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_POP 0x01 /* pop out */
316 static int swap_pager_full = 2; /* swap space exhaustion (task killing) */
317 static int swap_pager_almost_full = 1; /* swap space exhaustion (w/hysteresis)*/
318 static int nsw_rcount; /* free read buffers */
319 static int nsw_wcount_sync; /* limit write buffers / synchronous */
320 static int nsw_wcount_async; /* limit write buffers / asynchronous */
321 static int nsw_wcount_async_max;/* assigned maximum */
322 static int nsw_cluster_max; /* maximum VOP I/O allowed */
324 static int sysctl_swap_async_max(SYSCTL_HANDLER_ARGS);
325 SYSCTL_PROC(_vm, OID_AUTO, swap_async_max, CTLTYPE_INT | CTLFLAG_RW |
326 CTLFLAG_MPSAFE, NULL, 0, sysctl_swap_async_max, "I",
327 "Maximum running async swap ops");
328 static int sysctl_swap_fragmentation(SYSCTL_HANDLER_ARGS);
329 SYSCTL_PROC(_vm, OID_AUTO, swap_fragmentation, CTLTYPE_STRING | CTLFLAG_RD |
330 CTLFLAG_MPSAFE, NULL, 0, sysctl_swap_fragmentation, "A",
331 "Swap Fragmentation Info");
333 static struct sx sw_alloc_sx;
336 * "named" and "unnamed" anon region objects. Try to reduce the overhead
337 * of searching a named list by hashing it just a little.
342 #define NOBJLIST(handle) \
343 (&swap_pager_object_list[((int)(intptr_t)handle >> 4) & (NOBJLISTS-1)])
345 static struct pagerlst swap_pager_object_list[NOBJLISTS];
346 static uma_zone_t swblk_zone;
347 static uma_zone_t swpctrie_zone;
350 * pagerops for OBJT_SWAP - "swap pager". Some ops are also global procedure
351 * calls hooked from other parts of the VM system and do not appear here.
352 * (see vm/swap_pager.h).
355 swap_pager_alloc(void *handle, vm_ooffset_t size,
356 vm_prot_t prot, vm_ooffset_t offset, struct ucred *);
357 static void swap_pager_dealloc(vm_object_t object);
358 static int swap_pager_getpages(vm_object_t, vm_page_t *, int, int *,
360 static int swap_pager_getpages_async(vm_object_t, vm_page_t *, int, int *,
361 int *, pgo_getpages_iodone_t, void *);
362 static void swap_pager_putpages(vm_object_t, vm_page_t *, int, boolean_t, int *);
364 swap_pager_haspage(vm_object_t object, vm_pindex_t pindex, int *before, int *after);
365 static void swap_pager_init(void);
366 static void swap_pager_unswapped(vm_page_t);
367 static void swap_pager_swapoff(struct swdevt *sp);
369 struct pagerops swappagerops = {
370 .pgo_init = swap_pager_init, /* early system initialization of pager */
371 .pgo_alloc = swap_pager_alloc, /* allocate an OBJT_SWAP object */
372 .pgo_dealloc = swap_pager_dealloc, /* deallocate an OBJT_SWAP object */
373 .pgo_getpages = swap_pager_getpages, /* pagein */
374 .pgo_getpages_async = swap_pager_getpages_async, /* pagein (async) */
375 .pgo_putpages = swap_pager_putpages, /* pageout */
376 .pgo_haspage = swap_pager_haspage, /* get backing store status for page */
377 .pgo_pageunswapped = swap_pager_unswapped, /* remove swap related to page */
381 * swap_*() routines are externally accessible. swp_*() routines are
384 static int nswap_lowat = 128; /* in pages, swap_pager_almost_full warn */
385 static int nswap_hiwat = 512; /* in pages, swap_pager_almost_full warn */
387 SYSCTL_INT(_vm, OID_AUTO, dmmax, CTLFLAG_RD, &nsw_cluster_max, 0,
388 "Maximum size of a swap block in pages");
390 static void swp_sizecheck(void);
391 static void swp_pager_async_iodone(struct buf *bp);
392 static bool swp_pager_swblk_empty(struct swblk *sb, int start, int limit);
393 static int swapongeom(struct vnode *);
394 static int swaponvp(struct thread *, struct vnode *, u_long);
395 static int swapoff_one(struct swdevt *sp, struct ucred *cred);
398 * Swap bitmap functions
400 static void swp_pager_freeswapspace(daddr_t blk, daddr_t npages);
401 static daddr_t swp_pager_getswapspace(int npages);
406 static void swp_pager_meta_build(vm_object_t, vm_pindex_t, daddr_t);
407 static void swp_pager_meta_free(vm_object_t, vm_pindex_t, vm_pindex_t);
408 static void swp_pager_meta_free_all(vm_object_t);
409 static daddr_t swp_pager_meta_ctl(vm_object_t, vm_pindex_t, int);
412 swblk_trie_alloc(struct pctrie *ptree)
415 return (uma_zalloc(swpctrie_zone, M_NOWAIT | (curproc == pageproc ?
416 M_USE_RESERVE : 0)));
420 swblk_trie_free(struct pctrie *ptree, void *node)
423 uma_zfree(swpctrie_zone, node);
426 PCTRIE_DEFINE(SWAP, swblk, p, swblk_trie_alloc, swblk_trie_free);
429 * SWP_SIZECHECK() - update swap_pager_full indication
431 * update the swap_pager_almost_full indication and warn when we are
432 * about to run out of swap space, using lowat/hiwat hysteresis.
434 * Clear swap_pager_full ( task killing ) indication when lowat is met.
436 * No restrictions on call
437 * This routine may not block.
443 if (swap_pager_avail < nswap_lowat) {
444 if (swap_pager_almost_full == 0) {
445 printf("swap_pager: out of swap space\n");
446 swap_pager_almost_full = 1;
450 if (swap_pager_avail > nswap_hiwat)
451 swap_pager_almost_full = 0;
456 * SWAP_PAGER_INIT() - initialize the swap pager!
458 * Expected to be started from system init. NOTE: This code is run
459 * before much else so be careful what you depend on. Most of the VM
460 * system has yet to be initialized at this point.
463 swap_pager_init(void)
466 * Initialize object lists
470 for (i = 0; i < NOBJLISTS; ++i)
471 TAILQ_INIT(&swap_pager_object_list[i]);
472 mtx_init(&sw_dev_mtx, "swapdev", NULL, MTX_DEF);
473 sx_init(&sw_alloc_sx, "swspsx");
474 sx_init(&swdev_syscall_lock, "swsysc");
478 * SWAP_PAGER_SWAP_INIT() - swap pager initialization from pageout process
480 * Expected to be started from pageout process once, prior to entering
484 swap_pager_swap_init(void)
489 * Number of in-transit swap bp operations. Don't
490 * exhaust the pbufs completely. Make sure we
491 * initialize workable values (0 will work for hysteresis
492 * but it isn't very efficient).
494 * The nsw_cluster_max is constrained by the bp->b_pages[]
495 * array (MAXPHYS/PAGE_SIZE) and our locally defined
496 * MAX_PAGEOUT_CLUSTER. Also be aware that swap ops are
497 * constrained by the swap device interleave stripe size.
499 * Currently we hardwire nsw_wcount_async to 4. This limit is
500 * designed to prevent other I/O from having high latencies due to
501 * our pageout I/O. The value 4 works well for one or two active swap
502 * devices but is probably a little low if you have more. Even so,
503 * a higher value would probably generate only a limited improvement
504 * with three or four active swap devices since the system does not
505 * typically have to pageout at extreme bandwidths. We will want
506 * at least 2 per swap devices, and 4 is a pretty good value if you
507 * have one NFS swap device due to the command/ack latency over NFS.
508 * So it all works out pretty well.
510 nsw_cluster_max = min((MAXPHYS/PAGE_SIZE), MAX_PAGEOUT_CLUSTER);
513 nsw_rcount = (nswbuf + 1) / 2;
514 nsw_wcount_sync = (nswbuf + 3) / 4;
515 nsw_wcount_async = 4;
516 nsw_wcount_async_max = nsw_wcount_async;
517 mtx_unlock(&pbuf_mtx);
520 * Initialize our zone, guessing on the number we need based
521 * on the number of pages in the system.
523 n = vm_cnt.v_page_count / 2;
524 if (maxswzone && n > maxswzone / sizeof(struct swblk))
525 n = maxswzone / sizeof(struct swblk);
526 swpctrie_zone = uma_zcreate("swpctrie", pctrie_node_size(), NULL, NULL,
527 pctrie_zone_init, NULL, UMA_ALIGN_PTR,
528 UMA_ZONE_NOFREE | UMA_ZONE_VM);
529 if (swpctrie_zone == NULL)
530 panic("failed to create swap pctrie zone.");
531 swblk_zone = uma_zcreate("swblk", sizeof(struct swblk), NULL, NULL,
532 NULL, NULL, _Alignof(struct swblk) - 1,
533 UMA_ZONE_NOFREE | UMA_ZONE_VM);
534 if (swblk_zone == NULL)
535 panic("failed to create swap blk zone.");
538 if (uma_zone_reserve_kva(swblk_zone, n))
541 * if the allocation failed, try a zone two thirds the
542 * size of the previous attempt.
548 * Often uma_zone_reserve_kva() cannot reserve exactly the
549 * requested size. Account for the difference when
550 * calculating swap_maxpages.
552 n = uma_zone_get_max(swblk_zone);
555 printf("Swap blk zone entries reduced from %lu to %lu.\n",
557 swap_maxpages = n * SWAP_META_PAGES;
558 swzone = n * sizeof(struct swblk);
559 if (!uma_zone_reserve_kva(swpctrie_zone, n))
560 printf("Cannot reserve swap pctrie zone, "
561 "reduce kern.maxswzone.\n");
565 swap_pager_alloc_init(void *handle, struct ucred *cred, vm_ooffset_t size,
571 if (!swap_reserve_by_cred(size, cred))
577 * The un_pager.swp.swp_blks trie is initialized by
578 * vm_object_allocate() to ensure the correct order of
579 * visibility to other threads.
581 object = vm_object_allocate(OBJT_SWAP, OFF_TO_IDX(offset +
584 object->handle = handle;
587 object->charge = size;
593 * SWAP_PAGER_ALLOC() - allocate a new OBJT_SWAP VM object and instantiate
594 * its metadata structures.
596 * This routine is called from the mmap and fork code to create a new
599 * This routine must ensure that no live duplicate is created for
600 * the named object request, which is protected against by
601 * holding the sw_alloc_sx lock in case handle != NULL.
604 swap_pager_alloc(void *handle, vm_ooffset_t size, vm_prot_t prot,
605 vm_ooffset_t offset, struct ucred *cred)
609 if (handle != NULL) {
611 * Reference existing named region or allocate new one. There
612 * should not be a race here against swp_pager_meta_build()
613 * as called from vm_page_remove() in regards to the lookup
616 sx_xlock(&sw_alloc_sx);
617 object = vm_pager_object_lookup(NOBJLIST(handle), handle);
618 if (object == NULL) {
619 object = swap_pager_alloc_init(handle, cred, size,
621 if (object != NULL) {
622 TAILQ_INSERT_TAIL(NOBJLIST(object->handle),
623 object, pager_object_list);
626 sx_xunlock(&sw_alloc_sx);
628 object = swap_pager_alloc_init(handle, cred, size, offset);
634 * SWAP_PAGER_DEALLOC() - remove swap metadata from object
636 * The swap backing for the object is destroyed. The code is
637 * designed such that we can reinstantiate it later, but this
638 * routine is typically called only when the entire object is
639 * about to be destroyed.
641 * The object must be locked.
644 swap_pager_dealloc(vm_object_t object)
647 VM_OBJECT_ASSERT_WLOCKED(object);
648 KASSERT((object->flags & OBJ_DEAD) != 0, ("dealloc of reachable obj"));
651 * Remove from list right away so lookups will fail if we block for
652 * pageout completion.
654 if (object->handle != NULL) {
655 VM_OBJECT_WUNLOCK(object);
656 sx_xlock(&sw_alloc_sx);
657 TAILQ_REMOVE(NOBJLIST(object->handle), object,
659 sx_xunlock(&sw_alloc_sx);
660 VM_OBJECT_WLOCK(object);
663 vm_object_pip_wait(object, "swpdea");
666 * Free all remaining metadata. We only bother to free it from
667 * the swap meta data. We do not attempt to free swapblk's still
668 * associated with vm_page_t's for this object. We do not care
669 * if paging is still in progress on some objects.
671 swp_pager_meta_free_all(object);
672 object->handle = NULL;
673 object->type = OBJT_DEAD;
676 /************************************************************************
677 * SWAP PAGER BITMAP ROUTINES *
678 ************************************************************************/
681 * SWP_PAGER_GETSWAPSPACE() - allocate raw swap space
683 * Allocate swap for the requested number of pages. The starting
684 * swap block number (a page index) is returned or SWAPBLK_NONE
685 * if the allocation failed.
687 * Also has the side effect of advising that somebody made a mistake
688 * when they configured swap and didn't configure enough.
690 * This routine may not sleep.
692 * We allocate in round-robin fashion from the configured devices.
695 swp_pager_getswapspace(int npages)
702 mtx_lock(&sw_dev_mtx);
704 for (i = 0; i < nswapdev; i++) {
706 sp = TAILQ_FIRST(&swtailq);
707 if (!(sp->sw_flags & SW_CLOSING)) {
708 blk = blist_alloc(sp->sw_blist, npages);
709 if (blk != SWAPBLK_NONE) {
711 sp->sw_used += npages;
712 swap_pager_avail -= npages;
714 swdevhd = TAILQ_NEXT(sp, sw_list);
718 sp = TAILQ_NEXT(sp, sw_list);
720 if (swap_pager_full != 2) {
721 printf("swap_pager_getswapspace(%d): failed\n", npages);
723 swap_pager_almost_full = 1;
727 mtx_unlock(&sw_dev_mtx);
732 swp_pager_isondev(daddr_t blk, struct swdevt *sp)
735 return (blk >= sp->sw_first && blk < sp->sw_end);
739 swp_pager_strategy(struct buf *bp)
743 mtx_lock(&sw_dev_mtx);
744 TAILQ_FOREACH(sp, &swtailq, sw_list) {
745 if (bp->b_blkno >= sp->sw_first && bp->b_blkno < sp->sw_end) {
746 mtx_unlock(&sw_dev_mtx);
747 if ((sp->sw_flags & SW_UNMAPPED) != 0 &&
748 unmapped_buf_allowed) {
749 bp->b_data = unmapped_buf;
752 pmap_qenter((vm_offset_t)bp->b_data,
753 &bp->b_pages[0], bp->b_bcount / PAGE_SIZE);
755 sp->sw_strategy(bp, sp);
759 panic("Swapdev not found");
764 * SWP_PAGER_FREESWAPSPACE() - free raw swap space
766 * This routine returns the specified swap blocks back to the bitmap.
768 * This routine may not sleep.
771 swp_pager_freeswapspace(daddr_t blk, daddr_t npages)
777 mtx_lock(&sw_dev_mtx);
778 TAILQ_FOREACH(sp, &swtailq, sw_list) {
779 if (blk >= sp->sw_first && blk < sp->sw_end) {
780 sp->sw_used -= npages;
782 * If we are attempting to stop swapping on
783 * this device, we don't want to mark any
784 * blocks free lest they be reused.
786 if ((sp->sw_flags & SW_CLOSING) == 0) {
787 blist_free(sp->sw_blist, blk - sp->sw_first,
789 swap_pager_avail += npages;
792 mtx_unlock(&sw_dev_mtx);
796 panic("Swapdev not found");
800 * SYSCTL_SWAP_FRAGMENTATION() - produce raw swap space stats
803 sysctl_swap_fragmentation(SYSCTL_HANDLER_ARGS)
810 error = sysctl_wire_old_buffer(req, 0);
813 sbuf_new_for_sysctl(&sbuf, NULL, 128, req);
814 mtx_lock(&sw_dev_mtx);
815 TAILQ_FOREACH(sp, &swtailq, sw_list) {
816 if (vn_isdisk(sp->sw_vp, NULL))
817 devname = devtoname(sp->sw_vp->v_rdev);
820 sbuf_printf(&sbuf, "\nFree space on device %s:\n", devname);
821 blist_stats(sp->sw_blist, &sbuf);
823 mtx_unlock(&sw_dev_mtx);
824 error = sbuf_finish(&sbuf);
830 * SWAP_PAGER_FREESPACE() - frees swap blocks associated with a page
831 * range within an object.
833 * This is a globally accessible routine.
835 * This routine removes swapblk assignments from swap metadata.
837 * The external callers of this routine typically have already destroyed
838 * or renamed vm_page_t's associated with this range in the object so
841 * The object must be locked.
844 swap_pager_freespace(vm_object_t object, vm_pindex_t start, vm_size_t size)
847 swp_pager_meta_free(object, start, size);
851 * SWAP_PAGER_RESERVE() - reserve swap blocks in object
853 * Assigns swap blocks to the specified range within the object. The
854 * swap blocks are not zeroed. Any previous swap assignment is destroyed.
856 * Returns 0 on success, -1 on failure.
859 swap_pager_reserve(vm_object_t object, vm_pindex_t start, vm_size_t size)
862 daddr_t blk = SWAPBLK_NONE;
863 vm_pindex_t beg = start; /* save start index */
865 VM_OBJECT_WLOCK(object);
869 while ((blk = swp_pager_getswapspace(n)) == SWAPBLK_NONE) {
872 swp_pager_meta_free(object, beg, start - beg);
873 VM_OBJECT_WUNLOCK(object);
878 swp_pager_meta_build(object, start, blk);
884 swp_pager_meta_free(object, start, n);
885 VM_OBJECT_WUNLOCK(object);
890 * SWAP_PAGER_COPY() - copy blocks from source pager to destination pager
891 * and destroy the source.
893 * Copy any valid swapblks from the source to the destination. In
894 * cases where both the source and destination have a valid swapblk,
895 * we keep the destination's.
897 * This routine is allowed to sleep. It may sleep allocating metadata
898 * indirectly through swp_pager_meta_build() or if paging is still in
899 * progress on the source.
901 * The source object contains no vm_page_t's (which is just as well)
903 * The source object is of type OBJT_SWAP.
905 * The source and destination objects must be locked.
906 * Both object locks may temporarily be released.
909 swap_pager_copy(vm_object_t srcobject, vm_object_t dstobject,
910 vm_pindex_t offset, int destroysource)
913 daddr_t dstaddr, first_free, num_free, srcaddr;
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 first_free = SWAPBLK_NONE;
942 for (i = 0; i < dstobject->size; ++i) {
943 srcaddr = swp_pager_meta_ctl(srcobject, i + offset, SWM_POP);
944 if (srcaddr == SWAPBLK_NONE)
946 dstaddr = swp_pager_meta_ctl(dstobject, i, 0);
947 if (dstaddr == SWAPBLK_NONE) {
949 * Destination has no swapblk and is not resident,
952 * swp_pager_meta_build() can sleep.
954 vm_object_pip_add(srcobject, 1);
955 VM_OBJECT_WUNLOCK(srcobject);
956 vm_object_pip_add(dstobject, 1);
957 swp_pager_meta_build(dstobject, i, srcaddr);
958 vm_object_pip_wakeup(dstobject);
959 VM_OBJECT_WLOCK(srcobject);
960 vm_object_pip_wakeup(srcobject);
963 * Destination has valid swapblk or it is represented
964 * by a resident page. We destroy the sourceblock.
966 if (first_free + num_free == srcaddr)
969 swp_pager_freeswapspace(first_free, num_free);
970 first_free = srcaddr;
975 swp_pager_freeswapspace(first_free, num_free);
978 * Free left over swap blocks in source.
980 * We have to revert the type to OBJT_DEFAULT so we do not accidentally
981 * double-remove the object from the swap queues.
984 swp_pager_meta_free_all(srcobject);
986 * Reverting the type is not necessary, the caller is going
987 * to destroy srcobject directly, but I'm doing it here
988 * for consistency since we've removed the object from its
991 srcobject->type = OBJT_DEFAULT;
996 * SWAP_PAGER_HASPAGE() - determine if we have good backing store for
997 * the requested page.
999 * We determine whether good backing store exists for the requested
1000 * page and return TRUE if it does, FALSE if it doesn't.
1002 * If TRUE, we also try to determine how much valid, contiguous backing
1003 * store exists before and after the requested page.
1006 swap_pager_haspage(vm_object_t object, vm_pindex_t pindex, int *before,
1012 VM_OBJECT_ASSERT_LOCKED(object);
1015 * do we have good backing store at the requested index ?
1017 blk0 = swp_pager_meta_ctl(object, pindex, 0);
1018 if (blk0 == SWAPBLK_NONE) {
1027 * find backwards-looking contiguous good backing store
1029 if (before != NULL) {
1030 for (i = 1; i < SWB_NPAGES; i++) {
1033 blk = swp_pager_meta_ctl(object, pindex - i, 0);
1034 if (blk != blk0 - i)
1041 * find forward-looking contiguous good backing store
1043 if (after != NULL) {
1044 for (i = 1; i < SWB_NPAGES; i++) {
1045 blk = swp_pager_meta_ctl(object, pindex + i, 0);
1046 if (blk != blk0 + i)
1055 * SWAP_PAGER_PAGE_UNSWAPPED() - remove swap backing store related to page
1057 * This removes any associated swap backing store, whether valid or
1058 * not, from the page.
1060 * This routine is typically called when a page is made dirty, at
1061 * which point any associated swap can be freed. MADV_FREE also
1062 * calls us in a special-case situation
1064 * NOTE!!! If the page is clean and the swap was valid, the caller
1065 * should make the page dirty before calling this routine. This routine
1066 * does NOT change the m->dirty status of the page. Also: MADV_FREE
1069 * This routine may not sleep.
1071 * The object containing the page must be locked.
1074 swap_pager_unswapped(vm_page_t m)
1078 srcaddr = swp_pager_meta_ctl(m->object, m->pindex, SWM_POP);
1079 if (srcaddr != SWAPBLK_NONE)
1080 swp_pager_freeswapspace(srcaddr, 1);
1084 * swap_pager_getpages() - bring pages in from swap
1086 * Attempt to page in the pages in array "m" of length "count". The caller
1087 * may optionally specify that additional pages preceding and succeeding
1088 * the specified range be paged in. The number of such pages is returned
1089 * in the "rbehind" and "rahead" parameters, and they will be in the
1090 * inactive queue upon return.
1092 * The pages in "m" must be busied and will remain busied upon return.
1095 swap_pager_getpages(vm_object_t object, vm_page_t *m, int count, int *rbehind,
1099 vm_page_t mpred, msucc, p;
1102 int i, j, maxahead, maxbehind, reqcount, shift;
1106 VM_OBJECT_WUNLOCK(object);
1107 bp = getpbuf(&nsw_rcount);
1108 VM_OBJECT_WLOCK(object);
1110 if (!swap_pager_haspage(object, m[0]->pindex, &maxbehind, &maxahead)) {
1111 relpbuf(bp, &nsw_rcount);
1112 return (VM_PAGER_FAIL);
1116 * Clip the readahead and readbehind ranges to exclude resident pages.
1118 if (rahead != NULL) {
1119 KASSERT(reqcount - 1 <= maxahead,
1120 ("page count %d extends beyond swap block", reqcount));
1121 *rahead = imin(*rahead, maxahead - (reqcount - 1));
1122 pindex = m[reqcount - 1]->pindex;
1123 msucc = TAILQ_NEXT(m[reqcount - 1], listq);
1124 if (msucc != NULL && msucc->pindex - pindex - 1 < *rahead)
1125 *rahead = msucc->pindex - pindex - 1;
1127 if (rbehind != NULL) {
1128 *rbehind = imin(*rbehind, maxbehind);
1129 pindex = m[0]->pindex;
1130 mpred = TAILQ_PREV(m[0], pglist, listq);
1131 if (mpred != NULL && pindex - mpred->pindex - 1 < *rbehind)
1132 *rbehind = pindex - mpred->pindex - 1;
1136 * Allocate readahead and readbehind pages.
1138 shift = rbehind != NULL ? *rbehind : 0;
1140 for (i = 1; i <= shift; i++) {
1141 p = vm_page_alloc(object, m[0]->pindex - i,
1144 /* Shift allocated pages to the left. */
1145 for (j = 0; j < i - 1; j++)
1147 bp->b_pages[j + shift - i + 1];
1150 bp->b_pages[shift - i] = p;
1155 for (i = 0; i < reqcount; i++)
1156 bp->b_pages[i + shift] = m[i];
1157 if (rahead != NULL) {
1158 for (i = 0; i < *rahead; i++) {
1159 p = vm_page_alloc(object,
1160 m[reqcount - 1]->pindex + i + 1, VM_ALLOC_NORMAL);
1163 bp->b_pages[shift + reqcount + i] = p;
1167 if (rbehind != NULL)
1172 vm_object_pip_add(object, count);
1174 for (i = 0; i < count; i++)
1175 bp->b_pages[i]->oflags |= VPO_SWAPINPROG;
1177 pindex = bp->b_pages[0]->pindex;
1178 blk = swp_pager_meta_ctl(object, pindex, 0);
1179 KASSERT(blk != SWAPBLK_NONE,
1180 ("no swap blocking containing %p(%jx)", object, (uintmax_t)pindex));
1182 VM_OBJECT_WUNLOCK(object);
1184 bp->b_flags |= B_PAGING;
1185 bp->b_iocmd = BIO_READ;
1186 bp->b_iodone = swp_pager_async_iodone;
1187 bp->b_rcred = crhold(thread0.td_ucred);
1188 bp->b_wcred = crhold(thread0.td_ucred);
1190 bp->b_bcount = PAGE_SIZE * count;
1191 bp->b_bufsize = PAGE_SIZE * count;
1192 bp->b_npages = count;
1193 bp->b_pgbefore = rbehind != NULL ? *rbehind : 0;
1194 bp->b_pgafter = rahead != NULL ? *rahead : 0;
1196 VM_CNT_INC(v_swapin);
1197 VM_CNT_ADD(v_swappgsin, count);
1200 * perform the I/O. NOTE!!! bp cannot be considered valid after
1201 * this point because we automatically release it on completion.
1202 * Instead, we look at the one page we are interested in which we
1203 * still hold a lock on even through the I/O completion.
1205 * The other pages in our m[] array are also released on completion,
1206 * so we cannot assume they are valid anymore either.
1208 * NOTE: b_blkno is destroyed by the call to swapdev_strategy
1211 swp_pager_strategy(bp);
1214 * Wait for the pages we want to complete. VPO_SWAPINPROG is always
1215 * cleared on completion. If an I/O error occurs, SWAPBLK_NONE
1216 * is set in the metadata for each page in the request.
1218 VM_OBJECT_WLOCK(object);
1219 while ((m[0]->oflags & VPO_SWAPINPROG) != 0) {
1220 m[0]->oflags |= VPO_SWAPSLEEP;
1221 VM_CNT_INC(v_intrans);
1222 if (VM_OBJECT_SLEEP(object, &object->paging_in_progress, PSWP,
1223 "swread", hz * 20)) {
1225 "swap_pager: indefinite wait buffer: bufobj: %p, blkno: %jd, size: %ld\n",
1226 bp->b_bufobj, (intmax_t)bp->b_blkno, bp->b_bcount);
1231 * If we had an unrecoverable read error pages will not be valid.
1233 for (i = 0; i < reqcount; i++)
1234 if (m[i]->valid != VM_PAGE_BITS_ALL)
1235 return (VM_PAGER_ERROR);
1237 return (VM_PAGER_OK);
1240 * A final note: in a low swap situation, we cannot deallocate swap
1241 * and mark a page dirty here because the caller is likely to mark
1242 * the page clean when we return, causing the page to possibly revert
1243 * to all-zero's later.
1248 * swap_pager_getpages_async():
1250 * Right now this is emulation of asynchronous operation on top of
1251 * swap_pager_getpages().
1254 swap_pager_getpages_async(vm_object_t object, vm_page_t *m, int count,
1255 int *rbehind, int *rahead, pgo_getpages_iodone_t iodone, void *arg)
1259 r = swap_pager_getpages(object, m, count, rbehind, rahead);
1260 VM_OBJECT_WUNLOCK(object);
1265 case VM_PAGER_ERROR:
1272 panic("unhandled swap_pager_getpages() error %d", r);
1274 (iodone)(arg, m, count, error);
1275 VM_OBJECT_WLOCK(object);
1281 * swap_pager_putpages:
1283 * Assign swap (if necessary) and initiate I/O on the specified pages.
1285 * We support both OBJT_DEFAULT and OBJT_SWAP objects. DEFAULT objects
1286 * are automatically converted to SWAP objects.
1288 * In a low memory situation we may block in VOP_STRATEGY(), but the new
1289 * vm_page reservation system coupled with properly written VFS devices
1290 * should ensure that no low-memory deadlock occurs. This is an area
1293 * The parent has N vm_object_pip_add() references prior to
1294 * calling us and will remove references for rtvals[] that are
1295 * not set to VM_PAGER_PEND. We need to remove the rest on I/O
1298 * The parent has soft-busy'd the pages it passes us and will unbusy
1299 * those whos rtvals[] entry is not set to VM_PAGER_PEND on return.
1300 * We need to unbusy the rest on I/O completion.
1303 swap_pager_putpages(vm_object_t object, vm_page_t *m, int count,
1304 int flags, int *rtvals)
1309 if (count && m[0]->object != object) {
1310 panic("swap_pager_putpages: object mismatch %p/%p",
1319 * Turn object into OBJT_SWAP
1320 * check for bogus sysops
1321 * force sync if not pageout process
1323 if (object->type != OBJT_SWAP)
1324 swp_pager_meta_build(object, 0, SWAPBLK_NONE);
1325 VM_OBJECT_WUNLOCK(object);
1328 if (curproc != pageproc)
1331 sync = (flags & VM_PAGER_PUT_SYNC) != 0;
1336 * Assign swap blocks and issue I/O. We reallocate swap on the fly.
1337 * The page is left dirty until the pageout operation completes
1340 for (i = 0; i < count; i += n) {
1346 * Maximum I/O size is limited by a number of factors.
1348 n = min(BLIST_MAX_ALLOC, count - i);
1349 n = min(n, nsw_cluster_max);
1352 * Get biggest block of swap we can. If we fail, fall
1353 * back and try to allocate a smaller block. Don't go
1354 * overboard trying to allocate space if it would overly
1358 (blk = swp_pager_getswapspace(n)) == SWAPBLK_NONE &&
1363 if (blk == SWAPBLK_NONE) {
1364 for (j = 0; j < n; ++j)
1365 rtvals[i+j] = VM_PAGER_FAIL;
1370 * All I/O parameters have been satisfied, build the I/O
1371 * request and assign the swap space.
1374 bp = getpbuf(&nsw_wcount_sync);
1376 bp = getpbuf(&nsw_wcount_async);
1377 bp->b_flags = B_ASYNC;
1379 bp->b_flags |= B_PAGING;
1380 bp->b_iocmd = BIO_WRITE;
1382 bp->b_rcred = crhold(thread0.td_ucred);
1383 bp->b_wcred = crhold(thread0.td_ucred);
1384 bp->b_bcount = PAGE_SIZE * n;
1385 bp->b_bufsize = PAGE_SIZE * n;
1388 VM_OBJECT_WLOCK(object);
1389 for (j = 0; j < n; ++j) {
1390 vm_page_t mreq = m[i+j];
1392 swp_pager_meta_build(
1397 MPASS(mreq->dirty == VM_PAGE_BITS_ALL);
1398 mreq->oflags |= VPO_SWAPINPROG;
1399 bp->b_pages[j] = mreq;
1401 VM_OBJECT_WUNLOCK(object);
1404 * Must set dirty range for NFS to work.
1407 bp->b_dirtyend = bp->b_bcount;
1409 VM_CNT_INC(v_swapout);
1410 VM_CNT_ADD(v_swappgsout, bp->b_npages);
1413 * We unconditionally set rtvals[] to VM_PAGER_PEND so that we
1414 * can call the async completion routine at the end of a
1415 * synchronous I/O operation. Otherwise, our caller would
1416 * perform duplicate unbusy and wakeup operations on the page
1417 * and object, respectively.
1419 for (j = 0; j < n; j++)
1420 rtvals[i + j] = VM_PAGER_PEND;
1425 * NOTE: b_blkno is destroyed by the call to swapdev_strategy
1427 if (sync == FALSE) {
1428 bp->b_iodone = swp_pager_async_iodone;
1430 swp_pager_strategy(bp);
1437 * NOTE: b_blkno is destroyed by the call to swapdev_strategy
1439 bp->b_iodone = bdone;
1440 swp_pager_strategy(bp);
1443 * Wait for the sync I/O to complete.
1445 bwait(bp, PVM, "swwrt");
1448 * Now that we are through with the bp, we can call the
1449 * normal async completion, which frees everything up.
1451 swp_pager_async_iodone(bp);
1453 VM_OBJECT_WLOCK(object);
1457 * swp_pager_async_iodone:
1459 * Completion routine for asynchronous reads and writes from/to swap.
1460 * Also called manually by synchronous code to finish up a bp.
1462 * This routine may not sleep.
1465 swp_pager_async_iodone(struct buf *bp)
1468 vm_object_t object = NULL;
1473 if (bp->b_ioflags & BIO_ERROR) {
1475 "swap_pager: I/O error - %s failed; blkno %ld,"
1476 "size %ld, error %d\n",
1477 ((bp->b_iocmd == BIO_READ) ? "pagein" : "pageout"),
1485 * remove the mapping for kernel virtual
1488 pmap_qremove((vm_offset_t)bp->b_data, bp->b_npages);
1490 bp->b_data = bp->b_kvabase;
1493 object = bp->b_pages[0]->object;
1494 VM_OBJECT_WLOCK(object);
1498 * cleanup pages. If an error occurs writing to swap, we are in
1499 * very serious trouble. If it happens to be a disk error, though,
1500 * we may be able to recover by reassigning the swap later on. So
1501 * in this case we remove the m->swapblk assignment for the page
1502 * but do not free it in the rlist. The errornous block(s) are thus
1503 * never reallocated as swap. Redirty the page and continue.
1505 for (i = 0; i < bp->b_npages; ++i) {
1506 vm_page_t m = bp->b_pages[i];
1508 m->oflags &= ~VPO_SWAPINPROG;
1509 if (m->oflags & VPO_SWAPSLEEP) {
1510 m->oflags &= ~VPO_SWAPSLEEP;
1511 wakeup(&object->paging_in_progress);
1514 if (bp->b_ioflags & BIO_ERROR) {
1516 * If an error occurs I'd love to throw the swapblk
1517 * away without freeing it back to swapspace, so it
1518 * can never be used again. But I can't from an
1521 if (bp->b_iocmd == BIO_READ) {
1523 * NOTE: for reads, m->dirty will probably
1524 * be overridden by the original caller of
1525 * getpages so don't play cute tricks here.
1530 * If a write error occurs, reactivate page
1531 * so it doesn't clog the inactive list,
1532 * then finish the I/O.
1534 MPASS(m->dirty == VM_PAGE_BITS_ALL);
1536 vm_page_activate(m);
1540 } else if (bp->b_iocmd == BIO_READ) {
1542 * NOTE: for reads, m->dirty will probably be
1543 * overridden by the original caller of getpages so
1544 * we cannot set them in order to free the underlying
1545 * swap in a low-swap situation. I don't think we'd
1546 * want to do that anyway, but it was an optimization
1547 * that existed in the old swapper for a time before
1548 * it got ripped out due to precisely this problem.
1550 KASSERT(!pmap_page_is_mapped(m),
1551 ("swp_pager_async_iodone: page %p is mapped", m));
1552 KASSERT(m->dirty == 0,
1553 ("swp_pager_async_iodone: page %p is dirty", m));
1555 m->valid = VM_PAGE_BITS_ALL;
1556 if (i < bp->b_pgbefore ||
1557 i >= bp->b_npages - bp->b_pgafter)
1558 vm_page_readahead_finish(m);
1561 * For write success, clear the dirty
1562 * status, then finish the I/O ( which decrements the
1563 * busy count and possibly wakes waiter's up ).
1564 * A page is only written to swap after a period of
1565 * inactivity. Therefore, we do not expect it to be
1568 KASSERT(!pmap_page_is_write_mapped(m),
1569 ("swp_pager_async_iodone: page %p is not write"
1573 vm_page_deactivate_noreuse(m);
1580 * adjust pip. NOTE: the original parent may still have its own
1581 * pip refs on the object.
1583 if (object != NULL) {
1584 vm_object_pip_wakeupn(object, bp->b_npages);
1585 VM_OBJECT_WUNLOCK(object);
1589 * swapdev_strategy() manually sets b_vp and b_bufobj before calling
1590 * bstrategy(). Set them back to NULL now we're done with it, or we'll
1591 * trigger a KASSERT in relpbuf().
1595 bp->b_bufobj = NULL;
1598 * release the physical I/O buffer
1602 ((bp->b_iocmd == BIO_READ) ? &nsw_rcount :
1603 ((bp->b_flags & B_ASYNC) ?
1612 swap_pager_nswapdev(void)
1619 * SWP_PAGER_FORCE_PAGEIN() - force a swap block to be paged in
1621 * This routine dissociates the page at the given index within an object
1622 * from its backing store, paging it in if it does not reside in memory.
1623 * If the page is paged in, it is marked dirty and placed in the laundry
1624 * queue. The page is marked dirty because it no longer has backing
1625 * store. It is placed in the laundry queue because it has not been
1626 * accessed recently. Otherwise, it would already reside in memory.
1628 * We also attempt to swap in all other pages in the swap block.
1629 * However, we only guarantee that the one at the specified index is
1632 * XXX - The code to page the whole block in doesn't work, so we
1633 * revert to the one-by-one behavior for now. Sigh.
1636 swp_pager_force_pagein(vm_object_t object, vm_pindex_t pindex)
1640 vm_object_pip_add(object, 1);
1641 m = vm_page_grab(object, pindex, VM_ALLOC_NORMAL);
1642 if (m->valid == VM_PAGE_BITS_ALL) {
1643 vm_object_pip_wakeup(object);
1647 if (m->wire_count == 0 && m->queue == PQ_NONE)
1648 panic("page %p is neither wired nor queued", m);
1652 vm_pager_page_unswapped(m);
1656 if (swap_pager_getpages(object, &m, 1, NULL, NULL) != VM_PAGER_OK)
1657 panic("swap_pager_force_pagein: read from swap failed");/*XXX*/
1658 vm_object_pip_wakeup(object);
1664 vm_pager_page_unswapped(m);
1668 * swap_pager_swapoff:
1670 * Page in all of the pages that have been paged out to the
1671 * given device. The corresponding blocks in the bitmap must be
1672 * marked as allocated and the device must be flagged SW_CLOSING.
1673 * There may be no processes swapped out to the device.
1675 * This routine may block.
1678 swap_pager_swapoff(struct swdevt *sp)
1685 sx_assert(&swdev_syscall_lock, SA_XLOCKED);
1689 mtx_lock(&vm_object_list_mtx);
1690 TAILQ_FOREACH(object, &vm_object_list, object_list) {
1691 if (object->type != OBJT_SWAP)
1693 mtx_unlock(&vm_object_list_mtx);
1694 /* Depends on type-stability. */
1695 VM_OBJECT_WLOCK(object);
1698 * Dead objects are eventually terminated on their own.
1700 if ((object->flags & OBJ_DEAD) != 0)
1704 * Sync with fences placed after pctrie
1705 * initialization. We must not access pctrie below
1706 * unless we checked that our object is swap and not
1709 atomic_thread_fence_acq();
1710 if (object->type != OBJT_SWAP)
1713 for (pi = 0; (sb = SWAP_PCTRIE_LOOKUP_GE(
1714 &object->un_pager.swp.swp_blks, pi)) != NULL; ) {
1715 pi = sb->p + SWAP_META_PAGES;
1716 for (i = 0; i < SWAP_META_PAGES; i++) {
1717 if (sb->d[i] == SWAPBLK_NONE)
1719 if (swp_pager_isondev(sb->d[i], sp))
1720 swp_pager_force_pagein(object,
1725 VM_OBJECT_WUNLOCK(object);
1726 mtx_lock(&vm_object_list_mtx);
1728 mtx_unlock(&vm_object_list_mtx);
1732 * Objects may be locked or paging to the device being
1733 * removed, so we will miss their pages and need to
1734 * make another pass. We have marked this device as
1735 * SW_CLOSING, so the activity should finish soon.
1738 if (retries > 100) {
1739 panic("swapoff: failed to locate %d swap blocks",
1742 pause("swpoff", hz / 20);
1745 EVENTHANDLER_INVOKE(swapoff, sp);
1748 /************************************************************************
1750 ************************************************************************
1752 * These routines manipulate the swap metadata stored in the
1755 * Swap metadata is implemented with a global hash and not directly
1756 * linked into the object. Instead the object simply contains
1757 * appropriate tracking counters.
1761 * SWP_PAGER_SWBLK_EMPTY() - is a range of blocks free?
1764 swp_pager_swblk_empty(struct swblk *sb, int start, int limit)
1768 MPASS(0 <= start && start <= limit && limit <= SWAP_META_PAGES);
1769 for (i = start; i < limit; i++) {
1770 if (sb->d[i] != SWAPBLK_NONE)
1777 * SWP_PAGER_META_BUILD() - add swap block to swap meta data for object
1779 * We first convert the object to a swap object if it is a default
1782 * The specified swapblk is added to the object's swap metadata. If
1783 * the swapblk is not valid, it is freed instead. Any previously
1784 * assigned swapblk is freed.
1787 swp_pager_meta_build(vm_object_t object, vm_pindex_t pindex, daddr_t swapblk)
1789 static volatile int swblk_zone_exhausted, swpctrie_zone_exhausted;
1790 struct swblk *sb, *sb1;
1791 vm_pindex_t modpi, rdpi;
1794 VM_OBJECT_ASSERT_WLOCKED(object);
1797 * Convert default object to swap object if necessary
1799 if (object->type != OBJT_SWAP) {
1800 pctrie_init(&object->un_pager.swp.swp_blks);
1803 * Ensure that swap_pager_swapoff()'s iteration over
1804 * object_list does not see a garbage pctrie.
1806 atomic_thread_fence_rel();
1808 object->type = OBJT_SWAP;
1809 KASSERT(object->handle == NULL, ("default pager with handle"));
1812 rdpi = rounddown(pindex, SWAP_META_PAGES);
1813 sb = SWAP_PCTRIE_LOOKUP(&object->un_pager.swp.swp_blks, rdpi);
1815 if (swapblk == SWAPBLK_NONE)
1818 sb = uma_zalloc(swblk_zone, M_NOWAIT | (curproc ==
1819 pageproc ? M_USE_RESERVE : 0));
1822 for (i = 0; i < SWAP_META_PAGES; i++)
1823 sb->d[i] = SWAPBLK_NONE;
1824 if (atomic_cmpset_int(&swblk_zone_exhausted,
1826 printf("swblk zone ok\n");
1829 VM_OBJECT_WUNLOCK(object);
1830 if (uma_zone_exhausted(swblk_zone)) {
1831 if (atomic_cmpset_int(&swblk_zone_exhausted,
1833 printf("swap blk zone exhausted, "
1834 "increase kern.maxswzone\n");
1835 vm_pageout_oom(VM_OOM_SWAPZ);
1836 pause("swzonxb", 10);
1838 uma_zwait(swblk_zone);
1839 VM_OBJECT_WLOCK(object);
1840 sb = SWAP_PCTRIE_LOOKUP(&object->un_pager.swp.swp_blks,
1844 * Somebody swapped out a nearby page,
1845 * allocating swblk at the rdpi index,
1846 * while we dropped the object lock.
1851 error = SWAP_PCTRIE_INSERT(
1852 &object->un_pager.swp.swp_blks, sb);
1854 if (atomic_cmpset_int(&swpctrie_zone_exhausted,
1856 printf("swpctrie zone ok\n");
1859 VM_OBJECT_WUNLOCK(object);
1860 if (uma_zone_exhausted(swpctrie_zone)) {
1861 if (atomic_cmpset_int(&swpctrie_zone_exhausted,
1863 printf("swap pctrie zone exhausted, "
1864 "increase kern.maxswzone\n");
1865 vm_pageout_oom(VM_OOM_SWAPZ);
1866 pause("swzonxp", 10);
1868 uma_zwait(swpctrie_zone);
1869 VM_OBJECT_WLOCK(object);
1870 sb1 = SWAP_PCTRIE_LOOKUP(&object->un_pager.swp.swp_blks,
1873 uma_zfree(swblk_zone, sb);
1880 MPASS(sb->p == rdpi);
1882 modpi = pindex % SWAP_META_PAGES;
1883 /* Delete prior contents of metadata. */
1884 if (sb->d[modpi] != SWAPBLK_NONE)
1885 swp_pager_freeswapspace(sb->d[modpi], 1);
1886 /* Enter block into metadata. */
1887 sb->d[modpi] = swapblk;
1890 * Free the swblk if we end up with the empty page run.
1892 if (swapblk == SWAPBLK_NONE &&
1893 swp_pager_swblk_empty(sb, 0, SWAP_META_PAGES)) {
1894 SWAP_PCTRIE_REMOVE(&object->un_pager.swp.swp_blks, rdpi);
1895 uma_zfree(swblk_zone, sb);
1900 * SWP_PAGER_META_FREE() - free a range of blocks in the object's swap metadata
1902 * The requested range of blocks is freed, with any associated swap
1903 * returned to the swap bitmap.
1905 * This routine will free swap metadata structures as they are cleaned
1906 * out. This routine does *NOT* operate on swap metadata associated
1907 * with resident pages.
1910 swp_pager_meta_free(vm_object_t object, vm_pindex_t pindex, vm_pindex_t count)
1913 daddr_t first_free, num_free;
1915 int i, limit, start;
1917 VM_OBJECT_ASSERT_WLOCKED(object);
1918 if (object->type != OBJT_SWAP || count == 0)
1921 first_free = SWAPBLK_NONE;
1923 last = pindex + count;
1925 sb = SWAP_PCTRIE_LOOKUP_GE(&object->un_pager.swp.swp_blks,
1926 rounddown(pindex, SWAP_META_PAGES));
1927 if (sb == NULL || sb->p >= last)
1929 start = pindex > sb->p ? pindex - sb->p : 0;
1930 limit = last - sb->p < SWAP_META_PAGES ? last - sb->p :
1932 for (i = start; i < limit; i++) {
1933 if (sb->d[i] == SWAPBLK_NONE)
1935 if (first_free + num_free == sb->d[i])
1938 swp_pager_freeswapspace(first_free, num_free);
1939 first_free = sb->d[i];
1942 sb->d[i] = SWAPBLK_NONE;
1944 if (swp_pager_swblk_empty(sb, 0, start) &&
1945 swp_pager_swblk_empty(sb, limit, SWAP_META_PAGES)) {
1946 SWAP_PCTRIE_REMOVE(&object->un_pager.swp.swp_blks,
1948 uma_zfree(swblk_zone, sb);
1950 pindex = sb->p + SWAP_META_PAGES;
1952 swp_pager_freeswapspace(first_free, num_free);
1956 * SWP_PAGER_META_FREE_ALL() - destroy all swap metadata associated with object
1958 * This routine locates and destroys all swap metadata associated with
1962 swp_pager_meta_free_all(vm_object_t object)
1965 daddr_t first_free, num_free;
1969 VM_OBJECT_ASSERT_WLOCKED(object);
1970 if (object->type != OBJT_SWAP)
1973 first_free = SWAPBLK_NONE;
1975 for (pindex = 0; (sb = SWAP_PCTRIE_LOOKUP_GE(
1976 &object->un_pager.swp.swp_blks, pindex)) != NULL;) {
1977 pindex = sb->p + SWAP_META_PAGES;
1978 for (i = 0; i < SWAP_META_PAGES; i++) {
1979 if (sb->d[i] == SWAPBLK_NONE)
1981 if (first_free + num_free == sb->d[i])
1984 swp_pager_freeswapspace(first_free, num_free);
1985 first_free = sb->d[i];
1989 SWAP_PCTRIE_REMOVE(&object->un_pager.swp.swp_blks, sb->p);
1990 uma_zfree(swblk_zone, sb);
1992 swp_pager_freeswapspace(first_free, num_free);
1996 * SWP_PAGER_METACTL() - misc control of swap meta data.
1998 * This routine is capable of looking up, or removing swapblk
1999 * assignments in the swap meta data. It returns the swapblk being
2000 * looked-up, popped, or SWAPBLK_NONE if the block was invalid.
2002 * When acting on a busy resident page and paging is in progress, we
2003 * have to wait until paging is complete but otherwise can act on the
2006 * SWM_POP remove from meta data but do not free it
2009 swp_pager_meta_ctl(vm_object_t object, vm_pindex_t pindex, int flags)
2014 if ((flags & SWM_POP) != 0)
2015 VM_OBJECT_ASSERT_WLOCKED(object);
2017 VM_OBJECT_ASSERT_LOCKED(object);
2020 * The meta data only exists if the object is OBJT_SWAP
2021 * and even then might not be allocated yet.
2023 if (object->type != OBJT_SWAP)
2024 return (SWAPBLK_NONE);
2026 sb = SWAP_PCTRIE_LOOKUP(&object->un_pager.swp.swp_blks,
2027 rounddown(pindex, SWAP_META_PAGES));
2029 return (SWAPBLK_NONE);
2030 r1 = sb->d[pindex % SWAP_META_PAGES];
2031 if (r1 == SWAPBLK_NONE)
2032 return (SWAPBLK_NONE);
2033 if ((flags & SWM_POP) != 0) {
2034 sb->d[pindex % SWAP_META_PAGES] = SWAPBLK_NONE;
2035 if (swp_pager_swblk_empty(sb, 0, SWAP_META_PAGES)) {
2036 SWAP_PCTRIE_REMOVE(&object->un_pager.swp.swp_blks,
2037 rounddown(pindex, SWAP_META_PAGES));
2038 uma_zfree(swblk_zone, sb);
2045 * Returns the least page index which is greater than or equal to the
2046 * parameter pindex and for which there is a swap block allocated.
2047 * Returns object's size if the object's type is not swap or if there
2048 * are no allocated swap blocks for the object after the requested
2052 swap_pager_find_least(vm_object_t object, vm_pindex_t pindex)
2057 VM_OBJECT_ASSERT_LOCKED(object);
2058 if (object->type != OBJT_SWAP)
2059 return (object->size);
2061 sb = SWAP_PCTRIE_LOOKUP_GE(&object->un_pager.swp.swp_blks,
2062 rounddown(pindex, SWAP_META_PAGES));
2064 return (object->size);
2065 if (sb->p < pindex) {
2066 for (i = pindex % SWAP_META_PAGES; i < SWAP_META_PAGES; i++) {
2067 if (sb->d[i] != SWAPBLK_NONE)
2070 sb = SWAP_PCTRIE_LOOKUP_GE(&object->un_pager.swp.swp_blks,
2071 roundup(pindex, SWAP_META_PAGES));
2073 return (object->size);
2075 for (i = 0; i < SWAP_META_PAGES; i++) {
2076 if (sb->d[i] != SWAPBLK_NONE)
2081 * We get here if a swblk is present in the trie but it
2082 * doesn't map any blocks.
2085 return (object->size);
2089 * System call swapon(name) enables swapping on device name,
2090 * which must be in the swdevsw. Return EBUSY
2091 * if already swapping on this device.
2093 #ifndef _SYS_SYSPROTO_H_
2094 struct swapon_args {
2104 sys_swapon(struct thread *td, struct swapon_args *uap)
2108 struct nameidata nd;
2111 error = priv_check(td, PRIV_SWAPON);
2115 sx_xlock(&swdev_syscall_lock);
2118 * Swap metadata may not fit in the KVM if we have physical
2121 if (swblk_zone == NULL) {
2126 NDINIT(&nd, LOOKUP, ISOPEN | FOLLOW | AUDITVNODE1, UIO_USERSPACE,
2132 NDFREE(&nd, NDF_ONLY_PNBUF);
2135 if (vn_isdisk(vp, &error)) {
2136 error = swapongeom(vp);
2137 } else if (vp->v_type == VREG &&
2138 (vp->v_mount->mnt_vfc->vfc_flags & VFCF_NETWORK) != 0 &&
2139 (error = VOP_GETATTR(vp, &attr, td->td_ucred)) == 0) {
2141 * Allow direct swapping to NFS regular files in the same
2142 * way that nfs_mountroot() sets up diskless swapping.
2144 error = swaponvp(td, vp, attr.va_size / DEV_BSIZE);
2150 sx_xunlock(&swdev_syscall_lock);
2155 * Check that the total amount of swap currently configured does not
2156 * exceed half the theoretical maximum. If it does, print a warning
2160 swapon_check_swzone(void)
2162 unsigned long maxpages, npages;
2164 npages = swap_total / PAGE_SIZE;
2165 /* absolute maximum we can handle assuming 100% efficiency */
2166 maxpages = uma_zone_get_max(swblk_zone) * SWAP_META_PAGES;
2168 /* recommend using no more than half that amount */
2169 if (npages > maxpages / 2) {
2170 printf("warning: total configured swap (%lu pages) "
2171 "exceeds maximum recommended amount (%lu pages).\n",
2172 npages, maxpages / 2);
2173 printf("warning: increase kern.maxswzone "
2174 "or reduce amount of swap.\n");
2179 swaponsomething(struct vnode *vp, void *id, u_long nblks,
2180 sw_strategy_t *strategy, sw_close_t *close, dev_t dev, int flags)
2182 struct swdevt *sp, *tsp;
2187 * nblks is in DEV_BSIZE'd chunks, convert to PAGE_SIZE'd chunks.
2188 * First chop nblks off to page-align it, then convert.
2190 * sw->sw_nblks is in page-sized chunks now too.
2192 nblks &= ~(ctodb(1) - 1);
2193 nblks = dbtoc(nblks);
2196 * If we go beyond this, we get overflows in the radix
2199 mblocks = 0x40000000 / BLIST_META_RADIX;
2200 if (nblks > mblocks) {
2202 "WARNING: reducing swap size to maximum of %luMB per unit\n",
2203 mblocks / 1024 / 1024 * PAGE_SIZE);
2207 sp = malloc(sizeof *sp, M_VMPGDATA, M_WAITOK | M_ZERO);
2212 sp->sw_nblks = nblks;
2214 sp->sw_strategy = strategy;
2215 sp->sw_close = close;
2216 sp->sw_flags = flags;
2218 sp->sw_blist = blist_create(nblks, M_WAITOK);
2220 * Do not free the first two block in order to avoid overwriting
2221 * any bsd label at the front of the partition
2223 blist_free(sp->sw_blist, 2, nblks - 2);
2226 mtx_lock(&sw_dev_mtx);
2227 TAILQ_FOREACH(tsp, &swtailq, sw_list) {
2228 if (tsp->sw_end >= dvbase) {
2230 * We put one uncovered page between the devices
2231 * in order to definitively prevent any cross-device
2234 dvbase = tsp->sw_end + 1;
2237 sp->sw_first = dvbase;
2238 sp->sw_end = dvbase + nblks;
2239 TAILQ_INSERT_TAIL(&swtailq, sp, sw_list);
2241 swap_pager_avail += nblks - 2;
2242 swap_total += (vm_ooffset_t)nblks * PAGE_SIZE;
2243 swapon_check_swzone();
2245 mtx_unlock(&sw_dev_mtx);
2246 EVENTHANDLER_INVOKE(swapon, sp);
2250 * SYSCALL: swapoff(devname)
2252 * Disable swapping on the given device.
2254 * XXX: Badly designed system call: it should use a device index
2255 * rather than filename as specification. We keep sw_vp around
2256 * only to make this work.
2258 #ifndef _SYS_SYSPROTO_H_
2259 struct swapoff_args {
2269 sys_swapoff(struct thread *td, struct swapoff_args *uap)
2272 struct nameidata nd;
2276 error = priv_check(td, PRIV_SWAPOFF);
2280 sx_xlock(&swdev_syscall_lock);
2282 NDINIT(&nd, LOOKUP, FOLLOW | AUDITVNODE1, UIO_USERSPACE, uap->name,
2287 NDFREE(&nd, NDF_ONLY_PNBUF);
2290 mtx_lock(&sw_dev_mtx);
2291 TAILQ_FOREACH(sp, &swtailq, sw_list) {
2292 if (sp->sw_vp == vp)
2295 mtx_unlock(&sw_dev_mtx);
2300 error = swapoff_one(sp, td->td_ucred);
2302 sx_xunlock(&swdev_syscall_lock);
2307 swapoff_one(struct swdevt *sp, struct ucred *cred)
2314 sx_assert(&swdev_syscall_lock, SA_XLOCKED);
2316 (void) vn_lock(sp->sw_vp, LK_EXCLUSIVE | LK_RETRY);
2317 error = mac_system_check_swapoff(cred, sp->sw_vp);
2318 (void) VOP_UNLOCK(sp->sw_vp, 0);
2322 nblks = sp->sw_nblks;
2325 * We can turn off this swap device safely only if the
2326 * available virtual memory in the system will fit the amount
2327 * of data we will have to page back in, plus an epsilon so
2328 * the system doesn't become critically low on swap space.
2330 if (vm_cnt.v_free_count + swap_pager_avail < nblks + nswap_lowat)
2334 * Prevent further allocations on this device.
2336 mtx_lock(&sw_dev_mtx);
2337 sp->sw_flags |= SW_CLOSING;
2338 swap_pager_avail -= blist_fill(sp->sw_blist, 0, nblks);
2339 swap_total -= (vm_ooffset_t)nblks * PAGE_SIZE;
2340 mtx_unlock(&sw_dev_mtx);
2343 * Page in the contents of the device and close it.
2345 swap_pager_swapoff(sp);
2347 sp->sw_close(curthread, sp);
2348 mtx_lock(&sw_dev_mtx);
2350 TAILQ_REMOVE(&swtailq, sp, sw_list);
2352 if (nswapdev == 0) {
2353 swap_pager_full = 2;
2354 swap_pager_almost_full = 1;
2358 mtx_unlock(&sw_dev_mtx);
2359 blist_destroy(sp->sw_blist);
2360 free(sp, M_VMPGDATA);
2367 struct swdevt *sp, *spt;
2368 const char *devname;
2371 sx_xlock(&swdev_syscall_lock);
2373 mtx_lock(&sw_dev_mtx);
2374 TAILQ_FOREACH_SAFE(sp, &swtailq, sw_list, spt) {
2375 mtx_unlock(&sw_dev_mtx);
2376 if (vn_isdisk(sp->sw_vp, NULL))
2377 devname = devtoname(sp->sw_vp->v_rdev);
2380 error = swapoff_one(sp, thread0.td_ucred);
2382 printf("Cannot remove swap device %s (error=%d), "
2383 "skipping.\n", devname, error);
2384 } else if (bootverbose) {
2385 printf("Swap device %s removed.\n", devname);
2387 mtx_lock(&sw_dev_mtx);
2389 mtx_unlock(&sw_dev_mtx);
2391 sx_xunlock(&swdev_syscall_lock);
2395 swap_pager_status(int *total, int *used)
2401 mtx_lock(&sw_dev_mtx);
2402 TAILQ_FOREACH(sp, &swtailq, sw_list) {
2403 *total += sp->sw_nblks;
2404 *used += sp->sw_used;
2406 mtx_unlock(&sw_dev_mtx);
2410 swap_dev_info(int name, struct xswdev *xs, char *devname, size_t len)
2413 const char *tmp_devname;
2418 mtx_lock(&sw_dev_mtx);
2419 TAILQ_FOREACH(sp, &swtailq, sw_list) {
2424 xs->xsw_version = XSWDEV_VERSION;
2425 xs->xsw_dev = sp->sw_dev;
2426 xs->xsw_flags = sp->sw_flags;
2427 xs->xsw_nblks = sp->sw_nblks;
2428 xs->xsw_used = sp->sw_used;
2429 if (devname != NULL) {
2430 if (vn_isdisk(sp->sw_vp, NULL))
2431 tmp_devname = devtoname(sp->sw_vp->v_rdev);
2433 tmp_devname = "[file]";
2434 strncpy(devname, tmp_devname, len);
2439 mtx_unlock(&sw_dev_mtx);
2443 #if defined(COMPAT_FREEBSD11)
2444 #define XSWDEV_VERSION_11 1
2455 sysctl_vm_swap_info(SYSCTL_HANDLER_ARGS)
2458 #if defined(COMPAT_FREEBSD11)
2459 struct xswdev11 xs11;
2463 if (arg2 != 1) /* name length */
2465 error = swap_dev_info(*(int *)arg1, &xs, NULL, 0);
2468 #if defined(COMPAT_FREEBSD11)
2469 if (req->oldlen == sizeof(xs11)) {
2470 xs11.xsw_version = XSWDEV_VERSION_11;
2471 xs11.xsw_dev = xs.xsw_dev; /* truncation */
2472 xs11.xsw_flags = xs.xsw_flags;
2473 xs11.xsw_nblks = xs.xsw_nblks;
2474 xs11.xsw_used = xs.xsw_used;
2475 error = SYSCTL_OUT(req, &xs11, sizeof(xs11));
2478 error = SYSCTL_OUT(req, &xs, sizeof(xs));
2482 SYSCTL_INT(_vm, OID_AUTO, nswapdev, CTLFLAG_RD, &nswapdev, 0,
2483 "Number of swap devices");
2484 SYSCTL_NODE(_vm, OID_AUTO, swap_info, CTLFLAG_RD | CTLFLAG_MPSAFE,
2485 sysctl_vm_swap_info,
2486 "Swap statistics by device");
2489 * Count the approximate swap usage in pages for a vmspace. The
2490 * shadowed or not yet copied on write swap blocks are not accounted.
2491 * The map must be locked.
2494 vmspace_swap_count(struct vmspace *vmspace)
2504 map = &vmspace->vm_map;
2507 for (cur = map->header.next; cur != &map->header; cur = cur->next) {
2508 if ((cur->eflags & MAP_ENTRY_IS_SUB_MAP) != 0)
2510 object = cur->object.vm_object;
2511 if (object == NULL || object->type != OBJT_SWAP)
2513 VM_OBJECT_RLOCK(object);
2514 if (object->type != OBJT_SWAP)
2516 pi = OFF_TO_IDX(cur->offset);
2517 e = pi + OFF_TO_IDX(cur->end - cur->start);
2518 for (;; pi = sb->p + SWAP_META_PAGES) {
2519 sb = SWAP_PCTRIE_LOOKUP_GE(
2520 &object->un_pager.swp.swp_blks, pi);
2521 if (sb == NULL || sb->p >= e)
2523 for (i = 0; i < SWAP_META_PAGES; i++) {
2524 if (sb->p + i < e &&
2525 sb->d[i] != SWAPBLK_NONE)
2530 VM_OBJECT_RUNLOCK(object);
2538 * Swapping onto disk devices.
2542 static g_orphan_t swapgeom_orphan;
2544 static struct g_class g_swap_class = {
2546 .version = G_VERSION,
2547 .orphan = swapgeom_orphan,
2550 DECLARE_GEOM_CLASS(g_swap_class, g_class);
2554 swapgeom_close_ev(void *arg, int flags)
2556 struct g_consumer *cp;
2559 g_access(cp, -1, -1, 0);
2561 g_destroy_consumer(cp);
2565 * Add a reference to the g_consumer for an inflight transaction.
2568 swapgeom_acquire(struct g_consumer *cp)
2571 mtx_assert(&sw_dev_mtx, MA_OWNED);
2576 * Remove a reference from the g_consumer. Post a close event if all
2577 * references go away, since the function might be called from the
2581 swapgeom_release(struct g_consumer *cp, struct swdevt *sp)
2584 mtx_assert(&sw_dev_mtx, MA_OWNED);
2586 if (cp->index == 0) {
2587 if (g_post_event(swapgeom_close_ev, cp, M_NOWAIT, NULL) == 0)
2593 swapgeom_done(struct bio *bp2)
2597 struct g_consumer *cp;
2599 bp = bp2->bio_caller2;
2601 bp->b_ioflags = bp2->bio_flags;
2603 bp->b_ioflags |= BIO_ERROR;
2604 bp->b_resid = bp->b_bcount - bp2->bio_completed;
2605 bp->b_error = bp2->bio_error;
2607 sp = bp2->bio_caller1;
2608 mtx_lock(&sw_dev_mtx);
2609 swapgeom_release(cp, sp);
2610 mtx_unlock(&sw_dev_mtx);
2615 swapgeom_strategy(struct buf *bp, struct swdevt *sp)
2618 struct g_consumer *cp;
2620 mtx_lock(&sw_dev_mtx);
2623 mtx_unlock(&sw_dev_mtx);
2624 bp->b_error = ENXIO;
2625 bp->b_ioflags |= BIO_ERROR;
2629 swapgeom_acquire(cp);
2630 mtx_unlock(&sw_dev_mtx);
2631 if (bp->b_iocmd == BIO_WRITE)
2634 bio = g_alloc_bio();
2636 mtx_lock(&sw_dev_mtx);
2637 swapgeom_release(cp, sp);
2638 mtx_unlock(&sw_dev_mtx);
2639 bp->b_error = ENOMEM;
2640 bp->b_ioflags |= BIO_ERROR;
2645 bio->bio_caller1 = sp;
2646 bio->bio_caller2 = bp;
2647 bio->bio_cmd = bp->b_iocmd;
2648 bio->bio_offset = (bp->b_blkno - sp->sw_first) * PAGE_SIZE;
2649 bio->bio_length = bp->b_bcount;
2650 bio->bio_done = swapgeom_done;
2651 if (!buf_mapped(bp)) {
2652 bio->bio_ma = bp->b_pages;
2653 bio->bio_data = unmapped_buf;
2654 bio->bio_ma_offset = (vm_offset_t)bp->b_offset & PAGE_MASK;
2655 bio->bio_ma_n = bp->b_npages;
2656 bio->bio_flags |= BIO_UNMAPPED;
2658 bio->bio_data = bp->b_data;
2661 g_io_request(bio, cp);
2666 swapgeom_orphan(struct g_consumer *cp)
2671 mtx_lock(&sw_dev_mtx);
2672 TAILQ_FOREACH(sp, &swtailq, sw_list) {
2673 if (sp->sw_id == cp) {
2674 sp->sw_flags |= SW_CLOSING;
2679 * Drop reference we were created with. Do directly since we're in a
2680 * special context where we don't have to queue the call to
2681 * swapgeom_close_ev().
2684 destroy = ((sp != NULL) && (cp->index == 0));
2687 mtx_unlock(&sw_dev_mtx);
2689 swapgeom_close_ev(cp, 0);
2693 swapgeom_close(struct thread *td, struct swdevt *sw)
2695 struct g_consumer *cp;
2697 mtx_lock(&sw_dev_mtx);
2700 mtx_unlock(&sw_dev_mtx);
2703 * swapgeom_close() may be called from the biodone context,
2704 * where we cannot perform topology changes. Delegate the
2705 * work to the events thread.
2708 g_waitfor_event(swapgeom_close_ev, cp, M_WAITOK, NULL);
2712 swapongeom_locked(struct cdev *dev, struct vnode *vp)
2714 struct g_provider *pp;
2715 struct g_consumer *cp;
2716 static struct g_geom *gp;
2721 pp = g_dev_getprovider(dev);
2724 mtx_lock(&sw_dev_mtx);
2725 TAILQ_FOREACH(sp, &swtailq, sw_list) {
2727 if (cp != NULL && cp->provider == pp) {
2728 mtx_unlock(&sw_dev_mtx);
2732 mtx_unlock(&sw_dev_mtx);
2734 gp = g_new_geomf(&g_swap_class, "swap");
2735 cp = g_new_consumer(gp);
2736 cp->index = 1; /* Number of active I/Os, plus one for being active. */
2737 cp->flags |= G_CF_DIRECT_SEND | G_CF_DIRECT_RECEIVE;
2740 * XXX: Every time you think you can improve the margin for
2741 * footshooting, somebody depends on the ability to do so:
2742 * savecore(8) wants to write to our swapdev so we cannot
2743 * set an exclusive count :-(
2745 error = g_access(cp, 1, 1, 0);
2748 g_destroy_consumer(cp);
2751 nblks = pp->mediasize / DEV_BSIZE;
2752 swaponsomething(vp, cp, nblks, swapgeom_strategy,
2753 swapgeom_close, dev2udev(dev),
2754 (pp->flags & G_PF_ACCEPT_UNMAPPED) != 0 ? SW_UNMAPPED : 0);
2759 swapongeom(struct vnode *vp)
2763 vn_lock(vp, LK_EXCLUSIVE | LK_RETRY);
2764 if (vp->v_type != VCHR || (vp->v_iflag & VI_DOOMED) != 0) {
2768 error = swapongeom_locked(vp->v_rdev, vp);
2769 g_topology_unlock();
2778 * This is used mainly for network filesystem (read: probably only tested
2779 * with NFS) swapfiles.
2784 swapdev_strategy(struct buf *bp, struct swdevt *sp)
2788 bp->b_blkno = ctodb(bp->b_blkno - sp->sw_first);
2792 if (bp->b_iocmd == BIO_WRITE) {
2794 bufobj_wdrop(bp->b_bufobj);
2795 bufobj_wref(&vp2->v_bufobj);
2797 if (bp->b_bufobj != &vp2->v_bufobj)
2798 bp->b_bufobj = &vp2->v_bufobj;
2800 bp->b_iooffset = dbtob(bp->b_blkno);
2806 swapdev_close(struct thread *td, struct swdevt *sp)
2809 VOP_CLOSE(sp->sw_vp, FREAD | FWRITE, td->td_ucred, td);
2815 swaponvp(struct thread *td, struct vnode *vp, u_long nblks)
2822 mtx_lock(&sw_dev_mtx);
2823 TAILQ_FOREACH(sp, &swtailq, sw_list) {
2824 if (sp->sw_id == vp) {
2825 mtx_unlock(&sw_dev_mtx);
2829 mtx_unlock(&sw_dev_mtx);
2831 (void) vn_lock(vp, LK_EXCLUSIVE | LK_RETRY);
2833 error = mac_system_check_swapon(td->td_ucred, vp);
2836 error = VOP_OPEN(vp, FREAD | FWRITE, td->td_ucred, td, NULL);
2837 (void) VOP_UNLOCK(vp, 0);
2841 swaponsomething(vp, vp, nblks, swapdev_strategy, swapdev_close,
2847 sysctl_swap_async_max(SYSCTL_HANDLER_ARGS)
2851 new = nsw_wcount_async_max;
2852 error = sysctl_handle_int(oidp, &new, 0, req);
2853 if (error != 0 || req->newptr == NULL)
2856 if (new > nswbuf / 2 || new < 1)
2859 mtx_lock(&pbuf_mtx);
2860 while (nsw_wcount_async_max != new) {
2862 * Adjust difference. If the current async count is too low,
2863 * we will need to sqeeze our update slowly in. Sleep with a
2864 * higher priority than getpbuf() to finish faster.
2866 n = new - nsw_wcount_async_max;
2867 if (nsw_wcount_async + n >= 0) {
2868 nsw_wcount_async += n;
2869 nsw_wcount_async_max += n;
2870 wakeup(&nsw_wcount_async);
2872 nsw_wcount_async_max -= nsw_wcount_async;
2873 nsw_wcount_async = 0;
2874 msleep(&nsw_wcount_async, &pbuf_mtx, PSWP,
2878 mtx_unlock(&pbuf_mtx);