[PATCH 5.19 118/717] jbd2: wake up journal waiters in FIFO order, not LIFO

Greg Kroah-Hartman
2022-10-22T10:48:08Z

From: Andrew Perepechko <anserper@ya.ru>

commit 34fc8768ec6089565d6d73bad26724083cecf7bd upstream.

LIFO wakeup order is unfair and sometimes leads to a journal
user not being able to get a journal handle for hundreds of
transactions in a row.

FIFO wakeup can make things more fair.

Cc: stable@kernel.org
Signed-off-by: Alexey Lyashkov <alexey.lyashkov@gmail.com>
Reviewed-by: Ritesh Harjani (IBM) <ritesh.list@gmail.com>
Link: https://lore.kernel.org/r/20220907165959.1137482-1-alexey.lyashkov@gmail.com
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
fs/jbd2/commit.c | 2 +-
fs/jbd2/transaction.c | 6 +++---
2 files changed, 4 insertions(+), 4 deletions(-)

--- a/fs/jbd2/commit.c
+++ b/fs/jbd2/commit.c
@@ -570,7 +570,7 @@ void jbd2_journal_commit_transaction(jou
journal->j_running_transaction = NULL;
start_time = ktime_get();
commit_transaction->t_log_start = journal->j_head;
- wake_up(&journal->j_wait_transaction_locked);
+ wake_up_all(&journal->j_wait_transaction_locked);
write_unlock(&journal->j_state_lock);

jbd_debug(3, "JBD2: commit phase 2a\n");
--- a/fs/jbd2/transaction.c
+++ b/fs/jbd2/transaction.c
@@ -168,7 +168,7 @@ static void wait_transaction_locked(jour
int need_to_start;
tid_t tid = journal->j_running_transaction->t_tid;

- prepare_to_wait(&journal->j_wait_transaction_locked, &wait,
+ prepare_to_wait_exclusive(&journal->j_wait_transaction_locked, &wait,
TASK_UNINTERRUPTIBLE);
need_to_start = !tid_geq(journal->j_commit_request, tid);
read_unlock(&journal->j_state_lock);
@@ -194,7 +194,7 @@ static void wait_transaction_switching(j
read_unlock(&journal->j_state_lock);
return;
}
- prepare_to_wait(&journal->j_wait_transaction_locked, &wait,
+ prepare_to_wait_exclusive(&journal->j_wait_transaction_locked, &wait,
TASK_UNINTERRUPTIBLE);
read_unlock(&journal->j_state_lock);
/*
@@ -920,7 +920,7 @@ void jbd2_journal_unlock_updates (journa
write_lock(&journal->j_state_lock);
--journal->j_barrier_count;
write_unlock(&journal->j_state_lock);
- wake_up(&journal->j_wait_transaction_locked);
+ wake_up_all(&journal->j_wait_transaction_locked);
}

static void warn_dirty_buffer(struct buffer_head *bh)