Introduce some functions in the vnode locks namespace and in the ffs

namespace in order to handle lockmgr fields in a controlled way instead
than spreading all around bogus stubs:
- VN_LOCK_AREC() allows lock recursion for a specified vnode
- VN_LOCK_ASHARE() allows lock sharing for a specified vnode

In FFS land:
- BUF_AREC() allows lock recursion for a specified buffer lock
- BUF_NOREC() disallows recursion for a specified buffer lock

Side note: union_subr.c::unionfs_node_update() is the only other function
directly handling lockmgr fields. As this is not simple to fix, it has
been left behind as "sole" exception.

2 files changed, 8 insertions, 5 deletions

diff --git a/sys/ufs/ffs/ffs_softdep.c b/sys/ufs/ffs/ffs_softdep.c
index e4838e3..bda95d0 100644
--- a/sys/ufs/ffs/ffs_softdep.c
+++ b/sys/ufs/ffs/ffs_softdep.c
@@ -564,6 +564,9 @@ MTX_SYSINIT(softdep_lock, &lk, "Softdep Lock", MTX_DEF);
 #define ACQUIRE_LOCK(lk)		mtx_lock(lk)
 #define FREE_LOCK(lk)			mtx_unlock(lk)
 
+#define	BUF_AREC(bp)	((bp)->b_lock.lk_flags |= LK_CANRECURSE)
+#define	BUF_NOREC(bp)	((bp)->b_lock.lk_flags &= ~LK_CANRECURSE)
+
 /*
  * Worklist queue management.
  * These routines require that the lock be held.
@@ -5251,7 +5254,7 @@ top:
 		return (0);
 loop:
 	/* While syncing snapshots, we must allow recursive lookups */
-	bp->b_lock.lk_flags |= LK_CANRECURSE;
+	BUF_AREC(bp);
 	ACQUIRE_LOCK(&lk);
 	/*
 	 * As we hold the buffer locked, none of its dependencies
@@ -5393,7 +5396,7 @@ loop:
 		/* We reach here only in error and unlocked */
 		if (error == 0)
 			panic("softdep_sync_metadata: zero error");
-		bp->b_lock.lk_flags &= ~LK_CANRECURSE;
+		BUF_NOREC(bp);
 		bawrite(bp);
 		return (error);
 	}
@@ -5405,7 +5408,7 @@ loop:
 			break;
 	}
 	VI_UNLOCK(vp);
-	bp->b_lock.lk_flags &= ~LK_CANRECURSE;
+	BUF_NOREC(bp);
 	bawrite(bp);
 	if (nbp != NULL) {
 		bp = nbp;
diff --git a/sys/ufs/ffs/ffs_vfsops.c b/sys/ufs/ffs/ffs_vfsops.c
index 971694f..f226750 100644
--- a/sys/ufs/ffs/ffs_vfsops.c
+++ b/sys/ufs/ffs/ffs_vfsops.c
@@ -1363,8 +1363,8 @@ ffs_vget(mp, ino, flags, vpp)
 	/*
 	 * FFS supports recursive and shared locking.
 	 */
-	vp->v_vnlock->lk_flags |= LK_CANRECURSE;
-	vp->v_vnlock->lk_flags &= ~LK_NOSHARE;
+	VN_LOCK_AREC(vp);
+	VN_LOCK_ASHARE(vp);
 	vp->v_data = ip;
 	vp->v_bufobj.bo_bsize = fs->fs_bsize;
 	ip->i_vnode = vp;