Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame^] | 1 | /* mntpt.c: 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/sched.h> |
| 16 | #include <linux/slab.h> |
| 17 | #include <linux/fs.h> |
| 18 | #include <linux/pagemap.h> |
| 19 | #include <linux/mount.h> |
| 20 | #include <linux/namei.h> |
| 21 | #include <linux/namespace.h> |
| 22 | #include "super.h" |
| 23 | #include "cell.h" |
| 24 | #include "volume.h" |
| 25 | #include "vnode.h" |
| 26 | #include "internal.h" |
| 27 | |
| 28 | |
| 29 | static struct dentry *afs_mntpt_lookup(struct inode *dir, |
| 30 | struct dentry *dentry, |
| 31 | struct nameidata *nd); |
| 32 | static int afs_mntpt_open(struct inode *inode, struct file *file); |
| 33 | static int afs_mntpt_follow_link(struct dentry *dentry, struct nameidata *nd); |
| 34 | |
| 35 | struct file_operations afs_mntpt_file_operations = { |
| 36 | .open = afs_mntpt_open, |
| 37 | }; |
| 38 | |
| 39 | struct inode_operations afs_mntpt_inode_operations = { |
| 40 | .lookup = afs_mntpt_lookup, |
| 41 | .follow_link = afs_mntpt_follow_link, |
| 42 | .readlink = page_readlink, |
| 43 | .getattr = afs_inode_getattr, |
| 44 | }; |
| 45 | |
| 46 | static LIST_HEAD(afs_vfsmounts); |
| 47 | |
| 48 | static void afs_mntpt_expiry_timed_out(struct afs_timer *timer); |
| 49 | |
| 50 | struct afs_timer_ops afs_mntpt_expiry_timer_ops = { |
| 51 | .timed_out = afs_mntpt_expiry_timed_out, |
| 52 | }; |
| 53 | |
| 54 | struct afs_timer afs_mntpt_expiry_timer; |
| 55 | |
| 56 | unsigned long afs_mntpt_expiry_timeout = 20; |
| 57 | |
| 58 | /*****************************************************************************/ |
| 59 | /* |
| 60 | * check a symbolic link to see whether it actually encodes a mountpoint |
| 61 | * - sets the AFS_VNODE_MOUNTPOINT flag on the vnode appropriately |
| 62 | */ |
| 63 | int afs_mntpt_check_symlink(struct afs_vnode *vnode) |
| 64 | { |
| 65 | struct page *page; |
| 66 | filler_t *filler; |
| 67 | size_t size; |
| 68 | char *buf; |
| 69 | int ret; |
| 70 | |
| 71 | _enter("{%u,%u}", vnode->fid.vnode, vnode->fid.unique); |
| 72 | |
| 73 | /* read the contents of the symlink into the pagecache */ |
| 74 | filler = (filler_t *) AFS_VNODE_TO_I(vnode)->i_mapping->a_ops->readpage; |
| 75 | |
| 76 | page = read_cache_page(AFS_VNODE_TO_I(vnode)->i_mapping, 0, |
| 77 | filler, NULL); |
| 78 | if (IS_ERR(page)) { |
| 79 | ret = PTR_ERR(page); |
| 80 | goto out; |
| 81 | } |
| 82 | |
| 83 | ret = -EIO; |
| 84 | wait_on_page_locked(page); |
| 85 | buf = kmap(page); |
| 86 | if (!PageUptodate(page)) |
| 87 | goto out_free; |
| 88 | if (PageError(page)) |
| 89 | goto out_free; |
| 90 | |
| 91 | /* examine the symlink's contents */ |
| 92 | size = vnode->status.size; |
| 93 | _debug("symlink to %*.*s", size, (int) size, buf); |
| 94 | |
| 95 | if (size > 2 && |
| 96 | (buf[0] == '%' || buf[0] == '#') && |
| 97 | buf[size - 1] == '.' |
| 98 | ) { |
| 99 | _debug("symlink is a mountpoint"); |
| 100 | spin_lock(&vnode->lock); |
| 101 | vnode->flags |= AFS_VNODE_MOUNTPOINT; |
| 102 | spin_unlock(&vnode->lock); |
| 103 | } |
| 104 | |
| 105 | ret = 0; |
| 106 | |
| 107 | out_free: |
| 108 | kunmap(page); |
| 109 | page_cache_release(page); |
| 110 | out: |
| 111 | _leave(" = %d", ret); |
| 112 | return ret; |
| 113 | |
| 114 | } /* end afs_mntpt_check_symlink() */ |
| 115 | |
| 116 | /*****************************************************************************/ |
| 117 | /* |
| 118 | * no valid lookup procedure on this sort of dir |
| 119 | */ |
| 120 | static struct dentry *afs_mntpt_lookup(struct inode *dir, |
| 121 | struct dentry *dentry, |
| 122 | struct nameidata *nd) |
| 123 | { |
| 124 | kenter("%p,%p{%p{%s},%s}", |
| 125 | dir, |
| 126 | dentry, |
| 127 | dentry->d_parent, |
| 128 | dentry->d_parent ? |
| 129 | dentry->d_parent->d_name.name : (const unsigned char *) "", |
| 130 | dentry->d_name.name); |
| 131 | |
| 132 | return ERR_PTR(-EREMOTE); |
| 133 | } /* end afs_mntpt_lookup() */ |
| 134 | |
| 135 | /*****************************************************************************/ |
| 136 | /* |
| 137 | * no valid open procedure on this sort of dir |
| 138 | */ |
| 139 | static int afs_mntpt_open(struct inode *inode, struct file *file) |
| 140 | { |
| 141 | kenter("%p,%p{%p{%s},%s}", |
| 142 | inode, file, |
| 143 | file->f_dentry->d_parent, |
| 144 | file->f_dentry->d_parent ? |
| 145 | file->f_dentry->d_parent->d_name.name : |
| 146 | (const unsigned char *) "", |
| 147 | file->f_dentry->d_name.name); |
| 148 | |
| 149 | return -EREMOTE; |
| 150 | } /* end afs_mntpt_open() */ |
| 151 | |
| 152 | /*****************************************************************************/ |
| 153 | /* |
| 154 | * create a vfsmount to be automounted |
| 155 | */ |
| 156 | static struct vfsmount *afs_mntpt_do_automount(struct dentry *mntpt) |
| 157 | { |
| 158 | struct afs_super_info *super; |
| 159 | struct vfsmount *mnt; |
| 160 | struct page *page = NULL; |
| 161 | size_t size; |
| 162 | char *buf, *devname = NULL, *options = NULL; |
| 163 | filler_t *filler; |
| 164 | int ret; |
| 165 | |
| 166 | kenter("{%s}", mntpt->d_name.name); |
| 167 | |
| 168 | BUG_ON(!mntpt->d_inode); |
| 169 | |
| 170 | ret = -EINVAL; |
| 171 | size = mntpt->d_inode->i_size; |
| 172 | if (size > PAGE_SIZE - 1) |
| 173 | goto error; |
| 174 | |
| 175 | ret = -ENOMEM; |
| 176 | devname = (char *) get_zeroed_page(GFP_KERNEL); |
| 177 | if (!devname) |
| 178 | goto error; |
| 179 | |
| 180 | options = (char *) get_zeroed_page(GFP_KERNEL); |
| 181 | if (!options) |
| 182 | goto error; |
| 183 | |
| 184 | /* read the contents of the AFS special symlink */ |
| 185 | filler = (filler_t *)mntpt->d_inode->i_mapping->a_ops->readpage; |
| 186 | |
| 187 | page = read_cache_page(mntpt->d_inode->i_mapping, 0, filler, NULL); |
| 188 | if (IS_ERR(page)) { |
| 189 | ret = PTR_ERR(page); |
| 190 | goto error; |
| 191 | } |
| 192 | |
| 193 | ret = -EIO; |
| 194 | wait_on_page_locked(page); |
| 195 | if (!PageUptodate(page) || PageError(page)) |
| 196 | goto error; |
| 197 | |
| 198 | buf = kmap(page); |
| 199 | memcpy(devname, buf, size); |
| 200 | kunmap(page); |
| 201 | page_cache_release(page); |
| 202 | page = NULL; |
| 203 | |
| 204 | /* work out what options we want */ |
| 205 | super = AFS_FS_S(mntpt->d_sb); |
| 206 | memcpy(options, "cell=", 5); |
| 207 | strcpy(options + 5, super->volume->cell->name); |
| 208 | if (super->volume->type == AFSVL_RWVOL) |
| 209 | strcat(options, ",rwpath"); |
| 210 | |
| 211 | /* try and do the mount */ |
| 212 | kdebug("--- attempting mount %s -o %s ---", devname, options); |
| 213 | mnt = do_kern_mount("afs", 0, devname, options); |
| 214 | kdebug("--- mount result %p ---", mnt); |
| 215 | |
| 216 | free_page((unsigned long) devname); |
| 217 | free_page((unsigned long) options); |
| 218 | kleave(" = %p", mnt); |
| 219 | return mnt; |
| 220 | |
| 221 | error: |
| 222 | if (page) |
| 223 | page_cache_release(page); |
| 224 | if (devname) |
| 225 | free_page((unsigned long) devname); |
| 226 | if (options) |
| 227 | free_page((unsigned long) options); |
| 228 | kleave(" = %d", ret); |
| 229 | return ERR_PTR(ret); |
| 230 | } /* end afs_mntpt_do_automount() */ |
| 231 | |
| 232 | /*****************************************************************************/ |
| 233 | /* |
| 234 | * follow a link from a mountpoint directory, thus causing it to be mounted |
| 235 | */ |
| 236 | static int afs_mntpt_follow_link(struct dentry *dentry, struct nameidata *nd) |
| 237 | { |
| 238 | struct vfsmount *newmnt; |
| 239 | struct dentry *old_dentry; |
| 240 | int err; |
| 241 | |
| 242 | kenter("%p{%s},{%s:%p{%s}}", |
| 243 | dentry, |
| 244 | dentry->d_name.name, |
| 245 | nd->mnt->mnt_devname, |
| 246 | dentry, |
| 247 | nd->dentry->d_name.name); |
| 248 | |
| 249 | newmnt = afs_mntpt_do_automount(dentry); |
| 250 | if (IS_ERR(newmnt)) { |
| 251 | path_release(nd); |
| 252 | return PTR_ERR(newmnt); |
| 253 | } |
| 254 | |
| 255 | old_dentry = nd->dentry; |
| 256 | nd->dentry = dentry; |
| 257 | err = do_add_mount(newmnt, nd, 0, &afs_vfsmounts); |
| 258 | nd->dentry = old_dentry; |
| 259 | |
| 260 | path_release(nd); |
| 261 | |
| 262 | if (!err) { |
| 263 | mntget(newmnt); |
| 264 | nd->mnt = newmnt; |
| 265 | dget(newmnt->mnt_root); |
| 266 | nd->dentry = newmnt->mnt_root; |
| 267 | } |
| 268 | |
| 269 | kleave(" = %d", err); |
| 270 | return err; |
| 271 | } /* end afs_mntpt_follow_link() */ |
| 272 | |
| 273 | /*****************************************************************************/ |
| 274 | /* |
| 275 | * handle mountpoint expiry timer going off |
| 276 | */ |
| 277 | static void afs_mntpt_expiry_timed_out(struct afs_timer *timer) |
| 278 | { |
| 279 | kenter(""); |
| 280 | |
| 281 | mark_mounts_for_expiry(&afs_vfsmounts); |
| 282 | |
| 283 | afs_kafstimod_add_timer(&afs_mntpt_expiry_timer, |
| 284 | afs_mntpt_expiry_timeout * HZ); |
| 285 | |
| 286 | kleave(""); |
| 287 | } /* end afs_mntpt_expiry_timed_out() */ |