/* * Copyright (c) 1998 Matthew Dillon, * Copyright (c) 1994 John S. Dyson * Copyright (c) 1990 University of Utah. * Copyright (c) 1982, 1986, 1989, 1993 * The Regents of the University of California. All rights reserved. * * This code is derived from software contributed to Berkeley by * the Systems Programming Group of the University of Utah Computer * Science Department. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * 1. Redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer. * 2. Redistributions in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer in the * documentation and/or other materials provided with the distribution. * 3. All advertising materials mentioning features or use of this software * must display the following acknowledgement: * This product includes software developed by the University of * California, Berkeley and its contributors. * 4. Neither the name of the University nor the names of its contributors * may be used to endorse or promote products derived from this software * without specific prior written permission. * * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF * SUCH DAMAGE. * * New Swap System * Matthew Dillon * * Radix Bitmap 'blists'. * * - The new swapper uses the new radix bitmap code. This should scale * to arbitrarily small or arbitrarily large swap spaces and an almost * arbitrary degree of fragmentation. * * Features: * * - on the fly reallocation of swap during putpages. The new system * does not try to keep previously allocated swap blocks for dirty * pages. * * - on the fly deallocation of swap * * - No more garbage collection required. Unnecessarily allocated swap * blocks only exist for dirty vm_page_t's now and these are already * cycled (in a high-load system) by the pager. We also do on-the-fly * removal of invalidated swap blocks when a page is destroyed * or renamed. * * from: Utah $Hdr: swap_pager.c 1.4 91/04/30$ * * @(#)swap_pager.c 8.9 (Berkeley) 3/21/94 * @(#)vm_swap.c 8.5 (Berkeley) 2/17/94 */ #include __FBSDID("$FreeBSD$"); #include "opt_mac.h" #include "opt_swap.h" #include "opt_vm.h" #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include /* * SWB_NPAGES must be a power of 2. It may be set to 1, 2, 4, 8, or 16 * pages per allocation. We recommend you stick with the default of 8. * The 16-page limit is due to the radix code (kern/subr_blist.c). */ #ifndef MAX_PAGEOUT_CLUSTER #define MAX_PAGEOUT_CLUSTER 16 #endif #if !defined(SWB_NPAGES) #define SWB_NPAGES MAX_PAGEOUT_CLUSTER #endif /* * Piecemeal swap metadata structure. Swap is stored in a radix tree. * * If SWB_NPAGES is 8 and sizeof(char *) == sizeof(daddr_t), our radix * is basically 8. Assuming PAGE_SIZE == 4096, one tree level represents * 32K worth of data, two levels represent 256K, three levels represent * 2 MBytes. This is acceptable. * * Overall memory utilization is about the same as the old swap structure. */ #define SWCORRECT(n) (sizeof(void *) * (n) / sizeof(daddr_t)) #define SWAP_META_PAGES (SWB_NPAGES * 2) #define SWAP_META_MASK (SWAP_META_PAGES - 1) typedef int32_t swblk_t; /* * swap offset. This is the type used to * address the "virtual swap device" and * therefore the maximum swap space is * 2^32 pages. */ /* * Swap device table */ struct swdevt { udev_t sw_dev; /* For quasibogus swapdev reporting */ int sw_flags; int sw_nblks; int sw_used; struct vnode *sw_vp; dev_t sw_device; swblk_t sw_first; swblk_t sw_end; struct blist *sw_blist; TAILQ_ENTRY(swdevt) sw_list; }; #define SW_CLOSING 0x04 struct swblock { struct swblock *swb_hnext; vm_object_t swb_object; vm_pindex_t swb_index; int swb_count; daddr_t swb_pages[SWAP_META_PAGES]; }; static TAILQ_HEAD(, swdevt) swtailq = TAILQ_HEAD_INITIALIZER(swtailq); static struct swdevt *swdevhd; /* Allocate from here next */ static int nswapdev; /* Number of swap devices */ int swap_pager_avail; static int swdev_syscall_active = 0; /* serialize swap(on|off) */ static void swapdev_strategy(struct buf *); #define SWM_FREE 0x02 /* free, period */ #define SWM_POP 0x04 /* pop out */ int swap_pager_full; /* swap space exhaustion (task killing) */ static int swap_pager_almost_full; /* swap space exhaustion (w/ hysteresis)*/ static int nsw_rcount; /* free read buffers */ static int nsw_wcount_sync; /* limit write buffers / synchronous */ static int nsw_wcount_async; /* limit write buffers / asynchronous */ static int nsw_wcount_async_max;/* assigned maximum */ static int nsw_cluster_max; /* maximum VOP I/O allowed */ static struct swblock **swhash; static int swhash_mask; static int swap_async_max = 4; /* maximum in-progress async I/O's */ static struct sx sw_alloc_sx; SYSCTL_INT(_vm, OID_AUTO, swap_async_max, CTLFLAG_RW, &swap_async_max, 0, "Maximum running async swap ops"); /* * "named" and "unnamed" anon region objects. Try to reduce the overhead * of searching a named list by hashing it just a little. */ #define NOBJLISTS 8 #define NOBJLIST(handle) \ (&swap_pager_object_list[((int)(intptr_t)handle >> 4) & (NOBJLISTS-1)]) static struct mtx sw_alloc_mtx; /* protect list manipulation */ static struct pagerlst swap_pager_object_list[NOBJLISTS]; static struct pagerlst swap_pager_un_object_list; static uma_zone_t swap_zone; /* * pagerops for OBJT_SWAP - "swap pager". Some ops are also global procedure * calls hooked from other parts of the VM system and do not appear here. * (see vm/swap_pager.h). */ static vm_object_t swap_pager_alloc(void *handle, vm_ooffset_t size, vm_prot_t prot, vm_ooffset_t offset); static void swap_pager_dealloc(vm_object_t object); static int swap_pager_getpages(vm_object_t, vm_page_t *, int, int); static boolean_t swap_pager_haspage(vm_object_t object, vm_pindex_t pindex, int *before, int *after); static void swap_pager_init(void); static void swap_pager_unswapped(vm_page_t); static void swap_pager_swapoff(struct swdevt *sp, int *sw_used); struct pagerops swappagerops = { .pgo_init = swap_pager_init, /* early system initialization of pager */ .pgo_alloc = swap_pager_alloc, /* allocate an OBJT_SWAP object */ .pgo_dealloc = swap_pager_dealloc, /* deallocate an OBJT_SWAP object */ .pgo_getpages = swap_pager_getpages, /* pagein */ .pgo_putpages = swap_pager_putpages, /* pageout */ .pgo_haspage = swap_pager_haspage, /* get backing store status for page */ .pgo_pageunswapped = swap_pager_unswapped, /* remove swap related to page */ }; /* * dmmax is in page-sized chunks with the new swap system. It was * dev-bsized chunks in the old. dmmax is always a power of 2. * * swap_*() routines are externally accessible. swp_*() routines are * internal. */ static int dmmax, dmmax_mask; static int nswap_lowat = 128; /* in pages, swap_pager_almost_full warn */ static int nswap_hiwat = 512; /* in pages, swap_pager_almost_full warn */ SYSCTL_INT(_vm, OID_AUTO, dmmax, CTLFLAG_RD, &dmmax, 0, "Maximum size of a swap block"); static void swp_sizecheck(void); static void swp_pager_sync_iodone(struct buf *bp); static void swp_pager_async_iodone(struct buf *bp); /* * Swap bitmap functions */ static void swp_pager_freeswapspace(daddr_t blk, int npages); static daddr_t swp_pager_getswapspace(int npages); /* * Metadata functions */ static struct swblock **swp_pager_hash(vm_object_t object, vm_pindex_t index); static void swp_pager_meta_build(vm_object_t, vm_pindex_t, daddr_t); static void swp_pager_meta_free(vm_object_t, vm_pindex_t, daddr_t); static void swp_pager_meta_free_all(vm_object_t); static daddr_t swp_pager_meta_ctl(vm_object_t, vm_pindex_t, int); /* * SWP_SIZECHECK() - update swap_pager_full indication * * update the swap_pager_almost_full indication and warn when we are * about to run out of swap space, using lowat/hiwat hysteresis. * * Clear swap_pager_full ( task killing ) indication when lowat is met. * * No restrictions on call * This routine may not block. * This routine must be called at splvm() */ static void swp_sizecheck() { GIANT_REQUIRED; if (swap_pager_avail < nswap_lowat) { if (swap_pager_almost_full == 0) { printf("swap_pager: out of swap space\n"); swap_pager_almost_full = 1; } } else { swap_pager_full = 0; if (swap_pager_avail > nswap_hiwat) swap_pager_almost_full = 0; } } /* * SWP_PAGER_HASH() - hash swap meta data * * This is an helper function which hashes the swapblk given * the object and page index. It returns a pointer to a pointer * to the object, or a pointer to a NULL pointer if it could not * find a swapblk. * * This routine must be called at splvm(). */ static struct swblock ** swp_pager_hash(vm_object_t object, vm_pindex_t index) { struct swblock **pswap; struct swblock *swap; index &= ~(vm_pindex_t)SWAP_META_MASK; pswap = &swhash[(index ^ (int)(intptr_t)object) & swhash_mask]; while ((swap = *pswap) != NULL) { if (swap->swb_object == object && swap->swb_index == index ) { break; } pswap = &swap->swb_hnext; } return (pswap); } /* * SWAP_PAGER_INIT() - initialize the swap pager! * * Expected to be started from system init. NOTE: This code is run * before much else so be careful what you depend on. Most of the VM * system has yet to be initialized at this point. */ static void swap_pager_init() { /* * Initialize object lists */ int i; for (i = 0; i < NOBJLISTS; ++i) TAILQ_INIT(&swap_pager_object_list[i]); TAILQ_INIT(&swap_pager_un_object_list); mtx_init(&sw_alloc_mtx, "swap_pager list", NULL, MTX_DEF); /* * Device Stripe, in PAGE_SIZE'd blocks */ dmmax = SWB_NPAGES * 2; dmmax_mask = ~(dmmax - 1); } /* * SWAP_PAGER_SWAP_INIT() - swap pager initialization from pageout process * * Expected to be started from pageout process once, prior to entering * its main loop. */ void swap_pager_swap_init() { int n, n2; /* * Number of in-transit swap bp operations. Don't * exhaust the pbufs completely. Make sure we * initialize workable values (0 will work for hysteresis * but it isn't very efficient). * * The nsw_cluster_max is constrained by the bp->b_pages[] * array (MAXPHYS/PAGE_SIZE) and our locally defined * MAX_PAGEOUT_CLUSTER. Also be aware that swap ops are * constrained by the swap device interleave stripe size. * * Currently we hardwire nsw_wcount_async to 4. This limit is * designed to prevent other I/O from having high latencies due to * our pageout I/O. The value 4 works well for one or two active swap * devices but is probably a little low if you have more. Even so, * a higher value would probably generate only a limited improvement * with three or four active swap devices since the system does not * typically have to pageout at extreme bandwidths. We will want * at least 2 per swap devices, and 4 is a pretty good value if you * have one NFS swap device due to the command/ack latency over NFS. * So it all works out pretty well. */ nsw_cluster_max = min((MAXPHYS/PAGE_SIZE), MAX_PAGEOUT_CLUSTER); mtx_lock(&pbuf_mtx); nsw_rcount = (nswbuf + 1) / 2; nsw_wcount_sync = (nswbuf + 3) / 4; nsw_wcount_async = 4; nsw_wcount_async_max = nsw_wcount_async; mtx_unlock(&pbuf_mtx); /* * Initialize our zone. Right now I'm just guessing on the number * we need based on the number of pages in the system. Each swblock * can hold 16 pages, so this is probably overkill. This reservation * is typically limited to around 32MB by default. */ n = cnt.v_page_count / 2; if (maxswzone && n > maxswzone / sizeof(struct swblock)) n = maxswzone / sizeof(struct swblock); n2 = n; swap_zone = uma_zcreate("SWAPMETA", sizeof(struct swblock), NULL, NULL, NULL, NULL, UMA_ALIGN_PTR, UMA_ZONE_NOFREE); do { if (uma_zone_set_obj(swap_zone, NULL, n)) break; /* * if the allocation failed, try a zone two thirds the * size of the previous attempt. */ n -= ((n + 2) / 3); } while (n > 0); if (swap_zone == NULL) panic("failed to create swap_zone."); if (n2 != n) printf("Swap zone entries reduced from %d to %d.\n", n2, n); n2 = n; /* * Initialize our meta-data hash table. The swapper does not need to * be quite as efficient as the VM system, so we do not use an * oversized hash table. * * n: size of hash table, must be power of 2 * swhash_mask: hash table index mask */ for (n = 1; n < n2 / 8; n *= 2) ; swhash = malloc(sizeof(struct swblock *) * n, M_VMPGDATA, M_WAITOK | M_ZERO); swhash_mask = n - 1; } /* * SWAP_PAGER_ALLOC() - allocate a new OBJT_SWAP VM object and instantiate * its metadata structures. * * This routine is called from the mmap and fork code to create a new * OBJT_SWAP object. We do this by creating an OBJT_DEFAULT object * and then converting it with swp_pager_meta_build(). * * This routine may block in vm_object_allocate() and create a named * object lookup race, so we must interlock. We must also run at * splvm() for the object lookup to handle races with interrupts, but * we do not have to maintain splvm() in between the lookup and the * add because (I believe) it is not possible to attempt to create * a new swap object w/handle when a default object with that handle * already exists. * * MPSAFE */ static vm_object_t swap_pager_alloc(void *handle, vm_ooffset_t size, vm_prot_t prot, vm_ooffset_t offset) { vm_object_t object; mtx_lock(&Giant); if (handle) { /* * Reference existing named region or allocate new one. There * should not be a race here against swp_pager_meta_build() * as called from vm_page_remove() in regards to the lookup * of the handle. */ sx_xlock(&sw_alloc_sx); object = vm_pager_object_lookup(NOBJLIST(handle), handle); if (object != NULL) { vm_object_reference(object); } else { object = vm_object_allocate(OBJT_DEFAULT, OFF_TO_IDX(offset + PAGE_MASK + size)); object->handle = handle; swp_pager_meta_build(object, 0, SWAPBLK_NONE); } sx_xunlock(&sw_alloc_sx); } else { object = vm_object_allocate(OBJT_DEFAULT, OFF_TO_IDX(offset + PAGE_MASK + size)); swp_pager_meta_build(object, 0, SWAPBLK_NONE); } mtx_unlock(&Giant); return (object); } /* * SWAP_PAGER_DEALLOC() - remove swap metadata from object * * The swap backing for the object is destroyed. The code is * designed such that we can reinstantiate it later, but this * routine is typically called only when the entire object is * about to be destroyed. * * This routine may block, but no longer does. * * The object must be locked or unreferenceable. */ static void swap_pager_dealloc(object) vm_object_t object; { int s; GIANT_REQUIRED; /* * Remove from list right away so lookups will fail if we block for * pageout completion. */ mtx_lock(&sw_alloc_mtx); if (object->handle == NULL) { TAILQ_REMOVE(&swap_pager_un_object_list, object, pager_object_list); } else { TAILQ_REMOVE(NOBJLIST(object->handle), object, pager_object_list); } mtx_unlock(&sw_alloc_mtx); VM_OBJECT_LOCK_ASSERT(object, MA_OWNED); vm_object_pip_wait(object, "swpdea"); /* * Free all remaining metadata. We only bother to free it from * the swap meta data. We do not attempt to free swapblk's still * associated with vm_page_t's for this object. We do not care * if paging is still in progress on some objects. */ s = splvm(); swp_pager_meta_free_all(object); splx(s); } /************************************************************************ * SWAP PAGER BITMAP ROUTINES * ************************************************************************/ /* * SWP_PAGER_GETSWAPSPACE() - allocate raw swap space * * Allocate swap for the requested number of pages. The starting * swap block number (a page index) is returned or SWAPBLK_NONE * if the allocation failed. * * Also has the side effect of advising that somebody made a mistake * when they configured swap and didn't configure enough. * * Must be called at splvm() to avoid races with bitmap frees from * vm_page_remove() aka swap_pager_page_removed(). * * This routine may not block * This routine must be called at splvm(). * * We allocate in round-robin fashion from the configured devices. */ static daddr_t swp_pager_getswapspace(npages) int npages; { daddr_t blk; struct swdevt *sp; int i; GIANT_REQUIRED; blk = SWAPBLK_NONE; sp = swdevhd; for (i = 0; i < nswapdev; i++) { if (sp == NULL) sp = TAILQ_FIRST(&swtailq); if (!(sp->sw_flags & SW_CLOSING)) { blk = blist_alloc(sp->sw_blist, npages); if (blk != SWAPBLK_NONE) { blk += sp->sw_first; swap_pager_avail -= npages; sp->sw_used += npages; swp_sizecheck(); swdevhd = TAILQ_NEXT(sp, sw_list); return(blk); } } sp = TAILQ_NEXT(sp, sw_list); } if (swap_pager_full != 2) { printf("swap_pager_getswapspace: failed\n"); swap_pager_full = 2; swap_pager_almost_full = 1; } swdevhd = NULL; return (blk); } static struct swdevt * swp_pager_find_dev(daddr_t blk, int npages) { struct swdevt *sp; TAILQ_FOREACH(sp, &swtailq, sw_list) { if (blk >= sp->sw_first && blk + npages <= sp->sw_end) return (sp); } printf("Failed to find swapdev blk %ju, %d pages\n", (uintmax_t)blk, npages); TAILQ_FOREACH(sp, &swtailq, sw_list) printf("has %ju...%ju\n", (uintmax_t)sp->sw_first, (uintmax_t)sp->sw_end); return (NULL); } /* * SWP_PAGER_FREESWAPSPACE() - free raw swap space * * This routine returns the specified swap blocks back to the bitmap. * * Note: This routine may not block (it could in the old swap code), * and through the use of the new blist routines it does not block. * * We must be called at splvm() to avoid races with bitmap frees from * vm_page_remove() aka swap_pager_page_removed(). * * This routine may not block * This routine must be called at splvm(). */ static void swp_pager_freeswapspace(daddr_t blk, int npages) { struct swdevt *sp; GIANT_REQUIRED; sp = swp_pager_find_dev(blk, npages); /* per-swap area stats */ sp->sw_used -= npages; /* * If we are attempting to stop swapping on this device, we * don't want to mark any blocks free lest they be reused. */ if (sp->sw_flags & SW_CLOSING) return; blist_free(sp->sw_blist, blk - sp->sw_first, npages); swap_pager_avail += npages; swp_sizecheck(); } /* * SWAP_PAGER_FREESPACE() - frees swap blocks associated with a page * range within an object. * * This is a globally accessible routine. * * This routine removes swapblk assignments from swap metadata. * * The external callers of this routine typically have already destroyed * or renamed vm_page_t's associated with this range in the object so * we should be ok. * * This routine may be called at any spl. We up our spl to splvm temporarily * in order to perform the metadata removal. */ void swap_pager_freespace(object, start, size) vm_object_t object; vm_pindex_t start; vm_size_t size; { int s = splvm(); VM_OBJECT_LOCK_ASSERT(object, MA_OWNED); swp_pager_meta_free(object, start, size); splx(s); } /* * SWAP_PAGER_RESERVE() - reserve swap blocks in object * * Assigns swap blocks to the specified range within the object. The * swap blocks are not zerod. Any previous swap assignment is destroyed. * * Returns 0 on success, -1 on failure. */ int swap_pager_reserve(vm_object_t object, vm_pindex_t start, vm_size_t size) { int s; int n = 0; daddr_t blk = SWAPBLK_NONE; vm_pindex_t beg = start; /* save start index */ s = splvm(); while (size) { if (n == 0) { n = BLIST_MAX_ALLOC; while ((blk = swp_pager_getswapspace(n)) == SWAPBLK_NONE) { n >>= 1; if (n == 0) { swp_pager_meta_free(object, beg, start - beg); splx(s); return (-1); } } } swp_pager_meta_build(object, start, blk); --size; ++start; ++blk; --n; } swp_pager_meta_free(object, start, n); splx(s); return (0); } /* * SWAP_PAGER_COPY() - copy blocks from source pager to destination pager * and destroy the source. * * Copy any valid swapblks from the source to the destination. In * cases where both the source and destination have a valid swapblk, * we keep the destination's. * * This routine is allowed to block. It may block allocating metadata * indirectly through swp_pager_meta_build() or if paging is still in * progress on the source. * * This routine can be called at any spl * * XXX vm_page_collapse() kinda expects us not to block because we * supposedly do not need to allocate memory, but for the moment we * *may* have to get a little memory from the zone allocator, but * it is taken from the interrupt memory. We should be ok. * * The source object contains no vm_page_t's (which is just as well) * * The source object is of type OBJT_SWAP. * * The source and destination objects must be locked or * inaccessible (XXX are they ?) */ void swap_pager_copy(srcobject, dstobject, offset, destroysource) vm_object_t srcobject; vm_object_t dstobject; vm_pindex_t offset; int destroysource; { vm_pindex_t i; int s; GIANT_REQUIRED; s = splvm(); /* * If destroysource is set, we remove the source object from the * swap_pager internal queue now. */ if (destroysource) { mtx_lock(&sw_alloc_mtx); if (srcobject->handle == NULL) { TAILQ_REMOVE( &swap_pager_un_object_list, srcobject, pager_object_list ); } else { TAILQ_REMOVE( NOBJLIST(srcobject->handle), srcobject, pager_object_list ); } mtx_unlock(&sw_alloc_mtx); } /* * transfer source to destination. */ for (i = 0; i < dstobject->size; ++i) { daddr_t dstaddr; /* * Locate (without changing) the swapblk on the destination, * unless it is invalid in which case free it silently, or * if the destination is a resident page, in which case the * source is thrown away. */ dstaddr = swp_pager_meta_ctl(dstobject, i, 0); if (dstaddr == SWAPBLK_NONE) { /* * Destination has no swapblk and is not resident, * copy source. */ daddr_t srcaddr; srcaddr = swp_pager_meta_ctl( srcobject, i + offset, SWM_POP ); if (srcaddr != SWAPBLK_NONE) swp_pager_meta_build(dstobject, i, srcaddr); } else { /* * Destination has valid swapblk or it is represented * by a resident page. We destroy the sourceblock. */ swp_pager_meta_ctl(srcobject, i + offset, SWM_FREE); } } /* * Free left over swap blocks in source. * * We have to revert the type to OBJT_DEFAULT so we do not accidently * double-remove the object from the swap queues. */ if (destroysource) { swp_pager_meta_free_all(srcobject); /* * Reverting the type is not necessary, the caller is going * to destroy srcobject directly, but I'm doing it here * for consistency since we've removed the object from its * queues. */ srcobject->type = OBJT_DEFAULT; } splx(s); } /* * SWAP_PAGER_HASPAGE() - determine if we have good backing store for * the requested page. * * We determine whether good backing store exists for the requested * page and return TRUE if it does, FALSE if it doesn't. * * If TRUE, we also try to determine how much valid, contiguous backing * store exists before and after the requested page within a reasonable * distance. We do not try to restrict it to the swap device stripe * (that is handled in getpages/putpages). It probably isn't worth * doing here. */ static boolean_t swap_pager_haspage(object, pindex, before, after) vm_object_t object; vm_pindex_t pindex; int *before; int *after; { daddr_t blk0; int s; /* * do we have good backing store at the requested index ? */ s = splvm(); blk0 = swp_pager_meta_ctl(object, pindex, 0); if (blk0 == SWAPBLK_NONE) { splx(s); if (before) *before = 0; if (after) *after = 0; return (FALSE); } /* * find backwards-looking contiguous good backing store */ if (before != NULL) { int i; for (i = 1; i < (SWB_NPAGES/2); ++i) { daddr_t blk; if (i > pindex) break; blk = swp_pager_meta_ctl(object, pindex - i, 0); if (blk != blk0 - i) break; } *before = (i - 1); } /* * find forward-looking contiguous good backing store */ if (after != NULL) { int i; for (i = 1; i < (SWB_NPAGES/2); ++i) { daddr_t blk; blk = swp_pager_meta_ctl(object, pindex + i, 0); if (blk != blk0 + i) break; } *after = (i - 1); } splx(s); return (TRUE); } /* * SWAP_PAGER_PAGE_UNSWAPPED() - remove swap backing store related to page * * This removes any associated swap backing store, whether valid or * not, from the page. * * This routine is typically called when a page is made dirty, at * which point any associated swap can be freed. MADV_FREE also * calls us in a special-case situation * * NOTE!!! If the page is clean and the swap was valid, the caller * should make the page dirty before calling this routine. This routine * does NOT change the m->dirty status of the page. Also: MADV_FREE * depends on it. * * This routine may not block * This routine must be called at splvm() */ static void swap_pager_unswapped(m) vm_page_t m; { swp_pager_meta_ctl(m->object, m->pindex, SWM_FREE); } /* * SWAP_PAGER_GETPAGES() - bring pages in from swap * * Attempt to retrieve (m, count) pages from backing store, but make * sure we retrieve at least m[reqpage]. We try to load in as large * a chunk surrounding m[reqpage] as is contiguous in swap and which * belongs to the same object. * * The code is designed for asynchronous operation and * immediate-notification of 'reqpage' but tends not to be * used that way. Please do not optimize-out this algorithmic * feature, I intend to improve on it in the future. * * The parent has a single vm_object_pip_add() reference prior to * calling us and we should return with the same. * * The parent has BUSY'd the pages. We should return with 'm' * left busy, but the others adjusted. */ static int swap_pager_getpages(object, m, count, reqpage) vm_object_t object; vm_page_t *m; int count, reqpage; { struct buf *bp; vm_page_t mreq; int s; int i; int j; daddr_t blk; vm_pindex_t lastpindex; mreq = m[reqpage]; KASSERT(mreq->object == object, ("swap_pager_getpages: object mismatch %p/%p", object, mreq->object)); /* * Calculate range to retrieve. The pages have already been assigned * their swapblks. We require a *contiguous* range that falls entirely * within a single device stripe. If we do not supply it, bad things * happen. Note that blk, iblk & jblk can be SWAPBLK_NONE, but the * loops are set up such that the case(s) are handled implicitly. * * The swp_*() calls must be made at splvm(). vm_page_free() does * not need to be, but it will go a little faster if it is. */ s = splvm(); blk = swp_pager_meta_ctl(mreq->object, mreq->pindex, 0); for (i = reqpage - 1; i >= 0; --i) { daddr_t iblk; iblk = swp_pager_meta_ctl(m[i]->object, m[i]->pindex, 0); if (blk != iblk + (reqpage - i)) break; if ((blk ^ iblk) & dmmax_mask) break; } ++i; for (j = reqpage + 1; j < count; ++j) { daddr_t jblk; jblk = swp_pager_meta_ctl(m[j]->object, m[j]->pindex, 0); if (blk != jblk - (j - reqpage)) break; if ((blk ^ jblk) & dmmax_mask) break; } /* * free pages outside our collection range. Note: we never free * mreq, it must remain busy throughout. */ vm_page_lock_queues(); { int k; for (k = 0; k < i; ++k) vm_page_free(m[k]); for (k = j; k < count; ++k) vm_page_free(m[k]); } vm_page_unlock_queues(); splx(s); /* * Return VM_PAGER_FAIL if we have nothing to do. Return mreq * still busy, but the others unbusied. */ if (blk == SWAPBLK_NONE) return (VM_PAGER_FAIL); /* * Getpbuf() can sleep. */ VM_OBJECT_UNLOCK(object); /* * Get a swap buffer header to perform the IO */ bp = getpbuf(&nsw_rcount); /* * map our page(s) into kva for input * * NOTE: B_PAGING is set by pbgetvp() */ pmap_qenter((vm_offset_t)bp->b_data, m + i, j - i); bp->b_iocmd = BIO_READ; bp->b_iodone = swp_pager_async_iodone; bp->b_rcred = crhold(thread0.td_ucred); bp->b_wcred = crhold(thread0.td_ucred); bp->b_blkno = blk - (reqpage - i); bp->b_bcount = PAGE_SIZE * (j - i); bp->b_bufsize = PAGE_SIZE * (j - i); bp->b_pager.pg_reqpage = reqpage - i; VM_OBJECT_LOCK(object); vm_page_lock_queues(); { int k; for (k = i; k < j; ++k) { bp->b_pages[k - i] = m[k]; vm_page_flag_set(m[k], PG_SWAPINPROG); } } vm_page_unlock_queues(); VM_OBJECT_UNLOCK(object); bp->b_npages = j - i; cnt.v_swapin++; cnt.v_swappgsin += bp->b_npages; /* * We still hold the lock on mreq, and our automatic completion routine * does not remove it. */ VM_OBJECT_LOCK(mreq->object); vm_object_pip_add(mreq->object, bp->b_npages); VM_OBJECT_UNLOCK(mreq->object); lastpindex = m[j-1]->pindex; /* * perform the I/O. NOTE!!! bp cannot be considered valid after * this point because we automatically release it on completion. * Instead, we look at the one page we are interested in which we * still hold a lock on even through the I/O completion. * * The other pages in our m[] array are also released on completion, * so we cannot assume they are valid anymore either. * * NOTE: b_blkno is destroyed by the call to swapdev_strategy */ BUF_KERNPROC(bp); swapdev_strategy(bp); /* * wait for the page we want to complete. PG_SWAPINPROG is always * cleared on completion. If an I/O error occurs, SWAPBLK_NONE * is set in the meta-data. */ s = splvm(); vm_page_lock_queues(); while ((mreq->flags & PG_SWAPINPROG) != 0) { vm_page_flag_set(mreq, PG_WANTED | PG_REFERENCED); cnt.v_intrans++; if (msleep(mreq, &vm_page_queue_mtx, PSWP, "swread", hz*20)) { printf( "swap_pager: indefinite wait buffer: device:" " %s, blkno: %ld, size: %ld\n", devtoname(bp->b_dev), (long)bp->b_blkno, bp->b_bcount ); } } vm_page_unlock_queues(); splx(s); VM_OBJECT_LOCK(mreq->object); /* * mreq is left busied after completion, but all the other pages * are freed. If we had an unrecoverable read error the page will * not be valid. */ if (mreq->valid != VM_PAGE_BITS_ALL) { return (VM_PAGER_ERROR); } else { return (VM_PAGER_OK); } /* * A final note: in a low swap situation, we cannot deallocate swap * and mark a page dirty here because the caller is likely to mark * the page clean when we return, causing the page to possibly revert * to all-zero's later. */ } /* * swap_pager_putpages: * * Assign swap (if necessary) and initiate I/O on the specified pages. * * We support both OBJT_DEFAULT and OBJT_SWAP objects. DEFAULT objects * are automatically converted to SWAP objects. * * In a low memory situation we may block in VOP_STRATEGY(), but the new * vm_page reservation system coupled with properly written VFS devices * should ensure that no low-memory deadlock occurs. This is an area * which needs work. * * The parent has N vm_object_pip_add() references prior to * calling us and will remove references for rtvals[] that are * not set to VM_PAGER_PEND. We need to remove the rest on I/O * completion. * * The parent has soft-busy'd the pages it passes us and will unbusy * those whos rtvals[] entry is not set to VM_PAGER_PEND on return. * We need to unbusy the rest on I/O completion. */ void swap_pager_putpages(object, m, count, sync, rtvals) vm_object_t object; vm_page_t *m; int count; boolean_t sync; int *rtvals; { int i; int n = 0; GIANT_REQUIRED; if (count && m[0]->object != object) { panic("swap_pager_getpages: object mismatch %p/%p", object, m[0]->object ); } /* * Step 1 * * Turn object into OBJT_SWAP * check for bogus sysops * force sync if not pageout process */ if (object->type != OBJT_SWAP) swp_pager_meta_build(object, 0, SWAPBLK_NONE); if (curproc != pageproc) sync = TRUE; /* * Step 2 * * Update nsw parameters from swap_async_max sysctl values. * Do not let the sysop crash the machine with bogus numbers. */ mtx_lock(&pbuf_mtx); if (swap_async_max != nsw_wcount_async_max) { int n; int s; /* * limit range */ if ((n = swap_async_max) > nswbuf / 2) n = nswbuf / 2; if (n < 1) n = 1; swap_async_max = n; /* * Adjust difference ( if possible ). If the current async * count is too low, we may not be able to make the adjustment * at this time. */ s = splvm(); n -= nsw_wcount_async_max; if (nsw_wcount_async + n >= 0) { nsw_wcount_async += n; nsw_wcount_async_max += n; wakeup(&nsw_wcount_async); } splx(s); } mtx_unlock(&pbuf_mtx); /* * Step 3 * * Assign swap blocks and issue I/O. We reallocate swap on the fly. * The page is left dirty until the pageout operation completes * successfully. */ for (i = 0; i < count; i += n) { int s; int j; struct buf *bp; daddr_t blk; /* * Maximum I/O size is limited by a number of factors. */ n = min(BLIST_MAX_ALLOC, count - i); n = min(n, nsw_cluster_max); s = splvm(); /* * Get biggest block of swap we can. If we fail, fall * back and try to allocate a smaller block. Don't go * overboard trying to allocate space if it would overly * fragment swap. */ while ( (blk = swp_pager_getswapspace(n)) == SWAPBLK_NONE && n > 4 ) { n >>= 1; } if (blk == SWAPBLK_NONE) { for (j = 0; j < n; ++j) rtvals[i+j] = VM_PAGER_FAIL; splx(s); continue; } /* * The I/O we are constructing cannot cross a physical * disk boundry in the swap stripe. Note: we are still * at splvm(). */ if ((blk ^ (blk + n)) & dmmax_mask) { j = ((blk + dmmax) & dmmax_mask) - blk; swp_pager_freeswapspace(blk + j, n - j); n = j; } /* * All I/O parameters have been satisfied, build the I/O * request and assign the swap space. * * NOTE: B_PAGING is set by pbgetvp() */ if (sync == TRUE) { bp = getpbuf(&nsw_wcount_sync); } else { bp = getpbuf(&nsw_wcount_async); bp->b_flags = B_ASYNC; } bp->b_iocmd = BIO_WRITE; pmap_qenter((vm_offset_t)bp->b_data, &m[i], n); bp->b_rcred = crhold(thread0.td_ucred); bp->b_wcred = crhold(thread0.td_ucred); bp->b_bcount = PAGE_SIZE * n; bp->b_bufsize = PAGE_SIZE * n; bp->b_blkno = blk; for (j = 0; j < n; ++j) { vm_page_t mreq = m[i+j]; swp_pager_meta_build( mreq->object, mreq->pindex, blk + j ); vm_page_dirty(mreq); rtvals[i+j] = VM_PAGER_OK; vm_page_lock_queues(); vm_page_flag_set(mreq, PG_SWAPINPROG); vm_page_unlock_queues(); bp->b_pages[j] = mreq; } bp->b_npages = n; /* * Must set dirty range for NFS to work. */ bp->b_dirtyoff = 0; bp->b_dirtyend = bp->b_bcount; cnt.v_swapout++; cnt.v_swappgsout += bp->b_npages; splx(s); /* * asynchronous * * NOTE: b_blkno is destroyed by the call to swapdev_strategy */ if (sync == FALSE) { bp->b_iodone = swp_pager_async_iodone; BUF_KERNPROC(bp); swapdev_strategy(bp); for (j = 0; j < n; ++j) rtvals[i+j] = VM_PAGER_PEND; /* restart outter loop */ continue; } /* * synchronous * * NOTE: b_blkno is destroyed by the call to swapdev_strategy */ bp->b_iodone = swp_pager_sync_iodone; swapdev_strategy(bp); /* * Wait for the sync I/O to complete, then update rtvals. * We just set the rtvals[] to VM_PAGER_PEND so we can call * our async completion routine at the end, thus avoiding a * double-free. */ s = splbio(); while ((bp->b_flags & B_DONE) == 0) { tsleep(bp, PVM, "swwrt", 0); } for (j = 0; j < n; ++j) rtvals[i+j] = VM_PAGER_PEND; /* * Now that we are through with the bp, we can call the * normal async completion, which frees everything up. */ swp_pager_async_iodone(bp); splx(s); } } /* * swap_pager_sync_iodone: * * Completion routine for synchronous reads and writes from/to swap. * We just mark the bp is complete and wake up anyone waiting on it. * * This routine may not block. This routine is called at splbio() or better. */ static void swp_pager_sync_iodone(bp) struct buf *bp; { bp->b_flags |= B_DONE; bp->b_flags &= ~B_ASYNC; wakeup(bp); } /* * swp_pager_async_iodone: * * Completion routine for asynchronous reads and writes from/to swap. * Also called manually by synchronous code to finish up a bp. * * For READ operations, the pages are PG_BUSY'd. For WRITE operations, * the pages are vm_page_t->busy'd. For READ operations, we PG_BUSY * unbusy all pages except the 'main' request page. For WRITE * operations, we vm_page_t->busy'd unbusy all pages ( we can do this * because we marked them all VM_PAGER_PEND on return from putpages ). * * This routine may not block. * This routine is called at splbio() or better * * We up ourselves to splvm() as required for various vm_page related * calls. */ static void swp_pager_async_iodone(bp) struct buf *bp; { int s; int i; vm_object_t object = NULL; GIANT_REQUIRED; bp->b_flags |= B_DONE; /* * report error */ if (bp->b_ioflags & BIO_ERROR) { printf( "swap_pager: I/O error - %s failed; blkno %ld," "size %ld, error %d\n", ((bp->b_iocmd == BIO_READ) ? "pagein" : "pageout"), (long)bp->b_blkno, (long)bp->b_bcount, bp->b_error ); } /* * set object, raise to splvm(). */ s = splvm(); /* * remove the mapping for kernel virtual */ pmap_qremove((vm_offset_t)bp->b_data, bp->b_npages); if (bp->b_npages) { object = bp->b_pages[0]->object; VM_OBJECT_LOCK(object); } vm_page_lock_queues(); /* * cleanup pages. If an error occurs writing to swap, we are in * very serious trouble. If it happens to be a disk error, though, * we may be able to recover by reassigning the swap later on. So * in this case we remove the m->swapblk assignment for the page * but do not free it in the rlist. The errornous block(s) are thus * never reallocated as swap. Redirty the page and continue. */ for (i = 0; i < bp->b_npages; ++i) { vm_page_t m = bp->b_pages[i]; vm_page_flag_clear(m, PG_SWAPINPROG); if (bp->b_ioflags & BIO_ERROR) { /* * If an error occurs I'd love to throw the swapblk * away without freeing it back to swapspace, so it * can never be used again. But I can't from an * interrupt. */ if (bp->b_iocmd == BIO_READ) { /* * When reading, reqpage needs to stay * locked for the parent, but all other * pages can be freed. We still want to * wakeup the parent waiting on the page, * though. ( also: pg_reqpage can be -1 and * not match anything ). * * We have to wake specifically requested pages * up too because we cleared PG_SWAPINPROG and * someone may be waiting for that. * * NOTE: for reads, m->dirty will probably * be overridden by the original caller of * getpages so don't play cute tricks here. * * XXX IT IS NOT LEGAL TO FREE THE PAGE HERE * AS THIS MESSES WITH object->memq, and it is * not legal to mess with object->memq from an * interrupt. */ m->valid = 0; vm_page_flag_clear(m, PG_ZERO); if (i != bp->b_pager.pg_reqpage) vm_page_free(m); else vm_page_flash(m); /* * If i == bp->b_pager.pg_reqpage, do not wake * the page up. The caller needs to. */ } else { /* * If a write error occurs, reactivate page * so it doesn't clog the inactive list, * then finish the I/O. */ vm_page_dirty(m); vm_page_activate(m); vm_page_io_finish(m); } } else if (bp->b_iocmd == BIO_READ) { /* * For read success, clear dirty bits. Nobody should * have this page mapped but don't take any chances, * make sure the pmap modify bits are also cleared. * * NOTE: for reads, m->dirty will probably be * overridden by the original caller of getpages so * we cannot set them in order to free the underlying * swap in a low-swap situation. I don't think we'd * want to do that anyway, but it was an optimization * that existed in the old swapper for a time before * it got ripped out due to precisely this problem. * * clear PG_ZERO in page. * * If not the requested page then deactivate it. * * Note that the requested page, reqpage, is left * busied, but we still have to wake it up. The * other pages are released (unbusied) by * vm_page_wakeup(). We do not set reqpage's * valid bits here, it is up to the caller. */ pmap_clear_modify(m); m->valid = VM_PAGE_BITS_ALL; vm_page_undirty(m); vm_page_flag_clear(m, PG_ZERO); /* * We have to wake specifically requested pages * up too because we cleared PG_SWAPINPROG and * could be waiting for it in getpages. However, * be sure to not unbusy getpages specifically * requested page - getpages expects it to be * left busy. */ if (i != bp->b_pager.pg_reqpage) { vm_page_deactivate(m); vm_page_wakeup(m); } else { vm_page_flash(m); } } else { /* * For write success, clear the modify and dirty * status, then finish the I/O ( which decrements the * busy count and possibly wakes waiter's up ). */ pmap_clear_modify(m); vm_page_undirty(m); vm_page_io_finish(m); if (!vm_page_count_severe() || !vm_page_try_to_cache(m)) pmap_page_protect(m, VM_PROT_READ); } } vm_page_unlock_queues(); /* * adjust pip. NOTE: the original parent may still have its own * pip refs on the object. */ if (object != NULL) { vm_object_pip_wakeupn(object, bp->b_npages); VM_OBJECT_UNLOCK(object); } /* * release the physical I/O buffer */ relpbuf( bp, ((bp->b_iocmd == BIO_READ) ? &nsw_rcount : ((bp->b_flags & B_ASYNC) ? &nsw_wcount_async : &nsw_wcount_sync ) ) ); splx(s); } /* * swap_pager_isswapped: * * Return 1 if at least one page in the given object is paged * out to the given swap device. * * This routine may not block. */ int swap_pager_isswapped(vm_object_t object, struct swdevt *sp) { daddr_t index = 0; int bcount; int i; VM_OBJECT_LOCK_ASSERT(object, MA_OWNED); for (bcount = 0; bcount < object->un_pager.swp.swp_bcount; bcount++) { struct swblock *swap; if ((swap = *swp_pager_hash(object, index)) != NULL) { for (i = 0; i < SWAP_META_PAGES; ++i) { daddr_t v = swap->swb_pages[i]; if (v == SWAPBLK_NONE) continue; if (swp_pager_find_dev(v, 1) == sp) return 1; } } index += SWAP_META_PAGES; if (index > 0x20000000) panic("swap_pager_isswapped: failed to locate all swap meta blocks"); } return 0; } /* * SWP_PAGER_FORCE_PAGEIN() - force a swap block to be paged in * * This routine dissociates the page at the given index within a * swap block from its backing store, paging it in if necessary. * If the page is paged in, it is placed in the inactive queue, * since it had its backing store ripped out from under it. * We also attempt to swap in all other pages in the swap block, * we only guarantee that the one at the specified index is * paged in. * * XXX - The code to page the whole block in doesn't work, so we * revert to the one-by-one behavior for now. Sigh. */ static __inline void swp_pager_force_pagein(struct swblock *swap, int idx) { vm_object_t object; vm_page_t m; vm_pindex_t pindex; object = swap->swb_object; pindex = swap->swb_index; VM_OBJECT_LOCK(object); vm_object_pip_add(object, 1); m = vm_page_grab(object, pindex + idx, VM_ALLOC_NORMAL|VM_ALLOC_RETRY); if (m->valid == VM_PAGE_BITS_ALL) { vm_object_pip_subtract(object, 1); VM_OBJECT_UNLOCK(object); vm_page_lock_queues(); vm_page_activate(m); vm_page_dirty(m); vm_page_wakeup(m); vm_page_unlock_queues(); vm_pager_page_unswapped(m); return; } if (swap_pager_getpages(object, &m, 1, 0) != VM_PAGER_OK) panic("swap_pager_force_pagein: read from swap failed");/*XXX*/ vm_object_pip_subtract(object, 1); VM_OBJECT_UNLOCK(object); vm_page_lock_queues(); vm_page_dirty(m); vm_page_dontneed(m); vm_page_wakeup(m); vm_page_unlock_queues(); vm_pager_page_unswapped(m); } /* * swap_pager_swapoff: * * Page in all of the pages that have been paged out to the * given device. The corresponding blocks in the bitmap must be * marked as allocated and the device must be flagged SW_CLOSING. * There may be no processes swapped out to the device. * * The sw_used parameter points to the field in the swdev structure * that contains a count of the number of blocks still allocated * on the device. If we encounter objects with a nonzero pip count * in our scan, we use this number to determine if we're really done. * * This routine may block. */ static void swap_pager_swapoff(struct swdevt *sp, int *sw_used) { struct swblock **pswap; struct swblock *swap; vm_object_t waitobj; daddr_t v; int i, j; GIANT_REQUIRED; full_rescan: waitobj = NULL; for (i = 0; i <= swhash_mask; i++) { /* '<=' is correct here */ restart: pswap = &swhash[i]; while ((swap = *pswap) != NULL) { for (j = 0; j < SWAP_META_PAGES; ++j) { v = swap->swb_pages[j]; if (v != SWAPBLK_NONE && swp_pager_find_dev(v, 1) == sp) break; } if (j < SWAP_META_PAGES) { swp_pager_force_pagein(swap, j); goto restart; } else if (swap->swb_object->paging_in_progress) { if (!waitobj) waitobj = swap->swb_object; } pswap = &swap->swb_hnext; } } if (waitobj && *sw_used) { /* * We wait on an arbitrary object to clock our rescans * to the rate of paging completion. */ VM_OBJECT_LOCK(waitobj); vm_object_pip_wait(waitobj, "swpoff"); VM_OBJECT_UNLOCK(waitobj); goto full_rescan; } if (*sw_used) panic("swapoff: failed to locate %d swap blocks", *sw_used); } /************************************************************************ * SWAP META DATA * ************************************************************************ * * These routines manipulate the swap metadata stored in the * OBJT_SWAP object. All swp_*() routines must be called at * splvm() because swap can be freed up by the low level vm_page * code which might be called from interrupts beyond what splbio() covers. * * Swap metadata is implemented with a global hash and not directly * linked into the object. Instead the object simply contains * appropriate tracking counters. */ /* * SWP_PAGER_META_BUILD() - add swap block to swap meta data for object * * We first convert the object to a swap object if it is a default * object. * * The specified swapblk is added to the object's swap metadata. If * the swapblk is not valid, it is freed instead. Any previously * assigned swapblk is freed. * * This routine must be called at splvm(), except when used to convert * an OBJT_DEFAULT object into an OBJT_SWAP object. */ static void swp_pager_meta_build( vm_object_t object, vm_pindex_t pindex, daddr_t swapblk ) { struct swblock *swap; struct swblock **pswap; int idx; GIANT_REQUIRED; /* * Convert default object to swap object if necessary */ if (object->type != OBJT_SWAP) { object->type = OBJT_SWAP; object->un_pager.swp.swp_bcount = 0; mtx_lock(&sw_alloc_mtx); if (object->handle != NULL) { TAILQ_INSERT_TAIL( NOBJLIST(object->handle), object, pager_object_list ); } else { TAILQ_INSERT_TAIL( &swap_pager_un_object_list, object, pager_object_list ); } mtx_unlock(&sw_alloc_mtx); } /* * Locate hash entry. If not found create, but if we aren't adding * anything just return. If we run out of space in the map we wait * and, since the hash table may have changed, retry. */ retry: pswap = swp_pager_hash(object, pindex); if ((swap = *pswap) == NULL) { int i; if (swapblk == SWAPBLK_NONE) return; swap = *pswap = uma_zalloc(swap_zone, M_NOWAIT); if (swap == NULL) { VM_WAIT; goto retry; } swap->swb_hnext = NULL; swap->swb_object = object; swap->swb_index = pindex & ~(vm_pindex_t)SWAP_META_MASK; swap->swb_count = 0; ++object->un_pager.swp.swp_bcount; for (i = 0; i < SWAP_META_PAGES; ++i) swap->swb_pages[i] = SWAPBLK_NONE; } /* * Delete prior contents of metadata */ idx = pindex & SWAP_META_MASK; if (swap->swb_pages[idx] != SWAPBLK_NONE) { swp_pager_freeswapspace(swap->swb_pages[idx], 1); --swap->swb_count; } /* * Enter block into metadata */ swap->swb_pages[idx] = swapblk; if (swapblk != SWAPBLK_NONE) ++swap->swb_count; } /* * SWP_PAGER_META_FREE() - free a range of blocks in the object's swap metadata * * The requested range of blocks is freed, with any associated swap * returned to the swap bitmap. * * This routine will free swap metadata structures as they are cleaned * out. This routine does *NOT* operate on swap metadata associated * with resident pages. * * This routine must be called at splvm() */ static void swp_pager_meta_free(vm_object_t object, vm_pindex_t index, daddr_t count) { GIANT_REQUIRED; if (object->type != OBJT_SWAP) return; while (count > 0) { struct swblock **pswap; struct swblock *swap; pswap = swp_pager_hash(object, index); if ((swap = *pswap) != NULL) { daddr_t v = swap->swb_pages[index & SWAP_META_MASK]; if (v != SWAPBLK_NONE) { swp_pager_freeswapspace(v, 1); swap->swb_pages[index & SWAP_META_MASK] = SWAPBLK_NONE; if (--swap->swb_count == 0) { *pswap = swap->swb_hnext; uma_zfree(swap_zone, swap); --object->un_pager.swp.swp_bcount; } } --count; ++index; } else { int n = SWAP_META_PAGES - (index & SWAP_META_MASK); count -= n; index += n; } } } /* * SWP_PAGER_META_FREE_ALL() - destroy all swap metadata associated with object * * This routine locates and destroys all swap metadata associated with * an object. * * This routine must be called at splvm() */ static void swp_pager_meta_free_all(vm_object_t object) { daddr_t index = 0; GIANT_REQUIRED; if (object->type != OBJT_SWAP) return; while (object->un_pager.swp.swp_bcount) { struct swblock **pswap; struct swblock *swap; pswap = swp_pager_hash(object, index); if ((swap = *pswap) != NULL) { int i; for (i = 0; i < SWAP_META_PAGES; ++i) { daddr_t v = swap->swb_pages[i]; if (v != SWAPBLK_NONE) { --swap->swb_count; swp_pager_freeswapspace(v, 1); } } if (swap->swb_count != 0) panic("swap_pager_meta_free_all: swb_count != 0"); *pswap = swap->swb_hnext; uma_zfree(swap_zone, swap); --object->un_pager.swp.swp_bcount; } index += SWAP_META_PAGES; if (index > 0x20000000) panic("swp_pager_meta_free_all: failed to locate all swap meta blocks"); } } /* * SWP_PAGER_METACTL() - misc control of swap and vm_page_t meta data. * * This routine is capable of looking up, popping, or freeing * swapblk assignments in the swap meta data or in the vm_page_t. * The routine typically returns the swapblk being looked-up, or popped, * or SWAPBLK_NONE if the block was freed, or SWAPBLK_NONE if the block * was invalid. This routine will automatically free any invalid * meta-data swapblks. * * It is not possible to store invalid swapblks in the swap meta data * (other then a literal 'SWAPBLK_NONE'), so we don't bother checking. * * When acting on a busy resident page and paging is in progress, we * have to wait until paging is complete but otherwise can act on the * busy page. * * This routine must be called at splvm(). * * SWM_FREE remove and free swap block from metadata * SWM_POP remove from meta data but do not free.. pop it out */ static daddr_t swp_pager_meta_ctl( vm_object_t object, vm_pindex_t pindex, int flags ) { struct swblock **pswap; struct swblock *swap; daddr_t r1; int idx; GIANT_REQUIRED; /* * The meta data only exists of the object is OBJT_SWAP * and even then might not be allocated yet. */ if (object->type != OBJT_SWAP) return (SWAPBLK_NONE); r1 = SWAPBLK_NONE; pswap = swp_pager_hash(object, pindex); if ((swap = *pswap) != NULL) { idx = pindex & SWAP_META_MASK; r1 = swap->swb_pages[idx]; if (r1 != SWAPBLK_NONE) { if (flags & SWM_FREE) { swp_pager_freeswapspace(r1, 1); r1 = SWAPBLK_NONE; } if (flags & (SWM_FREE|SWM_POP)) { swap->swb_pages[idx] = SWAPBLK_NONE; if (--swap->swb_count == 0) { *pswap = swap->swb_hnext; uma_zfree(swap_zone, swap); --object->un_pager.swp.swp_bcount; } } } } return (r1); } /******************************************************** * CHAINING FUNCTIONS * ******************************************************** * * These functions support recursion of I/O operations * on bp's, typically by chaining one or more 'child' bp's * to the parent. Synchronous, asynchronous, and semi-synchronous * chaining is possible. */ /* * swapdev_strategy: * * Perform swap strategy interleave device selection. * * The bp is expected to be locked and *not* B_DONE on call. */ static void swapdev_strategy(struct buf *a_bp) { int s, sz; struct swdevt *sp; struct vnode *vp; struct buf *bp; bp = a_bp; sz = howmany(bp->b_bcount, PAGE_SIZE); /* * Convert interleaved swap into per-device swap. Note that * the block size is left in PAGE_SIZE'd chunks (for the newswap) * here. */ sp = swp_pager_find_dev(bp->b_blkno, sz); bp->b_dev = sp->sw_device; /* * Convert from PAGE_SIZE'd to DEV_BSIZE'd chunks for the actual I/O */ bp->b_blkno = ctodb(bp->b_blkno - sp->sw_first); vhold(sp->sw_vp); s = splvm(); if (bp->b_iocmd == BIO_WRITE) { vp = bp->b_vp; if (vp) { VI_LOCK(vp); vp->v_numoutput--; if ((vp->v_iflag & VI_BWAIT) && vp->v_numoutput <= 0) { vp->v_iflag &= ~VI_BWAIT; wakeup(&vp->v_numoutput); } VI_UNLOCK(vp); } VI_LOCK(sp->sw_vp); sp->sw_vp->v_numoutput++; VI_UNLOCK(sp->sw_vp); } bp->b_vp = sp->sw_vp; splx(s); if (bp->b_vp->v_type == VCHR) VOP_SPECSTRATEGY(bp->b_vp, bp); else VOP_STRATEGY(bp->b_vp, bp); return; } /* * System call swapon(name) enables swapping on device name, * which must be in the swdevsw. Return EBUSY * if already swapping on this device. */ #ifndef _SYS_SYSPROTO_H_ struct swapon_args { char *name; }; #endif /* * MPSAFE */ /* ARGSUSED */ int swapon(td, uap) struct thread *td; struct swapon_args *uap; { struct vattr attr; struct vnode *vp; struct nameidata nd; int error; mtx_lock(&Giant); error = suser(td); if (error) goto done2; while (swdev_syscall_active) tsleep(&swdev_syscall_active, PUSER - 1, "swpon", 0); swdev_syscall_active = 1; /* * Swap metadata may not fit in the KVM if we have physical * memory of >1GB. */ if (swap_zone == NULL) { error = ENOMEM; goto done; } NDINIT(&nd, LOOKUP, FOLLOW, UIO_USERSPACE, uap->name, td); error = namei(&nd); if (error) goto done; NDFREE(&nd, NDF_ONLY_PNBUF); vp = nd.ni_vp; if (vn_isdisk(vp, &error)) error = swaponvp(td, vp, vp->v_rdev, 0); else if (vp->v_type == VREG && (vp->v_mount->mnt_vfc->vfc_flags & VFCF_NETWORK) != 0 && (error = VOP_GETATTR(vp, &attr, td->td_ucred, td)) == 0) { /* * Allow direct swapping to NFS regular files in the same * way that nfs_mountroot() sets up diskless swapping. */ error = swaponvp(td, vp, NODEV, attr.va_size / DEV_BSIZE); } if (error) vrele(vp); done: swdev_syscall_active = 0; wakeup_one(&swdev_syscall_active); done2: mtx_unlock(&Giant); return (error); } /* * Swfree(index) frees the index'th portion of the swap map. * Each of the NSWAPDEV devices provides 1/NSWAPDEV'th of the swap * space, which is laid out with blocks of dmmax pages circularly * among the devices. * * The new swap code uses page-sized blocks. The old swap code used * DEV_BSIZE'd chunks. */ int swaponvp(td, vp, dev, nblks) struct thread *td; struct vnode *vp; dev_t dev; u_long nblks; { struct swdevt *sp; swblk_t dvbase; int error; u_long mblocks; off_t mediasize; dvbase = 0; TAILQ_FOREACH(sp, &swtailq, sw_list) { if (sp->sw_vp == vp) return (EBUSY); if (sp->sw_end >= dvbase) { /* * We put one uncovered page between the devices * in order to definitively prevent any cross-device * I/O requests */ dvbase = sp->sw_end + 1; } } (void) vn_lock(vp, LK_EXCLUSIVE | LK_RETRY, td); #ifdef MAC error = mac_check_system_swapon(td->td_ucred, vp); if (error == 0) #endif error = VOP_OPEN(vp, FREAD | FWRITE, td->td_ucred, td, -1); (void) VOP_UNLOCK(vp, 0, td); if (error) return (error); if (nblks == 0) { error = VOP_IOCTL(vp, DIOCGMEDIASIZE, (caddr_t)&mediasize, FREAD, td->td_ucred, td); if (error == 0) nblks = mediasize / DEV_BSIZE; } /* * XXX: We should also check that the sectorsize makes sense * XXX: it should be a power of two, no larger than the page size. */ if (nblks == 0) { (void) VOP_CLOSE(vp, FREAD | FWRITE, td->td_ucred, td); return (ENXIO); } /* * If we go beyond this, we get overflows in the radix * tree bitmap code. */ mblocks = 0x40000000 / BLIST_META_RADIX; if (nblks > mblocks) { printf("WARNING: reducing size to maximum of %lu blocks per swap unit\n", mblocks); nblks = mblocks; } /* * nblks is in DEV_BSIZE'd chunks, convert to PAGE_SIZE'd chunks. * First chop nblks off to page-align it, then convert. * * sw->sw_nblks is in page-sized chunks now too. */ nblks &= ~(ctodb(1) - 1); nblks = dbtoc(nblks); sp = malloc(sizeof *sp, M_VMPGDATA, M_WAITOK | M_ZERO); sp->sw_vp = vp; sp->sw_dev = dev2udev(dev); sp->sw_device = dev; sp->sw_flags = 0; sp->sw_nblks = nblks; sp->sw_used = 0; sp->sw_first = dvbase; sp->sw_end = dvbase + nblks; sp->sw_blist = blist_create(nblks); /* * Do not free the first block in order to avoid overwriting * any bsd label at the front of the partition */ blist_free(sp->sw_blist, 1, nblks - 1); TAILQ_INSERT_TAIL(&swtailq, sp, sw_list); nswapdev++; swap_pager_avail += nblks; swap_pager_full = 0; return (0); } /* * SYSCALL: swapoff(devname) * * Disable swapping on the given device. */ #ifndef _SYS_SYSPROTO_H_ struct swapoff_args { char *name; }; #endif /* * MPSAFE */ /* ARGSUSED */ int swapoff(td, uap) struct thread *td; struct swapoff_args *uap; { struct vnode *vp; struct nameidata nd; struct swdevt *sp; u_long nblks, dvbase; int error; mtx_lock(&Giant); error = suser(td); if (error) goto done2; while (swdev_syscall_active) tsleep(&swdev_syscall_active, PUSER - 1, "swpoff", 0); swdev_syscall_active = 1; NDINIT(&nd, LOOKUP, FOLLOW, UIO_USERSPACE, uap->name, td); error = namei(&nd); if (error) goto done; NDFREE(&nd, NDF_ONLY_PNBUF); vp = nd.ni_vp; TAILQ_FOREACH(sp, &swtailq, sw_list) { if (sp->sw_vp == vp) goto found; } error = EINVAL; goto done; found: #ifdef MAC (void) vn_lock(vp, LK_EXCLUSIVE | LK_RETRY, td); error = mac_check_system_swapoff(td->td_ucred, vp); (void) VOP_UNLOCK(vp, 0, td); if (error != 0) goto done; #endif nblks = sp->sw_nblks; /* * We can turn off this swap device safely only if the * available virtual memory in the system will fit the amount * of data we will have to page back in, plus an epsilon so * the system doesn't become critically low on swap space. */ if (cnt.v_free_count + cnt.v_cache_count + swap_pager_avail < nblks + nswap_lowat) { error = ENOMEM; goto done; } /* * Prevent further allocations on this device. */ sp->sw_flags |= SW_CLOSING; for (dvbase = 0; dvbase < sp->sw_end; dvbase += dmmax) { swap_pager_avail -= blist_fill(sp->sw_blist, dvbase, dmmax); } /* * Page in the contents of the device and close it. */ #ifndef NO_SWAPPING vm_proc_swapin_all(sp); #endif /* !NO_SWAPPING */ swap_pager_swapoff(sp, &sp->sw_used); VOP_CLOSE(vp, FREAD | FWRITE, td->td_ucred, td); vrele(vp); sp->sw_vp = NULL; TAILQ_REMOVE(&swtailq, sp, sw_list); if (swdevhd == sp) swdevhd = NULL; nswapdev--; blist_destroy(sp->sw_blist); free(sp, M_VMPGDATA); done: swdev_syscall_active = 0; wakeup_one(&swdev_syscall_active); done2: mtx_unlock(&Giant); return (error); } void swap_pager_status(int *total, int *used) { struct swdevt *sp; *total = 0; *used = 0; TAILQ_FOREACH(sp, &swtailq, sw_list) { *total += sp->sw_nblks; *used += sp->sw_used; } } static int sysctl_vm_swap_info(SYSCTL_HANDLER_ARGS) { int *name = (int *)arg1; int error, n; struct xswdev xs; struct swdevt *sp; if (arg2 != 1) /* name length */ return (EINVAL); n = 0; TAILQ_FOREACH(sp, &swtailq, sw_list) { if (n == *name) { xs.xsw_version = XSWDEV_VERSION; xs.xsw_dev = sp->sw_dev; xs.xsw_flags = sp->sw_flags; xs.xsw_nblks = sp->sw_nblks; xs.xsw_used = sp->sw_used; error = SYSCTL_OUT(req, &xs, sizeof(xs)); return (error); } n++; } return (ENOENT); } SYSCTL_INT(_vm, OID_AUTO, nswapdev, CTLFLAG_RD, &nswapdev, 0, "Number of swap devices"); SYSCTL_NODE(_vm, OID_AUTO, swap_info, CTLFLAG_RD, sysctl_vm_swap_info, "Swap statistics by device"); /* * vmspace_swap_count() - count the approximate swap useage in pages for a * vmspace. * * The map must be locked. * * Swap useage is determined by taking the proportional swap used by * VM objects backing the VM map. To make up for fractional losses, * if the VM object has any swap use at all the associated map entries * count for at least 1 swap page. */ int vmspace_swap_count(struct vmspace *vmspace) { vm_map_t map = &vmspace->vm_map; vm_map_entry_t cur; int count = 0; for (cur = map->header.next; cur != &map->header; cur = cur->next) { vm_object_t object; if ((cur->eflags & MAP_ENTRY_IS_SUB_MAP) == 0 && (object = cur->object.vm_object) != NULL) { VM_OBJECT_LOCK(object); if (object->type == OBJT_SWAP && object->un_pager.swp.swp_bcount != 0) { int n = (cur->end - cur->start) / PAGE_SIZE; count += object->un_pager.swp.swp_bcount * SWAP_META_PAGES * n / object->size + 1; } VM_OBJECT_UNLOCK(object); } } return (count); }