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Re: [Bug-tar] Re: [patch] O_NOATIME support
From: |
Ian Turner |
Subject: |
Re: [Bug-tar] Re: [patch] O_NOATIME support |
Date: |
Thu, 13 Oct 2005 08:14:46 -0700 |
User-agent: |
KMail/1.7.1 |
> Should't a clean Linux implementation offer a related [f]pathconf() call
> for this feature?
Maybe. But the Linux implementors were just trying to grab the libc interface,
which doesn't say anything about fpathconf().
Right now you can check if the kernel supports O_NOATIME at all using fcntl();
If you set the flag at open() (or using F_SETFL), then if the kernel supports
it, the flag will still be there when you use F_GETFL. Otherwise, the flag
will remain unset.
HOWEVER, right now even the linux kernel itself does not know which
filesystems support this feature. We are working on adding this
functionality, but it may take some time to get it accepted, as the original
patch was itself contraversial.
Probably the interface to find out if O_NOATIME works will be simple: If you
do open(), and O_NOATIME is not OK for this filesystem, then open() will just
return EINVAL. I'm OK with adding an fpathconf() facility too, but the big
work is going to be just teaching the kernel which filesystems work and which
don't.
--Ian