[PATCH] PATCH 6/7: knfsd cleanups - syscall cleanup

Cleanup the syscall interface to nfsd

1/ add an "owner" field to the nfsd_linkage structure
2/ grab a reference to that module before calling the syscall
3/ Remove the reference counting from inside the module
4/ Always allow nfsd module to be called, even if compile with
	CONFIG_NFSD == N
   ( but not if CONFIG_MODULES also == N)

fs/filesystems.c

@@ -3,7 +3,7 @@
  *
  *  Copyright (C) 1991, 1992  Linus Torvalds
  *
- *  table of configured filesystems
+ *  nfsservctl system-call when nfsd is not compiled in.
  */
 
 #include <linux/config.h>
@@ -14,28 +14,28 @@
 #include <linux/nfsd/interface.h>
 #include <linux/linkage.h>
 
-#if defined(CONFIG_NFSD_MODULE)
-struct nfsd_linkage *nfsd_linkage = NULL;
+#if ! defined(CONFIG_NFSD)
+struct nfsd_linkage *nfsd_linkage;
 
 long
 asmlinkage sys_nfsservctl(int cmd, void *argp, void *resp)
 {
 	int ret = -ENOSYS;
 	
+#if defined(CONFIG_MODULES)
 	lock_kernel();
 
 	if (nfsd_linkage ||
-	    (request_module ("nfsd") == 0 && nfsd_linkage))
+	    (request_module ("nfsd") == 0 && nfsd_linkage)) {
+		__MOD_INC_USE_COUNT(nfsd_linkage->owner);
+		unlock_kernel();
 		ret = nfsd_linkage->do_nfsservctl(cmd, argp, resp);
-
-	unlock_kernel();
+		__MOD_DEC_USE_COUNT(nfsd_linkage->owner);
+	} else
+		unlock_kernel();
+#endif
 	return ret;
 }
 EXPORT_SYMBOL(nfsd_linkage);
 
-#elif ! defined (CONFIG_NFSD)
-asmlinkage int sys_nfsservctl(int cmd, void *argp, void *resp)
-{
-	return -ENOSYS;
-}
 #endif /* CONFIG_NFSD */

fs/nfsd/nfsctl.c

@@ -203,7 +203,6 @@ asmlinkage handle_sys_nfsservctl(int cmd, void *opaque_argp, void *opaque_resp)
 	int			err;
 	int			argsize, respsize;
 
-	MOD_INC_USE_COUNT;
 	lock_kernel ();
 	if (!initialized)
 		nfsd_init();
@@ -276,7 +275,6 @@ asmlinkage handle_sys_nfsservctl(int cmd, void *opaque_argp, void *opaque_resp)
 		kfree(res);
 
 	unlock_kernel ();
-	MOD_DEC_USE_COUNT;
 	return err;
 }
 
@@ -288,6 +286,7 @@ MODULE_LICENSE("GPL");
 
 struct nfsd_linkage nfsd_linkage_s = {
 	do_nfsservctl: handle_sys_nfsservctl,
+	owner: THIS_MODULE,
 };
 
 /*

include/linux/nfsd/interface.h

@@ -16,6 +16,7 @@
 
 extern struct nfsd_linkage {
 	long (*do_nfsservctl)(int cmd, void *argp, void *resp);
+	struct module *owner;
 } * nfsd_linkage;
 
 #endif