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bcachefs: Fix spurious transaction restarts

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The checks for lock ordering violations weren't quite right.

Signed-off-by: Kent Overstreet <kent.overstreet@gmail.com>
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
This commit is contained in:
Kent Overstreet 2020-11-05 20:49:08 -05:00 committed by Kent Overstreet
parent 1a21bf9866
commit 7e7ae6ca57
2 changed files with 26 additions and 15 deletions
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39
fs/bcachefs/btree_iter.c
View file

@ -238,14 +238,32 @@ bool __bch2_btree_node_lock(struct btree *b, struct bpos pos,
}
}
if (linked->btree_id != iter->btree_id) {
if (linked->btree_id > iter->btree_id) {
deadlock_iter = linked;
reason = 3;
}
continue;
}
/*
* Within the same btree, cached iterators come before non
* cached iterators:
*/
if (btree_iter_is_cached(linked) != btree_iter_is_cached(iter)) {
if (btree_iter_is_cached(iter)) {
deadlock_iter = linked;
reason = 4;
}
continue;
}
/*
* Interior nodes must be locked before their descendants: if
* another iterator has possible descendants locked of the node
* we're about to lock, it must have the ancestors locked too:
*/
if (linked->btree_id == iter->btree_id &&
btree_iter_is_cached(linked) == btree_iter_is_cached(iter) &&
level > __fls(linked->nodes_locked)) {
if (level > __fls(linked->nodes_locked)) {
if (!(trans->nounlock)) {
linked->locks_want =
max(level + 1, max_t(unsigned,
@ -253,27 +271,20 @@ bool __bch2_btree_node_lock(struct btree *b, struct bpos pos,
iter->locks_want));
if (!btree_iter_get_locks(linked, true, false)) {
deadlock_iter = linked;
reason = 3;
reason = 5;
}
} else {
deadlock_iter = linked;
reason = 4;
reason = 6;
}
}
/* Must lock btree nodes in key order: */
if ((cmp_int(iter->btree_id, linked->btree_id) ?:
-cmp_int(btree_iter_type(iter), btree_iter_type(linked))) < 0) {
deadlock_iter = linked;
reason = 5;
}
if (iter->btree_id == linked->btree_id &&
btree_node_locked(linked, level) &&
if (btree_node_locked(linked, level) &&
bkey_cmp(pos, btree_node_pos((void *) linked->l[level].b,
btree_iter_type(linked))) <= 0) {
deadlock_iter = linked;
reason = 6;
reason = 7;
}
/*

2
fs/bcachefs/btree_iter.h
View file

@ -182,7 +182,7 @@ static inline int btree_iter_lock_cmp(const struct btree_iter *l,
const struct btree_iter *r)
{
return cmp_int(l->btree_id, r->btree_id) ?:
-cmp_int(btree_iter_type(l), btree_iter_type(r)) ?:
-cmp_int(btree_iter_is_cached(l), btree_iter_is_cached(r)) ?:
bkey_cmp(l->pos, r->pos);
}