FreeBSD/Linux Kernel Cross Reference
sys/vm/swap_pager.c
1 /*
2 * Copyright (c) 1998 Matthew Dillon,
3 * Copyright (c) 1994 John S. Dyson
4 * Copyright (c) 1990 University of Utah.
5 * Copyright (c) 1982, 1986, 1989, 1993
6 * The Regents of the University of California. All rights reserved.
7 *
8 * This code is derived from software contributed to Berkeley by
9 * the Systems Programming Group of the University of Utah Computer
10 * Science Department.
11 *
12 * Redistribution and use in source and binary forms, with or without
13 * modification, are permitted provided that the following conditions
14 * are met:
15 * 1. Redistributions of source code must retain the above copyright
16 * notice, this list of conditions and the following disclaimer.
17 * 2. Redistributions in binary form must reproduce the above copyright
18 * notice, this list of conditions and the following disclaimer in the
19 * documentation and/or other materials provided with the distribution.
20 * 3. All advertising materials mentioning features or use of this software
21 * must display the following acknowledgement:
22 * This product includes software developed by the University of
23 * California, Berkeley and its contributors.
24 * 4. Neither the name of the University nor the names of its contributors
25 * may be used to endorse or promote products derived from this software
26 * without specific prior written permission.
27 *
28 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
29 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
30 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
31 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
32 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
33 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
34 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
35 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
36 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
37 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
38 * SUCH DAMAGE.
39 *
40 * New Swap System
41 * Matthew Dillon
42 *
43 * Radix Bitmap 'blists'.
44 *
45 * - The new swapper uses the new radix bitmap code. This should scale
46 * to arbitrarily small or arbitrarily large swap spaces and an almost
47 * arbitrary degree of fragmentation.
48 *
49 * Features:
50 *
51 * - on the fly reallocation of swap during putpages. The new system
52 * does not try to keep previously allocated swap blocks for dirty
53 * pages.
54 *
55 * - on the fly deallocation of swap
56 *
57 * - No more garbage collection required. Unnecessarily allocated swap
58 * blocks only exist for dirty vm_page_t's now and these are already
59 * cycled (in a high-load system) by the pager. We also do on-the-fly
60 * removal of invalidated swap blocks when a page is destroyed
61 * or renamed.
62 *
63 * from: Utah $Hdr: swap_pager.c 1.4 91/04/30$
64 *
65 * @(#)swap_pager.c 8.9 (Berkeley) 3/21/94
66 * @(#)vm_swap.c 8.5 (Berkeley) 2/17/94
67 */
68
69 #include <sys/cdefs.h>
70 __FBSDID("$FreeBSD: releng/5.3/sys/vm/swap_pager.c 135840 2004-09-27 04:53:18Z das $");
71
72 #include "opt_mac.h"
73 #include "opt_swap.h"
74 #include "opt_vm.h"
75
76 #include <sys/param.h>
77 #include <sys/systm.h>
78 #include <sys/conf.h>
79 #include <sys/kernel.h>
80 #include <sys/proc.h>
81 #include <sys/bio.h>
82 #include <sys/buf.h>
83 #include <sys/disk.h>
84 #include <sys/fcntl.h>
85 #include <sys/mount.h>
86 #include <sys/namei.h>
87 #include <sys/vnode.h>
88 #include <sys/mac.h>
89 #include <sys/malloc.h>
90 #include <sys/sysctl.h>
91 #include <sys/sysproto.h>
92 #include <sys/blist.h>
93 #include <sys/lock.h>
94 #include <sys/sx.h>
95 #include <sys/vmmeter.h>
96
97 #include <vm/vm.h>
98 #include <vm/pmap.h>
99 #include <vm/vm_map.h>
100 #include <vm/vm_kern.h>
101 #include <vm/vm_object.h>
102 #include <vm/vm_page.h>
103 #include <vm/vm_pager.h>
104 #include <vm/vm_pageout.h>
105 #include <vm/vm_param.h>
106 #include <vm/swap_pager.h>
107 #include <vm/vm_extern.h>
108 #include <vm/uma.h>
109
110 #include <geom/geom.h>
111
112 /*
113 * SWB_NPAGES must be a power of 2. It may be set to 1, 2, 4, 8, or 16
114 * pages per allocation. We recommend you stick with the default of 8.
115 * The 16-page limit is due to the radix code (kern/subr_blist.c).
116 */
117 #ifndef MAX_PAGEOUT_CLUSTER
118 #define MAX_PAGEOUT_CLUSTER 16
119 #endif
120
121 #if !defined(SWB_NPAGES)
122 #define SWB_NPAGES MAX_PAGEOUT_CLUSTER
123 #endif
124
125 /*
126 * Piecemeal swap metadata structure. Swap is stored in a radix tree.
127 *
128 * If SWB_NPAGES is 8 and sizeof(char *) == sizeof(daddr_t), our radix
129 * is basically 8. Assuming PAGE_SIZE == 4096, one tree level represents
130 * 32K worth of data, two levels represent 256K, three levels represent
131 * 2 MBytes. This is acceptable.
132 *
133 * Overall memory utilization is about the same as the old swap structure.
134 */
135 #define SWCORRECT(n) (sizeof(void *) * (n) / sizeof(daddr_t))
136 #define SWAP_META_PAGES (SWB_NPAGES * 2)
137 #define SWAP_META_MASK (SWAP_META_PAGES - 1)
138
139 typedef int32_t swblk_t; /*
140 * swap offset. This is the type used to
141 * address the "virtual swap device" and
142 * therefore the maximum swap space is
143 * 2^32 pages.
144 */
145
146 struct swdevt;
147 typedef void sw_strategy_t(struct buf *bp, struct swdevt *sw);
148 typedef void sw_close_t(struct thread *td, struct swdevt *sw);
149
150 /*
151 * Swap device table
152 */
153 struct swdevt {
154 int sw_flags;
155 int sw_nblks;
156 int sw_used;
157 dev_t sw_dev;
158 struct vnode *sw_vp;
159 void *sw_id;
160 swblk_t sw_first;
161 swblk_t sw_end;
162 struct blist *sw_blist;
163 TAILQ_ENTRY(swdevt) sw_list;
164 sw_strategy_t *sw_strategy;
165 sw_close_t *sw_close;
166 };
167
168 #define SW_CLOSING 0x04
169
170 struct swblock {
171 struct swblock *swb_hnext;
172 vm_object_t swb_object;
173 vm_pindex_t swb_index;
174 int swb_count;
175 daddr_t swb_pages[SWAP_META_PAGES];
176 };
177
178 static struct mtx sw_dev_mtx;
179 static TAILQ_HEAD(, swdevt) swtailq = TAILQ_HEAD_INITIALIZER(swtailq);
180 static struct swdevt *swdevhd; /* Allocate from here next */
181 static int nswapdev; /* Number of swap devices */
182 int swap_pager_avail;
183 static int swdev_syscall_active = 0; /* serialize swap(on|off) */
184
185 static void swapdev_strategy(struct buf *, struct swdevt *sw);
186
187 #define SWM_FREE 0x02 /* free, period */
188 #define SWM_POP 0x04 /* pop out */
189
190 int swap_pager_full = 2; /* swap space exhaustion (task killing) */
191 static int swap_pager_almost_full = 1; /* swap space exhaustion (w/hysteresis)*/
192 static int nsw_rcount; /* free read buffers */
193 static int nsw_wcount_sync; /* limit write buffers / synchronous */
194 static int nsw_wcount_async; /* limit write buffers / asynchronous */
195 static int nsw_wcount_async_max;/* assigned maximum */
196 static int nsw_cluster_max; /* maximum VOP I/O allowed */
197
198 static struct swblock **swhash;
199 static int swhash_mask;
200 static struct mtx swhash_mtx;
201
202 static int swap_async_max = 4; /* maximum in-progress async I/O's */
203 static struct sx sw_alloc_sx;
204
205
206 SYSCTL_INT(_vm, OID_AUTO, swap_async_max,
207 CTLFLAG_RW, &swap_async_max, 0, "Maximum running async swap ops");
208
209 /*
210 * "named" and "unnamed" anon region objects. Try to reduce the overhead
211 * of searching a named list by hashing it just a little.
212 */
213
214 #define NOBJLISTS 8
215
216 #define NOBJLIST(handle) \
217 (&swap_pager_object_list[((int)(intptr_t)handle >> 4) & (NOBJLISTS-1)])
218
219 static struct mtx sw_alloc_mtx; /* protect list manipulation */
220 static struct pagerlst swap_pager_object_list[NOBJLISTS];
221 static uma_zone_t swap_zone;
222 static struct vm_object swap_zone_obj;
223
224 /*
225 * pagerops for OBJT_SWAP - "swap pager". Some ops are also global procedure
226 * calls hooked from other parts of the VM system and do not appear here.
227 * (see vm/swap_pager.h).
228 */
229 static vm_object_t
230 swap_pager_alloc(void *handle, vm_ooffset_t size,
231 vm_prot_t prot, vm_ooffset_t offset);
232 static void swap_pager_dealloc(vm_object_t object);
233 static int swap_pager_getpages(vm_object_t, vm_page_t *, int, int);
234 static void swap_pager_putpages(vm_object_t, vm_page_t *, int, boolean_t, int *);
235 static boolean_t
236 swap_pager_haspage(vm_object_t object, vm_pindex_t pindex, int *before, int *after);
237 static void swap_pager_init(void);
238 static void swap_pager_unswapped(vm_page_t);
239 static void swap_pager_swapoff(struct swdevt *sp, int *sw_used);
240
241 struct pagerops swappagerops = {
242 .pgo_init = swap_pager_init, /* early system initialization of pager */
243 .pgo_alloc = swap_pager_alloc, /* allocate an OBJT_SWAP object */
244 .pgo_dealloc = swap_pager_dealloc, /* deallocate an OBJT_SWAP object */
245 .pgo_getpages = swap_pager_getpages, /* pagein */
246 .pgo_putpages = swap_pager_putpages, /* pageout */
247 .pgo_haspage = swap_pager_haspage, /* get backing store status for page */
248 .pgo_pageunswapped = swap_pager_unswapped, /* remove swap related to page */
249 };
250
251 /*
252 * dmmax is in page-sized chunks with the new swap system. It was
253 * dev-bsized chunks in the old. dmmax is always a power of 2.
254 *
255 * swap_*() routines are externally accessible. swp_*() routines are
256 * internal.
257 */
258 static int dmmax;
259 static int nswap_lowat = 128; /* in pages, swap_pager_almost_full warn */
260 static int nswap_hiwat = 512; /* in pages, swap_pager_almost_full warn */
261
262 SYSCTL_INT(_vm, OID_AUTO, dmmax,
263 CTLFLAG_RD, &dmmax, 0, "Maximum size of a swap block");
264
265 static void swp_sizecheck(void);
266 static void swp_pager_async_iodone(struct buf *bp);
267 static int swapongeom(struct thread *, struct vnode *);
268 static int swaponvp(struct thread *, struct vnode *, u_long);
269
270 /*
271 * Swap bitmap functions
272 */
273 static void swp_pager_freeswapspace(daddr_t blk, int npages);
274 static daddr_t swp_pager_getswapspace(int npages);
275
276 /*
277 * Metadata functions
278 */
279 static struct swblock **swp_pager_hash(vm_object_t object, vm_pindex_t index);
280 static void swp_pager_meta_build(vm_object_t, vm_pindex_t, daddr_t);
281 static void swp_pager_meta_free(vm_object_t, vm_pindex_t, daddr_t);
282 static void swp_pager_meta_free_all(vm_object_t);
283 static daddr_t swp_pager_meta_ctl(vm_object_t, vm_pindex_t, int);
284
285 /*
286 * SWP_SIZECHECK() - update swap_pager_full indication
287 *
288 * update the swap_pager_almost_full indication and warn when we are
289 * about to run out of swap space, using lowat/hiwat hysteresis.
290 *
291 * Clear swap_pager_full ( task killing ) indication when lowat is met.
292 *
293 * No restrictions on call
294 * This routine may not block.
295 * This routine must be called at splvm()
296 */
297 static void
298 swp_sizecheck(void)
299 {
300
301 if (swap_pager_avail < nswap_lowat) {
302 if (swap_pager_almost_full == 0) {
303 printf("swap_pager: out of swap space\n");
304 swap_pager_almost_full = 1;
305 }
306 } else {
307 swap_pager_full = 0;
308 if (swap_pager_avail > nswap_hiwat)
309 swap_pager_almost_full = 0;
310 }
311 }
312
313 /*
314 * SWP_PAGER_HASH() - hash swap meta data
315 *
316 * This is an helper function which hashes the swapblk given
317 * the object and page index. It returns a pointer to a pointer
318 * to the object, or a pointer to a NULL pointer if it could not
319 * find a swapblk.
320 *
321 * This routine must be called at splvm().
322 */
323 static struct swblock **
324 swp_pager_hash(vm_object_t object, vm_pindex_t index)
325 {
326 struct swblock **pswap;
327 struct swblock *swap;
328
329 index &= ~(vm_pindex_t)SWAP_META_MASK;
330 pswap = &swhash[(index ^ (int)(intptr_t)object) & swhash_mask];
331 while ((swap = *pswap) != NULL) {
332 if (swap->swb_object == object &&
333 swap->swb_index == index
334 ) {
335 break;
336 }
337 pswap = &swap->swb_hnext;
338 }
339 return (pswap);
340 }
341
342 /*
343 * SWAP_PAGER_INIT() - initialize the swap pager!
344 *
345 * Expected to be started from system init. NOTE: This code is run
346 * before much else so be careful what you depend on. Most of the VM
347 * system has yet to be initialized at this point.
348 */
349 static void
350 swap_pager_init(void)
351 {
352 /*
353 * Initialize object lists
354 */
355 int i;
356
357 for (i = 0; i < NOBJLISTS; ++i)
358 TAILQ_INIT(&swap_pager_object_list[i]);
359 mtx_init(&sw_alloc_mtx, "swap_pager list", NULL, MTX_DEF);
360 mtx_init(&sw_dev_mtx, "swapdev", NULL, MTX_DEF);
361
362 /*
363 * Device Stripe, in PAGE_SIZE'd blocks
364 */
365 dmmax = SWB_NPAGES * 2;
366 }
367
368 /*
369 * SWAP_PAGER_SWAP_INIT() - swap pager initialization from pageout process
370 *
371 * Expected to be started from pageout process once, prior to entering
372 * its main loop.
373 */
374 void
375 swap_pager_swap_init(void)
376 {
377 int n, n2;
378
379 /*
380 * Number of in-transit swap bp operations. Don't
381 * exhaust the pbufs completely. Make sure we
382 * initialize workable values (0 will work for hysteresis
383 * but it isn't very efficient).
384 *
385 * The nsw_cluster_max is constrained by the bp->b_pages[]
386 * array (MAXPHYS/PAGE_SIZE) and our locally defined
387 * MAX_PAGEOUT_CLUSTER. Also be aware that swap ops are
388 * constrained by the swap device interleave stripe size.
389 *
390 * Currently we hardwire nsw_wcount_async to 4. This limit is
391 * designed to prevent other I/O from having high latencies due to
392 * our pageout I/O. The value 4 works well for one or two active swap
393 * devices but is probably a little low if you have more. Even so,
394 * a higher value would probably generate only a limited improvement
395 * with three or four active swap devices since the system does not
396 * typically have to pageout at extreme bandwidths. We will want
397 * at least 2 per swap devices, and 4 is a pretty good value if you
398 * have one NFS swap device due to the command/ack latency over NFS.
399 * So it all works out pretty well.
400 */
401 nsw_cluster_max = min((MAXPHYS/PAGE_SIZE), MAX_PAGEOUT_CLUSTER);
402
403 mtx_lock(&pbuf_mtx);
404 nsw_rcount = (nswbuf + 1) / 2;
405 nsw_wcount_sync = (nswbuf + 3) / 4;
406 nsw_wcount_async = 4;
407 nsw_wcount_async_max = nsw_wcount_async;
408 mtx_unlock(&pbuf_mtx);
409
410 /*
411 * Initialize our zone. Right now I'm just guessing on the number
412 * we need based on the number of pages in the system. Each swblock
413 * can hold 16 pages, so this is probably overkill. This reservation
414 * is typically limited to around 32MB by default.
415 */
416 n = cnt.v_page_count / 2;
417 if (maxswzone && n > maxswzone / sizeof(struct swblock))
418 n = maxswzone / sizeof(struct swblock);
419 n2 = n;
420 swap_zone = uma_zcreate("SWAPMETA", sizeof(struct swblock), NULL, NULL,
421 NULL, NULL, UMA_ALIGN_PTR, UMA_ZONE_NOFREE | UMA_ZONE_VM);
422 do {
423 if (uma_zone_set_obj(swap_zone, &swap_zone_obj, n))
424 break;
425 /*
426 * if the allocation failed, try a zone two thirds the
427 * size of the previous attempt.
428 */
429 n -= ((n + 2) / 3);
430 } while (n > 0);
431 if (swap_zone == NULL)
432 panic("failed to create swap_zone.");
433 if (n2 != n)
434 printf("Swap zone entries reduced from %d to %d.\n", n2, n);
435 n2 = n;
436
437 /*
438 * Initialize our meta-data hash table. The swapper does not need to
439 * be quite as efficient as the VM system, so we do not use an
440 * oversized hash table.
441 *
442 * n: size of hash table, must be power of 2
443 * swhash_mask: hash table index mask
444 */
445 for (n = 1; n < n2 / 8; n *= 2)
446 ;
447 swhash = malloc(sizeof(struct swblock *) * n, M_VMPGDATA, M_WAITOK | M_ZERO);
448 swhash_mask = n - 1;
449 mtx_init(&swhash_mtx, "swap_pager swhash", NULL, MTX_DEF);
450 }
451
452 /*
453 * SWAP_PAGER_ALLOC() - allocate a new OBJT_SWAP VM object and instantiate
454 * its metadata structures.
455 *
456 * This routine is called from the mmap and fork code to create a new
457 * OBJT_SWAP object. We do this by creating an OBJT_DEFAULT object
458 * and then converting it with swp_pager_meta_build().
459 *
460 * This routine may block in vm_object_allocate() and create a named
461 * object lookup race, so we must interlock. We must also run at
462 * splvm() for the object lookup to handle races with interrupts, but
463 * we do not have to maintain splvm() in between the lookup and the
464 * add because (I believe) it is not possible to attempt to create
465 * a new swap object w/handle when a default object with that handle
466 * already exists.
467 *
468 * MPSAFE
469 */
470 static vm_object_t
471 swap_pager_alloc(void *handle, vm_ooffset_t size, vm_prot_t prot,
472 vm_ooffset_t offset)
473 {
474 vm_object_t object;
475 vm_pindex_t pindex;
476
477 pindex = OFF_TO_IDX(offset + PAGE_MASK + size);
478
479 if (handle) {
480 mtx_lock(&Giant);
481 /*
482 * Reference existing named region or allocate new one. There
483 * should not be a race here against swp_pager_meta_build()
484 * as called from vm_page_remove() in regards to the lookup
485 * of the handle.
486 */
487 sx_xlock(&sw_alloc_sx);
488 object = vm_pager_object_lookup(NOBJLIST(handle), handle);
489
490 if (object != NULL) {
491 vm_object_reference(object);
492 } else {
493 object = vm_object_allocate(OBJT_DEFAULT, pindex);
494 object->handle = handle;
495
496 VM_OBJECT_LOCK(object);
497 swp_pager_meta_build(object, 0, SWAPBLK_NONE);
498 VM_OBJECT_UNLOCK(object);
499 }
500 sx_xunlock(&sw_alloc_sx);
501 mtx_unlock(&Giant);
502 } else {
503 object = vm_object_allocate(OBJT_DEFAULT, pindex);
504
505 VM_OBJECT_LOCK(object);
506 swp_pager_meta_build(object, 0, SWAPBLK_NONE);
507 VM_OBJECT_UNLOCK(object);
508 }
509 return (object);
510 }
511
512 /*
513 * SWAP_PAGER_DEALLOC() - remove swap metadata from object
514 *
515 * The swap backing for the object is destroyed. The code is
516 * designed such that we can reinstantiate it later, but this
517 * routine is typically called only when the entire object is
518 * about to be destroyed.
519 *
520 * This routine may block, but no longer does.
521 *
522 * The object must be locked or unreferenceable.
523 */
524 static void
525 swap_pager_dealloc(vm_object_t object)
526 {
527 int s;
528
529 /*
530 * Remove from list right away so lookups will fail if we block for
531 * pageout completion.
532 */
533 if (object->handle != NULL) {
534 mtx_lock(&sw_alloc_mtx);
535 TAILQ_REMOVE(NOBJLIST(object->handle), object, pager_object_list);
536 mtx_unlock(&sw_alloc_mtx);
537 }
538
539 VM_OBJECT_LOCK_ASSERT(object, MA_OWNED);
540 vm_object_pip_wait(object, "swpdea");
541
542 /*
543 * Free all remaining metadata. We only bother to free it from
544 * the swap meta data. We do not attempt to free swapblk's still
545 * associated with vm_page_t's for this object. We do not care
546 * if paging is still in progress on some objects.
547 */
548 s = splvm();
549 swp_pager_meta_free_all(object);
550 splx(s);
551 }
552
553 /************************************************************************
554 * SWAP PAGER BITMAP ROUTINES *
555 ************************************************************************/
556
557 /*
558 * SWP_PAGER_GETSWAPSPACE() - allocate raw swap space
559 *
560 * Allocate swap for the requested number of pages. The starting
561 * swap block number (a page index) is returned or SWAPBLK_NONE
562 * if the allocation failed.
563 *
564 * Also has the side effect of advising that somebody made a mistake
565 * when they configured swap and didn't configure enough.
566 *
567 * Must be called at splvm() to avoid races with bitmap frees from
568 * vm_page_remove() aka swap_pager_page_removed().
569 *
570 * This routine may not block
571 * This routine must be called at splvm().
572 *
573 * We allocate in round-robin fashion from the configured devices.
574 */
575 static daddr_t
576 swp_pager_getswapspace(int npages)
577 {
578 daddr_t blk;
579 struct swdevt *sp;
580 int i;
581
582 blk = SWAPBLK_NONE;
583 mtx_lock(&sw_dev_mtx);
584 sp = swdevhd;
585 for (i = 0; i < nswapdev; i++) {
586 if (sp == NULL)
587 sp = TAILQ_FIRST(&swtailq);
588 if (!(sp->sw_flags & SW_CLOSING)) {
589 blk = blist_alloc(sp->sw_blist, npages);
590 if (blk != SWAPBLK_NONE) {
591 blk += sp->sw_first;
592 sp->sw_used += npages;
593 swap_pager_avail -= npages;
594 swp_sizecheck();
595 swdevhd = TAILQ_NEXT(sp, sw_list);
596 goto done;
597 }
598 }
599 sp = TAILQ_NEXT(sp, sw_list);
600 }
601 if (swap_pager_full != 2) {
602 printf("swap_pager_getswapspace(%d): failed\n", npages);
603 swap_pager_full = 2;
604 swap_pager_almost_full = 1;
605 }
606 swdevhd = NULL;
607 done:
608 mtx_unlock(&sw_dev_mtx);
609 return (blk);
610 }
611
612 static struct swdevt *
613 swp_pager_find_dev(daddr_t blk)
614 {
615 struct swdevt *sp;
616
617 mtx_lock(&sw_dev_mtx);
618 TAILQ_FOREACH(sp, &swtailq, sw_list) {
619 if (blk >= sp->sw_first && blk < sp->sw_end) {
620 mtx_unlock(&sw_dev_mtx);
621 return (sp);
622 }
623 }
624 panic("Swapdev not found");
625 }
626
627 static void
628 swp_pager_strategy(struct buf *bp)
629 {
630 struct swdevt *sp;
631
632 mtx_lock(&sw_dev_mtx);
633 TAILQ_FOREACH(sp, &swtailq, sw_list) {
634 if (bp->b_blkno >= sp->sw_first && bp->b_blkno < sp->sw_end) {
635 mtx_unlock(&sw_dev_mtx);
636 sp->sw_strategy(bp, sp);
637 return;
638 }
639 }
640 panic("Swapdev not found");
641 }
642
643
644 /*
645 * SWP_PAGER_FREESWAPSPACE() - free raw swap space
646 *
647 * This routine returns the specified swap blocks back to the bitmap.
648 *
649 * Note: This routine may not block (it could in the old swap code),
650 * and through the use of the new blist routines it does not block.
651 *
652 * We must be called at splvm() to avoid races with bitmap frees from
653 * vm_page_remove() aka swap_pager_page_removed().
654 *
655 * This routine may not block
656 * This routine must be called at splvm().
657 */
658 static void
659 swp_pager_freeswapspace(daddr_t blk, int npages)
660 {
661 struct swdevt *sp;
662
663 mtx_lock(&sw_dev_mtx);
664 TAILQ_FOREACH(sp, &swtailq, sw_list) {
665 if (blk >= sp->sw_first && blk < sp->sw_end) {
666 sp->sw_used -= npages;
667 /*
668 * If we are attempting to stop swapping on
669 * this device, we don't want to mark any
670 * blocks free lest they be reused.
671 */
672 if ((sp->sw_flags & SW_CLOSING) == 0) {
673 blist_free(sp->sw_blist, blk - sp->sw_first,
674 npages);
675 swap_pager_avail += npages;
676 swp_sizecheck();
677 }
678 mtx_unlock(&sw_dev_mtx);
679 return;
680 }
681 }
682 panic("Swapdev not found");
683 }
684
685 /*
686 * SWAP_PAGER_FREESPACE() - frees swap blocks associated with a page
687 * range within an object.
688 *
689 * This is a globally accessible routine.
690 *
691 * This routine removes swapblk assignments from swap metadata.
692 *
693 * The external callers of this routine typically have already destroyed
694 * or renamed vm_page_t's associated with this range in the object so
695 * we should be ok.
696 *
697 * This routine may be called at any spl. We up our spl to splvm temporarily
698 * in order to perform the metadata removal.
699 */
700 void
701 swap_pager_freespace(vm_object_t object, vm_pindex_t start, vm_size_t size)
702 {
703 int s = splvm();
704
705 VM_OBJECT_LOCK_ASSERT(object, MA_OWNED);
706 swp_pager_meta_free(object, start, size);
707 splx(s);
708 }
709
710 /*
711 * SWAP_PAGER_RESERVE() - reserve swap blocks in object
712 *
713 * Assigns swap blocks to the specified range within the object. The
714 * swap blocks are not zerod. Any previous swap assignment is destroyed.
715 *
716 * Returns 0 on success, -1 on failure.
717 */
718 int
719 swap_pager_reserve(vm_object_t object, vm_pindex_t start, vm_size_t size)
720 {
721 int s;
722 int n = 0;
723 daddr_t blk = SWAPBLK_NONE;
724 vm_pindex_t beg = start; /* save start index */
725
726 s = splvm();
727 VM_OBJECT_LOCK(object);
728 while (size) {
729 if (n == 0) {
730 n = BLIST_MAX_ALLOC;
731 while ((blk = swp_pager_getswapspace(n)) == SWAPBLK_NONE) {
732 n >>= 1;
733 if (n == 0) {
734 swp_pager_meta_free(object, beg, start - beg);
735 VM_OBJECT_UNLOCK(object);
736 splx(s);
737 return (-1);
738 }
739 }
740 }
741 swp_pager_meta_build(object, start, blk);
742 --size;
743 ++start;
744 ++blk;
745 --n;
746 }
747 swp_pager_meta_free(object, start, n);
748 VM_OBJECT_UNLOCK(object);
749 splx(s);
750 return (0);
751 }
752
753 /*
754 * SWAP_PAGER_COPY() - copy blocks from source pager to destination pager
755 * and destroy the source.
756 *
757 * Copy any valid swapblks from the source to the destination. In
758 * cases where both the source and destination have a valid swapblk,
759 * we keep the destination's.
760 *
761 * This routine is allowed to block. It may block allocating metadata
762 * indirectly through swp_pager_meta_build() or if paging is still in
763 * progress on the source.
764 *
765 * This routine can be called at any spl
766 *
767 * XXX vm_page_collapse() kinda expects us not to block because we
768 * supposedly do not need to allocate memory, but for the moment we
769 * *may* have to get a little memory from the zone allocator, but
770 * it is taken from the interrupt memory. We should be ok.
771 *
772 * The source object contains no vm_page_t's (which is just as well)
773 *
774 * The source object is of type OBJT_SWAP.
775 *
776 * The source and destination objects must be locked or
777 * inaccessible (XXX are they ?)
778 */
779 void
780 swap_pager_copy(vm_object_t srcobject, vm_object_t dstobject,
781 vm_pindex_t offset, int destroysource)
782 {
783 vm_pindex_t i;
784 int s;
785
786 VM_OBJECT_LOCK_ASSERT(srcobject, MA_OWNED);
787 VM_OBJECT_LOCK_ASSERT(dstobject, MA_OWNED);
788
789 s = splvm();
790 /*
791 * If destroysource is set, we remove the source object from the
792 * swap_pager internal queue now.
793 */
794 if (destroysource) {
795 if (srcobject->handle != NULL) {
796 mtx_lock(&sw_alloc_mtx);
797 TAILQ_REMOVE(
798 NOBJLIST(srcobject->handle),
799 srcobject,
800 pager_object_list
801 );
802 mtx_unlock(&sw_alloc_mtx);
803 }
804 }
805
806 /*
807 * transfer source to destination.
808 */
809 for (i = 0; i < dstobject->size; ++i) {
810 daddr_t dstaddr;
811
812 /*
813 * Locate (without changing) the swapblk on the destination,
814 * unless it is invalid in which case free it silently, or
815 * if the destination is a resident page, in which case the
816 * source is thrown away.
817 */
818 dstaddr = swp_pager_meta_ctl(dstobject, i, 0);
819
820 if (dstaddr == SWAPBLK_NONE) {
821 /*
822 * Destination has no swapblk and is not resident,
823 * copy source.
824 */
825 daddr_t srcaddr;
826
827 srcaddr = swp_pager_meta_ctl(
828 srcobject,
829 i + offset,
830 SWM_POP
831 );
832
833 if (srcaddr != SWAPBLK_NONE) {
834 /*
835 * swp_pager_meta_build() can sleep.
836 */
837 vm_object_pip_add(srcobject, 1);
838 VM_OBJECT_UNLOCK(srcobject);
839 vm_object_pip_add(dstobject, 1);
840 swp_pager_meta_build(dstobject, i, srcaddr);
841 vm_object_pip_wakeup(dstobject);
842 VM_OBJECT_LOCK(srcobject);
843 vm_object_pip_wakeup(srcobject);
844 }
845 } else {
846 /*
847 * Destination has valid swapblk or it is represented
848 * by a resident page. We destroy the sourceblock.
849 */
850
851 swp_pager_meta_ctl(srcobject, i + offset, SWM_FREE);
852 }
853 }
854
855 /*
856 * Free left over swap blocks in source.
857 *
858 * We have to revert the type to OBJT_DEFAULT so we do not accidently
859 * double-remove the object from the swap queues.
860 */
861 if (destroysource) {
862 swp_pager_meta_free_all(srcobject);
863 /*
864 * Reverting the type is not necessary, the caller is going
865 * to destroy srcobject directly, but I'm doing it here
866 * for consistency since we've removed the object from its
867 * queues.
868 */
869 srcobject->type = OBJT_DEFAULT;
870 }
871 splx(s);
872 }
873
874 /*
875 * SWAP_PAGER_HASPAGE() - determine if we have good backing store for
876 * the requested page.
877 *
878 * We determine whether good backing store exists for the requested
879 * page and return TRUE if it does, FALSE if it doesn't.
880 *
881 * If TRUE, we also try to determine how much valid, contiguous backing
882 * store exists before and after the requested page within a reasonable
883 * distance. We do not try to restrict it to the swap device stripe
884 * (that is handled in getpages/putpages). It probably isn't worth
885 * doing here.
886 */
887 static boolean_t
888 swap_pager_haspage(vm_object_t object, vm_pindex_t pindex, int *before, int *after)
889 {
890 daddr_t blk0;
891 int s;
892
893 VM_OBJECT_LOCK_ASSERT(object, MA_OWNED);
894 /*
895 * do we have good backing store at the requested index ?
896 */
897 s = splvm();
898 blk0 = swp_pager_meta_ctl(object, pindex, 0);
899
900 if (blk0 == SWAPBLK_NONE) {
901 splx(s);
902 if (before)
903 *before = 0;
904 if (after)
905 *after = 0;
906 return (FALSE);
907 }
908
909 /*
910 * find backwards-looking contiguous good backing store
911 */
912 if (before != NULL) {
913 int i;
914
915 for (i = 1; i < (SWB_NPAGES/2); ++i) {
916 daddr_t blk;
917
918 if (i > pindex)
919 break;
920 blk = swp_pager_meta_ctl(object, pindex - i, 0);
921 if (blk != blk0 - i)
922 break;
923 }
924 *before = (i - 1);
925 }
926
927 /*
928 * find forward-looking contiguous good backing store
929 */
930 if (after != NULL) {
931 int i;
932
933 for (i = 1; i < (SWB_NPAGES/2); ++i) {
934 daddr_t blk;
935
936 blk = swp_pager_meta_ctl(object, pindex + i, 0);
937 if (blk != blk0 + i)
938 break;
939 }
940 *after = (i - 1);
941 }
942 splx(s);
943 return (TRUE);
944 }
945
946 /*
947 * SWAP_PAGER_PAGE_UNSWAPPED() - remove swap backing store related to page
948 *
949 * This removes any associated swap backing store, whether valid or
950 * not, from the page.
951 *
952 * This routine is typically called when a page is made dirty, at
953 * which point any associated swap can be freed. MADV_FREE also
954 * calls us in a special-case situation
955 *
956 * NOTE!!! If the page is clean and the swap was valid, the caller
957 * should make the page dirty before calling this routine. This routine
958 * does NOT change the m->dirty status of the page. Also: MADV_FREE
959 * depends on it.
960 *
961 * This routine may not block
962 * This routine must be called at splvm()
963 */
964 static void
965 swap_pager_unswapped(vm_page_t m)
966 {
967
968 VM_OBJECT_LOCK_ASSERT(m->object, MA_OWNED);
969 swp_pager_meta_ctl(m->object, m->pindex, SWM_FREE);
970 }
971
972 /*
973 * SWAP_PAGER_GETPAGES() - bring pages in from swap
974 *
975 * Attempt to retrieve (m, count) pages from backing store, but make
976 * sure we retrieve at least m[reqpage]. We try to load in as large
977 * a chunk surrounding m[reqpage] as is contiguous in swap and which
978 * belongs to the same object.
979 *
980 * The code is designed for asynchronous operation and
981 * immediate-notification of 'reqpage' but tends not to be
982 * used that way. Please do not optimize-out this algorithmic
983 * feature, I intend to improve on it in the future.
984 *
985 * The parent has a single vm_object_pip_add() reference prior to
986 * calling us and we should return with the same.
987 *
988 * The parent has BUSY'd the pages. We should return with 'm'
989 * left busy, but the others adjusted.
990 */
991 static int
992 swap_pager_getpages(vm_object_t object, vm_page_t *m, int count, int reqpage)
993 {
994 struct buf *bp;
995 vm_page_t mreq;
996 int s;
997 int i;
998 int j;
999 daddr_t blk;
1000
1001 mreq = m[reqpage];
1002
1003 KASSERT(mreq->object == object,
1004 ("swap_pager_getpages: object mismatch %p/%p",
1005 object, mreq->object));
1006
1007 /*
1008 * Calculate range to retrieve. The pages have already been assigned
1009 * their swapblks. We require a *contiguous* range but we know it to
1010 * not span devices. If we do not supply it, bad things
1011 * happen. Note that blk, iblk & jblk can be SWAPBLK_NONE, but the
1012 * loops are set up such that the case(s) are handled implicitly.
1013 *
1014 * The swp_*() calls must be made at splvm(). vm_page_free() does
1015 * not need to be, but it will go a little faster if it is.
1016 */
1017 s = splvm();
1018 blk = swp_pager_meta_ctl(mreq->object, mreq->pindex, 0);
1019
1020 for (i = reqpage - 1; i >= 0; --i) {
1021 daddr_t iblk;
1022
1023 iblk = swp_pager_meta_ctl(m[i]->object, m[i]->pindex, 0);
1024 if (blk != iblk + (reqpage - i))
1025 break;
1026 }
1027 ++i;
1028
1029 for (j = reqpage + 1; j < count; ++j) {
1030 daddr_t jblk;
1031
1032 jblk = swp_pager_meta_ctl(m[j]->object, m[j]->pindex, 0);
1033 if (blk != jblk - (j - reqpage))
1034 break;
1035 }
1036
1037 /*
1038 * free pages outside our collection range. Note: we never free
1039 * mreq, it must remain busy throughout.
1040 */
1041 vm_page_lock_queues();
1042 {
1043 int k;
1044
1045 for (k = 0; k < i; ++k)
1046 vm_page_free(m[k]);
1047 for (k = j; k < count; ++k)
1048 vm_page_free(m[k]);
1049 }
1050 vm_page_unlock_queues();
1051 splx(s);
1052
1053
1054 /*
1055 * Return VM_PAGER_FAIL if we have nothing to do. Return mreq
1056 * still busy, but the others unbusied.
1057 */
1058 if (blk == SWAPBLK_NONE)
1059 return (VM_PAGER_FAIL);
1060
1061 /*
1062 * Getpbuf() can sleep.
1063 */
1064 VM_OBJECT_UNLOCK(object);
1065 /*
1066 * Get a swap buffer header to perform the IO
1067 */
1068 bp = getpbuf(&nsw_rcount);
1069 bp->b_flags |= B_PAGING;
1070
1071 /*
1072 * map our page(s) into kva for input
1073 */
1074 pmap_qenter((vm_offset_t)bp->b_data, m + i, j - i);
1075
1076 bp->b_iocmd = BIO_READ;
1077 bp->b_iodone = swp_pager_async_iodone;
1078 bp->b_rcred = crhold(thread0.td_ucred);
1079 bp->b_wcred = crhold(thread0.td_ucred);
1080 bp->b_blkno = blk - (reqpage - i);
1081 bp->b_bcount = PAGE_SIZE * (j - i);
1082 bp->b_bufsize = PAGE_SIZE * (j - i);
1083 bp->b_pager.pg_reqpage = reqpage - i;
1084
1085 VM_OBJECT_LOCK(object);
1086 vm_page_lock_queues();
1087 {
1088 int k;
1089
1090 for (k = i; k < j; ++k) {
1091 bp->b_pages[k - i] = m[k];
1092 vm_page_flag_set(m[k], PG_SWAPINPROG);
1093 }
1094 }
1095 vm_page_unlock_queues();
1096 VM_OBJECT_UNLOCK(object);
1097 bp->b_npages = j - i;
1098
1099 cnt.v_swapin++;
1100 cnt.v_swappgsin += bp->b_npages;
1101
1102 /*
1103 * We still hold the lock on mreq, and our automatic completion routine
1104 * does not remove it.
1105 */
1106 VM_OBJECT_LOCK(mreq->object);
1107 vm_object_pip_add(mreq->object, bp->b_npages);
1108 VM_OBJECT_UNLOCK(mreq->object);
1109
1110 /*
1111 * perform the I/O. NOTE!!! bp cannot be considered valid after
1112 * this point because we automatically release it on completion.
1113 * Instead, we look at the one page we are interested in which we
1114 * still hold a lock on even through the I/O completion.
1115 *
1116 * The other pages in our m[] array are also released on completion,
1117 * so we cannot assume they are valid anymore either.
1118 *
1119 * NOTE: b_blkno is destroyed by the call to swapdev_strategy
1120 */
1121 BUF_KERNPROC(bp);
1122 swp_pager_strategy(bp);
1123
1124 /*
1125 * wait for the page we want to complete. PG_SWAPINPROG is always
1126 * cleared on completion. If an I/O error occurs, SWAPBLK_NONE
1127 * is set in the meta-data.
1128 */
1129 s = splvm();
1130 vm_page_lock_queues();
1131 while ((mreq->flags & PG_SWAPINPROG) != 0) {
1132 vm_page_flag_set(mreq, PG_WANTED | PG_REFERENCED);
1133 cnt.v_intrans++;
1134 if (msleep(mreq, &vm_page_queue_mtx, PSWP, "swread", hz*20)) {
1135 printf(
1136 "swap_pager: indefinite wait buffer: device: %s, blkno: %jd, size: %ld\n",
1137 bp->b_dev == NULL ? "[NULL]" : devtoname(bp->b_dev),
1138 (intmax_t)bp->b_blkno, bp->b_bcount);
1139 }
1140 }
1141 vm_page_unlock_queues();
1142 splx(s);
1143
1144 VM_OBJECT_LOCK(mreq->object);
1145 /*
1146 * mreq is left busied after completion, but all the other pages
1147 * are freed. If we had an unrecoverable read error the page will
1148 * not be valid.
1149 */
1150 if (mreq->valid != VM_PAGE_BITS_ALL) {
1151 return (VM_PAGER_ERROR);
1152 } else {
1153 return (VM_PAGER_OK);
1154 }
1155
1156 /*
1157 * A final note: in a low swap situation, we cannot deallocate swap
1158 * and mark a page dirty here because the caller is likely to mark
1159 * the page clean when we return, causing the page to possibly revert
1160 * to all-zero's later.
1161 */
1162 }
1163
1164 /*
1165 * swap_pager_putpages:
1166 *
1167 * Assign swap (if necessary) and initiate I/O on the specified pages.
1168 *
1169 * We support both OBJT_DEFAULT and OBJT_SWAP objects. DEFAULT objects
1170 * are automatically converted to SWAP objects.
1171 *
1172 * In a low memory situation we may block in VOP_STRATEGY(), but the new
1173 * vm_page reservation system coupled with properly written VFS devices
1174 * should ensure that no low-memory deadlock occurs. This is an area
1175 * which needs work.
1176 *
1177 * The parent has N vm_object_pip_add() references prior to
1178 * calling us and will remove references for rtvals[] that are
1179 * not set to VM_PAGER_PEND. We need to remove the rest on I/O
1180 * completion.
1181 *
1182 * The parent has soft-busy'd the pages it passes us and will unbusy
1183 * those whos rtvals[] entry is not set to VM_PAGER_PEND on return.
1184 * We need to unbusy the rest on I/O completion.
1185 */
1186 void
1187 swap_pager_putpages(vm_object_t object, vm_page_t *m, int count,
1188 boolean_t sync, int *rtvals)
1189 {
1190 int i;
1191 int n = 0;
1192
1193 GIANT_REQUIRED;
1194 if (count && m[0]->object != object) {
1195 panic("swap_pager_getpages: object mismatch %p/%p",
1196 object,
1197 m[0]->object
1198 );
1199 }
1200
1201 /*
1202 * Step 1
1203 *
1204 * Turn object into OBJT_SWAP
1205 * check for bogus sysops
1206 * force sync if not pageout process
1207 */
1208 if (object->type != OBJT_SWAP)
1209 swp_pager_meta_build(object, 0, SWAPBLK_NONE);
1210 VM_OBJECT_UNLOCK(object);
1211
1212 if (curproc != pageproc)
1213 sync = TRUE;
1214
1215 /*
1216 * Step 2
1217 *
1218 * Update nsw parameters from swap_async_max sysctl values.
1219 * Do not let the sysop crash the machine with bogus numbers.
1220 */
1221 mtx_lock(&pbuf_mtx);
1222 if (swap_async_max != nsw_wcount_async_max) {
1223 int n;
1224 int s;
1225
1226 /*
1227 * limit range
1228 */
1229 if ((n = swap_async_max) > nswbuf / 2)
1230 n = nswbuf / 2;
1231 if (n < 1)
1232 n = 1;
1233 swap_async_max = n;
1234
1235 /*
1236 * Adjust difference ( if possible ). If the current async
1237 * count is too low, we may not be able to make the adjustment
1238 * at this time.
1239 */
1240 s = splvm();
1241 n -= nsw_wcount_async_max;
1242 if (nsw_wcount_async + n >= 0) {
1243 nsw_wcount_async += n;
1244 nsw_wcount_async_max += n;
1245 wakeup(&nsw_wcount_async);
1246 }
1247 splx(s);
1248 }
1249 mtx_unlock(&pbuf_mtx);
1250
1251 /*
1252 * Step 3
1253 *
1254 * Assign swap blocks and issue I/O. We reallocate swap on the fly.
1255 * The page is left dirty until the pageout operation completes
1256 * successfully.
1257 */
1258 for (i = 0; i < count; i += n) {
1259 int s;
1260 int j;
1261 struct buf *bp;
1262 daddr_t blk;
1263
1264 /*
1265 * Maximum I/O size is limited by a number of factors.
1266 */
1267 n = min(BLIST_MAX_ALLOC, count - i);
1268 n = min(n, nsw_cluster_max);
1269
1270 s = splvm();
1271
1272 /*
1273 * Get biggest block of swap we can. If we fail, fall
1274 * back and try to allocate a smaller block. Don't go
1275 * overboard trying to allocate space if it would overly
1276 * fragment swap.
1277 */
1278 while (
1279 (blk = swp_pager_getswapspace(n)) == SWAPBLK_NONE &&
1280 n > 4
1281 ) {
1282 n >>= 1;
1283 }
1284 if (blk == SWAPBLK_NONE) {
1285 for (j = 0; j < n; ++j)
1286 rtvals[i+j] = VM_PAGER_FAIL;
1287 splx(s);
1288 continue;
1289 }
1290
1291 /*
1292 * All I/O parameters have been satisfied, build the I/O
1293 * request and assign the swap space.
1294 */
1295 if (sync == TRUE) {
1296 bp = getpbuf(&nsw_wcount_sync);
1297 } else {
1298 bp = getpbuf(&nsw_wcount_async);
1299 bp->b_flags = B_ASYNC;
1300 }
1301 bp->b_flags |= B_PAGING;
1302 bp->b_iocmd = BIO_WRITE;
1303
1304 pmap_qenter((vm_offset_t)bp->b_data, &m[i], n);
1305
1306 bp->b_rcred = crhold(thread0.td_ucred);
1307 bp->b_wcred = crhold(thread0.td_ucred);
1308 bp->b_bcount = PAGE_SIZE * n;
1309 bp->b_bufsize = PAGE_SIZE * n;
1310 bp->b_blkno = blk;
1311
1312 VM_OBJECT_LOCK(object);
1313 for (j = 0; j < n; ++j) {
1314 vm_page_t mreq = m[i+j];
1315
1316 swp_pager_meta_build(
1317 mreq->object,
1318 mreq->pindex,
1319 blk + j
1320 );
1321 vm_page_dirty(mreq);
1322 rtvals[i+j] = VM_PAGER_OK;
1323
1324 vm_page_lock_queues();
1325 vm_page_flag_set(mreq, PG_SWAPINPROG);
1326 vm_page_unlock_queues();
1327 bp->b_pages[j] = mreq;
1328 }
1329 VM_OBJECT_UNLOCK(object);
1330 bp->b_npages = n;
1331 /*
1332 * Must set dirty range for NFS to work.
1333 */
1334 bp->b_dirtyoff = 0;
1335 bp->b_dirtyend = bp->b_bcount;
1336
1337 cnt.v_swapout++;
1338 cnt.v_swappgsout += bp->b_npages;
1339
1340 splx(s);
1341
1342 /*
1343 * asynchronous
1344 *
1345 * NOTE: b_blkno is destroyed by the call to swapdev_strategy
1346 */
1347 if (sync == FALSE) {
1348 bp->b_iodone = swp_pager_async_iodone;
1349 BUF_KERNPROC(bp);
1350 swp_pager_strategy(bp);
1351
1352 for (j = 0; j < n; ++j)
1353 rtvals[i+j] = VM_PAGER_PEND;
1354 /* restart outter loop */
1355 continue;
1356 }
1357
1358 /*
1359 * synchronous
1360 *
1361 * NOTE: b_blkno is destroyed by the call to swapdev_strategy
1362 */
1363 bp->b_iodone = bdone;
1364 swp_pager_strategy(bp);
1365
1366 /*
1367 * Wait for the sync I/O to complete, then update rtvals.
1368 * We just set the rtvals[] to VM_PAGER_PEND so we can call
1369 * our async completion routine at the end, thus avoiding a
1370 * double-free.
1371 */
1372 s = splbio();
1373 bwait(bp, PVM, "swwrt");
1374 for (j = 0; j < n; ++j)
1375 rtvals[i+j] = VM_PAGER_PEND;
1376 /*
1377 * Now that we are through with the bp, we can call the
1378 * normal async completion, which frees everything up.
1379 */
1380 swp_pager_async_iodone(bp);
1381 splx(s);
1382 }
1383 VM_OBJECT_LOCK(object);
1384 }
1385
1386 /*
1387 * swp_pager_async_iodone:
1388 *
1389 * Completion routine for asynchronous reads and writes from/to swap.
1390 * Also called manually by synchronous code to finish up a bp.
1391 *
1392 * For READ operations, the pages are PG_BUSY'd. For WRITE operations,
1393 * the pages are vm_page_t->busy'd. For READ operations, we PG_BUSY
1394 * unbusy all pages except the 'main' request page. For WRITE
1395 * operations, we vm_page_t->busy'd unbusy all pages ( we can do this
1396 * because we marked them all VM_PAGER_PEND on return from putpages ).
1397 *
1398 * This routine may not block.
1399 * This routine is called at splbio() or better
1400 *
1401 * We up ourselves to splvm() as required for various vm_page related
1402 * calls.
1403 */
1404 static void
1405 swp_pager_async_iodone(struct buf *bp)
1406 {
1407 int s;
1408 int i;
1409 vm_object_t object = NULL;
1410
1411 bp->b_flags |= B_DONE;
1412
1413 /*
1414 * report error
1415 */
1416 if (bp->b_ioflags & BIO_ERROR) {
1417 printf(
1418 "swap_pager: I/O error - %s failed; blkno %ld,"
1419 "size %ld, error %d\n",
1420 ((bp->b_iocmd == BIO_READ) ? "pagein" : "pageout"),
1421 (long)bp->b_blkno,
1422 (long)bp->b_bcount,
1423 bp->b_error
1424 );
1425 }
1426
1427 /*
1428 * set object, raise to splvm().
1429 */
1430 s = splvm();
1431
1432 /*
1433 * remove the mapping for kernel virtual
1434 */
1435 pmap_qremove((vm_offset_t)bp->b_data, bp->b_npages);
1436
1437 if (bp->b_npages) {
1438 object = bp->b_pages[0]->object;
1439 VM_OBJECT_LOCK(object);
1440 }
1441 vm_page_lock_queues();
1442 /*
1443 * cleanup pages. If an error occurs writing to swap, we are in
1444 * very serious trouble. If it happens to be a disk error, though,
1445 * we may be able to recover by reassigning the swap later on. So
1446 * in this case we remove the m->swapblk assignment for the page
1447 * but do not free it in the rlist. The errornous block(s) are thus
1448 * never reallocated as swap. Redirty the page and continue.
1449 */
1450 for (i = 0; i < bp->b_npages; ++i) {
1451 vm_page_t m = bp->b_pages[i];
1452
1453 vm_page_flag_clear(m, PG_SWAPINPROG);
1454
1455 if (bp->b_ioflags & BIO_ERROR) {
1456 /*
1457 * If an error occurs I'd love to throw the swapblk
1458 * away without freeing it back to swapspace, so it
1459 * can never be used again. But I can't from an
1460 * interrupt.
1461 */
1462 if (bp->b_iocmd == BIO_READ) {
1463 /*
1464 * When reading, reqpage needs to stay
1465 * locked for the parent, but all other
1466 * pages can be freed. We still want to
1467 * wakeup the parent waiting on the page,
1468 * though. ( also: pg_reqpage can be -1 and
1469 * not match anything ).
1470 *
1471 * We have to wake specifically requested pages
1472 * up too because we cleared PG_SWAPINPROG and
1473 * someone may be waiting for that.
1474 *
1475 * NOTE: for reads, m->dirty will probably
1476 * be overridden by the original caller of
1477 * getpages so don't play cute tricks here.
1478 *
1479 * XXX IT IS NOT LEGAL TO FREE THE PAGE HERE
1480 * AS THIS MESSES WITH object->memq, and it is
1481 * not legal to mess with object->memq from an
1482 * interrupt.
1483 */
1484 m->valid = 0;
1485 if (i != bp->b_pager.pg_reqpage)
1486 vm_page_free(m);
1487 else
1488 vm_page_flash(m);
1489 /*
1490 * If i == bp->b_pager.pg_reqpage, do not wake
1491 * the page up. The caller needs to.
1492 */
1493 } else {
1494 /*
1495 * If a write error occurs, reactivate page
1496 * so it doesn't clog the inactive list,
1497 * then finish the I/O.
1498 */
1499 vm_page_dirty(m);
1500 vm_page_activate(m);
1501 vm_page_io_finish(m);
1502 }
1503 } else if (bp->b_iocmd == BIO_READ) {
1504 /*
1505 * For read success, clear dirty bits. Nobody should
1506 * have this page mapped but don't take any chances,
1507 * make sure the pmap modify bits are also cleared.
1508 *
1509 * NOTE: for reads, m->dirty will probably be
1510 * overridden by the original caller of getpages so
1511 * we cannot set them in order to free the underlying
1512 * swap in a low-swap situation. I don't think we'd
1513 * want to do that anyway, but it was an optimization
1514 * that existed in the old swapper for a time before
1515 * it got ripped out due to precisely this problem.
1516 *
1517 * If not the requested page then deactivate it.
1518 *
1519 * Note that the requested page, reqpage, is left
1520 * busied, but we still have to wake it up. The
1521 * other pages are released (unbusied) by
1522 * vm_page_wakeup(). We do not set reqpage's
1523 * valid bits here, it is up to the caller.
1524 */
1525 pmap_clear_modify(m);
1526 m->valid = VM_PAGE_BITS_ALL;
1527 vm_page_undirty(m);
1528
1529 /*
1530 * We have to wake specifically requested pages
1531 * up too because we cleared PG_SWAPINPROG and
1532 * could be waiting for it in getpages. However,
1533 * be sure to not unbusy getpages specifically
1534 * requested page - getpages expects it to be
1535 * left busy.
1536 */
1537 if (i != bp->b_pager.pg_reqpage) {
1538 vm_page_deactivate(m);
1539 vm_page_wakeup(m);
1540 } else {
1541 vm_page_flash(m);
1542 }
1543 } else {
1544 /*
1545 * For write success, clear the modify and dirty
1546 * status, then finish the I/O ( which decrements the
1547 * busy count and possibly wakes waiter's up ).
1548 */
1549 pmap_clear_modify(m);
1550 vm_page_undirty(m);
1551 vm_page_io_finish(m);
1552 if (vm_page_count_severe())
1553 vm_page_try_to_cache(m);
1554 }
1555 }
1556 vm_page_unlock_queues();
1557
1558 /*
1559 * adjust pip. NOTE: the original parent may still have its own
1560 * pip refs on the object.
1561 */
1562 if (object != NULL) {
1563 vm_object_pip_wakeupn(object, bp->b_npages);
1564 VM_OBJECT_UNLOCK(object);
1565 }
1566
1567 /*
1568 * release the physical I/O buffer
1569 */
1570 relpbuf(
1571 bp,
1572 ((bp->b_iocmd == BIO_READ) ? &nsw_rcount :
1573 ((bp->b_flags & B_ASYNC) ?
1574 &nsw_wcount_async :
1575 &nsw_wcount_sync
1576 )
1577 )
1578 );
1579 splx(s);
1580 }
1581
1582 /*
1583 * swap_pager_isswapped:
1584 *
1585 * Return 1 if at least one page in the given object is paged
1586 * out to the given swap device.
1587 *
1588 * This routine may not block.
1589 */
1590 int
1591 swap_pager_isswapped(vm_object_t object, struct swdevt *sp)
1592 {
1593 daddr_t index = 0;
1594 int bcount;
1595 int i;
1596
1597 VM_OBJECT_LOCK_ASSERT(object, MA_OWNED);
1598 if (object->type != OBJT_SWAP)
1599 return (0);
1600
1601 for (bcount = 0; bcount < object->un_pager.swp.swp_bcount; bcount++) {
1602 struct swblock *swap;
1603
1604 mtx_lock(&swhash_mtx);
1605 if ((swap = *swp_pager_hash(object, index)) != NULL) {
1606 for (i = 0; i < SWAP_META_PAGES; ++i) {
1607 daddr_t v = swap->swb_pages[i];
1608 if (v == SWAPBLK_NONE)
1609 continue;
1610 if (swp_pager_find_dev(v) == sp) {
1611 mtx_unlock(&swhash_mtx);
1612 return 1;
1613 }
1614 }
1615 }
1616 mtx_unlock(&swhash_mtx);
1617 index += SWAP_META_PAGES;
1618 if (index > 0x20000000)
1619 panic("swap_pager_isswapped: failed to locate all swap meta blocks");
1620 }
1621 return 0;
1622 }
1623
1624 /*
1625 * SWP_PAGER_FORCE_PAGEIN() - force a swap block to be paged in
1626 *
1627 * This routine dissociates the page at the given index within a
1628 * swap block from its backing store, paging it in if necessary.
1629 * If the page is paged in, it is placed in the inactive queue,
1630 * since it had its backing store ripped out from under it.
1631 * We also attempt to swap in all other pages in the swap block,
1632 * we only guarantee that the one at the specified index is
1633 * paged in.
1634 *
1635 * XXX - The code to page the whole block in doesn't work, so we
1636 * revert to the one-by-one behavior for now. Sigh.
1637 */
1638 static __inline void
1639 swp_pager_force_pagein(struct swblock *swap, int idx)
1640 {
1641 vm_object_t object;
1642 vm_page_t m;
1643 vm_pindex_t pindex;
1644
1645 object = swap->swb_object;
1646 pindex = swap->swb_index;
1647 mtx_unlock(&swhash_mtx);
1648
1649 VM_OBJECT_LOCK(object);
1650 vm_object_pip_add(object, 1);
1651 m = vm_page_grab(object, pindex + idx, VM_ALLOC_NORMAL|VM_ALLOC_RETRY);
1652 if (m->valid == VM_PAGE_BITS_ALL) {
1653 vm_object_pip_subtract(object, 1);
1654 vm_page_lock_queues();
1655 vm_page_activate(m);
1656 vm_page_dirty(m);
1657 vm_page_wakeup(m);
1658 vm_page_unlock_queues();
1659 vm_pager_page_unswapped(m);
1660 VM_OBJECT_UNLOCK(object);
1661 return;
1662 }
1663
1664 if (swap_pager_getpages(object, &m, 1, 0) !=
1665 VM_PAGER_OK)
1666 panic("swap_pager_force_pagein: read from swap failed");/*XXX*/
1667 vm_object_pip_subtract(object, 1);
1668 vm_page_lock_queues();
1669 vm_page_dirty(m);
1670 vm_page_dontneed(m);
1671 vm_page_wakeup(m);
1672 vm_page_unlock_queues();
1673 vm_pager_page_unswapped(m);
1674 VM_OBJECT_UNLOCK(object);
1675 }
1676
1677
1678 /*
1679 * swap_pager_swapoff:
1680 *
1681 * Page in all of the pages that have been paged out to the
1682 * given device. The corresponding blocks in the bitmap must be
1683 * marked as allocated and the device must be flagged SW_CLOSING.
1684 * There may be no processes swapped out to the device.
1685 *
1686 * The sw_used parameter points to the field in the swdev structure
1687 * that contains a count of the number of blocks still allocated
1688 * on the device. If we encounter objects with a nonzero pip count
1689 * in our scan, we use this number to determine if we're really done.
1690 *
1691 * This routine may block.
1692 */
1693 static void
1694 swap_pager_swapoff(struct swdevt *sp, int *sw_used)
1695 {
1696 struct swblock **pswap;
1697 struct swblock *swap;
1698 vm_object_t waitobj;
1699 daddr_t v;
1700 int i, j;
1701
1702 GIANT_REQUIRED;
1703
1704 full_rescan:
1705 waitobj = NULL;
1706 for (i = 0; i <= swhash_mask; i++) { /* '<=' is correct here */
1707 restart:
1708 pswap = &swhash[i];
1709 mtx_lock(&swhash_mtx);
1710 while ((swap = *pswap) != NULL) {
1711 for (j = 0; j < SWAP_META_PAGES; ++j) {
1712 v = swap->swb_pages[j];
1713 if (v != SWAPBLK_NONE &&
1714 swp_pager_find_dev(v) == sp)
1715 break;
1716 }
1717 if (j < SWAP_META_PAGES) {
1718 swp_pager_force_pagein(swap, j);
1719 goto restart;
1720 } else if (swap->swb_object->paging_in_progress) {
1721 if (!waitobj)
1722 waitobj = swap->swb_object;
1723 }
1724 pswap = &swap->swb_hnext;
1725 }
1726 mtx_unlock(&swhash_mtx);
1727 }
1728 if (waitobj && *sw_used) {
1729 /*
1730 * We wait on an arbitrary object to clock our rescans
1731 * to the rate of paging completion.
1732 */
1733 VM_OBJECT_LOCK(waitobj);
1734 vm_object_pip_wait(waitobj, "swpoff");
1735 VM_OBJECT_UNLOCK(waitobj);
1736 goto full_rescan;
1737 }
1738 if (*sw_used)
1739 panic("swapoff: failed to locate %d swap blocks", *sw_used);
1740 }
1741
1742 /************************************************************************
1743 * SWAP META DATA *
1744 ************************************************************************
1745 *
1746 * These routines manipulate the swap metadata stored in the
1747 * OBJT_SWAP object. All swp_*() routines must be called at
1748 * splvm() because swap can be freed up by the low level vm_page
1749 * code which might be called from interrupts beyond what splbio() covers.
1750 *
1751 * Swap metadata is implemented with a global hash and not directly
1752 * linked into the object. Instead the object simply contains
1753 * appropriate tracking counters.
1754 */
1755
1756 /*
1757 * SWP_PAGER_META_BUILD() - add swap block to swap meta data for object
1758 *
1759 * We first convert the object to a swap object if it is a default
1760 * object.
1761 *
1762 * The specified swapblk is added to the object's swap metadata. If
1763 * the swapblk is not valid, it is freed instead. Any previously
1764 * assigned swapblk is freed.
1765 *
1766 * This routine must be called at splvm(), except when used to convert
1767 * an OBJT_DEFAULT object into an OBJT_SWAP object.
1768 */
1769 static void
1770 swp_pager_meta_build(vm_object_t object, vm_pindex_t pindex, daddr_t swapblk)
1771 {
1772 struct swblock *swap;
1773 struct swblock **pswap;
1774 int idx;
1775
1776 VM_OBJECT_LOCK_ASSERT(object, MA_OWNED);
1777 /*
1778 * Convert default object to swap object if necessary
1779 */
1780 if (object->type != OBJT_SWAP) {
1781 object->type = OBJT_SWAP;
1782 object->un_pager.swp.swp_bcount = 0;
1783
1784 if (object->handle != NULL) {
1785 mtx_lock(&sw_alloc_mtx);
1786 TAILQ_INSERT_TAIL(
1787 NOBJLIST(object->handle),
1788 object,
1789 pager_object_list
1790 );
1791 mtx_unlock(&sw_alloc_mtx);
1792 }
1793 }
1794
1795 /*
1796 * Locate hash entry. If not found create, but if we aren't adding
1797 * anything just return. If we run out of space in the map we wait
1798 * and, since the hash table may have changed, retry.
1799 */
1800 retry:
1801 mtx_lock(&swhash_mtx);
1802 pswap = swp_pager_hash(object, pindex);
1803
1804 if ((swap = *pswap) == NULL) {
1805 int i;
1806
1807 if (swapblk == SWAPBLK_NONE)
1808 goto done;
1809
1810 swap = *pswap = uma_zalloc(swap_zone, M_NOWAIT);
1811 if (swap == NULL) {
1812 mtx_unlock(&swhash_mtx);
1813 VM_OBJECT_UNLOCK(object);
1814 VM_WAIT;
1815 VM_OBJECT_LOCK(object);
1816 goto retry;
1817 }
1818
1819 swap->swb_hnext = NULL;
1820 swap->swb_object = object;
1821 swap->swb_index = pindex & ~(vm_pindex_t)SWAP_META_MASK;
1822 swap->swb_count = 0;
1823
1824 ++object->un_pager.swp.swp_bcount;
1825
1826 for (i = 0; i < SWAP_META_PAGES; ++i)
1827 swap->swb_pages[i] = SWAPBLK_NONE;
1828 }
1829
1830 /*
1831 * Delete prior contents of metadata
1832 */
1833 idx = pindex & SWAP_META_MASK;
1834
1835 if (swap->swb_pages[idx] != SWAPBLK_NONE) {
1836 swp_pager_freeswapspace(swap->swb_pages[idx], 1);
1837 --swap->swb_count;
1838 }
1839
1840 /*
1841 * Enter block into metadata
1842 */
1843 swap->swb_pages[idx] = swapblk;
1844 if (swapblk != SWAPBLK_NONE)
1845 ++swap->swb_count;
1846 done:
1847 mtx_unlock(&swhash_mtx);
1848 }
1849
1850 /*
1851 * SWP_PAGER_META_FREE() - free a range of blocks in the object's swap metadata
1852 *
1853 * The requested range of blocks is freed, with any associated swap
1854 * returned to the swap bitmap.
1855 *
1856 * This routine will free swap metadata structures as they are cleaned
1857 * out. This routine does *NOT* operate on swap metadata associated
1858 * with resident pages.
1859 *
1860 * This routine must be called at splvm()
1861 */
1862 static void
1863 swp_pager_meta_free(vm_object_t object, vm_pindex_t index, daddr_t count)
1864 {
1865
1866 VM_OBJECT_LOCK_ASSERT(object, MA_OWNED);
1867 if (object->type != OBJT_SWAP)
1868 return;
1869
1870 while (count > 0) {
1871 struct swblock **pswap;
1872 struct swblock *swap;
1873
1874 mtx_lock(&swhash_mtx);
1875 pswap = swp_pager_hash(object, index);
1876
1877 if ((swap = *pswap) != NULL) {
1878 daddr_t v = swap->swb_pages[index & SWAP_META_MASK];
1879
1880 if (v != SWAPBLK_NONE) {
1881 swp_pager_freeswapspace(v, 1);
1882 swap->swb_pages[index & SWAP_META_MASK] =
1883 SWAPBLK_NONE;
1884 if (--swap->swb_count == 0) {
1885 *pswap = swap->swb_hnext;
1886 uma_zfree(swap_zone, swap);
1887 --object->un_pager.swp.swp_bcount;
1888 }
1889 }
1890 --count;
1891 ++index;
1892 } else {
1893 int n = SWAP_META_PAGES - (index & SWAP_META_MASK);
1894 count -= n;
1895 index += n;
1896 }
1897 mtx_unlock(&swhash_mtx);
1898 }
1899 }
1900
1901 /*
1902 * SWP_PAGER_META_FREE_ALL() - destroy all swap metadata associated with object
1903 *
1904 * This routine locates and destroys all swap metadata associated with
1905 * an object.
1906 *
1907 * This routine must be called at splvm()
1908 */
1909 static void
1910 swp_pager_meta_free_all(vm_object_t object)
1911 {
1912 daddr_t index = 0;
1913
1914 VM_OBJECT_LOCK_ASSERT(object, MA_OWNED);
1915 if (object->type != OBJT_SWAP)
1916 return;
1917
1918 while (object->un_pager.swp.swp_bcount) {
1919 struct swblock **pswap;
1920 struct swblock *swap;
1921
1922 mtx_lock(&swhash_mtx);
1923 pswap = swp_pager_hash(object, index);
1924 if ((swap = *pswap) != NULL) {
1925 int i;
1926
1927 for (i = 0; i < SWAP_META_PAGES; ++i) {
1928 daddr_t v = swap->swb_pages[i];
1929 if (v != SWAPBLK_NONE) {
1930 --swap->swb_count;
1931 swp_pager_freeswapspace(v, 1);
1932 }
1933 }
1934 if (swap->swb_count != 0)
1935 panic("swap_pager_meta_free_all: swb_count != 0");
1936 *pswap = swap->swb_hnext;
1937 uma_zfree(swap_zone, swap);
1938 --object->un_pager.swp.swp_bcount;
1939 }
1940 mtx_unlock(&swhash_mtx);
1941 index += SWAP_META_PAGES;
1942 if (index > 0x20000000)
1943 panic("swp_pager_meta_free_all: failed to locate all swap meta blocks");
1944 }
1945 }
1946
1947 /*
1948 * SWP_PAGER_METACTL() - misc control of swap and vm_page_t meta data.
1949 *
1950 * This routine is capable of looking up, popping, or freeing
1951 * swapblk assignments in the swap meta data or in the vm_page_t.
1952 * The routine typically returns the swapblk being looked-up, or popped,
1953 * or SWAPBLK_NONE if the block was freed, or SWAPBLK_NONE if the block
1954 * was invalid. This routine will automatically free any invalid
1955 * meta-data swapblks.
1956 *
1957 * It is not possible to store invalid swapblks in the swap meta data
1958 * (other then a literal 'SWAPBLK_NONE'), so we don't bother checking.
1959 *
1960 * When acting on a busy resident page and paging is in progress, we
1961 * have to wait until paging is complete but otherwise can act on the
1962 * busy page.
1963 *
1964 * This routine must be called at splvm().
1965 *
1966 * SWM_FREE remove and free swap block from metadata
1967 * SWM_POP remove from meta data but do not free.. pop it out
1968 */
1969 static daddr_t
1970 swp_pager_meta_ctl(vm_object_t object, vm_pindex_t pindex, int flags)
1971 {
1972 struct swblock **pswap;
1973 struct swblock *swap;
1974 daddr_t r1;
1975 int idx;
1976
1977 VM_OBJECT_LOCK_ASSERT(object, MA_OWNED);
1978 /*
1979 * The meta data only exists of the object is OBJT_SWAP
1980 * and even then might not be allocated yet.
1981 */
1982 if (object->type != OBJT_SWAP)
1983 return (SWAPBLK_NONE);
1984
1985 r1 = SWAPBLK_NONE;
1986 mtx_lock(&swhash_mtx);
1987 pswap = swp_pager_hash(object, pindex);
1988
1989 if ((swap = *pswap) != NULL) {
1990 idx = pindex & SWAP_META_MASK;
1991 r1 = swap->swb_pages[idx];
1992
1993 if (r1 != SWAPBLK_NONE) {
1994 if (flags & SWM_FREE) {
1995 swp_pager_freeswapspace(r1, 1);
1996 r1 = SWAPBLK_NONE;
1997 }
1998 if (flags & (SWM_FREE|SWM_POP)) {
1999 swap->swb_pages[idx] = SWAPBLK_NONE;
2000 if (--swap->swb_count == 0) {
2001 *pswap = swap->swb_hnext;
2002 uma_zfree(swap_zone, swap);
2003 --object->un_pager.swp.swp_bcount;
2004 }
2005 }
2006 }
2007 }
2008 mtx_unlock(&swhash_mtx);
2009 return (r1);
2010 }
2011
2012 /*
2013 * System call swapon(name) enables swapping on device name,
2014 * which must be in the swdevsw. Return EBUSY
2015 * if already swapping on this device.
2016 */
2017 #ifndef _SYS_SYSPROTO_H_
2018 struct swapon_args {
2019 char *name;
2020 };
2021 #endif
2022
2023 /*
2024 * MPSAFE
2025 */
2026 /* ARGSUSED */
2027 int
2028 swapon(struct thread *td, struct swapon_args *uap)
2029 {
2030 struct vattr attr;
2031 struct vnode *vp;
2032 struct nameidata nd;
2033 int error;
2034
2035 mtx_lock(&Giant);
2036 error = suser(td);
2037 if (error)
2038 goto done2;
2039
2040 while (swdev_syscall_active)
2041 tsleep(&swdev_syscall_active, PUSER - 1, "swpon", 0);
2042 swdev_syscall_active = 1;
2043
2044 /*
2045 * Swap metadata may not fit in the KVM if we have physical
2046 * memory of >1GB.
2047 */
2048 if (swap_zone == NULL) {
2049 error = ENOMEM;
2050 goto done;
2051 }
2052
2053 NDINIT(&nd, LOOKUP, FOLLOW, UIO_USERSPACE, uap->name, td);
2054 error = namei(&nd);
2055 if (error)
2056 goto done;
2057
2058 NDFREE(&nd, NDF_ONLY_PNBUF);
2059 vp = nd.ni_vp;
2060
2061 if (vn_isdisk(vp, &error)) {
2062 error = swapongeom(td, vp);
2063 } else if (vp->v_type == VREG &&
2064 (vp->v_mount->mnt_vfc->vfc_flags & VFCF_NETWORK) != 0 &&
2065 (error = VOP_GETATTR(vp, &attr, td->td_ucred, td)) == 0) {
2066 /*
2067 * Allow direct swapping to NFS regular files in the same
2068 * way that nfs_mountroot() sets up diskless swapping.
2069 */
2070 error = swaponvp(td, vp, attr.va_size / DEV_BSIZE);
2071 }
2072
2073 if (error)
2074 vrele(vp);
2075 done:
2076 swdev_syscall_active = 0;
2077 wakeup_one(&swdev_syscall_active);
2078 done2:
2079 mtx_unlock(&Giant);
2080 return (error);
2081 }
2082
2083 static void
2084 swaponsomething(struct vnode *vp, void *id, u_long nblks, sw_strategy_t *strategy, sw_close_t *close, dev_t dev)
2085 {
2086 struct swdevt *sp, *tsp;
2087 swblk_t dvbase;
2088 u_long mblocks;
2089
2090 /*
2091 * If we go beyond this, we get overflows in the radix
2092 * tree bitmap code.
2093 */
2094 mblocks = 0x40000000 / BLIST_META_RADIX;
2095 if (nblks > mblocks) {
2096 printf("WARNING: reducing size to maximum of %lu blocks per swap unit\n",
2097 mblocks);
2098 nblks = mblocks;
2099 }
2100 /*
2101 * nblks is in DEV_BSIZE'd chunks, convert to PAGE_SIZE'd chunks.
2102 * First chop nblks off to page-align it, then convert.
2103 *
2104 * sw->sw_nblks is in page-sized chunks now too.
2105 */
2106 nblks &= ~(ctodb(1) - 1);
2107 nblks = dbtoc(nblks);
2108
2109 sp = malloc(sizeof *sp, M_VMPGDATA, M_WAITOK | M_ZERO);
2110 sp->sw_vp = vp;
2111 sp->sw_id = id;
2112 sp->sw_dev = dev;
2113 sp->sw_flags = 0;
2114 sp->sw_nblks = nblks;
2115 sp->sw_used = 0;
2116 sp->sw_strategy = strategy;
2117 sp->sw_close = close;
2118
2119 sp->sw_blist = blist_create(nblks);
2120 /*
2121 * Do not free the first two block in order to avoid overwriting
2122 * any bsd label at the front of the partition
2123 */
2124 blist_free(sp->sw_blist, 2, nblks - 2);
2125
2126 dvbase = 0;
2127 mtx_lock(&sw_dev_mtx);
2128 TAILQ_FOREACH(tsp, &swtailq, sw_list) {
2129 if (tsp->sw_end >= dvbase) {
2130 /*
2131 * We put one uncovered page between the devices
2132 * in order to definitively prevent any cross-device
2133 * I/O requests
2134 */
2135 dvbase = tsp->sw_end + 1;
2136 }
2137 }
2138 sp->sw_first = dvbase;
2139 sp->sw_end = dvbase + nblks;
2140 TAILQ_INSERT_TAIL(&swtailq, sp, sw_list);
2141 nswapdev++;
2142 swap_pager_avail += nblks;
2143 swp_sizecheck();
2144 mtx_unlock(&sw_dev_mtx);
2145 }
2146
2147 /*
2148 * SYSCALL: swapoff(devname)
2149 *
2150 * Disable swapping on the given device.
2151 *
2152 * XXX: Badly designed system call: it should use a device index
2153 * rather than filename as specification. We keep sw_vp around
2154 * only to make this work.
2155 */
2156 #ifndef _SYS_SYSPROTO_H_
2157 struct swapoff_args {
2158 char *name;
2159 };
2160 #endif
2161
2162 /*
2163 * MPSAFE
2164 */
2165 /* ARGSUSED */
2166 int
2167 swapoff(struct thread *td, struct swapoff_args *uap)
2168 {
2169 struct vnode *vp;
2170 struct nameidata nd;
2171 struct swdevt *sp;
2172 u_long nblks, dvbase;
2173 int error;
2174
2175 mtx_lock(&Giant);
2176
2177 error = suser(td);
2178 if (error)
2179 goto done2;
2180
2181 while (swdev_syscall_active)
2182 tsleep(&swdev_syscall_active, PUSER - 1, "swpoff", 0);
2183 swdev_syscall_active = 1;
2184
2185 NDINIT(&nd, LOOKUP, FOLLOW, UIO_USERSPACE, uap->name, td);
2186 error = namei(&nd);
2187 if (error)
2188 goto done;
2189 NDFREE(&nd, NDF_ONLY_PNBUF);
2190 vp = nd.ni_vp;
2191
2192 mtx_lock(&sw_dev_mtx);
2193 TAILQ_FOREACH(sp, &swtailq, sw_list) {
2194 if (sp->sw_vp == vp)
2195 goto found;
2196 }
2197 mtx_unlock(&sw_dev_mtx);
2198 error = EINVAL;
2199 goto done;
2200 found:
2201 mtx_unlock(&sw_dev_mtx);
2202 #ifdef MAC
2203 (void) vn_lock(vp, LK_EXCLUSIVE | LK_RETRY, td);
2204 error = mac_check_system_swapoff(td->td_ucred, vp);
2205 (void) VOP_UNLOCK(vp, 0, td);
2206 if (error != 0)
2207 goto done;
2208 #endif
2209
2210 nblks = sp->sw_nblks;
2211
2212 /*
2213 * We can turn off this swap device safely only if the
2214 * available virtual memory in the system will fit the amount
2215 * of data we will have to page back in, plus an epsilon so
2216 * the system doesn't become critically low on swap space.
2217 */
2218 if (cnt.v_free_count + cnt.v_cache_count + swap_pager_avail <
2219 nblks + nswap_lowat) {
2220 error = ENOMEM;
2221 goto done;
2222 }
2223
2224 /*
2225 * Prevent further allocations on this device.
2226 */
2227 mtx_lock(&sw_dev_mtx);
2228 sp->sw_flags |= SW_CLOSING;
2229 for (dvbase = 0; dvbase < sp->sw_end; dvbase += dmmax) {
2230 swap_pager_avail -= blist_fill(sp->sw_blist,
2231 dvbase, dmmax);
2232 }
2233 mtx_unlock(&sw_dev_mtx);
2234
2235 /*
2236 * Page in the contents of the device and close it.
2237 */
2238 #ifndef NO_SWAPPING
2239 vm_proc_swapin_all(sp);
2240 #endif /* !NO_SWAPPING */
2241 swap_pager_swapoff(sp, &sp->sw_used);
2242
2243 sp->sw_close(td, sp);
2244 sp->sw_id = NULL;
2245 mtx_lock(&sw_dev_mtx);
2246 TAILQ_REMOVE(&swtailq, sp, sw_list);
2247 nswapdev--;
2248 if (nswapdev == 0) {
2249 swap_pager_full = 2;
2250 swap_pager_almost_full = 1;
2251 }
2252 if (swdevhd == sp)
2253 swdevhd = NULL;
2254 mtx_unlock(&sw_dev_mtx);
2255 blist_destroy(sp->sw_blist);
2256 free(sp, M_VMPGDATA);
2257
2258 done:
2259 swdev_syscall_active = 0;
2260 wakeup_one(&swdev_syscall_active);
2261 done2:
2262 mtx_unlock(&Giant);
2263 return (error);
2264 }
2265
2266 void
2267 swap_pager_status(int *total, int *used)
2268 {
2269 struct swdevt *sp;
2270
2271 *total = 0;
2272 *used = 0;
2273 mtx_lock(&sw_dev_mtx);
2274 TAILQ_FOREACH(sp, &swtailq, sw_list) {
2275 *total += sp->sw_nblks;
2276 *used += sp->sw_used;
2277 }
2278 mtx_unlock(&sw_dev_mtx);
2279 }
2280
2281 static int
2282 sysctl_vm_swap_info(SYSCTL_HANDLER_ARGS)
2283 {
2284 int *name = (int *)arg1;
2285 int error, n;
2286 struct xswdev xs;
2287 struct swdevt *sp;
2288
2289 if (arg2 != 1) /* name length */
2290 return (EINVAL);
2291
2292 n = 0;
2293 mtx_lock(&sw_dev_mtx);
2294 TAILQ_FOREACH(sp, &swtailq, sw_list) {
2295 if (n == *name) {
2296 mtx_unlock(&sw_dev_mtx);
2297 xs.xsw_version = XSWDEV_VERSION;
2298 xs.xsw_dev = sp->sw_dev;
2299 xs.xsw_flags = sp->sw_flags;
2300 xs.xsw_nblks = sp->sw_nblks;
2301 xs.xsw_used = sp->sw_used;
2302
2303 error = SYSCTL_OUT(req, &xs, sizeof(xs));
2304 return (error);
2305 }
2306 n++;
2307 }
2308 mtx_unlock(&sw_dev_mtx);
2309 return (ENOENT);
2310 }
2311
2312 SYSCTL_INT(_vm, OID_AUTO, nswapdev, CTLFLAG_RD, &nswapdev, 0,
2313 "Number of swap devices");
2314 SYSCTL_NODE(_vm, OID_AUTO, swap_info, CTLFLAG_RD, sysctl_vm_swap_info,
2315 "Swap statistics by device");
2316
2317 /*
2318 * vmspace_swap_count() - count the approximate swap useage in pages for a
2319 * vmspace.
2320 *
2321 * The map must be locked.
2322 *
2323 * Swap useage is determined by taking the proportional swap used by
2324 * VM objects backing the VM map. To make up for fractional losses,
2325 * if the VM object has any swap use at all the associated map entries
2326 * count for at least 1 swap page.
2327 */
2328 int
2329 vmspace_swap_count(struct vmspace *vmspace)
2330 {
2331 vm_map_t map = &vmspace->vm_map;
2332 vm_map_entry_t cur;
2333 int count = 0;
2334
2335 for (cur = map->header.next; cur != &map->header; cur = cur->next) {
2336 vm_object_t object;
2337
2338 if ((cur->eflags & MAP_ENTRY_IS_SUB_MAP) == 0 &&
2339 (object = cur->object.vm_object) != NULL) {
2340 VM_OBJECT_LOCK(object);
2341 if (object->type == OBJT_SWAP &&
2342 object->un_pager.swp.swp_bcount != 0) {
2343 int n = (cur->end - cur->start) / PAGE_SIZE;
2344
2345 count += object->un_pager.swp.swp_bcount *
2346 SWAP_META_PAGES * n / object->size + 1;
2347 }
2348 VM_OBJECT_UNLOCK(object);
2349 }
2350 }
2351 return (count);
2352 }
2353
2354 /*
2355 * GEOM backend
2356 *
2357 * Swapping onto disk devices.
2358 *
2359 */
2360
2361 static g_orphan_t swapgeom_orphan;
2362
2363 static struct g_class g_swap_class = {
2364 .name = "SWAP",
2365 .version = G_VERSION,
2366 .orphan = swapgeom_orphan,
2367 };
2368
2369 DECLARE_GEOM_CLASS(g_swap_class, g_class);
2370
2371
2372 static void
2373 swapgeom_done(struct bio *bp2)
2374 {
2375 struct buf *bp;
2376
2377 bp = bp2->bio_caller2;
2378 if (bp2->bio_error)
2379 bp->b_ioflags |= BIO_ERROR;
2380 bufdone(bp);
2381 g_destroy_bio(bp2);
2382 }
2383
2384 static void
2385 swapgeom_strategy(struct buf *bp, struct swdevt *sp)
2386 {
2387 struct bio *bio;
2388 struct g_consumer *cp;
2389
2390 cp = sp->sw_id;
2391 if (cp == NULL) {
2392 bp->b_error = ENXIO;
2393 bp->b_ioflags |= BIO_ERROR;
2394 bufdone(bp);
2395 return;
2396 }
2397 bio = g_clone_bio(&bp->b_io);
2398 if (bio == NULL) {
2399 /*
2400 * XXX: This is better than panicing, but not much better.
2401 * XXX: Somehow this should be retried. A more generic
2402 * XXX: implementation of ENOMEM in geom may be able to cope.
2403 */
2404 bp->b_error = ENOMEM;
2405 bp->b_ioflags |= BIO_ERROR;
2406 bufdone(bp);
2407 return;
2408 }
2409 bio->bio_caller2 = bp;
2410 bio->bio_offset = (bp->b_blkno - sp->sw_first) * PAGE_SIZE;
2411 bio->bio_length = bp->b_bcount;
2412 bio->bio_done = swapgeom_done;
2413 g_io_request(bio, cp);
2414 return;
2415 }
2416
2417 static void
2418 swapgeom_orphan(struct g_consumer *cp)
2419 {
2420 struct swdevt *sp;
2421
2422 mtx_lock(&sw_dev_mtx);
2423 TAILQ_FOREACH(sp, &swtailq, sw_list)
2424 if (sp->sw_id == cp)
2425 sp->sw_id = NULL;
2426 mtx_unlock(&sw_dev_mtx);
2427 }
2428
2429 static void
2430 swapgeom_close_ev(void *arg, int flags)
2431 {
2432 struct g_consumer *cp;
2433
2434 cp = arg;
2435 g_access(cp, -1, -1, 0);
2436 g_detach(cp);
2437 g_destroy_consumer(cp);
2438 }
2439
2440 static void
2441 swapgeom_close(struct thread *td, struct swdevt *sw)
2442 {
2443
2444 /* XXX: direct call when Giant untangled */
2445 g_waitfor_event(swapgeom_close_ev, sw->sw_id, M_WAITOK, NULL);
2446 }
2447
2448
2449 struct swh0h0 {
2450 struct cdev *dev;
2451 struct vnode *vp;
2452 int error;
2453 };
2454
2455 static void
2456 swapongeom_ev(void *arg, int flags)
2457 {
2458 struct swh0h0 *swh;
2459 struct g_provider *pp;
2460 struct g_consumer *cp;
2461 static struct g_geom *gp;
2462 struct swdevt *sp;
2463 u_long nblks;
2464 int error;
2465
2466 swh = arg;
2467 swh->error = 0;
2468 pp = g_dev_getprovider(swh->dev);
2469 if (pp == NULL) {
2470 swh->error = ENODEV;
2471 return;
2472 }
2473 mtx_lock(&sw_dev_mtx);
2474 TAILQ_FOREACH(sp, &swtailq, sw_list) {
2475 cp = sp->sw_id;
2476 if (cp != NULL && cp->provider == pp) {
2477 mtx_unlock(&sw_dev_mtx);
2478 swh->error = EBUSY;
2479 return;
2480 }
2481 }
2482 mtx_unlock(&sw_dev_mtx);
2483 if (gp == NULL)
2484 gp = g_new_geomf(&g_swap_class, "swap", NULL);
2485 cp = g_new_consumer(gp);
2486 g_attach(cp, pp);
2487 /*
2488 * XXX: Everytime you think you can improve the margin for
2489 * footshooting, somebody depends on the ability to do so:
2490 * savecore(8) wants to write to our swapdev so we cannot
2491 * set an exclusive count :-(
2492 */
2493 error = g_access(cp, 1, 1, 0);
2494 if (error) {
2495 g_detach(cp);
2496 g_destroy_consumer(cp);
2497 swh->error = error;
2498 return;
2499 }
2500 nblks = pp->mediasize / DEV_BSIZE;
2501 swaponsomething(swh->vp, cp, nblks, swapgeom_strategy,
2502 swapgeom_close, dev2udev(swh->dev));
2503 swh->error = 0;
2504 return;
2505 }
2506
2507 static int
2508 swapongeom(struct thread *td, struct vnode *vp)
2509 {
2510 int error;
2511 struct swh0h0 swh;
2512
2513 vn_lock(vp, LK_EXCLUSIVE | LK_RETRY, td);
2514
2515 swh.dev = vp->v_rdev;
2516 swh.vp = vp;
2517 swh.error = 0;
2518 /* XXX: direct call when Giant untangled */
2519 error = g_waitfor_event(swapongeom_ev, &swh, M_WAITOK, NULL);
2520 if (!error)
2521 error = swh.error;
2522 VOP_UNLOCK(vp, 0, td);
2523 return (error);
2524 }
2525
2526 /*
2527 * VNODE backend
2528 *
2529 * This is used mainly for network filesystem (read: probably only tested
2530 * with NFS) swapfiles.
2531 *
2532 */
2533
2534 static void
2535 swapdev_strategy(struct buf *bp, struct swdevt *sp)
2536 {
2537 int s;
2538 struct vnode *vp, *vp2;
2539
2540 bp->b_dev = NULL;
2541 bp->b_blkno = ctodb(bp->b_blkno - sp->sw_first);
2542
2543 vp2 = sp->sw_id;
2544 vhold(vp2);
2545 s = splvm();
2546 if (bp->b_iocmd == BIO_WRITE) {
2547 vp = bp->b_vp;
2548 if (vp) {
2549 VI_LOCK(vp);
2550 vp->v_numoutput--;
2551 if ((vp->v_iflag & VI_BWAIT) && vp->v_numoutput <= 0) {
2552 vp->v_iflag &= ~VI_BWAIT;
2553 wakeup(&vp->v_numoutput);
2554 }
2555 VI_UNLOCK(vp);
2556 }
2557 VI_LOCK(vp2);
2558 vp2->v_numoutput++;
2559 VI_UNLOCK(vp2);
2560 }
2561 bp->b_vp = vp2;
2562 splx(s);
2563 bp->b_iooffset = dbtob(bp->b_blkno);
2564 VOP_STRATEGY(vp2, bp);
2565 return;
2566 }
2567
2568 static void
2569 swapdev_close(struct thread *td, struct swdevt *sp)
2570 {
2571
2572 VOP_CLOSE(sp->sw_vp, FREAD | FWRITE, td->td_ucred, td);
2573 vrele(sp->sw_vp);
2574 }
2575
2576
2577 static int
2578 swaponvp(struct thread *td, struct vnode *vp, u_long nblks)
2579 {
2580 struct swdevt *sp;
2581 int error;
2582
2583 if (nblks == 0)
2584 return (ENXIO);
2585 mtx_lock(&sw_dev_mtx);
2586 TAILQ_FOREACH(sp, &swtailq, sw_list) {
2587 if (sp->sw_id == vp) {
2588 mtx_unlock(&sw_dev_mtx);
2589 return (EBUSY);
2590 }
2591 }
2592 mtx_unlock(&sw_dev_mtx);
2593
2594 (void) vn_lock(vp, LK_EXCLUSIVE | LK_RETRY, td);
2595 #ifdef MAC
2596 error = mac_check_system_swapon(td->td_ucred, vp);
2597 if (error == 0)
2598 #endif
2599 error = VOP_OPEN(vp, FREAD | FWRITE, td->td_ucred, td, -1);
2600 (void) VOP_UNLOCK(vp, 0, td);
2601 if (error)
2602 return (error);
2603
2604 swaponsomething(vp, vp, nblks, swapdev_strategy, swapdev_close,
2605 NODEV);
2606 return (0);
2607 }
Cache object: 32bc6f2cb4ce7b7283815d34a2949f76
|