapshots, + s->nb_snapshots * sizeof(QCowSnapshot)); + old_snapshot_list = s->snapshots; } - s->snapshots = snapshots1; + s->snapshots = new_snapshot_list; s->snapshots[s->nb_snapshots++] = *sn; - if (qcow2_write_snapshots(bs) < 0) + ret = qcow2_write_snapshots(bs); + if (ret < 0) { + g_free(s->snapshots); + s->snapshots = old_snapshot_list; goto fail; + } + + g_free(old_snapshot_list); + #ifdef DEBUG_ALLOC { BdrvCheckResult result = {0}; @@ -349,7 +375,8 @@ fail: g_free(sn->id_str); g_free(sn->name); g_free(l1_table); - return -1; + + return ret; } /* copy the snapshot 'snapshot_name' into the current disk image */