jbd2: Call journal commit callback without holding j_list_lock

Avoid freeing the transaction in __jbd2_journal_drop_transaction() so
the journal commit callback can run without holding j_list_lock, to
avoid lock contention on this spinlock.

Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>

3 files changed, 11 insertions, 8 deletions

diff --git a/fs/jbd2/checkpoint.c b/fs/jbd2/checkpoint.c
index adc08ec875ed..17159cacbd9e 100644
--- a/fs/jbd2/checkpoint.c
+++ b/fs/jbd2/checkpoint.c
@@ -682,6 +682,7 @@ int __jbd2_journal_remove_checkpoint(struct journal_head *jh)
            safely remove this transaction from the log */
 
         __jbd2_journal_drop_transaction(journal, transaction);
+        kfree(transaction);
 
         /* Just in case anybody was waiting for more transactions to be
            checkpointed... */
@@ -756,5 +757,4 @@ void __jbd2_journal_drop_transaction(journal_t *journal, transaction_t *transact
         J_ASSERT(journal->j_running_transaction != transaction);
 
         jbd_debug(1, "Dropping transaction %d, all done\n", transaction->t_tid);
-        kfree(transaction);
 }
diff --git a/fs/jbd2/commit.c b/fs/jbd2/commit.c
index f22d1828ea85..0ad84162c425 100644
--- a/fs/jbd2/commit.c
+++ b/fs/jbd2/commit.c
@@ -363,7 +363,7 @@ void jbd2_journal_commit_transaction(journal_t *journal)
         int space_left = 0;
         int first_tag = 0;
         int tag_flag;
-        int i;
+        int i, to_free = 0;
         int tag_bytes = journal_tag_bytes(journal);
         struct buffer_head *cbh = NULL; /* For transactional checksums */
         __u32 crc32_sum = ~0;
@@ -1011,12 +1011,10 @@ restart_loop:
                 journal->j_average_commit_time = commit_time;
         spin_unlock(&journal->j_state_lock);
 
-        if (journal->j_commit_callback)
-                journal->j_commit_callback(journal, commit_transaction);
-
         if (commit_transaction->t_checkpoint_list == NULL &&
             commit_transaction->t_checkpoint_io_list == NULL) {
                 __jbd2_journal_drop_transaction(journal, commit_transaction);
+                to_free = 1;
         } else {
                 if (journal->j_checkpoint_transactions == NULL) {
                         journal->j_checkpoint_transactions = commit_transaction;
@@ -1035,11 +1033,16 @@ restart_loop:
         }
         spin_unlock(&journal->j_list_lock);
 
+        if (journal->j_commit_callback)
+                journal->j_commit_callback(journal, commit_transaction);
+
         trace_mark(jbd2_end_commit, "dev %s transaction %d head %d",
-                   journal->j_devname, journal->j_commit_sequence,
+                   journal->j_devname, commit_transaction->t_tid,
                    journal->j_tail_sequence);
         jbd_debug(1, "JBD: commit %d complete, head %d\n",
                   journal->j_commit_sequence, journal->j_tail_sequence);
+        if (to_free)
+                kfree(commit_transaction);
 
         wake_up(&journal->j_wait_done_commit);
 }
diff --git a/include/linux/jbd2.h b/include/linux/jbd2.h
index 004c9a8d63ed..9d82084a1605 100644
--- a/include/linux/jbd2.h
+++ b/include/linux/jbd2.h
@@ -1179,8 +1179,8 @@ int jbd2_log_wait_commit(journal_t *journal, tid_t tid);
 int jbd2_log_do_checkpoint(journal_t *journal);
 
 void __jbd2_log_wait_for_space(journal_t *journal);
-extern void     __jbd2_journal_drop_transaction(journal_t *, transaction_t *);
-extern int      jbd2_cleanup_journal_tail(journal_t *);
+extern void __jbd2_journal_drop_transaction(journal_t *, transaction_t *);
+extern int jbd2_cleanup_journal_tail(journal_t *);
 
 /* Debugging code only: */