blob: 1118a0dc6b45f0292cfdf34970d35c6dfc2e6ba8 [file] [log] [blame]
David Howellsda4458b2009-02-12 10:40:10 +00001/* 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;
Bob Liu2b4b2482011-06-27 16:18:06 -070030 unsigned long isize, offset, maxpages, lpages;
Artem Bityutskiy4991e722011-12-28 17:08:03 +020031 int ret;
David Howellsda4458b2009-02-12 10:40:10 +000032
33 if (!mtd)
Artem Bityutskiy4991e722011-12-28 17:08:03 +020034 return (unsigned long) -ENOSYS;
David Howellsda4458b2009-02-12 10:40:10 +000035
Bob Liu2b4b2482011-06-27 16:18:06 -070036 /* the mapping mustn't extend beyond the EOF */
37 lpages = (len + PAGE_SIZE - 1) >> PAGE_SHIFT;
David Howellsda4458b2009-02-12 10:40:10 +000038 isize = i_size_read(inode);
39 offset = pgoff << PAGE_SHIFT;
Bob Liu2b4b2482011-06-27 16:18:06 -070040
41 maxpages = (isize + PAGE_SIZE - 1) >> PAGE_SHIFT;
42 if ((pgoff >= maxpages) || (maxpages - pgoff < lpages))
David Howellsda4458b2009-02-12 10:40:10 +000043 return (unsigned long) -EINVAL;
44
Artem Bityutskiy4991e722011-12-28 17:08:03 +020045 if (addr != 0)
46 return (unsigned long) -EINVAL;
David Howellsda4458b2009-02-12 10:40:10 +000047
Artem Bityutskiy4991e722011-12-28 17:08:03 +020048 if (len > mtd->size || pgoff >= (mtd->size >> PAGE_SHIFT))
49 return (unsigned long) -EINVAL;
David Howellsda4458b2009-02-12 10:40:10 +000050
Artem Bityutskiy4991e722011-12-28 17:08:03 +020051 offset += ROMFS_I(inode)->i_dataoffset;
Greg Ungerere4ba4fc2013-04-02 14:25:33 +100052 if (offset >= mtd->size)
Artem Bityutskiy4991e722011-12-28 17:08:03 +020053 return (unsigned long) -EINVAL;
Greg Ungerere4ba4fc2013-04-02 14:25:33 +100054 /* the mapping mustn't extend beyond the EOF */
55 if ((offset + len) > mtd->size)
56 len = mtd->size - offset;
David Howellsda4458b2009-02-12 10:40:10 +000057
Artem Bityutskiy4991e722011-12-28 17:08:03 +020058 ret = mtd_get_unmapped_area(mtd, len, offset, flags);
59 if (ret == -EOPNOTSUPP)
60 ret = -ENOSYS;
61 return (unsigned long) ret;
David Howellsda4458b2009-02-12 10:40:10 +000062}
63
64/*
65 * permit a R/O mapping to be made directly through onto an MTD device if
66 * possible
67 */
68static int romfs_mmap(struct file *file, struct vm_area_struct *vma)
69{
70 return vma->vm_flags & (VM_SHARED | VM_MAYSHARE) ? 0 : -ENOSYS;
71}
72
Christoph Hellwigb4caecd2015-01-14 10:42:32 +010073static unsigned romfs_mmap_capabilities(struct file *file)
74{
75 struct mtd_info *mtd = file_inode(file)->i_sb->s_mtd;
76
77 if (!mtd)
78 return NOMMU_MAP_COPY;
79 return mtd_mmap_capabilities(mtd);
80}
81
David Howellsda4458b2009-02-12 10:40:10 +000082const struct file_operations romfs_ro_fops = {
83 .llseek = generic_file_llseek,
Al Viroaad4f8b2014-04-02 14:33:16 -040084 .read_iter = generic_file_read_iter,
David Howellsda4458b2009-02-12 10:40:10 +000085 .splice_read = generic_file_splice_read,
86 .mmap = romfs_mmap,
87 .get_unmapped_area = romfs_get_unmapped_area,
Christoph Hellwigb4caecd2015-01-14 10:42:32 +010088 .mmap_capabilities = romfs_mmap_capabilities,
David Howellsda4458b2009-02-12 10:40:10 +000089};