[libvirt] [PATCH 2/3] fdstream: introduce virFDStreamOpenBlockDevice

[Daniel P. Berrange]

On Fri, Aug 15, 2014 at 12:44:21PM +0400, Roman Bogorodskiy wrote:
> virStorageBackendVolDownloadLocal and virStorageBackendVolUploadLocal
> use virFDStreamOpenFile function to work with the volume fd.
> 
> virFDStreamOpenFile calls virFDStreamOpenFileInternal that implements
> handling of the non-blocking I/O. If a file is not a character device and
> not a fifo, it uses libvirt_iohelper.
> 
> On FreeBSD, it doesn't work as expected because disks are exposed as
> character devices.

Why does that cause a problem ? The reason we use iohelper is because
POSIX does not have O_NONBLOCK work on plain files, so we need to use
the iohelper so that we have a pipe we can set O_NONBLOCK on. If FreeBSD
disks are character devices though, O_NONBLOCK should work fine on them
avoiding the need for iohelper.


Regards,
Daniel
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