File: [cvs.NetBSD.org] / src / sys / kern / vfs_vnode.c (download)
Revision 1.30, Sat Dec 7 10:03:28 2013 UTC (10 years, 4 months ago) by hannken
Branch: MAIN
Changes since 1.29: +12 -28
lines
When deciding to defer in vrelel():
- No need to always defer layer vnodes, if we get the vnode lock it
is safe to inactivate.
- Always use VOP_LOCK(), it makes no sense to use vn_lock() here.
- No need to drop v_interlock for VOP_LOCK(... LK_NOWAIT).
|
/* $NetBSD: vfs_vnode.c,v 1.30 2013/12/07 10:03:28 hannken Exp $ */
/*-
* Copyright (c) 1997-2011 The NetBSD Foundation, Inc.
* All rights reserved.
*
* This code is derived from software contributed to The NetBSD Foundation
* by Jason R. Thorpe of the Numerical Aerospace Simulation Facility,
* NASA Ames Research Center, by Charles M. Hannum, and by Andrew Doran.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
* ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
* TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
* BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGE.
*/
/*
* Copyright (c) 1989, 1993
* The Regents of the University of California. All rights reserved.
* (c) UNIX System Laboratories, Inc.
* All or some portions of this file are derived from material licensed
* to the University of California by American Telephone and Telegraph
* Co. or Unix System Laboratories, Inc. and are reproduced herein with
* the permission of UNIX System Laboratories, Inc.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. Neither the name of the University nor the names of its contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*
* @(#)vfs_subr.c 8.13 (Berkeley) 4/18/94
*/
/*
* The vnode cache subsystem.
*
* Life-cycle
*
* Normally, there are two points where new vnodes are created:
* VOP_CREATE(9) and VOP_LOOKUP(9). The life-cycle of a vnode
* starts in one of the following ways:
*
* - Allocation, via getnewvnode(9) and/or vnalloc(9).
* - Reclamation of inactive vnode, via vget(9).
*
* Recycle from a free list, via getnewvnode(9) -> getcleanvnode(9)
* was another, traditional way. Currently, only the draining thread
* recycles the vnodes. This behaviour might be revisited.
*
* The life-cycle ends when the last reference is dropped, usually
* in VOP_REMOVE(9). In such case, VOP_INACTIVE(9) is called to inform
* the file system that vnode is inactive. Via this call, file system
* indicates whether vnode can be recycled (usually, it checks its own
* references, e.g. count of links, whether the file was removed).
*
* Depending on indication, vnode can be put into a free list (cache),
* or cleaned via vclean(9), which calls VOP_RECLAIM(9) to disassociate
* underlying file system from the vnode, and finally destroyed.
*
* Reference counting
*
* Vnode is considered active, if reference count (vnode_t::v_usecount)
* is non-zero. It is maintained using: vref(9) and vrele(9), as well
* as vput(9), routines. Common points holding references are e.g.
* file openings, current working directory, mount points, etc.
*
* Note on v_usecount and its locking
*
* At nearly all points it is known that v_usecount could be zero,
* the vnode_t::v_interlock will be held. To change v_usecount away
* from zero, the interlock must be held. To change from a non-zero
* value to zero, again the interlock must be held.
*
* Changing the usecount from a non-zero value to a non-zero value can
* safely be done using atomic operations, without the interlock held.
*
* Note: if VI_CLEAN is set, vnode_t::v_interlock will be released while
* mntvnode_lock is still held.
*
* See PR 41374.
*/
#include <sys/cdefs.h>
__KERNEL_RCSID(0, "$NetBSD: vfs_vnode.c,v 1.30 2013/12/07 10:03:28 hannken Exp $");
#define _VFS_VNODE_PRIVATE
#include <sys/param.h>
#include <sys/kernel.h>
#include <sys/atomic.h>
#include <sys/buf.h>
#include <sys/conf.h>
#include <sys/device.h>
#include <sys/kauth.h>
#include <sys/kmem.h>
#include <sys/kthread.h>
#include <sys/module.h>
#include <sys/mount.h>
#include <sys/namei.h>
#include <sys/syscallargs.h>
#include <sys/sysctl.h>
#include <sys/systm.h>
#include <sys/vnode.h>
#include <sys/wapbl.h>
#include <sys/fstrans.h>
#include <uvm/uvm.h>
#include <uvm/uvm_readahead.h>
/* Flags to vrelel. */
#define VRELEL_ASYNC_RELE 0x0001 /* Always defer to vrele thread. */
#define VRELEL_CHANGING_SET 0x0002 /* VI_CHANGING set by caller. */
u_int numvnodes __cacheline_aligned;
static pool_cache_t vnode_cache __read_mostly;
/*
* There are two free lists: one is for vnodes which have no buffer/page
* references and one for those which do (i.e. v_holdcnt is non-zero).
* Vnode recycling mechanism first attempts to look into the former list.
*/
static kmutex_t vnode_free_list_lock __cacheline_aligned;
static vnodelst_t vnode_free_list __cacheline_aligned;
static vnodelst_t vnode_hold_list __cacheline_aligned;
static kcondvar_t vdrain_cv __cacheline_aligned;
static vnodelst_t vrele_list __cacheline_aligned;
static kmutex_t vrele_lock __cacheline_aligned;
static kcondvar_t vrele_cv __cacheline_aligned;
static lwp_t * vrele_lwp __cacheline_aligned;
static int vrele_pending __cacheline_aligned;
static int vrele_gen __cacheline_aligned;
static int cleanvnode(void);
static void vclean(vnode_t *);
static void vrelel(vnode_t *, int);
static void vdrain_thread(void *);
static void vrele_thread(void *);
static void vnpanic(vnode_t *, const char *, ...)
__printflike(2, 3);
/* Routines having to do with the management of the vnode table. */
extern int (**dead_vnodeop_p)(void *);
void
vfs_vnode_sysinit(void)
{
int error __diagused;
vnode_cache = pool_cache_init(sizeof(vnode_t), 0, 0, 0, "vnodepl",
NULL, IPL_NONE, NULL, NULL, NULL);
KASSERT(vnode_cache != NULL);
mutex_init(&vnode_free_list_lock, MUTEX_DEFAULT, IPL_NONE);
TAILQ_INIT(&vnode_free_list);
TAILQ_INIT(&vnode_hold_list);
TAILQ_INIT(&vrele_list);
mutex_init(&vrele_lock, MUTEX_DEFAULT, IPL_NONE);
cv_init(&vdrain_cv, "vdrain");
cv_init(&vrele_cv, "vrele");
error = kthread_create(PRI_VM, KTHREAD_MPSAFE, NULL, vdrain_thread,
NULL, NULL, "vdrain");
KASSERT(error == 0);
error = kthread_create(PRI_VM, KTHREAD_MPSAFE, NULL, vrele_thread,
NULL, &vrele_lwp, "vrele");
KASSERT(error == 0);
}
/*
* Allocate a new, uninitialized vnode. If 'mp' is non-NULL, this is a
* marker vnode.
*/
vnode_t *
vnalloc(struct mount *mp)
{
vnode_t *vp;
vp = pool_cache_get(vnode_cache, PR_WAITOK);
KASSERT(vp != NULL);
memset(vp, 0, sizeof(*vp));
uvm_obj_init(&vp->v_uobj, &uvm_vnodeops, true, 0);
cv_init(&vp->v_cv, "vnode");
/*
* Done by memset() above.
* LIST_INIT(&vp->v_nclist);
* LIST_INIT(&vp->v_dnclist);
*/
if (mp != NULL) {
vp->v_mount = mp;
vp->v_type = VBAD;
vp->v_iflag = VI_MARKER;
} else {
rw_init(&vp->v_lock);
}
return vp;
}
/*
* Free an unused, unreferenced vnode.
*/
void
vnfree(vnode_t *vp)
{
KASSERT(vp->v_usecount == 0);
if ((vp->v_iflag & VI_MARKER) == 0) {
rw_destroy(&vp->v_lock);
mutex_enter(&vnode_free_list_lock);
numvnodes--;
mutex_exit(&vnode_free_list_lock);
}
/*
* Note: the vnode interlock will either be freed, of reference
* dropped (if VI_LOCKSHARE was in use).
*/
uvm_obj_destroy(&vp->v_uobj, true);
cv_destroy(&vp->v_cv);
pool_cache_put(vnode_cache, vp);
}
/*
* cleanvnode: grab a vnode from freelist, clean and free it.
*
* => Releases vnode_free_list_lock.
*/
static int
cleanvnode(void)
{
vnode_t *vp;
vnodelst_t *listhd;
struct mount *mp;
KASSERT(mutex_owned(&vnode_free_list_lock));
listhd = &vnode_free_list;
try_nextlist:
TAILQ_FOREACH(vp, listhd, v_freelist) {
/*
* It's safe to test v_usecount and v_iflag
* without holding the interlock here, since
* these vnodes should never appear on the
* lists.
*/
KASSERT(vp->v_usecount == 0);
KASSERT((vp->v_iflag & VI_CLEAN) == 0);
KASSERT(vp->v_freelisthd == listhd);
if (!mutex_tryenter(vp->v_interlock))
continue;
if ((vp->v_iflag & VI_XLOCK) != 0) {
mutex_exit(vp->v_interlock);
continue;
}
mp = vp->v_mount;
if (fstrans_start_nowait(mp, FSTRANS_SHARED) != 0) {
mutex_exit(vp->v_interlock);
continue;
}
break;
}
if (vp == NULL) {
if (listhd == &vnode_free_list) {
listhd = &vnode_hold_list;
goto try_nextlist;
}
mutex_exit(&vnode_free_list_lock);
return EBUSY;
}
/* Remove it from the freelist. */
TAILQ_REMOVE(listhd, vp, v_freelist);
vp->v_freelisthd = NULL;
mutex_exit(&vnode_free_list_lock);
KASSERT(vp->v_usecount == 0);
/*
* The vnode is still associated with a file system, so we must
* clean it out before freeing it. We need to add a reference
* before doing this.
*/
vp->v_usecount = 1;
KASSERT((vp->v_iflag & VI_CHANGING) == 0);
vp->v_iflag |= VI_CHANGING;
vclean(vp);
vrelel(vp, VRELEL_CHANGING_SET);
fstrans_done(mp);
return 0;
}
/*
* getnewvnode: return a fresh vnode.
*
* => Returns referenced vnode, moved into the mount queue.
* => Shares the interlock specified by 'slock', if it is not NULL.
*/
int
getnewvnode(enum vtagtype tag, struct mount *mp, int (**vops)(void *),
kmutex_t *slock, vnode_t **vpp)
{
struct uvm_object *uobj __diagused;
vnode_t *vp;
int error = 0;
if (mp != NULL) {
/*
* Mark filesystem busy while we are creating a vnode.
* If unmount is in progress, this will fail.
*/
error = vfs_busy(mp, NULL);
if (error)
return error;
}
vp = NULL;
/* Allocate a new vnode. */
mutex_enter(&vnode_free_list_lock);
numvnodes++;
if (numvnodes > desiredvnodes + desiredvnodes / 10)
cv_signal(&vdrain_cv);
mutex_exit(&vnode_free_list_lock);
vp = vnalloc(NULL);
KASSERT(vp->v_freelisthd == NULL);
KASSERT(LIST_EMPTY(&vp->v_nclist));
KASSERT(LIST_EMPTY(&vp->v_dnclist));
/* Initialize vnode. */
vp->v_usecount = 1;
vp->v_type = VNON;
vp->v_tag = tag;
vp->v_op = vops;
vp->v_data = NULL;
uobj = &vp->v_uobj;
KASSERT(uobj->pgops == &uvm_vnodeops);
KASSERT(uobj->uo_npages == 0);
KASSERT(TAILQ_FIRST(&uobj->memq) == NULL);
vp->v_size = vp->v_writesize = VSIZENOTSET;
/* Share the vnode_t::v_interlock, if requested. */
if (slock) {
/* Set the interlock and mark that it is shared. */
KASSERT(vp->v_mount == NULL);
mutex_obj_hold(slock);
uvm_obj_setlock(&vp->v_uobj, slock);
KASSERT(vp->v_interlock == slock);
vp->v_iflag |= VI_LOCKSHARE;
}
/* Finally, move vnode into the mount queue. */
vfs_insmntque(vp, mp);
if (mp != NULL) {
if ((mp->mnt_iflag & IMNT_MPSAFE) != 0)
vp->v_vflag |= VV_MPSAFE;
vfs_unbusy(mp, true, NULL);
}
*vpp = vp;
return 0;
}
/*
* This is really just the reverse of getnewvnode(). Needed for
* VFS_VGET functions who may need to push back a vnode in case
* of a locking race.
*/
void
ungetnewvnode(vnode_t *vp)
{
KASSERT(vp->v_usecount == 1);
KASSERT(vp->v_data == NULL);
KASSERT(vp->v_freelisthd == NULL);
mutex_enter(vp->v_interlock);
vp->v_iflag |= VI_CLEAN;
vrelel(vp, 0);
}
/*
* Helper thread to keep the number of vnodes below desiredvnodes.
*/
static void
vdrain_thread(void *cookie)
{
int error;
mutex_enter(&vnode_free_list_lock);
for (;;) {
cv_timedwait(&vdrain_cv, &vnode_free_list_lock, hz);
while (numvnodes > desiredvnodes) {
error = cleanvnode();
if (error)
kpause("vndsbusy", false, hz, NULL);
mutex_enter(&vnode_free_list_lock);
if (error)
break;
}
}
}
/*
* Remove a vnode from its freelist.
*/
void
vremfree(vnode_t *vp)
{
KASSERT(mutex_owned(vp->v_interlock));
KASSERT(vp->v_usecount == 0);
/*
* Note that the reference count must not change until
* the vnode is removed.
*/
mutex_enter(&vnode_free_list_lock);
if (vp->v_holdcnt > 0) {
KASSERT(vp->v_freelisthd == &vnode_hold_list);
} else {
KASSERT(vp->v_freelisthd == &vnode_free_list);
}
TAILQ_REMOVE(vp->v_freelisthd, vp, v_freelist);
vp->v_freelisthd = NULL;
mutex_exit(&vnode_free_list_lock);
}
/*
* vget: get a particular vnode from the free list, increment its reference
* count and lock it.
*
* => Should be called with v_interlock held.
*
* If VI_CHANGING is set, the vnode may be eliminated in vgone()/vclean().
* In that case, we cannot grab the vnode, so the process is awakened when
* the transition is completed, and an error returned to indicate that the
* vnode is no longer usable.
*/
int
vget(vnode_t *vp, int flags)
{
int error = 0;
KASSERT((vp->v_iflag & VI_MARKER) == 0);
KASSERT(mutex_owned(vp->v_interlock));
KASSERT((flags & ~(LK_SHARED|LK_EXCLUSIVE|LK_NOWAIT)) == 0);
/*
* Before adding a reference, we must remove the vnode
* from its freelist.
*/
if (vp->v_usecount == 0) {
vremfree(vp);
vp->v_usecount = 1;
} else {
atomic_inc_uint(&vp->v_usecount);
}
/*
* If the vnode is in the process of changing state we wait
* for the change to complete and take care not to return
* a clean vnode.
*/
if ((vp->v_iflag & VI_CHANGING) != 0) {
if ((flags & LK_NOWAIT) != 0) {
vrelel(vp, 0);
return EBUSY;
}
vwait(vp, VI_CHANGING);
if ((vp->v_iflag & VI_CLEAN) != 0) {
vrelel(vp, 0);
return ENOENT;
}
}
/*
* Ok, we got it in good shape. Just locking left.
*/
KASSERT((vp->v_iflag & VI_CLEAN) == 0);
mutex_exit(vp->v_interlock);
if (flags & (LK_EXCLUSIVE | LK_SHARED)) {
error = vn_lock(vp, flags);
if (error != 0) {
vrele(vp);
}
}
return error;
}
/*
* vput: unlock and release the reference.
*/
void
vput(vnode_t *vp)
{
KASSERT((vp->v_iflag & VI_MARKER) == 0);
VOP_UNLOCK(vp);
vrele(vp);
}
/*
* Try to drop reference on a vnode. Abort if we are releasing the
* last reference. Note: this _must_ succeed if not the last reference.
*/
static inline bool
vtryrele(vnode_t *vp)
{
u_int use, next;
for (use = vp->v_usecount;; use = next) {
if (use == 1) {
return false;
}
KASSERT(use > 1);
next = atomic_cas_uint(&vp->v_usecount, use, use - 1);
if (__predict_true(next == use)) {
return true;
}
}
}
/*
* Vnode release. If reference count drops to zero, call inactive
* routine and either return to freelist or free to the pool.
*/
static void
vrelel(vnode_t *vp, int flags)
{
bool recycle, defer;
int error;
KASSERT(mutex_owned(vp->v_interlock));
KASSERT((vp->v_iflag & VI_MARKER) == 0);
KASSERT(vp->v_freelisthd == NULL);
if (__predict_false(vp->v_op == dead_vnodeop_p &&
(vp->v_iflag & (VI_CLEAN|VI_XLOCK)) == 0)) {
vnpanic(vp, "dead but not clean");
}
/*
* If not the last reference, just drop the reference count
* and unlock.
*/
if (vtryrele(vp)) {
if ((flags & VRELEL_CHANGING_SET) != 0) {
KASSERT((vp->v_iflag & VI_CHANGING) != 0);
vp->v_iflag &= ~VI_CHANGING;
cv_broadcast(&vp->v_cv);
}
mutex_exit(vp->v_interlock);
return;
}
if (vp->v_usecount <= 0 || vp->v_writecount != 0) {
vnpanic(vp, "%s: bad ref count", __func__);
}
KASSERT((vp->v_iflag & VI_XLOCK) == 0);
#ifdef DIAGNOSTIC
if ((vp->v_type == VBLK || vp->v_type == VCHR) &&
vp->v_specnode != NULL && vp->v_specnode->sn_opencnt != 0) {
vprint("vrelel: missing VOP_CLOSE()", vp);
}
#endif
/*
* If not clean, deactivate the vnode, but preserve
* our reference across the call to VOP_INACTIVE().
*/
if ((vp->v_iflag & VI_CLEAN) == 0) {
recycle = false;
/*
* XXX This ugly block can be largely eliminated if
* locking is pushed down into the file systems.
*
* Defer vnode release to vrele_thread if caller
* requests it explicitly or is the pagedaemon.
*/
if ((curlwp == uvm.pagedaemon_lwp) ||
(flags & VRELEL_ASYNC_RELE) != 0) {
defer = true;
} else if (curlwp == vrele_lwp) {
/*
* We have to try harder.
*/
mutex_exit(vp->v_interlock);
error = VOP_LOCK(vp, LK_EXCLUSIVE);
KASSERT(error == 0);
mutex_enter(vp->v_interlock);
/*
* If the node got another reference while sleeping,
* don't try to inactivate it yet.
*/
if (__predict_false(vtryrele(vp))) {
VOP_UNLOCK(vp);
if ((flags & VRELEL_CHANGING_SET) != 0) {
KASSERT((vp->v_iflag & VI_CHANGING) != 0);
vp->v_iflag &= ~VI_CHANGING;
cv_broadcast(&vp->v_cv);
}
mutex_exit(vp->v_interlock);
return;
}
defer = false;
} else {
/* If we can't acquire the lock, then defer. */
error = VOP_LOCK(vp, LK_EXCLUSIVE | LK_NOWAIT);
defer = (error != 0);
}
KASSERT(mutex_owned(vp->v_interlock));
KASSERT(! (curlwp == vrele_lwp && defer));
if (defer) {
/*
* Defer reclaim to the kthread; it's not safe to
* clean it here. We donate it our last reference.
*/
if ((flags & VRELEL_CHANGING_SET) != 0) {
KASSERT((vp->v_iflag & VI_CHANGING) != 0);
vp->v_iflag &= ~VI_CHANGING;
cv_broadcast(&vp->v_cv);
}
mutex_enter(&vrele_lock);
TAILQ_INSERT_TAIL(&vrele_list, vp, v_freelist);
if (++vrele_pending > (desiredvnodes >> 8))
cv_signal(&vrele_cv);
mutex_exit(&vrele_lock);
mutex_exit(vp->v_interlock);
return;
}
if ((flags & VRELEL_CHANGING_SET) == 0) {
KASSERT((vp->v_iflag & VI_CHANGING) == 0);
vp->v_iflag |= VI_CHANGING;
}
mutex_exit(vp->v_interlock);
/*
* The vnode can gain another reference while being
* deactivated. If VOP_INACTIVE() indicates that
* the described file has been deleted, then recycle
* the vnode irrespective of additional references.
* Another thread may be waiting to re-use the on-disk
* inode.
*
* Note that VOP_INACTIVE() will drop the vnode lock.
*/
VOP_INACTIVE(vp, &recycle);
mutex_enter(vp->v_interlock);
if (!recycle) {
if (vtryrele(vp)) {
KASSERT((vp->v_iflag & VI_CHANGING) != 0);
vp->v_iflag &= ~VI_CHANGING;
cv_broadcast(&vp->v_cv);
mutex_exit(vp->v_interlock);
return;
}
}
/* Take care of space accounting. */
if (vp->v_iflag & VI_EXECMAP) {
atomic_add_int(&uvmexp.execpages,
-vp->v_uobj.uo_npages);
atomic_add_int(&uvmexp.filepages,
vp->v_uobj.uo_npages);
}
vp->v_iflag &= ~(VI_TEXT|VI_EXECMAP|VI_WRMAP);
vp->v_vflag &= ~VV_MAPPED;
/*
* Recycle the vnode if the file is now unused (unlinked),
* otherwise just free it.
*/
if (recycle) {
vclean(vp);
}
KASSERT(vp->v_usecount > 0);
} else { /* vnode was already clean */
if ((flags & VRELEL_CHANGING_SET) == 0) {
KASSERT((vp->v_iflag & VI_CHANGING) == 0);
vp->v_iflag |= VI_CHANGING;
}
}
if (atomic_dec_uint_nv(&vp->v_usecount) != 0) {
/* Gained another reference while being reclaimed. */
KASSERT((vp->v_iflag & VI_CHANGING) != 0);
vp->v_iflag &= ~VI_CHANGING;
cv_broadcast(&vp->v_cv);
mutex_exit(vp->v_interlock);
return;
}
if ((vp->v_iflag & VI_CLEAN) != 0) {
/*
* It's clean so destroy it. It isn't referenced
* anywhere since it has been reclaimed.
*/
KASSERT(vp->v_holdcnt == 0);
KASSERT(vp->v_writecount == 0);
mutex_exit(vp->v_interlock);
vfs_insmntque(vp, NULL);
if (vp->v_type == VBLK || vp->v_type == VCHR) {
spec_node_destroy(vp);
}
vnfree(vp);
} else {
/*
* Otherwise, put it back onto the freelist. It
* can't be destroyed while still associated with
* a file system.
*/
mutex_enter(&vnode_free_list_lock);
if (vp->v_holdcnt > 0) {
vp->v_freelisthd = &vnode_hold_list;
} else {
vp->v_freelisthd = &vnode_free_list;
}
TAILQ_INSERT_TAIL(vp->v_freelisthd, vp, v_freelist);
mutex_exit(&vnode_free_list_lock);
KASSERT((vp->v_iflag & VI_CHANGING) != 0);
vp->v_iflag &= ~VI_CHANGING;
cv_broadcast(&vp->v_cv);
mutex_exit(vp->v_interlock);
}
}
void
vrele(vnode_t *vp)
{
KASSERT((vp->v_iflag & VI_MARKER) == 0);
if (vtryrele(vp)) {
return;
}
mutex_enter(vp->v_interlock);
vrelel(vp, 0);
}
/*
* Asynchronous vnode release, vnode is released in different context.
*/
void
vrele_async(vnode_t *vp)
{
KASSERT((vp->v_iflag & VI_MARKER) == 0);
if (vtryrele(vp)) {
return;
}
mutex_enter(vp->v_interlock);
vrelel(vp, VRELEL_ASYNC_RELE);
}
static void
vrele_thread(void *cookie)
{
vnode_t *vp;
for (;;) {
mutex_enter(&vrele_lock);
while (TAILQ_EMPTY(&vrele_list)) {
vrele_gen++;
cv_broadcast(&vrele_cv);
cv_timedwait(&vrele_cv, &vrele_lock, hz);
}
vp = TAILQ_FIRST(&vrele_list);
TAILQ_REMOVE(&vrele_list, vp, v_freelist);
vrele_pending--;
mutex_exit(&vrele_lock);
/*
* If not the last reference, then ignore the vnode
* and look for more work.
*/
mutex_enter(vp->v_interlock);
vrelel(vp, 0);
}
}
void
vrele_flush(void)
{
int gen;
mutex_enter(&vrele_lock);
gen = vrele_gen;
while (vrele_pending && gen == vrele_gen) {
cv_broadcast(&vrele_cv);
cv_wait(&vrele_cv, &vrele_lock);
}
mutex_exit(&vrele_lock);
}
/*
* Vnode reference, where a reference is already held by some other
* object (for example, a file structure).
*/
void
vref(vnode_t *vp)
{
KASSERT((vp->v_iflag & VI_MARKER) == 0);
KASSERT(vp->v_usecount != 0);
atomic_inc_uint(&vp->v_usecount);
}
/*
* Page or buffer structure gets a reference.
* Called with v_interlock held.
*/
void
vholdl(vnode_t *vp)
{
KASSERT(mutex_owned(vp->v_interlock));
KASSERT((vp->v_iflag & VI_MARKER) == 0);
if (vp->v_holdcnt++ == 0 && vp->v_usecount == 0) {
mutex_enter(&vnode_free_list_lock);
KASSERT(vp->v_freelisthd == &vnode_free_list);
TAILQ_REMOVE(vp->v_freelisthd, vp, v_freelist);
vp->v_freelisthd = &vnode_hold_list;
TAILQ_INSERT_TAIL(vp->v_freelisthd, vp, v_freelist);
mutex_exit(&vnode_free_list_lock);
}
}
/*
* Page or buffer structure frees a reference.
* Called with v_interlock held.
*/
void
holdrelel(vnode_t *vp)
{
KASSERT(mutex_owned(vp->v_interlock));
KASSERT((vp->v_iflag & VI_MARKER) == 0);
if (vp->v_holdcnt <= 0) {
vnpanic(vp, "%s: holdcnt vp %p", __func__, vp);
}
vp->v_holdcnt--;
if (vp->v_holdcnt == 0 && vp->v_usecount == 0) {
mutex_enter(&vnode_free_list_lock);
KASSERT(vp->v_freelisthd == &vnode_hold_list);
TAILQ_REMOVE(vp->v_freelisthd, vp, v_freelist);
vp->v_freelisthd = &vnode_free_list;
TAILQ_INSERT_TAIL(vp->v_freelisthd, vp, v_freelist);
mutex_exit(&vnode_free_list_lock);
}
}
/*
* Disassociate the underlying file system from a vnode.
*
* Must be called with the interlock held, and will return with it held.
*/
static void
vclean(vnode_t *vp)
{
lwp_t *l = curlwp;
bool recycle, active, doclose;
int error;
KASSERT(mutex_owned(vp->v_interlock));
KASSERT((vp->v_iflag & VI_MARKER) == 0);
KASSERT(vp->v_usecount != 0);
/* If cleaning is already in progress wait until done and return. */
if (vp->v_iflag & VI_XLOCK) {
vwait(vp, VI_XLOCK);
return;
}
/* If already clean, nothing to do. */
if ((vp->v_iflag & VI_CLEAN) != 0) {
return;
}
/*
* Prevent the vnode from being recycled or brought into use
* while we clean it out.
*/
vp->v_iflag |= VI_XLOCK;
if (vp->v_iflag & VI_EXECMAP) {
atomic_add_int(&uvmexp.execpages, -vp->v_uobj.uo_npages);
atomic_add_int(&uvmexp.filepages, vp->v_uobj.uo_npages);
}
vp->v_iflag &= ~(VI_TEXT|VI_EXECMAP);
active = (vp->v_usecount > 1);
/* XXXAD should not lock vnode under layer */
mutex_exit(vp->v_interlock);
VOP_LOCK(vp, LK_EXCLUSIVE);
doclose = ! (active && vp->v_type == VBLK &&
spec_node_getmountedfs(vp) != NULL);
/*
* Clean out any cached data associated with the vnode.
* If purging an active vnode, it must be closed and
* deactivated before being reclaimed. Note that the
* VOP_INACTIVE will unlock the vnode.
*/
if (doclose) {
error = vinvalbuf(vp, V_SAVE, NOCRED, l, 0, 0);
if (error != 0) {
if (wapbl_vphaswapbl(vp))
WAPBL_DISCARD(wapbl_vptomp(vp));
error = vinvalbuf(vp, 0, NOCRED, l, 0, 0);
}
KASSERT(error == 0);
KASSERT((vp->v_iflag & VI_ONWORKLST) == 0);
if (active && (vp->v_type == VBLK || vp->v_type == VCHR)) {
spec_node_revoke(vp);
}
}
if (active) {
VOP_INACTIVE(vp, &recycle);
} else {
/*
* Any other processes trying to obtain this lock must first
* wait for VI_XLOCK to clear, then call the new lock operation.
*/
VOP_UNLOCK(vp);
}
/* Disassociate the underlying file system from the vnode. */
if (VOP_RECLAIM(vp)) {
vnpanic(vp, "%s: cannot reclaim", __func__);
}
KASSERT(vp->v_data == NULL);
KASSERT(vp->v_uobj.uo_npages == 0);
if (vp->v_type == VREG && vp->v_ractx != NULL) {
uvm_ra_freectx(vp->v_ractx);
vp->v_ractx = NULL;
}
/* Purge name cache. */
cache_purge(vp);
/*
* The vnode isn't clean, but still resides on the mount list. Remove
* it. XXX This is a bit dodgy.
*/
if (! doclose)
vfs_insmntque(vp, NULL);
/* Done with purge, notify sleepers of the grim news. */
mutex_enter(vp->v_interlock);
if (doclose) {
vp->v_op = dead_vnodeop_p;
vp->v_vflag |= VV_LOCKSWORK;
vp->v_iflag |= VI_CLEAN;
} else {
vp->v_op = spec_vnodeop_p;
vp->v_vflag &= ~VV_LOCKSWORK;
}
vp->v_tag = VT_NON;
KNOTE(&vp->v_klist, NOTE_REVOKE);
vp->v_iflag &= ~VI_XLOCK;
cv_broadcast(&vp->v_cv);
KASSERT((vp->v_iflag & VI_ONWORKLST) == 0);
}
/*
* Recycle an unused vnode to the front of the free list.
* Release the passed interlock if the vnode will be recycled.
*/
int
vrecycle(vnode_t *vp, kmutex_t *inter_lkp)
{
KASSERT((vp->v_iflag & VI_MARKER) == 0);
mutex_enter(vp->v_interlock);
if (vp->v_usecount != 0 || (vp->v_iflag & (VI_CLEAN|VI_XLOCK)) != 0) {
mutex_exit(vp->v_interlock);
return 0;
}
if (inter_lkp) {
mutex_exit(inter_lkp);
}
vremfree(vp);
vp->v_usecount = 1;
KASSERT((vp->v_iflag & VI_CHANGING) == 0);
vp->v_iflag |= VI_CHANGING;
vclean(vp);
vrelel(vp, VRELEL_CHANGING_SET);
return 1;
}
/*
* Eliminate all activity associated with the requested vnode
* and with all vnodes aliased to the requested vnode.
*/
void
vrevoke(vnode_t *vp)
{
vnode_t *vq;
enum vtype type;
dev_t dev;
KASSERT(vp->v_usecount > 0);
mutex_enter(vp->v_interlock);
if ((vp->v_iflag & VI_CLEAN) != 0) {
mutex_exit(vp->v_interlock);
return;
} else if (vp->v_type != VBLK && vp->v_type != VCHR) {
atomic_inc_uint(&vp->v_usecount);
mutex_exit(vp->v_interlock);
vgone(vp);
return;
} else {
dev = vp->v_rdev;
type = vp->v_type;
mutex_exit(vp->v_interlock);
}
while (spec_node_lookup_by_dev(type, dev, &vq) == 0) {
vgone(vq);
}
}
/*
* Eliminate all activity associated with a vnode in preparation for
* reuse. Drops a reference from the vnode.
*/
void
vgone(vnode_t *vp)
{
mutex_enter(vp->v_interlock);
if ((vp->v_iflag & VI_CHANGING) != 0)
vwait(vp, VI_CHANGING);
vp->v_iflag |= VI_CHANGING;
vclean(vp);
vrelel(vp, VRELEL_CHANGING_SET);
}
/*
* Update outstanding I/O count and do wakeup if requested.
*/
void
vwakeup(struct buf *bp)
{
vnode_t *vp;
if ((vp = bp->b_vp) == NULL)
return;
KASSERT(bp->b_objlock == vp->v_interlock);
KASSERT(mutex_owned(bp->b_objlock));
if (--vp->v_numoutput < 0)
vnpanic(vp, "%s: neg numoutput, vp %p", __func__, vp);
if (vp->v_numoutput == 0)
cv_broadcast(&vp->v_cv);
}
/*
* Wait for a vnode (typically with VI_XLOCK set) to be cleaned or
* recycled.
*/
void
vwait(vnode_t *vp, int flags)
{
KASSERT(mutex_owned(vp->v_interlock));
KASSERT(vp->v_usecount != 0);
while ((vp->v_iflag & flags) != 0)
cv_wait(&vp->v_cv, vp->v_interlock);
}
int
vfs_drainvnodes(long target)
{
int error;
mutex_enter(&vnode_free_list_lock);
while (numvnodes > target) {
error = cleanvnode();
if (error != 0)
return error;
mutex_enter(&vnode_free_list_lock);
}
mutex_exit(&vnode_free_list_lock);
return 0;
}
void
vnpanic(vnode_t *vp, const char *fmt, ...)
{
va_list ap;
#ifdef DIAGNOSTIC
vprint(NULL, vp);
#endif
va_start(ap, fmt);
vpanic(fmt, ap);
va_end(ap);
}
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