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bcachefs: CONFIG_BCACHEFS_INJECT_TRANSACTION_RESTARTS

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Incorrectly handled transaction restarts can be a source of heisenbugs;
add a mode where we randomly inject them to shake them out.

Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
This commit is contained in:
Kent Overstreet 2024-09-23 22:12:31 -04:00
parent 9f734cd076
commit 9cf6b84b71
5 changed files with 58 additions and 1 deletions
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7
fs/bcachefs/Kconfig
View file

@ -61,6 +61,13 @@ config BCACHEFS_DEBUG
The resulting code will be significantly slower than normal; you
probably shouldn't select this option unless you're a developer.
config BCACHEFS_INJECT_TRANSACTION_RESTARTS
bool "Randomly inject transaction restarts"
depends on BCACHEFS_DEBUG
help
Randomly inject transaction restarts in a few core paths - may have a
significant performance penalty
config BCACHEFS_TESTS
bool "bcachefs unit and performance tests"
depends on BCACHEFS_FS

33
fs/bcachefs/btree_iter.c
View file

@ -2357,6 +2357,12 @@ struct bkey_s_c bch2_btree_iter_peek_max(struct btree_iter *iter, struct bpos en
bch2_btree_iter_verify_entry_exit(iter);
EBUG_ON((iter->flags & BTREE_ITER_filter_snapshots) && bkey_eq(end, POS_MAX));
ret = trans_maybe_inject_restart(trans, _RET_IP_);
if (unlikely(ret)) {
k = bkey_s_c_err(ret);
goto out_no_locked;
}
if (iter->update_path) {
bch2_path_put_nokeep(trans, iter->update_path,
iter->flags & BTREE_ITER_intent);
@ -2622,6 +2628,12 @@ struct bkey_s_c bch2_btree_iter_peek_prev_min(struct btree_iter *iter, struct bp
bch2_btree_iter_verify_entry_exit(iter);
EBUG_ON((iter->flags & BTREE_ITER_filter_snapshots) && bpos_eq(end, POS_MIN));
int ret = trans_maybe_inject_restart(trans, _RET_IP_);
if (unlikely(ret)) {
k = bkey_s_c_err(ret);
goto out_no_locked;
}
while (1) {
k = __bch2_btree_iter_peek_prev(iter, search_key);
if (unlikely(!k.k))
@ -2749,6 +2761,12 @@ struct bkey_s_c bch2_btree_iter_peek_slot(struct btree_iter *iter)
bch2_btree_iter_verify_entry_exit(iter);
EBUG_ON(btree_iter_path(trans, iter)->level && (iter->flags & BTREE_ITER_with_key_cache));
ret = trans_maybe_inject_restart(trans, _RET_IP_);
if (unlikely(ret)) {
k = bkey_s_c_err(ret);
goto out_no_locked;
}
/* extents can't span inode numbers: */
if ((iter->flags & BTREE_ITER_is_extents) &&
unlikely(iter->pos.offset == KEY_OFFSET_MAX)) {
@ -3106,6 +3124,10 @@ void *__bch2_trans_kmalloc(struct btree_trans *trans, size_t size)
WARN_ON_ONCE(new_bytes > BTREE_TRANS_MEM_MAX);
ret = trans_maybe_inject_restart(trans, _RET_IP_);
if (ret)
return ERR_PTR(ret);
struct btree_transaction_stats *s = btree_trans_stats(trans);
s->max_mem = max(s->max_mem, new_bytes);
@ -3163,7 +3185,8 @@ out_new_mem:
if (old_bytes) {
trace_and_count(c, trans_restart_mem_realloced, trans, _RET_IP_, new_bytes);
return ERR_PTR(btree_trans_restart(trans, BCH_ERR_transaction_restart_mem_realloced));
return ERR_PTR(btree_trans_restart_ip(trans,
BCH_ERR_transaction_restart_mem_realloced, _RET_IP_));
}
out_change_top:
p = trans->mem + trans->mem_top;
@ -3271,6 +3294,14 @@ u32 bch2_trans_begin(struct btree_trans *trans)
trans->last_begin_ip = _RET_IP_;
#ifdef CONFIG_BCACHEFS_INJECT_TRANSACTION_RESTARTS
if (trans->restarted) {
trans->restart_count_this_trans++;
} else {
trans->restart_count_this_trans = 0;
}
#endif
trans_set_locked(trans, false);
if (trans->restarted) {

12
fs/bcachefs/btree_iter.h
View file

@ -355,6 +355,18 @@ static int btree_trans_restart(struct btree_trans *trans, int err)
return btree_trans_restart_ip(trans, err, _THIS_IP_);
}
static inline int trans_maybe_inject_restart(struct btree_trans *trans, unsigned long ip)
{
#ifdef CONFIG_BCACHEFS_INJECT_TRANSACTION_RESTARTS
if (!(ktime_get_ns() & ~(~0ULL << min(63, (10 + trans->restart_count_this_trans))))) {
trace_and_count(trans->c, trans_restart_injected, trans, ip);
return btree_trans_restart_ip(trans,
BCH_ERR_transaction_restart_fault_inject, ip);
}
#endif
return 0;
}
bool bch2_btree_node_upgrade(struct btree_trans *,
struct btree_path *, unsigned);

4
fs/bcachefs/btree_trans_commit.c
View file

@ -999,6 +999,10 @@ int __bch2_trans_commit(struct btree_trans *trans, unsigned flags)
bch2_trans_verify_not_unlocked_or_in_restart(trans);
ret = trans_maybe_inject_restart(trans, _RET_IP_);
if (unlikely(ret))
goto out_reset;
if (!trans->nr_updates &&
!trans->journal_entries_u64s)
goto out_reset;

3
fs/bcachefs/btree_types.h
View file

@ -509,6 +509,9 @@ struct btree_trans {
bool notrace_relock_fail:1;
enum bch_errcode restarted:16;
u32 restart_count;
#ifdef CONFIG_BCACHEFS_INJECT_TRANSACTION_RESTARTS
u32 restart_count_this_trans;
#endif
u64 last_begin_time;
unsigned long last_begin_ip;