| /* |
| * 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; |
| BUG_ON(!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 int sdcardfs_page_mkwrite(struct vm_area_struct *vma, |
| struct vm_fault *vmf) |
| { |
| int err = 0; |
| 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; |
| BUG_ON(!lower_vm_ops); |
| if (!lower_vm_ops->page_mkwrite) |
| goto out; |
| |
| lower_file = sdcardfs_lower_file(file); |
| /* |
| * XXX: vm_ops->page_mkwrite 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_page_mkwrite 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 |
| * ->page_mkwrite to take an explicit file pointer. |
| */ |
| lower_vma.vm_file = lower_file; |
| err = lower_vm_ops->page_mkwrite(&lower_vma, vmf); |
| out: |
| return err; |
| } |
| |
| static ssize_t sdcardfs_direct_IO(struct kiocb *iocb, struct iov_iter *iter) |
| { |
| /* |
| * This function should never be called directly. We need it |
| * to exist, to get past a check in open_check_o_direct(), |
| * which is called from do_last(). |
| */ |
| return -EINVAL; |
| } |
| |
| const struct address_space_operations sdcardfs_aops = { |
| .direct_IO = sdcardfs_direct_IO, |
| }; |
| |
| const struct vm_operations_struct sdcardfs_vm_ops = { |
| .fault = sdcardfs_fault, |
| .page_mkwrite = sdcardfs_page_mkwrite, |
| }; |