Aren/NetBSD
1
0
Fork 0
Code Issues Pull Requests Packages Projects Releases Wiki Activity
NetBSD/sys/uvm/uvm_aobj.c
mrg 1f6b921cf7 restore rcsids
1998-02-07 11:07:38 +00:00

1015 lines
24 KiB
C
Raw Blame History

/* $NetBSD: uvm_aobj.c,v 1.4 1998/02/07 11:08:08 mrg Exp $ */
/* copyright here */
/*
* from: Id: uvm_aobj.c,v 1.1.2.5 1998/02/06 05:14:38 chs Exp
*/
#include <sys/param.h>
#include <sys/systm.h>
#include <sys/proc.h>
#include <sys/malloc.h>
#include <vm/vm.h>
#include <vm/vm_page.h>
#include <vm/vm_kern.h>
#include <uvm/uvm.h>
/*
* uvm_aobj.c: anonymous-memory backed uvm_object
*/
/*
* an aobj manages anonymous-memory backed uvm_objects. in addition
* to keeping the list of resident pages, it also keeps a list of
* allocated swap blocks. depending on the size of the aobj this list
* of allocated swap blocks is either stored in an array (small objects)
* or in a hash table (large objects).
*/
/*
* local structures
*/
/*
* for hash tables, we break the address space of the aobj into blocks
* of UAO_SWHASH_CLUSTER_SIZE pages. we require the cluster size to
* be a power of two.
*/
#define UAO_SWHASH_CLUSTER_SHIFT 4
#define UAO_SWHASH_CLUSTER_SIZE (1 << UAO_SWHASH_CLUSTER_SHIFT)
/* get the "tag" for this page index */
#define UAO_SWHASH_ELT_TAG(PAGEIDX) \
((PAGEIDX) >> UAO_SWHASH_CLUSTER_SHIFT)
/* given an ELT and a page index, find the swap slot */
#define UAO_SWHASH_ELT_PAGESLOT(ELT, PAGEIDX) \
((ELT)->slots[(PAGEIDX) & (UAO_SWHASH_CLUSTER_SIZE - 1)])
/* given an ELT, return its pageidx base */
#define UAO_SWHASH_ELT_PAGEIDX_BASE(ELT) \
((ELT)->tag << UAO_SWHASH_CLUSTER_SHIFT)
/*
* the swhash hash function
*/
#define UAO_SWHASH_HASH(AOBJ, PAGEIDX) \
(&(AOBJ)->u_swhash[(((PAGEIDX) >> UAO_SWHASH_CLUSTER_SHIFT) \
& (AOBJ)->u_swhashmask)])
/*
* the swhash threshhold determines if we will use an array or a
* hash table to store the list of allocated swap blocks.
*/
#define UAO_SWHASH_THRESHOLD (UAO_SWHASH_CLUSTER_SIZE * 4)
#define UAO_USES_SWHASH(AOBJ) \
((AOBJ)->u_pages > UAO_SWHASH_THRESHOLD) /* use hash? */
/*
* the number of buckets in a swhash, with an upper bound
*/
#define UAO_SWHASH_MAXBUCKETS 256
#define UAO_SWHASH_BUCKETS(AOBJ) \
(min((AOBJ)->u_pages >> UAO_SWHASH_CLUSTER_SHIFT, \
UAO_SWHASH_MAXBUCKETS))
/*
* uao_swhash_elt: when a hash table is being used, this structure defines
* the format of an entry in the bucket list.
*/
struct uao_swhash_elt {
LIST_ENTRY(uao_swhash_elt) list; /* the hash list */
vm_offset_t tag; /* our 'tag' */
int count; /* our number of active slots */
int slots[UAO_SWHASH_CLUSTER_SIZE]; /* the slots */
};
/*
* uao_swhash: the swap hash table structure
*/
LIST_HEAD(uao_swhash, uao_swhash_elt);
/*
* uvm_aobj: the actual anon-backed uvm_object
*
* => the uvm_object is at the top of the structure, this allows
* (struct uvm_device *) == (struct uvm_object *)
* => only one of u_swslots and u_swhash is used in any given aobj
*/
struct uvm_aobj {
struct uvm_object u_obj; /* has: lock, pgops, memq, #pages, #refs */
vm_size_t u_pages; /* number of pages in entire object */
int u_flags; /* the flags (see uvm_aobj.h) */
int *u_swslots; /* array of offset->swapslot mappings */
struct uao_swhash *u_swhash; /* hashtable of offset->swapslot mappings */
/* (u_swhash is an array of bucket heads) */
u_long u_swhashmask; /* mask for hashtable */
LIST_ENTRY(uvm_aobj) u_list; /* global list of aobjs */
};
/*
* local functions
*/
static void uao_init __P((void));
static struct uao_swhash_elt *uao_find_swhash_elt __P((struct uvm_aobj *,
int, boolean_t));
static int uao_find_swslot __P((struct uvm_aobj *,
vm_offset_t));
static boolean_t uao_flush __P((struct uvm_object *,
vm_offset_t, vm_offset_t,
int));
static void uao_free __P((struct uvm_aobj *));
static int uao_get __P((struct uvm_object *, vm_offset_t,
vm_page_t *, int *, int,
vm_prot_t, int, int));
static boolean_t uao_releasepg __P((struct vm_page *,
struct vm_page **));
/*
* aobj_pager
*
* note that some functions (e.g. put) are handled elsewhere
*/
struct uvm_pagerops aobj_pager = {
uao_init, /* init */
NULL, /* attach */
uao_reference, /* reference */
uao_detach, /* detach */
NULL, /* fault */
uao_flush, /* flush */
uao_get, /* get */
NULL, /* asyncget */
NULL, /* put (done by pagedaemon) */
NULL, /* cluster */
NULL, /* mk_pcluster */
uvm_shareprot, /* shareprot */
NULL, /* aiodone */
uao_releasepg /* releasepg */
};
/*
* uao_list: global list of active aobjs, locked by uao_list_lock
*/
static LIST_HEAD(aobjlist, uvm_aobj) uao_list;
#if NCPU > 1
static simple_lock_data_t uao_list_lock;
#endif
/*
* functions
*/
/*
* hash table/array related functions
*/
/*
* uao_find_swhash_elt: find (or create) a hash table entry for a page
* offset.
*
* => the object should be locked by the caller
*/
static struct uao_swhash_elt *uao_find_swhash_elt(aobj, pageidx, create)
struct uvm_aobj *aobj;
int pageidx;
boolean_t create;
{
struct uao_swhash *swhash;
struct uao_swhash_elt *elt;
int page_tag;
swhash = UAO_SWHASH_HASH(aobj, pageidx); /* first hash to get bucket */
page_tag = UAO_SWHASH_ELT_TAG(pageidx); /* tag to search for */
/*
* now search the bucket for the requested tag
*/
for (elt = swhash->lh_first; elt != NULL; elt = elt->list.le_next) {
if (elt->tag == page_tag)
return(elt);
}
/* fail now if we are not allowed to create a new entry in the bucket */
if (!create)
return NULL;
/*
* malloc a new entry for the bucket and init/insert it in
*/
MALLOC(elt, struct uao_swhash_elt *, sizeof(*elt), M_UVMAOBJ, M_WAITOK);
LIST_INSERT_HEAD(swhash, elt, list);
elt->tag = page_tag;
elt->count = 0;
bzero(elt->slots, sizeof(elt->slots));
return(elt);
}
/*
* uao_find_swslot: find the swap slot number for an aobj/pageidx
*
* => object must be locked by caller
*/
__inline static int uao_find_swslot(aobj, pageidx)
struct uvm_aobj *aobj;
vm_offset_t pageidx;
{
/*
* if noswap flag is set, then we never return a slot
*/
if (aobj->u_flags & UAO_FLAG_NOSWAP)
return(0);
/*
* if hashing, look in hash table.
*/
if (UAO_USES_SWHASH(aobj)) {
struct uao_swhash_elt *elt = uao_find_swhash_elt(aobj, pageidx, FALSE);
if (elt)
return(UAO_SWHASH_ELT_PAGESLOT(elt, pageidx));
else
return(NULL);
}
/*
* otherwise, look in the array
*/
return(aobj->u_swslots[pageidx]);
}
/*
* uao_set_swslot: set the swap slot for a page in an aobj.
*
* => setting a slot to zero frees the slot
* => object must be locked by caller
*/
int uao_set_swslot(uobj, pageidx, slot)
struct uvm_object *uobj;
int pageidx, slot;
{
struct uvm_aobj *aobj = (struct uvm_aobj *)uobj;
int oldslot;
UVMHIST_FUNC("uao_set_swslot"); UVMHIST_CALLED(pdhist);
UVMHIST_LOG(pdhist, "aobj %p pageidx %d slot %d", aobj, pageidx, slot, 0);
/*
* if noswap flag is set, then we can't set a slot
*/
if (aobj->u_flags & UAO_FLAG_NOSWAP) {
if (slot == 0)
return(0); /* a clear is ok */
/* but a set is not */
printf("uao_set_swslot: uobj = %p\n", uobj);
panic("uao_set_swslot: attempt to set a slot on a NOSWAP object");
}
/*
* are we using a hash table? if so, add it in the hash.
*/
if (UAO_USES_SWHASH(aobj)) {
struct uao_swhash_elt *elt = uao_find_swhash_elt(aobj, pageidx, TRUE);
oldslot = UAO_SWHASH_ELT_PAGESLOT(elt, pageidx);
UAO_SWHASH_ELT_PAGESLOT(elt, pageidx) = slot;
/*
* now adjust the elt's reference counter and free it if we've dropped
* it to zero.
*/
if (slot) { /* an allocation? */
if (oldslot == 0)
elt->count++;
} else { /* freeing slot ... */
if (oldslot) /* to be safe (who would replace zero with zero?) */
elt->count--;
if (elt->count == 0) {
LIST_REMOVE(elt, list);
FREE(elt, M_UVMAOBJ);
}
}
} else {
/* we are using an array */
oldslot = aobj->u_swslots[pageidx];
aobj->u_swslots[pageidx] = slot;
}
return(oldslot);
}
/*
* end of hash/array functions
*/
/*
* uao_free: free all resources held by an aobj, and then free the aobj
*
* => the aobj should be dead
*/
static void
uao_free(aobj)
struct uvm_aobj *aobj;
{
if (UAO_USES_SWHASH(aobj)) {
int i, hashbuckets = aobj->u_swhashmask + 1;
/*
* free the swslots from each hash bucket,
* then the hash bucket, and finally the hash table itself.
*/
for (i = 0; i < hashbuckets; i++) {
struct uao_swhash_elt *elt, *next;
for (elt = aobj->u_swhash[i].lh_first; elt != NULL; elt = next) {
int j;
for (j = 0; j < UAO_SWHASH_CLUSTER_SIZE; j++)
{
int slot = elt->slots[j];
if (slot)
{
uvm_swap_free(slot, 1);
}
}
next = elt->list.le_next;
FREE(elt, M_UVMAOBJ);
}
}
FREE(aobj->u_swhash, M_UVMAOBJ);
} else {
int i;
/*
* free the array
*/
for (i = 0; i < aobj->u_pages; i++)
{
int slot = aobj->u_swslots[i];
if (slot)
{
uvm_swap_free(slot, 1);
}
}
FREE(aobj->u_swslots, M_UVMAOBJ);
}
/*
* finally free the aobj itself
*/
FREE(aobj, M_UVMAOBJ);
}
/*
* pager functions
*/
/*
* uao_create: create an aobj of the given size and return its uvm_object.
*
* => for normal use, flags are always zero
* => for the kernel object, the flags are:
* UAO_FLAG_KERNOBJ - allocate the kernel object (can only happen once)
* UAO_FLAG_KERNSWAP - enable swapping of kernel object (" ")
*/
struct uvm_object *uao_create(size, flags)
vm_size_t size;
int flags;
{
static struct uvm_aobj kernel_object_store; /* home of kernel_object */
static int kobj_alloced = 0; /* not allocated yet */
int pages = round_page(size) / PAGE_SIZE;
struct uvm_aobj *aobj;
/*
* malloc a new aobj unless we are asked for the kernel object
*/
if (flags & UAO_FLAG_KERNOBJ) { /* want kernel object? */
if (kobj_alloced)
panic("uao_create: kernel object already allocated");
aobj = &kernel_object_store;
aobj->u_pages = pages;
aobj->u_flags = UAO_FLAG_NOSWAP; /* no swap to start */
aobj->u_obj.uo_refs = UVM_OBJ_KERN; /* we are special, we never die */
kobj_alloced = UAO_FLAG_KERNOBJ;
} else if (flags & UAO_FLAG_KERNSWAP) {
aobj = &kernel_object_store;
if (kobj_alloced != UAO_FLAG_KERNOBJ)
panic("uao_create: asked to enable swap on kernel object");
kobj_alloced = UAO_FLAG_KERNSWAP;
} else { /* normal object */
MALLOC(aobj, struct uvm_aobj *, sizeof(*aobj), M_UVMAOBJ, M_WAITOK);
aobj->u_pages = pages;
aobj->u_flags = 0; /* normal object */
aobj->u_obj.uo_refs = 1; /* start with 1 reference */
}
/*
* allocate hash/array if necessary
*
* note: in the KERNSWAP case no need to worry about locking since
* we are still booting we should be the only thread around.
*/
if (flags == 0 || (flags & UAO_FLAG_KERNSWAP) != 0) {
int mflags = (flags & UAO_FLAG_KERNSWAP) != 0 ? M_NOWAIT : M_WAITOK;
/* allocate hash table or array depending on object size */
if (UAO_USES_SWHASH(aobj)) {
aobj->u_swhash = hashinit(UAO_SWHASH_BUCKETS(aobj), M_UVMAOBJ, mflags,
&aobj->u_swhashmask);
if (aobj->u_swhash == NULL)
panic("uao_create: hashinit swhash failed");
} else {
MALLOC(aobj->u_swslots, int *, pages * sizeof(int), M_UVMAOBJ, mflags);
if (aobj->u_swslots == NULL)
panic("uao_create: malloc swslots failed");
bzero(aobj->u_swslots, pages * sizeof(int));
}
if (flags) {
aobj->u_flags &= ~UAO_FLAG_NOSWAP; /* clear noswap */
return(&aobj->u_obj);
/* done! */
}
}
/*
* init aobj fields
*/
simple_lock_init(&aobj->u_obj.vmobjlock);
aobj->u_obj.pgops = &aobj_pager;
TAILQ_INIT(&aobj->u_obj.memq);
aobj->u_obj.uo_npages = 0;
/*
* now that aobj is ready, add it to the global list
* XXXCHS: uao_init hasn't been called'd in the KERNOBJ case, do we really
* need the kernel object on this list anyway?
*/
simple_lock(&uao_list_lock);
LIST_INSERT_HEAD(&uao_list, aobj, u_list);
simple_unlock(&uao_list_lock);
/*
* done!
*/
return(&aobj->u_obj);
}
/*
* uao_init: set up aobj pager subsystem
*
* => called at boot time from uvm_pager_init()
*/
static void uao_init()
{
LIST_INIT(&uao_list);
simple_lock_init(&uao_list_lock);
}
/*
* uao_reference: add a ref to an aobj
*
* => aobj must be unlocked (we will lock it)
*/
void uao_reference(uobj)
struct uvm_object *uobj;
{
UVMHIST_FUNC("uao_reference"); UVMHIST_CALLED(maphist);
/*
* kernel_object already has plenty of references, leave it alone.
*/
if (uobj->uo_refs == UVM_OBJ_KERN) {
return;
}
simple_lock(&uobj->vmobjlock);
uobj->uo_refs++; /* bump! */
UVMHIST_LOG(maphist, "<- done (uobj=0x%x, ref = %d)",
uobj, uobj->uo_refs,0,0);
simple_unlock(&uobj->vmobjlock);
}
/*
* uao_detach: drop a reference to an aobj
*
* => aobj must be unlocked, we will lock it
*/
void uao_detach(uobj)
struct uvm_object *uobj;
{
struct uvm_aobj *aobj = (struct uvm_aobj *)uobj;
struct vm_page *pg;
boolean_t busybody;
UVMHIST_FUNC("uao_detach"); UVMHIST_CALLED(maphist);
/*
* detaching from kernel_object is a noop.
*/
if (uobj->uo_refs == UVM_OBJ_KERN) {
return;
}
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;
}
/*
* remove the aobj from the global list.
*/
simple_lock(&uao_list_lock);
LIST_REMOVE(aobj, u_list);
simple_unlock(&uao_list_lock);
/*
* free all the pages that aren't PG_BUSY, mark for release any that are.
*/
busybody = FALSE;
for (pg = uobj->memq.tqh_first ; pg != NULL ; pg = pg->listq.tqe_next) {
int swslot;
if (pg->flags & PG_BUSY) {
pg->flags |= PG_RELEASED;
busybody = TRUE;
continue;
}
/* zap the mappings, free the swap slot, free the page */
pmap_page_protect(PMAP_PGARG(pg), VM_PROT_NONE);
swslot = uao_set_swslot(&aobj->u_obj, pg->offset / PAGE_SIZE, 0);
if (swslot) {
uvm_swap_free(swslot, 1);
}
uvm_lock_pageq();
uvm_pagefree(pg);
uvm_unlock_pageq();
}
/*
* if we found any busy pages, we're done for now.
* mark the aobj for death, releasepg will finish up for us.
*/
if (busybody) {
aobj->u_flags |= UAO_FLAG_KILLME;
simple_unlock(&aobj->u_obj.vmobjlock);
return;
}
/*
* finally, free the rest.
*/
uao_free(aobj);
}
/*
* uao_flush: uh, yea, sure it's flushed. really!
*/
boolean_t uao_flush(uobj, start, end, flags)
struct uvm_object *uobj;
vm_offset_t start, end;
int flags;
{
/*
* anonymous memory doesn't "flush"
*/
/*
* XXX
* deal with PGO_DEACTIVATE (for madvise(MADV_SEQUENTIAL))
* and PGO_FREE (for msync(MSINVALIDATE))
*/
return TRUE;
}
/*
* uao_get: fetch me a page
*
* we have three cases:
* 1: page is resident -> just return the page.
* 2: page is zero-fill -> allocate a new page and zero it.
* 3: page is swapped out -> fetch the page from swap.
*
* cases 1 and 2 can be handled with PGO_LOCKED, case 3 cannot.
* so, if the "center" page hits case 3 (or any page, with PGO_ALLPAGES),
* then we will need to return VM_PAGER_UNLOCK.
*
* => 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 uao_get(uobj, offset, pps, npagesp, centeridx, access_type,
advice, flags)
struct uvm_object *uobj;
vm_offset_t offset;
struct vm_page **pps;
int *npagesp;
int centeridx, advice, flags;
vm_prot_t access_type;
{
struct uvm_aobj *aobj = (struct uvm_aobj *)uobj;
vm_offset_t current_offset;
vm_page_t ptmp;
int lcv, gotpages, maxpages, swslot, rv;
boolean_t done;
UVMHIST_FUNC("uao_get"); UVMHIST_CALLED(pdhist);
UVMHIST_LOG(pdhist, "aobj=%p offset=%d, flags=%d", aobj, offset, flags,0);
/*
* get number of pages
*/
maxpages = *npagesp;
/*
* step 1: handled the case where fault data structures are locked.
*/
if (flags & PGO_LOCKED) {
/*
* 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 */
gotpages = 0; /* # of pages we got so far */
for (lcv = 0, current_offset = offset ;
lcv < maxpages ; lcv++, current_offset += PAGE_SIZE) {
/* do we care about this page? if not, skip it */
if (pps[lcv] == PGO_DONTCARE)
continue;
ptmp = uvm_pagelookup(uobj, current_offset);
/*
* if page is new, attempt to allocate the page, then zero-fill it.
*/
if (ptmp == NULL &&
uao_find_swslot(aobj, current_offset / PAGE_SIZE) == 0) {
ptmp = uvm_pagealloc(uobj, current_offset, NULL);
if (ptmp) {
ptmp->flags &= ~(PG_BUSY|PG_FAKE); /* new page */
ptmp->pqflags |= PQ_AOBJ;
UVM_PAGE_OWN(ptmp, NULL);
uvm_pagezero(ptmp);
}
}
/* to be useful must get a non-busy, non-released page */
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; /* caller must un-busy this page */
UVM_PAGE_OWN(ptmp, "uao_get1");
pps[lcv] = ptmp;
gotpages++;
} /* "for" lcv loop */
/*
* step 1b: now we've either done everything needed or we to unlock
* and do some waiting or I/O.
*/
UVMHIST_LOG(pdhist, "<- done (done=%d)", done, 0,0,0);
*npagesp = gotpages;
if (done)
return(VM_PAGER_OK); /* bingo! */
else
return(VM_PAGER_UNLOCK); /* EEK! Need to unlock and I/O */
}
/*
* step 2: get non-resident or busy pages.
* object is locked. data structures are unlocked.
*/
for (lcv = 0, current_offset = offset ;
lcv < maxpages ;
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
* find 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 'break's 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 resident page */
ptmp = uvm_pagelookup(uobj, current_offset);
/* not resident? allocate one now (if we can) */
if (ptmp == NULL) {
ptmp = uvm_pagealloc(uobj, current_offset, NULL); /* alloc */
/* out of RAM? */
if (ptmp == NULL) {
simple_unlock(&uobj->vmobjlock);
UVMHIST_LOG(pdhist, "sleeping, ptmp == NULL\n",0,0,0,0);
uvm_wait("uao_getpage");
simple_lock(&uobj->vmobjlock);
continue; /* goto top of pps while loop */
}
/* safe with PQ's unlocked: because we just alloc'd the page */
ptmp->pqflags |= PQ_AOBJ;
/*
* 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;
UVMHIST_LOG(pdhist, "sleeping, ptmp->flags 0x%x\n",ptmp->flags,0,0,0);
UVM_UNLOCK_AND_WAIT(ptmp,&uobj->vmobjlock,0,"uao_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; /* we own it, caller must un-busy */
UVM_PAGE_OWN(ptmp, "uao_get2");
pps[lcv] = ptmp;
}
/*
* if we own the 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 the needed "i/o", either reading from swap or zeroing.
*/
swslot = uao_find_swslot(aobj, current_offset / PAGE_SIZE);
/*
* just zero the page if there's nothing in swap.
*/
if (swslot == 0)
{
/*
* page hasn't existed before, just zero it.
*/
uvm_pagezero(ptmp);
}
else
{
UVMHIST_LOG(pdhist, "pagein from swslot %d", swslot, 0,0,0);
/*
* page in the swapped-out page.
* unlock object for i/o, relock when done.
*/
simple_unlock(&uobj->vmobjlock);
rv = uvm_swap_get(ptmp, swslot, PGO_SYNCIO);
simple_lock(&uobj->vmobjlock);
/*
* I/O done. check for errors.
*/
if (rv != VM_PAGER_OK)
{
UVMHIST_LOG(pdhist, "<- done (error=%d)",rv,0,0,0);
if (ptmp->flags & PG_WANTED)
thread_wakeup(ptmp); /* object lock still held */
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 rv;
}
}
/*
* 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);
UVMHIST_LOG(pdhist, "<- done (OK)",0,0,0,0);
return(VM_PAGER_OK);
}
/*
* uao_releasepg: handle released page in an aobj
*
* => "pg" is a PG_BUSY [caller owns it], PG_RELEASED page that we need
* to dispose of.
* => caller must handle 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 aobj if it is not referenced and we are suppose to
* kill it ("KILLME").
*/
static boolean_t uao_releasepg(pg, nextpgp)
struct vm_page *pg;
struct vm_page **nextpgp; /* OUT */
{
struct uvm_aobj *aobj = (struct uvm_aobj *) pg->uobject;
int slot;
#ifdef DIAGNOSTIC
if ((pg->flags & PG_RELEASED) == 0)
panic("uao_releasepg: page not released!");
#endif
/*
* dispose of the page [caller handles PG_WANTED] and swap slot.
*/
pmap_page_protect(PMAP_PGARG(pg), VM_PROT_NONE);
slot = uao_set_swslot(&aobj->u_obj, pg->offset / PAGE_SIZE, 0);
if (slot)
uvm_swap_free(slot, 1);
uvm_lock_pageq();
if (nextpgp)
*nextpgp = pg->pageq.tqe_next; /* next page for daemon */
uvm_pagefree(pg);
if (!nextpgp)
uvm_unlock_pageq(); /* keep locked for daemon */
/*
* if we're not killing the object, we're done.
*/
if ((aobj->u_flags & UAO_FLAG_KILLME) == 0)
return TRUE;
#ifdef DIAGNOSTIC
if (aobj->u_obj.uo_refs)
panic("uvm_km_releasepg: kill flag set on referenced object!");
#endif
/*
* if there are still pages in the object, we're done for now.
*/
if (aobj->u_obj.uo_npages != 0)
return TRUE;
#ifdef DIAGNOSTIC
if (aobj->u_obj.memq.tqh_first)
panic("uvn_releasepg: pages in object with npages == 0");
#endif
/*
* finally, free the rest.
*/
uao_free(aobj);
return FALSE;
}
Reference in New Issue View Git Blame Copy Permalink