xref: /netbsd-src/sys/external/bsd/drm2/include/linux/shmem_fs.h (revision 55d48114186d94fd53ff5cdb77063ed0c2d5390e)
1 /*	$NetBSD: shmem_fs.h,v 1.5 2022/08/20 23:49:31 riastradh Exp $	*/
2 
3 /*-
4  * Copyright (c) 2013 The NetBSD Foundation, Inc.
5  * All rights reserved.
6  *
7  * This code is derived from software contributed to The NetBSD Foundation
8  * by Taylor R. Campbell.
9  *
10  * Redistribution and use in source and binary forms, with or without
11  * modification, are permitted provided that the following conditions
12  * are met:
13  * 1. Redistributions of source code must retain the above copyright
14  *    notice, this list of conditions and the following disclaimer.
15  * 2. Redistributions in binary form must reproduce the above copyright
16  *    notice, this list of conditions and the following disclaimer in the
17  *    documentation and/or other materials provided with the distribution.
18  *
19  * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
20  * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
21  * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
22  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
23  * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
24  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
25  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
26  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
27  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
28  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
29  * POSSIBILITY OF SUCH DAMAGE.
30  */
31 
32 #ifndef _LINUX_SHMEM_FS_H_
33 #define _LINUX_SHMEM_FS_H_
34 
35 #include <sys/types.h>
36 #include <sys/param.h>
37 
38 #include <sys/rwlock.h>
39 
40 #include <lib/libkern/libkern.h>
41 
42 #include <uvm/uvm_extern.h>
43 #include <uvm/uvm_object.h>
44 
45 #include <linux/err.h>
46 #include <linux/gfp.h>
47 #include <linux/mm_types.h>
48 
49 static inline struct page *
shmem_read_mapping_page_gfp(struct uvm_object * uobj,voff_t i,gfp_t gfp)50 shmem_read_mapping_page_gfp(struct uvm_object *uobj, voff_t i, gfp_t gfp)
51 {
52 	struct vm_page *vm_page;
53 	int error;
54 
55 	error = uvm_obj_wirepages(uobj, i*PAGE_SIZE, (i + 1)*PAGE_SIZE, NULL);
56 	if (error)
57 		return ERR_PTR(-error); /* XXX errno NetBSD->Linux */
58 
59 	rw_enter(uobj->vmobjlock, RW_READER);
60 	vm_page = uvm_pagelookup(uobj, i*PAGE_SIZE);
61 	rw_exit(uobj->vmobjlock);
62 
63 	KASSERT(vm_page);
64 	return container_of(vm_page, struct page, p_vmp);
65 }
66 
67 static inline struct page *
shmem_read_mapping_page(struct uvm_object * uobj,voff_t i)68 shmem_read_mapping_page(struct uvm_object *uobj, voff_t i)
69 {
70 	return shmem_read_mapping_page_gfp(uobj, i, GFP_KERNEL);
71 }
72 
73 static inline void
shmem_truncate_range(struct uvm_object * uobj,voff_t start,voff_t end)74 shmem_truncate_range(struct uvm_object *uobj, voff_t start, voff_t end)
75 {
76 	int flags = PGO_FREE;
77 
78 	if (start == 0 && end == -1) {
79 		flags |= PGO_ALLPAGES;
80 	} else {
81 		KASSERT(0 <= start);
82 		KASSERT(start <= end);
83 	}
84 
85 	rw_enter(uobj->vmobjlock, RW_WRITER);
86 	(*uobj->pgops->pgo_put)(uobj, start, end, flags);
87 }
88 
89 #endif  /* _LINUX_SHMEM_FS_H_ */
90