Date: Wed, 7 Apr 2004 13:46:41 +0100
From: viro@parcelfarce.linux.theplanet.co.uk
To: Andrew Morton <akpm@osdl.org>, torvalds@osdl.org,
       linux-kernel@vger.kernel.org
Subject: Re: [Patch] BME, noatime and nodiratime
Message-ID: <20040407124641.GR31500@parcelfarce.linux.theplanet.co.uk>
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On Wed, Apr 07, 2004 at 12:19:12PM +0200, Herbert Poetzl wrote:

> > Yes, but that's S_NOATIME in inode->i_flags, not MS_NOATIME in sb->s_flags.
> > Actually, I've been wrong here - we *do* need that check, since there are
> > filesystems that force noatime or nodiratime.
> 
> so we keep them?

yes.

> > it on remount.  Most of those are my fault - I've missed the remount side of
> > things in readdir patch.  They should have nodiratime always on to match
> > the original behaviour.  IMO, both (a) and (b) should be handled by a new
> > field - sb->s_forced_flags.  do_remount_sb() would set those in flags before
> > doing anything else.  Note that assignment to ->s_flags in do_remount_sb()
> > is not safe - e.g. ext[23] can get forced r/o by fs error and if that
> > happens after return from ->remount_sb() but before assignement, we are
> > screwed.  IOW, do_remount_sb() will need more work.
> 
> are you going to do this?

Yes - for now I'll do a fix that doesn't change API (IOW, add/update
->remount_fs() to filesystems with forced flags, forced r/o has the
same problems); we'll see what should be done in the long run when
the things clean up a bit.  I'd rather avoid struct super_block changes
that would have to be reverted soon.
 
> >> simple, to match the MS_* counterparts, something which
> >> actually confused me in the first place (in the code)
> 
> so is this okay? actually I'd prefer to use the same
> values for the MNT_NOATIME and MNT_NODIRATIME too ...
> (as in the previous version I did)

Hmm...  Potentially we are breaking ABI for no good reason, since these
defines are visible to out-of-tree code.  I don't think that we should
care about matching MS_... stuff, simply because MS_... encoding is ugly
as hell and there's no reason to use MNT_... and MS_... in the same
context.
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