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, 13 insertions, 13 deletions

diff --git a/fs/jbd2/commit.c b/fs/jbd2/commit.c
index fbd2c564e916..67bb0a2f35e5 100644
--- a/fs/jbd2/commit.c
+++ b/fs/jbd2/commit.c
@@ -152,9 +152,9 @@ static int journal_submit_commit_record(journal_t *journal,
                 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 @@ retry:
                 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 @@ void jbd2_journal_commit_transaction(journal_t *journal)
         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 @@ void jbd2_journal_commit_transaction(journal_t *journal)
                                         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 @@ void jbd2_journal_commit_transaction(journal_t *journal)
         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 @@ void jbd2_journal_commit_transaction(journal_t *journal)
          * 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 @@ restart_loop:
          * __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 @@ restart_loop:
          */
         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 @@ restart_loop:
                                 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) {