From cae98cb87d269c33d23b2bccd79bb8d99a60d811 Mon Sep 17 00:00:00 2001 From: Stefan Hajnoczi Date: Wed, 1 Jul 2015 15:45:50 +0100 Subject: block/mirror: limit qiov to IOV_MAX elements If mirror has more free buffers than IOV_MAX, preadv(2)/pwritev(2) EINVAL failures may be encountered. It is possible to trigger this by setting granularity to a low value like 8192. This patch stops appending chunks once IOV_MAX is reached. The spurious EINVAL failure can be reproduced with a qcow2 image file and the following QMP invocation: qmp.command('drive-mirror', device='virtio0', target='/tmp/r7.s1', granularity=8192, sync='full', mode='absolute-paths', format='raw') While the guest is running dd if=/dev/zero of=/var/tmp/foo oflag=direct bs=4k. Cc: Jeff Cody Signed-off-by: Stefan Hajnoczi Reviewed-by: Paolo Bonzini Message-id: 1435761950-26714-1-git-send-email-stefanha@redhat.com Signed-off-by: Jeff Cody --- block/mirror.c | 4 ++++ 1 file changed, 4 insertions(+) (limited to 'block') diff --git a/block/mirror.c b/block/mirror.c index fc4d8f5..0841964 100644 --- a/block/mirror.c +++ b/block/mirror.c @@ -245,6 +245,10 @@ static uint64_t coroutine_fn mirror_iteration(MirrorBlockJob *s) trace_mirror_break_buf_busy(s, nb_chunks, s->in_flight); break; } + if (IOV_MAX < nb_chunks + added_chunks) { + trace_mirror_break_iov_max(s, nb_chunks, added_chunks); + break; + } /* We have enough free space to copy these sectors. */ bitmap_set(s->in_flight_bitmap, next_chunk, added_chunks); -- cgit v1.1