[libvirt] [PATCH v2] iohelper: fix reading with O_DIRECT

[Daniel P. Berrange]

On Wed, Sep 20, 2017 at 02:58:55PM +0300, Nikolay Shirokovskiy wrote:
> saferead is not suitable for direct reads. If file size is not multiple
> of align size then we get EINVAL on the read(2) that is supposed to
> return 0 because read buffer will not be aligned at this point.
> 
> Let's not read again after partial read and check that we read
> everything by comparing the number of total bytes read against file size.

What scenario did you actually hit this problem in ?    IIUC, we should
only be using O_DIRECT against block devices or plain files, and in both
those cases we should never see short-read unless we hit EOF.


Regards,
Daniel
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