jbd2: Change j_state_lock to be a rwlock_t
Lockstat reports have shown that j_state_lock is a major source of
lock contention, especially on systems with more than 4 CPU cores. So
change it to be a read/write spinlock.
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
diff --git a/fs/jbd2/checkpoint.c b/fs/jbd2/checkpoint.c
index f8cdc02..1c23a0f 100644
--- a/fs/jbd2/checkpoint.c
+++ b/fs/jbd2/checkpoint.c
@@ -118,13 +118,13 @@
void __jbd2_log_wait_for_space(journal_t *journal)
{
int nblocks, space_left;
- assert_spin_locked(&journal->j_state_lock);
+ /* assert_spin_locked(&journal->j_state_lock); */
nblocks = jbd_space_needed(journal);
while (__jbd2_log_space_left(journal) < nblocks) {
if (journal->j_flags & JBD2_ABORT)
return;
- spin_unlock(&journal->j_state_lock);
+ write_unlock(&journal->j_state_lock);
mutex_lock(&journal->j_checkpoint_mutex);
/*
@@ -138,7 +138,7 @@
* filesystem, so abort the journal and leave a stack
* trace for forensic evidence.
*/
- spin_lock(&journal->j_state_lock);
+ write_lock(&journal->j_state_lock);
spin_lock(&journal->j_list_lock);
nblocks = jbd_space_needed(journal);
space_left = __jbd2_log_space_left(journal);
@@ -149,7 +149,7 @@
if (journal->j_committing_transaction)
tid = journal->j_committing_transaction->t_tid;
spin_unlock(&journal->j_list_lock);
- spin_unlock(&journal->j_state_lock);
+ write_unlock(&journal->j_state_lock);
if (chkpt) {
jbd2_log_do_checkpoint(journal);
} else if (jbd2_cleanup_journal_tail(journal) == 0) {
@@ -167,7 +167,7 @@
WARN_ON(1);
jbd2_journal_abort(journal, 0);
}
- spin_lock(&journal->j_state_lock);
+ write_lock(&journal->j_state_lock);
} else {
spin_unlock(&journal->j_list_lock);
}
@@ -474,7 +474,7 @@
* next transaction ID we will write, and where it will
* start. */
- spin_lock(&journal->j_state_lock);
+ write_lock(&journal->j_state_lock);
spin_lock(&journal->j_list_lock);
transaction = journal->j_checkpoint_transactions;
if (transaction) {
@@ -496,7 +496,7 @@
/* If the oldest pinned transaction is at the tail of the log
already then there's not much we can do right now. */
if (journal->j_tail_sequence == first_tid) {
- spin_unlock(&journal->j_state_lock);
+ write_unlock(&journal->j_state_lock);
return 1;
}
@@ -516,7 +516,7 @@
journal->j_free += freed;
journal->j_tail_sequence = first_tid;
journal->j_tail = blocknr;
- spin_unlock(&journal->j_state_lock);
+ write_unlock(&journal->j_state_lock);
/*
* If there is an external journal, we need to make sure that