From 6c20ec850360bc6e5c66a787f0523a80450d65ab Mon Sep 17 00:00:00 2001
From: Theodore Ts'o <tytso@mit.edu>
Date: Tue, 28 Oct 2008 21:08:20 -0400
Subject: [PATCH] jbd2: Call the commit callback before the transaction could
 get dropped

The transaction can potentially get dropped if there are no buffers
that need to be written.  Make sure we call the commit callback before
potentially deciding to drop the transaction.  Also avoid
dereferencing the commit_transaction pointer in the marker for the
same reason.

This patch fixes the bug reported by Eric Paris at:
http://bugzilla.kernel.org/show_bug.cgi?id=11838

Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
Acked-by: Eric Sandeen <sandeen@redhat.com>
Tested-by: Eric Paris <eparis@redhat.com>
---
 fs/jbd2/commit.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/fs/jbd2/commit.c b/fs/jbd2/commit.c
index 8b119e16aa36..ebc667bc54a8 100644
--- a/fs/jbd2/commit.c
+++ b/fs/jbd2/commit.c
@@ -974,6 +974,9 @@ restart_loop:
 	journal->j_committing_transaction = NULL;
 	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);
@@ -995,11 +998,8 @@ 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, commit_transaction->t_tid,
+		   journal->j_devname, journal->j_commit_sequence,
 		   journal->j_tail_sequence);
 	jbd_debug(1, "JBD: commit %d complete, head %d\n",
 		  journal->j_commit_sequence, journal->j_tail_sequence);