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![David Howells](/assets/img/avatar_default.png)
Each AFS mountpoint has strings that define the target to be mounted. This
is required to end in a dot that is supposed to be stripped off. The
string can include suffixes of ".readonly" or ".backup" - which are
supposed to come before the terminal dot. To add to the confusion, the "fs
lsmount" afs utility does not show the terminal dot when displaying the
string.
The kernel mount source string parser, however, assumes that the terminal
dot marks the suffix and that the suffix is always "" and is thus ignored.
In most cases, there is no suffix and this is not a problem - but if there
is a suffix, it is lost and this affects the ability to mount the correct
volume.
The command line mount command, on the other hand, is expected not to
include a terminal dot - so the problem doesn't arise there.
Fix this by making sure that the dot exists and then stripping it when
passing the string to the mount configuration.
Fixes: bec5eb6141
("AFS: Implement an autocell mount capability [ver #2]")
Reported-by: Jonathan Billings <jsbillings@jsbillings.org>
Signed-off-by: David Howells <dhowells@redhat.com>
Reviewed-by: Marc Dionne <marc.dionne@auristor.com>
Tested-by: Jonathan Billings <jsbillings@jsbillings.org>
226 lines
5.1 KiB
C
226 lines
5.1 KiB
C
// SPDX-License-Identifier: GPL-2.0-or-later
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/* mountpoint management
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*
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* Copyright (C) 2002 Red Hat, Inc. All Rights Reserved.
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* Written by David Howells (dhowells@redhat.com)
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*/
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#include <linux/kernel.h>
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#include <linux/module.h>
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#include <linux/init.h>
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#include <linux/fs.h>
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#include <linux/pagemap.h>
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#include <linux/mount.h>
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#include <linux/namei.h>
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#include <linux/gfp.h>
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#include <linux/fs_context.h>
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#include "internal.h"
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static struct dentry *afs_mntpt_lookup(struct inode *dir,
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struct dentry *dentry,
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unsigned int flags);
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static int afs_mntpt_open(struct inode *inode, struct file *file);
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static void afs_mntpt_expiry_timed_out(struct work_struct *work);
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const struct file_operations afs_mntpt_file_operations = {
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.open = afs_mntpt_open,
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.llseek = noop_llseek,
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};
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const struct inode_operations afs_mntpt_inode_operations = {
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.lookup = afs_mntpt_lookup,
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.readlink = page_readlink,
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.getattr = afs_getattr,
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.listxattr = afs_listxattr,
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};
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const struct inode_operations afs_autocell_inode_operations = {
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.getattr = afs_getattr,
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};
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static LIST_HEAD(afs_vfsmounts);
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static DECLARE_DELAYED_WORK(afs_mntpt_expiry_timer, afs_mntpt_expiry_timed_out);
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static unsigned long afs_mntpt_expiry_timeout = 10 * 60;
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static const char afs_root_volume[] = "root.cell";
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/*
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* no valid lookup procedure on this sort of dir
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*/
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static struct dentry *afs_mntpt_lookup(struct inode *dir,
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struct dentry *dentry,
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unsigned int flags)
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{
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_enter("%p,%p{%pd2}", dir, dentry, dentry);
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return ERR_PTR(-EREMOTE);
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}
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/*
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* no valid open procedure on this sort of dir
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*/
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static int afs_mntpt_open(struct inode *inode, struct file *file)
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{
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_enter("%p,%p{%pD2}", inode, file, file);
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return -EREMOTE;
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}
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/*
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* Set the parameters for the proposed superblock.
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*/
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static int afs_mntpt_set_params(struct fs_context *fc, struct dentry *mntpt)
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{
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struct afs_fs_context *ctx = fc->fs_private;
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struct afs_super_info *src_as = AFS_FS_S(mntpt->d_sb);
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struct afs_vnode *vnode = AFS_FS_I(d_inode(mntpt));
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struct afs_cell *cell;
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const char *p;
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int ret;
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if (fc->net_ns != src_as->net_ns) {
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put_net(fc->net_ns);
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fc->net_ns = get_net(src_as->net_ns);
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}
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if (src_as->volume && src_as->volume->type == AFSVL_RWVOL) {
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ctx->type = AFSVL_RWVOL;
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ctx->force = true;
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}
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if (ctx->cell) {
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afs_put_cell(ctx->net, ctx->cell);
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ctx->cell = NULL;
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}
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if (test_bit(AFS_VNODE_PSEUDODIR, &vnode->flags)) {
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/* if the directory is a pseudo directory, use the d_name */
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unsigned size = mntpt->d_name.len;
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if (size < 2)
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return -ENOENT;
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p = mntpt->d_name.name;
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if (mntpt->d_name.name[0] == '.') {
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size--;
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p++;
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ctx->type = AFSVL_RWVOL;
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ctx->force = true;
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}
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if (size > AFS_MAXCELLNAME)
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return -ENAMETOOLONG;
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cell = afs_lookup_cell(ctx->net, p, size, NULL, false);
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if (IS_ERR(cell)) {
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pr_err("kAFS: unable to lookup cell '%pd'\n", mntpt);
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return PTR_ERR(cell);
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}
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ctx->cell = cell;
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ctx->volname = afs_root_volume;
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ctx->volnamesz = sizeof(afs_root_volume) - 1;
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} else {
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/* read the contents of the AFS special symlink */
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struct page *page;
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loff_t size = i_size_read(d_inode(mntpt));
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char *buf;
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if (src_as->cell)
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ctx->cell = afs_get_cell(src_as->cell);
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if (size < 2 || size > PAGE_SIZE - 1)
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return -EINVAL;
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page = read_mapping_page(d_inode(mntpt)->i_mapping, 0, NULL);
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if (IS_ERR(page))
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return PTR_ERR(page);
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if (PageError(page)) {
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ret = afs_bad(AFS_FS_I(d_inode(mntpt)), afs_file_error_mntpt);
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put_page(page);
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return ret;
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}
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buf = kmap(page);
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ret = -EINVAL;
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if (buf[size - 1] == '.')
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ret = vfs_parse_fs_string(fc, "source", buf, size - 1);
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kunmap(page);
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put_page(page);
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if (ret < 0)
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return ret;
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}
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return 0;
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}
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/*
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* create a vfsmount to be automounted
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*/
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static struct vfsmount *afs_mntpt_do_automount(struct dentry *mntpt)
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{
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struct fs_context *fc;
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struct vfsmount *mnt;
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int ret;
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BUG_ON(!d_inode(mntpt));
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fc = fs_context_for_submount(&afs_fs_type, mntpt);
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if (IS_ERR(fc))
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return ERR_CAST(fc);
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ret = afs_mntpt_set_params(fc, mntpt);
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if (!ret)
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mnt = fc_mount(fc);
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else
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mnt = ERR_PTR(ret);
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put_fs_context(fc);
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return mnt;
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}
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/*
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* handle an automount point
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*/
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struct vfsmount *afs_d_automount(struct path *path)
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{
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struct vfsmount *newmnt;
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_enter("{%pd}", path->dentry);
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newmnt = afs_mntpt_do_automount(path->dentry);
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if (IS_ERR(newmnt))
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return newmnt;
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mntget(newmnt); /* prevent immediate expiration */
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mnt_set_expiry(newmnt, &afs_vfsmounts);
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queue_delayed_work(afs_wq, &afs_mntpt_expiry_timer,
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afs_mntpt_expiry_timeout * HZ);
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_leave(" = %p", newmnt);
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return newmnt;
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}
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/*
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* handle mountpoint expiry timer going off
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*/
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static void afs_mntpt_expiry_timed_out(struct work_struct *work)
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{
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_enter("");
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if (!list_empty(&afs_vfsmounts)) {
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mark_mounts_for_expiry(&afs_vfsmounts);
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queue_delayed_work(afs_wq, &afs_mntpt_expiry_timer,
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afs_mntpt_expiry_timeout * HZ);
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}
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_leave("");
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}
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/*
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* kill the AFS mountpoint timer if it's still running
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*/
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void afs_mntpt_kill_timer(void)
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{
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_enter("");
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ASSERT(list_empty(&afs_vfsmounts));
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cancel_delayed_work_sync(&afs_mntpt_expiry_timer);
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}
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