sys_fstat() is implemented as a wrapper around `fo_stat'.  All
implementations are ready to be called without KERNEL_LOCK() except
for vn_statfile() below.

This was part of my previous VFS unlock diff.

ok?

Index: kern/syscalls.master
===================================================================
RCS file: /cvs/src/sys/kern/syscalls.master,v
diff -u -p -r1.265 syscalls.master
--- kern/syscalls.master	2 Aug 2024 14:34:45 -0000	1.265
+++ kern/syscalls.master	5 Jan 2025 10:02:35 -0000
@@ -133,7 +133,7 @@
 51	UNIMPL		acct
 #endif
 52	STD		{ int sys_sigpending(void); }
-53	STD		{ int sys_fstat(int fd, struct stat *sb); }
+53	STD NOLOCK	{ int sys_fstat(int fd, struct stat *sb); }
 54	STD NOLOCK	{ int sys_ioctl(int fd, \
 			    u_long com, ... void *data); }
 55	STD		{ int sys_reboot(int opt); }
Index: kern/vfs_vnops.c
===================================================================
RCS file: /cvs/src/sys/kern/vfs_vnops.c,v
diff -u -p -r1.124 vfs_vnops.c
--- kern/vfs_vnops.c	30 Dec 2024 02:46:00 -0000	1.124
+++ kern/vfs_vnops.c	5 Jan 2025 10:03:02 -0000
@@ -427,7 +427,13 @@ int
 vn_statfile(struct file *fp, struct stat *sb, struct proc *p)
 {
 	struct vnode *vp = fp->f_data;
-	return vn_stat(vp, sb, p);
+	int error;
+
+	KERNEL_LOCK();
+	error = vn_stat(vp, sb, p);
+	KERNEL_UNLOCK();
+
+	return (error);
 }
 
 /*