fs/afs/mntpt.c

   1 /* mountpoint management
   2  *
   3  * Copyright (C) 2002 Red Hat, Inc. All Rights Reserved.
   4  * Written by David Howells (dhowells@redhat.com)
   5  *
   6  * This program is free software; you can redistribute it and/or
   7  * modify it under the terms of the GNU General Public License
   8  * as published by the Free Software Foundation; either version
   9  * 2 of the License, or (at your option) any later version.
  10  */
  11
  12 #include <linux/kernel.h>
  13 #include <linux/module.h>
  14 #include <linux/init.h>
  15 #include <linux/fs.h>
  16 #include <linux/pagemap.h>
  17 #include <linux/mount.h>
  18 #include <linux/namei.h>
  19 #include <linux/gfp.h>
  20 #include "internal.h"
  21
  22
  23 static struct dentry *afs_mntpt_lookup(struct inode *dir,
  24                                        struct dentry *dentry,
  25                                        unsigned int flags);
  26 static int afs_mntpt_open(struct inode *inode, struct file *file);
  27 static void afs_mntpt_expiry_timed_out(struct work_struct *work);
  28
  29 const struct file_operations afs_mntpt_file_operations = {
  30         .open           = afs_mntpt_open,
  31         .llseek         = noop_llseek,
  32 };
  33
  34 const struct inode_operations afs_mntpt_inode_operations = {
  35         .lookup         = afs_mntpt_lookup,
  36         .readlink       = page_readlink,
  37         .getattr        = afs_getattr,
  38         .listxattr      = afs_listxattr,
  39 };
  40
  41 const struct inode_operations afs_autocell_inode_operations = {
  42         .getattr        = afs_getattr,
  43 };
  44
  45 static LIST_HEAD(afs_vfsmounts);
  46 static DECLARE_DELAYED_WORK(afs_mntpt_expiry_timer, afs_mntpt_expiry_timed_out);
  47
  48 static unsigned long afs_mntpt_expiry_timeout = 10 * 60;
  49
  50 /*
  51  * no valid lookup procedure on this sort of dir
  52  */
  53 static struct dentry *afs_mntpt_lookup(struct inode *dir,
  54                                        struct dentry *dentry,
  55                                        unsigned int flags)
  56 {
  57         _enter("%p,%p{%pd2}", dir, dentry, dentry);
  58         return ERR_PTR(-EREMOTE);
  59 }
  60
  61 /*
  62  * no valid open procedure on this sort of dir
  63  */
  64 static int afs_mntpt_open(struct inode *inode, struct file *file)
  65 {
  66         _enter("%p,%p{%pD2}", inode, file, file);
  67         return -EREMOTE;
  68 }
  69
  70 /*
  71  * create a vfsmount to be automounted
  72  */
  73 static struct vfsmount *afs_mntpt_do_automount(struct dentry *mntpt)
  74 {
  75         struct afs_super_info *as;
  76         struct vfsmount *mnt;
  77         struct afs_vnode *vnode;
  78         struct page *page;
  79         char *devname, *options;
  80         bool rwpath = false;
  81         int ret;
  82
  83         _enter("{%pd}", mntpt);
  84
  85         BUG_ON(!d_inode(mntpt));
  86
  87         ret = -ENOMEM;
  88         devname = (char *) get_zeroed_page(GFP_KERNEL);
  89         if (!devname)
  90                 goto error_no_devname;
  91
  92         options = (char *) get_zeroed_page(GFP_KERNEL);
  93         if (!options)
  94                 goto error_no_options;
  95
  96         vnode = AFS_FS_I(d_inode(mntpt));
  97         if (test_bit(AFS_VNODE_PSEUDODIR, &vnode->flags)) {
  98                 /* if the directory is a pseudo directory, use the d_name */
  99                 static const char afs_root_cell[] = ":root.cell.";
 100                 unsigned size = mntpt->d_name.len;
 101
 102                 ret = -ENOENT;
 103                 if (size < 2 || size > AFS_MAXCELLNAME)
 104                         goto error_no_page;
 105
 106                 if (mntpt->d_name.name[0] == '.') {
 107                         devname[0] = '%';
 108                         memcpy(devname + 1, mntpt->d_name.name + 1, size - 1);
 109                         memcpy(devname + size, afs_root_cell,
 110                                sizeof(afs_root_cell));
 111                         rwpath = true;
 112                 } else {
 113                         devname[0] = '#';
 114                         memcpy(devname + 1, mntpt->d_name.name, size);
 115                         memcpy(devname + size + 1, afs_root_cell,
 116                                sizeof(afs_root_cell));
 117                 }
 118         } else {
 119                 /* read the contents of the AFS special symlink */
 120                 loff_t size = i_size_read(d_inode(mntpt));
 121                 char *buf;
 122
 123                 ret = -EINVAL;
 124                 if (size > PAGE_SIZE - 1)
 125                         goto error_no_page;
 126
 127                 page = read_mapping_page(d_inode(mntpt)->i_mapping, 0, NULL);
 128                 if (IS_ERR(page)) {
 129                         ret = PTR_ERR(page);
 130                         goto error_no_page;
 131                 }
 132
 133                 ret = -EIO;
 134                 if (PageError(page))
 135                         goto error;
 136
 137                 buf = kmap_atomic(page);
 138                 memcpy(devname, buf, size);
 139                 kunmap_atomic(buf);
 140                 put_page(page);
 141                 page = NULL;
 142         }
 143
 144         /* work out what options we want */
 145         as = AFS_FS_S(mntpt->d_sb);
 146         if (as->cell) {
 147                 memcpy(options, "cell=", 5);
 148                 strcpy(options + 5, as->cell->name);
 149                 if ((as->volume && as->volume->type == AFSVL_RWVOL) || rwpath)
 150                         strcat(options, ",rwpath");
 151         }
 152
 153         /* try and do the mount */
 154         _debug("--- attempting mount %s -o %s ---", devname, options);
 155         mnt = vfs_submount(mntpt, &afs_fs_type, devname, options);
 156         _debug("--- mount result %p ---", mnt);
 157
 158         free_page((unsigned long) devname);
 159         free_page((unsigned long) options);
 160         _leave(" = %p", mnt);
 161         return mnt;
 162
 163 error:
 164         put_page(page);
 165 error_no_page:
 166         free_page((unsigned long) options);
 167 error_no_options:
 168         free_page((unsigned long) devname);
 169 error_no_devname:
 170         _leave(" = %d", ret);
 171         return ERR_PTR(ret);
 172 }
 173
 174 /*
 175  * handle an automount point
 176  */
 177 struct vfsmount *afs_d_automount(struct path *path)
 178 {
 179         struct vfsmount *newmnt;
 180
 181         _enter("{%pd}", path->dentry);
 182
 183         newmnt = afs_mntpt_do_automount(path->dentry);
 184         if (IS_ERR(newmnt))
 185                 return newmnt;
 186
 187         mntget(newmnt); /* prevent immediate expiration */
 188         mnt_set_expiry(newmnt, &afs_vfsmounts);
 189         queue_delayed_work(afs_wq, &afs_mntpt_expiry_timer,
 190                            afs_mntpt_expiry_timeout * HZ);
 191         _leave(" = %p", newmnt);
 192         return newmnt;
 193 }
 194
 195 /*
 196  * handle mountpoint expiry timer going off
 197  */
 198 static void afs_mntpt_expiry_timed_out(struct work_struct *work)
 199 {
 200         _enter("");
 201
 202         if (!list_empty(&afs_vfsmounts)) {
 203                 mark_mounts_for_expiry(&afs_vfsmounts);
 204                 queue_delayed_work(afs_wq, &afs_mntpt_expiry_timer,
 205                                    afs_mntpt_expiry_timeout * HZ);
 206         }
 207
 208         _leave("");
 209 }
 210
 211 /*
 212  * kill the AFS mountpoint timer if it's still running
 213  */
 214 void afs_mntpt_kill_timer(void)
 215 {
 216         _enter("");
 217
 218         ASSERT(list_empty(&afs_vfsmounts));
 219         cancel_delayed_work_sync(&afs_mntpt_expiry_timer);
 220 }