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, 1 insertions, 1 deletions

diff --git a/fs/bcachefs/bset.c b/fs/bcachefs/bset.c
index 5746199dfafb..de4dc2fac1d6 100644
--- a/fs/bcachefs/bset.c
+++ b/fs/bcachefs/bset.c
@@ -1438,7 +1438,7 @@ static void btree_node_iter_init_pack_failed(struct btree_node_iter *iter,
  *    to the search key is going to have 0 sectors after the search key.
  *
  *    But this does mean that we can't just search for
- *    bkey_successor(start_of_range) to get the first extent that overlaps with
+ *    bpos_successor(start_of_range) to get the first extent that overlaps with
  *    the range we want - if we're unlucky and there's an extent that ends
  *    exactly where we searched, then there could be a deleted key at the same
  *    position and we'd get that when we search instead of the preceding extent