Author: mjg
Date: Fri Dec 2 18:03:15 2016
New Revision: 309425
URL: https://svnweb.freebsd.org/changeset/base/309425
Log:
vfs: provide fake locking primitives for the crossmp vnode
Since the vnode is only expected to be shared locked, we can save a
little overhead by only pretending we are locking in the first place.
Reviewed by: kib
Tested by: pho
Modified:
head/sys/kern/vfs_lookup.c
Modified: head/sys/kern/vfs_lookup.c
==============================================================================
--- head/sys/kern/vfs_lookup.c Fri Dec 2 17:08:27 2016 (r309424)
+++ head/sys/kern/vfs_lookup.c Fri Dec 2 18:03:15 2016 (r309425)
@@ -79,6 +79,64 @@ uma_zone_t namei_zone;
/* Placeholder vnode for mp traversal. */
static struct vnode *vp_crossmp;
+static int
+crossmp_vop_islocked(struct vop_islocked_args *ap)
+{
+
+ return (LK_SHARED);
+}
+
+static int
+crossmp_vop_lock1(struct vop_lock1_args *ap)
+{
+ struct vnode *vp;
+ struct lock *lk;
+ const char *file;
+ int flags, line;
+
+ vp = ap->a_vp;
+ lk = vp->v_vnlock;
+ flags = ap->a_flags;
+ file = ap->a_file;
+ line = ap->a_line;
+
+ if ((flags & LK_SHARED) == 0)
+ panic("invalid lock request for crossmp");
+
+ WITNESS_CHECKORDER(&lk->lock_object, LOP_NEWORDER, file, line,
+ flags & LK_INTERLOCK ? &VI_MTX(vp)->lock_object : NULL);
+ WITNESS_LOCK(&lk->lock_object, 0, file, line);
+ if ((flags & LK_INTERLOCK) != 0)
+ VI_UNLOCK(vp);
+ LOCK_LOG_LOCK("SLOCK", &lk->lock_object, 0, 0, ap->a_file, line);
+ return (0);
+}
+
+static int
+crossmp_vop_unlock(struct vop_unlock_args *ap)
+{
+ struct vnode *vp;
+ struct lock *lk;
+ int flags;
+
+ vp = ap->a_vp;
+ lk = vp->v_vnlock;
+ flags = ap->a_flags;
+
+ if ((flags & LK_INTERLOCK) != 0)
+ VI_UNLOCK(vp);
+ WITNESS_UNLOCK(&lk->lock_object, 0, LOCK_FILE, LOCK_LINE);
+ LOCK_LOG_LOCK("SUNLOCK", &lk->lock_object, 0, 0, LOCK_FILE,
+ LOCK_LINE);
+ return (0);
+}
+
+static struct vop_vector crossmp_vnodeops = {
+ .vop_islocked = crossmp_vop_islocked,
+ .vop_lock1 = crossmp_vop_lock1,
+ .vop_unlock = crossmp_vop_unlock,
+};
+
struct nameicap_tracker {
struct vnode *dp;
TAILQ_ENTRY(nameicap_tracker) nm_link;
@@ -95,10 +153,7 @@ nameiinit(void *dummy __unused)
UMA_ALIGN_PTR, 0);
nt_zone = uma_zcreate("rentr", sizeof(struct nameicap_tracker),
NULL, NULL, NULL, NULL, sizeof(void *), 0);
- getnewvnode("crossmp", NULL, &dead_vnodeops, &vp_crossmp);
- vn_lock(vp_crossmp, LK_EXCLUSIVE);
- VN_LOCK_ASHARE(vp_crossmp);
- VOP_UNLOCK(vp_crossmp, 0);
+ getnewvnode("crossmp", NULL, &crossmp_vnodeops, &vp_crossmp);
}
SYSINIT(vfs, SI_SUB_VFS, SI_ORDER_SECOND, nameiinit, NULL);
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