linux-kernel - Re: [fuse-devel] utimensat fails to update ctime

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Message-ID: <4B3097C4.3060803@wanadoo.fr>
Date:	Tue, 22 Dec 2009 10:56:20 +0100
From:	Jean-Pierre André <jean-pierre.andre@...adoo.fr>
To:	OGAWA Hirofumi <hirofumi@...l.parknet.co.jp>
CC:	Eric Blake <ebb9@....net>, fuse-devel@...ts.sourceforge.net,
	Miklos Szeredi <miklos@...redi.hu>,
	Christoph Hellwig <hch@....de>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	xfs@....sgi.com
Subject: Re: [fuse-devel] utimensat fails to update ctime

Hi all,


OGAWA Hirofumi wrote:
> Eric Blake<ebb9@....net>  writes:
>
>    
> It is likely the issue of libfuse or ntfs-3g. I don't know about ntfs-3g
> people at all. So, for now, just Cc: to fuse people.
>    

Which ntfs-3g version are you using ?

>> utimensat(0, NULL, {UTIME_OMIT, UTIME_NOW}, 0) = 0
>>      
>    

Currently ntfs-3g does not set sub-second precision.

There is also a slight problem in the fuse interface :
the time buffer is never passed as NULL, consequently
in some circumstances ntfs-3g cannot decide correctly
over permissions. A permissive action is taken in this
situation.

> > From this, "ia_valid" will have "ATTR_CTIME | ATTR_MTIME". And the
> request would pass to userland via fuse of kernel part, then it will be
> handled by libfuse.
>
> > From quick grep of libfuse and ntfs-3g (would not be latest), ntfs-3g is
> using "struct fuse_operations", not "struct fuse_lowlevel_ops".
>    

With the latest ntfs-3g, currently as a release candidate,
you can (optionally) use the low level fuse interface
http://pagesperso-orange.fr/b.andre/advanced-ntfs-3g.html
use the "lowntfs-3g" driver instead of "ntfs-3g"

Hope this helps

Regards

Jean-Pierre



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