Re: [RFC 07/27] pnfs: encode_layoutcommit

[Benny Halevy <bhalevy@panasas.com>]

On 2011-04-20 23:18, Trond Myklebust wrote:
> On Wed, 2011-04-20 at 20:27 +0300, Benny Halevy wrote:
>> Signed-off-by: Benny Halevy <bhalevy@panasas.com>
>> ---
>>  fs/nfs/nfs4xdr.c |   16 +++++++++++++---
>>  fs/nfs/pnfs.h    |    4 ++++
>>  2 files changed, 17 insertions(+), 3 deletions(-)
>>
>> diff --git a/fs/nfs/nfs4xdr.c b/fs/nfs/nfs4xdr.c
>> index 6b64dd8..4f7bef9 100644
>> --- a/fs/nfs/nfs4xdr.c
>> +++ b/fs/nfs/nfs4xdr.c
>> @@ -1877,6 +1877,7 @@ encode_layoutget(struct xdr_stream *xdr,
>>  
>>  static int
>>  encode_layoutcommit(struct xdr_stream *xdr,
>> +		    struct inode *inode,
>>  		    const struct nfs4_layoutcommit_args *args,
>>  		    struct compound_hdr *hdr)
>>  {
>> @@ -1885,7 +1886,7 @@ encode_layoutcommit(struct xdr_stream *xdr,
>>  	dprintk("%s: lbw: %llu type: %d\n", __func__, args->lastbytewritten,
>>  		NFS_SERVER(args->inode)->pnfs_curr_ld->id);
>>  
>> -	p = reserve_space(xdr, 48 + NFS4_STATEID_SIZE);
>> +	p = reserve_space(xdr, 44 + NFS4_STATEID_SIZE);
>>  	*p++ = cpu_to_be32(OP_LAYOUTCOMMIT);
>>  	/* Only whole file layouts */
>>  	p = xdr_encode_hyper(p, 0); /* offset */
>> @@ -1896,7 +1897,14 @@ encode_layoutcommit(struct xdr_stream *xdr,
>>  	p = xdr_encode_hyper(p, args->lastbytewritten);
>>  	*p++ = cpu_to_be32(0); /* Never send time_modify_changed */
>>  	*p++ = cpu_to_be32(NFS_SERVER(args->inode)->pnfs_curr_ld->id);/* type */
>> -	*p++ = cpu_to_be32(0); /* no file layout payload */
>> +
>> +	if (NFS_SERVER(inode)->pnfs_curr_ld->encode_layoutcommit)
>> +		NFS_SERVER(inode)->pnfs_curr_ld->encode_layoutcommit(
>> +			NFS_I(inode)->layout, xdr, args);
>> +	else {
>> +		p = reserve_space(xdr, 4);
>> +		*p = cpu_to_be32(0); /* no layout-type payload */
>> +	}
>>  
>>  	hdr->nops++;
>>  	hdr->replen += decode_layoutcommit_maxsz;
>> @@ -2759,6 +2767,8 @@ static void nfs4_xdr_enc_layoutcommit(struct rpc_rqst *req,
>>  				      struct xdr_stream *xdr,
>>  				      struct nfs4_layoutcommit_args *args)
>>  {
>> +	struct nfs4_layoutcommit_data *data =
>> +		container_of(args, struct nfs4_layoutcommit_data, args);
>>  	struct compound_hdr hdr = {
>>  		.minorversion = nfs4_xdr_minorversion(&args->seq_args),
>>  	};
>> @@ -2766,7 +2776,7 @@ static void nfs4_xdr_enc_layoutcommit(struct rpc_rqst *req,
>>  	encode_compound_hdr(xdr, req, &hdr);
>>  	encode_sequence(xdr, &args->seq_args, &hdr);
>>  	encode_putfh(xdr, NFS_FH(args->inode), &hdr);
>> -	encode_layoutcommit(xdr, args, &hdr);
>> +	encode_layoutcommit(xdr, data->args.inode, args, &hdr);
>>  	encode_getfattr(xdr, args->bitmask, &hdr);
>>  	encode_nops(&hdr);
>>  }
>> diff --git a/fs/nfs/pnfs.h b/fs/nfs/pnfs.h
>> index 51dcbc1..011885e 100644
>> --- a/fs/nfs/pnfs.h
>> +++ b/fs/nfs/pnfs.h
>> @@ -99,6 +99,10 @@ struct pnfs_layoutdriver_type {
>>  	/* device notification methods */
>>  	void (*delete_deviceid)(struct nfs4_deviceid *);
>>  
>> +	void (*encode_layoutcommit) (struct pnfs_layout_hdr *layoutid,
>> +				     struct xdr_stream *xdr,
>> +				     const struct nfs4_layoutcommit_args *args);
> 
> This too is way too ugly. Can't the layout payload be pre-encoded by the
> layout driver?
> 
> 

The contents for the objects layout driver are dynamic, representing
attribute-level metadata rather than something derived from the layout
that can be pre-encoded.  In addition, I'd like to avoid having to
alloc and free a buffer for this stuff and rather have the layout driver
encode whatever it needs in-line.

Benny