From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:36220) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1cYWWs-0006sQ-Qi for qemu-devel@nongnu.org; Tue, 31 Jan 2017 06:23:19 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1cYWWp-0008N4-NC for qemu-devel@nongnu.org; Tue, 31 Jan 2017 06:23:18 -0500 Received: from mailhub.sw.ru ([195.214.232.25]:30493 helo=relay.sw.ru) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1cYWWp-0008Kk-Bb for qemu-devel@nongnu.org; Tue, 31 Jan 2017 06:23:15 -0500 From: Vladimir Sementsov-Ogievskiy Date: Tue, 31 Jan 2017 14:23:08 +0300 Message-Id: <20170131112308.54189-1-vsementsov@virtuozzo.com> Subject: [Qemu-devel] [PATCH] block: bdrv_invalidate_cache: invalidate children first List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: qemu-block@nongnu.org, qemu-devel@nongnu.org Cc: kwolf@redhat.com, mreitz@redhat.com, armbru@redhat.com, eblake@redhat.com, jsnow@redhat.com, famz@redhat.com, den@openvz.org, stefanha@redhat.com, vsementsov@virtuozzo.com, pbonzini@redhat.com Current implementation invalidates firstly parent bds and then its children. This leads to the following bug: after incoming migration, in bdrv_invalidate_cache_all: 1. invalidate parent bds - reopen it with BDRV_O_INACTIVE cleared 2. child is not yet invalidated 3. parent check that its BDRV_O_INACTIVE is cleared 4. parent writes to child 5. assert in bdrv_co_pwritev, as BDRV_O_INACTIVE is set for child This patch fixes it by just changing invalidate sequence: invalidate children first. Signed-off-by: Vladimir Sementsov-Ogievskiy --- v2: I've missed that bdrv_invalidate_cache is already recursive, so we can change sequence here. Also v1 doesn't cover the case when bdrv_invalidate_cache is called not from bdrv_invalidate_cache_all. block.c | 11 +++++------ 1 file changed, 5 insertions(+), 6 deletions(-) diff --git a/block.c b/block.c index a0346c80c6..dce1dc02af 100644 --- a/block.c +++ b/block.c @@ -3235,19 +3235,18 @@ void bdrv_invalidate_cache(BlockDriverState *bs, Error **errp) if (!(bs->open_flags & BDRV_O_INACTIVE)) { return; } - bs->open_flags &= ~BDRV_O_INACTIVE; - if (bs->drv->bdrv_invalidate_cache) { - bs->drv->bdrv_invalidate_cache(bs, &local_err); + QLIST_FOREACH(child, &bs->children, next) { + bdrv_invalidate_cache(child->bs, &local_err); if (local_err) { - bs->open_flags |= BDRV_O_INACTIVE; error_propagate(errp, local_err); return; } } - QLIST_FOREACH(child, &bs->children, next) { - bdrv_invalidate_cache(child->bs, &local_err); + bs->open_flags &= ~BDRV_O_INACTIVE; + if (bs->drv->bdrv_invalidate_cache) { + bs->drv->bdrv_invalidate_cache(bs, &local_err); if (local_err) { bs->open_flags |= BDRV_O_INACTIVE; error_propagate(errp, local_err); -- 2.11.0