bcachefs: Convert bch2_pd_controller_print_debug() to a printbuf

Fewer random on-stack char arrays.
Signed-off-by: Kent Overstreet <kent.overstreet@gmail.com>

fs/bcachefs/util.c

@@ -484,36 +484,44 @@ void bch2_pd_controller_init(struct bch_pd_controller *pd)
 	pd->backpressure	= 1;
 }
 
-size_t bch2_pd_controller_print_debug(struct bch_pd_controller *pd, char *buf)
-{
-	/* 2^64 - 1 is 20 digits, plus null byte */
-	char rate[21];
-	char actual[21];
-	char target[21];
-	char proportional[21];
-	char derivative[21];
-	char change[21];
-	s64 next_io;
-
-	bch2_hprint(&PBUF(rate),	pd->rate.rate);
-	bch2_hprint(&PBUF(actual),	pd->last_actual);
-	bch2_hprint(&PBUF(target),	pd->last_target);
-	bch2_hprint(&PBUF(proportional), pd->last_proportional);
-	bch2_hprint(&PBUF(derivative),	pd->last_derivative);
-	bch2_hprint(&PBUF(change),	pd->last_change);
-
-	next_io = div64_s64(pd->rate.next - local_clock(), NSEC_PER_MSEC);
-
-	return sprintf(buf,
-		       "rate:\t\t%s/sec\n"
-		       "target:\t\t%s\n"
-		       "actual:\t\t%s\n"
-		       "proportional:\t%s\n"
-		       "derivative:\t%s\n"
-		       "change:\t\t%s/sec\n"
-		       "next io:\t%llims\n",
-		       rate, target, actual, proportional,
-		       derivative, change, next_io);
+void bch2_pd_controller_debug_to_text(struct printbuf *out, struct bch_pd_controller *pd)
+{
+	out->tabstops[0] = 20;
+
+	pr_buf(out, "rate:");
+	pr_tab(out);
+	bch2_hprint(out, pd->rate.rate);
+	pr_newline(out);
+
+	pr_buf(out, "target:");
+	pr_tab(out);
+	bch2_hprint(out, pd->last_target);
+	pr_newline(out);
+
+	pr_buf(out, "actual:");
+	pr_tab(out);
+	bch2_hprint(out, pd->last_actual);
+	pr_newline(out);
+
+	pr_buf(out, "proportional:");
+	pr_tab(out);
+	bch2_hprint(out, pd->last_proportional);
+	pr_newline(out);
+
+	pr_buf(out, "derivative:");
+	pr_tab(out);
+	bch2_hprint(out, pd->last_derivative);
+	pr_newline(out);
+
+	pr_buf(out, "change:");
+	pr_tab(out);
+	bch2_hprint(out, pd->last_change);
+	pr_newline(out);
+
+	pr_buf(out, "next io:");
+	pr_tab(out);
+	pr_buf(out, "%llims", div64_s64(pd->rate.next - local_clock(), NSEC_PER_MSEC));
+	pr_newline(out);
 }
 
 /* misc: */

fs/bcachefs/util.h

@@ -582,7 +582,7 @@ struct bch_pd_controller {
 
 void bch2_pd_controller_update(struct bch_pd_controller *, s64, s64, int);
 void bch2_pd_controller_init(struct bch_pd_controller *);
-size_t bch2_pd_controller_print_debug(struct bch_pd_controller *, char *);
+void bch2_pd_controller_debug_to_text(struct printbuf *, struct bch_pd_controller *);
 
 #define sysfs_pd_controller_attribute(name)				\
 	rw_attribute(name##_rate);					\
@@ -605,8 +605,10 @@ do {									\
 	sysfs_print(name##_rate_d_term,		(var)->d_term);		\
 	sysfs_print(name##_rate_p_term_inverse,	(var)->p_term_inverse);	\
 									\
-	if (attr == &sysfs_##name##_rate_debug)				\
-		return bch2_pd_controller_print_debug(var, buf);		\
+	if (attr == &sysfs_##name##_rate_debug) {			\
+		bch2_pd_controller_debug_to_text(&out, var);		\
+		return out.pos - buf;					\
+	}								\
 } while (0)
 
 #define sysfs_pd_controller_store(name, var)				\