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 };
  39
  40 const struct inode_operations afs_autocell_inode_operations = {
  41         .getattr        = afs_getattr,
  42 };
  43
  44 static LIST_HEAD(afs_vfsmounts);
  45 static DECLARE_DELAYED_WORK(afs_mntpt_expiry_timer, afs_mntpt_expiry_timed_out);
  46
  47 static unsigned long afs_mntpt_expiry_timeout = 10 * 60;
  48
  49 /*
  50  * no valid lookup procedure on this sort of dir
  51  */
  52 static struct dentry *afs_mntpt_lookup(struct inode *dir,
  53                                        struct dentry *dentry,
  54                                        unsigned int flags)
  55 {
  56         _enter("%p,%p{%pd2}", dir, dentry, dentry);
  57         return ERR_PTR(-EREMOTE);
  58 }
  59
  60 /*
  61  * no valid open procedure on this sort of dir
  62  */
  63 static int afs_mntpt_open(struct inode *inode, struct file *file)
  64 {
  65         _enter("%p,%p{%pD2}", inode, file, file);
  66         return -EREMOTE;
  67 }
  68
  69 /*
  70  * create a vfsmount to be automounted
  71  */
  72 static struct vfsmount *afs_mntpt_do_automount(struct dentry *mntpt)
  73 {
  74         struct afs_super_info *super;
  75         struct vfsmount *mnt;
  76         struct afs_vnode *vnode;
  77         struct page *page;
  78         char *devname, *options;
  79         bool rwpath = false;
  80         int ret;
  81
  82         _enter("{%pd}", mntpt);
  83
  84         BUG_ON(!d_inode(mntpt));
  85
  86         ret = -ENOMEM;
  87         devname = (char *) get_zeroed_page(GFP_KERNEL);
  88         if (!devname)
  89                 goto error_no_devname;
  90
  91         options = (char *) get_zeroed_page(GFP_KERNEL);
  92         if (!options)
  93                 goto error_no_options;
  94
  95         vnode = AFS_FS_I(d_inode(mntpt));
  96         if (test_bit(AFS_VNODE_PSEUDODIR, &vnode->flags)) {
  97                 /* if the directory is a pseudo directory, use the d_name */
  98                 static const char afs_root_cell[] = ":root.cell.";
  99                 unsigned size = mntpt->d_name.len;
 100
 101                 ret = -ENOENT;
 102                 if (size < 2 || size > AFS_MAXCELLNAME)
 103                         goto error_no_page;
 104
 105                 if (mntpt->d_name.name[0] == '.') {
 106                         devname[0] = '#';
 107                         memcpy(devname + 1, mntpt->d_name.name, size - 1);
 108                         memcpy(devname + size, afs_root_cell,
 109                                sizeof(afs_root_cell));
 110                         rwpath = true;
 111                 } else {
 112                         devname[0] = '%';
 113                         memcpy(devname + 1, mntpt->d_name.name, size);
 114                         memcpy(devname + size + 1, afs_root_cell,
 115                                sizeof(afs_root_cell));
 116                 }
 117         } else {
 118                 /* read the contents of the AFS special symlink */
 119                 loff_t size = i_size_read(d_inode(mntpt));
 120                 char *buf;
 121
 122                 ret = -EINVAL;
 123                 if (size > PAGE_SIZE - 1)
 124                         goto error_no_page;
 125
 126                 page = read_mapping_page(d_inode(mntpt)->i_mapping, 0, NULL);
 127                 if (IS_ERR(page)) {
 128                         ret = PTR_ERR(page);
 129                         goto error_no_page;
 130                 }
 131
 132                 ret = -EIO;
 133                 if (PageError(page))
 134                         goto error;
 135
 136                 buf = kmap_atomic(page);
 137                 memcpy(devname, buf, size);
 138                 kunmap_atomic(buf);
 139                 put_page(page);
 140                 page = NULL;
 141         }
 142
 143         /* work out what options we want */
 144         super = AFS_FS_S(mntpt->d_sb);
 145         memcpy(options, "cell=", 5);
 146         strcpy(options + 5, super->volume->cell->name);
 147         if (super->volume->type == AFSVL_RWVOL || rwpath)
 148                 strcat(options, ",rwpath");
 149
 150         /* try and do the mount */
 151         _debug("--- attempting mount %s -o %s ---", devname, options);
 152         mnt = vfs_submount(mntpt, &afs_fs_type, devname, options);
 153         _debug("--- mount result %p ---", mnt);
 154
 155         free_page((unsigned long) devname);
 156         free_page((unsigned long) options);
 157         _leave(" = %p", mnt);
 158         return mnt;
 159
 160 error:
 161         put_page(page);
 162 error_no_page:
 163         free_page((unsigned long) options);
 164 error_no_options:
 165         free_page((unsigned long) devname);
 166 error_no_devname:
 167         _leave(" = %d", ret);
 168         return ERR_PTR(ret);
 169 }
 170
 171 /*
 172  * handle an automount point
 173  */
 174 struct vfsmount *afs_d_automount(struct path *path)
 175 {
 176         struct vfsmount *newmnt;
 177
 178         _enter("{%pd}", path->dentry);
 179
 180         newmnt = afs_mntpt_do_automount(path->dentry);
 181         if (IS_ERR(newmnt))
 182                 return newmnt;
 183
 184         mntget(newmnt); /* prevent immediate expiration */
 185         mnt_set_expiry(newmnt, &afs_vfsmounts);
 186         queue_delayed_work(afs_wq, &afs_mntpt_expiry_timer,
 187                            afs_mntpt_expiry_timeout * HZ);
 188         _leave(" = %p", newmnt);
 189         return newmnt;
 190 }
 191
 192 /*
 193  * handle mountpoint expiry timer going off
 194  */
 195 static void afs_mntpt_expiry_timed_out(struct work_struct *work)
 196 {
 197         _enter("");
 198
 199         if (!list_empty(&afs_vfsmounts)) {
 200                 mark_mounts_for_expiry(&afs_vfsmounts);
 201                 queue_delayed_work(afs_wq, &afs_mntpt_expiry_timer,
 202                                    afs_mntpt_expiry_timeout * HZ);
 203         }
 204
 205         _leave("");
 206 }
 207
 208 /*
 209  * kill the AFS mountpoint timer if it's still running
 210  */
 211 void afs_mntpt_kill_timer(void)
 212 {
 213         _enter("");
 214
 215         ASSERT(list_empty(&afs_vfsmounts));
 216         cancel_delayed_work_sync(&afs_mntpt_expiry_timer);
 217 }