bcachefs: Kill BTREE_ITER_ALL_LEVELS

As discussed in the previous patch, BTREE_ITER_ALL_LEVELS appears to be
racy with concurrent interior node updates - and perhaps it is fixable,
but it's tricky and unnecessary.

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

3 files changed, 24 insertions, 140 deletions

diff --git a/fs/bcachefs/btree_iter.c b/fs/bcachefs/btree_iter.c
index bf4d2ade4535..f58e03e3e038 100644
--- a/fs/bcachefs/btree_iter.c
+++ b/fs/bcachefs/btree_iter.c
@@ -1797,23 +1797,15 @@ err:
 
 inline bool bch2_btree_iter_advance(struct btree_iter *iter)
 {
-	if (likely(!(iter->flags & BTREE_ITER_ALL_LEVELS))) {
-		struct bpos pos = iter->k.p;
-		bool ret = !(iter->flags & BTREE_ITER_ALL_SNAPSHOTS
-			     ? bpos_eq(pos, SPOS_MAX)
-			     : bkey_eq(pos, SPOS_MAX));
-
-		if (ret && !(iter->flags & BTREE_ITER_IS_EXTENTS))
-			pos = bkey_successor(iter, pos);
-		bch2_btree_iter_set_pos(iter, pos);
-		return ret;
-	} else {
-		if (!btree_path_node(iter->path, iter->path->level))
-			return true;
+	struct bpos pos = iter->k.p;
+	bool ret = !(iter->flags & BTREE_ITER_ALL_SNAPSHOTS
+		     ? bpos_eq(pos, SPOS_MAX)
+		     : bkey_eq(pos, SPOS_MAX));
 
-		iter->advanced = true;
-		return false;
-	}
+	if (ret && !(iter->flags & BTREE_ITER_IS_EXTENTS))
+		pos = bkey_successor(iter, pos);
+	bch2_btree_iter_set_pos(iter, pos);
+	return ret;
 }
 
 inline bool bch2_btree_iter_rewind(struct btree_iter *iter)
@@ -2064,7 +2056,6 @@ struct bkey_s_c bch2_btree_iter_peek_upto(struct btree_iter *iter, struct bpos e
 	struct bpos iter_pos;
 	int ret;
 
-	EBUG_ON(iter->flags & BTREE_ITER_ALL_LEVELS);
 	EBUG_ON((iter->flags & BTREE_ITER_FILTER_SNAPSHOTS) && bkey_eq(end, POS_MAX));
 
 	if (iter->update_path) {
@@ -2204,103 +2195,6 @@ end:
 }
 
 /**
- * bch2_btree_iter_peek_all_levels() - returns the first key greater than or
- * equal to iterator's current position, returning keys from every level of the
- * btree. For keys at different levels of the btree that compare equal, the key
- * from the lower level (leaf) is returned first.
- * @iter:	iterator to peek from
- *
- * Returns:	key if found, or an error extractable with bkey_err().
- */
-struct bkey_s_c bch2_btree_iter_peek_all_levels(struct btree_iter *iter)
-{
-	struct btree_trans *trans = iter->trans;
-	struct bkey_s_c k;
-	int ret;
-
-	EBUG_ON(iter->path->cached);
-	bch2_btree_iter_verify(iter);
-	BUG_ON(iter->path->level < iter->min_depth);
-	BUG_ON(!(iter->flags & BTREE_ITER_ALL_SNAPSHOTS));
-	EBUG_ON(!(iter->flags & BTREE_ITER_ALL_LEVELS));
-
-	while (1) {
-		iter->path = bch2_btree_path_set_pos(trans, iter->path, iter->pos,
-					iter->flags & BTREE_ITER_INTENT,
-					btree_iter_ip_allocated(iter));
-
-		ret = bch2_btree_path_traverse(trans, iter->path, iter->flags);
-		if (unlikely(ret)) {
-			/* ensure that iter->k is consistent with iter->pos: */
-			bch2_btree_iter_set_pos(iter, iter->pos);
-			k = bkey_s_c_err(ret);
-			goto out_no_locked;
-		}
-
-		/* Already at end? */
-		if (!btree_path_node(iter->path, iter->path->level)) {
-			k = bkey_s_c_null;
-			goto out_no_locked;
-		}
-
-		k = btree_path_level_peek_all(trans->c,
-				&iter->path->l[iter->path->level], &iter->k);
-
-		/* Check if we should go up to the parent node: */
-		if (!k.k ||
-		    (iter->advanced &&
-		     bpos_eq(path_l(iter->path)->b->key.k.p, iter->pos))) {
-			iter->pos = path_l(iter->path)->b->key.k.p;
-			btree_path_set_level_up(trans, iter->path);
-			iter->advanced = false;
-			continue;
-		}
-
-		/*
-		 * Check if we should go back down to a leaf:
-		 * If we're not in a leaf node, we only return the current key
-		 * if it exactly matches iter->pos - otherwise we first have to
-		 * go back to the leaf:
-		 */
-		if (iter->path->level != iter->min_depth &&
-		    (iter->advanced ||
-		     !k.k ||
-		     !bpos_eq(iter->pos, k.k->p))) {
-			btree_path_set_level_down(trans, iter->path, iter->min_depth);
-			iter->pos = bpos_successor(iter->pos);
-			iter->advanced = false;
-			continue;
-		}
-
-		/* Check if we should go to the next key: */
-		if (iter->path->level == iter->min_depth &&
-		    iter->advanced &&
-		    k.k &&
-		    bpos_eq(iter->pos, k.k->p)) {
-			iter->pos = bpos_successor(iter->pos);
-			iter->advanced = false;
-			continue;
-		}
-
-		if (iter->advanced &&
-		    iter->path->level == iter->min_depth &&
-		    !bpos_eq(k.k->p, iter->pos))
-			iter->advanced = false;
-
-		BUG_ON(iter->advanced);
-		BUG_ON(!k.k);
-		break;
-	}
-
-	iter->pos = k.k->p;
-	btree_path_set_should_be_locked(iter->path);
-out_no_locked:
-	bch2_btree_iter_verify(iter);
-
-	return k;
-}
-
-/**
  * bch2_btree_iter_next() - returns first key greater than iterator's current
  * position
  * @iter:	iterator to peek from
@@ -2466,7 +2360,6 @@ struct bkey_s_c bch2_btree_iter_peek_slot(struct btree_iter *iter)
 
 	bch2_btree_iter_verify(iter);
 	bch2_btree_iter_verify_entry_exit(iter);
-	EBUG_ON(iter->flags & BTREE_ITER_ALL_LEVELS);
 	EBUG_ON(iter->path->level && (iter->flags & BTREE_ITER_WITH_KEY_CACHE));
 
 	/* extents can't span inode numbers: */
diff --git a/fs/bcachefs/btree_iter.h b/fs/bcachefs/btree_iter.h
index eaffced4c132..7286f92b1974 100644
--- a/fs/bcachefs/btree_iter.h
+++ b/fs/bcachefs/btree_iter.h
@@ -348,8 +348,6 @@ struct btree *bch2_btree_iter_next_node(struct btree_iter *);
 struct bkey_s_c bch2_btree_iter_peek_upto(struct btree_iter *, struct bpos);
 struct bkey_s_c bch2_btree_iter_next(struct btree_iter *);
 
-struct bkey_s_c bch2_btree_iter_peek_all_levels(struct btree_iter *);
-
 static inline struct bkey_s_c bch2_btree_iter_peek(struct btree_iter *iter)
 {
 	return bch2_btree_iter_peek_upto(iter, SPOS_MAX);
@@ -408,9 +406,6 @@ static inline unsigned __bch2_btree_iter_flags(struct btree_trans *trans,
 					       unsigned btree_id,
 					       unsigned flags)
 {
-	if (flags & BTREE_ITER_ALL_LEVELS)
-		flags |= BTREE_ITER_ALL_SNAPSHOTS|__BTREE_ITER_ALL_SNAPSHOTS;
-
 	if (!(flags & (BTREE_ITER_ALL_SNAPSHOTS|BTREE_ITER_NOT_EXTENTS)) &&
 	    btree_id_is_extents(btree_id))
 		flags |= BTREE_ITER_IS_EXTENTS;
@@ -606,8 +601,6 @@ u32 bch2_trans_begin(struct btree_trans *);
 static inline struct bkey_s_c bch2_btree_iter_peek_prev_type(struct btree_iter *iter,
 							     unsigned flags)
 {
-	BUG_ON(flags & BTREE_ITER_ALL_LEVELS);
-
 	return  flags & BTREE_ITER_SLOTS      ? bch2_btree_iter_peek_slot(iter) :
 						bch2_btree_iter_peek_prev(iter);
 }
@@ -615,8 +608,7 @@ static inline struct bkey_s_c bch2_btree_iter_peek_prev_type(struct btree_iter *
 static inline struct bkey_s_c bch2_btree_iter_peek_type(struct btree_iter *iter,
 							unsigned flags)
 {
-	return  flags & BTREE_ITER_ALL_LEVELS ? bch2_btree_iter_peek_all_levels(iter) :
-		flags & BTREE_ITER_SLOTS      ? bch2_btree_iter_peek_slot(iter) :
+	return  flags & BTREE_ITER_SLOTS      ? bch2_btree_iter_peek_slot(iter) :
 						bch2_btree_iter_peek(iter);
 }
 
diff --git a/fs/bcachefs/btree_types.h b/fs/bcachefs/btree_types.h
index b667da4e8403..7f17c23326c7 100644
--- a/fs/bcachefs/btree_types.h
+++ b/fs/bcachefs/btree_types.h
@@ -185,33 +185,32 @@ struct btree_node_iter {
  * Iterate over all possible positions, synthesizing deleted keys for holes:
  */
 static const __maybe_unused u16 BTREE_ITER_SLOTS		= 1 << 0;
-static const __maybe_unused u16 BTREE_ITER_ALL_LEVELS		= 1 << 1;
 /*
  * Indicates that intent locks should be taken on leaf nodes, because we expect
  * to be doing updates:
  */
-static const __maybe_unused u16 BTREE_ITER_INTENT		= 1 << 2;
+static const __maybe_unused u16 BTREE_ITER_INTENT		= 1 << 1;
 /*
  * Causes the btree iterator code to prefetch additional btree nodes from disk:
  */
-static const __maybe_unused u16 BTREE_ITER_PREFETCH		= 1 << 3;
+static const __maybe_unused u16 BTREE_ITER_PREFETCH		= 1 << 2;
 /*
  * Used in bch2_btree_iter_traverse(), to indicate whether we're searching for
  * @pos or the first key strictly greater than @pos
  */
-static const __maybe_unused u16 BTREE_ITER_IS_EXTENTS		= 1 << 4;
-static const __maybe_unused u16 BTREE_ITER_NOT_EXTENTS		= 1 << 5;
-static const __maybe_unused u16 BTREE_ITER_CACHED		= 1 << 6;
-static const __maybe_unused u16 BTREE_ITER_WITH_KEY_CACHE	= 1 << 7;
-static const __maybe_unused u16 BTREE_ITER_WITH_UPDATES		= 1 << 8;
-static const __maybe_unused u16 BTREE_ITER_WITH_JOURNAL		= 1 << 9;
-static const __maybe_unused u16 __BTREE_ITER_ALL_SNAPSHOTS	= 1 << 10;
-static const __maybe_unused u16 BTREE_ITER_ALL_SNAPSHOTS	= 1 << 11;
-static const __maybe_unused u16 BTREE_ITER_FILTER_SNAPSHOTS	= 1 << 12;
-static const __maybe_unused u16 BTREE_ITER_NOPRESERVE		= 1 << 13;
-static const __maybe_unused u16 BTREE_ITER_CACHED_NOFILL	= 1 << 14;
-static const __maybe_unused u16 BTREE_ITER_KEY_CACHE_FILL	= 1 << 15;
-#define __BTREE_ITER_FLAGS_END					       16
+static const __maybe_unused u16 BTREE_ITER_IS_EXTENTS		= 1 << 3;
+static const __maybe_unused u16 BTREE_ITER_NOT_EXTENTS		= 1 << 4;
+static const __maybe_unused u16 BTREE_ITER_CACHED		= 1 << 5;
+static const __maybe_unused u16 BTREE_ITER_WITH_KEY_CACHE	= 1 << 6;
+static const __maybe_unused u16 BTREE_ITER_WITH_UPDATES		= 1 << 7;
+static const __maybe_unused u16 BTREE_ITER_WITH_JOURNAL		= 1 << 8;
+static const __maybe_unused u16 __BTREE_ITER_ALL_SNAPSHOTS	= 1 << 9;
+static const __maybe_unused u16 BTREE_ITER_ALL_SNAPSHOTS	= 1 << 10;
+static const __maybe_unused u16 BTREE_ITER_FILTER_SNAPSHOTS	= 1 << 11;
+static const __maybe_unused u16 BTREE_ITER_NOPRESERVE		= 1 << 12;
+static const __maybe_unused u16 BTREE_ITER_CACHED_NOFILL	= 1 << 13;
+static const __maybe_unused u16 BTREE_ITER_KEY_CACHE_FILL	= 1 << 14;
+#define __BTREE_ITER_FLAGS_END					       15
 
 enum btree_path_uptodate {
 	BTREE_ITER_UPTODATE		= 0,