[libvirt] [PATCH] fdstream: drop delete argument

[Eric Blake]

On 08/02/2011 01:18 PM, Laine Stump wrote:
> On 08/02/2011 01:31 PM, Eric Blake wrote:
>> Revert 6a1f5f568f8. Now that libvirt_iohelper no longer has a
>> race where it can open() a file after the parent process has
>> unlink()d the same file, it makes more sense to make the callers
>> both create and unlink, rather than the caller create and the
>> stream unlink.
>
>
> I wasn't paying attention to the messages/patches related to the race
> condition you reference,

Commit 1eb66479 plugged the race; commit 6a1f5f5 introduced the race in 
the first place.

The problem was that if we use libvirt_iohelper, and the child process 
calls open(), but the parent process calls unlink() before the child 
process gets to run very far, then the child process will fail to 
open().  But by changing fdstream to pass the fd to libvirt-iohelper by 
fd inheritance instead of by name-wise open() calls, there is no longer 
an open() race, so we can once again unlink() in the parent.

 > but this (caller creates and unlinks)
> definitely seems cleaner than the other way. Beyond that, the patch
> seems to be correct. ACK.

Should this go in for 0.9.4, or am I correct in deferring it until after 
the release?

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