1 files changed, 27 insertions, 154 deletions

diff --git a/libbcachefs/btree_update.c b/libbcachefs/btree_update.c
index ac852310..cbb7cf21 100644
--- a/libbcachefs/btree_update.c
+++ b/libbcachefs/btree_update.c
@@ -82,168 +82,38 @@ static noinline int extent_back_merge(struct btree_trans *trans,
 	return 0;
 }
 
-static struct bkey_s_c peek_slot_including_whiteouts(struct btree_trans *trans, struct btree_iter *iter,
-						     enum btree_id btree, struct bpos pos)
-{
-	struct bkey_s_c k;
-	int ret;
-
-	for_each_btree_key_norestart(trans, *iter, btree, pos,
-			   BTREE_ITER_ALL_SNAPSHOTS|
-			   BTREE_ITER_NOPRESERVE, k, ret) {
-		if (!bkey_eq(k.k->p, pos))
-			break;
-		if (bch2_snapshot_is_ancestor(trans->c, pos.snapshot, k.k->p.snapshot))
-			return k;
-	}
-	bch2_trans_iter_exit(trans, iter);
-
-	return ret ? bkey_s_c_err(ret) : bkey_s_c_null;
-}
-
 /*
  * When deleting, check if we need to emit a whiteout (because we're overwriting
  * something in an ancestor snapshot)
  */
-static int need_whiteout_for_snapshot(struct btree_trans *trans, enum btree_id btree, struct bpos pos)
-{
-	pos.snapshot = bch2_snapshot_parent(trans->c, pos.snapshot);
-	if (!pos.snapshot)
-		return 0;
-
-	struct btree_iter iter;
-	struct bkey_s_c k = peek_slot_including_whiteouts(trans, &iter, btree, pos);
-	int ret = bkey_err(k) ?: k.k && !bkey_whiteout(k.k);
-	bch2_trans_iter_exit(trans, &iter);
-
-	return ret;
-}
-
-/*
- * We're overwriting a key at @pos in snapshot @snapshot, so we need to insert a
- * whiteout: that might be in @snapshot, or if there are overwites in sibling
- * snapshots, find the common ancestor where @pos is overwritten in every
- * descendent and insert the whiteout there - which might be at @pos.
- */
-static int delete_interior_snapshot_key(struct btree_trans *trans,
-					enum btree_id btree,
-					struct bpos whiteout, bool deleting,
-					struct bpos overwrite, bool old_is_whiteout)
+static int need_whiteout_for_snapshot(struct btree_trans *trans,
+				      enum btree_id btree_id, struct bpos pos)
 {
-	struct bch_fs *c = trans->c;
-	struct bpos orig_whiteout = whiteout, sib = whiteout;
 	struct btree_iter iter;
 	struct bkey_s_c k;
+	u32 snapshot = pos.snapshot;
 	int ret;
 
-	sib.snapshot = bch2_snapshot_sibling(c, sib.snapshot);
+	if (!bch2_snapshot_parent(trans->c, pos.snapshot))
+		return 0;
 
-	for_each_btree_key_norestart(trans, iter, btree, sib,
-				     BTREE_ITER_ALL_SNAPSHOTS|BTREE_ITER_INTENT, k, ret) {
-		BUG_ON(bpos_gt(k.k->p, overwrite));
+	pos.snapshot++;
 
-		if (bpos_lt(k.k->p, sib)) /* unrelated branch - skip */
-			continue;
-		if (bpos_gt(k.k->p, sib)) /* did not find @sib */
+	for_each_btree_key_norestart(trans, iter, btree_id, pos,
+			   BTREE_ITER_ALL_SNAPSHOTS|
+			   BTREE_ITER_NOPRESERVE, k, ret) {
+		if (!bkey_eq(k.k->p, pos))
 			break;
 
-		/* @overwrite is also written in @sib, now check parent */
-		whiteout.snapshot = bch2_snapshot_parent(c, whiteout.snapshot);
-		if (bpos_eq(whiteout, overwrite))
+		if (bch2_snapshot_is_ancestor(trans->c, snapshot,
+					      k.k->p.snapshot)) {
+			ret = !bkey_whiteout(k.k);
 			break;
-
-		sib = whiteout;
-		sib.snapshot = bch2_snapshot_sibling(c, sib.snapshot);
-	}
-
-	if (ret)
-		goto err;
-
-	if (!deleting && bpos_eq(whiteout, orig_whiteout))
-		goto out;
-
-	if (!bpos_eq(iter.pos, whiteout)) {
-		bch2_trans_iter_exit(trans, &iter);
-		bch2_trans_iter_init(trans, &iter, btree, whiteout, BTREE_ITER_INTENT);
-		k = bch2_btree_iter_peek_slot(&iter);
-		ret = bkey_err(k);
-		if (ret)
-			goto err;
-	}
-
-	iter.flags &= ~BTREE_ITER_ALL_SNAPSHOTS;
-	iter.flags |= BTREE_ITER_FILTER_SNAPSHOTS;
-
-	struct bkey_i *delete = bch2_trans_kmalloc(trans, sizeof(*delete));
-	ret = PTR_ERR_OR_ZERO(delete);
-	if (ret)
-		goto err;
-
-	bkey_init(&delete->k);
-	delete->k.p = whiteout;
-
-	ret = !bpos_eq(whiteout, overwrite)
-		? !old_is_whiteout
-		: need_whiteout_for_snapshot(trans, btree, whiteout);
-	if (ret < 0)
-		goto err;
-	if (ret)
-		delete->k.type = KEY_TYPE_whiteout;
-
-	ret = bch2_trans_update(trans, &iter, delete,
-				BTREE_UPDATE_INTERNAL_SNAPSHOT_NODE|
-				BTREE_UPDATE_SNAPSHOT_WHITEOUT_CHECKS_DONE);
-out:
-err:
-	bch2_trans_iter_exit(trans, &iter);
-	return ret;
-}
-
-/*
- * We're overwriting a key in a snapshot that has ancestors: if we're
- * overwriting a key in a different snapshot, we need to check if it is now
- * fully overritten and can be deleted, and if we're deleting a key in the
- * current snapshot we need to check if we need to leave a whiteout.
- */
-static noinline int
-overwrite_interior_snapshot_key(struct btree_trans *trans,
-				struct btree_iter *iter,
-				struct bkey_i *k)
-{
-	struct bkey_s_c old = bch2_btree_iter_peek_slot(iter);
-
-	int ret = bkey_err(old);
-	if (ret)
-		return ret;
-
-	if (!bkey_deleted(old.k)) {
-		if (btree_type_snapshots_unreffed(iter->btree_id) &&
-		    old.k->p.snapshot != k->k.p.snapshot) {
-			/*
-			 * We're overwriting a key in a different snapshot:
-			 * check if it's also been overwritten in siblings
-			 */
-			ret = delete_interior_snapshot_key(trans, iter->btree_id,
-							   k->k.p,   bkey_deleted(&k->k),
-							   old.k->p, bkey_whiteout(old.k));
-			if (ret)
-				return ret;
-			if (bkey_deleted(&k->k))
-				return 1;
-		} else if (bkey_deleted(&k->k)) {
-			/*
-			 * We're deleting a key in the current snapshot:
-			 * check if we need to leave a whiteout
-			 */
-			ret = need_whiteout_for_snapshot(trans, iter->btree_id, k->k.p);
-			if (unlikely(ret < 0))
-				return ret;
-			if (ret)
-				k->k.type = KEY_TYPE_whiteout;
 		}
 	}
+	bch2_trans_iter_exit(trans, &iter);
 
-	return 0;
+	return ret;
 }
 
 int __bch2_insert_snapshot_whiteouts(struct btree_trans *trans,
@@ -633,29 +503,32 @@ static noinline int bch2_trans_update_get_key_cache(struct btree_trans *trans,
 int __must_check bch2_trans_update(struct btree_trans *trans, struct btree_iter *iter,
 				   struct bkey_i *k, enum btree_update_flags flags)
 {
+	btree_path_idx_t path_idx = iter->update_path ?: iter->path;
+	int ret;
+
 	if (iter->flags & BTREE_ITER_IS_EXTENTS)
 		return bch2_trans_update_extent(trans, iter, k, flags);
 
-	if (!(flags & (BTREE_UPDATE_SNAPSHOT_WHITEOUT_CHECKS_DONE|
-		       BTREE_UPDATE_KEY_CACHE_RECLAIM)) &&
-	    (iter->flags & BTREE_ITER_FILTER_SNAPSHOTS) &&
-	    bch2_snapshot_parent(trans->c, k->k.p.snapshot)) {
-		int ret = overwrite_interior_snapshot_key(trans, iter, k);
+	if (bkey_deleted(&k->k) &&
+	    !(flags & BTREE_UPDATE_KEY_CACHE_RECLAIM) &&
+	    (iter->flags & BTREE_ITER_FILTER_SNAPSHOTS)) {
+		ret = need_whiteout_for_snapshot(trans, iter->btree_id, k->k.p);
+		if (unlikely(ret < 0))
+			return ret;
+
 		if (ret)
-			return ret < 0 ? ret : 0;
+			k->k.type = KEY_TYPE_whiteout;
 	}
 
 	/*
 	 * Ensure that updates to cached btrees go to the key cache:
 	 */
-	btree_path_idx_t path_idx = iter->update_path ?: iter->path;
 	struct btree_path *path = trans->paths + path_idx;
-
 	if (!(flags & BTREE_UPDATE_KEY_CACHE_RECLAIM) &&
 	    !path->cached &&
 	    !path->level &&
 	    btree_id_cached(trans->c, path->btree_id)) {
-		int ret = bch2_trans_update_get_key_cache(trans, iter, path);
+		ret = bch2_trans_update_get_key_cache(trans, iter, path);
 		if (ret)
 			return ret;