[GFS2] Update locking in log.c

Replace the lock_for_trans()/lock_for_flush() functions with an rwsem.
In fact the sd_log_flush_lock becomes an rwsem (the write part of it)
and is extended slightly to cover everything that the lock_for_flush()
used to cover. The read part of the lock is instead of lock_for_trans().

This corrects the races in the original code and reduces the code size.

Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>

1 files changed, 1 insertions, 5 deletions

diff --git a/fs/gfs2/incore.h b/fs/gfs2/incore.h
index be307185f492..35163b562460 100644
--- a/fs/gfs2/incore.h
+++ b/fs/gfs2/incore.h
@@ -611,10 +611,6 @@ struct gfs2_sbd {
 	/* Log stuff */
 
 	spinlock_t sd_log_lock;
-	atomic_t sd_log_trans_count;
-	wait_queue_head_t sd_log_trans_wq;
-	atomic_t sd_log_flush_count;
-	wait_queue_head_t sd_log_flush_wq;
 
 	unsigned int sd_log_blks_reserved;
 	unsigned int sd_log_commited_buf;
@@ -643,7 +639,7 @@ struct gfs2_sbd {
 	int sd_log_idle;
 
 	unsigned long sd_log_flush_time;
-	struct mutex sd_log_flush_lock;
+	struct rw_semaphore sd_log_flush_lock;
 	struct list_head sd_log_flush_list;
 
 	unsigned int sd_log_flush_head;