From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:42194) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1VlCIj-0004E2-A3 for qemu-devel@nongnu.org; Tue, 26 Nov 2013 01:39:22 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1VlCIa-0000m5-82 for qemu-devel@nongnu.org; Tue, 26 Nov 2013 01:39:13 -0500 Received: from e23smtp07.au.ibm.com ([202.81.31.140]:38148) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1VlCIZ-0000lS-CO for qemu-devel@nongnu.org; Tue, 26 Nov 2013 01:39:04 -0500 Received: from /spool/local by e23smtp07.au.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Tue, 26 Nov 2013 16:39:01 +1000 Received: from d23relay04.au.ibm.com (d23relay04.au.ibm.com [9.190.234.120]) by d23dlp03.au.ibm.com (Postfix) with ESMTP id 1F3623578053 for ; Tue, 26 Nov 2013 17:38:58 +1100 (EST) Received: from d23av04.au.ibm.com (d23av04.au.ibm.com [9.190.235.139]) by d23relay04.au.ibm.com (8.13.8/8.13.8/NCO v10.0) with ESMTP id rAQ6L39A41222292 for ; Tue, 26 Nov 2013 17:21:03 +1100 Received: from d23av04.au.ibm.com (localhost [127.0.0.1]) by d23av04.au.ibm.com (8.14.4/8.14.4/NCO v10.0 AVout) with ESMTP id rAQ6cvEJ017968 for ; Tue, 26 Nov 2013 17:38:57 +1100 From: Xu Wang Date: Tue, 26 Nov 2013 01:38:32 -0500 Message-Id: <1385447913-19004-4-git-send-email-gesaint@linux.vnet.ibm.com> In-Reply-To: <1385447913-19004-1-git-send-email-gesaint@linux.vnet.ibm.com> References: <1385447913-19004-1-git-send-email-gesaint@linux.vnet.ibm.com> Subject: [Qemu-devel] [PATCH V9 3/4] block: Add backing file loop check in change_backing_file() List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: qemu-devel@nongnu.org Cc: kwolf@redhat.com, famz@redhat.com, stefanha@gmail.com, wdongxu@linux.vnet.ibm.com, Xu Wang Backing file loop should be checked before calling change_backing_ file(). If loop appeared, this calling should be stopped and an error printed. Signed-off-by: Xu Wang --- block.c | 9 +++++++++ 1 file changed, 9 insertions(+) diff --git a/block.c b/block.c index b8cea1c..87f7018 100644 --- a/block.c +++ b/block.c @@ -2075,6 +2075,7 @@ static void coroutine_fn wait_for_overlapping_requests(BlockDriverState *bs, * Return values: * 0 - success * -EINVAL - backing format specified, but no file + * -EIO - generic I/O error (may happen for all errors) * -ENOSPC - can't update the backing file because no space is left in the * image file header * -ENOTSUP - format driver doesn't support changing the backing file @@ -2083,6 +2084,7 @@ int bdrv_change_backing_file(BlockDriverState *bs, const char *backing_file, const char *backing_fmt) { BlockDriver *drv = bs->drv; + Error *local_err = NULL; int ret; /* Backing file format doesn't make sense without a backing file */ @@ -2090,6 +2092,13 @@ int bdrv_change_backing_file(BlockDriverState *bs, return -EINVAL; } + /* Check if loop exists in backing files chain after change */ + if (!bdrv_backing_chain_okay(backing_file, NULL, bs->filename, + &local_err)) { + error_report("Backing file check: %s", error_get_pretty(local_err)); + return -EIO; + } + if (drv->bdrv_change_backing_file != NULL) { ret = drv->bdrv_change_backing_file(bs, backing_file, backing_fmt); } else { -- 1.8.1.4