| /* NOMMU mmap support for RomFS on MTD devices |
| * |
| * Copyright © 2007 Red Hat, Inc. All Rights Reserved. |
| * Written by David Howells (dhowells@redhat.com) |
| * |
| * This program is free software; you can redistribute it and/or |
| * modify it under the terms of the GNU General Public License |
| * as published by the Free Software Foundation; either version |
| * 2 of the License, or (at your option) any later version. |
| */ |
| |
| #include <linux/mm.h> |
| #include <linux/mtd/super.h> |
| #include "internal.h" |
| |
| /* |
| * try to determine where a shared mapping can be made |
| * - only supported for NOMMU at the moment (MMU can't doesn't copy private |
| * mappings) |
| * - attempts to map through to the underlying MTD device |
| */ |
| static unsigned long romfs_get_unmapped_area(struct file *file, |
| unsigned long addr, |
| unsigned long len, |
| unsigned long pgoff, |
| unsigned long flags) |
| { |
| struct inode *inode = file->f_mapping->host; |
| struct mtd_info *mtd = inode->i_sb->s_mtd; |
| unsigned long isize, offset, maxpages, lpages; |
| int ret; |
| |
| if (!mtd) |
| return (unsigned long) -ENOSYS; |
| |
| /* the mapping mustn't extend beyond the EOF */ |
| lpages = (len + PAGE_SIZE - 1) >> PAGE_SHIFT; |
| isize = i_size_read(inode); |
| offset = pgoff << PAGE_SHIFT; |
| |
| maxpages = (isize + PAGE_SIZE - 1) >> PAGE_SHIFT; |
| if ((pgoff >= maxpages) || (maxpages - pgoff < lpages)) |
| return (unsigned long) -EINVAL; |
| |
| if (addr != 0) |
| return (unsigned long) -EINVAL; |
| |
| if (len > mtd->size || pgoff >= (mtd->size >> PAGE_SHIFT)) |
| return (unsigned long) -EINVAL; |
| |
| offset += ROMFS_I(inode)->i_dataoffset; |
| if (offset >= mtd->size) |
| return (unsigned long) -EINVAL; |
| /* the mapping mustn't extend beyond the EOF */ |
| if ((offset + len) > mtd->size) |
| len = mtd->size - offset; |
| |
| ret = mtd_get_unmapped_area(mtd, len, offset, flags); |
| if (ret == -EOPNOTSUPP) |
| ret = -ENOSYS; |
| return (unsigned long) ret; |
| } |
| |
| /* |
| * permit a R/O mapping to be made directly through onto an MTD device if |
| * possible |
| */ |
| static int romfs_mmap(struct file *file, struct vm_area_struct *vma) |
| { |
| return vma->vm_flags & (VM_SHARED | VM_MAYSHARE) ? 0 : -ENOSYS; |
| } |
| |
| static unsigned romfs_mmap_capabilities(struct file *file) |
| { |
| struct mtd_info *mtd = file_inode(file)->i_sb->s_mtd; |
| |
| if (!mtd) |
| return NOMMU_MAP_COPY; |
| return mtd_mmap_capabilities(mtd); |
| } |
| |
| const struct file_operations romfs_ro_fops = { |
| .llseek = generic_file_llseek, |
| .read_iter = generic_file_read_iter, |
| .splice_read = generic_file_splice_read, |
| .mmap = romfs_mmap, |
| .get_unmapped_area = romfs_get_unmapped_area, |
| .mmap_capabilities = romfs_mmap_capabilities, |
| }; |