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/ext4/super.c b/fs/ext4/super.c
index 3fd65eb..81cb3fc 100644
--- a/fs/ext4/super.c
+++ b/fs/ext4/super.c
@@ -3232,7 +3232,7 @@
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 @@
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,