/*- * 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_compat.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 #include #include #include #include #include #include /* * SWB_NPAGES must be a power of 2. It may be set to 1, 2, 4, 8, 16 * or 32 pages per allocation. * The 32-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 /* * The swblock structure maps an object and a small, fixed-size range * of page indices to disk addresses within a swap area. * The collection of these mappings is implemented as a hash table. * Unused disk addresses within a swap area are allocated and managed * using a blist. */ #define SWCORRECT(n) (sizeof(void *) * (n) / sizeof(daddr_t)) #define SWAP_META_PAGES (SWB_NPAGES * 2) #define SWAP_META_MASK (SWAP_META_PAGES - 1) 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 MALLOC_DEFINE(M_VMPGDATA, "vm_pgdata", "swap pager private data"); static struct mtx sw_dev_mtx; 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 struct sx swdev_syscall_lock; /* serialize swap(on|off) */ static vm_ooffset_t swap_total; SYSCTL_QUAD(_vm, OID_AUTO, swap_total, CTLFLAG_RD, &swap_total, 0, "Total amount of available swap storage."); static vm_ooffset_t swap_reserved; SYSCTL_QUAD(_vm, OID_AUTO, swap_reserved, CTLFLAG_RD, &swap_reserved, 0, "Amount of swap storage needed to back all allocated anonymous memory."); static int overcommit = 0; SYSCTL_INT(_vm, OID_AUTO, overcommit, CTLFLAG_RW, &overcommit, 0, "Configure virtual memory overcommit behavior. See tuning(7) " "for details."); static unsigned long swzone; SYSCTL_ULONG(_vm, OID_AUTO, swzone, CTLFLAG_RD, &swzone, 0, "Actual size of swap metadata zone"); static unsigned long swap_maxpages; SYSCTL_ULONG(_vm, OID_AUTO, swap_maxpages, CTLFLAG_RD, &swap_maxpages, 0, "Maximum amount of swap supported"); /* bits from overcommit */ #define SWAP_RESERVE_FORCE_ON (1 << 0) #define SWAP_RESERVE_RLIMIT_ON (1 << 1) #define SWAP_RESERVE_ALLOW_NONWIRED (1 << 2) int swap_reserve(vm_ooffset_t incr) { return (swap_reserve_by_cred(incr, curthread->td_ucred)); } int swap_reserve_by_cred(vm_ooffset_t incr, struct ucred *cred) { vm_ooffset_t r, s; int res, error; static int curfail; static struct timeval lastfail; struct uidinfo *uip; uip = cred->cr_ruidinfo; if (incr & PAGE_MASK) panic("swap_reserve: & PAGE_MASK"); #ifdef RACCT if (racct_enable) { PROC_LOCK(curproc); error = racct_add(curproc, RACCT_SWAP, incr); PROC_UNLOCK(curproc); if (error != 0) return (0); } #endif res = 0; mtx_lock(&sw_dev_mtx); r = swap_reserved + incr; if (overcommit & SWAP_RESERVE_ALLOW_NONWIRED) { s = vm_cnt.v_page_count - vm_cnt.v_free_reserved - vm_cnt.v_wire_count; s *= PAGE_SIZE; } else s = 0; s += swap_total; if ((overcommit & SWAP_RESERVE_FORCE_ON) == 0 || r <= s || (error = priv_check(curthread, PRIV_VM_SWAP_NOQUOTA)) == 0) { res = 1; swap_reserved = r; } mtx_unlock(&sw_dev_mtx); if (res) { UIDINFO_VMSIZE_LOCK(uip); if ((overcommit & SWAP_RESERVE_RLIMIT_ON) != 0 && uip->ui_vmsize + incr > lim_cur(curthread, RLIMIT_SWAP) && priv_check(curthread, PRIV_VM_SWAP_NORLIMIT)) res = 0; else uip->ui_vmsize += incr; UIDINFO_VMSIZE_UNLOCK(uip); if (!res) { mtx_lock(&sw_dev_mtx); swap_reserved -= incr; mtx_unlock(&sw_dev_mtx); } } if (!res && ppsratecheck(&lastfail, &curfail, 1)) { printf("uid %d, pid %d: swap reservation for %jd bytes failed\n", uip->ui_uid, curproc->p_pid, incr); } #ifdef RACCT if (!res) { PROC_LOCK(curproc); racct_sub(curproc, RACCT_SWAP, incr); PROC_UNLOCK(curproc); } #endif return (res); } void swap_reserve_force(vm_ooffset_t incr) { struct uidinfo *uip; mtx_lock(&sw_dev_mtx); swap_reserved += incr; mtx_unlock(&sw_dev_mtx); #ifdef RACCT PROC_LOCK(curproc); racct_add_force(curproc, RACCT_SWAP, incr); PROC_UNLOCK(curproc); #endif uip = curthread->td_ucred->cr_ruidinfo; PROC_LOCK(curproc); UIDINFO_VMSIZE_LOCK(uip); uip->ui_vmsize += incr; UIDINFO_VMSIZE_UNLOCK(uip); PROC_UNLOCK(curproc); } void swap_release(vm_ooffset_t decr) { struct ucred *cred; PROC_LOCK(curproc); cred = curthread->td_ucred; swap_release_by_cred(decr, cred); PROC_UNLOCK(curproc); } void swap_release_by_cred(vm_ooffset_t decr, struct ucred *cred) { struct uidinfo *uip; uip = cred->cr_ruidinfo; if (decr & PAGE_MASK) panic("swap_release: & PAGE_MASK"); mtx_lock(&sw_dev_mtx); if (swap_reserved < decr) panic("swap_reserved < decr"); swap_reserved -= decr; mtx_unlock(&sw_dev_mtx); UIDINFO_VMSIZE_LOCK(uip); if (uip->ui_vmsize < decr) printf("negative vmsize for uid = %d\n", uip->ui_uid); uip->ui_vmsize -= decr; UIDINFO_VMSIZE_UNLOCK(uip); racct_sub_cred(cred, RACCT_SWAP, decr); } #define SWM_FREE 0x02 /* free, period */ #define SWM_POP 0x04 /* pop out */ int swap_pager_full = 2; /* swap space exhaustion (task killing) */ static int swap_pager_almost_full = 1; /* 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 int sysctl_swap_async_max(SYSCTL_HANDLER_ARGS); SYSCTL_PROC(_vm, OID_AUTO, swap_async_max, CTLTYPE_INT | CTLFLAG_RW | CTLFLAG_MPSAFE, NULL, 0, sysctl_swap_async_max, "I", "Maximum running async swap ops"); static struct swblock **swhash; static int swhash_mask; static struct mtx swhash_mtx; static struct sx sw_alloc_sx; /* * "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 pagerlst swap_pager_object_list[NOBJLISTS]; 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, struct ucred *); static void swap_pager_dealloc(vm_object_t object); static int swap_pager_getpages(vm_object_t, vm_page_t *, int, int *, int *); static int swap_pager_getpages_async(vm_object_t, vm_page_t *, int, int *, int *, pgo_getpages_iodone_t, void *); static void swap_pager_putpages(vm_object_t, vm_page_t *, int, boolean_t, 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); 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_getpages_async = swap_pager_getpages_async, /* pagein (async) */ .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 */ }; /* * swap_*() routines are externally accessible. swp_*() routines are * internal. */ 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, &nsw_cluster_max, 0, "Maximum size of a swap block in pages"); static void swp_sizecheck(void); static void swp_pager_async_iodone(struct buf *bp); static int swapongeom(struct vnode *); static int swaponvp(struct thread *, struct vnode *, u_long); static int swapoff_one(struct swdevt *sp, struct ucred *cred); /* * 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, vm_pindex_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. */ static void swp_sizecheck(void) { 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. */ 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(void) { /* * Initialize object lists */ int i; for (i = 0; i < NOBJLISTS; ++i) TAILQ_INIT(&swap_pager_object_list[i]); mtx_init(&sw_dev_mtx, "swapdev", NULL, MTX_DEF); sx_init(&sw_alloc_sx, "swspsx"); sx_init(&swdev_syscall_lock, "swsysc"); } /* * 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(void) { unsigned long 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 32 pages, so this is probably overkill. This reservation * is typically limited to around 32MB by default. */ n = vm_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 | UMA_ZONE_VM); if (swap_zone == NULL) panic("failed to create swap_zone."); do { if (uma_zone_reserve_kva(swap_zone, 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 (n2 != n) printf("Swap zone entries reduced from %lu to %lu.\n", n2, n); swap_maxpages = n * SWAP_META_PAGES; swzone = n * sizeof(struct swblock); 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; mtx_init(&swhash_mtx, "swap_pager swhash", NULL, MTX_DEF); } static vm_object_t swap_pager_alloc_init(void *handle, struct ucred *cred, vm_ooffset_t size, vm_ooffset_t offset) { vm_object_t object; if (cred != NULL) { if (!swap_reserve_by_cred(size, cred)) return (NULL); crhold(cred); } object = vm_object_allocate(OBJT_SWAP, OFF_TO_IDX(offset + PAGE_MASK + size)); object->handle = handle; if (cred != NULL) { object->cred = cred; object->charge = size; } object->un_pager.swp.swp_bcount = 0; return (object); } /* * 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. * * This routine must ensure that no live duplicate is created for * the named object request, which is protected against by * holding the sw_alloc_sx lock in case handle != NULL. */ static vm_object_t swap_pager_alloc(void *handle, vm_ooffset_t size, vm_prot_t prot, vm_ooffset_t offset, struct ucred *cred) { vm_object_t object; if (handle != NULL) { /* * 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) { object = swap_pager_alloc_init(handle, cred, size, offset); if (object != NULL) { TAILQ_INSERT_TAIL(NOBJLIST(object->handle), object, pager_object_list); } } sx_xunlock(&sw_alloc_sx); } else { object = swap_pager_alloc_init(handle, cred, size, offset); } 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. * * The object must be locked. */ static void swap_pager_dealloc(vm_object_t object) { VM_OBJECT_ASSERT_WLOCKED(object); KASSERT((object->flags & OBJ_DEAD) != 0, ("dealloc of reachable obj")); /* * Remove from list right away so lookups will fail if we block for * pageout completion. */ if (object->handle != NULL) { VM_OBJECT_WUNLOCK(object); sx_xlock(&sw_alloc_sx); TAILQ_REMOVE(NOBJLIST(object->handle), object, pager_object_list); sx_xunlock(&sw_alloc_sx); VM_OBJECT_WLOCK(object); } 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. */ swp_pager_meta_free_all(object); object->handle = NULL; object->type = OBJT_DEAD; } /************************************************************************ * 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. * * This routine may not sleep. * * We allocate in round-robin fashion from the configured devices. */ static daddr_t swp_pager_getswapspace(int npages) { daddr_t blk; struct swdevt *sp; int i; blk = SWAPBLK_NONE; mtx_lock(&sw_dev_mtx); 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; sp->sw_used += npages; swap_pager_avail -= npages; swp_sizecheck(); swdevhd = TAILQ_NEXT(sp, sw_list); goto done; } } sp = TAILQ_NEXT(sp, sw_list); } if (swap_pager_full != 2) { printf("swap_pager_getswapspace(%d): failed\n", npages); swap_pager_full = 2; swap_pager_almost_full = 1; } swdevhd = NULL; done: mtx_unlock(&sw_dev_mtx); return (blk); } static int swp_pager_isondev(daddr_t blk, struct swdevt *sp) { return (blk >= sp->sw_first && blk < sp->sw_end); } static void swp_pager_strategy(struct buf *bp) { struct swdevt *sp; mtx_lock(&sw_dev_mtx); TAILQ_FOREACH(sp, &swtailq, sw_list) { if (bp->b_blkno >= sp->sw_first && bp->b_blkno < sp->sw_end) { mtx_unlock(&sw_dev_mtx); if ((sp->sw_flags & SW_UNMAPPED) != 0 && unmapped_buf_allowed) { bp->b_data = unmapped_buf; bp->b_offset = 0; } else { pmap_qenter((vm_offset_t)bp->b_data, &bp->b_pages[0], bp->b_bcount / PAGE_SIZE); } sp->sw_strategy(bp, sp); return; } } panic("Swapdev not found"); } /* * SWP_PAGER_FREESWAPSPACE() - free raw swap space * * This routine returns the specified swap blocks back to the bitmap. * * This routine may not sleep. */ static void swp_pager_freeswapspace(daddr_t blk, int npages) { struct swdevt *sp; mtx_lock(&sw_dev_mtx); TAILQ_FOREACH(sp, &swtailq, sw_list) { if (blk >= sp->sw_first && blk < sp->sw_end) { 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) == 0) { blist_free(sp->sw_blist, blk - sp->sw_first, npages); swap_pager_avail += npages; swp_sizecheck(); } mtx_unlock(&sw_dev_mtx); return; } } panic("Swapdev not found"); } /* * 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. * * The object must be locked. */ void swap_pager_freespace(vm_object_t object, vm_pindex_t start, vm_size_t size) { swp_pager_meta_free(object, start, size); } /* * SWAP_PAGER_RESERVE() - reserve swap blocks in object * * Assigns swap blocks to the specified range within the object. The * swap blocks are not zeroed. 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 n = 0; daddr_t blk = SWAPBLK_NONE; vm_pindex_t beg = start; /* save start index */ VM_OBJECT_WLOCK(object); 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); VM_OBJECT_WUNLOCK(object); return (-1); } } } swp_pager_meta_build(object, start, blk); --size; ++start; ++blk; --n; } swp_pager_meta_free(object, start, n); VM_OBJECT_WUNLOCK(object); 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 sleep. It may sleep allocating metadata * indirectly through swp_pager_meta_build() or if paging is still in * progress on the source. * * 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. * Both object locks may temporarily be released. */ void swap_pager_copy(vm_object_t srcobject, vm_object_t dstobject, vm_pindex_t offset, int destroysource) { vm_pindex_t i; VM_OBJECT_ASSERT_WLOCKED(srcobject); VM_OBJECT_ASSERT_WLOCKED(dstobject); /* * If destroysource is set, we remove the source object from the * swap_pager internal queue now. */ if (destroysource && srcobject->handle != NULL) { vm_object_pip_add(srcobject, 1); VM_OBJECT_WUNLOCK(srcobject); vm_object_pip_add(dstobject, 1); VM_OBJECT_WUNLOCK(dstobject); sx_xlock(&sw_alloc_sx); TAILQ_REMOVE(NOBJLIST(srcobject->handle), srcobject, pager_object_list); sx_xunlock(&sw_alloc_sx); VM_OBJECT_WLOCK(dstobject); vm_object_pip_wakeup(dstobject); VM_OBJECT_WLOCK(srcobject); vm_object_pip_wakeup(srcobject); } /* * 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() can sleep. */ vm_object_pip_add(srcobject, 1); VM_OBJECT_WUNLOCK(srcobject); vm_object_pip_add(dstobject, 1); swp_pager_meta_build(dstobject, i, srcaddr); vm_object_pip_wakeup(dstobject); VM_OBJECT_WLOCK(srcobject); vm_object_pip_wakeup(srcobject); } } 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 accidentally * 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; } } /* * 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. */ static boolean_t swap_pager_haspage(vm_object_t object, vm_pindex_t pindex, int *before, int *after) { daddr_t blk, blk0; int i; VM_OBJECT_ASSERT_LOCKED(object); /* * do we have good backing store at the requested index ? */ blk0 = swp_pager_meta_ctl(object, pindex, 0); if (blk0 == SWAPBLK_NONE) { if (before) *before = 0; if (after) *after = 0; return (FALSE); } /* * find backwards-looking contiguous good backing store */ if (before != NULL) { for (i = 1; i < SWB_NPAGES; i++) { 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) { for (i = 1; i < SWB_NPAGES; i++) { blk = swp_pager_meta_ctl(object, pindex + i, 0); if (blk != blk0 + i) break; } *after = i - 1; } 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 sleep. * * The object containing the page must be locked. */ static void swap_pager_unswapped(vm_page_t m) { swp_pager_meta_ctl(m->object, m->pindex, SWM_FREE); } /* * swap_pager_getpages() - bring pages in from swap * * Attempt to page in the pages in array "m" of length "count". The caller * may optionally specify that additional pages preceding and succeeding * the specified range be paged in. The number of such pages is returned * in the "rbehind" and "rahead" parameters, and they will be in the * inactive queue upon return. * * The pages in "m" must be busied and will remain busied upon return. */ static int swap_pager_getpages(vm_object_t object, vm_page_t *m, int count, int *rbehind, int *rahead) { struct buf *bp; vm_page_t mpred, msucc, p; vm_pindex_t pindex; daddr_t blk; int i, j, maxahead, maxbehind, reqcount, shift; reqcount = count; VM_OBJECT_WUNLOCK(object); bp = getpbuf(&nsw_rcount); VM_OBJECT_WLOCK(object); if (!swap_pager_haspage(object, m[0]->pindex, &maxbehind, &maxahead)) { relpbuf(bp, &nsw_rcount); return (VM_PAGER_FAIL); } /* * Clip the readahead and readbehind ranges to exclude resident pages. */ if (rahead != NULL) { KASSERT(reqcount - 1 <= maxahead, ("page count %d extends beyond swap block", reqcount)); *rahead = imin(*rahead, maxahead - (reqcount - 1)); pindex = m[reqcount - 1]->pindex; msucc = TAILQ_NEXT(m[reqcount - 1], listq); if (msucc != NULL && msucc->pindex - pindex - 1 < *rahead) *rahead = msucc->pindex - pindex - 1; } if (rbehind != NULL) { *rbehind = imin(*rbehind, maxbehind); pindex = m[0]->pindex; mpred = TAILQ_PREV(m[0], pglist, listq); if (mpred != NULL && pindex - mpred->pindex - 1 < *rbehind) *rbehind = pindex - mpred->pindex - 1; } /* * Allocate readahead and readbehind pages. */ shift = rbehind != NULL ? *rbehind : 0; if (shift != 0) { for (i = 1; i <= shift; i++) { p = vm_page_alloc(object, m[0]->pindex - i, VM_ALLOC_NORMAL); if (p == NULL) { /* Shift allocated pages to the left. */ for (j = 0; j < i - 1; j++) bp->b_pages[j] = bp->b_pages[j + shift - i + 1]; break; } bp->b_pages[shift - i] = p; } shift = i - 1; *rbehind = shift; } for (i = 0; i < reqcount; i++) bp->b_pages[i + shift] = m[i]; if (rahead != NULL) { for (i = 0; i < *rahead; i++) { p = vm_page_alloc(object, m[reqcount - 1]->pindex + i + 1, VM_ALLOC_NORMAL); if (p == NULL) break; bp->b_pages[shift + reqcount + i] = p; } *rahead = i; } if (rbehind != NULL) count += *rbehind; if (rahead != NULL) count += *rahead; vm_object_pip_add(object, count); for (i = 0; i < count; i++) bp->b_pages[i]->oflags |= VPO_SWAPINPROG; pindex = bp->b_pages[0]->pindex; blk = swp_pager_meta_ctl(object, pindex, 0); KASSERT(blk != SWAPBLK_NONE, ("no swap blocking containing %p(%jx)", object, (uintmax_t)pindex)); VM_OBJECT_WUNLOCK(object); bp->b_flags |= B_PAGING; 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; bp->b_bcount = PAGE_SIZE * count; bp->b_bufsize = PAGE_SIZE * count; bp->b_npages = count; bp->b_pgbefore = rbehind != NULL ? *rbehind : 0; bp->b_pgafter = rahead != NULL ? *rahead : 0; VM_CNT_INC(v_swapin); VM_CNT_ADD(v_swappgsin, count); /* * 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); swp_pager_strategy(bp); /* * Wait for the pages we want to complete. VPO_SWAPINPROG is always * cleared on completion. If an I/O error occurs, SWAPBLK_NONE * is set in the metadata for each page in the request. */ VM_OBJECT_WLOCK(object); while ((m[0]->oflags & VPO_SWAPINPROG) != 0) { m[0]->oflags |= VPO_SWAPSLEEP; VM_CNT_INC(v_intrans); if (VM_OBJECT_SLEEP(object, &object->paging_in_progress, PSWP, "swread", hz * 20)) { printf( "swap_pager: indefinite wait buffer: bufobj: %p, blkno: %jd, size: %ld\n", bp->b_bufobj, (intmax_t)bp->b_blkno, bp->b_bcount); } } /* * If we had an unrecoverable read error pages will not be valid. */ for (i = 0; i < reqcount; i++) if (m[i]->valid != VM_PAGE_BITS_ALL) return (VM_PAGER_ERROR); 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_getpages_async(): * * Right now this is emulation of asynchronous operation on top of * swap_pager_getpages(). */ static int swap_pager_getpages_async(vm_object_t object, vm_page_t *m, int count, int *rbehind, int *rahead, pgo_getpages_iodone_t iodone, void *arg) { int r, error; r = swap_pager_getpages(object, m, count, rbehind, rahead); VM_OBJECT_WUNLOCK(object); switch (r) { case VM_PAGER_OK: error = 0; break; case VM_PAGER_ERROR: error = EIO; break; case VM_PAGER_FAIL: error = EINVAL; break; default: panic("unhandled swap_pager_getpages() error %d", r); } (iodone)(arg, m, count, error); VM_OBJECT_WLOCK(object); return (r); } /* * 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. */ static void swap_pager_putpages(vm_object_t object, vm_page_t *m, int count, int flags, int *rtvals) { int i, n; boolean_t sync; if (count && m[0]->object != object) { panic("swap_pager_putpages: 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); VM_OBJECT_WUNLOCK(object); n = 0; if (curproc != pageproc) sync = TRUE; else sync = (flags & VM_PAGER_PUT_SYNC) != 0; /* * Step 2 * * 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 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); /* * 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; continue; } /* * All I/O parameters have been satisfied, build the I/O * request and assign the swap space. */ if (sync == TRUE) { bp = getpbuf(&nsw_wcount_sync); } else { bp = getpbuf(&nsw_wcount_async); bp->b_flags = B_ASYNC; } bp->b_flags |= B_PAGING; bp->b_iocmd = BIO_WRITE; 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; VM_OBJECT_WLOCK(object); 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); mreq->oflags |= VPO_SWAPINPROG; bp->b_pages[j] = mreq; } VM_OBJECT_WUNLOCK(object); bp->b_npages = n; /* * Must set dirty range for NFS to work. */ bp->b_dirtyoff = 0; bp->b_dirtyend = bp->b_bcount; VM_CNT_INC(v_swapout); VM_CNT_ADD(v_swappgsout, bp->b_npages); /* * We unconditionally set rtvals[] to VM_PAGER_PEND so that we * can call the async completion routine at the end of a * synchronous I/O operation. Otherwise, our caller would * perform duplicate unbusy and wakeup operations on the page * and object, respectively. */ for (j = 0; j < n; j++) rtvals[i + j] = VM_PAGER_PEND; /* * 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); swp_pager_strategy(bp); continue; } /* * synchronous * * NOTE: b_blkno is destroyed by the call to swapdev_strategy */ bp->b_iodone = bdone; swp_pager_strategy(bp); /* * Wait for the sync I/O to complete. */ bwait(bp, PVM, "swwrt"); /* * Now that we are through with the bp, we can call the * normal async completion, which frees everything up. */ swp_pager_async_iodone(bp); } VM_OBJECT_WLOCK(object); } /* * 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. * * This routine may not sleep. */ static void swp_pager_async_iodone(struct buf *bp) { int i; vm_object_t object = NULL; /* * 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 ); } /* * remove the mapping for kernel virtual */ if (buf_mapped(bp)) pmap_qremove((vm_offset_t)bp->b_data, bp->b_npages); else bp->b_data = bp->b_kvabase; if (bp->b_npages) { object = bp->b_pages[0]->object; VM_OBJECT_WLOCK(object); } /* * 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]; m->oflags &= ~VPO_SWAPINPROG; if (m->oflags & VPO_SWAPSLEEP) { m->oflags &= ~VPO_SWAPSLEEP; wakeup(&object->paging_in_progress); } 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) { /* * NOTE: for reads, m->dirty will probably * be overridden by the original caller of * getpages so don't play cute tricks here. */ m->valid = 0; } 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_lock(m); vm_page_activate(m); vm_page_unlock(m); vm_page_sunbusy(m); } } else if (bp->b_iocmd == BIO_READ) { /* * 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. */ KASSERT(!pmap_page_is_mapped(m), ("swp_pager_async_iodone: page %p is mapped", m)); KASSERT(m->dirty == 0, ("swp_pager_async_iodone: page %p is dirty", m)); m->valid = VM_PAGE_BITS_ALL; if (i < bp->b_pgbefore || i >= bp->b_npages - bp->b_pgafter) vm_page_readahead_finish(m); } else { /* * For write success, clear the dirty * status, then finish the I/O ( which decrements the * busy count and possibly wakes waiter's up ). * A page is only written to swap after a period of * inactivity. Therefore, we do not expect it to be * reused. */ KASSERT(!pmap_page_is_write_mapped(m), ("swp_pager_async_iodone: page %p is not write" " protected", m)); vm_page_undirty(m); vm_page_lock(m); vm_page_deactivate_noreuse(m); vm_page_unlock(m); vm_page_sunbusy(m); } } /* * 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_WUNLOCK(object); } /* * swapdev_strategy() manually sets b_vp and b_bufobj before calling * bstrategy(). Set them back to NULL now we're done with it, or we'll * trigger a KASSERT in relpbuf(). */ if (bp->b_vp) { bp->b_vp = NULL; bp->b_bufobj = NULL; } /* * 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 ) ) ); } /* * 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 sleep. */ int swap_pager_isswapped(vm_object_t object, struct swdevt *sp) { daddr_t index = 0; int bcount; int i; VM_OBJECT_ASSERT_WLOCKED(object); if (object->type != OBJT_SWAP) return (0); mtx_lock(&swhash_mtx); 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) { if (swp_pager_isondev(swap->swb_pages[i], sp)) { mtx_unlock(&swhash_mtx); return (1); } } } index += SWAP_META_PAGES; } mtx_unlock(&swhash_mtx); return (0); } int swap_pager_nswapdev(void) { return (nswapdev); } /* * SWP_PAGER_FORCE_PAGEIN() - force a swap block to be paged in * * This routine dissociates the page at the given index within an object * from its backing store, paging it in if it does not reside in memory. * If the page is paged in, it is marked dirty and placed in the laundry * queue. The page is marked dirty because it no longer has backing * store. It is placed in the laundry queue because it has not been * accessed recently. Otherwise, it would already reside in memory. * * We also attempt to swap in all other pages in the swap block. * However, 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(vm_object_t object, vm_pindex_t pindex) { vm_page_t m; vm_object_pip_add(object, 1); m = vm_page_grab(object, pindex, VM_ALLOC_NORMAL); if (m->valid == VM_PAGE_BITS_ALL) { vm_object_pip_wakeup(object); vm_page_dirty(m); vm_page_lock(m); vm_page_activate(m); vm_page_unlock(m); vm_page_xunbusy(m); vm_pager_page_unswapped(m); return; } if (swap_pager_getpages(object, &m, 1, NULL, NULL) != VM_PAGER_OK) panic("swap_pager_force_pagein: read from swap failed");/*XXX*/ vm_object_pip_wakeup(object); vm_page_dirty(m); vm_page_lock(m); vm_page_launder(m); vm_page_unlock(m); vm_page_xunbusy(m); 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. * * This routine may block. */ static void swap_pager_swapoff(struct swdevt *sp) { struct swblock *swap; vm_object_t locked_obj, object; vm_pindex_t pindex; int i, j, retries; sx_assert(&swdev_syscall_lock, SA_XLOCKED); retries = 0; locked_obj = NULL; full_rescan: mtx_lock(&swhash_mtx); for (i = 0; i <= swhash_mask; i++) { /* '<=' is correct here */ restart: for (swap = swhash[i]; swap != NULL; swap = swap->swb_hnext) { object = swap->swb_object; pindex = swap->swb_index; for (j = 0; j < SWAP_META_PAGES; ++j) { if (!swp_pager_isondev(swap->swb_pages[j], sp)) continue; if (locked_obj != object) { if (locked_obj != NULL) VM_OBJECT_WUNLOCK(locked_obj); locked_obj = object; if (!VM_OBJECT_TRYWLOCK(object)) { mtx_unlock(&swhash_mtx); /* Depends on type-stability. */ VM_OBJECT_WLOCK(object); mtx_lock(&swhash_mtx); goto restart; } } MPASS(locked_obj == object); mtx_unlock(&swhash_mtx); swp_pager_force_pagein(object, pindex + j); mtx_lock(&swhash_mtx); goto restart; } } } mtx_unlock(&swhash_mtx); if (locked_obj != NULL) { VM_OBJECT_WUNLOCK(locked_obj); locked_obj = NULL; } if (sp->sw_used) { /* * Objects may be locked or paging to the device being * removed, so we will miss their pages and need to * make another pass. We have marked this device as * SW_CLOSING, so the activity should finish soon. */ retries++; if (retries > 100) { panic("swapoff: failed to locate %d swap blocks", sp->sw_used); } pause("swpoff", hz / 20); goto full_rescan; } EVENTHANDLER_INVOKE(swapoff, sp); } /************************************************************************ * SWAP META DATA * ************************************************************************ * * These routines manipulate the swap metadata stored in the * OBJT_SWAP object. * * 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. */ static void swp_pager_meta_build(vm_object_t object, vm_pindex_t pindex, daddr_t swapblk) { static volatile int exhausted; struct swblock *swap; struct swblock **pswap; int idx; VM_OBJECT_ASSERT_WLOCKED(object); /* * Convert default object to swap object if necessary */ if (object->type != OBJT_SWAP) { object->type = OBJT_SWAP; object->un_pager.swp.swp_bcount = 0; KASSERT(object->handle == NULL, ("default pager with handle")); } /* * 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: mtx_lock(&swhash_mtx); pswap = swp_pager_hash(object, pindex); if ((swap = *pswap) == NULL) { int i; if (swapblk == SWAPBLK_NONE) goto done; swap = *pswap = uma_zalloc(swap_zone, M_NOWAIT | (curproc == pageproc ? M_USE_RESERVE : 0)); if (swap == NULL) { mtx_unlock(&swhash_mtx); VM_OBJECT_WUNLOCK(object); if (uma_zone_exhausted(swap_zone)) { if (atomic_cmpset_int(&exhausted, 0, 1)) printf("swap zone exhausted, " "increase kern.maxswzone\n"); vm_pageout_oom(VM_OOM_SWAPZ); pause("swzonex", 10); } else VM_WAIT; VM_OBJECT_WLOCK(object); goto retry; } if (atomic_cmpset_int(&exhausted, 1, 0)) printf("swap zone ok\n"); 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; done: mtx_unlock(&swhash_mtx); } /* * 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. */ static void swp_pager_meta_free(vm_object_t object, vm_pindex_t index, vm_pindex_t count) { struct swblock **pswap, *swap; vm_pindex_t c; daddr_t v; int n, sidx; VM_OBJECT_ASSERT_LOCKED(object); if (object->type != OBJT_SWAP || count == 0) return; mtx_lock(&swhash_mtx); for (c = 0; c < count;) { pswap = swp_pager_hash(object, index); sidx = index & SWAP_META_MASK; n = SWAP_META_PAGES - sidx; index += n; if ((swap = *pswap) == NULL) { c += n; continue; } for (; c < count && sidx < SWAP_META_PAGES; ++c, ++sidx) { if ((v = swap->swb_pages[sidx]) == SWAPBLK_NONE) continue; swp_pager_freeswapspace(v, 1); swap->swb_pages[sidx] = SWAPBLK_NONE; if (--swap->swb_count == 0) { *pswap = swap->swb_hnext; uma_zfree(swap_zone, swap); --object->un_pager.swp.swp_bcount; c += SWAP_META_PAGES - sidx; break; } } } mtx_unlock(&swhash_mtx); } /* * SWP_PAGER_META_FREE_ALL() - destroy all swap metadata associated with object * * This routine locates and destroys all swap metadata associated with * an object. */ static void swp_pager_meta_free_all(vm_object_t object) { struct swblock **pswap, *swap; vm_pindex_t index; daddr_t v; int i; VM_OBJECT_ASSERT_WLOCKED(object); if (object->type != OBJT_SWAP) return; index = 0; while (object->un_pager.swp.swp_bcount != 0) { mtx_lock(&swhash_mtx); pswap = swp_pager_hash(object, index); if ((swap = *pswap) != NULL) { for (i = 0; i < SWAP_META_PAGES; ++i) { 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; } mtx_unlock(&swhash_mtx); index += SWAP_META_PAGES; } } /* * 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. * * 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; VM_OBJECT_ASSERT_LOCKED(object); /* * 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; mtx_lock(&swhash_mtx); 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; } } } } mtx_unlock(&swhash_mtx); return (r1); } /* * Returns the least page index which is greater than or equal to the * parameter pindex and for which there is a swap block allocated. * Returns object's size if the object's type is not swap or if there * are no allocated swap blocks for the object after the requested * pindex. */ vm_pindex_t swap_pager_find_least(vm_object_t object, vm_pindex_t pindex) { struct swblock **pswap, *swap; vm_pindex_t i, j, lim; int idx; VM_OBJECT_ASSERT_LOCKED(object); if (object->type != OBJT_SWAP || object->un_pager.swp.swp_bcount == 0) return (object->size); mtx_lock(&swhash_mtx); for (j = pindex; j < object->size; j = lim) { pswap = swp_pager_hash(object, j); lim = rounddown2(j + SWAP_META_PAGES, SWAP_META_PAGES); if (lim > object->size) lim = object->size; if ((swap = *pswap) != NULL) { for (idx = j & SWAP_META_MASK, i = j; i < lim; i++, idx++) { if (swap->swb_pages[idx] != SWAPBLK_NONE) goto found; } } } i = object->size; found: mtx_unlock(&swhash_mtx); return (i); } /* * 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 sys_swapon(struct thread *td, struct swapon_args *uap) { struct vattr attr; struct vnode *vp; struct nameidata nd; int error; error = priv_check(td, PRIV_SWAPON); if (error) return (error); sx_xlock(&swdev_syscall_lock); /* * 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, ISOPEN | FOLLOW | AUDITVNODE1, 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 = swapongeom(vp); } else if (vp->v_type == VREG && (vp->v_mount->mnt_vfc->vfc_flags & VFCF_NETWORK) != 0 && (error = VOP_GETATTR(vp, &attr, td->td_ucred)) == 0) { /* * Allow direct swapping to NFS regular files in the same * way that nfs_mountroot() sets up diskless swapping. */ error = swaponvp(td, vp, attr.va_size / DEV_BSIZE); } if (error) vrele(vp); done: sx_xunlock(&swdev_syscall_lock); return (error); } /* * Check that the total amount of swap currently configured does not * exceed half the theoretical maximum. If it does, print a warning * message and return -1; otherwise, return 0. */ static int swapon_check_swzone(unsigned long npages) { unsigned long maxpages; /* absolute maximum we can handle assuming 100% efficiency */ maxpages = uma_zone_get_max(swap_zone) * SWAP_META_PAGES; /* recommend using no more than half that amount */ if (npages > maxpages / 2) { printf("warning: total configured swap (%lu pages) " "exceeds maximum recommended amount (%lu pages).\n", npages, maxpages / 2); printf("warning: increase kern.maxswzone " "or reduce amount of swap.\n"); return (-1); } return (0); } static void swaponsomething(struct vnode *vp, void *id, u_long nblks, sw_strategy_t *strategy, sw_close_t *close, dev_t dev, int flags) { struct swdevt *sp, *tsp; swblk_t dvbase; u_long 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); /* * 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 swap size to maximum of %luMB per unit\n", mblocks / 1024 / 1024 * PAGE_SIZE); nblks = mblocks; } sp = malloc(sizeof *sp, M_VMPGDATA, M_WAITOK | M_ZERO); sp->sw_vp = vp; sp->sw_id = id; sp->sw_dev = dev; sp->sw_flags = 0; sp->sw_nblks = nblks; sp->sw_used = 0; sp->sw_strategy = strategy; sp->sw_close = close; sp->sw_flags = flags; sp->sw_blist = blist_create(nblks, M_WAITOK); /* * Do not free the first two block in order to avoid overwriting * any bsd label at the front of the partition */ blist_free(sp->sw_blist, 2, nblks - 2); dvbase = 0; mtx_lock(&sw_dev_mtx); TAILQ_FOREACH(tsp, &swtailq, sw_list) { if (tsp->sw_end >= dvbase) { /* * We put one uncovered page between the devices * in order to definitively prevent any cross-device * I/O requests */ dvbase = tsp->sw_end + 1; } } sp->sw_first = dvbase; sp->sw_end = dvbase + nblks; TAILQ_INSERT_TAIL(&swtailq, sp, sw_list); nswapdev++; swap_pager_avail += nblks; swap_total += (vm_ooffset_t)nblks * PAGE_SIZE; swapon_check_swzone(swap_total / PAGE_SIZE); swp_sizecheck(); mtx_unlock(&sw_dev_mtx); EVENTHANDLER_INVOKE(swapon, sp); } /* * SYSCALL: swapoff(devname) * * Disable swapping on the given device. * * XXX: Badly designed system call: it should use a device index * rather than filename as specification. We keep sw_vp around * only to make this work. */ #ifndef _SYS_SYSPROTO_H_ struct swapoff_args { char *name; }; #endif /* * MPSAFE */ /* ARGSUSED */ int sys_swapoff(struct thread *td, struct swapoff_args *uap) { struct vnode *vp; struct nameidata nd; struct swdevt *sp; int error; error = priv_check(td, PRIV_SWAPOFF); if (error) return (error); sx_xlock(&swdev_syscall_lock); NDINIT(&nd, LOOKUP, FOLLOW | AUDITVNODE1, UIO_USERSPACE, uap->name, td); error = namei(&nd); if (error) goto done; NDFREE(&nd, NDF_ONLY_PNBUF); vp = nd.ni_vp; mtx_lock(&sw_dev_mtx); TAILQ_FOREACH(sp, &swtailq, sw_list) { if (sp->sw_vp == vp) break; } mtx_unlock(&sw_dev_mtx); if (sp == NULL) { error = EINVAL; goto done; } error = swapoff_one(sp, td->td_ucred); done: sx_xunlock(&swdev_syscall_lock); return (error); } static int swapoff_one(struct swdevt *sp, struct ucred *cred) { u_long nblks, dvbase; #ifdef MAC int error; #endif sx_assert(&swdev_syscall_lock, SA_XLOCKED); #ifdef MAC (void) vn_lock(sp->sw_vp, LK_EXCLUSIVE | LK_RETRY); error = mac_system_check_swapoff(cred, sp->sw_vp); (void) VOP_UNLOCK(sp->sw_vp, 0); if (error != 0) return (error); #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 (vm_cnt.v_free_count + swap_pager_avail < nblks + nswap_lowat) return (ENOMEM); /* * Prevent further allocations on this device. */ mtx_lock(&sw_dev_mtx); sp->sw_flags |= SW_CLOSING; for (dvbase = 0; dvbase < nblks; dvbase += BLIST_BMAP_RADIX) { /* * blist_fill() cannot allocate more than BLIST_BMAP_RADIX * blocks per call. */ swap_pager_avail -= blist_fill(sp->sw_blist, dvbase, ulmin(nblks - dvbase, BLIST_BMAP_RADIX)); } swap_total -= (vm_ooffset_t)nblks * PAGE_SIZE; mtx_unlock(&sw_dev_mtx); /* * Page in the contents of the device and close it. */ swap_pager_swapoff(sp); sp->sw_close(curthread, sp); mtx_lock(&sw_dev_mtx); sp->sw_id = NULL; TAILQ_REMOVE(&swtailq, sp, sw_list); nswapdev--; if (nswapdev == 0) { swap_pager_full = 2; swap_pager_almost_full = 1; } if (swdevhd == sp) swdevhd = NULL; mtx_unlock(&sw_dev_mtx); blist_destroy(sp->sw_blist); free(sp, M_VMPGDATA); return (0); } void swapoff_all(void) { struct swdevt *sp, *spt; const char *devname; int error; sx_xlock(&swdev_syscall_lock); mtx_lock(&sw_dev_mtx); TAILQ_FOREACH_SAFE(sp, &swtailq, sw_list, spt) { mtx_unlock(&sw_dev_mtx); if (vn_isdisk(sp->sw_vp, NULL)) devname = devtoname(sp->sw_vp->v_rdev); else devname = "[file]"; error = swapoff_one(sp, thread0.td_ucred); if (error != 0) { printf("Cannot remove swap device %s (error=%d), " "skipping.\n", devname, error); } else if (bootverbose) { printf("Swap device %s removed.\n", devname); } mtx_lock(&sw_dev_mtx); } mtx_unlock(&sw_dev_mtx); sx_xunlock(&swdev_syscall_lock); } void swap_pager_status(int *total, int *used) { struct swdevt *sp; *total = 0; *used = 0; mtx_lock(&sw_dev_mtx); TAILQ_FOREACH(sp, &swtailq, sw_list) { *total += sp->sw_nblks; *used += sp->sw_used; } mtx_unlock(&sw_dev_mtx); } int swap_dev_info(int name, struct xswdev *xs, char *devname, size_t len) { struct swdevt *sp; const char *tmp_devname; int error, n; n = 0; error = ENOENT; mtx_lock(&sw_dev_mtx); TAILQ_FOREACH(sp, &swtailq, sw_list) { if (n != name) { n++; continue; } 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; if (devname != NULL) { if (vn_isdisk(sp->sw_vp, NULL)) tmp_devname = devtoname(sp->sw_vp->v_rdev); else tmp_devname = "[file]"; strncpy(devname, tmp_devname, len); } error = 0; break; } mtx_unlock(&sw_dev_mtx); return (error); } #if defined(COMPAT_FREEBSD11) #define XSWDEV_VERSION_11 1 struct xswdev11 { u_int xsw_version; uint32_t xsw_dev; int xsw_flags; int xsw_nblks; int xsw_used; }; #endif static int sysctl_vm_swap_info(SYSCTL_HANDLER_ARGS) { struct xswdev xs; #if defined(COMPAT_FREEBSD11) struct xswdev11 xs11; #endif int error; if (arg2 != 1) /* name length */ return (EINVAL); error = swap_dev_info(*(int *)arg1, &xs, NULL, 0); if (error != 0) return (error); #if defined(COMPAT_FREEBSD11) if (req->oldlen == sizeof(xs11)) { xs11.xsw_version = XSWDEV_VERSION_11; xs11.xsw_dev = xs.xsw_dev; /* truncation */ xs11.xsw_flags = xs.xsw_flags; xs11.xsw_nblks = xs.xsw_nblks; xs11.xsw_used = xs.xsw_used; error = SYSCTL_OUT(req, &xs11, sizeof(xs11)); } else #endif error = SYSCTL_OUT(req, &xs, sizeof(xs)); return (error); } SYSCTL_INT(_vm, OID_AUTO, nswapdev, CTLFLAG_RD, &nswapdev, 0, "Number of swap devices"); SYSCTL_NODE(_vm, OID_AUTO, swap_info, CTLFLAG_RD | CTLFLAG_MPSAFE, sysctl_vm_swap_info, "Swap statistics by device"); /* * vmspace_swap_count() - count the approximate swap usage in pages for a * vmspace. * * The map must be locked. * * Swap usage 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. */ long vmspace_swap_count(struct vmspace *vmspace) { vm_map_t map; vm_map_entry_t cur; vm_object_t object; long count, n; map = &vmspace->vm_map; count = 0; for (cur = map->header.next; cur != &map->header; cur = cur->next) { if ((cur->eflags & MAP_ENTRY_IS_SUB_MAP) == 0 && (object = cur->object.vm_object) != NULL) { VM_OBJECT_WLOCK(object); if (object->type == OBJT_SWAP && object->un_pager.swp.swp_bcount != 0) { n = (cur->end - cur->start) / PAGE_SIZE; count += object->un_pager.swp.swp_bcount * SWAP_META_PAGES * n / object->size + 1; } VM_OBJECT_WUNLOCK(object); } } return (count); } /* * GEOM backend * * Swapping onto disk devices. * */ static g_orphan_t swapgeom_orphan; static struct g_class g_swap_class = { .name = "SWAP", .version = G_VERSION, .orphan = swapgeom_orphan, }; DECLARE_GEOM_CLASS(g_swap_class, g_class); static void swapgeom_close_ev(void *arg, int flags) { struct g_consumer *cp; cp = arg; g_access(cp, -1, -1, 0); g_detach(cp); g_destroy_consumer(cp); } /* * Add a reference to the g_consumer for an inflight transaction. */ static void swapgeom_acquire(struct g_consumer *cp) { mtx_assert(&sw_dev_mtx, MA_OWNED); cp->index++; } /* * Remove a reference from the g_consumer. Post a close event if all * references go away, since the function might be called from the * biodone context. */ static void swapgeom_release(struct g_consumer *cp, struct swdevt *sp) { mtx_assert(&sw_dev_mtx, MA_OWNED); cp->index--; if (cp->index == 0) { if (g_post_event(swapgeom_close_ev, cp, M_NOWAIT, NULL) == 0) sp->sw_id = NULL; } } static void swapgeom_done(struct bio *bp2) { struct swdevt *sp; struct buf *bp; struct g_consumer *cp; bp = bp2->bio_caller2; cp = bp2->bio_from; bp->b_ioflags = bp2->bio_flags; if (bp2->bio_error) bp->b_ioflags |= BIO_ERROR; bp->b_resid = bp->b_bcount - bp2->bio_completed; bp->b_error = bp2->bio_error; bufdone(bp); sp = bp2->bio_caller1; mtx_lock(&sw_dev_mtx); swapgeom_release(cp, sp); mtx_unlock(&sw_dev_mtx); g_destroy_bio(bp2); } static void swapgeom_strategy(struct buf *bp, struct swdevt *sp) { struct bio *bio; struct g_consumer *cp; mtx_lock(&sw_dev_mtx); cp = sp->sw_id; if (cp == NULL) { mtx_unlock(&sw_dev_mtx); bp->b_error = ENXIO; bp->b_ioflags |= BIO_ERROR; bufdone(bp); return; } swapgeom_acquire(cp); mtx_unlock(&sw_dev_mtx); if (bp->b_iocmd == BIO_WRITE) bio = g_new_bio(); else bio = g_alloc_bio(); if (bio == NULL) { mtx_lock(&sw_dev_mtx); swapgeom_release(cp, sp); mtx_unlock(&sw_dev_mtx); bp->b_error = ENOMEM; bp->b_ioflags |= BIO_ERROR; bufdone(bp); return; } bio->bio_caller1 = sp; bio->bio_caller2 = bp; bio->bio_cmd = bp->b_iocmd; bio->bio_offset = (bp->b_blkno - sp->sw_first) * PAGE_SIZE; bio->bio_length = bp->b_bcount; bio->bio_done = swapgeom_done; if (!buf_mapped(bp)) { bio->bio_ma = bp->b_pages; bio->bio_data = unmapped_buf; bio->bio_ma_offset = (vm_offset_t)bp->b_offset & PAGE_MASK; bio->bio_ma_n = bp->b_npages; bio->bio_flags |= BIO_UNMAPPED; } else { bio->bio_data = bp->b_data; bio->bio_ma = NULL; } g_io_request(bio, cp); return; } static void swapgeom_orphan(struct g_consumer *cp) { struct swdevt *sp; int destroy; mtx_lock(&sw_dev_mtx); TAILQ_FOREACH(sp, &swtailq, sw_list) { if (sp->sw_id == cp) { sp->sw_flags |= SW_CLOSING; break; } } /* * Drop reference we were created with. Do directly since we're in a * special context where we don't have to queue the call to * swapgeom_close_ev(). */ cp->index--; destroy = ((sp != NULL) && (cp->index == 0)); if (destroy) sp->sw_id = NULL; mtx_unlock(&sw_dev_mtx); if (destroy) swapgeom_close_ev(cp, 0); } static void swapgeom_close(struct thread *td, struct swdevt *sw) { struct g_consumer *cp; mtx_lock(&sw_dev_mtx); cp = sw->sw_id; sw->sw_id = NULL; mtx_unlock(&sw_dev_mtx); /* * swapgeom_close() may be called from the biodone context, * where we cannot perform topology changes. Delegate the * work to the events thread. */ if (cp != NULL) g_waitfor_event(swapgeom_close_ev, cp, M_WAITOK, NULL); } static int swapongeom_locked(struct cdev *dev, struct vnode *vp) { struct g_provider *pp; struct g_consumer *cp; static struct g_geom *gp; struct swdevt *sp; u_long nblks; int error; pp = g_dev_getprovider(dev); if (pp == NULL) return (ENODEV); mtx_lock(&sw_dev_mtx); TAILQ_FOREACH(sp, &swtailq, sw_list) { cp = sp->sw_id; if (cp != NULL && cp->provider == pp) { mtx_unlock(&sw_dev_mtx); return (EBUSY); } } mtx_unlock(&sw_dev_mtx); if (gp == NULL) gp = g_new_geomf(&g_swap_class, "swap"); cp = g_new_consumer(gp); cp->index = 1; /* Number of active I/Os, plus one for being active. */ cp->flags |= G_CF_DIRECT_SEND | G_CF_DIRECT_RECEIVE; g_attach(cp, pp); /* * XXX: Every time you think you can improve the margin for * footshooting, somebody depends on the ability to do so: * savecore(8) wants to write to our swapdev so we cannot * set an exclusive count :-( */ error = g_access(cp, 1, 1, 0); if (error != 0) { g_detach(cp); g_destroy_consumer(cp); return (error); } nblks = pp->mediasize / DEV_BSIZE; swaponsomething(vp, cp, nblks, swapgeom_strategy, swapgeom_close, dev2udev(dev), (pp->flags & G_PF_ACCEPT_UNMAPPED) != 0 ? SW_UNMAPPED : 0); return (0); } static int swapongeom(struct vnode *vp) { int error; vn_lock(vp, LK_EXCLUSIVE | LK_RETRY); if (vp->v_type != VCHR || (vp->v_iflag & VI_DOOMED) != 0) { error = ENOENT; } else { g_topology_lock(); error = swapongeom_locked(vp->v_rdev, vp); g_topology_unlock(); } VOP_UNLOCK(vp, 0); return (error); } /* * VNODE backend * * This is used mainly for network filesystem (read: probably only tested * with NFS) swapfiles. * */ static void swapdev_strategy(struct buf *bp, struct swdevt *sp) { struct vnode *vp2; bp->b_blkno = ctodb(bp->b_blkno - sp->sw_first); vp2 = sp->sw_id; vhold(vp2); if (bp->b_iocmd == BIO_WRITE) { if (bp->b_bufobj) bufobj_wdrop(bp->b_bufobj); bufobj_wref(&vp2->v_bufobj); } if (bp->b_bufobj != &vp2->v_bufobj) bp->b_bufobj = &vp2->v_bufobj; bp->b_vp = vp2; bp->b_iooffset = dbtob(bp->b_blkno); bstrategy(bp); return; } static void swapdev_close(struct thread *td, struct swdevt *sp) { VOP_CLOSE(sp->sw_vp, FREAD | FWRITE, td->td_ucred, td); vrele(sp->sw_vp); } static int swaponvp(struct thread *td, struct vnode *vp, u_long nblks) { struct swdevt *sp; int error; if (nblks == 0) return (ENXIO); mtx_lock(&sw_dev_mtx); TAILQ_FOREACH(sp, &swtailq, sw_list) { if (sp->sw_id == vp) { mtx_unlock(&sw_dev_mtx); return (EBUSY); } } mtx_unlock(&sw_dev_mtx); (void) vn_lock(vp, LK_EXCLUSIVE | LK_RETRY); #ifdef MAC error = mac_system_check_swapon(td->td_ucred, vp); if (error == 0) #endif error = VOP_OPEN(vp, FREAD | FWRITE, td->td_ucred, td, NULL); (void) VOP_UNLOCK(vp, 0); if (error) return (error); swaponsomething(vp, vp, nblks, swapdev_strategy, swapdev_close, NODEV, 0); return (0); } static int sysctl_swap_async_max(SYSCTL_HANDLER_ARGS) { int error, new, n; new = nsw_wcount_async_max; error = sysctl_handle_int(oidp, &new, 0, req); if (error != 0 || req->newptr == NULL) return (error); if (new > nswbuf / 2 || new < 1) return (EINVAL); mtx_lock(&pbuf_mtx); while (nsw_wcount_async_max != new) { /* * Adjust difference. If the current async count is too low, * we will need to sqeeze our update slowly in. Sleep with a * higher priority than getpbuf() to finish faster. */ n = new - nsw_wcount_async_max; if (nsw_wcount_async + n >= 0) { nsw_wcount_async += n; nsw_wcount_async_max += n; wakeup(&nsw_wcount_async); } else { nsw_wcount_async_max -= nsw_wcount_async; nsw_wcount_async = 0; msleep(&nsw_wcount_async, &pbuf_mtx, PSWP, "swpsysctl", 0); } } mtx_unlock(&pbuf_mtx); return (0); }