Re: [Qemu-devel] [PATCH 2/2] file-posix: Do runtime check for ofd lock API

[Eric Blake <eblake@redhat.com>]

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On 07/21/2017 05:20 AM, Fam Zheng wrote:
> It is reported that on Windows Subsystem for Linux, ofd operations fail
> with -EINVAL. In other words, QEMU binary built with system headers that
> exports F_OFD_SETLK doesn't necessarily run in an environment that
> actually supports it:
> 
> $ qemu-system-aarch64 ... -drive file=test.vhdx,if=none,id=hd0 \
>     -device virtio-blk-pci,drive=hd0
> qemu-system-aarch64: -drive file=test.vhdx,if=none,id=hd0: Failed to unlock byte 100
> qemu-system-aarch64: -drive file=test.vhdx,if=none,id=hd0: Failed to unlock byte 100
> qemu-system-aarch64: -drive file=test.vhdx,if=none,id=hd0: Failed to lock byte 100
> 
> Let's do a runtime check to cope with that.

You may want to mention that the same is possible on a system with old
kernel but new glibc (ie. this issue is not necessarily specific to WSL).

> 
> Reported-by: Andrew Baumann <Andrew.Baumann@microsoft.com>
> Signed-off-by: Fam Zheng <famz@redhat.com>
> ---
>  block/file-posix.c | 19 ++++++++-----------
>  1 file changed, 8 insertions(+), 11 deletions(-)
> 

Reviewed-by: Eric Blake <eblake@redhat.com>

-- 
Eric Blake, Principal Software Engineer
Red Hat, Inc.           +1-919-301-3266
Virtualization:  qemu.org | libvirt.org


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