From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:37031) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1WO6Mg-0006jS-3n for qemu-devel@nongnu.org; Thu, 13 Mar 2014 10:12:12 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1WO6Ma-0006ct-4L for qemu-devel@nongnu.org; Thu, 13 Mar 2014 10:12:06 -0400 Received: from mx1.redhat.com ([209.132.183.28]:25022) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1WO6MZ-0006cl-Rd for qemu-devel@nongnu.org; Thu, 13 Mar 2014 10:12:00 -0400 From: Stefan Hajnoczi Date: Thu, 13 Mar 2014 15:11:01 +0100 Message-Id: <1394719868-24312-18-git-send-email-stefanha@redhat.com> In-Reply-To: <1394719868-24312-1-git-send-email-stefanha@redhat.com> References: <1394719868-24312-1-git-send-email-stefanha@redhat.com> Subject: [Qemu-devel] [PULL v2 for-2.0 17/24] qcow2: Don't write with BDRV_O_INCOMING List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: qemu-devel@nongnu.org Cc: Kevin Wolf , Peter Maydell , Stefan Hajnoczi , Anthony Liguori From: Kevin Wolf qcow2_open() causes writes when repairing an image with the dirty flag set and when clearing autoclear flags. It shouldn't do this when another qemu instance is still actively working on this image file. One effect of the bug is that images may have a cleared dirty flag while the migration source host still has it in use with lazy refcounts enabled, so refcounts are not accurate and the dirty flag must remain set. Signed-off-by: Kevin Wolf Reviewed-by: Eric Blake Signed-off-by: Stefan Hajnoczi --- block/qcow2.c | 12 +++++++----- 1 file changed, 7 insertions(+), 5 deletions(-) diff --git a/block/qcow2.c b/block/qcow2.c index ec23cc4..945c9d6 100644 --- a/block/qcow2.c +++ b/block/qcow2.c @@ -644,7 +644,7 @@ static int qcow2_open(BlockDriverState *bs, QDict *options, int flags, } /* Clear unknown autoclear feature bits */ - if (!bs->read_only && s->autoclear_features != 0) { + if (!bs->read_only && !(flags & BDRV_O_INCOMING) && s->autoclear_features) { s->autoclear_features = 0; ret = qcow2_update_header(bs); if (ret < 0) { @@ -657,7 +657,7 @@ static int qcow2_open(BlockDriverState *bs, QDict *options, int flags, qemu_co_mutex_init(&s->lock); /* Repair image if dirty */ - if (!(flags & BDRV_O_CHECK) && !bs->read_only && + if (!(flags & (BDRV_O_CHECK | BDRV_O_INCOMING)) && !bs->read_only && (s->incompatible_features & QCOW2_INCOMPAT_DIRTY)) { BdrvCheckResult result = {0}; @@ -1137,10 +1137,12 @@ static void qcow2_close(BlockDriverState *bs) /* else pre-write overlap checks in cache_destroy may crash */ s->l1_table = NULL; - qcow2_cache_flush(bs, s->l2_table_cache); - qcow2_cache_flush(bs, s->refcount_block_cache); + if (!(bs->open_flags & BDRV_O_INCOMING)) { + qcow2_cache_flush(bs, s->l2_table_cache); + qcow2_cache_flush(bs, s->refcount_block_cache); - qcow2_mark_clean(bs); + qcow2_mark_clean(bs); + } qcow2_cache_destroy(bs, s->l2_table_cache); qcow2_cache_destroy(bs, s->refcount_block_cache); -- 1.8.5.3