ext4: Fix buffer head reference leak in no-journal mode

We found a problem with buffer head reference leaks when using an ext4
partition without a journal.  In particular, calls to ext4_forget() would
not to a brelse() on the input buffer head, which will cause pages they
belong to to not be reclaimable.

Further investigation showed that all places where ext4_journal_forget() and
ext4_journal_revoke() are called are subject to the same problem.  The patch
below changes __ext4_journal_forget/__ext4_journal_revoke to do an explicit
release of the buffer head when the journal handle isn't valid.

Signed-off-by: Curt Wohlgemuth <curtw@google.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>

1 files changed, 4 insertions, 0 deletions

diff --git a/fs/ext4/ext4_jbd2.c b/fs/ext4/ext4_jbd2.c
index ad13a84644e1..eb27fd0f2ee8 100644
--- a/fs/ext4/ext4_jbd2.c
+++ b/fs/ext4/ext4_jbd2.c
@@ -43,6 +43,8 @@ int __ext4_journal_forget(const char *where, handle_t *handle,
                         ext4_journal_abort_handle(where, __func__, bh,
                                                   handle, err);
         }
+        else
+                brelse(bh);
         return err;
 }
 
@@ -57,6 +59,8 @@ int __ext4_journal_revoke(const char *where, handle_t *handle,
                         ext4_journal_abort_handle(where, __func__, bh,
                                                   handle, err);
         }
+        else
+                brelse(bh);
         return err;
 }