jbd2: wake up journal waiters in FIFO order, not LIFO

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>

diff --git a/fs/jbd2/commit.c b/fs/jbd2/commit.c
index 6b51d2dc56e25446d90ae74b3d512f7bd3f14fa2..885a7a6cc53e6df5315adfa6419a11e0c4ce536f 100644 (file)
--- a/fs/jbd2/commit.c
+++ b/fs/jbd2/commit.c
@@ -568,7 +568,7 @@ void jbd2_journal_commit_transaction(journal_t *journal)
        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);
 
        jbd2_debug(3, "JBD2: commit phase 2a\n");

diff --git a/fs/jbd2/transaction.c b/fs/jbd2/transaction.c
index e1be93ccd81cb43d259b5265ce88b473a7220aee..6a404ac1c178f03652d7c8f8acc1b1191441c9b3 100644 (file)
--- a/fs/jbd2/transaction.c
+++ b/fs/jbd2/transaction.c
@@ -168,7 +168,7 @@ static void wait_transaction_locked(journal_t *journal)
        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(journal_t *journal)
                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 (journal_t *journal)
        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)