bcachefs: Fix bch2_sort_keys() to not modify src keys

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

fs/bcachefs/bkey_sort.c

@@ -254,23 +254,18 @@ unsigned bch2_sort_keys(struct bkey_packed *dst,
 	sort_iter_sort(iter, sort_keys_cmp);
 
 	while ((in = sort_iter_next(iter, sort_keys_cmp))) {
+		bool needs_whiteout = false;
+
 		if (bkey_whiteout(in) &&
 		    (filter_whiteouts || !in->needs_whiteout))
 			continue;
 
-		if (bkey_whiteout(in) &&
-		    (next = sort_iter_peek(iter)) &&
-		    !bkey_cmp_packed(iter->b, in, next)) {
+		while ((next = sort_iter_peek(iter)) &&
+		       !bkey_cmp_packed(iter->b, in, next)) {
 			BUG_ON(in->needs_whiteout &&
 			       next->needs_whiteout);
-			/*
-			 * XXX racy, called with read lock from write path
-			 *
-			 * leads to spurious BUG_ON() in bkey_unpack_key() in
-			 * debug mode
-			 */
-			next->needs_whiteout |= in->needs_whiteout;
-			continue;
+			needs_whiteout |= in->needs_whiteout;
+			in = sort_iter_next(iter, sort_keys_cmp);
 		}
 
 		if (bkey_whiteout(in)) {
@@ -279,6 +274,7 @@ unsigned bch2_sort_keys(struct bkey_packed *dst,
 		} else {
 			bkey_copy(out, in);
 		}
+		out->needs_whiteout |= needs_whiteout;
 		out = bkey_next(out);
 	}
 

fs/bcachefs/bset.h

@@ -199,12 +199,6 @@ __bkey_unpack_key_format_checked(const struct btree *b,
 		if (btree_keys_expensive_checks(b)) {
 			struct bkey dst2 = __bch2_bkey_unpack_key(&b->format, src);
 
-			/*
-			 * hack around a harmless race when compacting whiteouts
-			 * for a write:
-			 */
-			dst2.needs_whiteout = dst->needs_whiteout;
-
 			BUG_ON(memcmp(dst, &dst2, sizeof(*dst)));
 		}
 	}

fs/bcachefs/btree_iter.c

@@ -1339,12 +1339,6 @@ static inline struct bkey_s_c btree_iter_peek_uptodate(struct btree_iter *iter)
 		if (debug_check_iterators(iter->trans->c)) {
 			struct bkey k = bkey_unpack_key(l->b, _k);
 
-			/*
-			 * this flag is internal to the btree code,
-			 * we don't care if it doesn't match - if it's now set
-			 * it just means the key has been written out to disk:
-			 */
-			k.needs_whiteout = iter->k.needs_whiteout;
 			BUG_ON(memcmp(&k, &iter->k, sizeof(k)));
 		}