1 /*-
2 * SPDX-License-Identifier: BSD-4-Clause
3 *
4 * Copyright (c) 1998 Matthew Dillon,
5 * Copyright (c) 1994 John S. Dyson
6 * Copyright (c) 1990 University of Utah.
7 * Copyright (c) 1982, 1986, 1989, 1993
8 * The Regents of the University of California. All rights reserved.
9 *
10 * This code is derived from software contributed to Berkeley by
11 * the Systems Programming Group of the University of Utah Computer
12 * Science Department.
13 *
14 * Redistribution and use in source and binary forms, with or without
15 * modification, are permitted provided that the following conditions
16 * are met:
17 * 1. Redistributions of source code must retain the above copyright
18 * notice, this list of conditions and the following disclaimer.
19 * 2. Redistributions in binary form must reproduce the above copyright
20 * notice, this list of conditions and the following disclaimer in the
21 * documentation and/or other materials provided with the distribution.
22 * 3. All advertising materials mentioning features or use of this software
23 * must display the following acknowledgement:
24 * This product includes software developed by the University of
25 * California, Berkeley and its contributors.
26 * 4. Neither the name of the University nor the names of its contributors
27 * may be used to endorse or promote products derived from this software
28 * without specific prior written permission.
29 *
30 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
31 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
32 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
33 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
34 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
35 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
36 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
37 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
38 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
39 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
40 * SUCH DAMAGE.
41 *
42 * New Swap System
43 * Matthew Dillon
44 *
45 * Radix Bitmap 'blists'.
46 *
47 * - The new swapper uses the new radix bitmap code. This should scale
48 * to arbitrarily small or arbitrarily large swap spaces and an almost
49 * arbitrary degree of fragmentation.
50 *
51 * Features:
52 *
53 * - on the fly reallocation of swap during putpages. The new system
54 * does not try to keep previously allocated swap blocks for dirty
55 * pages.
56 *
57 * - on the fly deallocation of swap
58 *
59 * - No more garbage collection required. Unnecessarily allocated swap
60 * blocks only exist for dirty vm_page_t's now and these are already
61 * cycled (in a high-load system) by the pager. We also do on-the-fly
62 * removal of invalidated swap blocks when a page is destroyed
63 * or renamed.
64 *
65 * from: Utah $Hdr: swap_pager.c 1.4 91/04/30$
66 */
67
68 #include <sys/cdefs.h>
69 #include "opt_vm.h"
70
71 #include <sys/param.h>
72 #include <sys/bio.h>
73 #include <sys/blist.h>
74 #include <sys/buf.h>
75 #include <sys/conf.h>
76 #include <sys/disk.h>
77 #include <sys/disklabel.h>
78 #include <sys/eventhandler.h>
79 #include <sys/fcntl.h>
80 #include <sys/limits.h>
81 #include <sys/lock.h>
82 #include <sys/kernel.h>
83 #include <sys/mount.h>
84 #include <sys/namei.h>
85 #include <sys/malloc.h>
86 #include <sys/pctrie.h>
87 #include <sys/priv.h>
88 #include <sys/proc.h>
89 #include <sys/racct.h>
90 #include <sys/resource.h>
91 #include <sys/resourcevar.h>
92 #include <sys/rwlock.h>
93 #include <sys/sbuf.h>
94 #include <sys/sysctl.h>
95 #include <sys/sysproto.h>
96 #include <sys/systm.h>
97 #include <sys/sx.h>
98 #include <sys/unistd.h>
99 #include <sys/user.h>
100 #include <sys/vmmeter.h>
101 #include <sys/vnode.h>
102
103 #include <security/mac/mac_framework.h>
104
105 #include <vm/vm.h>
106 #include <vm/pmap.h>
107 #include <vm/vm_map.h>
108 #include <vm/vm_kern.h>
109 #include <vm/vm_object.h>
110 #include <vm/vm_page.h>
111 #include <vm/vm_pager.h>
112 #include <vm/vm_pageout.h>
113 #include <vm/vm_param.h>
114 #include <vm/swap_pager.h>
115 #include <vm/vm_extern.h>
116 #include <vm/uma.h>
117
118 #include <geom/geom.h>
119
120 /*
121 * MAX_PAGEOUT_CLUSTER must be a power of 2 between 1 and 64.
122 * The 64-page limit is due to the radix code (kern/subr_blist.c).
123 */
124 #ifndef MAX_PAGEOUT_CLUSTER
125 #define MAX_PAGEOUT_CLUSTER 32
126 #endif
127
128 #if !defined(SWB_NPAGES)
129 #define SWB_NPAGES MAX_PAGEOUT_CLUSTER
130 #endif
131
132 #define SWAP_META_PAGES PCTRIE_COUNT
133
134 /*
135 * A swblk structure maps each page index within a
136 * SWAP_META_PAGES-aligned and sized range to the address of an
137 * on-disk swap block (or SWAPBLK_NONE). The collection of these
138 * mappings for an entire vm object is implemented as a pc-trie.
139 */
140 struct swblk {
141 vm_pindex_t p;
142 daddr_t d[SWAP_META_PAGES];
143 };
144
145 static MALLOC_DEFINE(M_VMPGDATA, "vm_pgdata", "swap pager private data");
146 static struct mtx sw_dev_mtx;
147 static TAILQ_HEAD(, swdevt) swtailq = TAILQ_HEAD_INITIALIZER(swtailq);
148 static struct swdevt *swdevhd; /* Allocate from here next */
149 static int nswapdev; /* Number of swap devices */
150 int swap_pager_avail;
151 static struct sx swdev_syscall_lock; /* serialize swap(on|off) */
152
153 static __exclusive_cache_line u_long swap_reserved;
154 static u_long swap_total;
155 static int sysctl_page_shift(SYSCTL_HANDLER_ARGS);
156
157 static SYSCTL_NODE(_vm_stats, OID_AUTO, swap, CTLFLAG_RD | CTLFLAG_MPSAFE, 0,
158 "VM swap stats");
159
160 SYSCTL_PROC(_vm, OID_AUTO, swap_reserved, CTLTYPE_U64 | CTLFLAG_RD | CTLFLAG_MPSAFE,
161 &swap_reserved, 0, sysctl_page_shift, "QU",
162 "Amount of swap storage needed to back all allocated anonymous memory.");
163 SYSCTL_PROC(_vm, OID_AUTO, swap_total, CTLTYPE_U64 | CTLFLAG_RD | CTLFLAG_MPSAFE,
164 &swap_total, 0, sysctl_page_shift, "QU",
165 "Total amount of available swap storage.");
166
167 int vm_overcommit __read_mostly = 0;
168 SYSCTL_INT(_vm, VM_OVERCOMMIT, overcommit, CTLFLAG_RW, &vm_overcommit, 0,
169 "Configure virtual memory overcommit behavior. See tuning(7) "
170 "for details.");
171 static unsigned long swzone;
172 SYSCTL_ULONG(_vm, OID_AUTO, swzone, CTLFLAG_RD, &swzone, 0,
173 "Actual size of swap metadata zone");
174 static unsigned long swap_maxpages;
175 SYSCTL_ULONG(_vm, OID_AUTO, swap_maxpages, CTLFLAG_RD, &swap_maxpages, 0,
176 "Maximum amount of swap supported");
177
178 static COUNTER_U64_DEFINE_EARLY(swap_free_deferred);
179 SYSCTL_COUNTER_U64(_vm_stats_swap, OID_AUTO, free_deferred,
180 CTLFLAG_RD, &swap_free_deferred,
181 "Number of pages that deferred freeing swap space");
182
183 static COUNTER_U64_DEFINE_EARLY(swap_free_completed);
184 SYSCTL_COUNTER_U64(_vm_stats_swap, OID_AUTO, free_completed,
185 CTLFLAG_RD, &swap_free_completed,
186 "Number of deferred frees completed");
187
188 static int
sysctl_page_shift(SYSCTL_HANDLER_ARGS)189 sysctl_page_shift(SYSCTL_HANDLER_ARGS)
190 {
191 uint64_t newval;
192 u_long value = *(u_long *)arg1;
193
194 newval = ((uint64_t)value) << PAGE_SHIFT;
195 return (sysctl_handle_64(oidp, &newval, 0, req));
196 }
197
198 static bool
swap_reserve_by_cred_rlimit(u_long pincr,struct ucred * cred,int oc)199 swap_reserve_by_cred_rlimit(u_long pincr, struct ucred *cred, int oc)
200 {
201 struct uidinfo *uip;
202 u_long prev;
203
204 uip = cred->cr_ruidinfo;
205
206 prev = atomic_fetchadd_long(&uip->ui_vmsize, pincr);
207 if ((oc & SWAP_RESERVE_RLIMIT_ON) != 0 &&
208 prev + pincr > lim_cur(curthread, RLIMIT_SWAP) &&
209 priv_check(curthread, PRIV_VM_SWAP_NORLIMIT) != 0) {
210 prev = atomic_fetchadd_long(&uip->ui_vmsize, -pincr);
211 KASSERT(prev >= pincr,
212 ("negative vmsize for uid %d\n", uip->ui_uid));
213 return (false);
214 }
215 return (true);
216 }
217
218 static void
swap_release_by_cred_rlimit(u_long pdecr,struct ucred * cred)219 swap_release_by_cred_rlimit(u_long pdecr, struct ucred *cred)
220 {
221 struct uidinfo *uip;
222 #ifdef INVARIANTS
223 u_long prev;
224 #endif
225
226 uip = cred->cr_ruidinfo;
227
228 #ifdef INVARIANTS
229 prev = atomic_fetchadd_long(&uip->ui_vmsize, -pdecr);
230 KASSERT(prev >= pdecr,
231 ("negative vmsize for uid %d\n", uip->ui_uid));
232 #else
233 atomic_subtract_long(&uip->ui_vmsize, pdecr);
234 #endif
235 }
236
237 static void
swap_reserve_force_rlimit(u_long pincr,struct ucred * cred)238 swap_reserve_force_rlimit(u_long pincr, struct ucred *cred)
239 {
240 struct uidinfo *uip;
241
242 uip = cred->cr_ruidinfo;
243 atomic_add_long(&uip->ui_vmsize, pincr);
244 }
245
246 bool
swap_reserve(vm_ooffset_t incr)247 swap_reserve(vm_ooffset_t incr)
248 {
249
250 return (swap_reserve_by_cred(incr, curthread->td_ucred));
251 }
252
253 bool
swap_reserve_by_cred(vm_ooffset_t incr,struct ucred * cred)254 swap_reserve_by_cred(vm_ooffset_t incr, struct ucred *cred)
255 {
256 u_long r, s, prev, pincr;
257 #ifdef RACCT
258 int error;
259 #endif
260 int oc;
261 static int curfail;
262 static struct timeval lastfail;
263
264 KASSERT((incr & PAGE_MASK) == 0, ("%s: incr: %ju & PAGE_MASK",
265 __func__, (uintmax_t)incr));
266
267 #ifdef RACCT
268 if (RACCT_ENABLED()) {
269 PROC_LOCK(curproc);
270 error = racct_add(curproc, RACCT_SWAP, incr);
271 PROC_UNLOCK(curproc);
272 if (error != 0)
273 return (false);
274 }
275 #endif
276
277 pincr = atop(incr);
278 prev = atomic_fetchadd_long(&swap_reserved, pincr);
279 r = prev + pincr;
280 s = swap_total;
281 oc = atomic_load_int(&vm_overcommit);
282 if (r > s && (oc & SWAP_RESERVE_ALLOW_NONWIRED) != 0) {
283 s += vm_cnt.v_page_count - vm_cnt.v_free_reserved -
284 vm_wire_count();
285 }
286 if ((oc & SWAP_RESERVE_FORCE_ON) != 0 && r > s &&
287 priv_check(curthread, PRIV_VM_SWAP_NOQUOTA) != 0) {
288 prev = atomic_fetchadd_long(&swap_reserved, -pincr);
289 KASSERT(prev >= pincr,
290 ("swap_reserved < incr on overcommit fail"));
291 goto out_error;
292 }
293
294 if (!swap_reserve_by_cred_rlimit(pincr, cred, oc)) {
295 prev = atomic_fetchadd_long(&swap_reserved, -pincr);
296 KASSERT(prev >= pincr,
297 ("swap_reserved < incr on overcommit fail"));
298 goto out_error;
299 }
300
301 return (true);
302
303 out_error:
304 if (ppsratecheck(&lastfail, &curfail, 1)) {
305 printf("uid %d, pid %d: swap reservation "
306 "for %jd bytes failed\n",
307 cred->cr_ruidinfo->ui_uid, curproc->p_pid, incr);
308 }
309 #ifdef RACCT
310 if (RACCT_ENABLED()) {
311 PROC_LOCK(curproc);
312 racct_sub(curproc, RACCT_SWAP, incr);
313 PROC_UNLOCK(curproc);
314 }
315 #endif
316
317 return (false);
318 }
319
320 void
swap_reserve_force(vm_ooffset_t incr)321 swap_reserve_force(vm_ooffset_t incr)
322 {
323 u_long pincr;
324
325 KASSERT((incr & PAGE_MASK) == 0, ("%s: incr: %ju & PAGE_MASK",
326 __func__, (uintmax_t)incr));
327
328 #ifdef RACCT
329 if (RACCT_ENABLED()) {
330 PROC_LOCK(curproc);
331 racct_add_force(curproc, RACCT_SWAP, incr);
332 PROC_UNLOCK(curproc);
333 }
334 #endif
335 pincr = atop(incr);
336 atomic_add_long(&swap_reserved, pincr);
337 swap_reserve_force_rlimit(pincr, curthread->td_ucred);
338 }
339
340 void
swap_release(vm_ooffset_t decr)341 swap_release(vm_ooffset_t decr)
342 {
343 struct ucred *cred;
344
345 PROC_LOCK(curproc);
346 cred = curproc->p_ucred;
347 swap_release_by_cred(decr, cred);
348 PROC_UNLOCK(curproc);
349 }
350
351 void
swap_release_by_cred(vm_ooffset_t decr,struct ucred * cred)352 swap_release_by_cred(vm_ooffset_t decr, struct ucred *cred)
353 {
354 u_long pdecr;
355 #ifdef INVARIANTS
356 u_long prev;
357 #endif
358
359 KASSERT((decr & PAGE_MASK) == 0, ("%s: decr: %ju & PAGE_MASK",
360 __func__, (uintmax_t)decr));
361
362 pdecr = atop(decr);
363 #ifdef INVARIANTS
364 prev = atomic_fetchadd_long(&swap_reserved, -pdecr);
365 KASSERT(prev >= pdecr, ("swap_reserved < decr"));
366 #else
367 atomic_subtract_long(&swap_reserved, pdecr);
368 #endif
369
370 swap_release_by_cred_rlimit(pdecr, cred);
371 #ifdef RACCT
372 if (racct_enable)
373 racct_sub_cred(cred, RACCT_SWAP, decr);
374 #endif
375 }
376
377 static int swap_pager_full = 2; /* swap space exhaustion (task killing) */
378 static int swap_pager_almost_full = 1; /* swap space exhaustion (w/hysteresis)*/
379 static struct mtx swbuf_mtx; /* to sync nsw_wcount_async */
380 static int nsw_wcount_async; /* limit async write buffers */
381 static int nsw_wcount_async_max;/* assigned maximum */
382 int nsw_cluster_max; /* maximum VOP I/O allowed */
383
384 static int sysctl_swap_async_max(SYSCTL_HANDLER_ARGS);
385 SYSCTL_PROC(_vm, OID_AUTO, swap_async_max, CTLTYPE_INT | CTLFLAG_RW |
386 CTLFLAG_MPSAFE, NULL, 0, sysctl_swap_async_max, "I",
387 "Maximum running async swap ops");
388 static int sysctl_swap_fragmentation(SYSCTL_HANDLER_ARGS);
389 SYSCTL_PROC(_vm, OID_AUTO, swap_fragmentation, CTLTYPE_STRING | CTLFLAG_RD |
390 CTLFLAG_MPSAFE, NULL, 0, sysctl_swap_fragmentation, "A",
391 "Swap Fragmentation Info");
392
393 static struct sx sw_alloc_sx;
394
395 /*
396 * "named" and "unnamed" anon region objects. Try to reduce the overhead
397 * of searching a named list by hashing it just a little.
398 */
399
400 #define NOBJLISTS 8
401
402 #define NOBJLIST(handle) \
403 (&swap_pager_object_list[((int)(intptr_t)handle >> 4) & (NOBJLISTS-1)])
404
405 static struct pagerlst swap_pager_object_list[NOBJLISTS];
406 static uma_zone_t swwbuf_zone;
407 static uma_zone_t swrbuf_zone;
408 static uma_zone_t swblk_zone;
409 static uma_zone_t swpctrie_zone;
410
411 /*
412 * pagerops for OBJT_SWAP - "swap pager". Some ops are also global procedure
413 * calls hooked from other parts of the VM system and do not appear here.
414 * (see vm/swap_pager.h).
415 */
416 static vm_object_t
417 swap_pager_alloc(void *handle, vm_ooffset_t size,
418 vm_prot_t prot, vm_ooffset_t offset, struct ucred *);
419 static void swap_pager_dealloc(vm_object_t object);
420 static int swap_pager_getpages(vm_object_t, vm_page_t *, int, int *,
421 int *);
422 static int swap_pager_getpages_async(vm_object_t, vm_page_t *, int, int *,
423 int *, pgo_getpages_iodone_t, void *);
424 static void swap_pager_putpages(vm_object_t, vm_page_t *, int, int, int *);
425 static boolean_t
426 swap_pager_haspage(vm_object_t object, vm_pindex_t pindex, int *before, int *after);
427 static void swap_pager_init(void);
428 static void swap_pager_unswapped(vm_page_t);
429 static void swap_pager_swapoff(struct swdevt *sp);
430 static void swap_pager_update_writecount(vm_object_t object,
431 vm_offset_t start, vm_offset_t end);
432 static void swap_pager_release_writecount(vm_object_t object,
433 vm_offset_t start, vm_offset_t end);
434 static void swap_pager_freespace_pgo(vm_object_t object, vm_pindex_t start,
435 vm_size_t size);
436
437 const struct pagerops swappagerops = {
438 .pgo_kvme_type = KVME_TYPE_SWAP,
439 .pgo_init = swap_pager_init, /* early system initialization of pager */
440 .pgo_alloc = swap_pager_alloc, /* allocate an OBJT_SWAP object */
441 .pgo_dealloc = swap_pager_dealloc, /* deallocate an OBJT_SWAP object */
442 .pgo_getpages = swap_pager_getpages, /* pagein */
443 .pgo_getpages_async = swap_pager_getpages_async, /* pagein (async) */
444 .pgo_putpages = swap_pager_putpages, /* pageout */
445 .pgo_haspage = swap_pager_haspage, /* get backing store status for page */
446 .pgo_pageunswapped = swap_pager_unswapped, /* remove swap related to page */
447 .pgo_update_writecount = swap_pager_update_writecount,
448 .pgo_release_writecount = swap_pager_release_writecount,
449 .pgo_freespace = swap_pager_freespace_pgo,
450 };
451
452 /*
453 * swap_*() routines are externally accessible. swp_*() routines are
454 * internal.
455 */
456 static int nswap_lowat = 128; /* in pages, swap_pager_almost_full warn */
457 static int nswap_hiwat = 512; /* in pages, swap_pager_almost_full warn */
458
459 SYSCTL_INT(_vm, OID_AUTO, dmmax, CTLFLAG_RD, &nsw_cluster_max, 0,
460 "Maximum size of a swap block in pages");
461
462 static void swp_sizecheck(void);
463 static void swp_pager_async_iodone(struct buf *bp);
464 static bool swp_pager_swblk_empty(struct swblk *sb, int start, int limit);
465 static void swp_pager_free_empty_swblk(vm_object_t, struct swblk *sb);
466 static int swapongeom(struct vnode *);
467 static int swaponvp(struct thread *, struct vnode *, u_long);
468 static int swapoff_one(struct swdevt *sp, struct ucred *cred,
469 u_int flags);
470
471 /*
472 * Swap bitmap functions
473 */
474 static void swp_pager_freeswapspace(daddr_t blk, daddr_t npages);
475 static daddr_t swp_pager_getswapspace(int *npages);
476
477 /*
478 * Metadata functions
479 */
480 static daddr_t swp_pager_meta_build(vm_object_t, vm_pindex_t, daddr_t);
481 static void swp_pager_meta_free(vm_object_t, vm_pindex_t, vm_pindex_t,
482 vm_size_t *);
483 static void swp_pager_meta_transfer(vm_object_t src, vm_object_t dst,
484 vm_pindex_t pindex, vm_pindex_t count, vm_size_t *freed);
485 static void swp_pager_meta_free_all(vm_object_t);
486 static daddr_t swp_pager_meta_lookup(vm_object_t, vm_pindex_t);
487
488 static void
swp_pager_init_freerange(daddr_t * start,daddr_t * num)489 swp_pager_init_freerange(daddr_t *start, daddr_t *num)
490 {
491
492 *start = SWAPBLK_NONE;
493 *num = 0;
494 }
495
496 static void
swp_pager_update_freerange(daddr_t * start,daddr_t * num,daddr_t addr)497 swp_pager_update_freerange(daddr_t *start, daddr_t *num, daddr_t addr)
498 {
499
500 if (*start + *num == addr) {
501 (*num)++;
502 } else {
503 swp_pager_freeswapspace(*start, *num);
504 *start = addr;
505 *num = 1;
506 }
507 }
508
509 static void *
swblk_trie_alloc(struct pctrie * ptree)510 swblk_trie_alloc(struct pctrie *ptree)
511 {
512
513 return (uma_zalloc(swpctrie_zone, M_NOWAIT | (curproc == pageproc ?
514 M_USE_RESERVE : 0)));
515 }
516
517 static void
swblk_trie_free(struct pctrie * ptree,void * node)518 swblk_trie_free(struct pctrie *ptree, void *node)
519 {
520
521 uma_zfree(swpctrie_zone, node);
522 }
523
524 PCTRIE_DEFINE(SWAP, swblk, p, swblk_trie_alloc, swblk_trie_free);
525
526 /*
527 * SWP_SIZECHECK() - update swap_pager_full indication
528 *
529 * update the swap_pager_almost_full indication and warn when we are
530 * about to run out of swap space, using lowat/hiwat hysteresis.
531 *
532 * Clear swap_pager_full ( task killing ) indication when lowat is met.
533 *
534 * No restrictions on call
535 * This routine may not block.
536 */
537 static void
swp_sizecheck(void)538 swp_sizecheck(void)
539 {
540
541 if (swap_pager_avail < nswap_lowat) {
542 if (swap_pager_almost_full == 0) {
543 printf("swap_pager: out of swap space\n");
544 swap_pager_almost_full = 1;
545 }
546 } else {
547 swap_pager_full = 0;
548 if (swap_pager_avail > nswap_hiwat)
549 swap_pager_almost_full = 0;
550 }
551 }
552
553 /*
554 * SWAP_PAGER_INIT() - initialize the swap pager!
555 *
556 * Expected to be started from system init. NOTE: This code is run
557 * before much else so be careful what you depend on. Most of the VM
558 * system has yet to be initialized at this point.
559 */
560 static void
swap_pager_init(void)561 swap_pager_init(void)
562 {
563 /*
564 * Initialize object lists
565 */
566 int i;
567
568 for (i = 0; i < NOBJLISTS; ++i)
569 TAILQ_INIT(&swap_pager_object_list[i]);
570 mtx_init(&sw_dev_mtx, "swapdev", NULL, MTX_DEF);
571 sx_init(&sw_alloc_sx, "swspsx");
572 sx_init(&swdev_syscall_lock, "swsysc");
573
574 /*
575 * The nsw_cluster_max is constrained by the bp->b_pages[]
576 * array, which has maxphys / PAGE_SIZE entries, and our locally
577 * defined MAX_PAGEOUT_CLUSTER. Also be aware that swap ops are
578 * constrained by the swap device interleave stripe size.
579 *
580 * Initialized early so that GEOM_ELI can see it.
581 */
582 nsw_cluster_max = min(maxphys / PAGE_SIZE, MAX_PAGEOUT_CLUSTER);
583 }
584
585 /*
586 * SWAP_PAGER_SWAP_INIT() - swap pager initialization from pageout process
587 *
588 * Expected to be started from pageout process once, prior to entering
589 * its main loop.
590 */
591 void
swap_pager_swap_init(void)592 swap_pager_swap_init(void)
593 {
594 unsigned long n, n2;
595
596 /*
597 * Number of in-transit swap bp operations. Don't
598 * exhaust the pbufs completely. Make sure we
599 * initialize workable values (0 will work for hysteresis
600 * but it isn't very efficient).
601 *
602 * Currently we hardwire nsw_wcount_async to 4. This limit is
603 * designed to prevent other I/O from having high latencies due to
604 * our pageout I/O. The value 4 works well for one or two active swap
605 * devices but is probably a little low if you have more. Even so,
606 * a higher value would probably generate only a limited improvement
607 * with three or four active swap devices since the system does not
608 * typically have to pageout at extreme bandwidths. We will want
609 * at least 2 per swap devices, and 4 is a pretty good value if you
610 * have one NFS swap device due to the command/ack latency over NFS.
611 * So it all works out pretty well.
612 *
613 * nsw_cluster_max is initialized in swap_pager_init().
614 */
615
616 nsw_wcount_async = 4;
617 nsw_wcount_async_max = nsw_wcount_async;
618 mtx_init(&swbuf_mtx, "async swbuf mutex", NULL, MTX_DEF);
619
620 swwbuf_zone = pbuf_zsecond_create("swwbuf", nswbuf / 4);
621 swrbuf_zone = pbuf_zsecond_create("swrbuf", nswbuf / 2);
622
623 /*
624 * Initialize our zone, taking the user's requested size or
625 * estimating the number we need based on the number of pages
626 * in the system.
627 */
628 n = maxswzone != 0 ? maxswzone / sizeof(struct swblk) :
629 vm_cnt.v_page_count / 2;
630 swpctrie_zone = uma_zcreate("swpctrie", pctrie_node_size(), NULL, NULL,
631 pctrie_zone_init, NULL, UMA_ALIGN_PTR, 0);
632 swblk_zone = uma_zcreate("swblk", sizeof(struct swblk), NULL, NULL,
633 NULL, NULL, _Alignof(struct swblk) - 1, 0);
634 n2 = n;
635 do {
636 if (uma_zone_reserve_kva(swblk_zone, n))
637 break;
638 /*
639 * if the allocation failed, try a zone two thirds the
640 * size of the previous attempt.
641 */
642 n -= ((n + 2) / 3);
643 } while (n > 0);
644
645 /*
646 * Often uma_zone_reserve_kva() cannot reserve exactly the
647 * requested size. Account for the difference when
648 * calculating swap_maxpages.
649 */
650 n = uma_zone_get_max(swblk_zone);
651
652 if (n < n2)
653 printf("Swap blk zone entries changed from %lu to %lu.\n",
654 n2, n);
655 /* absolute maximum we can handle assuming 100% efficiency */
656 swap_maxpages = n * SWAP_META_PAGES;
657 swzone = n * sizeof(struct swblk);
658 if (!uma_zone_reserve_kva(swpctrie_zone, n))
659 printf("Cannot reserve swap pctrie zone, "
660 "reduce kern.maxswzone.\n");
661 }
662
663 bool
swap_pager_init_object(vm_object_t object,void * handle,struct ucred * cred,vm_ooffset_t size,vm_ooffset_t offset)664 swap_pager_init_object(vm_object_t object, void *handle, struct ucred *cred,
665 vm_ooffset_t size, vm_ooffset_t offset)
666 {
667 if (cred != NULL) {
668 if (!swap_reserve_by_cred(size, cred))
669 return (false);
670 crhold(cred);
671 }
672
673 object->un_pager.swp.writemappings = 0;
674 object->handle = handle;
675 if (cred != NULL) {
676 object->cred = cred;
677 object->charge = size;
678 }
679 return (true);
680 }
681
682 static vm_object_t
swap_pager_alloc_init(objtype_t otype,void * handle,struct ucred * cred,vm_ooffset_t size,vm_ooffset_t offset)683 swap_pager_alloc_init(objtype_t otype, void *handle, struct ucred *cred,
684 vm_ooffset_t size, vm_ooffset_t offset)
685 {
686 vm_object_t object;
687
688 /*
689 * The un_pager.swp.swp_blks trie is initialized by
690 * vm_object_allocate() to ensure the correct order of
691 * visibility to other threads.
692 */
693 object = vm_object_allocate(otype, OFF_TO_IDX(offset +
694 PAGE_MASK + size));
695
696 if (!swap_pager_init_object(object, handle, cred, size, offset)) {
697 vm_object_deallocate(object);
698 return (NULL);
699 }
700 return (object);
701 }
702
703 /*
704 * SWAP_PAGER_ALLOC() - allocate a new OBJT_SWAP VM object and instantiate
705 * its metadata structures.
706 *
707 * This routine is called from the mmap and fork code to create a new
708 * OBJT_SWAP object.
709 *
710 * This routine must ensure that no live duplicate is created for
711 * the named object request, which is protected against by
712 * holding the sw_alloc_sx lock in case handle != NULL.
713 */
714 static vm_object_t
swap_pager_alloc(void * handle,vm_ooffset_t size,vm_prot_t prot,vm_ooffset_t offset,struct ucred * cred)715 swap_pager_alloc(void *handle, vm_ooffset_t size, vm_prot_t prot,
716 vm_ooffset_t offset, struct ucred *cred)
717 {
718 vm_object_t object;
719
720 if (handle != NULL) {
721 /*
722 * Reference existing named region or allocate new one. There
723 * should not be a race here against swp_pager_meta_build()
724 * as called from vm_page_remove() in regards to the lookup
725 * of the handle.
726 */
727 sx_xlock(&sw_alloc_sx);
728 object = vm_pager_object_lookup(NOBJLIST(handle), handle);
729 if (object == NULL) {
730 object = swap_pager_alloc_init(OBJT_SWAP, handle, cred,
731 size, offset);
732 if (object != NULL) {
733 TAILQ_INSERT_TAIL(NOBJLIST(object->handle),
734 object, pager_object_list);
735 }
736 }
737 sx_xunlock(&sw_alloc_sx);
738 } else {
739 object = swap_pager_alloc_init(OBJT_SWAP, handle, cred,
740 size, offset);
741 }
742 return (object);
743 }
744
745 /*
746 * SWAP_PAGER_DEALLOC() - remove swap metadata from object
747 *
748 * The swap backing for the object is destroyed. The code is
749 * designed such that we can reinstantiate it later, but this
750 * routine is typically called only when the entire object is
751 * about to be destroyed.
752 *
753 * The object must be locked.
754 */
755 static void
swap_pager_dealloc(vm_object_t object)756 swap_pager_dealloc(vm_object_t object)
757 {
758
759 VM_OBJECT_ASSERT_WLOCKED(object);
760 KASSERT((object->flags & OBJ_DEAD) != 0, ("dealloc of reachable obj"));
761
762 /*
763 * Remove from list right away so lookups will fail if we block for
764 * pageout completion.
765 */
766 if ((object->flags & OBJ_ANON) == 0 && object->handle != NULL) {
767 VM_OBJECT_WUNLOCK(object);
768 sx_xlock(&sw_alloc_sx);
769 TAILQ_REMOVE(NOBJLIST(object->handle), object,
770 pager_object_list);
771 sx_xunlock(&sw_alloc_sx);
772 VM_OBJECT_WLOCK(object);
773 }
774
775 vm_object_pip_wait(object, "swpdea");
776
777 /*
778 * Free all remaining metadata. We only bother to free it from
779 * the swap meta data. We do not attempt to free swapblk's still
780 * associated with vm_page_t's for this object. We do not care
781 * if paging is still in progress on some objects.
782 */
783 swp_pager_meta_free_all(object);
784 object->handle = NULL;
785 object->type = OBJT_DEAD;
786
787 /*
788 * Release the allocation charge.
789 */
790 if (object->cred != NULL) {
791 swap_release_by_cred(object->charge, object->cred);
792 object->charge = 0;
793 crfree(object->cred);
794 object->cred = NULL;
795 }
796
797 /*
798 * Hide the object from swap_pager_swapoff().
799 */
800 vm_object_clear_flag(object, OBJ_SWAP);
801 }
802
803 /************************************************************************
804 * SWAP PAGER BITMAP ROUTINES *
805 ************************************************************************/
806
807 /*
808 * SWP_PAGER_GETSWAPSPACE() - allocate raw swap space
809 *
810 * Allocate swap for up to the requested number of pages. The
811 * starting swap block number (a page index) is returned or
812 * SWAPBLK_NONE if the allocation failed.
813 *
814 * Also has the side effect of advising that somebody made a mistake
815 * when they configured swap and didn't configure enough.
816 *
817 * This routine may not sleep.
818 *
819 * We allocate in round-robin fashion from the configured devices.
820 */
821 static daddr_t
swp_pager_getswapspace(int * io_npages)822 swp_pager_getswapspace(int *io_npages)
823 {
824 daddr_t blk;
825 struct swdevt *sp;
826 int mpages, npages;
827
828 KASSERT(*io_npages >= 1,
829 ("%s: npages not positive", __func__));
830 blk = SWAPBLK_NONE;
831 mpages = *io_npages;
832 npages = imin(BLIST_MAX_ALLOC, mpages);
833 mtx_lock(&sw_dev_mtx);
834 sp = swdevhd;
835 while (!TAILQ_EMPTY(&swtailq)) {
836 if (sp == NULL)
837 sp = TAILQ_FIRST(&swtailq);
838 if ((sp->sw_flags & SW_CLOSING) == 0)
839 blk = blist_alloc(sp->sw_blist, &npages, mpages);
840 if (blk != SWAPBLK_NONE)
841 break;
842 sp = TAILQ_NEXT(sp, sw_list);
843 if (swdevhd == sp) {
844 if (npages == 1)
845 break;
846 mpages = npages - 1;
847 npages >>= 1;
848 }
849 }
850 if (blk != SWAPBLK_NONE) {
851 *io_npages = npages;
852 blk += sp->sw_first;
853 sp->sw_used += npages;
854 swap_pager_avail -= npages;
855 swp_sizecheck();
856 swdevhd = TAILQ_NEXT(sp, sw_list);
857 } else {
858 if (swap_pager_full != 2) {
859 printf("swp_pager_getswapspace(%d): failed\n",
860 *io_npages);
861 swap_pager_full = 2;
862 swap_pager_almost_full = 1;
863 }
864 swdevhd = NULL;
865 }
866 mtx_unlock(&sw_dev_mtx);
867 return (blk);
868 }
869
870 static bool
swp_pager_isondev(daddr_t blk,struct swdevt * sp)871 swp_pager_isondev(daddr_t blk, struct swdevt *sp)
872 {
873
874 return (blk >= sp->sw_first && blk < sp->sw_end);
875 }
876
877 static void
swp_pager_strategy(struct buf * bp)878 swp_pager_strategy(struct buf *bp)
879 {
880 struct swdevt *sp;
881
882 mtx_lock(&sw_dev_mtx);
883 TAILQ_FOREACH(sp, &swtailq, sw_list) {
884 if (swp_pager_isondev(bp->b_blkno, sp)) {
885 mtx_unlock(&sw_dev_mtx);
886 if ((sp->sw_flags & SW_UNMAPPED) != 0 &&
887 unmapped_buf_allowed) {
888 bp->b_data = unmapped_buf;
889 bp->b_offset = 0;
890 } else {
891 pmap_qenter((vm_offset_t)bp->b_data,
892 &bp->b_pages[0], bp->b_bcount / PAGE_SIZE);
893 }
894 sp->sw_strategy(bp, sp);
895 return;
896 }
897 }
898 panic("Swapdev not found");
899 }
900
901 /*
902 * SWP_PAGER_FREESWAPSPACE() - free raw swap space
903 *
904 * This routine returns the specified swap blocks back to the bitmap.
905 *
906 * This routine may not sleep.
907 */
908 static void
swp_pager_freeswapspace(daddr_t blk,daddr_t npages)909 swp_pager_freeswapspace(daddr_t blk, daddr_t npages)
910 {
911 struct swdevt *sp;
912
913 if (npages == 0)
914 return;
915 mtx_lock(&sw_dev_mtx);
916 TAILQ_FOREACH(sp, &swtailq, sw_list) {
917 if (swp_pager_isondev(blk, sp)) {
918 sp->sw_used -= npages;
919 /*
920 * If we are attempting to stop swapping on
921 * this device, we don't want to mark any
922 * blocks free lest they be reused.
923 */
924 if ((sp->sw_flags & SW_CLOSING) == 0) {
925 blist_free(sp->sw_blist, blk - sp->sw_first,
926 npages);
927 swap_pager_avail += npages;
928 swp_sizecheck();
929 }
930 mtx_unlock(&sw_dev_mtx);
931 return;
932 }
933 }
934 panic("Swapdev not found");
935 }
936
937 /*
938 * SYSCTL_SWAP_FRAGMENTATION() - produce raw swap space stats
939 */
940 static int
sysctl_swap_fragmentation(SYSCTL_HANDLER_ARGS)941 sysctl_swap_fragmentation(SYSCTL_HANDLER_ARGS)
942 {
943 struct sbuf sbuf;
944 struct swdevt *sp;
945 const char *devname;
946 int error;
947
948 error = sysctl_wire_old_buffer(req, 0);
949 if (error != 0)
950 return (error);
951 sbuf_new_for_sysctl(&sbuf, NULL, 128, req);
952 mtx_lock(&sw_dev_mtx);
953 TAILQ_FOREACH(sp, &swtailq, sw_list) {
954 if (vn_isdisk(sp->sw_vp))
955 devname = devtoname(sp->sw_vp->v_rdev);
956 else
957 devname = "[file]";
958 sbuf_printf(&sbuf, "\nFree space on device %s:\n", devname);
959 blist_stats(sp->sw_blist, &sbuf);
960 }
961 mtx_unlock(&sw_dev_mtx);
962 error = sbuf_finish(&sbuf);
963 sbuf_delete(&sbuf);
964 return (error);
965 }
966
967 /*
968 * SWAP_PAGER_FREESPACE() - frees swap blocks associated with a page
969 * range within an object.
970 *
971 * This routine removes swapblk assignments from swap metadata.
972 *
973 * The external callers of this routine typically have already destroyed
974 * or renamed vm_page_t's associated with this range in the object so
975 * we should be ok.
976 *
977 * The object must be locked.
978 */
979 void
swap_pager_freespace(vm_object_t object,vm_pindex_t start,vm_size_t size,vm_size_t * freed)980 swap_pager_freespace(vm_object_t object, vm_pindex_t start, vm_size_t size,
981 vm_size_t *freed)
982 {
983 MPASS((object->flags & OBJ_SWAP) != 0);
984
985 swp_pager_meta_free(object, start, size, freed);
986 }
987
988 static void
swap_pager_freespace_pgo(vm_object_t object,vm_pindex_t start,vm_size_t size)989 swap_pager_freespace_pgo(vm_object_t object, vm_pindex_t start, vm_size_t size)
990 {
991 MPASS((object->flags & OBJ_SWAP) != 0);
992
993 swp_pager_meta_free(object, start, size, NULL);
994 }
995
996 /*
997 * SWAP_PAGER_RESERVE() - reserve swap blocks in object
998 *
999 * Assigns swap blocks to the specified range within the object. The
1000 * swap blocks are not zeroed. Any previous swap assignment is destroyed.
1001 *
1002 * Returns 0 on success, -1 on failure.
1003 */
1004 int
swap_pager_reserve(vm_object_t object,vm_pindex_t start,vm_pindex_t size)1005 swap_pager_reserve(vm_object_t object, vm_pindex_t start, vm_pindex_t size)
1006 {
1007 daddr_t addr, blk, n_free, s_free;
1008 vm_pindex_t i, j;
1009 int n;
1010
1011 swp_pager_init_freerange(&s_free, &n_free);
1012 VM_OBJECT_WLOCK(object);
1013 for (i = 0; i < size; i += n) {
1014 n = MIN(size - i, INT_MAX);
1015 blk = swp_pager_getswapspace(&n);
1016 if (blk == SWAPBLK_NONE) {
1017 swp_pager_meta_free(object, start, i, NULL);
1018 VM_OBJECT_WUNLOCK(object);
1019 return (-1);
1020 }
1021 for (j = 0; j < n; ++j) {
1022 addr = swp_pager_meta_build(object,
1023 start + i + j, blk + j);
1024 if (addr != SWAPBLK_NONE)
1025 swp_pager_update_freerange(&s_free, &n_free,
1026 addr);
1027 }
1028 }
1029 swp_pager_freeswapspace(s_free, n_free);
1030 VM_OBJECT_WUNLOCK(object);
1031 return (0);
1032 }
1033
1034 static bool
swp_pager_xfer_source(vm_object_t srcobject,vm_object_t dstobject,vm_pindex_t pindex,daddr_t addr)1035 swp_pager_xfer_source(vm_object_t srcobject, vm_object_t dstobject,
1036 vm_pindex_t pindex, daddr_t addr)
1037 {
1038 daddr_t dstaddr __diagused;
1039
1040 KASSERT((srcobject->flags & OBJ_SWAP) != 0,
1041 ("%s: srcobject not swappable", __func__));
1042 KASSERT((dstobject->flags & OBJ_SWAP) != 0,
1043 ("%s: dstobject not swappable", __func__));
1044
1045 if (swp_pager_meta_lookup(dstobject, pindex) != SWAPBLK_NONE) {
1046 /* Caller should destroy the source block. */
1047 return (false);
1048 }
1049
1050 /*
1051 * Destination has no swapblk and is not resident, transfer source.
1052 * swp_pager_meta_build() can sleep.
1053 */
1054 VM_OBJECT_WUNLOCK(srcobject);
1055 dstaddr = swp_pager_meta_build(dstobject, pindex, addr);
1056 KASSERT(dstaddr == SWAPBLK_NONE,
1057 ("Unexpected destination swapblk"));
1058 VM_OBJECT_WLOCK(srcobject);
1059
1060 return (true);
1061 }
1062
1063 /*
1064 * SWAP_PAGER_COPY() - copy blocks from source pager to destination pager
1065 * and destroy the source.
1066 *
1067 * Copy any valid swapblks from the source to the destination. In
1068 * cases where both the source and destination have a valid swapblk,
1069 * we keep the destination's.
1070 *
1071 * This routine is allowed to sleep. It may sleep allocating metadata
1072 * indirectly through swp_pager_meta_build().
1073 *
1074 * The source object contains no vm_page_t's (which is just as well)
1075 *
1076 * The source and destination objects must be locked.
1077 * Both object locks may temporarily be released.
1078 */
1079 void
swap_pager_copy(vm_object_t srcobject,vm_object_t dstobject,vm_pindex_t offset,int destroysource)1080 swap_pager_copy(vm_object_t srcobject, vm_object_t dstobject,
1081 vm_pindex_t offset, int destroysource)
1082 {
1083 VM_OBJECT_ASSERT_WLOCKED(srcobject);
1084 VM_OBJECT_ASSERT_WLOCKED(dstobject);
1085
1086 /*
1087 * If destroysource is set, we remove the source object from the
1088 * swap_pager internal queue now.
1089 */
1090 if (destroysource && (srcobject->flags & OBJ_ANON) == 0 &&
1091 srcobject->handle != NULL) {
1092 VM_OBJECT_WUNLOCK(srcobject);
1093 VM_OBJECT_WUNLOCK(dstobject);
1094 sx_xlock(&sw_alloc_sx);
1095 TAILQ_REMOVE(NOBJLIST(srcobject->handle), srcobject,
1096 pager_object_list);
1097 sx_xunlock(&sw_alloc_sx);
1098 VM_OBJECT_WLOCK(dstobject);
1099 VM_OBJECT_WLOCK(srcobject);
1100 }
1101
1102 /*
1103 * Transfer source to destination.
1104 */
1105 swp_pager_meta_transfer(srcobject, dstobject, offset, dstobject->size,
1106 NULL);
1107
1108 /*
1109 * Free left over swap blocks in source.
1110 */
1111 if (destroysource)
1112 swp_pager_meta_free_all(srcobject);
1113 }
1114
1115 /*
1116 * SWAP_PAGER_HASPAGE() - determine if we have good backing store for
1117 * the requested page.
1118 *
1119 * We determine whether good backing store exists for the requested
1120 * page and return TRUE if it does, FALSE if it doesn't.
1121 *
1122 * If TRUE, we also try to determine how much valid, contiguous backing
1123 * store exists before and after the requested page.
1124 */
1125 static boolean_t
swap_pager_haspage(vm_object_t object,vm_pindex_t pindex,int * before,int * after)1126 swap_pager_haspage(vm_object_t object, vm_pindex_t pindex, int *before,
1127 int *after)
1128 {
1129 daddr_t blk, blk0;
1130 int i;
1131
1132 VM_OBJECT_ASSERT_LOCKED(object);
1133 KASSERT((object->flags & OBJ_SWAP) != 0,
1134 ("%s: object not swappable", __func__));
1135
1136 /*
1137 * do we have good backing store at the requested index ?
1138 */
1139 blk0 = swp_pager_meta_lookup(object, pindex);
1140 if (blk0 == SWAPBLK_NONE) {
1141 if (before)
1142 *before = 0;
1143 if (after)
1144 *after = 0;
1145 return (FALSE);
1146 }
1147
1148 /*
1149 * find backwards-looking contiguous good backing store
1150 */
1151 if (before != NULL) {
1152 for (i = 1; i < SWB_NPAGES; i++) {
1153 if (i > pindex)
1154 break;
1155 blk = swp_pager_meta_lookup(object, pindex - i);
1156 if (blk != blk0 - i)
1157 break;
1158 }
1159 *before = i - 1;
1160 }
1161
1162 /*
1163 * find forward-looking contiguous good backing store
1164 */
1165 if (after != NULL) {
1166 for (i = 1; i < SWB_NPAGES; i++) {
1167 blk = swp_pager_meta_lookup(object, pindex + i);
1168 if (blk != blk0 + i)
1169 break;
1170 }
1171 *after = i - 1;
1172 }
1173 return (TRUE);
1174 }
1175
1176 /*
1177 * SWAP_PAGER_PAGE_UNSWAPPED() - remove swap backing store related to page
1178 *
1179 * This removes any associated swap backing store, whether valid or
1180 * not, from the page.
1181 *
1182 * This routine is typically called when a page is made dirty, at
1183 * which point any associated swap can be freed. MADV_FREE also
1184 * calls us in a special-case situation
1185 *
1186 * NOTE!!! If the page is clean and the swap was valid, the caller
1187 * should make the page dirty before calling this routine. This routine
1188 * does NOT change the m->dirty status of the page. Also: MADV_FREE
1189 * depends on it.
1190 *
1191 * This routine may not sleep.
1192 *
1193 * The object containing the page may be locked.
1194 */
1195 static void
swap_pager_unswapped(vm_page_t m)1196 swap_pager_unswapped(vm_page_t m)
1197 {
1198 struct swblk *sb;
1199 vm_object_t obj;
1200
1201 /*
1202 * Handle enqueing deferred frees first. If we do not have the
1203 * object lock we wait for the page daemon to clear the space.
1204 */
1205 obj = m->object;
1206 if (!VM_OBJECT_WOWNED(obj)) {
1207 VM_PAGE_OBJECT_BUSY_ASSERT(m);
1208 /*
1209 * The caller is responsible for synchronization but we
1210 * will harmlessly handle races. This is typically provided
1211 * by only calling unswapped() when a page transitions from
1212 * clean to dirty.
1213 */
1214 if ((m->a.flags & (PGA_SWAP_SPACE | PGA_SWAP_FREE)) ==
1215 PGA_SWAP_SPACE) {
1216 vm_page_aflag_set(m, PGA_SWAP_FREE);
1217 counter_u64_add(swap_free_deferred, 1);
1218 }
1219 return;
1220 }
1221 if ((m->a.flags & PGA_SWAP_FREE) != 0)
1222 counter_u64_add(swap_free_completed, 1);
1223 vm_page_aflag_clear(m, PGA_SWAP_FREE | PGA_SWAP_SPACE);
1224
1225 /*
1226 * The meta data only exists if the object is OBJT_SWAP
1227 * and even then might not be allocated yet.
1228 */
1229 KASSERT((m->object->flags & OBJ_SWAP) != 0,
1230 ("Free object not swappable"));
1231
1232 sb = SWAP_PCTRIE_LOOKUP(&m->object->un_pager.swp.swp_blks,
1233 rounddown(m->pindex, SWAP_META_PAGES));
1234 if (sb == NULL)
1235 return;
1236 if (sb->d[m->pindex % SWAP_META_PAGES] == SWAPBLK_NONE)
1237 return;
1238 swp_pager_freeswapspace(sb->d[m->pindex % SWAP_META_PAGES], 1);
1239 sb->d[m->pindex % SWAP_META_PAGES] = SWAPBLK_NONE;
1240 swp_pager_free_empty_swblk(m->object, sb);
1241 }
1242
1243 /*
1244 * swap_pager_getpages() - bring pages in from swap
1245 *
1246 * Attempt to page in the pages in array "ma" of length "count". The
1247 * caller may optionally specify that additional pages preceding and
1248 * succeeding the specified range be paged in. The number of such pages
1249 * is returned in the "rbehind" and "rahead" parameters, and they will
1250 * be in the inactive queue upon return.
1251 *
1252 * The pages in "ma" must be busied and will remain busied upon return.
1253 */
1254 static int
swap_pager_getpages_locked(vm_object_t object,vm_page_t * ma,int count,int * rbehind,int * rahead)1255 swap_pager_getpages_locked(vm_object_t object, vm_page_t *ma, int count,
1256 int *rbehind, int *rahead)
1257 {
1258 struct buf *bp;
1259 vm_page_t bm, mpred, msucc, p;
1260 vm_pindex_t pindex;
1261 daddr_t blk;
1262 int i, maxahead, maxbehind, reqcount;
1263
1264 VM_OBJECT_ASSERT_WLOCKED(object);
1265 reqcount = count;
1266
1267 KASSERT((object->flags & OBJ_SWAP) != 0,
1268 ("%s: object not swappable", __func__));
1269 if (!swap_pager_haspage(object, ma[0]->pindex, &maxbehind, &maxahead)) {
1270 VM_OBJECT_WUNLOCK(object);
1271 return (VM_PAGER_FAIL);
1272 }
1273
1274 KASSERT(reqcount - 1 <= maxahead,
1275 ("page count %d extends beyond swap block", reqcount));
1276
1277 /*
1278 * Do not transfer any pages other than those that are xbusied
1279 * when running during a split or collapse operation. This
1280 * prevents clustering from re-creating pages which are being
1281 * moved into another object.
1282 */
1283 if ((object->flags & (OBJ_SPLIT | OBJ_DEAD)) != 0) {
1284 maxahead = reqcount - 1;
1285 maxbehind = 0;
1286 }
1287
1288 /*
1289 * Clip the readahead and readbehind ranges to exclude resident pages.
1290 */
1291 if (rahead != NULL) {
1292 *rahead = imin(*rahead, maxahead - (reqcount - 1));
1293 pindex = ma[reqcount - 1]->pindex;
1294 msucc = TAILQ_NEXT(ma[reqcount - 1], listq);
1295 if (msucc != NULL && msucc->pindex - pindex - 1 < *rahead)
1296 *rahead = msucc->pindex - pindex - 1;
1297 }
1298 if (rbehind != NULL) {
1299 *rbehind = imin(*rbehind, maxbehind);
1300 pindex = ma[0]->pindex;
1301 mpred = TAILQ_PREV(ma[0], pglist, listq);
1302 if (mpred != NULL && pindex - mpred->pindex - 1 < *rbehind)
1303 *rbehind = pindex - mpred->pindex - 1;
1304 }
1305
1306 bm = ma[0];
1307 for (i = 0; i < count; i++)
1308 ma[i]->oflags |= VPO_SWAPINPROG;
1309
1310 /*
1311 * Allocate readahead and readbehind pages.
1312 */
1313 if (rbehind != NULL) {
1314 for (i = 1; i <= *rbehind; i++) {
1315 p = vm_page_alloc(object, ma[0]->pindex - i,
1316 VM_ALLOC_NORMAL);
1317 if (p == NULL)
1318 break;
1319 p->oflags |= VPO_SWAPINPROG;
1320 bm = p;
1321 }
1322 *rbehind = i - 1;
1323 }
1324 if (rahead != NULL) {
1325 for (i = 0; i < *rahead; i++) {
1326 p = vm_page_alloc(object,
1327 ma[reqcount - 1]->pindex + i + 1, VM_ALLOC_NORMAL);
1328 if (p == NULL)
1329 break;
1330 p->oflags |= VPO_SWAPINPROG;
1331 }
1332 *rahead = i;
1333 }
1334 if (rbehind != NULL)
1335 count += *rbehind;
1336 if (rahead != NULL)
1337 count += *rahead;
1338
1339 vm_object_pip_add(object, count);
1340
1341 pindex = bm->pindex;
1342 blk = swp_pager_meta_lookup(object, pindex);
1343 KASSERT(blk != SWAPBLK_NONE,
1344 ("no swap blocking containing %p(%jx)", object, (uintmax_t)pindex));
1345
1346 VM_OBJECT_WUNLOCK(object);
1347 bp = uma_zalloc(swrbuf_zone, M_WAITOK);
1348 MPASS((bp->b_flags & B_MAXPHYS) != 0);
1349 /* Pages cannot leave the object while busy. */
1350 for (i = 0, p = bm; i < count; i++, p = TAILQ_NEXT(p, listq)) {
1351 MPASS(p->pindex == bm->pindex + i);
1352 bp->b_pages[i] = p;
1353 }
1354
1355 bp->b_flags |= B_PAGING;
1356 bp->b_iocmd = BIO_READ;
1357 bp->b_iodone = swp_pager_async_iodone;
1358 bp->b_rcred = crhold(thread0.td_ucred);
1359 bp->b_wcred = crhold(thread0.td_ucred);
1360 bp->b_blkno = blk;
1361 bp->b_bcount = PAGE_SIZE * count;
1362 bp->b_bufsize = PAGE_SIZE * count;
1363 bp->b_npages = count;
1364 bp->b_pgbefore = rbehind != NULL ? *rbehind : 0;
1365 bp->b_pgafter = rahead != NULL ? *rahead : 0;
1366
1367 VM_CNT_INC(v_swapin);
1368 VM_CNT_ADD(v_swappgsin, count);
1369
1370 /*
1371 * perform the I/O. NOTE!!! bp cannot be considered valid after
1372 * this point because we automatically release it on completion.
1373 * Instead, we look at the one page we are interested in which we
1374 * still hold a lock on even through the I/O completion.
1375 *
1376 * The other pages in our ma[] array are also released on completion,
1377 * so we cannot assume they are valid anymore either.
1378 *
1379 * NOTE: b_blkno is destroyed by the call to swapdev_strategy
1380 */
1381 BUF_KERNPROC(bp);
1382 swp_pager_strategy(bp);
1383
1384 /*
1385 * Wait for the pages we want to complete. VPO_SWAPINPROG is always
1386 * cleared on completion. If an I/O error occurs, SWAPBLK_NONE
1387 * is set in the metadata for each page in the request.
1388 */
1389 VM_OBJECT_WLOCK(object);
1390 /* This could be implemented more efficiently with aflags */
1391 while ((ma[0]->oflags & VPO_SWAPINPROG) != 0) {
1392 ma[0]->oflags |= VPO_SWAPSLEEP;
1393 VM_CNT_INC(v_intrans);
1394 if (VM_OBJECT_SLEEP(object, &object->handle, PSWP,
1395 "swread", hz * 20)) {
1396 printf(
1397 "swap_pager: indefinite wait buffer: bufobj: %p, blkno: %jd, size: %ld\n",
1398 bp->b_bufobj, (intmax_t)bp->b_blkno, bp->b_bcount);
1399 }
1400 }
1401 VM_OBJECT_WUNLOCK(object);
1402
1403 /*
1404 * If we had an unrecoverable read error pages will not be valid.
1405 */
1406 for (i = 0; i < reqcount; i++)
1407 if (ma[i]->valid != VM_PAGE_BITS_ALL)
1408 return (VM_PAGER_ERROR);
1409
1410 return (VM_PAGER_OK);
1411
1412 /*
1413 * A final note: in a low swap situation, we cannot deallocate swap
1414 * and mark a page dirty here because the caller is likely to mark
1415 * the page clean when we return, causing the page to possibly revert
1416 * to all-zero's later.
1417 */
1418 }
1419
1420 static int
swap_pager_getpages(vm_object_t object,vm_page_t * ma,int count,int * rbehind,int * rahead)1421 swap_pager_getpages(vm_object_t object, vm_page_t *ma, int count,
1422 int *rbehind, int *rahead)
1423 {
1424
1425 VM_OBJECT_WLOCK(object);
1426 return (swap_pager_getpages_locked(object, ma, count, rbehind, rahead));
1427 }
1428
1429 /*
1430 * swap_pager_getpages_async():
1431 *
1432 * Right now this is emulation of asynchronous operation on top of
1433 * swap_pager_getpages().
1434 */
1435 static int
swap_pager_getpages_async(vm_object_t object,vm_page_t * ma,int count,int * rbehind,int * rahead,pgo_getpages_iodone_t iodone,void * arg)1436 swap_pager_getpages_async(vm_object_t object, vm_page_t *ma, int count,
1437 int *rbehind, int *rahead, pgo_getpages_iodone_t iodone, void *arg)
1438 {
1439 int r, error;
1440
1441 r = swap_pager_getpages(object, ma, count, rbehind, rahead);
1442 switch (r) {
1443 case VM_PAGER_OK:
1444 error = 0;
1445 break;
1446 case VM_PAGER_ERROR:
1447 error = EIO;
1448 break;
1449 case VM_PAGER_FAIL:
1450 error = EINVAL;
1451 break;
1452 default:
1453 panic("unhandled swap_pager_getpages() error %d", r);
1454 }
1455 (iodone)(arg, ma, count, error);
1456
1457 return (r);
1458 }
1459
1460 /*
1461 * swap_pager_putpages:
1462 *
1463 * Assign swap (if necessary) and initiate I/O on the specified pages.
1464 *
1465 * In a low memory situation we may block in VOP_STRATEGY(), but the new
1466 * vm_page reservation system coupled with properly written VFS devices
1467 * should ensure that no low-memory deadlock occurs. This is an area
1468 * which needs work.
1469 *
1470 * The parent has N vm_object_pip_add() references prior to
1471 * calling us and will remove references for rtvals[] that are
1472 * not set to VM_PAGER_PEND. We need to remove the rest on I/O
1473 * completion.
1474 *
1475 * The parent has soft-busy'd the pages it passes us and will unbusy
1476 * those whose rtvals[] entry is not set to VM_PAGER_PEND on return.
1477 * We need to unbusy the rest on I/O completion.
1478 */
1479 static void
swap_pager_putpages(vm_object_t object,vm_page_t * ma,int count,int flags,int * rtvals)1480 swap_pager_putpages(vm_object_t object, vm_page_t *ma, int count,
1481 int flags, int *rtvals)
1482 {
1483 struct buf *bp;
1484 daddr_t addr, blk, n_free, s_free;
1485 vm_page_t mreq;
1486 int i, j, n;
1487 bool async;
1488
1489 KASSERT(count == 0 || ma[0]->object == object,
1490 ("%s: object mismatch %p/%p",
1491 __func__, object, ma[0]->object));
1492
1493 VM_OBJECT_WUNLOCK(object);
1494 async = curproc == pageproc && (flags & VM_PAGER_PUT_SYNC) == 0;
1495 swp_pager_init_freerange(&s_free, &n_free);
1496
1497 /*
1498 * Assign swap blocks and issue I/O. We reallocate swap on the fly.
1499 * The page is left dirty until the pageout operation completes
1500 * successfully.
1501 */
1502 for (i = 0; i < count; i += n) {
1503 /* Maximum I/O size is limited by maximum swap block size. */
1504 n = min(count - i, nsw_cluster_max);
1505
1506 if (async) {
1507 mtx_lock(&swbuf_mtx);
1508 while (nsw_wcount_async == 0)
1509 msleep(&nsw_wcount_async, &swbuf_mtx, PVM,
1510 "swbufa", 0);
1511 nsw_wcount_async--;
1512 mtx_unlock(&swbuf_mtx);
1513 }
1514
1515 /* Get a block of swap of size up to size n. */
1516 blk = swp_pager_getswapspace(&n);
1517 if (blk == SWAPBLK_NONE) {
1518 mtx_lock(&swbuf_mtx);
1519 if (++nsw_wcount_async == 1)
1520 wakeup(&nsw_wcount_async);
1521 mtx_unlock(&swbuf_mtx);
1522 for (j = 0; j < n; ++j)
1523 rtvals[i + j] = VM_PAGER_FAIL;
1524 continue;
1525 }
1526 VM_OBJECT_WLOCK(object);
1527 for (j = 0; j < n; ++j) {
1528 mreq = ma[i + j];
1529 vm_page_aflag_clear(mreq, PGA_SWAP_FREE);
1530 addr = swp_pager_meta_build(mreq->object, mreq->pindex,
1531 blk + j);
1532 if (addr != SWAPBLK_NONE)
1533 swp_pager_update_freerange(&s_free, &n_free,
1534 addr);
1535 MPASS(mreq->dirty == VM_PAGE_BITS_ALL);
1536 mreq->oflags |= VPO_SWAPINPROG;
1537 }
1538 VM_OBJECT_WUNLOCK(object);
1539
1540 bp = uma_zalloc(swwbuf_zone, M_WAITOK);
1541 MPASS((bp->b_flags & B_MAXPHYS) != 0);
1542 if (async)
1543 bp->b_flags |= B_ASYNC;
1544 bp->b_flags |= B_PAGING;
1545 bp->b_iocmd = BIO_WRITE;
1546
1547 bp->b_rcred = crhold(thread0.td_ucred);
1548 bp->b_wcred = crhold(thread0.td_ucred);
1549 bp->b_bcount = PAGE_SIZE * n;
1550 bp->b_bufsize = PAGE_SIZE * n;
1551 bp->b_blkno = blk;
1552 for (j = 0; j < n; j++)
1553 bp->b_pages[j] = ma[i + j];
1554 bp->b_npages = n;
1555
1556 /*
1557 * Must set dirty range for NFS to work.
1558 */
1559 bp->b_dirtyoff = 0;
1560 bp->b_dirtyend = bp->b_bcount;
1561
1562 VM_CNT_INC(v_swapout);
1563 VM_CNT_ADD(v_swappgsout, bp->b_npages);
1564
1565 /*
1566 * We unconditionally set rtvals[] to VM_PAGER_PEND so that we
1567 * can call the async completion routine at the end of a
1568 * synchronous I/O operation. Otherwise, our caller would
1569 * perform duplicate unbusy and wakeup operations on the page
1570 * and object, respectively.
1571 */
1572 for (j = 0; j < n; j++)
1573 rtvals[i + j] = VM_PAGER_PEND;
1574
1575 /*
1576 * asynchronous
1577 *
1578 * NOTE: b_blkno is destroyed by the call to swapdev_strategy.
1579 */
1580 if (async) {
1581 bp->b_iodone = swp_pager_async_iodone;
1582 BUF_KERNPROC(bp);
1583 swp_pager_strategy(bp);
1584 continue;
1585 }
1586
1587 /*
1588 * synchronous
1589 *
1590 * NOTE: b_blkno is destroyed by the call to swapdev_strategy.
1591 */
1592 bp->b_iodone = bdone;
1593 swp_pager_strategy(bp);
1594
1595 /*
1596 * Wait for the sync I/O to complete.
1597 */
1598 bwait(bp, PVM, "swwrt");
1599
1600 /*
1601 * Now that we are through with the bp, we can call the
1602 * normal async completion, which frees everything up.
1603 */
1604 swp_pager_async_iodone(bp);
1605 }
1606 swp_pager_freeswapspace(s_free, n_free);
1607 VM_OBJECT_WLOCK(object);
1608 }
1609
1610 /*
1611 * swp_pager_async_iodone:
1612 *
1613 * Completion routine for asynchronous reads and writes from/to swap.
1614 * Also called manually by synchronous code to finish up a bp.
1615 *
1616 * This routine may not sleep.
1617 */
1618 static void
swp_pager_async_iodone(struct buf * bp)1619 swp_pager_async_iodone(struct buf *bp)
1620 {
1621 int i;
1622 vm_object_t object = NULL;
1623
1624 /*
1625 * Report error - unless we ran out of memory, in which case
1626 * we've already logged it in swapgeom_strategy().
1627 */
1628 if (bp->b_ioflags & BIO_ERROR && bp->b_error != ENOMEM) {
1629 printf(
1630 "swap_pager: I/O error - %s failed; blkno %ld,"
1631 "size %ld, error %d\n",
1632 ((bp->b_iocmd == BIO_READ) ? "pagein" : "pageout"),
1633 (long)bp->b_blkno,
1634 (long)bp->b_bcount,
1635 bp->b_error
1636 );
1637 }
1638
1639 /*
1640 * remove the mapping for kernel virtual
1641 */
1642 if (buf_mapped(bp))
1643 pmap_qremove((vm_offset_t)bp->b_data, bp->b_npages);
1644 else
1645 bp->b_data = bp->b_kvabase;
1646
1647 if (bp->b_npages) {
1648 object = bp->b_pages[0]->object;
1649 VM_OBJECT_WLOCK(object);
1650 }
1651
1652 /*
1653 * cleanup pages. If an error occurs writing to swap, we are in
1654 * very serious trouble. If it happens to be a disk error, though,
1655 * we may be able to recover by reassigning the swap later on. So
1656 * in this case we remove the m->swapblk assignment for the page
1657 * but do not free it in the rlist. The errornous block(s) are thus
1658 * never reallocated as swap. Redirty the page and continue.
1659 */
1660 for (i = 0; i < bp->b_npages; ++i) {
1661 vm_page_t m = bp->b_pages[i];
1662
1663 m->oflags &= ~VPO_SWAPINPROG;
1664 if (m->oflags & VPO_SWAPSLEEP) {
1665 m->oflags &= ~VPO_SWAPSLEEP;
1666 wakeup(&object->handle);
1667 }
1668
1669 /* We always have space after I/O, successful or not. */
1670 vm_page_aflag_set(m, PGA_SWAP_SPACE);
1671
1672 if (bp->b_ioflags & BIO_ERROR) {
1673 /*
1674 * If an error occurs I'd love to throw the swapblk
1675 * away without freeing it back to swapspace, so it
1676 * can never be used again. But I can't from an
1677 * interrupt.
1678 */
1679 if (bp->b_iocmd == BIO_READ) {
1680 /*
1681 * NOTE: for reads, m->dirty will probably
1682 * be overridden by the original caller of
1683 * getpages so don't play cute tricks here.
1684 */
1685 vm_page_invalid(m);
1686 if (i < bp->b_pgbefore ||
1687 i >= bp->b_npages - bp->b_pgafter)
1688 vm_page_free_invalid(m);
1689 } else {
1690 /*
1691 * If a write error occurs, reactivate page
1692 * so it doesn't clog the inactive list,
1693 * then finish the I/O.
1694 */
1695 MPASS(m->dirty == VM_PAGE_BITS_ALL);
1696
1697 /* PQ_UNSWAPPABLE? */
1698 vm_page_activate(m);
1699 vm_page_sunbusy(m);
1700 }
1701 } else if (bp->b_iocmd == BIO_READ) {
1702 /*
1703 * NOTE: for reads, m->dirty will probably be
1704 * overridden by the original caller of getpages so
1705 * we cannot set them in order to free the underlying
1706 * swap in a low-swap situation. I don't think we'd
1707 * want to do that anyway, but it was an optimization
1708 * that existed in the old swapper for a time before
1709 * it got ripped out due to precisely this problem.
1710 */
1711 KASSERT(!pmap_page_is_mapped(m),
1712 ("swp_pager_async_iodone: page %p is mapped", m));
1713 KASSERT(m->dirty == 0,
1714 ("swp_pager_async_iodone: page %p is dirty", m));
1715
1716 vm_page_valid(m);
1717 if (i < bp->b_pgbefore ||
1718 i >= bp->b_npages - bp->b_pgafter)
1719 vm_page_readahead_finish(m);
1720 } else {
1721 /*
1722 * For write success, clear the dirty
1723 * status, then finish the I/O ( which decrements the
1724 * busy count and possibly wakes waiter's up ).
1725 * A page is only written to swap after a period of
1726 * inactivity. Therefore, we do not expect it to be
1727 * reused.
1728 */
1729 KASSERT(!pmap_page_is_write_mapped(m),
1730 ("swp_pager_async_iodone: page %p is not write"
1731 " protected", m));
1732 vm_page_undirty(m);
1733 vm_page_deactivate_noreuse(m);
1734 vm_page_sunbusy(m);
1735 }
1736 }
1737
1738 /*
1739 * adjust pip. NOTE: the original parent may still have its own
1740 * pip refs on the object.
1741 */
1742 if (object != NULL) {
1743 vm_object_pip_wakeupn(object, bp->b_npages);
1744 VM_OBJECT_WUNLOCK(object);
1745 }
1746
1747 /*
1748 * swapdev_strategy() manually sets b_vp and b_bufobj before calling
1749 * bstrategy(). Set them back to NULL now we're done with it, or we'll
1750 * trigger a KASSERT in relpbuf().
1751 */
1752 if (bp->b_vp) {
1753 bp->b_vp = NULL;
1754 bp->b_bufobj = NULL;
1755 }
1756 /*
1757 * release the physical I/O buffer
1758 */
1759 if (bp->b_flags & B_ASYNC) {
1760 mtx_lock(&swbuf_mtx);
1761 if (++nsw_wcount_async == 1)
1762 wakeup(&nsw_wcount_async);
1763 mtx_unlock(&swbuf_mtx);
1764 }
1765 uma_zfree((bp->b_iocmd == BIO_READ) ? swrbuf_zone : swwbuf_zone, bp);
1766 }
1767
1768 int
swap_pager_nswapdev(void)1769 swap_pager_nswapdev(void)
1770 {
1771
1772 return (nswapdev);
1773 }
1774
1775 static void
swp_pager_force_dirty(vm_page_t m)1776 swp_pager_force_dirty(vm_page_t m)
1777 {
1778
1779 vm_page_dirty(m);
1780 swap_pager_unswapped(m);
1781 vm_page_launder(m);
1782 }
1783
1784 u_long
swap_pager_swapped_pages(vm_object_t object)1785 swap_pager_swapped_pages(vm_object_t object)
1786 {
1787 struct swblk *sb;
1788 vm_pindex_t pi;
1789 u_long res;
1790 int i;
1791
1792 VM_OBJECT_ASSERT_LOCKED(object);
1793
1794 if (pctrie_is_empty(&object->un_pager.swp.swp_blks))
1795 return (0);
1796
1797 for (res = 0, pi = 0; (sb = SWAP_PCTRIE_LOOKUP_GE(
1798 &object->un_pager.swp.swp_blks, pi)) != NULL;
1799 pi = sb->p + SWAP_META_PAGES) {
1800 for (i = 0; i < SWAP_META_PAGES; i++) {
1801 if (sb->d[i] != SWAPBLK_NONE)
1802 res++;
1803 }
1804 }
1805 return (res);
1806 }
1807
1808 /*
1809 * swap_pager_swapoff_object:
1810 *
1811 * Page in all of the pages that have been paged out for an object
1812 * to a swap device.
1813 */
1814 static void
swap_pager_swapoff_object(struct swdevt * sp,vm_object_t object)1815 swap_pager_swapoff_object(struct swdevt *sp, vm_object_t object)
1816 {
1817 struct swblk *sb;
1818 vm_page_t m;
1819 vm_pindex_t pi;
1820 daddr_t blk;
1821 int i, nv, rahead, rv;
1822
1823 KASSERT((object->flags & OBJ_SWAP) != 0,
1824 ("%s: Object not swappable", __func__));
1825
1826 for (pi = 0; (sb = SWAP_PCTRIE_LOOKUP_GE(
1827 &object->un_pager.swp.swp_blks, pi)) != NULL; ) {
1828 if ((object->flags & OBJ_DEAD) != 0) {
1829 /*
1830 * Make sure that pending writes finish before
1831 * returning.
1832 */
1833 vm_object_pip_wait(object, "swpoff");
1834 swp_pager_meta_free_all(object);
1835 break;
1836 }
1837 for (i = 0; i < SWAP_META_PAGES; i++) {
1838 /*
1839 * Count the number of contiguous valid blocks.
1840 */
1841 for (nv = 0; nv < SWAP_META_PAGES - i; nv++) {
1842 blk = sb->d[i + nv];
1843 if (!swp_pager_isondev(blk, sp) ||
1844 blk == SWAPBLK_NONE)
1845 break;
1846 }
1847 if (nv == 0)
1848 continue;
1849
1850 /*
1851 * Look for a page corresponding to the first
1852 * valid block and ensure that any pending paging
1853 * operations on it are complete. If the page is valid,
1854 * mark it dirty and free the swap block. Try to batch
1855 * this operation since it may cause sp to be freed,
1856 * meaning that we must restart the scan. Avoid busying
1857 * valid pages since we may block forever on kernel
1858 * stack pages.
1859 */
1860 m = vm_page_lookup(object, sb->p + i);
1861 if (m == NULL) {
1862 m = vm_page_alloc(object, sb->p + i,
1863 VM_ALLOC_NORMAL | VM_ALLOC_WAITFAIL);
1864 if (m == NULL)
1865 break;
1866 } else {
1867 if ((m->oflags & VPO_SWAPINPROG) != 0) {
1868 m->oflags |= VPO_SWAPSLEEP;
1869 VM_OBJECT_SLEEP(object, &object->handle,
1870 PSWP, "swpoff", 0);
1871 break;
1872 }
1873 if (vm_page_all_valid(m)) {
1874 do {
1875 swp_pager_force_dirty(m);
1876 } while (--nv > 0 &&
1877 (m = vm_page_next(m)) != NULL &&
1878 vm_page_all_valid(m) &&
1879 (m->oflags & VPO_SWAPINPROG) == 0);
1880 break;
1881 }
1882 if (!vm_page_busy_acquire(m, VM_ALLOC_WAITFAIL))
1883 break;
1884 }
1885
1886 vm_object_pip_add(object, 1);
1887 rahead = SWAP_META_PAGES;
1888 rv = swap_pager_getpages_locked(object, &m, 1, NULL,
1889 &rahead);
1890 if (rv != VM_PAGER_OK)
1891 panic("%s: read from swap failed: %d",
1892 __func__, rv);
1893 VM_OBJECT_WLOCK(object);
1894 vm_object_pip_wakeupn(object, 1);
1895 vm_page_xunbusy(m);
1896
1897 /*
1898 * The object lock was dropped so we must restart the
1899 * scan of this swap block. Pages paged in during this
1900 * iteration will be marked dirty in a future iteration.
1901 */
1902 break;
1903 }
1904 if (i == SWAP_META_PAGES)
1905 pi = sb->p + SWAP_META_PAGES;
1906 }
1907 }
1908
1909 /*
1910 * swap_pager_swapoff:
1911 *
1912 * Page in all of the pages that have been paged out to the
1913 * given device. The corresponding blocks in the bitmap must be
1914 * marked as allocated and the device must be flagged SW_CLOSING.
1915 * There may be no processes swapped out to the device.
1916 *
1917 * This routine may block.
1918 */
1919 static void
swap_pager_swapoff(struct swdevt * sp)1920 swap_pager_swapoff(struct swdevt *sp)
1921 {
1922 vm_object_t object;
1923 int retries;
1924
1925 sx_assert(&swdev_syscall_lock, SA_XLOCKED);
1926
1927 retries = 0;
1928 full_rescan:
1929 mtx_lock(&vm_object_list_mtx);
1930 TAILQ_FOREACH(object, &vm_object_list, object_list) {
1931 if ((object->flags & OBJ_SWAP) == 0)
1932 continue;
1933 mtx_unlock(&vm_object_list_mtx);
1934 /* Depends on type-stability. */
1935 VM_OBJECT_WLOCK(object);
1936
1937 /*
1938 * Dead objects are eventually terminated on their own.
1939 */
1940 if ((object->flags & OBJ_DEAD) != 0)
1941 goto next_obj;
1942
1943 /*
1944 * Sync with fences placed after pctrie
1945 * initialization. We must not access pctrie below
1946 * unless we checked that our object is swap and not
1947 * dead.
1948 */
1949 atomic_thread_fence_acq();
1950 if ((object->flags & OBJ_SWAP) == 0)
1951 goto next_obj;
1952
1953 swap_pager_swapoff_object(sp, object);
1954 next_obj:
1955 VM_OBJECT_WUNLOCK(object);
1956 mtx_lock(&vm_object_list_mtx);
1957 }
1958 mtx_unlock(&vm_object_list_mtx);
1959
1960 if (sp->sw_used) {
1961 /*
1962 * Objects may be locked or paging to the device being
1963 * removed, so we will miss their pages and need to
1964 * make another pass. We have marked this device as
1965 * SW_CLOSING, so the activity should finish soon.
1966 */
1967 retries++;
1968 if (retries > 100) {
1969 panic("swapoff: failed to locate %d swap blocks",
1970 sp->sw_used);
1971 }
1972 pause("swpoff", hz / 20);
1973 goto full_rescan;
1974 }
1975 EVENTHANDLER_INVOKE(swapoff, sp);
1976 }
1977
1978 /************************************************************************
1979 * SWAP META DATA *
1980 ************************************************************************
1981 *
1982 * These routines manipulate the swap metadata stored in the
1983 * OBJT_SWAP object.
1984 *
1985 * Swap metadata is implemented with a global hash and not directly
1986 * linked into the object. Instead the object simply contains
1987 * appropriate tracking counters.
1988 */
1989
1990 /*
1991 * SWP_PAGER_SWBLK_EMPTY() - is a range of blocks free?
1992 */
1993 static bool
swp_pager_swblk_empty(struct swblk * sb,int start,int limit)1994 swp_pager_swblk_empty(struct swblk *sb, int start, int limit)
1995 {
1996 int i;
1997
1998 MPASS(0 <= start && start <= limit && limit <= SWAP_META_PAGES);
1999 for (i = start; i < limit; i++) {
2000 if (sb->d[i] != SWAPBLK_NONE)
2001 return (false);
2002 }
2003 return (true);
2004 }
2005
2006 /*
2007 * SWP_PAGER_FREE_EMPTY_SWBLK() - frees if a block is free
2008 *
2009 * Nothing is done if the block is still in use.
2010 */
2011 static void
swp_pager_free_empty_swblk(vm_object_t object,struct swblk * sb)2012 swp_pager_free_empty_swblk(vm_object_t object, struct swblk *sb)
2013 {
2014
2015 if (swp_pager_swblk_empty(sb, 0, SWAP_META_PAGES)) {
2016 SWAP_PCTRIE_REMOVE(&object->un_pager.swp.swp_blks, sb->p);
2017 uma_zfree(swblk_zone, sb);
2018 }
2019 }
2020
2021 /*
2022 * SWP_PAGER_META_BUILD() - add swap block to swap meta data for object
2023 *
2024 * The specified swapblk is added to the object's swap metadata. If
2025 * the swapblk is not valid, it is freed instead. Any previously
2026 * assigned swapblk is returned.
2027 */
2028 static daddr_t
swp_pager_meta_build(vm_object_t object,vm_pindex_t pindex,daddr_t swapblk)2029 swp_pager_meta_build(vm_object_t object, vm_pindex_t pindex, daddr_t swapblk)
2030 {
2031 static volatile int swblk_zone_exhausted, swpctrie_zone_exhausted;
2032 struct swblk *sb, *sb1;
2033 vm_pindex_t modpi, rdpi;
2034 daddr_t prev_swapblk;
2035 int error, i;
2036
2037 VM_OBJECT_ASSERT_WLOCKED(object);
2038
2039 rdpi = rounddown(pindex, SWAP_META_PAGES);
2040 sb = SWAP_PCTRIE_LOOKUP(&object->un_pager.swp.swp_blks, rdpi);
2041 if (sb == NULL) {
2042 if (swapblk == SWAPBLK_NONE)
2043 return (SWAPBLK_NONE);
2044 for (;;) {
2045 sb = uma_zalloc(swblk_zone, M_NOWAIT | (curproc ==
2046 pageproc ? M_USE_RESERVE : 0));
2047 if (sb != NULL) {
2048 sb->p = rdpi;
2049 for (i = 0; i < SWAP_META_PAGES; i++)
2050 sb->d[i] = SWAPBLK_NONE;
2051 if (atomic_cmpset_int(&swblk_zone_exhausted,
2052 1, 0))
2053 printf("swblk zone ok\n");
2054 break;
2055 }
2056 VM_OBJECT_WUNLOCK(object);
2057 if (uma_zone_exhausted(swblk_zone)) {
2058 if (atomic_cmpset_int(&swblk_zone_exhausted,
2059 0, 1))
2060 printf("swap blk zone exhausted, "
2061 "increase kern.maxswzone\n");
2062 vm_pageout_oom(VM_OOM_SWAPZ);
2063 pause("swzonxb", 10);
2064 } else
2065 uma_zwait(swblk_zone);
2066 VM_OBJECT_WLOCK(object);
2067 sb = SWAP_PCTRIE_LOOKUP(&object->un_pager.swp.swp_blks,
2068 rdpi);
2069 if (sb != NULL)
2070 /*
2071 * Somebody swapped out a nearby page,
2072 * allocating swblk at the rdpi index,
2073 * while we dropped the object lock.
2074 */
2075 goto allocated;
2076 }
2077 for (;;) {
2078 error = SWAP_PCTRIE_INSERT(
2079 &object->un_pager.swp.swp_blks, sb);
2080 if (error == 0) {
2081 if (atomic_cmpset_int(&swpctrie_zone_exhausted,
2082 1, 0))
2083 printf("swpctrie zone ok\n");
2084 break;
2085 }
2086 VM_OBJECT_WUNLOCK(object);
2087 if (uma_zone_exhausted(swpctrie_zone)) {
2088 if (atomic_cmpset_int(&swpctrie_zone_exhausted,
2089 0, 1))
2090 printf("swap pctrie zone exhausted, "
2091 "increase kern.maxswzone\n");
2092 vm_pageout_oom(VM_OOM_SWAPZ);
2093 pause("swzonxp", 10);
2094 } else
2095 uma_zwait(swpctrie_zone);
2096 VM_OBJECT_WLOCK(object);
2097 sb1 = SWAP_PCTRIE_LOOKUP(&object->un_pager.swp.swp_blks,
2098 rdpi);
2099 if (sb1 != NULL) {
2100 uma_zfree(swblk_zone, sb);
2101 sb = sb1;
2102 goto allocated;
2103 }
2104 }
2105 }
2106 allocated:
2107 MPASS(sb->p == rdpi);
2108
2109 modpi = pindex % SWAP_META_PAGES;
2110 /* Return prior contents of metadata. */
2111 prev_swapblk = sb->d[modpi];
2112 /* Enter block into metadata. */
2113 sb->d[modpi] = swapblk;
2114
2115 /*
2116 * Free the swblk if we end up with the empty page run.
2117 */
2118 if (swapblk == SWAPBLK_NONE)
2119 swp_pager_free_empty_swblk(object, sb);
2120 return (prev_swapblk);
2121 }
2122
2123 /*
2124 * SWP_PAGER_META_TRANSFER() - free a range of blocks in the srcobject's swap
2125 * metadata, or transfer it into dstobject.
2126 *
2127 * This routine will free swap metadata structures as they are cleaned
2128 * out.
2129 */
2130 static void
swp_pager_meta_transfer(vm_object_t srcobject,vm_object_t dstobject,vm_pindex_t pindex,vm_pindex_t count,vm_size_t * moved)2131 swp_pager_meta_transfer(vm_object_t srcobject, vm_object_t dstobject,
2132 vm_pindex_t pindex, vm_pindex_t count, vm_size_t *moved)
2133 {
2134 struct swblk *sb;
2135 vm_page_t m;
2136 daddr_t n_free, s_free;
2137 vm_pindex_t offset, last;
2138 vm_size_t mc;
2139 int i, limit, start;
2140
2141 VM_OBJECT_ASSERT_WLOCKED(srcobject);
2142 MPASS(moved == NULL || dstobject == NULL);
2143
2144 mc = 0;
2145 m = NULL;
2146 if (count == 0 || pctrie_is_empty(&srcobject->un_pager.swp.swp_blks))
2147 goto out;
2148
2149 swp_pager_init_freerange(&s_free, &n_free);
2150 offset = pindex;
2151 last = pindex + count;
2152 for (;;) {
2153 sb = SWAP_PCTRIE_LOOKUP_GE(&srcobject->un_pager.swp.swp_blks,
2154 rounddown(pindex, SWAP_META_PAGES));
2155 if (sb == NULL || sb->p >= last)
2156 break;
2157 start = pindex > sb->p ? pindex - sb->p : 0;
2158 limit = last - sb->p < SWAP_META_PAGES ? last - sb->p :
2159 SWAP_META_PAGES;
2160 for (i = start; i < limit; i++) {
2161 if (sb->d[i] == SWAPBLK_NONE)
2162 continue;
2163 if (dstobject == NULL ||
2164 !swp_pager_xfer_source(srcobject, dstobject,
2165 sb->p + i - offset, sb->d[i])) {
2166 swp_pager_update_freerange(&s_free, &n_free,
2167 sb->d[i]);
2168 }
2169 if (moved != NULL) {
2170 if (m != NULL && m->pindex != pindex + i - 1)
2171 m = NULL;
2172 m = m != NULL ? vm_page_next(m) :
2173 vm_page_lookup(srcobject, pindex + i);
2174 if (m == NULL || vm_page_none_valid(m))
2175 mc++;
2176 }
2177 sb->d[i] = SWAPBLK_NONE;
2178 }
2179 pindex = sb->p + SWAP_META_PAGES;
2180 if (swp_pager_swblk_empty(sb, 0, start) &&
2181 swp_pager_swblk_empty(sb, limit, SWAP_META_PAGES)) {
2182 SWAP_PCTRIE_REMOVE(&srcobject->un_pager.swp.swp_blks,
2183 sb->p);
2184 uma_zfree(swblk_zone, sb);
2185 }
2186 }
2187 swp_pager_freeswapspace(s_free, n_free);
2188 out:
2189 if (moved != NULL)
2190 *moved = mc;
2191 }
2192
2193 /*
2194 * SWP_PAGER_META_FREE() - free a range of blocks in the object's swap metadata
2195 *
2196 * The requested range of blocks is freed, with any associated swap
2197 * returned to the swap bitmap.
2198 *
2199 * This routine will free swap metadata structures as they are cleaned
2200 * out. This routine does *NOT* operate on swap metadata associated
2201 * with resident pages.
2202 */
2203 static void
swp_pager_meta_free(vm_object_t object,vm_pindex_t pindex,vm_pindex_t count,vm_size_t * freed)2204 swp_pager_meta_free(vm_object_t object, vm_pindex_t pindex, vm_pindex_t count,
2205 vm_size_t *freed)
2206 {
2207 swp_pager_meta_transfer(object, NULL, pindex, count, freed);
2208 }
2209
2210 /*
2211 * SWP_PAGER_META_FREE_ALL() - destroy all swap metadata associated with object
2212 *
2213 * This routine locates and destroys all swap metadata associated with
2214 * an object.
2215 */
2216 static void
swp_pager_meta_free_all(vm_object_t object)2217 swp_pager_meta_free_all(vm_object_t object)
2218 {
2219 struct swblk *sb;
2220 daddr_t n_free, s_free;
2221 vm_pindex_t pindex;
2222 int i;
2223
2224 VM_OBJECT_ASSERT_WLOCKED(object);
2225
2226 if (pctrie_is_empty(&object->un_pager.swp.swp_blks))
2227 return;
2228
2229 swp_pager_init_freerange(&s_free, &n_free);
2230 for (pindex = 0; (sb = SWAP_PCTRIE_LOOKUP_GE(
2231 &object->un_pager.swp.swp_blks, pindex)) != NULL;) {
2232 pindex = sb->p + SWAP_META_PAGES;
2233 for (i = 0; i < SWAP_META_PAGES; i++) {
2234 if (sb->d[i] == SWAPBLK_NONE)
2235 continue;
2236 swp_pager_update_freerange(&s_free, &n_free, sb->d[i]);
2237 }
2238 SWAP_PCTRIE_REMOVE(&object->un_pager.swp.swp_blks, sb->p);
2239 uma_zfree(swblk_zone, sb);
2240 }
2241 swp_pager_freeswapspace(s_free, n_free);
2242 }
2243
2244 /*
2245 * SWP_PAGER_METACTL() - misc control of swap meta data.
2246 *
2247 * This routine is capable of looking up, or removing swapblk
2248 * assignments in the swap meta data. It returns the swapblk being
2249 * looked-up, popped, or SWAPBLK_NONE if the block was invalid.
2250 *
2251 * When acting on a busy resident page and paging is in progress, we
2252 * have to wait until paging is complete but otherwise can act on the
2253 * busy page.
2254 */
2255 static daddr_t
swp_pager_meta_lookup(vm_object_t object,vm_pindex_t pindex)2256 swp_pager_meta_lookup(vm_object_t object, vm_pindex_t pindex)
2257 {
2258 struct swblk *sb;
2259
2260 VM_OBJECT_ASSERT_LOCKED(object);
2261
2262 /*
2263 * The meta data only exists if the object is OBJT_SWAP
2264 * and even then might not be allocated yet.
2265 */
2266 KASSERT((object->flags & OBJ_SWAP) != 0,
2267 ("Lookup object not swappable"));
2268
2269 sb = SWAP_PCTRIE_LOOKUP(&object->un_pager.swp.swp_blks,
2270 rounddown(pindex, SWAP_META_PAGES));
2271 if (sb == NULL)
2272 return (SWAPBLK_NONE);
2273 return (sb->d[pindex % SWAP_META_PAGES]);
2274 }
2275
2276 /*
2277 * Returns the least page index which is greater than or equal to the
2278 * parameter pindex and for which there is a swap block allocated.
2279 * Returns object's size if the object's type is not swap or if there
2280 * are no allocated swap blocks for the object after the requested
2281 * pindex.
2282 */
2283 vm_pindex_t
swap_pager_find_least(vm_object_t object,vm_pindex_t pindex)2284 swap_pager_find_least(vm_object_t object, vm_pindex_t pindex)
2285 {
2286 struct swblk *sb;
2287 int i;
2288
2289 VM_OBJECT_ASSERT_LOCKED(object);
2290 MPASS((object->flags & OBJ_SWAP) != 0);
2291
2292 if (pctrie_is_empty(&object->un_pager.swp.swp_blks))
2293 return (object->size);
2294 sb = SWAP_PCTRIE_LOOKUP_GE(&object->un_pager.swp.swp_blks,
2295 rounddown(pindex, SWAP_META_PAGES));
2296 if (sb == NULL)
2297 return (object->size);
2298 if (sb->p < pindex) {
2299 for (i = pindex % SWAP_META_PAGES; i < SWAP_META_PAGES; i++) {
2300 if (sb->d[i] != SWAPBLK_NONE)
2301 return (sb->p + i);
2302 }
2303 sb = SWAP_PCTRIE_LOOKUP_GE(&object->un_pager.swp.swp_blks,
2304 roundup(pindex, SWAP_META_PAGES));
2305 if (sb == NULL)
2306 return (object->size);
2307 }
2308 for (i = 0; i < SWAP_META_PAGES; i++) {
2309 if (sb->d[i] != SWAPBLK_NONE)
2310 return (sb->p + i);
2311 }
2312
2313 /*
2314 * We get here if a swblk is present in the trie but it
2315 * doesn't map any blocks.
2316 */
2317 MPASS(0);
2318 return (object->size);
2319 }
2320
2321 /*
2322 * System call swapon(name) enables swapping on device name,
2323 * which must be in the swdevsw. Return EBUSY
2324 * if already swapping on this device.
2325 */
2326 #ifndef _SYS_SYSPROTO_H_
2327 struct swapon_args {
2328 char *name;
2329 };
2330 #endif
2331
2332 int
sys_swapon(struct thread * td,struct swapon_args * uap)2333 sys_swapon(struct thread *td, struct swapon_args *uap)
2334 {
2335 struct vattr attr;
2336 struct vnode *vp;
2337 struct nameidata nd;
2338 int error;
2339
2340 error = priv_check(td, PRIV_SWAPON);
2341 if (error)
2342 return (error);
2343
2344 sx_xlock(&swdev_syscall_lock);
2345
2346 /*
2347 * Swap metadata may not fit in the KVM if we have physical
2348 * memory of >1GB.
2349 */
2350 if (swblk_zone == NULL) {
2351 error = ENOMEM;
2352 goto done;
2353 }
2354
2355 NDINIT(&nd, LOOKUP, ISOPEN | FOLLOW | LOCKLEAF | AUDITVNODE1,
2356 UIO_USERSPACE, uap->name);
2357 error = namei(&nd);
2358 if (error)
2359 goto done;
2360
2361 NDFREE_PNBUF(&nd);
2362 vp = nd.ni_vp;
2363
2364 if (vn_isdisk_error(vp, &error)) {
2365 error = swapongeom(vp);
2366 } else if (vp->v_type == VREG &&
2367 (vp->v_mount->mnt_vfc->vfc_flags & VFCF_NETWORK) != 0 &&
2368 (error = VOP_GETATTR(vp, &attr, td->td_ucred)) == 0) {
2369 /*
2370 * Allow direct swapping to NFS regular files in the same
2371 * way that nfs_mountroot() sets up diskless swapping.
2372 */
2373 error = swaponvp(td, vp, attr.va_size / DEV_BSIZE);
2374 }
2375
2376 if (error != 0)
2377 vput(vp);
2378 else
2379 VOP_UNLOCK(vp);
2380 done:
2381 sx_xunlock(&swdev_syscall_lock);
2382 return (error);
2383 }
2384
2385 /*
2386 * Check that the total amount of swap currently configured does not
2387 * exceed half the theoretical maximum. If it does, print a warning
2388 * message.
2389 */
2390 static void
swapon_check_swzone(void)2391 swapon_check_swzone(void)
2392 {
2393
2394 /* recommend using no more than half that amount */
2395 if (swap_total > swap_maxpages / 2) {
2396 printf("warning: total configured swap (%lu pages) "
2397 "exceeds maximum recommended amount (%lu pages).\n",
2398 swap_total, swap_maxpages / 2);
2399 printf("warning: increase kern.maxswzone "
2400 "or reduce amount of swap.\n");
2401 }
2402 }
2403
2404 static void
swaponsomething(struct vnode * vp,void * id,u_long nblks,sw_strategy_t * strategy,sw_close_t * close,dev_t dev,int flags)2405 swaponsomething(struct vnode *vp, void *id, u_long nblks,
2406 sw_strategy_t *strategy, sw_close_t *close, dev_t dev, int flags)
2407 {
2408 struct swdevt *sp, *tsp;
2409 daddr_t dvbase;
2410
2411 /*
2412 * nblks is in DEV_BSIZE'd chunks, convert to PAGE_SIZE'd chunks.
2413 * First chop nblks off to page-align it, then convert.
2414 *
2415 * sw->sw_nblks is in page-sized chunks now too.
2416 */
2417 nblks &= ~(ctodb(1) - 1);
2418 nblks = dbtoc(nblks);
2419
2420 sp = malloc(sizeof *sp, M_VMPGDATA, M_WAITOK | M_ZERO);
2421 sp->sw_blist = blist_create(nblks, M_WAITOK);
2422 sp->sw_vp = vp;
2423 sp->sw_id = id;
2424 sp->sw_dev = dev;
2425 sp->sw_nblks = nblks;
2426 sp->sw_used = 0;
2427 sp->sw_strategy = strategy;
2428 sp->sw_close = close;
2429 sp->sw_flags = flags;
2430
2431 /*
2432 * Do not free the first blocks in order to avoid overwriting
2433 * any bsd label at the front of the partition
2434 */
2435 blist_free(sp->sw_blist, howmany(BBSIZE, PAGE_SIZE),
2436 nblks - howmany(BBSIZE, PAGE_SIZE));
2437
2438 dvbase = 0;
2439 mtx_lock(&sw_dev_mtx);
2440 TAILQ_FOREACH(tsp, &swtailq, sw_list) {
2441 if (tsp->sw_end >= dvbase) {
2442 /*
2443 * We put one uncovered page between the devices
2444 * in order to definitively prevent any cross-device
2445 * I/O requests
2446 */
2447 dvbase = tsp->sw_end + 1;
2448 }
2449 }
2450 sp->sw_first = dvbase;
2451 sp->sw_end = dvbase + nblks;
2452 TAILQ_INSERT_TAIL(&swtailq, sp, sw_list);
2453 nswapdev++;
2454 swap_pager_avail += nblks - howmany(BBSIZE, PAGE_SIZE);
2455 swap_total += nblks;
2456 swapon_check_swzone();
2457 swp_sizecheck();
2458 mtx_unlock(&sw_dev_mtx);
2459 EVENTHANDLER_INVOKE(swapon, sp);
2460 }
2461
2462 /*
2463 * SYSCALL: swapoff(devname)
2464 *
2465 * Disable swapping on the given device.
2466 *
2467 * XXX: Badly designed system call: it should use a device index
2468 * rather than filename as specification. We keep sw_vp around
2469 * only to make this work.
2470 */
2471 static int
kern_swapoff(struct thread * td,const char * name,enum uio_seg name_seg,u_int flags)2472 kern_swapoff(struct thread *td, const char *name, enum uio_seg name_seg,
2473 u_int flags)
2474 {
2475 struct vnode *vp;
2476 struct nameidata nd;
2477 struct swdevt *sp;
2478 int error;
2479
2480 error = priv_check(td, PRIV_SWAPOFF);
2481 if (error != 0)
2482 return (error);
2483 if ((flags & ~(SWAPOFF_FORCE)) != 0)
2484 return (EINVAL);
2485
2486 sx_xlock(&swdev_syscall_lock);
2487
2488 NDINIT(&nd, LOOKUP, FOLLOW | AUDITVNODE1, name_seg, name);
2489 error = namei(&nd);
2490 if (error)
2491 goto done;
2492 NDFREE_PNBUF(&nd);
2493 vp = nd.ni_vp;
2494
2495 mtx_lock(&sw_dev_mtx);
2496 TAILQ_FOREACH(sp, &swtailq, sw_list) {
2497 if (sp->sw_vp == vp)
2498 break;
2499 }
2500 mtx_unlock(&sw_dev_mtx);
2501 if (sp == NULL) {
2502 error = EINVAL;
2503 goto done;
2504 }
2505 error = swapoff_one(sp, td->td_ucred, flags);
2506 done:
2507 sx_xunlock(&swdev_syscall_lock);
2508 return (error);
2509 }
2510
2511
2512 #ifdef COMPAT_FREEBSD13
2513 int
freebsd13_swapoff(struct thread * td,struct freebsd13_swapoff_args * uap)2514 freebsd13_swapoff(struct thread *td, struct freebsd13_swapoff_args *uap)
2515 {
2516 return (kern_swapoff(td, uap->name, UIO_USERSPACE, 0));
2517 }
2518 #endif
2519
2520 int
sys_swapoff(struct thread * td,struct swapoff_args * uap)2521 sys_swapoff(struct thread *td, struct swapoff_args *uap)
2522 {
2523 return (kern_swapoff(td, uap->name, UIO_USERSPACE, uap->flags));
2524 }
2525
2526 static int
swapoff_one(struct swdevt * sp,struct ucred * cred,u_int flags)2527 swapoff_one(struct swdevt *sp, struct ucred *cred, u_int flags)
2528 {
2529 u_long nblks;
2530 #ifdef MAC
2531 int error;
2532 #endif
2533
2534 sx_assert(&swdev_syscall_lock, SA_XLOCKED);
2535 #ifdef MAC
2536 (void) vn_lock(sp->sw_vp, LK_EXCLUSIVE | LK_RETRY);
2537 error = mac_system_check_swapoff(cred, sp->sw_vp);
2538 (void) VOP_UNLOCK(sp->sw_vp);
2539 if (error != 0)
2540 return (error);
2541 #endif
2542 nblks = sp->sw_nblks;
2543
2544 /*
2545 * We can turn off this swap device safely only if the
2546 * available virtual memory in the system will fit the amount
2547 * of data we will have to page back in, plus an epsilon so
2548 * the system doesn't become critically low on swap space.
2549 * The vm_free_count() part does not account e.g. for clean
2550 * pages that can be immediately reclaimed without paging, so
2551 * this is a very rough estimation.
2552 *
2553 * On the other hand, not turning swap off on swapoff_all()
2554 * means that we can lose swap data when filesystems go away,
2555 * which is arguably worse.
2556 */
2557 if ((flags & SWAPOFF_FORCE) == 0 &&
2558 vm_free_count() + swap_pager_avail < nblks + nswap_lowat)
2559 return (ENOMEM);
2560
2561 /*
2562 * Prevent further allocations on this device.
2563 */
2564 mtx_lock(&sw_dev_mtx);
2565 sp->sw_flags |= SW_CLOSING;
2566 swap_pager_avail -= blist_fill(sp->sw_blist, 0, nblks);
2567 swap_total -= nblks;
2568 mtx_unlock(&sw_dev_mtx);
2569
2570 /*
2571 * Page in the contents of the device and close it.
2572 */
2573 swap_pager_swapoff(sp);
2574
2575 sp->sw_close(curthread, sp);
2576 mtx_lock(&sw_dev_mtx);
2577 sp->sw_id = NULL;
2578 TAILQ_REMOVE(&swtailq, sp, sw_list);
2579 nswapdev--;
2580 if (nswapdev == 0) {
2581 swap_pager_full = 2;
2582 swap_pager_almost_full = 1;
2583 }
2584 if (swdevhd == sp)
2585 swdevhd = NULL;
2586 mtx_unlock(&sw_dev_mtx);
2587 blist_destroy(sp->sw_blist);
2588 free(sp, M_VMPGDATA);
2589 return (0);
2590 }
2591
2592 void
swapoff_all(void)2593 swapoff_all(void)
2594 {
2595 struct swdevt *sp, *spt;
2596 const char *devname;
2597 int error;
2598
2599 sx_xlock(&swdev_syscall_lock);
2600
2601 mtx_lock(&sw_dev_mtx);
2602 TAILQ_FOREACH_SAFE(sp, &swtailq, sw_list, spt) {
2603 mtx_unlock(&sw_dev_mtx);
2604 if (vn_isdisk(sp->sw_vp))
2605 devname = devtoname(sp->sw_vp->v_rdev);
2606 else
2607 devname = "[file]";
2608 error = swapoff_one(sp, thread0.td_ucred, SWAPOFF_FORCE);
2609 if (error != 0) {
2610 printf("Cannot remove swap device %s (error=%d), "
2611 "skipping.\n", devname, error);
2612 } else if (bootverbose) {
2613 printf("Swap device %s removed.\n", devname);
2614 }
2615 mtx_lock(&sw_dev_mtx);
2616 }
2617 mtx_unlock(&sw_dev_mtx);
2618
2619 sx_xunlock(&swdev_syscall_lock);
2620 }
2621
2622 void
swap_pager_status(int * total,int * used)2623 swap_pager_status(int *total, int *used)
2624 {
2625
2626 *total = swap_total;
2627 *used = swap_total - swap_pager_avail -
2628 nswapdev * howmany(BBSIZE, PAGE_SIZE);
2629 }
2630
2631 int
swap_dev_info(int name,struct xswdev * xs,char * devname,size_t len)2632 swap_dev_info(int name, struct xswdev *xs, char *devname, size_t len)
2633 {
2634 struct swdevt *sp;
2635 const char *tmp_devname;
2636 int error, n;
2637
2638 n = 0;
2639 error = ENOENT;
2640 mtx_lock(&sw_dev_mtx);
2641 TAILQ_FOREACH(sp, &swtailq, sw_list) {
2642 if (n != name) {
2643 n++;
2644 continue;
2645 }
2646 xs->xsw_version = XSWDEV_VERSION;
2647 xs->xsw_dev = sp->sw_dev;
2648 xs->xsw_flags = sp->sw_flags;
2649 xs->xsw_nblks = sp->sw_nblks;
2650 xs->xsw_used = sp->sw_used;
2651 if (devname != NULL) {
2652 if (vn_isdisk(sp->sw_vp))
2653 tmp_devname = devtoname(sp->sw_vp->v_rdev);
2654 else
2655 tmp_devname = "[file]";
2656 strncpy(devname, tmp_devname, len);
2657 }
2658 error = 0;
2659 break;
2660 }
2661 mtx_unlock(&sw_dev_mtx);
2662 return (error);
2663 }
2664
2665 #if defined(COMPAT_FREEBSD11)
2666 #define XSWDEV_VERSION_11 1
2667 struct xswdev11 {
2668 u_int xsw_version;
2669 uint32_t xsw_dev;
2670 int xsw_flags;
2671 int xsw_nblks;
2672 int xsw_used;
2673 };
2674 #endif
2675
2676 #if defined(__amd64__) && defined(COMPAT_FREEBSD32)
2677 struct xswdev32 {
2678 u_int xsw_version;
2679 u_int xsw_dev1, xsw_dev2;
2680 int xsw_flags;
2681 int xsw_nblks;
2682 int xsw_used;
2683 };
2684 #endif
2685
2686 static int
sysctl_vm_swap_info(SYSCTL_HANDLER_ARGS)2687 sysctl_vm_swap_info(SYSCTL_HANDLER_ARGS)
2688 {
2689 struct xswdev xs;
2690 #if defined(__amd64__) && defined(COMPAT_FREEBSD32)
2691 struct xswdev32 xs32;
2692 #endif
2693 #if defined(COMPAT_FREEBSD11)
2694 struct xswdev11 xs11;
2695 #endif
2696 int error;
2697
2698 if (arg2 != 1) /* name length */
2699 return (EINVAL);
2700
2701 memset(&xs, 0, sizeof(xs));
2702 error = swap_dev_info(*(int *)arg1, &xs, NULL, 0);
2703 if (error != 0)
2704 return (error);
2705 #if defined(__amd64__) && defined(COMPAT_FREEBSD32)
2706 if (req->oldlen == sizeof(xs32)) {
2707 memset(&xs32, 0, sizeof(xs32));
2708 xs32.xsw_version = XSWDEV_VERSION;
2709 xs32.xsw_dev1 = xs.xsw_dev;
2710 xs32.xsw_dev2 = xs.xsw_dev >> 32;
2711 xs32.xsw_flags = xs.xsw_flags;
2712 xs32.xsw_nblks = xs.xsw_nblks;
2713 xs32.xsw_used = xs.xsw_used;
2714 error = SYSCTL_OUT(req, &xs32, sizeof(xs32));
2715 return (error);
2716 }
2717 #endif
2718 #if defined(COMPAT_FREEBSD11)
2719 if (req->oldlen == sizeof(xs11)) {
2720 memset(&xs11, 0, sizeof(xs11));
2721 xs11.xsw_version = XSWDEV_VERSION_11;
2722 xs11.xsw_dev = xs.xsw_dev; /* truncation */
2723 xs11.xsw_flags = xs.xsw_flags;
2724 xs11.xsw_nblks = xs.xsw_nblks;
2725 xs11.xsw_used = xs.xsw_used;
2726 error = SYSCTL_OUT(req, &xs11, sizeof(xs11));
2727 return (error);
2728 }
2729 #endif
2730 error = SYSCTL_OUT(req, &xs, sizeof(xs));
2731 return (error);
2732 }
2733
2734 SYSCTL_INT(_vm, OID_AUTO, nswapdev, CTLFLAG_RD, &nswapdev, 0,
2735 "Number of swap devices");
2736 SYSCTL_NODE(_vm, OID_AUTO, swap_info, CTLFLAG_RD | CTLFLAG_MPSAFE,
2737 sysctl_vm_swap_info,
2738 "Swap statistics by device");
2739
2740 /*
2741 * Count the approximate swap usage in pages for a vmspace. The
2742 * shadowed or not yet copied on write swap blocks are not accounted.
2743 * The map must be locked.
2744 */
2745 long
vmspace_swap_count(struct vmspace * vmspace)2746 vmspace_swap_count(struct vmspace *vmspace)
2747 {
2748 vm_map_t map;
2749 vm_map_entry_t cur;
2750 vm_object_t object;
2751 struct swblk *sb;
2752 vm_pindex_t e, pi;
2753 long count;
2754 int i;
2755
2756 map = &vmspace->vm_map;
2757 count = 0;
2758
2759 VM_MAP_ENTRY_FOREACH(cur, map) {
2760 if ((cur->eflags & MAP_ENTRY_IS_SUB_MAP) != 0)
2761 continue;
2762 object = cur->object.vm_object;
2763 if (object == NULL || (object->flags & OBJ_SWAP) == 0)
2764 continue;
2765 VM_OBJECT_RLOCK(object);
2766 if ((object->flags & OBJ_SWAP) == 0)
2767 goto unlock;
2768 pi = OFF_TO_IDX(cur->offset);
2769 e = pi + OFF_TO_IDX(cur->end - cur->start);
2770 for (;; pi = sb->p + SWAP_META_PAGES) {
2771 sb = SWAP_PCTRIE_LOOKUP_GE(
2772 &object->un_pager.swp.swp_blks, pi);
2773 if (sb == NULL || sb->p >= e)
2774 break;
2775 for (i = 0; i < SWAP_META_PAGES; i++) {
2776 if (sb->p + i < e &&
2777 sb->d[i] != SWAPBLK_NONE)
2778 count++;
2779 }
2780 }
2781 unlock:
2782 VM_OBJECT_RUNLOCK(object);
2783 }
2784 return (count);
2785 }
2786
2787 /*
2788 * GEOM backend
2789 *
2790 * Swapping onto disk devices.
2791 *
2792 */
2793
2794 static g_orphan_t swapgeom_orphan;
2795
2796 static struct g_class g_swap_class = {
2797 .name = "SWAP",
2798 .version = G_VERSION,
2799 .orphan = swapgeom_orphan,
2800 };
2801
2802 DECLARE_GEOM_CLASS(g_swap_class, g_class);
2803
2804 static void
swapgeom_close_ev(void * arg,int flags)2805 swapgeom_close_ev(void *arg, int flags)
2806 {
2807 struct g_consumer *cp;
2808
2809 cp = arg;
2810 g_access(cp, -1, -1, 0);
2811 g_detach(cp);
2812 g_destroy_consumer(cp);
2813 }
2814
2815 /*
2816 * Add a reference to the g_consumer for an inflight transaction.
2817 */
2818 static void
swapgeom_acquire(struct g_consumer * cp)2819 swapgeom_acquire(struct g_consumer *cp)
2820 {
2821
2822 mtx_assert(&sw_dev_mtx, MA_OWNED);
2823 cp->index++;
2824 }
2825
2826 /*
2827 * Remove a reference from the g_consumer. Post a close event if all
2828 * references go away, since the function might be called from the
2829 * biodone context.
2830 */
2831 static void
swapgeom_release(struct g_consumer * cp,struct swdevt * sp)2832 swapgeom_release(struct g_consumer *cp, struct swdevt *sp)
2833 {
2834
2835 mtx_assert(&sw_dev_mtx, MA_OWNED);
2836 cp->index--;
2837 if (cp->index == 0) {
2838 if (g_post_event(swapgeom_close_ev, cp, M_NOWAIT, NULL) == 0)
2839 sp->sw_id = NULL;
2840 }
2841 }
2842
2843 static void
swapgeom_done(struct bio * bp2)2844 swapgeom_done(struct bio *bp2)
2845 {
2846 struct swdevt *sp;
2847 struct buf *bp;
2848 struct g_consumer *cp;
2849
2850 bp = bp2->bio_caller2;
2851 cp = bp2->bio_from;
2852 bp->b_ioflags = bp2->bio_flags;
2853 if (bp2->bio_error)
2854 bp->b_ioflags |= BIO_ERROR;
2855 bp->b_resid = bp->b_bcount - bp2->bio_completed;
2856 bp->b_error = bp2->bio_error;
2857 bp->b_caller1 = NULL;
2858 bufdone(bp);
2859 sp = bp2->bio_caller1;
2860 mtx_lock(&sw_dev_mtx);
2861 swapgeom_release(cp, sp);
2862 mtx_unlock(&sw_dev_mtx);
2863 g_destroy_bio(bp2);
2864 }
2865
2866 static void
swapgeom_strategy(struct buf * bp,struct swdevt * sp)2867 swapgeom_strategy(struct buf *bp, struct swdevt *sp)
2868 {
2869 struct bio *bio;
2870 struct g_consumer *cp;
2871
2872 mtx_lock(&sw_dev_mtx);
2873 cp = sp->sw_id;
2874 if (cp == NULL) {
2875 mtx_unlock(&sw_dev_mtx);
2876 bp->b_error = ENXIO;
2877 bp->b_ioflags |= BIO_ERROR;
2878 bufdone(bp);
2879 return;
2880 }
2881 swapgeom_acquire(cp);
2882 mtx_unlock(&sw_dev_mtx);
2883 if (bp->b_iocmd == BIO_WRITE)
2884 bio = g_new_bio();
2885 else
2886 bio = g_alloc_bio();
2887 if (bio == NULL) {
2888 mtx_lock(&sw_dev_mtx);
2889 swapgeom_release(cp, sp);
2890 mtx_unlock(&sw_dev_mtx);
2891 bp->b_error = ENOMEM;
2892 bp->b_ioflags |= BIO_ERROR;
2893 printf("swap_pager: cannot allocate bio\n");
2894 bufdone(bp);
2895 return;
2896 }
2897
2898 bp->b_caller1 = bio;
2899 bio->bio_caller1 = sp;
2900 bio->bio_caller2 = bp;
2901 bio->bio_cmd = bp->b_iocmd;
2902 bio->bio_offset = (bp->b_blkno - sp->sw_first) * PAGE_SIZE;
2903 bio->bio_length = bp->b_bcount;
2904 bio->bio_done = swapgeom_done;
2905 bio->bio_flags |= BIO_SWAP;
2906 if (!buf_mapped(bp)) {
2907 bio->bio_ma = bp->b_pages;
2908 bio->bio_data = unmapped_buf;
2909 bio->bio_ma_offset = (vm_offset_t)bp->b_offset & PAGE_MASK;
2910 bio->bio_ma_n = bp->b_npages;
2911 bio->bio_flags |= BIO_UNMAPPED;
2912 } else {
2913 bio->bio_data = bp->b_data;
2914 bio->bio_ma = NULL;
2915 }
2916 g_io_request(bio, cp);
2917 return;
2918 }
2919
2920 static void
swapgeom_orphan(struct g_consumer * cp)2921 swapgeom_orphan(struct g_consumer *cp)
2922 {
2923 struct swdevt *sp;
2924 int destroy;
2925
2926 mtx_lock(&sw_dev_mtx);
2927 TAILQ_FOREACH(sp, &swtailq, sw_list) {
2928 if (sp->sw_id == cp) {
2929 sp->sw_flags |= SW_CLOSING;
2930 break;
2931 }
2932 }
2933 /*
2934 * Drop reference we were created with. Do directly since we're in a
2935 * special context where we don't have to queue the call to
2936 * swapgeom_close_ev().
2937 */
2938 cp->index--;
2939 destroy = ((sp != NULL) && (cp->index == 0));
2940 if (destroy)
2941 sp->sw_id = NULL;
2942 mtx_unlock(&sw_dev_mtx);
2943 if (destroy)
2944 swapgeom_close_ev(cp, 0);
2945 }
2946
2947 static void
swapgeom_close(struct thread * td,struct swdevt * sw)2948 swapgeom_close(struct thread *td, struct swdevt *sw)
2949 {
2950 struct g_consumer *cp;
2951
2952 mtx_lock(&sw_dev_mtx);
2953 cp = sw->sw_id;
2954 sw->sw_id = NULL;
2955 mtx_unlock(&sw_dev_mtx);
2956
2957 /*
2958 * swapgeom_close() may be called from the biodone context,
2959 * where we cannot perform topology changes. Delegate the
2960 * work to the events thread.
2961 */
2962 if (cp != NULL)
2963 g_waitfor_event(swapgeom_close_ev, cp, M_WAITOK, NULL);
2964 }
2965
2966 static int
swapongeom_locked(struct cdev * dev,struct vnode * vp)2967 swapongeom_locked(struct cdev *dev, struct vnode *vp)
2968 {
2969 struct g_provider *pp;
2970 struct g_consumer *cp;
2971 static struct g_geom *gp;
2972 struct swdevt *sp;
2973 u_long nblks;
2974 int error;
2975
2976 pp = g_dev_getprovider(dev);
2977 if (pp == NULL)
2978 return (ENODEV);
2979 mtx_lock(&sw_dev_mtx);
2980 TAILQ_FOREACH(sp, &swtailq, sw_list) {
2981 cp = sp->sw_id;
2982 if (cp != NULL && cp->provider == pp) {
2983 mtx_unlock(&sw_dev_mtx);
2984 return (EBUSY);
2985 }
2986 }
2987 mtx_unlock(&sw_dev_mtx);
2988 if (gp == NULL)
2989 gp = g_new_geomf(&g_swap_class, "swap");
2990 cp = g_new_consumer(gp);
2991 cp->index = 1; /* Number of active I/Os, plus one for being active. */
2992 cp->flags |= G_CF_DIRECT_SEND | G_CF_DIRECT_RECEIVE;
2993 g_attach(cp, pp);
2994 /*
2995 * XXX: Every time you think you can improve the margin for
2996 * footshooting, somebody depends on the ability to do so:
2997 * savecore(8) wants to write to our swapdev so we cannot
2998 * set an exclusive count :-(
2999 */
3000 error = g_access(cp, 1, 1, 0);
3001 if (error != 0) {
3002 g_detach(cp);
3003 g_destroy_consumer(cp);
3004 return (error);
3005 }
3006 nblks = pp->mediasize / DEV_BSIZE;
3007 swaponsomething(vp, cp, nblks, swapgeom_strategy,
3008 swapgeom_close, dev2udev(dev),
3009 (pp->flags & G_PF_ACCEPT_UNMAPPED) != 0 ? SW_UNMAPPED : 0);
3010 return (0);
3011 }
3012
3013 static int
swapongeom(struct vnode * vp)3014 swapongeom(struct vnode *vp)
3015 {
3016 int error;
3017
3018 ASSERT_VOP_ELOCKED(vp, "swapongeom");
3019 if (vp->v_type != VCHR || VN_IS_DOOMED(vp)) {
3020 error = ENOENT;
3021 } else {
3022 g_topology_lock();
3023 error = swapongeom_locked(vp->v_rdev, vp);
3024 g_topology_unlock();
3025 }
3026 return (error);
3027 }
3028
3029 /*
3030 * VNODE backend
3031 *
3032 * This is used mainly for network filesystem (read: probably only tested
3033 * with NFS) swapfiles.
3034 *
3035 */
3036
3037 static void
swapdev_strategy(struct buf * bp,struct swdevt * sp)3038 swapdev_strategy(struct buf *bp, struct swdevt *sp)
3039 {
3040 struct vnode *vp2;
3041
3042 bp->b_blkno = ctodb(bp->b_blkno - sp->sw_first);
3043
3044 vp2 = sp->sw_id;
3045 vhold(vp2);
3046 if (bp->b_iocmd == BIO_WRITE) {
3047 vn_lock(vp2, LK_EXCLUSIVE | LK_RETRY);
3048 if (bp->b_bufobj)
3049 bufobj_wdrop(bp->b_bufobj);
3050 bufobj_wref(&vp2->v_bufobj);
3051 } else {
3052 vn_lock(vp2, LK_SHARED | LK_RETRY);
3053 }
3054 if (bp->b_bufobj != &vp2->v_bufobj)
3055 bp->b_bufobj = &vp2->v_bufobj;
3056 bp->b_vp = vp2;
3057 bp->b_iooffset = dbtob(bp->b_blkno);
3058 bstrategy(bp);
3059 VOP_UNLOCK(vp2);
3060 }
3061
3062 static void
swapdev_close(struct thread * td,struct swdevt * sp)3063 swapdev_close(struct thread *td, struct swdevt *sp)
3064 {
3065 struct vnode *vp;
3066
3067 vp = sp->sw_vp;
3068 vn_lock(vp, LK_EXCLUSIVE | LK_RETRY);
3069 VOP_CLOSE(vp, FREAD | FWRITE, td->td_ucred, td);
3070 vput(vp);
3071 }
3072
3073 static int
swaponvp(struct thread * td,struct vnode * vp,u_long nblks)3074 swaponvp(struct thread *td, struct vnode *vp, u_long nblks)
3075 {
3076 struct swdevt *sp;
3077 int error;
3078
3079 ASSERT_VOP_ELOCKED(vp, "swaponvp");
3080 if (nblks == 0)
3081 return (ENXIO);
3082 mtx_lock(&sw_dev_mtx);
3083 TAILQ_FOREACH(sp, &swtailq, sw_list) {
3084 if (sp->sw_id == vp) {
3085 mtx_unlock(&sw_dev_mtx);
3086 return (EBUSY);
3087 }
3088 }
3089 mtx_unlock(&sw_dev_mtx);
3090
3091 #ifdef MAC
3092 error = mac_system_check_swapon(td->td_ucred, vp);
3093 if (error == 0)
3094 #endif
3095 error = VOP_OPEN(vp, FREAD | FWRITE, td->td_ucred, td, NULL);
3096 if (error != 0)
3097 return (error);
3098
3099 swaponsomething(vp, vp, nblks, swapdev_strategy, swapdev_close,
3100 NODEV, 0);
3101 return (0);
3102 }
3103
3104 static int
sysctl_swap_async_max(SYSCTL_HANDLER_ARGS)3105 sysctl_swap_async_max(SYSCTL_HANDLER_ARGS)
3106 {
3107 int error, new, n;
3108
3109 new = nsw_wcount_async_max;
3110 error = sysctl_handle_int(oidp, &new, 0, req);
3111 if (error != 0 || req->newptr == NULL)
3112 return (error);
3113
3114 if (new > nswbuf / 2 || new < 1)
3115 return (EINVAL);
3116
3117 mtx_lock(&swbuf_mtx);
3118 while (nsw_wcount_async_max != new) {
3119 /*
3120 * Adjust difference. If the current async count is too low,
3121 * we will need to sqeeze our update slowly in. Sleep with a
3122 * higher priority than getpbuf() to finish faster.
3123 */
3124 n = new - nsw_wcount_async_max;
3125 if (nsw_wcount_async + n >= 0) {
3126 nsw_wcount_async += n;
3127 nsw_wcount_async_max += n;
3128 wakeup(&nsw_wcount_async);
3129 } else {
3130 nsw_wcount_async_max -= nsw_wcount_async;
3131 nsw_wcount_async = 0;
3132 msleep(&nsw_wcount_async, &swbuf_mtx, PSWP,
3133 "swpsysctl", 0);
3134 }
3135 }
3136 mtx_unlock(&swbuf_mtx);
3137
3138 return (0);
3139 }
3140
3141 static void
swap_pager_update_writecount(vm_object_t object,vm_offset_t start,vm_offset_t end)3142 swap_pager_update_writecount(vm_object_t object, vm_offset_t start,
3143 vm_offset_t end)
3144 {
3145
3146 VM_OBJECT_WLOCK(object);
3147 KASSERT((object->flags & OBJ_ANON) == 0,
3148 ("Splittable object with writecount"));
3149 object->un_pager.swp.writemappings += (vm_ooffset_t)end - start;
3150 VM_OBJECT_WUNLOCK(object);
3151 }
3152
3153 static void
swap_pager_release_writecount(vm_object_t object,vm_offset_t start,vm_offset_t end)3154 swap_pager_release_writecount(vm_object_t object, vm_offset_t start,
3155 vm_offset_t end)
3156 {
3157
3158 VM_OBJECT_WLOCK(object);
3159 KASSERT((object->flags & OBJ_ANON) == 0,
3160 ("Splittable object with writecount"));
3161 object->un_pager.swp.writemappings -= (vm_ooffset_t)end - start;
3162 VM_OBJECT_WUNLOCK(object);
3163 }
3164