Re: [libvirt] [Qemu-devel] [PATCH v4 0/7] file descriptor passing using pass-fd
Am 26.06.2012 11:10, schrieb Daniel P. Berrange:
I was thinking about some of the sources complexity when using
FD passing from libvirt and wanted to raise one idea for discussion
before we continue.
With this proposed series, we have usage akin to:
1. pass_fd FDSET={M} -> returns a string "/dev/fd/N" showing QEMU's
view of the FD
2. drive_add file=/dev/fd/N
3. if failure:
close_fd "/dev/fd/N"
In fact, there are more steps:
4. use it successfully
5. close_fd "/dev/fd/N"
I think it would well be possible that qemu just closes the fd when it's
not used internally any more. The point of close_fd is more that libvirt
still keeps a handle and can make use of this fd. One example where this
is necessary is reopening the FD of a backing file in order to perform a
live commit operation.
Kevin