bcachefs: bch2_backpointer_get_key() now repairs dangling backpointers

Continuing on with the self healing theme, we should be running any
check and repair code at runtime that we can - instead of declaring the
filesystemt inconsistent.

This will also let us skip running the backpointers -> extents fsck pass
except in debug mode.

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

diff --git a/fs/bcachefs/backpointers.c b/fs/bcachefs/backpointers.c
index 892939763c3a6e482a6c52236253f764bf48c9d4..5cc4aaa3a3255c13067409fdfa169ca955ff08ca 100644 (file)
--- a/fs/bcachefs/backpointers.c
+++ b/fs/bcachefs/backpointers.c
@@ -172,9 +172,10 @@ err:
 
 static int bch2_backpointer_del(struct btree_trans *trans, struct bpos pos)
 {
-       return likely(!bch2_backpointers_no_use_write_buffer)
-              ? bch2_btree_delete_at_buffered(trans, BTREE_ID_backpointers, pos)
-              : bch2_btree_delete(trans, BTREE_ID_backpointers, pos, 0);
+       return (likely(!bch2_backpointers_no_use_write_buffer)
+               ? bch2_btree_delete_at_buffered(trans, BTREE_ID_backpointers, pos)
+               : bch2_btree_delete(trans, BTREE_ID_backpointers, pos, 0)) ?:
+                bch2_trans_commit(trans, NULL, NULL, BCH_TRANS_COMMIT_no_enospc);
 }
 
 static inline int bch2_backpointers_maybe_flush(struct btree_trans *trans,
@@ -186,20 +187,25 @@ static inline int bch2_backpointers_maybe_flush(struct btree_trans *trans,
                : 0;
 }
 
-static void backpointer_target_not_found(struct btree_trans *trans,
-                                        struct bkey_s_c_backpointer bp,
-                                        struct bkey_s_c target_k)
+static int backpointer_target_not_found(struct btree_trans *trans,
+                                 struct bkey_s_c_backpointer bp,
+                                 struct bkey_s_c target_k,
+                                 struct bkey_buf *last_flushed)
 {
        struct bch_fs *c = trans->c;
        struct printbuf buf = PRINTBUF;
+       int ret = 0;
 
        /*
         * If we're using the btree write buffer, the backpointer we were
         * looking at may have already been deleted - failure to find what it
         * pointed to is not an error:
         */
-       if (likely(!bch2_backpointers_no_use_write_buffer))
-               return;
+       ret = last_flushed
+               ? bch2_backpointers_maybe_flush(trans, bp.s_c, last_flushed)
+               : 0;
+       if (ret)
+               return ret;
 
        prt_printf(&buf, "backpointer doesn't match %s it points to:\n  ",
                   bp.v->level ? "btree node" : "extent");
@@ -207,12 +213,13 @@ static void backpointer_target_not_found(struct btree_trans *trans,
        prt_printf(&buf, "\n  ");
 
        bch2_bkey_val_to_text(&buf, c, target_k);
-       if (c->curr_recovery_pass >= BCH_RECOVERY_PASS_check_extents_to_backpointers)
-               bch_err_ratelimited(c, "%s", buf.buf);
-       else
-               bch2_trans_inconsistent(trans, "%s", buf.buf);
 
+       if (fsck_err(trans, backpointer_to_missing_ptr,
+                    "%s", buf.buf))
+               ret = bch2_backpointer_del(trans, bp.k->p);
+fsck_err:
        printbuf_exit(&buf);
+       return ret;
 }
 
 struct bkey_s_c bch2_backpointer_get_key(struct btree_trans *trans,
@@ -243,15 +250,13 @@ struct bkey_s_c bch2_backpointer_get_key(struct btree_trans *trans,
                        return k;
 
                bch2_trans_iter_exit(trans, iter);
-               backpointer_target_not_found(trans, bp, k);
-               return bkey_s_c_null;
+               int ret = backpointer_target_not_found(trans, bp, k, last_flushed);
+               return ret ? bkey_s_c_err(ret) : bkey_s_c_null;
        } else {
                struct btree *b = bch2_backpointer_get_node(trans, bp, iter, last_flushed);
+               if (IS_ERR_OR_NULL(b))
+                       return ((struct bkey_s_c) { .k = ERR_CAST(b) });
 
-               if (IS_ERR_OR_NULL(b)) {
-                       bch2_trans_iter_exit(trans, iter);
-                       return IS_ERR(b) ? bkey_s_c_err(PTR_ERR(b)) : bkey_s_c_null;
-               }
                return bkey_i_to_s_c(&b->key);
        }
 }
@@ -284,8 +289,8 @@ struct btree *bch2_backpointer_get_node(struct btree_trans *trans,
        if (btree_node_will_make_reachable(b)) {
                b = ERR_PTR(-BCH_ERR_backpointer_to_overwritten_btree_node);
        } else {
-               backpointer_target_not_found(trans, bp, bkey_i_to_s_c(&b->key));
-               b = NULL;
+               int ret = backpointer_target_not_found(trans, bp, bkey_i_to_s_c(&b->key), last_flushed);
+               b = ret ? ERR_PTR(ret) : NULL;
        }
 err:
        bch2_trans_iter_exit(trans, iter);
@@ -488,7 +493,7 @@ check_existing_bp:
        struct bkey_s_c_backpointer other_bp = bkey_s_c_to_backpointer(bp_k);
 
        struct bkey_s_c other_extent =
-               bch2_backpointer_get_key(trans, other_bp, &other_extent_iter, 0, &s->last_flushed);
+               bch2_backpointer_get_key(trans, other_bp, &other_extent_iter, 0, NULL);
        ret = bkey_err(other_extent);
        if (ret == -BCH_ERR_backpointer_to_overwritten_btree_node)
                ret = 0;
@@ -1143,9 +1148,7 @@ static int check_one_backpointer(struct btree_trans *trans,
                return 0;
 
        struct bkey_s_c_backpointer bp = bkey_s_c_to_backpointer(bp_k);
-       struct bch_fs *c = trans->c;
        struct bbpos pos = bp_to_bbpos(*bp.v);
-       struct printbuf buf = PRINTBUF;
 
        if (bbpos_cmp(pos, start) < 0 ||
            bbpos_cmp(pos, end) > 0)
@@ -1159,23 +1162,7 @@ static int check_one_backpointer(struct btree_trans *trans,
        if (ret)
                return ret;
 
-       if (!k.k) {
-               ret = bch2_backpointers_maybe_flush(trans, bp.s_c, last_flushed);
-               if (ret)
-                       goto out;
-
-               if (fsck_err(trans, backpointer_to_missing_ptr,
-                            "backpointer for missing %s\n  %s",
-                            bp.v->level ? "btree node" : "extent",
-                            (bch2_bkey_val_to_text(&buf, c, bp.s_c), buf.buf))) {
-                       ret = bch2_backpointer_del(trans, bp.k->p);
-                       goto out;
-               }
-       }
-out:
-fsck_err:
        bch2_trans_iter_exit(trans, &iter);
-       printbuf_exit(&buf);
        return ret;
 }
 
@@ -1210,9 +1197,8 @@ static int bch2_check_backpointers_to_extents_pass(struct btree_trans *trans,
        bkey_init(&last_flushed.k->k);
        progress_init(&progress, trans->c, BIT_ULL(BTREE_ID_backpointers));
 
-       int ret = for_each_btree_key_commit(trans, iter, BTREE_ID_backpointers,
-                                 POS_MIN, BTREE_ITER_prefetch, k,
-                                 NULL, NULL, BCH_TRANS_COMMIT_no_enospc, ({
+       int ret = for_each_btree_key(trans, iter, BTREE_ID_backpointers,
+                                    POS_MIN, BTREE_ITER_prefetch, k, ({
                        progress_update_iter(trans, &progress, &iter, "backpointers_to_extents");
                        check_one_backpointer(trans, start, end, k, &last_flushed);
        }));