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/commit.c b/fs/jbd2/commit.c
index fbd2c56..67bb0a2 100644
--- a/fs/jbd2/commit.c
+++ b/fs/jbd2/commit.c
@@ -152,9 +152,9 @@
printk(KERN_WARNING
"JBD2: Disabling barriers on %s, "
"not supported by device\n", journal->j_devname);
- spin_lock(&journal->j_state_lock);
+ write_lock(&journal->j_state_lock);
journal->j_flags &= ~JBD2_BARRIER;
- spin_unlock(&journal->j_state_lock);
+ write_unlock(&journal->j_state_lock);
/* And try again, without the barrier */
lock_buffer(bh);
@@ -182,9 +182,9 @@
printk(KERN_WARNING
"JBD2: %s: disabling barries on %s - not supported "
"by device\n", __func__, journal->j_devname);
- spin_lock(&journal->j_state_lock);
+ write_lock(&journal->j_state_lock);
journal->j_flags &= ~JBD2_BARRIER;
- spin_unlock(&journal->j_state_lock);
+ write_unlock(&journal->j_state_lock);
lock_buffer(bh);
clear_buffer_dirty(bh);
@@ -400,7 +400,7 @@
jbd_debug(1, "JBD: starting commit of transaction %d\n",
commit_transaction->t_tid);
- spin_lock(&journal->j_state_lock);
+ write_lock(&journal->j_state_lock);
commit_transaction->t_state = T_LOCKED;
/*
@@ -424,9 +424,9 @@
TASK_UNINTERRUPTIBLE);
if (atomic_read(&commit_transaction->t_updates)) {
spin_unlock(&commit_transaction->t_handle_lock);
- spin_unlock(&journal->j_state_lock);
+ write_unlock(&journal->j_state_lock);
schedule();
- spin_lock(&journal->j_state_lock);
+ write_lock(&journal->j_state_lock);
spin_lock(&commit_transaction->t_handle_lock);
}
finish_wait(&journal->j_wait_updates, &wait);
@@ -497,7 +497,7 @@
start_time = ktime_get();
commit_transaction->t_log_start = journal->j_head;
wake_up(&journal->j_wait_transaction_locked);
- spin_unlock(&journal->j_state_lock);
+ write_unlock(&journal->j_state_lock);
jbd_debug (3, "JBD: commit phase 2\n");
@@ -519,9 +519,9 @@
* transaction! Now comes the tricky part: we need to write out
* metadata. Loop over the transaction's entire buffer list:
*/
- spin_lock(&journal->j_state_lock);
+ write_lock(&journal->j_state_lock);
commit_transaction->t_state = T_COMMIT;
- spin_unlock(&journal->j_state_lock);
+ write_unlock(&journal->j_state_lock);
trace_jbd2_commit_logging(journal, commit_transaction);
stats.run.rs_logging = jiffies;
@@ -978,7 +978,7 @@
* __jbd2_journal_drop_transaction(). Otherwise we could race with
* other checkpointing code processing the transaction...
*/
- spin_lock(&journal->j_state_lock);
+ write_lock(&journal->j_state_lock);
spin_lock(&journal->j_list_lock);
/*
* Now recheck if some buffers did not get attached to the transaction
@@ -986,7 +986,7 @@
*/
if (commit_transaction->t_forget) {
spin_unlock(&journal->j_list_lock);
- spin_unlock(&journal->j_state_lock);
+ write_unlock(&journal->j_state_lock);
goto restart_loop;
}
@@ -1038,7 +1038,7 @@
journal->j_average_commit_time*3) / 4;
else
journal->j_average_commit_time = commit_time;
- spin_unlock(&journal->j_state_lock);
+ write_unlock(&journal->j_state_lock);
if (commit_transaction->t_checkpoint_list == NULL &&
commit_transaction->t_checkpoint_io_list == NULL) {