From fae85b1e6961525c0b9017bb021d98e19c2e4451 Mon Sep 17 00:00:00 2001
From: claudio <claudio@openbsd.org>
Date: Thu, 21 Oct 2021 09:59:13 +0000
Subject: [PATCH] Move vfs_stall_barrier() from the fd layer into vn_lock() and
 the vfs layer. vfs stalling is used by suspend/resume and by vmt(4) to stall
 any filesystem operation from altering the state on disk. All these
 operations will call vn_lock and be stalled. Adjust vfs_stall_barrier() to
 allow the lock owner to still progress so that suspend can sync the
 filesystems after stalling vfs operation. OK mpi@

---
 sys/kern/kern_descrip.c | 4 +---
 sys/kern/vfs_subr.c     | 8 +++++---
 sys/kern/vfs_vnops.c    | 4 +++-
 sys/sys/file.h          | 8 ++------
 4 files changed, 11 insertions(+), 13 deletions(-)

diff --git a/sys/kern/kern_descrip.c b/sys/kern/kern_descrip.c
index 744b2247801..ea3e3399ce0 100644
--- a/sys/kern/kern_descrip.c
+++ b/sys/kern/kern_descrip.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: kern_descrip.c,v 1.202 2020/06/11 13:23:18 visa Exp $	*/
+/*	$OpenBSD: kern_descrip.c,v 1.203 2021/10/21 09:59:13 claudio Exp $	*/
 /*	$NetBSD: kern_descrip.c,v 1.42 1996/03/30 22:24:38 christos Exp $	*/
 
 /*
@@ -232,8 +232,6 @@ fd_getfile(struct filedesc *fdp, int fd)
 {
 	struct file *fp;
 
-	vfs_stall_barrier();
-
 	if ((u_int)fd >= fdp->fd_nfiles)
 		return (NULL);
 
diff --git a/sys/kern/vfs_subr.c b/sys/kern/vfs_subr.c
index 794a4f2cf03..011e7597269 100644
--- a/sys/kern/vfs_subr.c
+++ b/sys/kern/vfs_subr.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: vfs_subr.c,v 1.308 2021/10/20 06:35:39 semarie Exp $	*/
+/*	$OpenBSD: vfs_subr.c,v 1.309 2021/10/21 09:59:14 claudio Exp $	*/
 /*	$NetBSD: vfs_subr.c,v 1.53 1996/04/22 01:39:13 christos Exp $	*/
 
 /*
@@ -1701,8 +1701,10 @@ void
 vfs_stall_barrier(void)
 {
 	if (__predict_false(vfs_stalling)) {
-		rw_enter_read(&vfs_stall_lock);
-		rw_exit_read(&vfs_stall_lock);
+		if (curproc != RWLOCK_OWNER(&vfs_stall_lock)) {
+			rw_enter_read(&vfs_stall_lock);
+			rw_exit_read(&vfs_stall_lock);
+		}
 	}
 }
 
diff --git a/sys/kern/vfs_vnops.c b/sys/kern/vfs_vnops.c
index f726d72f8cb..de6d7593b14 100644
--- a/sys/kern/vfs_vnops.c
+++ b/sys/kern/vfs_vnops.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: vfs_vnops.c,v 1.116 2021/05/06 12:55:20 anton Exp $	*/
+/*	$OpenBSD: vfs_vnops.c,v 1.117 2021/10/21 09:59:14 claudio Exp $	*/
 /*	$NetBSD: vfs_vnops.c,v 1.20 1996/02/04 02:18:41 christos Exp $	*/
 
 /*
@@ -565,6 +565,8 @@ vn_lock(struct vnode *vp, int flags)
 {
 	int error, xlocked, do_wakeup;
 
+	vfs_stall_barrier();
+
 	do {
 		mtx_enter(&vnode_mtx);
 		if (vp->v_lflag & VXLOCK) {
diff --git a/sys/sys/file.h b/sys/sys/file.h
index ff07a1d41b1..b440e1275c5 100644
--- a/sys/sys/file.h
+++ b/sys/sys/file.h
@@ -1,4 +1,4 @@
-/*	$OpenBSD: file.h,v 1.62 2020/12/02 15:50:01 martijn Exp $	*/
+/*	$OpenBSD: file.h,v 1.63 2021/10/21 09:59:14 claudio Exp $	*/
 /*	$NetBSD: file.h,v 1.11 1995/03/26 20:24:13 jtc Exp $	*/
 
 /*
@@ -106,11 +106,7 @@ struct file {
 #define FIF_INSERTED		0x80	/* present in `filehead' */
 
 #define FREF(fp) \
-	do { \
-		extern void vfs_stall_barrier(void); \
-		vfs_stall_barrier(); \
-		atomic_inc_int(&(fp)->f_count); \
-	} while (0)
+	atomic_inc_int(&(fp)->f_count)
 
 #define FRELE(fp,p) \
 	(atomic_dec_int_nv(&fp->f_count) == 0 ? fdrop(fp, p) : 0)
-- 
2.20.1