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 int swdev_syscall_active = 0; /* 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 static void swapdev_strategy(struct buf *, struct swdevt *sw);
318 #define SWM_FREE 0x02 /* free, period */
319 #define SWM_POP 0x04 /* pop out */
321 int swap_pager_full = 2; /* swap space exhaustion (task killing) */
322 static int swap_pager_almost_full = 1; /* swap space exhaustion (w/hysteresis)*/
323 static int nsw_rcount; /* free read buffers */
324 static int nsw_wcount_sync; /* limit write buffers / synchronous */
325 static int nsw_wcount_async; /* limit write buffers / asynchronous */
326 static int nsw_wcount_async_max;/* assigned maximum */
327 static int nsw_cluster_max; /* maximum VOP I/O allowed */
329 static int sysctl_swap_async_max(SYSCTL_HANDLER_ARGS);
330 SYSCTL_PROC(_vm, OID_AUTO, swap_async_max, CTLTYPE_INT | CTLFLAG_RW,
331 NULL, 0, sysctl_swap_async_max, "I", "Maximum running async swap ops");
333 static struct swblock **swhash;
334 static int swhash_mask;
335 static struct mtx swhash_mtx;
337 static struct sx sw_alloc_sx;
340 * "named" and "unnamed" anon region objects. Try to reduce the overhead
341 * of searching a named list by hashing it just a little.
346 #define NOBJLIST(handle) \
347 (&swap_pager_object_list[((int)(intptr_t)handle >> 4) & (NOBJLISTS-1)])
349 static struct mtx sw_alloc_mtx; /* protect list manipulation */
350 static struct pagerlst swap_pager_object_list[NOBJLISTS];
351 static uma_zone_t swap_zone;
354 * pagerops for OBJT_SWAP - "swap pager". Some ops are also global procedure
355 * calls hooked from other parts of the VM system and do not appear here.
356 * (see vm/swap_pager.h).
359 swap_pager_alloc(void *handle, vm_ooffset_t size,
360 vm_prot_t prot, vm_ooffset_t offset, struct ucred *);
361 static void swap_pager_dealloc(vm_object_t object);
362 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 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_pager_free_nrpage(vm_page_t m)
423 if (m->wire_count == 0)
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 * SWP_PAGER_HASH() - hash swap meta data
458 * This is an helper function which hashes the swapblk given
459 * the object and page index. It returns a pointer to a pointer
460 * to the object, or a pointer to a NULL pointer if it could not
463 static struct swblock **
464 swp_pager_hash(vm_object_t object, vm_pindex_t index)
466 struct swblock **pswap;
467 struct swblock *swap;
469 index &= ~(vm_pindex_t)SWAP_META_MASK;
470 pswap = &swhash[(index ^ (int)(intptr_t)object) & swhash_mask];
471 while ((swap = *pswap) != NULL) {
472 if (swap->swb_object == object &&
473 swap->swb_index == index
477 pswap = &swap->swb_hnext;
483 * SWAP_PAGER_INIT() - initialize the swap pager!
485 * Expected to be started from system init. NOTE: This code is run
486 * before much else so be careful what you depend on. Most of the VM
487 * system has yet to be initialized at this point.
490 swap_pager_init(void)
493 * Initialize object lists
497 for (i = 0; i < NOBJLISTS; ++i)
498 TAILQ_INIT(&swap_pager_object_list[i]);
499 mtx_init(&sw_alloc_mtx, "swap_pager list", NULL, MTX_DEF);
500 mtx_init(&sw_dev_mtx, "swapdev", NULL, MTX_DEF);
503 * Device Stripe, in PAGE_SIZE'd blocks
505 dmmax = SWB_NPAGES * 2;
509 * SWAP_PAGER_SWAP_INIT() - swap pager initialization from pageout process
511 * Expected to be started from pageout process once, prior to entering
515 swap_pager_swap_init(void)
520 * Number of in-transit swap bp operations. Don't
521 * exhaust the pbufs completely. Make sure we
522 * initialize workable values (0 will work for hysteresis
523 * but it isn't very efficient).
525 * The nsw_cluster_max is constrained by the bp->b_pages[]
526 * array (MAXPHYS/PAGE_SIZE) and our locally defined
527 * MAX_PAGEOUT_CLUSTER. Also be aware that swap ops are
528 * constrained by the swap device interleave stripe size.
530 * Currently we hardwire nsw_wcount_async to 4. This limit is
531 * designed to prevent other I/O from having high latencies due to
532 * our pageout I/O. The value 4 works well for one or two active swap
533 * devices but is probably a little low if you have more. Even so,
534 * a higher value would probably generate only a limited improvement
535 * with three or four active swap devices since the system does not
536 * typically have to pageout at extreme bandwidths. We will want
537 * at least 2 per swap devices, and 4 is a pretty good value if you
538 * have one NFS swap device due to the command/ack latency over NFS.
539 * So it all works out pretty well.
541 nsw_cluster_max = min((MAXPHYS/PAGE_SIZE), MAX_PAGEOUT_CLUSTER);
544 nsw_rcount = (nswbuf + 1) / 2;
545 nsw_wcount_sync = (nswbuf + 3) / 4;
546 nsw_wcount_async = 4;
547 nsw_wcount_async_max = nsw_wcount_async;
548 mtx_unlock(&pbuf_mtx);
551 * Initialize our zone. Right now I'm just guessing on the number
552 * we need based on the number of pages in the system. Each swblock
553 * can hold 32 pages, so this is probably overkill. This reservation
554 * is typically limited to around 32MB by default.
556 n = vm_cnt.v_page_count / 2;
557 if (maxswzone && n > maxswzone / sizeof(struct swblock))
558 n = maxswzone / sizeof(struct swblock);
560 swap_zone = uma_zcreate("SWAPMETA", sizeof(struct swblock), NULL, NULL,
561 NULL, NULL, UMA_ALIGN_PTR, UMA_ZONE_NOFREE | UMA_ZONE_VM);
562 if (swap_zone == NULL)
563 panic("failed to create swap_zone.");
565 if (uma_zone_reserve_kva(swap_zone, n))
568 * if the allocation failed, try a zone two thirds the
569 * size of the previous attempt.
574 printf("Swap zone entries reduced from %lu to %lu.\n", n2, n);
575 swap_maxpages = n * SWAP_META_PAGES;
576 swzone = n * sizeof(struct swblock);
580 * Initialize our meta-data hash table. The swapper does not need to
581 * be quite as efficient as the VM system, so we do not use an
582 * oversized hash table.
584 * n: size of hash table, must be power of 2
585 * swhash_mask: hash table index mask
587 for (n = 1; n < n2 / 8; n *= 2)
589 swhash = malloc(sizeof(struct swblock *) * n, M_VMPGDATA, M_WAITOK | M_ZERO);
591 mtx_init(&swhash_mtx, "swap_pager swhash", NULL, MTX_DEF);
595 * SWAP_PAGER_ALLOC() - allocate a new OBJT_SWAP VM object and instantiate
596 * its metadata structures.
598 * This routine is called from the mmap and fork code to create a new
599 * OBJT_SWAP object. We do this by creating an OBJT_DEFAULT object
600 * and then converting it with swp_pager_meta_build().
602 * This routine may block in vm_object_allocate() and create a named
603 * object lookup race, so we must interlock.
608 swap_pager_alloc(void *handle, vm_ooffset_t size, vm_prot_t prot,
609 vm_ooffset_t offset, struct ucred *cred)
614 pindex = OFF_TO_IDX(offset + PAGE_MASK + size);
618 * Reference existing named region or allocate new one. There
619 * should not be a race here against swp_pager_meta_build()
620 * as called from vm_page_remove() in regards to the lookup
623 sx_xlock(&sw_alloc_sx);
624 object = vm_pager_object_lookup(NOBJLIST(handle), handle);
625 if (object == NULL) {
627 if (!swap_reserve_by_cred(size, cred)) {
628 sx_xunlock(&sw_alloc_sx);
634 object = vm_object_allocate(OBJT_DEFAULT, pindex);
635 VM_OBJECT_WLOCK(object);
636 object->handle = handle;
639 object->charge = size;
641 swp_pager_meta_build(object, 0, SWAPBLK_NONE);
642 VM_OBJECT_WUNLOCK(object);
644 sx_xunlock(&sw_alloc_sx);
648 if (!swap_reserve_by_cred(size, cred))
652 object = vm_object_allocate(OBJT_DEFAULT, pindex);
653 VM_OBJECT_WLOCK(object);
656 object->charge = size;
658 swp_pager_meta_build(object, 0, SWAPBLK_NONE);
659 VM_OBJECT_WUNLOCK(object);
665 * SWAP_PAGER_DEALLOC() - remove swap metadata from object
667 * The swap backing for the object is destroyed. The code is
668 * designed such that we can reinstantiate it later, but this
669 * routine is typically called only when the entire object is
670 * about to be destroyed.
672 * The object must be locked.
675 swap_pager_dealloc(vm_object_t object)
679 * Remove from list right away so lookups will fail if we block for
680 * pageout completion.
682 if (object->handle != NULL) {
683 mtx_lock(&sw_alloc_mtx);
684 TAILQ_REMOVE(NOBJLIST(object->handle), object, pager_object_list);
685 mtx_unlock(&sw_alloc_mtx);
688 VM_OBJECT_ASSERT_WLOCKED(object);
689 vm_object_pip_wait(object, "swpdea");
692 * Free all remaining metadata. We only bother to free it from
693 * the swap meta data. We do not attempt to free swapblk's still
694 * associated with vm_page_t's for this object. We do not care
695 * if paging is still in progress on some objects.
697 swp_pager_meta_free_all(object);
698 object->handle = NULL;
699 object->type = OBJT_DEAD;
702 /************************************************************************
703 * SWAP PAGER BITMAP ROUTINES *
704 ************************************************************************/
707 * SWP_PAGER_GETSWAPSPACE() - allocate raw swap space
709 * Allocate swap for the requested number of pages. The starting
710 * swap block number (a page index) is returned or SWAPBLK_NONE
711 * if the allocation failed.
713 * Also has the side effect of advising that somebody made a mistake
714 * when they configured swap and didn't configure enough.
716 * This routine may not sleep.
718 * We allocate in round-robin fashion from the configured devices.
721 swp_pager_getswapspace(int npages)
728 mtx_lock(&sw_dev_mtx);
730 for (i = 0; i < nswapdev; i++) {
732 sp = TAILQ_FIRST(&swtailq);
733 if (!(sp->sw_flags & SW_CLOSING)) {
734 blk = blist_alloc(sp->sw_blist, npages);
735 if (blk != SWAPBLK_NONE) {
737 sp->sw_used += npages;
738 swap_pager_avail -= npages;
740 swdevhd = TAILQ_NEXT(sp, sw_list);
744 sp = TAILQ_NEXT(sp, sw_list);
746 if (swap_pager_full != 2) {
747 printf("swap_pager_getswapspace(%d): failed\n", npages);
749 swap_pager_almost_full = 1;
753 mtx_unlock(&sw_dev_mtx);
758 swp_pager_isondev(daddr_t blk, struct swdevt *sp)
761 return (blk >= sp->sw_first && blk < sp->sw_end);
765 swp_pager_strategy(struct buf *bp)
769 mtx_lock(&sw_dev_mtx);
770 TAILQ_FOREACH(sp, &swtailq, sw_list) {
771 if (bp->b_blkno >= sp->sw_first && bp->b_blkno < sp->sw_end) {
772 mtx_unlock(&sw_dev_mtx);
773 if ((sp->sw_flags & SW_UNMAPPED) != 0 &&
774 unmapped_buf_allowed) {
775 bp->b_kvaalloc = bp->b_data;
776 bp->b_data = unmapped_buf;
777 bp->b_kvabase = unmapped_buf;
779 bp->b_flags |= B_UNMAPPED;
781 pmap_qenter((vm_offset_t)bp->b_data,
782 &bp->b_pages[0], bp->b_bcount / PAGE_SIZE);
784 sp->sw_strategy(bp, sp);
788 panic("Swapdev not found");
793 * SWP_PAGER_FREESWAPSPACE() - free raw swap space
795 * This routine returns the specified swap blocks back to the bitmap.
797 * This routine may not sleep.
800 swp_pager_freeswapspace(daddr_t blk, int npages)
804 mtx_lock(&sw_dev_mtx);
805 TAILQ_FOREACH(sp, &swtailq, sw_list) {
806 if (blk >= sp->sw_first && blk < sp->sw_end) {
807 sp->sw_used -= npages;
809 * If we are attempting to stop swapping on
810 * this device, we don't want to mark any
811 * blocks free lest they be reused.
813 if ((sp->sw_flags & SW_CLOSING) == 0) {
814 blist_free(sp->sw_blist, blk - sp->sw_first,
816 swap_pager_avail += npages;
819 mtx_unlock(&sw_dev_mtx);
823 panic("Swapdev not found");
827 * SWAP_PAGER_FREESPACE() - frees swap blocks associated with a page
828 * range within an object.
830 * This is a globally accessible routine.
832 * This routine removes swapblk assignments from swap metadata.
834 * The external callers of this routine typically have already destroyed
835 * or renamed vm_page_t's associated with this range in the object so
838 * The object must be locked.
841 swap_pager_freespace(vm_object_t object, vm_pindex_t start, vm_size_t size)
844 swp_pager_meta_free(object, start, size);
848 * SWAP_PAGER_RESERVE() - reserve swap blocks in object
850 * Assigns swap blocks to the specified range within the object. The
851 * swap blocks are not zeroed. Any previous swap assignment is destroyed.
853 * Returns 0 on success, -1 on failure.
856 swap_pager_reserve(vm_object_t object, vm_pindex_t start, vm_size_t size)
859 daddr_t blk = SWAPBLK_NONE;
860 vm_pindex_t beg = start; /* save start index */
862 VM_OBJECT_WLOCK(object);
866 while ((blk = swp_pager_getswapspace(n)) == SWAPBLK_NONE) {
869 swp_pager_meta_free(object, beg, start - beg);
870 VM_OBJECT_WUNLOCK(object);
875 swp_pager_meta_build(object, start, blk);
881 swp_pager_meta_free(object, start, n);
882 VM_OBJECT_WUNLOCK(object);
887 * SWAP_PAGER_COPY() - copy blocks from source pager to destination pager
888 * and destroy the source.
890 * Copy any valid swapblks from the source to the destination. In
891 * cases where both the source and destination have a valid swapblk,
892 * we keep the destination's.
894 * This routine is allowed to sleep. It may sleep allocating metadata
895 * indirectly through swp_pager_meta_build() or if paging is still in
896 * progress on the source.
898 * The source object contains no vm_page_t's (which is just as well)
900 * The source object is of type OBJT_SWAP.
902 * The source and destination objects must be locked.
903 * Both object locks may temporarily be released.
906 swap_pager_copy(vm_object_t srcobject, vm_object_t dstobject,
907 vm_pindex_t offset, int destroysource)
911 VM_OBJECT_ASSERT_WLOCKED(srcobject);
912 VM_OBJECT_ASSERT_WLOCKED(dstobject);
915 * If destroysource is set, we remove the source object from the
916 * swap_pager internal queue now.
919 if (srcobject->handle != NULL) {
920 mtx_lock(&sw_alloc_mtx);
922 NOBJLIST(srcobject->handle),
926 mtx_unlock(&sw_alloc_mtx);
931 * transfer source to destination.
933 for (i = 0; i < dstobject->size; ++i) {
937 * Locate (without changing) the swapblk on the destination,
938 * unless it is invalid in which case free it silently, or
939 * if the destination is a resident page, in which case the
940 * source is thrown away.
942 dstaddr = swp_pager_meta_ctl(dstobject, i, 0);
944 if (dstaddr == SWAPBLK_NONE) {
946 * Destination has no swapblk and is not resident,
951 srcaddr = swp_pager_meta_ctl(
957 if (srcaddr != SWAPBLK_NONE) {
959 * swp_pager_meta_build() can sleep.
961 vm_object_pip_add(srcobject, 1);
962 VM_OBJECT_WUNLOCK(srcobject);
963 vm_object_pip_add(dstobject, 1);
964 swp_pager_meta_build(dstobject, i, srcaddr);
965 vm_object_pip_wakeup(dstobject);
966 VM_OBJECT_WLOCK(srcobject);
967 vm_object_pip_wakeup(srcobject);
971 * Destination has valid swapblk or it is represented
972 * by a resident page. We destroy the sourceblock.
975 swp_pager_meta_ctl(srcobject, i + offset, SWM_FREE);
980 * Free left over swap blocks in source.
982 * We have to revert the type to OBJT_DEFAULT so we do not accidently
983 * double-remove the object from the swap queues.
986 swp_pager_meta_free_all(srcobject);
988 * Reverting the type is not necessary, the caller is going
989 * to destroy srcobject directly, but I'm doing it here
990 * for consistency since we've removed the object from its
993 srcobject->type = OBJT_DEFAULT;
998 * SWAP_PAGER_HASPAGE() - determine if we have good backing store for
999 * the requested page.
1001 * We determine whether good backing store exists for the requested
1002 * page and return TRUE if it does, FALSE if it doesn't.
1004 * If TRUE, we also try to determine how much valid, contiguous backing
1005 * store exists before and after the requested page within a reasonable
1006 * distance. We do not try to restrict it to the swap device stripe
1007 * (that is handled in getpages/putpages). It probably isn't worth
1011 swap_pager_haspage(vm_object_t object, vm_pindex_t pindex, int *before, int *after)
1015 VM_OBJECT_ASSERT_LOCKED(object);
1017 * do we have good backing store at the requested index ?
1019 blk0 = swp_pager_meta_ctl(object, pindex, 0);
1021 if (blk0 == SWAPBLK_NONE) {
1030 * find backwards-looking contiguous good backing store
1032 if (before != NULL) {
1035 for (i = 1; i < (SWB_NPAGES/2); ++i) {
1040 blk = swp_pager_meta_ctl(object, pindex - i, 0);
1041 if (blk != blk0 - i)
1048 * find forward-looking contiguous good backing store
1050 if (after != NULL) {
1053 for (i = 1; i < (SWB_NPAGES/2); ++i) {
1056 blk = swp_pager_meta_ctl(object, pindex + i, 0);
1057 if (blk != blk0 + i)
1066 * SWAP_PAGER_PAGE_UNSWAPPED() - remove swap backing store related to page
1068 * This removes any associated swap backing store, whether valid or
1069 * not, from the page.
1071 * This routine is typically called when a page is made dirty, at
1072 * which point any associated swap can be freed. MADV_FREE also
1073 * calls us in a special-case situation
1075 * NOTE!!! If the page is clean and the swap was valid, the caller
1076 * should make the page dirty before calling this routine. This routine
1077 * does NOT change the m->dirty status of the page. Also: MADV_FREE
1080 * This routine may not sleep.
1082 * The object containing the page must be locked.
1085 swap_pager_unswapped(vm_page_t m)
1088 swp_pager_meta_ctl(m->object, m->pindex, SWM_FREE);
1092 * SWAP_PAGER_GETPAGES() - bring pages in from swap
1094 * Attempt to retrieve (m, count) pages from backing store, but make
1095 * sure we retrieve at least m[reqpage]. We try to load in as large
1096 * a chunk surrounding m[reqpage] as is contiguous in swap and which
1097 * belongs to the same object.
1099 * The code is designed for asynchronous operation and
1100 * immediate-notification of 'reqpage' but tends not to be
1101 * used that way. Please do not optimize-out this algorithmic
1102 * feature, I intend to improve on it in the future.
1104 * The parent has a single vm_object_pip_add() reference prior to
1105 * calling us and we should return with the same.
1107 * The parent has BUSY'd the pages. We should return with 'm'
1108 * left busy, but the others adjusted.
1111 swap_pager_getpages(vm_object_t object, vm_page_t *m, int count, int reqpage)
1122 * Calculate range to retrieve. The pages have already been assigned
1123 * their swapblks. We require a *contiguous* range but we know it to
1124 * not span devices. If we do not supply it, bad things
1125 * happen. Note that blk, iblk & jblk can be SWAPBLK_NONE, but the
1126 * loops are set up such that the case(s) are handled implicitly.
1128 * The swp_*() calls must be made with the object locked.
1130 blk = swp_pager_meta_ctl(mreq->object, mreq->pindex, 0);
1132 for (i = reqpage - 1; i >= 0; --i) {
1135 iblk = swp_pager_meta_ctl(m[i]->object, m[i]->pindex, 0);
1136 if (blk != iblk + (reqpage - i))
1141 for (j = reqpage + 1; j < count; ++j) {
1144 jblk = swp_pager_meta_ctl(m[j]->object, m[j]->pindex, 0);
1145 if (blk != jblk - (j - reqpage))
1150 * free pages outside our collection range. Note: we never free
1151 * mreq, it must remain busy throughout.
1153 if (0 < i || j < count) {
1156 for (k = 0; k < i; ++k)
1157 swp_pager_free_nrpage(m[k]);
1158 for (k = j; k < count; ++k)
1159 swp_pager_free_nrpage(m[k]);
1163 * Return VM_PAGER_FAIL if we have nothing to do. Return mreq
1164 * still busy, but the others unbusied.
1166 if (blk == SWAPBLK_NONE)
1167 return (VM_PAGER_FAIL);
1170 * Getpbuf() can sleep.
1172 VM_OBJECT_WUNLOCK(object);
1174 * Get a swap buffer header to perform the IO
1176 bp = getpbuf(&nsw_rcount);
1177 bp->b_flags |= B_PAGING;
1179 bp->b_iocmd = BIO_READ;
1180 bp->b_iodone = swp_pager_async_iodone;
1181 bp->b_rcred = crhold(thread0.td_ucred);
1182 bp->b_wcred = crhold(thread0.td_ucred);
1183 bp->b_blkno = blk - (reqpage - i);
1184 bp->b_bcount = PAGE_SIZE * (j - i);
1185 bp->b_bufsize = PAGE_SIZE * (j - i);
1186 bp->b_pager.pg_reqpage = reqpage - i;
1188 VM_OBJECT_WLOCK(object);
1192 for (k = i; k < j; ++k) {
1193 bp->b_pages[k - i] = m[k];
1194 m[k]->oflags |= VPO_SWAPINPROG;
1197 bp->b_npages = j - i;
1199 PCPU_INC(cnt.v_swapin);
1200 PCPU_ADD(cnt.v_swappgsin, bp->b_npages);
1203 * We still hold the lock on mreq, and our automatic completion routine
1204 * does not remove it.
1206 vm_object_pip_add(object, bp->b_npages);
1207 VM_OBJECT_WUNLOCK(object);
1210 * perform the I/O. NOTE!!! bp cannot be considered valid after
1211 * this point because we automatically release it on completion.
1212 * Instead, we look at the one page we are interested in which we
1213 * still hold a lock on even through the I/O completion.
1215 * The other pages in our m[] array are also released on completion,
1216 * so we cannot assume they are valid anymore either.
1218 * NOTE: b_blkno is destroyed by the call to swapdev_strategy
1221 swp_pager_strategy(bp);
1224 * wait for the page we want to complete. VPO_SWAPINPROG is always
1225 * cleared on completion. If an I/O error occurs, SWAPBLK_NONE
1226 * is set in the meta-data.
1228 VM_OBJECT_WLOCK(object);
1229 while ((mreq->oflags & VPO_SWAPINPROG) != 0) {
1230 mreq->oflags |= VPO_SWAPSLEEP;
1231 PCPU_INC(cnt.v_intrans);
1232 if (VM_OBJECT_SLEEP(object, &object->paging_in_progress, PSWP,
1233 "swread", hz * 20)) {
1235 "swap_pager: indefinite wait buffer: bufobj: %p, blkno: %jd, size: %ld\n",
1236 bp->b_bufobj, (intmax_t)bp->b_blkno, bp->b_bcount);
1241 * mreq is left busied after completion, but all the other pages
1242 * are freed. If we had an unrecoverable read error the page will
1245 if (mreq->valid != VM_PAGE_BITS_ALL) {
1246 return (VM_PAGER_ERROR);
1248 return (VM_PAGER_OK);
1252 * A final note: in a low swap situation, we cannot deallocate swap
1253 * and mark a page dirty here because the caller is likely to mark
1254 * the page clean when we return, causing the page to possibly revert
1255 * to all-zero's later.
1260 * swap_pager_getpages_async():
1262 * Right now this is emulation of asynchronous operation on top of
1263 * swap_pager_getpages().
1266 swap_pager_getpages_async(vm_object_t object, vm_page_t *m, int count,
1267 int reqpage, pgo_getpages_iodone_t iodone, void *arg)
1271 r = swap_pager_getpages(object, m, count, reqpage);
1272 VM_OBJECT_WUNLOCK(object);
1277 case VM_PAGER_ERROR:
1284 panic("unhandled swap_pager_getpages() error %d", r);
1286 (iodone)(arg, m, count, error);
1287 VM_OBJECT_WLOCK(object);
1293 * swap_pager_putpages:
1295 * Assign swap (if necessary) and initiate I/O on the specified pages.
1297 * We support both OBJT_DEFAULT and OBJT_SWAP objects. DEFAULT objects
1298 * are automatically converted to SWAP objects.
1300 * In a low memory situation we may block in VOP_STRATEGY(), but the new
1301 * vm_page reservation system coupled with properly written VFS devices
1302 * should ensure that no low-memory deadlock occurs. This is an area
1305 * The parent has N vm_object_pip_add() references prior to
1306 * calling us and will remove references for rtvals[] that are
1307 * not set to VM_PAGER_PEND. We need to remove the rest on I/O
1310 * The parent has soft-busy'd the pages it passes us and will unbusy
1311 * those whos rtvals[] entry is not set to VM_PAGER_PEND on return.
1312 * We need to unbusy the rest on I/O completion.
1315 swap_pager_putpages(vm_object_t object, vm_page_t *m, int count,
1316 int flags, int *rtvals)
1321 if (count && m[0]->object != object) {
1322 panic("swap_pager_putpages: object mismatch %p/%p",
1331 * Turn object into OBJT_SWAP
1332 * check for bogus sysops
1333 * force sync if not pageout process
1335 if (object->type != OBJT_SWAP)
1336 swp_pager_meta_build(object, 0, SWAPBLK_NONE);
1337 VM_OBJECT_WUNLOCK(object);
1340 if (curproc != pageproc)
1343 sync = (flags & VM_PAGER_PUT_SYNC) != 0;
1348 * Assign swap blocks and issue I/O. We reallocate swap on the fly.
1349 * The page is left dirty until the pageout operation completes
1352 for (i = 0; i < count; i += n) {
1358 * Maximum I/O size is limited by a number of factors.
1360 n = min(BLIST_MAX_ALLOC, count - i);
1361 n = min(n, nsw_cluster_max);
1364 * Get biggest block of swap we can. If we fail, fall
1365 * back and try to allocate a smaller block. Don't go
1366 * overboard trying to allocate space if it would overly
1370 (blk = swp_pager_getswapspace(n)) == SWAPBLK_NONE &&
1375 if (blk == SWAPBLK_NONE) {
1376 for (j = 0; j < n; ++j)
1377 rtvals[i+j] = VM_PAGER_FAIL;
1382 * All I/O parameters have been satisfied, build the I/O
1383 * request and assign the swap space.
1386 bp = getpbuf(&nsw_wcount_sync);
1388 bp = getpbuf(&nsw_wcount_async);
1389 bp->b_flags = B_ASYNC;
1391 bp->b_flags |= B_PAGING;
1392 bp->b_iocmd = BIO_WRITE;
1394 bp->b_rcred = crhold(thread0.td_ucred);
1395 bp->b_wcred = crhold(thread0.td_ucred);
1396 bp->b_bcount = PAGE_SIZE * n;
1397 bp->b_bufsize = PAGE_SIZE * n;
1400 VM_OBJECT_WLOCK(object);
1401 for (j = 0; j < n; ++j) {
1402 vm_page_t mreq = m[i+j];
1404 swp_pager_meta_build(
1409 vm_page_dirty(mreq);
1410 rtvals[i+j] = VM_PAGER_OK;
1412 mreq->oflags |= VPO_SWAPINPROG;
1413 bp->b_pages[j] = mreq;
1415 VM_OBJECT_WUNLOCK(object);
1418 * Must set dirty range for NFS to work.
1421 bp->b_dirtyend = bp->b_bcount;
1423 PCPU_INC(cnt.v_swapout);
1424 PCPU_ADD(cnt.v_swappgsout, bp->b_npages);
1429 * NOTE: b_blkno is destroyed by the call to swapdev_strategy
1431 if (sync == FALSE) {
1432 bp->b_iodone = swp_pager_async_iodone;
1434 swp_pager_strategy(bp);
1436 for (j = 0; j < n; ++j)
1437 rtvals[i+j] = VM_PAGER_PEND;
1438 /* restart outter loop */
1445 * NOTE: b_blkno is destroyed by the call to swapdev_strategy
1447 bp->b_iodone = bdone;
1448 swp_pager_strategy(bp);
1451 * Wait for the sync I/O to complete, then update rtvals.
1452 * We just set the rtvals[] to VM_PAGER_PEND so we can call
1453 * our async completion routine at the end, thus avoiding a
1456 bwait(bp, PVM, "swwrt");
1457 for (j = 0; j < n; ++j)
1458 rtvals[i+j] = VM_PAGER_PEND;
1460 * Now that we are through with the bp, we can call the
1461 * normal async completion, which frees everything up.
1463 swp_pager_async_iodone(bp);
1465 VM_OBJECT_WLOCK(object);
1469 * swp_pager_async_iodone:
1471 * Completion routine for asynchronous reads and writes from/to swap.
1472 * Also called manually by synchronous code to finish up a bp.
1474 * This routine may not sleep.
1477 swp_pager_async_iodone(struct buf *bp)
1480 vm_object_t object = NULL;
1485 if (bp->b_ioflags & BIO_ERROR) {
1487 "swap_pager: I/O error - %s failed; blkno %ld,"
1488 "size %ld, error %d\n",
1489 ((bp->b_iocmd == BIO_READ) ? "pagein" : "pageout"),
1497 * remove the mapping for kernel virtual
1499 if ((bp->b_flags & B_UNMAPPED) != 0) {
1500 bp->b_data = bp->b_kvaalloc;
1501 bp->b_kvabase = bp->b_kvaalloc;
1502 bp->b_flags &= ~B_UNMAPPED;
1504 pmap_qremove((vm_offset_t)bp->b_data, bp->b_npages);
1507 object = bp->b_pages[0]->object;
1508 VM_OBJECT_WLOCK(object);
1512 * cleanup pages. If an error occurs writing to swap, we are in
1513 * very serious trouble. If it happens to be a disk error, though,
1514 * we may be able to recover by reassigning the swap later on. So
1515 * in this case we remove the m->swapblk assignment for the page
1516 * but do not free it in the rlist. The errornous block(s) are thus
1517 * never reallocated as swap. Redirty the page and continue.
1519 for (i = 0; i < bp->b_npages; ++i) {
1520 vm_page_t m = bp->b_pages[i];
1522 m->oflags &= ~VPO_SWAPINPROG;
1523 if (m->oflags & VPO_SWAPSLEEP) {
1524 m->oflags &= ~VPO_SWAPSLEEP;
1525 wakeup(&object->paging_in_progress);
1528 if (bp->b_ioflags & BIO_ERROR) {
1530 * If an error occurs I'd love to throw the swapblk
1531 * away without freeing it back to swapspace, so it
1532 * can never be used again. But I can't from an
1535 if (bp->b_iocmd == BIO_READ) {
1537 * When reading, reqpage needs to stay
1538 * locked for the parent, but all other
1539 * pages can be freed. We still want to
1540 * wakeup the parent waiting on the page,
1541 * though. ( also: pg_reqpage can be -1 and
1542 * not match anything ).
1544 * We have to wake specifically requested pages
1545 * up too because we cleared VPO_SWAPINPROG and
1546 * someone may be waiting for that.
1548 * NOTE: for reads, m->dirty will probably
1549 * be overridden by the original caller of
1550 * getpages so don't play cute tricks here.
1553 if (i != bp->b_pager.pg_reqpage)
1554 swp_pager_free_nrpage(m);
1561 * If i == bp->b_pager.pg_reqpage, do not wake
1562 * the page up. The caller needs to.
1566 * If a write error occurs, reactivate page
1567 * so it doesn't clog the inactive list,
1568 * then finish the I/O.
1572 vm_page_activate(m);
1576 } else if (bp->b_iocmd == BIO_READ) {
1578 * NOTE: for reads, m->dirty will probably be
1579 * overridden by the original caller of getpages so
1580 * we cannot set them in order to free the underlying
1581 * swap in a low-swap situation. I don't think we'd
1582 * want to do that anyway, but it was an optimization
1583 * that existed in the old swapper for a time before
1584 * it got ripped out due to precisely this problem.
1586 * If not the requested page then deactivate it.
1588 * Note that the requested page, reqpage, is left
1589 * busied, but we still have to wake it up. The
1590 * other pages are released (unbusied) by
1591 * vm_page_xunbusy().
1593 KASSERT(!pmap_page_is_mapped(m),
1594 ("swp_pager_async_iodone: page %p is mapped", m));
1595 m->valid = VM_PAGE_BITS_ALL;
1596 KASSERT(m->dirty == 0,
1597 ("swp_pager_async_iodone: page %p is dirty", m));
1600 * We have to wake specifically requested pages
1601 * up too because we cleared VPO_SWAPINPROG and
1602 * could be waiting for it in getpages. However,
1603 * be sure to not unbusy getpages specifically
1604 * requested page - getpages expects it to be
1607 if (i != bp->b_pager.pg_reqpage) {
1609 vm_page_deactivate(m);
1619 * For write success, clear the dirty
1620 * status, then finish the I/O ( which decrements the
1621 * busy count and possibly wakes waiter's up ).
1623 KASSERT(!pmap_page_is_write_mapped(m),
1624 ("swp_pager_async_iodone: page %p is not write"
1628 if (vm_page_count_severe()) {
1630 vm_page_try_to_cache(m);
1637 * adjust pip. NOTE: the original parent may still have its own
1638 * pip refs on the object.
1640 if (object != NULL) {
1641 vm_object_pip_wakeupn(object, bp->b_npages);
1642 VM_OBJECT_WUNLOCK(object);
1646 * swapdev_strategy() manually sets b_vp and b_bufobj before calling
1647 * bstrategy(). Set them back to NULL now we're done with it, or we'll
1648 * trigger a KASSERT in relpbuf().
1652 bp->b_bufobj = NULL;
1655 * release the physical I/O buffer
1659 ((bp->b_iocmd == BIO_READ) ? &nsw_rcount :
1660 ((bp->b_flags & B_ASYNC) ?
1669 * swap_pager_isswapped:
1671 * Return 1 if at least one page in the given object is paged
1672 * out to the given swap device.
1674 * This routine may not sleep.
1677 swap_pager_isswapped(vm_object_t object, struct swdevt *sp)
1683 VM_OBJECT_ASSERT_WLOCKED(object);
1684 if (object->type != OBJT_SWAP)
1687 mtx_lock(&swhash_mtx);
1688 for (bcount = 0; bcount < object->un_pager.swp.swp_bcount; bcount++) {
1689 struct swblock *swap;
1691 if ((swap = *swp_pager_hash(object, index)) != NULL) {
1692 for (i = 0; i < SWAP_META_PAGES; ++i) {
1693 if (swp_pager_isondev(swap->swb_pages[i], sp)) {
1694 mtx_unlock(&swhash_mtx);
1699 index += SWAP_META_PAGES;
1701 mtx_unlock(&swhash_mtx);
1706 * SWP_PAGER_FORCE_PAGEIN() - force a swap block to be paged in
1708 * This routine dissociates the page at the given index within a
1709 * swap block from its backing store, paging it in if necessary.
1710 * If the page is paged in, it is placed in the inactive queue,
1711 * since it had its backing store ripped out from under it.
1712 * We also attempt to swap in all other pages in the swap block,
1713 * we only guarantee that the one at the specified index is
1716 * XXX - The code to page the whole block in doesn't work, so we
1717 * revert to the one-by-one behavior for now. Sigh.
1720 swp_pager_force_pagein(vm_object_t object, vm_pindex_t pindex)
1724 vm_object_pip_add(object, 1);
1725 m = vm_page_grab(object, pindex, VM_ALLOC_NORMAL);
1726 if (m->valid == VM_PAGE_BITS_ALL) {
1727 vm_object_pip_wakeup(object);
1730 vm_page_activate(m);
1733 vm_pager_page_unswapped(m);
1737 if (swap_pager_getpages(object, &m, 1, 0) != VM_PAGER_OK)
1738 panic("swap_pager_force_pagein: read from swap failed");/*XXX*/
1739 vm_object_pip_wakeup(object);
1742 vm_page_deactivate(m);
1745 vm_pager_page_unswapped(m);
1749 * swap_pager_swapoff:
1751 * Page in all of the pages that have been paged out to the
1752 * given device. The corresponding blocks in the bitmap must be
1753 * marked as allocated and the device must be flagged SW_CLOSING.
1754 * There may be no processes swapped out to the device.
1756 * This routine may block.
1759 swap_pager_swapoff(struct swdevt *sp)
1761 struct swblock *swap;
1768 mtx_lock(&swhash_mtx);
1769 for (i = 0; i <= swhash_mask; i++) { /* '<=' is correct here */
1771 for (swap = swhash[i]; swap != NULL; swap = swap->swb_hnext) {
1772 vm_object_t object = swap->swb_object;
1773 vm_pindex_t pindex = swap->swb_index;
1774 for (j = 0; j < SWAP_META_PAGES; ++j) {
1775 if (swp_pager_isondev(swap->swb_pages[j], sp)) {
1776 /* avoid deadlock */
1777 if (!VM_OBJECT_TRYWLOCK(object)) {
1780 mtx_unlock(&swhash_mtx);
1781 swp_pager_force_pagein(object,
1783 VM_OBJECT_WUNLOCK(object);
1784 mtx_lock(&swhash_mtx);
1791 mtx_unlock(&swhash_mtx);
1794 * Objects may be locked or paging to the device being
1795 * removed, so we will miss their pages and need to
1796 * make another pass. We have marked this device as
1797 * SW_CLOSING, so the activity should finish soon.
1800 if (retries > 100) {
1801 panic("swapoff: failed to locate %d swap blocks",
1804 pause("swpoff", hz / 20);
1809 /************************************************************************
1811 ************************************************************************
1813 * These routines manipulate the swap metadata stored in the
1816 * Swap metadata is implemented with a global hash and not directly
1817 * linked into the object. Instead the object simply contains
1818 * appropriate tracking counters.
1822 * SWP_PAGER_META_BUILD() - add swap block to swap meta data for object
1824 * We first convert the object to a swap object if it is a default
1827 * The specified swapblk is added to the object's swap metadata. If
1828 * the swapblk is not valid, it is freed instead. Any previously
1829 * assigned swapblk is freed.
1832 swp_pager_meta_build(vm_object_t object, vm_pindex_t pindex, daddr_t swapblk)
1834 static volatile int exhausted;
1835 struct swblock *swap;
1836 struct swblock **pswap;
1839 VM_OBJECT_ASSERT_WLOCKED(object);
1841 * Convert default object to swap object if necessary
1843 if (object->type != OBJT_SWAP) {
1844 object->type = OBJT_SWAP;
1845 object->un_pager.swp.swp_bcount = 0;
1847 if (object->handle != NULL) {
1848 mtx_lock(&sw_alloc_mtx);
1850 NOBJLIST(object->handle),
1854 mtx_unlock(&sw_alloc_mtx);
1859 * Locate hash entry. If not found create, but if we aren't adding
1860 * anything just return. If we run out of space in the map we wait
1861 * and, since the hash table may have changed, retry.
1864 mtx_lock(&swhash_mtx);
1865 pswap = swp_pager_hash(object, pindex);
1867 if ((swap = *pswap) == NULL) {
1870 if (swapblk == SWAPBLK_NONE)
1873 swap = *pswap = uma_zalloc(swap_zone, M_NOWAIT |
1874 (curproc == pageproc ? M_USE_RESERVE : 0));
1876 mtx_unlock(&swhash_mtx);
1877 VM_OBJECT_WUNLOCK(object);
1878 if (uma_zone_exhausted(swap_zone)) {
1879 if (atomic_cmpset_int(&exhausted, 0, 1))
1880 printf("swap zone exhausted, "
1881 "increase kern.maxswzone\n");
1882 vm_pageout_oom(VM_OOM_SWAPZ);
1883 pause("swzonex", 10);
1886 VM_OBJECT_WLOCK(object);
1890 if (atomic_cmpset_int(&exhausted, 1, 0))
1891 printf("swap zone ok\n");
1893 swap->swb_hnext = NULL;
1894 swap->swb_object = object;
1895 swap->swb_index = pindex & ~(vm_pindex_t)SWAP_META_MASK;
1896 swap->swb_count = 0;
1898 ++object->un_pager.swp.swp_bcount;
1900 for (i = 0; i < SWAP_META_PAGES; ++i)
1901 swap->swb_pages[i] = SWAPBLK_NONE;
1905 * Delete prior contents of metadata
1907 idx = pindex & SWAP_META_MASK;
1909 if (swap->swb_pages[idx] != SWAPBLK_NONE) {
1910 swp_pager_freeswapspace(swap->swb_pages[idx], 1);
1915 * Enter block into metadata
1917 swap->swb_pages[idx] = swapblk;
1918 if (swapblk != SWAPBLK_NONE)
1921 mtx_unlock(&swhash_mtx);
1925 * SWP_PAGER_META_FREE() - free a range of blocks in the object's swap metadata
1927 * The requested range of blocks is freed, with any associated swap
1928 * returned to the swap bitmap.
1930 * This routine will free swap metadata structures as they are cleaned
1931 * out. This routine does *NOT* operate on swap metadata associated
1932 * with resident pages.
1935 swp_pager_meta_free(vm_object_t object, vm_pindex_t index, daddr_t count)
1938 VM_OBJECT_ASSERT_LOCKED(object);
1939 if (object->type != OBJT_SWAP)
1943 struct swblock **pswap;
1944 struct swblock *swap;
1946 mtx_lock(&swhash_mtx);
1947 pswap = swp_pager_hash(object, index);
1949 if ((swap = *pswap) != NULL) {
1950 daddr_t v = swap->swb_pages[index & SWAP_META_MASK];
1952 if (v != SWAPBLK_NONE) {
1953 swp_pager_freeswapspace(v, 1);
1954 swap->swb_pages[index & SWAP_META_MASK] =
1956 if (--swap->swb_count == 0) {
1957 *pswap = swap->swb_hnext;
1958 uma_zfree(swap_zone, swap);
1959 --object->un_pager.swp.swp_bcount;
1965 int n = SWAP_META_PAGES - (index & SWAP_META_MASK);
1969 mtx_unlock(&swhash_mtx);
1974 * SWP_PAGER_META_FREE_ALL() - destroy all swap metadata associated with object
1976 * This routine locates and destroys all swap metadata associated with
1980 swp_pager_meta_free_all(vm_object_t object)
1984 VM_OBJECT_ASSERT_WLOCKED(object);
1985 if (object->type != OBJT_SWAP)
1988 while (object->un_pager.swp.swp_bcount) {
1989 struct swblock **pswap;
1990 struct swblock *swap;
1992 mtx_lock(&swhash_mtx);
1993 pswap = swp_pager_hash(object, index);
1994 if ((swap = *pswap) != NULL) {
1997 for (i = 0; i < SWAP_META_PAGES; ++i) {
1998 daddr_t v = swap->swb_pages[i];
1999 if (v != SWAPBLK_NONE) {
2001 swp_pager_freeswapspace(v, 1);
2004 if (swap->swb_count != 0)
2005 panic("swap_pager_meta_free_all: swb_count != 0");
2006 *pswap = swap->swb_hnext;
2007 uma_zfree(swap_zone, swap);
2008 --object->un_pager.swp.swp_bcount;
2010 mtx_unlock(&swhash_mtx);
2011 index += SWAP_META_PAGES;
2016 * SWP_PAGER_METACTL() - misc control of swap and vm_page_t meta data.
2018 * This routine is capable of looking up, popping, or freeing
2019 * swapblk assignments in the swap meta data or in the vm_page_t.
2020 * The routine typically returns the swapblk being looked-up, or popped,
2021 * or SWAPBLK_NONE if the block was freed, or SWAPBLK_NONE if the block
2022 * was invalid. This routine will automatically free any invalid
2023 * meta-data swapblks.
2025 * It is not possible to store invalid swapblks in the swap meta data
2026 * (other then a literal 'SWAPBLK_NONE'), so we don't bother checking.
2028 * When acting on a busy resident page and paging is in progress, we
2029 * have to wait until paging is complete but otherwise can act on the
2032 * SWM_FREE remove and free swap block from metadata
2033 * SWM_POP remove from meta data but do not free.. pop it out
2036 swp_pager_meta_ctl(vm_object_t object, vm_pindex_t pindex, int flags)
2038 struct swblock **pswap;
2039 struct swblock *swap;
2043 VM_OBJECT_ASSERT_LOCKED(object);
2045 * The meta data only exists of the object is OBJT_SWAP
2046 * and even then might not be allocated yet.
2048 if (object->type != OBJT_SWAP)
2049 return (SWAPBLK_NONE);
2052 mtx_lock(&swhash_mtx);
2053 pswap = swp_pager_hash(object, pindex);
2055 if ((swap = *pswap) != NULL) {
2056 idx = pindex & SWAP_META_MASK;
2057 r1 = swap->swb_pages[idx];
2059 if (r1 != SWAPBLK_NONE) {
2060 if (flags & SWM_FREE) {
2061 swp_pager_freeswapspace(r1, 1);
2064 if (flags & (SWM_FREE|SWM_POP)) {
2065 swap->swb_pages[idx] = SWAPBLK_NONE;
2066 if (--swap->swb_count == 0) {
2067 *pswap = swap->swb_hnext;
2068 uma_zfree(swap_zone, swap);
2069 --object->un_pager.swp.swp_bcount;
2074 mtx_unlock(&swhash_mtx);
2079 * System call swapon(name) enables swapping on device name,
2080 * which must be in the swdevsw. Return EBUSY
2081 * if already swapping on this device.
2083 #ifndef _SYS_SYSPROTO_H_
2084 struct swapon_args {
2094 sys_swapon(struct thread *td, struct swapon_args *uap)
2098 struct nameidata nd;
2101 error = priv_check(td, PRIV_SWAPON);
2106 while (swdev_syscall_active)
2107 tsleep(&swdev_syscall_active, PUSER - 1, "swpon", 0);
2108 swdev_syscall_active = 1;
2111 * Swap metadata may not fit in the KVM if we have physical
2114 if (swap_zone == NULL) {
2119 NDINIT(&nd, LOOKUP, ISOPEN | FOLLOW | AUDITVNODE1, UIO_USERSPACE,
2125 NDFREE(&nd, NDF_ONLY_PNBUF);
2128 if (vn_isdisk(vp, &error)) {
2129 error = swapongeom(td, vp);
2130 } else if (vp->v_type == VREG &&
2131 (vp->v_mount->mnt_vfc->vfc_flags & VFCF_NETWORK) != 0 &&
2132 (error = VOP_GETATTR(vp, &attr, td->td_ucred)) == 0) {
2134 * Allow direct swapping to NFS regular files in the same
2135 * way that nfs_mountroot() sets up diskless swapping.
2137 error = swaponvp(td, vp, attr.va_size / DEV_BSIZE);
2143 swdev_syscall_active = 0;
2144 wakeup_one(&swdev_syscall_active);
2150 * Check that the total amount of swap currently configured does not
2151 * exceed half the theoretical maximum. If it does, print a warning
2152 * message and return -1; otherwise, return 0.
2155 swapon_check_swzone(unsigned long npages)
2157 unsigned long maxpages;
2159 /* absolute maximum we can handle assuming 100% efficiency */
2160 maxpages = uma_zone_get_max(swap_zone) * SWAP_META_PAGES;
2162 /* recommend using no more than half that amount */
2163 if (npages > maxpages / 2) {
2164 printf("warning: total configured swap (%lu pages) "
2165 "exceeds maximum recommended amount (%lu pages).\n",
2166 npages, maxpages / 2);
2167 printf("warning: increase kern.maxswzone "
2168 "or reduce amount of swap.\n");
2175 swaponsomething(struct vnode *vp, void *id, u_long nblks,
2176 sw_strategy_t *strategy, sw_close_t *close, dev_t dev, int flags)
2178 struct swdevt *sp, *tsp;
2183 * nblks is in DEV_BSIZE'd chunks, convert to PAGE_SIZE'd chunks.
2184 * First chop nblks off to page-align it, then convert.
2186 * sw->sw_nblks is in page-sized chunks now too.
2188 nblks &= ~(ctodb(1) - 1);
2189 nblks = dbtoc(nblks);
2192 * If we go beyond this, we get overflows in the radix
2195 mblocks = 0x40000000 / BLIST_META_RADIX;
2196 if (nblks > mblocks) {
2198 "WARNING: reducing swap size to maximum of %luMB per unit\n",
2199 mblocks / 1024 / 1024 * PAGE_SIZE);
2203 sp = malloc(sizeof *sp, M_VMPGDATA, M_WAITOK | M_ZERO);
2208 sp->sw_nblks = nblks;
2210 sp->sw_strategy = strategy;
2211 sp->sw_close = close;
2212 sp->sw_flags = flags;
2214 sp->sw_blist = blist_create(nblks, M_WAITOK);
2216 * Do not free the first two block in order to avoid overwriting
2217 * any bsd label at the front of the partition
2219 blist_free(sp->sw_blist, 2, nblks - 2);
2222 mtx_lock(&sw_dev_mtx);
2223 TAILQ_FOREACH(tsp, &swtailq, sw_list) {
2224 if (tsp->sw_end >= dvbase) {
2226 * We put one uncovered page between the devices
2227 * in order to definitively prevent any cross-device
2230 dvbase = tsp->sw_end + 1;
2233 sp->sw_first = dvbase;
2234 sp->sw_end = dvbase + nblks;
2235 TAILQ_INSERT_TAIL(&swtailq, sp, sw_list);
2237 swap_pager_avail += nblks;
2238 swap_total += (vm_ooffset_t)nblks * PAGE_SIZE;
2239 swapon_check_swzone(swap_total / PAGE_SIZE);
2241 mtx_unlock(&sw_dev_mtx);
2245 * SYSCALL: swapoff(devname)
2247 * Disable swapping on the given device.
2249 * XXX: Badly designed system call: it should use a device index
2250 * rather than filename as specification. We keep sw_vp around
2251 * only to make this work.
2253 #ifndef _SYS_SYSPROTO_H_
2254 struct swapoff_args {
2264 sys_swapoff(struct thread *td, struct swapoff_args *uap)
2267 struct nameidata nd;
2271 error = priv_check(td, PRIV_SWAPOFF);
2276 while (swdev_syscall_active)
2277 tsleep(&swdev_syscall_active, PUSER - 1, "swpoff", 0);
2278 swdev_syscall_active = 1;
2280 NDINIT(&nd, LOOKUP, FOLLOW | AUDITVNODE1, UIO_USERSPACE, uap->name,
2285 NDFREE(&nd, NDF_ONLY_PNBUF);
2288 mtx_lock(&sw_dev_mtx);
2289 TAILQ_FOREACH(sp, &swtailq, sw_list) {
2290 if (sp->sw_vp == vp)
2293 mtx_unlock(&sw_dev_mtx);
2298 error = swapoff_one(sp, td->td_ucred);
2300 swdev_syscall_active = 0;
2301 wakeup_one(&swdev_syscall_active);
2307 swapoff_one(struct swdevt *sp, struct ucred *cred)
2309 u_long nblks, dvbase;
2314 mtx_assert(&Giant, MA_OWNED);
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 + vm_cnt.v_cache_count + swap_pager_avail <
2331 nblks + nswap_lowat) {
2336 * Prevent further allocations on this device.
2338 mtx_lock(&sw_dev_mtx);
2339 sp->sw_flags |= SW_CLOSING;
2340 for (dvbase = 0; dvbase < sp->sw_end; dvbase += dmmax) {
2341 swap_pager_avail -= blist_fill(sp->sw_blist,
2344 swap_total -= (vm_ooffset_t)nblks * PAGE_SIZE;
2345 mtx_unlock(&sw_dev_mtx);
2348 * Page in the contents of the device and close it.
2350 swap_pager_swapoff(sp);
2352 sp->sw_close(curthread, sp);
2354 mtx_lock(&sw_dev_mtx);
2355 TAILQ_REMOVE(&swtailq, sp, sw_list);
2357 if (nswapdev == 0) {
2358 swap_pager_full = 2;
2359 swap_pager_almost_full = 1;
2363 mtx_unlock(&sw_dev_mtx);
2364 blist_destroy(sp->sw_blist);
2365 free(sp, M_VMPGDATA);
2372 struct swdevt *sp, *spt;
2373 const char *devname;
2377 while (swdev_syscall_active)
2378 tsleep(&swdev_syscall_active, PUSER - 1, "swpoff", 0);
2379 swdev_syscall_active = 1;
2381 mtx_lock(&sw_dev_mtx);
2382 TAILQ_FOREACH_SAFE(sp, &swtailq, sw_list, spt) {
2383 mtx_unlock(&sw_dev_mtx);
2384 if (vn_isdisk(sp->sw_vp, NULL))
2385 devname = devtoname(sp->sw_vp->v_rdev);
2388 error = swapoff_one(sp, thread0.td_ucred);
2390 printf("Cannot remove swap device %s (error=%d), "
2391 "skipping.\n", devname, error);
2392 } else if (bootverbose) {
2393 printf("Swap device %s removed.\n", devname);
2395 mtx_lock(&sw_dev_mtx);
2397 mtx_unlock(&sw_dev_mtx);
2399 swdev_syscall_active = 0;
2400 wakeup_one(&swdev_syscall_active);
2405 swap_pager_status(int *total, int *used)
2411 mtx_lock(&sw_dev_mtx);
2412 TAILQ_FOREACH(sp, &swtailq, sw_list) {
2413 *total += sp->sw_nblks;
2414 *used += sp->sw_used;
2416 mtx_unlock(&sw_dev_mtx);
2420 swap_dev_info(int name, struct xswdev *xs, char *devname, size_t len)
2423 const char *tmp_devname;
2428 mtx_lock(&sw_dev_mtx);
2429 TAILQ_FOREACH(sp, &swtailq, sw_list) {
2434 xs->xsw_version = XSWDEV_VERSION;
2435 xs->xsw_dev = sp->sw_dev;
2436 xs->xsw_flags = sp->sw_flags;
2437 xs->xsw_nblks = sp->sw_nblks;
2438 xs->xsw_used = sp->sw_used;
2439 if (devname != NULL) {
2440 if (vn_isdisk(sp->sw_vp, NULL))
2441 tmp_devname = devtoname(sp->sw_vp->v_rdev);
2443 tmp_devname = "[file]";
2444 strncpy(devname, tmp_devname, len);
2449 mtx_unlock(&sw_dev_mtx);
2454 sysctl_vm_swap_info(SYSCTL_HANDLER_ARGS)
2459 if (arg2 != 1) /* name length */
2461 error = swap_dev_info(*(int *)arg1, &xs, NULL, 0);
2464 error = SYSCTL_OUT(req, &xs, sizeof(xs));
2468 SYSCTL_INT(_vm, OID_AUTO, nswapdev, CTLFLAG_RD, &nswapdev, 0,
2469 "Number of swap devices");
2470 SYSCTL_NODE(_vm, OID_AUTO, swap_info, CTLFLAG_RD, sysctl_vm_swap_info,
2471 "Swap statistics by device");
2474 * vmspace_swap_count() - count the approximate swap usage in pages for a
2477 * The map must be locked.
2479 * Swap usage is determined by taking the proportional swap used by
2480 * VM objects backing the VM map. To make up for fractional losses,
2481 * if the VM object has any swap use at all the associated map entries
2482 * count for at least 1 swap page.
2485 vmspace_swap_count(struct vmspace *vmspace)
2492 map = &vmspace->vm_map;
2495 for (cur = map->header.next; cur != &map->header; cur = cur->next) {
2496 if ((cur->eflags & MAP_ENTRY_IS_SUB_MAP) == 0 &&
2497 (object = cur->object.vm_object) != NULL) {
2498 VM_OBJECT_WLOCK(object);
2499 if (object->type == OBJT_SWAP &&
2500 object->un_pager.swp.swp_bcount != 0) {
2501 n = (cur->end - cur->start) / PAGE_SIZE;
2502 count += object->un_pager.swp.swp_bcount *
2503 SWAP_META_PAGES * n / object->size + 1;
2505 VM_OBJECT_WUNLOCK(object);
2514 * Swapping onto disk devices.
2518 static g_orphan_t swapgeom_orphan;
2520 static struct g_class g_swap_class = {
2522 .version = G_VERSION,
2523 .orphan = swapgeom_orphan,
2526 DECLARE_GEOM_CLASS(g_swap_class, g_class);
2530 swapgeom_close_ev(void *arg, int flags)
2532 struct g_consumer *cp;
2535 g_access(cp, -1, -1, 0);
2537 g_destroy_consumer(cp);
2541 swapgeom_done(struct bio *bp2)
2545 struct g_consumer *cp;
2547 bp = bp2->bio_caller2;
2549 bp->b_ioflags = bp2->bio_flags;
2551 bp->b_ioflags |= BIO_ERROR;
2552 bp->b_resid = bp->b_bcount - bp2->bio_completed;
2553 bp->b_error = bp2->bio_error;
2555 mtx_lock(&sw_dev_mtx);
2556 if ((--cp->index) == 0 && cp->private) {
2557 if (g_post_event(swapgeom_close_ev, cp, M_NOWAIT, NULL) == 0) {
2558 sp = bp2->bio_caller1;
2562 mtx_unlock(&sw_dev_mtx);
2567 swapgeom_strategy(struct buf *bp, struct swdevt *sp)
2570 struct g_consumer *cp;
2572 mtx_lock(&sw_dev_mtx);
2575 mtx_unlock(&sw_dev_mtx);
2576 bp->b_error = ENXIO;
2577 bp->b_ioflags |= BIO_ERROR;
2582 mtx_unlock(&sw_dev_mtx);
2583 if (bp->b_iocmd == BIO_WRITE)
2586 bio = g_alloc_bio();
2588 bp->b_error = ENOMEM;
2589 bp->b_ioflags |= BIO_ERROR;
2594 bio->bio_caller1 = sp;
2595 bio->bio_caller2 = bp;
2596 bio->bio_cmd = bp->b_iocmd;
2597 bio->bio_offset = (bp->b_blkno - sp->sw_first) * PAGE_SIZE;
2598 bio->bio_length = bp->b_bcount;
2599 bio->bio_done = swapgeom_done;
2600 if ((bp->b_flags & B_UNMAPPED) != 0) {
2601 bio->bio_ma = bp->b_pages;
2602 bio->bio_data = unmapped_buf;
2603 bio->bio_ma_offset = (vm_offset_t)bp->b_offset & PAGE_MASK;
2604 bio->bio_ma_n = bp->b_npages;
2605 bio->bio_flags |= BIO_UNMAPPED;
2607 bio->bio_data = bp->b_data;
2610 g_io_request(bio, cp);
2615 swapgeom_orphan(struct g_consumer *cp)
2620 mtx_lock(&sw_dev_mtx);
2621 TAILQ_FOREACH(sp, &swtailq, sw_list) {
2622 if (sp->sw_id == cp) {
2623 sp->sw_flags |= SW_CLOSING;
2627 cp->private = (void *)(uintptr_t)1;
2628 destroy = ((sp != NULL) && (cp->index == 0));
2631 mtx_unlock(&sw_dev_mtx);
2633 swapgeom_close_ev(cp, 0);
2637 swapgeom_close(struct thread *td, struct swdevt *sw)
2639 struct g_consumer *cp;
2641 mtx_lock(&sw_dev_mtx);
2644 mtx_unlock(&sw_dev_mtx);
2645 /* XXX: direct call when Giant untangled */
2647 g_waitfor_event(swapgeom_close_ev, cp, M_WAITOK, NULL);
2658 swapongeom_ev(void *arg, int flags)
2661 struct g_provider *pp;
2662 struct g_consumer *cp;
2663 static struct g_geom *gp;
2670 pp = g_dev_getprovider(swh->dev);
2672 swh->error = ENODEV;
2675 mtx_lock(&sw_dev_mtx);
2676 TAILQ_FOREACH(sp, &swtailq, sw_list) {
2678 if (cp != NULL && cp->provider == pp) {
2679 mtx_unlock(&sw_dev_mtx);
2684 mtx_unlock(&sw_dev_mtx);
2686 gp = g_new_geomf(&g_swap_class, "swap");
2687 cp = g_new_consumer(gp);
2688 cp->index = 0; /* Number of active I/Os. */
2689 cp->private = NULL; /* Orphanization flag */
2692 * XXX: Everytime you think you can improve the margin for
2693 * footshooting, somebody depends on the ability to do so:
2694 * savecore(8) wants to write to our swapdev so we cannot
2695 * set an exclusive count :-(
2697 error = g_access(cp, 1, 1, 0);
2700 g_destroy_consumer(cp);
2704 nblks = pp->mediasize / DEV_BSIZE;
2705 swaponsomething(swh->vp, cp, nblks, swapgeom_strategy,
2706 swapgeom_close, dev2udev(swh->dev),
2707 (pp->flags & G_PF_ACCEPT_UNMAPPED) != 0 ? SW_UNMAPPED : 0);
2712 swapongeom(struct thread *td, struct vnode *vp)
2717 vn_lock(vp, LK_EXCLUSIVE | LK_RETRY);
2719 swh.dev = vp->v_rdev;
2722 /* XXX: direct call when Giant untangled */
2723 error = g_waitfor_event(swapongeom_ev, &swh, M_WAITOK, NULL);
2733 * This is used mainly for network filesystem (read: probably only tested
2734 * with NFS) swapfiles.
2739 swapdev_strategy(struct buf *bp, struct swdevt *sp)
2743 bp->b_blkno = ctodb(bp->b_blkno - sp->sw_first);
2747 if (bp->b_iocmd == BIO_WRITE) {
2749 bufobj_wdrop(bp->b_bufobj);
2750 bufobj_wref(&vp2->v_bufobj);
2752 if (bp->b_bufobj != &vp2->v_bufobj)
2753 bp->b_bufobj = &vp2->v_bufobj;
2755 bp->b_iooffset = dbtob(bp->b_blkno);
2761 swapdev_close(struct thread *td, struct swdevt *sp)
2764 VOP_CLOSE(sp->sw_vp, FREAD | FWRITE, td->td_ucred, td);
2770 swaponvp(struct thread *td, struct vnode *vp, u_long nblks)
2777 mtx_lock(&sw_dev_mtx);
2778 TAILQ_FOREACH(sp, &swtailq, sw_list) {
2779 if (sp->sw_id == vp) {
2780 mtx_unlock(&sw_dev_mtx);
2784 mtx_unlock(&sw_dev_mtx);
2786 (void) vn_lock(vp, LK_EXCLUSIVE | LK_RETRY);
2788 error = mac_system_check_swapon(td->td_ucred, vp);
2791 error = VOP_OPEN(vp, FREAD | FWRITE, td->td_ucred, td, NULL);
2792 (void) VOP_UNLOCK(vp, 0);
2796 swaponsomething(vp, vp, nblks, swapdev_strategy, swapdev_close,
2802 sysctl_swap_async_max(SYSCTL_HANDLER_ARGS)
2806 new = nsw_wcount_async_max;
2807 error = sysctl_handle_int(oidp, &new, 0, req);
2808 if (error != 0 || req->newptr == NULL)
2811 if (new > nswbuf / 2 || new < 1)
2814 mtx_lock(&pbuf_mtx);
2815 while (nsw_wcount_async_max != new) {
2817 * Adjust difference. If the current async count is too low,
2818 * we will need to sqeeze our update slowly in. Sleep with a
2819 * higher priority than getpbuf() to finish faster.
2821 n = new - nsw_wcount_async_max;
2822 if (nsw_wcount_async + n >= 0) {
2823 nsw_wcount_async += n;
2824 nsw_wcount_async_max += n;
2825 wakeup(&nsw_wcount_async);
2827 nsw_wcount_async_max -= nsw_wcount_async;
2828 nsw_wcount_async = 0;
2829 msleep(&nsw_wcount_async, &pbuf_mtx, PSWP,
2833 mtx_unlock(&pbuf_mtx);