From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:34893) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1YYL1F-00074r-9K for qemu-devel@nongnu.org; Wed, 18 Mar 2015 16:56:50 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1YYL1E-00024i-EN for qemu-devel@nongnu.org; Wed, 18 Mar 2015 16:56:49 -0400 From: Max Reitz Date: Wed, 18 Mar 2015 16:56:27 -0400 Message-Id: <1426712188-24799-10-git-send-email-mreitz@redhat.com> In-Reply-To: <1426712188-24799-1-git-send-email-mreitz@redhat.com> References: <1426712188-24799-1-git-send-email-mreitz@redhat.com> Subject: [Qemu-devel] [PATCH v8 09/10] qcow2: Point to amend function in check List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: qemu-block@nongnu.org Cc: Kevin Wolf , qemu-devel@nongnu.org, Stefan Hajnoczi , Max Reitz If a reference count is not representable with the current refcount order, the image check should point to qemu-img amend for increasing the refcount order. However, qemu-img amend needs write access to the image which cannot be provided if the image is marked corrupt; and the image check will not mark the image consistent unless everything actually is consistent. Therefore, if an image is marked corrupt and the image check encounters a reference count overflow, it cannot be fixed by using qemu-img amend to increase the refcount order. Instead, one has to use qemu-img convert to create a completely new copy of the image in this case. Alternatively, we may want to give the user a way of manually removing the corrupt flag, maybe through qemu-img amend, but this is not part of this patch. Signed-off-by: Max Reitz Reviewed-by: Eric Blake Reviewed-by: Stefan Hajnoczi --- block/qcow2-refcount.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/block/qcow2-refcount.c b/block/qcow2-refcount.c index f7e5b5e..46f999c 100644 --- a/block/qcow2-refcount.c +++ b/block/qcow2-refcount.c @@ -1340,6 +1340,9 @@ static int inc_refcounts(BlockDriverState *bs, if (refcount == s->refcount_max) { fprintf(stderr, "ERROR: overflow cluster offset=0x%" PRIx64 "\n", cluster_offset); + fprintf(stderr, "Use qemu-img amend to increase the refcount entry " + "width or qemu-img convert to create a clean copy if the " + "image cannot be opened for writing\n"); res->corruptions++; continue; } -- 2.1.0