jbd: Remove j_barrier mutex

j_barrier mutex is used for serializing different journal lock operations.  The
problem with it is that e.g. FIFREEZE ioctl results in process leaving kernel
with j_barrier mutex held which makes lockdep freak out. Also hibernation code
wants to freeze filesystem but it cannot do so because it then cannot hibernate
the system because of mutex being locked.

So we remove j_barrier mutex and use direct wait on j_barrier_count instead.
Since locking journal is a rare operation we don't have to care about fairness
or such things.

CC: Andrew Morton <akpm@linux-foundation.org>
Acked-by: Joel Becker <jlbec@evilplan.org>
Signed-off-by: Jan Kara <jack@suse.cz>

1 files changed, 0 insertions, 4 deletions

diff --git a/include/linux/jbd.h b/include/linux/jbd.h
index 492cc12244fd..d211732b9e99 100644
--- a/include/linux/jbd.h
+++ b/include/linux/jbd.h
@@ -497,7 +497,6 @@ struct transaction_s
  * @j_format_version: Version of the superblock format
  * @j_state_lock: Protect the various scalars in the journal
  * @j_barrier_count:  Number of processes waiting to create a barrier lock
- * @j_barrier: The barrier lock itself
  * @j_running_transaction: The current running transaction..
  * @j_committing_transaction: the transaction we are pushing to disk
  * @j_checkpoint_transactions: a linked circular list of all transactions
@@ -580,9 +579,6 @@ struct journal_s
          */
         int                     j_barrier_count;
 
-        /* The barrier lock itself */
-        struct mutex            j_barrier;
-
         /*
          * Transactions: The current running transaction...
          * [j_state_lock] [caller holding open handle]