NFSv4.2: add client side XDR handling for extended attributes

Define the argument and response structures that will be used for
RFC 8276 extended attribute RPC calls, and implement the necessary
functions to encode/decode the extended attribute operations.
Signed-off-by: Frank van der Linden <fllinden@amazon.com>
Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>

fs/nfs/nfs42xdr.c

@@ -169,7 +169,6 @@
 					 decode_clone_maxsz + \
 					 decode_getattr_maxsz)
 
-#ifdef CONFIG_NFS_V4_2
 /* Not limited by NFS itself, limited by the generic xattr code */
 #define nfs4_xattr_name_maxsz   XDR_QUADLEN(XATTR_NAME_MAX)
 
@@ -241,7 +240,6 @@ const u32 nfs42_maxlistxattrs_overhead = ((RPC_MAX_HEADER_WITH_AUTH +
 					compound_decode_hdr_maxsz +
 					decode_sequence_maxsz +
 					decode_putfh_maxsz + 3) * XDR_UNIT);
-#endif
 
 static void encode_fallocate(struct xdr_stream *xdr,
 			     const struct nfs42_falloc_args *args)
@@ -407,6 +405,210 @@ static void encode_layouterror(struct xdr_stream *xdr,
 	encode_device_error(xdr, &args->errors[0]);
 }
 
+static void encode_setxattr(struct xdr_stream *xdr,
+			    const struct nfs42_setxattrargs *arg,
+			    struct compound_hdr *hdr)
+{
+	__be32 *p;
+
+	BUILD_BUG_ON(XATTR_CREATE != SETXATTR4_CREATE);
+	BUILD_BUG_ON(XATTR_REPLACE != SETXATTR4_REPLACE);
+
+	encode_op_hdr(xdr, OP_SETXATTR, decode_setxattr_maxsz, hdr);
+	p = reserve_space(xdr, 4);
+	*p = cpu_to_be32(arg->xattr_flags);
+	encode_string(xdr, strlen(arg->xattr_name), arg->xattr_name);
+	p = reserve_space(xdr, 4);
+	*p = cpu_to_be32(arg->xattr_len);
+	if (arg->xattr_len)
+		xdr_write_pages(xdr, arg->xattr_pages, 0, arg->xattr_len);
+}
+
+static int decode_setxattr(struct xdr_stream *xdr,
+			   struct nfs4_change_info *cinfo)
+{
+	int status;
+
+	status = decode_op_hdr(xdr, OP_SETXATTR);
+	if (status)
+		goto out;
+	status = decode_change_info(xdr, cinfo);
+out:
+	return status;
+}
+
+
+static void encode_getxattr(struct xdr_stream *xdr, const char *name,
+			    struct compound_hdr *hdr)
+{
+	encode_op_hdr(xdr, OP_GETXATTR, decode_getxattr_maxsz, hdr);
+	encode_string(xdr, strlen(name), name);
+}
+
+static int decode_getxattr(struct xdr_stream *xdr,
+			   struct nfs42_getxattrres *res,
+			   struct rpc_rqst *req)
+{
+	int status;
+	__be32 *p;
+	u32 len, rdlen;
+
+	status = decode_op_hdr(xdr, OP_GETXATTR);
+	if (status)
+		return status;
+
+	p = xdr_inline_decode(xdr, 4);
+	if (unlikely(!p))
+		return -EIO;
+
+	len = be32_to_cpup(p);
+	if (len > req->rq_rcv_buf.page_len)
+		return -ERANGE;
+
+	res->xattr_len = len;
+
+	if (len > 0) {
+		rdlen = xdr_read_pages(xdr, len);
+		if (rdlen < len)
+			return -EIO;
+	}
+
+	return 0;
+}
+
+static void encode_removexattr(struct xdr_stream *xdr, const char *name,
+			       struct compound_hdr *hdr)
+{
+	encode_op_hdr(xdr, OP_REMOVEXATTR, decode_removexattr_maxsz, hdr);
+	encode_string(xdr, strlen(name), name);
+}
+
+
+static int decode_removexattr(struct xdr_stream *xdr,
+			   struct nfs4_change_info *cinfo)
+{
+	int status;
+
+	status = decode_op_hdr(xdr, OP_REMOVEXATTR);
+	if (status)
+		goto out;
+
+	status = decode_change_info(xdr, cinfo);
+out:
+	return status;
+}
+
+static void encode_listxattrs(struct xdr_stream *xdr,
+			     const struct nfs42_listxattrsargs *arg,
+			     struct compound_hdr *hdr)
+{
+	__be32 *p;
+
+	encode_op_hdr(xdr, OP_LISTXATTRS, decode_listxattrs_maxsz + 1, hdr);
+
+	p = reserve_space(xdr, 12);
+	if (unlikely(!p))
+		return;
+
+	p = xdr_encode_hyper(p, arg->cookie);
+	/*
+	 * RFC 8276 says to specify the full max length of the LISTXATTRS
+	 * XDR reply. Count is set to the XDR length of the names array
+	 * plus the EOF marker. So, add the cookie and the names count.
+	 */
+	*p = cpu_to_be32(arg->count + 8 + 4);
+}
+
+static int decode_listxattrs(struct xdr_stream *xdr,
+			    struct nfs42_listxattrsres *res)
+{
+	int status;
+	__be32 *p;
+	u32 count, len, ulen;
+	size_t left, copied;
+	char *buf;
+
+	status = decode_op_hdr(xdr, OP_LISTXATTRS);
+	if (status) {
+		/*
+		 * Special case: for LISTXATTRS, NFS4ERR_TOOSMALL
+		 * should be translated to ERANGE.
+		 */
+		if (status == -ETOOSMALL)
+			status = -ERANGE;
+		goto out;
+	}
+
+	p = xdr_inline_decode(xdr, 8);
+	if (unlikely(!p))
+		return -EIO;
+
+	xdr_decode_hyper(p, &res->cookie);
+
+	p = xdr_inline_decode(xdr, 4);
+	if (unlikely(!p))
+		return -EIO;
+
+	left = res->xattr_len;
+	buf = res->xattr_buf;
+
+	count = be32_to_cpup(p);
+	copied = 0;
+
+	/*
+	 * We have asked for enough room to encode the maximum number
+	 * of possible attribute names, so everything should fit.
+	 *
+	 * But, don't rely on that assumption. Just decode entries
+	 * until they don't fit anymore, just in case the server did
+	 * something odd.
+	 */
+	while (count--) {
+		p = xdr_inline_decode(xdr, 4);
+		if (unlikely(!p))
+			return -EIO;
+
+		len = be32_to_cpup(p);
+		if (len > (XATTR_NAME_MAX - XATTR_USER_PREFIX_LEN)) {
+			status = -ERANGE;
+			goto out;
+		}
+
+		p = xdr_inline_decode(xdr, len);
+		if (unlikely(!p))
+			return -EIO;
+
+		ulen = len + XATTR_USER_PREFIX_LEN + 1;
+		if (buf) {
+			if (ulen > left) {
+				status = -ERANGE;
+				goto out;
+			}
+
+			memcpy(buf, XATTR_USER_PREFIX, XATTR_USER_PREFIX_LEN);
+			memcpy(buf + XATTR_USER_PREFIX_LEN, p, len);
+
+			buf[ulen - 1] = 0;
+			buf += ulen;
+			left -= ulen;
+		}
+		copied += ulen;
+	}
+
+	p = xdr_inline_decode(xdr, 4);
+	if (unlikely(!p))
+		return -EIO;
+
+	res->eof = be32_to_cpup(p);
+	res->copied = copied;
+
+out:
+	if (status == -ERANGE && res->xattr_len == XATTR_LIST_MAX)
+		status = -E2BIG;
+
+	return status;
+}
+
 /*
  * Encode ALLOCATE request
  */
@@ -1062,4 +1264,166 @@ static int nfs4_xdr_dec_layouterror(struct rpc_rqst *rqstp,
 	return status;
 }
 
+#ifdef CONFIG_NFS_V4_2
+static void nfs4_xdr_enc_setxattr(struct rpc_rqst *req, struct xdr_stream *xdr,
+				  const void *data)
+{
+	const struct nfs42_setxattrargs *args = data;
+	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_setxattr(xdr, args, &hdr);
+	encode_nops(&hdr);
+}
+
+static int nfs4_xdr_dec_setxattr(struct rpc_rqst *req, struct xdr_stream *xdr,
+				 void *data)
+{
+	struct nfs42_setxattrres *res = data;
+	struct compound_hdr hdr;
+	int status;
+
+	status = decode_compound_hdr(xdr, &hdr);
+	if (status)
+		goto out;
+	status = decode_sequence(xdr, &res->seq_res, req);
+	if (status)
+		goto out;
+	status = decode_putfh(xdr);
+	if (status)
+		goto out;
+
+	status = decode_setxattr(xdr, &res->cinfo);
+out:
+	return status;
+}
+
+static void nfs4_xdr_enc_getxattr(struct rpc_rqst *req, struct xdr_stream *xdr,
+				  const void *data)
+{
+	const struct nfs42_getxattrargs *args = data;
+	struct compound_hdr hdr = {
+		.minorversion = nfs4_xdr_minorversion(&args->seq_args),
+	};
+	size_t plen;
+
+	encode_compound_hdr(xdr, req, &hdr);
+	encode_sequence(xdr, &args->seq_args, &hdr);
+	encode_putfh(xdr, args->fh, &hdr);
+	encode_getxattr(xdr, args->xattr_name, &hdr);
+
+	plen = args->xattr_len ? args->xattr_len : XATTR_SIZE_MAX;
+
+	rpc_prepare_reply_pages(req, args->xattr_pages, 0, plen,
+	    hdr.replen);
+	req->rq_rcv_buf.flags |= XDRBUF_SPARSE_PAGES;
+
+	encode_nops(&hdr);
+}
+
+static int nfs4_xdr_dec_getxattr(struct rpc_rqst *rqstp,
+				 struct xdr_stream *xdr, void *data)
+{
+	struct nfs42_getxattrres *res = data;
+	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_getxattr(xdr, res, rqstp);
+out:
+	return status;
+}
+
+static void nfs4_xdr_enc_listxattrs(struct rpc_rqst *req,
+				    struct xdr_stream *xdr, const void *data)
+{
+	const struct nfs42_listxattrsargs *args = data;
+	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_listxattrs(xdr, args, &hdr);
+
+	rpc_prepare_reply_pages(req, args->xattr_pages, 0, args->count,
+	    hdr.replen);
+	req->rq_rcv_buf.flags |= XDRBUF_SPARSE_PAGES;
+
+	encode_nops(&hdr);
+}
+
+static int nfs4_xdr_dec_listxattrs(struct rpc_rqst *rqstp,
+				   struct xdr_stream *xdr, void *data)
+{
+	struct nfs42_listxattrsres *res = data;
+	struct compound_hdr hdr;
+	int status;
+
+	xdr_set_scratch_buffer(xdr, page_address(res->scratch), PAGE_SIZE);
+
+	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_listxattrs(xdr, res);
+out:
+	return status;
+}
+
+static void nfs4_xdr_enc_removexattr(struct rpc_rqst *req,
+				     struct xdr_stream *xdr, const void *data)
+{
+	const struct nfs42_removexattrargs *args = data;
+	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_removexattr(xdr, args->xattr_name, &hdr);
+	encode_nops(&hdr);
+}
+
+static int nfs4_xdr_dec_removexattr(struct rpc_rqst *req,
+				    struct xdr_stream *xdr, void *data)
+{
+	struct nfs42_removexattrres *res = data;
+	struct compound_hdr hdr;
+	int status;
+
+	status = decode_compound_hdr(xdr, &hdr);
+	if (status)
+		goto out;
+	status = decode_sequence(xdr, &res->seq_res, req);
+	if (status)
+		goto out;
+	status = decode_putfh(xdr);
+	if (status)
+		goto out;
+
+	status = decode_removexattr(xdr, &res->cinfo);
+out:
+	return status;
+}
+#endif
 #endif /* __LINUX_FS_NFS_NFS4_2XDR_H */

fs/nfs/nfs4xdr.c

@@ -7481,6 +7481,8 @@ static struct {
 	{ NFS4ERR_SYMLINK,	-ELOOP		},
 	{ NFS4ERR_OP_ILLEGAL,	-EOPNOTSUPP	},
 	{ NFS4ERR_DEADLOCK,	-EDEADLK	},
+	{ NFS4ERR_NOXATTR,	-ENODATA	},
+	{ NFS4ERR_XATTR2BIG,	-E2BIG		},
 	{ -1,			-EIO		}
 };
 
@@ -7609,6 +7611,10 @@ const struct rpc_procinfo nfs4_procedures[] = {
 	PROC42(COPY_NOTIFY,	enc_copy_notify,	dec_copy_notify),
 	PROC(LOOKUPP,		enc_lookupp,		dec_lookupp),
 	PROC42(LAYOUTERROR,	enc_layouterror,	dec_layouterror),
+	PROC42(GETXATTR,	enc_getxattr,		dec_getxattr),
+	PROC42(SETXATTR,	enc_setxattr,		dec_setxattr),
+	PROC42(LISTXATTRS,	enc_listxattrs,		dec_listxattrs),
+	PROC42(REMOVEXATTR,	enc_removexattr,	dec_removexattr),
 };
 
 static unsigned int nfs_version4_counts[ARRAY_SIZE(nfs4_procedures)];

include/linux/nfs_xdr.h

@@ -1498,7 +1498,64 @@ struct nfs42_seek_res {
 	u32	sr_eof;
 	u64	sr_offset;
 };
-#endif
+
+struct nfs42_setxattrargs {
+	struct nfs4_sequence_args	seq_args;
+	struct nfs_fh			*fh;
+	const char			*xattr_name;
+	u32				xattr_flags;
+	size_t				xattr_len;
+	struct page			**xattr_pages;
+};
+
+struct nfs42_setxattrres {
+	struct nfs4_sequence_res	seq_res;
+	struct nfs4_change_info		cinfo;
+};
+
+struct nfs42_getxattrargs {
+	struct nfs4_sequence_args	seq_args;
+	struct nfs_fh			*fh;
+	const char			*xattr_name;
+	size_t				xattr_len;
+	struct page			**xattr_pages;
+};
+
+struct nfs42_getxattrres {
+	struct nfs4_sequence_res	seq_res;
+	size_t				xattr_len;
+};
+
+struct nfs42_listxattrsargs {
+	struct nfs4_sequence_args	seq_args;
+	struct nfs_fh			*fh;
+	u32				count;
+	u64				cookie;
+	struct page			**xattr_pages;
+};
+
+struct nfs42_listxattrsres {
+	struct nfs4_sequence_res	seq_res;
+	struct page			*scratch;
+	void				*xattr_buf;
+	size_t				xattr_len;
+	u64				cookie;
+	bool				eof;
+	size_t				copied;
+};
+
+struct nfs42_removexattrargs {
+	struct nfs4_sequence_args	seq_args;
+	struct nfs_fh			*fh;
+	const char			*xattr_name;
+};
+
+struct nfs42_removexattrres {
+	struct nfs4_sequence_res	seq_res;
+	struct nfs4_change_info		cinfo;
+};
+
+#endif /* CONFIG_NFS_V4_2 */
 
 struct nfs_page;