Regularize the vop_stdlock'ing protocol across all the filesystems

that use it. Specifically, vop_stdlock uses the lock pointed to by
vp->v_vnlock. By default, getnewvnode sets up vp->v_vnlock to
reference vp->v_lock. Filesystems that wish to use the default
do not need to allocate a lock at the front of their node structure
(as some still did) or do a lockinit. They can simply start using
vn_lock/VOP_UNLOCK. Filesystems that wish to manage their own locks,
but still use the vop_stdlock functions (such as nullfs) can simply
replace vp->v_vnlock with a pointer to the lock that they wish to
have used for the vnode. Such filesystems are responsible for
setting the vp->v_vnlock back to the default in their vop_reclaim
routine (e.g., vp->v_vnlock = &vp->v_lock).

In theory, this set of changes cleans up the existing filesystem
lock interface and should have no function change to the existing
locking scheme.

Sponsored by:	DARPA & NAI Labs.

1 files changed, 0 insertions, 5 deletions

diff --git a/sys/fs/unionfs/union.h b/sys/fs/unionfs/union.h
index 3a2ee2a..58afd21 100644
--- a/sys/fs/unionfs/union.h
+++ b/sys/fs/unionfs/union.h
@@ -66,13 +66,8 @@ struct union_mount {
 
 /*
  * A cache of vnode references	(hangs off v_data)
- *
- * Placing un_lock as the first elements theoretically allows us to
- * use the vop_stdlock functions.  However, we need to make sure of
- * certain side effects so we will still punch in our own code.
  */
 struct union_node {
-	struct lock		un_lock;
 	LIST_ENTRY(union_node)	un_cache;	/* Hash chain */
 	struct vnode		*un_vnode;	/* Back pointer */
 	struct vnode	        *un_uppervp;	/* overlaying object */