Index: lib/libc/sys/getfsstat.2
===================================================================
--- lib/libc/sys/getfsstat.2
+++ lib/libc/sys/getfsstat.2
@@ -41,7 +41,7 @@
 .In sys/ucred.h
 .In sys/mount.h
 .Ft int
-.Fn getfsstat "struct statfs *buf" "long bufsize" "int flags"
+.Fn getfsstat "struct statfs *buf" "long bufsize" "int flag"
 .Sh DESCRIPTION
 The
 .Fn getfsstat
@@ -74,11 +74,11 @@
 returns just the number of mounted file systems.
 .Pp
 Normally
-.Fa flags
+.Fa flag
 should be specified as
 .Dv MNT_WAIT .
 If
-.Fa flags
+.Fa flag
 is set to
 .Dv MNT_NOWAIT ,
 .Fn getfsstat
@@ -108,6 +108,12 @@
 .Fa buf
 argument
 points to an invalid address.
+.It Bq Er EINVAL
+.Fa flag
+is set to a value other than
+.Dv MNT_WAIT
+or
+.Dv MNT_NOWAIT .
 .It Bq Er EIO
 An
 .Tn I/O
Index: sys/compat/freebsd32/freebsd32_misc.c
===================================================================
--- sys/compat/freebsd32/freebsd32_misc.c
+++ sys/compat/freebsd32/freebsd32_misc.c
@@ -253,7 +253,7 @@
 
 	count = uap->bufsize / sizeof(struct statfs32);
 	size = count * sizeof(struct statfs);
-	error = kern_getfsstat(td, &buf, size, &count, UIO_SYSSPACE, uap->flags);
+	error = kern_getfsstat(td, &buf, size, &count, UIO_SYSSPACE, uap->flag);
 	if (size > 0) {
 		sp = buf;
 		copycount = count;
Index: sys/compat/freebsd32/freebsd32_proto.h
===================================================================
--- sys/compat/freebsd32/freebsd32_proto.h
+++ sys/compat/freebsd32/freebsd32_proto.h
@@ -917,7 +917,7 @@
 struct freebsd4_freebsd32_getfsstat_args {
 	char buf_l_[PADL_(struct statfs32 *)]; struct statfs32 * buf; char buf_r_[PADR_(struct statfs32 *)];
 	char bufsize_l_[PADL_(long)]; long bufsize; char bufsize_r_[PADR_(long)];
-	char flags_l_[PADL_(int)]; int flags; char flags_r_[PADR_(int)];
+	char flag_l_[PADL_(int)]; int flag; char flag_r_[PADR_(int)];
 };
 struct freebsd4_freebsd32_statfs_args {
 	char path_l_[PADL_(char *)]; char * path; char path_r_[PADR_(char *)];
Index: sys/compat/freebsd32/freebsd32_systrace_args.c
===================================================================
--- sys/compat/freebsd32/freebsd32_systrace_args.c
+++ sys/compat/freebsd32/freebsd32_systrace_args.c
@@ -1960,7 +1960,7 @@
 		struct getfsstat_args *p = params;
 		uarg[0] = (intptr_t) p->buf; /* struct statfs * */
 		iarg[1] = p->bufsize; /* long */
-		iarg[2] = p->flags; /* int */
+		iarg[2] = p->flag; /* int */
 		*n_args = 3;
 		break;
 	}
Index: sys/compat/freebsd32/syscalls.master
===================================================================
--- sys/compat/freebsd32/syscalls.master
+++ sys/compat/freebsd32/syscalls.master
@@ -89,7 +89,7 @@
 				    obreak_args int
 18	AUE_GETFSSTAT	COMPAT4	{ int freebsd32_getfsstat( \
 				    struct statfs32 *buf, long bufsize, \
-				    int flags); }
+				    int flag); }
 19	AUE_LSEEK	COMPAT	{ int freebsd32_lseek(int fd, int offset, \
 				    int whence); }
 20	AUE_GETPID	NOPROTO	{ pid_t getpid(void); }
@@ -711,7 +711,7 @@
 				    off_t *sbytes, int flags); }
 394	AUE_NULL	UNIMPL	mac_syscall
 395	AUE_GETFSSTAT	NOPROTO	{ int getfsstat(struct statfs *buf, \
-				    long bufsize, int flags); }
+				    long bufsize, int flag); }
 396	AUE_STATFS	NOPROTO	{ int statfs(char *path, \
 				    struct statfs *buf); }
 397	AUE_FSTATFS	NOPROTO	{ int fstatfs(int fd, struct statfs *buf); }
Index: sys/kern/syscalls.master
===================================================================
--- sys/kern/syscalls.master
+++ sys/kern/syscalls.master
@@ -85,7 +85,7 @@
 17	AUE_NULL	STD	{ int obreak(char *nsize); } break \
 				    obreak_args int
 18	AUE_GETFSSTAT	COMPAT4	{ int getfsstat(struct ostatfs *buf, \
-				    long bufsize, int flags); }
+				    long bufsize, int flag); }
 19	AUE_LSEEK	COMPAT	{ long lseek(int fd, long offset, \
 				    int whence); }
 20	AUE_GETPID	STD	{ pid_t getpid(void); }
@@ -706,7 +706,7 @@
 394	AUE_NULL	STD	{ int mac_syscall(const char *policy, \
 				    int call, void *arg); }
 395	AUE_GETFSSTAT	STD	{ int getfsstat(struct statfs *buf, \
-				    long bufsize, int flags); }
+				    long bufsize, int flag); }
 396	AUE_STATFS	STD	{ int statfs(char *path, \
 				    struct statfs *buf); }
 397	AUE_FSTATFS	STD	{ int fstatfs(int fd, struct statfs *buf); }
Index: sys/kern/systrace_args.c
===================================================================
--- sys/kern/systrace_args.c
+++ sys/kern/systrace_args.c
@@ -2072,7 +2072,7 @@
 		struct getfsstat_args *p = params;
 		uarg[0] = (intptr_t) p->buf; /* struct statfs * */
 		iarg[1] = p->bufsize; /* long */
-		iarg[2] = p->flags; /* int */
+		iarg[2] = p->flag; /* int */
 		*n_args = 3;
 		break;
 	}
Index: sys/kern/vfs_syscalls.c
===================================================================
--- sys/kern/vfs_syscalls.c
+++ sys/kern/vfs_syscalls.c
@@ -412,7 +412,7 @@
 struct getfsstat_args {
 	struct statfs *buf;
 	long bufsize;
-	int flags;
+	int flag;
 };
 #endif
 int
@@ -421,7 +421,7 @@
 	register struct getfsstat_args /* {
 		struct statfs *buf;
 		long bufsize;
-		int flags;
+		int flag;
 	} */ *uap;
 {
 	size_t count;
@@ -430,7 +430,7 @@
 	if (uap->bufsize < 0 || uap->bufsize > SIZE_MAX)
 		return (EINVAL);
 	error = kern_getfsstat(td, &uap->buf, uap->bufsize, &count,
-	    UIO_USERSPACE, uap->flags);
+	    UIO_USERSPACE, uap->flag);
 	if (error == 0)
 		td->td_retval[0] = count;
 	return (error);
@@ -443,13 +443,20 @@
  */
 int
 kern_getfsstat(struct thread *td, struct statfs **buf, size_t bufsize,
-    size_t *countp, enum uio_seg bufseg, int flags)
+    size_t *countp, enum uio_seg bufseg, int flag)
 {
 	struct mount *mp, *nmp;
 	struct statfs *sfsp, *sp, sb, *tofree;
 	size_t count, maxcount;
 	int error;
 
+	switch (flag) {
+	case MNT_WAIT:
+	case MNT_NOWAIT:
+		break;
+	default:
+		return (EINVAL);
+	}
 restart:
 	maxcount = bufsize / sizeof(struct statfs);
 	if (bufsize == 0) {
@@ -483,7 +490,7 @@
 			continue;
 		}
 #endif
-		if (flags == MNT_WAIT) {
+		if (flag == MNT_WAIT) {
 			if (vfs_busy(mp, MBF_MNTLSTLOCK) != 0) {
 				/*
 				 * If vfs_busy() failed, and MBF_NOWAIT
@@ -515,7 +522,7 @@
 			 * If MNT_NOWAIT or MNT_LAZY is specified, do not
 			 * refresh the fsstat cache.
 			 */
-			if (flags != MNT_LAZY && flags != MNT_NOWAIT) {
+			if (flag != MNT_LAZY && flag != MNT_NOWAIT) {
 				error = VFS_STATFS(mp, sp);
 				if (error != 0) {
 					mtx_lock(&mountlist_mtx);
@@ -620,7 +627,7 @@
 struct freebsd4_getfsstat_args {
 	struct ostatfs *buf;
 	long bufsize;
-	int flags;
+	int flag;
 };
 #endif
 int
@@ -629,7 +636,7 @@
 	register struct freebsd4_getfsstat_args /* {
 		struct ostatfs *buf;
 		long bufsize;
-		int flags;
+		int flag;
 	} */ *uap;
 {
 	struct statfs *buf, *sp;
@@ -644,7 +651,7 @@
 		return (EINVAL);
 	size = count * sizeof(struct statfs);
 	error = kern_getfsstat(td, &buf, size, &count, UIO_SYSSPACE,
-	    uap->flags);
+	    uap->flag);
 	td->td_retval[0] = count;
 	if (size != 0) {
 		sp = buf;
Index: sys/sys/syscallsubr.h
===================================================================
--- sys/sys/syscallsubr.h
+++ sys/sys/syscallsubr.h
@@ -109,7 +109,7 @@
 int	kern_getdirentries(struct thread *td, int fd, char *buf, u_int count,
 	    long *basep, ssize_t *residp, enum uio_seg bufseg);
 int	kern_getfsstat(struct thread *td, struct statfs **buf, size_t bufsize,
-	    size_t *countp, enum uio_seg bufseg, int flags);
+	    size_t *countp, enum uio_seg bufseg, int flag);
 int	kern_getitimer(struct thread *, u_int, struct itimerval *);
 int	kern_getppid(struct thread *);
 int	kern_getpeername(struct thread *td, int fd, struct sockaddr **sa,
Index: sys/sys/sysproto.h
===================================================================
--- sys/sys/sysproto.h
+++ sys/sys/sysproto.h
@@ -1102,7 +1102,7 @@
 struct getfsstat_args {
 	char buf_l_[PADL_(struct statfs *)]; struct statfs * buf; char buf_r_[PADR_(struct statfs *)];
 	char bufsize_l_[PADL_(long)]; long bufsize; char bufsize_r_[PADR_(long)];
-	char flags_l_[PADL_(int)]; int flags; char flags_r_[PADR_(int)];
+	char flag_l_[PADL_(int)]; int flag; char flag_r_[PADR_(int)];
 };
 struct statfs_args {
 	char path_l_[PADL_(char *)]; char * path; char path_r_[PADR_(char *)];
@@ -2350,7 +2350,7 @@
 struct freebsd4_getfsstat_args {
 	char buf_l_[PADL_(struct ostatfs *)]; struct ostatfs * buf; char buf_r_[PADR_(struct ostatfs *)];
 	char bufsize_l_[PADL_(long)]; long bufsize; char bufsize_r_[PADR_(long)];
-	char flags_l_[PADL_(int)]; int flags; char flags_r_[PADR_(int)];
+	char flag_l_[PADL_(int)]; int flag; char flag_r_[PADR_(int)];
 };
 struct freebsd4_statfs_args {
 	char path_l_[PADL_(char *)]; char * path; char path_r_[PADR_(char *)];