bcachefs: Fix locking when checking freespace btree

On transaction restart, we weren't re-validating the hole we saw.

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

diff --git a/fs/bcachefs/alloc_background.c b/fs/bcachefs/alloc_background.c
index 1fec0e67891f120efefed775c8010bc1b6675a86..6002bd0cf89c669119e0b4e11168920f07d6c2df 100644 (file)
--- a/fs/bcachefs/alloc_background.c
+++ b/fs/bcachefs/alloc_background.c
@@ -1212,7 +1212,7 @@ fsck_err:
        return ret;
 }
 
-static noinline_for_stack int __bch2_check_discard_freespace_key(struct btree_trans *trans,
+static noinline_for_stack int bch2_check_discard_freespace_key(struct btree_trans *trans,
                                              struct btree_iter *iter)
 {
        struct bch_fs *c = trans->c;
@@ -1271,24 +1271,6 @@ delete:
        goto out;
 }
 
-static int bch2_check_discard_freespace_key(struct btree_trans *trans,
-                                           struct btree_iter *iter,
-                                           struct bpos end)
-{
-       if (!btree_id_is_extents(iter->btree_id)) {
-               return __bch2_check_discard_freespace_key(trans, iter);
-       } else {
-               int ret = 0;
-
-               while (!bkey_eq(iter->pos, end) &&
-                      !(ret = btree_trans_too_many_iters(trans) ?:
-                              __bch2_check_discard_freespace_key(trans, iter)))
-                       bch2_btree_iter_set_pos(iter, bpos_nosnap_successor(iter->pos));
-
-               return ret;
-       }
-}
-
 /*
  * We've already checked that generation numbers in the bucket_gens btree are
  * valid for buckets that exist; this just checks for keys for nonexistent
@@ -1445,12 +1427,40 @@ bkey_err:
        ret = for_each_btree_key2(trans, iter,
                        BTREE_ID_need_discard, POS_MIN,
                        BTREE_ITER_PREFETCH, k,
-               bch2_check_discard_freespace_key(trans, &iter, k.k->p)) ?:
-             for_each_btree_key2(trans, iter,
-                       BTREE_ID_freespace, POS_MIN,
-                       BTREE_ITER_PREFETCH, k,
-               bch2_check_discard_freespace_key(trans, &iter, k.k->p)) ?:
-             for_each_btree_key_commit(trans, iter,
+               bch2_check_discard_freespace_key(trans, &iter));
+       if (ret)
+               goto err;
+
+       bch2_trans_iter_init(trans, &iter, BTREE_ID_freespace, POS_MIN,
+                            BTREE_ITER_PREFETCH);
+       while (1) {
+               bch2_trans_begin(trans);
+               k = bch2_btree_iter_peek(&iter);
+               if (!k.k)
+                       break;
+
+               ret = bkey_err(k) ?:
+                       bch2_check_discard_freespace_key(trans, &iter);
+               if (bch2_err_matches(ret, BCH_ERR_transaction_restart)) {
+                       ret = 0;
+                       continue;
+               }
+               if (ret) {
+                       struct printbuf buf = PRINTBUF;
+                       bch2_bkey_val_to_text(&buf, c, k);
+
+                       bch_err(c, "while checking %s", buf.buf);
+                       printbuf_exit(&buf);
+                       break;
+               }
+
+               bch2_btree_iter_set_pos(&iter, bpos_nosnap_successor(iter.pos));
+       }
+       bch2_trans_iter_exit(trans, &iter);
+       if (ret)
+               goto err;
+
+       ret = for_each_btree_key_commit(trans, iter,
                        BTREE_ID_bucket_gens, POS_MIN,
                        BTREE_ITER_PREFETCH, k,
                        NULL, NULL, BTREE_INSERT_NOFAIL|BTREE_INSERT_LAZY_RW,