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/*
* Copyright (c) 2015, The Linux Foundation. All rights reserved.
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 and
* only version 2 as published by the Free Software Foundation.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
*/
#include "fuse_shortcircuit.h"
#include <linux/aio.h>
#include <linux/fs_stack.h>
void fuse_setup_shortcircuit(struct fuse_conn *fc, struct fuse_req *req)
{
int daemon_fd;
struct file *rw_lower_file = NULL;
struct fuse_open_out *open_out;
int open_out_index;
req->private_lower_rw_file = NULL;
if (!(fc->shortcircuit_io))
return;
if ((req->in.h.opcode != FUSE_OPEN) &&
(req->in.h.opcode != FUSE_CREATE))
return;
open_out_index = req->in.numargs - 1;
BUG_ON(open_out_index != 0 && open_out_index != 1);
BUG_ON(req->out.args[open_out_index].size != sizeof(*open_out));
open_out = req->out.args[open_out_index].value;
daemon_fd = (int)open_out->lower_fd;
if (daemon_fd < 0)
return;
rw_lower_file = fget_raw(daemon_fd);
if (!rw_lower_file)
return;
req->private_lower_rw_file = rw_lower_file;
}
static ssize_t fuse_shortcircuit_read_write_iter(struct kiocb *iocb,
struct iov_iter *iter,
int do_write)
{
ssize_t ret_val;
struct fuse_file *ff;
struct file *fuse_file, *lower_file;
struct inode *fuse_inode, *lower_inode;
ff = iocb->ki_filp->private_data;
fuse_file = iocb->ki_filp;
lower_file = ff->rw_lower_file;
/* lock lower file to prevent it from being released */
get_file(lower_file);
iocb->ki_filp = lower_file;
fuse_inode = fuse_file->f_path.dentry->d_inode;
lower_inode = file_inode(lower_file);
if (do_write) {
if (!lower_file->f_op->write_iter)
return -EIO;
ret_val = lower_file->f_op->write_iter(iocb, iter);
if (ret_val >= 0 || ret_val == -EIOCBQUEUED) {
fsstack_copy_inode_size(fuse_inode, lower_inode);
fsstack_copy_attr_times(fuse_inode, lower_inode);
}
} else {
if (!lower_file->f_op->read_iter)
return -EIO;
ret_val = lower_file->f_op->read_iter(iocb, iter);
if (ret_val >= 0 || ret_val == -EIOCBQUEUED)
fsstack_copy_attr_atime(fuse_inode, lower_inode);
}
iocb->ki_filp = fuse_file;
fput(lower_file);
/* unlock lower file */
return ret_val;
}
ssize_t fuse_shortcircuit_read_iter(struct kiocb *iocb, struct iov_iter *to)
{
return fuse_shortcircuit_read_write_iter(iocb, to, 0);
}
ssize_t fuse_shortcircuit_write_iter(struct kiocb *iocb, struct iov_iter *from)
{
return fuse_shortcircuit_read_write_iter(iocb, from, 1);
}
void fuse_shortcircuit_release(struct fuse_file *ff)
{
if (!(ff->rw_lower_file))
return;
/* Release the lower file. */
fput(ff->rw_lower_file);
ff->rw_lower_file = NULL;
}
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