4 * Copyright (c) 1998-2010 The DragonFly Project. All rights reserved.
6 * This code is derived from software contributed to The DragonFly Project
7 * by Matthew Dillon <dillon@backplane.com>
9 * Redistribution and use in source and binary forms, with or without
10 * modification, are permitted provided that the following conditions
13 * 1. Redistributions of source code must retain the above copyright
14 * notice, this list of conditions and the following disclaimer.
15 * 2. Redistributions in binary form must reproduce the above copyright
16 * notice, this list of conditions and the following disclaimer in
17 * the documentation and/or other materials provided with the
19 * 3. Neither the name of The DragonFly Project nor the names of its
20 * contributors may be used to endorse or promote products derived
21 * from this software without specific, prior written permission.
23 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
24 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
25 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
26 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
27 * COPYRIGHT HOLDERS OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
28 * INCIDENTAL, SPECIAL, EXEMPLARY OR CONSEQUENTIAL DAMAGES (INCLUDING,
29 * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
30 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
31 * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
32 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
33 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
36 * Copyright (c) 1994 John S. Dyson
37 * Copyright (c) 1990 University of Utah.
38 * Copyright (c) 1991, 1993
39 * The Regents of the University of California. All rights reserved.
41 * This code is derived from software contributed to Berkeley by
42 * the Systems Programming Group of the University of Utah Computer
45 * Redistribution and use in source and binary forms, with or without
46 * modification, are permitted provided that the following conditions
48 * 1. Redistributions of source code must retain the above copyright
49 * notice, this list of conditions and the following disclaimer.
50 * 2. Redistributions in binary form must reproduce the above copyright
51 * notice, this list of conditions and the following disclaimer in the
52 * documentation and/or other materials provided with the distribution.
53 * 3. Neither the name of the University nor the names of its contributors
54 * may be used to endorse or promote products derived from this software
55 * without specific prior written permission.
57 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
58 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
59 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
60 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
61 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
62 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
63 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
64 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
65 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
66 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
72 * Radix Bitmap 'blists'.
74 * - The new swapper uses the new radix bitmap code. This should scale
75 * to arbitrarily small or arbitrarily large swap spaces and an almost
76 * arbitrary degree of fragmentation.
80 * - on the fly reallocation of swap during putpages. The new system
81 * does not try to keep previously allocated swap blocks for dirty
84 * - on the fly deallocation of swap
86 * - No more garbage collection required. Unnecessarily allocated swap
87 * blocks only exist for dirty vm_page_t's now and these are already
88 * cycled (in a high-load system) by the pager. We also do on-the-fly
89 * removal of invalidated swap blocks when a page is destroyed
92 * from: Utah $Hdr: swap_pager.c 1.4 91/04/30$
93 * @(#)swap_pager.c 8.9 (Berkeley) 3/21/94
94 * $FreeBSD: src/sys/vm/swap_pager.c,v 1.130.2.12 2002/08/31 21:15:55 dillon Exp $
97 #include <sys/param.h>
98 #include <sys/systm.h>
100 #include <sys/kernel.h>
101 #include <sys/proc.h>
103 #include <sys/vnode.h>
104 #include <sys/malloc.h>
105 #include <sys/vmmeter.h>
106 #include <sys/sysctl.h>
107 #include <sys/blist.h>
108 #include <sys/lock.h>
109 #include <sys/kcollect.h>
112 #include "opt_swap.h"
114 #include <vm/vm_object.h>
115 #include <vm/vm_page.h>
116 #include <vm/vm_pager.h>
117 #include <vm/vm_pageout.h>
118 #include <vm/swap_pager.h>
119 #include <vm/vm_extern.h>
120 #include <vm/vm_zone.h>
121 #include <vm/vnode_pager.h>
123 #include <sys/buf2.h>
124 #include <vm/vm_page2.h>
126 #ifndef MAX_PAGEOUT_CLUSTER
127 #define MAX_PAGEOUT_CLUSTER SWB_NPAGES
130 #define SWM_FREE 0x02 /* free, period */
131 #define SWM_POP 0x04 /* pop out */
133 #define SWBIO_READ 0x01
134 #define SWBIO_WRITE 0x02
135 #define SWBIO_SYNC 0x04
136 #define SWBIO_TTC 0x08 /* for VM_PAGER_TRY_TO_CACHE */
142 vm_pindex_t endi; /* inclusive */
145 struct swswapoffinfo {
152 * vm_swap_size is in page-sized chunks now. It was DEV_BSIZE'd chunks
156 int swap_pager_full; /* swap space exhaustion (task killing) */
157 int swap_fail_ticks; /* when we became exhausted */
158 int swap_pager_almost_full; /* swap space exhaustion (w/ hysteresis)*/
159 swblk_t vm_swap_cache_use;
160 swblk_t vm_swap_anon_use;
161 static int vm_report_swap_allocs;
163 static int nsw_rcount; /* free read buffers */
164 static int nsw_wcount_sync; /* limit write buffers / synchronous */
165 static int nsw_wcount_async; /* limit write buffers / asynchronous */
166 static int nsw_wcount_async_max;/* assigned maximum */
167 static int nsw_cluster_max; /* maximum VOP I/O allowed */
169 struct blist *swapblist;
170 static int swap_async_max = 4; /* maximum in-progress async I/O's */
171 static int swap_burst_read = 0; /* allow burst reading */
172 static swblk_t swapiterator; /* linearize allocations */
173 int swap_user_async = 0; /* user swap pager operation can be async */
175 static struct spinlock swapbp_spin = SPINLOCK_INITIALIZER(&swapbp_spin, "swapbp_spin");
178 extern struct vnode *swapdev_vp;
179 extern struct swdevt *swdevt;
182 #define BLK2DEVIDX(blk) (nswdev > 1 ? blk / SWB_DMMAX % nswdev : 0)
184 SYSCTL_INT(_vm, OID_AUTO, swap_async_max,
185 CTLFLAG_RW, &swap_async_max, 0, "Maximum running async swap ops");
186 SYSCTL_INT(_vm, OID_AUTO, swap_burst_read,
187 CTLFLAG_RW, &swap_burst_read, 0, "Allow burst reads for pageins");
188 SYSCTL_INT(_vm, OID_AUTO, swap_user_async,
189 CTLFLAG_RW, &swap_user_async, 0, "Allow async uuser swap write I/O");
192 SYSCTL_LONG(_vm, OID_AUTO, swap_cache_use,
193 CTLFLAG_RD, &vm_swap_cache_use, 0, "");
194 SYSCTL_LONG(_vm, OID_AUTO, swap_anon_use,
195 CTLFLAG_RD, &vm_swap_anon_use, 0, "");
196 SYSCTL_LONG(_vm, OID_AUTO, swap_size,
197 CTLFLAG_RD, &vm_swap_size, 0, "");
199 SYSCTL_INT(_vm, OID_AUTO, swap_cache_use,
200 CTLFLAG_RD, &vm_swap_cache_use, 0, "");
201 SYSCTL_INT(_vm, OID_AUTO, swap_anon_use,
202 CTLFLAG_RD, &vm_swap_anon_use, 0, "");
203 SYSCTL_INT(_vm, OID_AUTO, swap_size,
204 CTLFLAG_RD, &vm_swap_size, 0, "");
206 SYSCTL_INT(_vm, OID_AUTO, report_swap_allocs,
207 CTLFLAG_RW, &vm_report_swap_allocs, 0, "");
212 * Red-Black tree for swblock entries
214 * The caller must hold vm_token
216 RB_GENERATE2(swblock_rb_tree, swblock, swb_entry, rb_swblock_compare,
217 vm_pindex_t, swb_index);
220 rb_swblock_compare(struct swblock *swb1, struct swblock *swb2)
222 if (swb1->swb_index < swb2->swb_index)
224 if (swb1->swb_index > swb2->swb_index)
231 rb_swblock_scancmp(struct swblock *swb, void *data)
233 struct swfreeinfo *info = data;
235 if (swb->swb_index < info->basei)
237 if (swb->swb_index > info->endi)
244 rb_swblock_condcmp(struct swblock *swb, void *data)
246 struct swfreeinfo *info = data;
248 if (swb->swb_index < info->basei)
254 * pagerops for OBJT_SWAP - "swap pager". Some ops are also global procedure
255 * calls hooked from other parts of the VM system and do not appear here.
256 * (see vm/swap_pager.h).
259 static void swap_pager_dealloc (vm_object_t object);
260 static int swap_pager_getpage (vm_object_t, vm_page_t *, int);
261 static void swap_chain_iodone(struct bio *biox);
263 struct pagerops swappagerops = {
264 swap_pager_dealloc, /* deallocate an OBJT_SWAP object */
265 swap_pager_getpage, /* pagein */
266 swap_pager_putpages, /* pageout */
267 swap_pager_haspage /* get backing store status for page */
271 * SWB_DMMAX is in page-sized chunks with the new swap system. It was
272 * dev-bsized chunks in the old. SWB_DMMAX is always a power of 2.
274 * swap_*() routines are externally accessible. swp_*() routines are
278 int nswap_lowat = 128; /* in pages, swap_pager_almost_full warn */
279 int nswap_hiwat = 512; /* in pages, swap_pager_almost_full warn */
281 static __inline void swp_sizecheck (void);
282 static void swp_pager_async_iodone (struct bio *bio);
285 * Swap bitmap functions
288 static __inline void swp_pager_freeswapspace(vm_object_t object,
289 swblk_t blk, int npages);
290 static __inline swblk_t swp_pager_getswapspace(vm_object_t object, int npages);
296 static void swp_pager_meta_convert(vm_object_t);
297 static void swp_pager_meta_build(vm_object_t, vm_pindex_t, swblk_t);
298 static void swp_pager_meta_free(vm_object_t, vm_pindex_t, vm_pindex_t);
299 static void swp_pager_meta_free_all(vm_object_t);
300 static swblk_t swp_pager_meta_ctl(vm_object_t, vm_pindex_t, int);
303 * SWP_SIZECHECK() - update swap_pager_full indication
305 * update the swap_pager_almost_full indication and warn when we are
306 * about to run out of swap space, using lowat/hiwat hysteresis.
308 * Clear swap_pager_full ( task killing ) indication when lowat is met.
310 * No restrictions on call
311 * This routine may not block.
317 if (vm_swap_size < nswap_lowat) {
318 if (swap_pager_almost_full == 0) {
319 kprintf("swap_pager: out of swap space\n");
320 swap_pager_almost_full = 1;
321 swap_fail_ticks = ticks;
325 if (vm_swap_size > nswap_hiwat)
326 swap_pager_almost_full = 0;
331 * Long-term data collection on 10-second interval. Return the value
332 * for KCOLLECT_SWAPPCT and set the values for SWAPANO and SWAPCCAC.
334 * Return total swap in the scale field. This can change if swap is
335 * regularly added or removed and may cause some historical confusion
336 * in that case, but SWAPPCT will always be historically accurate.
339 #define PTOB(value) ((uint64_t)(value) << PAGE_SHIFT)
342 collect_swap_callback(int n)
344 uint64_t total = vm_swap_max;
345 uint64_t anon = vm_swap_anon_use;
346 uint64_t cache = vm_swap_cache_use;
348 if (total == 0) /* avoid divide by zero */
350 kcollect_setvalue(KCOLLECT_SWAPANO, PTOB(anon));
351 kcollect_setvalue(KCOLLECT_SWAPCAC, PTOB(cache));
352 kcollect_setscale(KCOLLECT_SWAPANO,
353 KCOLLECT_SCALE(KCOLLECT_SWAPANO_FORMAT, PTOB(total)));
354 kcollect_setscale(KCOLLECT_SWAPCAC,
355 KCOLLECT_SCALE(KCOLLECT_SWAPCAC_FORMAT, PTOB(total)));
356 return (((anon + cache) * 10000 + (total >> 1)) / total);
360 * SWAP_PAGER_INIT() - initialize the swap pager!
362 * Expected to be started from system init. NOTE: This code is run
363 * before much else so be careful what you depend on. Most of the VM
364 * system has yet to be initialized at this point.
366 * Called from the low level boot code only.
369 swap_pager_init(void *arg __unused)
371 kcollect_register(KCOLLECT_SWAPPCT, "swapuse", collect_swap_callback,
372 KCOLLECT_SCALE(KCOLLECT_SWAPPCT_FORMAT, 0));
373 kcollect_register(KCOLLECT_SWAPANO, "swapano", NULL,
374 KCOLLECT_SCALE(KCOLLECT_SWAPANO_FORMAT, 0));
375 kcollect_register(KCOLLECT_SWAPCAC, "swapcac", NULL,
376 KCOLLECT_SCALE(KCOLLECT_SWAPCAC_FORMAT, 0));
378 SYSINIT(vm_mem, SI_BOOT1_VM, SI_ORDER_THIRD, swap_pager_init, NULL);
381 * SWAP_PAGER_SWAP_INIT() - swap pager initialization from pageout process
383 * Expected to be started from pageout process once, prior to entering
386 * Called from the low level boot code only.
389 swap_pager_swap_init(void)
394 * Number of in-transit swap bp operations. Don't
395 * exhaust the pbufs completely. Make sure we
396 * initialize workable values (0 will work for hysteresis
397 * but it isn't very efficient).
399 * The nsw_cluster_max is constrained by the number of pages an XIO
400 * holds, i.e., (MAXPHYS/PAGE_SIZE) and our locally defined
401 * MAX_PAGEOUT_CLUSTER. Also be aware that swap ops are
402 * constrained by the swap device interleave stripe size.
404 * Currently we hardwire nsw_wcount_async to 4. This limit is
405 * designed to prevent other I/O from having high latencies due to
406 * our pageout I/O. The value 4 works well for one or two active swap
407 * devices but is probably a little low if you have more. Even so,
408 * a higher value would probably generate only a limited improvement
409 * with three or four active swap devices since the system does not
410 * typically have to pageout at extreme bandwidths. We will want
411 * at least 2 per swap devices, and 4 is a pretty good value if you
412 * have one NFS swap device due to the command/ack latency over NFS.
413 * So it all works out pretty well.
416 nsw_cluster_max = min((MAXPHYS/PAGE_SIZE), MAX_PAGEOUT_CLUSTER);
418 nsw_rcount = (nswbuf_kva + 1) / 2;
419 nsw_wcount_sync = (nswbuf_kva + 3) / 4;
420 nsw_wcount_async = 4;
421 nsw_wcount_async_max = nsw_wcount_async;
424 * The zone is dynamically allocated so generally size it to
425 * maxswzone (32MB to 256GB of KVM). Set a minimum size based
426 * on physical memory of around 8x (each swblock can hold 16 pages).
428 * With the advent of SSDs (vs HDs) the practical (swap:memory) ratio
429 * has increased dramatically.
431 n = vmstats.v_page_count / 2;
432 if (maxswzone && n < maxswzone / sizeof(struct swblock))
433 n = maxswzone / sizeof(struct swblock);
439 sizeof(struct swblock),
442 if (swap_zone != NULL)
445 * if the allocation failed, try a zone two thirds the
446 * size of the previous attempt.
451 if (swap_zone == NULL)
452 panic("swap_pager_swap_init: swap_zone == NULL");
454 kprintf("Swap zone entries reduced from %d to %d.\n", n2, n);
458 * SWAP_PAGER_ALLOC() - allocate a new OBJT_SWAP VM object and instantiate
459 * its metadata structures.
461 * This routine is called from the mmap and fork code to create a new
462 * OBJT_SWAP object. We do this by creating an OBJT_DEFAULT object
463 * and then converting it with swp_pager_meta_convert().
465 * We only support unnamed objects.
470 swap_pager_alloc(void *handle, off_t size, vm_prot_t prot, off_t offset)
474 KKASSERT(handle == NULL);
475 object = vm_object_allocate_hold(OBJT_DEFAULT,
476 OFF_TO_IDX(offset + PAGE_MASK + size));
477 swp_pager_meta_convert(object);
478 vm_object_drop(object);
484 * SWAP_PAGER_DEALLOC() - remove swap metadata from object
486 * The swap backing for the object is destroyed. The code is
487 * designed such that we can reinstantiate it later, but this
488 * routine is typically called only when the entire object is
489 * about to be destroyed.
491 * The object must be locked or unreferenceable.
492 * No other requirements.
495 swap_pager_dealloc(vm_object_t object)
497 vm_object_hold(object);
498 vm_object_pip_wait(object, "swpdea");
501 * Free all remaining metadata. We only bother to free it from
502 * the swap meta data. We do not attempt to free swapblk's still
503 * associated with vm_page_t's for this object. We do not care
504 * if paging is still in progress on some objects.
506 swp_pager_meta_free_all(object);
507 vm_object_drop(object);
510 /************************************************************************
511 * SWAP PAGER BITMAP ROUTINES *
512 ************************************************************************/
515 * SWP_PAGER_GETSWAPSPACE() - allocate raw swap space
517 * Allocate swap for the requested number of pages. The starting
518 * swap block number (a page index) is returned or SWAPBLK_NONE
519 * if the allocation failed.
521 * Also has the side effect of advising that somebody made a mistake
522 * when they configured swap and didn't configure enough.
524 * The caller must hold the object.
525 * This routine may not block.
527 static __inline swblk_t
528 swp_pager_getswapspace(vm_object_t object, int npages)
532 lwkt_gettoken(&vm_token);
533 blk = blist_allocat(swapblist, npages, swapiterator);
534 if (blk == SWAPBLK_NONE)
535 blk = blist_allocat(swapblist, npages, 0);
536 if (blk == SWAPBLK_NONE) {
537 if (swap_pager_full != 2) {
538 if (vm_swap_max == 0)
539 kprintf("Warning: The system would like to "
540 "page to swap but no swap space "
543 kprintf("swap_pager_getswapspace: "
544 "swap full allocating %d pages\n",
547 if (swap_pager_almost_full == 0)
548 swap_fail_ticks = ticks;
549 swap_pager_almost_full = 1;
552 /* swapiterator = blk; disable for now, doesn't work well */
553 swapacctspace(blk, -npages);
554 if (object->type == OBJT_SWAP)
555 vm_swap_anon_use += npages;
557 vm_swap_cache_use += npages;
560 lwkt_reltoken(&vm_token);
565 * SWP_PAGER_FREESWAPSPACE() - free raw swap space
567 * This routine returns the specified swap blocks back to the bitmap.
569 * Note: This routine may not block (it could in the old swap code),
570 * and through the use of the new blist routines it does not block.
572 * This routine may not block.
576 swp_pager_freeswapspace(vm_object_t object, swblk_t blk, int npages)
578 struct swdevt *sp = &swdevt[BLK2DEVIDX(blk)];
580 lwkt_gettoken(&vm_token);
581 sp->sw_nused -= npages;
582 if (object->type == OBJT_SWAP)
583 vm_swap_anon_use -= npages;
585 vm_swap_cache_use -= npages;
587 if (sp->sw_flags & SW_CLOSING) {
588 lwkt_reltoken(&vm_token);
592 blist_free(swapblist, blk, npages);
593 vm_swap_size += npages;
595 lwkt_reltoken(&vm_token);
599 * SWAP_PAGER_FREESPACE() - frees swap blocks associated with a page
600 * range within an object.
602 * This is a globally accessible routine.
604 * This routine removes swapblk assignments from swap metadata.
606 * The external callers of this routine typically have already destroyed
607 * or renamed vm_page_t's associated with this range in the object so
613 swap_pager_freespace(vm_object_t object, vm_pindex_t start, vm_pindex_t size)
615 vm_object_hold(object);
616 swp_pager_meta_free(object, start, size);
617 vm_object_drop(object);
624 swap_pager_freespace_all(vm_object_t object)
626 vm_object_hold(object);
627 swp_pager_meta_free_all(object);
628 vm_object_drop(object);
632 * This function conditionally frees swap cache swap starting at
633 * (*basei) in the object. (count) swap blocks will be nominally freed.
634 * The actual number of blocks freed can be more or less than the
637 * This function nominally returns the number of blocks freed. However,
638 * the actual number of blocks freed may be less then the returned value.
639 * If the function is unable to exhaust the object or if it is able to
640 * free (approximately) the requested number of blocks it returns
643 * If we exhaust the object we will return a value n <= count.
645 * The caller must hold the object.
647 * WARNING! If count == 0 then -1 can be returned as a degenerate case,
648 * callers should always pass a count value > 0.
650 static int swap_pager_condfree_callback(struct swblock *swap, void *data);
653 swap_pager_condfree(vm_object_t object, vm_pindex_t *basei, int count)
655 struct swfreeinfo info;
659 ASSERT_LWKT_TOKEN_HELD(vm_object_token(object));
661 info.object = object;
662 info.basei = *basei; /* skip up to this page index */
663 info.begi = count; /* max swap pages to destroy */
664 info.endi = count * 8; /* max swblocks to scan */
666 swblock_rb_tree_RB_SCAN(&object->swblock_root, rb_swblock_condcmp,
667 swap_pager_condfree_callback, &info);
671 * Take the higher difference swblocks vs pages
673 n = count - (int)info.begi;
674 t = count * 8 - (int)info.endi;
683 * The idea is to free whole meta-block to avoid fragmenting
684 * the swap space or disk I/O. We only do this if NO VM pages
687 * We do not have to deal with clearing PG_SWAPPED in related VM
688 * pages because there are no related VM pages.
690 * The caller must hold the object.
693 swap_pager_condfree_callback(struct swblock *swap, void *data)
695 struct swfreeinfo *info = data;
696 vm_object_t object = info->object;
699 for (i = 0; i < SWAP_META_PAGES; ++i) {
700 if (vm_page_lookup(object, swap->swb_index + i))
703 info->basei = swap->swb_index + SWAP_META_PAGES;
704 if (i == SWAP_META_PAGES) {
705 info->begi -= swap->swb_count;
706 swap_pager_freespace(object, swap->swb_index, SWAP_META_PAGES);
709 if ((int)info->begi < 0 || (int)info->endi < 0)
716 * Called by vm_page_alloc() when a new VM page is inserted
717 * into a VM object. Checks whether swap has been assigned to
718 * the page and sets PG_SWAPPED as necessary.
720 * (m) must be busied by caller and remains busied on return.
723 swap_pager_page_inserted(vm_page_t m)
725 if (m->object->swblock_count) {
726 vm_object_hold(m->object);
727 if (swp_pager_meta_ctl(m->object, m->pindex, 0) != SWAPBLK_NONE)
728 vm_page_flag_set(m, PG_SWAPPED);
729 vm_object_drop(m->object);
734 * SWAP_PAGER_RESERVE() - reserve swap blocks in object
736 * Assigns swap blocks to the specified range within the object. The
737 * swap blocks are not zerod. Any previous swap assignment is destroyed.
739 * Returns 0 on success, -1 on failure.
741 * The caller is responsible for avoiding races in the specified range.
742 * No other requirements.
745 swap_pager_reserve(vm_object_t object, vm_pindex_t start, vm_size_t size)
748 swblk_t blk = SWAPBLK_NONE;
749 vm_pindex_t beg = start; /* save start index */
751 vm_object_hold(object);
756 while ((blk = swp_pager_getswapspace(object, n)) ==
761 swp_pager_meta_free(object, beg,
763 vm_object_drop(object);
768 swp_pager_meta_build(object, start, blk);
774 swp_pager_meta_free(object, start, n);
775 vm_object_drop(object);
780 * SWAP_PAGER_COPY() - copy blocks from source pager to destination pager
781 * and destroy the source.
783 * Copy any valid swapblks from the source to the destination. In
784 * cases where both the source and destination have a valid swapblk,
785 * we keep the destination's.
787 * This routine is allowed to block. It may block allocating metadata
788 * indirectly through swp_pager_meta_build() or if paging is still in
789 * progress on the source.
791 * XXX vm_page_collapse() kinda expects us not to block because we
792 * supposedly do not need to allocate memory, but for the moment we
793 * *may* have to get a little memory from the zone allocator, but
794 * it is taken from the interrupt memory. We should be ok.
796 * The source object contains no vm_page_t's (which is just as well)
797 * The source object is of type OBJT_SWAP.
799 * The source and destination objects must be held by the caller.
802 swap_pager_copy(vm_object_t srcobject, vm_object_t dstobject,
803 vm_pindex_t base_index, int destroysource)
807 ASSERT_LWKT_TOKEN_HELD(vm_object_token(srcobject));
808 ASSERT_LWKT_TOKEN_HELD(vm_object_token(dstobject));
811 * transfer source to destination.
813 for (i = 0; i < dstobject->size; ++i) {
817 * Locate (without changing) the swapblk on the destination,
818 * unless it is invalid in which case free it silently, or
819 * if the destination is a resident page, in which case the
820 * source is thrown away.
822 dstaddr = swp_pager_meta_ctl(dstobject, i, 0);
824 if (dstaddr == SWAPBLK_NONE) {
826 * Destination has no swapblk and is not resident,
831 srcaddr = swp_pager_meta_ctl(srcobject,
832 base_index + i, SWM_POP);
834 if (srcaddr != SWAPBLK_NONE)
835 swp_pager_meta_build(dstobject, i, srcaddr);
838 * Destination has valid swapblk or it is represented
839 * by a resident page. We destroy the sourceblock.
841 swp_pager_meta_ctl(srcobject, base_index + i, SWM_FREE);
846 * Free left over swap blocks in source.
848 * We have to revert the type to OBJT_DEFAULT so we do not accidently
849 * double-remove the object from the swap queues.
853 * Reverting the type is not necessary, the caller is going
854 * to destroy srcobject directly, but I'm doing it here
855 * for consistency since we've removed the object from its
858 swp_pager_meta_free_all(srcobject);
859 if (srcobject->type == OBJT_SWAP)
860 srcobject->type = OBJT_DEFAULT;
865 * SWAP_PAGER_HASPAGE() - determine if we have good backing store for
866 * the requested page.
868 * We determine whether good backing store exists for the requested
869 * page and return TRUE if it does, FALSE if it doesn't.
871 * If TRUE, we also try to determine how much valid, contiguous backing
872 * store exists before and after the requested page within a reasonable
873 * distance. We do not try to restrict it to the swap device stripe
874 * (that is handled in getpages/putpages). It probably isn't worth
880 swap_pager_haspage(vm_object_t object, vm_pindex_t pindex)
885 * do we have good backing store at the requested index ?
887 vm_object_hold(object);
888 blk0 = swp_pager_meta_ctl(object, pindex, 0);
890 if (blk0 == SWAPBLK_NONE) {
891 vm_object_drop(object);
894 vm_object_drop(object);
899 * SWAP_PAGER_PAGE_UNSWAPPED() - remove swap backing store related to page
901 * This removes any associated swap backing store, whether valid or
902 * not, from the page. This operates on any VM object, not just OBJT_SWAP
905 * This routine is typically called when a page is made dirty, at
906 * which point any associated swap can be freed. MADV_FREE also
907 * calls us in a special-case situation
909 * NOTE!!! If the page is clean and the swap was valid, the caller
910 * should make the page dirty before calling this routine.
911 * This routine does NOT change the m->dirty status of the page.
912 * Also: MADV_FREE depends on it.
914 * The page must be busied.
915 * The caller can hold the object to avoid blocking, else we might block.
916 * No other requirements.
919 swap_pager_unswapped(vm_page_t m)
921 if (m->flags & PG_SWAPPED) {
922 vm_object_hold(m->object);
923 KKASSERT(m->flags & PG_SWAPPED);
924 swp_pager_meta_ctl(m->object, m->pindex, SWM_FREE);
925 vm_page_flag_clear(m, PG_SWAPPED);
926 vm_object_drop(m->object);
931 * SWAP_PAGER_STRATEGY() - read, write, free blocks
933 * This implements a VM OBJECT strategy function using swap backing store.
934 * This can operate on any VM OBJECT type, not necessarily just OBJT_SWAP
935 * types. Only BUF_CMD_{READ,WRITE,FREEBLKS} is supported, any other
936 * requests will return EINVAL.
938 * This is intended to be a cacheless interface (i.e. caching occurs at
939 * higher levels), and is also used as a swap-based SSD cache for vnode
940 * and device objects.
942 * All I/O goes directly to and from the swap device.
944 * We currently attempt to run I/O synchronously or asynchronously as
945 * the caller requests. This isn't perfect because we loose error
946 * sequencing when we run multiple ops in parallel to satisfy a request.
947 * But this is swap, so we let it all hang out.
949 * NOTE: This function supports the KVABIO API wherein bp->b_data might
950 * not be synchronized to the current cpu.
955 swap_pager_strategy(vm_object_t object, struct bio *bio)
957 struct buf *bp = bio->bio_buf;
960 vm_pindex_t biox_blkno = 0;
966 struct bio_track *track;
971 * tracking for swapdev vnode I/Os
973 if (bp->b_cmd == BUF_CMD_READ)
974 track = &swapdev_vp->v_track_read;
976 track = &swapdev_vp->v_track_write;
980 * Only supported commands
982 if (bp->b_cmd != BUF_CMD_FREEBLKS &&
983 bp->b_cmd != BUF_CMD_READ &&
984 bp->b_cmd != BUF_CMD_WRITE) {
985 bp->b_error = EINVAL;
986 bp->b_flags |= B_ERROR | B_INVAL;
992 * bcount must be an integral number of pages.
994 if (bp->b_bcount & PAGE_MASK) {
995 bp->b_error = EINVAL;
996 bp->b_flags |= B_ERROR | B_INVAL;
998 kprintf("swap_pager_strategy: bp %p offset %lld size %d, "
999 "not page bounded\n",
1000 bp, (long long)bio->bio_offset, (int)bp->b_bcount);
1005 * Clear error indication, initialize page index, count, data pointer.
1008 bp->b_flags &= ~B_ERROR;
1009 bp->b_resid = bp->b_bcount;
1011 start = (vm_pindex_t)(bio->bio_offset >> PAGE_SHIFT);
1012 count = howmany(bp->b_bcount, PAGE_SIZE);
1015 * WARNING! Do not dereference *data without issuing a bkvasync()
1020 * Deal with BUF_CMD_FREEBLKS
1022 if (bp->b_cmd == BUF_CMD_FREEBLKS) {
1024 * FREE PAGE(s) - destroy underlying swap that is no longer
1027 vm_object_hold(object);
1028 swp_pager_meta_free(object, start, count);
1029 vm_object_drop(object);
1036 * We need to be able to create a new cluster of I/O's. We cannot
1037 * use the caller fields of the passed bio so push a new one.
1039 * Because nbio is just a placeholder for the cluster links,
1040 * we can biodone() the original bio instead of nbio to make
1041 * things a bit more efficient.
1043 nbio = push_bio(bio);
1044 nbio->bio_offset = bio->bio_offset;
1045 nbio->bio_caller_info1.cluster_head = NULL;
1046 nbio->bio_caller_info2.cluster_tail = NULL;
1052 * Execute read or write
1054 vm_object_hold(object);
1060 * Obtain block. If block not found and writing, allocate a
1061 * new block and build it into the object.
1063 blk = swp_pager_meta_ctl(object, start, 0);
1064 if ((blk == SWAPBLK_NONE) && bp->b_cmd == BUF_CMD_WRITE) {
1065 blk = swp_pager_getswapspace(object, 1);
1066 if (blk == SWAPBLK_NONE) {
1067 bp->b_error = ENOMEM;
1068 bp->b_flags |= B_ERROR;
1071 swp_pager_meta_build(object, start, blk);
1075 * Do we have to flush our current collection? Yes if:
1077 * - no swap block at this index
1078 * - swap block is not contiguous
1079 * - we cross a physical disk boundry in the
1083 (biox_blkno + btoc(bufx->b_bcount) != blk ||
1084 ((biox_blkno ^ blk) & ~SWB_DMMASK))) {
1087 ++mycpu->gd_cnt.v_swapin;
1088 mycpu->gd_cnt.v_swappgsin +=
1089 btoc(bufx->b_bcount);
1092 ++mycpu->gd_cnt.v_swapout;
1093 mycpu->gd_cnt.v_swappgsout +=
1094 btoc(bufx->b_bcount);
1095 bufx->b_dirtyend = bufx->b_bcount;
1103 * Finished with this buf.
1105 KKASSERT(bufx->b_bcount != 0);
1106 if (bufx->b_cmd != BUF_CMD_READ)
1107 bufx->b_dirtyend = bufx->b_bcount;
1113 * Add new swapblk to biox, instantiating biox if necessary.
1114 * Zero-fill reads are able to take a shortcut.
1116 if (blk == SWAPBLK_NONE) {
1118 * We can only get here if we are reading.
1121 bzero(data, PAGE_SIZE);
1122 bp->b_resid -= PAGE_SIZE;
1125 /* XXX chain count > 4, wait to <= 4 */
1127 bufx = getpbuf(NULL);
1128 bufx->b_flags |= B_KVABIO;
1129 biox = &bufx->b_bio1;
1130 cluster_append(nbio, bufx);
1131 bufx->b_cmd = bp->b_cmd;
1132 biox->bio_done = swap_chain_iodone;
1133 biox->bio_offset = (off_t)blk << PAGE_SHIFT;
1134 biox->bio_caller_info1.cluster_parent = nbio;
1137 bufx->b_data = data;
1139 bufx->b_bcount += PAGE_SIZE;
1146 vm_object_drop(object);
1149 * Flush out last buffer
1152 if (bufx->b_cmd == BUF_CMD_READ) {
1153 ++mycpu->gd_cnt.v_swapin;
1154 mycpu->gd_cnt.v_swappgsin += btoc(bufx->b_bcount);
1156 ++mycpu->gd_cnt.v_swapout;
1157 mycpu->gd_cnt.v_swappgsout += btoc(bufx->b_bcount);
1158 bufx->b_dirtyend = bufx->b_bcount;
1160 KKASSERT(bufx->b_bcount);
1161 if (bufx->b_cmd != BUF_CMD_READ)
1162 bufx->b_dirtyend = bufx->b_bcount;
1163 /* biox, bufx = NULL */
1167 * Now initiate all the I/O. Be careful looping on our chain as
1168 * I/O's may complete while we are still initiating them.
1170 * If the request is a 100% sparse read no bios will be present
1171 * and we just biodone() the buffer.
1173 nbio->bio_caller_info2.cluster_tail = NULL;
1174 bufx = nbio->bio_caller_info1.cluster_head;
1178 biox = &bufx->b_bio1;
1180 bufx = bufx->b_cluster_next;
1181 vn_strategy(swapdev_vp, biox);
1188 * Completion of the cluster will also call biodone_chain(nbio).
1189 * We never call biodone(nbio) so we don't have to worry about
1190 * setting up a bio_done callback. It's handled in the sub-IO.
1201 swap_chain_iodone(struct bio *biox)
1204 struct buf *bufx; /* chained sub-buffer */
1205 struct bio *nbio; /* parent nbio with chain glue */
1206 struct buf *bp; /* original bp associated with nbio */
1209 bufx = biox->bio_buf;
1210 nbio = biox->bio_caller_info1.cluster_parent;
1214 * Update the original buffer
1216 KKASSERT(bp != NULL);
1217 if (bufx->b_flags & B_ERROR) {
1218 atomic_set_int(&bufx->b_flags, B_ERROR);
1219 bp->b_error = bufx->b_error; /* race ok */
1220 } else if (bufx->b_resid != 0) {
1221 atomic_set_int(&bufx->b_flags, B_ERROR);
1222 bp->b_error = EINVAL; /* race ok */
1224 atomic_subtract_int(&bp->b_resid, bufx->b_bcount);
1228 * Remove us from the chain.
1230 spin_lock(&swapbp_spin);
1231 nextp = &nbio->bio_caller_info1.cluster_head;
1232 while (*nextp != bufx) {
1233 KKASSERT(*nextp != NULL);
1234 nextp = &(*nextp)->b_cluster_next;
1236 *nextp = bufx->b_cluster_next;
1237 chain_empty = (nbio->bio_caller_info1.cluster_head == NULL);
1238 spin_unlock(&swapbp_spin);
1241 * Clean up bufx. If the chain is now empty we finish out
1242 * the parent. Note that we may be racing other completions
1243 * so we must use the chain_empty status from above.
1246 if (bp->b_resid != 0 && !(bp->b_flags & B_ERROR)) {
1247 atomic_set_int(&bp->b_flags, B_ERROR);
1248 bp->b_error = EINVAL;
1250 biodone_chain(nbio);
1252 relpbuf(bufx, NULL);
1256 * SWAP_PAGER_GETPAGES() - bring page in from swap
1258 * The requested page may have to be brought in from swap. Calculate the
1259 * swap block and bring in additional pages if possible. All pages must
1260 * have contiguous swap block assignments and reside in the same object.
1262 * The caller has a single vm_object_pip_add() reference prior to
1263 * calling us and we should return with the same.
1265 * The caller has BUSY'd the page. We should return with (*mpp) left busy,
1266 * and any additinal pages unbusied.
1268 * If the caller encounters a PG_RAM page it will pass it to us even though
1269 * it may be valid and dirty. We cannot overwrite the page in this case!
1270 * The case is used to allow us to issue pure read-aheads.
1272 * NOTE! XXX This code does not entirely pipeline yet due to the fact that
1273 * the PG_RAM page is validated at the same time as mreq. What we
1274 * really need to do is issue a separate read-ahead pbuf.
1279 swap_pager_getpage(vm_object_t object, vm_page_t *mpp, int seqaccess)
1291 u_int32_t busy_count;
1292 vm_page_t marray[XIO_INTERNAL_PAGES];
1296 vm_object_hold(object);
1297 if (mreq->object != object) {
1298 panic("swap_pager_getpages: object mismatch %p/%p",
1305 * We don't want to overwrite a fully valid page as it might be
1306 * dirty. This case can occur when e.g. vm_fault hits a perfectly
1307 * valid page with PG_RAM set.
1309 * In this case we see if the next page is a suitable page-in
1310 * candidate and if it is we issue read-ahead. PG_RAM will be
1311 * set on the last page of the read-ahead to continue the pipeline.
1313 if (mreq->valid == VM_PAGE_BITS_ALL) {
1314 if (swap_burst_read == 0 || mreq->pindex + 1 >= object->size) {
1315 vm_object_drop(object);
1316 return(VM_PAGER_OK);
1318 blk = swp_pager_meta_ctl(object, mreq->pindex + 1, 0);
1319 if (blk == SWAPBLK_NONE) {
1320 vm_object_drop(object);
1321 return(VM_PAGER_OK);
1323 m = vm_page_lookup_busy_try(object, mreq->pindex + 1,
1326 vm_object_drop(object);
1327 return(VM_PAGER_OK);
1328 } else if (m == NULL) {
1330 * Use VM_ALLOC_QUICK to avoid blocking on cache
1333 m = vm_page_alloc(object, mreq->pindex + 1,
1336 vm_object_drop(object);
1337 return(VM_PAGER_OK);
1342 vm_object_drop(object);
1343 return(VM_PAGER_OK);
1345 vm_page_unqueue_nowakeup(m);
1355 * Try to block-read contiguous pages from swap if sequential,
1356 * otherwise just read one page. Contiguous pages from swap must
1357 * reside within a single device stripe because the I/O cannot be
1358 * broken up across multiple stripes.
1360 * Note that blk and iblk can be SWAPBLK_NONE but the loop is
1361 * set up such that the case(s) are handled implicitly.
1363 blk = swp_pager_meta_ctl(mreq->object, mreq->pindex, 0);
1366 for (i = 1; i <= swap_burst_read &&
1367 i < XIO_INTERNAL_PAGES &&
1368 mreq->pindex + i < object->size; ++i) {
1371 iblk = swp_pager_meta_ctl(object, mreq->pindex + i, 0);
1372 if (iblk != blk + i)
1374 if ((blk ^ iblk) & ~SWB_DMMASK)
1376 m = vm_page_lookup_busy_try(object, mreq->pindex + i,
1380 } else if (m == NULL) {
1382 * Use VM_ALLOC_QUICK to avoid blocking on cache
1385 m = vm_page_alloc(object, mreq->pindex + i,
1394 vm_page_unqueue_nowakeup(m);
1400 vm_page_flag_set(marray[i - 1], PG_RAM);
1403 * If mreq is the requested page and we have nothing to do return
1404 * VM_PAGER_FAIL. If raonly is set mreq is just another read-ahead
1405 * page and must be cleaned up.
1407 if (blk == SWAPBLK_NONE) {
1410 vnode_pager_freepage(mreq);
1411 vm_object_drop(object);
1412 return(VM_PAGER_OK);
1414 vm_object_drop(object);
1415 return(VM_PAGER_FAIL);
1420 * Map our page(s) into kva for input
1422 * Use the KVABIO API to avoid synchronizing the pmap.
1424 bp = getpbuf_kva(&nsw_rcount);
1426 kva = (vm_offset_t) bp->b_kvabase;
1427 bcopy(marray, bp->b_xio.xio_pages, i * sizeof(vm_page_t));
1428 pmap_qenter_noinval(kva, bp->b_xio.xio_pages, i);
1430 bp->b_data = (caddr_t)kva;
1431 bp->b_bcount = PAGE_SIZE * i;
1432 bp->b_xio.xio_npages = i;
1433 bp->b_flags |= B_KVABIO;
1434 bio->bio_done = swp_pager_async_iodone;
1435 bio->bio_offset = (off_t)blk << PAGE_SHIFT;
1436 bio->bio_caller_info1.index = SWBIO_READ;
1439 * Set index. If raonly set the index beyond the array so all
1440 * the pages are treated the same, otherwise the original mreq is
1444 bio->bio_driver_info = (void *)(intptr_t)i;
1446 bio->bio_driver_info = (void *)(intptr_t)0;
1448 for (j = 0; j < i; ++j) {
1449 atomic_set_int(&bp->b_xio.xio_pages[j]->busy_count,
1453 mycpu->gd_cnt.v_swapin++;
1454 mycpu->gd_cnt.v_swappgsin += bp->b_xio.xio_npages;
1457 * We still hold the lock on mreq, and our automatic completion routine
1458 * does not remove it.
1460 vm_object_pip_add(object, bp->b_xio.xio_npages);
1463 * perform the I/O. NOTE!!! bp cannot be considered valid after
1464 * this point because we automatically release it on completion.
1465 * Instead, we look at the one page we are interested in which we
1466 * still hold a lock on even through the I/O completion.
1468 * The other pages in our m[] array are also released on completion,
1469 * so we cannot assume they are valid anymore either.
1471 bp->b_cmd = BUF_CMD_READ;
1473 vn_strategy(swapdev_vp, bio);
1476 * Wait for the page we want to complete. PBUSY_SWAPINPROG is always
1477 * cleared on completion. If an I/O error occurs, SWAPBLK_NONE
1478 * is set in the meta-data.
1480 * If this is a read-ahead only we return immediately without
1484 vm_object_drop(object);
1485 return(VM_PAGER_OK);
1489 * Read-ahead includes originally requested page case.
1492 busy_count = mreq->busy_count;
1494 if ((busy_count & PBUSY_SWAPINPROG) == 0)
1496 tsleep_interlock(mreq, 0);
1497 if (!atomic_cmpset_int(&mreq->busy_count, busy_count,
1499 PBUSY_SWAPINPROG | PBUSY_WANTED)) {
1502 atomic_set_int(&mreq->flags, PG_REFERENCED);
1503 mycpu->gd_cnt.v_intrans++;
1504 if (tsleep(mreq, PINTERLOCKED, "swread", hz*20)) {
1506 "swap_pager: indefinite wait buffer: "
1507 " bp %p offset: %lld, size: %ld\n",
1509 (long long)bio->bio_offset,
1516 * Disallow speculative reads prior to the SWAPINPROG test.
1521 * mreq is left busied after completion, but all the other pages
1522 * are freed. If we had an unrecoverable read error the page will
1525 vm_object_drop(object);
1526 if (mreq->valid != VM_PAGE_BITS_ALL)
1527 return(VM_PAGER_ERROR);
1529 return(VM_PAGER_OK);
1532 * A final note: in a low swap situation, we cannot deallocate swap
1533 * and mark a page dirty here because the caller is likely to mark
1534 * the page clean when we return, causing the page to possibly revert
1535 * to all-zero's later.
1540 * swap_pager_putpages:
1542 * Assign swap (if necessary) and initiate I/O on the specified pages.
1544 * We support both OBJT_DEFAULT and OBJT_SWAP objects. DEFAULT objects
1545 * are automatically converted to SWAP objects.
1547 * In a low memory situation we may block in vn_strategy(), but the new
1548 * vm_page reservation system coupled with properly written VFS devices
1549 * should ensure that no low-memory deadlock occurs. This is an area
1552 * The parent has N vm_object_pip_add() references prior to
1553 * calling us and will remove references for rtvals[] that are
1554 * not set to VM_PAGER_PEND. We need to remove the rest on I/O
1557 * The parent has soft-busy'd the pages it passes us and will unbusy
1558 * those whos rtvals[] entry is not set to VM_PAGER_PEND on return.
1559 * We need to unbusy the rest on I/O completion.
1564 swap_pager_putpages(vm_object_t object, vm_page_t *m, int count,
1565 int flags, int *rtvals)
1570 vm_object_hold(object);
1572 if (count && m[0]->object != object) {
1573 panic("swap_pager_getpages: object mismatch %p/%p",
1582 * Turn object into OBJT_SWAP
1583 * Check for bogus sysops
1585 * Force sync if not pageout process, we don't want any single
1586 * non-pageout process to be able to hog the I/O subsystem! This
1587 * can be overridden by setting.
1589 if (object->type == OBJT_DEFAULT) {
1590 if (object->type == OBJT_DEFAULT)
1591 swp_pager_meta_convert(object);
1595 * Normally we force synchronous swap I/O if this is not the
1596 * pageout daemon to prevent any single user process limited
1597 * via RLIMIT_RSS from hogging swap write bandwidth.
1599 if (curthread != pagethread &&
1600 curthread != emergpager &&
1601 swap_user_async == 0) {
1602 flags |= VM_PAGER_PUT_SYNC;
1608 * Update nsw parameters from swap_async_max sysctl values.
1609 * Do not let the sysop crash the machine with bogus numbers.
1611 if (swap_async_max != nsw_wcount_async_max) {
1617 if ((n = swap_async_max) > nswbuf_kva / 2)
1624 * Adjust difference ( if possible ). If the current async
1625 * count is too low, we may not be able to make the adjustment
1628 * vm_token needed for nsw_wcount sleep interlock
1630 lwkt_gettoken(&vm_token);
1631 n -= nsw_wcount_async_max;
1632 if (nsw_wcount_async + n >= 0) {
1633 nsw_wcount_async_max += n;
1634 pbuf_adjcount(&nsw_wcount_async, n);
1636 lwkt_reltoken(&vm_token);
1642 * Assign swap blocks and issue I/O. We reallocate swap on the fly.
1643 * The page is left dirty until the pageout operation completes
1647 for (i = 0; i < count; i += n) {
1654 * Maximum I/O size is limited by a number of factors.
1657 n = min(BLIST_MAX_ALLOC, count - i);
1658 n = min(n, nsw_cluster_max);
1660 lwkt_gettoken(&vm_token);
1663 * Get biggest block of swap we can. If we fail, fall
1664 * back and try to allocate a smaller block. Don't go
1665 * overboard trying to allocate space if it would overly
1669 (blk = swp_pager_getswapspace(object, n)) == SWAPBLK_NONE &&
1674 if (blk == SWAPBLK_NONE) {
1675 for (j = 0; j < n; ++j)
1676 rtvals[i+j] = VM_PAGER_FAIL;
1677 lwkt_reltoken(&vm_token);
1680 if (vm_report_swap_allocs > 0) {
1681 kprintf("swap_alloc %08jx,%d\n", (intmax_t)blk, n);
1682 --vm_report_swap_allocs;
1686 * The I/O we are constructing cannot cross a physical
1687 * disk boundry in the swap stripe.
1689 if ((blk ^ (blk + n)) & ~SWB_DMMASK) {
1690 j = ((blk + SWB_DMMAX) & ~SWB_DMMASK) - blk;
1691 swp_pager_freeswapspace(object, blk + j, n - j);
1696 * All I/O parameters have been satisfied, build the I/O
1697 * request and assign the swap space.
1699 * Use the KVABIO API to avoid synchronizing the pmap.
1701 if ((flags & VM_PAGER_PUT_SYNC))
1702 bp = getpbuf_kva(&nsw_wcount_sync);
1704 bp = getpbuf_kva(&nsw_wcount_async);
1707 lwkt_reltoken(&vm_token);
1709 pmap_qenter_noinval((vm_offset_t)bp->b_data, &m[i], n);
1711 bp->b_flags |= B_KVABIO;
1712 bp->b_bcount = PAGE_SIZE * n;
1713 bio->bio_offset = (off_t)blk << PAGE_SHIFT;
1715 for (j = 0; j < n; ++j) {
1716 vm_page_t mreq = m[i+j];
1718 swp_pager_meta_build(mreq->object, mreq->pindex,
1720 if (object->type == OBJT_SWAP)
1721 vm_page_dirty(mreq);
1722 rtvals[i+j] = VM_PAGER_OK;
1724 atomic_set_int(&mreq->busy_count, PBUSY_SWAPINPROG);
1725 bp->b_xio.xio_pages[j] = mreq;
1727 bp->b_xio.xio_npages = n;
1729 mycpu->gd_cnt.v_swapout++;
1730 mycpu->gd_cnt.v_swappgsout += bp->b_xio.xio_npages;
1732 bp->b_dirtyoff = 0; /* req'd for NFS */
1733 bp->b_dirtyend = bp->b_bcount; /* req'd for NFS */
1734 bp->b_cmd = BUF_CMD_WRITE;
1735 bio->bio_caller_info1.index = SWBIO_WRITE;
1740 if ((flags & VM_PAGER_PUT_SYNC) == 0) {
1741 bio->bio_done = swp_pager_async_iodone;
1743 vn_strategy(swapdev_vp, bio);
1745 for (j = 0; j < n; ++j)
1746 rtvals[i+j] = VM_PAGER_PEND;
1751 * Issue synchrnously.
1753 * Wait for the sync I/O to complete, then update rtvals.
1754 * We just set the rtvals[] to VM_PAGER_PEND so we can call
1755 * our async completion routine at the end, thus avoiding a
1758 bio->bio_caller_info1.index |= SWBIO_SYNC;
1759 if (flags & VM_PAGER_TRY_TO_CACHE)
1760 bio->bio_caller_info1.index |= SWBIO_TTC;
1761 bio->bio_done = biodone_sync;
1762 bio->bio_flags |= BIO_SYNC;
1763 vn_strategy(swapdev_vp, bio);
1764 biowait(bio, "swwrt");
1766 for (j = 0; j < n; ++j)
1767 rtvals[i+j] = VM_PAGER_PEND;
1770 * Now that we are through with the bp, we can call the
1771 * normal async completion, which frees everything up.
1773 swp_pager_async_iodone(bio);
1775 vm_object_drop(object);
1781 * Recalculate the low and high-water marks.
1784 swap_pager_newswap(void)
1787 * NOTE: vm_swap_max cannot exceed 1 billion blocks, which is the
1788 * limitation imposed by the blist code. Remember that this
1789 * will be divided by NSWAP_MAX (4), so each swap device is
1790 * limited to around a terrabyte.
1793 nswap_lowat = (int64_t)vm_swap_max * 4 / 100; /* 4% left */
1794 nswap_hiwat = (int64_t)vm_swap_max * 6 / 100; /* 6% left */
1795 kprintf("swap low/high-water marks set to %d/%d\n",
1796 nswap_lowat, nswap_hiwat);
1805 * swp_pager_async_iodone:
1807 * Completion routine for asynchronous reads and writes from/to swap.
1808 * Also called manually by synchronous code to finish up a bp.
1810 * For READ operations, the pages are BUSY'd. For WRITE operations,
1811 * the pages are vm_page_t->busy'd. For READ operations, we BUSY
1812 * unbusy all pages except the 'main' request page. For WRITE
1813 * operations, we vm_page_t->busy'd unbusy all pages ( we can do this
1814 * because we marked them all VM_PAGER_PEND on return from putpages ).
1816 * This routine may not block.
1821 swp_pager_async_iodone(struct bio *bio)
1823 struct buf *bp = bio->bio_buf;
1824 vm_object_t object = NULL;
1831 if (bp->b_flags & B_ERROR) {
1833 "swap_pager: I/O error - %s failed; offset %lld,"
1834 "size %ld, error %d\n",
1835 ((bio->bio_caller_info1.index & SWBIO_READ) ?
1836 "pagein" : "pageout"),
1837 (long long)bio->bio_offset,
1846 if (bp->b_xio.xio_npages)
1847 object = bp->b_xio.xio_pages[0]->object;
1850 /* PMAP TESTING CODE (useful, keep it in but #if 0'd) */
1851 if (bio->bio_caller_info1.index & SWBIO_WRITE) {
1852 if (bio->bio_crc != iscsi_crc32(bp->b_data, bp->b_bcount)) {
1853 kprintf("SWAPOUT: BADCRC %08x %08x\n",
1855 iscsi_crc32(bp->b_data, bp->b_bcount));
1856 for (i = 0; i < bp->b_xio.xio_npages; ++i) {
1857 vm_page_t m = bp->b_xio.xio_pages[i];
1858 if (m->flags & PG_WRITEABLE)
1860 "%d/%d %p writable\n",
1861 i, bp->b_xio.xio_npages, m);
1868 * remove the mapping for kernel virtual
1870 pmap_qremove((vm_offset_t)bp->b_data, bp->b_xio.xio_npages);
1873 * cleanup pages. If an error occurs writing to swap, we are in
1874 * very serious trouble. If it happens to be a disk error, though,
1875 * we may be able to recover by reassigning the swap later on. So
1876 * in this case we remove the m->swapblk assignment for the page
1877 * but do not free it in the rlist. The errornous block(s) are thus
1878 * never reallocated as swap. Redirty the page and continue.
1880 for (i = 0; i < bp->b_xio.xio_npages; ++i) {
1881 vm_page_t m = bp->b_xio.xio_pages[i];
1883 if (bp->b_flags & B_ERROR) {
1885 * If an error occurs I'd love to throw the swapblk
1886 * away without freeing it back to swapspace, so it
1887 * can never be used again. But I can't from an
1891 if (bio->bio_caller_info1.index & SWBIO_READ) {
1893 * When reading, reqpage needs to stay
1894 * locked for the parent, but all other
1895 * pages can be freed. We still want to
1896 * wakeup the parent waiting on the page,
1897 * though. ( also: pg_reqpage can be -1 and
1898 * not match anything ).
1900 * We have to wake specifically requested pages
1901 * up too because we cleared SWAPINPROG and
1902 * someone may be waiting for that.
1904 * NOTE: For reads, m->dirty will probably
1905 * be overridden by the original caller
1906 * of getpages so don't play cute tricks
1909 * NOTE: We can't actually free the page from
1910 * here, because this is an interrupt.
1911 * It is not legal to mess with
1912 * object->memq from an interrupt.
1913 * Deactivate the page instead.
1915 * WARNING! The instant SWAPINPROG is
1916 * cleared another cpu may start
1917 * using the mreq page (it will
1918 * check m->valid immediately).
1922 atomic_clear_int(&m->busy_count,
1926 * bio_driver_info holds the requested page
1929 if (i != (int)(intptr_t)bio->bio_driver_info) {
1930 vm_page_deactivate(m);
1936 * If i == bp->b_pager.pg_reqpage, do not wake
1937 * the page up. The caller needs to.
1941 * If a write error occurs remove the swap
1942 * assignment (note that PG_SWAPPED may or
1943 * may not be set depending on prior activity).
1945 * Re-dirty OBJT_SWAP pages as there is no
1946 * other backing store, we can't throw the
1949 * Non-OBJT_SWAP pages (aka swapcache) must
1950 * not be dirtied since they may not have
1951 * been dirty in the first place, and they
1952 * do have backing store (the vnode).
1954 vm_page_busy_wait(m, FALSE, "swadpg");
1955 vm_object_hold(m->object);
1956 swp_pager_meta_ctl(m->object, m->pindex,
1958 vm_page_flag_clear(m, PG_SWAPPED);
1959 vm_object_drop(m->object);
1960 if (m->object->type == OBJT_SWAP) {
1962 vm_page_activate(m);
1964 vm_page_io_finish(m);
1965 atomic_clear_int(&m->busy_count,
1969 } else if (bio->bio_caller_info1.index & SWBIO_READ) {
1971 * NOTE: for reads, m->dirty will probably be
1972 * overridden by the original caller of getpages so
1973 * we cannot set them in order to free the underlying
1974 * swap in a low-swap situation. I don't think we'd
1975 * want to do that anyway, but it was an optimization
1976 * that existed in the old swapper for a time before
1977 * it got ripped out due to precisely this problem.
1979 * If not the requested page then deactivate it.
1981 * Note that the requested page, reqpage, is left
1982 * busied, but we still have to wake it up. The
1983 * other pages are released (unbusied) by
1984 * vm_page_wakeup(). We do not set reqpage's
1985 * valid bits here, it is up to the caller.
1989 * NOTE: Can't call pmap_clear_modify(m) from an
1990 * interrupt thread, the pmap code may have to
1991 * map non-kernel pmaps and currently asserts
1994 * WARNING! The instant SWAPINPROG is
1995 * cleared another cpu may start
1996 * using the mreq page (it will
1997 * check m->valid immediately).
1999 /*pmap_clear_modify(m);*/
2000 m->valid = VM_PAGE_BITS_ALL;
2002 vm_page_flag_set(m, PG_SWAPPED);
2003 atomic_clear_int(&m->busy_count, PBUSY_SWAPINPROG);
2006 * We have to wake specifically requested pages
2007 * up too because we cleared SWAPINPROG and
2008 * could be waiting for it in getpages. However,
2009 * be sure to not unbusy getpages specifically
2010 * requested page - getpages expects it to be
2013 * bio_driver_info holds the requested page
2015 if (i != (int)(intptr_t)bio->bio_driver_info) {
2016 vm_page_deactivate(m);
2023 * Mark the page clean but do not mess with the
2024 * pmap-layer's modified state. That state should
2025 * also be clear since the caller protected the
2026 * page VM_PROT_READ, but allow the case.
2028 * We are in an interrupt, avoid pmap operations.
2030 * If we have a severe page deficit, deactivate the
2031 * page. Do not try to cache it (which would also
2032 * involve a pmap op), because the page might still
2035 * When using the swap to cache clean vnode pages
2036 * we do not mess with the page dirty bits.
2038 * NOTE! Nobody is waiting for the key mreq page
2039 * on write completion.
2041 vm_page_busy_wait(m, FALSE, "swadpg");
2042 if (m->object->type == OBJT_SWAP)
2044 vm_page_flag_set(m, PG_SWAPPED);
2045 atomic_clear_int(&m->busy_count, PBUSY_SWAPINPROG);
2046 if (vm_page_count_severe())
2047 vm_page_deactivate(m);
2048 vm_page_io_finish(m);
2049 if (bio->bio_caller_info1.index & SWBIO_TTC)
2050 vm_page_try_to_cache(m);
2057 * adjust pip. NOTE: the original parent may still have its own
2058 * pip refs on the object.
2062 vm_object_pip_wakeup_n(object, bp->b_xio.xio_npages);
2065 * Release the physical I/O buffer.
2067 * NOTE: Due to synchronous operations in the write case b_cmd may
2068 * already be set to BUF_CMD_DONE and BIO_SYNC may have already
2071 * Use vm_token to interlock nsw_rcount/wcount wakeup?
2073 lwkt_gettoken(&vm_token);
2074 if (bio->bio_caller_info1.index & SWBIO_READ)
2075 nswptr = &nsw_rcount;
2076 else if (bio->bio_caller_info1.index & SWBIO_SYNC)
2077 nswptr = &nsw_wcount_sync;
2079 nswptr = &nsw_wcount_async;
2080 bp->b_cmd = BUF_CMD_DONE;
2081 relpbuf(bp, nswptr);
2082 lwkt_reltoken(&vm_token);
2086 * Fault-in a potentially swapped page and remove the swap reference.
2087 * (used by swapoff code)
2089 * object must be held.
2091 static __inline void
2092 swp_pager_fault_page(vm_object_t object, int *sharedp, vm_pindex_t pindex)
2098 ASSERT_LWKT_TOKEN_HELD(vm_object_token(object));
2100 if (object->type == OBJT_VNODE) {
2102 * Any swap related to a vnode is due to swapcache. We must
2103 * vget() the vnode in case it is not active (otherwise
2104 * vref() will panic). Calling vm_object_page_remove() will
2105 * ensure that any swap ref is removed interlocked with the
2106 * page. clean_only is set to TRUE so we don't throw away
2109 vp = object->handle;
2110 error = vget(vp, LK_SHARED | LK_RETRY | LK_CANRECURSE);
2112 vm_object_page_remove(object, pindex, pindex + 1, TRUE);
2117 * Otherwise it is a normal OBJT_SWAP object and we can
2118 * fault the page in and remove the swap.
2120 m = vm_fault_object_page(object, IDX_TO_OFF(pindex),
2122 VM_FAULT_DIRTY | VM_FAULT_UNSWAP,
2130 * This removes all swap blocks related to a particular device. We have
2131 * to be careful of ripups during the scan.
2133 static int swp_pager_swapoff_callback(struct swblock *swap, void *data);
2136 swap_pager_swapoff(int devidx)
2138 struct vm_object_hash *hash;
2139 struct swswapoffinfo info;
2140 struct vm_object marker;
2144 bzero(&marker, sizeof(marker));
2145 marker.type = OBJT_MARKER;
2147 for (n = 0; n < VMOBJ_HSIZE; ++n) {
2148 hash = &vm_object_hash[n];
2150 lwkt_gettoken(&hash->token);
2151 TAILQ_INSERT_HEAD(&hash->list, &marker, object_list);
2153 while ((object = TAILQ_NEXT(&marker, object_list)) != NULL) {
2154 if (object->type == OBJT_MARKER)
2156 if (object->type != OBJT_SWAP &&
2157 object->type != OBJT_VNODE)
2159 vm_object_hold(object);
2160 if (object->type != OBJT_SWAP &&
2161 object->type != OBJT_VNODE) {
2162 vm_object_drop(object);
2167 * Object is special in that we can't just pagein
2168 * into vm_page's in it (tmpfs, vn).
2170 if ((object->flags & OBJ_NOPAGEIN) &&
2171 RB_ROOT(&object->swblock_root)) {
2172 vm_object_drop(object);
2176 info.object = object;
2178 info.devidx = devidx;
2179 swblock_rb_tree_RB_SCAN(&object->swblock_root,
2180 NULL, swp_pager_swapoff_callback,
2182 vm_object_drop(object);
2184 if (object == TAILQ_NEXT(&marker, object_list)) {
2185 TAILQ_REMOVE(&hash->list, &marker, object_list);
2186 TAILQ_INSERT_AFTER(&hash->list, object,
2187 &marker, object_list);
2190 TAILQ_REMOVE(&hash->list, &marker, object_list);
2191 lwkt_reltoken(&hash->token);
2195 * If we fail to locate all swblocks we just fail gracefully and
2196 * do not bother to restore paging on the swap device. If the
2197 * user wants to retry the user can retry.
2199 if (swdevt[devidx].sw_nused)
2207 swp_pager_swapoff_callback(struct swblock *swap, void *data)
2209 struct swswapoffinfo *info = data;
2210 vm_object_t object = info->object;
2215 index = swap->swb_index;
2216 for (i = 0; i < SWAP_META_PAGES; ++i) {
2218 * Make sure we don't race a dying object. This will
2219 * kill the scan of the object's swap blocks entirely.
2221 if (object->flags & OBJ_DEAD)
2225 * Fault the page, which can obviously block. If the swap
2226 * structure disappears break out.
2228 v = swap->swb_pages[i];
2229 if (v != SWAPBLK_NONE && BLK2DEVIDX(v) == info->devidx) {
2230 swp_pager_fault_page(object, &info->shared,
2231 swap->swb_index + i);
2232 /* swap ptr might go away */
2233 if (RB_LOOKUP(swblock_rb_tree,
2234 &object->swblock_root, index) != swap) {
2242 /************************************************************************
2244 ************************************************************************
2246 * These routines manipulate the swap metadata stored in the
2249 * Swap metadata is implemented with a global hash and not directly
2250 * linked into the object. Instead the object simply contains
2251 * appropriate tracking counters.
2255 * Lookup the swblock containing the specified swap block index.
2257 * The caller must hold the object.
2261 swp_pager_lookup(vm_object_t object, vm_pindex_t index)
2263 ASSERT_LWKT_TOKEN_HELD(vm_object_token(object));
2264 index &= ~(vm_pindex_t)SWAP_META_MASK;
2265 return (RB_LOOKUP(swblock_rb_tree, &object->swblock_root, index));
2269 * Remove a swblock from the RB tree.
2271 * The caller must hold the object.
2275 swp_pager_remove(vm_object_t object, struct swblock *swap)
2277 ASSERT_LWKT_TOKEN_HELD(vm_object_token(object));
2278 RB_REMOVE(swblock_rb_tree, &object->swblock_root, swap);
2282 * Convert default object to swap object if necessary
2284 * The caller must hold the object.
2287 swp_pager_meta_convert(vm_object_t object)
2289 if (object->type == OBJT_DEFAULT) {
2290 object->type = OBJT_SWAP;
2291 KKASSERT(object->swblock_count == 0);
2296 * SWP_PAGER_META_BUILD() - add swap block to swap meta data for object
2298 * We first convert the object to a swap object if it is a default
2299 * object. Vnode objects do not need to be converted.
2301 * The specified swapblk is added to the object's swap metadata. If
2302 * the swapblk is not valid, it is freed instead. Any previously
2303 * assigned swapblk is freed.
2305 * The caller must hold the object.
2308 swp_pager_meta_build(vm_object_t object, vm_pindex_t index, swblk_t swapblk)
2310 struct swblock *swap;
2311 struct swblock *oswap;
2314 KKASSERT(swapblk != SWAPBLK_NONE);
2315 ASSERT_LWKT_TOKEN_HELD(vm_object_token(object));
2318 * Convert object if necessary
2320 if (object->type == OBJT_DEFAULT)
2321 swp_pager_meta_convert(object);
2324 * Locate swblock. If not found create, but if we aren't adding
2325 * anything just return. If we run out of space in the map we wait
2326 * and, since the hash table may have changed, retry.
2329 swap = swp_pager_lookup(object, index);
2334 swap = zalloc(swap_zone);
2339 swap->swb_index = index & ~(vm_pindex_t)SWAP_META_MASK;
2340 swap->swb_count = 0;
2342 ++object->swblock_count;
2344 for (i = 0; i < SWAP_META_PAGES; ++i)
2345 swap->swb_pages[i] = SWAPBLK_NONE;
2346 oswap = RB_INSERT(swblock_rb_tree, &object->swblock_root, swap);
2347 KKASSERT(oswap == NULL);
2351 * Delete prior contents of metadata.
2353 * NOTE: Decrement swb_count after the freeing operation (which
2354 * might block) to prevent racing destruction of the swblock.
2356 index &= SWAP_META_MASK;
2358 while ((v = swap->swb_pages[index]) != SWAPBLK_NONE) {
2359 swap->swb_pages[index] = SWAPBLK_NONE;
2361 swp_pager_freeswapspace(object, v, 1);
2363 --mycpu->gd_vmtotal.t_vm;
2367 * Enter block into metadata
2369 swap->swb_pages[index] = swapblk;
2370 if (swapblk != SWAPBLK_NONE) {
2372 ++mycpu->gd_vmtotal.t_vm;
2377 * SWP_PAGER_META_FREE() - free a range of blocks in the object's swap metadata
2379 * The requested range of blocks is freed, with any associated swap
2380 * returned to the swap bitmap.
2382 * This routine will free swap metadata structures as they are cleaned
2383 * out. This routine does *NOT* operate on swap metadata associated
2384 * with resident pages.
2386 * The caller must hold the object.
2388 static int swp_pager_meta_free_callback(struct swblock *swb, void *data);
2391 swp_pager_meta_free(vm_object_t object, vm_pindex_t index, vm_pindex_t count)
2393 struct swfreeinfo info;
2395 ASSERT_LWKT_TOKEN_HELD(vm_object_token(object));
2400 if (object->swblock_count == 0) {
2401 KKASSERT(RB_EMPTY(&object->swblock_root));
2408 * Setup for RB tree scan. Note that the pindex range can be huge
2409 * due to the 64 bit page index space so we cannot safely iterate.
2411 info.object = object;
2412 info.basei = index & ~(vm_pindex_t)SWAP_META_MASK;
2414 info.endi = index + count - 1;
2415 swblock_rb_tree_RB_SCAN(&object->swblock_root, rb_swblock_scancmp,
2416 swp_pager_meta_free_callback, &info);
2420 * The caller must hold the object.
2424 swp_pager_meta_free_callback(struct swblock *swap, void *data)
2426 struct swfreeinfo *info = data;
2427 vm_object_t object = info->object;
2432 * Figure out the range within the swblock. The wider scan may
2433 * return edge-case swap blocks when the start and/or end points
2434 * are in the middle of a block.
2436 if (swap->swb_index < info->begi)
2437 index = (int)info->begi & SWAP_META_MASK;
2441 if (swap->swb_index + SWAP_META_PAGES > info->endi)
2442 eindex = (int)info->endi & SWAP_META_MASK;
2444 eindex = SWAP_META_MASK;
2447 * Scan and free the blocks. The loop terminates early
2448 * if (swap) runs out of blocks and could be freed.
2450 * NOTE: Decrement swb_count after swp_pager_freeswapspace()
2451 * to deal with a zfree race.
2453 while (index <= eindex) {
2454 swblk_t v = swap->swb_pages[index];
2456 if (v != SWAPBLK_NONE) {
2457 swap->swb_pages[index] = SWAPBLK_NONE;
2459 swp_pager_freeswapspace(object, v, 1);
2460 --mycpu->gd_vmtotal.t_vm;
2461 if (--swap->swb_count == 0) {
2462 swp_pager_remove(object, swap);
2463 zfree(swap_zone, swap);
2464 --object->swblock_count;
2471 /* swap may be invalid here due to zfree above */
2478 * SWP_PAGER_META_FREE_ALL() - destroy all swap metadata associated with object
2480 * This routine locates and destroys all swap metadata associated with
2483 * NOTE: Decrement swb_count after the freeing operation (which
2484 * might block) to prevent racing destruction of the swblock.
2486 * The caller must hold the object.
2489 swp_pager_meta_free_all(vm_object_t object)
2491 struct swblock *swap;
2494 ASSERT_LWKT_TOKEN_HELD(vm_object_token(object));
2496 while ((swap = RB_ROOT(&object->swblock_root)) != NULL) {
2497 swp_pager_remove(object, swap);
2498 for (i = 0; i < SWAP_META_PAGES; ++i) {
2499 swblk_t v = swap->swb_pages[i];
2500 if (v != SWAPBLK_NONE) {
2502 swp_pager_freeswapspace(object, v, 1);
2504 --mycpu->gd_vmtotal.t_vm;
2507 if (swap->swb_count != 0)
2508 panic("swap_pager_meta_free_all: swb_count != 0");
2509 zfree(swap_zone, swap);
2510 --object->swblock_count;
2513 KKASSERT(object->swblock_count == 0);
2517 * SWP_PAGER_METACTL() - misc control of swap and vm_page_t meta data.
2519 * This routine is capable of looking up, popping, or freeing
2520 * swapblk assignments in the swap meta data or in the vm_page_t.
2521 * The routine typically returns the swapblk being looked-up, or popped,
2522 * or SWAPBLK_NONE if the block was freed, or SWAPBLK_NONE if the block
2523 * was invalid. This routine will automatically free any invalid
2524 * meta-data swapblks.
2526 * It is not possible to store invalid swapblks in the swap meta data
2527 * (other then a literal 'SWAPBLK_NONE'), so we don't bother checking.
2529 * When acting on a busy resident page and paging is in progress, we
2530 * have to wait until paging is complete but otherwise can act on the
2533 * SWM_FREE remove and free swap block from metadata
2534 * SWM_POP remove from meta data but do not free.. pop it out
2536 * The caller must hold the object.
2539 swp_pager_meta_ctl(vm_object_t object, vm_pindex_t index, int flags)
2541 struct swblock *swap;
2544 if (object->swblock_count == 0)
2545 return(SWAPBLK_NONE);
2548 swap = swp_pager_lookup(object, index);
2551 index &= SWAP_META_MASK;
2552 r1 = swap->swb_pages[index];
2554 if (r1 != SWAPBLK_NONE) {
2555 if (flags & (SWM_FREE|SWM_POP)) {
2556 swap->swb_pages[index] = SWAPBLK_NONE;
2557 --mycpu->gd_vmtotal.t_vm;
2558 if (--swap->swb_count == 0) {
2559 swp_pager_remove(object, swap);
2560 zfree(swap_zone, swap);
2561 --object->swblock_count;
2564 /* swap ptr may be invalid */
2565 if (flags & SWM_FREE) {
2566 swp_pager_freeswapspace(object, r1, 1);
2570 /* swap ptr may be invalid */