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authorStefan Hajnoczi <stefanha@redhat.com>2015-07-01 15:45:50 +0100
committerJeff Cody <jcody@redhat.com>2015-08-06 04:41:09 -0400
commitcae98cb87d269c33d23b2bccd79bb8d99a60d811 (patch)
tree0fd48543b2d8df826b152198ce27b03d9f1bb240 /include/qemu/compiler.h
parent2d697366a14ce95da2e9a59ea9872d3034eb49e4 (diff)
downloadfocaccia-qemu-cae98cb87d269c33d23b2bccd79bb8d99a60d811.tar.gz
focaccia-qemu-cae98cb87d269c33d23b2bccd79bb8d99a60d811.zip
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 <jcody@redhat.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Message-id: 1435761950-26714-1-git-send-email-stefanha@redhat.com
Signed-off-by: Jeff Cody <jcody@redhat.com>
Diffstat (limited to 'include/qemu/compiler.h')
0 files changed, 0 insertions, 0 deletions