blob: e21f64675a808caa33659bbdb46f2ba44ca8690c [file] [log] [blame]
* fs/sdcardfs/mmap.c
* Copyright (c) 2013 Samsung Electronics Co. Ltd
* Authors: Daeho Jeong, Woojoong Lee, Seunghwan Hyun,
* Sunghwan Yun, Sungjong Seo
* This program has been developed as a stackable file system based on
* the WrapFS which written by
* Copyright (c) 1998-2011 Erez Zadok
* Copyright (c) 2009 Shrikar Archak
* Copyright (c) 2003-2011 Stony Brook University
* Copyright (c) 2003-2011 The Research Foundation of SUNY
* This file is dual licensed. It may be redistributed and/or modified
* under the terms of the Apache 2.0 License OR version 2 of the GNU
* General Public License.
#include "sdcardfs.h"
static int sdcardfs_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
int err;
struct file *file, *lower_file;
const struct vm_operations_struct *lower_vm_ops;
struct vm_area_struct lower_vma;
memcpy(&lower_vma, vma, sizeof(struct vm_area_struct));
file = lower_vma.vm_file;
lower_vm_ops = SDCARDFS_F(file)->lower_vm_ops;
lower_file = sdcardfs_lower_file(file);
* XXX: vm_ops->fault may be called in parallel. Because we have to
* resort to temporarily changing the vma->vm_file to point to the
* lower file, a concurrent invocation of sdcardfs_fault could see a
* different value. In this workaround, we keep a different copy of
* the vma structure in our stack, so we never expose a different
* value of the vma->vm_file called to us, even temporarily. A
* better fix would be to change the calling semantics of ->fault to
* take an explicit file pointer.
lower_vma.vm_file = lower_file;
err = lower_vm_ops->fault(&lower_vma, vmf);
return err;
static ssize_t sdcardfs_direct_IO(struct kiocb *iocb,
struct iov_iter *iter, loff_t pos)
* This function returns zero on purpose in order to support direct IO.
* __dentry_open checks a_ops->direct_IO and returns EINVAL if it is null.
* However, this function won't be called by certain file operations
* including generic fs functions. * reads and writes are delivered to
* the lower file systems and the direct IOs will be handled by them.
* NOTE: exceptionally, on the recent kernels (since Linux 3.8.x),
* swap_writepage invokes this function directly.
printk(KERN_INFO "%s, operation is not supported\n", __func__);
return 0;
* XXX: the default address_space_ops for sdcardfs is empty. We cannot set
* our inode->i_mapping->a_ops to NULL because too many code paths expect
* the a_ops vector to be non-NULL.
const struct address_space_operations sdcardfs_aops = {
/* empty on purpose */
.direct_IO = sdcardfs_direct_IO,
const struct vm_operations_struct sdcardfs_vm_ops = {
.fault = sdcardfs_fault,