- 根目录:
- fs
- sdcardfs
- file.c
/*
* fs/sdcardfs/file.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"
#ifdef CONFIG_SDCARD_FS_FADV_NOACTIVE
#include <linux/backing-dev.h>
#endif
static ssize_t sdcardfs_read(struct file *file, char __user *buf,
size_t count, loff_t *ppos)
{
int err;
struct file *lower_file;
struct dentry *dentry = file->f_path.dentry;
#ifdef CONFIG_SDCARD_FS_FADV_NOACTIVE
struct backing_dev_info *bdi;
#endif
lower_file = sdcardfs_lower_file(file);
#ifdef CONFIG_SDCARD_FS_FADV_NOACTIVE
if (file->f_mode & FMODE_NOACTIVE) {
if (!(lower_file->f_mode & FMODE_NOACTIVE)) {
bdi = lower_file->f_mapping->backing_dev_info;
lower_file->f_ra.ra_pages = bdi->ra_pages * 2;
spin_lock(&lower_file->f_lock);
lower_file->f_mode |= FMODE_NOACTIVE;
spin_unlock(&lower_file->f_lock);
}
}
#endif
err = vfs_read(lower_file, buf, count, ppos);
/* update our inode atime upon a successful lower read */
if (err >= 0)
fsstack_copy_attr_atime(dentry->d_inode,
file_inode(lower_file));
return err;
}
static ssize_t sdcardfs_write(struct file *file, const char __user *buf,
size_t count, loff_t *ppos)
{
int err;
struct file *lower_file;
struct dentry *dentry = file->f_path.dentry;
/* check disk space */
if (!check_min_free_space(dentry, count, 0)) {
printk(KERN_INFO "No minimum free space.\n");
return -ENOSPC;
}
lower_file = sdcardfs_lower_file(file);
err = vfs_write(lower_file, buf, count, ppos);
/* update our inode times+sizes upon a successful lower write */
if (err >= 0) {
fsstack_copy_inode_size(dentry->d_inode,
file_inode(lower_file));
fsstack_copy_attr_times(dentry->d_inode,
file_inode(lower_file));
}
return err;
}
static int sdcardfs_readdir(struct file *file, struct dir_context *ctx)
{
int err;
struct file *lower_file = NULL;
struct dentry *dentry = file->f_path.dentry;
lower_file = sdcardfs_lower_file(file);
lower_file->f_pos = file->f_pos;
err = iterate_dir(lower_file, ctx);
file->f_pos = lower_file->f_pos;
if (err >= 0) /* copy the atime */
fsstack_copy_attr_atime(dentry->d_inode,
file_inode(lower_file));
return err;
}
static long sdcardfs_unlocked_ioctl(struct file *file, unsigned int cmd,
unsigned long arg)
{
long err = -ENOTTY;
struct file *lower_file;
lower_file = sdcardfs_lower_file(file);
/* XXX: use vfs_ioctl if/when VFS exports it */
if (!lower_file || !lower_file->f_op)
goto out;
if (lower_file->f_op->unlocked_ioctl)
err = lower_file->f_op->unlocked_ioctl(lower_file, cmd, arg);
out:
return err;
}
#ifdef CONFIG_COMPAT
static long sdcardfs_compat_ioctl(struct file *file, unsigned int cmd,
unsigned long arg)
{
long err = -ENOTTY;
struct file *lower_file;
lower_file = sdcardfs_lower_file(file);
/* XXX: use vfs_ioctl if/when VFS exports it */
if (!lower_file || !lower_file->f_op)
goto out;
if (lower_file->f_op->compat_ioctl)
err = lower_file->f_op->compat_ioctl(lower_file, cmd, arg);
out:
return err;
}
#endif
static int sdcardfs_mmap(struct file *file, struct vm_area_struct *vma)
{
int err = 0;
bool willwrite;
struct file *lower_file;
const struct vm_operations_struct *saved_vm_ops = NULL;
/* this might be deferred to mmap's writepage */
willwrite = ((vma->vm_flags | VM_SHARED | VM_WRITE) == vma->vm_flags);
/*
* File systems which do not implement ->writepage may use
* generic_file_readonly_mmap as their ->mmap op. If you call
* generic_file_readonly_mmap with VM_WRITE, you'd get an -EINVAL.
* But we cannot call the lower ->mmap op, so we can't tell that
* writeable mappings won't work. Therefore, our only choice is to
* check if the lower file system supports the ->writepage, and if
* not, return EINVAL (the same error that
* generic_file_readonly_mmap returns in that case).
*/
lower_file = sdcardfs_lower_file(file);
if (willwrite && !lower_file->f_mapping->a_ops->writepage) {
err = -EINVAL;
printk(KERN_ERR "sdcardfs: lower file system does not "
"support writeable mmap\n");
goto out;
}
/*
* find and save lower vm_ops.
*
* XXX: the VFS should have a cleaner way of finding the lower vm_ops
*/
if (!SDCARDFS_F(file)->lower_vm_ops) {
err = lower_file->f_op->mmap(lower_file, vma);
if (err) {
printk(KERN_ERR "sdcardfs: lower mmap failed %d\n", err);
goto out;
}
saved_vm_ops = vma->vm_ops; /* save: came from lower ->mmap */
err = do_munmap(current->mm, vma->vm_start,
vma->vm_end - vma->vm_start);
if (err) {
printk(KERN_ERR "sdcardfs: do_munmap failed %d\n", err);
goto out;
}
}
/*
* Next 3 lines are all I need from generic_file_mmap. I definitely
* don't want its test for ->readpage which returns -ENOEXEC.
*/
file_accessed(file);
vma->vm_ops = &sdcardfs_vm_ops;
file->f_mapping->a_ops = &sdcardfs_aops; /* set our aops */
if (!SDCARDFS_F(file)->lower_vm_ops) /* save for our ->fault */
SDCARDFS_F(file)->lower_vm_ops = saved_vm_ops;
out:
return err;
}
static int sdcardfs_open(struct inode *inode, struct file *file)
{
int err = 0;
struct file *lower_file = NULL;
struct path lower_path;
struct dentry *dentry = file->f_path.dentry;
struct dentry *parent = dget_parent(dentry);
struct sdcardfs_sb_info *sbi = SDCARDFS_SB(dentry->d_sb);
const struct cred *saved_cred = NULL;
/* don't open unhashed/deleted files */
if (d_unhashed(dentry)) {
err = -ENOENT;
goto out_err;
}
if(!check_caller_access_to_name(parent->d_inode, dentry->d_name.name)) {
printk(KERN_INFO "%s: need to check the caller's gid in packages.list\n"
" dentry: %s, task:%s\n",
__func__, dentry->d_name.name, current->comm);
err = -EACCES;
goto out_err;
}
/* save current_cred and override it */
OVERRIDE_CRED(sbi, saved_cred);
file->private_data =
kzalloc(sizeof(struct sdcardfs_file_info), GFP_KERNEL);
if (!SDCARDFS_F(file)) {
err = -ENOMEM;
goto out_revert_cred;
}
/* open lower object and link sdcardfs's file struct to lower's */
sdcardfs_get_lower_path(file->f_path.dentry, &lower_path);
lower_file = dentry_open(&lower_path, file->f_flags, current_cred());
path_put(&lower_path);
if (IS_ERR(lower_file)) {
err = PTR_ERR(lower_file);
lower_file = sdcardfs_lower_file(file);
if (lower_file) {
sdcardfs_set_lower_file(file, NULL);
fput(lower_file); /* fput calls dput for lower_dentry */
}
} else {
sdcardfs_set_lower_file(file, lower_file);
}
if (err)
kfree(SDCARDFS_F(file));
else {
sdcardfs_copy_and_fix_attrs(inode, sdcardfs_lower_inode(inode));
}
out_revert_cred:
REVERT_CRED(saved_cred);
out_err:
dput(parent);
return err;
}
static int sdcardfs_flush(struct file *file, fl_owner_t id)
{
int err = 0;
struct file *lower_file = NULL;
lower_file = sdcardfs_lower_file(file);
if (lower_file && lower_file->f_op && lower_file->f_op->flush) {
filemap_write_and_wait(file->f_mapping);
err = lower_file->f_op->flush(lower_file, id);
}
return err;
}
/* release all lower object references & free the file info structure */
static int sdcardfs_file_release(struct inode *inode, struct file *file)
{
struct file *lower_file;
lower_file = sdcardfs_lower_file(file);
if (lower_file) {
sdcardfs_set_lower_file(file, NULL);
fput(lower_file);
}
kfree(SDCARDFS_F(file));
return 0;
}
static int sdcardfs_fsync(struct file *file, loff_t start, loff_t end,
int datasync)
{
int err;
struct file *lower_file;
struct path lower_path;
struct dentry *dentry = file->f_path.dentry;
err = generic_file_fsync(file, start, end, datasync);
if (err)
goto out;
lower_file = sdcardfs_lower_file(file);
sdcardfs_get_lower_path(dentry, &lower_path);
err = vfs_fsync_range(lower_file, start, end, datasync);
sdcardfs_put_lower_path(dentry, &lower_path);
out:
return err;
}
static int sdcardfs_fasync(int fd, struct file *file, int flag)
{
int err = 0;
struct file *lower_file = NULL;
lower_file = sdcardfs_lower_file(file);
if (lower_file->f_op && lower_file->f_op->fasync)
err = lower_file->f_op->fasync(fd, lower_file, flag);
return err;
}
const struct file_operations sdcardfs_main_fops = {
.llseek = generic_file_llseek,
.read = sdcardfs_read,
.write = sdcardfs_write,
.unlocked_ioctl = sdcardfs_unlocked_ioctl,
#ifdef CONFIG_COMPAT
.compat_ioctl = sdcardfs_compat_ioctl,
#endif
.mmap = sdcardfs_mmap,
.open = sdcardfs_open,
.flush = sdcardfs_flush,
.release = sdcardfs_file_release,
.fsync = sdcardfs_fsync,
.fasync = sdcardfs_fasync,
};
/* trimmed directory options */
const struct file_operations sdcardfs_dir_fops = {
.llseek = generic_file_llseek,
.read = generic_read_dir,
.iterate = sdcardfs_readdir,
.unlocked_ioctl = sdcardfs_unlocked_ioctl,
#ifdef CONFIG_COMPAT
.compat_ioctl = sdcardfs_compat_ioctl,
#endif
.open = sdcardfs_open,
.release = sdcardfs_file_release,
.flush = sdcardfs_flush,
.fsync = sdcardfs_fsync,
.fasync = sdcardfs_fasync,
};