bcachefs: Fix null ptr deref when splitting compressed extents

Signed-off-by: Kent Overstreet <kent.overstreet@gmail.com>

fs/bcachefs/btree_iter.c

@@ -2329,6 +2329,7 @@ void bch2_trans_reset(struct btree_trans *trans, unsigned flags)
 
 	trans->iters_touched &= trans->iters_live;
 
+	trans->extra_journal_res	= 0;
 	trans->nr_updates		= 0;
 	trans->mem_top			= 0;
 

fs/bcachefs/btree_types.h

@@ -383,6 +383,11 @@ struct btree_trans {
 	unsigned		used_mempool:1;
 	unsigned		error:1;
 	unsigned		in_traverse_all:1;
+	/*
+	 * For when bch2_trans_update notices we'll be splitting a compressed
+	 * extent:
+	 */
+	unsigned		extra_journal_res;
 
 	u64			iters_linked;
 	u64			iters_live;
@@ -680,7 +685,6 @@ enum btree_insert_ret {
 	BTREE_INSERT_OK,
 	/* leaf node needs to be split */
 	BTREE_INSERT_BTREE_NODE_FULL,
-	BTREE_INSERT_ENOSPC,
 	BTREE_INSERT_NEED_MARK_REPLICAS,
 	BTREE_INSERT_NEED_JOURNAL_RES,
 	BTREE_INSERT_NEED_JOURNAL_RECLAIM,

fs/bcachefs/btree_update_leaf.c

@@ -696,10 +696,6 @@ int bch2_trans_commit_error(struct btree_trans *trans,
 			ret = -EINTR;
 		}
 		break;
-	case BTREE_INSERT_ENOSPC:
-		BUG_ON(flags & BTREE_INSERT_NOFAIL);
-		ret = -ENOSPC;
-		break;
 	case BTREE_INSERT_NEED_MARK_REPLICAS:
 		bch2_trans_unlock(trans);
 
@@ -833,7 +829,7 @@ static int extent_handle_overwrites(struct btree_trans *trans,
 	struct bpos start = bkey_start_pos(&i->k->k);
 	struct bkey_i *update;
 	struct bkey_s_c k;
-	int ret = 0;
+	int ret = 0, compressed_sectors;
 
 	iter = bch2_trans_get_iter(trans, i->btree_id, start,
 				   BTREE_ITER_INTENT|
@@ -854,6 +850,16 @@ static int extent_handle_overwrites(struct btree_trans *trans,
 	}
 
 	while (bkey_cmp(i->k->k.p, bkey_start_pos(k.k)) > 0) {
+		/*
+		 * If we're going to be splitting a compressed extent, note it
+		 * so that __bch2_trans_commit() can increase our disk
+		 * reservation:
+		 */
+		if (bkey_cmp(bkey_start_pos(k.k), start) < 0 &&
+		    bkey_cmp(k.k->p, i->k->k.p) > 0 &&
+		    (compressed_sectors = bch2_bkey_sectors_compressed(k)))
+			trans->extra_journal_res += compressed_sectors;
+
 		if (bkey_cmp(bkey_start_pos(k.k), start) < 0) {
 			update = bch2_trans_kmalloc(trans, bkey_bytes(k.k));
 			if ((ret = PTR_ERR_OR_ZERO(update)))
@@ -992,6 +998,15 @@ int __bch2_trans_commit(struct btree_trans *trans)
 			trans->journal_preres_u64s += u64s;
 		trans->journal_u64s += u64s;
 	}
+
+	if (trans->extra_journal_res) {
+		ret = bch2_disk_reservation_add(trans->c, trans->disk_res,
+				trans->extra_journal_res,
+				(trans->flags & BTREE_INSERT_NOFAIL)
+				? BCH_DISK_RESERVATION_NOFAIL : 0);
+		if (ret)
+			goto err;
+	}
 retry:
 	memset(&trans->journal_res, 0, sizeof(trans->journal_res));
 
@@ -1045,22 +1060,12 @@ int bch2_trans_update(struct btree_trans *trans, struct btree_iter *iter,
 	BUG_ON(trans->nr_updates >= BTREE_ITER_MAX);
 
 #ifdef CONFIG_BCACHEFS_DEBUG
-	BUG_ON(bkey_cmp(iter->pos,
-			is_extent ? bkey_start_pos(&k->k) : k->k.p));
-
-	trans_for_each_update(trans, i) {
-		BUG_ON(bkey_cmp(i->iter->pos, i->k->k.p));
-
+	trans_for_each_update(trans, i)
 		BUG_ON(i != trans->updates &&
 		       btree_insert_entry_cmp(i - 1, i) >= 0);
-	}
 #endif
 
 	if (is_extent) {
-		ret = bch2_extent_can_insert(trans, n.iter, n.k);
-		if (ret)
-			return ret;
-
 		ret = extent_handle_overwrites(trans, &n);
 		if (ret)
 			return ret;

fs/bcachefs/extent_update.c

@@ -173,38 +173,3 @@ int bch2_extent_is_atomic(struct bkey_i *k, struct btree_iter *iter)
 
 	return !bkey_cmp(end, k->k.p);
 }
-
-enum btree_insert_ret
-bch2_extent_can_insert(struct btree_trans *trans,
-		       struct btree_iter *iter,
-		       struct bkey_i *insert)
-{
-	struct bkey_s_c k;
-	int ret, sectors;
-
-	k = bch2_btree_iter_peek_slot(iter);
-	ret = bkey_err(k);
-	if (ret)
-		return ret;
-
-	/* Check if we're splitting a compressed extent: */
-
-	if (bkey_cmp(bkey_start_pos(&insert->k), bkey_start_pos(k.k)) > 0 &&
-	    bkey_cmp(insert->k.p, k.k->p) < 0 &&
-	    (sectors = bch2_bkey_sectors_compressed(k))) {
-		int flags = trans->flags & BTREE_INSERT_NOFAIL
-			? BCH_DISK_RESERVATION_NOFAIL : 0;
-
-		switch (bch2_disk_reservation_add(trans->c, trans->disk_res,
-						  sectors, flags)) {
-		case 0:
-			break;
-		case -ENOSPC:
-			return BTREE_INSERT_ENOSPC;
-		default:
-			BUG();
-		}
-	}
-
-	return BTREE_INSERT_OK;
-}

fs/bcachefs/extent_update.h

@@ -9,8 +9,4 @@ int bch2_extent_atomic_end(struct btree_iter *, struct bkey_i *,
 int bch2_extent_trim_atomic(struct bkey_i *, struct btree_iter *);
 int bch2_extent_is_atomic(struct bkey_i *, struct btree_iter *);
 
-enum btree_insert_ret
-bch2_extent_can_insert(struct btree_trans *, struct btree_iter *,
-		       struct bkey_i *);
-
 #endif /* _BCACHEFS_EXTENT_UPDATE_H */