Commit | Line | Data |
---|---|---|
ec26815a | 1 | /* mountpoint management |
1da177e4 LT |
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> | |
1da177e4 LT |
15 | #include <linux/slab.h> |
16 | #include <linux/fs.h> | |
17 | #include <linux/pagemap.h> | |
18 | #include <linux/mount.h> | |
19 | #include <linux/namei.h> | |
6b3286ed | 20 | #include <linux/mnt_namespace.h> |
1da177e4 LT |
21 | #include "internal.h" |
22 | ||
23 | ||
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); | |
008b150a | 28 | static void *afs_mntpt_follow_link(struct dentry *dentry, struct nameidata *nd); |
08e0e7c8 | 29 | static void afs_mntpt_expiry_timed_out(struct work_struct *work); |
1da177e4 | 30 | |
4b6f5d20 | 31 | const struct file_operations afs_mntpt_file_operations = { |
1da177e4 LT |
32 | .open = afs_mntpt_open, |
33 | }; | |
34 | ||
754661f1 | 35 | const struct inode_operations afs_mntpt_inode_operations = { |
1da177e4 LT |
36 | .lookup = afs_mntpt_lookup, |
37 | .follow_link = afs_mntpt_follow_link, | |
38 | .readlink = page_readlink, | |
39 | .getattr = afs_inode_getattr, | |
40 | }; | |
41 | ||
42 | static LIST_HEAD(afs_vfsmounts); | |
08e0e7c8 | 43 | static DECLARE_DELAYED_WORK(afs_mntpt_expiry_timer, afs_mntpt_expiry_timed_out); |
1da177e4 | 44 | |
08e0e7c8 | 45 | unsigned long afs_mntpt_expiry_timeout = 10 * 60; |
1da177e4 | 46 | |
1da177e4 LT |
47 | /* |
48 | * check a symbolic link to see whether it actually encodes a mountpoint | |
49 | * - sets the AFS_VNODE_MOUNTPOINT flag on the vnode appropriately | |
50 | */ | |
00d3b7a4 | 51 | int afs_mntpt_check_symlink(struct afs_vnode *vnode, struct key *key) |
1da177e4 | 52 | { |
00d3b7a4 DH |
53 | struct file file = { |
54 | .private_data = key, | |
55 | }; | |
1da177e4 | 56 | struct page *page; |
1da177e4 LT |
57 | size_t size; |
58 | char *buf; | |
59 | int ret; | |
60 | ||
61 | _enter("{%u,%u}", vnode->fid.vnode, vnode->fid.unique); | |
62 | ||
63 | /* read the contents of the symlink into the pagecache */ | |
00d3b7a4 | 64 | page = read_mapping_page(AFS_VNODE_TO_I(vnode)->i_mapping, 0, &file); |
1da177e4 LT |
65 | if (IS_ERR(page)) { |
66 | ret = PTR_ERR(page); | |
67 | goto out; | |
68 | } | |
69 | ||
70 | ret = -EIO; | |
71 | wait_on_page_locked(page); | |
72 | buf = kmap(page); | |
73 | if (!PageUptodate(page)) | |
74 | goto out_free; | |
75 | if (PageError(page)) | |
76 | goto out_free; | |
77 | ||
78 | /* examine the symlink's contents */ | |
79 | size = vnode->status.size; | |
08e0e7c8 | 80 | _debug("symlink to %*.*s", (int) size, (int) size, buf); |
1da177e4 LT |
81 | |
82 | if (size > 2 && | |
83 | (buf[0] == '%' || buf[0] == '#') && | |
84 | buf[size - 1] == '.' | |
85 | ) { | |
86 | _debug("symlink is a mountpoint"); | |
87 | spin_lock(&vnode->lock); | |
08e0e7c8 | 88 | set_bit(AFS_VNODE_MOUNTPOINT, &vnode->flags); |
1da177e4 LT |
89 | spin_unlock(&vnode->lock); |
90 | } | |
91 | ||
92 | ret = 0; | |
93 | ||
ec26815a | 94 | out_free: |
1da177e4 LT |
95 | kunmap(page); |
96 | page_cache_release(page); | |
ec26815a | 97 | out: |
1da177e4 LT |
98 | _leave(" = %d", ret); |
99 | return ret; | |
ec26815a | 100 | } |
1da177e4 | 101 | |
1da177e4 LT |
102 | /* |
103 | * no valid lookup procedure on this sort of dir | |
104 | */ | |
105 | static struct dentry *afs_mntpt_lookup(struct inode *dir, | |
106 | struct dentry *dentry, | |
107 | struct nameidata *nd) | |
108 | { | |
08e0e7c8 | 109 | _enter("%p,%p{%p{%s},%s}", |
1da177e4 LT |
110 | dir, |
111 | dentry, | |
112 | dentry->d_parent, | |
113 | dentry->d_parent ? | |
114 | dentry->d_parent->d_name.name : (const unsigned char *) "", | |
115 | dentry->d_name.name); | |
116 | ||
117 | return ERR_PTR(-EREMOTE); | |
ec26815a | 118 | } |
1da177e4 | 119 | |
1da177e4 LT |
120 | /* |
121 | * no valid open procedure on this sort of dir | |
122 | */ | |
123 | static int afs_mntpt_open(struct inode *inode, struct file *file) | |
124 | { | |
08e0e7c8 | 125 | _enter("%p,%p{%p{%s},%s}", |
1da177e4 | 126 | inode, file, |
1d56a969 JS |
127 | file->f_path.dentry->d_parent, |
128 | file->f_path.dentry->d_parent ? | |
129 | file->f_path.dentry->d_parent->d_name.name : | |
1da177e4 | 130 | (const unsigned char *) "", |
1d56a969 | 131 | file->f_path.dentry->d_name.name); |
1da177e4 LT |
132 | |
133 | return -EREMOTE; | |
ec26815a | 134 | } |
1da177e4 | 135 | |
1da177e4 LT |
136 | /* |
137 | * create a vfsmount to be automounted | |
138 | */ | |
139 | static struct vfsmount *afs_mntpt_do_automount(struct dentry *mntpt) | |
140 | { | |
141 | struct afs_super_info *super; | |
142 | struct vfsmount *mnt; | |
143 | struct page *page = NULL; | |
144 | size_t size; | |
145 | char *buf, *devname = NULL, *options = NULL; | |
1da177e4 LT |
146 | int ret; |
147 | ||
08e0e7c8 | 148 | _enter("{%s}", mntpt->d_name.name); |
1da177e4 LT |
149 | |
150 | BUG_ON(!mntpt->d_inode); | |
151 | ||
152 | ret = -EINVAL; | |
153 | size = mntpt->d_inode->i_size; | |
154 | if (size > PAGE_SIZE - 1) | |
155 | goto error; | |
156 | ||
157 | ret = -ENOMEM; | |
158 | devname = (char *) get_zeroed_page(GFP_KERNEL); | |
159 | if (!devname) | |
160 | goto error; | |
161 | ||
162 | options = (char *) get_zeroed_page(GFP_KERNEL); | |
163 | if (!options) | |
164 | goto error; | |
165 | ||
166 | /* read the contents of the AFS special symlink */ | |
090d2b18 | 167 | page = read_mapping_page(mntpt->d_inode->i_mapping, 0, NULL); |
1da177e4 LT |
168 | if (IS_ERR(page)) { |
169 | ret = PTR_ERR(page); | |
170 | goto error; | |
171 | } | |
172 | ||
173 | ret = -EIO; | |
174 | wait_on_page_locked(page); | |
175 | if (!PageUptodate(page) || PageError(page)) | |
176 | goto error; | |
177 | ||
178 | buf = kmap(page); | |
179 | memcpy(devname, buf, size); | |
180 | kunmap(page); | |
181 | page_cache_release(page); | |
182 | page = NULL; | |
183 | ||
184 | /* work out what options we want */ | |
185 | super = AFS_FS_S(mntpt->d_sb); | |
186 | memcpy(options, "cell=", 5); | |
187 | strcpy(options + 5, super->volume->cell->name); | |
188 | if (super->volume->type == AFSVL_RWVOL) | |
189 | strcat(options, ",rwpath"); | |
190 | ||
191 | /* try and do the mount */ | |
08e0e7c8 | 192 | _debug("--- attempting mount %s -o %s ---", devname, options); |
1f5ce9e9 | 193 | mnt = vfs_kern_mount(&afs_fs_type, 0, devname, options); |
08e0e7c8 | 194 | _debug("--- mount result %p ---", mnt); |
1da177e4 LT |
195 | |
196 | free_page((unsigned long) devname); | |
197 | free_page((unsigned long) options); | |
08e0e7c8 | 198 | _leave(" = %p", mnt); |
1da177e4 LT |
199 | return mnt; |
200 | ||
ec26815a | 201 | error: |
1da177e4 LT |
202 | if (page) |
203 | page_cache_release(page); | |
204 | if (devname) | |
205 | free_page((unsigned long) devname); | |
206 | if (options) | |
207 | free_page((unsigned long) options); | |
08e0e7c8 | 208 | _leave(" = %d", ret); |
1da177e4 | 209 | return ERR_PTR(ret); |
ec26815a | 210 | } |
1da177e4 | 211 | |
1da177e4 LT |
212 | /* |
213 | * follow a link from a mountpoint directory, thus causing it to be mounted | |
214 | */ | |
008b150a | 215 | static void *afs_mntpt_follow_link(struct dentry *dentry, struct nameidata *nd) |
1da177e4 LT |
216 | { |
217 | struct vfsmount *newmnt; | |
1da177e4 LT |
218 | int err; |
219 | ||
00d3b7a4 | 220 | _enter("%p{%s},{%s:%p{%s},}", |
1da177e4 LT |
221 | dentry, |
222 | dentry->d_name.name, | |
223 | nd->mnt->mnt_devname, | |
224 | dentry, | |
225 | nd->dentry->d_name.name); | |
226 | ||
08e0e7c8 DH |
227 | dput(nd->dentry); |
228 | nd->dentry = dget(dentry); | |
229 | ||
230 | newmnt = afs_mntpt_do_automount(nd->dentry); | |
1da177e4 LT |
231 | if (IS_ERR(newmnt)) { |
232 | path_release(nd); | |
008b150a | 233 | return (void *)newmnt; |
1da177e4 LT |
234 | } |
235 | ||
08e0e7c8 DH |
236 | mntget(newmnt); |
237 | err = do_add_mount(newmnt, nd, MNT_SHRINKABLE, &afs_vfsmounts); | |
238 | switch (err) { | |
239 | case 0: | |
00d3b7a4 DH |
240 | mntput(nd->mnt); |
241 | dput(nd->dentry); | |
1da177e4 | 242 | nd->mnt = newmnt; |
08e0e7c8 DH |
243 | nd->dentry = dget(newmnt->mnt_root); |
244 | schedule_delayed_work(&afs_mntpt_expiry_timer, | |
245 | afs_mntpt_expiry_timeout * HZ); | |
246 | break; | |
247 | case -EBUSY: | |
248 | /* someone else made a mount here whilst we were busy */ | |
249 | while (d_mountpoint(nd->dentry) && | |
250 | follow_down(&nd->mnt, &nd->dentry)) | |
251 | ; | |
252 | err = 0; | |
253 | default: | |
254 | mntput(newmnt); | |
255 | break; | |
1da177e4 LT |
256 | } |
257 | ||
08e0e7c8 | 258 | _leave(" = %d", err); |
008b150a | 259 | return ERR_PTR(err); |
ec26815a | 260 | } |
1da177e4 | 261 | |
1da177e4 LT |
262 | /* |
263 | * handle mountpoint expiry timer going off | |
264 | */ | |
08e0e7c8 | 265 | static void afs_mntpt_expiry_timed_out(struct work_struct *work) |
1da177e4 | 266 | { |
08e0e7c8 DH |
267 | _enter(""); |
268 | ||
269 | if (!list_empty(&afs_vfsmounts)) { | |
270 | mark_mounts_for_expiry(&afs_vfsmounts); | |
271 | schedule_delayed_work(&afs_mntpt_expiry_timer, | |
272 | afs_mntpt_expiry_timeout * HZ); | |
273 | } | |
274 | ||
275 | _leave(""); | |
276 | } | |
1da177e4 | 277 | |
08e0e7c8 DH |
278 | /* |
279 | * kill the AFS mountpoint timer if it's still running | |
280 | */ | |
281 | void afs_mntpt_kill_timer(void) | |
282 | { | |
283 | _enter(""); | |
1da177e4 | 284 | |
08e0e7c8 DH |
285 | ASSERT(list_empty(&afs_vfsmounts)); |
286 | cancel_delayed_work(&afs_mntpt_expiry_timer); | |
287 | flush_scheduled_work(); | |
288 | } | |
1da177e4 | 289 | |
08e0e7c8 DH |
290 | /* |
291 | * begin unmount by attempting to remove all automounted mountpoints we added | |
292 | */ | |
293 | void afs_umount_begin(struct vfsmount *vfsmnt, int flags) | |
294 | { | |
295 | shrink_submounts(vfsmnt, &afs_vfsmounts); | |
ec26815a | 296 | } |