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
);