vm_pager.h

/*-
 * SPDX-License-Identifier: BSD-3-Clause
 *
 * 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.
 * 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.
 */

/*
 * Pager routine interface definition.
 */

#ifndef	_VM_PAGER_
#define	_VM_PAGER_

#include <sys/systm.h>

TAILQ_HEAD(pagerlst, vm_object);
struct vnode;

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 int pgo_populate_t(vm_object_t, vm_pindex_t, int, vm_prot_t,
    vm_pindex_t *, vm_pindex_t *);
typedef void pgo_pageunswapped_t(vm_page_t);
typedef void pgo_writecount_t(vm_object_t, vm_offset_t, vm_offset_t);
typedef void pgo_set_writeable_dirty_t(vm_object_t);
typedef bool pgo_mightbedirty_t(vm_object_t);
typedef void pgo_getvp_t(vm_object_t object, struct vnode **vpp,
    bool *vp_heldp);
typedef void pgo_freespace_t(vm_object_t object, vm_pindex_t start,
    vm_size_t size);
typedef void pgo_page_inserted_t(vm_object_t object, vm_page_t m);
typedef void pgo_page_removed_t(vm_object_t object, vm_page_t m);
typedef boolean_t pgo_can_alloc_page_t(vm_object_t object, vm_pindex_t pindex);

struct pagerops {
	int			pgo_kvme_type;
	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_populate_t		*pgo_populate;		/* Bulk spec pagein. */
	pgo_pageunswapped_t	*pgo_pageunswapped;
	pgo_writecount_t	*pgo_update_writecount;
	pgo_writecount_t	*pgo_release_writecount;
	pgo_set_writeable_dirty_t *pgo_set_writeable_dirty;
	pgo_mightbedirty_t	*pgo_mightbedirty;
	pgo_getvp_t		*pgo_getvp;
	pgo_freespace_t		*pgo_freespace;
	pgo_page_inserted_t	*pgo_page_inserted;
	pgo_page_removed_t	*pgo_page_removed;
	pgo_can_alloc_page_t	*pgo_can_alloc_page;
};

extern const struct pagerops defaultpagerops;
extern const struct pagerops swappagerops;
extern const struct pagerops vnodepagerops;
extern const struct pagerops devicepagerops;
extern const struct pagerops physpagerops;
extern const struct pagerops sgpagerops;
extern const struct pagerops mgtdevicepagerops;
extern const struct pagerops swaptmpfspagerops;

/*
 * 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_PUT_NOREUSE		0x0004
#define VM_PAGER_CLUSTER_OK		0x0008

#ifdef _KERNEL

extern const struct pagerops *pagertab[] __read_mostly;
extern struct mtx_padalign pbuf_mtx;

/*
 * Number of pages that pbuf buffer can store in b_pages.
 * It is +1 to allow for unaligned data buffer of maxphys size.
 */
#define	PBUF_PAGES	(atop(maxphys) + 1)

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 *);
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_LOCKED(object);
	ret = (*pagertab[object->type]->pgo_haspage)
	    (object, offset, before, after);
	return (ret);
} 

static __inline int
vm_pager_populate(vm_object_t object, vm_pindex_t pidx, int fault_type,
    vm_prot_t max_prot, vm_pindex_t *first, vm_pindex_t *last)
{

	MPASS((object->flags & OBJ_POPULATE) != 0);
	MPASS(pidx < object->size);
	MPASS(blockcount_read(&object->paging_in_progress) > 0);
	return ((*pagertab[object->type]->pgo_populate)(object, pidx,
	    fault_type, max_prot, first, last));
}

/* 
 *      vm_pager_page_unswapped
 * 
 *	Destroy swap associated with the page.
 * 
 *	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)
{
	pgo_pageunswapped_t *method;

	method = pagertab[m->object->type]->pgo_pageunswapped;
	if (method != NULL)
		method(m);
}

static __inline void
vm_pager_update_writecount(vm_object_t object, vm_offset_t start,
    vm_offset_t end)
{
	pgo_writecount_t *method;

	method = pagertab[object->type]->pgo_update_writecount;
	if (method != NULL)
		method(object, start, end);
}

static __inline void
vm_pager_release_writecount(vm_object_t object, vm_offset_t start,
    vm_offset_t end)
{
	pgo_writecount_t *method;

	method = pagertab[object->type]->pgo_release_writecount;
	if (method != NULL)
		method(object, start, end);
}

static __inline void
vm_pager_getvp(vm_object_t object, struct vnode **vpp, bool *vp_heldp)
{
	pgo_getvp_t *method;

	*vpp = NULL;
	if (vp_heldp != NULL)
		*vp_heldp = false;
	method = pagertab[object->type]->pgo_getvp;
	if (method != NULL)
		method(object, vpp, vp_heldp);
}

static __inline void
vm_pager_freespace(vm_object_t object, vm_pindex_t start,
    vm_size_t size)
{
	pgo_freespace_t *method;

	method = pagertab[object->type]->pgo_freespace;
	if (method != NULL)
		method(object, start, size);
}

static __inline void
vm_pager_page_inserted(vm_object_t object, vm_page_t m)
{
	pgo_page_inserted_t *method;

	method = pagertab[object->type]->pgo_page_inserted;
	if (method != NULL)
		method(object, m);
}

static __inline void
vm_pager_page_removed(vm_object_t object, vm_page_t m)
{
	pgo_page_removed_t *method;

	method = pagertab[object->type]->pgo_page_removed;
	if (method != NULL)
		method(object, m);
}

static __inline bool
vm_pager_can_alloc_page(vm_object_t object, vm_pindex_t pindex)
{
	pgo_can_alloc_page_t *method;

	method = pagertab[object->type]->pgo_can_alloc_page;
	return (method != NULL ? method(object, pindex) : true);
}

int vm_pager_alloc_dyn_type(struct pagerops *ops, int base_type);
void vm_pager_free_dyn_type(objtype_t type);

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_populate)(vm_object_t vm_obj, vm_pindex_t pidx,
	    int fault_type, vm_prot_t max_prot, vm_pindex_t *first,
	    vm_pindex_t *last);
	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);
	void (*cdev_pg_path)(void *handle, char *path, size_t len);
};

vm_object_t cdev_pager_allocate(void *handle, enum obj_type tp,
    const 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);
void cdev_mgtdev_pager_free_page(struct pctrie_iter *pages, vm_page_t m);
void cdev_mgtdev_pager_free_pages(vm_object_t object);
void cdev_pager_get_path(vm_object_t object, char *path, size_t sz);

struct phys_pager_ops {
	int (*phys_pg_getpages)(vm_object_t vm_obj, vm_page_t *m, int count,
	    int *rbehind, int *rahead);
	int (*phys_pg_populate)(vm_object_t vm_obj, vm_pindex_t pidx,
	    int fault_type, vm_prot_t max_prot, vm_pindex_t *first,
	    vm_pindex_t *last);
	boolean_t (*phys_pg_haspage)(vm_object_t obj,  vm_pindex_t pindex,
	    int *before, int *after);
	void (*phys_pg_ctor)(vm_object_t vm_obj, vm_prot_t prot,
	    vm_ooffset_t foff, struct ucred *cred);
	void (*phys_pg_dtor)(vm_object_t vm_obj);
};
extern const struct phys_pager_ops default_phys_pg_ops;
vm_object_t phys_pager_allocate(void *handle, const struct phys_pager_ops *ops,
    void *data, vm_ooffset_t size, vm_prot_t prot, vm_ooffset_t foff,
    struct ucred *cred);

#endif				/* _KERNEL */
#endif				/* _VM_PAGER_ */