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>
15 #include <linux/slab.h>
17 #include <linux/pagemap.h>
18 #include <linux/mount.h>
19 #include <linux/namei.h>
20 #include <linux/mnt_namespace.h>
24 static struct dentry *afs_mntpt_lookup(struct inode *dir,
25 struct dentry *dentry,
26 struct nameidata *nd);
27 static int afs_mntpt_open(struct inode *inode, struct file *file);
28 static void *afs_mntpt_follow_link(struct dentry *dentry, struct nameidata *nd);
29 static void afs_mntpt_expiry_timed_out(struct work_struct *work);
31 const struct file_operations afs_mntpt_file_operations = {
32 .open = afs_mntpt_open,
35 const struct inode_operations afs_mntpt_inode_operations = {
36 .lookup = afs_mntpt_lookup,
37 .follow_link = afs_mntpt_follow_link,
38 .readlink = page_readlink,
39 .getattr = afs_inode_getattr,
42 static LIST_HEAD(afs_vfsmounts);
43 static DECLARE_DELAYED_WORK(afs_mntpt_expiry_timer, afs_mntpt_expiry_timed_out);
45 unsigned long afs_mntpt_expiry_timeout = 10 * 60;
48 * check a symbolic link to see whether it actually encodes a mountpoint
49 * - sets the AFS_VNODE_MOUNTPOINT flag on the vnode appropriately
51 int afs_mntpt_check_symlink(struct afs_vnode *vnode)
58 _enter("{%u,%u}", vnode->fid.vnode, vnode->fid.unique);
60 /* read the contents of the symlink into the pagecache */
61 page = read_mapping_page(AFS_VNODE_TO_I(vnode)->i_mapping, 0, NULL);
68 wait_on_page_locked(page);
70 if (!PageUptodate(page))
75 /* examine the symlink's contents */
76 size = vnode->status.size;
77 _debug("symlink to %*.*s", (int) size, (int) size, buf);
80 (buf[0] == '%' || buf[0] == '#') &&
83 _debug("symlink is a mountpoint");
84 spin_lock(&vnode->lock);
85 set_bit(AFS_VNODE_MOUNTPOINT, &vnode->flags);
86 spin_unlock(&vnode->lock);
93 page_cache_release(page);
100 * no valid lookup procedure on this sort of dir
102 static struct dentry *afs_mntpt_lookup(struct inode *dir,
103 struct dentry *dentry,
104 struct nameidata *nd)
106 _enter("%p,%p{%p{%s},%s}",
111 dentry->d_parent->d_name.name : (const unsigned char *) "",
112 dentry->d_name.name);
114 return ERR_PTR(-EREMOTE);
118 * no valid open procedure on this sort of dir
120 static int afs_mntpt_open(struct inode *inode, struct file *file)
122 _enter("%p,%p{%p{%s},%s}",
124 file->f_path.dentry->d_parent,
125 file->f_path.dentry->d_parent ?
126 file->f_path.dentry->d_parent->d_name.name :
127 (const unsigned char *) "",
128 file->f_path.dentry->d_name.name);
134 * create a vfsmount to be automounted
136 static struct vfsmount *afs_mntpt_do_automount(struct dentry *mntpt)
138 struct afs_super_info *super;
139 struct vfsmount *mnt;
140 struct page *page = NULL;
142 char *buf, *devname = NULL, *options = NULL;
145 _enter("{%s}", mntpt->d_name.name);
147 BUG_ON(!mntpt->d_inode);
150 size = mntpt->d_inode->i_size;
151 if (size > PAGE_SIZE - 1)
155 devname = (char *) get_zeroed_page(GFP_KERNEL);
159 options = (char *) get_zeroed_page(GFP_KERNEL);
163 /* read the contents of the AFS special symlink */
164 page = read_mapping_page(mntpt->d_inode->i_mapping, 0, NULL);
171 wait_on_page_locked(page);
172 if (!PageUptodate(page) || PageError(page))
176 memcpy(devname, buf, size);
178 page_cache_release(page);
181 /* work out what options we want */
182 super = AFS_FS_S(mntpt->d_sb);
183 memcpy(options, "cell=", 5);
184 strcpy(options + 5, super->volume->cell->name);
185 if (super->volume->type == AFSVL_RWVOL)
186 strcat(options, ",rwpath");
188 /* try and do the mount */
189 _debug("--- attempting mount %s -o %s ---", devname, options);
190 mnt = vfs_kern_mount(&afs_fs_type, 0, devname, options);
191 _debug("--- mount result %p ---", mnt);
193 free_page((unsigned long) devname);
194 free_page((unsigned long) options);
195 _leave(" = %p", mnt);
200 page_cache_release(page);
202 free_page((unsigned long) devname);
204 free_page((unsigned long) options);
205 _leave(" = %d", ret);
210 * follow a link from a mountpoint directory, thus causing it to be mounted
212 static void *afs_mntpt_follow_link(struct dentry *dentry, struct nameidata *nd)
214 struct vfsmount *newmnt;
217 _enter("%p{%s},{%s:%p{%s}}",
220 nd->mnt->mnt_devname,
222 nd->dentry->d_name.name);
225 nd->dentry = dget(dentry);
227 newmnt = afs_mntpt_do_automount(nd->dentry);
228 if (IS_ERR(newmnt)) {
230 return (void *)newmnt;
234 err = do_add_mount(newmnt, nd, MNT_SHRINKABLE, &afs_vfsmounts);
239 nd->dentry = dget(newmnt->mnt_root);
240 schedule_delayed_work(&afs_mntpt_expiry_timer,
241 afs_mntpt_expiry_timeout * HZ);
244 /* someone else made a mount here whilst we were busy */
245 while (d_mountpoint(nd->dentry) &&
246 follow_down(&nd->mnt, &nd->dentry))
254 _leave(" = %d", err);
259 * handle mountpoint expiry timer going off
261 static void afs_mntpt_expiry_timed_out(struct work_struct *work)
265 if (!list_empty(&afs_vfsmounts)) {
266 mark_mounts_for_expiry(&afs_vfsmounts);
267 schedule_delayed_work(&afs_mntpt_expiry_timer,
268 afs_mntpt_expiry_timeout * HZ);
275 * kill the AFS mountpoint timer if it's still running
277 void afs_mntpt_kill_timer(void)
281 ASSERT(list_empty(&afs_vfsmounts));
282 cancel_delayed_work(&afs_mntpt_expiry_timer);
283 flush_scheduled_work();
287 * begin unmount by attempting to remove all automounted mountpoints we added
289 void afs_umount_begin(struct vfsmount *vfsmnt, int flags)
291 shrink_submounts(vfsmnt, &afs_vfsmounts);