2 * SPDX-License-Identifier: BSD-4-Clause
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.
10 * This code is derived from software contributed to Berkeley by
11 * the Systems Programming Group of the University of Utah Computer
14 * Redistribution and use in source and binary forms, with or without
15 * modification, are permitted provided that the following conditions
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.
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
45 * Radix Bitmap 'blists'.
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.
53 * - on the fly reallocation of swap during putpages. The new system
54 * does not try to keep previously allocated swap blocks for dirty
57 * - on the fly deallocation of swap
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
65 * from: Utah $Hdr: swap_pager.c 1.4 91/04/30$
67 * @(#)swap_pager.c 8.9 (Berkeley) 3/21/94
68 * @(#)vm_swap.c 8.5 (Berkeley) 2/17/94
71 #include <sys/cdefs.h>
72 __FBSDID("$FreeBSD$");
74 #include "opt_compat.h"
78 #include <sys/param.h>
79 #include <sys/systm.h>
81 #include <sys/kernel.h>
87 #include <sys/fcntl.h>
88 #include <sys/mount.h>
89 #include <sys/namei.h>
90 #include <sys/vnode.h>
91 #include <sys/malloc.h>
92 #include <sys/pctrie.h>
93 #include <sys/racct.h>
94 #include <sys/resource.h>
95 #include <sys/resourcevar.h>
96 #include <sys/rwlock.h>
98 #include <sys/sysctl.h>
99 #include <sys/sysproto.h>
100 #include <sys/blist.h>
101 #include <sys/lock.h>
103 #include <sys/vmmeter.h>
105 #include <security/mac/mac_framework.h>
109 #include <vm/vm_map.h>
110 #include <vm/vm_kern.h>
111 #include <vm/vm_object.h>
112 #include <vm/vm_page.h>
113 #include <vm/vm_pager.h>
114 #include <vm/vm_pageout.h>
115 #include <vm/vm_param.h>
116 #include <vm/swap_pager.h>
117 #include <vm/vm_extern.h>
120 #include <geom/geom.h>
123 * MAX_PAGEOUT_CLUSTER must be a power of 2 between 1 and 64.
124 * The 64-page limit is due to the radix code (kern/subr_blist.c).
126 #ifndef MAX_PAGEOUT_CLUSTER
127 #define MAX_PAGEOUT_CLUSTER 32
130 #if !defined(SWB_NPAGES)
131 #define SWB_NPAGES MAX_PAGEOUT_CLUSTER
134 #define SWAP_META_PAGES PCTRIE_COUNT
137 * A swblk structure maps each page index within a
138 * SWAP_META_PAGES-aligned and sized range to the address of an
139 * on-disk swap block (or SWAPBLK_NONE). The collection of these
140 * mappings for an entire vm object is implemented as a pc-trie.
144 daddr_t d[SWAP_META_PAGES];
147 static MALLOC_DEFINE(M_VMPGDATA, "vm_pgdata", "swap pager private data");
148 static struct mtx sw_dev_mtx;
149 static TAILQ_HEAD(, swdevt) swtailq = TAILQ_HEAD_INITIALIZER(swtailq);
150 static struct swdevt *swdevhd; /* Allocate from here next */
151 static int nswapdev; /* Number of swap devices */
152 int swap_pager_avail;
153 static struct sx swdev_syscall_lock; /* serialize swap(on|off) */
155 static vm_ooffset_t swap_total;
156 SYSCTL_QUAD(_vm, OID_AUTO, swap_total, CTLFLAG_RD, &swap_total, 0,
157 "Total amount of available swap storage.");
158 static vm_ooffset_t swap_reserved;
159 SYSCTL_QUAD(_vm, OID_AUTO, swap_reserved, CTLFLAG_RD, &swap_reserved, 0,
160 "Amount of swap storage needed to back all allocated anonymous memory.");
161 static int overcommit = 0;
162 SYSCTL_INT(_vm, VM_OVERCOMMIT, overcommit, CTLFLAG_RW, &overcommit, 0,
163 "Configure virtual memory overcommit behavior. See tuning(7) "
165 static unsigned long swzone;
166 SYSCTL_ULONG(_vm, OID_AUTO, swzone, CTLFLAG_RD, &swzone, 0,
167 "Actual size of swap metadata zone");
168 static unsigned long swap_maxpages;
169 SYSCTL_ULONG(_vm, OID_AUTO, swap_maxpages, CTLFLAG_RD, &swap_maxpages, 0,
170 "Maximum amount of swap supported");
172 /* bits from overcommit */
173 #define SWAP_RESERVE_FORCE_ON (1 << 0)
174 #define SWAP_RESERVE_RLIMIT_ON (1 << 1)
175 #define SWAP_RESERVE_ALLOW_NONWIRED (1 << 2)
178 swap_reserve(vm_ooffset_t incr)
181 return (swap_reserve_by_cred(incr, curthread->td_ucred));
185 swap_reserve_by_cred(vm_ooffset_t incr, struct ucred *cred)
190 static struct timeval lastfail;
193 uip = cred->cr_ruidinfo;
195 if (incr & PAGE_MASK)
196 panic("swap_reserve: & PAGE_MASK");
201 error = racct_add(curproc, RACCT_SWAP, incr);
202 PROC_UNLOCK(curproc);
209 mtx_lock(&sw_dev_mtx);
210 r = swap_reserved + incr;
211 if (overcommit & SWAP_RESERVE_ALLOW_NONWIRED) {
212 s = vm_cnt.v_page_count - vm_cnt.v_free_reserved - vm_cnt.v_wire_count;
217 if ((overcommit & SWAP_RESERVE_FORCE_ON) == 0 || r <= s ||
218 (error = priv_check(curthread, PRIV_VM_SWAP_NOQUOTA)) == 0) {
222 mtx_unlock(&sw_dev_mtx);
225 UIDINFO_VMSIZE_LOCK(uip);
226 if ((overcommit & SWAP_RESERVE_RLIMIT_ON) != 0 &&
227 uip->ui_vmsize + incr > lim_cur(curthread, RLIMIT_SWAP) &&
228 priv_check(curthread, PRIV_VM_SWAP_NORLIMIT))
231 uip->ui_vmsize += incr;
232 UIDINFO_VMSIZE_UNLOCK(uip);
234 mtx_lock(&sw_dev_mtx);
235 swap_reserved -= incr;
236 mtx_unlock(&sw_dev_mtx);
239 if (!res && ppsratecheck(&lastfail, &curfail, 1)) {
240 printf("uid %d, pid %d: swap reservation for %jd bytes failed\n",
241 uip->ui_uid, curproc->p_pid, incr);
247 racct_sub(curproc, RACCT_SWAP, incr);
248 PROC_UNLOCK(curproc);
256 swap_reserve_force(vm_ooffset_t incr)
260 mtx_lock(&sw_dev_mtx);
261 swap_reserved += incr;
262 mtx_unlock(&sw_dev_mtx);
266 racct_add_force(curproc, RACCT_SWAP, incr);
267 PROC_UNLOCK(curproc);
270 uip = curthread->td_ucred->cr_ruidinfo;
272 UIDINFO_VMSIZE_LOCK(uip);
273 uip->ui_vmsize += incr;
274 UIDINFO_VMSIZE_UNLOCK(uip);
275 PROC_UNLOCK(curproc);
279 swap_release(vm_ooffset_t decr)
284 cred = curthread->td_ucred;
285 swap_release_by_cred(decr, cred);
286 PROC_UNLOCK(curproc);
290 swap_release_by_cred(vm_ooffset_t decr, struct ucred *cred)
294 uip = cred->cr_ruidinfo;
296 if (decr & PAGE_MASK)
297 panic("swap_release: & PAGE_MASK");
299 mtx_lock(&sw_dev_mtx);
300 if (swap_reserved < decr)
301 panic("swap_reserved < decr");
302 swap_reserved -= decr;
303 mtx_unlock(&sw_dev_mtx);
305 UIDINFO_VMSIZE_LOCK(uip);
306 if (uip->ui_vmsize < decr)
307 printf("negative vmsize for uid = %d\n", uip->ui_uid);
308 uip->ui_vmsize -= decr;
309 UIDINFO_VMSIZE_UNLOCK(uip);
311 racct_sub_cred(cred, RACCT_SWAP, decr);
314 #define SWM_FREE 0x02 /* free, period */
315 #define SWM_POP 0x04 /* pop out */
317 static int swap_pager_full = 2; /* swap space exhaustion (task killing) */
318 static int swap_pager_almost_full = 1; /* swap space exhaustion (w/hysteresis)*/
319 static int nsw_rcount; /* free read buffers */
320 static int nsw_wcount_sync; /* limit write buffers / synchronous */
321 static int nsw_wcount_async; /* limit write buffers / asynchronous */
322 static int nsw_wcount_async_max;/* assigned maximum */
323 static int nsw_cluster_max; /* maximum VOP I/O allowed */
325 static int sysctl_swap_async_max(SYSCTL_HANDLER_ARGS);
326 SYSCTL_PROC(_vm, OID_AUTO, swap_async_max, CTLTYPE_INT | CTLFLAG_RW |
327 CTLFLAG_MPSAFE, NULL, 0, sysctl_swap_async_max, "I",
328 "Maximum running async swap ops");
329 static int sysctl_swap_fragmentation(SYSCTL_HANDLER_ARGS);
330 SYSCTL_PROC(_vm, OID_AUTO, swap_fragmentation, CTLTYPE_STRING | CTLFLAG_RD |
331 CTLFLAG_MPSAFE, NULL, 0, sysctl_swap_fragmentation, "A",
332 "Swap Fragmentation Info");
334 static struct sx sw_alloc_sx;
337 * "named" and "unnamed" anon region objects. Try to reduce the overhead
338 * of searching a named list by hashing it just a little.
343 #define NOBJLIST(handle) \
344 (&swap_pager_object_list[((int)(intptr_t)handle >> 4) & (NOBJLISTS-1)])
346 static struct pagerlst swap_pager_object_list[NOBJLISTS];
347 static uma_zone_t swblk_zone;
348 static uma_zone_t swpctrie_zone;
351 * pagerops for OBJT_SWAP - "swap pager". Some ops are also global procedure
352 * calls hooked from other parts of the VM system and do not appear here.
353 * (see vm/swap_pager.h).
356 swap_pager_alloc(void *handle, vm_ooffset_t size,
357 vm_prot_t prot, vm_ooffset_t offset, struct ucred *);
358 static void swap_pager_dealloc(vm_object_t object);
359 static int swap_pager_getpages(vm_object_t, vm_page_t *, int, int *,
361 static int swap_pager_getpages_async(vm_object_t, vm_page_t *, int, int *,
362 int *, pgo_getpages_iodone_t, void *);
363 static void swap_pager_putpages(vm_object_t, vm_page_t *, int, boolean_t, int *);
365 swap_pager_haspage(vm_object_t object, vm_pindex_t pindex, int *before, int *after);
366 static void swap_pager_init(void);
367 static void swap_pager_unswapped(vm_page_t);
368 static void swap_pager_swapoff(struct swdevt *sp);
370 struct pagerops swappagerops = {
371 .pgo_init = swap_pager_init, /* early system initialization of pager */
372 .pgo_alloc = swap_pager_alloc, /* allocate an OBJT_SWAP object */
373 .pgo_dealloc = swap_pager_dealloc, /* deallocate an OBJT_SWAP object */
374 .pgo_getpages = swap_pager_getpages, /* pagein */
375 .pgo_getpages_async = swap_pager_getpages_async, /* pagein (async) */
376 .pgo_putpages = swap_pager_putpages, /* pageout */
377 .pgo_haspage = swap_pager_haspage, /* get backing store status for page */
378 .pgo_pageunswapped = swap_pager_unswapped, /* remove swap related to page */
382 * swap_*() routines are externally accessible. swp_*() routines are
385 static int nswap_lowat = 128; /* in pages, swap_pager_almost_full warn */
386 static int nswap_hiwat = 512; /* in pages, swap_pager_almost_full warn */
388 SYSCTL_INT(_vm, OID_AUTO, dmmax, CTLFLAG_RD, &nsw_cluster_max, 0,
389 "Maximum size of a swap block in pages");
391 static void swp_sizecheck(void);
392 static void swp_pager_async_iodone(struct buf *bp);
393 static bool swp_pager_swblk_empty(struct swblk *sb, int start, int limit);
394 static int swapongeom(struct vnode *);
395 static int swaponvp(struct thread *, struct vnode *, u_long);
396 static int swapoff_one(struct swdevt *sp, struct ucred *cred);
399 * Swap bitmap functions
401 static void swp_pager_freeswapspace(daddr_t blk, daddr_t npages);
402 static daddr_t swp_pager_getswapspace(int npages);
407 static void swp_pager_meta_build(vm_object_t, vm_pindex_t, daddr_t);
408 static void swp_pager_meta_free(vm_object_t, vm_pindex_t, vm_pindex_t);
409 static void swp_pager_meta_free_all(vm_object_t);
410 static daddr_t swp_pager_meta_ctl(vm_object_t, vm_pindex_t, int);
413 swblk_trie_alloc(struct pctrie *ptree)
416 return (uma_zalloc(swpctrie_zone, M_NOWAIT | (curproc == pageproc ?
417 M_USE_RESERVE : 0)));
421 swblk_trie_free(struct pctrie *ptree, void *node)
424 uma_zfree(swpctrie_zone, node);
427 PCTRIE_DEFINE(SWAP, swblk, p, swblk_trie_alloc, swblk_trie_free);
430 * SWP_SIZECHECK() - update swap_pager_full indication
432 * update the swap_pager_almost_full indication and warn when we are
433 * about to run out of swap space, using lowat/hiwat hysteresis.
435 * Clear swap_pager_full ( task killing ) indication when lowat is met.
437 * No restrictions on call
438 * This routine may not block.
444 if (swap_pager_avail < nswap_lowat) {
445 if (swap_pager_almost_full == 0) {
446 printf("swap_pager: out of swap space\n");
447 swap_pager_almost_full = 1;
451 if (swap_pager_avail > nswap_hiwat)
452 swap_pager_almost_full = 0;
457 * SWAP_PAGER_INIT() - initialize the swap pager!
459 * Expected to be started from system init. NOTE: This code is run
460 * before much else so be careful what you depend on. Most of the VM
461 * system has yet to be initialized at this point.
464 swap_pager_init(void)
467 * Initialize object lists
471 for (i = 0; i < NOBJLISTS; ++i)
472 TAILQ_INIT(&swap_pager_object_list[i]);
473 mtx_init(&sw_dev_mtx, "swapdev", NULL, MTX_DEF);
474 sx_init(&sw_alloc_sx, "swspsx");
475 sx_init(&swdev_syscall_lock, "swsysc");
479 * SWAP_PAGER_SWAP_INIT() - swap pager initialization from pageout process
481 * Expected to be started from pageout process once, prior to entering
485 swap_pager_swap_init(void)
490 * Number of in-transit swap bp operations. Don't
491 * exhaust the pbufs completely. Make sure we
492 * initialize workable values (0 will work for hysteresis
493 * but it isn't very efficient).
495 * The nsw_cluster_max is constrained by the bp->b_pages[]
496 * array (MAXPHYS/PAGE_SIZE) and our locally defined
497 * MAX_PAGEOUT_CLUSTER. Also be aware that swap ops are
498 * constrained by the swap device interleave stripe size.
500 * Currently we hardwire nsw_wcount_async to 4. This limit is
501 * designed to prevent other I/O from having high latencies due to
502 * our pageout I/O. The value 4 works well for one or two active swap
503 * devices but is probably a little low if you have more. Even so,
504 * a higher value would probably generate only a limited improvement
505 * with three or four active swap devices since the system does not
506 * typically have to pageout at extreme bandwidths. We will want
507 * at least 2 per swap devices, and 4 is a pretty good value if you
508 * have one NFS swap device due to the command/ack latency over NFS.
509 * So it all works out pretty well.
511 nsw_cluster_max = min((MAXPHYS/PAGE_SIZE), MAX_PAGEOUT_CLUSTER);
514 nsw_rcount = (nswbuf + 1) / 2;
515 nsw_wcount_sync = (nswbuf + 3) / 4;
516 nsw_wcount_async = 4;
517 nsw_wcount_async_max = nsw_wcount_async;
518 mtx_unlock(&pbuf_mtx);
521 * Initialize our zone, guessing on the number we need based
522 * on the number of pages in the system.
524 n = vm_cnt.v_page_count / 2;
525 if (maxswzone && n > maxswzone / sizeof(struct swblk))
526 n = maxswzone / sizeof(struct swblk);
527 swpctrie_zone = uma_zcreate("swpctrie", pctrie_node_size(), NULL, NULL,
528 pctrie_zone_init, NULL, UMA_ALIGN_PTR,
529 UMA_ZONE_NOFREE | UMA_ZONE_VM);
530 if (swpctrie_zone == NULL)
531 panic("failed to create swap pctrie zone.");
532 swblk_zone = uma_zcreate("swblk", sizeof(struct swblk), NULL, NULL,
533 NULL, NULL, _Alignof(struct swblk) - 1,
534 UMA_ZONE_NOFREE | UMA_ZONE_VM);
535 if (swblk_zone == NULL)
536 panic("failed to create swap blk zone.");
539 if (uma_zone_reserve_kva(swblk_zone, n))
542 * if the allocation failed, try a zone two thirds the
543 * size of the previous attempt.
549 * Often uma_zone_reserve_kva() cannot reserve exactly the
550 * requested size. Account for the difference when
551 * calculating swap_maxpages.
553 n = uma_zone_get_max(swblk_zone);
556 printf("Swap blk zone entries reduced from %lu to %lu.\n",
558 swap_maxpages = n * SWAP_META_PAGES;
559 swzone = n * sizeof(struct swblk);
560 if (!uma_zone_reserve_kva(swpctrie_zone, n))
561 printf("Cannot reserve swap pctrie zone, "
562 "reduce kern.maxswzone.\n");
566 swap_pager_alloc_init(void *handle, struct ucred *cred, vm_ooffset_t size,
572 if (!swap_reserve_by_cred(size, cred))
578 * The un_pager.swp.swp_blks trie is initialized by
579 * vm_object_allocate() to ensure the correct order of
580 * visibility to other threads.
582 object = vm_object_allocate(OBJT_SWAP, OFF_TO_IDX(offset +
585 object->handle = handle;
588 object->charge = size;
594 * SWAP_PAGER_ALLOC() - allocate a new OBJT_SWAP VM object and instantiate
595 * its metadata structures.
597 * This routine is called from the mmap and fork code to create a new
600 * This routine must ensure that no live duplicate is created for
601 * the named object request, which is protected against by
602 * holding the sw_alloc_sx lock in case handle != NULL.
605 swap_pager_alloc(void *handle, vm_ooffset_t size, vm_prot_t prot,
606 vm_ooffset_t offset, struct ucred *cred)
610 if (handle != NULL) {
612 * Reference existing named region or allocate new one. There
613 * should not be a race here against swp_pager_meta_build()
614 * as called from vm_page_remove() in regards to the lookup
617 sx_xlock(&sw_alloc_sx);
618 object = vm_pager_object_lookup(NOBJLIST(handle), handle);
619 if (object == NULL) {
620 object = swap_pager_alloc_init(handle, cred, size,
622 if (object != NULL) {
623 TAILQ_INSERT_TAIL(NOBJLIST(object->handle),
624 object, pager_object_list);
627 sx_xunlock(&sw_alloc_sx);
629 object = swap_pager_alloc_init(handle, cred, size, offset);
635 * SWAP_PAGER_DEALLOC() - remove swap metadata from object
637 * The swap backing for the object is destroyed. The code is
638 * designed such that we can reinstantiate it later, but this
639 * routine is typically called only when the entire object is
640 * about to be destroyed.
642 * The object must be locked.
645 swap_pager_dealloc(vm_object_t object)
648 VM_OBJECT_ASSERT_WLOCKED(object);
649 KASSERT((object->flags & OBJ_DEAD) != 0, ("dealloc of reachable obj"));
652 * Remove from list right away so lookups will fail if we block for
653 * pageout completion.
655 if (object->handle != NULL) {
656 VM_OBJECT_WUNLOCK(object);
657 sx_xlock(&sw_alloc_sx);
658 TAILQ_REMOVE(NOBJLIST(object->handle), object,
660 sx_xunlock(&sw_alloc_sx);
661 VM_OBJECT_WLOCK(object);
664 vm_object_pip_wait(object, "swpdea");
667 * Free all remaining metadata. We only bother to free it from
668 * the swap meta data. We do not attempt to free swapblk's still
669 * associated with vm_page_t's for this object. We do not care
670 * if paging is still in progress on some objects.
672 swp_pager_meta_free_all(object);
673 object->handle = NULL;
674 object->type = OBJT_DEAD;
677 /************************************************************************
678 * SWAP PAGER BITMAP ROUTINES *
679 ************************************************************************/
682 * SWP_PAGER_GETSWAPSPACE() - allocate raw swap space
684 * Allocate swap for the requested number of pages. The starting
685 * swap block number (a page index) is returned or SWAPBLK_NONE
686 * if the allocation failed.
688 * Also has the side effect of advising that somebody made a mistake
689 * when they configured swap and didn't configure enough.
691 * This routine may not sleep.
693 * We allocate in round-robin fashion from the configured devices.
696 swp_pager_getswapspace(int npages)
703 mtx_lock(&sw_dev_mtx);
705 for (i = 0; i < nswapdev; i++) {
707 sp = TAILQ_FIRST(&swtailq);
708 if (!(sp->sw_flags & SW_CLOSING)) {
709 blk = blist_alloc(sp->sw_blist, npages);
710 if (blk != SWAPBLK_NONE) {
712 sp->sw_used += npages;
713 swap_pager_avail -= npages;
715 swdevhd = TAILQ_NEXT(sp, sw_list);
719 sp = TAILQ_NEXT(sp, sw_list);
721 if (swap_pager_full != 2) {
722 printf("swap_pager_getswapspace(%d): failed\n", npages);
724 swap_pager_almost_full = 1;
728 mtx_unlock(&sw_dev_mtx);
733 swp_pager_isondev(daddr_t blk, struct swdevt *sp)
736 return (blk >= sp->sw_first && blk < sp->sw_end);
740 swp_pager_strategy(struct buf *bp)
744 mtx_lock(&sw_dev_mtx);
745 TAILQ_FOREACH(sp, &swtailq, sw_list) {
746 if (bp->b_blkno >= sp->sw_first && bp->b_blkno < sp->sw_end) {
747 mtx_unlock(&sw_dev_mtx);
748 if ((sp->sw_flags & SW_UNMAPPED) != 0 &&
749 unmapped_buf_allowed) {
750 bp->b_data = unmapped_buf;
753 pmap_qenter((vm_offset_t)bp->b_data,
754 &bp->b_pages[0], bp->b_bcount / PAGE_SIZE);
756 sp->sw_strategy(bp, sp);
760 panic("Swapdev not found");
765 * SWP_PAGER_FREESWAPSPACE() - free raw swap space
767 * This routine returns the specified swap blocks back to the bitmap.
769 * This routine may not sleep.
772 swp_pager_freeswapspace(daddr_t blk, daddr_t npages)
778 mtx_lock(&sw_dev_mtx);
779 TAILQ_FOREACH(sp, &swtailq, sw_list) {
780 if (blk >= sp->sw_first && blk < sp->sw_end) {
781 sp->sw_used -= npages;
783 * If we are attempting to stop swapping on
784 * this device, we don't want to mark any
785 * blocks free lest they be reused.
787 if ((sp->sw_flags & SW_CLOSING) == 0) {
788 blist_free(sp->sw_blist, blk - sp->sw_first,
790 swap_pager_avail += npages;
793 mtx_unlock(&sw_dev_mtx);
797 panic("Swapdev not found");
801 * SYSCTL_SWAP_FRAGMENTATION() - produce raw swap space stats
804 sysctl_swap_fragmentation(SYSCTL_HANDLER_ARGS)
811 error = sysctl_wire_old_buffer(req, 0);
814 sbuf_new_for_sysctl(&sbuf, NULL, 128, req);
815 mtx_lock(&sw_dev_mtx);
816 TAILQ_FOREACH(sp, &swtailq, sw_list) {
817 if (vn_isdisk(sp->sw_vp, NULL))
818 devname = devtoname(sp->sw_vp->v_rdev);
821 sbuf_printf(&sbuf, "\nFree space on device %s:\n", devname);
822 blist_stats(sp->sw_blist, &sbuf);
824 mtx_unlock(&sw_dev_mtx);
825 error = sbuf_finish(&sbuf);
831 * SWAP_PAGER_FREESPACE() - frees swap blocks associated with a page
832 * range within an object.
834 * This is a globally accessible routine.
836 * This routine removes swapblk assignments from swap metadata.
838 * The external callers of this routine typically have already destroyed
839 * or renamed vm_page_t's associated with this range in the object so
842 * The object must be locked.
845 swap_pager_freespace(vm_object_t object, vm_pindex_t start, vm_size_t size)
848 swp_pager_meta_free(object, start, size);
852 * SWAP_PAGER_RESERVE() - reserve swap blocks in object
854 * Assigns swap blocks to the specified range within the object. The
855 * swap blocks are not zeroed. Any previous swap assignment is destroyed.
857 * Returns 0 on success, -1 on failure.
860 swap_pager_reserve(vm_object_t object, vm_pindex_t start, vm_size_t size)
863 daddr_t blk = SWAPBLK_NONE;
864 vm_pindex_t beg = start; /* save start index */
866 VM_OBJECT_WLOCK(object);
870 while ((blk = swp_pager_getswapspace(n)) == SWAPBLK_NONE) {
873 swp_pager_meta_free(object, beg, start - beg);
874 VM_OBJECT_WUNLOCK(object);
879 swp_pager_meta_build(object, start, blk);
885 swp_pager_meta_free(object, start, n);
886 VM_OBJECT_WUNLOCK(object);
891 * SWAP_PAGER_COPY() - copy blocks from source pager to destination pager
892 * and destroy the source.
894 * Copy any valid swapblks from the source to the destination. In
895 * cases where both the source and destination have a valid swapblk,
896 * we keep the destination's.
898 * This routine is allowed to sleep. It may sleep allocating metadata
899 * indirectly through swp_pager_meta_build() or if paging is still in
900 * progress on the source.
902 * The source object contains no vm_page_t's (which is just as well)
904 * The source object is of type OBJT_SWAP.
906 * The source and destination objects must be locked.
907 * Both object locks may temporarily be released.
910 swap_pager_copy(vm_object_t srcobject, vm_object_t dstobject,
911 vm_pindex_t offset, int destroysource)
915 VM_OBJECT_ASSERT_WLOCKED(srcobject);
916 VM_OBJECT_ASSERT_WLOCKED(dstobject);
919 * If destroysource is set, we remove the source object from the
920 * swap_pager internal queue now.
922 if (destroysource && srcobject->handle != NULL) {
923 vm_object_pip_add(srcobject, 1);
924 VM_OBJECT_WUNLOCK(srcobject);
925 vm_object_pip_add(dstobject, 1);
926 VM_OBJECT_WUNLOCK(dstobject);
927 sx_xlock(&sw_alloc_sx);
928 TAILQ_REMOVE(NOBJLIST(srcobject->handle), srcobject,
930 sx_xunlock(&sw_alloc_sx);
931 VM_OBJECT_WLOCK(dstobject);
932 vm_object_pip_wakeup(dstobject);
933 VM_OBJECT_WLOCK(srcobject);
934 vm_object_pip_wakeup(srcobject);
938 * transfer source to destination.
940 for (i = 0; i < dstobject->size; ++i) {
944 * Locate (without changing) the swapblk on the destination,
945 * unless it is invalid in which case free it silently, or
946 * if the destination is a resident page, in which case the
947 * source is thrown away.
949 dstaddr = swp_pager_meta_ctl(dstobject, i, 0);
951 if (dstaddr == SWAPBLK_NONE) {
953 * Destination has no swapblk and is not resident,
958 srcaddr = swp_pager_meta_ctl(
964 if (srcaddr != SWAPBLK_NONE) {
966 * swp_pager_meta_build() can sleep.
968 vm_object_pip_add(srcobject, 1);
969 VM_OBJECT_WUNLOCK(srcobject);
970 vm_object_pip_add(dstobject, 1);
971 swp_pager_meta_build(dstobject, i, srcaddr);
972 vm_object_pip_wakeup(dstobject);
973 VM_OBJECT_WLOCK(srcobject);
974 vm_object_pip_wakeup(srcobject);
978 * Destination has valid swapblk or it is represented
979 * by a resident page. We destroy the sourceblock.
982 swp_pager_meta_ctl(srcobject, i + offset, SWM_FREE);
987 * Free left over swap blocks in source.
989 * We have to revert the type to OBJT_DEFAULT so we do not accidentally
990 * double-remove the object from the swap queues.
993 swp_pager_meta_free_all(srcobject);
995 * Reverting the type is not necessary, the caller is going
996 * to destroy srcobject directly, but I'm doing it here
997 * for consistency since we've removed the object from its
1000 srcobject->type = OBJT_DEFAULT;
1005 * SWAP_PAGER_HASPAGE() - determine if we have good backing store for
1006 * the requested page.
1008 * We determine whether good backing store exists for the requested
1009 * page and return TRUE if it does, FALSE if it doesn't.
1011 * If TRUE, we also try to determine how much valid, contiguous backing
1012 * store exists before and after the requested page.
1015 swap_pager_haspage(vm_object_t object, vm_pindex_t pindex, int *before,
1021 VM_OBJECT_ASSERT_LOCKED(object);
1024 * do we have good backing store at the requested index ?
1026 blk0 = swp_pager_meta_ctl(object, pindex, 0);
1027 if (blk0 == SWAPBLK_NONE) {
1036 * find backwards-looking contiguous good backing store
1038 if (before != NULL) {
1039 for (i = 1; i < SWB_NPAGES; i++) {
1042 blk = swp_pager_meta_ctl(object, pindex - i, 0);
1043 if (blk != blk0 - i)
1050 * find forward-looking contiguous good backing store
1052 if (after != NULL) {
1053 for (i = 1; i < SWB_NPAGES; i++) {
1054 blk = swp_pager_meta_ctl(object, pindex + i, 0);
1055 if (blk != blk0 + i)
1064 * SWAP_PAGER_PAGE_UNSWAPPED() - remove swap backing store related to page
1066 * This removes any associated swap backing store, whether valid or
1067 * not, from the page.
1069 * This routine is typically called when a page is made dirty, at
1070 * which point any associated swap can be freed. MADV_FREE also
1071 * calls us in a special-case situation
1073 * NOTE!!! If the page is clean and the swap was valid, the caller
1074 * should make the page dirty before calling this routine. This routine
1075 * does NOT change the m->dirty status of the page. Also: MADV_FREE
1078 * This routine may not sleep.
1080 * The object containing the page must be locked.
1083 swap_pager_unswapped(vm_page_t m)
1086 swp_pager_meta_ctl(m->object, m->pindex, SWM_FREE);
1090 * swap_pager_getpages() - bring pages in from swap
1092 * Attempt to page in the pages in array "m" of length "count". The caller
1093 * may optionally specify that additional pages preceding and succeeding
1094 * the specified range be paged in. The number of such pages is returned
1095 * in the "rbehind" and "rahead" parameters, and they will be in the
1096 * inactive queue upon return.
1098 * The pages in "m" must be busied and will remain busied upon return.
1101 swap_pager_getpages(vm_object_t object, vm_page_t *m, int count, int *rbehind,
1105 vm_page_t mpred, msucc, p;
1108 int i, j, maxahead, maxbehind, reqcount, shift;
1112 VM_OBJECT_WUNLOCK(object);
1113 bp = getpbuf(&nsw_rcount);
1114 VM_OBJECT_WLOCK(object);
1116 if (!swap_pager_haspage(object, m[0]->pindex, &maxbehind, &maxahead)) {
1117 relpbuf(bp, &nsw_rcount);
1118 return (VM_PAGER_FAIL);
1122 * Clip the readahead and readbehind ranges to exclude resident pages.
1124 if (rahead != NULL) {
1125 KASSERT(reqcount - 1 <= maxahead,
1126 ("page count %d extends beyond swap block", reqcount));
1127 *rahead = imin(*rahead, maxahead - (reqcount - 1));
1128 pindex = m[reqcount - 1]->pindex;
1129 msucc = TAILQ_NEXT(m[reqcount - 1], listq);
1130 if (msucc != NULL && msucc->pindex - pindex - 1 < *rahead)
1131 *rahead = msucc->pindex - pindex - 1;
1133 if (rbehind != NULL) {
1134 *rbehind = imin(*rbehind, maxbehind);
1135 pindex = m[0]->pindex;
1136 mpred = TAILQ_PREV(m[0], pglist, listq);
1137 if (mpred != NULL && pindex - mpred->pindex - 1 < *rbehind)
1138 *rbehind = pindex - mpred->pindex - 1;
1142 * Allocate readahead and readbehind pages.
1144 shift = rbehind != NULL ? *rbehind : 0;
1146 for (i = 1; i <= shift; i++) {
1147 p = vm_page_alloc(object, m[0]->pindex - i,
1150 /* Shift allocated pages to the left. */
1151 for (j = 0; j < i - 1; j++)
1153 bp->b_pages[j + shift - i + 1];
1156 bp->b_pages[shift - i] = p;
1161 for (i = 0; i < reqcount; i++)
1162 bp->b_pages[i + shift] = m[i];
1163 if (rahead != NULL) {
1164 for (i = 0; i < *rahead; i++) {
1165 p = vm_page_alloc(object,
1166 m[reqcount - 1]->pindex + i + 1, VM_ALLOC_NORMAL);
1169 bp->b_pages[shift + reqcount + i] = p;
1173 if (rbehind != NULL)
1178 vm_object_pip_add(object, count);
1180 for (i = 0; i < count; i++)
1181 bp->b_pages[i]->oflags |= VPO_SWAPINPROG;
1183 pindex = bp->b_pages[0]->pindex;
1184 blk = swp_pager_meta_ctl(object, pindex, 0);
1185 KASSERT(blk != SWAPBLK_NONE,
1186 ("no swap blocking containing %p(%jx)", object, (uintmax_t)pindex));
1188 VM_OBJECT_WUNLOCK(object);
1190 bp->b_flags |= B_PAGING;
1191 bp->b_iocmd = BIO_READ;
1192 bp->b_iodone = swp_pager_async_iodone;
1193 bp->b_rcred = crhold(thread0.td_ucred);
1194 bp->b_wcred = crhold(thread0.td_ucred);
1196 bp->b_bcount = PAGE_SIZE * count;
1197 bp->b_bufsize = PAGE_SIZE * count;
1198 bp->b_npages = count;
1199 bp->b_pgbefore = rbehind != NULL ? *rbehind : 0;
1200 bp->b_pgafter = rahead != NULL ? *rahead : 0;
1202 VM_CNT_INC(v_swapin);
1203 VM_CNT_ADD(v_swappgsin, count);
1206 * perform the I/O. NOTE!!! bp cannot be considered valid after
1207 * this point because we automatically release it on completion.
1208 * Instead, we look at the one page we are interested in which we
1209 * still hold a lock on even through the I/O completion.
1211 * The other pages in our m[] array are also released on completion,
1212 * so we cannot assume they are valid anymore either.
1214 * NOTE: b_blkno is destroyed by the call to swapdev_strategy
1217 swp_pager_strategy(bp);
1220 * Wait for the pages we want to complete. VPO_SWAPINPROG is always
1221 * cleared on completion. If an I/O error occurs, SWAPBLK_NONE
1222 * is set in the metadata for each page in the request.
1224 VM_OBJECT_WLOCK(object);
1225 while ((m[0]->oflags & VPO_SWAPINPROG) != 0) {
1226 m[0]->oflags |= VPO_SWAPSLEEP;
1227 VM_CNT_INC(v_intrans);
1228 if (VM_OBJECT_SLEEP(object, &object->paging_in_progress, PSWP,
1229 "swread", hz * 20)) {
1231 "swap_pager: indefinite wait buffer: bufobj: %p, blkno: %jd, size: %ld\n",
1232 bp->b_bufobj, (intmax_t)bp->b_blkno, bp->b_bcount);
1237 * If we had an unrecoverable read error pages will not be valid.
1239 for (i = 0; i < reqcount; i++)
1240 if (m[i]->valid != VM_PAGE_BITS_ALL)
1241 return (VM_PAGER_ERROR);
1243 return (VM_PAGER_OK);
1246 * A final note: in a low swap situation, we cannot deallocate swap
1247 * and mark a page dirty here because the caller is likely to mark
1248 * the page clean when we return, causing the page to possibly revert
1249 * to all-zero's later.
1254 * swap_pager_getpages_async():
1256 * Right now this is emulation of asynchronous operation on top of
1257 * swap_pager_getpages().
1260 swap_pager_getpages_async(vm_object_t object, vm_page_t *m, int count,
1261 int *rbehind, int *rahead, pgo_getpages_iodone_t iodone, void *arg)
1265 r = swap_pager_getpages(object, m, count, rbehind, rahead);
1266 VM_OBJECT_WUNLOCK(object);
1271 case VM_PAGER_ERROR:
1278 panic("unhandled swap_pager_getpages() error %d", r);
1280 (iodone)(arg, m, count, error);
1281 VM_OBJECT_WLOCK(object);
1287 * swap_pager_putpages:
1289 * Assign swap (if necessary) and initiate I/O on the specified pages.
1291 * We support both OBJT_DEFAULT and OBJT_SWAP objects. DEFAULT objects
1292 * are automatically converted to SWAP objects.
1294 * In a low memory situation we may block in VOP_STRATEGY(), but the new
1295 * vm_page reservation system coupled with properly written VFS devices
1296 * should ensure that no low-memory deadlock occurs. This is an area
1299 * The parent has N vm_object_pip_add() references prior to
1300 * calling us and will remove references for rtvals[] that are
1301 * not set to VM_PAGER_PEND. We need to remove the rest on I/O
1304 * The parent has soft-busy'd the pages it passes us and will unbusy
1305 * those whos rtvals[] entry is not set to VM_PAGER_PEND on return.
1306 * We need to unbusy the rest on I/O completion.
1309 swap_pager_putpages(vm_object_t object, vm_page_t *m, int count,
1310 int flags, int *rtvals)
1315 if (count && m[0]->object != object) {
1316 panic("swap_pager_putpages: object mismatch %p/%p",
1325 * Turn object into OBJT_SWAP
1326 * check for bogus sysops
1327 * force sync if not pageout process
1329 if (object->type != OBJT_SWAP)
1330 swp_pager_meta_build(object, 0, SWAPBLK_NONE);
1331 VM_OBJECT_WUNLOCK(object);
1334 if (curproc != pageproc)
1337 sync = (flags & VM_PAGER_PUT_SYNC) != 0;
1342 * Assign swap blocks and issue I/O. We reallocate swap on the fly.
1343 * The page is left dirty until the pageout operation completes
1346 for (i = 0; i < count; i += n) {
1352 * Maximum I/O size is limited by a number of factors.
1354 n = min(BLIST_MAX_ALLOC, count - i);
1355 n = min(n, nsw_cluster_max);
1358 * Get biggest block of swap we can. If we fail, fall
1359 * back and try to allocate a smaller block. Don't go
1360 * overboard trying to allocate space if it would overly
1364 (blk = swp_pager_getswapspace(n)) == SWAPBLK_NONE &&
1369 if (blk == SWAPBLK_NONE) {
1370 for (j = 0; j < n; ++j)
1371 rtvals[i+j] = VM_PAGER_FAIL;
1376 * All I/O parameters have been satisfied, build the I/O
1377 * request and assign the swap space.
1380 bp = getpbuf(&nsw_wcount_sync);
1382 bp = getpbuf(&nsw_wcount_async);
1383 bp->b_flags = B_ASYNC;
1385 bp->b_flags |= B_PAGING;
1386 bp->b_iocmd = BIO_WRITE;
1388 bp->b_rcred = crhold(thread0.td_ucred);
1389 bp->b_wcred = crhold(thread0.td_ucred);
1390 bp->b_bcount = PAGE_SIZE * n;
1391 bp->b_bufsize = PAGE_SIZE * n;
1394 VM_OBJECT_WLOCK(object);
1395 for (j = 0; j < n; ++j) {
1396 vm_page_t mreq = m[i+j];
1398 swp_pager_meta_build(
1403 MPASS(mreq->dirty == VM_PAGE_BITS_ALL);
1404 mreq->oflags |= VPO_SWAPINPROG;
1405 bp->b_pages[j] = mreq;
1407 VM_OBJECT_WUNLOCK(object);
1410 * Must set dirty range for NFS to work.
1413 bp->b_dirtyend = bp->b_bcount;
1415 VM_CNT_INC(v_swapout);
1416 VM_CNT_ADD(v_swappgsout, bp->b_npages);
1419 * We unconditionally set rtvals[] to VM_PAGER_PEND so that we
1420 * can call the async completion routine at the end of a
1421 * synchronous I/O operation. Otherwise, our caller would
1422 * perform duplicate unbusy and wakeup operations on the page
1423 * and object, respectively.
1425 for (j = 0; j < n; j++)
1426 rtvals[i + j] = VM_PAGER_PEND;
1431 * NOTE: b_blkno is destroyed by the call to swapdev_strategy
1433 if (sync == FALSE) {
1434 bp->b_iodone = swp_pager_async_iodone;
1436 swp_pager_strategy(bp);
1443 * NOTE: b_blkno is destroyed by the call to swapdev_strategy
1445 bp->b_iodone = bdone;
1446 swp_pager_strategy(bp);
1449 * Wait for the sync I/O to complete.
1451 bwait(bp, PVM, "swwrt");
1454 * Now that we are through with the bp, we can call the
1455 * normal async completion, which frees everything up.
1457 swp_pager_async_iodone(bp);
1459 VM_OBJECT_WLOCK(object);
1463 * swp_pager_async_iodone:
1465 * Completion routine for asynchronous reads and writes from/to swap.
1466 * Also called manually by synchronous code to finish up a bp.
1468 * This routine may not sleep.
1471 swp_pager_async_iodone(struct buf *bp)
1474 vm_object_t object = NULL;
1479 if (bp->b_ioflags & BIO_ERROR) {
1481 "swap_pager: I/O error - %s failed; blkno %ld,"
1482 "size %ld, error %d\n",
1483 ((bp->b_iocmd == BIO_READ) ? "pagein" : "pageout"),
1491 * remove the mapping for kernel virtual
1494 pmap_qremove((vm_offset_t)bp->b_data, bp->b_npages);
1496 bp->b_data = bp->b_kvabase;
1499 object = bp->b_pages[0]->object;
1500 VM_OBJECT_WLOCK(object);
1504 * cleanup pages. If an error occurs writing to swap, we are in
1505 * very serious trouble. If it happens to be a disk error, though,
1506 * we may be able to recover by reassigning the swap later on. So
1507 * in this case we remove the m->swapblk assignment for the page
1508 * but do not free it in the rlist. The errornous block(s) are thus
1509 * never reallocated as swap. Redirty the page and continue.
1511 for (i = 0; i < bp->b_npages; ++i) {
1512 vm_page_t m = bp->b_pages[i];
1514 m->oflags &= ~VPO_SWAPINPROG;
1515 if (m->oflags & VPO_SWAPSLEEP) {
1516 m->oflags &= ~VPO_SWAPSLEEP;
1517 wakeup(&object->paging_in_progress);
1520 if (bp->b_ioflags & BIO_ERROR) {
1522 * If an error occurs I'd love to throw the swapblk
1523 * away without freeing it back to swapspace, so it
1524 * can never be used again. But I can't from an
1527 if (bp->b_iocmd == BIO_READ) {
1529 * NOTE: for reads, m->dirty will probably
1530 * be overridden by the original caller of
1531 * getpages so don't play cute tricks here.
1536 * If a write error occurs, reactivate page
1537 * so it doesn't clog the inactive list,
1538 * then finish the I/O.
1540 MPASS(m->dirty == VM_PAGE_BITS_ALL);
1542 vm_page_activate(m);
1546 } else if (bp->b_iocmd == BIO_READ) {
1548 * NOTE: for reads, m->dirty will probably be
1549 * overridden by the original caller of getpages so
1550 * we cannot set them in order to free the underlying
1551 * swap in a low-swap situation. I don't think we'd
1552 * want to do that anyway, but it was an optimization
1553 * that existed in the old swapper for a time before
1554 * it got ripped out due to precisely this problem.
1556 KASSERT(!pmap_page_is_mapped(m),
1557 ("swp_pager_async_iodone: page %p is mapped", m));
1558 KASSERT(m->dirty == 0,
1559 ("swp_pager_async_iodone: page %p is dirty", m));
1561 m->valid = VM_PAGE_BITS_ALL;
1562 if (i < bp->b_pgbefore ||
1563 i >= bp->b_npages - bp->b_pgafter)
1564 vm_page_readahead_finish(m);
1567 * For write success, clear the dirty
1568 * status, then finish the I/O ( which decrements the
1569 * busy count and possibly wakes waiter's up ).
1570 * A page is only written to swap after a period of
1571 * inactivity. Therefore, we do not expect it to be
1574 KASSERT(!pmap_page_is_write_mapped(m),
1575 ("swp_pager_async_iodone: page %p is not write"
1579 vm_page_deactivate_noreuse(m);
1586 * adjust pip. NOTE: the original parent may still have its own
1587 * pip refs on the object.
1589 if (object != NULL) {
1590 vm_object_pip_wakeupn(object, bp->b_npages);
1591 VM_OBJECT_WUNLOCK(object);
1595 * swapdev_strategy() manually sets b_vp and b_bufobj before calling
1596 * bstrategy(). Set them back to NULL now we're done with it, or we'll
1597 * trigger a KASSERT in relpbuf().
1601 bp->b_bufobj = NULL;
1604 * release the physical I/O buffer
1608 ((bp->b_iocmd == BIO_READ) ? &nsw_rcount :
1609 ((bp->b_flags & B_ASYNC) ?
1618 swap_pager_nswapdev(void)
1625 * SWP_PAGER_FORCE_PAGEIN() - force a swap block to be paged in
1627 * This routine dissociates the page at the given index within an object
1628 * from its backing store, paging it in if it does not reside in memory.
1629 * If the page is paged in, it is marked dirty and placed in the laundry
1630 * queue. The page is marked dirty because it no longer has backing
1631 * store. It is placed in the laundry queue because it has not been
1632 * accessed recently. Otherwise, it would already reside in memory.
1634 * We also attempt to swap in all other pages in the swap block.
1635 * However, we only guarantee that the one at the specified index is
1638 * XXX - The code to page the whole block in doesn't work, so we
1639 * revert to the one-by-one behavior for now. Sigh.
1642 swp_pager_force_pagein(vm_object_t object, vm_pindex_t pindex)
1646 vm_object_pip_add(object, 1);
1647 m = vm_page_grab(object, pindex, VM_ALLOC_NORMAL);
1648 if (m->valid == VM_PAGE_BITS_ALL) {
1649 vm_object_pip_wakeup(object);
1653 if (m->wire_count == 0 && m->queue == PQ_NONE)
1654 panic("page %p is neither wired nor queued", m);
1658 vm_pager_page_unswapped(m);
1662 if (swap_pager_getpages(object, &m, 1, NULL, NULL) != VM_PAGER_OK)
1663 panic("swap_pager_force_pagein: read from swap failed");/*XXX*/
1664 vm_object_pip_wakeup(object);
1670 vm_pager_page_unswapped(m);
1674 * swap_pager_swapoff:
1676 * Page in all of the pages that have been paged out to the
1677 * given device. The corresponding blocks in the bitmap must be
1678 * marked as allocated and the device must be flagged SW_CLOSING.
1679 * There may be no processes swapped out to the device.
1681 * This routine may block.
1684 swap_pager_swapoff(struct swdevt *sp)
1691 sx_assert(&swdev_syscall_lock, SA_XLOCKED);
1695 mtx_lock(&vm_object_list_mtx);
1696 TAILQ_FOREACH(object, &vm_object_list, object_list) {
1697 if (object->type != OBJT_SWAP)
1699 mtx_unlock(&vm_object_list_mtx);
1700 /* Depends on type-stability. */
1701 VM_OBJECT_WLOCK(object);
1704 * Dead objects are eventually terminated on their own.
1706 if ((object->flags & OBJ_DEAD) != 0)
1710 * Sync with fences placed after pctrie
1711 * initialization. We must not access pctrie below
1712 * unless we checked that our object is swap and not
1715 atomic_thread_fence_acq();
1716 if (object->type != OBJT_SWAP)
1719 for (pi = 0; (sb = SWAP_PCTRIE_LOOKUP_GE(
1720 &object->un_pager.swp.swp_blks, pi)) != NULL; ) {
1721 pi = sb->p + SWAP_META_PAGES;
1722 for (i = 0; i < SWAP_META_PAGES; i++) {
1723 if (sb->d[i] == SWAPBLK_NONE)
1725 if (swp_pager_isondev(sb->d[i], sp))
1726 swp_pager_force_pagein(object,
1731 VM_OBJECT_WUNLOCK(object);
1732 mtx_lock(&vm_object_list_mtx);
1734 mtx_unlock(&vm_object_list_mtx);
1738 * Objects may be locked or paging to the device being
1739 * removed, so we will miss their pages and need to
1740 * make another pass. We have marked this device as
1741 * SW_CLOSING, so the activity should finish soon.
1744 if (retries > 100) {
1745 panic("swapoff: failed to locate %d swap blocks",
1748 pause("swpoff", hz / 20);
1751 EVENTHANDLER_INVOKE(swapoff, sp);
1754 /************************************************************************
1756 ************************************************************************
1758 * These routines manipulate the swap metadata stored in the
1761 * Swap metadata is implemented with a global hash and not directly
1762 * linked into the object. Instead the object simply contains
1763 * appropriate tracking counters.
1767 * SWP_PAGER_SWBLK_EMPTY() - is a range of blocks free?
1770 swp_pager_swblk_empty(struct swblk *sb, int start, int limit)
1774 MPASS(0 <= start && start <= limit && limit <= SWAP_META_PAGES);
1775 for (i = start; i < limit; i++) {
1776 if (sb->d[i] != SWAPBLK_NONE)
1783 * SWP_PAGER_META_BUILD() - add swap block to swap meta data for object
1785 * We first convert the object to a swap object if it is a default
1788 * The specified swapblk is added to the object's swap metadata. If
1789 * the swapblk is not valid, it is freed instead. Any previously
1790 * assigned swapblk is freed.
1793 swp_pager_meta_build(vm_object_t object, vm_pindex_t pindex, daddr_t swapblk)
1795 static volatile int swblk_zone_exhausted, swpctrie_zone_exhausted;
1796 struct swblk *sb, *sb1;
1797 vm_pindex_t modpi, rdpi;
1800 VM_OBJECT_ASSERT_WLOCKED(object);
1803 * Convert default object to swap object if necessary
1805 if (object->type != OBJT_SWAP) {
1806 pctrie_init(&object->un_pager.swp.swp_blks);
1809 * Ensure that swap_pager_swapoff()'s iteration over
1810 * object_list does not see a garbage pctrie.
1812 atomic_thread_fence_rel();
1814 object->type = OBJT_SWAP;
1815 KASSERT(object->handle == NULL, ("default pager with handle"));
1818 rdpi = rounddown(pindex, SWAP_META_PAGES);
1819 sb = SWAP_PCTRIE_LOOKUP(&object->un_pager.swp.swp_blks, rdpi);
1821 if (swapblk == SWAPBLK_NONE)
1824 sb = uma_zalloc(swblk_zone, M_NOWAIT | (curproc ==
1825 pageproc ? M_USE_RESERVE : 0));
1828 for (i = 0; i < SWAP_META_PAGES; i++)
1829 sb->d[i] = SWAPBLK_NONE;
1830 if (atomic_cmpset_int(&swblk_zone_exhausted,
1832 printf("swblk zone ok\n");
1835 VM_OBJECT_WUNLOCK(object);
1836 if (uma_zone_exhausted(swblk_zone)) {
1837 if (atomic_cmpset_int(&swblk_zone_exhausted,
1839 printf("swap blk zone exhausted, "
1840 "increase kern.maxswzone\n");
1841 vm_pageout_oom(VM_OOM_SWAPZ);
1842 pause("swzonxb", 10);
1844 uma_zwait(swblk_zone);
1845 VM_OBJECT_WLOCK(object);
1846 sb = SWAP_PCTRIE_LOOKUP(&object->un_pager.swp.swp_blks,
1850 * Somebody swapped out a nearby page,
1851 * allocating swblk at the rdpi index,
1852 * while we dropped the object lock.
1857 error = SWAP_PCTRIE_INSERT(
1858 &object->un_pager.swp.swp_blks, sb);
1860 if (atomic_cmpset_int(&swpctrie_zone_exhausted,
1862 printf("swpctrie zone ok\n");
1865 VM_OBJECT_WUNLOCK(object);
1866 if (uma_zone_exhausted(swpctrie_zone)) {
1867 if (atomic_cmpset_int(&swpctrie_zone_exhausted,
1869 printf("swap pctrie zone exhausted, "
1870 "increase kern.maxswzone\n");
1871 vm_pageout_oom(VM_OOM_SWAPZ);
1872 pause("swzonxp", 10);
1874 uma_zwait(swpctrie_zone);
1875 VM_OBJECT_WLOCK(object);
1876 sb1 = SWAP_PCTRIE_LOOKUP(&object->un_pager.swp.swp_blks,
1879 uma_zfree(swblk_zone, sb);
1886 MPASS(sb->p == rdpi);
1888 modpi = pindex % SWAP_META_PAGES;
1889 /* Delete prior contents of metadata. */
1890 if (sb->d[modpi] != SWAPBLK_NONE)
1891 swp_pager_freeswapspace(sb->d[modpi], 1);
1892 /* Enter block into metadata. */
1893 sb->d[modpi] = swapblk;
1896 * Free the swblk if we end up with the empty page run.
1898 if (swapblk == SWAPBLK_NONE &&
1899 swp_pager_swblk_empty(sb, 0, SWAP_META_PAGES)) {
1900 SWAP_PCTRIE_REMOVE(&object->un_pager.swp.swp_blks, rdpi);
1901 uma_zfree(swblk_zone, sb);
1906 * SWP_PAGER_META_FREE() - free a range of blocks in the object's swap metadata
1908 * The requested range of blocks is freed, with any associated swap
1909 * returned to the swap bitmap.
1911 * This routine will free swap metadata structures as they are cleaned
1912 * out. This routine does *NOT* operate on swap metadata associated
1913 * with resident pages.
1916 swp_pager_meta_free(vm_object_t object, vm_pindex_t pindex, vm_pindex_t count)
1919 daddr_t first_free, num_free;
1921 int i, limit, start;
1923 VM_OBJECT_ASSERT_WLOCKED(object);
1924 if (object->type != OBJT_SWAP || count == 0)
1927 first_free = SWAPBLK_NONE;
1929 last = pindex + count;
1931 sb = SWAP_PCTRIE_LOOKUP_GE(&object->un_pager.swp.swp_blks,
1932 rounddown(pindex, SWAP_META_PAGES));
1933 if (sb == NULL || sb->p >= last)
1935 start = pindex > sb->p ? pindex - sb->p : 0;
1936 limit = last - sb->p < SWAP_META_PAGES ? last - sb->p :
1938 for (i = start; i < limit; i++) {
1939 if (sb->d[i] == SWAPBLK_NONE)
1941 if (first_free + num_free == sb->d[i])
1944 swp_pager_freeswapspace(first_free, num_free);
1945 first_free = sb->d[i];
1948 sb->d[i] = SWAPBLK_NONE;
1950 if (swp_pager_swblk_empty(sb, 0, start) &&
1951 swp_pager_swblk_empty(sb, limit, SWAP_META_PAGES)) {
1952 SWAP_PCTRIE_REMOVE(&object->un_pager.swp.swp_blks,
1954 uma_zfree(swblk_zone, sb);
1956 pindex = sb->p + SWAP_META_PAGES;
1958 swp_pager_freeswapspace(first_free, num_free);
1962 * SWP_PAGER_META_FREE_ALL() - destroy all swap metadata associated with object
1964 * This routine locates and destroys all swap metadata associated with
1968 swp_pager_meta_free_all(vm_object_t object)
1971 daddr_t first_free, num_free;
1975 VM_OBJECT_ASSERT_WLOCKED(object);
1976 if (object->type != OBJT_SWAP)
1979 first_free = SWAPBLK_NONE;
1981 for (pindex = 0; (sb = SWAP_PCTRIE_LOOKUP_GE(
1982 &object->un_pager.swp.swp_blks, pindex)) != NULL;) {
1983 pindex = sb->p + SWAP_META_PAGES;
1984 for (i = 0; i < SWAP_META_PAGES; i++) {
1985 if (sb->d[i] == SWAPBLK_NONE)
1987 if (first_free + num_free == sb->d[i])
1990 swp_pager_freeswapspace(first_free, num_free);
1991 first_free = sb->d[i];
1995 SWAP_PCTRIE_REMOVE(&object->un_pager.swp.swp_blks, sb->p);
1996 uma_zfree(swblk_zone, sb);
1998 swp_pager_freeswapspace(first_free, num_free);
2002 * SWP_PAGER_METACTL() - misc control of swap and vm_page_t meta data.
2004 * This routine is capable of looking up, popping, or freeing
2005 * swapblk assignments in the swap meta data or in the vm_page_t.
2006 * The routine typically returns the swapblk being looked-up, or popped,
2007 * or SWAPBLK_NONE if the block was freed, or SWAPBLK_NONE if the block
2008 * was invalid. This routine will automatically free any invalid
2009 * meta-data swapblks.
2011 * When acting on a busy resident page and paging is in progress, we
2012 * have to wait until paging is complete but otherwise can act on the
2015 * SWM_FREE remove and free swap block from metadata
2016 * SWM_POP remove from meta data but do not free.. pop it out
2019 swp_pager_meta_ctl(vm_object_t object, vm_pindex_t pindex, int flags)
2024 if ((flags & (SWM_FREE | SWM_POP)) != 0)
2025 VM_OBJECT_ASSERT_WLOCKED(object);
2027 VM_OBJECT_ASSERT_LOCKED(object);
2030 * The meta data only exists if the object is OBJT_SWAP
2031 * and even then might not be allocated yet.
2033 if (object->type != OBJT_SWAP)
2034 return (SWAPBLK_NONE);
2036 sb = SWAP_PCTRIE_LOOKUP(&object->un_pager.swp.swp_blks,
2037 rounddown(pindex, SWAP_META_PAGES));
2039 return (SWAPBLK_NONE);
2040 r1 = sb->d[pindex % SWAP_META_PAGES];
2041 if (r1 == SWAPBLK_NONE)
2042 return (SWAPBLK_NONE);
2043 if ((flags & (SWM_FREE | SWM_POP)) != 0) {
2044 sb->d[pindex % SWAP_META_PAGES] = SWAPBLK_NONE;
2045 if (swp_pager_swblk_empty(sb, 0, SWAP_META_PAGES)) {
2046 SWAP_PCTRIE_REMOVE(&object->un_pager.swp.swp_blks,
2047 rounddown(pindex, SWAP_META_PAGES));
2048 uma_zfree(swblk_zone, sb);
2051 if ((flags & SWM_FREE) != 0) {
2052 swp_pager_freeswapspace(r1, 1);
2059 * Returns the least page index which is greater than or equal to the
2060 * parameter pindex and for which there is a swap block allocated.
2061 * Returns object's size if the object's type is not swap or if there
2062 * are no allocated swap blocks for the object after the requested
2066 swap_pager_find_least(vm_object_t object, vm_pindex_t pindex)
2071 VM_OBJECT_ASSERT_LOCKED(object);
2072 if (object->type != OBJT_SWAP)
2073 return (object->size);
2075 sb = SWAP_PCTRIE_LOOKUP_GE(&object->un_pager.swp.swp_blks,
2076 rounddown(pindex, SWAP_META_PAGES));
2078 return (object->size);
2079 if (sb->p < pindex) {
2080 for (i = pindex % SWAP_META_PAGES; i < SWAP_META_PAGES; i++) {
2081 if (sb->d[i] != SWAPBLK_NONE)
2084 sb = SWAP_PCTRIE_LOOKUP_GE(&object->un_pager.swp.swp_blks,
2085 roundup(pindex, SWAP_META_PAGES));
2087 return (object->size);
2089 for (i = 0; i < SWAP_META_PAGES; i++) {
2090 if (sb->d[i] != SWAPBLK_NONE)
2095 * We get here if a swblk is present in the trie but it
2096 * doesn't map any blocks.
2099 return (object->size);
2103 * System call swapon(name) enables swapping on device name,
2104 * which must be in the swdevsw. Return EBUSY
2105 * if already swapping on this device.
2107 #ifndef _SYS_SYSPROTO_H_
2108 struct swapon_args {
2118 sys_swapon(struct thread *td, struct swapon_args *uap)
2122 struct nameidata nd;
2125 error = priv_check(td, PRIV_SWAPON);
2129 sx_xlock(&swdev_syscall_lock);
2132 * Swap metadata may not fit in the KVM if we have physical
2135 if (swblk_zone == NULL) {
2140 NDINIT(&nd, LOOKUP, ISOPEN | FOLLOW | AUDITVNODE1, UIO_USERSPACE,
2146 NDFREE(&nd, NDF_ONLY_PNBUF);
2149 if (vn_isdisk(vp, &error)) {
2150 error = swapongeom(vp);
2151 } else if (vp->v_type == VREG &&
2152 (vp->v_mount->mnt_vfc->vfc_flags & VFCF_NETWORK) != 0 &&
2153 (error = VOP_GETATTR(vp, &attr, td->td_ucred)) == 0) {
2155 * Allow direct swapping to NFS regular files in the same
2156 * way that nfs_mountroot() sets up diskless swapping.
2158 error = swaponvp(td, vp, attr.va_size / DEV_BSIZE);
2164 sx_xunlock(&swdev_syscall_lock);
2169 * Check that the total amount of swap currently configured does not
2170 * exceed half the theoretical maximum. If it does, print a warning
2174 swapon_check_swzone(void)
2176 unsigned long maxpages, npages;
2178 npages = swap_total / PAGE_SIZE;
2179 /* absolute maximum we can handle assuming 100% efficiency */
2180 maxpages = uma_zone_get_max(swblk_zone) * SWAP_META_PAGES;
2182 /* recommend using no more than half that amount */
2183 if (npages > maxpages / 2) {
2184 printf("warning: total configured swap (%lu pages) "
2185 "exceeds maximum recommended amount (%lu pages).\n",
2186 npages, maxpages / 2);
2187 printf("warning: increase kern.maxswzone "
2188 "or reduce amount of swap.\n");
2193 swaponsomething(struct vnode *vp, void *id, u_long nblks,
2194 sw_strategy_t *strategy, sw_close_t *close, dev_t dev, int flags)
2196 struct swdevt *sp, *tsp;
2201 * nblks is in DEV_BSIZE'd chunks, convert to PAGE_SIZE'd chunks.
2202 * First chop nblks off to page-align it, then convert.
2204 * sw->sw_nblks is in page-sized chunks now too.
2206 nblks &= ~(ctodb(1) - 1);
2207 nblks = dbtoc(nblks);
2210 * If we go beyond this, we get overflows in the radix
2213 mblocks = 0x40000000 / BLIST_META_RADIX;
2214 if (nblks > mblocks) {
2216 "WARNING: reducing swap size to maximum of %luMB per unit\n",
2217 mblocks / 1024 / 1024 * PAGE_SIZE);
2221 sp = malloc(sizeof *sp, M_VMPGDATA, M_WAITOK | M_ZERO);
2226 sp->sw_nblks = nblks;
2228 sp->sw_strategy = strategy;
2229 sp->sw_close = close;
2230 sp->sw_flags = flags;
2232 sp->sw_blist = blist_create(nblks, M_WAITOK);
2234 * Do not free the first two block in order to avoid overwriting
2235 * any bsd label at the front of the partition
2237 blist_free(sp->sw_blist, 2, nblks - 2);
2240 mtx_lock(&sw_dev_mtx);
2241 TAILQ_FOREACH(tsp, &swtailq, sw_list) {
2242 if (tsp->sw_end >= dvbase) {
2244 * We put one uncovered page between the devices
2245 * in order to definitively prevent any cross-device
2248 dvbase = tsp->sw_end + 1;
2251 sp->sw_first = dvbase;
2252 sp->sw_end = dvbase + nblks;
2253 TAILQ_INSERT_TAIL(&swtailq, sp, sw_list);
2255 swap_pager_avail += nblks - 2;
2256 swap_total += (vm_ooffset_t)nblks * PAGE_SIZE;
2257 swapon_check_swzone();
2259 mtx_unlock(&sw_dev_mtx);
2260 EVENTHANDLER_INVOKE(swapon, sp);
2264 * SYSCALL: swapoff(devname)
2266 * Disable swapping on the given device.
2268 * XXX: Badly designed system call: it should use a device index
2269 * rather than filename as specification. We keep sw_vp around
2270 * only to make this work.
2272 #ifndef _SYS_SYSPROTO_H_
2273 struct swapoff_args {
2283 sys_swapoff(struct thread *td, struct swapoff_args *uap)
2286 struct nameidata nd;
2290 error = priv_check(td, PRIV_SWAPOFF);
2294 sx_xlock(&swdev_syscall_lock);
2296 NDINIT(&nd, LOOKUP, FOLLOW | AUDITVNODE1, UIO_USERSPACE, uap->name,
2301 NDFREE(&nd, NDF_ONLY_PNBUF);
2304 mtx_lock(&sw_dev_mtx);
2305 TAILQ_FOREACH(sp, &swtailq, sw_list) {
2306 if (sp->sw_vp == vp)
2309 mtx_unlock(&sw_dev_mtx);
2314 error = swapoff_one(sp, td->td_ucred);
2316 sx_xunlock(&swdev_syscall_lock);
2321 swapoff_one(struct swdevt *sp, struct ucred *cred)
2328 sx_assert(&swdev_syscall_lock, SA_XLOCKED);
2330 (void) vn_lock(sp->sw_vp, LK_EXCLUSIVE | LK_RETRY);
2331 error = mac_system_check_swapoff(cred, sp->sw_vp);
2332 (void) VOP_UNLOCK(sp->sw_vp, 0);
2336 nblks = sp->sw_nblks;
2339 * We can turn off this swap device safely only if the
2340 * available virtual memory in the system will fit the amount
2341 * of data we will have to page back in, plus an epsilon so
2342 * the system doesn't become critically low on swap space.
2344 if (vm_cnt.v_free_count + swap_pager_avail < nblks + nswap_lowat)
2348 * Prevent further allocations on this device.
2350 mtx_lock(&sw_dev_mtx);
2351 sp->sw_flags |= SW_CLOSING;
2352 swap_pager_avail -= blist_fill(sp->sw_blist, 0, nblks);
2353 swap_total -= (vm_ooffset_t)nblks * PAGE_SIZE;
2354 mtx_unlock(&sw_dev_mtx);
2357 * Page in the contents of the device and close it.
2359 swap_pager_swapoff(sp);
2361 sp->sw_close(curthread, sp);
2362 mtx_lock(&sw_dev_mtx);
2364 TAILQ_REMOVE(&swtailq, sp, sw_list);
2366 if (nswapdev == 0) {
2367 swap_pager_full = 2;
2368 swap_pager_almost_full = 1;
2372 mtx_unlock(&sw_dev_mtx);
2373 blist_destroy(sp->sw_blist);
2374 free(sp, M_VMPGDATA);
2381 struct swdevt *sp, *spt;
2382 const char *devname;
2385 sx_xlock(&swdev_syscall_lock);
2387 mtx_lock(&sw_dev_mtx);
2388 TAILQ_FOREACH_SAFE(sp, &swtailq, sw_list, spt) {
2389 mtx_unlock(&sw_dev_mtx);
2390 if (vn_isdisk(sp->sw_vp, NULL))
2391 devname = devtoname(sp->sw_vp->v_rdev);
2394 error = swapoff_one(sp, thread0.td_ucred);
2396 printf("Cannot remove swap device %s (error=%d), "
2397 "skipping.\n", devname, error);
2398 } else if (bootverbose) {
2399 printf("Swap device %s removed.\n", devname);
2401 mtx_lock(&sw_dev_mtx);
2403 mtx_unlock(&sw_dev_mtx);
2405 sx_xunlock(&swdev_syscall_lock);
2409 swap_pager_status(int *total, int *used)
2415 mtx_lock(&sw_dev_mtx);
2416 TAILQ_FOREACH(sp, &swtailq, sw_list) {
2417 *total += sp->sw_nblks;
2418 *used += sp->sw_used;
2420 mtx_unlock(&sw_dev_mtx);
2424 swap_dev_info(int name, struct xswdev *xs, char *devname, size_t len)
2427 const char *tmp_devname;
2432 mtx_lock(&sw_dev_mtx);
2433 TAILQ_FOREACH(sp, &swtailq, sw_list) {
2438 xs->xsw_version = XSWDEV_VERSION;
2439 xs->xsw_dev = sp->sw_dev;
2440 xs->xsw_flags = sp->sw_flags;
2441 xs->xsw_nblks = sp->sw_nblks;
2442 xs->xsw_used = sp->sw_used;
2443 if (devname != NULL) {
2444 if (vn_isdisk(sp->sw_vp, NULL))
2445 tmp_devname = devtoname(sp->sw_vp->v_rdev);
2447 tmp_devname = "[file]";
2448 strncpy(devname, tmp_devname, len);
2453 mtx_unlock(&sw_dev_mtx);
2457 #if defined(COMPAT_FREEBSD11)
2458 #define XSWDEV_VERSION_11 1
2469 sysctl_vm_swap_info(SYSCTL_HANDLER_ARGS)
2472 #if defined(COMPAT_FREEBSD11)
2473 struct xswdev11 xs11;
2477 if (arg2 != 1) /* name length */
2479 error = swap_dev_info(*(int *)arg1, &xs, NULL, 0);
2482 #if defined(COMPAT_FREEBSD11)
2483 if (req->oldlen == sizeof(xs11)) {
2484 xs11.xsw_version = XSWDEV_VERSION_11;
2485 xs11.xsw_dev = xs.xsw_dev; /* truncation */
2486 xs11.xsw_flags = xs.xsw_flags;
2487 xs11.xsw_nblks = xs.xsw_nblks;
2488 xs11.xsw_used = xs.xsw_used;
2489 error = SYSCTL_OUT(req, &xs11, sizeof(xs11));
2492 error = SYSCTL_OUT(req, &xs, sizeof(xs));
2496 SYSCTL_INT(_vm, OID_AUTO, nswapdev, CTLFLAG_RD, &nswapdev, 0,
2497 "Number of swap devices");
2498 SYSCTL_NODE(_vm, OID_AUTO, swap_info, CTLFLAG_RD | CTLFLAG_MPSAFE,
2499 sysctl_vm_swap_info,
2500 "Swap statistics by device");
2503 * Count the approximate swap usage in pages for a vmspace. The
2504 * shadowed or not yet copied on write swap blocks are not accounted.
2505 * The map must be locked.
2508 vmspace_swap_count(struct vmspace *vmspace)
2518 map = &vmspace->vm_map;
2521 for (cur = map->header.next; cur != &map->header; cur = cur->next) {
2522 if ((cur->eflags & MAP_ENTRY_IS_SUB_MAP) != 0)
2524 object = cur->object.vm_object;
2525 if (object == NULL || object->type != OBJT_SWAP)
2527 VM_OBJECT_RLOCK(object);
2528 if (object->type != OBJT_SWAP)
2530 pi = OFF_TO_IDX(cur->offset);
2531 e = pi + OFF_TO_IDX(cur->end - cur->start);
2532 for (;; pi = sb->p + SWAP_META_PAGES) {
2533 sb = SWAP_PCTRIE_LOOKUP_GE(
2534 &object->un_pager.swp.swp_blks, pi);
2535 if (sb == NULL || sb->p >= e)
2537 for (i = 0; i < SWAP_META_PAGES; i++) {
2538 if (sb->p + i < e &&
2539 sb->d[i] != SWAPBLK_NONE)
2544 VM_OBJECT_RUNLOCK(object);
2552 * Swapping onto disk devices.
2556 static g_orphan_t swapgeom_orphan;
2558 static struct g_class g_swap_class = {
2560 .version = G_VERSION,
2561 .orphan = swapgeom_orphan,
2564 DECLARE_GEOM_CLASS(g_swap_class, g_class);
2568 swapgeom_close_ev(void *arg, int flags)
2570 struct g_consumer *cp;
2573 g_access(cp, -1, -1, 0);
2575 g_destroy_consumer(cp);
2579 * Add a reference to the g_consumer for an inflight transaction.
2582 swapgeom_acquire(struct g_consumer *cp)
2585 mtx_assert(&sw_dev_mtx, MA_OWNED);
2590 * Remove a reference from the g_consumer. Post a close event if all
2591 * references go away, since the function might be called from the
2595 swapgeom_release(struct g_consumer *cp, struct swdevt *sp)
2598 mtx_assert(&sw_dev_mtx, MA_OWNED);
2600 if (cp->index == 0) {
2601 if (g_post_event(swapgeom_close_ev, cp, M_NOWAIT, NULL) == 0)
2607 swapgeom_done(struct bio *bp2)
2611 struct g_consumer *cp;
2613 bp = bp2->bio_caller2;
2615 bp->b_ioflags = bp2->bio_flags;
2617 bp->b_ioflags |= BIO_ERROR;
2618 bp->b_resid = bp->b_bcount - bp2->bio_completed;
2619 bp->b_error = bp2->bio_error;
2621 sp = bp2->bio_caller1;
2622 mtx_lock(&sw_dev_mtx);
2623 swapgeom_release(cp, sp);
2624 mtx_unlock(&sw_dev_mtx);
2629 swapgeom_strategy(struct buf *bp, struct swdevt *sp)
2632 struct g_consumer *cp;
2634 mtx_lock(&sw_dev_mtx);
2637 mtx_unlock(&sw_dev_mtx);
2638 bp->b_error = ENXIO;
2639 bp->b_ioflags |= BIO_ERROR;
2643 swapgeom_acquire(cp);
2644 mtx_unlock(&sw_dev_mtx);
2645 if (bp->b_iocmd == BIO_WRITE)
2648 bio = g_alloc_bio();
2650 mtx_lock(&sw_dev_mtx);
2651 swapgeom_release(cp, sp);
2652 mtx_unlock(&sw_dev_mtx);
2653 bp->b_error = ENOMEM;
2654 bp->b_ioflags |= BIO_ERROR;
2659 bio->bio_caller1 = sp;
2660 bio->bio_caller2 = bp;
2661 bio->bio_cmd = bp->b_iocmd;
2662 bio->bio_offset = (bp->b_blkno - sp->sw_first) * PAGE_SIZE;
2663 bio->bio_length = bp->b_bcount;
2664 bio->bio_done = swapgeom_done;
2665 if (!buf_mapped(bp)) {
2666 bio->bio_ma = bp->b_pages;
2667 bio->bio_data = unmapped_buf;
2668 bio->bio_ma_offset = (vm_offset_t)bp->b_offset & PAGE_MASK;
2669 bio->bio_ma_n = bp->b_npages;
2670 bio->bio_flags |= BIO_UNMAPPED;
2672 bio->bio_data = bp->b_data;
2675 g_io_request(bio, cp);
2680 swapgeom_orphan(struct g_consumer *cp)
2685 mtx_lock(&sw_dev_mtx);
2686 TAILQ_FOREACH(sp, &swtailq, sw_list) {
2687 if (sp->sw_id == cp) {
2688 sp->sw_flags |= SW_CLOSING;
2693 * Drop reference we were created with. Do directly since we're in a
2694 * special context where we don't have to queue the call to
2695 * swapgeom_close_ev().
2698 destroy = ((sp != NULL) && (cp->index == 0));
2701 mtx_unlock(&sw_dev_mtx);
2703 swapgeom_close_ev(cp, 0);
2707 swapgeom_close(struct thread *td, struct swdevt *sw)
2709 struct g_consumer *cp;
2711 mtx_lock(&sw_dev_mtx);
2714 mtx_unlock(&sw_dev_mtx);
2717 * swapgeom_close() may be called from the biodone context,
2718 * where we cannot perform topology changes. Delegate the
2719 * work to the events thread.
2722 g_waitfor_event(swapgeom_close_ev, cp, M_WAITOK, NULL);
2726 swapongeom_locked(struct cdev *dev, struct vnode *vp)
2728 struct g_provider *pp;
2729 struct g_consumer *cp;
2730 static struct g_geom *gp;
2735 pp = g_dev_getprovider(dev);
2738 mtx_lock(&sw_dev_mtx);
2739 TAILQ_FOREACH(sp, &swtailq, sw_list) {
2741 if (cp != NULL && cp->provider == pp) {
2742 mtx_unlock(&sw_dev_mtx);
2746 mtx_unlock(&sw_dev_mtx);
2748 gp = g_new_geomf(&g_swap_class, "swap");
2749 cp = g_new_consumer(gp);
2750 cp->index = 1; /* Number of active I/Os, plus one for being active. */
2751 cp->flags |= G_CF_DIRECT_SEND | G_CF_DIRECT_RECEIVE;
2754 * XXX: Every time you think you can improve the margin for
2755 * footshooting, somebody depends on the ability to do so:
2756 * savecore(8) wants to write to our swapdev so we cannot
2757 * set an exclusive count :-(
2759 error = g_access(cp, 1, 1, 0);
2762 g_destroy_consumer(cp);
2765 nblks = pp->mediasize / DEV_BSIZE;
2766 swaponsomething(vp, cp, nblks, swapgeom_strategy,
2767 swapgeom_close, dev2udev(dev),
2768 (pp->flags & G_PF_ACCEPT_UNMAPPED) != 0 ? SW_UNMAPPED : 0);
2773 swapongeom(struct vnode *vp)
2777 vn_lock(vp, LK_EXCLUSIVE | LK_RETRY);
2778 if (vp->v_type != VCHR || (vp->v_iflag & VI_DOOMED) != 0) {
2782 error = swapongeom_locked(vp->v_rdev, vp);
2783 g_topology_unlock();
2792 * This is used mainly for network filesystem (read: probably only tested
2793 * with NFS) swapfiles.
2798 swapdev_strategy(struct buf *bp, struct swdevt *sp)
2802 bp->b_blkno = ctodb(bp->b_blkno - sp->sw_first);
2806 if (bp->b_iocmd == BIO_WRITE) {
2808 bufobj_wdrop(bp->b_bufobj);
2809 bufobj_wref(&vp2->v_bufobj);
2811 if (bp->b_bufobj != &vp2->v_bufobj)
2812 bp->b_bufobj = &vp2->v_bufobj;
2814 bp->b_iooffset = dbtob(bp->b_blkno);
2820 swapdev_close(struct thread *td, struct swdevt *sp)
2823 VOP_CLOSE(sp->sw_vp, FREAD | FWRITE, td->td_ucred, td);
2829 swaponvp(struct thread *td, struct vnode *vp, u_long nblks)
2836 mtx_lock(&sw_dev_mtx);
2837 TAILQ_FOREACH(sp, &swtailq, sw_list) {
2838 if (sp->sw_id == vp) {
2839 mtx_unlock(&sw_dev_mtx);
2843 mtx_unlock(&sw_dev_mtx);
2845 (void) vn_lock(vp, LK_EXCLUSIVE | LK_RETRY);
2847 error = mac_system_check_swapon(td->td_ucred, vp);
2850 error = VOP_OPEN(vp, FREAD | FWRITE, td->td_ucred, td, NULL);
2851 (void) VOP_UNLOCK(vp, 0);
2855 swaponsomething(vp, vp, nblks, swapdev_strategy, swapdev_close,
2861 sysctl_swap_async_max(SYSCTL_HANDLER_ARGS)
2865 new = nsw_wcount_async_max;
2866 error = sysctl_handle_int(oidp, &new, 0, req);
2867 if (error != 0 || req->newptr == NULL)
2870 if (new > nswbuf / 2 || new < 1)
2873 mtx_lock(&pbuf_mtx);
2874 while (nsw_wcount_async_max != new) {
2876 * Adjust difference. If the current async count is too low,
2877 * we will need to sqeeze our update slowly in. Sleep with a
2878 * higher priority than getpbuf() to finish faster.
2880 n = new - nsw_wcount_async_max;
2881 if (nsw_wcount_async + n >= 0) {
2882 nsw_wcount_async += n;
2883 nsw_wcount_async_max += n;
2884 wakeup(&nsw_wcount_async);
2886 nsw_wcount_async_max -= nsw_wcount_async;
2887 nsw_wcount_async = 0;
2888 msleep(&nsw_wcount_async, &pbuf_mtx, PSWP,
2892 mtx_unlock(&pbuf_mtx);