bcachefs: Fix btree_node_scan io_ref handling

This was completely fubar; it's now simplified a bit as well.
Note that for_each_online_member() takes and releases io_refs as it
iterates, so we need to release that if we break.

Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>

diff --git a/fs/bcachefs/btree_node_scan.c b/fs/bcachefs/btree_node_scan.c
index fb73ec77c099f2b15c9875ad3a010ed3873b026d..678161321e426479334512adbfb10d96f2f64658 100644 (file)
--- a/fs/bcachefs/btree_node_scan.c
+++ b/fs/bcachefs/btree_node_scan.c
@@ -270,7 +270,7 @@ static int read_btree_nodes_worker(void *p)
 err:
        bio_put(bio);
        free_page((unsigned long) buf);
-       percpu_ref_get(&ca->io_ref);
+       percpu_ref_put(&ca->io_ref);
        closure_put(w->cl);
        kfree(w);
        return 0;
@@ -289,29 +289,28 @@ static int read_btree_nodes(struct find_btree_nodes *f)
                        continue;
 
                struct find_btree_nodes_worker *w = kmalloc(sizeof(*w), GFP_KERNEL);
-               struct task_struct *t;
-
                if (!w) {
                        percpu_ref_put(&ca->io_ref);
                        ret = -ENOMEM;
                        goto err;
                }
 
-               percpu_ref_get(&ca->io_ref);
-               closure_get(&cl);
                w->cl           = &cl;
                w->f            = f;
                w->ca           = ca;
 
-               t = kthread_run(read_btree_nodes_worker, w, "read_btree_nodes/%s", ca->name);
+               struct task_struct *t = kthread_create(read_btree_nodes_worker, w, "read_btree_nodes/%s", ca->name);
                ret = PTR_ERR_OR_ZERO(t);
                if (ret) {
                        percpu_ref_put(&ca->io_ref);
-                       closure_put(&cl);
-                       f->ret = ret;
-                       bch_err(c, "error starting kthread: %i", ret);
+                       kfree(w);
+                       bch_err_msg(c, ret, "starting kthread");
                        break;
                }
+
+               closure_get(&cl);
+               percpu_ref_get(&ca->io_ref);
+               wake_up_process(t);
        }
 err:
        closure_sync(&cl);