bcachefs: copy_(to|from)_user_errcode()

we've got some helpers that return errors sanely, move them to a more
common location for use in fs-ioctl.c
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>

fs/bcachefs/chardev.c

@@ -22,12 +22,6 @@
 #include <linux/slab.h>
 #include <linux/uaccess.h>
 
-__must_check
-static int copy_to_user_errcode(void __user *to, const void *from, unsigned long n)
-{
-	return copy_to_user(to, from, n) ? -EFAULT : 0;
-}
-
 /* returns with ref on ca->ref */
 static struct bch_dev *bch2_device_lookup(struct bch_fs *c, u64 dev,
 					  unsigned flags)

fs/bcachefs/util.h

@@ -848,4 +848,20 @@ static inline bool qstr_eq(const struct qstr l, const struct qstr r)
 void bch2_darray_str_exit(darray_str *);
 int bch2_split_devs(const char *, darray_str *);
 
+#ifdef __KERNEL__
+
+__must_check
+static inline int copy_to_user_errcode(void __user *to, const void *from, unsigned long n)
+{
+	return copy_to_user(to, from, n) ? -EFAULT : 0;
+}
+
+__must_check
+static inline int copy_from_user_errcode(void *to, const void __user *from, unsigned long n)
+{
+	return copy_from_user(to, from, n) ? -EFAULT : 0;
+}
+
+#endif
+
 #endif /* _BCACHEFS_UTIL_H */