/*- * Copyright (c) 1991, 1993 * The Regents of the University of California. All rights reserved. * * This code is derived from software contributed to Berkeley by * The Mach Operating System project at Carnegie-Mellon University. * * 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. * 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. * * from: @(#)vm_pager.c 8.6 (Berkeley) 1/12/94 * * * Copyright (c) 1987, 1990 Carnegie-Mellon University. * All rights reserved. * * Authors: Avadis Tevanian, Jr., Michael Wayne Young * * Permission to use, copy, modify and distribute this software and * its documentation is hereby granted, provided that both the copyright * notice and this permission notice appear in all copies of the * software, derivative works or modified versions, and any portions * thereof, and that both notices appear in supporting documentation. * * CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS "AS IS" * CONDITION. CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND * FOR ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE. * * Carnegie Mellon requests users of this software to return to * * Software Distribution Coordinator or Software.Distribution@CS.CMU.EDU * School of Computer Science * Carnegie Mellon University * Pittsburgh PA 15213-3890 * * any improvements or extensions that they make and grant Carnegie the * rights to redistribute these changes. */ /* * Paging space routine stubs. Emulates a matchmaker-like interface * for builtin pagers. */ #include __FBSDID("$FreeBSD$"); #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include int cluster_pbuf_freecnt = -1; /* unlimited to begin with */ struct buf *swbuf; static int dead_pager_getpages(vm_object_t, vm_page_t *, int, int *, int *); static vm_object_t dead_pager_alloc(void *, vm_ooffset_t, vm_prot_t, vm_ooffset_t, struct ucred *); static void dead_pager_putpages(vm_object_t, vm_page_t *, int, int, int *); static boolean_t dead_pager_haspage(vm_object_t, vm_pindex_t, int *, int *); static void dead_pager_dealloc(vm_object_t); static int dead_pager_getpages(vm_object_t obj, vm_page_t *ma, int count, int *rbehind, int *rahead) { return (VM_PAGER_FAIL); } static vm_object_t dead_pager_alloc(void *handle, vm_ooffset_t size, vm_prot_t prot, vm_ooffset_t off, struct ucred *cred) { return (NULL); } static void dead_pager_putpages(vm_object_t object, vm_page_t *m, int count, int flags, int *rtvals) { int i; for (i = 0; i < count; i++) rtvals[i] = VM_PAGER_AGAIN; } static int dead_pager_haspage(vm_object_t object, vm_pindex_t pindex, int *prev, int *next) { if (prev != NULL) *prev = 0; if (next != NULL) *next = 0; return (FALSE); } static void dead_pager_dealloc(vm_object_t object) { } static struct pagerops deadpagerops = { .pgo_alloc = dead_pager_alloc, .pgo_dealloc = dead_pager_dealloc, .pgo_getpages = dead_pager_getpages, .pgo_putpages = dead_pager_putpages, .pgo_haspage = dead_pager_haspage, }; struct pagerops *pagertab[] = { &defaultpagerops, /* OBJT_DEFAULT */ &swappagerops, /* OBJT_SWAP */ &vnodepagerops, /* OBJT_VNODE */ &devicepagerops, /* OBJT_DEVICE */ &physpagerops, /* OBJT_PHYS */ &deadpagerops, /* OBJT_DEAD */ &sgpagerops, /* OBJT_SG */ &mgtdevicepagerops, /* OBJT_MGTDEVICE */ }; /* * Kernel address space for mapping pages. * Used by pagers where KVAs are needed for IO. * * XXX needs to be large enough to support the number of pending async * cleaning requests (NPENDINGIO == 64) * the maximum swap cluster size * (MAXPHYS == 64k) if you want to get the most efficiency. */ struct mtx_padalign __exclusive_cache_line pbuf_mtx; static TAILQ_HEAD(swqueue, buf) bswlist; static int bswneeded; vm_offset_t swapbkva; /* swap buffers kva */ void vm_pager_init(void) { struct pagerops **pgops; TAILQ_INIT(&bswlist); /* * Initialize known pagers */ for (pgops = pagertab; pgops < &pagertab[nitems(pagertab)]; pgops++) if ((*pgops)->pgo_init != NULL) (*(*pgops)->pgo_init)(); } void vm_pager_bufferinit(void) { struct buf *bp; int i; mtx_init(&pbuf_mtx, "pbuf mutex", NULL, MTX_DEF); bp = swbuf; /* * Now set up swap and physical I/O buffer headers. */ for (i = 0; i < nswbuf; i++, bp++) { TAILQ_INSERT_HEAD(&bswlist, bp, b_freelist); BUF_LOCKINIT(bp); LIST_INIT(&bp->b_dep); bp->b_rcred = bp->b_wcred = NOCRED; bp->b_xflags = 0; } cluster_pbuf_freecnt = nswbuf / 2; vnode_pbuf_freecnt = nswbuf / 2 + 1; vnode_async_pbuf_freecnt = nswbuf / 2; } /* * Allocate an instance of a pager of the given type. * Size, protection and offset parameters are passed in for pagers that * need to perform page-level validation (e.g. the device pager). */ vm_object_t vm_pager_allocate(objtype_t type, void *handle, vm_ooffset_t size, vm_prot_t prot, vm_ooffset_t off, struct ucred *cred) { vm_object_t ret; struct pagerops *ops; ops = pagertab[type]; if (ops) ret = (*ops->pgo_alloc)(handle, size, prot, off, cred); else ret = NULL; return (ret); } /* * The object must be locked. */ void vm_pager_deallocate(vm_object_t object) { VM_OBJECT_ASSERT_WLOCKED(object); (*pagertab[object->type]->pgo_dealloc) (object); } static void vm_pager_assert_in(vm_object_t object, vm_page_t *m, int count) { #ifdef INVARIANTS VM_OBJECT_ASSERT_WLOCKED(object); KASSERT(count > 0, ("%s: 0 count", __func__)); /* * All pages must be busied, not mapped, not fully valid, * not dirty and belong to the proper object. */ for (int i = 0 ; i < count; i++) { vm_page_assert_xbusied(m[i]); KASSERT(!pmap_page_is_mapped(m[i]), ("%s: page %p is mapped", __func__, m[i])); KASSERT(m[i]->valid != VM_PAGE_BITS_ALL, ("%s: request for a valid page %p", __func__, m[i])); KASSERT(m[i]->dirty == 0, ("%s: page %p is dirty", __func__, m[i])); KASSERT(m[i]->object == object, ("%s: wrong object %p/%p", __func__, object, m[i]->object)); } #endif } /* * Page in the pages for the object using its associated pager. * The requested page must be fully valid on successful return. */ int vm_pager_get_pages(vm_object_t object, vm_page_t *m, int count, int *rbehind, int *rahead) { #ifdef INVARIANTS vm_pindex_t pindex = m[0]->pindex; #endif int r; vm_pager_assert_in(object, m, count); r = (*pagertab[object->type]->pgo_getpages)(object, m, count, rbehind, rahead); if (r != VM_PAGER_OK) return (r); for (int i = 0; i < count; i++) { /* * If pager has replaced a page, assert that it had * updated the array. */ KASSERT(m[i] == vm_page_lookup(object, pindex++), ("%s: mismatch page %p pindex %ju", __func__, m[i], (uintmax_t )pindex - 1)); /* * Zero out partially filled data. */ if (m[i]->valid != VM_PAGE_BITS_ALL) vm_page_zero_invalid(m[i], TRUE); } return (VM_PAGER_OK); } int vm_pager_get_pages_async(vm_object_t object, vm_page_t *m, int count, int *rbehind, int *rahead, pgo_getpages_iodone_t iodone, void *arg) { vm_pager_assert_in(object, m, count); return ((*pagertab[object->type]->pgo_getpages_async)(object, m, count, rbehind, rahead, iodone, arg)); } /* * vm_pager_put_pages() - inline, see vm/vm_pager.h * vm_pager_has_page() - inline, see vm/vm_pager.h */ /* * Search the specified pager object list for an object with the * specified handle. If an object with the specified handle is found, * increase its reference count and return it. Otherwise, return NULL. * * The pager object list must be locked. */ vm_object_t vm_pager_object_lookup(struct pagerlst *pg_list, void *handle) { vm_object_t object; TAILQ_FOREACH(object, pg_list, pager_object_list) { if (object->handle == handle) { VM_OBJECT_WLOCK(object); if ((object->flags & OBJ_DEAD) == 0) { vm_object_reference_locked(object); VM_OBJECT_WUNLOCK(object); break; } VM_OBJECT_WUNLOCK(object); } } return (object); } /* * initialize a physical buffer */ /* * XXX This probably belongs in vfs_bio.c */ static void initpbuf(struct buf *bp) { KASSERT(bp->b_bufobj == NULL, ("initpbuf with bufobj")); KASSERT(bp->b_vp == NULL, ("initpbuf with vp")); bp->b_rcred = NOCRED; bp->b_wcred = NOCRED; bp->b_qindex = 0; /* On no queue (QUEUE_NONE) */ bp->b_kvabase = (caddr_t)(MAXPHYS * (bp - swbuf)) + swapbkva; bp->b_data = bp->b_kvabase; bp->b_kvasize = MAXPHYS; bp->b_flags = 0; bp->b_xflags = 0; bp->b_ioflags = 0; bp->b_iodone = NULL; bp->b_error = 0; BUF_LOCK(bp, LK_EXCLUSIVE, NULL); } /* * allocate a physical buffer * * There are a limited number (nswbuf) of physical buffers. We need * to make sure that no single subsystem is able to hog all of them, * so each subsystem implements a counter which is typically initialized * to 1/2 nswbuf. getpbuf() decrements this counter in allocation and * increments it on release, and blocks if the counter hits zero. A * subsystem may initialize the counter to -1 to disable the feature, * but it must still be sure to match up all uses of getpbuf() with * relpbuf() using the same variable. * * NOTE: pfreecnt can be NULL, but this 'feature' will be removed * relatively soon when the rest of the subsystems get smart about it. XXX */ struct buf * getpbuf(int *pfreecnt) { struct buf *bp; mtx_lock(&pbuf_mtx); for (;;) { if (pfreecnt != NULL) { while (*pfreecnt == 0) { msleep(pfreecnt, &pbuf_mtx, PVM, "wswbuf0", 0); } } /* get a bp from the swap buffer header pool */ if ((bp = TAILQ_FIRST(&bswlist)) != NULL) break; bswneeded = 1; msleep(&bswneeded, &pbuf_mtx, PVM, "wswbuf1", 0); /* loop in case someone else grabbed one */ } TAILQ_REMOVE(&bswlist, bp, b_freelist); if (pfreecnt) --*pfreecnt; mtx_unlock(&pbuf_mtx); initpbuf(bp); return (bp); } /* * allocate a physical buffer, if one is available. * * Note that there is no NULL hack here - all subsystems using this * call understand how to use pfreecnt. */ struct buf * trypbuf(int *pfreecnt) { struct buf *bp; mtx_lock(&pbuf_mtx); if (*pfreecnt == 0 || (bp = TAILQ_FIRST(&bswlist)) == NULL) { mtx_unlock(&pbuf_mtx); return NULL; } TAILQ_REMOVE(&bswlist, bp, b_freelist); --*pfreecnt; mtx_unlock(&pbuf_mtx); initpbuf(bp); return (bp); } /* * release a physical buffer * * NOTE: pfreecnt can be NULL, but this 'feature' will be removed * relatively soon when the rest of the subsystems get smart about it. XXX */ void relpbuf(struct buf *bp, int *pfreecnt) { if (bp->b_rcred != NOCRED) { crfree(bp->b_rcred); bp->b_rcred = NOCRED; } if (bp->b_wcred != NOCRED) { crfree(bp->b_wcred); bp->b_wcred = NOCRED; } KASSERT(bp->b_vp == NULL, ("relpbuf with vp")); KASSERT(bp->b_bufobj == NULL, ("relpbuf with bufobj")); BUF_UNLOCK(bp); mtx_lock(&pbuf_mtx); TAILQ_INSERT_HEAD(&bswlist, bp, b_freelist); if (bswneeded) { bswneeded = 0; wakeup(&bswneeded); } if (pfreecnt) { if (++*pfreecnt == 1) wakeup(pfreecnt); } mtx_unlock(&pbuf_mtx); } /* * Associate a p-buffer with a vnode. * * Also sets B_PAGING flag to indicate that vnode is not fully associated * with the buffer. i.e. the bp has not been linked into the vnode or * ref-counted. */ void pbgetvp(struct vnode *vp, struct buf *bp) { KASSERT(bp->b_vp == NULL, ("pbgetvp: not free")); KASSERT(bp->b_bufobj == NULL, ("pbgetvp: not free (bufobj)")); bp->b_vp = vp; bp->b_flags |= B_PAGING; bp->b_bufobj = &vp->v_bufobj; } /* * Associate a p-buffer with a vnode. * * Also sets B_PAGING flag to indicate that vnode is not fully associated * with the buffer. i.e. the bp has not been linked into the vnode or * ref-counted. */ void pbgetbo(struct bufobj *bo, struct buf *bp) { KASSERT(bp->b_vp == NULL, ("pbgetbo: not free (vnode)")); KASSERT(bp->b_bufobj == NULL, ("pbgetbo: not free (bufobj)")); bp->b_flags |= B_PAGING; bp->b_bufobj = bo; } /* * Disassociate a p-buffer from a vnode. */ void pbrelvp(struct buf *bp) { KASSERT(bp->b_vp != NULL, ("pbrelvp: NULL")); KASSERT(bp->b_bufobj != NULL, ("pbrelvp: NULL bufobj")); KASSERT((bp->b_xflags & (BX_VNDIRTY | BX_VNCLEAN)) == 0, ("pbrelvp: pager buf on vnode list.")); bp->b_vp = NULL; bp->b_bufobj = NULL; bp->b_flags &= ~B_PAGING; } /* * Disassociate a p-buffer from a bufobj. */ void pbrelbo(struct buf *bp) { KASSERT(bp->b_vp == NULL, ("pbrelbo: vnode")); KASSERT(bp->b_bufobj != NULL, ("pbrelbo: NULL bufobj")); KASSERT((bp->b_xflags & (BX_VNDIRTY | BX_VNCLEAN)) == 0, ("pbrelbo: pager buf on vnode list.")); bp->b_bufobj = NULL; bp->b_flags &= ~B_PAGING; }