From 10f9848d04f8279c2cc67d7970233b2e2dfec9ba Mon Sep 17 00:00:00 2001 From: Kevin Wolf Date: Tue, 8 Jun 2010 11:12:44 -0300 Subject: [PATCH 02/13] qcow2: Fix corruption after error in update_refcount RH-Author: Kevin Wolf Message-id: <1275995574-17666-2-git-send-email-kwolf@redhat.com> Patchwork-id: 9766 O-Subject: [RHEL-6 qemu-kvm PATCH v2 01/11] qcow2: Fix corruption after error in update_refcount Bugzilla: 598507 RH-Acked-by: Christoph Hellwig RH-Acked-by: Jes Sorensen RH-Acked-by: Juan Quintela Bugzilla: 598507 Upstream status: Submitted After it is done with updating refcounts in the cache, update_refcount writes all changed entries to disk. If a refcount block allocation fails, however, there was no change yet and therefore first_index = last_index = -1. Don't treat -1 as a normal sector index (resulting in a 512 byte write!) but return without updating anything in this case. Signed-off-by: Kevin Wolf (cherry picked from commit 10f0bb658e6d7265d658a162c47700bf9b8a4de1) --- block/qcow2-refcount.c | 4 ++++ 1 files changed, 4 insertions(+), 0 deletions(-) Signed-off-by: Eduardo Habkost --- block/qcow2-refcount.c | 4 ++++ 1 files changed, 4 insertions(+), 0 deletions(-) diff --git a/block/qcow2-refcount.c b/block/qcow2-refcount.c index 1fc0aa1..dc57e16 100644 --- a/block/qcow2-refcount.c +++ b/block/qcow2-refcount.c @@ -416,6 +416,10 @@ static int write_refcount_block_entries(BlockDriverState *bs, return 0; } + if (first_index < 0) { + return 0; + } + first_index &= ~(REFCOUNTS_PER_SECTOR - 1); last_index = (last_index + REFCOUNTS_PER_SECTOR) & ~(REFCOUNTS_PER_SECTOR - 1); -- 1.7.0.3