Re: [PATCH] NFSV4 :All lock operations should be sent to the server for resolution

["J. Bruce Fields" <bfields@fieldses.org>]

On Fri, Jan 14, 2011 at 02:45:56PM +0800, Fu Liankun wrote:
> The RFC3530 describes that the client's all lock operations, including those
> requesting non-exclusive locks, should be sent to the server for resolution,
> even if it holds a read open delegation. But the kernel implements like that
> lock operations can be performed locally when a client holds an open
> delegation.
> 
> The following are the RFC3530 provisions for Open Delegation and File Locks:
> 
> 9.4.2.  Open Delegation and File Locks
> 
>    When a client holds a write open delegation, lock operations may be
>    performed locally.  This includes those required for mandatory file
>    locking.  This can be done since the delegation implies that there
>    can be no conflicting locks.  Similarly, all of the revalidations
>    that would normally be associated with obtaining locks and the
>    flushing of data associated with the releasing of locks need not be
>    done.
> 
>    When a client holds a read open delegation, lock operations are not
>    performed locally.  All lock operations, including those requesting
>    non-exclusive locks, are sent to the server for resolution.

Weird.  Can the rfc really be right about that?

I guess it does permit servers to allow write-locks on read-open files,
but it seems bizarre not to require them to break delegations in that
case.

--b.

> 
> Signed-off-by: Fu Liankun <fuliankun@cn.fujitsu.com>
> ---
>  fs/nfs/nfs4proc.c |    7 -------
>  1 files changed, 0 insertions(+), 7 deletions(-)
> 
> diff --git a/fs/nfs/nfs4proc.c b/fs/nfs/nfs4proc.c
> index 0f24cdf..3bba85b 100644
> --- a/fs/nfs/nfs4proc.c
> +++ b/fs/nfs/nfs4proc.c
> @@ -4215,13 +4215,6 @@ static int _nfs4_proc_setlk(struct nfs4_state *state, int cmd, struct file_lock
>  	if (status < 0)
>  		goto out;
>  	down_read(&nfsi->rwsem);
> -	if (test_bit(NFS_DELEGATED_STATE, &state->flags)) {
> -		/* Yes: cache locks! */
> -		/* ...but avoid races with delegation recall... */
> -		request->fl_flags = fl_flags & ~FL_SLEEP;
> -		status = do_vfs_lock(request->fl_file, request);
> -		goto out_unlock;
> -	}
>  	status = _nfs4_do_setlk(state, cmd, request, NFS_LOCK_NEW);
>  	if (status != 0)
>  		goto out_unlock;
> -- 
> 1.7.3.1
> 
> --
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