Add freebsd32 compat shim for nmount(2).

(and quiet some compiler warnings for vfs_donmount)

sys/compat/freebsd32/freebsd32_misc.c

@@ -85,6 +85,8 @@ __FBSDID("$FreeBSD$");
 
 #include <machine/cpu.h>
 
+#include <security/audit/audit.h>
+
 #include <compat/freebsd32/freebsd32_util.h>
 #include <compat/freebsd32/freebsd32.h>
 #include <compat/freebsd32/freebsd32_ipc.h>
@@ -2552,8 +2554,51 @@ freebsd32_cpuset_setaffinity(struct thread *td,
 	return (cpuset_setaffinity(td, &ap));
 }
 
-#if 0
+int
+freebsd32_nmount(struct thread *td,
+    struct freebsd32_nmount_args /* {
+    	struct iovec *iovp;
+    	unsigned int iovcnt;
+    	int flags;
+    } */ *uap)
+{
+	struct uio *auio;
+	struct iovec *iov;
+	int error, k;
 
+	AUDIT_ARG(fflags, uap->flags);
+
+	/*
+	 * Filter out MNT_ROOTFS.  We do not want clients of nmount() in
+	 * userspace to set this flag, but we must filter it out if we want
+	 * MNT_UPDATE on the root file system to work.
+	 * MNT_ROOTFS should only be set in the kernel in vfs_mountroot_try().
+	 */
+	uap->flags &= ~MNT_ROOTFS;
+
+	/*
+	 * check that we have an even number of iovec's
+	 * and that we have at least two options.
+	 */
+	if ((uap->iovcnt & 1) || (uap->iovcnt < 4))
+		return (EINVAL);
+
+	error = freebsd32_copyinuio(uap->iovp, uap->iovcnt, &auio);
+	if (error)
+		return (error);
+	for (iov = auio->uio_iov, k = 0; k < uap->iovcnt; ++k, ++iov) {
+		if (iov->iov_len > MMAXOPTIONLEN) {
+			free(auio, M_IOV);
+			return (EINVAL);
+		}
+	}
+
+	error = vfs_donmount(td, uap->flags, auio);
+	free(auio, M_IOV);
+	return error;
+}
+
+#if 0
 int
 freebsd32_xxx(struct thread *td, struct freebsd32_xxx_args *uap)
 {
@@ -2578,5 +2623,4 @@ freebsd32_xxx(struct thread *td, struct freebsd32_xxx_args *uap)
 	}
 	return (error);
 }
-
 #endif

sys/compat/freebsd32/syscalls.master

@@ -651,7 +651,7 @@
 375	AUE_NULL	UNIMPL	nfsclnt
 376	AUE_EACCESS	NOPROTO	{ int eaccess(char *path, int flags); }
 377	AUE_NULL	UNIMPL	afs_syscall
-378	AUE_NMOUNT	NOPROTO	{ int nmount(struct iovec *iovp, \
+378	AUE_NMOUNT	STD	{ int freebsd32_nmount(struct iovec32 *iovp, \
 				    unsigned int iovcnt, int flags); }
 379	AUE_NULL	UNIMPL	kse_exit
 380	AUE_NULL	UNIMPL	kse_wakeup

sys/kern/vfs_mount.c

@@ -77,8 +77,6 @@ static int	vfs_domount(struct thread *td, const char *fstype,
 		    char *fspath, int fsflags, void *fsdata);
 static int	vfs_mountroot_ask(void);
 static int	vfs_mountroot_try(const char *mountfrom);
-static int	vfs_donmount(struct thread *td, int fsflags,
-		    struct uio *fsoptions);
 static void	free_mntarg(struct mntarg *ma);
 static int	vfs_getopt_pos(struct vfsoptlist *opts, const char *name);
 
@@ -583,7 +581,7 @@ vfs_mount_destroy(struct mount *mp)
 	uma_zfree(mount_zone, mp);
 }
 
-static int
+int
 vfs_donmount(struct thread *td, int fsflags, struct uio *fsoptions)
 {
 	struct vfsoptlist *optlist;
@@ -592,11 +590,9 @@ vfs_donmount(struct thread *td, int fsflags, struct uio *fsoptions)
 	int error, fstypelen, fspathlen, errmsg_len, errmsg_pos;
 	int has_rw, has_noro;
 
-	errmsg = NULL;
+	errmsg = fspath = NULL;
-	errmsg_len = 0;
+	errmsg_len = has_noro = has_rw = fspathlen = 0;
 	errmsg_pos = -1;
-	has_rw = 0;
-	has_noro = 0;
 
 	error = vfs_buildopts(fsoptions, &optlist);
 	if (error)

sys/sys/mount.h

@@ -690,6 +690,7 @@ int	vfs_busy(struct mount *, int, struct mtx *);
 int	vfs_export			 /* process mount export info */
 	    (struct mount *, struct export_args *);
 int	vfs_allocate_syncvnode(struct mount *);
+int	vfs_donmount(struct thread *td, int fsflags, struct uio *fsoptions);
 void	vfs_getnewfsid(struct mount *);
 struct cdev *vfs_getrootfsid(struct mount *);
 struct	mount *vfs_getvfs(fsid_t *);      /* return vfs given fsid */