bcachefs: Update fsck for snapshots

This updates the fsck algorithms to handle snapshots - meaning there
will be multiple versions of the same key (extents, inodes, dirents,
xattrs) in different snapshots, and we have to carefully consider which
keys are visible in which snapshot.
Signed-off-by: Kent Overstreet <kent.overstreet@gmail.com>

fs/bcachefs/btree_update.h

@@ -61,7 +61,7 @@ int bch2_btree_insert(struct bch_fs *, enum btree_id, struct bkey_i *,
 		     struct disk_reservation *, u64 *, int flags);
 
 int bch2_btree_delete_range_trans(struct btree_trans *, enum btree_id,
-				  struct bpos, struct bpos, u64 *);
+				  struct bpos, struct bpos, unsigned, u64 *);
 int bch2_btree_delete_range(struct bch_fs *, enum btree_id,
 			    struct bpos, struct bpos, u64 *);
 

fs/bcachefs/btree_update_leaf.c

@@ -1204,13 +1204,14 @@ int bch2_btree_delete_at(struct btree_trans *trans,
 
 int bch2_btree_delete_range_trans(struct btree_trans *trans, enum btree_id id,
 				  struct bpos start, struct bpos end,
+				  unsigned iter_flags,
 				  u64 *journal_seq)
 {
 	struct btree_iter iter;
 	struct bkey_s_c k;
 	int ret = 0;
 
-	bch2_trans_iter_init(trans, &iter, id, start, BTREE_ITER_INTENT);
+	bch2_trans_iter_init(trans, &iter, id, start, BTREE_ITER_INTENT|iter_flags);
 retry:
 	while ((bch2_trans_begin(trans),
 	       (k = bch2_btree_iter_peek(&iter)).k) &&
@@ -1277,5 +1278,5 @@ int bch2_btree_delete_range(struct bch_fs *c, enum btree_id id,
 			    u64 *journal_seq)
 {
 	return bch2_trans_do(c, NULL, journal_seq, 0,
-			     bch2_btree_delete_range_trans(&trans, id, start, end, journal_seq));
+			     bch2_btree_delete_range_trans(&trans, id, start, end, 0, journal_seq));
 }