468 lines
12 KiB
C
468 lines
12 KiB
C
/*
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* fs/sdcardfs/file.c
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*
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* Copyright (c) 2013 Samsung Electronics Co. Ltd
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* Authors: Daeho Jeong, Woojoong Lee, Seunghwan Hyun,
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* Sunghwan Yun, Sungjong Seo
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*
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* This program has been developed as a stackable file system based on
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* the WrapFS which written by
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*
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* Copyright (c) 1998-2011 Erez Zadok
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* Copyright (c) 2009 Shrikar Archak
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* Copyright (c) 2003-2011 Stony Brook University
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* Copyright (c) 2003-2011 The Research Foundation of SUNY
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*
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* This file is dual licensed. It may be redistributed and/or modified
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* under the terms of the Apache 2.0 License OR version 2 of the GNU
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* General Public License.
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*/
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#include "sdcardfs.h"
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#ifdef CONFIG_SDCARD_FS_FADV_NOACTIVE
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#include <linux/backing-dev.h>
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#endif
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static ssize_t sdcardfs_read(struct file *file, char __user *buf,
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size_t count, loff_t *ppos)
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{
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int err;
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struct file *lower_file;
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struct dentry *dentry = file->f_path.dentry;
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#ifdef CONFIG_SDCARD_FS_FADV_NOACTIVE
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struct backing_dev_info *bdi;
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#endif
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lower_file = sdcardfs_lower_file(file);
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#ifdef CONFIG_SDCARD_FS_FADV_NOACTIVE
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if (file->f_mode & FMODE_NOACTIVE) {
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if (!(lower_file->f_mode & FMODE_NOACTIVE)) {
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bdi = lower_file->f_mapping->backing_dev_info;
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lower_file->f_ra.ra_pages = bdi->ra_pages * 2;
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spin_lock(&lower_file->f_lock);
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lower_file->f_mode |= FMODE_NOACTIVE;
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spin_unlock(&lower_file->f_lock);
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}
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}
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#endif
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err = vfs_read(lower_file, buf, count, ppos);
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/* update our inode atime upon a successful lower read */
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if (err >= 0)
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fsstack_copy_attr_atime(d_inode(dentry),
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file_inode(lower_file));
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return err;
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}
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static ssize_t sdcardfs_write(struct file *file, const char __user *buf,
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size_t count, loff_t *ppos)
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{
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int err;
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struct file *lower_file;
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struct dentry *dentry = file->f_path.dentry;
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struct inode *inode = d_inode(dentry);
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/* check disk space */
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if (!check_min_free_space(dentry, count, 0)) {
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pr_err("No minimum free space.\n");
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return -ENOSPC;
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}
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lower_file = sdcardfs_lower_file(file);
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err = vfs_write(lower_file, buf, count, ppos);
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/* update our inode times+sizes upon a successful lower write */
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if (err >= 0) {
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if (sizeof(loff_t) > sizeof(long))
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inode_lock(inode);
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fsstack_copy_inode_size(inode, file_inode(lower_file));
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fsstack_copy_attr_times(inode, file_inode(lower_file));
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if (sizeof(loff_t) > sizeof(long))
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inode_unlock(inode);
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}
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return err;
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}
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static int sdcardfs_readdir(struct file *file, struct dir_context *ctx)
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{
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int err;
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struct file *lower_file = NULL;
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struct dentry *dentry = file->f_path.dentry;
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lower_file = sdcardfs_lower_file(file);
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lower_file->f_pos = file->f_pos;
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err = iterate_dir(lower_file, ctx);
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file->f_pos = lower_file->f_pos;
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if (err >= 0) /* copy the atime */
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fsstack_copy_attr_atime(d_inode(dentry),
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file_inode(lower_file));
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return err;
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}
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static long sdcardfs_unlocked_ioctl(struct file *file, unsigned int cmd,
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unsigned long arg)
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{
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long err = -ENOTTY;
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struct file *lower_file;
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const struct cred *saved_cred = NULL;
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struct dentry *dentry = file->f_path.dentry;
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struct sdcardfs_sb_info *sbi = SDCARDFS_SB(dentry->d_sb);
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lower_file = sdcardfs_lower_file(file);
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/* XXX: use vfs_ioctl if/when VFS exports it */
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if (!lower_file || !lower_file->f_op)
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goto out;
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/* save current_cred and override it */
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saved_cred = override_fsids(sbi, SDCARDFS_I(file_inode(file))->data);
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if (!saved_cred) {
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err = -ENOMEM;
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goto out;
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}
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if (lower_file->f_op->unlocked_ioctl)
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err = lower_file->f_op->unlocked_ioctl(lower_file, cmd, arg);
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/* some ioctls can change inode attributes (EXT2_IOC_SETFLAGS) */
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if (!err)
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sdcardfs_copy_and_fix_attrs(file_inode(file),
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file_inode(lower_file));
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revert_fsids(saved_cred);
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out:
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return err;
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}
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#ifdef CONFIG_COMPAT
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static long sdcardfs_compat_ioctl(struct file *file, unsigned int cmd,
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unsigned long arg)
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{
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long err = -ENOTTY;
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struct file *lower_file;
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const struct cred *saved_cred = NULL;
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struct dentry *dentry = file->f_path.dentry;
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struct sdcardfs_sb_info *sbi = SDCARDFS_SB(dentry->d_sb);
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lower_file = sdcardfs_lower_file(file);
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/* XXX: use vfs_ioctl if/when VFS exports it */
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if (!lower_file || !lower_file->f_op)
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goto out;
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/* save current_cred and override it */
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saved_cred = override_fsids(sbi, SDCARDFS_I(file_inode(file))->data);
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if (!saved_cred) {
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err = -ENOMEM;
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goto out;
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}
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if (lower_file->f_op->compat_ioctl)
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err = lower_file->f_op->compat_ioctl(lower_file, cmd, arg);
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revert_fsids(saved_cred);
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out:
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return err;
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}
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#endif
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static int sdcardfs_mmap(struct file *file, struct vm_area_struct *vma)
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{
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int err = 0;
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bool willwrite;
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struct file *lower_file;
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const struct vm_operations_struct *saved_vm_ops = NULL;
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/* this might be deferred to mmap's writepage */
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willwrite = ((vma->vm_flags | VM_SHARED | VM_WRITE) == vma->vm_flags);
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/*
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* File systems which do not implement ->writepage may use
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* generic_file_readonly_mmap as their ->mmap op. If you call
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* generic_file_readonly_mmap with VM_WRITE, you'd get an -EINVAL.
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* But we cannot call the lower ->mmap op, so we can't tell that
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* writeable mappings won't work. Therefore, our only choice is to
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* check if the lower file system supports the ->writepage, and if
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* not, return EINVAL (the same error that
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* generic_file_readonly_mmap returns in that case).
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*/
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lower_file = sdcardfs_lower_file(file);
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if (willwrite && !lower_file->f_mapping->a_ops->writepage) {
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err = -EINVAL;
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pr_err("sdcardfs: lower file system does not support writeable mmap\n");
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goto out;
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}
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/*
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* find and save lower vm_ops.
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*
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* XXX: the VFS should have a cleaner way of finding the lower vm_ops
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*/
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if (!SDCARDFS_F(file)->lower_vm_ops) {
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err = lower_file->f_op->mmap(lower_file, vma);
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if (err) {
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pr_err("sdcardfs: lower mmap failed %d\n", err);
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goto out;
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}
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saved_vm_ops = vma->vm_ops; /* save: came from lower ->mmap */
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}
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/*
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* Next 3 lines are all I need from generic_file_mmap. I definitely
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* don't want its test for ->readpage which returns -ENOEXEC.
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*/
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file_accessed(file);
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vma->vm_ops = &sdcardfs_vm_ops;
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file->f_mapping->a_ops = &sdcardfs_aops; /* set our aops */
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if (!SDCARDFS_F(file)->lower_vm_ops) /* save for our ->fault */
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SDCARDFS_F(file)->lower_vm_ops = saved_vm_ops;
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vma->vm_private_data = file;
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get_file(lower_file);
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vma->vm_file = lower_file;
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out:
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return err;
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}
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static int sdcardfs_open(struct inode *inode, struct file *file)
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{
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int err = 0;
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struct file *lower_file = NULL;
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struct path lower_path;
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struct dentry *dentry = file->f_path.dentry;
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struct dentry *parent = dget_parent(dentry);
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struct sdcardfs_sb_info *sbi = SDCARDFS_SB(dentry->d_sb);
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const struct cred *saved_cred = NULL;
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/* don't open unhashed/deleted files */
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if (d_unhashed(dentry)) {
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err = -ENOENT;
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goto out_err;
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}
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if (!check_caller_access_to_name(d_inode(parent), &dentry->d_name)) {
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err = -EACCES;
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goto out_err;
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}
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/* save current_cred and override it */
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saved_cred = override_fsids(sbi, SDCARDFS_I(inode)->data);
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if (!saved_cred) {
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err = -ENOMEM;
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goto out_err;
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}
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file->private_data =
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kzalloc(sizeof(struct sdcardfs_file_info), GFP_KERNEL);
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if (!SDCARDFS_F(file)) {
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err = -ENOMEM;
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goto out_revert_cred;
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}
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/* open lower object and link sdcardfs's file struct to lower's */
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sdcardfs_get_lower_path(file->f_path.dentry, &lower_path);
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lower_file = dentry_open(&lower_path, file->f_flags, current_cred());
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path_put(&lower_path);
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if (IS_ERR(lower_file)) {
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err = PTR_ERR(lower_file);
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lower_file = sdcardfs_lower_file(file);
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if (lower_file) {
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sdcardfs_set_lower_file(file, NULL);
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fput(lower_file); /* fput calls dput for lower_dentry */
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}
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} else {
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sdcardfs_set_lower_file(file, lower_file);
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}
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if (err)
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kfree(SDCARDFS_F(file));
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else
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sdcardfs_copy_and_fix_attrs(inode, sdcardfs_lower_inode(inode));
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out_revert_cred:
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revert_fsids(saved_cred);
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out_err:
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dput(parent);
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return err;
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}
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static int sdcardfs_flush(struct file *file, fl_owner_t id)
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{
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int err = 0;
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struct file *lower_file = NULL;
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lower_file = sdcardfs_lower_file(file);
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if (lower_file && lower_file->f_op && lower_file->f_op->flush) {
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filemap_write_and_wait(file->f_mapping);
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err = lower_file->f_op->flush(lower_file, id);
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}
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return err;
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}
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/* release all lower object references & free the file info structure */
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static int sdcardfs_file_release(struct inode *inode, struct file *file)
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{
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struct file *lower_file;
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lower_file = sdcardfs_lower_file(file);
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if (lower_file) {
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sdcardfs_set_lower_file(file, NULL);
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fput(lower_file);
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}
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kfree(SDCARDFS_F(file));
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return 0;
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}
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static int sdcardfs_fsync(struct file *file, loff_t start, loff_t end,
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int datasync)
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{
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int err;
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struct file *lower_file;
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struct path lower_path;
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struct dentry *dentry = file->f_path.dentry;
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err = __generic_file_fsync(file, start, end, datasync);
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if (err)
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goto out;
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lower_file = sdcardfs_lower_file(file);
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sdcardfs_get_lower_path(dentry, &lower_path);
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err = vfs_fsync_range(lower_file, start, end, datasync);
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sdcardfs_put_lower_path(dentry, &lower_path);
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out:
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return err;
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}
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static int sdcardfs_fasync(int fd, struct file *file, int flag)
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{
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int err = 0;
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struct file *lower_file = NULL;
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lower_file = sdcardfs_lower_file(file);
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if (lower_file->f_op && lower_file->f_op->fasync)
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err = lower_file->f_op->fasync(fd, lower_file, flag);
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return err;
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}
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/*
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* Sdcardfs cannot use generic_file_llseek as ->llseek, because it would
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* only set the offset of the upper file. So we have to implement our
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* own method to set both the upper and lower file offsets
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* consistently.
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*/
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static loff_t sdcardfs_file_llseek(struct file *file, loff_t offset, int whence)
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{
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int err;
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struct file *lower_file;
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err = generic_file_llseek(file, offset, whence);
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if (err < 0)
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goto out;
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lower_file = sdcardfs_lower_file(file);
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err = generic_file_llseek(lower_file, offset, whence);
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out:
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return err;
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}
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/*
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* Sdcardfs read_iter, redirect modified iocb to lower read_iter
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*/
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ssize_t sdcardfs_read_iter(struct kiocb *iocb, struct iov_iter *iter)
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{
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int err;
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struct file *file = iocb->ki_filp, *lower_file;
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lower_file = sdcardfs_lower_file(file);
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if (!lower_file->f_op->read_iter) {
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err = -EINVAL;
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goto out;
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}
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get_file(lower_file); /* prevent lower_file from being released */
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iocb->ki_filp = lower_file;
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err = lower_file->f_op->read_iter(iocb, iter);
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iocb->ki_filp = file;
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fput(lower_file);
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/* update upper inode atime as needed */
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if (err >= 0 || err == -EIOCBQUEUED)
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fsstack_copy_attr_atime(file->f_path.dentry->d_inode,
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file_inode(lower_file));
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out:
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return err;
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}
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/*
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* Sdcardfs write_iter, redirect modified iocb to lower write_iter
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*/
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ssize_t sdcardfs_write_iter(struct kiocb *iocb, struct iov_iter *iter)
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{
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int err;
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struct file *file = iocb->ki_filp, *lower_file;
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struct inode *inode = file->f_path.dentry->d_inode;
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lower_file = sdcardfs_lower_file(file);
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if (!lower_file->f_op->write_iter) {
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err = -EINVAL;
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goto out;
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}
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get_file(lower_file); /* prevent lower_file from being released */
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iocb->ki_filp = lower_file;
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err = lower_file->f_op->write_iter(iocb, iter);
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iocb->ki_filp = file;
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fput(lower_file);
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/* update upper inode times/sizes as needed */
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if (err >= 0 || err == -EIOCBQUEUED) {
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if (sizeof(loff_t) > sizeof(long))
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inode_lock(inode);
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fsstack_copy_inode_size(inode, file_inode(lower_file));
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fsstack_copy_attr_times(inode, file_inode(lower_file));
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if (sizeof(loff_t) > sizeof(long))
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inode_unlock(inode);
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}
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out:
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return err;
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}
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const struct file_operations sdcardfs_main_fops = {
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.llseek = generic_file_llseek,
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.read = sdcardfs_read,
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.write = sdcardfs_write,
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.unlocked_ioctl = sdcardfs_unlocked_ioctl,
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#ifdef CONFIG_COMPAT
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.compat_ioctl = sdcardfs_compat_ioctl,
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#endif
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.mmap = sdcardfs_mmap,
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.open = sdcardfs_open,
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.flush = sdcardfs_flush,
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.release = sdcardfs_file_release,
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.fsync = sdcardfs_fsync,
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.fasync = sdcardfs_fasync,
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.read_iter = sdcardfs_read_iter,
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.write_iter = sdcardfs_write_iter,
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};
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/* trimmed directory options */
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const struct file_operations sdcardfs_dir_fops = {
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.llseek = sdcardfs_file_llseek,
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.read = generic_read_dir,
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.iterate = sdcardfs_readdir,
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.unlocked_ioctl = sdcardfs_unlocked_ioctl,
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#ifdef CONFIG_COMPAT
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.compat_ioctl = sdcardfs_compat_ioctl,
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#endif
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.open = sdcardfs_open,
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.release = sdcardfs_file_release,
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.flush = sdcardfs_flush,
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.fsync = sdcardfs_fsync,
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.fasync = sdcardfs_fasync,
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};
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