bcachefs: Start/stop io clock hands in read/write paths

This fixes a bug where the clock hands in the journal and superblock
didn't match, because we were still incrementing the read clock hand
while read-only.
Signed-off-by: Kent Overstreet <kent.overstreet@gmail.com>
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>

fs/bcachefs/alloc_background.c

@@ -1267,18 +1267,6 @@ void bch2_recalc_capacity(struct bch_fs *c)
 
 	c->bucket_size_max = bucket_size_max;
 
-	if (c->capacity) {
-		bch2_io_timer_add(&c->io_clock[READ],
-				 &c->bucket_clock[READ].rescale);
-		bch2_io_timer_add(&c->io_clock[WRITE],
-				 &c->bucket_clock[WRITE].rescale);
-	} else {
-		bch2_io_timer_del(&c->io_clock[READ],
-				 &c->bucket_clock[READ].rescale);
-		bch2_io_timer_del(&c->io_clock[WRITE],
-				 &c->bucket_clock[WRITE].rescale);
-	}
-
 	/* Wake up case someone was waiting for buckets */
 	closure_wake_up(&c->freelist_wait);
 }

fs/bcachefs/super.c

@@ -182,6 +182,9 @@ static void __bch2_fs_read_only(struct bch_fs *c)
 	bch2_copygc_stop(c);
 	bch2_gc_thread_stop(c);
 
+	bch2_io_timer_del(&c->io_clock[READ], &c->bucket_clock[READ].rescale);
+	bch2_io_timer_del(&c->io_clock[WRITE], &c->bucket_clock[WRITE].rescale);
+
 	/*
 	 * Flush journal before stopping allocators, because flushing journal
 	 * blacklist entries involves allocating new btree nodes:
@@ -407,6 +410,9 @@ static int __bch2_fs_read_write(struct bch_fs *c, bool early)
 		bch2_dev_allocator_add(c, ca);
 	bch2_recalc_capacity(c);
 
+	bch2_io_timer_add(&c->io_clock[READ], &c->bucket_clock[READ].rescale);
+	bch2_io_timer_add(&c->io_clock[WRITE], &c->bucket_clock[WRITE].rescale);
+
 	for_each_rw_member(ca, c, i) {
 		ret = bch2_dev_allocator_start(ca);
 		if (ret) {