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/include/linux/jbd2.h b/include/linux/jbd2.h
index a72ce21..15d5743 100644
--- a/include/linux/jbd2.h
+++ b/include/linux/jbd2.h
@@ -764,7 +764,7 @@
/*
* Protect the various scalars in the journal
*/
- spinlock_t j_state_lock;
+ rwlock_t j_state_lock;
/*
* Number of processes waiting to create a barrier lock [j_state_lock]