1/* NOMMU mmap support for RomFS on MTD devices
 2 *
 3 * Copyright © 2007 Red Hat, Inc. All Rights Reserved.
 4 * Written by David Howells (dhowells@redhat.com)
 5 *
 6 * This program is free software; you can redistribute it and/or
 7 * modify it under the terms of the GNU General Public License
 8 * as published by the Free Software Foundation; either version
 9 * 2 of the License, or (at your option) any later version.
10 */
11
12#include <linux/mm.h>
13#include <linux/mtd/super.h>
14#include "internal.h"
15
16/*
17 * try to determine where a shared mapping can be made
18 * - only supported for NOMMU at the moment (MMU can't doesn't copy private
19 *   mappings)
20 * - attempts to map through to the underlying MTD device
21 */
22static unsigned long romfs_get_unmapped_area(struct file *file,
23					     unsigned long addr,
24					     unsigned long len,
25					     unsigned long pgoff,
26					     unsigned long flags)
27{
28	struct inode *inode = file->f_mapping->host;
29	struct mtd_info *mtd = inode->i_sb->s_mtd;
30	unsigned long isize, offset, maxpages, lpages;
31	int ret;
32
33	if (!mtd)
34		return (unsigned long) -ENOSYS;
35
36	/* the mapping mustn't extend beyond the EOF */
37	lpages = (len + PAGE_SIZE - 1) >> PAGE_SHIFT;
38	isize = i_size_read(inode);
39	offset = pgoff << PAGE_SHIFT;
40
41	maxpages = (isize + PAGE_SIZE - 1) >> PAGE_SHIFT;
42	if ((pgoff >= maxpages) || (maxpages - pgoff < lpages))
43		return (unsigned long) -EINVAL;
44
45	if (addr != 0)
46		return (unsigned long) -EINVAL;
47
48	if (len > mtd->size || pgoff >= (mtd->size >> PAGE_SHIFT))
49		return (unsigned long) -EINVAL;
50
51	offset += ROMFS_I(inode)->i_dataoffset;
52	if (offset > mtd->size - len)
53		return (unsigned long) -EINVAL;
 
 
 
54
55	ret = mtd_get_unmapped_area(mtd, len, offset, flags);
56	if (ret == -EOPNOTSUPP)
57		ret = -ENOSYS;
58	return (unsigned long) ret;
59}
60
61/*
62 * permit a R/O mapping to be made directly through onto an MTD device if
63 * possible
64 */
65static int romfs_mmap(struct file *file, struct vm_area_struct *vma)
66{
67	return vma->vm_flags & (VM_SHARED | VM_MAYSHARE) ? 0 : -ENOSYS;
 
 
 
 
 
 
 
 
 
68}
69
70const struct file_operations romfs_ro_fops = {
71	.llseek			= generic_file_llseek,
72	.read			= do_sync_read,
73	.aio_read		= generic_file_aio_read,
74	.splice_read		= generic_file_splice_read,
75	.mmap			= romfs_mmap,
76	.get_unmapped_area	= romfs_get_unmapped_area,
 
77};

 1// SPDX-License-Identifier: GPL-2.0-or-later
 2/* NOMMU mmap support for RomFS on MTD devices
 3 *
 4 * Copyright © 2007 Red Hat, Inc. All Rights Reserved.
 5 * Written by David Howells (dhowells@redhat.com)
 
 
 
 
 
 6 */
 7
 8#include <linux/mm.h>
 9#include <linux/mtd/super.h>
10#include "internal.h"
11
12/*
13 * try to determine where a shared mapping can be made
14 * - only supported for NOMMU at the moment (MMU can't doesn't copy private
15 *   mappings)
16 * - attempts to map through to the underlying MTD device
17 */
18static unsigned long romfs_get_unmapped_area(struct file *file,
19					     unsigned long addr,
20					     unsigned long len,
21					     unsigned long pgoff,
22					     unsigned long flags)
23{
24	struct inode *inode = file->f_mapping->host;
25	struct mtd_info *mtd = inode->i_sb->s_mtd;
26	unsigned long isize, offset, maxpages, lpages;
27	int ret;
28
29	if (!mtd)
30		return (unsigned long) -ENOSYS;
31
32	/* the mapping mustn't extend beyond the EOF */
33	lpages = (len + PAGE_SIZE - 1) >> PAGE_SHIFT;
34	isize = i_size_read(inode);
35	offset = pgoff << PAGE_SHIFT;
36
37	maxpages = (isize + PAGE_SIZE - 1) >> PAGE_SHIFT;
38	if ((pgoff >= maxpages) || (maxpages - pgoff < lpages))
39		return (unsigned long) -EINVAL;
40
41	if (addr != 0)
42		return (unsigned long) -EINVAL;
43
44	if (len > mtd->size || pgoff >= (mtd->size >> PAGE_SHIFT))
45		return (unsigned long) -EINVAL;
46
47	offset += ROMFS_I(inode)->i_dataoffset;
48	if (offset >= mtd->size)
49		return (unsigned long) -EINVAL;
50	/* the mapping mustn't extend beyond the EOF */
51	if ((offset + len) > mtd->size)
52		len = mtd->size - offset;
53
54	ret = mtd_get_unmapped_area(mtd, len, offset, flags);
55	if (ret == -EOPNOTSUPP)
56		ret = -ENOSYS;
57	return (unsigned long) ret;
58}
59
60/*
61 * permit a R/O mapping to be made directly through onto an MTD device if
62 * possible
63 */
64static int romfs_mmap(struct file *file, struct vm_area_struct *vma)
65{
66	return is_nommu_shared_mapping(vma->vm_flags) ? 0 : -ENOSYS;
67}
68
69static unsigned romfs_mmap_capabilities(struct file *file)
70{
71	struct mtd_info *mtd = file_inode(file)->i_sb->s_mtd;
72
73	if (!mtd)
74		return NOMMU_MAP_COPY;
75	return mtd_mmap_capabilities(mtd);
76}
77
78const struct file_operations romfs_ro_fops = {
79	.llseek			= generic_file_llseek,
80	.read_iter		= generic_file_read_iter,
81	.splice_read		= filemap_splice_read,
 
82	.mmap			= romfs_mmap,
83	.get_unmapped_area	= romfs_get_unmapped_area,
84	.mmap_capabilities	= romfs_mmap_capabilities,
85};