linux-kernel - Re: [patch 04/14] hpfs: dont call notify

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Date:	Wed, 23 Jul 2008 19:03:36 +0200
From:	Miklos Szeredi <miklos@...redi.hu>
To:	mikulas@...ax.karlin.mff.cuni.cz
CC:	miklos@...redi.hu, viro@...IV.linux.org.uk,
	linux-kernel@...r.kernel.org
Subject: Re: [patch 04/14] hpfs: dont call notify_change

On Wed, 23 Jul 2008, Mikulas Patocka wrote:
> What about down_write on i_alloc_sem --- notify change takes that and your 
> patch bypasses that.

i_alloc_sem is only relevant if filesystem uses blockdev_direct_IO()
and friends.  It is not used for anything else, so for hpfs there's no
need to surround take that lock.

Thanks,
Miklos

> > From: Miklos Szeredi <mszeredi@...e.cz>
> > 
> > hpfs_unlink() calls notify_change() to truncate the file before
> > deleting.  Replace with explicit call to hpfs_notify_change().
> > 
> > This is equivalent, except that:
> >  - security_inode_setattr() is not called before hpfs_notify_change()
> >  - fsnotify_change() is not called after hpfs_notify_change()
> > 
> > The truncation is just an implementation detail, so both the security
> > check and the notification are unnecessary.
> > 
> > Possibly even the ctime modification is wrong?
> > 
> > Signed-off-by: Miklos Szeredi <mszeredi@...e.cz>
> > CC: Mikulas Patocka <mikulas@...ax.karlin.mff.cuni.cz>
> > ---
> >  fs/hpfs/namei.c |    3 ++-
> >  1 file changed, 2 insertions(+), 1 deletion(-)
> > 
> > Index: linux-2.6/fs/hpfs/namei.c
> > ===================================================================
> > --- linux-2.6.orig/fs/hpfs/namei.c	2008-07-23 00:10:13.000000000 +0200
> > +++ linux-2.6/fs/hpfs/namei.c	2008-07-23 00:10:22.000000000 +0200
> > @@ -426,7 +426,8 @@ again:
> >  			/*printk("HPFS: truncating file before delete.\n");*/
> >  			newattrs.ia_size = 0;
> >  			newattrs.ia_valid = ATTR_SIZE | ATTR_CTIME;
> > -			err = notify_change(dentry, &newattrs);
> > +			newattrs.ia_ctime = current_fs_time(inode->i_sb);
> > +			err = hpfs_notify_change(dentry, &newattrs);
> >  			put_write_access(inode);
> >  			if (!err)
> >  				goto again;
> > 
> > --
> > 
> 
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