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      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 *
     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 *
     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
     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