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

To: Jean-Pierre André <jean-pierre.andre@xxxxxxxxxx>
Subject: Re: [fuse-devel] utimensat fails to update ctime
From: OGAWA Hirofumi <hirofumi@xxxxxxxxxxxxxxxxxx>
Date: Tue, 22 Dec 2009 19:43:16 +0900
Cc: Eric Blake <ebb9@xxxxxxx>, fuse-devel@xxxxxxxxxxxxxxxxxxxxx, Miklos Szeredi <miklos@xxxxxxxxxx>, Christoph Hellwig <hch@xxxxxx>, Linux Kernel Mailing List <linux-kernel@xxxxxxxxxxxxxxx>, xfs@xxxxxxxxxxx
In-reply-to: <4B3097C4.3060803@xxxxxxxxxx> ("Jean-Pierre André"'s message of "Tue, 22 Dec 2009 10:56:20 +0100")
References: <4B2B156D.9040604@xxxxxxx> <87aaxclr4q.fsf@xxxxxxxxxxxxxxxxxxx> <4B2F7421.10005@xxxxxxx> <4B2F7A95.3010708@xxxxxxx> <87hbrkjrk8.fsf@xxxxxxxxxxxxxxxxxxx> <4B304D04.6040501@xxxxxxx> <87d427jscr.fsf@xxxxxxxxxxxxxxxxxxx> <4B3097C4.3060803@xxxxxxxxxx>
User-agent: Gnus/5.13 (Gnus v5.13) Emacs/23.1.90 (gnu/linux)
Jean-Pierre André <jean-pierre.andre@xxxxxxxxxx> writes:

> Hi all,

Hi,

> OGAWA Hirofumi wrote:
>> Eric Blake<ebb9@xxxxxxx>  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 ?

I don't know which version is used by actual user. But, well, I've got
source by "apt-get source", and the version was 1:2009.4.4-1.

Now, I've got ntfs-3g-2009.11.14AC.2.tgz from specified url.

>>> 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"

Well, the problem seems in fuse_lib_setattr() and ntfs_fuse_setattr()
(lowlevel op too).

The both functions is requiring "ATIME | MTIME". Doesn't it mean the
ntfs-3g can't set only MTIME like above utimensat()?

In fuse_lib_setattr(),

        if (!err && (valid & (FUSE_SET_ATTR_ATIME | FUSE_SET_ATTR_MTIME)) ==
            (FUSE_SET_ATTR_ATIME | FUSE_SET_ATTR_MTIME)) {

In ntfs_fuse_setattr(),
        case FUSE_SET_ATTR_ATIME + FUSE_SET_ATTR_MTIME :
                res = ntfs_fuse_utime(&security, ino, attr, &stbuf);

Or I'm missing something?

Thanks.
-- 
OGAWA Hirofumi <hirofumi@xxxxxxxxxxxxxxxxxx>

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