Re: [Qemu-devel] Safely reopening image files by stashing fds

[Stefan Hajnoczi]

On Fri, Aug 5, 2011 at 3:28 PM, Christoph Hellwig <address@hidden> wrote:
> On Fri, Aug 05, 2011 at 02:12:48PM +0100, Daniel P. Berrange wrote:
>> > Because you cannot change O_DIRECT on an open fd :(.  This is why
>> > we're going through this pain.
>>
>> Hmm, I remember hearing that before, but looking at the current fcntl()
>> manpage, it claims you *can* change O_DIRECT using SET_FL. Perhaps this
>> is a newish feature, but it'd be nicer to use it if possible ?
>
> It's been there since day 1 of O_DIRECT support.

Sorry, my bad.  So for Linux we could just use fcntl for
block_set_hostcache and not bother with reopening.  However, we will
need to reopen should we wish to support changing O_DSYNC.

Stefan