bcachefs: Start using bpos.snapshot field

This patch starts treating the bpos.snapshot field like part of the key
in the btree code:

* bpos_successor() and bpos_predecessor() now include the snapshot field
* Keys in btrees that will be using snapshots (extents, inodes, dirents
  and xattrs) now always have their snapshot field set to U32_MAX

The btree iterator code gets a new flag, BTREE_ITER_ALL_SNAPSHOTS, that
determines whether we're iterating over keys in all snapshots or not -
internally, this controlls whether bkey_(successor|predecessor)
increment/decrement the snapshot field, or only the higher bits of the
key.

We add a new member to struct btree_iter, iter->snapshot: when
BTREE_ITER_ALL_SNAPSHOTS is not set, iter->pos.snapshot should always
equal iter->snapshot, which will be 0 for btrees that don't use
snapshots, and alsways U32_MAX for btrees that will use snapshots
(until we enable snapshot creation).

This patch also introduces a new metadata version number, and compat
code for reading from/writing to older versions - this isn't a forced
upgrade (yet).

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

1 files changed, 11 insertions, 3 deletions

diff --git a/fs/bcachefs/btree_update_leaf.c b/fs/bcachefs/btree_update_leaf.c
index a32c8f34039c..88da89e8b170 100644
--- a/fs/bcachefs/btree_update_leaf.c
+++ b/fs/bcachefs/btree_update_leaf.c
@@ -223,9 +223,17 @@ static inline void btree_insert_entry_checks(struct btree_trans *trans,
 {
 	struct bch_fs *c = trans->c;
 
-	BUG_ON(bch2_debug_check_bkeys &&
-	       bch2_bkey_invalid(c, bkey_i_to_s_c(i->k), i->bkey_type));
-	BUG_ON(bpos_cmp(i->k->k.p, i->iter->real_pos));
+	if (bch2_debug_check_bkeys) {
+		const char *invalid = bch2_bkey_invalid(c,
+				bkey_i_to_s_c(i->k), i->bkey_type);
+		if (invalid) {
+			char buf[200];
+
+			bch2_bkey_val_to_text(&PBUF(buf), c, bkey_i_to_s_c(i->k));
+			panic("invalid bkey %s on insert: %s\n", buf, invalid);
+		}
+	}
+	BUG_ON(!i->is_extent && bpos_cmp(i->k->k.p, i->iter->real_pos));
 	BUG_ON(i->level		!= i->iter->level);
 	BUG_ON(i->btree_id	!= i->iter->btree_id);
 }