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![Pedro Cuadra](/assets/img/avatar_default.png)
This adds support for partial file caching in Coda. Every read, write and mmap informs the userspace cache manager about what part of a file is about to be accessed so that the cache manager can ensure the relevant parts are available before the operation is allowed to proceed. When a read or write operation completes, this is also reported to allow the cache manager to track when partially cached content can be released. If the cache manager does not support partial file caching, or when the entire file has been fetched into the local cache, the cache manager may return an EOPNOTSUPP error to indicate that intent upcalls are no longer necessary until the file is closed. [akpm@linux-foundation.org: little whitespace fixup] Link: http://lkml.kernel.org/r/20190618181301.6960-1-jaharkes@cs.cmu.edu Signed-off-by: Pedro Cuadra <pjcuadra@gmail.com> Signed-off-by: Jan Harkes <jaharkes@cs.cmu.edu> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
442 lines
10 KiB
C
442 lines
10 KiB
C
// SPDX-License-Identifier: GPL-2.0-or-later
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/*
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* An implementation of a loadable kernel mode driver providing
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* multiple kernel/user space bidirectional communications links.
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*
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* Author: Alan Cox <alan@lxorguk.ukuu.org.uk>
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*
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* Adapted to become the Linux 2.0 Coda pseudo device
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* Peter Braam <braam@maths.ox.ac.uk>
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* Michael Callahan <mjc@emmy.smith.edu>
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*
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* Changes for Linux 2.1
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* Copyright (c) 1997 Carnegie-Mellon University
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*/
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#include <linux/module.h>
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#include <linux/errno.h>
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#include <linux/kernel.h>
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#include <linux/major.h>
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#include <linux/time.h>
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#include <linux/sched/signal.h>
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#include <linux/slab.h>
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#include <linux/ioport.h>
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#include <linux/fcntl.h>
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#include <linux/delay.h>
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#include <linux/skbuff.h>
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#include <linux/proc_fs.h>
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#include <linux/vmalloc.h>
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#include <linux/fs.h>
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#include <linux/file.h>
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#include <linux/poll.h>
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#include <linux/init.h>
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#include <linux/list.h>
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#include <linux/mutex.h>
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#include <linux/device.h>
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#include <linux/pid_namespace.h>
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#include <asm/io.h>
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#include <linux/uaccess.h>
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#include <linux/coda.h>
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#include "coda_psdev.h"
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#include "coda_linux.h"
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#include "coda_int.h"
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/* statistics */
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int coda_hard; /* allows signals during upcalls */
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unsigned long coda_timeout = 30; /* .. secs, then signals will dequeue */
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struct venus_comm coda_comms[MAX_CODADEVS];
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static struct class *coda_psdev_class;
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/*
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* Device operations
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*/
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static __poll_t coda_psdev_poll(struct file *file, poll_table * wait)
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{
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struct venus_comm *vcp = (struct venus_comm *) file->private_data;
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__poll_t mask = EPOLLOUT | EPOLLWRNORM;
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poll_wait(file, &vcp->vc_waitq, wait);
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mutex_lock(&vcp->vc_mutex);
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if (!list_empty(&vcp->vc_pending))
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mask |= EPOLLIN | EPOLLRDNORM;
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mutex_unlock(&vcp->vc_mutex);
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return mask;
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}
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static long coda_psdev_ioctl(struct file * filp, unsigned int cmd, unsigned long arg)
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{
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unsigned int data;
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switch(cmd) {
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case CIOC_KERNEL_VERSION:
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data = CODA_KERNEL_VERSION;
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return put_user(data, (int __user *) arg);
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default:
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return -ENOTTY;
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}
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return 0;
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}
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/*
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* Receive a message written by Venus to the psdev
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*/
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static ssize_t coda_psdev_write(struct file *file, const char __user *buf,
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size_t nbytes, loff_t *off)
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{
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struct venus_comm *vcp = (struct venus_comm *) file->private_data;
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struct upc_req *req = NULL;
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struct upc_req *tmp;
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struct list_head *lh;
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struct coda_in_hdr hdr;
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ssize_t retval = 0, count = 0;
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int error;
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/* make sure there is enough to copy out the (opcode, unique) values */
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if (nbytes < (2 * sizeof(u_int32_t)))
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return -EINVAL;
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/* Peek at the opcode, uniquefier */
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if (copy_from_user(&hdr, buf, 2 * sizeof(u_int32_t)))
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return -EFAULT;
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if (DOWNCALL(hdr.opcode)) {
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union outputArgs *dcbuf;
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int size = sizeof(*dcbuf);
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if ( nbytes < sizeof(struct coda_out_hdr) ) {
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pr_warn("coda_downcall opc %d uniq %d, not enough!\n",
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hdr.opcode, hdr.unique);
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count = nbytes;
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goto out;
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}
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if ( nbytes > size ) {
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pr_warn("downcall opc %d, uniq %d, too much!",
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hdr.opcode, hdr.unique);
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nbytes = size;
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}
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dcbuf = kvmalloc(nbytes, GFP_KERNEL);
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if (!dcbuf) {
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retval = -ENOMEM;
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goto out;
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}
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if (copy_from_user(dcbuf, buf, nbytes)) {
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kvfree(dcbuf);
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retval = -EFAULT;
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goto out;
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}
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/* what downcall errors does Venus handle ? */
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error = coda_downcall(vcp, hdr.opcode, dcbuf, nbytes);
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kvfree(dcbuf);
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if (error) {
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pr_warn("%s: coda_downcall error: %d\n",
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__func__, error);
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retval = error;
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goto out;
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}
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count = nbytes;
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goto out;
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}
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/* Look for the message on the processing queue. */
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mutex_lock(&vcp->vc_mutex);
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list_for_each(lh, &vcp->vc_processing) {
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tmp = list_entry(lh, struct upc_req , uc_chain);
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if (tmp->uc_unique == hdr.unique) {
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req = tmp;
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list_del(&req->uc_chain);
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break;
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}
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}
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mutex_unlock(&vcp->vc_mutex);
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if (!req) {
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pr_warn("%s: msg (%d, %d) not found\n",
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__func__, hdr.opcode, hdr.unique);
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retval = -ESRCH;
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goto out;
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}
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/* move data into response buffer. */
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if (req->uc_outSize < nbytes) {
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pr_warn("%s: too much cnt: %d, cnt: %ld, opc: %d, uniq: %d.\n",
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__func__, req->uc_outSize, (long)nbytes,
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hdr.opcode, hdr.unique);
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nbytes = req->uc_outSize; /* don't have more space! */
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}
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if (copy_from_user(req->uc_data, buf, nbytes)) {
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req->uc_flags |= CODA_REQ_ABORT;
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wake_up(&req->uc_sleep);
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retval = -EFAULT;
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goto out;
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}
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/* adjust outsize. is this useful ?? */
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req->uc_outSize = nbytes;
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req->uc_flags |= CODA_REQ_WRITE;
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count = nbytes;
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/* Convert filedescriptor into a file handle */
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if (req->uc_opcode == CODA_OPEN_BY_FD) {
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struct coda_open_by_fd_out *outp =
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(struct coda_open_by_fd_out *)req->uc_data;
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if (!outp->oh.result) {
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outp->fh = fget(outp->fd);
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if (!outp->fh)
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return -EBADF;
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}
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}
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wake_up(&req->uc_sleep);
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out:
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return(count ? count : retval);
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}
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/*
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* Read a message from the kernel to Venus
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*/
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static ssize_t coda_psdev_read(struct file * file, char __user * buf,
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size_t nbytes, loff_t *off)
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{
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DECLARE_WAITQUEUE(wait, current);
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struct venus_comm *vcp = (struct venus_comm *) file->private_data;
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struct upc_req *req;
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ssize_t retval = 0, count = 0;
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if (nbytes == 0)
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return 0;
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mutex_lock(&vcp->vc_mutex);
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add_wait_queue(&vcp->vc_waitq, &wait);
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set_current_state(TASK_INTERRUPTIBLE);
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while (list_empty(&vcp->vc_pending)) {
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if (file->f_flags & O_NONBLOCK) {
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retval = -EAGAIN;
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break;
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}
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if (signal_pending(current)) {
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retval = -ERESTARTSYS;
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break;
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}
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mutex_unlock(&vcp->vc_mutex);
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schedule();
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mutex_lock(&vcp->vc_mutex);
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}
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set_current_state(TASK_RUNNING);
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remove_wait_queue(&vcp->vc_waitq, &wait);
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if (retval)
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goto out;
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req = list_entry(vcp->vc_pending.next, struct upc_req,uc_chain);
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list_del(&req->uc_chain);
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/* Move the input args into userspace */
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count = req->uc_inSize;
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if (nbytes < req->uc_inSize) {
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pr_warn("%s: Venus read %ld bytes of %d in message\n",
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__func__, (long)nbytes, req->uc_inSize);
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count = nbytes;
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}
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if (copy_to_user(buf, req->uc_data, count))
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retval = -EFAULT;
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/* If request was not a signal, enqueue and don't free */
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if (!(req->uc_flags & CODA_REQ_ASYNC)) {
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req->uc_flags |= CODA_REQ_READ;
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list_add_tail(&(req->uc_chain), &vcp->vc_processing);
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goto out;
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}
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kvfree(req->uc_data);
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kfree(req);
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out:
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mutex_unlock(&vcp->vc_mutex);
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return (count ? count : retval);
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}
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static int coda_psdev_open(struct inode * inode, struct file * file)
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{
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struct venus_comm *vcp;
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int idx, err;
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if (task_active_pid_ns(current) != &init_pid_ns)
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return -EINVAL;
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if (current_user_ns() != &init_user_ns)
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return -EINVAL;
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idx = iminor(inode);
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if (idx < 0 || idx >= MAX_CODADEVS)
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return -ENODEV;
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err = -EBUSY;
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vcp = &coda_comms[idx];
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mutex_lock(&vcp->vc_mutex);
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if (!vcp->vc_inuse) {
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vcp->vc_inuse++;
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INIT_LIST_HEAD(&vcp->vc_pending);
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INIT_LIST_HEAD(&vcp->vc_processing);
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init_waitqueue_head(&vcp->vc_waitq);
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vcp->vc_sb = NULL;
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vcp->vc_seq = 0;
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file->private_data = vcp;
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err = 0;
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}
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mutex_unlock(&vcp->vc_mutex);
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return err;
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}
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static int coda_psdev_release(struct inode * inode, struct file * file)
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{
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struct venus_comm *vcp = (struct venus_comm *) file->private_data;
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struct upc_req *req, *tmp;
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if (!vcp || !vcp->vc_inuse ) {
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pr_warn("%s: Not open.\n", __func__);
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return -1;
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}
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mutex_lock(&vcp->vc_mutex);
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/* Wakeup clients so they can return. */
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list_for_each_entry_safe(req, tmp, &vcp->vc_pending, uc_chain) {
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list_del(&req->uc_chain);
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/* Async requests need to be freed here */
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if (req->uc_flags & CODA_REQ_ASYNC) {
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kvfree(req->uc_data);
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kfree(req);
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continue;
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}
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req->uc_flags |= CODA_REQ_ABORT;
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wake_up(&req->uc_sleep);
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}
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list_for_each_entry_safe(req, tmp, &vcp->vc_processing, uc_chain) {
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list_del(&req->uc_chain);
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req->uc_flags |= CODA_REQ_ABORT;
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wake_up(&req->uc_sleep);
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}
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file->private_data = NULL;
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vcp->vc_inuse--;
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mutex_unlock(&vcp->vc_mutex);
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return 0;
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}
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static const struct file_operations coda_psdev_fops = {
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.owner = THIS_MODULE,
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.read = coda_psdev_read,
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.write = coda_psdev_write,
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.poll = coda_psdev_poll,
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.unlocked_ioctl = coda_psdev_ioctl,
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.open = coda_psdev_open,
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.release = coda_psdev_release,
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.llseek = noop_llseek,
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};
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static int __init init_coda_psdev(void)
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{
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int i, err = 0;
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if (register_chrdev(CODA_PSDEV_MAJOR, "coda", &coda_psdev_fops)) {
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pr_err("%s: unable to get major %d\n",
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__func__, CODA_PSDEV_MAJOR);
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return -EIO;
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}
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coda_psdev_class = class_create(THIS_MODULE, "coda");
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if (IS_ERR(coda_psdev_class)) {
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err = PTR_ERR(coda_psdev_class);
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goto out_chrdev;
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}
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for (i = 0; i < MAX_CODADEVS; i++) {
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mutex_init(&(&coda_comms[i])->vc_mutex);
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device_create(coda_psdev_class, NULL,
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MKDEV(CODA_PSDEV_MAJOR, i), NULL, "cfs%d", i);
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}
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coda_sysctl_init();
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goto out;
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out_chrdev:
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unregister_chrdev(CODA_PSDEV_MAJOR, "coda");
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out:
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return err;
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}
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MODULE_AUTHOR("Jan Harkes, Peter J. Braam");
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MODULE_DESCRIPTION("Coda Distributed File System VFS interface");
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MODULE_ALIAS_CHARDEV_MAJOR(CODA_PSDEV_MAJOR);
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MODULE_LICENSE("GPL");
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MODULE_VERSION("7.0");
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static int __init init_coda(void)
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{
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int status;
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int i;
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status = coda_init_inodecache();
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if (status)
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goto out2;
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status = init_coda_psdev();
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if ( status ) {
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pr_warn("Problem (%d) in init_coda_psdev\n", status);
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goto out1;
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}
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status = register_filesystem(&coda_fs_type);
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if (status) {
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pr_warn("failed to register filesystem!\n");
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goto out;
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}
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return 0;
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out:
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for (i = 0; i < MAX_CODADEVS; i++)
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device_destroy(coda_psdev_class, MKDEV(CODA_PSDEV_MAJOR, i));
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class_destroy(coda_psdev_class);
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unregister_chrdev(CODA_PSDEV_MAJOR, "coda");
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coda_sysctl_clean();
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out1:
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coda_destroy_inodecache();
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out2:
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return status;
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}
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static void __exit exit_coda(void)
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{
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int err, i;
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err = unregister_filesystem(&coda_fs_type);
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if (err != 0)
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pr_warn("failed to unregister filesystem\n");
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for (i = 0; i < MAX_CODADEVS; i++)
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device_destroy(coda_psdev_class, MKDEV(CODA_PSDEV_MAJOR, i));
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class_destroy(coda_psdev_class);
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unregister_chrdev(CODA_PSDEV_MAJOR, "coda");
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coda_sysctl_clean();
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coda_destroy_inodecache();
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}
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module_init(init_coda);
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module_exit(exit_coda);
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