FreeBSD/Linux Kernel Cross Reference
sys/kern/vfs_mount.c
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 *
70 * $DragonFly: src/sys/kern/vfs_mount.c,v 1.37 2008/09/17 21:44:18 dillon Exp $
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>
94 #include <sys/sysref2.h>
95
96 #include <vm/vm.h>
97 #include <vm/vm_object.h>
98
99 struct mountscan_info {
100 TAILQ_ENTRY(mountscan_info) msi_entry;
101 int msi_how;
102 struct mount *msi_node;
103 };
104
105 struct vmntvnodescan_info {
106 TAILQ_ENTRY(vmntvnodescan_info) entry;
107 struct vnode *vp;
108 };
109
110 static int vnlru_nowhere = 0;
111 SYSCTL_INT(_debug, OID_AUTO, vnlru_nowhere, CTLFLAG_RD,
112 &vnlru_nowhere, 0,
113 "Number of times the vnlru process ran without success");
114
115
116 static struct lwkt_token mntid_token;
117
118 /* note: mountlist exported to pstat */
119 struct mntlist mountlist = TAILQ_HEAD_INITIALIZER(mountlist);
120 static TAILQ_HEAD(,mountscan_info) mountscan_list;
121 static struct lwkt_token mountlist_token;
122 static TAILQ_HEAD(,vmntvnodescan_info) mntvnodescan_list;
123 struct lwkt_token mntvnode_token;
124
125 static TAILQ_HEAD(,bio_ops) bio_ops_list = TAILQ_HEAD_INITIALIZER(bio_ops_list);
126
127 /*
128 * Called from vfsinit()
129 */
130 void
131 vfs_mount_init(void)
132 {
133 lwkt_token_init(&mountlist_token);
134 lwkt_token_init(&mntvnode_token);
135 lwkt_token_init(&mntid_token);
136 TAILQ_INIT(&mountscan_list);
137 TAILQ_INIT(&mntvnodescan_list);
138 }
139
140 /*
141 * Support function called with mntvnode_token held to remove a vnode
142 * from the mountlist. We must update any list scans which are in progress.
143 */
144 static void
145 vremovevnodemnt(struct vnode *vp)
146 {
147 struct vmntvnodescan_info *info;
148
149 TAILQ_FOREACH(info, &mntvnodescan_list, entry) {
150 if (info->vp == vp)
151 info->vp = TAILQ_NEXT(vp, v_nmntvnodes);
152 }
153 TAILQ_REMOVE(&vp->v_mount->mnt_nvnodelist, vp, v_nmntvnodes);
154 }
155
156 /*
157 * Allocate a new vnode and associate it with a tag, mount point, and
158 * operations vector.
159 *
160 * A VX locked and refd vnode is returned. The caller should setup the
161 * remaining fields and vx_put() or, if he wishes to leave a vref,
162 * vx_unlock() the vnode.
163 */
164 int
165 getnewvnode(enum vtagtype tag, struct mount *mp,
166 struct vnode **vpp, int lktimeout, int lkflags)
167 {
168 struct vnode *vp;
169
170 KKASSERT(mp != NULL);
171
172 vp = allocvnode(lktimeout, lkflags);
173 vp->v_tag = tag;
174 vp->v_data = NULL;
175
176 /*
177 * By default the vnode is assigned the mount point's normal
178 * operations vector.
179 */
180 vp->v_ops = &mp->mnt_vn_use_ops;
181
182 /*
183 * Placing the vnode on the mount point's queue makes it visible.
184 * VNON prevents it from being messed with, however.
185 */
186 insmntque(vp, mp);
187
188 /*
189 * A VX locked & refd vnode is returned.
190 */
191 *vpp = vp;
192 return (0);
193 }
194
195 /*
196 * This function creates vnodes with special operations vectors. The
197 * mount point is optional.
198 *
199 * This routine is being phased out.
200 */
201 int
202 getspecialvnode(enum vtagtype tag, struct mount *mp,
203 struct vop_ops **ops,
204 struct vnode **vpp, int lktimeout, int lkflags)
205 {
206 struct vnode *vp;
207
208 vp = allocvnode(lktimeout, lkflags);
209 vp->v_tag = tag;
210 vp->v_data = NULL;
211 vp->v_ops = ops;
212
213 /*
214 * Placing the vnode on the mount point's queue makes it visible.
215 * VNON prevents it from being messed with, however.
216 */
217 insmntque(vp, mp);
218
219 /*
220 * A VX locked & refd vnode is returned.
221 */
222 *vpp = vp;
223 return (0);
224 }
225
226 /*
227 * Interlock against an unmount, return 0 on success, non-zero on failure.
228 *
229 * The passed flag may be 0 or LK_NOWAIT and is only used if an unmount
230 * is in-progress.
231 *
232 * If no unmount is in-progress LK_NOWAIT is ignored. No other flag bits
233 * are used. A shared locked will be obtained and the filesystem will not
234 * be unmountable until the lock is released.
235 */
236 int
237 vfs_busy(struct mount *mp, int flags)
238 {
239 int lkflags;
240
241 if (mp->mnt_kern_flag & MNTK_UNMOUNT) {
242 if (flags & LK_NOWAIT)
243 return (ENOENT);
244 /* XXX not MP safe */
245 mp->mnt_kern_flag |= MNTK_MWAIT;
246 /*
247 * Since all busy locks are shared except the exclusive
248 * lock granted when unmounting, the only place that a
249 * wakeup needs to be done is at the release of the
250 * exclusive lock at the end of dounmount.
251 */
252 tsleep((caddr_t)mp, 0, "vfs_busy", 0);
253 return (ENOENT);
254 }
255 lkflags = LK_SHARED;
256 if (lockmgr(&mp->mnt_lock, lkflags))
257 panic("vfs_busy: unexpected lock failure");
258 return (0);
259 }
260
261 /*
262 * Free a busy filesystem.
263 */
264 void
265 vfs_unbusy(struct mount *mp)
266 {
267 lockmgr(&mp->mnt_lock, LK_RELEASE);
268 }
269
270 /*
271 * Lookup a filesystem type, and if found allocate and initialize
272 * a mount structure for it.
273 *
274 * Devname is usually updated by mount(8) after booting.
275 */
276 int
277 vfs_rootmountalloc(char *fstypename, char *devname, struct mount **mpp)
278 {
279 struct vfsconf *vfsp;
280 struct mount *mp;
281
282 if (fstypename == NULL)
283 return (ENODEV);
284
285 vfsp = vfsconf_find_by_name(fstypename);
286 if (vfsp == NULL)
287 return (ENODEV);
288 mp = kmalloc(sizeof(struct mount), M_MOUNT, M_WAITOK | M_ZERO);
289 lockinit(&mp->mnt_lock, "vfslock", VLKTIMEOUT, 0);
290 vfs_busy(mp, LK_NOWAIT);
291 TAILQ_INIT(&mp->mnt_nvnodelist);
292 TAILQ_INIT(&mp->mnt_reservedvnlist);
293 TAILQ_INIT(&mp->mnt_jlist);
294 mp->mnt_nvnodelistsize = 0;
295 mp->mnt_vfc = vfsp;
296 mp->mnt_op = vfsp->vfc_vfsops;
297 mp->mnt_flag = MNT_RDONLY;
298 vfsp->vfc_refcount++;
299 mp->mnt_iosize_max = DFLTPHYS;
300 mp->mnt_stat.f_type = vfsp->vfc_typenum;
301 mp->mnt_flag |= vfsp->vfc_flags & MNT_VISFLAGMASK;
302 strncpy(mp->mnt_stat.f_fstypename, vfsp->vfc_name, MFSNAMELEN);
303 copystr(devname, mp->mnt_stat.f_mntfromname, MNAMELEN - 1, 0);
304 *mpp = mp;
305 return (0);
306 }
307
308 /*
309 * Lookup a mount point by filesystem identifier.
310 */
311 struct mount *
312 vfs_getvfs(fsid_t *fsid)
313 {
314 struct mount *mp;
315 lwkt_tokref ilock;
316
317 lwkt_gettoken(&ilock, &mountlist_token);
318 TAILQ_FOREACH(mp, &mountlist, mnt_list) {
319 if (mp->mnt_stat.f_fsid.val[0] == fsid->val[0] &&
320 mp->mnt_stat.f_fsid.val[1] == fsid->val[1]) {
321 break;
322 }
323 }
324 lwkt_reltoken(&ilock);
325 return (mp);
326 }
327
328 /*
329 * Get a new unique fsid. Try to make its val[0] unique, since this value
330 * will be used to create fake device numbers for stat(). Also try (but
331 * not so hard) make its val[0] unique mod 2^16, since some emulators only
332 * support 16-bit device numbers. We end up with unique val[0]'s for the
333 * first 2^16 calls and unique val[0]'s mod 2^16 for the first 2^8 calls.
334 *
335 * Keep in mind that several mounts may be running in parallel. Starting
336 * the search one past where the previous search terminated is both a
337 * micro-optimization and a defense against returning the same fsid to
338 * different mounts.
339 */
340 void
341 vfs_getnewfsid(struct mount *mp)
342 {
343 static u_int16_t mntid_base;
344 lwkt_tokref ilock;
345 fsid_t tfsid;
346 int mtype;
347
348 lwkt_gettoken(&ilock, &mntid_token);
349 mtype = mp->mnt_vfc->vfc_typenum;
350 tfsid.val[1] = mtype;
351 mtype = (mtype & 0xFF) << 24;
352 for (;;) {
353 tfsid.val[0] = makeudev(255,
354 mtype | ((mntid_base & 0xFF00) << 8) | (mntid_base & 0xFF));
355 mntid_base++;
356 if (vfs_getvfs(&tfsid) == NULL)
357 break;
358 }
359 mp->mnt_stat.f_fsid.val[0] = tfsid.val[0];
360 mp->mnt_stat.f_fsid.val[1] = tfsid.val[1];
361 lwkt_reltoken(&ilock);
362 }
363
364 /*
365 * Set the FSID for a new mount point to the template. Adjust
366 * the FSID to avoid collisions.
367 */
368 int
369 vfs_setfsid(struct mount *mp, fsid_t *template)
370 {
371 int didmunge = 0;
372
373 bzero(&mp->mnt_stat.f_fsid, sizeof(mp->mnt_stat.f_fsid));
374 for (;;) {
375 if (vfs_getvfs(template) == NULL)
376 break;
377 didmunge = 1;
378 ++template->val[1];
379 }
380 mp->mnt_stat.f_fsid = *template;
381 return(didmunge);
382 }
383
384 /*
385 * This routine is called when we have too many vnodes. It attempts
386 * to free <count> vnodes and will potentially free vnodes that still
387 * have VM backing store (VM backing store is typically the cause
388 * of a vnode blowout so we want to do this). Therefore, this operation
389 * is not considered cheap.
390 *
391 * A number of conditions may prevent a vnode from being reclaimed.
392 * the buffer cache may have references on the vnode, a directory
393 * vnode may still have references due to the namei cache representing
394 * underlying files, or the vnode may be in active use. It is not
395 * desireable to reuse such vnodes. These conditions may cause the
396 * number of vnodes to reach some minimum value regardless of what
397 * you set kern.maxvnodes to. Do not set kern.maxvnodes too low.
398 */
399
400 /*
401 * This is a quick non-blocking check to determine if the vnode is a good
402 * candidate for being (eventually) vgone()'d. Returns 0 if the vnode is
403 * not a good candidate, 1 if it is.
404 */
405 static __inline int
406 vmightfree(struct vnode *vp, int page_count)
407 {
408 if (vp->v_flag & VRECLAIMED)
409 return (0);
410 #if 0
411 if ((vp->v_flag & VFREE) && TAILQ_EMPTY(&vp->v_namecache))
412 return (0);
413 #endif
414 if (sysref_isactive(&vp->v_sysref))
415 return (0);
416 if (vp->v_object && vp->v_object->resident_page_count >= page_count)
417 return (0);
418 return (1);
419 }
420
421 /*
422 * The vnode was found to be possibly vgone()able and the caller has locked it
423 * (thus the usecount should be 1 now). Determine if the vnode is actually
424 * vgone()able, doing some cleanups in the process. Returns 1 if the vnode
425 * can be vgone()'d, 0 otherwise.
426 *
427 * Note that v_auxrefs may be non-zero because (A) this vnode is not a leaf
428 * in the namecache topology and (B) this vnode has buffer cache bufs.
429 * We cannot remove vnodes with non-leaf namecache associations. We do a
430 * tentitive leaf check prior to attempting to flush out any buffers but the
431 * 'real' test when all is said in done is that v_auxrefs must become 0 for
432 * the vnode to be freeable.
433 *
434 * We could theoretically just unconditionally flush when v_auxrefs != 0,
435 * but flushing data associated with non-leaf nodes (which are always
436 * directories), just throws it away for no benefit. It is the buffer
437 * cache's responsibility to choose buffers to recycle from the cached
438 * data point of view.
439 */
440 static int
441 visleaf(struct vnode *vp)
442 {
443 struct namecache *ncp;
444
445 TAILQ_FOREACH(ncp, &vp->v_namecache, nc_vnode) {
446 if (!TAILQ_EMPTY(&ncp->nc_list))
447 return(0);
448 }
449 return(1);
450 }
451
452 /*
453 * Try to clean up the vnode to the point where it can be vgone()'d, returning
454 * 0 if it cannot be vgone()'d (or already has been), 1 if it can. Unlike
455 * vmightfree() this routine may flush the vnode and block. Vnodes marked
456 * VFREE are still candidates for vgone()ing because they may hold namecache
457 * resources and could be blocking the namecache directory hierarchy (and
458 * related vnodes) from being freed.
459 */
460 static int
461 vtrytomakegoneable(struct vnode *vp, int page_count)
462 {
463 if (vp->v_flag & VRECLAIMED)
464 return (0);
465 if (vp->v_sysref.refcnt > 1)
466 return (0);
467 if (vp->v_object && vp->v_object->resident_page_count >= page_count)
468 return (0);
469 if (vp->v_auxrefs && visleaf(vp)) {
470 vinvalbuf(vp, V_SAVE, 0, 0);
471 #if 0 /* DEBUG */
472 kprintf((vp->v_auxrefs ? "vrecycle: vp %p failed: %s\n" :
473 "vrecycle: vp %p succeeded: %s\n"), vp,
474 (TAILQ_FIRST(&vp->v_namecache) ?
475 TAILQ_FIRST(&vp->v_namecache)->nc_name : "?"));
476 #endif
477 }
478
479 /*
480 * This sequence may seem a little strange, but we need to optimize
481 * the critical path a bit. We can't recycle vnodes with other
482 * references and because we are trying to recycle an otherwise
483 * perfectly fine vnode we have to invalidate the namecache in a
484 * way that avoids possible deadlocks (since the vnode lock is being
485 * held here). Finally, we have to check for other references one
486 * last time in case something snuck in during the inval.
487 */
488 if (vp->v_sysref.refcnt > 1 || vp->v_auxrefs != 0)
489 return (0);
490 if (cache_inval_vp_nonblock(vp))
491 return (0);
492 return (vp->v_sysref.refcnt <= 1 && vp->v_auxrefs == 0);
493 }
494
495 /*
496 * Reclaim up to 1/10 of the vnodes associated with a mount point. Try
497 * to avoid vnodes which have lots of resident pages (we are trying to free
498 * vnodes, not memory).
499 *
500 * This routine is a callback from the mountlist scan. The mount point
501 * in question will be busied.
502 */
503 static int
504 vlrureclaim(struct mount *mp, void *data)
505 {
506 struct vnode *vp;
507 lwkt_tokref ilock;
508 int done;
509 int trigger;
510 int usevnodes;
511 int count;
512 int trigger_mult = vnlru_nowhere;
513
514 /*
515 * Calculate the trigger point for the resident pages check. The
516 * minimum trigger value is approximately the number of pages in
517 * the system divded by the number of vnodes. However, due to
518 * various other system memory overheads unrelated to data caching
519 * it is a good idea to double the trigger (at least).
520 *
521 * trigger_mult starts at 0. If the recycler is having problems
522 * finding enough freeable vnodes it will increase trigger_mult.
523 * This should not happen in normal operation, even on machines with
524 * low amounts of memory, but extraordinary memory use by the system
525 * verses the amount of cached data can trigger it.
526 */
527 usevnodes = desiredvnodes;
528 if (usevnodes <= 0)
529 usevnodes = 1;
530 trigger = vmstats.v_page_count * (trigger_mult + 2) / usevnodes;
531
532 done = 0;
533 lwkt_gettoken(&ilock, &mntvnode_token);
534 count = mp->mnt_nvnodelistsize / 10 + 1;
535 while (count && mp->mnt_syncer) {
536 /*
537 * Next vnode. Use the special syncer vnode to placemark
538 * the LRU. This way the LRU code does not interfere with
539 * vmntvnodescan().
540 */
541 vp = TAILQ_NEXT(mp->mnt_syncer, v_nmntvnodes);
542 TAILQ_REMOVE(&mp->mnt_nvnodelist, mp->mnt_syncer, v_nmntvnodes);
543 if (vp) {
544 TAILQ_INSERT_AFTER(&mp->mnt_nvnodelist, vp,
545 mp->mnt_syncer, v_nmntvnodes);
546 } else {
547 TAILQ_INSERT_HEAD(&mp->mnt_nvnodelist, mp->mnt_syncer,
548 v_nmntvnodes);
549 vp = TAILQ_NEXT(mp->mnt_syncer, v_nmntvnodes);
550 if (vp == NULL)
551 break;
552 }
553
554 /*
555 * __VNODESCAN__
556 *
557 * The VP will stick around while we hold mntvnode_token,
558 * at least until we block, so we can safely do an initial
559 * check, and then must check again after we lock the vnode.
560 */
561 if (vp->v_type == VNON || /* syncer or indeterminant */
562 !vmightfree(vp, trigger) /* critical path opt */
563 ) {
564 --count;
565 continue;
566 }
567
568 /*
569 * VX get the candidate vnode. If the VX get fails the
570 * vnode might still be on the mountlist. Our loop depends
571 * on us at least cycling the vnode to the end of the
572 * mountlist.
573 */
574 if (vx_get_nonblock(vp) != 0) {
575 --count;
576 continue;
577 }
578
579 /*
580 * Since we blocked locking the vp, make sure it is still
581 * a candidate for reclamation. That is, it has not already
582 * been reclaimed and only has our VX reference associated
583 * with it.
584 */
585 if (vp->v_type == VNON || /* syncer or indeterminant */
586 (vp->v_flag & VRECLAIMED) ||
587 vp->v_mount != mp ||
588 !vtrytomakegoneable(vp, trigger) /* critical path opt */
589 ) {
590 --count;
591 vx_put(vp);
592 continue;
593 }
594
595 /*
596 * All right, we are good, move the vp to the end of the
597 * mountlist and clean it out. The vget will have returned
598 * an error if the vnode was destroyed (VRECLAIMED set), so we
599 * do not have to check again. The vput() will move the
600 * vnode to the free list if the vgone() was successful.
601 */
602 KKASSERT(vp->v_mount == mp);
603 vgone_vxlocked(vp);
604 vx_put(vp);
605 ++done;
606 --count;
607 }
608 lwkt_reltoken(&ilock);
609 return (done);
610 }
611
612 /*
613 * Attempt to recycle vnodes in a context that is always safe to block.
614 * Calling vlrurecycle() from the bowels of file system code has some
615 * interesting deadlock problems.
616 */
617 static struct thread *vnlruthread;
618 static int vnlruproc_sig;
619
620 void
621 vnlru_proc_wait(void)
622 {
623 if (vnlruproc_sig == 0) {
624 vnlruproc_sig = 1; /* avoid unnecessary wakeups */
625 wakeup(vnlruthread);
626 }
627 tsleep(&vnlruproc_sig, 0, "vlruwk", hz);
628 }
629
630 static void
631 vnlru_proc(void)
632 {
633 struct thread *td = curthread;
634 int done;
635
636 EVENTHANDLER_REGISTER(shutdown_pre_sync, shutdown_kproc, td,
637 SHUTDOWN_PRI_FIRST);
638
639 crit_enter();
640 for (;;) {
641 kproc_suspend_loop();
642
643 /*
644 * Try to free some vnodes if we have too many
645 */
646 if (numvnodes > desiredvnodes &&
647 freevnodes > desiredvnodes * 2 / 10) {
648 int count = numvnodes - desiredvnodes;
649
650 if (count > freevnodes / 100)
651 count = freevnodes / 100;
652 if (count < 5)
653 count = 5;
654 freesomevnodes(count);
655 }
656
657 /*
658 * Nothing to do if most of our vnodes are already on
659 * the free list.
660 */
661 if (numvnodes - freevnodes <= desiredvnodes * 9 / 10) {
662 vnlruproc_sig = 0;
663 wakeup(&vnlruproc_sig);
664 tsleep(td, 0, "vlruwt", hz);
665 continue;
666 }
667 cache_cleanneg(0);
668 done = mountlist_scan(vlrureclaim, NULL, MNTSCAN_FORWARD);
669
670 /*
671 * The vlrureclaim() call only processes 1/10 of the vnodes
672 * on each mount. If we couldn't find any repeat the loop
673 * at least enough times to cover all available vnodes before
674 * we start sleeping. Complain if the failure extends past
675 * 30 second, every 30 seconds.
676 */
677 if (done == 0) {
678 ++vnlru_nowhere;
679 if (vnlru_nowhere % 10 == 0)
680 tsleep(td, 0, "vlrup", hz * 3);
681 if (vnlru_nowhere % 100 == 0)
682 kprintf("vnlru_proc: vnode recycler stopped working!\n");
683 if (vnlru_nowhere == 1000)
684 vnlru_nowhere = 900;
685 } else {
686 vnlru_nowhere = 0;
687 }
688 }
689 crit_exit();
690 }
691
692 /*
693 * MOUNTLIST FUNCTIONS
694 */
695
696 /*
697 * mountlist_insert (MP SAFE)
698 *
699 * Add a new mount point to the mount list.
700 */
701 void
702 mountlist_insert(struct mount *mp, int how)
703 {
704 lwkt_tokref ilock;
705
706 lwkt_gettoken(&ilock, &mountlist_token);
707 if (how == MNTINS_FIRST)
708 TAILQ_INSERT_HEAD(&mountlist, mp, mnt_list);
709 else
710 TAILQ_INSERT_TAIL(&mountlist, mp, mnt_list);
711 lwkt_reltoken(&ilock);
712 }
713
714 /*
715 * mountlist_interlock (MP SAFE)
716 *
717 * Execute the specified interlock function with the mountlist token
718 * held. The function will be called in a serialized fashion verses
719 * other functions called through this mechanism.
720 */
721 int
722 mountlist_interlock(int (*callback)(struct mount *), struct mount *mp)
723 {
724 lwkt_tokref ilock;
725 int error;
726
727 lwkt_gettoken(&ilock, &mountlist_token);
728 error = callback(mp);
729 lwkt_reltoken(&ilock);
730 return (error);
731 }
732
733 /*
734 * mountlist_boot_getfirst (DURING BOOT ONLY)
735 *
736 * This function returns the first mount on the mountlist, which is
737 * expected to be the root mount. Since no interlocks are obtained
738 * this function is only safe to use during booting.
739 */
740
741 struct mount *
742 mountlist_boot_getfirst(void)
743 {
744 return(TAILQ_FIRST(&mountlist));
745 }
746
747 /*
748 * mountlist_remove (MP SAFE)
749 *
750 * Remove a node from the mountlist. If this node is the next scan node
751 * for any active mountlist scans, the active mountlist scan will be
752 * adjusted to skip the node, thus allowing removals during mountlist
753 * scans.
754 */
755 void
756 mountlist_remove(struct mount *mp)
757 {
758 struct mountscan_info *msi;
759 lwkt_tokref ilock;
760
761 lwkt_gettoken(&ilock, &mountlist_token);
762 TAILQ_FOREACH(msi, &mountscan_list, msi_entry) {
763 if (msi->msi_node == mp) {
764 if (msi->msi_how & MNTSCAN_FORWARD)
765 msi->msi_node = TAILQ_NEXT(mp, mnt_list);
766 else
767 msi->msi_node = TAILQ_PREV(mp, mntlist, mnt_list);
768 }
769 }
770 TAILQ_REMOVE(&mountlist, mp, mnt_list);
771 lwkt_reltoken(&ilock);
772 }
773
774 /*
775 * mountlist_scan (MP SAFE)
776 *
777 * Safely scan the mount points on the mount list. Unless otherwise
778 * specified each mount point will be busied prior to the callback and
779 * unbusied afterwords. The callback may safely remove any mount point
780 * without interfering with the scan. If the current callback
781 * mount is removed the scanner will not attempt to unbusy it.
782 *
783 * If a mount node cannot be busied it is silently skipped.
784 *
785 * The callback return value is aggregated and a total is returned. A return
786 * value of < 0 is not aggregated and will terminate the scan.
787 *
788 * MNTSCAN_FORWARD - the mountlist is scanned in the forward direction
789 * MNTSCAN_REVERSE - the mountlist is scanned in reverse
790 * MNTSCAN_NOBUSY - the scanner will make the callback without busying
791 * the mount node.
792 */
793 int
794 mountlist_scan(int (*callback)(struct mount *, void *), void *data, int how)
795 {
796 struct mountscan_info info;
797 lwkt_tokref ilock;
798 struct mount *mp;
799 thread_t td;
800 int count;
801 int res;
802
803 lwkt_gettoken(&ilock, &mountlist_token);
804
805 info.msi_how = how;
806 info.msi_node = NULL; /* paranoia */
807 TAILQ_INSERT_TAIL(&mountscan_list, &info, msi_entry);
808
809 res = 0;
810 td = curthread;
811
812 if (how & MNTSCAN_FORWARD) {
813 info.msi_node = TAILQ_FIRST(&mountlist);
814 while ((mp = info.msi_node) != NULL) {
815 if (how & MNTSCAN_NOBUSY) {
816 count = callback(mp, data);
817 } else if (vfs_busy(mp, LK_NOWAIT) == 0) {
818 count = callback(mp, data);
819 if (mp == info.msi_node)
820 vfs_unbusy(mp);
821 } else {
822 count = 0;
823 }
824 if (count < 0)
825 break;
826 res += count;
827 if (mp == info.msi_node)
828 info.msi_node = TAILQ_NEXT(mp, mnt_list);
829 }
830 } else if (how & MNTSCAN_REVERSE) {
831 info.msi_node = TAILQ_LAST(&mountlist, mntlist);
832 while ((mp = info.msi_node) != NULL) {
833 if (how & MNTSCAN_NOBUSY) {
834 count = callback(mp, data);
835 } else if (vfs_busy(mp, LK_NOWAIT) == 0) {
836 count = callback(mp, data);
837 if (mp == info.msi_node)
838 vfs_unbusy(mp);
839 } else {
840 count = 0;
841 }
842 if (count < 0)
843 break;
844 res += count;
845 if (mp == info.msi_node)
846 info.msi_node = TAILQ_PREV(mp, mntlist, mnt_list);
847 }
848 }
849 TAILQ_REMOVE(&mountscan_list, &info, msi_entry);
850 lwkt_reltoken(&ilock);
851 return(res);
852 }
853
854 /*
855 * MOUNT RELATED VNODE FUNCTIONS
856 */
857
858 static struct kproc_desc vnlru_kp = {
859 "vnlru",
860 vnlru_proc,
861 &vnlruthread
862 };
863 SYSINIT(vnlru, SI_SUB_KTHREAD_UPDATE, SI_ORDER_FIRST, kproc_start, &vnlru_kp)
864
865 /*
866 * Move a vnode from one mount queue to another.
867 */
868 void
869 insmntque(struct vnode *vp, struct mount *mp)
870 {
871 lwkt_tokref ilock;
872
873 lwkt_gettoken(&ilock, &mntvnode_token);
874 /*
875 * Delete from old mount point vnode list, if on one.
876 */
877 if (vp->v_mount != NULL) {
878 KASSERT(vp->v_mount->mnt_nvnodelistsize > 0,
879 ("bad mount point vnode list size"));
880 vremovevnodemnt(vp);
881 vp->v_mount->mnt_nvnodelistsize--;
882 }
883 /*
884 * Insert into list of vnodes for the new mount point, if available.
885 * The 'end' of the LRU list is the vnode prior to mp->mnt_syncer.
886 */
887 if ((vp->v_mount = mp) == NULL) {
888 lwkt_reltoken(&ilock);
889 return;
890 }
891 if (mp->mnt_syncer) {
892 TAILQ_INSERT_BEFORE(mp->mnt_syncer, vp, v_nmntvnodes);
893 } else {
894 TAILQ_INSERT_TAIL(&mp->mnt_nvnodelist, vp, v_nmntvnodes);
895 }
896 mp->mnt_nvnodelistsize++;
897 lwkt_reltoken(&ilock);
898 }
899
900
901 /*
902 * Scan the vnodes under a mount point and issue appropriate callbacks.
903 *
904 * The fastfunc() callback is called with just the mountlist token held
905 * (no vnode lock). It may not block and the vnode may be undergoing
906 * modifications while the caller is processing it. The vnode will
907 * not be entirely destroyed, however, due to the fact that the mountlist
908 * token is held. A return value < 0 skips to the next vnode without calling
909 * the slowfunc(), a return value > 0 terminates the loop.
910 *
911 * The slowfunc() callback is called after the vnode has been successfully
912 * locked based on passed flags. The vnode is skipped if it gets rearranged
913 * or destroyed while blocking on the lock. A non-zero return value from
914 * the slow function terminates the loop. The slow function is allowed to
915 * arbitrarily block. The scanning code guarentees consistency of operation
916 * even if the slow function deletes or moves the node, or blocks and some
917 * other thread deletes or moves the node.
918 */
919 int
920 vmntvnodescan(
921 struct mount *mp,
922 int flags,
923 int (*fastfunc)(struct mount *mp, struct vnode *vp, void *data),
924 int (*slowfunc)(struct mount *mp, struct vnode *vp, void *data),
925 void *data
926 ) {
927 struct vmntvnodescan_info info;
928 lwkt_tokref ilock;
929 struct vnode *vp;
930 int r = 0;
931 int maxcount = 1000000;
932 int stopcount = 0;
933 int count = 0;
934
935 lwkt_gettoken(&ilock, &mntvnode_token);
936
937 /*
938 * If asked to do one pass stop after iterating available vnodes.
939 * Under heavy loads new vnodes can be added while we are scanning,
940 * so this isn't perfect. Create a slop factor of 2x.
941 */
942 if (flags & VMSC_ONEPASS)
943 stopcount = mp->mnt_nvnodelistsize * 2;
944
945 info.vp = TAILQ_FIRST(&mp->mnt_nvnodelist);
946 TAILQ_INSERT_TAIL(&mntvnodescan_list, &info, entry);
947 while ((vp = info.vp) != NULL) {
948 if (--maxcount == 0)
949 panic("maxcount reached during vmntvnodescan");
950
951 /*
952 * Skip if visible but not ready, or special (e.g.
953 * mp->mnt_syncer)
954 */
955 if (vp->v_type == VNON)
956 goto next;
957 KKASSERT(vp->v_mount == mp);
958
959 /*
960 * Quick test. A negative return continues the loop without
961 * calling the slow test. 0 continues onto the slow test.
962 * A positive number aborts the loop.
963 */
964 if (fastfunc) {
965 if ((r = fastfunc(mp, vp, data)) < 0) {
966 r = 0;
967 goto next;
968 }
969 if (r)
970 break;
971 }
972
973 /*
974 * Get a vxlock on the vnode, retry if it has moved or isn't
975 * in the mountlist where we expect it.
976 */
977 if (slowfunc) {
978 int error;
979
980 switch(flags & (VMSC_GETVP|VMSC_GETVX|VMSC_NOWAIT)) {
981 case VMSC_GETVP:
982 error = vget(vp, LK_EXCLUSIVE);
983 break;
984 case VMSC_GETVP|VMSC_NOWAIT:
985 error = vget(vp, LK_EXCLUSIVE|LK_NOWAIT);
986 break;
987 case VMSC_GETVX:
988 vx_get(vp);
989 error = 0;
990 break;
991 default:
992 error = 0;
993 break;
994 }
995 if (error)
996 goto next;
997 /*
998 * Do not call the slow function if the vnode is
999 * invalid or if it was ripped out from under us
1000 * while we (potentially) blocked.
1001 */
1002 if (info.vp == vp && vp->v_type != VNON)
1003 r = slowfunc(mp, vp, data);
1004
1005 /*
1006 * Cleanup
1007 */
1008 switch(flags & (VMSC_GETVP|VMSC_GETVX|VMSC_NOWAIT)) {
1009 case VMSC_GETVP:
1010 case VMSC_GETVP|VMSC_NOWAIT:
1011 vput(vp);
1012 break;
1013 case VMSC_GETVX:
1014 vx_put(vp);
1015 break;
1016 default:
1017 break;
1018 }
1019 if (r != 0)
1020 break;
1021 }
1022
1023 next:
1024 /*
1025 * Yield after some processing. Depending on the number
1026 * of vnodes, we might wind up running for a long time.
1027 * Because threads are not preemptable, time critical
1028 * userland processes might starve. Give them a chance
1029 * now and then.
1030 */
1031 if (++count == 10000) {
1032 /* We really want to yield a bit, so we simply sleep a tick */
1033 tsleep(mp, 0, "vnodescn", 1);
1034 count = 0;
1035 }
1036
1037 /*
1038 * If doing one pass this decrements to zero. If it starts
1039 * at zero it is effectively unlimited for the purposes of
1040 * this loop.
1041 */
1042 if (--stopcount == 0)
1043 break;
1044
1045 /*
1046 * Iterate. If the vnode was ripped out from under us
1047 * info.vp will already point to the next vnode, otherwise
1048 * we have to obtain the next valid vnode ourselves.
1049 */
1050 if (info.vp == vp)
1051 info.vp = TAILQ_NEXT(vp, v_nmntvnodes);
1052 }
1053 TAILQ_REMOVE(&mntvnodescan_list, &info, entry);
1054 lwkt_reltoken(&ilock);
1055 return(r);
1056 }
1057
1058 /*
1059 * Remove any vnodes in the vnode table belonging to mount point mp.
1060 *
1061 * If FORCECLOSE is not specified, there should not be any active ones,
1062 * return error if any are found (nb: this is a user error, not a
1063 * system error). If FORCECLOSE is specified, detach any active vnodes
1064 * that are found.
1065 *
1066 * If WRITECLOSE is set, only flush out regular file vnodes open for
1067 * writing.
1068 *
1069 * SKIPSYSTEM causes any vnodes marked VSYSTEM to be skipped.
1070 *
1071 * `rootrefs' specifies the base reference count for the root vnode
1072 * of this filesystem. The root vnode is considered busy if its
1073 * v_sysref.refcnt exceeds this value. On a successful return, vflush()
1074 * will call vrele() on the root vnode exactly rootrefs times.
1075 * If the SKIPSYSTEM or WRITECLOSE flags are specified, rootrefs must
1076 * be zero.
1077 */
1078 #ifdef DIAGNOSTIC
1079 static int busyprt = 0; /* print out busy vnodes */
1080 SYSCTL_INT(_debug, OID_AUTO, busyprt, CTLFLAG_RW, &busyprt, 0, "");
1081 #endif
1082
1083 static int vflush_scan(struct mount *mp, struct vnode *vp, void *data);
1084
1085 struct vflush_info {
1086 int flags;
1087 int busy;
1088 thread_t td;
1089 };
1090
1091 int
1092 vflush(struct mount *mp, int rootrefs, int flags)
1093 {
1094 struct thread *td = curthread; /* XXX */
1095 struct vnode *rootvp = NULL;
1096 int error;
1097 struct vflush_info vflush_info;
1098
1099 if (rootrefs > 0) {
1100 KASSERT((flags & (SKIPSYSTEM | WRITECLOSE)) == 0,
1101 ("vflush: bad args"));
1102 /*
1103 * Get the filesystem root vnode. We can vput() it
1104 * immediately, since with rootrefs > 0, it won't go away.
1105 */
1106 if ((error = VFS_ROOT(mp, &rootvp)) != 0)
1107 return (error);
1108 vput(rootvp);
1109 }
1110
1111 vflush_info.busy = 0;
1112 vflush_info.flags = flags;
1113 vflush_info.td = td;
1114 vmntvnodescan(mp, VMSC_GETVX, NULL, vflush_scan, &vflush_info);
1115
1116 if (rootrefs > 0 && (flags & FORCECLOSE) == 0) {
1117 /*
1118 * If just the root vnode is busy, and if its refcount
1119 * is equal to `rootrefs', then go ahead and kill it.
1120 */
1121 KASSERT(vflush_info.busy > 0, ("vflush: not busy"));
1122 KASSERT(rootvp->v_sysref.refcnt >= rootrefs, ("vflush: rootrefs"));
1123 if (vflush_info.busy == 1 && rootvp->v_sysref.refcnt == rootrefs) {
1124 vx_lock(rootvp);
1125 vgone_vxlocked(rootvp);
1126 vx_unlock(rootvp);
1127 vflush_info.busy = 0;
1128 }
1129 }
1130 if (vflush_info.busy)
1131 return (EBUSY);
1132 for (; rootrefs > 0; rootrefs--)
1133 vrele(rootvp);
1134 return (0);
1135 }
1136
1137 /*
1138 * The scan callback is made with an VX locked vnode.
1139 */
1140 static int
1141 vflush_scan(struct mount *mp, struct vnode *vp, void *data)
1142 {
1143 struct vflush_info *info = data;
1144 struct vattr vattr;
1145
1146 /*
1147 * Skip over a vnodes marked VSYSTEM.
1148 */
1149 if ((info->flags & SKIPSYSTEM) && (vp->v_flag & VSYSTEM)) {
1150 return(0);
1151 }
1152
1153 /*
1154 * If WRITECLOSE is set, flush out unlinked but still open
1155 * files (even if open only for reading) and regular file
1156 * vnodes open for writing.
1157 */
1158 if ((info->flags & WRITECLOSE) &&
1159 (vp->v_type == VNON ||
1160 (VOP_GETATTR(vp, &vattr) == 0 &&
1161 vattr.va_nlink > 0)) &&
1162 (vp->v_writecount == 0 || vp->v_type != VREG)) {
1163 return(0);
1164 }
1165
1166 /*
1167 * If we are the only holder (refcnt of 1) or the vnode is in
1168 * termination (refcnt < 0), we can vgone the vnode.
1169 */
1170 if (vp->v_sysref.refcnt <= 1) {
1171 vgone_vxlocked(vp);
1172 return(0);
1173 }
1174
1175 /*
1176 * If FORCECLOSE is set, forcibly close the vnode. For block
1177 * or character devices, revert to an anonymous device. For
1178 * all other files, just kill them.
1179 */
1180 if (info->flags & FORCECLOSE) {
1181 if (vp->v_type != VBLK && vp->v_type != VCHR) {
1182 vgone_vxlocked(vp);
1183 } else {
1184 vclean_vxlocked(vp, 0);
1185 vp->v_ops = &spec_vnode_vops_p;
1186 insmntque(vp, NULL);
1187 }
1188 return(0);
1189 }
1190 #ifdef DIAGNOSTIC
1191 if (busyprt)
1192 vprint("vflush: busy vnode", vp);
1193 #endif
1194 ++info->busy;
1195 return(0);
1196 }
1197
1198 void
1199 add_bio_ops(struct bio_ops *ops)
1200 {
1201 TAILQ_INSERT_TAIL(&bio_ops_list, ops, entry);
1202 }
1203
1204 void
1205 rem_bio_ops(struct bio_ops *ops)
1206 {
1207 TAILQ_REMOVE(&bio_ops_list, ops, entry);
1208 }
1209
1210 /*
1211 * This calls the bio_ops io_sync function either for a mount point
1212 * or generally.
1213 *
1214 * WARNING: softdeps is weirdly coded and just isn't happy unless
1215 * io_sync is called with a NULL mount from the general syncing code.
1216 */
1217 void
1218 bio_ops_sync(struct mount *mp)
1219 {
1220 struct bio_ops *ops;
1221
1222 if (mp) {
1223 if ((ops = mp->mnt_bioops) != NULL)
1224 ops->io_sync(mp);
1225 } else {
1226 TAILQ_FOREACH(ops, &bio_ops_list, entry) {
1227 ops->io_sync(NULL);
1228 }
1229 }
1230 }
1231
Cache object: 56cb4049aceb5cbcb013c8faa0e09eb0
|