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, 2 insertions, 2 deletions

diff --git a/fs/bcachefs/reflink.c b/fs/bcachefs/reflink.c
index 2827d0ef1019..8e66e6390e62 100644
--- a/fs/bcachefs/reflink.c
+++ b/fs/bcachefs/reflink.c
@@ -131,7 +131,7 @@ static int bch2_make_extent_indirect(struct btree_trans *trans,
 	if (orig->k.type == KEY_TYPE_inline_data)
 		bch2_check_set_feature(c, BCH_FEATURE_reflink_inline_data);
 
-	for_each_btree_key(trans, reflink_iter, BTREE_ID_reflink,
+	for_each_btree_key_norestart(trans, reflink_iter, BTREE_ID_reflink,
 			   POS(0, c->reflink_hint),
 			   BTREE_ITER_INTENT|BTREE_ITER_SLOTS, k, ret) {
 		if (reflink_iter.pos.inode) {
@@ -194,7 +194,7 @@ static struct bkey_s_c get_next_src(struct btree_iter *iter, struct bpos end)
 	struct bkey_s_c k;
 	int ret;
 
-	for_each_btree_key_continue(*iter, 0, k, ret) {
+	for_each_btree_key_continue_norestart(*iter, 0, k, ret) {
 		if (bkey_cmp(iter->pos, end) >= 0)
 			break;