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>

1 files changed, 1 insertions, 1 deletions

diff --git a/include/linux/jbd2.h b/include/linux/jbd2.h
index a72ce21de0e1..15d5743ccfbb 100644
--- a/include/linux/jbd2.h
+++ b/include/linux/jbd2.h
@@ -764,7 +764,7 @@ struct journal_s
         /*
          * 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]