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

[Anna Schumaker <Anna.Schumaker@netapp.com>]

On 08/27/2014 03:09 PM, J. Bruce Fields wrote:
> 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.

I was expecting them to be temporary, and to get removed when the draft becomes an RFC.

> 
>> +
>> +	  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.

I was trying to cover the case where an application does:

	open(WRITE);
	seek(HOLE);
	write("blah");

I can change the code if that's not the way people use SEEK_HOLE / SEEK_DATA ...

Anna

> 
> --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
>>