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	Index: sys/fs/devfs/devfs_devs.c
	===================================================================
	--- sys/fs/devfs/devfs_devs.c
	+++ sys/fs/devfs/devfs_devs.c
	@@ -62,6 +62,7 @@
	static MALLOC_DEFINE(M_DEVFS2, "DEVFS2", "DEVFS data 2");
	static MALLOC_DEFINE(M_DEVFS3, "DEVFS3", "DEVFS data 3");
	static MALLOC_DEFINE(M_CDEVP, "DEVFS1", "DEVFS cdev_priv storage");
	+MALLOC_DEFINE(M_CDEV_VP, "DEVFS4", "DEVFS vnode tables");

	SYSCTL_NODE(_vfs, OID_AUTO, devfs, CTLFLAG_RW, 0, "DEVFS filesystem");

	@@ -144,6 +145,8 @@
	LIST_INIT(&cdev->si_children);
	vfs_timestamp(&ts);
	cdev->si_atime = cdev->si_mtime = cdev->si_ctime = ts;
	+ cdev->si_vnodes = (void *)&cdev->si_vnodes_local;
	+ cdev->si_vnodes_size = nitems(cdev->si_vnodes_local);

	return (cdev);
	}
	@@ -173,6 +176,9 @@
	devfs_free(struct cdev *cdev)
	{
	struct cdev_priv *cdp;
	+#ifdef INVARIANTS
	+ int i;
	+#endif

	cdp = cdev2priv(cdev);
	if (cdev->si_cred != NULL)
	@@ -180,6 +186,18 @@
	devfs_free_cdp_inode(cdp->cdp_inode);
	if (cdp->cdp_maxdirent > 0)
	free(cdp->cdp_dirents, M_DEVFS2);
	+ KASSERT(cdev->si_vnodes_assigned == 0, ("%s: cdev %p still has "
	+ "vnodes %d assigned", __func__, cdev, cdev->si_vnodes_assigned));
	+#ifdef INVARIANTS
	+ for (i = 0; i < cdev->si_vnodes_size; i++) {
	+ if (cdev->si_vnodes[i] != NULL) {
	+ printf("%s: cdev %p non-NULL entry at %d\n", __func__,
	+ cdev, i);
	+ }
	+ }
	+#endif
	+ if (cdev->si_vnodes != (void *)&cdev->si_vnodes_local)
	+ free(cdev->si_vnodes, M_CDEV_VP);
	free(cdp, M_CDEVP);
	}

	Index: sys/fs/devfs/devfs_vnops.c
	===================================================================
	--- sys/fs/devfs/devfs_vnops.c
	+++ sys/fs/devfs/devfs_vnops.c
	@@ -82,6 +82,7 @@
	#include <vm/vm_object.h>

	static MALLOC_DEFINE(M_CDEVPDATA, "DEVFSP", "Metainfo for cdev-fp data");
	+MALLOC_DECLARE(M_CDEV_VP);

	struct mtx devfs_de_interlock;
	MTX_SYSINIT(devfs_de_interlock, &devfs_de_interlock, "devfs interlock", MTX_DEF);
	@@ -418,6 +419,88 @@
	vput(vp);
	}

	+static void
	+dev_vn_growtable(struct cdev *dev)
	+{
	+ struct vnode vt, tofree;
	+ int newsize;
	+
	+ newsize = dev->si_vnodes_size * 2;
	+ vt = malloc(newsize * sizeof(*vt), M_CDEV_VP, M_WAITOK \| M_ZERO);
	+ dev_lock();
	+ if (dev->si_vnodes_size >= newsize) {
	+ dev_unlock();
	+ free(vt, M_CDEV_VP);
	+ return;
	+ }
	+ memcpy(vt, dev->si_vnodes, dev->si_vnodes_size * sizeof(*vt));
	+ if (dev->si_vnodes != (void *)&dev->si_vnodes_local)
	+ tofree = dev->si_vnodes;
	+ else
	+ tofree = NULL;
	+ dev->si_vnodes = vt;
	+ dev->si_vnodes_size = newsize;
	+ dev_unlock();
	+ free(tofree, M_CDEV_VP);
	+}
	+
	+static int
	+dev_vn_add_vp(struct cdev dev, struct vnode vp)
	+{
	+
	+ if (dev->si_vnodes_size == dev->si_vnodes_assigned)
	+ return (EAGAIN);
	+
	+ vp->v_rdev = dev;
	+ KASSERT(vp->v_usecount == 1,
	+ ("%s %d (%d)\n", __func__, __LINE__, vp->v_usecount));
	+ dev->si_vnodes_assigned++;
	+ dev_vn_table_add(dev, vp);
	+ return (0);
	+}
	+
	+static void
	+dev_vn_remove_vp(struct cdev dev, struct vnode vp)
	+{
	+ mtx_assert(&devmtx, MA_OWNED);
	+
	+ if (dev == NULL)
	+ return;
	+ dev_vn_table_remove(dev, vp);
	+ dev->si_vnodes_assigned--;
	+ vp->v_rdev = NULL;
	+}
	+
	+void
	+dev_vn_table_add(struct cdev dev, struct vnode vp)
	+{
	+ mtx_assert(&devmtx, MA_OWNED);
	+
	+ if (dev->si_vnodes_size == dev->si_vnodes_index)
	+ panic("%s: no room for vnode %p in cdev %p table\n",
	+ __func__, vp, dev);
	+
	+ dev->si_vnodes[dev->si_vnodes_index++] = vp;
	+}
	+
	+void
	+dev_vn_table_remove(struct cdev dev, struct vnode vp)
	+{
	+ int i;
	+
	+ mtx_assert(&devmtx, MA_OWNED);
	+
	+ for (i = 0; i < dev->si_vnodes_index; i++) {
	+ if (dev->si_vnodes[i] == vp) {
	+ dev->si_vnodes[i] = dev->si_vnodes[dev->si_vnodes_index - 1];
	+ dev->si_vnodes[dev->si_vnodes_index - 1] = NULL;
	+ dev->si_vnodes_index--;
	+ return;
	+ }
	+ }
	+ panic("%s: vnode %p not found in cdev %p table\n", __func__, vp, dev);
	+}
	+
	/*
	* devfs_allocv shall be entered with dmp->dm_lock held, and it drops
	* it on return.
	@@ -485,14 +568,16 @@

	if (de->de_dirent->d_type == DT_CHR) {
	vp->v_type = VCHR;
	- VI_LOCK(vp);
	- dev_lock();
	+ for (;;) {
	+ VI_LOCK(vp);
	+ dev_lock();
	+ if (dev_vn_add_vp(dev, vp) == 0)
	+ break;
	+ dev_unlock();
	+ VI_UNLOCK(vp);
	+ dev_vn_growtable(dev);
	+ }
	dev_refl(dev);
	- /* XXX: v_rdev should be protect by vnode lock */
	- vp->v_rdev = dev;
	- KASSERT(vp->v_usecount == 1,
	- ("%s %d (%d)\n", __func__, __LINE__, vp->v_usecount));
	- dev->si_usecount += vp->v_usecount;
	/* Special casing of ttys for deadfs. Probably redundant. */
	dsw = dev->si_devsw;
	if (dsw != NULL && (dsw->d_flags & D_TTY) != 0)
	@@ -602,7 +687,7 @@
	if (vp == p->p_session->s_ttyvp) {
	SESS_LOCK(p->p_session);
	VI_LOCK(vp);
	- if (count_dev(dev) == 2 &&
	+ if (count_dev_cmp(dev, 2) == 0 &&
	(vp->v_iflag & VI_DOOMED) == 0) {
	p->p_session->s_ttyvp = NULL;
	p->p_session->s_ttydp = NULL;
	@@ -636,12 +721,12 @@
	dflags \|= FREVOKE \| FNONBLOCK;
	} else if (dsw->d_flags & D_TRACKCLOSE) {
	/* Keep device updated on status. */
	- } else if (count_dev(dev) > 1) {
	+ } else if (count_dev_cmp(dev, 1) > 0) {
	VI_UNLOCK(vp);
	dev_relthread(dev, ref);
	return (0);
	}
	- if (count_dev(dev) == 1)
	+ if (count_dev_cmp(dev, 1) == 0)
	dflags \|= FLASTCLOSE;
	vholdl(vp);
	VI_UNLOCK(vp);
	@@ -1445,9 +1530,7 @@
	VI_LOCK(vp);
	dev_lock();
	dev = vp->v_rdev;
	- vp->v_rdev = NULL;
	- if (dev != NULL)
	- dev->si_usecount -= vp->v_usecount;
	+ dev_vn_remove_vp(dev, vp);
	dev_unlock();
	VI_UNLOCK(vp);
	if (dev != NULL)
	Index: sys/kern/kern_conf.c
	===================================================================
	--- sys/kern/kern_conf.c
	+++ sys/kern/kern_conf.c
	@@ -1526,8 +1526,8 @@

	dev = (struct cdev *)addr;
	cdp = cdev2priv(dev);
	- db_printf("dev %s ref %d use %ld thr %ld inuse %u fdpriv %p\n",
	- dev->si_name, dev->si_refcount, dev->si_usecount,
	+ db_printf("dev %s ref %d use %d thr %ld inuse %u fdpriv %p\n",
	+ dev->si_name, dev->si_refcount, count_dev(dev),
	dev->si_threadcount, cdp->cdp_inuse, cdp->cdp_fdpriv.lh_first);
	db_printf("devsw %p si_drv0 %d si_drv1 %p si_drv2 %p\n",
	dev->si_devsw, dev->si_drv0, dev->si_drv1, dev->si_drv2);
	@@ -1563,5 +1563,8 @@
	CDP_FLAG(CDP_ACTIVE);
	CDP_FLAG(CDP_SCHED_DTR);
	db_printf("cdp_flags %s\n", buf);
	+ db_printf("si_vnodes %p si_vnodes_assigned %d si_vnodes_index %d"
	+ "si_vnodes_size %d\n", dev->si_vnodes, dev->si_vnodes_assigned,
	+ dev->si_vnodes_index, dev->si_vnodes_size);
	}
	#endif
	Index: sys/kern/vfs_subr.c
	===================================================================
	--- sys/kern/vfs_subr.c
	+++ sys/kern/vfs_subr.c
	@@ -107,8 +107,6 @@
	static void syncer_shutdown(void *arg, int howto);
	static int vtryrecycle(struct vnode *vp);
	static void v_init_counters(struct vnode *);
	-static void v_incr_devcount(struct vnode *);
	-static void v_decr_devcount(struct vnode *);
	static void vgonel(struct vnode *);
	static void vfs_knllock(void *arg);
	static void vfs_knlunlock(void *arg);
	@@ -2630,36 +2628,6 @@
	refcount_init(&vp->v_usecount, 1);
	}

	-/*
	- * Increment si_usecount of the associated device, if any.
	- */
	-static void
	-v_incr_devcount(struct vnode *vp)
	-{
	-
	- ASSERT_VI_LOCKED(vp, __FUNCTION__);
	- if (vp->v_type == VCHR && vp->v_rdev != NULL) {
	- dev_lock();
	- vp->v_rdev->si_usecount++;
	- dev_unlock();
	- }
	-}
	-
	-/*
	- * Decrement si_usecount of the associated device, if any.
	- */
	-static void
	-v_decr_devcount(struct vnode *vp)
	-{
	-
	- ASSERT_VI_LOCKED(vp, __FUNCTION__);
	- if (vp->v_type == VCHR && vp->v_rdev != NULL) {
	- dev_lock();
	- vp->v_rdev->si_usecount--;
	- dev_unlock();
	- }
	-}
	-
	/*
	* Grab a particular vnode from the free list, increment its
	* reference count and lock it. VI_DOOMED is set if the vnode
	@@ -2679,26 +2647,11 @@
	{
	enum vgetstate vs;

	- if (__predict_true(vp->v_type != VCHR)) {
	- if (refcount_acquire_if_not_zero(&vp->v_usecount)) {
	- vs = VGET_USECOUNT;
	- } else {
	- _vhold(vp, interlock);
	- vs = VGET_HOLDCNT;
	- }
	+ if (refcount_acquire_if_not_zero(&vp->v_usecount)) {
	+ vs = VGET_USECOUNT;
	} else {
	- if (!interlock)
	- VI_LOCK(vp);
	- if (vp->v_usecount == 0) {
	- vholdl(vp);
	- vs = VGET_HOLDCNT;
	- } else {
	- v_incr_devcount(vp);
	- refcount_acquire(&vp->v_usecount);
	- vs = VGET_USECOUNT;
	- }
	- if (!interlock)
	- VI_UNLOCK(vp);
	+ _vhold(vp, interlock);
	+ vs = VGET_HOLDCNT;
	}
	return (vs);
	}
	@@ -2761,8 +2714,7 @@
	* the vnode around. Otherwise someone else lended their hold count and
	* we have to drop ours.
	*/
	- if (vp->v_type != VCHR &&
	- refcount_acquire_if_not_zero(&vp->v_usecount)) {
	+ if (refcount_acquire_if_not_zero(&vp->v_usecount)) {
	#ifdef INVARIANTS
	int old = atomic_fetchadd_int(&vp->v_holdcnt, -1) - 1;
	VNASSERT(old > 0, vp, ("%s: wrong hold count", __func__));
	@@ -2793,7 +2745,6 @@
	}
	if (vp->v_usecount > 0)
	refcount_release(&vp->v_holdcnt);
	- v_incr_devcount(vp);
	refcount_acquire(&vp->v_usecount);
	if (oweinact && VOP_ISLOCKED(vp) == LK_EXCLUSIVE &&
	(flags & LK_NOWAIT) == 0)
	@@ -2812,8 +2763,7 @@

	ASSERT_VI_UNLOCKED(vp, __func__);
	CTR2(KTR_VFS, "%s: vp %p", __func__, vp);
	- if (vp->v_type != VCHR &&
	- refcount_acquire_if_not_zero(&vp->v_usecount)) {
	+ if (refcount_acquire_if_not_zero(&vp->v_usecount)) {
	VNODE_REFCOUNT_FENCE_ACQ();
	VNASSERT(vp->v_holdcnt > 0, vp,
	("%s: active vnode not held", __func__));
	@@ -2838,7 +2788,6 @@
	vp->v_iflag &= ~VI_OWEINACT;
	VNODE_REFCOUNT_FENCE_REL();
	}
	- v_incr_devcount(vp);
	refcount_acquire(&vp->v_usecount);
	}

	@@ -2847,12 +2796,6 @@
	{

	CTR2(KTR_VFS, "%s: vp %p", __func__, vp);
	- if (__predict_false(vp->v_type == VCHR)) {
	- VNASSERT(vp->v_holdcnt > 0 && vp->v_usecount > 0, vp,
	- ("%s: wrong ref counts", __func__));
	- vref(vp);
	- return;
	- }
	#ifdef INVARIANTS
	int old = atomic_fetchadd_int(&vp->v_usecount, 1);
	VNASSERT(old > 0, vp, ("%s: wrong use count", __func__));
	@@ -2917,8 +2860,7 @@
	if (func == VPUTX_VPUT)
	VOP_UNLOCK(vp, 0);

	- if (vp->v_type != VCHR &&
	- refcount_release_if_not_last(&vp->v_usecount))
	+ if (refcount_release_if_not_last(&vp->v_usecount))
	return;

	VI_LOCK(vp);
	@@ -2928,7 +2870,6 @@
	* prevent vgone() races. We drop the use count here and the
	* hold count below when we're done.
	*/
	- v_decr_devcount(vp);
	if (!refcount_release(&vp->v_usecount)) {
	VI_UNLOCK(vp);
	return;
	@@ -3083,6 +3024,13 @@
	mp->mnt_activevnodelistsize++;
	mtx_unlock(&mp->mnt_listmtx);
	refcount_acquire(&vp->v_holdcnt);
	+ if (vp->v_rdev != NULL) {
	+ VNASSERT(vp->v_type == VCHR, vp,
	+ ("vdropl: non-VCHR vnode with v_rdev"));
	+ dev_lock();
	+ dev_vn_table_add(vp->v_rdev, vp);
	+ dev_unlock();
	+ }
	if (!locked)
	VI_UNLOCK(vp);
	}
	@@ -3145,6 +3093,13 @@
	("vnode already free"));
	VNASSERT(vp->v_holdcnt == 0, vp,
	("vdropl: freeing when we shouldn't"));
	+ if (vp->v_rdev != NULL) {
	+ VNASSERT(vp->v_type == VCHR, vp,
	+ ("vdropl: non-VCHR vnode with v_rdev"));
	+ dev_lock();
	+ dev_vn_table_remove(vp->v_rdev, vp);
	+ dev_unlock();
	+ }
	active = vp->v_iflag & VI_ACTIVE;
	if ((vp->v_iflag & VI_OWEINACT) == 0) {
	vp->v_iflag &= ~VI_ACTIVE;
	@@ -3652,12 +3607,8 @@
	int
	vcount(struct vnode *vp)
	{
	- int count;

	- dev_lock();
	- count = vp->v_rdev->si_usecount;
	- dev_unlock();
	- return (count);
	+ return (count_dev(vp->v_rdev));
	}

	/*
	@@ -3666,12 +3617,38 @@
	int
	count_dev(struct cdev *dev)
	{
	- int count;
	+ int count, i;
	+
	+ count = 0;
	+ dev_lock();
	+ for (i = 0; i < dev->si_vnodes_index; i++) {
	+ count += dev->si_vnodes[i]->v_usecount;
	+ }
	+ dev_unlock();
	+ return (count);
	+}
	+
	+int
	+count_dev_cmp(struct cdev *dev, int n)
	+{
	+ int count, i, ret;

	+ count = 0;
	dev_lock();
	- count = dev->si_usecount;
	+ for (i = 0; i < dev->si_vnodes_index; i++) {
	+ count += dev->si_vnodes[i]->v_usecount;
	+ if (count > n) {
	+ ret = 1;
	+ goto out;
	+ }
	+ }
	+ if (count == n)
	+ ret = 0;
	+ else
	+ ret = -1;
	+out:
	dev_unlock();
	- return(count);
	+ return (ret);
	}

	/*
	Index: sys/sys/conf.h
	===================================================================
	--- sys/sys/conf.h
	+++ sys/sys/conf.h
	@@ -83,12 +83,16 @@
	void si_drv1, si_drv2;
	struct cdevsw *si_devsw;
	int si_iosize_max; /* maximum I/O size (for physio &al) */
	- u_long si_usecount;
	u_long si_threadcount;
	+ struct vnode **si_vnodes;
	+ int si_vnodes_index;
	+ int si_vnodes_size;
	+ int si_vnodes_assigned;
	union {
	struct snapdata *__sid_snapdata;
	} __si_u;
	char si_name[SPECNAMELEN + 1];
	+ struct vnode *si_vnodes_local[2];
	};

	#define si_snapdata __si_u.__sid_snapdata
	@@ -256,7 +260,10 @@
	#define make_dev_args_init(a) \
	make_dev_args_init_impl((a), sizeof(struct make_dev_args))

	+void dev_vn_table_add(struct cdev dev, struct vnode vp);
	+void dev_vn_table_remove(struct cdev dev, struct vnode vp);
	int count_dev(struct cdev *_dev);
	+int count_dev_cmp(struct cdev *_dev, int n);
	void delist_dev(struct cdev *_dev);
	void destroy_dev(struct cdev *_dev);
	int destroy_dev_sched(struct cdev *dev);

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