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

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

On Wed, Aug 27, 2014 at 03:21:22PM -0400, Anna Schumaker wrote:
> 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.

OK.

In the security label case I guess there's one other issue, which is
that removing CONFIG_NFSD_V4_SECURITY_LABEL would mean adding a
previously unnecessary dependency on CONFIG_SECURITY.

--b.

> 
> > 
> >> +
> >> +	  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
> >>
>