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Re: [Qemu-devel] [PATCH v2] qemu-nbd: only send a limited number of errn
Re: [Qemu-devel] [PATCH v2] qemu-nbd: only send a limited number of errno codes on the wire
Fri, 08 May 2015 06:35:28 -0600
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On 05/08/2015 04:27 AM, Paolo Bonzini wrote:
> On 08/05/2015 12:12, Markus Armbruster wrote:
>>> The corresponding patch to the NBD protocol description can be found at
>>> - EFBIG is part of the universal set of errors, but it is also changed
>>> to ENOSPC because it is pretty similar to ENOSPC or EDQUOT.
>> Perhaps debatable, but I defer to your judgement.
> EFBIG is weird anyway, and requires you (or your parents) to ignore
> SIGXFSZ. A simpler protocol puts fewer requirements on the client.
Not only that, but if I understand correctly, the only way to trigger
SIGXFSZ or EFBIG is to compile your application to use a smaller off_t
than the maximum the system supports. That is, it is impossible on
64-bit Linux, and on 32-bit Linux is it possible only when you use
32-bit off_t instead of 64-bit off_t. But we are dealing with guest
disk images, and practically require 64-bit off_t to make it useful for
all but the oldest of guests.
> (In fact, we probably should ignore SIGXFSZ in QEMU and treat EFBIG like
> ENOSPC everywhere. Should doesn't mean that it will get on anyone's
> todo list or priority list...).
and if I'm right above, it wouldn't make a difference anyway.
Eric Blake eblake redhat com +1-919-301-3266
Libvirt virtualization library http://libvirt.org
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