forked from Minki/linux
288 lines
7.0 KiB
C
288 lines
7.0 KiB
C
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/* mntpt.c: 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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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* as published by the Free Software Foundation; either version
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* 2 of the License, or (at your option) any later version.
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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/sched.h>
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#include <linux/slab.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/namespace.h>
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#include "super.h"
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#include "cell.h"
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#include "volume.h"
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#include "vnode.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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struct nameidata *nd);
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static int afs_mntpt_open(struct inode *inode, struct file *file);
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static int afs_mntpt_follow_link(struct dentry *dentry, struct nameidata *nd);
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struct file_operations afs_mntpt_file_operations = {
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.open = afs_mntpt_open,
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};
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struct inode_operations afs_mntpt_inode_operations = {
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.lookup = afs_mntpt_lookup,
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.follow_link = afs_mntpt_follow_link,
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.readlink = page_readlink,
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.getattr = afs_inode_getattr,
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};
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static LIST_HEAD(afs_vfsmounts);
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static void afs_mntpt_expiry_timed_out(struct afs_timer *timer);
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struct afs_timer_ops afs_mntpt_expiry_timer_ops = {
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.timed_out = afs_mntpt_expiry_timed_out,
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};
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struct afs_timer afs_mntpt_expiry_timer;
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unsigned long afs_mntpt_expiry_timeout = 20;
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/*****************************************************************************/
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/*
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* check a symbolic link to see whether it actually encodes a mountpoint
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* - sets the AFS_VNODE_MOUNTPOINT flag on the vnode appropriately
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*/
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int afs_mntpt_check_symlink(struct afs_vnode *vnode)
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{
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struct page *page;
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filler_t *filler;
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size_t size;
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char *buf;
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int ret;
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_enter("{%u,%u}", vnode->fid.vnode, vnode->fid.unique);
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/* read the contents of the symlink into the pagecache */
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filler = (filler_t *) AFS_VNODE_TO_I(vnode)->i_mapping->a_ops->readpage;
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page = read_cache_page(AFS_VNODE_TO_I(vnode)->i_mapping, 0,
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filler, NULL);
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if (IS_ERR(page)) {
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ret = PTR_ERR(page);
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goto out;
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}
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ret = -EIO;
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wait_on_page_locked(page);
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buf = kmap(page);
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if (!PageUptodate(page))
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goto out_free;
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if (PageError(page))
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goto out_free;
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/* examine the symlink's contents */
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size = vnode->status.size;
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_debug("symlink to %*.*s", size, (int) size, buf);
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if (size > 2 &&
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(buf[0] == '%' || buf[0] == '#') &&
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buf[size - 1] == '.'
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) {
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_debug("symlink is a mountpoint");
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spin_lock(&vnode->lock);
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vnode->flags |= AFS_VNODE_MOUNTPOINT;
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spin_unlock(&vnode->lock);
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}
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ret = 0;
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out_free:
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kunmap(page);
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page_cache_release(page);
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out:
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_leave(" = %d", ret);
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return ret;
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} /* end afs_mntpt_check_symlink() */
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/*****************************************************************************/
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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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struct nameidata *nd)
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{
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kenter("%p,%p{%p{%s},%s}",
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dir,
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dentry,
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dentry->d_parent,
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dentry->d_parent ?
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dentry->d_parent->d_name.name : (const unsigned char *) "",
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dentry->d_name.name);
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return ERR_PTR(-EREMOTE);
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} /* end afs_mntpt_lookup() */
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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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kenter("%p,%p{%p{%s},%s}",
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inode, file,
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file->f_dentry->d_parent,
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file->f_dentry->d_parent ?
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file->f_dentry->d_parent->d_name.name :
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(const unsigned char *) "",
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file->f_dentry->d_name.name);
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return -EREMOTE;
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} /* end afs_mntpt_open() */
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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 afs_super_info *super;
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struct vfsmount *mnt;
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struct page *page = NULL;
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size_t size;
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char *buf, *devname = NULL, *options = NULL;
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filler_t *filler;
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int ret;
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kenter("{%s}", mntpt->d_name.name);
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BUG_ON(!mntpt->d_inode);
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ret = -EINVAL;
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size = mntpt->d_inode->i_size;
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if (size > PAGE_SIZE - 1)
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goto error;
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ret = -ENOMEM;
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devname = (char *) get_zeroed_page(GFP_KERNEL);
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if (!devname)
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goto error;
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options = (char *) get_zeroed_page(GFP_KERNEL);
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if (!options)
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goto error;
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/* read the contents of the AFS special symlink */
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filler = (filler_t *)mntpt->d_inode->i_mapping->a_ops->readpage;
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page = read_cache_page(mntpt->d_inode->i_mapping, 0, filler, NULL);
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if (IS_ERR(page)) {
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ret = PTR_ERR(page);
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goto error;
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}
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ret = -EIO;
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wait_on_page_locked(page);
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if (!PageUptodate(page) || PageError(page))
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goto error;
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buf = kmap(page);
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memcpy(devname, buf, size);
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kunmap(page);
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page_cache_release(page);
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page = NULL;
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/* work out what options we want */
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super = AFS_FS_S(mntpt->d_sb);
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memcpy(options, "cell=", 5);
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strcpy(options + 5, super->volume->cell->name);
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if (super->volume->type == AFSVL_RWVOL)
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strcat(options, ",rwpath");
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/* try and do the mount */
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kdebug("--- attempting mount %s -o %s ---", devname, options);
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mnt = do_kern_mount("afs", 0, devname, options);
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kdebug("--- mount result %p ---", mnt);
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free_page((unsigned long) devname);
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free_page((unsigned long) options);
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kleave(" = %p", mnt);
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return mnt;
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error:
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if (page)
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page_cache_release(page);
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if (devname)
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free_page((unsigned long) devname);
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if (options)
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free_page((unsigned long) options);
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kleave(" = %d", ret);
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return ERR_PTR(ret);
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} /* end afs_mntpt_do_automount() */
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/*****************************************************************************/
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/*
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* follow a link from a mountpoint directory, thus causing it to be mounted
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*/
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static int afs_mntpt_follow_link(struct dentry *dentry, struct nameidata *nd)
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{
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struct vfsmount *newmnt;
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struct dentry *old_dentry;
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int err;
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kenter("%p{%s},{%s:%p{%s}}",
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dentry,
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dentry->d_name.name,
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nd->mnt->mnt_devname,
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dentry,
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nd->dentry->d_name.name);
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newmnt = afs_mntpt_do_automount(dentry);
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if (IS_ERR(newmnt)) {
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path_release(nd);
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return PTR_ERR(newmnt);
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}
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old_dentry = nd->dentry;
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nd->dentry = dentry;
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err = do_add_mount(newmnt, nd, 0, &afs_vfsmounts);
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nd->dentry = old_dentry;
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path_release(nd);
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if (!err) {
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mntget(newmnt);
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nd->mnt = newmnt;
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dget(newmnt->mnt_root);
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nd->dentry = newmnt->mnt_root;
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}
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kleave(" = %d", err);
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return err;
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} /* end afs_mntpt_follow_link() */
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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 afs_timer *timer)
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{
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kenter("");
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mark_mounts_for_expiry(&afs_vfsmounts);
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afs_kafstimod_add_timer(&afs_mntpt_expiry_timer,
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afs_mntpt_expiry_timeout * HZ);
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kleave("");
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} /* end afs_mntpt_expiry_timed_out() */
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