FreeBSD: Fix format of vfs.zfs.arc_no_grow_shift

vfs.zfs.arc_no_grow_shift has an invalid type (15) and this causes
py-sysctl to format it as a bytearray when it should be an integer.

"U" is not a valid format, it should be "I" and the type should match
the variable type, int.  We can return EINVAL if the value is set below
zero.

Reviewed-by: Brian Behlendorf <[email protected]>
Signed-off-by: Ryan Moeller <[email protected]>
Closes #11318

Author: Ryan Moeller

module/os/freebsd/zfs/sysctl_os.c

@@ -229,24 +229,23 @@ SYSCTL_UQUAD(_vfs_zfs, OID_AUTO, l2c_only_size, CTLFLAG_RD,
 static int
 sysctl_vfs_zfs_arc_no_grow_shift(SYSCTL_HANDLER_ARGS)
 {
-	uint32_t val;
-	int err;
+	int err, val;
 
 	val = arc_no_grow_shift;
-	err = sysctl_handle_32(oidp, &val, 0, req);
+	err = sysctl_handle_int(oidp, &val, 0, req);
 	if (err != 0 || req->newptr == NULL)
 		return (err);
 
-        if (val >= arc_shrink_shift)
+        if (val < 0 || val >= arc_shrink_shift)
 		return (EINVAL);
 
 	arc_no_grow_shift = val;
 	return (0);
 }
 
 SYSCTL_PROC(_vfs_zfs, OID_AUTO, arc_no_grow_shift,
-    CTLTYPE_U32 | CTLFLAG_RWTUN | CTLFLAG_MPSAFE, 0, sizeof (uint32_t),
-    sysctl_vfs_zfs_arc_no_grow_shift, "U",
+    CTLTYPE_INT | CTLFLAG_RWTUN | CTLFLAG_MPSAFE, NULL, sizeof (int),
+    sysctl_vfs_zfs_arc_no_grow_shift, "I",
     "log2(fraction of ARC which must be free to allow growing)");
 
 int