bcachefs: lockdep fix when going rw from bch2_alloc_write()

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

diff --git a/fs/bcachefs/alloc_background.c b/fs/bcachefs/alloc_background.c
index 5c8cebc443d1b7ddf56e081f9ab50396d15fc622..c254c08af9d174d15ddc3171b3ab8d3fe24122fd 100644 (file)
--- a/fs/bcachefs/alloc_background.c
+++ b/fs/bcachefs/alloc_background.c
@@ -411,21 +411,21 @@ static int __bch2_alloc_write_key(struct btree_trans *trans, struct bch_dev *ca,
 
 int bch2_alloc_write(struct bch_fs *c, unsigned flags, bool *wrote)
 {
+       struct btree_trans trans;
+       struct btree_iter *iter;
+       struct bucket_array *buckets;
        struct bch_dev *ca;
        unsigned i;
+       size_t b;
        int ret = 0;
 
-       for_each_rw_member(ca, c, i) {
-               struct btree_trans trans;
-               struct btree_iter *iter;
-               struct bucket_array *buckets;
-               size_t b;
-
-               bch2_trans_init(&trans, c);
+       bch2_trans_init(&trans, c);
 
-               iter = bch2_trans_get_iter(&trans, BTREE_ID_ALLOC, POS_MIN,
-                                          BTREE_ITER_SLOTS|BTREE_ITER_INTENT);
+       iter = bch2_trans_get_iter(&trans, BTREE_ID_ALLOC, POS_MIN,
+                                  BTREE_ITER_SLOTS|BTREE_ITER_INTENT);
 
+       for_each_rw_member(ca, c, i) {
+relock:
                down_read(&ca->bucket_lock);
                buckets = bucket_array(ca);
 
@@ -435,6 +435,17 @@ int bch2_alloc_write(struct bch_fs *c, unsigned flags, bool *wrote)
                        if (!buckets->b[b].mark.dirty)
                                continue;
 
+                       if ((flags & BTREE_INSERT_LAZY_RW) &&
+                           percpu_ref_is_zero(&c->writes)) {
+                               up_read(&ca->bucket_lock);
+                               bch2_trans_unlock(&trans);
+
+                               ret = bch2_fs_read_write_early(c);
+                               if (ret)
+                                       goto out;
+                               goto relock;
+                       }
+
                        ret = __bch2_alloc_write_key(&trans, ca, b,
                                                     iter, flags);
                        if (ret)
@@ -444,15 +455,15 @@ int bch2_alloc_write(struct bch_fs *c, unsigned flags, bool *wrote)
                        *wrote = true;
                }
                up_read(&ca->bucket_lock);
-
-               bch2_trans_exit(&trans);
-
+out:
                if (ret) {
                        percpu_ref_put(&ca->io_ref);
                        break;
                }
        }
 
+       bch2_trans_exit(&trans);
+
        return ret;
 }