2 * Copyright (c) 1998 Matthew Dillon,
3 * Copyright (c) 1994 John S. Dyson
4 * Copyright (c) 1990 University of Utah.
5 * Copyright (c) 1982, 1986, 1989, 1993
6 * The Regents of the University of California. All rights reserved.
8 * This code is derived from software contributed to Berkeley by
9 * the Systems Programming Group of the University of Utah Computer
12 * Redistribution and use in source and binary forms, with or without
13 * modification, are permitted provided that the following conditions
15 * 1. Redistributions of source code must retain the above copyright
16 * notice, this list of conditions and the following disclaimer.
17 * 2. Redistributions in binary form must reproduce the above copyright
18 * notice, this list of conditions and the following disclaimer in the
19 * documentation and/or other materials provided with the distribution.
20 * 3. All advertising materials mentioning features or use of this software
21 * must display the following acknowledgement:
22 * This product includes software developed by the University of
23 * California, Berkeley and its contributors.
24 * 4. Neither the name of the University nor the names of its contributors
25 * may be used to endorse or promote products derived from this software
26 * without specific prior written permission.
28 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
29 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
30 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
31 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
32 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
33 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
34 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
35 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
36 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
37 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
43 * Radix Bitmap 'blists'.
45 * - The new swapper uses the new radix bitmap code. This should scale
46 * to arbitrarily small or arbitrarily large swap spaces and an almost
47 * arbitrary degree of fragmentation.
51 * - on the fly reallocation of swap during putpages. The new system
52 * does not try to keep previously allocated swap blocks for dirty
55 * - on the fly deallocation of swap
57 * - No more garbage collection required. Unnecessarily allocated swap
58 * blocks only exist for dirty vm_page_t's now and these are already
59 * cycled (in a high-load system) by the pager. We also do on-the-fly
60 * removal of invalidated swap blocks when a page is destroyed
63 * from: Utah $Hdr: swap_pager.c 1.4 91/04/30$
65 * @(#)swap_pager.c 8.9 (Berkeley) 3/21/94
66 * @(#)vm_swap.c 8.5 (Berkeley) 2/17/94
69 #include <sys/cdefs.h>
70 __FBSDID("$FreeBSD$");
75 #include <sys/param.h>
76 #include <sys/systm.h>
78 #include <sys/kernel.h>
84 #include <sys/fcntl.h>
85 #include <sys/mount.h>
86 #include <sys/namei.h>
87 #include <sys/vnode.h>
88 #include <sys/malloc.h>
89 #include <sys/racct.h>
90 #include <sys/resource.h>
91 #include <sys/resourcevar.h>
92 #include <sys/rwlock.h>
93 #include <sys/sysctl.h>
94 #include <sys/sysproto.h>
95 #include <sys/blist.h>
98 #include <sys/vmmeter.h>
100 #include <security/mac/mac_framework.h>
104 #include <vm/vm_map.h>
105 #include <vm/vm_kern.h>
106 #include <vm/vm_object.h>
107 #include <vm/vm_page.h>
108 #include <vm/vm_pager.h>
109 #include <vm/vm_pageout.h>
110 #include <vm/vm_param.h>
111 #include <vm/swap_pager.h>
112 #include <vm/vm_extern.h>
115 #include <geom/geom.h>
118 * SWB_NPAGES must be a power of 2. It may be set to 1, 2, 4, 8, 16
119 * or 32 pages per allocation.
120 * The 32-page limit is due to the radix code (kern/subr_blist.c).
122 #ifndef MAX_PAGEOUT_CLUSTER
123 #define MAX_PAGEOUT_CLUSTER 16
126 #if !defined(SWB_NPAGES)
127 #define SWB_NPAGES MAX_PAGEOUT_CLUSTER
131 * The swblock structure maps an object and a small, fixed-size range
132 * of page indices to disk addresses within a swap area.
133 * The collection of these mappings is implemented as a hash table.
134 * Unused disk addresses within a swap area are allocated and managed
137 #define SWCORRECT(n) (sizeof(void *) * (n) / sizeof(daddr_t))
138 #define SWAP_META_PAGES (SWB_NPAGES * 2)
139 #define SWAP_META_MASK (SWAP_META_PAGES - 1)
142 struct swblock *swb_hnext;
143 vm_object_t swb_object;
144 vm_pindex_t swb_index;
146 daddr_t swb_pages[SWAP_META_PAGES];
149 static MALLOC_DEFINE(M_VMPGDATA, "vm_pgdata", "swap pager private data");
150 static struct mtx sw_dev_mtx;
151 static TAILQ_HEAD(, swdevt) swtailq = TAILQ_HEAD_INITIALIZER(swtailq);
152 static struct swdevt *swdevhd; /* Allocate from here next */
153 static int nswapdev; /* Number of swap devices */
154 int swap_pager_avail;
155 static struct sx swdev_syscall_lock; /* serialize swap(on|off) */
157 static vm_ooffset_t swap_total;
158 SYSCTL_QUAD(_vm, OID_AUTO, swap_total, CTLFLAG_RD, &swap_total, 0,
159 "Total amount of available swap storage.");
160 static vm_ooffset_t swap_reserved;
161 SYSCTL_QUAD(_vm, OID_AUTO, swap_reserved, CTLFLAG_RD, &swap_reserved, 0,
162 "Amount of swap storage needed to back all allocated anonymous memory.");
163 static int overcommit = 0;
164 SYSCTL_INT(_vm, OID_AUTO, overcommit, CTLFLAG_RW, &overcommit, 0,
165 "Configure virtual memory overcommit behavior. See tuning(7) "
167 static unsigned long swzone;
168 SYSCTL_ULONG(_vm, OID_AUTO, swzone, CTLFLAG_RD, &swzone, 0,
169 "Actual size of swap metadata zone");
170 static unsigned long swap_maxpages;
171 SYSCTL_ULONG(_vm, OID_AUTO, swap_maxpages, CTLFLAG_RD, &swap_maxpages, 0,
172 "Maximum amount of swap supported");
174 /* bits from overcommit */
175 #define SWAP_RESERVE_FORCE_ON (1 << 0)
176 #define SWAP_RESERVE_RLIMIT_ON (1 << 1)
177 #define SWAP_RESERVE_ALLOW_NONWIRED (1 << 2)
180 swap_reserve(vm_ooffset_t incr)
183 return (swap_reserve_by_cred(incr, curthread->td_ucred));
187 swap_reserve_by_cred(vm_ooffset_t incr, struct ucred *cred)
192 static struct timeval lastfail;
195 uip = cred->cr_ruidinfo;
197 if (incr & PAGE_MASK)
198 panic("swap_reserve: & PAGE_MASK");
203 error = racct_add(curproc, RACCT_SWAP, incr);
204 PROC_UNLOCK(curproc);
211 mtx_lock(&sw_dev_mtx);
212 r = swap_reserved + incr;
213 if (overcommit & SWAP_RESERVE_ALLOW_NONWIRED) {
214 s = vm_cnt.v_page_count - vm_cnt.v_free_reserved - vm_cnt.v_wire_count;
219 if ((overcommit & SWAP_RESERVE_FORCE_ON) == 0 || r <= s ||
220 (error = priv_check(curthread, PRIV_VM_SWAP_NOQUOTA)) == 0) {
224 mtx_unlock(&sw_dev_mtx);
227 UIDINFO_VMSIZE_LOCK(uip);
228 if ((overcommit & SWAP_RESERVE_RLIMIT_ON) != 0 &&
229 uip->ui_vmsize + incr > lim_cur(curthread, RLIMIT_SWAP) &&
230 priv_check(curthread, PRIV_VM_SWAP_NORLIMIT))
233 uip->ui_vmsize += incr;
234 UIDINFO_VMSIZE_UNLOCK(uip);
236 mtx_lock(&sw_dev_mtx);
237 swap_reserved -= incr;
238 mtx_unlock(&sw_dev_mtx);
241 if (!res && ppsratecheck(&lastfail, &curfail, 1)) {
242 printf("uid %d, pid %d: swap reservation for %jd bytes failed\n",
243 uip->ui_uid, curproc->p_pid, incr);
249 racct_sub(curproc, RACCT_SWAP, incr);
250 PROC_UNLOCK(curproc);
258 swap_reserve_force(vm_ooffset_t incr)
262 mtx_lock(&sw_dev_mtx);
263 swap_reserved += incr;
264 mtx_unlock(&sw_dev_mtx);
268 racct_add_force(curproc, RACCT_SWAP, incr);
269 PROC_UNLOCK(curproc);
272 uip = curthread->td_ucred->cr_ruidinfo;
274 UIDINFO_VMSIZE_LOCK(uip);
275 uip->ui_vmsize += incr;
276 UIDINFO_VMSIZE_UNLOCK(uip);
277 PROC_UNLOCK(curproc);
281 swap_release(vm_ooffset_t decr)
286 cred = curthread->td_ucred;
287 swap_release_by_cred(decr, cred);
288 PROC_UNLOCK(curproc);
292 swap_release_by_cred(vm_ooffset_t decr, struct ucred *cred)
296 uip = cred->cr_ruidinfo;
298 if (decr & PAGE_MASK)
299 panic("swap_release: & PAGE_MASK");
301 mtx_lock(&sw_dev_mtx);
302 if (swap_reserved < decr)
303 panic("swap_reserved < decr");
304 swap_reserved -= decr;
305 mtx_unlock(&sw_dev_mtx);
307 UIDINFO_VMSIZE_LOCK(uip);
308 if (uip->ui_vmsize < decr)
309 printf("negative vmsize for uid = %d\n", uip->ui_uid);
310 uip->ui_vmsize -= decr;
311 UIDINFO_VMSIZE_UNLOCK(uip);
313 racct_sub_cred(cred, RACCT_SWAP, decr);
316 #define SWM_FREE 0x02 /* free, period */
317 #define SWM_POP 0x04 /* pop out */
319 int swap_pager_full = 2; /* swap space exhaustion (task killing) */
320 static int swap_pager_almost_full = 1; /* swap space exhaustion (w/hysteresis)*/
321 static int nsw_rcount; /* free read buffers */
322 static int nsw_wcount_sync; /* limit write buffers / synchronous */
323 static int nsw_wcount_async; /* limit write buffers / asynchronous */
324 static int nsw_wcount_async_max;/* assigned maximum */
325 static int nsw_cluster_max; /* maximum VOP I/O allowed */
327 static int sysctl_swap_async_max(SYSCTL_HANDLER_ARGS);
328 SYSCTL_PROC(_vm, OID_AUTO, swap_async_max, CTLTYPE_INT | CTLFLAG_RW |
329 CTLFLAG_MPSAFE, NULL, 0, sysctl_swap_async_max, "I",
330 "Maximum running async swap ops");
332 static struct swblock **swhash;
333 static int swhash_mask;
334 static struct mtx swhash_mtx;
336 static struct sx sw_alloc_sx;
339 * "named" and "unnamed" anon region objects. Try to reduce the overhead
340 * of searching a named list by hashing it just a little.
345 #define NOBJLIST(handle) \
346 (&swap_pager_object_list[((int)(intptr_t)handle >> 4) & (NOBJLISTS-1)])
348 static struct mtx sw_alloc_mtx; /* protect list manipulation */
349 static struct pagerlst swap_pager_object_list[NOBJLISTS];
350 static uma_zone_t swap_zone;
353 * pagerops for OBJT_SWAP - "swap pager". Some ops are also global procedure
354 * calls hooked from other parts of the VM system and do not appear here.
355 * (see vm/swap_pager.h).
358 swap_pager_alloc(void *handle, vm_ooffset_t size,
359 vm_prot_t prot, vm_ooffset_t offset, struct ucred *);
360 static void swap_pager_dealloc(vm_object_t object);
361 static int swap_pager_getpages(vm_object_t, vm_page_t *, int, int *,
363 static int swap_pager_getpages_async(vm_object_t, vm_page_t *, int, int *,
364 int *, pgo_getpages_iodone_t, void *);
365 static void swap_pager_putpages(vm_object_t, vm_page_t *, int, boolean_t, int *);
367 swap_pager_haspage(vm_object_t object, vm_pindex_t pindex, int *before, int *after);
368 static void swap_pager_init(void);
369 static void swap_pager_unswapped(vm_page_t);
370 static void swap_pager_swapoff(struct swdevt *sp);
372 struct pagerops swappagerops = {
373 .pgo_init = swap_pager_init, /* early system initialization of pager */
374 .pgo_alloc = swap_pager_alloc, /* allocate an OBJT_SWAP object */
375 .pgo_dealloc = swap_pager_dealloc, /* deallocate an OBJT_SWAP object */
376 .pgo_getpages = swap_pager_getpages, /* pagein */
377 .pgo_getpages_async = swap_pager_getpages_async, /* pagein (async) */
378 .pgo_putpages = swap_pager_putpages, /* pageout */
379 .pgo_haspage = swap_pager_haspage, /* get backing store status for page */
380 .pgo_pageunswapped = swap_pager_unswapped, /* remove swap related to page */
384 * dmmax is in page-sized chunks with the new swap system. It was
385 * dev-bsized chunks in the old. dmmax is always a power of 2.
387 * swap_*() routines are externally accessible. swp_*() routines are
391 static int nswap_lowat = 128; /* in pages, swap_pager_almost_full warn */
392 static int nswap_hiwat = 512; /* in pages, swap_pager_almost_full warn */
394 SYSCTL_INT(_vm, OID_AUTO, dmmax,
395 CTLFLAG_RD, &dmmax, 0, "Maximum size of a swap block");
397 static void swp_sizecheck(void);
398 static void swp_pager_async_iodone(struct buf *bp);
399 static int swapongeom(struct thread *, struct vnode *);
400 static int swaponvp(struct thread *, struct vnode *, u_long);
401 static int swapoff_one(struct swdevt *sp, struct ucred *cred);
404 * Swap bitmap functions
406 static void swp_pager_freeswapspace(daddr_t blk, int npages);
407 static daddr_t swp_pager_getswapspace(int npages);
412 static struct swblock **swp_pager_hash(vm_object_t object, vm_pindex_t index);
413 static void swp_pager_meta_build(vm_object_t, vm_pindex_t, daddr_t);
414 static void swp_pager_meta_free(vm_object_t, vm_pindex_t, daddr_t);
415 static void swp_pager_meta_free_all(vm_object_t);
416 static daddr_t swp_pager_meta_ctl(vm_object_t, vm_pindex_t, int);
419 * SWP_SIZECHECK() - update swap_pager_full indication
421 * update the swap_pager_almost_full indication and warn when we are
422 * about to run out of swap space, using lowat/hiwat hysteresis.
424 * Clear swap_pager_full ( task killing ) indication when lowat is met.
426 * No restrictions on call
427 * This routine may not block.
433 if (swap_pager_avail < nswap_lowat) {
434 if (swap_pager_almost_full == 0) {
435 printf("swap_pager: out of swap space\n");
436 swap_pager_almost_full = 1;
440 if (swap_pager_avail > nswap_hiwat)
441 swap_pager_almost_full = 0;
446 * SWP_PAGER_HASH() - hash swap meta data
448 * This is an helper function which hashes the swapblk given
449 * the object and page index. It returns a pointer to a pointer
450 * to the object, or a pointer to a NULL pointer if it could not
453 static struct swblock **
454 swp_pager_hash(vm_object_t object, vm_pindex_t index)
456 struct swblock **pswap;
457 struct swblock *swap;
459 index &= ~(vm_pindex_t)SWAP_META_MASK;
460 pswap = &swhash[(index ^ (int)(intptr_t)object) & swhash_mask];
461 while ((swap = *pswap) != NULL) {
462 if (swap->swb_object == object &&
463 swap->swb_index == index
467 pswap = &swap->swb_hnext;
473 * SWAP_PAGER_INIT() - initialize the swap pager!
475 * Expected to be started from system init. NOTE: This code is run
476 * before much else so be careful what you depend on. Most of the VM
477 * system has yet to be initialized at this point.
480 swap_pager_init(void)
483 * Initialize object lists
487 for (i = 0; i < NOBJLISTS; ++i)
488 TAILQ_INIT(&swap_pager_object_list[i]);
489 mtx_init(&sw_alloc_mtx, "swap_pager list", NULL, MTX_DEF);
490 mtx_init(&sw_dev_mtx, "swapdev", NULL, MTX_DEF);
491 sx_init(&swdev_syscall_lock, "swsysc");
494 * Device Stripe, in PAGE_SIZE'd blocks
496 dmmax = SWB_NPAGES * 2;
500 * SWAP_PAGER_SWAP_INIT() - swap pager initialization from pageout process
502 * Expected to be started from pageout process once, prior to entering
506 swap_pager_swap_init(void)
511 * Number of in-transit swap bp operations. Don't
512 * exhaust the pbufs completely. Make sure we
513 * initialize workable values (0 will work for hysteresis
514 * but it isn't very efficient).
516 * The nsw_cluster_max is constrained by the bp->b_pages[]
517 * array (MAXPHYS/PAGE_SIZE) and our locally defined
518 * MAX_PAGEOUT_CLUSTER. Also be aware that swap ops are
519 * constrained by the swap device interleave stripe size.
521 * Currently we hardwire nsw_wcount_async to 4. This limit is
522 * designed to prevent other I/O from having high latencies due to
523 * our pageout I/O. The value 4 works well for one or two active swap
524 * devices but is probably a little low if you have more. Even so,
525 * a higher value would probably generate only a limited improvement
526 * with three or four active swap devices since the system does not
527 * typically have to pageout at extreme bandwidths. We will want
528 * at least 2 per swap devices, and 4 is a pretty good value if you
529 * have one NFS swap device due to the command/ack latency over NFS.
530 * So it all works out pretty well.
532 nsw_cluster_max = min((MAXPHYS/PAGE_SIZE), MAX_PAGEOUT_CLUSTER);
535 nsw_rcount = (nswbuf + 1) / 2;
536 nsw_wcount_sync = (nswbuf + 3) / 4;
537 nsw_wcount_async = 4;
538 nsw_wcount_async_max = nsw_wcount_async;
539 mtx_unlock(&pbuf_mtx);
542 * Initialize our zone. Right now I'm just guessing on the number
543 * we need based on the number of pages in the system. Each swblock
544 * can hold 32 pages, so this is probably overkill. This reservation
545 * is typically limited to around 32MB by default.
547 n = vm_cnt.v_page_count / 2;
548 if (maxswzone && n > maxswzone / sizeof(struct swblock))
549 n = maxswzone / sizeof(struct swblock);
551 swap_zone = uma_zcreate("SWAPMETA", sizeof(struct swblock), NULL, NULL,
552 NULL, NULL, UMA_ALIGN_PTR, UMA_ZONE_NOFREE | UMA_ZONE_VM);
553 if (swap_zone == NULL)
554 panic("failed to create swap_zone.");
556 if (uma_zone_reserve_kva(swap_zone, n))
559 * if the allocation failed, try a zone two thirds the
560 * size of the previous attempt.
565 printf("Swap zone entries reduced from %lu to %lu.\n", n2, n);
566 swap_maxpages = n * SWAP_META_PAGES;
567 swzone = n * sizeof(struct swblock);
571 * Initialize our meta-data hash table. The swapper does not need to
572 * be quite as efficient as the VM system, so we do not use an
573 * oversized hash table.
575 * n: size of hash table, must be power of 2
576 * swhash_mask: hash table index mask
578 for (n = 1; n < n2 / 8; n *= 2)
580 swhash = malloc(sizeof(struct swblock *) * n, M_VMPGDATA, M_WAITOK | M_ZERO);
582 mtx_init(&swhash_mtx, "swap_pager swhash", NULL, MTX_DEF);
586 * SWAP_PAGER_ALLOC() - allocate a new OBJT_SWAP VM object and instantiate
587 * its metadata structures.
589 * This routine is called from the mmap and fork code to create a new
590 * OBJT_SWAP object. We do this by creating an OBJT_DEFAULT object
591 * and then converting it with swp_pager_meta_build().
593 * This routine may block in vm_object_allocate() and create a named
594 * object lookup race, so we must interlock.
599 swap_pager_alloc(void *handle, vm_ooffset_t size, vm_prot_t prot,
600 vm_ooffset_t offset, struct ucred *cred)
605 pindex = OFF_TO_IDX(offset + PAGE_MASK + size);
608 * Reference existing named region or allocate new one. There
609 * should not be a race here against swp_pager_meta_build()
610 * as called from vm_page_remove() in regards to the lookup
613 sx_xlock(&sw_alloc_sx);
614 object = vm_pager_object_lookup(NOBJLIST(handle), handle);
615 if (object == NULL) {
617 if (!swap_reserve_by_cred(size, cred)) {
618 sx_xunlock(&sw_alloc_sx);
623 object = vm_object_allocate(OBJT_DEFAULT, pindex);
624 VM_OBJECT_WLOCK(object);
625 object->handle = handle;
628 object->charge = size;
630 swp_pager_meta_build(object, 0, SWAPBLK_NONE);
631 VM_OBJECT_WUNLOCK(object);
633 sx_xunlock(&sw_alloc_sx);
636 if (!swap_reserve_by_cred(size, cred))
640 object = vm_object_allocate(OBJT_DEFAULT, pindex);
641 VM_OBJECT_WLOCK(object);
644 object->charge = size;
646 swp_pager_meta_build(object, 0, SWAPBLK_NONE);
647 VM_OBJECT_WUNLOCK(object);
653 * SWAP_PAGER_DEALLOC() - remove swap metadata from object
655 * The swap backing for the object is destroyed. The code is
656 * designed such that we can reinstantiate it later, but this
657 * routine is typically called only when the entire object is
658 * about to be destroyed.
660 * The object must be locked.
663 swap_pager_dealloc(vm_object_t object)
667 * Remove from list right away so lookups will fail if we block for
668 * pageout completion.
670 if (object->handle != NULL) {
671 mtx_lock(&sw_alloc_mtx);
672 TAILQ_REMOVE(NOBJLIST(object->handle), object, pager_object_list);
673 mtx_unlock(&sw_alloc_mtx);
676 VM_OBJECT_ASSERT_WLOCKED(object);
677 vm_object_pip_wait(object, "swpdea");
680 * Free all remaining metadata. We only bother to free it from
681 * the swap meta data. We do not attempt to free swapblk's still
682 * associated with vm_page_t's for this object. We do not care
683 * if paging is still in progress on some objects.
685 swp_pager_meta_free_all(object);
686 object->handle = NULL;
687 object->type = OBJT_DEAD;
690 /************************************************************************
691 * SWAP PAGER BITMAP ROUTINES *
692 ************************************************************************/
695 * SWP_PAGER_GETSWAPSPACE() - allocate raw swap space
697 * Allocate swap for the requested number of pages. The starting
698 * swap block number (a page index) is returned or SWAPBLK_NONE
699 * if the allocation failed.
701 * Also has the side effect of advising that somebody made a mistake
702 * when they configured swap and didn't configure enough.
704 * This routine may not sleep.
706 * We allocate in round-robin fashion from the configured devices.
709 swp_pager_getswapspace(int npages)
716 mtx_lock(&sw_dev_mtx);
718 for (i = 0; i < nswapdev; i++) {
720 sp = TAILQ_FIRST(&swtailq);
721 if (!(sp->sw_flags & SW_CLOSING)) {
722 blk = blist_alloc(sp->sw_blist, npages);
723 if (blk != SWAPBLK_NONE) {
725 sp->sw_used += npages;
726 swap_pager_avail -= npages;
728 swdevhd = TAILQ_NEXT(sp, sw_list);
732 sp = TAILQ_NEXT(sp, sw_list);
734 if (swap_pager_full != 2) {
735 printf("swap_pager_getswapspace(%d): failed\n", npages);
737 swap_pager_almost_full = 1;
741 mtx_unlock(&sw_dev_mtx);
746 swp_pager_isondev(daddr_t blk, struct swdevt *sp)
749 return (blk >= sp->sw_first && blk < sp->sw_end);
753 swp_pager_strategy(struct buf *bp)
757 mtx_lock(&sw_dev_mtx);
758 TAILQ_FOREACH(sp, &swtailq, sw_list) {
759 if (bp->b_blkno >= sp->sw_first && bp->b_blkno < sp->sw_end) {
760 mtx_unlock(&sw_dev_mtx);
761 if ((sp->sw_flags & SW_UNMAPPED) != 0 &&
762 unmapped_buf_allowed) {
763 bp->b_data = unmapped_buf;
766 pmap_qenter((vm_offset_t)bp->b_data,
767 &bp->b_pages[0], bp->b_bcount / PAGE_SIZE);
769 sp->sw_strategy(bp, sp);
773 panic("Swapdev not found");
778 * SWP_PAGER_FREESWAPSPACE() - free raw swap space
780 * This routine returns the specified swap blocks back to the bitmap.
782 * This routine may not sleep.
785 swp_pager_freeswapspace(daddr_t blk, int npages)
789 mtx_lock(&sw_dev_mtx);
790 TAILQ_FOREACH(sp, &swtailq, sw_list) {
791 if (blk >= sp->sw_first && blk < sp->sw_end) {
792 sp->sw_used -= npages;
794 * If we are attempting to stop swapping on
795 * this device, we don't want to mark any
796 * blocks free lest they be reused.
798 if ((sp->sw_flags & SW_CLOSING) == 0) {
799 blist_free(sp->sw_blist, blk - sp->sw_first,
801 swap_pager_avail += npages;
804 mtx_unlock(&sw_dev_mtx);
808 panic("Swapdev not found");
812 * SWAP_PAGER_FREESPACE() - frees swap blocks associated with a page
813 * range within an object.
815 * This is a globally accessible routine.
817 * This routine removes swapblk assignments from swap metadata.
819 * The external callers of this routine typically have already destroyed
820 * or renamed vm_page_t's associated with this range in the object so
823 * The object must be locked.
826 swap_pager_freespace(vm_object_t object, vm_pindex_t start, vm_size_t size)
829 swp_pager_meta_free(object, start, size);
833 * SWAP_PAGER_RESERVE() - reserve swap blocks in object
835 * Assigns swap blocks to the specified range within the object. The
836 * swap blocks are not zeroed. Any previous swap assignment is destroyed.
838 * Returns 0 on success, -1 on failure.
841 swap_pager_reserve(vm_object_t object, vm_pindex_t start, vm_size_t size)
844 daddr_t blk = SWAPBLK_NONE;
845 vm_pindex_t beg = start; /* save start index */
847 VM_OBJECT_WLOCK(object);
851 while ((blk = swp_pager_getswapspace(n)) == SWAPBLK_NONE) {
854 swp_pager_meta_free(object, beg, start - beg);
855 VM_OBJECT_WUNLOCK(object);
860 swp_pager_meta_build(object, start, blk);
866 swp_pager_meta_free(object, start, n);
867 VM_OBJECT_WUNLOCK(object);
872 * SWAP_PAGER_COPY() - copy blocks from source pager to destination pager
873 * and destroy the source.
875 * Copy any valid swapblks from the source to the destination. In
876 * cases where both the source and destination have a valid swapblk,
877 * we keep the destination's.
879 * This routine is allowed to sleep. It may sleep allocating metadata
880 * indirectly through swp_pager_meta_build() or if paging is still in
881 * progress on the source.
883 * The source object contains no vm_page_t's (which is just as well)
885 * The source object is of type OBJT_SWAP.
887 * The source and destination objects must be locked.
888 * Both object locks may temporarily be released.
891 swap_pager_copy(vm_object_t srcobject, vm_object_t dstobject,
892 vm_pindex_t offset, int destroysource)
896 VM_OBJECT_ASSERT_WLOCKED(srcobject);
897 VM_OBJECT_ASSERT_WLOCKED(dstobject);
900 * If destroysource is set, we remove the source object from the
901 * swap_pager internal queue now.
904 if (srcobject->handle != NULL) {
905 mtx_lock(&sw_alloc_mtx);
907 NOBJLIST(srcobject->handle),
911 mtx_unlock(&sw_alloc_mtx);
916 * transfer source to destination.
918 for (i = 0; i < dstobject->size; ++i) {
922 * Locate (without changing) the swapblk on the destination,
923 * unless it is invalid in which case free it silently, or
924 * if the destination is a resident page, in which case the
925 * source is thrown away.
927 dstaddr = swp_pager_meta_ctl(dstobject, i, 0);
929 if (dstaddr == SWAPBLK_NONE) {
931 * Destination has no swapblk and is not resident,
936 srcaddr = swp_pager_meta_ctl(
942 if (srcaddr != SWAPBLK_NONE) {
944 * swp_pager_meta_build() can sleep.
946 vm_object_pip_add(srcobject, 1);
947 VM_OBJECT_WUNLOCK(srcobject);
948 vm_object_pip_add(dstobject, 1);
949 swp_pager_meta_build(dstobject, i, srcaddr);
950 vm_object_pip_wakeup(dstobject);
951 VM_OBJECT_WLOCK(srcobject);
952 vm_object_pip_wakeup(srcobject);
956 * Destination has valid swapblk or it is represented
957 * by a resident page. We destroy the sourceblock.
960 swp_pager_meta_ctl(srcobject, i + offset, SWM_FREE);
965 * Free left over swap blocks in source.
967 * We have to revert the type to OBJT_DEFAULT so we do not accidentally
968 * double-remove the object from the swap queues.
971 swp_pager_meta_free_all(srcobject);
973 * Reverting the type is not necessary, the caller is going
974 * to destroy srcobject directly, but I'm doing it here
975 * for consistency since we've removed the object from its
978 srcobject->type = OBJT_DEFAULT;
983 * SWAP_PAGER_HASPAGE() - determine if we have good backing store for
984 * the requested page.
986 * We determine whether good backing store exists for the requested
987 * page and return TRUE if it does, FALSE if it doesn't.
989 * If TRUE, we also try to determine how much valid, contiguous backing
990 * store exists before and after the requested page within a reasonable
991 * distance. We do not try to restrict it to the swap device stripe
992 * (that is handled in getpages/putpages). It probably isn't worth
996 swap_pager_haspage(vm_object_t object, vm_pindex_t pindex, int *before, int *after)
1000 VM_OBJECT_ASSERT_LOCKED(object);
1002 * do we have good backing store at the requested index ?
1004 blk0 = swp_pager_meta_ctl(object, pindex, 0);
1006 if (blk0 == SWAPBLK_NONE) {
1015 * find backwards-looking contiguous good backing store
1017 if (before != NULL) {
1020 for (i = 1; i < (SWB_NPAGES/2); ++i) {
1025 blk = swp_pager_meta_ctl(object, pindex - i, 0);
1026 if (blk != blk0 - i)
1033 * find forward-looking contiguous good backing store
1035 if (after != NULL) {
1038 for (i = 1; i < (SWB_NPAGES/2); ++i) {
1041 blk = swp_pager_meta_ctl(object, pindex + i, 0);
1042 if (blk != blk0 + i)
1051 * SWAP_PAGER_PAGE_UNSWAPPED() - remove swap backing store related to page
1053 * This removes any associated swap backing store, whether valid or
1054 * not, from the page.
1056 * This routine is typically called when a page is made dirty, at
1057 * which point any associated swap can be freed. MADV_FREE also
1058 * calls us in a special-case situation
1060 * NOTE!!! If the page is clean and the swap was valid, the caller
1061 * should make the page dirty before calling this routine. This routine
1062 * does NOT change the m->dirty status of the page. Also: MADV_FREE
1065 * This routine may not sleep.
1067 * The object containing the page must be locked.
1070 swap_pager_unswapped(vm_page_t m)
1073 swp_pager_meta_ctl(m->object, m->pindex, SWM_FREE);
1077 * SWAP_PAGER_GETPAGES() - bring pages in from swap
1079 * Attempt to retrieve (m, count) pages from backing store, but make
1080 * sure we retrieve at least m[reqpage]. We try to load in as large
1081 * a chunk surrounding m[reqpage] as is contiguous in swap and which
1082 * belongs to the same object.
1084 * The code is designed for asynchronous operation and
1085 * immediate-notification of 'reqpage' but tends not to be
1086 * used that way. Please do not optimize-out this algorithmic
1087 * feature, I intend to improve on it in the future.
1089 * The parent has a single vm_object_pip_add() reference prior to
1090 * calling us and we should return with the same.
1092 * The parent has BUSY'd the pages. We should return with 'm'
1093 * left busy, but the others adjusted.
1096 swap_pager_getpages(vm_object_t object, vm_page_t *m, int count, int *rbehind,
1103 * Calculate range to retrieve. The pages have already been assigned
1104 * their swapblks. We require a *contiguous* range but we know it to
1105 * not span devices. If we do not supply it, bad things
1106 * happen. Note that blk, iblk & jblk can be SWAPBLK_NONE, but the
1107 * loops are set up such that the case(s) are handled implicitly.
1109 * The swp_*() calls must be made with the object locked.
1111 blk = swp_pager_meta_ctl(m[0]->object, m[0]->pindex, 0);
1113 if (blk == SWAPBLK_NONE)
1114 return (VM_PAGER_FAIL);
1117 for (int i = 0; i < count; i++)
1119 swp_pager_meta_ctl(m[i]->object, m[i]->pindex, 0),
1120 ("%s: range is not contiguous", __func__));
1124 * Getpbuf() can sleep.
1126 VM_OBJECT_WUNLOCK(object);
1128 * Get a swap buffer header to perform the IO
1130 bp = getpbuf(&nsw_rcount);
1131 bp->b_flags |= B_PAGING;
1133 bp->b_iocmd = BIO_READ;
1134 bp->b_iodone = swp_pager_async_iodone;
1135 bp->b_rcred = crhold(thread0.td_ucred);
1136 bp->b_wcred = crhold(thread0.td_ucred);
1138 bp->b_bcount = PAGE_SIZE * count;
1139 bp->b_bufsize = PAGE_SIZE * count;
1140 bp->b_npages = count;
1142 VM_OBJECT_WLOCK(object);
1143 for (int i = 0; i < count; i++) {
1144 bp->b_pages[i] = m[i];
1145 m[i]->oflags |= VPO_SWAPINPROG;
1148 PCPU_INC(cnt.v_swapin);
1149 PCPU_ADD(cnt.v_swappgsin, bp->b_npages);
1152 * We still hold the lock on mreq, and our automatic completion routine
1153 * does not remove it.
1155 vm_object_pip_add(object, bp->b_npages);
1156 VM_OBJECT_WUNLOCK(object);
1159 * perform the I/O. NOTE!!! bp cannot be considered valid after
1160 * this point because we automatically release it on completion.
1161 * Instead, we look at the one page we are interested in which we
1162 * still hold a lock on even through the I/O completion.
1164 * The other pages in our m[] array are also released on completion,
1165 * so we cannot assume they are valid anymore either.
1167 * NOTE: b_blkno is destroyed by the call to swapdev_strategy
1170 swp_pager_strategy(bp);
1173 * wait for the page we want to complete. VPO_SWAPINPROG is always
1174 * cleared on completion. If an I/O error occurs, SWAPBLK_NONE
1175 * is set in the meta-data.
1177 VM_OBJECT_WLOCK(object);
1178 while ((m[0]->oflags & VPO_SWAPINPROG) != 0) {
1179 m[0]->oflags |= VPO_SWAPSLEEP;
1180 PCPU_INC(cnt.v_intrans);
1181 if (VM_OBJECT_SLEEP(object, &object->paging_in_progress, PSWP,
1182 "swread", hz * 20)) {
1184 "swap_pager: indefinite wait buffer: bufobj: %p, blkno: %jd, size: %ld\n",
1185 bp->b_bufobj, (intmax_t)bp->b_blkno, bp->b_bcount);
1190 * If we had an unrecoverable read error pages will not be valid.
1192 for (int i = 0; i < count; i++)
1193 if (m[i]->valid != VM_PAGE_BITS_ALL)
1194 return (VM_PAGER_ERROR);
1201 return (VM_PAGER_OK);
1204 * A final note: in a low swap situation, we cannot deallocate swap
1205 * and mark a page dirty here because the caller is likely to mark
1206 * the page clean when we return, causing the page to possibly revert
1207 * to all-zero's later.
1212 * swap_pager_getpages_async():
1214 * Right now this is emulation of asynchronous operation on top of
1215 * swap_pager_getpages().
1218 swap_pager_getpages_async(vm_object_t object, vm_page_t *m, int count,
1219 int *rbehind, int *rahead, pgo_getpages_iodone_t iodone, void *arg)
1223 r = swap_pager_getpages(object, m, count, rbehind, rahead);
1224 VM_OBJECT_WUNLOCK(object);
1229 case VM_PAGER_ERROR:
1236 panic("unhandled swap_pager_getpages() error %d", r);
1238 (iodone)(arg, m, count, error);
1239 VM_OBJECT_WLOCK(object);
1245 * swap_pager_putpages:
1247 * Assign swap (if necessary) and initiate I/O on the specified pages.
1249 * We support both OBJT_DEFAULT and OBJT_SWAP objects. DEFAULT objects
1250 * are automatically converted to SWAP objects.
1252 * In a low memory situation we may block in VOP_STRATEGY(), but the new
1253 * vm_page reservation system coupled with properly written VFS devices
1254 * should ensure that no low-memory deadlock occurs. This is an area
1257 * The parent has N vm_object_pip_add() references prior to
1258 * calling us and will remove references for rtvals[] that are
1259 * not set to VM_PAGER_PEND. We need to remove the rest on I/O
1262 * The parent has soft-busy'd the pages it passes us and will unbusy
1263 * those whos rtvals[] entry is not set to VM_PAGER_PEND on return.
1264 * We need to unbusy the rest on I/O completion.
1267 swap_pager_putpages(vm_object_t object, vm_page_t *m, int count,
1268 int flags, int *rtvals)
1273 if (count && m[0]->object != object) {
1274 panic("swap_pager_putpages: object mismatch %p/%p",
1283 * Turn object into OBJT_SWAP
1284 * check for bogus sysops
1285 * force sync if not pageout process
1287 if (object->type != OBJT_SWAP)
1288 swp_pager_meta_build(object, 0, SWAPBLK_NONE);
1289 VM_OBJECT_WUNLOCK(object);
1292 if (curproc != pageproc)
1295 sync = (flags & VM_PAGER_PUT_SYNC) != 0;
1300 * Assign swap blocks and issue I/O. We reallocate swap on the fly.
1301 * The page is left dirty until the pageout operation completes
1304 for (i = 0; i < count; i += n) {
1310 * Maximum I/O size is limited by a number of factors.
1312 n = min(BLIST_MAX_ALLOC, count - i);
1313 n = min(n, nsw_cluster_max);
1316 * Get biggest block of swap we can. If we fail, fall
1317 * back and try to allocate a smaller block. Don't go
1318 * overboard trying to allocate space if it would overly
1322 (blk = swp_pager_getswapspace(n)) == SWAPBLK_NONE &&
1327 if (blk == SWAPBLK_NONE) {
1328 for (j = 0; j < n; ++j)
1329 rtvals[i+j] = VM_PAGER_FAIL;
1334 * All I/O parameters have been satisfied, build the I/O
1335 * request and assign the swap space.
1338 bp = getpbuf(&nsw_wcount_sync);
1340 bp = getpbuf(&nsw_wcount_async);
1341 bp->b_flags = B_ASYNC;
1343 bp->b_flags |= B_PAGING;
1344 bp->b_iocmd = BIO_WRITE;
1346 bp->b_rcred = crhold(thread0.td_ucred);
1347 bp->b_wcred = crhold(thread0.td_ucred);
1348 bp->b_bcount = PAGE_SIZE * n;
1349 bp->b_bufsize = PAGE_SIZE * n;
1352 VM_OBJECT_WLOCK(object);
1353 for (j = 0; j < n; ++j) {
1354 vm_page_t mreq = m[i+j];
1356 swp_pager_meta_build(
1361 vm_page_dirty(mreq);
1362 mreq->oflags |= VPO_SWAPINPROG;
1363 bp->b_pages[j] = mreq;
1365 VM_OBJECT_WUNLOCK(object);
1368 * Must set dirty range for NFS to work.
1371 bp->b_dirtyend = bp->b_bcount;
1373 PCPU_INC(cnt.v_swapout);
1374 PCPU_ADD(cnt.v_swappgsout, bp->b_npages);
1377 * We unconditionally set rtvals[] to VM_PAGER_PEND so that we
1378 * can call the async completion routine at the end of a
1379 * synchronous I/O operation. Otherwise, our caller would
1380 * perform duplicate unbusy and wakeup operations on the page
1381 * and object, respectively.
1383 for (j = 0; j < n; j++)
1384 rtvals[i + j] = VM_PAGER_PEND;
1389 * NOTE: b_blkno is destroyed by the call to swapdev_strategy
1391 if (sync == FALSE) {
1392 bp->b_iodone = swp_pager_async_iodone;
1394 swp_pager_strategy(bp);
1401 * NOTE: b_blkno is destroyed by the call to swapdev_strategy
1403 bp->b_iodone = bdone;
1404 swp_pager_strategy(bp);
1407 * Wait for the sync I/O to complete.
1409 bwait(bp, PVM, "swwrt");
1412 * Now that we are through with the bp, we can call the
1413 * normal async completion, which frees everything up.
1415 swp_pager_async_iodone(bp);
1417 VM_OBJECT_WLOCK(object);
1421 * swp_pager_async_iodone:
1423 * Completion routine for asynchronous reads and writes from/to swap.
1424 * Also called manually by synchronous code to finish up a bp.
1426 * This routine may not sleep.
1429 swp_pager_async_iodone(struct buf *bp)
1432 vm_object_t object = NULL;
1437 if (bp->b_ioflags & BIO_ERROR) {
1439 "swap_pager: I/O error - %s failed; blkno %ld,"
1440 "size %ld, error %d\n",
1441 ((bp->b_iocmd == BIO_READ) ? "pagein" : "pageout"),
1449 * remove the mapping for kernel virtual
1452 pmap_qremove((vm_offset_t)bp->b_data, bp->b_npages);
1454 bp->b_data = bp->b_kvabase;
1457 object = bp->b_pages[0]->object;
1458 VM_OBJECT_WLOCK(object);
1462 * cleanup pages. If an error occurs writing to swap, we are in
1463 * very serious trouble. If it happens to be a disk error, though,
1464 * we may be able to recover by reassigning the swap later on. So
1465 * in this case we remove the m->swapblk assignment for the page
1466 * but do not free it in the rlist. The errornous block(s) are thus
1467 * never reallocated as swap. Redirty the page and continue.
1469 for (i = 0; i < bp->b_npages; ++i) {
1470 vm_page_t m = bp->b_pages[i];
1472 m->oflags &= ~VPO_SWAPINPROG;
1473 if (m->oflags & VPO_SWAPSLEEP) {
1474 m->oflags &= ~VPO_SWAPSLEEP;
1475 wakeup(&object->paging_in_progress);
1478 if (bp->b_ioflags & BIO_ERROR) {
1480 * If an error occurs I'd love to throw the swapblk
1481 * away without freeing it back to swapspace, so it
1482 * can never be used again. But I can't from an
1485 if (bp->b_iocmd == BIO_READ) {
1487 * NOTE: for reads, m->dirty will probably
1488 * be overridden by the original caller of
1489 * getpages so don't play cute tricks here.
1494 * If a write error occurs, reactivate page
1495 * so it doesn't clog the inactive list,
1496 * then finish the I/O.
1500 vm_page_activate(m);
1504 } else if (bp->b_iocmd == BIO_READ) {
1506 * NOTE: for reads, m->dirty will probably be
1507 * overridden by the original caller of getpages so
1508 * we cannot set them in order to free the underlying
1509 * swap in a low-swap situation. I don't think we'd
1510 * want to do that anyway, but it was an optimization
1511 * that existed in the old swapper for a time before
1512 * it got ripped out due to precisely this problem.
1514 KASSERT(!pmap_page_is_mapped(m),
1515 ("swp_pager_async_iodone: page %p is mapped", m));
1516 KASSERT(m->dirty == 0,
1517 ("swp_pager_async_iodone: page %p is dirty", m));
1518 m->valid = VM_PAGE_BITS_ALL;
1521 * For write success, clear the dirty
1522 * status, then finish the I/O ( which decrements the
1523 * busy count and possibly wakes waiter's up ).
1525 KASSERT(!pmap_page_is_write_mapped(m),
1526 ("swp_pager_async_iodone: page %p is not write"
1530 if (vm_page_count_severe()) {
1532 vm_page_try_to_cache(m);
1539 * adjust pip. NOTE: the original parent may still have its own
1540 * pip refs on the object.
1542 if (object != NULL) {
1543 vm_object_pip_wakeupn(object, bp->b_npages);
1544 VM_OBJECT_WUNLOCK(object);
1548 * swapdev_strategy() manually sets b_vp and b_bufobj before calling
1549 * bstrategy(). Set them back to NULL now we're done with it, or we'll
1550 * trigger a KASSERT in relpbuf().
1554 bp->b_bufobj = NULL;
1557 * release the physical I/O buffer
1561 ((bp->b_iocmd == BIO_READ) ? &nsw_rcount :
1562 ((bp->b_flags & B_ASYNC) ?
1571 * swap_pager_isswapped:
1573 * Return 1 if at least one page in the given object is paged
1574 * out to the given swap device.
1576 * This routine may not sleep.
1579 swap_pager_isswapped(vm_object_t object, struct swdevt *sp)
1585 VM_OBJECT_ASSERT_WLOCKED(object);
1586 if (object->type != OBJT_SWAP)
1589 mtx_lock(&swhash_mtx);
1590 for (bcount = 0; bcount < object->un_pager.swp.swp_bcount; bcount++) {
1591 struct swblock *swap;
1593 if ((swap = *swp_pager_hash(object, index)) != NULL) {
1594 for (i = 0; i < SWAP_META_PAGES; ++i) {
1595 if (swp_pager_isondev(swap->swb_pages[i], sp)) {
1596 mtx_unlock(&swhash_mtx);
1601 index += SWAP_META_PAGES;
1603 mtx_unlock(&swhash_mtx);
1608 * SWP_PAGER_FORCE_PAGEIN() - force a swap block to be paged in
1610 * This routine dissociates the page at the given index within a
1611 * swap block from its backing store, paging it in if necessary.
1612 * If the page is paged in, it is placed in the inactive queue,
1613 * since it had its backing store ripped out from under it.
1614 * We also attempt to swap in all other pages in the swap block,
1615 * we only guarantee that the one at the specified index is
1618 * XXX - The code to page the whole block in doesn't work, so we
1619 * revert to the one-by-one behavior for now. Sigh.
1622 swp_pager_force_pagein(vm_object_t object, vm_pindex_t pindex)
1626 vm_object_pip_add(object, 1);
1627 m = vm_page_grab(object, pindex, VM_ALLOC_NORMAL);
1628 if (m->valid == VM_PAGE_BITS_ALL) {
1629 vm_object_pip_wakeup(object);
1632 vm_page_activate(m);
1635 vm_pager_page_unswapped(m);
1639 if (swap_pager_getpages(object, &m, 1, NULL, NULL) != VM_PAGER_OK)
1640 panic("swap_pager_force_pagein: read from swap failed");/*XXX*/
1641 vm_object_pip_wakeup(object);
1644 vm_page_deactivate(m);
1647 vm_pager_page_unswapped(m);
1651 * swap_pager_swapoff:
1653 * Page in all of the pages that have been paged out to the
1654 * given device. The corresponding blocks in the bitmap must be
1655 * marked as allocated and the device must be flagged SW_CLOSING.
1656 * There may be no processes swapped out to the device.
1658 * This routine may block.
1661 swap_pager_swapoff(struct swdevt *sp)
1663 struct swblock *swap;
1666 sx_assert(&swdev_syscall_lock, SA_XLOCKED);
1670 mtx_lock(&swhash_mtx);
1671 for (i = 0; i <= swhash_mask; i++) { /* '<=' is correct here */
1673 for (swap = swhash[i]; swap != NULL; swap = swap->swb_hnext) {
1674 vm_object_t object = swap->swb_object;
1675 vm_pindex_t pindex = swap->swb_index;
1676 for (j = 0; j < SWAP_META_PAGES; ++j) {
1677 if (swp_pager_isondev(swap->swb_pages[j], sp)) {
1678 /* avoid deadlock */
1679 if (!VM_OBJECT_TRYWLOCK(object)) {
1682 mtx_unlock(&swhash_mtx);
1683 swp_pager_force_pagein(object,
1685 VM_OBJECT_WUNLOCK(object);
1686 mtx_lock(&swhash_mtx);
1693 mtx_unlock(&swhash_mtx);
1696 * Objects may be locked or paging to the device being
1697 * removed, so we will miss their pages and need to
1698 * make another pass. We have marked this device as
1699 * SW_CLOSING, so the activity should finish soon.
1702 if (retries > 100) {
1703 panic("swapoff: failed to locate %d swap blocks",
1706 pause("swpoff", hz / 20);
1711 /************************************************************************
1713 ************************************************************************
1715 * These routines manipulate the swap metadata stored in the
1718 * Swap metadata is implemented with a global hash and not directly
1719 * linked into the object. Instead the object simply contains
1720 * appropriate tracking counters.
1724 * SWP_PAGER_META_BUILD() - add swap block to swap meta data for object
1726 * We first convert the object to a swap object if it is a default
1729 * The specified swapblk is added to the object's swap metadata. If
1730 * the swapblk is not valid, it is freed instead. Any previously
1731 * assigned swapblk is freed.
1734 swp_pager_meta_build(vm_object_t object, vm_pindex_t pindex, daddr_t swapblk)
1736 static volatile int exhausted;
1737 struct swblock *swap;
1738 struct swblock **pswap;
1741 VM_OBJECT_ASSERT_WLOCKED(object);
1743 * Convert default object to swap object if necessary
1745 if (object->type != OBJT_SWAP) {
1746 object->type = OBJT_SWAP;
1747 object->un_pager.swp.swp_bcount = 0;
1749 if (object->handle != NULL) {
1750 mtx_lock(&sw_alloc_mtx);
1752 NOBJLIST(object->handle),
1756 mtx_unlock(&sw_alloc_mtx);
1761 * Locate hash entry. If not found create, but if we aren't adding
1762 * anything just return. If we run out of space in the map we wait
1763 * and, since the hash table may have changed, retry.
1766 mtx_lock(&swhash_mtx);
1767 pswap = swp_pager_hash(object, pindex);
1769 if ((swap = *pswap) == NULL) {
1772 if (swapblk == SWAPBLK_NONE)
1775 swap = *pswap = uma_zalloc(swap_zone, M_NOWAIT |
1776 (curproc == pageproc ? M_USE_RESERVE : 0));
1778 mtx_unlock(&swhash_mtx);
1779 VM_OBJECT_WUNLOCK(object);
1780 if (uma_zone_exhausted(swap_zone)) {
1781 if (atomic_cmpset_int(&exhausted, 0, 1))
1782 printf("swap zone exhausted, "
1783 "increase kern.maxswzone\n");
1784 vm_pageout_oom(VM_OOM_SWAPZ);
1785 pause("swzonex", 10);
1788 VM_OBJECT_WLOCK(object);
1792 if (atomic_cmpset_int(&exhausted, 1, 0))
1793 printf("swap zone ok\n");
1795 swap->swb_hnext = NULL;
1796 swap->swb_object = object;
1797 swap->swb_index = pindex & ~(vm_pindex_t)SWAP_META_MASK;
1798 swap->swb_count = 0;
1800 ++object->un_pager.swp.swp_bcount;
1802 for (i = 0; i < SWAP_META_PAGES; ++i)
1803 swap->swb_pages[i] = SWAPBLK_NONE;
1807 * Delete prior contents of metadata
1809 idx = pindex & SWAP_META_MASK;
1811 if (swap->swb_pages[idx] != SWAPBLK_NONE) {
1812 swp_pager_freeswapspace(swap->swb_pages[idx], 1);
1817 * Enter block into metadata
1819 swap->swb_pages[idx] = swapblk;
1820 if (swapblk != SWAPBLK_NONE)
1823 mtx_unlock(&swhash_mtx);
1827 * SWP_PAGER_META_FREE() - free a range of blocks in the object's swap metadata
1829 * The requested range of blocks is freed, with any associated swap
1830 * returned to the swap bitmap.
1832 * This routine will free swap metadata structures as they are cleaned
1833 * out. This routine does *NOT* operate on swap metadata associated
1834 * with resident pages.
1837 swp_pager_meta_free(vm_object_t object, vm_pindex_t index, daddr_t count)
1840 VM_OBJECT_ASSERT_LOCKED(object);
1841 if (object->type != OBJT_SWAP)
1845 struct swblock **pswap;
1846 struct swblock *swap;
1848 mtx_lock(&swhash_mtx);
1849 pswap = swp_pager_hash(object, index);
1851 if ((swap = *pswap) != NULL) {
1852 daddr_t v = swap->swb_pages[index & SWAP_META_MASK];
1854 if (v != SWAPBLK_NONE) {
1855 swp_pager_freeswapspace(v, 1);
1856 swap->swb_pages[index & SWAP_META_MASK] =
1858 if (--swap->swb_count == 0) {
1859 *pswap = swap->swb_hnext;
1860 uma_zfree(swap_zone, swap);
1861 --object->un_pager.swp.swp_bcount;
1867 int n = SWAP_META_PAGES - (index & SWAP_META_MASK);
1871 mtx_unlock(&swhash_mtx);
1876 * SWP_PAGER_META_FREE_ALL() - destroy all swap metadata associated with object
1878 * This routine locates and destroys all swap metadata associated with
1882 swp_pager_meta_free_all(vm_object_t object)
1886 VM_OBJECT_ASSERT_WLOCKED(object);
1887 if (object->type != OBJT_SWAP)
1890 while (object->un_pager.swp.swp_bcount) {
1891 struct swblock **pswap;
1892 struct swblock *swap;
1894 mtx_lock(&swhash_mtx);
1895 pswap = swp_pager_hash(object, index);
1896 if ((swap = *pswap) != NULL) {
1899 for (i = 0; i < SWAP_META_PAGES; ++i) {
1900 daddr_t v = swap->swb_pages[i];
1901 if (v != SWAPBLK_NONE) {
1903 swp_pager_freeswapspace(v, 1);
1906 if (swap->swb_count != 0)
1907 panic("swap_pager_meta_free_all: swb_count != 0");
1908 *pswap = swap->swb_hnext;
1909 uma_zfree(swap_zone, swap);
1910 --object->un_pager.swp.swp_bcount;
1912 mtx_unlock(&swhash_mtx);
1913 index += SWAP_META_PAGES;
1918 * SWP_PAGER_METACTL() - misc control of swap and vm_page_t meta data.
1920 * This routine is capable of looking up, popping, or freeing
1921 * swapblk assignments in the swap meta data or in the vm_page_t.
1922 * The routine typically returns the swapblk being looked-up, or popped,
1923 * or SWAPBLK_NONE if the block was freed, or SWAPBLK_NONE if the block
1924 * was invalid. This routine will automatically free any invalid
1925 * meta-data swapblks.
1927 * It is not possible to store invalid swapblks in the swap meta data
1928 * (other then a literal 'SWAPBLK_NONE'), so we don't bother checking.
1930 * When acting on a busy resident page and paging is in progress, we
1931 * have to wait until paging is complete but otherwise can act on the
1934 * SWM_FREE remove and free swap block from metadata
1935 * SWM_POP remove from meta data but do not free.. pop it out
1938 swp_pager_meta_ctl(vm_object_t object, vm_pindex_t pindex, int flags)
1940 struct swblock **pswap;
1941 struct swblock *swap;
1945 VM_OBJECT_ASSERT_LOCKED(object);
1947 * The meta data only exists of the object is OBJT_SWAP
1948 * and even then might not be allocated yet.
1950 if (object->type != OBJT_SWAP)
1951 return (SWAPBLK_NONE);
1954 mtx_lock(&swhash_mtx);
1955 pswap = swp_pager_hash(object, pindex);
1957 if ((swap = *pswap) != NULL) {
1958 idx = pindex & SWAP_META_MASK;
1959 r1 = swap->swb_pages[idx];
1961 if (r1 != SWAPBLK_NONE) {
1962 if (flags & SWM_FREE) {
1963 swp_pager_freeswapspace(r1, 1);
1966 if (flags & (SWM_FREE|SWM_POP)) {
1967 swap->swb_pages[idx] = SWAPBLK_NONE;
1968 if (--swap->swb_count == 0) {
1969 *pswap = swap->swb_hnext;
1970 uma_zfree(swap_zone, swap);
1971 --object->un_pager.swp.swp_bcount;
1976 mtx_unlock(&swhash_mtx);
1981 * System call swapon(name) enables swapping on device name,
1982 * which must be in the swdevsw. Return EBUSY
1983 * if already swapping on this device.
1985 #ifndef _SYS_SYSPROTO_H_
1986 struct swapon_args {
1996 sys_swapon(struct thread *td, struct swapon_args *uap)
2000 struct nameidata nd;
2003 error = priv_check(td, PRIV_SWAPON);
2007 sx_xlock(&swdev_syscall_lock);
2010 * Swap metadata may not fit in the KVM if we have physical
2013 if (swap_zone == NULL) {
2018 NDINIT(&nd, LOOKUP, ISOPEN | FOLLOW | AUDITVNODE1, UIO_USERSPACE,
2024 NDFREE(&nd, NDF_ONLY_PNBUF);
2027 if (vn_isdisk(vp, &error)) {
2028 error = swapongeom(td, vp);
2029 } else if (vp->v_type == VREG &&
2030 (vp->v_mount->mnt_vfc->vfc_flags & VFCF_NETWORK) != 0 &&
2031 (error = VOP_GETATTR(vp, &attr, td->td_ucred)) == 0) {
2033 * Allow direct swapping to NFS regular files in the same
2034 * way that nfs_mountroot() sets up diskless swapping.
2036 error = swaponvp(td, vp, attr.va_size / DEV_BSIZE);
2042 sx_xunlock(&swdev_syscall_lock);
2047 * Check that the total amount of swap currently configured does not
2048 * exceed half the theoretical maximum. If it does, print a warning
2049 * message and return -1; otherwise, return 0.
2052 swapon_check_swzone(unsigned long npages)
2054 unsigned long maxpages;
2056 /* absolute maximum we can handle assuming 100% efficiency */
2057 maxpages = uma_zone_get_max(swap_zone) * SWAP_META_PAGES;
2059 /* recommend using no more than half that amount */
2060 if (npages > maxpages / 2) {
2061 printf("warning: total configured swap (%lu pages) "
2062 "exceeds maximum recommended amount (%lu pages).\n",
2063 npages, maxpages / 2);
2064 printf("warning: increase kern.maxswzone "
2065 "or reduce amount of swap.\n");
2072 swaponsomething(struct vnode *vp, void *id, u_long nblks,
2073 sw_strategy_t *strategy, sw_close_t *close, dev_t dev, int flags)
2075 struct swdevt *sp, *tsp;
2080 * nblks is in DEV_BSIZE'd chunks, convert to PAGE_SIZE'd chunks.
2081 * First chop nblks off to page-align it, then convert.
2083 * sw->sw_nblks is in page-sized chunks now too.
2085 nblks &= ~(ctodb(1) - 1);
2086 nblks = dbtoc(nblks);
2089 * If we go beyond this, we get overflows in the radix
2092 mblocks = 0x40000000 / BLIST_META_RADIX;
2093 if (nblks > mblocks) {
2095 "WARNING: reducing swap size to maximum of %luMB per unit\n",
2096 mblocks / 1024 / 1024 * PAGE_SIZE);
2100 sp = malloc(sizeof *sp, M_VMPGDATA, M_WAITOK | M_ZERO);
2105 sp->sw_nblks = nblks;
2107 sp->sw_strategy = strategy;
2108 sp->sw_close = close;
2109 sp->sw_flags = flags;
2111 sp->sw_blist = blist_create(nblks, M_WAITOK);
2113 * Do not free the first two block in order to avoid overwriting
2114 * any bsd label at the front of the partition
2116 blist_free(sp->sw_blist, 2, nblks - 2);
2119 mtx_lock(&sw_dev_mtx);
2120 TAILQ_FOREACH(tsp, &swtailq, sw_list) {
2121 if (tsp->sw_end >= dvbase) {
2123 * We put one uncovered page between the devices
2124 * in order to definitively prevent any cross-device
2127 dvbase = tsp->sw_end + 1;
2130 sp->sw_first = dvbase;
2131 sp->sw_end = dvbase + nblks;
2132 TAILQ_INSERT_TAIL(&swtailq, sp, sw_list);
2134 swap_pager_avail += nblks;
2135 swap_total += (vm_ooffset_t)nblks * PAGE_SIZE;
2136 swapon_check_swzone(swap_total / PAGE_SIZE);
2138 mtx_unlock(&sw_dev_mtx);
2142 * SYSCALL: swapoff(devname)
2144 * Disable swapping on the given device.
2146 * XXX: Badly designed system call: it should use a device index
2147 * rather than filename as specification. We keep sw_vp around
2148 * only to make this work.
2150 #ifndef _SYS_SYSPROTO_H_
2151 struct swapoff_args {
2161 sys_swapoff(struct thread *td, struct swapoff_args *uap)
2164 struct nameidata nd;
2168 error = priv_check(td, PRIV_SWAPOFF);
2172 sx_xlock(&swdev_syscall_lock);
2174 NDINIT(&nd, LOOKUP, FOLLOW | AUDITVNODE1, UIO_USERSPACE, uap->name,
2179 NDFREE(&nd, NDF_ONLY_PNBUF);
2182 mtx_lock(&sw_dev_mtx);
2183 TAILQ_FOREACH(sp, &swtailq, sw_list) {
2184 if (sp->sw_vp == vp)
2187 mtx_unlock(&sw_dev_mtx);
2192 error = swapoff_one(sp, td->td_ucred);
2194 sx_xunlock(&swdev_syscall_lock);
2199 swapoff_one(struct swdevt *sp, struct ucred *cred)
2201 u_long nblks, dvbase;
2206 sx_assert(&swdev_syscall_lock, SA_XLOCKED);
2208 (void) vn_lock(sp->sw_vp, LK_EXCLUSIVE | LK_RETRY);
2209 error = mac_system_check_swapoff(cred, sp->sw_vp);
2210 (void) VOP_UNLOCK(sp->sw_vp, 0);
2214 nblks = sp->sw_nblks;
2217 * We can turn off this swap device safely only if the
2218 * available virtual memory in the system will fit the amount
2219 * of data we will have to page back in, plus an epsilon so
2220 * the system doesn't become critically low on swap space.
2222 if (vm_cnt.v_free_count + vm_cnt.v_cache_count + swap_pager_avail <
2223 nblks + nswap_lowat) {
2228 * Prevent further allocations on this device.
2230 mtx_lock(&sw_dev_mtx);
2231 sp->sw_flags |= SW_CLOSING;
2232 for (dvbase = 0; dvbase < sp->sw_end; dvbase += dmmax) {
2233 swap_pager_avail -= blist_fill(sp->sw_blist,
2236 swap_total -= (vm_ooffset_t)nblks * PAGE_SIZE;
2237 mtx_unlock(&sw_dev_mtx);
2240 * Page in the contents of the device and close it.
2242 swap_pager_swapoff(sp);
2244 sp->sw_close(curthread, sp);
2245 mtx_lock(&sw_dev_mtx);
2247 TAILQ_REMOVE(&swtailq, sp, sw_list);
2249 if (nswapdev == 0) {
2250 swap_pager_full = 2;
2251 swap_pager_almost_full = 1;
2255 mtx_unlock(&sw_dev_mtx);
2256 blist_destroy(sp->sw_blist);
2257 free(sp, M_VMPGDATA);
2264 struct swdevt *sp, *spt;
2265 const char *devname;
2268 sx_xlock(&swdev_syscall_lock);
2270 mtx_lock(&sw_dev_mtx);
2271 TAILQ_FOREACH_SAFE(sp, &swtailq, sw_list, spt) {
2272 mtx_unlock(&sw_dev_mtx);
2273 if (vn_isdisk(sp->sw_vp, NULL))
2274 devname = devtoname(sp->sw_vp->v_rdev);
2277 error = swapoff_one(sp, thread0.td_ucred);
2279 printf("Cannot remove swap device %s (error=%d), "
2280 "skipping.\n", devname, error);
2281 } else if (bootverbose) {
2282 printf("Swap device %s removed.\n", devname);
2284 mtx_lock(&sw_dev_mtx);
2286 mtx_unlock(&sw_dev_mtx);
2288 sx_xunlock(&swdev_syscall_lock);
2292 swap_pager_status(int *total, int *used)
2298 mtx_lock(&sw_dev_mtx);
2299 TAILQ_FOREACH(sp, &swtailq, sw_list) {
2300 *total += sp->sw_nblks;
2301 *used += sp->sw_used;
2303 mtx_unlock(&sw_dev_mtx);
2307 swap_dev_info(int name, struct xswdev *xs, char *devname, size_t len)
2310 const char *tmp_devname;
2315 mtx_lock(&sw_dev_mtx);
2316 TAILQ_FOREACH(sp, &swtailq, sw_list) {
2321 xs->xsw_version = XSWDEV_VERSION;
2322 xs->xsw_dev = sp->sw_dev;
2323 xs->xsw_flags = sp->sw_flags;
2324 xs->xsw_nblks = sp->sw_nblks;
2325 xs->xsw_used = sp->sw_used;
2326 if (devname != NULL) {
2327 if (vn_isdisk(sp->sw_vp, NULL))
2328 tmp_devname = devtoname(sp->sw_vp->v_rdev);
2330 tmp_devname = "[file]";
2331 strncpy(devname, tmp_devname, len);
2336 mtx_unlock(&sw_dev_mtx);
2341 sysctl_vm_swap_info(SYSCTL_HANDLER_ARGS)
2346 if (arg2 != 1) /* name length */
2348 error = swap_dev_info(*(int *)arg1, &xs, NULL, 0);
2351 error = SYSCTL_OUT(req, &xs, sizeof(xs));
2355 SYSCTL_INT(_vm, OID_AUTO, nswapdev, CTLFLAG_RD, &nswapdev, 0,
2356 "Number of swap devices");
2357 SYSCTL_NODE(_vm, OID_AUTO, swap_info, CTLFLAG_RD | CTLFLAG_MPSAFE,
2358 sysctl_vm_swap_info,
2359 "Swap statistics by device");
2362 * vmspace_swap_count() - count the approximate swap usage in pages for a
2365 * The map must be locked.
2367 * Swap usage is determined by taking the proportional swap used by
2368 * VM objects backing the VM map. To make up for fractional losses,
2369 * if the VM object has any swap use at all the associated map entries
2370 * count for at least 1 swap page.
2373 vmspace_swap_count(struct vmspace *vmspace)
2380 map = &vmspace->vm_map;
2383 for (cur = map->header.next; cur != &map->header; cur = cur->next) {
2384 if ((cur->eflags & MAP_ENTRY_IS_SUB_MAP) == 0 &&
2385 (object = cur->object.vm_object) != NULL) {
2386 VM_OBJECT_WLOCK(object);
2387 if (object->type == OBJT_SWAP &&
2388 object->un_pager.swp.swp_bcount != 0) {
2389 n = (cur->end - cur->start) / PAGE_SIZE;
2390 count += object->un_pager.swp.swp_bcount *
2391 SWAP_META_PAGES * n / object->size + 1;
2393 VM_OBJECT_WUNLOCK(object);
2402 * Swapping onto disk devices.
2406 static g_orphan_t swapgeom_orphan;
2408 static struct g_class g_swap_class = {
2410 .version = G_VERSION,
2411 .orphan = swapgeom_orphan,
2414 DECLARE_GEOM_CLASS(g_swap_class, g_class);
2418 swapgeom_close_ev(void *arg, int flags)
2420 struct g_consumer *cp;
2423 g_access(cp, -1, -1, 0);
2425 g_destroy_consumer(cp);
2429 * Add a reference to the g_consumer for an inflight transaction.
2432 swapgeom_acquire(struct g_consumer *cp)
2435 mtx_assert(&sw_dev_mtx, MA_OWNED);
2440 * Remove a reference from the g_consumer. Post a close event if
2441 * all referneces go away.
2444 swapgeom_release(struct g_consumer *cp, struct swdevt *sp)
2447 mtx_assert(&sw_dev_mtx, MA_OWNED);
2449 if (cp->index == 0) {
2450 if (g_post_event(swapgeom_close_ev, cp, M_NOWAIT, NULL) == 0)
2456 swapgeom_done(struct bio *bp2)
2460 struct g_consumer *cp;
2462 bp = bp2->bio_caller2;
2464 bp->b_ioflags = bp2->bio_flags;
2466 bp->b_ioflags |= BIO_ERROR;
2467 bp->b_resid = bp->b_bcount - bp2->bio_completed;
2468 bp->b_error = bp2->bio_error;
2470 sp = bp2->bio_caller1;
2471 mtx_lock(&sw_dev_mtx);
2472 swapgeom_release(cp, sp);
2473 mtx_unlock(&sw_dev_mtx);
2478 swapgeom_strategy(struct buf *bp, struct swdevt *sp)
2481 struct g_consumer *cp;
2483 mtx_lock(&sw_dev_mtx);
2486 mtx_unlock(&sw_dev_mtx);
2487 bp->b_error = ENXIO;
2488 bp->b_ioflags |= BIO_ERROR;
2492 swapgeom_acquire(cp);
2493 mtx_unlock(&sw_dev_mtx);
2494 if (bp->b_iocmd == BIO_WRITE)
2497 bio = g_alloc_bio();
2499 mtx_lock(&sw_dev_mtx);
2500 swapgeom_release(cp, sp);
2501 mtx_unlock(&sw_dev_mtx);
2502 bp->b_error = ENOMEM;
2503 bp->b_ioflags |= BIO_ERROR;
2508 bio->bio_caller1 = sp;
2509 bio->bio_caller2 = bp;
2510 bio->bio_cmd = bp->b_iocmd;
2511 bio->bio_offset = (bp->b_blkno - sp->sw_first) * PAGE_SIZE;
2512 bio->bio_length = bp->b_bcount;
2513 bio->bio_done = swapgeom_done;
2514 if (!buf_mapped(bp)) {
2515 bio->bio_ma = bp->b_pages;
2516 bio->bio_data = unmapped_buf;
2517 bio->bio_ma_offset = (vm_offset_t)bp->b_offset & PAGE_MASK;
2518 bio->bio_ma_n = bp->b_npages;
2519 bio->bio_flags |= BIO_UNMAPPED;
2521 bio->bio_data = bp->b_data;
2524 g_io_request(bio, cp);
2529 swapgeom_orphan(struct g_consumer *cp)
2534 mtx_lock(&sw_dev_mtx);
2535 TAILQ_FOREACH(sp, &swtailq, sw_list) {
2536 if (sp->sw_id == cp) {
2537 sp->sw_flags |= SW_CLOSING;
2542 * Drop reference we were created with. Do directly since we're in a
2543 * special context where we don't have to queue the call to
2544 * swapgeom_close_ev().
2547 destroy = ((sp != NULL) && (cp->index == 0));
2550 mtx_unlock(&sw_dev_mtx);
2552 swapgeom_close_ev(cp, 0);
2556 swapgeom_close(struct thread *td, struct swdevt *sw)
2558 struct g_consumer *cp;
2560 mtx_lock(&sw_dev_mtx);
2563 mtx_unlock(&sw_dev_mtx);
2564 /* XXX: direct call when Giant untangled */
2566 g_waitfor_event(swapgeom_close_ev, cp, M_WAITOK, NULL);
2577 swapongeom_ev(void *arg, int flags)
2580 struct g_provider *pp;
2581 struct g_consumer *cp;
2582 static struct g_geom *gp;
2589 pp = g_dev_getprovider(swh->dev);
2591 swh->error = ENODEV;
2594 mtx_lock(&sw_dev_mtx);
2595 TAILQ_FOREACH(sp, &swtailq, sw_list) {
2597 if (cp != NULL && cp->provider == pp) {
2598 mtx_unlock(&sw_dev_mtx);
2603 mtx_unlock(&sw_dev_mtx);
2605 gp = g_new_geomf(&g_swap_class, "swap");
2606 cp = g_new_consumer(gp);
2607 cp->index = 1; /* Number of active I/Os, plus one for being active. */
2608 cp->flags |= G_CF_DIRECT_SEND | G_CF_DIRECT_RECEIVE;
2611 * XXX: Every time you think you can improve the margin for
2612 * footshooting, somebody depends on the ability to do so:
2613 * savecore(8) wants to write to our swapdev so we cannot
2614 * set an exclusive count :-(
2616 error = g_access(cp, 1, 1, 0);
2619 g_destroy_consumer(cp);
2623 nblks = pp->mediasize / DEV_BSIZE;
2624 swaponsomething(swh->vp, cp, nblks, swapgeom_strategy,
2625 swapgeom_close, dev2udev(swh->dev),
2626 (pp->flags & G_PF_ACCEPT_UNMAPPED) != 0 ? SW_UNMAPPED : 0);
2631 swapongeom(struct thread *td, struct vnode *vp)
2636 vn_lock(vp, LK_EXCLUSIVE | LK_RETRY);
2638 swh.dev = vp->v_rdev;
2641 /* XXX: direct call when Giant untangled */
2642 error = g_waitfor_event(swapongeom_ev, &swh, M_WAITOK, NULL);
2652 * This is used mainly for network filesystem (read: probably only tested
2653 * with NFS) swapfiles.
2658 swapdev_strategy(struct buf *bp, struct swdevt *sp)
2662 bp->b_blkno = ctodb(bp->b_blkno - sp->sw_first);
2666 if (bp->b_iocmd == BIO_WRITE) {
2668 bufobj_wdrop(bp->b_bufobj);
2669 bufobj_wref(&vp2->v_bufobj);
2671 if (bp->b_bufobj != &vp2->v_bufobj)
2672 bp->b_bufobj = &vp2->v_bufobj;
2674 bp->b_iooffset = dbtob(bp->b_blkno);
2680 swapdev_close(struct thread *td, struct swdevt *sp)
2683 VOP_CLOSE(sp->sw_vp, FREAD | FWRITE, td->td_ucred, td);
2689 swaponvp(struct thread *td, struct vnode *vp, u_long nblks)
2696 mtx_lock(&sw_dev_mtx);
2697 TAILQ_FOREACH(sp, &swtailq, sw_list) {
2698 if (sp->sw_id == vp) {
2699 mtx_unlock(&sw_dev_mtx);
2703 mtx_unlock(&sw_dev_mtx);
2705 (void) vn_lock(vp, LK_EXCLUSIVE | LK_RETRY);
2707 error = mac_system_check_swapon(td->td_ucred, vp);
2710 error = VOP_OPEN(vp, FREAD | FWRITE, td->td_ucred, td, NULL);
2711 (void) VOP_UNLOCK(vp, 0);
2715 swaponsomething(vp, vp, nblks, swapdev_strategy, swapdev_close,
2721 sysctl_swap_async_max(SYSCTL_HANDLER_ARGS)
2725 new = nsw_wcount_async_max;
2726 error = sysctl_handle_int(oidp, &new, 0, req);
2727 if (error != 0 || req->newptr == NULL)
2730 if (new > nswbuf / 2 || new < 1)
2733 mtx_lock(&pbuf_mtx);
2734 while (nsw_wcount_async_max != new) {
2736 * Adjust difference. If the current async count is too low,
2737 * we will need to sqeeze our update slowly in. Sleep with a
2738 * higher priority than getpbuf() to finish faster.
2740 n = new - nsw_wcount_async_max;
2741 if (nsw_wcount_async + n >= 0) {
2742 nsw_wcount_async += n;
2743 nsw_wcount_async_max += n;
2744 wakeup(&nsw_wcount_async);
2746 nsw_wcount_async_max -= nsw_wcount_async;
2747 nsw_wcount_async = 0;
2748 msleep(&nsw_wcount_async, &pbuf_mtx, PSWP,
2752 mtx_unlock(&pbuf_mtx);