76 lines
2.1 KiB
C
76 lines
2.1 KiB
C
/* 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;
|
|
|
|
if (!mtd)
|
|
goto cant_map_directly;
|
|
|
|
isize = i_size_read(inode);
|
|
offset = pgoff << PAGE_SHIFT;
|
|
if (offset > isize || len > isize || offset > isize - len)
|
|
return (unsigned long) -EINVAL;
|
|
|
|
/* we need to call down to the MTD layer to do the actual mapping */
|
|
if (mtd->get_unmapped_area) {
|
|
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 - len)
|
|
return (unsigned long) -EINVAL;
|
|
|
|
return mtd->get_unmapped_area(mtd, len, offset, flags);
|
|
}
|
|
|
|
cant_map_directly:
|
|
return (unsigned long) -ENOSYS;
|
|
}
|
|
|
|
/*
|
|
* 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;
|
|
}
|
|
|
|
const struct file_operations romfs_ro_fops = {
|
|
.llseek = generic_file_llseek,
|
|
.read = do_sync_read,
|
|
.aio_read = generic_file_aio_read,
|
|
.splice_read = generic_file_splice_read,
|
|
.mmap = romfs_mmap,
|
|
.get_unmapped_area = romfs_get_unmapped_area,
|
|
};
|