swapoff: add one more variant of the syscall

Requested and reviewed by:	brooks
Sponsored by:	The FreeBSD Foundation
MFC after:	1 week
Differential revision:	https://reviews.freebsd.org/D33343

include/unistd.h

@@ -579,7 +579,7 @@ int	 setruid(uid_t);
 void	 setusershell(void);
 int	 strtofflags(char **, u_long *, u_long *);
 int	 swapon(const char *);
-int	 swapoff(const char *);
+int	 swapoff(const char *, u_int);
 int	 syscall(int, ...);
 off_t	 __syscall(quad_t, ...);
 int	 undelete(const char *);

lib/libc/include/compat.h

@@ -69,6 +69,8 @@ __sym_compat(mknodat, freebsd11_mknodat, FBSD_1.1);
 
 __sym_compat(kevent, freebsd11_kevent, FBSD_1.0);
 
+__sym_compat(swapoff, freebsd13_swapoff, FBSD_1.0);
+
 #undef __sym_compat
 
 #define	__weak_reference(sym,alias)	\

lib/libc/sys/Symbol.map

@@ -260,7 +260,6 @@ FBSD_1.0 {
 	sigwaitinfo;
 	socket;
 	socketpair;
-	swapoff;
 	swapon;
 	symlink;
 	sync;
@@ -420,6 +419,7 @@ FBSD_1.6 {
 FBSD_1.7 {
 	_Fork;
 	fspacectl;
+	swapoff;
 };
 
 FBSDprivate_1.0 {

sys/kern/syscalls.master

@@ -2247,7 +2247,7 @@
 		    _In_ _Contains_long_ptr_ const struct __ucontext *ucp
 		);
 	}
-424	AUE_SWAPOFF	STD {
+424	AUE_SWAPOFF	COMPAT13 {
 		int swapoff(
 		    _In_z_ const char *name
 		);
@@ -3300,6 +3300,13 @@
 		int sched_getcpu(void);
 	}
 
+582	AUE_SWAPOFF	STD {
+		int swapoff(
+		    _In_z_ const char *name,
+		    u_int flags,
+		);
+	}
+
 ; Please copy any additions and changes to the following compatability tables:
 ; sys/compat/freebsd32/syscalls.master
 ; vim: syntax=off

sys/sys/unistd.h

@@ -198,6 +198,8 @@
     RFPROCDESC | RFSPAWN | RFPPWAIT)
 #define	RFKERNELONLY	(RFSTOPPED | RFHIGHPID | RFPROCDESC)
 
+#define	SWAPOFF_FORCE	0x00000001
+
 #endif /* __BSD_VISIBLE */
 
 #endif /* !_SYS_UNISTD_H_ */

sys/vm/swap_pager.c

@@ -100,6 +100,7 @@ __FBSDID("$FreeBSD$");
 #include <sys/sysproto.h>
 #include <sys/systm.h>
 #include <sys/sx.h>
+#include <sys/unistd.h>
 #include <sys/user.h>
 #include <sys/vmmeter.h>
 #include <sys/vnode.h>
@@ -2479,50 +2480,24 @@ swaponsomething(struct vnode *vp, void *id, u_long nblks,
  * rather than filename as specification.  We keep sw_vp around
  * only to make this work.
  */
-#ifndef _SYS_SYSPROTO_H_
-struct swapoff_args {
-	char *name;
-};
-#endif
-
-int
-sys_swapoff(struct thread *td, struct swapoff_args *uap)
+static int
+kern_swapoff(struct thread *td, const char *name, enum uio_seg name_seg,
+    u_int flags)
 {
 	struct vnode *vp;
 	struct nameidata nd;
 	struct swdevt *sp;
-	struct swapoff_new_args sa;
-	int error, probe_byte;
+	int error;
 
 	error = priv_check(td, PRIV_SWAPOFF);
-	if (error)
+	if (error != 0)
 		return (error);
-
-	/*
-	 * Detect old vs. new-style swapoff(2) syscall.  The first
-	 * pointer in the memory pointed to by uap->name is NULL for
-	 * the new variant.
-	 */
-	probe_byte = fubyte(uap->name);
-	switch (probe_byte) {
-	case -1:
-		return (EFAULT);
-	case 0:
-		error = copyin(uap->name, &sa, sizeof(sa));
-		if (error != 0)
-			return (error);
-		if ((sa.flags & ~(SWAPOFF_FORCE)) != 0)
-			return (EINVAL);
-		break;
-	default:
-		bzero(&sa, sizeof(sa));
-		sa.name = uap->name;
-		break;
-	}
+	if ((flags & ~(SWAPOFF_FORCE)) != 0)
+		return (EINVAL);
 
 	sx_xlock(&swdev_syscall_lock);
 
-	NDINIT(&nd, LOOKUP, FOLLOW | AUDITVNODE1, UIO_USERSPACE, sa.name);
+	NDINIT(&nd, LOOKUP, FOLLOW | AUDITVNODE1, name_seg, name);
 	error = namei(&nd);
 	if (error)
 		goto done;
@@ -2539,12 +2514,27 @@ sys_swapoff(struct thread *td, struct swapoff_args *uap)
 		error = EINVAL;
 		goto done;
 	}
-	error = swapoff_one(sp, td->td_ucred, sa.flags);
+	error = swapoff_one(sp, td->td_ucred, flags);
 done:
 	sx_xunlock(&swdev_syscall_lock);
 	return (error);
 }
 
+
+#ifdef COMPAT_FREEBSD13
+int
+freebsd13_swapoff(struct thread *td, struct freebsd13_swapoff_args *uap)
+{
+	return (kern_swapoff(td, uap->name, UIO_USERSPACE, 0));
+}
+#endif
+
+int
+sys_swapoff(struct thread *td, struct swapoff_args *uap)
+{
+	return (kern_swapoff(td, uap->name, UIO_USERSPACE, uap->flags));
+}
+
 static int
 swapoff_one(struct swdevt *sp, struct ucred *cred, u_int flags)
 {

sys/vm/swap_pager.h

@@ -69,16 +69,6 @@ struct swdevt {
 #define	SW_UNMAPPED	0x01
 #define	SW_CLOSING	0x04
 
-struct swapoff_new_args {
-	const char *name_old_syscall;
-	const char *name;
-	u_int flags;
-	u_int pad0;
-	uintptr_t pad1[8];
-};
-
-#define	SWAPOFF_FORCE	0x00000001
-
 #ifdef _KERNEL
 
 extern int swap_pager_avail;