[PATCH v2 02/42] lockd: Introduce nlm__int__deadlock

[Chuck Lever <cel@kernel.org>]

From: Chuck Lever <chuck.lever@oracle.com>

The use of CONFIG_LOCKD_V4 in combination with a later cast_status()
in the NLMv3 code is difficult to reason about. Instead, replace the
use of nlm_deadlock with an implementation-defined status value that
version-specific code translates appropriately.

The new approach establishes a translation boundary: generic lockd
code returns nlm__int__deadlock when posix_lock_file() yields
-EDEADLK. Version-specific handlers (svc4proc.c for NLMv4,
svcproc.c for NLMv3) translate this internal status to the
appropriate wire protocol value. NLMv4 maps to nlm4_deadlock;
NLMv3 maps to nlm_lck_denied (since NLMv3 lacks a deadlock-specific
status code).

Later this modification will also remove the need to include NLMv4
headers in NLMv3 and generic code.

Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
---
 fs/lockd/svc4proc.c         | 10 ++++++++--
 fs/lockd/svclock.c          |  8 +-------
 fs/lockd/svcproc.c          |  4 +++-
 include/linux/lockd/lockd.h |  7 +++++++
 include/linux/lockd/xdr.h   |  2 --
 5 files changed, 19 insertions(+), 12 deletions(-)

diff --git a/fs/lockd/svc4proc.c b/fs/lockd/svc4proc.c
index 4b6f18d97734..061686b36b38 100644
--- a/fs/lockd/svc4proc.c
+++ b/fs/lockd/svc4proc.c
@@ -146,10 +146,16 @@ __nlm4svc_proc_lock(struct svc_rqst *rqstp, struct nlm_res *resp)
 	resp->status = nlmsvc_lock(rqstp, file, host, &argp->lock,
 					argp->block, &argp->cookie,
 					argp->reclaim);
-	if (resp->status == nlm_drop_reply)
+	switch (resp->status) {
+	case nlm_drop_reply:
 		rc = rpc_drop_reply;
-	else
+		break;
+	case nlm__int__deadlock:
+		resp->status = nlm4_deadlock;
+		fallthrough;
+	default:
 		dprintk("lockd: LOCK         status %d\n", ntohl(resp->status));
+	}
 
 	nlmsvc_release_lockowner(&argp->lock);
 	nlmsvc_release_host(host);
diff --git a/fs/lockd/svclock.c b/fs/lockd/svclock.c
index 712df1e025d8..e80e3b4ee689 100644
--- a/fs/lockd/svclock.c
+++ b/fs/lockd/svclock.c
@@ -33,12 +33,6 @@
 
 #define NLMDBG_FACILITY		NLMDBG_SVCLOCK
 
-#ifdef CONFIG_LOCKD_V4
-#define nlm_deadlock	nlm4_deadlock
-#else
-#define nlm_deadlock	nlm_lck_denied
-#endif
-
 static void nlmsvc_release_block(struct nlm_block *block);
 static void	nlmsvc_insert_block(struct nlm_block *block, unsigned long);
 static void	nlmsvc_remove_block(struct nlm_block *block);
@@ -589,7 +583,7 @@ nlmsvc_lock(struct svc_rqst *rqstp, struct nlm_file *file,
 			goto out;
 		case -EDEADLK:
 			nlmsvc_remove_block(block);
-			ret = nlm_deadlock;
+			ret = nlm__int__deadlock;
 			goto out;
 		default:			/* includes ENOLCK */
 			nlmsvc_remove_block(block);
diff --git a/fs/lockd/svcproc.c b/fs/lockd/svcproc.c
index 95c6bf7ab757..3e890534c3dc 100644
--- a/fs/lockd/svcproc.c
+++ b/fs/lockd/svcproc.c
@@ -27,7 +27,7 @@ static inline __be32 cast_status(__be32 status)
 	case nlm_lck_denied_grace_period:
 	case nlm_drop_reply:
 		break;
-	case nlm4_deadlock:
+	case nlm__int__deadlock:
 		status = nlm_lck_denied;
 		break;
 	default:
@@ -39,6 +39,8 @@ static inline __be32 cast_status(__be32 status)
 #else
 static inline __be32 cast_status(__be32 status)
 {
+	if (status == nlm__int__deadlock)
+		status = nlm_lck_denied;
 	return status;
 }
 #endif
diff --git a/include/linux/lockd/lockd.h b/include/linux/lockd/lockd.h
index 330e38776bb2..36a744f212ca 100644
--- a/include/linux/lockd/lockd.h
+++ b/include/linux/lockd/lockd.h
@@ -38,6 +38,13 @@
  */
 #define LOCKD_DFLT_TIMEO	10
 
+/*
+ * Internal-use status codes, not to be placed on the wire.
+ * Version handlers translate these to appropriate wire values.
+ */
+#define nlm_drop_reply		cpu_to_be32(30000)
+#define nlm__int__deadlock	cpu_to_be32(30001)
+
 /*
  * Lockd host handle (used both by the client and server personality).
  */
diff --git a/include/linux/lockd/xdr.h b/include/linux/lockd/xdr.h
index 17d53165d9f2..292e4e38d17d 100644
--- a/include/linux/lockd/xdr.h
+++ b/include/linux/lockd/xdr.h
@@ -33,8 +33,6 @@ struct svc_rqst;
 #define	nlm_lck_blocked		cpu_to_be32(NLM_LCK_BLOCKED)
 #define	nlm_lck_denied_grace_period	cpu_to_be32(NLM_LCK_DENIED_GRACE_PERIOD)
 
-#define nlm_drop_reply		cpu_to_be32(30000)
-
 /* Lock info passed via NLM */
 struct nlm_lock {
 	char *			caller;
-- 
2.52.0