projects / linux-2.6-block.git / blame
| Commit | Line | Data |
|---|---|---|
| da4458bd DH |
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 | */ | |
| 22 | static 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; | |
| 2b4b2482 | 30 | unsigned long isize, offset, maxpages, lpages; |
| da4458bd DH |
31 | |
| 32 | if (!mtd) | |
| 33 | goto cant_map_directly; | |
| 34 | ||
| 2b4b2482 BL |
35 | /* the mapping mustn't extend beyond the EOF */ |
| 36 | lpages = (len + PAGE_SIZE - 1) >> PAGE_SHIFT; | |
| da4458bd DH |
37 | isize = i_size_read(inode); |
| 38 | offset = pgoff << PAGE_SHIFT; | |
| 2b4b2482 BL |
39 | |
| 40 | maxpages = (isize + PAGE_SIZE - 1) >> PAGE_SHIFT; | |
| 41 | if ((pgoff >= maxpages) || (maxpages - pgoff < lpages)) | |
| da4458bd DH |
42 | return (unsigned long) -EINVAL; |
| 43 | ||
| 44 | /* we need to call down to the MTD layer to do the actual mapping */ | |
| 45 | if (mtd->get_unmapped_area) { | |
| 46 | if (addr != 0) | |
| 47 | return (unsigned long) -EINVAL; | |
| 48 | ||
| 49 | if (len > mtd->size || pgoff >= (mtd->size >> PAGE_SHIFT)) | |
| 50 | return (unsigned long) -EINVAL; | |
| 51 | ||
| 52 | offset += ROMFS_I(inode)->i_dataoffset; | |
| 53 | if (offset > mtd->size - len) | |
| 54 | return (unsigned long) -EINVAL; | |
| 55 | ||
| 56 | return mtd->get_unmapped_area(mtd, len, offset, flags); | |
| 57 | } | |
| 58 | ||
| 59 | cant_map_directly: | |
| 60 | return (unsigned long) -ENOSYS; | |
| 61 | } | |
| 62 | ||
| 63 | /* | |
| 64 | * permit a R/O mapping to be made directly through onto an MTD device if | |
| 65 | * possible | |
| 66 | */ | |
| 67 | static int romfs_mmap(struct file *file, struct vm_area_struct *vma) | |
| 68 | { | |
| 69 | return vma->vm_flags & (VM_SHARED | VM_MAYSHARE) ? 0 : -ENOSYS; | |
| 70 | } | |
| 71 | ||
| 72 | const struct file_operations romfs_ro_fops = { | |
| 73 | .llseek = generic_file_llseek, | |
| 74 | .read = do_sync_read, | |
| 75 | .aio_read = generic_file_aio_read, | |
| 76 | .splice_read = generic_file_splice_read, | |
| 77 | .mmap = romfs_mmap, | |
| 78 | .get_unmapped_area = romfs_get_unmapped_area, | |
| 79 | }; |