Add support for FATTR4_OPEN_ARGUMENTS. This a new mechanism for the
client to discover what OPEN features the server supports.

Signed-off-by: Jeff Layton <jlayton@kernel.org>
---
 fs/nfsd/nfs4xdr.c | 50 ++++++++++++++++++++++++++++++++++++++++++++++++++
 fs/nfsd/nfsd.h    |  3 ++-
 2 files changed, 52 insertions(+), 1 deletion(-)

diff --git a/fs/nfsd/nfs4xdr.c b/fs/nfsd/nfs4xdr.c
index 8c48da421a07bf460ace6eddc140ed5fedffd408..3006406aac8332e27ca9310288c724954f804e75 100644
--- a/fs/nfsd/nfs4xdr.c
+++ b/fs/nfsd/nfs4xdr.c
@@ -55,6 +55,7 @@
 #include "netns.h"
 #include "pnfs.h"
 #include "filecache.h"
+#include "nfs4xdr_gen.h"
 
 #include "trace.h"
 
@@ -3387,6 +3388,54 @@ static __be32 nfsd4_encode_fattr4_xattr_support(struct xdr_stream *xdr,
 	return nfsd4_encode_bool(xdr, err == 0);
 }
 
+#define NFSD_OA_SHARE_ACCESS	(BIT(OPEN_ARGS_SHARE_ACCESS_READ)	| \
+				 BIT(OPEN_ARGS_SHARE_ACCESS_WRITE)	| \
+				 BIT(OPEN_ARGS_SHARE_ACCESS_BOTH))
+
+#define NFSD_OA_SHARE_DENY	(BIT(OPEN_ARGS_SHARE_DENY_NONE)		| \
+				 BIT(OPEN_ARGS_SHARE_DENY_READ)		| \
+				 BIT(OPEN_ARGS_SHARE_DENY_WRITE)	| \
+				 BIT(OPEN_ARGS_SHARE_DENY_BOTH))
+
+#define NFSD_OA_SHARE_ACCESS_WANT	(BIT(OPEN_ARGS_SHARE_ACCESS_WANT_ANY_DELEG)		| \
+					 BIT(OPEN_ARGS_SHARE_ACCESS_WANT_NO_DELEG)		| \
+					 BIT(OPEN_ARGS_SHARE_ACCESS_WANT_CANCEL))
+
+#define NFSD_OA_OPEN_CLAIM	(BIT(OPEN_ARGS_OPEN_CLAIM_NULL)		| \
+				 BIT(OPEN_ARGS_OPEN_CLAIM_PREVIOUS)	| \
+				 BIT(OPEN_ARGS_OPEN_CLAIM_DELEGATE_CUR)	| \
+				 BIT(OPEN_ARGS_OPEN_CLAIM_DELEGATE_PREV)| \
+				 BIT(OPEN_ARGS_OPEN_CLAIM_FH)		| \
+				 BIT(OPEN_ARGS_OPEN_CLAIM_DELEG_CUR_FH)	| \
+				 BIT(OPEN_ARGS_OPEN_CLAIM_DELEG_PREV_FH))
+
+#define NFSD_OA_CREATE_MODE	(BIT(OPEN_ARGS_CREATEMODE_UNCHECKED4)	| \
+				 BIT(OPEN_ARGS_CREATE_MODE_GUARDED)	| \
+				 BIT(OPEN_ARGS_CREATEMODE_EXCLUSIVE4)	| \
+				 BIT(OPEN_ARGS_CREATE_MODE_EXCLUSIVE4_1))
+
+static uint32_t oa_share_access = NFSD_OA_SHARE_ACCESS;
+static uint32_t oa_share_deny = NFSD_OA_SHARE_DENY;
+static uint32_t oa_share_access_want = NFSD_OA_SHARE_ACCESS_WANT;
+static uint32_t oa_open_claim = NFSD_OA_OPEN_CLAIM;
+static uint32_t oa_create_mode = NFSD_OA_CREATE_MODE;
+
+static const struct open_arguments4 nfsd_open_arguments = {
+	.oa_share_access = { .count = 1, .element = &oa_share_access },
+	.oa_share_deny = { .count = 1, .element = &oa_share_deny },
+	.oa_share_access_want = { .count = 1, .element = &oa_share_access_want },
+	.oa_open_claim = { .count = 1, .element = &oa_open_claim },
+	.oa_create_mode = { .count = 1, .element = &oa_create_mode },
+};
+
+static __be32 nfsd4_encode_fattr4_open_arguments(struct xdr_stream *xdr,
+						 const struct nfsd4_fattr_args *args)
+{
+	if (!xdrgen_encode_fattr4_open_arguments(xdr, &nfsd_open_arguments))
+		return nfserr_resource;
+	return nfs_ok;
+}
+
 static const nfsd4_enc_attr nfsd4_enc_fattr4_encode_ops[] = {
 	[FATTR4_SUPPORTED_ATTRS]	= nfsd4_encode_fattr4_supported_attrs,
 	[FATTR4_TYPE]			= nfsd4_encode_fattr4_type,
@@ -3487,6 +3536,7 @@ static const nfsd4_enc_attr nfsd4_enc_fattr4_encode_ops[] = {
 
 	[FATTR4_MODE_UMASK]		= nfsd4_encode_fattr4__noop,
 	[FATTR4_XATTR_SUPPORT]		= nfsd4_encode_fattr4_xattr_support,
+	[FATTR4_OPEN_ARGUMENTS]		= nfsd4_encode_fattr4_open_arguments,
 };
 
 /*
diff --git a/fs/nfsd/nfsd.h b/fs/nfsd/nfsd.h
index 4b56ba1e8e48d08c4e3e52f378822c311193c3d4..1955c8e9c4c793728fa75dd136cadc735245483f 100644
--- a/fs/nfsd/nfsd.h
+++ b/fs/nfsd/nfsd.h
@@ -458,7 +458,8 @@ enum {
 	(NFSD4_1_SUPPORTED_ATTRS_WORD2 | \
 	FATTR4_WORD2_MODE_UMASK | \
 	NFSD4_2_SECURITY_ATTRS | \
-	FATTR4_WORD2_XATTR_SUPPORT)
+	FATTR4_WORD2_XATTR_SUPPORT | \
+	FATTR4_WORD2_OPEN_ARGUMENTS)
 
 extern const u32 nfsd_suppattrs[3][3];
 

-- 
2.47.1