bfs: kill BKL

Replace the BKL-based locking scheme used in the bfs driver by a private
filesystem-wide mutex.

Signed-off-by: Dmitri Vorobiev <dmitri.vorobiev@movial.fi>
Cc: Tigran Aivazian <tigran_aivazian@symantec.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/fs/bfs/bfs.h b/fs/bfs/bfs.h
index d1a6cd1..7109e45 100644
--- a/fs/bfs/bfs.h
+++ b/fs/bfs/bfs.h
@@ -18,6 +18,7 @@
 	unsigned long si_lasti;
 	unsigned long *si_imap;
 	struct buffer_head *si_sbh;		/* buffer header w/superblock */
+	struct mutex bfs_lock;
 };
 
 /*