/* $OpenBSD: uvm_vnode.c,v 1.53 2009/03/20 15:19:04 oga Exp $ */ /* $NetBSD: uvm_vnode.c,v 1.36 2000/11/24 20:34:01 chs Exp $ */ /* * Copyright (c) 1997 Charles D. Cranor and Washington University. * Copyright (c) 1991, 1993 * The Regents of the University of California. * Copyright (c) 1990 University of Utah. * * 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 Charles D. Cranor, * Washington University, 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. * * @(#)vnode_pager.c 8.8 (Berkeley) 2/13/94 * from: Id: uvm_vnode.c,v 1.1.2.26 1998/02/02 20:38:07 chuck Exp */ /* * uvm_vnode.c: the vnode pager. */ #include #include #include #include #include #include #include #include #include #include #include #include #include /* * private global data structure * * we keep a list of writeable active vnode-backed VM objects for sync op. * we keep a simpleq of vnodes that are currently being sync'd. */ LIST_HEAD(uvn_list_struct, uvm_vnode); struct uvn_list_struct uvn_wlist; /* writeable uvns */ SIMPLEQ_HEAD(uvn_sq_struct, uvm_vnode); struct uvn_sq_struct uvn_sync_q; /* sync'ing uvns */ struct rwlock uvn_sync_lock; /* locks sync operation */ /* * functions */ void uvn_cluster(struct uvm_object *, voff_t, voff_t *, voff_t *); void uvn_detach(struct uvm_object *); boolean_t uvn_flush(struct uvm_object *, voff_t, voff_t, int); int uvn_get(struct uvm_object *, voff_t, vm_page_t *, int *, int, vm_prot_t, int, int); void uvn_init(void); int uvn_io(struct uvm_vnode *, vm_page_t *, int, int, int); int uvn_put(struct uvm_object *, vm_page_t *, int, boolean_t); void uvn_reference(struct uvm_object *); boolean_t uvn_releasepg(struct vm_page *, struct vm_page **); /* * master pager structure */ struct uvm_pagerops uvm_vnodeops = { uvn_init, uvn_reference, uvn_detach, NULL, /* no specialized fault routine required */ uvn_flush, uvn_get, uvn_put, uvn_cluster, uvm_mk_pcluster, /* use generic version of this: see uvm_pager.c */ uvn_releasepg, }; /* * the ops! */ /* * uvn_init * * init pager private data structures. */ void uvn_init(void) { LIST_INIT(&uvn_wlist); /* note: uvn_sync_q init'd in uvm_vnp_sync() */ rw_init(&uvn_sync_lock, "uvnsync"); } /* * uvn_attach * * attach a vnode structure to a VM object. if the vnode is already * attached, then just bump the reference count by one and return the * VM object. if not already attached, attach and return the new VM obj. * the "accessprot" tells the max access the attaching thread wants to * our pages. * * => caller must _not_ already be holding the lock on the uvm_object. * => in fact, nothing should be locked so that we can sleep here. * => note that uvm_object is first thing in vnode structure, so their * pointers are equiv. */ struct uvm_object * uvn_attach(void *arg, vm_prot_t accessprot) { struct vnode *vp = arg; struct uvm_vnode *uvn = &vp->v_uvm; struct vattr vattr; int oldflags, result; struct partinfo pi; u_quad_t used_vnode_size; UVMHIST_FUNC("uvn_attach"); UVMHIST_CALLED(maphist); UVMHIST_LOG(maphist, "(vn=%p)", arg,0,0,0); used_vnode_size = (u_quad_t)0; /* XXX gcc -Wuninitialized */ /* * first get a lock on the uvn. */ simple_lock(&uvn->u_obj.vmobjlock); while (uvn->u_flags & UVM_VNODE_BLOCKED) { uvn->u_flags |= UVM_VNODE_WANTED; UVMHIST_LOG(maphist, " SLEEPING on blocked vn",0,0,0,0); UVM_UNLOCK_AND_WAIT(uvn, &uvn->u_obj.vmobjlock, FALSE, "uvn_attach", 0); simple_lock(&uvn->u_obj.vmobjlock); UVMHIST_LOG(maphist," WOKE UP",0,0,0,0); } /* * if we're mapping a BLK device, make sure it is a disk. */ if (vp->v_type == VBLK && bdevsw[major(vp->v_rdev)].d_type != D_DISK) { simple_unlock(&uvn->u_obj.vmobjlock); /* drop lock */ UVMHIST_LOG(maphist,"<- done (VBLK not D_DISK!)", 0,0,0,0); return(NULL); } /* * now we have lock and uvn must not be in a blocked state. * first check to see if it is already active, in which case * we can bump the reference count, check to see if we need to * add it to the writeable list, and then return. */ if (uvn->u_flags & UVM_VNODE_VALID) { /* already active? */ /* regain VREF if we were persisting */ if (uvn->u_obj.uo_refs == 0) { VREF(vp); UVMHIST_LOG(maphist," VREF (reclaim persisting vnode)", 0,0,0,0); } uvn->u_obj.uo_refs++; /* bump uvn ref! */ /* check for new writeable uvn */ if ((accessprot & VM_PROT_WRITE) != 0 && (uvn->u_flags & UVM_VNODE_WRITEABLE) == 0) { LIST_INSERT_HEAD(&uvn_wlist, uvn, u_wlist); /* we are now on wlist! */ uvn->u_flags |= UVM_VNODE_WRITEABLE; } /* unlock and return */ simple_unlock(&uvn->u_obj.vmobjlock); UVMHIST_LOG(maphist,"<- done, refcnt=%ld", uvn->u_obj.uo_refs, 0, 0, 0); return (&uvn->u_obj); } /* * need to call VOP_GETATTR() to get the attributes, but that could * block (due to I/O), so we want to unlock the object before calling. * however, we want to keep anyone else from playing with the object * while it is unlocked. to do this we set UVM_VNODE_ALOCK which * prevents anyone from attaching to the vnode until we are done with * it. */ uvn->u_flags = UVM_VNODE_ALOCK; simple_unlock(&uvn->u_obj.vmobjlock); /* drop lock in case we sleep */ /* XXX: curproc? */ if (vp->v_type == VBLK) { /* * We could implement this as a specfs getattr call, but: * * (1) VOP_GETATTR() would get the file system * vnode operation, not the specfs operation. * * (2) All we want is the size, anyhow. */ result = (*bdevsw[major(vp->v_rdev)].d_ioctl)(vp->v_rdev, DIOCGPART, (caddr_t)&pi, FREAD, curproc); if (result == 0) { /* XXX should remember blocksize */ used_vnode_size = (u_quad_t)pi.disklab->d_secsize * (u_quad_t)DL_GETPSIZE(pi.part); } } else { result = VOP_GETATTR(vp, &vattr, curproc->p_ucred, curproc); if (result == 0) used_vnode_size = vattr.va_size; } /* relock object */ simple_lock(&uvn->u_obj.vmobjlock); if (result != 0) { if (uvn->u_flags & UVM_VNODE_WANTED) wakeup(uvn); uvn->u_flags = 0; simple_unlock(&uvn->u_obj.vmobjlock); /* drop lock */ UVMHIST_LOG(maphist,"<- done (VOP_GETATTR FAILED!)", 0,0,0,0); return(NULL); } /* * make sure that the newsize fits within a vaddr_t * XXX: need to revise addressing data types */ #ifdef DEBUG if (vp->v_type == VBLK) printf("used_vnode_size = %llu\n", (long long)used_vnode_size); #endif /* * now set up the uvn. */ uvn->u_obj.pgops = &uvm_vnodeops; TAILQ_INIT(&uvn->u_obj.memq); uvn->u_obj.uo_npages = 0; uvn->u_obj.uo_refs = 1; /* just us... */ oldflags = uvn->u_flags; uvn->u_flags = UVM_VNODE_VALID|UVM_VNODE_CANPERSIST; uvn->u_nio = 0; uvn->u_size = used_vnode_size; /* if write access, we need to add it to the wlist */ if (accessprot & VM_PROT_WRITE) { LIST_INSERT_HEAD(&uvn_wlist, uvn, u_wlist); uvn->u_flags |= UVM_VNODE_WRITEABLE; /* we are on wlist! */ } /* * add a reference to the vnode. this reference will stay as long * as there is a valid mapping of the vnode. dropped when the * reference count goes to zero [and we either free or persist]. */ VREF(vp); simple_unlock(&uvn->u_obj.vmobjlock); if (oldflags & UVM_VNODE_WANTED) wakeup(uvn); UVMHIST_LOG(maphist,"<- done/VREF, ret %p", &uvn->u_obj,0,0,0); return(&uvn->u_obj); } /* * uvn_reference * * duplicate a reference to a VM object. Note that the reference * count must already be at least one (the passed in reference) so * there is no chance of the uvn being killed or locked out here. * * => caller must call with object unlocked. * => caller must be using the same accessprot as was used at attach time */ void uvn_reference(struct uvm_object *uobj) { #ifdef DEBUG struct uvm_vnode *uvn = (struct uvm_vnode *) uobj; #endif UVMHIST_FUNC("uvn_reference"); UVMHIST_CALLED(maphist); simple_lock(&uobj->vmobjlock); #ifdef DEBUG if ((uvn->u_flags & UVM_VNODE_VALID) == 0) { printf("uvn_reference: ref=%d, flags=0x%x\n", uvn->u_flags, uobj->uo_refs); panic("uvn_reference: invalid state"); } #endif uobj->uo_refs++; UVMHIST_LOG(maphist, "<- done (uobj=%p, ref = %ld)", uobj, uobj->uo_refs,0,0); simple_unlock(&uobj->vmobjlock); } /* * uvn_detach * * remove a reference to a VM object. * * => caller must call with object unlocked and map locked. * => this starts the detach process, but doesn't have to finish it * (async i/o could still be pending). */ void uvn_detach(struct uvm_object *uobj) { struct uvm_vnode *uvn; struct vnode *vp; int oldflags; UVMHIST_FUNC("uvn_detach"); UVMHIST_CALLED(maphist); simple_lock(&uobj->vmobjlock); UVMHIST_LOG(maphist," (uobj=%p) ref=%ld", uobj,uobj->uo_refs,0,0); uobj->uo_refs--; /* drop ref! */ if (uobj->uo_refs) { /* still more refs */ simple_unlock(&uobj->vmobjlock); UVMHIST_LOG(maphist, "<- done (rc>0)", 0,0,0,0); return; } /* * get other pointers ... */ uvn = (struct uvm_vnode *) uobj; vp = (struct vnode *) uobj; /* * clear VTEXT flag now that there are no mappings left (VTEXT is used * to keep an active text file from being overwritten). */ vp->v_flag &= ~VTEXT; /* * we just dropped the last reference to the uvn. see if we can * let it "stick around". */ if (uvn->u_flags & UVM_VNODE_CANPERSIST) { /* won't block */ uvn_flush(uobj, 0, 0, PGO_DEACTIVATE|PGO_ALLPAGES); simple_unlock(&uobj->vmobjlock); vrele(vp); /* drop vnode reference */ UVMHIST_LOG(maphist,"<- done/vrele! (persist)", 0,0,0,0); return; } /* * its a goner! */ UVMHIST_LOG(maphist," its a goner (flushing)!", 0,0,0,0); uvn->u_flags |= UVM_VNODE_DYING; /* * even though we may unlock in flush, no one can gain a reference * to us until we clear the "dying" flag [because it blocks * attaches]. we will not do that until after we've disposed of all * the pages with uvn_flush(). note that before the flush the only * pages that could be marked PG_BUSY are ones that are in async * pageout by the daemon. (there can't be any pending "get"'s * because there are no references to the object). */ (void) uvn_flush(uobj, 0, 0, PGO_CLEANIT|PGO_FREE|PGO_ALLPAGES); UVMHIST_LOG(maphist," its a goner (done flush)!", 0,0,0,0); /* * given the structure of this pager, the above flush request will * create the following state: all the pages that were in the object * have either been free'd or they are marked PG_BUSY|PG_RELEASED. * the PG_BUSY bit was set either by us or the daemon for async I/O. * in either case, if we have pages left we can't kill the object * yet because i/o is pending. in this case we set the "relkill" * flag which will cause pgo_releasepg to kill the object once all * the I/O's are done [pgo_releasepg will be called from the aiodone * routine or from the page daemon]. */ if (uobj->uo_npages) { /* I/O pending. iodone will free */ #ifdef DEBUG /* * XXXCDC: very unlikely to happen until we have async i/o * so print a little info message in case it does. */ printf("uvn_detach: vn %p has pages left after flush - " "relkill mode\n", uobj); #endif uvn->u_flags |= UVM_VNODE_RELKILL; simple_unlock(&uobj->vmobjlock); UVMHIST_LOG(maphist,"<- done! (releasepg will kill obj)", 0, 0, 0, 0); return; } /* * kill object now. note that we can't be on the sync q because * all references are gone. */ if (uvn->u_flags & UVM_VNODE_WRITEABLE) { LIST_REMOVE(uvn, u_wlist); } #ifdef DIAGNOSTIC if (!TAILQ_EMPTY(&uobj->memq)) panic("uvn_deref: vnode VM object still has pages afer " "syncio/free flush"); #endif oldflags = uvn->u_flags; uvn->u_flags = 0; simple_unlock(&uobj->vmobjlock); /* wake up any sleepers */ if (oldflags & UVM_VNODE_WANTED) wakeup(uvn); /* * drop our reference to the vnode. */ vrele(vp); UVMHIST_LOG(maphist,"<- done (vrele) final", 0,0,0,0); return; } /* * uvm_vnp_terminate: external hook to clear out a vnode's VM * * called in two cases: * [1] when a persisting vnode vm object (i.e. one with a zero reference * count) needs to be freed so that a vnode can be reused. this * happens under "getnewvnode" in vfs_subr.c. if the vnode from * the free list is still attached (i.e. not VBAD) then vgone is * called. as part of the vgone trace this should get called to * free the vm object. this is the common case. * [2] when a filesystem is being unmounted by force (MNT_FORCE, * "umount -f") the vgone() function is called on active vnodes * on the mounted file systems to kill their data (the vnodes become * "dead" ones [see src/sys/miscfs/deadfs/...]). that results in a * call here (even if the uvn is still in use -- i.e. has a non-zero * reference count). this case happens at "umount -f" and during a * "reboot/halt" operation. * * => the caller must XLOCK and VOP_LOCK the vnode before calling us * [protects us from getting a vnode that is already in the DYING * state...] * => unlike uvn_detach, this function must not return until all the * uvn's pages are disposed of. * => in case [2] the uvn is still alive after this call, but all I/O * ops will fail (due to the backing vnode now being "dead"). this * will prob. kill any process using the uvn due to pgo_get failing. */ void uvm_vnp_terminate(struct vnode *vp) { struct uvm_vnode *uvn = &vp->v_uvm; int oldflags; UVMHIST_FUNC("uvm_vnp_terminate"); UVMHIST_CALLED(maphist); /* * lock object and check if it is valid */ simple_lock(&uvn->u_obj.vmobjlock); UVMHIST_LOG(maphist, " vp=%p, ref=%ld, flag=0x%lx", vp, uvn->u_obj.uo_refs, uvn->u_flags, 0); if ((uvn->u_flags & UVM_VNODE_VALID) == 0) { simple_unlock(&uvn->u_obj.vmobjlock); UVMHIST_LOG(maphist, "<- done (not active)", 0, 0, 0, 0); return; } /* * must be a valid uvn that is not already dying (because XLOCK * protects us from that). the uvn can't in the ALOCK state * because it is valid, and uvn's that are in the ALOCK state haven't * been marked valid yet. */ #ifdef DEBUG /* * debug check: are we yanking the vnode out from under our uvn? */ if (uvn->u_obj.uo_refs) { printf("uvm_vnp_terminate(%p): terminating active vnode " "(refs=%d)\n", uvn, uvn->u_obj.uo_refs); } #endif /* * it is possible that the uvn was detached and is in the relkill * state [i.e. waiting for async i/o to finish so that releasepg can * kill object]. we take over the vnode now and cancel the relkill. * we want to know when the i/o is done so we can recycle right * away. note that a uvn can only be in the RELKILL state if it * has a zero reference count. */ if (uvn->u_flags & UVM_VNODE_RELKILL) uvn->u_flags &= ~UVM_VNODE_RELKILL; /* cancel RELKILL */ /* * block the uvn by setting the dying flag, and then flush the * pages. (note that flush may unlock object while doing I/O, but * it will re-lock it before it returns control here). * * also, note that we tell I/O that we are already VOP_LOCK'd so * that uvn_io doesn't attempt to VOP_LOCK again. * * XXXCDC: setting VNISLOCKED on an active uvn which is being terminated * due to a forceful unmount might not be a good idea. maybe we * need a way to pass in this info to uvn_flush through a * pager-defined PGO_ constant [currently there are none]. */ uvn->u_flags |= UVM_VNODE_DYING|UVM_VNODE_VNISLOCKED; (void) uvn_flush(&uvn->u_obj, 0, 0, PGO_CLEANIT|PGO_FREE|PGO_ALLPAGES); /* * as we just did a flush we expect all the pages to be gone or in * the process of going. sleep to wait for the rest to go [via iosync]. */ while (uvn->u_obj.uo_npages) { #ifdef DEBUG struct vm_page *pp; TAILQ_FOREACH(pp, &uvn->u_obj.memq, listq) { if ((pp->pg_flags & PG_BUSY) == 0) panic("uvm_vnp_terminate: detected unbusy pg"); } if (uvn->u_nio == 0) panic("uvm_vnp_terminate: no I/O to wait for?"); printf("uvm_vnp_terminate: waiting for I/O to fin.\n"); /* * XXXCDC: this is unlikely to happen without async i/o so we * put a printf in just to keep an eye on it. */ #endif uvn->u_flags |= UVM_VNODE_IOSYNC; UVM_UNLOCK_AND_WAIT(&uvn->u_nio, &uvn->u_obj.vmobjlock, FALSE, "uvn_term",0); simple_lock(&uvn->u_obj.vmobjlock); } /* * done. now we free the uvn if its reference count is zero * (true if we are zapping a persisting uvn). however, if we are * terminating a uvn with active mappings we let it live ... future * calls down to the vnode layer will fail. */ oldflags = uvn->u_flags; if (uvn->u_obj.uo_refs) { /* * uvn must live on it is dead-vnode state until all references * are gone. restore flags. clear CANPERSIST state. */ uvn->u_flags &= ~(UVM_VNODE_DYING|UVM_VNODE_VNISLOCKED| UVM_VNODE_WANTED|UVM_VNODE_CANPERSIST); } else { /* * free the uvn now. note that the VREF reference is already * gone [it is dropped when we enter the persist state]. */ if (uvn->u_flags & UVM_VNODE_IOSYNCWANTED) panic("uvm_vnp_terminate: io sync wanted bit set"); if (uvn->u_flags & UVM_VNODE_WRITEABLE) { LIST_REMOVE(uvn, u_wlist); } uvn->u_flags = 0; /* uvn is history, clear all bits */ } if (oldflags & UVM_VNODE_WANTED) wakeup(uvn); /* object lock still held */ simple_unlock(&uvn->u_obj.vmobjlock); UVMHIST_LOG(maphist, "<- done", 0, 0, 0, 0); } /* * uvn_releasepg: handled a released page in a uvn * * => "pg" is a PG_BUSY [caller owns it], PG_RELEASED page that we need * to dispose of. * => caller must handled PG_WANTED case * => called with page's object locked, pageq's unlocked * => returns TRUE if page's object is still alive, FALSE if we * killed the page's object. if we return TRUE, then we * return with the object locked. * => if (nextpgp != NULL) => we return pageq.tqe_next here, and return * with the page queues locked [for pagedaemon] * => if (nextpgp == NULL) => we return with page queues unlocked [normal case] * => we kill the uvn if it is not referenced and we are suppose to * kill it ("relkill"). */ boolean_t uvn_releasepg(struct vm_page *pg, struct vm_page **nextpgp /* OUT */) { struct uvm_vnode *uvn = (struct uvm_vnode *) pg->uobject; #ifdef DIAGNOSTIC if ((pg->pg_flags & PG_RELEASED) == 0) panic("uvn_releasepg: page not released!"); #endif /* * dispose of the page [caller handles PG_WANTED] */ pmap_page_protect(pg, VM_PROT_NONE); uvm_lock_pageq(); if (nextpgp) *nextpgp = TAILQ_NEXT(pg, pageq); /* next page for daemon */ uvm_pagefree(pg); if (!nextpgp) uvm_unlock_pageq(); /* * now see if we need to kill the object */ if (uvn->u_flags & UVM_VNODE_RELKILL) { if (uvn->u_obj.uo_refs) panic("uvn_releasepg: kill flag set on referenced " "object!"); if (uvn->u_obj.uo_npages == 0) { if (uvn->u_flags & UVM_VNODE_WRITEABLE) { LIST_REMOVE(uvn, u_wlist); } #ifdef DIAGNOSTIC if (!TAILQ_EMPTY(&uvn->u_obj.memq)) panic("uvn_releasepg: pages in object with npages == 0"); #endif if (uvn->u_flags & UVM_VNODE_WANTED) /* still holding object lock */ wakeup(uvn); uvn->u_flags = 0; /* DEAD! */ simple_unlock(&uvn->u_obj.vmobjlock); return (FALSE); } } return (TRUE); } /* * NOTE: currently we have to use VOP_READ/VOP_WRITE because they go * through the buffer cache and allow I/O in any size. These VOPs use * synchronous i/o. [vs. VOP_STRATEGY which can be async, but doesn't * go through the buffer cache or allow I/O sizes larger than a * block]. we will eventually want to change this. * * issues to consider: * uvm provides the uvm_aiodesc structure for async i/o management. * there are two tailq's in the uvm. structure... one for pending async * i/o and one for "done" async i/o. to do an async i/o one puts * an aiodesc on the "pending" list (protected by splbio()), starts the * i/o and returns VM_PAGER_PEND. when the i/o is done, we expect * some sort of "i/o done" function to be called (at splbio(), interrupt * time). this function should remove the aiodesc from the pending list * and place it on the "done" list and wakeup the daemon. the daemon * will run at normal spl() and will remove all items from the "done" * list and call the "aiodone" hook for each done request (see uvm_pager.c). * [in the old vm code, this was done by calling the "put" routine with * null arguments which made the code harder to read and understand because * you had one function ("put") doing two things.] * * so the current pager needs: * int uvn_aiodone(struct uvm_aiodesc *) * * => return 0 (aio finished, free it). otherwise requeue for later collection. * => called with pageq's locked by the daemon. * * general outline: * - "try" to lock object. if fail, just return (will try again later) * - drop "u_nio" (this req is done!) * - if (object->iosync && u_naio == 0) { wakeup &uvn->u_naio } * - get "page" structures (atop?). * - handle "wanted" pages * - handle "released" pages [using pgo_releasepg] * >>> pgo_releasepg may kill the object * dont forget to look at "object" wanted flag in all cases. */ /* * uvn_flush: flush pages out of a uvm object. * * => object should be locked by caller. we may _unlock_ the object * if (and only if) we need to clean a page (PGO_CLEANIT). * we return with the object locked. * => if PGO_CLEANIT is set, we may block (due to I/O). thus, a caller * might want to unlock higher level resources (e.g. vm_map) * before calling flush. * => if PGO_CLEANIT is not set, then we will neither unlock the object * or block. * => if PGO_ALLPAGE is set, then all pages in the object are valid targets * for flushing. * => NOTE: we rely on the fact that the object's memq is a TAILQ and * that new pages are inserted on the tail end of the list. thus, * we can make a complete pass through the object in one go by starting * at the head and working towards the tail (new pages are put in * front of us). * => NOTE: we are allowed to lock the page queues, so the caller * must not be holding the lock on them [e.g. pagedaemon had * better not call us with the queues locked] * => we return TRUE unless we encountered some sort of I/O error * * comment on "cleaning" object and PG_BUSY pages: * this routine is holding the lock on the object. the only time * that it can run into a PG_BUSY page that it does not own is if * some other process has started I/O on the page (e.g. either * a pagein, or a pageout). if the PG_BUSY page is being paged * in, then it can not be dirty (!PG_CLEAN) because no one has * had a chance to modify it yet. if the PG_BUSY page is being * paged out then it means that someone else has already started * cleaning the page for us (how nice!). in this case, if we * have syncio specified, then after we make our pass through the * object we need to wait for the other PG_BUSY pages to clear * off (i.e. we need to do an iosync). also note that once a * page is PG_BUSY it must stay in its object until it is un-busyed. * * note on page traversal: * we can traverse the pages in an object either by going down the * linked list in "uobj->memq", or we can go over the address range * by page doing hash table lookups for each address. depending * on how many pages are in the object it may be cheaper to do one * or the other. we set "by_list" to true if we are using memq. * if the cost of a hash lookup was equal to the cost of the list * traversal we could compare the number of pages in the start->stop * range to the total number of pages in the object. however, it * seems that a hash table lookup is more expensive than the linked * list traversal, so we multiply the number of pages in the * start->stop range by a penalty which we define below. */ #define UVN_HASH_PENALTY 4 /* XXX: a guess */ boolean_t uvn_flush(struct uvm_object *uobj, voff_t start, voff_t stop, int flags) { struct uvm_vnode *uvn = (struct uvm_vnode *) uobj; struct vm_page *pp, *ppnext, *ptmp; struct vm_page *pps[MAXBSIZE >> PAGE_SHIFT], **ppsp; int npages, result, lcv; boolean_t retval, need_iosync, by_list, needs_clean, all; voff_t curoff; u_short pp_version; UVMHIST_FUNC("uvn_flush"); UVMHIST_CALLED(maphist); curoff = 0; /* XXX: shut up gcc */ /* * get init vals and determine how we are going to traverse object */ need_iosync = FALSE; retval = TRUE; /* return value */ if (flags & PGO_ALLPAGES) { all = TRUE; by_list = TRUE; /* always go by the list */ } else { start = trunc_page(start); stop = round_page(stop); #ifdef DEBUG if (stop > round_page(uvn->u_size)) printf("uvn_flush: strange, got an out of range " "flush (fixed)\n"); #endif all = FALSE; by_list = (uobj->uo_npages <= ((stop - start) >> PAGE_SHIFT) * UVN_HASH_PENALTY); } UVMHIST_LOG(maphist, " flush start=0x%lx, stop=0x%lx, by_list=%ld, flags=0x%lx", (u_long)start, (u_long)stop, by_list, flags); /* * PG_CLEANCHK: this bit is used by the pgo_mk_pcluster function as * a _hint_ as to how up to date the PG_CLEAN bit is. if the hint * is wrong it will only prevent us from clustering... it won't break * anything. we clear all PG_CLEANCHK bits here, and pgo_mk_pcluster * will set them as it syncs PG_CLEAN. This is only an issue if we * are looking at non-inactive pages (because inactive page's PG_CLEAN * bit is always up to date since there are no mappings). * [borrowed PG_CLEANCHK idea from FreeBSD VM] */ if ((flags & PGO_CLEANIT) != 0 && uobj->pgops->pgo_mk_pcluster != NULL) { if (by_list) { TAILQ_FOREACH(pp, &uobj->memq, listq) { if (!all && (pp->offset < start || pp->offset >= stop)) continue; atomic_clearbits_int(&pp->pg_flags, PG_CLEANCHK); } } else { /* by hash */ for (curoff = start ; curoff < stop; curoff += PAGE_SIZE) { pp = uvm_pagelookup(uobj, curoff); if (pp) atomic_clearbits_int(&pp->pg_flags, PG_CLEANCHK); } } } /* * now do it. note: we must update ppnext in body of loop or we * will get stuck. we need to use ppnext because we may free "pp" * before doing the next loop. */ if (by_list) { pp = TAILQ_FIRST(&uobj->memq); } else { curoff = start; pp = uvm_pagelookup(uobj, curoff); } ppnext = NULL; /* XXX: shut up gcc */ ppsp = NULL; /* XXX: shut up gcc */ uvm_lock_pageq(); /* page queues locked */ /* locked: both page queues and uobj */ for ( ; (by_list && pp != NULL) || (!by_list && curoff < stop) ; pp = ppnext) { if (by_list) { /* * range check */ if (!all && (pp->offset < start || pp->offset >= stop)) { ppnext = TAILQ_NEXT(pp, listq); continue; } } else { /* * null check */ curoff += PAGE_SIZE; if (pp == NULL) { if (curoff < stop) ppnext = uvm_pagelookup(uobj, curoff); continue; } } /* * handle case where we do not need to clean page (either * because we are not clean or because page is not dirty or * is busy): * * NOTE: we are allowed to deactivate a non-wired active * PG_BUSY page, but once a PG_BUSY page is on the inactive * queue it must stay put until it is !PG_BUSY (so as not to * confuse pagedaemon). */ if ((flags & PGO_CLEANIT) == 0 || (pp->pg_flags & PG_BUSY) != 0) { needs_clean = FALSE; if ((pp->pg_flags & PG_BUSY) != 0 && (flags & (PGO_CLEANIT|PGO_SYNCIO)) == (PGO_CLEANIT|PGO_SYNCIO)) need_iosync = TRUE; } else { /* * freeing: nuke all mappings so we can sync * PG_CLEAN bit with no race */ if ((pp->pg_flags & PG_CLEAN) != 0 && (flags & PGO_FREE) != 0 && (pp->pg_flags & PQ_ACTIVE) != 0) pmap_page_protect(pp, VM_PROT_NONE); if ((pp->pg_flags & PG_CLEAN) != 0 && pmap_is_modified(pp)) atomic_clearbits_int(&pp->pg_flags, PG_CLEAN); atomic_setbits_int(&pp->pg_flags, PG_CLEANCHK); needs_clean = ((pp->pg_flags & PG_CLEAN) == 0); } /* * if we don't need a clean... load ppnext and dispose of pp */ if (!needs_clean) { /* load ppnext */ if (by_list) ppnext = TAILQ_NEXT(pp, listq); else { if (curoff < stop) ppnext = uvm_pagelookup(uobj, curoff); } /* now dispose of pp */ if (flags & PGO_DEACTIVATE) { if ((pp->pg_flags & PQ_INACTIVE) == 0 && pp->wire_count == 0) { pmap_page_protect(pp, VM_PROT_NONE); uvm_pagedeactivate(pp); } } else if (flags & PGO_FREE) { if (pp->pg_flags & PG_BUSY) { /* release busy pages */ atomic_setbits_int(&pp->pg_flags, PG_RELEASED); } else { pmap_page_protect(pp, VM_PROT_NONE); /* removed page from object */ uvm_pagefree(pp); } } /* ppnext is valid so we can continue... */ continue; } /* * pp points to a page in the locked object that we are * working on. if it is !PG_CLEAN,!PG_BUSY and we asked * for cleaning (PGO_CLEANIT). we clean it now. * * let uvm_pager_put attempted a clustered page out. * note: locked: uobj and page queues. */ atomic_setbits_int(&pp->pg_flags, PG_BUSY); UVM_PAGE_OWN(pp, "uvn_flush"); pmap_page_protect(pp, VM_PROT_READ); pp_version = pp->pg_version; ReTry: ppsp = pps; npages = sizeof(pps) / sizeof(struct vm_page *); /* locked: page queues, uobj */ result = uvm_pager_put(uobj, pp, &ppsp, &npages, flags | PGO_DOACTCLUST, start, stop); /* unlocked: page queues, uobj */ /* * at this point nothing is locked. if we did an async I/O * it is remotely possible for the async i/o to complete and * the page "pp" be freed or what not before we get a chance * to relock the object. in order to detect this, we have * saved the version number of the page in "pp_version". */ /* relock! */ simple_lock(&uobj->vmobjlock); uvm_lock_pageq(); /* * VM_PAGER_AGAIN: given the structure of this pager, this * can only happen when we are doing async I/O and can't * map the pages into kernel memory (pager_map) due to lack * of vm space. if this happens we drop back to sync I/O. */ if (result == VM_PAGER_AGAIN) { /* * it is unlikely, but page could have been released * while we had the object lock dropped. we ignore * this now and retry the I/O. we will detect and * handle the released page after the syncio I/O * completes. */ #ifdef DIAGNOSTIC if (flags & PGO_SYNCIO) panic("uvn_flush: PGO_SYNCIO return 'try again' error (impossible)"); #endif flags |= PGO_SYNCIO; goto ReTry; } /* * the cleaning operation is now done. finish up. note that * on error (!OK, !PEND) uvm_pager_put drops the cluster for us. * if success (OK, PEND) then uvm_pager_put returns the cluster * to us in ppsp/npages. */ /* * for pending async i/o if we are not deactivating/freeing * we can move on to the next page. */ if (result == VM_PAGER_PEND) { if ((flags & (PGO_DEACTIVATE|PGO_FREE)) == 0) { /* * no per-page ops: refresh ppnext and continue */ if (by_list) { if (pp->pg_version == pp_version) ppnext = TAILQ_NEXT(pp, listq); else /* reset */ ppnext = TAILQ_FIRST(&uobj->memq); } else { if (curoff < stop) ppnext = uvm_pagelookup(uobj, curoff); } continue; } /* need to do anything here? */ } /* * need to look at each page of the I/O operation. we defer * processing "pp" until the last trip through this "for" loop * so that we can load "ppnext" for the main loop after we * play with the cluster pages [thus the "npages + 1" in the * loop below]. */ for (lcv = 0 ; lcv < npages + 1 ; lcv++) { /* * handle ppnext for outside loop, and saving pp * until the end. */ if (lcv < npages) { if (ppsp[lcv] == pp) continue; /* skip pp until the end */ ptmp = ppsp[lcv]; } else { ptmp = pp; /* set up next page for outer loop */ if (by_list) { if (pp->pg_version == pp_version) ppnext = TAILQ_NEXT(pp, listq); else /* reset */ ppnext = TAILQ_FIRST(&uobj->memq); } else { if (curoff < stop) ppnext = uvm_pagelookup(uobj, curoff); } } /* * verify the page didn't get moved while obj was * unlocked */ if (result == VM_PAGER_PEND && ptmp->uobject != uobj) continue; /* * unbusy the page if I/O is done. note that for * pending I/O it is possible that the I/O op * finished before we relocked the object (in * which case the page is no longer busy). */ if (result != VM_PAGER_PEND) { if (ptmp->pg_flags & PG_WANTED) /* still holding object lock */ wakeup(ptmp); atomic_clearbits_int(&ptmp->pg_flags, PG_WANTED|PG_BUSY); UVM_PAGE_OWN(ptmp, NULL); if (ptmp->pg_flags & PG_RELEASED) { /* pgo_releasepg wants this */ uvm_unlock_pageq(); if (!uvn_releasepg(ptmp, NULL)) return (TRUE); uvm_lock_pageq(); /* relock */ continue; /* next page */ } else { atomic_setbits_int(&ptmp->pg_flags, PG_CLEAN|PG_CLEANCHK); if ((flags & PGO_FREE) == 0) pmap_clear_modify(ptmp); } } /* * dispose of page */ if (flags & PGO_DEACTIVATE) { if ((pp->pg_flags & PQ_INACTIVE) == 0 && pp->wire_count == 0) { pmap_page_protect(ptmp, VM_PROT_NONE); uvm_pagedeactivate(ptmp); } } else if (flags & PGO_FREE) { if (result == VM_PAGER_PEND) { if ((ptmp->pg_flags & PG_BUSY) != 0) /* signal for i/o done */ atomic_setbits_int( &ptmp->pg_flags, PG_RELEASED); } else { if (result != VM_PAGER_OK) { printf("uvn_flush: obj=%p, " "offset=0x%llx. error " "during pageout.\n", pp->uobject, (long long)pp->offset); printf("uvn_flush: WARNING: " "changes to page may be " "lost!\n"); retval = FALSE; } pmap_page_protect(ptmp, VM_PROT_NONE); uvm_pagefree(ptmp); } } } /* end of "lcv" for loop */ } /* end of "pp" for loop */ /* * done with pagequeues: unlock */ uvm_unlock_pageq(); /* * now wait for all I/O if required. */ if (need_iosync) { UVMHIST_LOG(maphist," <>",0,0,0,0); while (uvn->u_nio != 0) { uvn->u_flags |= UVM_VNODE_IOSYNC; UVM_UNLOCK_AND_WAIT(&uvn->u_nio, &uvn->u_obj.vmobjlock, FALSE, "uvn_flush",0); simple_lock(&uvn->u_obj.vmobjlock); } if (uvn->u_flags & UVM_VNODE_IOSYNCWANTED) wakeup(&uvn->u_flags); uvn->u_flags &= ~(UVM_VNODE_IOSYNC|UVM_VNODE_IOSYNCWANTED); } /* return, with object locked! */ UVMHIST_LOG(maphist,"<- done (retval=0x%lx)",retval,0,0,0); return(retval); } /* * uvn_cluster * * we are about to do I/O in an object at offset. this function is called * to establish a range of offsets around "offset" in which we can cluster * I/O. * * - currently doesn't matter if obj locked or not. */ void uvn_cluster(struct uvm_object *uobj, voff_t offset, voff_t *loffset, voff_t *hoffset) { struct uvm_vnode *uvn = (struct uvm_vnode *) uobj; *loffset = offset; if (*loffset >= uvn->u_size) panic("uvn_cluster: offset out of range"); /* * XXX: old pager claims we could use VOP_BMAP to get maxcontig value. */ *hoffset = *loffset + MAXBSIZE; if (*hoffset > round_page(uvn->u_size)) /* past end? */ *hoffset = round_page(uvn->u_size); return; } /* * uvn_put: flush page data to backing store. * * => prefer map unlocked (not required) * => object must be locked! we will _unlock_ it before starting I/O. * => flags: PGO_SYNCIO -- use sync. I/O * => note: caller must set PG_CLEAN and pmap_clear_modify (if needed) * => XXX: currently we use VOP_READ/VOP_WRITE which are only sync. * [thus we never do async i/o! see iodone comment] */ int uvn_put(struct uvm_object *uobj, struct vm_page **pps, int npages, int flags) { int retval; /* note: object locked */ retval = uvn_io((struct uvm_vnode*)uobj, pps, npages, flags, UIO_WRITE); /* note: object unlocked */ return(retval); } /* * uvn_get: get pages (synchronously) from backing store * * => prefer map unlocked (not required) * => object must be locked! we will _unlock_ it before starting any I/O. * => flags: PGO_ALLPAGES: get all of the pages * PGO_LOCKED: fault data structures are locked * => NOTE: offset is the offset of pps[0], _NOT_ pps[centeridx] * => NOTE: caller must check for released pages!! */ int uvn_get(struct uvm_object *uobj, voff_t offset, struct vm_page **pps, int *npagesp, int centeridx, vm_prot_t access_type, int advice, int flags) { voff_t current_offset; struct vm_page *ptmp; int lcv, result, gotpages; boolean_t done; UVMHIST_FUNC("uvn_get"); UVMHIST_CALLED(maphist); UVMHIST_LOG(maphist, "flags=%ld", flags,0,0,0); /* * step 1: handled the case where fault data structures are locked. */ if (flags & PGO_LOCKED) { /* * gotpages is the current number of pages we've gotten (which * we pass back up to caller via *npagesp. */ gotpages = 0; /* * step 1a: get pages that are already resident. only do this * if the data structures are locked (i.e. the first time * through). */ done = TRUE; /* be optimistic */ for (lcv = 0, current_offset = offset ; lcv < *npagesp ; lcv++, current_offset += PAGE_SIZE) { /* do we care about this page? if not, skip it */ if (pps[lcv] == PGO_DONTCARE) continue; /* lookup page */ ptmp = uvm_pagelookup(uobj, current_offset); /* to be useful must get a non-busy, non-released pg */ if (ptmp == NULL || (ptmp->pg_flags & (PG_BUSY|PG_RELEASED)) != 0) { if (lcv == centeridx || (flags & PGO_ALLPAGES) != 0) done = FALSE; /* need to do a wait or I/O! */ continue; } /* * useful page: busy/lock it and plug it in our * result array */ atomic_setbits_int(&ptmp->pg_flags, PG_BUSY); UVM_PAGE_OWN(ptmp, "uvn_get1"); pps[lcv] = ptmp; gotpages++; } /* "for" lcv loop */ /* * XXX: given the "advice", should we consider async read-ahead? * XXX: fault current does deactive of pages behind us. is * this good (other callers might now). */ /* * XXX: read-ahead currently handled by buffer cache (bread) * level. * XXX: no async i/o available. * XXX: so we don't do anything now. */ /* * step 1c: now we've either done everything needed or we to * unlock and do some waiting or I/O. */ *npagesp = gotpages; /* let caller know */ if (done) return(VM_PAGER_OK); /* bingo! */ else /* EEK! Need to unlock and I/O */ return(VM_PAGER_UNLOCK); } /* * step 2: get non-resident or busy pages. * object is locked. data structures are unlocked. * * XXX: because we can't do async I/O at this level we get things * page at a time (otherwise we'd chunk). the VOP_READ() will do * async-read-ahead for us at a lower level. */ for (lcv = 0, current_offset = offset; lcv < *npagesp ; lcv++, current_offset += PAGE_SIZE) { /* skip over pages we've already gotten or don't want */ /* skip over pages we don't _have_ to get */ if (pps[lcv] != NULL || (lcv != centeridx && (flags & PGO_ALLPAGES) == 0)) continue; /* * we have yet to locate the current page (pps[lcv]). we first * look for a page that is already at the current offset. if * we fine a page, we check to see if it is busy or released. * if that is the case, then we sleep on the page until it is * no longer busy or released and repeat the lookup. if the * page we found is neither busy nor released, then we busy it * (so we own it) and plug it into pps[lcv]. this breaks the * following while loop and indicates we are ready to move on * to the next page in the "lcv" loop above. * * if we exit the while loop with pps[lcv] still set to NULL, * then it means that we allocated a new busy/fake/clean page * ptmp in the object and we need to do I/O to fill in the data. */ while (pps[lcv] == NULL) { /* top of "pps" while loop */ /* look for a current page */ ptmp = uvm_pagelookup(uobj, current_offset); /* nope? allocate one now (if we can) */ if (ptmp == NULL) { ptmp = uvm_pagealloc(uobj, current_offset, NULL, 0); /* out of RAM? */ if (ptmp == NULL) { simple_unlock(&uobj->vmobjlock); uvm_wait("uvn_getpage"); simple_lock(&uobj->vmobjlock); /* goto top of pps while loop */ continue; } /* * got new page ready for I/O. break pps * while loop. pps[lcv] is still NULL. */ break; } /* page is there, see if we need to wait on it */ if ((ptmp->pg_flags & (PG_BUSY|PG_RELEASED)) != 0) { atomic_setbits_int(&ptmp->pg_flags, PG_WANTED); UVM_UNLOCK_AND_WAIT(ptmp, &uobj->vmobjlock, FALSE, "uvn_get",0); simple_lock(&uobj->vmobjlock); continue; /* goto top of pps while loop */ } /* * if we get here then the page has become resident * and unbusy between steps 1 and 2. we busy it * now (so we own it) and set pps[lcv] (so that we * exit the while loop). */ atomic_setbits_int(&ptmp->pg_flags, PG_BUSY); UVM_PAGE_OWN(ptmp, "uvn_get2"); pps[lcv] = ptmp; } /* * if we own the a valid page at the correct offset, pps[lcv] * will point to it. nothing more to do except go to the * next page. */ if (pps[lcv]) continue; /* next lcv */ /* * we have a "fake/busy/clean" page that we just allocated. do * I/O to fill it with valid data. note that object must be * locked going into uvn_io, but will be unlocked afterwards. */ result = uvn_io((struct uvm_vnode *) uobj, &ptmp, 1, PGO_SYNCIO, UIO_READ); /* * I/O done. object is unlocked (by uvn_io). because we used * syncio the result can not be PEND or AGAIN. we must relock * and check for errors. */ /* lock object. check for errors. */ simple_lock(&uobj->vmobjlock); if (result != VM_PAGER_OK) { if (ptmp->pg_flags & PG_WANTED) /* object lock still held */ wakeup(ptmp); atomic_clearbits_int(&ptmp->pg_flags, PG_WANTED|PG_BUSY); UVM_PAGE_OWN(ptmp, NULL); uvm_lock_pageq(); uvm_pagefree(ptmp); uvm_unlock_pageq(); simple_unlock(&uobj->vmobjlock); return(result); } /* * we got the page! clear the fake flag (indicates valid * data now in page) and plug into our result array. note * that page is still busy. * * it is the callers job to: * => check if the page is released * => unbusy the page * => activate the page */ /* data is valid ... */ atomic_clearbits_int(&ptmp->pg_flags, PG_FAKE); pmap_clear_modify(ptmp); /* ... and clean */ pps[lcv] = ptmp; } /* lcv loop */ /* * finally, unlock object and return. */ simple_unlock(&uobj->vmobjlock); return (VM_PAGER_OK); } /* * uvn_io: do I/O to a vnode * * => prefer map unlocked (not required) * => object must be locked! we will _unlock_ it before starting I/O. * => flags: PGO_SYNCIO -- use sync. I/O * => XXX: currently we use VOP_READ/VOP_WRITE which are only sync. * [thus we never do async i/o! see iodone comment] */ int uvn_io(struct uvm_vnode *uvn, vm_page_t *pps, int npages, int flags, int rw) { struct vnode *vn; struct uio uio; struct iovec iov; vaddr_t kva; off_t file_offset; int waitf, result, mapinflags; size_t got, wanted; UVMHIST_FUNC("uvn_io"); UVMHIST_CALLED(maphist); UVMHIST_LOG(maphist, "rw=%ld", rw,0,0,0); /* * init values */ waitf = (flags & PGO_SYNCIO) ? M_WAITOK : M_NOWAIT; vn = (struct vnode *) uvn; file_offset = pps[0]->offset; /* * check for sync'ing I/O. */ while (uvn->u_flags & UVM_VNODE_IOSYNC) { if (waitf == M_NOWAIT) { simple_unlock(&uvn->u_obj.vmobjlock); UVMHIST_LOG(maphist,"<- try again (iosync)",0,0,0,0); return(VM_PAGER_AGAIN); } uvn->u_flags |= UVM_VNODE_IOSYNCWANTED; UVM_UNLOCK_AND_WAIT(&uvn->u_flags, &uvn->u_obj.vmobjlock, FALSE, "uvn_iosync",0); simple_lock(&uvn->u_obj.vmobjlock); } /* * check size */ if (file_offset >= uvn->u_size) { simple_unlock(&uvn->u_obj.vmobjlock); UVMHIST_LOG(maphist,"<- BAD (size check)",0,0,0,0); return(VM_PAGER_BAD); } /* * first try and map the pages in (without waiting) */ mapinflags = (rw == UIO_READ) ? UVMPAGER_MAPIN_READ : UVMPAGER_MAPIN_WRITE; kva = uvm_pagermapin(pps, npages, mapinflags); if (kva == 0 && waitf == M_NOWAIT) { simple_unlock(&uvn->u_obj.vmobjlock); UVMHIST_LOG(maphist,"<- mapin failed (try again)",0,0,0,0); return(VM_PAGER_AGAIN); } /* * ok, now bump u_nio up. at this point we are done with uvn * and can unlock it. if we still don't have a kva, try again * (this time with sleep ok). */ uvn->u_nio++; /* we have an I/O in progress! */ simple_unlock(&uvn->u_obj.vmobjlock); /* NOTE: object now unlocked */ if (kva == 0) kva = uvm_pagermapin(pps, npages, mapinflags | UVMPAGER_MAPIN_WAITOK); /* * ok, mapped in. our pages are PG_BUSY so they are not going to * get touched (so we can look at "offset" without having to lock * the object). set up for I/O. */ /* * fill out uio/iov */ iov.iov_base = (caddr_t) kva; wanted = npages << PAGE_SHIFT; if (file_offset + wanted > uvn->u_size) wanted = uvn->u_size - file_offset; /* XXX: needed? */ iov.iov_len = wanted; uio.uio_iov = &iov; uio.uio_iovcnt = 1; uio.uio_offset = file_offset; uio.uio_segflg = UIO_SYSSPACE; uio.uio_rw = rw; uio.uio_resid = wanted; uio.uio_procp = curproc; /* * do the I/O! (XXX: curproc?) */ UVMHIST_LOG(maphist, "calling VOP",0,0,0,0); /* * This process may already have this vnode locked, if we faulted in * copyin() or copyout() on a region backed by this vnode * while doing I/O to the vnode. If this is the case, don't * panic.. instead, return the error to the user. * * XXX this is a stopgap to prevent a panic. * Ideally, this kind of operation *should* work. */ result = 0; if ((uvn->u_flags & UVM_VNODE_VNISLOCKED) == 0) result = vn_lock(vn, LK_EXCLUSIVE | LK_RECURSEFAIL, curproc); if (result == 0) { /* NOTE: vnode now locked! */ if (rw == UIO_READ) result = VOP_READ(vn, &uio, 0, curproc->p_ucred); else result = VOP_WRITE(vn, &uio, 0, curproc->p_ucred); if ((uvn->u_flags & UVM_VNODE_VNISLOCKED) == 0) VOP_UNLOCK(vn, 0, curproc); } /* NOTE: vnode now unlocked (unless vnislocked) */ UVMHIST_LOG(maphist, "done calling VOP",0,0,0,0); /* * result == unix style errno (0 == OK!) * * zero out rest of buffer (if needed) */ if (result == 0) { got = wanted - uio.uio_resid; if (wanted && got == 0) { result = EIO; /* XXX: error? */ } else if (got < PAGE_SIZE * npages && rw == UIO_READ) { memset((void *) (kva + got), 0, (npages << PAGE_SHIFT) - got); } } /* * now remove pager mapping */ uvm_pagermapout(kva, npages); /* * now clean up the object (i.e. drop I/O count) */ simple_lock(&uvn->u_obj.vmobjlock); /* NOTE: object now locked! */ uvn->u_nio--; /* I/O DONE! */ if ((uvn->u_flags & UVM_VNODE_IOSYNC) != 0 && uvn->u_nio == 0) { wakeup(&uvn->u_nio); } simple_unlock(&uvn->u_obj.vmobjlock); /* NOTE: object now unlocked! */ /* * done! */ UVMHIST_LOG(maphist, "<- done (result %ld)", result,0,0,0); if (result == 0) return(VM_PAGER_OK); else return(VM_PAGER_ERROR); } /* * uvm_vnp_uncache: disable "persisting" in a vnode... when last reference * is gone we will kill the object (flushing dirty pages back to the vnode * if needed). * * => returns TRUE if there was no uvm_object attached or if there was * one and we killed it [i.e. if there is no active uvn] * => called with the vnode VOP_LOCK'd [we will unlock it for I/O, if * needed] * * => XXX: given that we now kill uvn's when a vnode is recycled (without * having to hold a reference on the vnode) and given a working * uvm_vnp_sync(), how does that effect the need for this function? * [XXXCDC: seems like it can die?] * * => XXX: this function should DIE once we merge the VM and buffer * cache. * * research shows that this is called in the following places: * ext2fs_truncate, ffs_truncate, detrunc[msdosfs]: called when vnode * changes sizes * ext2fs_write, WRITE [ufs_readwrite], msdosfs_write: called when we * are written to * ex2fs_chmod, ufs_chmod: called if VTEXT vnode and the sticky bit * is off * ffs_realloccg: when we can't extend the current block and have * to allocate a new one we call this [XXX: why?] * nfsrv_rename, rename_files: called when the target filename is there * and we want to remove it * nfsrv_remove, sys_unlink: called on file we are removing * nfsrv_access: if VTEXT and we want WRITE access and we don't uncache * then return "text busy" * nfs_open: seems to uncache any file opened with nfs * vn_writechk: if VTEXT vnode and can't uncache return "text busy" */ boolean_t uvm_vnp_uncache(struct vnode *vp) { struct uvm_vnode *uvn = &vp->v_uvm; /* * lock uvn part of the vnode and check to see if we need to do anything */ simple_lock(&uvn->u_obj.vmobjlock); if ((uvn->u_flags & UVM_VNODE_VALID) == 0 || (uvn->u_flags & UVM_VNODE_BLOCKED) != 0) { simple_unlock(&uvn->u_obj.vmobjlock); return(TRUE); } /* * we have a valid, non-blocked uvn. clear persist flag. * if uvn is currently active we can return now. */ uvn->u_flags &= ~UVM_VNODE_CANPERSIST; if (uvn->u_obj.uo_refs) { simple_unlock(&uvn->u_obj.vmobjlock); return(FALSE); } /* * uvn is currently persisting! we have to gain a reference to * it so that we can call uvn_detach to kill the uvn. */ VREF(vp); /* seems ok, even with VOP_LOCK */ uvn->u_obj.uo_refs++; /* value is now 1 */ simple_unlock(&uvn->u_obj.vmobjlock); #ifdef VFSDEBUG /* * carry over sanity check from old vnode pager: the vnode should * be VOP_LOCK'd, and we confirm it here. */ if ((vp->v_flag & VLOCKSWORK) && !VOP_ISLOCKED(vp)) panic("uvm_vnp_uncache: vnode not locked!"); #endif /* VFSDEBUG */ /* * now drop our reference to the vnode. if we have the sole * reference to the vnode then this will cause it to die [as we * just cleared the persist flag]. we have to unlock the vnode * while we are doing this as it may trigger I/O. * * XXX: it might be possible for uvn to get reclaimed while we are * unlocked causing us to return TRUE when we should not. we ignore * this as a false-positive return value doesn't hurt us. */ VOP_UNLOCK(vp, 0, curproc); uvn_detach(&uvn->u_obj); vn_lock(vp, LK_EXCLUSIVE | LK_RETRY, curproc); /* * and return... */ return(TRUE); } /* * uvm_vnp_setsize: grow or shrink a vnode uvn * * grow => just update size value * shrink => toss un-needed pages * * => we assume that the caller has a reference of some sort to the * vnode in question so that it will not be yanked out from under * us. * * called from: * => truncate fns (ext2fs_truncate, ffs_truncate, detrunc[msdos]) * => "write" fns (ext2fs_write, WRITE [ufs/ufs], msdosfs_write, nfs_write) * => ffs_balloc [XXX: why? doesn't WRITE handle?] * => NFS: nfs_loadattrcache, nfs_getattrcache, nfs_setattr * => union fs: union_newsize */ void uvm_vnp_setsize(struct vnode *vp, voff_t newsize) { struct uvm_vnode *uvn = &vp->v_uvm; /* * lock uvn and check for valid object, and if valid: do it! */ simple_lock(&uvn->u_obj.vmobjlock); if (uvn->u_flags & UVM_VNODE_VALID) { /* * now check if the size has changed: if we shrink we had better * toss some pages... */ if (uvn->u_size > newsize) { (void)uvn_flush(&uvn->u_obj, newsize, uvn->u_size, PGO_FREE); } uvn->u_size = newsize; } simple_unlock(&uvn->u_obj.vmobjlock); /* * done */ return; } /* * uvm_vnp_sync: flush all dirty VM pages back to their backing vnodes. * * => called from sys_sync with no VM structures locked * => only one process can do a sync at a time (because the uvn * structure only has one queue for sync'ing). we ensure this * by holding the uvn_sync_lock while the sync is in progress. * other processes attempting a sync will sleep on this lock * until we are done. */ void uvm_vnp_sync(struct mount *mp) { struct uvm_vnode *uvn; struct vnode *vp; /* * step 1: ensure we are only ones using the uvn_sync_q by locking * our lock... */ rw_enter_write(&uvn_sync_lock); /* * step 2: build up a simpleq of uvns of interest based on the * write list. we gain a reference to uvns of interest. */ SIMPLEQ_INIT(&uvn_sync_q); LIST_FOREACH(uvn, &uvn_wlist, u_wlist) { vp = (struct vnode *)uvn; if (mp && vp->v_mount != mp) continue; /* * If the vnode is "blocked" it means it must be dying, which * in turn means its in the process of being flushed out so * we can safely skip it. * * note that uvn must already be valid because we found it on * the wlist (this also means it can't be ALOCK'd). */ if ((uvn->u_flags & UVM_VNODE_BLOCKED) != 0) continue; /* * gain reference. watch out for persisting uvns (need to * regain vnode REF). */ if (uvn->u_obj.uo_refs == 0) VREF(vp); uvn->u_obj.uo_refs++; SIMPLEQ_INSERT_HEAD(&uvn_sync_q, uvn, u_syncq); } /* step 3: we now have a list of uvn's that may need cleaning. */ SIMPLEQ_FOREACH(uvn, &uvn_sync_q, u_syncq) { #ifdef DEBUG if (uvn->u_flags & UVM_VNODE_DYING) { printf("uvm_vnp_sync: dying vnode on sync list\n"); } #endif uvn_flush(&uvn->u_obj, 0, 0, PGO_CLEANIT|PGO_ALLPAGES|PGO_DOACTCLUST); /* * if we have the only reference and we just cleaned the uvn, * then we can pull it out of the UVM_VNODE_WRITEABLE state * thus allowing us to avoid thinking about flushing it again * on later sync ops. */ if (uvn->u_obj.uo_refs == 1 && (uvn->u_flags & UVM_VNODE_WRITEABLE)) { LIST_REMOVE(uvn, u_wlist); uvn->u_flags &= ~UVM_VNODE_WRITEABLE; } /* now drop our reference to the uvn */ uvn_detach(&uvn->u_obj); } rw_exit_write(&uvn_sync_lock); }