Re: [PATCH] VFS: Unlink should revoke all outstanding leases on file

[Trond Myklebust <trond.myklebust@fys.uio.no>]

On Fri, 2010-05-14 at 05:58 -0400, Jeff Layton wrote: 
> On Fri, 14 May 2010 17:35:27 +0800
> Mi Jinlong <mijinlong@cn.fujitsu.com> wrote:
> 
> > After client get one file's READ delegation through NFSv4,
> > server delete this file but don't reclaim the delegation.
> > 
> > This patch add break_lease at may_delete, which can reclaim delegations.
> > 
> > ---
> >  fs/namei.c |    2 +-
> >  1 files changed, 1 insertions(+), 1 deletions(-)
> > 
> > diff --git a/fs/namei.c b/fs/namei.c
> > index 16df727..17bafc1 100644
> > --- a/fs/namei.c
> > +++ b/fs/namei.c
> > @@ -1338,7 +1338,7 @@ static int may_delete(struct inode *dir,struct dentry *victim,int isdir)
> >  		return -ENOENT;
> >  	if (victim->d_flags & DCACHE_NFSFS_RENAMED)
> >  		return -EBUSY;
> > -	return 0;
> > +	return break_lease(victim->d_inode, FMODE_WRITE);
> >  }
> >  
> >  /*	Check whether we can create an object with dentry child in directory
> 
> This doesn't look right to me.
> 
> The fcntl(2) manpage basically says that leases should be broken if the
> file is opened for read or write, or is truncated. unlinks don't seem
> to fall into either category...
> 

Breaking the lease in this case is certainly a requirement for NFSv4
delegations. I've no idea what the CIFS oplock requirements are...

Cheers
  Trond