[PATCHv1 2/2] jbd2: Remove CONFIG_JBD2_DEBUG to update t_max_wait

From: Ritesh Harjani
Date: Sun Jan 23 2022 - 12:24:07 EST


CONFIG_JBD2_DEBUG and jbd2_journal_enable_debug knobs were added in
update_t_max_wait(), since earlier it used to take a spinlock for updating
t_max_wait, which could cause a bottleneck while starting a txn
(start_this_handle()).
Since in previous patch, we have killed t_handle_lock completely, we
could get rid of this debug config and knob to let t_max_wait be updated
by default again.

Signed-off-by: Ritesh Harjani <riteshh@xxxxxxxxxxxxx>
---
fs/jbd2/transaction.c | 7 +++----
1 file changed, 3 insertions(+), 4 deletions(-)

diff --git a/fs/jbd2/transaction.c b/fs/jbd2/transaction.c
index 68dd7de49aff..77634e2e118e 100644
--- a/fs/jbd2/transaction.c
+++ b/fs/jbd2/transaction.c
@@ -141,20 +141,19 @@ static void jbd2_get_transaction(journal_t *journal,
* t_max_wait is carefully updated here with use of atomic compare exchange.
* Note that there could be multiplre threads trying to do this simultaneously
* hence using cmpxchg to avoid any use of locks in this case.
+ * With this t_max_wait can be updated w/o enabling jbd2_journal_enable_debug.
*/
static inline void update_t_max_wait(transaction_t *transaction,
unsigned long ts)
{
-#ifdef CONFIG_JBD2_DEBUG
unsigned long oldts, newts;
- if (jbd2_journal_enable_debug &&
- time_after(transaction->t_start, ts)) {
+
+ if (time_after(transaction->t_start, ts)) {
newts = jbd2_time_diff(ts, transaction->t_start);
oldts = READ_ONCE(transaction->t_max_wait);
while (oldts < newts)
oldts = cmpxchg(&transaction->t_max_wait, oldts, newts);
}
-#endif
}

/*
--
2.31.1