int
uvm_pager_put(struct uvm_object *uobj, struct vm_page *pg,
struct vm_page ***ppsp_ptr, int *npages, int flags,
voff_t start, voff_t stop)
{
int result;
daddr_t swblk;
struct vm_page **ppsp = *ppsp_ptr;
/*
* note that uobj is null if we are doing a swap-backed pageout.
* note that uobj is !null if we are doing normal object pageout.
* note that the page queues must be locked to cluster.
*/
if (uobj) { /* if !swap-backed */
/*
* attempt to build a cluster for pageout using its
* make-put-cluster function (if it has one).
*/
if (uobj->pgops->pgo_mk_pcluster) {
ppsp = uobj->pgops->pgo_mk_pcluster(uobj, ppsp,
npages, pg, flags, start, stop);
*ppsp_ptr = ppsp; /* update caller's pointer */
} else {
ppsp[0] = pg;
*npages = 1;
}
swblk = 0; /* XXX: keep gcc happy */
} else {
/*
* for swap-backed pageout, the caller (the pagedaemon) has
* already built the cluster for us. the starting swap
* block we are writing to has been passed in as "start."
* "pg" could be NULL if there is no page we are especially
* interested in (in which case the whole cluster gets dropped
* in the event of an error or a sync "done").
*/
swblk = start;
/* ppsp and npages should be ok */
}
/* now that we've clustered we can unlock the page queues */
uvm_unlock_pageq();
/*
* now attempt the I/O. if we have a failure and we are
* clustered, we will drop the cluster and try again.
*/
ReTry:
if (uobj) {
/* object is locked */
result = uobj->pgops->pgo_put(uobj, ppsp, *npages, flags);
/* object is now unlocked */
} else {
/* nothing locked */
/* XXX daddr_t -> int */
result = uvm_swap_put(swblk, ppsp, *npages, flags);
/* nothing locked */
}
/*
* we have attempted the I/O.
*
* if the I/O was a success then:
* if !PGO_PDFREECLUST, we return the cluster to the
* caller (who must un-busy all pages)
* else we un-busy cluster pages for the pagedaemon
*
* if I/O is pending (async i/o) then we return the pending code.
* [in this case the async i/o done function must clean up when
* i/o is done...]
*/
if (result == VM_PAGER_PEND || result == VM_PAGER_OK) {
if (result == VM_PAGER_OK && (flags & PGO_PDFREECLUST)) {
/*
* drop cluster and relock object (only if I/O is
* not pending)
*/
if (uobj)
/* required for dropcluster */
mtx_enter(&uobj->vmobjlock);
if (*npages > 1 || pg == NULL)
uvm_pager_dropcluster(uobj, pg, ppsp, npages,
PGO_PDFREECLUST);
/* if (uobj): object still locked, as per
* return-state item #3 */
}
return (result);
}
/*
* a pager error occured (even after dropping the cluster, if there
* was one). give up! the caller only has one page ("pg")
* to worry about.
*/
if (*npages > 1 || pg == NULL) {
if (uobj) {
mtx_enter(&uobj->vmobjlock);
}
uvm_pager_dropcluster(uobj, pg, ppsp, npages, PGO_REALLOCSWAP);
/*
* for failed swap-backed pageouts with a "pg",
* we need to reset pg's swslot to either:
* "swblk" (for transient errors, so we can retry),
* or 0 (for hard errors).
*/
if (uobj == NULL && pg != NULL) {
/* XXX daddr_t -> int */
int nswblk = (result == VM_PAGER_AGAIN) ? swblk : 0;
if (pg->pg_flags & PQ_ANON) {
mtx_enter(&pg->uanon->an_lock);
pg->uanon->an_swslot = nswblk;
mtx_leave(&pg->uanon->an_lock);
} else {
mtx_enter(&pg->uobject->vmobjlock);
uao_set_swslot(pg->uobject,
pg->offset >> PAGE_SHIFT,
nswblk);
mtx_leave(&pg->uobject->vmobjlock);
}
}
if (result == VM_PAGER_AGAIN) {
/*
* for transient failures, free all the swslots that
* we're not going to retry with.
*/
if (uobj == NULL) {
if (pg) {
/* XXX daddr_t -> int */
uvm_swap_free(swblk + 1, *npages - 1);
} else {
/* XXX daddr_t -> int */
uvm_swap_free(swblk, *npages);
}
}
if (pg) {
ppsp[0] = pg;
*npages = 1;
goto ReTry;
}
} else if (uobj == NULL) {
/*
* for hard errors on swap-backed pageouts,
* mark the swslots as bad. note that we do not
* free swslots that we mark bad.
*/
/* XXX daddr_t -> int */
uvm_swap_markbad(swblk, *npages);
}
if (uobj)
mtx_leave(&uobj->vmobjlock);
}
int
uvmfault_anonget(struct uvm_faultinfo *ufi, struct vm_amap *amap,
struct vm_anon *anon)
{
boolean_t we_own; /* we own anon's page? */
boolean_t locked; /* did we relock? */
struct vm_page *pg;
int result;
result = 0; /* XXX shut up gcc */
uvmexp.fltanget++;
/* bump rusage counters */
if (anon->an_page)
curproc->p_ru.ru_minflt++;
else
curproc->p_ru.ru_majflt++;
/*
* loop until we get it, or fail.
*/
while (1) {
we_own = FALSE; /* TRUE if we set PG_BUSY on a page */
pg = anon->an_page;
/*
* if there is a resident page and it is loaned, then anon
* may not own it. call out to uvm_anon_lockpage() to ensure
* the real owner of the page has been identified and locked.
*/
if (pg && pg->loan_count)
pg = uvm_anon_lockloanpg(anon);
/*
* page there? make sure it is not busy/released.
*/
if (pg) {
/*
* at this point, if the page has a uobject [meaning
* we have it on loan], then that uobject is locked
* by us! if the page is busy, we drop all the
* locks (including uobject) and try again.
*/
if ((pg->pg_flags & (PG_BUSY|PG_RELEASED)) == 0) {
return (VM_PAGER_OK);
}
atomic_setbits_int(&pg->pg_flags, PG_WANTED);
uvmexp.fltpgwait++;
/*
* the last unlock must be an atomic unlock+wait on
* the owner of page
*/
if (pg->uobject) { /* owner is uobject ? */
uvmfault_unlockall(ufi, amap, NULL, anon);
UVM_UNLOCK_AND_WAIT(pg,
&pg->uobject->vmobjlock,
FALSE, "anonget1",0);
} else {
/* anon owns page */
uvmfault_unlockall(ufi, amap, NULL, NULL);
UVM_UNLOCK_AND_WAIT(pg,&anon->an_lock,0,
"anonget2",0);
}
/* ready to relock and try again */
} else {
/*
* no page, we must try and bring it in.
*/
pg = uvm_pagealloc(NULL, 0, anon, 0);
if (pg == NULL) { /* out of RAM. */
uvmfault_unlockall(ufi, amap, NULL, anon);
uvmexp.fltnoram++;
uvm_wait("flt_noram1");
/* ready to relock and try again */
} else {
/* we set the PG_BUSY bit */
we_own = TRUE;
uvmfault_unlockall(ufi, amap, NULL, anon);
/*
* we are passing a PG_BUSY+PG_FAKE+PG_CLEAN
* page into the uvm_swap_get function with
* all data structures unlocked. note that
* it is ok to read an_swslot here because
* we hold PG_BUSY on the page.
*/
uvmexp.pageins++;
result = uvm_swap_get(pg, anon->an_swslot,
PGO_SYNCIO);
/*
* we clean up after the i/o below in the
* "we_own" case
*/
/* ready to relock and try again */
}
}
/*
* now relock and try again
*/
locked = uvmfault_relock(ufi);
if (locked || we_own)
simple_lock(&anon->an_lock);
/*
* if we own the page (i.e. we set PG_BUSY), then we need
* to clean up after the I/O. there are three cases to
* consider:
* [1] page released during I/O: free anon and ReFault.
* [2] I/O not OK. free the page and cause the fault
* to fail.
* [3] I/O OK! activate the page and sync with the
* non-we_own case (i.e. drop anon lock if not locked).
*/
if (we_own) {
if (pg->pg_flags & PG_WANTED) {
/* still holding object lock */
wakeup(pg);
}
/* un-busy! */
atomic_clearbits_int(&pg->pg_flags,
PG_WANTED|PG_BUSY|PG_FAKE);
UVM_PAGE_OWN(pg, NULL);
/*
* if we were RELEASED during I/O, then our anon is
* no longer part of an amap. we need to free the
* anon and try again.
*/
if (pg->pg_flags & PG_RELEASED) {
pmap_page_protect(pg, VM_PROT_NONE);
simple_unlock(&anon->an_lock);
uvm_anfree(anon); /* frees page for us */
if (locked)
uvmfault_unlockall(ufi, amap, NULL,
NULL);
uvmexp.fltpgrele++;
return (VM_PAGER_REFAULT); /* refault! */
}
if (result != VM_PAGER_OK) {
KASSERT(result != VM_PAGER_PEND);
/* remove page from anon */
anon->an_page = NULL;
/*
* remove the swap slot from the anon
* and mark the anon as having no real slot.
* don't free the swap slot, thus preventing
* it from being used again.
*/
uvm_swap_markbad(anon->an_swslot, 1);
anon->an_swslot = SWSLOT_BAD;
/*
* note: page was never !PG_BUSY, so it
* can't be mapped and thus no need to
* pmap_page_protect it...
*/
uvm_lock_pageq();
uvm_pagefree(pg);
uvm_unlock_pageq();
if (locked)
uvmfault_unlockall(ufi, amap, NULL,
anon);
else
simple_unlock(&anon->an_lock);
return (VM_PAGER_ERROR);
}
/*
* must be OK, clear modify (already PG_CLEAN)
* and activate
*/
pmap_clear_modify(pg);
uvm_lock_pageq();
uvm_pageactivate(pg);
uvm_unlock_pageq();
if (!locked)
simple_unlock(&anon->an_lock);
}
/*
* we were not able to relock. restart fault.
*/
if (!locked)
return (VM_PAGER_REFAULT);
/*
* verify no one has touched the amap and moved the anon on us.
*/
if (ufi != NULL &&
amap_lookup(&ufi->entry->aref,
ufi->orig_rvaddr - ufi->entry->start) != anon) {
uvmfault_unlockall(ufi, amap, NULL, anon);
return (VM_PAGER_REFAULT);
}
/*
* try it again!
*/
uvmexp.fltanretry++;
continue;
} /* while (1) */
/*NOTREACHED*/
}
