bcachefs: Fix restart handling in for_each_btree_key()

Code that uses for_each_btree_key often wants transaction restarts to be
handled locally and not returned. Originally, we wouldn't return
transaction restarts if there was a single iterator in the transaction -
the reasoning being if there weren't other iterators being invalidated,
and the current iterator was being advanced/retraversed, there weren't
any locks or iterators we were required to preserve.

But with the btree_path conversion that approach doesn't work anymore -
even when we're using for_each_btree_key() with a single iterator there
will still be two paths in the transaction, since we now always preserve
the path at the pos the iterator was initialized at - the reason being
that on restart we often restart from the same place.

And it turns out there's now a lot of for_each_btree_key() uses that _do
not_ want transaction restarts handled locally, and should be returning
them.

This patch splits out for_each_btree_key_norestart() and
for_each_btree_key_continue_norestart(), and converts existing users as
appropriate. for_each_btree_key(), for_each_btree_key_continue(), and
for_each_btree_node() now handle transaction restarts themselves by
calling bch2_trans_begin() when necessary - and the old hack to not
return transaction restarts when there's a single path in the
transaction has been deleted.

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

1 files changed, 1 insertions, 1 deletions

diff --git a/fs/bcachefs/io.c b/fs/bcachefs/io.c
index ea2adcc213d0..772fdeb722c7 100644
--- a/fs/bcachefs/io.c
+++ b/fs/bcachefs/io.c
@@ -216,7 +216,7 @@ int bch2_sum_sector_overwrites(struct btree_trans *trans,
 
 	bch2_trans_copy_iter(&iter, extent_iter);
 
-	for_each_btree_key_continue(iter, BTREE_ITER_SLOTS, old, ret) {
+	for_each_btree_key_continue_norestart(iter, BTREE_ITER_SLOTS, old, ret) {
 		s64 sectors = min(new->k.p.offset, old.k->p.offset) -
 			max(bkey_start_offset(&new->k),
 			    bkey_start_offset(old.k));