kernel - Fix NULL pointer dereference on forced unmount
[dragonfly.git] / sys / kern / vfs_mount.c
CommitLineData
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1/*
2 * Copyright (c) 2004 The DragonFly Project. All rights reserved.
3 *
4 * This code is derived from software contributed to The DragonFly Project
5 * by Matthew Dillon <dillon@backplane.com>
6 *
7 * Redistribution and use in source and binary forms, with or without
8 * modification, are permitted provided that the following conditions
9 * are met:
10 *
11 * 1. Redistributions of source code must retain the above copyright
12 * notice, this list of conditions and the following disclaimer.
13 * 2. Redistributions in binary form must reproduce the above copyright
14 * notice, this list of conditions and the following disclaimer in
15 * the documentation and/or other materials provided with the
16 * distribution.
17 * 3. Neither the name of The DragonFly Project nor the names of its
18 * contributors may be used to endorse or promote products derived
19 * from this software without specific, prior written permission.
20 *
21 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
22 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
23 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
24 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
25 * COPYRIGHT HOLDERS OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
26 * INCIDENTAL, SPECIAL, EXEMPLARY OR CONSEQUENTIAL DAMAGES (INCLUDING,
27 * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
28 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
29 * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
30 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
31 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
32 * SUCH DAMAGE.
33 *
34 * Copyright (c) 1989, 1993
35 * The Regents of the University of California. All rights reserved.
36 * (c) UNIX System Laboratories, Inc.
37 * All or some portions of this file are derived from material licensed
38 * to the University of California by American Telephone and Telegraph
39 * Co. or Unix System Laboratories, Inc. and are reproduced herein with
40 * the permission of UNIX System Laboratories, Inc.
41 *
42 * Redistribution and use in source and binary forms, with or without
43 * modification, are permitted provided that the following conditions
44 * are met:
45 * 1. Redistributions of source code must retain the above copyright
46 * notice, this list of conditions and the following disclaimer.
47 * 2. Redistributions in binary form must reproduce the above copyright
48 * notice, this list of conditions and the following disclaimer in the
49 * documentation and/or other materials provided with the distribution.
50 * 3. All advertising materials mentioning features or use of this software
51 * must display the following acknowledgement:
52 * This product includes software developed by the University of
53 * California, Berkeley and its contributors.
54 * 4. Neither the name of the University nor the names of its contributors
55 * may be used to endorse or promote products derived from this software
56 * without specific prior written permission.
57 *
58 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
59 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
60 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
61 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
62 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
63 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
64 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
65 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
66 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
67 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
68 * SUCH DAMAGE.
69 *
67863d04 70 * $DragonFly: src/sys/kern/vfs_mount.c,v 1.37 2008/09/17 21:44:18 dillon Exp $
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71 */
72
73/*
74 * External virtual filesystem routines
75 */
76#include "opt_ddb.h"
77
78#include <sys/param.h>
79#include <sys/systm.h>
80#include <sys/kernel.h>
81#include <sys/malloc.h>
82#include <sys/mount.h>
83#include <sys/proc.h>
84#include <sys/vnode.h>
85#include <sys/buf.h>
86#include <sys/eventhandler.h>
87#include <sys/kthread.h>
88#include <sys/sysctl.h>
89
90#include <machine/limits.h>
91
92#include <sys/buf2.h>
93#include <sys/thread2.h>
3c37c940 94#include <sys/sysref2.h>
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95
96#include <vm/vm.h>
97#include <vm/vm_object.h>
98
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99struct mountscan_info {
100 TAILQ_ENTRY(mountscan_info) msi_entry;
101 int msi_how;
102 struct mount *msi_node;
103};
104
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105struct vmntvnodescan_info {
106 TAILQ_ENTRY(vmntvnodescan_info) entry;
107 struct vnode *vp;
108};
109
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110struct vnlru_info {
111 int pass;
112};
113
5fd012e0 114static int vnlru_nowhere = 0;
58552887 115SYSCTL_INT(_debug, OID_AUTO, vnlru_nowhere, CTLFLAG_RD,
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116 &vnlru_nowhere, 0,
117 "Number of times the vnlru process ran without success");
118
119
120static struct lwkt_token mntid_token;
aac0aabd 121static struct mount dummymount;
5fd012e0 122
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123/* note: mountlist exported to pstat */
124struct mntlist mountlist = TAILQ_HEAD_INITIALIZER(mountlist);
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125static TAILQ_HEAD(,mountscan_info) mountscan_list;
126static struct lwkt_token mountlist_token;
be6c08cb 127static TAILQ_HEAD(,vmntvnodescan_info) mntvnodescan_list;
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128struct lwkt_token mntvnode_token;
129
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130static TAILQ_HEAD(,bio_ops) bio_ops_list = TAILQ_HEAD_INITIALIZER(bio_ops_list);
131
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132/*
133 * Called from vfsinit()
134 */
135void
136vfs_mount_init(void)
137{
138 lwkt_token_init(&mountlist_token);
139 lwkt_token_init(&mntvnode_token);
140 lwkt_token_init(&mntid_token);
861905fb 141 TAILQ_INIT(&mountscan_list);
be6c08cb 142 TAILQ_INIT(&mntvnodescan_list);
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143 mount_init(&dummymount);
144 dummymount.mnt_flag |= MNT_RDONLY;
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145}
146
147/*
148 * Support function called with mntvnode_token held to remove a vnode
149 * from the mountlist. We must update any list scans which are in progress.
150 */
151static void
152vremovevnodemnt(struct vnode *vp)
153{
154 struct vmntvnodescan_info *info;
155
156 TAILQ_FOREACH(info, &mntvnodescan_list, entry) {
157 if (info->vp == vp)
158 info->vp = TAILQ_NEXT(vp, v_nmntvnodes);
159 }
160 TAILQ_REMOVE(&vp->v_mount->mnt_nvnodelist, vp, v_nmntvnodes);
161}
162
163/*
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164 * Allocate a new vnode and associate it with a tag, mount point, and
165 * operations vector.
166 *
167 * A VX locked and refd vnode is returned. The caller should setup the
168 * remaining fields and vx_put() or, if he wishes to leave a vref,
169 * vx_unlock() the vnode.
170 */
171int
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172getnewvnode(enum vtagtype tag, struct mount *mp,
173 struct vnode **vpp, int lktimeout, int lkflags)
174{
175 struct vnode *vp;
176
177 KKASSERT(mp != NULL);
178
179 vp = allocvnode(lktimeout, lkflags);
180 vp->v_tag = tag;
181 vp->v_data = NULL;
182
183 /*
184 * By default the vnode is assigned the mount point's normal
185 * operations vector.
186 */
187 vp->v_ops = &mp->mnt_vn_use_ops;
188
189 /*
190 * Placing the vnode on the mount point's queue makes it visible.
191 * VNON prevents it from being messed with, however.
192 */
193 insmntque(vp, mp);
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194
195 /*
196 * A VX locked & refd vnode is returned.
197 */
198 *vpp = vp;
199 return (0);
200}
201
202/*
203 * This function creates vnodes with special operations vectors. The
204 * mount point is optional.
205 *
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206 * This routine is being phased out but is still used by vfs_conf to
207 * create vnodes for devices prior to the root mount (with mp == NULL).
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208 */
209int
210getspecialvnode(enum vtagtype tag, struct mount *mp,
66a1ddf5 211 struct vop_ops **ops,
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212 struct vnode **vpp, int lktimeout, int lkflags)
213{
214 struct vnode *vp;
215
216 vp = allocvnode(lktimeout, lkflags);
217 vp->v_tag = tag;
5fd012e0 218 vp->v_data = NULL;
66a1ddf5 219 vp->v_ops = ops;
5fd012e0 220
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221 if (mp == NULL)
222 mp = &dummymount;
223
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224 /*
225 * Placing the vnode on the mount point's queue makes it visible.
226 * VNON prevents it from being messed with, however.
227 */
228 insmntque(vp, mp);
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229
230 /*
231 * A VX locked & refd vnode is returned.
232 */
233 *vpp = vp;
234 return (0);
235}
236
237/*
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238 * Interlock against an unmount, return 0 on success, non-zero on failure.
239 *
240 * The passed flag may be 0 or LK_NOWAIT and is only used if an unmount
241 * is in-progress.
242 *
243 * If no unmount is in-progress LK_NOWAIT is ignored. No other flag bits
244 * are used. A shared locked will be obtained and the filesystem will not
245 * be unmountable until the lock is released.
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246 */
247int
f9642f56 248vfs_busy(struct mount *mp, int flags)
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249{
250 int lkflags;
251
252 if (mp->mnt_kern_flag & MNTK_UNMOUNT) {
253 if (flags & LK_NOWAIT)
254 return (ENOENT);
861905fb 255 /* XXX not MP safe */
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256 mp->mnt_kern_flag |= MNTK_MWAIT;
257 /*
258 * Since all busy locks are shared except the exclusive
259 * lock granted when unmounting, the only place that a
260 * wakeup needs to be done is at the release of the
261 * exclusive lock at the end of dounmount.
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262 */
263 tsleep((caddr_t)mp, 0, "vfs_busy", 0);
264 return (ENOENT);
265 }
ab6f251b 266 lkflags = LK_SHARED;
df4f70a6 267 if (lockmgr(&mp->mnt_lock, lkflags))
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268 panic("vfs_busy: unexpected lock failure");
269 return (0);
270}
271
272/*
273 * Free a busy filesystem.
274 */
275void
f9642f56 276vfs_unbusy(struct mount *mp)
5fd012e0 277{
df4f70a6 278 lockmgr(&mp->mnt_lock, LK_RELEASE);
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279}
280
281/*
282 * Lookup a filesystem type, and if found allocate and initialize
283 * a mount structure for it.
284 *
285 * Devname is usually updated by mount(8) after booting.
286 */
287int
288vfs_rootmountalloc(char *fstypename, char *devname, struct mount **mpp)
289{
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290 struct vfsconf *vfsp;
291 struct mount *mp;
292
293 if (fstypename == NULL)
294 return (ENODEV);
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295
296 vfsp = vfsconf_find_by_name(fstypename);
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297 if (vfsp == NULL)
298 return (ENODEV);
e7b4468c 299 mp = kmalloc(sizeof(struct mount), M_MOUNT, M_WAITOK | M_ZERO);
aac0aabd 300 mount_init(mp);
ab6f251b 301 lockinit(&mp->mnt_lock, "vfslock", VLKTIMEOUT, 0);
aac0aabd 302
f9642f56 303 vfs_busy(mp, LK_NOWAIT);
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304 mp->mnt_vfc = vfsp;
305 mp->mnt_op = vfsp->vfc_vfsops;
5fd012e0 306 vfsp->vfc_refcount++;
5fd012e0 307 mp->mnt_stat.f_type = vfsp->vfc_typenum;
aac0aabd 308 mp->mnt_flag |= MNT_RDONLY;
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309 mp->mnt_flag |= vfsp->vfc_flags & MNT_VISFLAGMASK;
310 strncpy(mp->mnt_stat.f_fstypename, vfsp->vfc_name, MFSNAMELEN);
069b825e 311 copystr(devname, mp->mnt_stat.f_mntfromname, MNAMELEN - 1, 0);
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312 *mpp = mp;
313 return (0);
314}
315
316/*
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317 * Basic mount structure initialization
318 */
319void
320mount_init(struct mount *mp)
321{
322 lockinit(&mp->mnt_lock, "vfslock", 0, 0);
323 lwkt_token_init(&mp->mnt_token);
324
325 TAILQ_INIT(&mp->mnt_nvnodelist);
326 TAILQ_INIT(&mp->mnt_reservedvnlist);
327 TAILQ_INIT(&mp->mnt_jlist);
328 mp->mnt_nvnodelistsize = 0;
329 mp->mnt_flag = 0;
330 mp->mnt_iosize_max = DFLTPHYS;
331}
332
333/*
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334 * Lookup a mount point by filesystem identifier.
335 */
336struct mount *
337vfs_getvfs(fsid_t *fsid)
338{
339 struct mount *mp;
340 lwkt_tokref ilock;
341
342 lwkt_gettoken(&ilock, &mountlist_token);
343 TAILQ_FOREACH(mp, &mountlist, mnt_list) {
344 if (mp->mnt_stat.f_fsid.val[0] == fsid->val[0] &&
345 mp->mnt_stat.f_fsid.val[1] == fsid->val[1]) {
346 break;
02dede15 347 }
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348 }
349 lwkt_reltoken(&ilock);
350 return (mp);
351}
352
353/*
354 * Get a new unique fsid. Try to make its val[0] unique, since this value
355 * will be used to create fake device numbers for stat(). Also try (but
356 * not so hard) make its val[0] unique mod 2^16, since some emulators only
357 * support 16-bit device numbers. We end up with unique val[0]'s for the
358 * first 2^16 calls and unique val[0]'s mod 2^16 for the first 2^8 calls.
359 *
360 * Keep in mind that several mounts may be running in parallel. Starting
361 * the search one past where the previous search terminated is both a
362 * micro-optimization and a defense against returning the same fsid to
363 * different mounts.
364 */
365void
366vfs_getnewfsid(struct mount *mp)
367{
368 static u_int16_t mntid_base;
369 lwkt_tokref ilock;
370 fsid_t tfsid;
371 int mtype;
372
373 lwkt_gettoken(&ilock, &mntid_token);
374 mtype = mp->mnt_vfc->vfc_typenum;
375 tfsid.val[1] = mtype;
376 mtype = (mtype & 0xFF) << 24;
377 for (;;) {
378 tfsid.val[0] = makeudev(255,
379 mtype | ((mntid_base & 0xFF00) << 8) | (mntid_base & 0xFF));
380 mntid_base++;
381 if (vfs_getvfs(&tfsid) == NULL)
382 break;
383 }
384 mp->mnt_stat.f_fsid.val[0] = tfsid.val[0];
385 mp->mnt_stat.f_fsid.val[1] = tfsid.val[1];
386 lwkt_reltoken(&ilock);
387}
388
389/*
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390 * Set the FSID for a new mount point to the template. Adjust
391 * the FSID to avoid collisions.
392 */
393int
394vfs_setfsid(struct mount *mp, fsid_t *template)
395{
396 int didmunge = 0;
397
398 bzero(&mp->mnt_stat.f_fsid, sizeof(mp->mnt_stat.f_fsid));
399 for (;;) {
400 if (vfs_getvfs(template) == NULL)
401 break;
402 didmunge = 1;
403 ++template->val[1];
404 }
405 mp->mnt_stat.f_fsid = *template;
406 return(didmunge);
407}
408
409/*
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410 * This routine is called when we have too many vnodes. It attempts
411 * to free <count> vnodes and will potentially free vnodes that still
412 * have VM backing store (VM backing store is typically the cause
413 * of a vnode blowout so we want to do this). Therefore, this operation
414 * is not considered cheap.
415 *
416 * A number of conditions may prevent a vnode from being reclaimed.
417 * the buffer cache may have references on the vnode, a directory
418 * vnode may still have references due to the namei cache representing
419 * underlying files, or the vnode may be in active use. It is not
420 * desireable to reuse such vnodes. These conditions may cause the
421 * number of vnodes to reach some minimum value regardless of what
422 * you set kern.maxvnodes to. Do not set kern.maxvnodes too low.
423 */
424
425/*
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426 * This is a quick non-blocking check to determine if the vnode is a good
427 * candidate for being (eventually) vgone()'d. Returns 0 if the vnode is
428 * not a good candidate, 1 if it is.
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429 */
430static __inline int
0e8bd897 431vmightfree(struct vnode *vp, int page_count, int pass)
5fd012e0 432{
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433 if (vp->v_flag & VRECLAIMED)
434 return (0);
44b1cf3d 435#if 0
58552887 436 if ((vp->v_flag & VFREE) && TAILQ_EMPTY(&vp->v_namecache))
5fd012e0 437 return (0);
44b1cf3d 438#endif
3c37c940 439 if (sysref_isactive(&vp->v_sysref))
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440 return (0);
441 if (vp->v_object && vp->v_object->resident_page_count >= page_count)
442 return (0);
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443
444 /*
445 * XXX horrible hack. Up to four passes will be taken. Each pass
446 * makes a larger set of vnodes eligible. For now what this really
447 * means is that we try to recycle files opened only once before
448 * recycling files opened multiple times.
449 */
450 switch(vp->v_flag & (VAGE0 | VAGE1)) {
451 case 0:
452 if (pass < 3)
453 return(0);
454 break;
455 case VAGE0:
456 if (pass < 2)
457 return(0);
458 break;
459 case VAGE1:
460 if (pass < 1)
461 return(0);
462 break;
463 case VAGE0 | VAGE1:
464 break;
465 }
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466 return (1);
467}
468
250d127c 469/*
58552887 470 * The vnode was found to be possibly vgone()able and the caller has locked it
250d127c 471 * (thus the usecount should be 1 now). Determine if the vnode is actually
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472 * vgone()able, doing some cleanups in the process. Returns 1 if the vnode
473 * can be vgone()'d, 0 otherwise.
250d127c 474 *
3c37c940 475 * Note that v_auxrefs may be non-zero because (A) this vnode is not a leaf
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476 * in the namecache topology and (B) this vnode has buffer cache bufs.
477 * We cannot remove vnodes with non-leaf namecache associations. We do a
478 * tentitive leaf check prior to attempting to flush out any buffers but the
3c37c940 479 * 'real' test when all is said in done is that v_auxrefs must become 0 for
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480 * the vnode to be freeable.
481 *
3c37c940 482 * We could theoretically just unconditionally flush when v_auxrefs != 0,
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483 * but flushing data associated with non-leaf nodes (which are always
484 * directories), just throws it away for no benefit. It is the buffer
485 * cache's responsibility to choose buffers to recycle from the cached
486 * data point of view.
487 */
488static int
489visleaf(struct vnode *vp)
490{
491 struct namecache *ncp;
492
f63911bf 493 spin_lock_wr(&vp->v_spinlock);
250d127c 494 TAILQ_FOREACH(ncp, &vp->v_namecache, nc_vnode) {
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495 if (!TAILQ_EMPTY(&ncp->nc_list)) {
496 spin_unlock_wr(&vp->v_spinlock);
250d127c 497 return(0);
f63911bf 498 }
250d127c 499 }
f63911bf 500 spin_unlock_wr(&vp->v_spinlock);
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501 return(1);
502}
503
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504/*
505 * Try to clean up the vnode to the point where it can be vgone()'d, returning
506 * 0 if it cannot be vgone()'d (or already has been), 1 if it can. Unlike
507 * vmightfree() this routine may flush the vnode and block. Vnodes marked
508 * VFREE are still candidates for vgone()ing because they may hold namecache
509 * resources and could be blocking the namecache directory hierarchy (and
510 * related vnodes) from being freed.
511 */
250d127c 512static int
58552887 513vtrytomakegoneable(struct vnode *vp, int page_count)
250d127c 514{
58552887 515 if (vp->v_flag & VRECLAIMED)
250d127c 516 return (0);
3c37c940 517 if (vp->v_sysref.refcnt > 1)
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518 return (0);
519 if (vp->v_object && vp->v_object->resident_page_count >= page_count)
520 return (0);
3c37c940 521 if (vp->v_auxrefs && visleaf(vp)) {
87de5057 522 vinvalbuf(vp, V_SAVE, 0, 0);
250d127c 523#if 0 /* DEBUG */
3c37c940 524 kprintf((vp->v_auxrefs ? "vrecycle: vp %p failed: %s\n" :
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525 "vrecycle: vp %p succeeded: %s\n"), vp,
526 (TAILQ_FIRST(&vp->v_namecache) ?
527 TAILQ_FIRST(&vp->v_namecache)->nc_name : "?"));
528#endif
529 }
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530
531 /*
532 * This sequence may seem a little strange, but we need to optimize
533 * the critical path a bit. We can't recycle vnodes with other
534 * references and because we are trying to recycle an otherwise
535 * perfectly fine vnode we have to invalidate the namecache in a
536 * way that avoids possible deadlocks (since the vnode lock is being
537 * held here). Finally, we have to check for other references one
538 * last time in case something snuck in during the inval.
539 */
540 if (vp->v_sysref.refcnt > 1 || vp->v_auxrefs != 0)
541 return (0);
542 if (cache_inval_vp_nonblock(vp))
543 return (0);
544 return (vp->v_sysref.refcnt <= 1 && vp->v_auxrefs == 0);
250d127c 545}
5fd012e0 546
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547/*
548 * Reclaim up to 1/10 of the vnodes associated with a mount point. Try
549 * to avoid vnodes which have lots of resident pages (we are trying to free
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550 * vnodes, not memory).
551 *
552 * This routine is a callback from the mountlist scan. The mount point
553 * in question will be busied.
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554 *
555 * NOTE: The 1/10 reclamation also ensures that the inactive data set
556 * (the vnodes being recycled by the one-time use) does not degenerate
557 * into too-small a set. This is important because once a vnode is
558 * marked as not being one-time-use (VAGE0/VAGE1 both 0) that vnode
559 * will not be destroyed EXCEPT by this mechanism. VM pages can still
560 * be cleaned/freed by the pageout daemon.
58552887 561 */
5fd012e0 562static int
861905fb 563vlrureclaim(struct mount *mp, void *data)
5fd012e0 564{
0e8bd897 565 struct vnlru_info *info = data;
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566 struct vnode *vp;
567 lwkt_tokref ilock;
568 int done;
569 int trigger;
570 int usevnodes;
571 int count;
861905fb 572 int trigger_mult = vnlru_nowhere;
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573
574 /*
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575 * Calculate the trigger point for the resident pages check. The
576 * minimum trigger value is approximately the number of pages in
577 * the system divded by the number of vnodes. However, due to
578 * various other system memory overheads unrelated to data caching
579 * it is a good idea to double the trigger (at least).
580 *
581 * trigger_mult starts at 0. If the recycler is having problems
582 * finding enough freeable vnodes it will increase trigger_mult.
583 * This should not happen in normal operation, even on machines with
584 * low amounts of memory, but extraordinary memory use by the system
585 * verses the amount of cached data can trigger it.
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586 */
587 usevnodes = desiredvnodes;
588 if (usevnodes <= 0)
589 usevnodes = 1;
58552887 590 trigger = vmstats.v_page_count * (trigger_mult + 2) / usevnodes;
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591
592 done = 0;
593 lwkt_gettoken(&ilock, &mntvnode_token);
594 count = mp->mnt_nvnodelistsize / 10 + 1;
0e8bd897 595
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596 while (count && mp->mnt_syncer) {
597 /*
598 * Next vnode. Use the special syncer vnode to placemark
599 * the LRU. This way the LRU code does not interfere with
600 * vmntvnodescan().
601 */
602 vp = TAILQ_NEXT(mp->mnt_syncer, v_nmntvnodes);
603 TAILQ_REMOVE(&mp->mnt_nvnodelist, mp->mnt_syncer, v_nmntvnodes);
604 if (vp) {
605 TAILQ_INSERT_AFTER(&mp->mnt_nvnodelist, vp,
606 mp->mnt_syncer, v_nmntvnodes);
607 } else {
608 TAILQ_INSERT_HEAD(&mp->mnt_nvnodelist, mp->mnt_syncer,
609 v_nmntvnodes);
610 vp = TAILQ_NEXT(mp->mnt_syncer, v_nmntvnodes);
611 if (vp == NULL)
612 break;
613 }
614
5fd012e0
MD
615 /*
616 * __VNODESCAN__
617 *
618 * The VP will stick around while we hold mntvnode_token,
619 * at least until we block, so we can safely do an initial
620 * check, and then must check again after we lock the vnode.
621 */
986e7cda 622 if (vp->v_type == VNON || /* syncer or indeterminant */
0e8bd897 623 !vmightfree(vp, trigger, info->pass) /* critical path opt */
5fd012e0 624 ) {
5fd012e0
MD
625 --count;
626 continue;
627 }
628
629 /*
630 * VX get the candidate vnode. If the VX get fails the
631 * vnode might still be on the mountlist. Our loop depends
632 * on us at least cycling the vnode to the end of the
633 * mountlist.
634 */
635 if (vx_get_nonblock(vp) != 0) {
5fd012e0
MD
636 --count;
637 continue;
638 }
639
640 /*
641 * Since we blocked locking the vp, make sure it is still
642 * a candidate for reclamation. That is, it has not already
643 * been reclaimed and only has our VX reference associated
644 * with it.
645 */
986e7cda 646 if (vp->v_type == VNON || /* syncer or indeterminant */
5fd012e0
MD
647 (vp->v_flag & VRECLAIMED) ||
648 vp->v_mount != mp ||
58552887 649 !vtrytomakegoneable(vp, trigger) /* critical path opt */
5fd012e0 650 ) {
5fd012e0
MD
651 --count;
652 vx_put(vp);
653 continue;
654 }
655
656 /*
657 * All right, we are good, move the vp to the end of the
658 * mountlist and clean it out. The vget will have returned
659 * an error if the vnode was destroyed (VRECLAIMED set), so we
660 * do not have to check again. The vput() will move the
661 * vnode to the free list if the vgone() was successful.
662 */
663 KKASSERT(vp->v_mount == mp);
3c37c940 664 vgone_vxlocked(vp);
5fd012e0
MD
665 vx_put(vp);
666 ++done;
667 --count;
668 }
669 lwkt_reltoken(&ilock);
670 return (done);
671}
672
673/*
674 * Attempt to recycle vnodes in a context that is always safe to block.
675 * Calling vlrurecycle() from the bowels of file system code has some
676 * interesting deadlock problems.
677 */
678static struct thread *vnlruthread;
679static int vnlruproc_sig;
680
681void
682vnlru_proc_wait(void)
683{
684 if (vnlruproc_sig == 0) {
685 vnlruproc_sig = 1; /* avoid unnecessary wakeups */
686 wakeup(vnlruthread);
687 }
688 tsleep(&vnlruproc_sig, 0, "vlruwk", hz);
689}
690
691static void
692vnlru_proc(void)
693{
5fd012e0 694 struct thread *td = curthread;
0e8bd897 695 struct vnlru_info info;
861905fb 696 int done;
5fd012e0
MD
697
698 EVENTHANDLER_REGISTER(shutdown_pre_sync, shutdown_kproc, td,
699 SHUTDOWN_PRI_FIRST);
700
e43a034f 701 crit_enter();
5fd012e0
MD
702 for (;;) {
703 kproc_suspend_loop();
3c37c940
MD
704
705 /*
706 * Try to free some vnodes if we have too many
707 */
708 if (numvnodes > desiredvnodes &&
709 freevnodes > desiredvnodes * 2 / 10) {
710 int count = numvnodes - desiredvnodes;
711
712 if (count > freevnodes / 100)
713 count = freevnodes / 100;
714 if (count < 5)
715 count = 5;
716 freesomevnodes(count);
717 }
718
719 /*
720 * Nothing to do if most of our vnodes are already on
721 * the free list.
722 */
5fd012e0
MD
723 if (numvnodes - freevnodes <= desiredvnodes * 9 / 10) {
724 vnlruproc_sig = 0;
725 wakeup(&vnlruproc_sig);
726 tsleep(td, 0, "vlruwt", hz);
727 continue;
728 }
65870584 729 cache_hysteresis();
0e8bd897
MD
730
731 /*
732 * The pass iterates through the four combinations of
733 * VAGE0/VAGE1. We want to get rid of aged small files
734 * first.
735 */
736 info.pass = 0;
737 done = 0;
738 while (done == 0 && info.pass < 4) {
739 done = mountlist_scan(vlrureclaim, &info,
740 MNTSCAN_FORWARD);
741 ++info.pass;
742 }
58552887
MD
743
744 /*
745 * The vlrureclaim() call only processes 1/10 of the vnodes
746 * on each mount. If we couldn't find any repeat the loop
747 * at least enough times to cover all available vnodes before
748 * we start sleeping. Complain if the failure extends past
749 * 30 second, every 30 seconds.
750 */
5fd012e0
MD
751 if (done == 0) {
752 ++vnlru_nowhere;
5fd012e0 753 if (vnlru_nowhere % 10 == 0)
58552887
MD
754 tsleep(td, 0, "vlrup", hz * 3);
755 if (vnlru_nowhere % 100 == 0)
6ea70f76 756 kprintf("vnlru_proc: vnode recycler stopped working!\n");
58552887
MD
757 if (vnlru_nowhere == 1000)
758 vnlru_nowhere = 900;
5fd012e0
MD
759 } else {
760 vnlru_nowhere = 0;
761 }
762 }
e43a034f 763 crit_exit();
5fd012e0
MD
764}
765
861905fb
MD
766/*
767 * MOUNTLIST FUNCTIONS
768 */
769
770/*
771 * mountlist_insert (MP SAFE)
772 *
773 * Add a new mount point to the mount list.
774 */
775void
776mountlist_insert(struct mount *mp, int how)
777{
778 lwkt_tokref ilock;
779
780 lwkt_gettoken(&ilock, &mountlist_token);
781 if (how == MNTINS_FIRST)
782 TAILQ_INSERT_HEAD(&mountlist, mp, mnt_list);
783 else
784 TAILQ_INSERT_TAIL(&mountlist, mp, mnt_list);
785 lwkt_reltoken(&ilock);
786}
787
788/*
789 * mountlist_interlock (MP SAFE)
790 *
791 * Execute the specified interlock function with the mountlist token
792 * held. The function will be called in a serialized fashion verses
793 * other functions called through this mechanism.
794 */
795int
796mountlist_interlock(int (*callback)(struct mount *), struct mount *mp)
797{
798 lwkt_tokref ilock;
799 int error;
800
801 lwkt_gettoken(&ilock, &mountlist_token);
802 error = callback(mp);
803 lwkt_reltoken(&ilock);
804 return (error);
805}
806
807/*
808 * mountlist_boot_getfirst (DURING BOOT ONLY)
809 *
810 * This function returns the first mount on the mountlist, which is
811 * expected to be the root mount. Since no interlocks are obtained
812 * this function is only safe to use during booting.
813 */
814
815struct mount *
816mountlist_boot_getfirst(void)
817{
818 return(TAILQ_FIRST(&mountlist));
819}
820
821/*
822 * mountlist_remove (MP SAFE)
823 *
824 * Remove a node from the mountlist. If this node is the next scan node
825 * for any active mountlist scans, the active mountlist scan will be
826 * adjusted to skip the node, thus allowing removals during mountlist
827 * scans.
828 */
829void
830mountlist_remove(struct mount *mp)
831{
832 struct mountscan_info *msi;
833 lwkt_tokref ilock;
834
835 lwkt_gettoken(&ilock, &mountlist_token);
836 TAILQ_FOREACH(msi, &mountscan_list, msi_entry) {
837 if (msi->msi_node == mp) {
838 if (msi->msi_how & MNTSCAN_FORWARD)
839 msi->msi_node = TAILQ_NEXT(mp, mnt_list);
840 else
841 msi->msi_node = TAILQ_PREV(mp, mntlist, mnt_list);
842 }
843 }
844 TAILQ_REMOVE(&mountlist, mp, mnt_list);
845 lwkt_reltoken(&ilock);
846}
847
848/*
849 * mountlist_scan (MP SAFE)
850 *
851 * Safely scan the mount points on the mount list. Unless otherwise
852 * specified each mount point will be busied prior to the callback and
853 * unbusied afterwords. The callback may safely remove any mount point
854 * without interfering with the scan. If the current callback
855 * mount is removed the scanner will not attempt to unbusy it.
856 *
857 * If a mount node cannot be busied it is silently skipped.
858 *
859 * The callback return value is aggregated and a total is returned. A return
860 * value of < 0 is not aggregated and will terminate the scan.
861 *
862 * MNTSCAN_FORWARD - the mountlist is scanned in the forward direction
863 * MNTSCAN_REVERSE - the mountlist is scanned in reverse
864 * MNTSCAN_NOBUSY - the scanner will make the callback without busying
865 * the mount node.
866 */
867int
868mountlist_scan(int (*callback)(struct mount *, void *), void *data, int how)
869{
870 struct mountscan_info info;
871 lwkt_tokref ilock;
872 struct mount *mp;
873 thread_t td;
874 int count;
875 int res;
876
877 lwkt_gettoken(&ilock, &mountlist_token);
878
879 info.msi_how = how;
880 info.msi_node = NULL; /* paranoia */
881 TAILQ_INSERT_TAIL(&mountscan_list, &info, msi_entry);
882
883 res = 0;
884 td = curthread;
885
886 if (how & MNTSCAN_FORWARD) {
887 info.msi_node = TAILQ_FIRST(&mountlist);
888 while ((mp = info.msi_node) != NULL) {
889 if (how & MNTSCAN_NOBUSY) {
890 count = callback(mp, data);
f9642f56 891 } else if (vfs_busy(mp, LK_NOWAIT) == 0) {
861905fb
MD
892 count = callback(mp, data);
893 if (mp == info.msi_node)
f9642f56 894 vfs_unbusy(mp);
861905fb
MD
895 } else {
896 count = 0;
897 }
898 if (count < 0)
899 break;
900 res += count;
901 if (mp == info.msi_node)
902 info.msi_node = TAILQ_NEXT(mp, mnt_list);
903 }
904 } else if (how & MNTSCAN_REVERSE) {
905 info.msi_node = TAILQ_LAST(&mountlist, mntlist);
906 while ((mp = info.msi_node) != NULL) {
907 if (how & MNTSCAN_NOBUSY) {
908 count = callback(mp, data);
f9642f56 909 } else if (vfs_busy(mp, LK_NOWAIT) == 0) {
861905fb
MD
910 count = callback(mp, data);
911 if (mp == info.msi_node)
f9642f56 912 vfs_unbusy(mp);
861905fb
MD
913 } else {
914 count = 0;
915 }
916 if (count < 0)
917 break;
918 res += count;
919 if (mp == info.msi_node)
920 info.msi_node = TAILQ_PREV(mp, mntlist, mnt_list);
921 }
922 }
923 TAILQ_REMOVE(&mountscan_list, &info, msi_entry);
924 lwkt_reltoken(&ilock);
925 return(res);
926}
927
928/*
929 * MOUNT RELATED VNODE FUNCTIONS
930 */
931
5fd012e0
MD
932static struct kproc_desc vnlru_kp = {
933 "vnlru",
934 vnlru_proc,
935 &vnlruthread
936};
937SYSINIT(vnlru, SI_SUB_KTHREAD_UPDATE, SI_ORDER_FIRST, kproc_start, &vnlru_kp)
938
939/*
940 * Move a vnode from one mount queue to another.
2247fe02
MD
941 *
942 * MPSAFE
5fd012e0
MD
943 */
944void
945insmntque(struct vnode *vp, struct mount *mp)
946{
947 lwkt_tokref ilock;
948
949 lwkt_gettoken(&ilock, &mntvnode_token);
950 /*
951 * Delete from old mount point vnode list, if on one.
952 */
953 if (vp->v_mount != NULL) {
954 KASSERT(vp->v_mount->mnt_nvnodelistsize > 0,
955 ("bad mount point vnode list size"));
be6c08cb 956 vremovevnodemnt(vp);
5fd012e0
MD
957 vp->v_mount->mnt_nvnodelistsize--;
958 }
959 /*
960 * Insert into list of vnodes for the new mount point, if available.
2ec4b00d 961 * The 'end' of the LRU list is the vnode prior to mp->mnt_syncer.
5fd012e0
MD
962 */
963 if ((vp->v_mount = mp) == NULL) {
964 lwkt_reltoken(&ilock);
965 return;
966 }
2ec4b00d
MD
967 if (mp->mnt_syncer) {
968 TAILQ_INSERT_BEFORE(mp->mnt_syncer, vp, v_nmntvnodes);
969 } else {
970 TAILQ_INSERT_TAIL(&mp->mnt_nvnodelist, vp, v_nmntvnodes);
971 }
5fd012e0
MD
972 mp->mnt_nvnodelistsize++;
973 lwkt_reltoken(&ilock);
974}
975
976
977/*
be6c08cb
MD
978 * Scan the vnodes under a mount point and issue appropriate callbacks.
979 *
980 * The fastfunc() callback is called with just the mountlist token held
981 * (no vnode lock). It may not block and the vnode may be undergoing
982 * modifications while the caller is processing it. The vnode will
983 * not be entirely destroyed, however, due to the fact that the mountlist
984 * token is held. A return value < 0 skips to the next vnode without calling
985 * the slowfunc(), a return value > 0 terminates the loop.
986 *
987 * The slowfunc() callback is called after the vnode has been successfully
988 * locked based on passed flags. The vnode is skipped if it gets rearranged
989 * or destroyed while blocking on the lock. A non-zero return value from
990 * the slow function terminates the loop. The slow function is allowed to
991 * arbitrarily block. The scanning code guarentees consistency of operation
992 * even if the slow function deletes or moves the node, or blocks and some
993 * other thread deletes or moves the node.
5fd012e0
MD
994 */
995int
996vmntvnodescan(
997 struct mount *mp,
998 int flags,
999 int (*fastfunc)(struct mount *mp, struct vnode *vp, void *data),
1000 int (*slowfunc)(struct mount *mp, struct vnode *vp, void *data),
1001 void *data
1002) {
be6c08cb 1003 struct vmntvnodescan_info info;
5fd012e0 1004 lwkt_tokref ilock;
5fd012e0
MD
1005 struct vnode *vp;
1006 int r = 0;
be6c08cb 1007 int maxcount = 1000000;
19b97e01 1008 int stopcount = 0;
9fe8385f 1009 int count = 0;
5fd012e0
MD
1010
1011 lwkt_gettoken(&ilock, &mntvnode_token);
5fd012e0 1012
19b97e01
MD
1013 /*
1014 * If asked to do one pass stop after iterating available vnodes.
1015 * Under heavy loads new vnodes can be added while we are scanning,
1016 * so this isn't perfect. Create a slop factor of 2x.
1017 */
1018 if (flags & VMSC_ONEPASS)
1019 stopcount = mp->mnt_nvnodelistsize * 2;
1020
be6c08cb
MD
1021 info.vp = TAILQ_FIRST(&mp->mnt_nvnodelist);
1022 TAILQ_INSERT_TAIL(&mntvnodescan_list, &info, entry);
1023 while ((vp = info.vp) != NULL) {
1024 if (--maxcount == 0)
1025 panic("maxcount reached during vmntvnodescan");
1026
2ec4b00d
MD
1027 /*
1028 * Skip if visible but not ready, or special (e.g.
1029 * mp->mnt_syncer)
1030 */
1031 if (vp->v_type == VNON)
be6c08cb 1032 goto next;
5fd012e0
MD
1033 KKASSERT(vp->v_mount == mp);
1034
1035 /*
1036 * Quick test. A negative return continues the loop without
1037 * calling the slow test. 0 continues onto the slow test.
1038 * A positive number aborts the loop.
1039 */
1040 if (fastfunc) {
c66c09cf
MD
1041 if ((r = fastfunc(mp, vp, data)) < 0) {
1042 r = 0;
be6c08cb 1043 goto next;
c66c09cf 1044 }
5fd012e0
MD
1045 if (r)
1046 break;
1047 }
1048
1049 /*
1050 * Get a vxlock on the vnode, retry if it has moved or isn't
1051 * in the mountlist where we expect it.
1052 */
1053 if (slowfunc) {
1054 int error;
1055
19b97e01 1056 switch(flags & (VMSC_GETVP|VMSC_GETVX|VMSC_NOWAIT)) {
5fd012e0 1057 case VMSC_GETVP:
87de5057 1058 error = vget(vp, LK_EXCLUSIVE);
5fd012e0
MD
1059 break;
1060 case VMSC_GETVP|VMSC_NOWAIT:
87de5057 1061 error = vget(vp, LK_EXCLUSIVE|LK_NOWAIT);
5fd012e0
MD
1062 break;
1063 case VMSC_GETVX:
e3332475
MD
1064 vx_get(vp);
1065 error = 0;
5fd012e0 1066 break;
5fd012e0
MD
1067 default:
1068 error = 0;
1069 break;
1070 }
1071 if (error)
be6c08cb
MD
1072 goto next;
1073 /*
1074 * Do not call the slow function if the vnode is
1075 * invalid or if it was ripped out from under us
1076 * while we (potentially) blocked.
1077 */
1078 if (info.vp == vp && vp->v_type != VNON)
1079 r = slowfunc(mp, vp, data);
1080
1081 /*
1082 * Cleanup
1083 */
19b97e01 1084 switch(flags & (VMSC_GETVP|VMSC_GETVX|VMSC_NOWAIT)) {
5fd012e0
MD
1085 case VMSC_GETVP:
1086 case VMSC_GETVP|VMSC_NOWAIT:
1087 vput(vp);
1088 break;
1089 case VMSC_GETVX:
1090 vx_put(vp);
1091 break;
5fd012e0
MD
1092 default:
1093 break;
1094 }
1095 if (r != 0)
1096 break;
1097 }
be6c08cb 1098
9fe8385f
SS
1099next:
1100 /*
1101 * Yield after some processing. Depending on the number
1102 * of vnodes, we might wind up running for a long time.
1103 * Because threads are not preemptable, time critical
1104 * userland processes might starve. Give them a chance
1105 * now and then.
1106 */
1107 if (++count == 10000) {
5a96e837
SS
1108 /* We really want to yield a bit, so we simply sleep a tick */
1109 tsleep(mp, 0, "vnodescn", 1);
9fe8385f
SS
1110 count = 0;
1111 }
1112
be6c08cb 1113 /*
19b97e01
MD
1114 * If doing one pass this decrements to zero. If it starts
1115 * at zero it is effectively unlimited for the purposes of
1116 * this loop.
1117 */
1118 if (--stopcount == 0)
1119 break;
1120
1121 /*
be6c08cb
MD
1122 * Iterate. If the vnode was ripped out from under us
1123 * info.vp will already point to the next vnode, otherwise
1124 * we have to obtain the next valid vnode ourselves.
1125 */
be6c08cb
MD
1126 if (info.vp == vp)
1127 info.vp = TAILQ_NEXT(vp, v_nmntvnodes);
5fd012e0 1128 }
be6c08cb 1129 TAILQ_REMOVE(&mntvnodescan_list, &info, entry);
5fd012e0
MD
1130 lwkt_reltoken(&ilock);
1131 return(r);
1132}
1133
1134/*
1135 * Remove any vnodes in the vnode table belonging to mount point mp.
1136 *
1137 * If FORCECLOSE is not specified, there should not be any active ones,
1138 * return error if any are found (nb: this is a user error, not a
1139 * system error). If FORCECLOSE is specified, detach any active vnodes
1140 * that are found.
1141 *
1142 * If WRITECLOSE is set, only flush out regular file vnodes open for
1143 * writing.
1144 *
1145 * SKIPSYSTEM causes any vnodes marked VSYSTEM to be skipped.
1146 *
1147 * `rootrefs' specifies the base reference count for the root vnode
1148 * of this filesystem. The root vnode is considered busy if its
3c37c940 1149 * v_sysref.refcnt exceeds this value. On a successful return, vflush()
5fd012e0
MD
1150 * will call vrele() on the root vnode exactly rootrefs times.
1151 * If the SKIPSYSTEM or WRITECLOSE flags are specified, rootrefs must
1152 * be zero.
1153 */
1154#ifdef DIAGNOSTIC
1155static int busyprt = 0; /* print out busy vnodes */
1156SYSCTL_INT(_debug, OID_AUTO, busyprt, CTLFLAG_RW, &busyprt, 0, "");
1157#endif
1158
1159static int vflush_scan(struct mount *mp, struct vnode *vp, void *data);
1160
1161struct vflush_info {
1162 int flags;
1163 int busy;
1164 thread_t td;
1165};
1166
1167int
1168vflush(struct mount *mp, int rootrefs, int flags)
1169{
1170 struct thread *td = curthread; /* XXX */
1171 struct vnode *rootvp = NULL;
1172 int error;
1173 struct vflush_info vflush_info;
1174
1175 if (rootrefs > 0) {
1176 KASSERT((flags & (SKIPSYSTEM | WRITECLOSE)) == 0,
1177 ("vflush: bad args"));
1178 /*
1179 * Get the filesystem root vnode. We can vput() it
1180 * immediately, since with rootrefs > 0, it won't go away.
1181 */
d9adbeaf
MD
1182 if ((error = VFS_ROOT(mp, &rootvp)) != 0) {
1183 if ((flags & FORCECLOSE) == 0)
1184 return (error);
1185 rootrefs = 0;
1186 /* continue anyway */
1187 }
1188 if (rootrefs)
1189 vput(rootvp);
5fd012e0
MD
1190 }
1191
1192 vflush_info.busy = 0;
1193 vflush_info.flags = flags;
1194 vflush_info.td = td;
1195 vmntvnodescan(mp, VMSC_GETVX, NULL, vflush_scan, &vflush_info);
1196
1197 if (rootrefs > 0 && (flags & FORCECLOSE) == 0) {
1198 /*
1199 * If just the root vnode is busy, and if its refcount
1200 * is equal to `rootrefs', then go ahead and kill it.
1201 */
1202 KASSERT(vflush_info.busy > 0, ("vflush: not busy"));
3c37c940
MD
1203 KASSERT(rootvp->v_sysref.refcnt >= rootrefs, ("vflush: rootrefs"));
1204 if (vflush_info.busy == 1 && rootvp->v_sysref.refcnt == rootrefs) {
e3332475 1205 vx_lock(rootvp);
3c37c940 1206 vgone_vxlocked(rootvp);
e3332475
MD
1207 vx_unlock(rootvp);
1208 vflush_info.busy = 0;
5fd012e0
MD
1209 }
1210 }
1211 if (vflush_info.busy)
1212 return (EBUSY);
1213 for (; rootrefs > 0; rootrefs--)
1214 vrele(rootvp);
1215 return (0);
1216}
1217
1218/*
1219 * The scan callback is made with an VX locked vnode.
1220 */
1221static int
1222vflush_scan(struct mount *mp, struct vnode *vp, void *data)
1223{
1224 struct vflush_info *info = data;
1225 struct vattr vattr;
1226
1227 /*
1228 * Skip over a vnodes marked VSYSTEM.
1229 */
1230 if ((info->flags & SKIPSYSTEM) && (vp->v_flag & VSYSTEM)) {
1231 return(0);
1232 }
1233
1234 /*
1235 * If WRITECLOSE is set, flush out unlinked but still open
1236 * files (even if open only for reading) and regular file
1237 * vnodes open for writing.
1238 */
1239 if ((info->flags & WRITECLOSE) &&
1240 (vp->v_type == VNON ||
87de5057 1241 (VOP_GETATTR(vp, &vattr) == 0 &&
5fd012e0
MD
1242 vattr.va_nlink > 0)) &&
1243 (vp->v_writecount == 0 || vp->v_type != VREG)) {
1244 return(0);
1245 }
1246
1247 /*
3c37c940
MD
1248 * If we are the only holder (refcnt of 1) or the vnode is in
1249 * termination (refcnt < 0), we can vgone the vnode.
5fd012e0 1250 */
3c37c940
MD
1251 if (vp->v_sysref.refcnt <= 1) {
1252 vgone_vxlocked(vp);
5fd012e0
MD
1253 return(0);
1254 }
1255
1256 /*
1e49b98c
MD
1257 * If FORCECLOSE is set, forcibly destroy the vnode and then move
1258 * it to a dummymount structure so vop_*() functions don't deref
1259 * a NULL pointer.
5fd012e0
MD
1260 */
1261 if (info->flags & FORCECLOSE) {
1e49b98c 1262 vhold(vp);
aec8eea4 1263 vgone_vxlocked(vp);
1e49b98c
MD
1264 if (vp->v_mount == NULL)
1265 insmntque(vp, &dummymount);
1266 vdrop(vp);
5fd012e0
MD
1267 return(0);
1268 }
1269#ifdef DIAGNOSTIC
1270 if (busyprt)
1271 vprint("vflush: busy vnode", vp);
1272#endif
1273 ++info->busy;
1274 return(0);
1275}
1276
408357d8
MD
1277void
1278add_bio_ops(struct bio_ops *ops)
1279{
1280 TAILQ_INSERT_TAIL(&bio_ops_list, ops, entry);
1281}
1282
1283void
1284rem_bio_ops(struct bio_ops *ops)
1285{
1286 TAILQ_REMOVE(&bio_ops_list, ops, entry);
1287}
1288
1289/*
1290 * This calls the bio_ops io_sync function either for a mount point
1291 * or generally.
1292 *
1293 * WARNING: softdeps is weirdly coded and just isn't happy unless
1294 * io_sync is called with a NULL mount from the general syncing code.
1295 */
1296void
1297bio_ops_sync(struct mount *mp)
1298{
1299 struct bio_ops *ops;
1300
1301 if (mp) {
1302 if ((ops = mp->mnt_bioops) != NULL)
1303 ops->io_sync(mp);
1304 } else {
1305 TAILQ_FOREACH(ops, &bio_ops_list, entry) {
1306 ops->io_sync(NULL);
1307 }
1308 }
1309}
1310
5b4cfb7e
AH
1311/*
1312 * Lookup a mount point by nch
1313 */
1314struct mount *
1315mount_get_by_nc(struct namecache *ncp)
1316{
1317 struct mount *mp = NULL;
1318 lwkt_tokref ilock;
1319
1320 lwkt_gettoken(&ilock, &mountlist_token);
1321 TAILQ_FOREACH(mp, &mountlist, mnt_list) {
1322 if (ncp == mp->mnt_ncmountpt.ncp)
1323 break;
1324 }
1325 lwkt_reltoken(&ilock);
1326 return (mp);
1327}
1328