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, 2 insertions, 2 deletions

diff --git a/fs/ext4/super.c b/fs/ext4/super.c
index 3fd65eb66ccd..81cb3fc1218e 100644
--- a/fs/ext4/super.c
+++ b/fs/ext4/super.c
@@ -3232,7 +3232,7 @@ static void ext4_init_journal_params(struct super_block *sb, journal_t *journal)
         journal->j_min_batch_time = sbi->s_min_batch_time;
         journal->j_max_batch_time = sbi->s_max_batch_time;
 
-        spin_lock(&journal->j_state_lock);
+        write_lock(&journal->j_state_lock);
         if (test_opt(sb, BARRIER))
                 journal->j_flags |= JBD2_BARRIER;
         else
@@ -3241,7 +3241,7 @@ static void ext4_init_journal_params(struct super_block *sb, journal_t *journal)
                 journal->j_flags |= JBD2_ABORT_ON_SYNCDATA_ERR;
         else
                 journal->j_flags &= ~JBD2_ABORT_ON_SYNCDATA_ERR;
-        spin_unlock(&journal->j_state_lock);
+        write_unlock(&journal->j_state_lock);
 }
 
 static journal_t *ext4_get_journal(struct super_block *sb,