From 55d33667ee1902c2f577b250fefd7658466ab80c Mon Sep 17 00:00:00 2001
From: Conrad Meyer <cem@FreeBSD.org>
Date: Tue, 15 Sep 2015 20:22:30 +0000
Subject: [PATCH] kevent(2): Note DOOMED vnodes with NOTE_REVOKE

In poll mode, check for and wake VBAD vnodes.  (Vnodes that are VBAD at
registration will never be woken by the RECLAIM trigger.)

Add post-VOP_RECLAIM hook to trigger notes on vnode reclamation.  (Vnodes that
were fine at registration but are vgoned while being monitored should signal
waiters.)

Reviewed by:	kib
Approved by:	markj (mentor)
Sponsored by:	EMC / Isilon Storage Division
Differential Revision:	https://reviews.freebsd.org/D3675
---
 sys/kern/vfs_subr.c   | 15 ++++++++++++---
 sys/kern/vnode_if.src |  1 +
 sys/sys/vnode.h       |  1 +
 3 files changed, 14 insertions(+), 3 deletions(-)

diff --git a/sys/kern/vfs_subr.c b/sys/kern/vfs_subr.c
index 410d1986b06f..29ca5b1011bd 100644
--- a/sys/kern/vfs_subr.c
+++ b/sys/kern/vfs_subr.c
@@ -4344,6 +4344,15 @@ vop_mknod_post(void *ap, int rc)
 		VFS_KNOTE_LOCKED(a->a_dvp, NOTE_WRITE);
 }
 
+void
+vop_reclaim_post(void *ap, int rc)
+{
+	struct vop_reclaim_args *a = ap;
+
+	if (!rc)
+		VFS_KNOTE_LOCKED(a->a_vp, NOTE_REVOKE);
+}
+
 void
 vop_remove_post(void *ap, int rc)
 {
@@ -4624,7 +4633,7 @@ filt_vfsread(struct knote *kn, long hint)
 	 * filesystem is gone, so set the EOF flag and schedule
 	 * the knote for deletion.
 	 */
-	if (hint == NOTE_REVOKE) {
+	if (hint == NOTE_REVOKE || (hint == 0 && vp->v_type == VBAD)) {
 		VI_LOCK(vp);
 		kn->kn_flags |= (EV_EOF | EV_ONESHOT);
 		VI_UNLOCK(vp);
@@ -4653,7 +4662,7 @@ filt_vfswrite(struct knote *kn, long hint)
 	 * filesystem is gone, so set the EOF flag and schedule
 	 * the knote for deletion.
 	 */
-	if (hint == NOTE_REVOKE)
+	if (hint == NOTE_REVOKE || (hint == 0 && vp->v_type == VBAD))
 		kn->kn_flags |= (EV_EOF | EV_ONESHOT);
 
 	kn->kn_data = 0;
@@ -4670,7 +4679,7 @@ filt_vfsvnode(struct knote *kn, long hint)
 	VI_LOCK(vp);
 	if (kn->kn_sfflags & hint)
 		kn->kn_fflags |= hint;
-	if (hint == NOTE_REVOKE) {
+	if (hint == NOTE_REVOKE || (hint == 0 && vp->v_type == VBAD)) {
 		kn->kn_flags |= EV_EOF;
 		VI_UNLOCK(vp);
 		return (1);
diff --git a/sys/kern/vnode_if.src b/sys/kern/vnode_if.src
index c3c8ed36adb2..63f8eb9237cf 100644
--- a/sys/kern/vnode_if.src
+++ b/sys/kern/vnode_if.src
@@ -355,6 +355,7 @@ vop_inactive {
 
 
 %% reclaim	vp	E E E
+%! reclaim	post	vop_reclaim_post
 
 vop_reclaim {
 	IN struct vnode *vp;
diff --git a/sys/sys/vnode.h b/sys/sys/vnode.h
index 800d340edbf5..f37fd05e9ea1 100644
--- a/sys/sys/vnode.h
+++ b/sys/sys/vnode.h
@@ -781,6 +781,7 @@ void	vop_lookup_post(void *a, int rc);
 void	vop_lookup_pre(void *a);
 void	vop_mkdir_post(void *a, int rc);
 void	vop_mknod_post(void *a, int rc);
+void	vop_reclaim_post(void *a, int rc);
 void	vop_remove_post(void *a, int rc);
 void	vop_rename_post(void *a, int rc);
 void	vop_rename_pre(void *a);