bcachefs: Kill bch2_verify_bucket_evacuated()

With backpointers, it's now impossible for bch2_evacuate_bucket() to be
completely reliable: it can race with an extent being partially
overwritten or split, which needs a new write buffer flush for the
backpointer to be seen.

This shouldn't be a real issue in practice; the previous patch added a
new tracepoint so we'll be able to see more easily if it is.

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

diff --git a/fs/bcachefs/move.c b/fs/bcachefs/move.c
index 498b3f9778de368531b0278040c13085a559cc81..642c076216ea1fb5759f3b1df79da80dad389724 100644 (file)
--- a/fs/bcachefs/move.c
+++ b/fs/bcachefs/move.c
@@ -654,85 +654,6 @@ int bch2_move_data(struct bch_fs *c,
        return ret;
 }
 
-void bch2_verify_bucket_evacuated(struct btree_trans *trans, struct bpos bucket, int gen)
-{
-       struct bch_fs *c = trans->c;
-       struct btree_iter iter;
-       struct bkey_s_c k;
-       struct printbuf buf = PRINTBUF;
-       struct bch_backpointer bp;
-       struct bpos bp_pos = POS_MIN;
-       unsigned nr_bps = 0;
-       int ret;
-
-       bch2_trans_begin(trans);
-
-       bch2_trans_iter_init(trans, &iter, BTREE_ID_alloc,
-                            bucket, BTREE_ITER_CACHED);
-again:
-       ret = lockrestart_do(trans,
-                       bkey_err(k = bch2_btree_iter_peek_slot(&iter)));
-
-       if (!ret && k.k->type == KEY_TYPE_alloc_v4) {
-               struct bkey_s_c_alloc_v4 a = bkey_s_c_to_alloc_v4(k);
-
-               if (a.v->gen == gen &&
-                   a.v->dirty_sectors) {
-                       if (a.v->data_type == BCH_DATA_btree) {
-                               bch2_trans_unlock(trans);
-                               if (bch2_btree_interior_updates_flush(c))
-                                       goto again;
-                               goto failed_to_evacuate;
-                       }
-               }
-       }
-
-       set_btree_iter_dontneed(&iter);
-       bch2_trans_iter_exit(trans, &iter);
-       return;
-failed_to_evacuate:
-       bch2_trans_iter_exit(trans, &iter);
-
-       if (test_bit(BCH_FS_EMERGENCY_RO, &c->flags))
-               return;
-
-       prt_printf(&buf, bch2_log_msg(c, "failed to evacuate bucket "));
-       bch2_bkey_val_to_text(&buf, c, k);
-
-       while (1) {
-               bch2_trans_begin(trans);
-
-               ret = bch2_get_next_backpointer(trans, bucket, gen,
-                                               &bp_pos, &bp,
-                                               BTREE_ITER_CACHED);
-               if (bch2_err_matches(ret, BCH_ERR_transaction_restart))
-                       continue;
-               if (ret)
-                       break;
-               if (bkey_eq(bp_pos, POS_MAX))
-                       break;
-
-               k = bch2_backpointer_get_key(trans, &iter, bp_pos, bp, 0);
-               ret = bkey_err(k);
-               if (bch2_err_matches(ret, BCH_ERR_transaction_restart))
-                       continue;
-               if (ret)
-                       break;
-               if (!k.k)
-                       continue;
-               prt_newline(&buf);
-               bch2_bkey_val_to_text(&buf, c, k);
-               bch2_trans_iter_exit(trans, &iter);
-
-               if (++nr_bps > 10)
-                       break;
-               bp_pos = bpos_nosnap_successor(bp_pos);
-       }
-
-       bch2_print_string_as_lines(KERN_ERR, buf.buf);
-       printbuf_exit(&buf);
-}
-
 int __bch2_evacuate_bucket(struct btree_trans *trans,
                           struct moving_context *ctxt,
                           struct move_bucket_in_flight *bucket_in_flight,

diff --git a/fs/bcachefs/move.h b/fs/bcachefs/move.h
index 50a6f7d7a292dcbe1b0f5e4b2c6959df701f9b60..547ee7b72c1617177056a3eb32061e345ed4351a 100644 (file)
--- a/fs/bcachefs/move.h
+++ b/fs/bcachefs/move.h
@@ -36,8 +36,6 @@ struct moving_context {
        wait_queue_head_t       wait;
 };
 
-void bch2_verify_bucket_evacuated(struct btree_trans *, struct bpos, int);
-
 #define move_ctxt_wait_event(_ctxt, _trans, _cond)                     \
 do {                                                                   \
        bool cond_finished = false;                                     \

diff --git a/fs/bcachefs/movinggc.c b/fs/bcachefs/movinggc.c
index 2d75334c541dd78960f696d4af5c9e17095da947..02081ee1a114e817490fc4a7926c8d4ffbfaa77a 100644 (file)
--- a/fs/bcachefs/movinggc.c
+++ b/fs/bcachefs/movinggc.c
@@ -134,13 +134,6 @@ static void move_buckets_wait(struct btree_trans *trans,
                if (atomic_read(&i->count))
                        break;
 
-               /*
-                * moving_ctxt_exit calls bch2_write as it flushes pending
-                * reads, which inits another btree_trans; this one must be
-                * unlocked:
-                */
-               bch2_verify_bucket_evacuated(trans, i->bucket.k.bucket, i->bucket.k.gen);
-
                list->first = i->next;
                if (!list->first)
                        list->last = NULL;