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bcachefs: Tighten up btree_iter locking assertions

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We weren't correctly verifying that we had interior node intent locks -
this patch also fixes bugs uncovered by the new assertions.

Signed-off-by: Kent Overstreet <kent.overstreet@gmail.com>
This commit is contained in:
Kent Overstreet 2021-07-14 15:13:27 -04:00 committed by Kent Overstreet
parent 5468f1195d
commit 5aab663534
4 changed files with 36 additions and 19 deletions
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8
fs/bcachefs/btree_cache.c
View File

@ -698,7 +698,9 @@ static noinline struct btree *bch2_btree_node_fill(struct bch_fs *c,
* currently fails for iterators that aren't pointed at a valid btree
* node
*/
if (iter && !bch2_trans_relock(iter->trans))
if (iter &&
(!bch2_trans_relock(iter->trans) ||
!bch2_btree_iter_relock(iter, _THIS_IP_)))
return ERR_PTR(-EINTR);
if (!six_relock_type(&b->c.lock, lock_type, seq))
@ -858,7 +860,9 @@ lock_node:
* currently fails for iterators that aren't pointed at a valid
* btree node
*/
if (iter && !bch2_trans_relock(iter->trans))
if (iter &&
(!bch2_trans_relock(iter->trans) ||
!bch2_btree_iter_relock(iter, _THIS_IP_)))
return ERR_PTR(-EINTR);
if (!six_relock_type(&b->c.lock, lock_type, seq))

41
fs/bcachefs/btree_iter.c
View File

@ -361,7 +361,7 @@ static void bch2_btree_iter_verify_locks(struct btree_iter *iter)
return;
}
for (l = 0; is_btree_node(iter, l); l++) {
for (l = 0; btree_iter_node(iter, l); l++) {
if (iter->uptodate >= BTREE_ITER_NEED_RELOCK &&
!btree_node_locked(iter, l))
continue;
@ -383,7 +383,7 @@ static inline void bch2_btree_iter_verify_locks(struct btree_iter *iter) {}
#endif
__flatten
static bool bch2_btree_iter_relock(struct btree_iter *iter, unsigned long trace_ip)
bool bch2_btree_iter_relock(struct btree_iter *iter, unsigned long trace_ip)
{
return btree_iter_get_locks(iter, false, trace_ip);
}
@ -607,6 +607,8 @@ err:
static void bch2_btree_iter_verify(struct btree_iter *iter)
{
struct btree_trans *trans = iter->trans;
struct bch_fs *c = trans->c;
enum btree_iter_type type = btree_iter_type(iter);
unsigned i;
@ -625,10 +627,16 @@ static void bch2_btree_iter_verify(struct btree_iter *iter)
(iter->flags & BTREE_ITER_ALL_SNAPSHOTS) &&
!btree_type_has_snapshots(iter->btree_id));
bch2_btree_iter_verify_locks(iter);
for (i = 0; i < (type != BTREE_ITER_CACHED ? BTREE_MAX_DEPTH : 1); i++) {
if (!iter->l[i].b) {
BUG_ON(c->btree_roots[iter->btree_id].b->c.level > i);
break;
}
for (i = 0; i < BTREE_MAX_DEPTH; i++)
bch2_btree_iter_verify_level(iter, i);
}
bch2_btree_iter_verify_locks(iter);
}
static void bch2_btree_iter_verify_entry_exit(struct btree_iter *iter)
@ -1350,30 +1358,30 @@ static inline unsigned btree_iter_up_until_good_node(struct btree_iter *iter,
static int btree_iter_traverse_one(struct btree_iter *iter,
unsigned long trace_ip)
{
unsigned depth_want = iter->level;
unsigned l, depth_want = iter->level;
int ret = 0;
/*
* if we need interior nodes locked, call btree_iter_relock() to make
* sure we walk back up enough that we lock them:
*/
if (iter->uptodate == BTREE_ITER_NEED_RELOCK ||
iter->locks_want > 1)
bch2_btree_iter_relock(iter, _THIS_IP_);
if (btree_iter_type(iter) == BTREE_ITER_CACHED) {
ret = bch2_btree_iter_traverse_cached(iter);
goto out;
}
if (iter->uptodate < BTREE_ITER_NEED_RELOCK)
goto out;
if (unlikely(iter->level >= BTREE_MAX_DEPTH))
goto out;
iter->level = btree_iter_up_until_good_node(iter, 0);
/* If we need intent locks, take them too: */
for (l = iter->level + 1;
l < iter->locks_want && btree_iter_node(iter, l);
l++)
if (!bch2_btree_node_relock(iter, l))
while (iter->level <= l) {
btree_node_unlock(iter, iter->level);
iter->l[iter->level].b = BTREE_ITER_NO_NODE_UP;
iter->level++;
}
/*
* Note: iter->nodes[iter->level] may be temporarily NULL here - that
* would indicate to other code that we got to the end of the btree,
@ -1394,6 +1402,7 @@ static int btree_iter_traverse_one(struct btree_iter *iter,
goto out;
}
__bch2_btree_iter_unlock(iter);
iter->level = depth_want;
if (ret == -EIO) {

2
fs/bcachefs/btree_iter.h
View File

@ -111,6 +111,8 @@ void bch2_btree_node_iter_fix(struct btree_iter *, struct btree *,
struct btree_node_iter *, struct bkey_packed *,
unsigned, unsigned);
bool bch2_btree_iter_relock(struct btree_iter *, unsigned long);
bool bch2_trans_relock(struct btree_trans *);
void bch2_trans_unlock(struct btree_trans *);

4
fs/bcachefs/btree_key_cache.c
View File

@ -271,7 +271,9 @@ int bch2_btree_iter_traverse_cached(struct btree_iter *iter)
BUG_ON(iter->level);
if (btree_node_locked(iter, 0)) {
iter->l[1].b = NULL;
if (bch2_btree_node_relock(iter, 0)) {
ck = (void *) iter->l[0].b;
goto fill;
}