1 /* mountpoint management
3 * Copyright (C) 2002 Red Hat, Inc. All Rights Reserved.
4 * Written by David Howells (dhowells@redhat.com)
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.
12 #include <linux/kernel.h>
13 #include <linux/module.h>
14 #include <linux/init.h>
16 #include <linux/pagemap.h>
17 #include <linux/mount.h>
18 #include <linux/namei.h>
19 #include <linux/gfp.h>
23 static struct dentry *afs_mntpt_lookup(struct inode *dir,
24 struct dentry *dentry,
25 struct nameidata *nd);
26 static int afs_mntpt_open(struct inode *inode, struct file *file);
27 static void *afs_mntpt_follow_link(struct dentry *dentry, struct nameidata *nd);
28 static void afs_mntpt_expiry_timed_out(struct work_struct *work);
30 const struct file_operations afs_mntpt_file_operations = {
31 .open = afs_mntpt_open,
34 const struct inode_operations afs_mntpt_inode_operations = {
35 .lookup = afs_mntpt_lookup,
36 .follow_link = afs_mntpt_follow_link,
37 .readlink = page_readlink,
38 .getattr = afs_getattr,
41 const struct inode_operations afs_autocell_inode_operations = {
42 .follow_link = afs_mntpt_follow_link,
43 .getattr = afs_getattr,
46 static LIST_HEAD(afs_vfsmounts);
47 static DECLARE_DELAYED_WORK(afs_mntpt_expiry_timer, afs_mntpt_expiry_timed_out);
49 static unsigned long afs_mntpt_expiry_timeout = 10 * 60;
52 * check a symbolic link to see whether it actually encodes a mountpoint
53 * - sets the AFS_VNODE_MOUNTPOINT flag on the vnode appropriately
55 int afs_mntpt_check_symlink(struct afs_vnode *vnode, struct key *key)
63 vnode->fid.vid, vnode->fid.vnode, vnode->fid.unique);
65 /* read the contents of the symlink into the pagecache */
66 page = read_cache_page(AFS_VNODE_TO_I(vnode)->i_mapping, 0,
67 afs_page_filler, key);
79 /* examine the symlink's contents */
80 size = vnode->status.size;
81 _debug("symlink to %*.*s", (int) size, (int) size, buf);
84 (buf[0] == '%' || buf[0] == '#') &&
87 _debug("symlink is a mountpoint");
88 spin_lock(&vnode->lock);
89 set_bit(AFS_VNODE_MOUNTPOINT, &vnode->flags);
90 spin_unlock(&vnode->lock);
97 page_cache_release(page);
104 * no valid lookup procedure on this sort of dir
106 static struct dentry *afs_mntpt_lookup(struct inode *dir,
107 struct dentry *dentry,
108 struct nameidata *nd)
110 _enter("%p,%p{%p{%s},%s}",
115 dentry->d_parent->d_name.name : (const unsigned char *) "",
116 dentry->d_name.name);
118 return ERR_PTR(-EREMOTE);
122 * no valid open procedure on this sort of dir
124 static int afs_mntpt_open(struct inode *inode, struct file *file)
126 _enter("%p,%p{%p{%s},%s}",
128 file->f_path.dentry->d_parent,
129 file->f_path.dentry->d_parent ?
130 file->f_path.dentry->d_parent->d_name.name :
131 (const unsigned char *) "",
132 file->f_path.dentry->d_name.name);
138 * create a vfsmount to be automounted
140 static struct vfsmount *afs_mntpt_do_automount(struct dentry *mntpt)
142 struct afs_super_info *super;
143 struct vfsmount *mnt;
144 struct afs_vnode *vnode;
146 char *devname, *options;
150 _enter("{%s}", mntpt->d_name.name);
152 BUG_ON(!mntpt->d_inode);
155 devname = (char *) get_zeroed_page(GFP_KERNEL);
157 goto error_no_devname;
159 options = (char *) get_zeroed_page(GFP_KERNEL);
161 goto error_no_options;
163 vnode = AFS_FS_I(mntpt->d_inode);
164 if (test_bit(AFS_VNODE_PSEUDODIR, &vnode->flags)) {
165 /* if the directory is a pseudo directory, use the d_name */
166 static const char afs_root_cell[] = ":root.cell.";
167 unsigned size = mntpt->d_name.len;
170 if (size < 2 || size > AFS_MAXCELLNAME)
173 if (mntpt->d_name.name[0] == '.') {
175 memcpy(devname + 1, mntpt->d_name.name, size - 1);
176 memcpy(devname + size, afs_root_cell,
177 sizeof(afs_root_cell));
181 memcpy(devname + 1, mntpt->d_name.name, size);
182 memcpy(devname + size + 1, afs_root_cell,
183 sizeof(afs_root_cell));
186 /* read the contents of the AFS special symlink */
187 loff_t size = i_size_read(mntpt->d_inode);
191 if (size > PAGE_SIZE - 1)
194 page = read_mapping_page(mntpt->d_inode->i_mapping, 0, NULL);
204 buf = kmap_atomic(page, KM_USER0);
205 memcpy(devname, buf, size);
206 kunmap_atomic(buf, KM_USER0);
207 page_cache_release(page);
211 /* work out what options we want */
212 super = AFS_FS_S(mntpt->d_sb);
213 memcpy(options, "cell=", 5);
214 strcpy(options + 5, super->volume->cell->name);
215 if (super->volume->type == AFSVL_RWVOL || rwpath)
216 strcat(options, ",rwpath");
218 /* try and do the mount */
219 _debug("--- attempting mount %s -o %s ---", devname, options);
220 mnt = vfs_kern_mount(&afs_fs_type, 0, devname, options);
221 _debug("--- mount result %p ---", mnt);
223 free_page((unsigned long) devname);
224 free_page((unsigned long) options);
225 _leave(" = %p", mnt);
229 page_cache_release(page);
231 free_page((unsigned long) options);
233 free_page((unsigned long) devname);
235 _leave(" = %d", ret);
240 * follow a link from a mountpoint directory, thus causing it to be mounted
242 static void *afs_mntpt_follow_link(struct dentry *dentry, struct nameidata *nd)
244 struct vfsmount *newmnt;
247 _enter("%p{%s},{%s:%p{%s},}",
250 nd->path.mnt->mnt_devname,
252 nd->path.dentry->d_name.name);
254 dput(nd->path.dentry);
255 nd->path.dentry = dget(dentry);
257 newmnt = afs_mntpt_do_automount(nd->path.dentry);
258 if (IS_ERR(newmnt)) {
260 return (void *)newmnt;
264 err = do_add_mount(newmnt, &nd->path, MNT_SHRINKABLE, &afs_vfsmounts);
268 nd->path.mnt = newmnt;
269 nd->path.dentry = dget(newmnt->mnt_root);
270 schedule_delayed_work(&afs_mntpt_expiry_timer,
271 afs_mntpt_expiry_timeout * HZ);
274 /* someone else made a mount here whilst we were busy */
275 while (d_mountpoint(nd->path.dentry) &&
276 follow_down(&nd->path))
284 _leave(" = %d", err);
289 * handle mountpoint expiry timer going off
291 static void afs_mntpt_expiry_timed_out(struct work_struct *work)
295 if (!list_empty(&afs_vfsmounts)) {
296 mark_mounts_for_expiry(&afs_vfsmounts);
297 schedule_delayed_work(&afs_mntpt_expiry_timer,
298 afs_mntpt_expiry_timeout * HZ);
305 * kill the AFS mountpoint timer if it's still running
307 void afs_mntpt_kill_timer(void)
311 ASSERT(list_empty(&afs_vfsmounts));
312 cancel_delayed_work(&afs_mntpt_expiry_timer);
313 flush_scheduled_work();