nfs,nfsd: NFSv4.2 extended attribute protocol definitions

Add definitions for the new operations, errors and flags as defined
in RFC 8276 (File System Extended Attributes in NFSv4).
Signed-off-by: Frank van der Linden <fllinden@amazon.com>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>

include/linux/nfs4.h

@@ -150,6 +150,12 @@ enum nfs_opnum4 {
 	OP_WRITE_SAME = 70,
 	OP_CLONE = 71,
 
+	/* xattr support (RFC8726) */
+	OP_GETXATTR                = 72,
+	OP_SETXATTR                = 73,
+	OP_LISTXATTRS              = 74,
+	OP_REMOVEXATTR             = 75,
+
 	OP_ILLEGAL = 10044,
 };
 
@@ -280,6 +286,10 @@ enum nfsstat4 {
 	NFS4ERR_WRONG_LFS = 10092,
 	NFS4ERR_BADLABEL = 10093,
 	NFS4ERR_OFFLOAD_NO_REQS = 10094,
+
+	/* xattr (RFC8276) */
+	NFS4ERR_NOXATTR        = 10095,
+	NFS4ERR_XATTR2BIG      = 10096,
 };
 
 static inline bool seqid_mutating_err(u32 err)
@@ -452,6 +462,7 @@ enum change_attr_type4 {
 #define FATTR4_WORD2_CHANGE_ATTR_TYPE	(1UL << 15)
 #define FATTR4_WORD2_SECURITY_LABEL     (1UL << 16)
 #define FATTR4_WORD2_MODE_UMASK		(1UL << 17)
+#define FATTR4_WORD2_XATTR_SUPPORT	(1UL << 18)
 
 /* MDS threshold bitmap bits */
 #define THRESHOLD_RD                    (1UL << 0)
@@ -700,4 +711,13 @@ struct nl4_server {
 		struct nfs42_netaddr	nl4_addr; /* NL4_NETADDR */
 	} u;
 };
+
+/*
+ * Options for setxattr. These match the flags for setxattr(2).
+ */
+enum nfs4_setxattr_options {
+	SETXATTR4_EITHER	= 0,
+	SETXATTR4_CREATE	= 1,
+	SETXATTR4_REPLACE	= 2,
+};
 #endif

include/uapi/linux/nfs4.h

@@ -33,6 +33,9 @@
 #define NFS4_ACCESS_EXTEND      0x0008
 #define NFS4_ACCESS_DELETE      0x0010
 #define NFS4_ACCESS_EXECUTE     0x0020
+#define NFS4_ACCESS_XAREAD      0x0040
+#define NFS4_ACCESS_XAWRITE     0x0080
+#define NFS4_ACCESS_XALIST      0x0100
 
 #define NFS4_FH_PERSISTENT		0x0000
 #define NFS4_FH_NOEXPIRE_WITH_OPEN	0x0001