Re: [pnfs] [PATCH] nfs41: get rid of unused struct nfs41_exchange_id_res members

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

On Wed, May 06, 2009 at 01:15:57AM +0300, Benny Halevy wrote:
> On 2009-05-06 01:12, Trond Myklebust wrote:
> > On Tue, 2009-05-05 at 23:35 +0300, Benny Halevy wrote:
> >> On 2009-05-05 23:28, Benny Halevy wrote:
> >>> On May. 05, 2009, 22:41 +0300, Trond Myklebust <trond.myklebust@fys.uio.no> wrote:
> >>>> On Tue, 2009-05-05 at 15:39 -0400, Trond Myklebust wrote:
> >>>>> On Tue, 2009-05-05 at 15:34 -0400, Trond Myklebust wrote:
> >>>>>> On Fri, 2009-05-01 at 23:14 +0300, Benny Halevy wrote:
> >>>>>>> struct nfs41_exchange_id_res is currently allocated on the stack
> >>>>>>> insanely taking over 2K of stack space due to the NFS4_OPAQUE_LIMIT (1K(
> >>>>>>> byte arrays embedded in server_owner and server_scope.
> >>>>>>> Since these are not in use yet, this patch gets rid of them for the
> >>>>>>> time being.
> >>>>>>>
> >>>>>>> Signed-off-by: Benny Halevy <bhalevy@panasas.com>
> >>>>>>> ---
> >>>>>>>  fs/nfs/nfs4xdr.c        |   27 ++++++++++++++-------------
> >>>>>>>  include/linux/nfs_xdr.h |    3 ---
> >>>>>>>  2 files changed, 14 insertions(+), 16 deletions(-)
> >>>>>>>
> >>>>>>> diff --git a/fs/nfs/nfs4xdr.c b/fs/nfs/nfs4xdr.c
> >>>>>>> index 80af0ae..3350d19 100644
> >>>>>>> --- a/fs/nfs/nfs4xdr.c
> >>>>>>> +++ b/fs/nfs/nfs4xdr.c
> >>>>>>> @@ -4185,8 +4185,8 @@ static int decode_delegreturn(struct xdr_stream *xdr)
> >>>>>>>  static int decode_exchange_id(struct xdr_stream *xdr,
> >>>>>>>  			      struct nfs41_exchange_id_res *res)
> >>>>>>>  {
> >>>>>>> -	uint32_t *p;
> >>>>>>> -	int status, dummy;
> >>>>>>> +	uint32_t *p, dummy;
> >>>> Oh, and 'p' _always_ has to be of type '__be32', otherwise the 'sparse'
> >>>> checker will yell at you.
> >>> Thanks!  I'll send a fixed version
> >>> of this patch and also look into the rest of the xdr code.
> >>>
> >>>>>>> +	int status;
> >>>>>>>  	struct nfs_client *clp = res->client;
> >>>>>>>  
> >>>>>>>  	status = decode_op_hdr(xdr, OP_EXCHANGE_ID);
> >>>>>>> @@ -4204,25 +4204,26 @@ static int decode_exchange_id(struct xdr_stream *xdr,
> >>>>>>>  	if (dummy != SP4_NONE)
> >>>>>>>  		return -EIO;
> >>>>>>>  
> >>>>>>> -	/* minor_id */
> >>>>>>> +	/* Throw away minor_id */
> >>>>>>>  	READ_BUF(8);
> >>>>>>> -	READ64(res->server_owner.minor_id);
> >>>>>>> +	p += 8;
> >>>>>>          ^^^^^^^^ Err... This isn't the same thing at all!
> >>> Ouch, of course.  What did I smoke that day?
> >>>
> >>>>>> You're suddenly skipping 10=words instead of the original 2. READ_BUF()
> >>>>>> will already take care of updating the 'p' pointer.
> >>> Which p?
> >>> It takes care of argp->p, not the local 'p' variable, doesn't it.
> >> Grr, I meant "xdr->p" of course, via xdr_inline_decode
> >> (argp is the server's READ_BUF, sigh)
> >>
> >>> p += 2 has an equivalent side effect on 'p' as doing READ64.
> >>> I can do "p = argp;" instead though to reset 'p' onto
> >> p = xdr->p; ...
> > 
> > Not necessary. Look again at the first line of the READ_BUF(nbytes)
> > macro:
> > 
> > 	p = xdr_inline_decode(xdr, nbytes);
> > 
> > So the value of 'p' is always correctly set to the beginning of the
> > buffer of length 'nbytes'.
> 
> Right, but then we want to skip over the buffer.
> 
> > 
> > I'll make a point of removing those macro references from the client
> > code in the next week or so. I'm getting really tired of them...
> 
> Yeah, I'm all for it.
> Let me know if there's anything I can do to help with that.

Ditto.  (I'll probably follow your example in fs/nfsd.)

--b.