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bcachefs: btree_iter->should_be_locked

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Add a field to struct btree_iter for tracking whether it should be
locked - this fixes spurious transaction restarts in
bch2_trans_relock().

Signed-off-by: Kent Overstreet <kent.overstreet@gmail.com>
This commit is contained in:
Kent Overstreet 2021-06-04 17:17:45 -04:00 committed by Kent Overstreet
parent 531a0095c9
commit 66a0a49750
3 changed files with 34 additions and 3 deletions
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28
fs/bcachefs/btree_iter.c
View File

@ -463,12 +463,20 @@ void bch2_trans_downgrade(struct btree_trans *trans)
/* Btree transaction locking: */
static inline bool btree_iter_should_be_locked(struct btree_trans *trans,
struct btree_iter *iter)
{
return (iter->flags & BTREE_ITER_KEEP_UNTIL_COMMIT) ||
iter->should_be_locked;
}
bool bch2_trans_relock(struct btree_trans *trans)
{
struct btree_iter *iter;
trans_for_each_iter(trans, iter)
if (!bch2_btree_iter_relock(iter, _RET_IP_)) {
if (!bch2_btree_iter_relock(iter, _RET_IP_) &&
btree_iter_should_be_locked(trans, iter)) {
trace_trans_restart_relock(trans->ip, _RET_IP_,
iter->btree_id, &iter->real_pos);
return false;
@ -1427,9 +1435,16 @@ btree_iter_traverse(struct btree_iter *iter)
int __must_check
bch2_btree_iter_traverse(struct btree_iter *iter)
{
int ret;
btree_iter_set_search_pos(iter, btree_iter_search_key(iter));
return btree_iter_traverse(iter);
ret = btree_iter_traverse(iter);
if (ret)
return ret;
iter->should_be_locked = true;
return 0;
}
/* Iterate across nodes (leaf and interior nodes) */
@ -1455,6 +1470,7 @@ struct btree *bch2_btree_iter_peek_node(struct btree_iter *iter)
iter->pos = iter->real_pos = b->key.k.p;
bch2_btree_iter_verify(iter);
iter->should_be_locked = true;
return b;
}
@ -1511,6 +1527,7 @@ struct btree *bch2_btree_iter_next_node(struct btree_iter *iter)
iter->pos = iter->real_pos = b->key.k.p;
bch2_btree_iter_verify(iter);
iter->should_be_locked = true;
return b;
}
@ -1527,6 +1544,7 @@ static void btree_iter_set_search_pos(struct btree_iter *iter, struct bpos new_p
goto out;
iter->real_pos = new_pos;
iter->should_be_locked = false;
if (unlikely(btree_iter_type(iter) == BTREE_ITER_CACHED)) {
btree_node_unlock(iter, 0);
@ -1686,6 +1704,7 @@ start:
bch2_btree_iter_verify_entry_exit(iter);
bch2_btree_iter_verify(iter);
iter->should_be_locked = true;
return k;
}
@ -1770,6 +1789,7 @@ struct bkey_s_c bch2_btree_iter_peek_prev(struct btree_iter *iter)
out:
bch2_btree_iter_verify_entry_exit(iter);
bch2_btree_iter_verify(iter);
iter->should_be_locked = true;
return k;
no_key:
/*
@ -1869,6 +1889,8 @@ struct bkey_s_c bch2_btree_iter_peek_slot(struct btree_iter *iter)
bch2_btree_iter_verify_entry_exit(iter);
bch2_btree_iter_verify(iter);
iter->should_be_locked = true;
return k;
}
@ -1906,6 +1928,8 @@ struct bkey_s_c bch2_btree_iter_peek_cached(struct btree_iter *iter)
bkey_cmp(iter->pos, ck->key.pos));
BUG_ON(!ck->valid);
iter->should_be_locked = true;
return bkey_i_to_s_c(ck->k);
}

1
fs/bcachefs/btree_iter.h
View File

@ -178,6 +178,7 @@ static inline void bch2_btree_iter_set_pos(struct btree_iter *iter, struct bpos
iter->k.p.offset = iter->pos.offset = new_pos.offset;
iter->k.p.snapshot = iter->pos.snapshot = new_pos.snapshot;
iter->k.size = 0;
iter->should_be_locked = false;
}
/* Sort order for locking btree iterators: */

8
fs/bcachefs/btree_types.h
View File

@ -252,7 +252,13 @@ struct btree_iter {
u8 idx;
enum btree_id btree_id:4;
enum btree_iter_uptodate uptodate:4;
enum btree_iter_uptodate uptodate:3;
/*
* True if we've returned a key (and thus are expected to keep it
* locked), false after set_pos - for avoiding spurious transaction
* restarts in bch2_trans_relock():
*/
bool should_be_locked:1;
unsigned level:4,
min_depth:4,
locks_want:4,