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NetBSD/sys/uvm/uvm_vnode.c

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/* $NetBSD: uvm_vnode.c,v 1.23 1999/04/11 04:04:11 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
*/
#include "fs_nfs.h"
#include "opt_uvmhist.h"
/*
* uvm_vnode.c: the vnode pager.
*/
#include <sys/param.h>
#include <sys/systm.h>
#include <sys/proc.h>
#include <sys/malloc.h>
#include <sys/vnode.h>
#include <sys/disklabel.h>
#include <sys/ioctl.h>
#include <sys/fcntl.h>
#include <sys/conf.h>
#include <miscfs/specfs/specdev.h>
#include <vm/vm.h>
#include <vm/vm_page.h>
#include <vm/vm_kern.h>
#include <uvm/uvm.h>
#include <uvm/uvm_vnode.h>
/*
* 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);
static struct uvn_list_struct uvn_wlist; /* writeable uvns */
static simple_lock_data_t uvn_wl_lock; /* locks uvn_wlist */
SIMPLEQ_HEAD(uvn_sq_struct, uvm_vnode);
static struct uvn_sq_struct uvn_sync_q; /* sync'ing uvns */
lock_data_t uvn_sync_lock; /* locks sync operation */
/*
* functions
*/
static int uvn_asyncget __P((struct uvm_object *, vaddr_t,
int));
struct uvm_object *uvn_attach __P((void *, vm_prot_t));
static void uvn_cluster __P((struct uvm_object *, vaddr_t,
vaddr_t *, vaddr_t *));
static void uvn_detach __P((struct uvm_object *));
static boolean_t uvn_flush __P((struct uvm_object *, vaddr_t,
vaddr_t, int));
static int uvn_get __P((struct uvm_object *, vaddr_t,
vm_page_t *, int *, int,
vm_prot_t, int, int));
static void uvn_init __P((void));
static int uvn_io __P((struct uvm_vnode *, vm_page_t *,
int, int, int));
static int uvn_put __P((struct uvm_object *, vm_page_t *,
int, boolean_t));
static void uvn_reference __P((struct uvm_object *));
static boolean_t uvn_releasepg __P((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_asyncget,
uvn_put,
uvn_cluster,
uvm_mk_pcluster, /* use generic version of this: see uvm_pager.c */
uvm_shareprot, /* !NULL: allow us in share maps */
NULL, /* AIO-DONE function (not until we have asyncio) */
uvn_releasepg,
};
/*
* the ops!
*/
/*
* uvn_init
*
* init pager private data structures.
*/
static void
uvn_init()
{
LIST_INIT(&uvn_wlist);
simple_lock_init(&uvn_wl_lock);
/* note: uvn_sync_q init'd in uvm_vnp_sync() */
lockinit(&uvn_sync_lock, PVM, "uvnsync", 0, 0);
}
/*
* 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(arg, accessprot)
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=0x%x)", 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) {
simple_lock(&uvn_wl_lock);
LIST_INSERT_HEAD(&uvn_wlist, uvn, u_wlist);
simple_unlock(&uvn_wl_lock);
/* 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=%d", 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)pi.part->p_size;
}
} 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 = %qu\n", (long long)used_vnode_size);
#endif
if (used_vnode_size > (vaddr_t) -PAGE_SIZE) {
#ifdef DEBUG
printf("uvn_attach: vn %p size truncated %qx->%x\n", vp,
(long long)used_vnode_size, -PAGE_SIZE);
#endif
used_vnode_size = (vaddr_t) -PAGE_SIZE;
}
/*
* 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) {
simple_lock(&uvn_wl_lock);
LIST_INSERT_HEAD(&uvn_wlist, uvn, u_wlist);
simple_unlock(&uvn_wl_lock);
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 0x%x", &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
*/
static void
uvn_reference(uobj)
struct uvm_object *uobj;
{
#ifdef DIAGNOSTIC
struct uvm_vnode *uvn = (struct uvm_vnode *) uobj;
#endif
UVMHIST_FUNC("uvn_reference"); UVMHIST_CALLED(maphist);
simple_lock(&uobj->vmobjlock);
#ifdef DIAGNOSTIC
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=0x%x, ref = %d)",
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).
*/
static void
uvn_detach(uobj)
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=0x%x) ref=%d", 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 DIAGNOSTIC
/*
* 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) {
simple_lock(&uvn_wl_lock); /* protect uvn_wlist */
LIST_REMOVE(uvn, u_wlist);
simple_unlock(&uvn_wl_lock);
}
#ifdef DIAGNOSTIC
if (uobj->memq.tqh_first != NULL)
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(vp)
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=0x%x, ref=%d, flag=0x%x", 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 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 DIAGNOSTIC
struct vm_page *pp;
for (pp = uvn->u_obj.memq.tqh_first ; pp != NULL ;
pp = pp->listq.tqe_next) {
if ((pp->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) {
simple_lock(&uvn_wl_lock);
LIST_REMOVE(uvn, u_wlist);
simple_unlock(&uvn_wl_lock);
}
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(pg, nextpgp)
struct vm_page *pg;
struct vm_page **nextpgp; /* OUT */
{
struct uvm_vnode *uvn = (struct uvm_vnode *) pg->uobject;
#ifdef DIAGNOSTIC
if ((pg->flags & PG_RELEASED) == 0)
panic("uvn_releasepg: page not released!");
#endif
/*
* dispose of the page [caller handles PG_WANTED]
*/
pmap_page_protect(PMAP_PGARG(pg), VM_PROT_NONE);
uvm_lock_pageq();
if (nextpgp)
*nextpgp = pg->pageq.tqe_next; /* 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) {
simple_lock(&uvn_wl_lock);
LIST_REMOVE(uvn, u_wlist);
simple_unlock(&uvn_wl_lock);
}
#ifdef DIAGNOSTIC
if (uvn->u_obj.memq.tqh_first)
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 KERN_SUCCESS (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 */
static boolean_t
uvn_flush(uobj, start, stop, flags)
struct uvm_object *uobj;
vaddr_t start, 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;
vaddr_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) {
start = 0;
stop = round_page(uvn->u_size);
by_list = TRUE; /* always go by the list */
} else {
start = trunc_page(start);
stop = round_page(stop);
if (stop > round_page(uvn->u_size))
printf("uvn_flush: strange, got an out of range "
"flush (fixed)\n");
by_list = (uobj->uo_npages <=
((stop - start) >> PAGE_SHIFT) * UVN_HASH_PENALTY);
}
UVMHIST_LOG(maphist,
" flush start=0x%x, stop=0x%x, by_list=%d, flags=0x%x",
start, 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) {
for (pp = uobj->memq.tqh_first ; pp != NULL ;
pp = pp->listq.tqe_next) {
if (pp->offset < start || pp->offset >= stop)
continue;
pp->flags &= ~PG_CLEANCHK;
}
} else { /* by hash */
for (curoff = start ; curoff < stop;
curoff += PAGE_SIZE) {
pp = uvm_pagelookup(uobj, curoff);
if (pp)
pp->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 = uobj->memq.tqh_first;
} 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 (pp->offset < start || pp->offset >= stop) {
ppnext = pp->listq.tqe_next;
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->flags & PG_BUSY) != 0) {
needs_clean = FALSE;
if ((pp->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->flags & PG_CLEAN) != 0 &&
(flags & PGO_FREE) != 0 &&
(pp->pqflags & PQ_ACTIVE) != 0)
pmap_page_protect(PMAP_PGARG(pp), VM_PROT_NONE);
if ((pp->flags & PG_CLEAN) != 0 &&
pmap_is_modified(PMAP_PGARG(pp)))
pp->flags &= ~(PG_CLEAN);
pp->flags |= PG_CLEANCHK; /* update "hint" */
needs_clean = ((pp->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 = pp->listq.tqe_next;
else {
if (curoff < stop)
ppnext = uvm_pagelookup(uobj, curoff);
}
/* now dispose of pp */
if (flags & PGO_DEACTIVATE) {
if ((pp->pqflags & PQ_INACTIVE) == 0 &&
pp->wire_count == 0) {
pmap_page_protect(PMAP_PGARG(pp),
VM_PROT_NONE);
uvm_pagedeactivate(pp);
}
} else if (flags & PGO_FREE) {
if (pp->flags & PG_BUSY) {
/* release busy pages */
pp->flags |= PG_RELEASED;
} else {
pmap_page_protect(PMAP_PGARG(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.
*/
pp->flags |= PG_BUSY; /* we 'own' page now */
UVM_PAGE_OWN(pp, "uvn_flush");
pmap_page_protect(PMAP_PGARG(pp), VM_PROT_READ);
pp_version = pp->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->version == pp_version)
ppnext = pp->listq.tqe_next;
else
/* reset */
ppnext = uobj->memq.tqh_first;
} 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->version == pp_version)
ppnext = pp->listq.tqe_next;
else
/* reset */
ppnext = uobj->memq.tqh_first;
} 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->flags & PG_WANTED)
/* still holding object lock */
thread_wakeup(ptmp);
ptmp->flags &= ~(PG_WANTED|PG_BUSY);
UVM_PAGE_OWN(ptmp, NULL);
if (ptmp->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 {
ptmp->flags |= (PG_CLEAN|PG_CLEANCHK);
if ((flags & PGO_FREE) == 0)
pmap_clear_modify(
PMAP_PGARG(ptmp));
}
}
/*
* dispose of page
*/
if (flags & PGO_DEACTIVATE) {
if ((pp->pqflags & PQ_INACTIVE) == 0 &&
pp->wire_count == 0) {
pmap_page_protect(PMAP_PGARG(ptmp),
VM_PROT_NONE);
uvm_pagedeactivate(ptmp);
}
} else if (flags & PGO_FREE) {
if (result == VM_PAGER_PEND) {
if ((ptmp->flags & PG_BUSY) != 0)
/* signal for i/o done */
ptmp->flags |= PG_RELEASED;
} else {
if (result != VM_PAGER_OK) {
printf("uvn_flush: obj=%p, "
"offset=0x%lx. error "
"during pageout.\n",
pp->uobject, pp->offset);
printf("uvn_flush: WARNING: "
"changes to page may be "
"lost!\n");
retval = FALSE;
}
pmap_page_protect(PMAP_PGARG(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," <<DOING IOSYNC>>",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%x)",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.
*/
static void
uvn_cluster(uobj, offset, loffset, hoffset)
struct uvm_object *uobj;
vaddr_t offset;
vaddr_t *loffset, *hoffset; /* OUT */
{
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]
*/
static int
uvn_put(uobj, pps, npages, flags)
struct uvm_object *uobj;
struct vm_page **pps;
int npages, 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!!
*/
static int
uvn_get(uobj, offset, pps, npagesp, centeridx, access_type, advice, flags)
struct uvm_object *uobj;
vaddr_t offset;
struct vm_page **pps; /* IN/OUT */
int *npagesp; /* IN (OUT if PGO_LOCKED) */
int centeridx, advice, flags;
vm_prot_t access_type;
{
vaddr_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=%d", 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->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
*/
ptmp->flags |= PG_BUSY; /* loan up to caller */
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->flags & (PG_BUSY|PG_RELEASED)) != 0) {
ptmp->flags |= PG_WANTED;
UVM_UNLOCK_AND_WAIT(ptmp,
&uobj->vmobjlock, 0, "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).
*/
ptmp->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->flags & PG_WANTED)
/* object lock still held */
thread_wakeup(ptmp);
ptmp->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
*/
ptmp->flags &= ~PG_FAKE; /* data is valid ... */
pmap_clear_modify(PMAP_PGARG(ptmp)); /* ... and clean */
pps[lcv] = ptmp;
} /* lcv loop */
/*
* finally, unlock object and return.
*/
simple_unlock(&uobj->vmobjlock);
return (VM_PAGER_OK);
}
/*
* uvn_asyncget: start async I/O to bring pages into ram
*
* => caller must lock object(???XXX: see if this is best)
* => could be called from uvn_get or a madvise() fault-ahead.
* => if it fails, it doesn't matter.
*/
static int
uvn_asyncget(uobj, offset, npages)
struct uvm_object *uobj;
vaddr_t offset;
int npages;
{
/*
* XXXCDC: we can't do async I/O yet
*/
printf("uvn_asyncget called\n");
return (KERN_SUCCESS);
}
/*
* 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]
*/
static int
uvn_io(uvn, pps, npages, flags, rw)
struct uvm_vnode *uvn;
vm_page_t *pps;
int npages, flags, rw;
{
struct vnode *vn;
struct uio uio;
struct iovec iov;
vaddr_t kva, file_offset;
int waitf, result, got, wanted;
UVMHIST_FUNC("uvn_io"); UVMHIST_CALLED(maphist);
UVMHIST_LOG(maphist, "rw=%d", 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);
#ifdef DIAGNOSTIC
printf("uvn_io: note: size check fired\n");
#endif
return(VM_PAGER_BAD);
}
/*
* first try and map the pages in (without waiting)
*/
kva = uvm_pagermapin(pps, npages, NULL, M_NOWAIT);
if (kva == NULL && 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 == NULL) {
kva = uvm_pagermapin(pps, npages, NULL, M_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 = NULL;
/*
* 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_RETRY | LK_RECURSEFAIL);
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);
}
/* 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 %d)", 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(vp)
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 DEBUG
/*
* carry over sanity check from old vnode pager: the vnode should
* be VOP_LOCK'd, and we confirm it here.
*/
if (!VOP_ISLOCKED(vp)) {
boolean_t is_ok_anyway = FALSE;
#ifdef NFS
extern int (**nfsv2_vnodeop_p) __P((void *));
extern int (**spec_nfsv2nodeop_p) __P((void *));
extern int (**fifo_nfsv2nodeop_p) __P((void *));
/* vnode is NOT VOP_LOCKed: some vnode types _never_ lock */
if (vp->v_op == nfsv2_vnodeop_p ||
vp->v_op == spec_nfsv2nodeop_p) {
is_ok_anyway = TRUE;
}
if (vp->v_op == fifo_nfsv2nodeop_p) {
is_ok_anyway = TRUE;
}
#endif /* NFS */
if (!is_ok_anyway)
panic("uvm_vnp_uncache: vnode not locked!");
}
#endif /* DEBUG */
/*
* 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);
uvn_detach(&uvn->u_obj);
vn_lock(vp, LK_EXCLUSIVE | LK_RETRY);
/*
* 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(vp, newsize)
struct vnode *vp;
u_quad_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) {
/*
* make sure that the newsize fits within a vaddr_t
* XXX: need to revise addressing data types
*/
if (newsize > (vaddr_t) -PAGE_SIZE) {
#ifdef DEBUG
printf("uvm_vnp_setsize: vn %p size truncated "
"%qx->%lx\n", vp, (long long)newsize,
(vaddr_t)-PAGE_SIZE);
#endif
newsize = (vaddr_t)-PAGE_SIZE;
}
/*
* 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, (vaddr_t) newsize,
uvn->u_size, PGO_FREE);
}
uvn->u_size = (vaddr_t)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(mp)
struct mount *mp;
{
struct uvm_vnode *uvn;
struct vnode *vp;
boolean_t got_lock;
/*
* step 1: ensure we are only ones using the uvn_sync_q by locking
* our lock...
*/
lockmgr(&uvn_sync_lock, LK_EXCLUSIVE, (void *)0);
/*
* step 2: build up a simpleq of uvns of interest based on the
* write list. we gain a reference to uvns of interest. must
* be careful about locking uvn's since we will be holding uvn_wl_lock
* in the body of the loop.
*/
SIMPLEQ_INIT(&uvn_sync_q);
simple_lock(&uvn_wl_lock);
for (uvn = uvn_wlist.lh_first ; uvn != NULL ;
uvn = uvn->u_wlist.le_next) {
vp = (struct vnode *) uvn;
if (mp && vp->v_mount != mp)
continue;
/* attempt to gain reference */
while ((got_lock = simple_lock_try(&uvn->u_obj.vmobjlock)) ==
FALSE &&
(uvn->u_flags & UVM_VNODE_BLOCKED) == 0)
/* spin */ ;
/*
* we will exit the loop if either if the following are true:
* - we got the lock [always true if NCPU == 1]
* - we failed to get the lock but noticed the vnode was
* "blocked" -- in this case the vnode must be a dying
* vnode, and since dying vnodes are in the process of
* being flushed out, we can safely skip this one
*
* we want to skip over the vnode if we did not get the lock,
* or if the vnode is already dying (due to the above logic).
*
* note that uvn must already be valid because we found it on
* the wlist (this also means it can't be ALOCK'd).
*/
if (!got_lock || (uvn->u_flags & UVM_VNODE_BLOCKED) != 0) {
if (got_lock)
simple_unlock(&uvn->u_obj.vmobjlock);
continue; /* skip it */
}
/*
* 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++;
simple_unlock(&uvn->u_obj.vmobjlock);
/*
* got it!
*/
SIMPLEQ_INSERT_HEAD(&uvn_sync_q, uvn, u_syncq);
}
simple_unlock(&uvn_wl_lock);
/*
* step 3: we now have a list of uvn's that may need cleaning.
* we are holding the uvn_sync_lock, but have dropped the uvn_wl_lock
* (so we can now safely lock uvn's again).
*/
for (uvn = uvn_sync_q.sqh_first ; uvn ; uvn = uvn->u_syncq.sqe_next) {
simple_lock(&uvn->u_obj.vmobjlock);
#ifdef DIAGNOSTIC
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;
}
simple_unlock(&uvn->u_obj.vmobjlock);
/* now drop our reference to the uvn */
uvn_detach(&uvn->u_obj);
}
/*
* done! release sync lock
*/
lockmgr(&uvn_sync_lock, LK_RELEASE, (void *)0);
}
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