diff options
Diffstat (limited to 'sys/vm/default_pager.c')
-rw-r--r-- | sys/vm/default_pager.c | 82 |
1 files changed, 41 insertions, 41 deletions
diff --git a/sys/vm/default_pager.c b/sys/vm/default_pager.c index ba92894..16b7512 100644 --- a/sys/vm/default_pager.c +++ b/sys/vm/default_pager.c @@ -28,7 +28,15 @@ * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF * SUCH DAMAGE. * - * $Id: default_pager.c,v 1.15 1998/02/06 12:14:20 eivind Exp $ + * The default pager is responsible for supplying backing store to unbacked + * storage. The backing store is usually swap so we just fall through to + * the swap routines. However, since swap metadata has not been assigned, + * the swap routines assign and manage the swap backing store through the + * vm_page->swapblk field. The object is only converted when the page is + * physically freed after having been cleaned and even then vm_page->swapblk + * is maintained whenever a resident page also has swap backing store. + * + * $Id: default_pager.c,v 1.16 1998/10/13 08:24:42 dg Exp $ */ #include <sys/param.h> @@ -78,6 +86,14 @@ default_pager_alloc(void *handle, vm_ooffset_t size, vm_prot_t prot, return vm_object_allocate(OBJT_DEFAULT, OFF_TO_IDX(round_page(offset + size))); } +/* + * deallocate resources associated with default objects. The default objects + * have no special resources allocated to them, but the vm_page's being used + * in this object might. Still, we do not have to do anything - we will free + * the swapblk in the underlying vm_page's when we free the vm_page or + * garbage collect the vm_page cache list. + */ + static void default_pager_dealloc(object) vm_object_t object; @@ -88,9 +104,11 @@ default_pager_dealloc(object) } /* - * The default pager has no backing store, so we always return - * failure. + * Load pages from backing store. Since OBJT_DEFAULT is converted to + * OBJT_SWAP at the time a swap-backed vm_page_t is freed, we will never + * see a vm_page with assigned swap here. */ + static int default_pager_getpages(object, m, count, reqpage) vm_object_t object; @@ -101,6 +119,13 @@ default_pager_getpages(object, m, count, reqpage) return VM_PAGER_FAIL; } +/* + * Store pages to backing store. We should assign swap and initiate + * I/O. We do not actually convert the object to OBJT_SWAP here. The + * object will be converted when the written-out vm_page_t is moved from the + * cache to the free list. + */ + static int default_pager_putpages(object, m, c, sync, rtvals) vm_object_t object; @@ -109,26 +134,22 @@ default_pager_putpages(object, m, c, sync, rtvals) boolean_t sync; int *rtvals; { - int i; - - /* - * Try to convert the object type into a OBJT_SWAP. - * If the swp structure allocation fails, convert it - * back to OBJT_DEFAULT and return failure. Otherwise - * pass this putpages to the swap pager. - */ - object->type = OBJT_SWAP; - - if (swap_pager_swp_alloc(object, M_KERNEL) != 0) { - object->type = OBJT_DEFAULT; - for (i = 0; i < c; i++) - rtvals[i] = VM_PAGER_FAIL; - return VM_PAGER_FAIL; - } - return swap_pager_putpages(object, m, c, sync, rtvals); } +/* + * Tell us whether the backing store for the requested (object,index) is + * synchronized. i.e. tell us whether we can throw the page away and + * reload it later. So, for example, if we are in the process of writing + * the page to its backing store, or if no backing store has been assigned, + * it is not yet synchronized. + * + * It is possible to have fully-synchronized swap assigned without the + * object having been converted. We just call swap_pager_haspage() to + * deal with it since it must already deal with it plus deal with swap + * meta-data structures. + */ + static boolean_t default_pager_haspage(object, pindex, before, after) vm_object_t object; @@ -139,24 +160,3 @@ default_pager_haspage(object, pindex, before, after) return FALSE; } -void -default_pager_convert_to_swap(object) - vm_object_t object; -{ - object->type = OBJT_SWAP; - if (swap_pager_swp_alloc(object, M_KERNEL) != 0) { - object->type = OBJT_DEFAULT; - } -} - -void -default_pager_convert_to_swapq(object) - vm_object_t object; -{ - if (object && - (object->type == OBJT_DEFAULT) && - (object != kernel_object && object != kmem_object) && - (object->size > ((cnt.v_page_count - cnt.v_wire_count) / 4))) - default_pager_convert_to_swap(object); -} - |