[libvirt] [RFC: PATCHv4 00/15] outgoing migration via fd: rather than exec:

[Eric Blake]

On 03/10/2011 12:54 PM, Laine Stump wrote:
> Okay, I've figured out what happened - the permission on a parent of my
> target directory on the NFS server had been changed during unrelated
> testing from (root,root) 755 to 700, so even though the target directory
> had the proper user (qemu,qemu), qemu was denied access to the directory
> due to its parent's permissions/ownership. When I set the parent
> directory back to 755, save and restore both work.
> 
> However, the current code still has a problem - if you try to save
> to/from a directory that the qemu user doesn't have permission for (and
> presumably if there's any other error in the child that causes it to
> skip the sendmsg), rather than returning an error virFileOpenAs just
> hangs on recvmsg waiting for the fd info to come over the pipe, while
> the child process sits around as a zombie because nobody has reaped its
> exit status.

Yep, makes sense.  I'm double checking whether I reliably closed the
write end of the socket in all paths, and it may boil down to changing
the child to _always_ sendmsg even if there is no fd to send.  I'm still
thinking about it.

-- 
Eric Blake   eblake at redhat.com    +1-801-349-2682
Libvirt virtualization library http://libvirt.org

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