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freebsd-skq/sys/vm/vm_pager.h
Gleb Smirnoff b0cd20172d A change to KPI of vm_pager_get_pages() and underlying VOP_GETPAGES(). 
o With new KPI consumers can request contiguous ranges of pages, and
  unlike before, all pages will be kept busied on return, like it was
  done before with the 'reqpage' only. Now the reqpage goes away. With
  new interface it is easier to implement code protected from race
  conditions.

  Such arrayed requests for now should be preceeded by a call to
  vm_pager_haspage() to make sure that request is possible. This
  could be improved later, making vm_pager_haspage() obsolete.

  Strenghtening the promises on the business of the array of pages
  allows us to remove such hacks as swp_pager_free_nrpage() and
  vm_pager_free_nonreq().

o New KPI accepts two integer pointers that may optionally point at
  values for read ahead and read behind, that a pager may do, if it
  can. These pages are completely owned by pager, and not controlled
  by the caller.

  This shifts the UFS-specific readahead logic from vm_fault.c, which
  should be file system agnostic, into vnode_pager.c. It also removes
  one VOP_BMAP() request per hard fault.

Discussed with:	kib, alc, jeff, scottl
Sponsored by:	Nginx, Inc.
Sponsored by:	Netflix
2015-12-16 21:30:45 +00:00

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/*-
* Copyright (c) 1990 University of Utah.
* Copyright (c) 1991, 1993
* The Regents of the University of California. 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.
* 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.
*
* @(#)vm_pager.h 8.4 (Berkeley) 1/12/94
* $FreeBSD$
*/
/*
* Pager routine interface definition.
*/
#ifndef _VM_PAGER_
#define _VM_PAGER_
#include <sys/queue.h>
TAILQ_HEAD(pagerlst, vm_object);
typedef void pgo_init_t(void);
typedef vm_object_t pgo_alloc_t(void *, vm_ooffset_t, vm_prot_t, vm_ooffset_t,
struct ucred *);
typedef void pgo_dealloc_t(vm_object_t);
typedef int pgo_getpages_t(vm_object_t, vm_page_t *, int, int *, int *);
typedef void pgo_getpages_iodone_t(void *, vm_page_t *, int, int);
typedef int pgo_getpages_async_t(vm_object_t, vm_page_t *, int, int *, int *,
pgo_getpages_iodone_t, void *);
typedef void pgo_putpages_t(vm_object_t, vm_page_t *, int, int, int *);
typedef boolean_t pgo_haspage_t(vm_object_t, vm_pindex_t, int *, int *);
typedef void pgo_pageunswapped_t(vm_page_t);
struct pagerops {
pgo_init_t *pgo_init; /* Initialize pager. */
pgo_alloc_t *pgo_alloc; /* Allocate pager. */
pgo_dealloc_t *pgo_dealloc; /* Disassociate. */
pgo_getpages_t *pgo_getpages; /* Get (read) page. */
pgo_getpages_async_t *pgo_getpages_async; /* Get page asyncly. */
pgo_putpages_t *pgo_putpages; /* Put (write) page. */
pgo_haspage_t *pgo_haspage; /* Query page. */
pgo_pageunswapped_t *pgo_pageunswapped;
};
extern struct pagerops defaultpagerops;
extern struct pagerops swappagerops;
extern struct pagerops vnodepagerops;
extern struct pagerops devicepagerops;
extern struct pagerops physpagerops;
extern struct pagerops sgpagerops;
extern struct pagerops mgtdevicepagerops;
/*
* get/put return values
* OK operation was successful
* BAD specified data was out of the accepted range
* FAIL specified data was in range, but doesn't exist
* PEND operations was initiated but not completed
* ERROR error while accessing data that is in range and exists
* AGAIN temporary resource shortage prevented operation from happening
*/
#define VM_PAGER_OK 0
#define VM_PAGER_BAD 1
#define VM_PAGER_FAIL 2
#define VM_PAGER_PEND 3
#define VM_PAGER_ERROR 4
#define VM_PAGER_AGAIN 5
#define VM_PAGER_PUT_SYNC 0x0001
#define VM_PAGER_PUT_INVAL 0x0002
#define VM_PAGER_CLUSTER_OK 0x0008
#ifdef _KERNEL
extern struct pagerops *pagertab[];
extern struct mtx_padalign pbuf_mtx;
vm_object_t vm_pager_allocate(objtype_t, void *, vm_ooffset_t, vm_prot_t,
vm_ooffset_t, struct ucred *);
void vm_pager_bufferinit(void);
void vm_pager_deallocate(vm_object_t);
int vm_pager_get_pages(vm_object_t, vm_page_t *, int, int *, int *);
int vm_pager_get_pages_async(vm_object_t, vm_page_t *, int, int *, int *,
pgo_getpages_iodone_t, void *);
static __inline boolean_t vm_pager_has_page(vm_object_t, vm_pindex_t, int *, int *);
void vm_pager_init(void);
vm_object_t vm_pager_object_lookup(struct pagerlst *, void *);
static __inline void
vm_pager_put_pages(
vm_object_t object,
vm_page_t *m,
int count,
int flags,
int *rtvals
) {
VM_OBJECT_ASSERT_WLOCKED(object);
(*pagertab[object->type]->pgo_putpages)
(object, m, count, flags, rtvals);
}
/*
* vm_pager_haspage
*
* Check to see if an object's pager has the requested page. The
* object's pager will also set before and after to give the caller
* some idea of the number of pages before and after the requested
* page can be I/O'd efficiently.
*
* The object must be locked.
*/
static __inline boolean_t
vm_pager_has_page(
vm_object_t object,
vm_pindex_t offset,
int *before,
int *after
) {
boolean_t ret;
VM_OBJECT_ASSERT_WLOCKED(object);
ret = (*pagertab[object->type]->pgo_haspage)
(object, offset, before, after);
return (ret);
}
/*
* vm_pager_page_unswapped
*
* Destroy swap associated with the page.
*
* The object containing the page must be locked.
* This function may not block.
*
* XXX: A much better name would be "vm_pager_page_dirtied()"
* XXX: It is not obvious if this could be profitably used by any
* XXX: pagers besides the swap_pager or if it should even be a
* XXX: generic pager_op in the first place.
*/
static __inline void
vm_pager_page_unswapped(vm_page_t m)
{
VM_OBJECT_ASSERT_LOCKED(m->object);
if (pagertab[m->object->type]->pgo_pageunswapped)
(*pagertab[m->object->type]->pgo_pageunswapped)(m);
}
struct cdev_pager_ops {
int (*cdev_pg_fault)(vm_object_t vm_obj, vm_ooffset_t offset,
int prot, vm_page_t *mres);
int (*cdev_pg_ctor)(void *handle, vm_ooffset_t size, vm_prot_t prot,
vm_ooffset_t foff, struct ucred *cred, u_short *color);
void (*cdev_pg_dtor)(void *handle);
};
vm_object_t cdev_pager_allocate(void *handle, enum obj_type tp,
struct cdev_pager_ops *ops, vm_ooffset_t size, vm_prot_t prot,
vm_ooffset_t foff, struct ucred *cred);
vm_object_t cdev_pager_lookup(void *handle);
void cdev_pager_free_page(vm_object_t object, vm_page_t m);
#endif /* _KERNEL */
#endif /* _VM_PAGER_ */
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