[Qemu-devel] [RFC] O_EXCL or not open block device

[Jack Wang]

Hi all,

We're using qemu export md-raid to guest OS, and we saw deadlock on
MD(which is already fixed by Neil), please see thread below:
> http://marc.info/?l=linux-raid&m=137894040228125&w=2

As Neil suggested it would be good for userspace applications to call
open() with O_EXCL flag, to avoid such MD hanging problems at the begining.

And we checked qemu, it looks it doesn't include O_EXCL flag when open
block device.

After search in the mail list we found there are a similar discussion:

https://lists.nongnu.org/archive/html/qemu-devel/2011-04/msg00722.html

> To O_EXCL or not to O_EXCL open host_cdrom

Which looks prefer enable O_EXCL, but I checked latest qemu tree, there
no such code, could anyone give comments on this?

Best regards,
Jack