/* * (MPSAFE) * * Copyright (c) 1990 University of Utah. * Copyright (c) 1991 The Regents of the University of California. * All rights reserved. * Copyright (c) 1993, 1994 John S. Dyson * Copyright (c) 1995, David Greenman * * 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. 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: @(#)vnode_pager.c 7.5 (Berkeley) 4/20/91 * $FreeBSD: src/sys/vm/vnode_pager.c,v 1.116.2.7 2002/12/31 09:34:51 dillon Exp $ */ /* * Page to/from files (vnodes). */ /* * TODO: * Implement VOP_GETPAGES/PUTPAGES interface for filesystems. Will * greatly re-simplify the vnode_pager. */ #include <sys/param.h> #include <sys/systm.h> #include <sys/uio.h> #include <sys/kernel.h> #include <sys/proc.h> #include <sys/vnode.h> #include <sys/mount.h> #include <sys/buf.h> #include <sys/vmmeter.h> #include <sys/conf.h> #include <cpu/lwbuf.h> #include <vm/vm.h> #include <vm/vm_object.h> #include <vm/vm_page.h> #include <vm/vm_pager.h> #include <vm/vm_map.h> #include <vm/vnode_pager.h> #include <vm/swap_pager.h> #include <vm/vm_extern.h> #include <vm/vm_page2.h> static pgo_dealloc_t vnode_pager_dealloc; static pgo_getpage_t vnode_pager_getpage; static pgo_putpages_t vnode_pager_putpages; static pgo_haspage_t vnode_pager_haspage; struct pagerops vnodepagerops = { .pgo_dealloc = vnode_pager_dealloc, .pgo_getpage = vnode_pager_getpage, .pgo_putpages = vnode_pager_putpages, .pgo_haspage = vnode_pager_haspage }; static struct krate vbadrate = { 1 }; static struct krate vresrate = { 1 }; long vnode_pbuf_freecnt = -1; /* start out unlimited */ /* * Allocate a VM object for a vnode, typically a regular file vnode. * * Some additional information is required to generate a properly sized * object which covers the entire buffer cache buffer straddling the file * EOF. Userland does not see the extra pages as the VM fault code tests * against v_filesize. */ vm_object_t vnode_pager_alloc(void *handle, off_t length, vm_prot_t prot, off_t offset, int blksize, int boff) { vm_object_t object; struct vnode *vp; off_t loffset; vm_pindex_t lsize; /* * Pageout to vnode, no can do yet. */ if (handle == NULL) return (NULL); /* * XXX hack - This initialization should be put somewhere else. */ if (vnode_pbuf_freecnt < 0) { vnode_pbuf_freecnt = nswbuf_kva / 2 + 1; } /* * Serialize potential vnode/object teardowns and interlocks */ vp = (struct vnode *)handle; lwkt_gettoken(&vp->v_token); /* * If the object is being terminated, wait for it to * go away. */ object = vp->v_object; if (object) { vm_object_hold(object); KKASSERT((object->flags & OBJ_DEAD) == 0); } if (VREFCNT(vp) <= 0) panic("vnode_pager_alloc: no vnode reference"); /* * Round up to the *next* block, then destroy the buffers in question. * Since we are only removing some of the buffers we must rely on the * scan count to determine whether a loop is necessary. * * Destroy any pages beyond the last buffer. */ if (boff < 0) boff = (int)(length % blksize); if (boff) loffset = length + (blksize - boff); else loffset = length; lsize = OFF_TO_IDX(round_page64(loffset)); if (object == NULL) { /* * And an object of the appropriate size */ object = vm_object_allocate_hold(OBJT_VNODE, lsize); object->handle = handle; vp->v_object = object; vp->v_filesize = length; if (vp->v_mount && (vp->v_mount->mnt_kern_flag & MNTK_NOMSYNC)) vm_object_set_flag(object, OBJ_NOMSYNC); vref(vp); } else { vm_object_reference_quick(object); /* also vref's */ if (object->size != lsize) { kprintf("vnode_pager_alloc: Warning, objsize " "mismatch %jd/%jd vp=%p obj=%p\n", (intmax_t)object->size, (intmax_t)lsize, vp, object); } if (vp->v_filesize != length) { kprintf("vnode_pager_alloc: Warning, filesize " "mismatch %jd/%jd vp=%p obj=%p\n", (intmax_t)vp->v_filesize, (intmax_t)length, vp, object); } } vm_object_drop(object); lwkt_reltoken(&vp->v_token); return (object); } /* * Add a ref to a vnode's existing VM object, return the object or * NULL if the vnode did not have one. This does not create the * object (we can't since we don't know what the proper blocksize/boff * is to match the VFS's use of the buffer cache). * * The vnode must be referenced and is typically open. The object should * be stable in this situation. * * Returns the object with an additional reference but not locked. */ vm_object_t vnode_pager_reference(struct vnode *vp) { vm_object_t object; if ((object = vp->v_object) != NULL) vm_object_reference_quick(object); /* also vref's vnode */ return (object); } static void vnode_pager_dealloc(vm_object_t object) { struct vnode *vp = object->handle; if (vp == NULL) panic("vnode_pager_dealloc: pager already dealloced"); vm_object_pip_wait(object, "vnpdea"); object->handle = NULL; object->type = OBJT_DEAD; vp->v_object = NULL; vp->v_filesize = NOOFFSET; vclrflags(vp, VTEXT | VOBJBUF); swap_pager_freespace_all(object); } /* * Return whether the vnode pager has the requested page. */ static boolean_t vnode_pager_haspage(vm_object_t object, vm_pindex_t pindex) { struct vnode *vp = object->handle; off_t loffset; off_t doffset; int voff; int bsize; int error; /* * If no vp or vp is doomed or marked transparent to VM, we do not * have the page. */ if ((vp == NULL) || (vp->v_flag & VRECLAIMED)) return FALSE; /* * If filesystem no longer mounted or offset beyond end of file we do * not have the page. */ loffset = IDX_TO_OFF(pindex); if (vp->v_mount == NULL || loffset >= vp->v_filesize) return FALSE; bsize = vp->v_mount->mnt_stat.f_iosize; voff = loffset % bsize; /* * XXX (obsolete - before and after pointers are now NULL) * * BMAP returns byte counts before and after, where after * is inclusive of the base page. haspage must return page * counts before and after where after does not include the * base page. * * BMAP is allowed to return a *after of 0 for backwards * compatibility. The base page is still considered valid if * no error is returned. */ error = VOP_BMAP(vp, loffset - voff, &doffset, NULL, NULL, 0); if (error) return TRUE; if (doffset == NOOFFSET) return FALSE; return TRUE; } /* * Lets the VM system know about a change in size for a file. * We adjust our own internal size and flush any cached pages in * the associated object that are affected by the size change. * * NOTE: This routine may be invoked as a result of a pager put * operation (possibly at object termination time), so we must be careful. * * NOTE: vp->v_filesize is initialized to NOOFFSET (-1), be sure that * we do not blow up on the case. nsize will always be >= 0, however. */ void vnode_pager_setsize(struct vnode *vp, vm_ooffset_t nsize) { vm_pindex_t nobjsize; vm_pindex_t oobjsize; vm_object_t object; object = vp->v_object; if (object == NULL) return; vm_object_hold(object); KKASSERT(vp->v_object == object); /* * Hasn't changed size */ if (nsize == vp->v_filesize) { vm_object_drop(object); return; } /* * Has changed size. Adjust the VM object's size and v_filesize * before we start scanning pages to prevent new pages from being * allocated during the scan. */ nobjsize = OFF_TO_IDX(nsize + PAGE_MASK); oobjsize = object->size; object->size = nobjsize; /* * File has shrunk. Toss any cached pages beyond the new EOF. */ if (nsize < vp->v_filesize) { vp->v_filesize = nsize; if (nobjsize < oobjsize) { vm_object_page_remove(object, nobjsize, oobjsize, FALSE); } /* * This gets rid of garbage at the end of a page that is now * only partially backed by the vnode. Since we are setting * the entire page valid & clean after we are done we have * to be sure that the portion of the page within the file * bounds is already valid. If it isn't then making it * valid would create a corrupt block. */ if (nsize & PAGE_MASK) { vm_offset_t kva; vm_page_t m; m = vm_page_lookup_busy_wait(object, OFF_TO_IDX(nsize), TRUE, "vsetsz"); if (m && m->valid) { int base = (int)nsize & PAGE_MASK; int size = PAGE_SIZE - base; struct lwbuf *lwb; struct lwbuf lwb_cache; /* * Clear out partial-page garbage in case * the page has been mapped. * * This is byte aligned. */ lwb = lwbuf_alloc(m, &lwb_cache); kva = lwbuf_kva(lwb); bzero((caddr_t)kva + base, size); lwbuf_free(lwb); /* * XXX work around SMP data integrity race * by unmapping the page from user processes. * The garbage we just cleared may be mapped * to a user process running on another cpu * and this code is not running through normal * I/O channels which handle SMP issues for * us, so unmap page to synchronize all cpus. * * XXX should vm_pager_unmap_page() have * dealt with this? */ vm_page_protect(m, VM_PROT_NONE); /* * Clear out partial-page dirty bits. This * has the side effect of setting the valid * bits, but that is ok. There are a bunch * of places in the VM system where we expected * m->dirty == VM_PAGE_BITS_ALL. The file EOF * case is one of them. If the page is still * partially dirty, make it fully dirty. * * NOTE: We do not clear out the valid * bits. This would prevent bogus_page * replacement from working properly. * * NOTE: We do not want to clear the dirty * bit for a partial DEV_BSIZE'd truncation! * This is DEV_BSIZE aligned! */ vm_page_clear_dirty_beg_nonincl(m, base, size); if (m->dirty != 0) m->dirty = VM_PAGE_BITS_ALL; vm_page_wakeup(m); } else if (m) { vm_page_wakeup(m); } } } else { vp->v_filesize = nsize; } vm_object_drop(object); } /* * Release a page busied for a getpages operation. The page may have become * wired (typically due to being used by the buffer cache) or otherwise been * soft-busied and cannot be freed in that case. A held page can still be * freed. */ void vnode_pager_freepage(vm_page_t m) { if ((m->busy_count & PBUSY_MASK) || m->wire_count || (m->flags & PG_NEED_COMMIT)) { vm_page_activate(m); vm_page_wakeup(m); } else { vm_page_free(m); } } /* * EOPNOTSUPP is no longer legal. For local media VFS's that do not * implement their own VOP_GETPAGES, their VOP_GETPAGES should call to * vnode_pager_generic_getpages() to implement the previous behaviour. * * All other FS's should use the bypass to get to the local media * backing vp's VOP_GETPAGES. */ static int vnode_pager_getpage(vm_object_t object, vm_pindex_t pindex, vm_page_t *mpp, int seqaccess) { int rtval; struct vnode *vp; vp = object->handle; rtval = VOP_GETPAGES(vp, mpp, PAGE_SIZE, 0, 0, seqaccess); if (rtval == EOPNOTSUPP) panic("vnode_pager: vfs's must implement vop_getpages"); return rtval; } /* * This is now called from local media FS's to operate against their * own vnodes if they fail to implement VOP_GETPAGES. * * With all the caching local media devices do these days there is really * very little point to attempting to restrict the I/O size to contiguous * blocks on-disk, especially if our caller thinks we need all the specified * pages. Just construct and issue a READ. */ int vnode_pager_generic_getpages(struct vnode *vp, vm_page_t *mpp, int bytecount, int reqpage, int seqaccess) { struct iovec aiov; struct uio auio; off_t foff; int error; int count; int i; int ioflags; int obytecount; /* * Do not do anything if the vnode is bad. */ if (vp->v_mount == NULL) return VM_PAGER_BAD; /* * Calculate the number of pages. Since we are paging in whole * pages, adjust bytecount to be an integral multiple of the page * size. It will be clipped to the file EOF later on. */ bytecount = round_page(bytecount); count = bytecount / PAGE_SIZE; /* * We could check m[reqpage]->valid here and shortcut the operation, * but doing so breaks read-ahead. Instead assume that the VM * system has already done at least the check, don't worry about * any races, and issue the VOP_READ to allow read-ahead to function. * * This keeps the pipeline full for I/O bound sequentially scanned * mmap()'s */ /* don't shortcut */ /* * Discard pages past the file EOF. If the requested page is past * the file EOF we just leave its valid bits set to 0, the caller * expects to maintain ownership of the requested page. If the * entire range is past file EOF discard everything and generate * a pagein error. */ foff = IDX_TO_OFF(mpp[0]->pindex); if (foff >= vp->v_filesize) { for (i = 0; i < count; i++) { if (i != reqpage) vnode_pager_freepage(mpp[i]); } return VM_PAGER_ERROR; } if (foff + bytecount > vp->v_filesize) { bytecount = vp->v_filesize - foff; i = round_page(bytecount) / PAGE_SIZE; while (count > i) { --count; if (count != reqpage) vnode_pager_freepage(mpp[count]); } } /* * The size of the transfer is bytecount. bytecount will be an * integral multiple of the page size unless it has been clipped * to the file EOF. The transfer cannot exceed the file EOF. * * When dealing with real devices we must round-up to the device * sector size. */ if (vp->v_type == VBLK || vp->v_type == VCHR) { int secmask = vp->v_rdev->si_bsize_phys - 1; KASSERT(secmask < PAGE_SIZE, ("vnode_pager_generic_getpages: sector size %d too large", secmask + 1)); bytecount = (bytecount + secmask) & ~secmask; } obytecount = bytecount; /* * Severe hack to avoid deadlocks with the buffer cache */ for (i = 0; i < count; ++i) { vm_page_t mt = mpp[i]; vm_page_io_start(mt); vm_page_wakeup(mt); } /* * Issue the I/O with some read-ahead if bytecount > PAGE_SIZE */ ioflags = IO_VMIO; if (seqaccess) ioflags |= IO_SEQMAX << IO_SEQSHIFT; aiov.iov_base = NULL; aiov.iov_len = bytecount; auio.uio_iov = &aiov; auio.uio_iovcnt = 1; auio.uio_offset = foff; auio.uio_segflg = UIO_NOCOPY; auio.uio_rw = UIO_READ; auio.uio_resid = bytecount; auio.uio_td = NULL; mycpu->gd_cnt.v_vnodein++; mycpu->gd_cnt.v_vnodepgsin += count; error = VOP_READ(vp, &auio, ioflags, proc0.p_ucred); /* * Severe hack to avoid deadlocks with the buffer cache */ for (i = 0; i < count; ++i) { vm_page_busy_wait(mpp[i], FALSE, "getpgs"); vm_page_io_finish(mpp[i]); } /* * Calculate the actual number of bytes read and clean up the * page list. */ bytecount -= auio.uio_resid; for (i = 0; i < count; ++i) { vm_page_t mt = mpp[i]; if (i != reqpage) { if (error == 0 && mt->valid) { if (mt->flags & PG_REFERENCED) vm_page_activate(mt); else vm_page_deactivate(mt); vm_page_wakeup(mt); } else { vnode_pager_freepage(mt); } } else if (mt->valid == 0) { if (error == 0) { kprintf("page failed but no I/O error page " "%p object %p pindex %d\n", mt, mt->object, (int) mt->pindex); kprintf("i=%d foff=%016lx bytecount=%d/%d " "uioresid=%zd\n", i, foff, obytecount, bytecount, auio.uio_resid); /* whoops, something happened */ error = EINVAL; } } else if (mt->valid != VM_PAGE_BITS_ALL) { /* * Zero-extend the requested page if necessary (if * the filesystem is using a small block size). */ vm_page_zero_invalid(mt, TRUE); } } if (error) { kprintf("vnode_pager_getpage: I/O read error\n"); } return (error ? VM_PAGER_ERROR : VM_PAGER_OK); } /* * EOPNOTSUPP is no longer legal. For local media VFS's that do not * implement their own VOP_PUTPAGES, their VOP_PUTPAGES should call to * vnode_pager_generic_putpages() to implement the previous behaviour. * * Caller has already cleared the pmap modified bits, if any. * * All other FS's should use the bypass to get to the local media * backing vp's VOP_PUTPAGES. */ static void vnode_pager_putpages(vm_object_t object, vm_page_t *m, int count, int flags, int *rtvals) { int rtval; struct vnode *vp; int bytes = count * PAGE_SIZE; /* * Force synchronous operation if we are extremely low on memory * to prevent a low-memory deadlock. VOP operations often need to * allocate more memory to initiate the I/O ( i.e. do a BMAP * operation ). The swapper handles the case by limiting the amount * of asynchronous I/O, but that sort of solution doesn't scale well * for the vnode pager without a lot of work. * * Also, the backing vnode's iodone routine may not wake the pageout * daemon up. This should be probably be addressed XXX. */ if ((vmstats.v_free_count + vmstats.v_cache_count) < vmstats.v_pageout_free_min) { flags |= OBJPC_SYNC; } /* * Call device-specific putpages function */ vp = object->handle; rtval = VOP_PUTPAGES(vp, m, bytes, flags, rtvals, 0); if (rtval == EOPNOTSUPP) { kprintf("vnode_pager: *** WARNING *** stale FS putpages\n"); rtval = vnode_pager_generic_putpages( vp, m, bytes, flags, rtvals); } } /* * This is now called from local media FS's to operate against their * own vnodes if they fail to implement VOP_PUTPAGES. * * This is typically called indirectly via the pageout daemon and * clustering has already typically occured, so in general we ask the * underlying filesystem to write the data out asynchronously rather * then delayed. */ int vnode_pager_generic_putpages(struct vnode *vp, vm_page_t *m, int bytecount, int flags, int *rtvals) { int i; int maxsize, ncount, count; vm_ooffset_t poffset; struct uio auio; struct iovec aiov; int error; int ioflags; count = bytecount / PAGE_SIZE; for (i = 0; i < count; i++) rtvals[i] = VM_PAGER_AGAIN; if ((int) m[0]->pindex < 0) { kprintf("vnode_pager_putpages: attempt to write meta-data!!! -- 0x%lx(%x)\n", (long)m[0]->pindex, m[0]->dirty); rtvals[0] = VM_PAGER_BAD; return VM_PAGER_BAD; } maxsize = count * PAGE_SIZE; ncount = count; poffset = IDX_TO_OFF(m[0]->pindex); /* * If the page-aligned write is larger then the actual file we * have to invalidate pages occuring beyond the file EOF. * * If the file EOF resides in the middle of a page we still clear * all of that page's dirty bits later on. If we didn't it would * endlessly re-write. * * We do not under any circumstances truncate the valid bits, as * this will screw up bogus page replacement. * * The caller has already read-protected the pages. The VFS must * use the buffer cache to wrap the pages. The pages might not * be immediately flushed by the buffer cache but once under its * control the pages themselves can wind up being marked clean * and their covering buffer cache buffer can be marked dirty. */ if (poffset + maxsize > vp->v_filesize) { if (poffset < vp->v_filesize) { maxsize = vp->v_filesize - poffset; ncount = btoc(maxsize); } else { maxsize = 0; ncount = 0; } if (ncount < count) { for (i = ncount; i < count; i++) { rtvals[i] = VM_PAGER_BAD; } } } /* * pageouts are already clustered, use IO_ASYNC to force a bawrite() * rather then a bdwrite() to prevent paging I/O from saturating * the buffer cache. Dummy-up the sequential heuristic to cause * large ranges to cluster. If neither IO_SYNC or IO_ASYNC is set, * the system decides how to cluster. */ ioflags = IO_VMIO; if (flags & (OBJPC_SYNC | OBJPC_INVAL)) ioflags |= IO_SYNC; else if ((flags & OBJPC_CLUSTER_OK) == 0) ioflags |= IO_ASYNC; ioflags |= (flags & OBJPC_INVAL) ? IO_INVAL: 0; ioflags |= IO_SEQMAX << IO_SEQSHIFT; aiov.iov_base = (caddr_t) 0; aiov.iov_len = maxsize; auio.uio_iov = &aiov; auio.uio_iovcnt = 1; auio.uio_offset = poffset; auio.uio_segflg = UIO_NOCOPY; auio.uio_rw = UIO_WRITE; auio.uio_resid = maxsize; auio.uio_td = NULL; error = VOP_WRITE(vp, &auio, ioflags, proc0.p_ucred); mycpu->gd_cnt.v_vnodeout++; mycpu->gd_cnt.v_vnodepgsout += ncount; if (error) { krateprintf(&vbadrate, "vnode_pager_putpages: I/O error %d\n", error); } if (auio.uio_resid) { krateprintf(&vresrate, "vnode_pager_putpages: residual I/O %zd at %lu\n", auio.uio_resid, (u_long)m[0]->pindex); } if (error == 0) { for (i = 0; i < ncount; i++) { rtvals[i] = VM_PAGER_OK; vm_page_undirty(m[i]); } } return rtvals[0]; } /* * Run the chain and if the bottom-most object is a vnode-type lock the * underlying vnode. A locked vnode or NULL is returned. * * Caller must hold the first object. */ struct vnode * vnode_pager_lock(vm_map_backing_t ba) { vm_map_backing_t lba; struct vnode *vp = NULL; vm_object_t lobject; int error; if (ba == NULL) return NULL; lba = ba; while (lba->backing_ba) lba = lba->backing_ba; if ((lobject = lba->object) == NULL) return NULL; if (lba != ba) vm_object_hold_shared(lobject); while (lobject->type == OBJT_VNODE && (lobject->flags & OBJ_DEAD) == 0) { /* * Extract the vp */ vp = lobject->handle; error = vget(vp, LK_SHARED | LK_RETRY | LK_CANRECURSE); if (error == 0) { if (lobject->handle == vp) break; vput(vp); } else { kprintf("vnode_pager_lock: vp %p error %d " "lockstatus %d, retrying\n", vp, error, lockstatus(&vp->v_lock, curthread)); tsleep(lobject->handle, 0, "vnpgrl", hz); } vp = NULL; } if (lba != ba) vm_object_drop(lobject); return (vp); }
