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, 8 insertions, 8 deletions

diff --git a/fs/jbd2/checkpoint.c b/fs/jbd2/checkpoint.c
index f8cdc02520f9..1c23a0f4e8a3 100644
--- a/fs/jbd2/checkpoint.c
+++ b/fs/jbd2/checkpoint.c
@@ -118,13 +118,13 @@ static int __try_to_free_cp_buf(struct journal_head *jh)
 void __jbd2_log_wait_for_space(journal_t *journal)
 {
         int nblocks, space_left;
-        assert_spin_locked(&journal->j_state_lock);
+        /* assert_spin_locked(&journal->j_state_lock); */
 
         nblocks = jbd_space_needed(journal);
         while (__jbd2_log_space_left(journal) < nblocks) {
                 if (journal->j_flags & JBD2_ABORT)
                         return;
-                spin_unlock(&journal->j_state_lock);
+                write_unlock(&journal->j_state_lock);
                 mutex_lock(&journal->j_checkpoint_mutex);
 
                 /*
@@ -138,7 +138,7 @@ void __jbd2_log_wait_for_space(journal_t *journal)
                  * filesystem, so abort the journal and leave a stack
                  * trace for forensic evidence.
                  */
-                spin_lock(&journal->j_state_lock);
+                write_lock(&journal->j_state_lock);
                 spin_lock(&journal->j_list_lock);
                 nblocks = jbd_space_needed(journal);
                 space_left = __jbd2_log_space_left(journal);
@@ -149,7 +149,7 @@ void __jbd2_log_wait_for_space(journal_t *journal)
                         if (journal->j_committing_transaction)
                                 tid = journal->j_committing_transaction->t_tid;
                         spin_unlock(&journal->j_list_lock);
-                        spin_unlock(&journal->j_state_lock);
+                        write_unlock(&journal->j_state_lock);
                         if (chkpt) {
                                 jbd2_log_do_checkpoint(journal);
                         } else if (jbd2_cleanup_journal_tail(journal) == 0) {
@@ -167,7 +167,7 @@ void __jbd2_log_wait_for_space(journal_t *journal)
                                 WARN_ON(1);
                                 jbd2_journal_abort(journal, 0);
                         }
-                        spin_lock(&journal->j_state_lock);
+                        write_lock(&journal->j_state_lock);
                 } else {
                         spin_unlock(&journal->j_list_lock);
                 }
@@ -474,7 +474,7 @@ int jbd2_cleanup_journal_tail(journal_t *journal)
          * next transaction ID we will write, and where it will
          * start. */
 
-        spin_lock(&journal->j_state_lock);
+        write_lock(&journal->j_state_lock);
         spin_lock(&journal->j_list_lock);
         transaction = journal->j_checkpoint_transactions;
         if (transaction) {
@@ -496,7 +496,7 @@ int jbd2_cleanup_journal_tail(journal_t *journal)
         /* If the oldest pinned transaction is at the tail of the log
            already then there's not much we can do right now. */
         if (journal->j_tail_sequence == first_tid) {
-                spin_unlock(&journal->j_state_lock);
+                write_unlock(&journal->j_state_lock);
                 return 1;
         }
 
@@ -516,7 +516,7 @@ int jbd2_cleanup_journal_tail(journal_t *journal)
         journal->j_free += freed;
         journal->j_tail_sequence = first_tid;
         journal->j_tail = blocknr;
-        spin_unlock(&journal->j_state_lock);
+        write_unlock(&journal->j_state_lock);
 
         /*
          * If there is an external journal, we need to make sure that