[PATCH 2/3] nfsd: be more systematic about selecting error codes for internal use.

[NeilBrown <neilb@suse.de>]

Rather than using ad hoc values for internal errors (30000, 11000, ...)
use 'enum' to sequentially allocated numbers starting from the first
known available number - now visible as NFS4ERR_FIRST_FREE.

The goal is values that are distinct from all be32 error codes.  To get
those we must first select integers that are not already used, then
convert them with cpu_to_be32().

Signed-off-by: NeilBrown <neilb@suse.de>
---
 fs/nfsd/nfsd.h       | 23 ++++++++++++++++++-----
 include/linux/nfs4.h | 17 ++++++++++-------
 2 files changed, 28 insertions(+), 12 deletions(-)

diff --git a/fs/nfsd/nfsd.h b/fs/nfsd/nfsd.h
index 8f4f239d9f8a..593c34fd325a 100644
--- a/fs/nfsd/nfsd.h
+++ b/fs/nfsd/nfsd.h
@@ -326,17 +326,30 @@ void		nfsd_lockd_shutdown(void);
 #define nfserr_xattr2big		cpu_to_be32(NFS4ERR_XATTR2BIG)
 #define nfserr_noxattr			cpu_to_be32(NFS4ERR_NOXATTR)
 
-/* error codes for internal use */
+/* Error codes for internal use.  We use enum to choose numbers that are
+ * not already assigned, then covert to be32 resulting in a number that
+ * cannot conflict with any existing be32 nfserr value.
+ */
+enum {
+	NFSERR_DROPIT = NFS4ERR_FIRST_FREE,
 /* if a request fails due to kmalloc failure, it gets dropped.
  *  Client should resend eventually
  */
-#define	nfserr_dropit		cpu_to_be32(30000)
+#define	nfserr_dropit		cpu_to_be32(NFSERR_DROPIT)
+
 /* end-of-file indicator in readdir */
-#define	nfserr_eof		cpu_to_be32(30001)
+	NFSERR_EOF,
+#define	nfserr_eof		cpu_to_be32(NFSERR_EOF)
+
 /* replay detected */
-#define	nfserr_replay_me	cpu_to_be32(11001)
+	NFSERR_REPLAY_ME,
+#define	nfserr_replay_me	cpu_to_be32(NFSERR_REPLAY_ME)
+
 /* nfs41 replay detected */
-#define	nfserr_replay_cache	cpu_to_be32(11002)
+	NFSERR_REPLAY_CACHE,
+#define	nfserr_replay_cache	cpu_to_be32(NFSERR_REPLAY_CACHE)
+
+};
 
 /* Check for dir entries '.' and '..' */
 #define isdotent(n, l)	(l < 3 && n[0] == '.' && (l == 1 || n[1] == '.'))
diff --git a/include/linux/nfs4.h b/include/linux/nfs4.h
index 0d896ce296ce..1ad794f81747 100644
--- a/include/linux/nfs4.h
+++ b/include/linux/nfs4.h
@@ -281,15 +281,18 @@ enum nfsstat4 {
 	/* nfs42 */
 	NFS4ERR_PARTNER_NOTSUPP	= 10088,
 	NFS4ERR_PARTNER_NO_AUTH	= 10089,
-	NFS4ERR_UNION_NOTSUPP = 10090,
-	NFS4ERR_OFFLOAD_DENIED = 10091,
-	NFS4ERR_WRONG_LFS = 10092,
-	NFS4ERR_BADLABEL = 10093,
-	NFS4ERR_OFFLOAD_NO_REQS = 10094,
+	NFS4ERR_UNION_NOTSUPP	= 10090,
+	NFS4ERR_OFFLOAD_DENIED	= 10091,
+	NFS4ERR_WRONG_LFS	= 10092,
+	NFS4ERR_BADLABEL	= 10093,
+	NFS4ERR_OFFLOAD_NO_REQS	= 10094,
 
 	/* xattr (RFC8276) */
-	NFS4ERR_NOXATTR        = 10095,
-	NFS4ERR_XATTR2BIG      = 10096,
+	NFS4ERR_NOXATTR		= 10095,
+	NFS4ERR_XATTR2BIG	= 10096,
+
+	/* can be used for internal errors */
+	NFS4ERR_FIRST_FREE
 };
 
 /* error codes for internal client use */
-- 
2.44.0