- Complete part of the unfinished bufobj work by consistently using

   BO_LOCK/UNLOCK/MTX when manipulating the bufobj.
 - Create a new lock in the bufobj to lock bufobj fields independently.
   This leaves the vnode interlock as an 'identity' lock while the bufobj
   is an io lock.  The bufobj lock is ordered before the vnode interlock
   and also before the mnt ilock.
 - Exploit this new lock order to simplify softdep_check_suspend().
 - A few sync related functions are marked with a new XXX to note that
   we may not properly interlock against a non-zero bv_cnt when
   attempting to sync all vnodes on a mountlist.  I do not believe this
   race is important.  If I'm wrong this will make these locations easier
   to find.

Reviewed by:	kib (earlier diff)
Tested by:	kris, pho (earlier diff)

1 files changed, 8 insertions, 16 deletions

diff --git a/sys/sys/bufobj.h b/sys/sys/bufobj.h
index 9ad572a..e491ce1 100644
--- a/sys/sys/bufobj.h
+++ b/sys/sys/bufobj.h
@@ -52,6 +52,8 @@
 #if defined(_KERNEL) || defined(_KVM_VNODE)
 
 #include <sys/queue.h>
+#include <sys/_lock.h>
+#include <sys/_mutex.h>
 
 struct bufobj;
 struct buf_ops;
@@ -87,7 +89,7 @@ struct buf_ops {
 #define BO_BDFLUSH(bo, bp)	((bo)->bo_ops->bop_bdflush((bo), (bp)))
 
 struct bufobj {
-	struct mtx	*bo_mtx;	/* Mutex which protects "i" things */
+	struct mtx	bo_mtx;		/* Mutex which protects "i" things */
 	struct bufv	bo_clean;	/* i Clean buffers */
 	struct bufv	bo_dirty;	/* i Dirty buffers */
 	long		bo_numoutput;	/* i Writes in progress */
@@ -112,21 +114,11 @@ struct bufobj {
 #define	BO_WWAIT	(1 << 1)	/* Wait for output to complete */
 #define	BO_NEEDSGIANT	(1 << 2)	/* Require giant for child buffers. */
 
-#define	BO_LOCK(bo) \
-	do { \
-		KASSERT((bo)->bo_mtx != NULL, ("No lock in bufobj")); \
-		mtx_lock((bo)->bo_mtx); \
-	} while (0)
-
-#define BO_UNLOCK(bo) \
-	do { \
-		KASSERT((bo)->bo_mtx != NULL, ("No lock in bufobj")); \
-		mtx_unlock((bo)->bo_mtx); \
-	} while (0)
-
-#define	BO_MTX(bo)		((bo)->bo_mtx)
-#define	ASSERT_BO_LOCKED(bo)	mtx_assert(bo->bo_mtx, MA_OWNED)
-#define	ASSERT_BO_UNLOCKED(bo)	mtx_assert(bo->bo_mtx, MA_NOTOWNED)
+#define	BO_MTX(bo)		(&(bo)->bo_mtx)
+#define	BO_LOCK(bo)		mtx_lock(BO_MTX((bo)))
+#define	BO_UNLOCK(bo)		mtx_unlock(BO_MTX((bo)))
+#define	ASSERT_BO_LOCKED(bo)	mtx_assert(BO_MTX((bo)), MA_OWNED)
+#define	ASSERT_BO_UNLOCKED(bo)	mtx_assert(BO_MTX((bo)), MA_NOTOWNED)
 
 void bufobj_wdrop(struct bufobj *bo);
 void bufobj_wref(struct bufobj *bo);