[v3,3/5] NFS: Add basic READ_PLUS support

Commit Message

Schumaker, Anna March 16, 2015, 9:17 p.m. UTC

This patch adds support for decoding a single NFS4_CONTENT_DATA or
NFS4_CONTENT_HOLE segment returned by the server.  This gives a simple
implementation that does not need to spent a lot of time shifting data
arount.

Signed-off-by: Anna Schumaker <[e-mail]>
---
 fs/nfs/nfs42xdr.c         | 158 ++++++++++++++++++++++++++++++++++++++++++++++
 fs/nfs/nfs4proc.c         |  30 ++++++++-
 fs/nfs/nfs4xdr.c          |   1 +
 include/linux/nfs4.h      |   1 +
 include/linux/nfs_fs_sb.h |   1 +
 include/linux/nfs_xdr.h   |   2 +-
 6 files changed, 190 insertions(+), 3 deletions(-)

Comments

J. Bruce Fields March 17, 2015, 7:14 p.m. UTC | #1

On Mon, Mar 16, 2015 at 05:17:44PM -0400, Anna Schumaker wrote:
> This patch adds support for decoding a single NFS4_CONTENT_DATA or
> NFS4_CONTENT_HOLE segment returned by the server.  This gives a simple
> implementation that does not need to spent a lot of time shifting data
> arount.

So to make sure I understand the code correctly: if the server returns
(say) 10 segments, the client won't error out--it will just use the
information from the first segment, ignore the remaining 9, and send
more reads if necessary to get the rest.

So that looks simple and correct.  The worst case for performance would
probably be reading a file that alternates small data and hole segments.

--b.

> 
> Signed-off-by: Anna Schumaker <[e-mail]>
> ---
>  fs/nfs/nfs42xdr.c         | 158 ++++++++++++++++++++++++++++++++++++++++++++++
>  fs/nfs/nfs4proc.c         |  30 ++++++++-
>  fs/nfs/nfs4xdr.c          |   1 +
>  include/linux/nfs4.h      |   1 +
>  include/linux/nfs_fs_sb.h |   1 +
>  include/linux/nfs_xdr.h   |   2 +-
>  6 files changed, 190 insertions(+), 3 deletions(-)
> 
> diff --git a/fs/nfs/nfs42xdr.c b/fs/nfs/nfs42xdr.c
> index 1a25b27..4d7bd89 100644
> --- a/fs/nfs/nfs42xdr.c
> +++ b/fs/nfs/nfs42xdr.c
> @@ -13,6 +13,14 @@
>  #define encode_deallocate_maxsz		(op_encode_hdr_maxsz + \
>  					 encode_fallocate_maxsz)
>  #define decode_deallocate_maxsz		(op_decode_hdr_maxsz)
> +#define encode_read_plus_maxsz		(op_encode_hdr_maxsz + \
> +					 encode_stateid_maxsz + 3)
> +#define decode_read_plus_maxsz		(op_decode_hdr_maxsz + \
> +					 1 /* rpr_eof */ + \
> +					 1 /* rpr_contents count */ + \
> +					 1 /* data_content4 */ + \
> +					 2 /* data_info4.di_offset */ + \
> +					 2 /* data_info4.di_length */)
>  #define encode_seek_maxsz		(op_encode_hdr_maxsz + \
>  					 encode_stateid_maxsz + \
>  					 2 /* offset */ + \
> @@ -39,6 +47,12 @@
>  					 decode_putfh_maxsz + \
>  					 decode_deallocate_maxsz + \
>  					 decode_getattr_maxsz)
> +#define NFS4_enc_read_plus_sz		(compound_encode_hdr_maxsz + \
> +					 encode_putfh_maxsz + \
> +					 encode_read_plus_maxsz)
> +#define NFS4_dec_read_plus_sz		(compound_decode_hdr_maxsz + \
> +					 decode_putfh_maxsz + \
> +					 decode_read_plus_maxsz)
>  #define NFS4_enc_seek_sz		(compound_encode_hdr_maxsz + \
>  					 encode_putfh_maxsz + \
>  					 encode_seek_maxsz)
> @@ -71,6 +85,16 @@ static void encode_deallocate(struct xdr_stream *xdr,
>  	encode_fallocate(xdr, args);
>  }
>  
> +static void encode_read_plus(struct xdr_stream *xdr,
> +			     struct nfs_pgio_args *args,
> +			     struct compound_hdr *hdr)
> +{
> +	encode_op_hdr(xdr, OP_READ_PLUS, decode_read_plus_maxsz, hdr);
> +	encode_nfs4_stateid(xdr, &args->stateid);
> +	encode_uint64(xdr, args->offset);
> +	encode_uint32(xdr, args->count);
> +}
> +
>  static void encode_seek(struct xdr_stream *xdr,
>  			struct nfs42_seek_args *args,
>  			struct compound_hdr *hdr)
> @@ -120,6 +144,28 @@ static void nfs4_xdr_enc_deallocate(struct rpc_rqst *req,
>  }
>  
>  /*
> + * Encode READ_PLUS request
> + */
> +static void nfs4_xdr_enc_read_plus(struct rpc_rqst *req,
> +				   struct xdr_stream *xdr,
> +				   struct nfs_pgio_args *args)
> +{
> +	struct compound_hdr hdr = {
> +		.minorversion = nfs4_xdr_minorversion(&args->seq_args),
> +	};
> +
> +	encode_compound_hdr(xdr, req, &hdr);
> +	encode_sequence(xdr, &args->seq_args, &hdr);
> +	encode_putfh(xdr, args->fh, &hdr);
> +	encode_read_plus(xdr, args, &hdr);
> +
> +	xdr_inline_pages(&req->rq_rcv_buf, hdr.replen << 2,
> +			 args->pages, args->pgbase, args->count);
> +	req->rq_rcv_buf.flags |= XDRBUF_READ;
> +	encode_nops(&hdr);
> +}
> +
> +/*
>   * Encode SEEK request
>   */
>  static void nfs4_xdr_enc_seek(struct rpc_rqst *req,
> @@ -147,6 +193,92 @@ static int decode_deallocate(struct xdr_stream *xdr, struct nfs42_falloc_res *re
>  	return decode_op_hdr(xdr, OP_DEALLOCATE);
>  }
>  
> +static int decode_read_plus_data(struct xdr_stream *xdr, struct nfs_pgio_res *res)
> +{
> +	__be32 *p;
> +	uint32_t count, recvd;
> +	uint64_t offset;
> +
> +	p = xdr_inline_decode(xdr, 8 + 4);
> +	if (unlikely(!p))
> +		goto out_overflow;
> +
> +	p = xdr_decode_hyper(p, &offset);
> +	count = be32_to_cpup(p);
> +
> +	recvd = xdr_read_pages(xdr, count);
> +	if (recvd < count)
> +		res->eof = 0;
> +
> +	res->count = recvd;
> +	return 0;
> +out_overflow:
> +	print_overflow_msg(__func__, xdr);
> +	return -EIO;
> +}
> +
> +static int decode_read_plus_hole(struct xdr_stream *xdr, struct nfs_pgio_res *res)
> +{
> +	__be32 *p;
> +	uint64_t offset, length;
> +	size_t recvd;
> +
> +	p = xdr_inline_decode(xdr, 8 + 8);
> +	if (unlikely(!p))
> +		goto out_overflow;
> +
> +	p = xdr_decode_hyper(p, &offset);
> +	p = xdr_decode_hyper(p, &length);
> +
> +	recvd = xdr_expand_hole(xdr, 0, length);
> +	if (recvd < length)
> +		res->eof = 0;
> +
> +	res->count = recvd;
> +	return 0;
> +out_overflow:
> +	print_overflow_msg(__func__, xdr);
> +	return -EIO;
> +}
> +
> +static int decode_read_plus(struct xdr_stream *xdr, struct nfs_pgio_res *res)
> +{
> +	__be32 *p;
> +	int status, type;
> +	uint32_t segments;
> +
> +	status = decode_op_hdr(xdr, OP_READ_PLUS);
> +	if (status)
> +		return status;
> +
> +	p = xdr_inline_decode(xdr, 4 + 4);
> +	if (unlikely(!p))
> +		goto out_overflow;
> +
> +	res->count = 0;
> +	res->eof = be32_to_cpup(p++);
> +	segments = be32_to_cpup(p++);
> +	if (segments == 0)
> +		return 0;
> +
> +	p = xdr_inline_decode(xdr, 4);
> +	if (unlikely(!p))
> +		goto out_overflow;
> +
> +	type = be32_to_cpup(p++);
> +	if (type == NFS4_CONTENT_DATA)
> +		status = decode_read_plus_data(xdr, res);
> +	else
> +		status = decode_read_plus_hole(xdr, res);
> +
> +	if (segments > 1)
> +		res->eof = 0;
> +	return status;
> +out_overflow:
> +	print_overflow_msg(__func__, xdr);
> +	return -EIO;
> +}
> +
>  static int decode_seek(struct xdr_stream *xdr, struct nfs42_seek_res *res)
>  {
>  	int status;
> @@ -224,6 +356,32 @@ out:
>  }
>  
>  /*
> + * Decode READ_PLUS request
> + */
> +static int nfs4_xdr_dec_read_plus(struct rpc_rqst *rqstp,
> +				  struct xdr_stream *xdr,
> +				  struct nfs_pgio_res *res)
> +{
> +	struct compound_hdr hdr;
> +	int status;
> +
> +	status = decode_compound_hdr(xdr, &hdr);
> +	if (status)
> +		goto out;
> +	status = decode_sequence(xdr, &res->seq_res, rqstp);
> +	if (status)
> +		goto out;
> +	status = decode_putfh(xdr);
> +	if (status)
> +		goto out;
> +	status = decode_read_plus(xdr, res);
> +	if (!status)
> +		status = res->count;
> +out:
> +	return status;
> +}
> +
> +/*
>   * Decode SEEK request
>   */
>  static int nfs4_xdr_dec_seek(struct rpc_rqst *rqstp,
> diff --git a/fs/nfs/nfs4proc.c b/fs/nfs/nfs4proc.c
> index 9ff8c63..175d01f 100644
> --- a/fs/nfs/nfs4proc.c
> +++ b/fs/nfs/nfs4proc.c
> @@ -68,6 +68,10 @@
>  
>  #include "nfs4trace.h"
>  
> +#ifdef CONFIG_NFS_V4_2
> +#include "nfs42.h"
> +#endif /* CONFIG_NFS_V4_2 */
> +
>  #define NFSDBG_FACILITY		NFSDBG_PROC
>  
>  #define NFS4_POLL_RETRY_MIN	(HZ/10)
> @@ -4187,9 +4191,15 @@ static bool nfs4_read_stateid_changed(struct rpc_task *task,
>  
>  static int nfs4_read_done(struct rpc_task *task, struct nfs_pgio_header *hdr)
>  {
> -
> +	struct nfs_server *server = NFS_SERVER(hdr->inode);
>  	dprintk("--> %s\n", __func__);
>  
> +	if ((server->caps & NFS_CAP_READ_PLUS) && (task->tk_status == -ENOTSUPP)) {
> +		server->caps &= ~NFS_CAP_READ_PLUS;
> +		if (rpc_restart_call_prepare(task))
> +			task->tk_status = 0;
> +		return -EAGAIN;
> +	}
>  	if (!nfs4_sequence_done(task, &hdr->res.seq_res))
>  		return -EAGAIN;
>  	if (nfs4_read_stateid_changed(task, &hdr->args))
> @@ -4198,12 +4208,27 @@ static int nfs4_read_done(struct rpc_task *task, struct nfs_pgio_header *hdr)
>  				    nfs4_read_done_cb(task, hdr);
>  }
>  
> +#ifdef CONFIG_NFS_V4_2
> +static void nfs42_read_plus_support(struct nfs_server *server, struct rpc_message *msg)
> +{
> +	if (server->caps & NFS_CAP_READ_PLUS)
> +		msg->rpc_proc = &nfs4_procedures[NFSPROC4_CLNT_READ_PLUS];
> +	else
> +		msg->rpc_proc = &nfs4_procedures[NFSPROC4_CLNT_READ];
> +}
> +#else
> +static void nfs42_read_plus_support(struct nfs_server *server, struct rpc_message *msg)
> +{
> +	msg->rpc_proc = &nfs4_procedures[NFSPROC4_CLNT_READ];
> +}
> +#endif /* CONFIG_NFS_V4_2 */
> +
>  static void nfs4_proc_read_setup(struct nfs_pgio_header *hdr,
>  				 struct rpc_message *msg)
>  {
>  	hdr->timestamp   = jiffies;
>  	hdr->pgio_done_cb = nfs4_read_done_cb;
> -	msg->rpc_proc = &nfs4_procedures[NFSPROC4_CLNT_READ];
> +	nfs42_read_plus_support(NFS_SERVER(hdr->inode), msg);
>  	nfs4_init_sequence(&hdr->args.seq_args, &hdr->res.seq_res, 0);
>  }
>  
> @@ -8556,6 +8581,7 @@ static const struct nfs4_minor_version_ops nfs_v4_2_minor_ops = {
>  		| NFS_CAP_ATOMIC_OPEN_V1
>  		| NFS_CAP_ALLOCATE
>  		| NFS_CAP_DEALLOCATE
> +		| NFS_CAP_READ_PLUS
>  		| NFS_CAP_SEEK,
>  	.init_client = nfs41_init_client,
>  	.shutdown_client = nfs41_shutdown_client,
> diff --git a/fs/nfs/nfs4xdr.c b/fs/nfs/nfs4xdr.c
> index 6b28a60..39e521a 100644
> --- a/fs/nfs/nfs4xdr.c
> +++ b/fs/nfs/nfs4xdr.c
> @@ -7421,6 +7421,7 @@ struct rpc_procinfo	nfs4_procedures[] = {
>  	PROC(SEEK,		enc_seek,		dec_seek),
>  	PROC(ALLOCATE,		enc_allocate,		dec_allocate),
>  	PROC(DEALLOCATE,	enc_deallocate,		dec_deallocate),
> +	PROC(READ_PLUS,		enc_read_plus,		dec_read_plus),
>  #endif /* CONFIG_NFS_V4_2 */
>  };
>  
> diff --git a/include/linux/nfs4.h b/include/linux/nfs4.h
> index ed43cb7..2470e62 100644
> --- a/include/linux/nfs4.h
> +++ b/include/linux/nfs4.h
> @@ -493,6 +493,7 @@ enum {
>  	NFSPROC4_CLNT_SEEK,
>  	NFSPROC4_CLNT_ALLOCATE,
>  	NFSPROC4_CLNT_DEALLOCATE,
> +	NFSPROC4_CLNT_READ_PLUS,
>  };
>  
>  /* nfs41 types */
> diff --git a/include/linux/nfs_fs_sb.h b/include/linux/nfs_fs_sb.h
> index 5e1273d..728d928 100644
> --- a/include/linux/nfs_fs_sb.h
> +++ b/include/linux/nfs_fs_sb.h
> @@ -237,5 +237,6 @@ struct nfs_server {
>  #define NFS_CAP_SEEK		(1U << 19)
>  #define NFS_CAP_ALLOCATE	(1U << 20)
>  #define NFS_CAP_DEALLOCATE	(1U << 21)
> +#define NFS_CAP_READ_PLUS	(1U << 22)
>  
>  #endif
> diff --git a/include/linux/nfs_xdr.h b/include/linux/nfs_xdr.h
> index 93ab607..35651b2 100644
> --- a/include/linux/nfs_xdr.h
> +++ b/include/linux/nfs_xdr.h
> @@ -520,7 +520,7 @@ struct nfs_pgio_args {
>  struct nfs_pgio_res {
>  	struct nfs4_sequence_res	seq_res;
>  	struct nfs_fattr *	fattr;
> -	__u32			count;
> +	__u64			count;
>  	__u32			op_status;
>  	int			eof;		/* used by read */
>  	struct nfs_writeverf *	verf;		/* used by write */
> -- 
> 2.3.3
> 
> --
> To unsubscribe from this list: send the line "unsubscribe linux-nfs" in
> the body of a message to [e-mail]
> More majordomo info at  http://vger.kernel.org/majordomo-info.html
--
To unsubscribe from this list: send the line "unsubscribe linux-nfs" in
the body of a message to [e-mail]
More majordomo info at  http://vger.kernel.org/majordomo-info.html

Patch

diff --git a/fs/nfs/nfs42xdr.c b/fs/nfs/nfs42xdr.c
index 1a25b27..4d7bd89 100644
--- a/fs/nfs/nfs42xdr.c
+++ b/fs/nfs/nfs42xdr.c
@@ -13,6 +13,14 @@ 
 #define encode_deallocate_maxsz		(op_encode_hdr_maxsz + \
 					 encode_fallocate_maxsz)
 #define decode_deallocate_maxsz		(op_decode_hdr_maxsz)
+#define encode_read_plus_maxsz		(op_encode_hdr_maxsz + \
+					 encode_stateid_maxsz + 3)
+#define decode_read_plus_maxsz		(op_decode_hdr_maxsz + \
+					 1 /* rpr_eof */ + \
+					 1 /* rpr_contents count */ + \
+					 1 /* data_content4 */ + \
+					 2 /* data_info4.di_offset */ + \
+					 2 /* data_info4.di_length */)
 #define encode_seek_maxsz		(op_encode_hdr_maxsz + \
 					 encode_stateid_maxsz + \
 					 2 /* offset */ + \
@@ -39,6 +47,12 @@ 
 					 decode_putfh_maxsz + \
 					 decode_deallocate_maxsz + \
 					 decode_getattr_maxsz)
+#define NFS4_enc_read_plus_sz		(compound_encode_hdr_maxsz + \
+					 encode_putfh_maxsz + \
+					 encode_read_plus_maxsz)
+#define NFS4_dec_read_plus_sz		(compound_decode_hdr_maxsz + \
+					 decode_putfh_maxsz + \
+					 decode_read_plus_maxsz)
 #define NFS4_enc_seek_sz		(compound_encode_hdr_maxsz + \
 					 encode_putfh_maxsz + \
 					 encode_seek_maxsz)
@@ -71,6 +85,16 @@  static void encode_deallocate(struct xdr_stream *xdr,
 	encode_fallocate(xdr, args);
 }
 
+static void encode_read_plus(struct xdr_stream *xdr,
+			     struct nfs_pgio_args *args,
+			     struct compound_hdr *hdr)
+{
+	encode_op_hdr(xdr, OP_READ_PLUS, decode_read_plus_maxsz, hdr);
+	encode_nfs4_stateid(xdr, &args->stateid);
+	encode_uint64(xdr, args->offset);
+	encode_uint32(xdr, args->count);
+}
+
 static void encode_seek(struct xdr_stream *xdr,
 			struct nfs42_seek_args *args,
 			struct compound_hdr *hdr)
@@ -120,6 +144,28 @@  static void nfs4_xdr_enc_deallocate(struct rpc_rqst *req,
 }
 
 /*
+ * Encode READ_PLUS request
+ */
+static void nfs4_xdr_enc_read_plus(struct rpc_rqst *req,
+				   struct xdr_stream *xdr,
+				   struct nfs_pgio_args *args)
+{
+	struct compound_hdr hdr = {
+		.minorversion = nfs4_xdr_minorversion(&args->seq_args),
+	};
+
+	encode_compound_hdr(xdr, req, &hdr);
+	encode_sequence(xdr, &args->seq_args, &hdr);
+	encode_putfh(xdr, args->fh, &hdr);
+	encode_read_plus(xdr, args, &hdr);
+
+	xdr_inline_pages(&req->rq_rcv_buf, hdr.replen << 2,
+			 args->pages, args->pgbase, args->count);
+	req->rq_rcv_buf.flags |= XDRBUF_READ;
+	encode_nops(&hdr);
+}
+
+/*
  * Encode SEEK request
  */
 static void nfs4_xdr_enc_seek(struct rpc_rqst *req,
@@ -147,6 +193,92 @@  static int decode_deallocate(struct xdr_stream *xdr, struct nfs42_falloc_res *re
 	return decode_op_hdr(xdr, OP_DEALLOCATE);
 }
 
+static int decode_read_plus_data(struct xdr_stream *xdr, struct nfs_pgio_res *res)
+{
+	__be32 *p;
+	uint32_t count, recvd;
+	uint64_t offset;
+
+	p = xdr_inline_decode(xdr, 8 + 4);
+	if (unlikely(!p))
+		goto out_overflow;
+
+	p = xdr_decode_hyper(p, &offset);
+	count = be32_to_cpup(p);
+
+	recvd = xdr_read_pages(xdr, count);
+	if (recvd < count)
+		res->eof = 0;
+
+	res->count = recvd;
+	return 0;
+out_overflow:
+	print_overflow_msg(__func__, xdr);
+	return -EIO;
+}
+
+static int decode_read_plus_hole(struct xdr_stream *xdr, struct nfs_pgio_res *res)
+{
+	__be32 *p;
+	uint64_t offset, length;
+	size_t recvd;
+
+	p = xdr_inline_decode(xdr, 8 + 8);
+	if (unlikely(!p))
+		goto out_overflow;
+
+	p = xdr_decode_hyper(p, &offset);
+	p = xdr_decode_hyper(p, &length);
+
+	recvd = xdr_expand_hole(xdr, 0, length);
+	if (recvd < length)
+		res->eof = 0;
+
+	res->count = recvd;
+	return 0;
+out_overflow:
+	print_overflow_msg(__func__, xdr);
+	return -EIO;
+}
+
+static int decode_read_plus(struct xdr_stream *xdr, struct nfs_pgio_res *res)
+{
+	__be32 *p;
+	int status, type;
+	uint32_t segments;
+
+	status = decode_op_hdr(xdr, OP_READ_PLUS);
+	if (status)
+		return status;
+
+	p = xdr_inline_decode(xdr, 4 + 4);
+	if (unlikely(!p))
+		goto out_overflow;
+
+	res->count = 0;
+	res->eof = be32_to_cpup(p++);
+	segments = be32_to_cpup(p++);
+	if (segments == 0)
+		return 0;
+
+	p = xdr_inline_decode(xdr, 4);
+	if (unlikely(!p))
+		goto out_overflow;
+
+	type = be32_to_cpup(p++);
+	if (type == NFS4_CONTENT_DATA)
+		status = decode_read_plus_data(xdr, res);
+	else
+		status = decode_read_plus_hole(xdr, res);
+
+	if (segments > 1)
+		res->eof = 0;
+	return status;
+out_overflow:
+	print_overflow_msg(__func__, xdr);
+	return -EIO;
+}
+
 static int decode_seek(struct xdr_stream *xdr, struct nfs42_seek_res *res)
 {
 	int status;
@@ -224,6 +356,32 @@  out:
 }
 
 /*
+ * Decode READ_PLUS request
+ */
+static int nfs4_xdr_dec_read_plus(struct rpc_rqst *rqstp,
+				  struct xdr_stream *xdr,
+				  struct nfs_pgio_res *res)
+{
+	struct compound_hdr hdr;
+	int status;
+
+	status = decode_compound_hdr(xdr, &hdr);
+	if (status)
+		goto out;
+	status = decode_sequence(xdr, &res->seq_res, rqstp);
+	if (status)
+		goto out;
+	status = decode_putfh(xdr);
+	if (status)
+		goto out;
+	status = decode_read_plus(xdr, res);
+	if (!status)
+		status = res->count;
+out:
+	return status;
+}
+
+/*
  * Decode SEEK request
  */
 static int nfs4_xdr_dec_seek(struct rpc_rqst *rqstp,
diff --git a/fs/nfs/nfs4proc.c b/fs/nfs/nfs4proc.c
index 9ff8c63..175d01f 100644
--- a/fs/nfs/nfs4proc.c
+++ b/fs/nfs/nfs4proc.c
@@ -68,6 +68,10 @@ 
 
 #include "nfs4trace.h"
 
+#ifdef CONFIG_NFS_V4_2
+#include "nfs42.h"
+#endif /* CONFIG_NFS_V4_2 */
+
 #define NFSDBG_FACILITY		NFSDBG_PROC
 
 #define NFS4_POLL_RETRY_MIN	(HZ/10)
@@ -4187,9 +4191,15 @@  static bool nfs4_read_stateid_changed(struct rpc_task *task,
 
 static int nfs4_read_done(struct rpc_task *task, struct nfs_pgio_header *hdr)
 {
-
+	struct nfs_server *server = NFS_SERVER(hdr->inode);
 	dprintk("--> %s\n", __func__);
 
+	if ((server->caps & NFS_CAP_READ_PLUS) && (task->tk_status == -ENOTSUPP)) {
+		server->caps &= ~NFS_CAP_READ_PLUS;
+		if (rpc_restart_call_prepare(task))
+			task->tk_status = 0;
+		return -EAGAIN;
+	}
 	if (!nfs4_sequence_done(task, &hdr->res.seq_res))
 		return -EAGAIN;
 	if (nfs4_read_stateid_changed(task, &hdr->args))
@@ -4198,12 +4208,27 @@  static int nfs4_read_done(struct rpc_task *task, struct nfs_pgio_header *hdr)
 				    nfs4_read_done_cb(task, hdr);
 }
 
+#ifdef CONFIG_NFS_V4_2
+static void nfs42_read_plus_support(struct nfs_server *server, struct rpc_message *msg)
+{
+	if (server->caps & NFS_CAP_READ_PLUS)
+		msg->rpc_proc = &nfs4_procedures[NFSPROC4_CLNT_READ_PLUS];
+	else
+		msg->rpc_proc = &nfs4_procedures[NFSPROC4_CLNT_READ];
+}
+#else
+static void nfs42_read_plus_support(struct nfs_server *server, struct rpc_message *msg)
+{
+	msg->rpc_proc = &nfs4_procedures[NFSPROC4_CLNT_READ];
+}
+#endif /* CONFIG_NFS_V4_2 */
+
 static void nfs4_proc_read_setup(struct nfs_pgio_header *hdr,
 				 struct rpc_message *msg)
 {
 	hdr->timestamp   = jiffies;
 	hdr->pgio_done_cb = nfs4_read_done_cb;
-	msg->rpc_proc = &nfs4_procedures[NFSPROC4_CLNT_READ];
+	nfs42_read_plus_support(NFS_SERVER(hdr->inode), msg);
 	nfs4_init_sequence(&hdr->args.seq_args, &hdr->res.seq_res, 0);
 }
 
@@ -8556,6 +8581,7 @@  static const struct nfs4_minor_version_ops nfs_v4_2_minor_ops = {
 		| NFS_CAP_ATOMIC_OPEN_V1
 		| NFS_CAP_ALLOCATE
 		| NFS_CAP_DEALLOCATE
+		| NFS_CAP_READ_PLUS
 		| NFS_CAP_SEEK,
 	.init_client = nfs41_init_client,
 	.shutdown_client = nfs41_shutdown_client,
diff --git a/fs/nfs/nfs4xdr.c b/fs/nfs/nfs4xdr.c
index 6b28a60..39e521a 100644
--- a/fs/nfs/nfs4xdr.c
+++ b/fs/nfs/nfs4xdr.c
@@ -7421,6 +7421,7 @@  struct rpc_procinfo	nfs4_procedures[] = {
 	PROC(SEEK,		enc_seek,		dec_seek),
 	PROC(ALLOCATE,		enc_allocate,		dec_allocate),
 	PROC(DEALLOCATE,	enc_deallocate,		dec_deallocate),
+	PROC(READ_PLUS,		enc_read_plus,		dec_read_plus),
 #endif /* CONFIG_NFS_V4_2 */
 };
 
diff --git a/include/linux/nfs4.h b/include/linux/nfs4.h
index ed43cb7..2470e62 100644
--- a/include/linux/nfs4.h
+++ b/include/linux/nfs4.h
@@ -493,6 +493,7 @@  enum {
 	NFSPROC4_CLNT_SEEK,
 	NFSPROC4_CLNT_ALLOCATE,
 	NFSPROC4_CLNT_DEALLOCATE,
+	NFSPROC4_CLNT_READ_PLUS,
 };
 
 /* nfs41 types */
diff --git a/include/linux/nfs_fs_sb.h b/include/linux/nfs_fs_sb.h
index 5e1273d..728d928 100644
--- a/include/linux/nfs_fs_sb.h
+++ b/include/linux/nfs_fs_sb.h
@@ -237,5 +237,6 @@  struct nfs_server {
 #define NFS_CAP_SEEK		(1U << 19)
 #define NFS_CAP_ALLOCATE	(1U << 20)
 #define NFS_CAP_DEALLOCATE	(1U << 21)
+#define NFS_CAP_READ_PLUS	(1U << 22)
 
 #endif
diff --git a/include/linux/nfs_xdr.h b/include/linux/nfs_xdr.h
index 93ab607..35651b2 100644
--- a/include/linux/nfs_xdr.h
+++ b/include/linux/nfs_xdr.h
@@ -520,7 +520,7 @@  struct nfs_pgio_args {
 struct nfs_pgio_res {
 	struct nfs4_sequence_res	seq_res;
 	struct nfs_fattr *	fattr;
-	__u32			count;
+	__u64			count;
 	__u32			op_status;
 	int			eof;		/* used by read */
 	struct nfs_writeverf *	verf;		/* used by write */