Daniel P. Berrange wrote:
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.
O_NONBLOCK doesn't work for some reason, at least on ZFS volumes: fcntl() fails with: fcntl: Inappropriate ioctl for device I have asked a question on an appropriate mailing list: https://lists.freebsd.org/pipermail/freebsd-fs/2014-August/019923.html I've also included a test program I use to reproduce that there.
Regards, Daniel -- |: http://berrange.com -o- http://www.flickr.com/photos/dberrange/ :| |: http://libvirt.org -o- http://virt-manager.org :| |: http://autobuild.org -o- http://search.cpan.org/~danberr/ :| |: http://entangle-photo.org -o- http://live.gnome.org/gtk-vnc :|
Roman Bogorodskiy