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uvm_vnode.c
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uvm_vnode.c
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/* $OpenBSD: uvm_vnode.c,v 1.104 2019/07/18 23:47:33 cheloha 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. 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 <sys/param.h>
#include <sys/systm.h>
#include <sys/proc.h>
#include <sys/malloc.h>
#include <sys/vnode.h>
#include <sys/lock.h>
#include <sys/disklabel.h>
#include <sys/fcntl.h>
#include <sys/conf.h>
#include <sys/rwlock.h>
#include <sys/dkio.h>
#include <sys/specdev.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);
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 */
extern int rebooting;
/*
* 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 *);
/*
* 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 */
};
/*
* 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_flags(&uvn_sync_lock, "uvnsync", RWL_IS_VNODE);
}
/*
* 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.
*
* => 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(struct vnode *vp, vm_prot_t accessprot)
{
struct uvm_vnode *uvn = vp->v_uvm;
struct vattr vattr;
int oldflags, result;
struct partinfo pi;
u_quad_t used_vnode_size = 0;
/* first get a lock on the uvn. */
while (uvn->u_flags & UVM_VNODE_BLOCKED) {
uvn->u_flags |= UVM_VNODE_WANTED;
tsleep_nsec(uvn, PVM, "uvn_attach", INFSLP);
}
/* 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) {
return(NULL);
}
/*
* now 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);
}
uvn->u_obj.uo_refs++; /* bump uvn ref! */
/* check for new writeable uvn */
if ((accessprot & 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;
}
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;
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;
}
if (result != 0) {
if (uvn->u_flags & UVM_VNODE_WANTED)
wakeup(uvn);
uvn->u_flags = 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. */
uvm_objinit(&uvn->u_obj, &uvm_vnodeops, 1);
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 & 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);
if (oldflags & UVM_VNODE_WANTED)
wakeup(uvn);
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 out here.
*
* => 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
#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++;
}
/*
* uvn_detach
*
* remove a reference to a VM object.
*
* => caller must call with 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;
uobj->uo_refs--; /* drop ref! */
if (uobj->uo_refs) { /* still more refs */
return;
}
/* get other pointers ... */
uvn = (struct uvm_vnode *) uobj;
vp = uvn->u_vnode;
/*
* 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);
vrele(vp); /* drop vnode reference */
return;
}
/* its a goner! */
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);
/*
* 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 and in the
* middle of an async io. If we still have pages we set the "relkill"
* state, so that in the case the vnode gets terminated we know
* to leave it alone. Otherwise we'll kill the vnode when it's empty.
*/
uvn->u_flags |= UVM_VNODE_RELKILL;
/* wait on any outstanding io */
while (uobj->uo_npages && uvn->u_flags & UVM_VNODE_RELKILL) {
uvn->u_flags |= UVM_VNODE_IOSYNC;
tsleep_nsec(&uvn->u_nio, PVM, "uvn_term", INFSLP);
}
if ((uvn->u_flags & UVM_VNODE_RELKILL) == 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);
}
KASSERT(RBT_EMPTY(uvm_objtree, &uobj->memt));
oldflags = uvn->u_flags;
uvn->u_flags = 0;
/* wake up any sleepers */
if (oldflags & UVM_VNODE_WANTED)
wakeup(uvn);
/* drop our reference to the vnode. */
vrele(vp);
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...]
* => 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;
/* check if it is valid */
if ((uvn->u_flags & UVM_VNODE_VALID) == 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].
* 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.
*
* 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;
RBT_FOREACH(pp, uvm_objtree, &uvn->u_obj.memt) {
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;
tsleep_nsec(&uvn->u_nio, PVM, "uvn_term", INFSLP);
}
/*
* 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);
}
/*
* 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:
* - drop "u_nio" (this req is done!)
* - if (object->iosync && u_naio == 0) { wakeup &uvn->u_naio }
* - get "page" structures (atop?).
* - handle "wanted" pages
* dont forget to look at "object" wanted flag in all cases.
*/
/*
* uvn_flush: flush pages out of a uvm object.
*
* => 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 not block
* => if PGO_ALLPAGE is set, then all pages in the object are valid targets
* for flushing.
* => 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.
*/
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, *ptmp;
struct vm_page *pps[MAXBSIZE >> PAGE_SHIFT], **ppsp;
int npages, result, lcv;
boolean_t retval, need_iosync, needs_clean;
voff_t curoff;
/* 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);
} else {
start = trunc_page(start);
stop = MIN(round_page(stop), round_page(uvn->u_size));
}
/*
* 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) {
KASSERT(uobj->pgops->pgo_mk_pcluster != 0);
for (curoff = start ; curoff < stop; curoff += PAGE_SIZE) {
if ((pp = uvm_pagelookup(uobj, curoff)) != NULL)
atomic_clearbits_int(&pp->pg_flags,
PG_CLEANCHK);
}
}
ppsp = NULL; /* XXX: shut up gcc */
uvm_lock_pageq();
/* locked: both page queues */
for (curoff = start; curoff < stop; curoff += PAGE_SIZE) {
if ((pp = uvm_pagelookup(uobj, curoff)) == NULL)
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, 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, deactivate/free pages then cont. */
if (!needs_clean) {
if (flags & PGO_DEACTIVATE) {
if (pp->wire_count == 0) {
pmap_page_protect(pp, PROT_NONE);
uvm_pagedeactivate(pp);
}
} else if (flags & PGO_FREE) {
if (pp->pg_flags & PG_BUSY) {
atomic_setbits_int(&pp->pg_flags,
PG_WANTED);
uvm_unlock_pageq();
tsleep_nsec(pp, PVM, "uvn_flsh",
INFSLP);
uvm_lock_pageq();
curoff -= PAGE_SIZE;
continue;
} else {
pmap_page_protect(pp, PROT_NONE);
/* removed page from object */
uvm_pagefree(pp);
}
}
continue;
}
/*
* pp points to a page in the 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: page queues.
*/
atomic_setbits_int(&pp->pg_flags, PG_BUSY);
UVM_PAGE_OWN(pp, "uvn_flush");
pmap_page_protect(pp, PROT_READ);
/* if we're async, free the page in aiodoned */
if ((flags & (PGO_FREE|PGO_SYNCIO)) == PGO_FREE)
atomic_setbits_int(&pp->pg_flags, PG_RELEASED);
ReTry:
ppsp = pps;
npages = sizeof(pps) / sizeof(struct vm_page *);
result = uvm_pager_put(uobj, pp, &ppsp, &npages,
flags | PGO_DOACTCLUST, start, stop);
/*
* 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. Therefore,
* we only touch it when it won't be freed, RELEASED took care
* of the rest.
*/
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
* 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;
if (flags & PGO_FREE)
atomic_clearbits_int(&pp->pg_flags,
PG_RELEASED);
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
* we can move on to the next page. aiodoned deals with
* the freeing case for us.
*/
if (result == VM_PAGER_PEND && (flags & PGO_DEACTIVATE) == 0)
continue;
/*
* need to look at each page of the I/O operation, and do what
* we gotta do.
*/
for (lcv = 0 ; lcv < npages; lcv++) {
ptmp = ppsp[lcv];
/*
* verify the page didn't get moved
*/
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
* (in which case the page is no longer busy).
*/
if (result != VM_PAGER_PEND) {
if (ptmp->pg_flags & PG_WANTED)
wakeup(ptmp);
atomic_clearbits_int(&ptmp->pg_flags,
PG_WANTED|PG_BUSY);
UVM_PAGE_OWN(ptmp, NULL);
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 (ptmp->wire_count == 0) {
pmap_page_protect(ptmp, PROT_NONE);
uvm_pagedeactivate(ptmp);
}
} else if (flags & PGO_FREE &&
result != VM_PAGER_PEND) {
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, 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) {
while (uvn->u_nio != 0) {
uvn->u_flags |= UVM_VNODE_IOSYNC;
tsleep_nsec(&uvn->u_nio, PVM, "uvn_flush", INFSLP);
}
if (uvn->u_flags & UVM_VNODE_IOSYNCWANTED)
wakeup(&uvn->u_flags);
uvn->u_flags &= ~(UVM_VNODE_IOSYNC|UVM_VNODE_IOSYNCWANTED);
}
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.
*/
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)
* => 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;
retval = uvn_io((struct uvm_vnode*)uobj, pps, npages, flags, UIO_WRITE);
return(retval);
}
/*
* uvn_get: get pages (synchronously) from backing store
*
* => prefer map unlocked (not required)
* => 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;
/* 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) != 0) {
if (lcv == centeridx || (flags & PGO_ALLPAGES)
!= 0)
done = FALSE; /* need to do a wait or I/O! */
continue;
}
/*
* useful page: busy 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++;
}
/*
* 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
return(VM_PAGER_UNLOCK);
}
/*
* step 2: get non-resident or busy pages.
* 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) {