Re: [PATCH 3/3] NFSD: Implement SEEK

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

On Wed, Aug 27, 2014 at 11:17:58AM -0400, bjschuma@netapp.com wrote:
> From: Anna Schumaker <Anna.Schumaker@netapp.com>
> 
> This patch adds server support for the NFS v4.2 operation SEEK, which
> returns the position of the next hole or data segment in a file.  This
> operation is off by default, and needs CONFIG_NFSD_V4_2_SEEK=y to be
> compiled.
> 
> Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
> ---
>  fs/nfsd/Kconfig      | 12 ++++++++++++
>  fs/nfsd/nfs4proc.c   | 47 +++++++++++++++++++++++++++++++++++++++++++++++
>  fs/nfsd/nfs4xdr.c    | 45 +++++++++++++++++++++++++++++++++++++++++++++
>  fs/nfsd/xdr4.h       | 14 ++++++++++++++
>  include/linux/nfs4.h |  5 +++++
>  5 files changed, 123 insertions(+)
> 
> diff --git a/fs/nfsd/Kconfig b/fs/nfsd/Kconfig
> index f994e75..804b20a 100644
> --- a/fs/nfsd/Kconfig
> +++ b/fs/nfsd/Kconfig
> @@ -81,6 +81,18 @@ config NFSD_V4
>  
>  	  If unsure, say N.
>  
> +config NFSD_V4_2_SEEK
> +	bool "Enable SEEK support for the NFS v4.2 server"
> +	depends on NFSD_V4
> +	help
> +	  Say Y here if you want to enable support for the NFS v4.2 operation
> +	  SEEK, which adds in SEEK_HOLE and SEEK_DATA support.
> +
> +	  WARNING: there is still a chance of backwards-incompatible protocol
> +	  changes.  This feature is targeted at developers and testers only.

I think now that we should instead confirm with the working group that
backwards-incompatible changes are done, and skip this warning.

I'll remove it in the labeled NFS case, which we've decided is "done"
even if the rest of the 4.2 draft isn't.

I also wonder if we should ditch these configuration options, or keep
them only temporarily.  It's not much code, so I think the only reason
to allow configuring it out is to temporarily protect people from
immature code.

> +
> +	  If unsure, say N.
> +
>  config NFSD_V4_SECURITY_LABEL
>  	bool "Provide Security Label support for NFSv4 server"
>  	depends on NFSD_V4 && SECURITY
> diff --git a/fs/nfsd/nfs4proc.c b/fs/nfsd/nfs4proc.c
> index 5e0dc52..f555eb2 100644
> --- a/fs/nfsd/nfs4proc.c
> +++ b/fs/nfsd/nfs4proc.c
> @@ -1013,6 +1013,45 @@ nfsd4_write(struct svc_rqst *rqstp, struct nfsd4_compound_state *cstate,
>  	return status;
>  }
>  
> +#ifdef CONFIG_NFSD_V4_2_SEEK
> +static __be32
> +nfsd4_seek(struct svc_rqst *rqstp, struct nfsd4_compound_state *cstate,
> +		struct nfsd4_seek *seek)
> +{
> +	struct file *file;
> +	__be32 status = nfs_ok;
> +
> +	status = nfs4_preprocess_stateid_op(SVC_NET(rqstp), cstate,
> +					    &seek->seek_stateid,
> +					    RD_STATE | WR_STATE, &file);

I think that should be just RD_STATE.

--b.


> +	if (status) {
> +		dprintk("NFSD: nfsd4_seek: couldn't process stateid!\n");
> +		return status;
> +	}
> +
> +	switch (seek->seek_whence) {
> +	case NFS4_CONTENT_DATA:
> +		seek->seek_pos = vfs_llseek(file, seek->seek_offset, SEEK_DATA);
> +		break;
> +	case NFS4_CONTENT_HOLE:
> +		seek->seek_pos = vfs_llseek(file, seek->seek_offset, SEEK_HOLE);
> +		break;
> +	default:
> +		status = nfserr_union_notsupp;
> +		goto out;
> +	}
> +
> +	if (seek->seek_pos < 0)
> +		status = nfserrno(seek->seek_pos);
> +	else if (seek->seek_pos >= i_size_read(file_inode(file)))
> +		seek->seek_eof = true;
> +
> +out:
> +	fput(file);
> +	return status;
> +}
> +#endif /* CONFIG_NFSD_V4_2_SEEK */
> +
>  /* This routine never returns NFS_OK!  If there are no other errors, it
>   * will return NFSERR_SAME or NFSERR_NOT_SAME depending on whether the
>   * attributes matched.  VERIFY is implemented by mapping NFSERR_SAME
> @@ -1881,6 +1920,14 @@ static struct nfsd4_operation nfsd4_ops[] = {
>  		.op_get_currentstateid = (stateid_getter)nfsd4_get_freestateid,
>  		.op_rsize_bop = (nfsd4op_rsize)nfsd4_only_status_rsize,
>  	},
> +
> +	/* NFSv4.2 operations */
> +#ifdef CONFIG_NFSD_V4_2_SEEK
> +	[OP_SEEK] = {
> +		.op_func = (nfsd4op_func)nfsd4_seek,
> +		.op_name = "OP_SEEK",
> +	},
> +#endif /* CONFIG_NFSD_V4_2_SEEK */
>  };
>  
>  int nfsd4_max_reply(struct svc_rqst *rqstp, struct nfsd4_op *op)
> diff --git a/fs/nfsd/nfs4xdr.c b/fs/nfsd/nfs4xdr.c
> index 94dde7b..5bedeb3 100644
> --- a/fs/nfsd/nfs4xdr.c
> +++ b/fs/nfsd/nfs4xdr.c
> @@ -1520,6 +1520,24 @@ static __be32 nfsd4_decode_reclaim_complete(struct nfsd4_compoundargs *argp, str
>  	DECODE_TAIL;
>  }
>  
> +#ifdef CONFIG_NFSD_V4_2_SEEK
> +static __be32
> +nfsd4_decode_seek(struct nfsd4_compoundargs *argp, struct nfsd4_seek *seek)
> +{
> +	DECODE_HEAD;
> +
> +	status = nfsd4_decode_stateid(argp, &seek->seek_stateid);
> +	if (status)
> +		return status;
> +
> +	READ_BUF(12);
> +	p = xdr_decode_hyper(p, &seek->seek_offset);
> +	seek->seek_whence = be32_to_cpup(p);
> +
> +	DECODE_TAIL;
> +}
> +#endif /* CONFIG_NFSD_V4_2_SEEK */
> +
>  static __be32
>  nfsd4_decode_noop(struct nfsd4_compoundargs *argp, void *p)
>  {
> @@ -1605,7 +1623,11 @@ static nfsd4_dec nfsd4_dec_ops[] = {
>  	[OP_OFFLOAD_CANCEL]	= (nfsd4_dec)nfsd4_decode_notsupp,
>  	[OP_OFFLOAD_STATUS]	= (nfsd4_dec)nfsd4_decode_notsupp,
>  	[OP_READ_PLUS]		= (nfsd4_dec)nfsd4_decode_notsupp,
> +#ifdef CONFIG_NFSD_V4_2_SEEK
> +	[OP_SEEK]		= (nfsd4_dec)nfsd4_decode_seek,
> +#else
>  	[OP_SEEK]		= (nfsd4_dec)nfsd4_decode_notsupp,
> +#endif /* CONFIG_NFSD_V4_2_SEEK */
>  	[OP_WRITE_SAME]		= (nfsd4_dec)nfsd4_decode_notsupp,
>  };
>  
> @@ -3764,6 +3786,24 @@ nfsd4_encode_test_stateid(struct nfsd4_compoundres *resp, __be32 nfserr,
>  	return nfserr;
>  }
>  
> +#ifdef CONFIG_NFSD_V4_2_SEEK
> +static __be32
> +nfsd4_encode_seek(struct nfsd4_compoundres *resp, __be32 nfserr,
> +		  struct nfsd4_seek *seek)
> +{
> +	__be32 *p;
> +
> +	if (nfserr)
> +		return nfserr;
> +
> +	p = xdr_reserve_space(&resp->xdr, 12);
> +	*p++ = cpu_to_be32(seek->seek_eof);
> +	p = xdr_encode_hyper(p, seek->seek_pos);
> +
> +	return nfserr;
> +}
> +#endif /* CONFIG_NFSD_V4_2_SEEK */
> +
>  static __be32
>  nfsd4_encode_noop(struct nfsd4_compoundres *resp, __be32 nfserr, void *p)
>  {
> @@ -3848,8 +3888,13 @@ static nfsd4_enc nfsd4_enc_ops[] = {
>  	[OP_OFFLOAD_CANCEL]	= (nfsd4_enc)nfsd4_encode_noop,
>  	[OP_OFFLOAD_STATUS]	= (nfsd4_enc)nfsd4_encode_noop,
>  	[OP_READ_PLUS]		= (nfsd4_enc)nfsd4_encode_noop,
> +#ifdef CONFIG_NFSD_V4_2_SEEK
> +	[OP_SEEK]		= (nfsd4_enc)nfsd4_encode_seek,
> +#else
>  	[OP_SEEK]		= (nfsd4_enc)nfsd4_encode_noop,
> +#endif /* CONFIG_NFSD_V4_2_SEEK */
>  	[OP_WRITE_SAME]		= (nfsd4_enc)nfsd4_encode_noop,
> +	[OP_IO_ADVISE]		= (nfsd4_enc)nfsd4_encode_noop,
>  };
>  
>  /*
> diff --git a/fs/nfsd/xdr4.h b/fs/nfsd/xdr4.h
> index 465e779..5720e94 100644
> --- a/fs/nfsd/xdr4.h
> +++ b/fs/nfsd/xdr4.h
> @@ -428,6 +428,17 @@ struct nfsd4_reclaim_complete {
>  	u32 rca_one_fs;
>  };
>  
> +struct nfsd4_seek {
> +	/* request */
> +	stateid_t	seek_stateid;
> +	loff_t		seek_offset;
> +	u32		seek_whence;
> +
> +	/* response */
> +	u32		seek_eof;
> +	loff_t		seek_pos;
> +};
> +
>  struct nfsd4_op {
>  	int					opnum;
>  	__be32					status;
> @@ -473,6 +484,9 @@ struct nfsd4_op {
>  		struct nfsd4_reclaim_complete	reclaim_complete;
>  		struct nfsd4_test_stateid	test_stateid;
>  		struct nfsd4_free_stateid	free_stateid;
> +
> +		/* NFSv4.2 */
> +		struct nfsd4_seek		seek;
>  	} u;
>  	struct nfs4_replay *			replay;
>  };
> diff --git a/include/linux/nfs4.h b/include/linux/nfs4.h
> index cf38224..026b0c0 100644
> --- a/include/linux/nfs4.h
> +++ b/include/linux/nfs4.h
> @@ -550,4 +550,9 @@ struct nfs4_deviceid {
>  	char data[NFS4_DEVICEID4_SIZE];
>  };
>  
> +enum data_content4 {
> +	NFS4_CONTENT_DATA		= 0,
> +	NFS4_CONTENT_HOLE		= 1,
> +};
> +
>  #endif
> -- 
> 2.1.0
>