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Date:   Tue,  5 Nov 2019 17:44:22 +0100
From:   Jan Kara <jack@...e.cz>
To:     Ted Tso <tytso@....edu>
Cc:     <linux-ext4@...r.kernel.org>, Jan Kara <jack@...e.cz>
Subject: [PATCH 16/25] jbd2: Drop pointless wakeup from jbd2_journal_stop()

When we drop last handle from a transaction and journal->j_barrier_count
> 0, jbd2_journal_stop() wakes up journal->j_wait_transaction_locked
wait queue. This looks pointless - wait for outstanding handles always
happens on journal->j_wait_updates waitqueue.
journal->j_wait_transaction_locked is used to wait for transaction state
changes and by start_this_handle() for waiting until
journal->j_barrier_count drops to 0. The first case is clearly
irrelevant here since only jbd2 thread changes transaction state. The
second case looks related but jbd2_journal_unlock_updates() is
responsible for the wakeup in this case. So just drop the wakeup.

Reviewed-by: Theodore Ts'o <tytso@....edu>
Signed-off-by: Jan Kara <jack@...e.cz>
---
 fs/jbd2/transaction.c | 5 +----
 1 file changed, 1 insertion(+), 4 deletions(-)

diff --git a/fs/jbd2/transaction.c b/fs/jbd2/transaction.c
index a160c3f665f9..d648cec3f90f 100644
--- a/fs/jbd2/transaction.c
+++ b/fs/jbd2/transaction.c
@@ -1831,11 +1831,8 @@ int jbd2_journal_stop(handle_t *handle)
 	 * once we do this, we must not dereference transaction
 	 * pointer again.
 	 */
-	if (atomic_dec_and_test(&transaction->t_updates)) {
+	if (atomic_dec_and_test(&transaction->t_updates))
 		wake_up(&journal->j_wait_updates);
-		if (journal->j_barrier_count)
-			wake_up(&journal->j_wait_transaction_locked);
-	}
 
 	rwsem_release(&journal->j_trans_commit_map, 1, _THIS_IP_);
 
-- 
2.16.4

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