reiserfs: convert j_commit_lock to mutex

j_commit_lock is a semaphore but uses it as if it were a mutex.  This patch
converts it to a mutex.

[akpm@linux-foundation.org: coding-style fixes]
Signed-off-by: Jeff Mahoney <jeffm@suse.com>
Cc: Matthew Wilcox <matthew@wil.cx>
Cc: Chris Mason <chris.mason@oracle.com>
Cc: Edward Shishkin <edward.shishkin@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/include/linux/reiserfs_fs_sb.h b/include/linux/reiserfs_fs_sb.h
index c075172..315517e 100644
--- a/include/linux/reiserfs_fs_sb.h
+++ b/include/linux/reiserfs_fs_sb.h
@@ -152,7 +152,7 @@
 	atomic_t j_nonzerolen;
 	atomic_t j_commit_left;
 	atomic_t j_older_commits_done;	/* all commits older than this on disk */
-	struct semaphore j_commit_lock;
+	struct mutex j_commit_mutex;
 	unsigned long j_trans_id;
 	time_t j_timestamp;
 	struct reiserfs_list_bitmap *j_list_bitmap;