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1 | /* 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/fs.h> |
16 | #include <linux/pagemap.h> |
17 | #include <linux/mount.h> |
18 | #include <linux/namei.h> |
19 | #include <linux/gfp.h> |
20 | #include "internal.h" |
21 | |
22 | |
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_expiry_timed_out(struct work_struct *work); |
28 | |
29 | const struct file_operations afs_mntpt_file_operations = { |
30 | .open = afs_mntpt_open, |
31 | .llseek = noop_llseek, |
32 | }; |
33 | |
34 | const struct inode_operations afs_mntpt_inode_operations = { |
35 | .lookup = afs_mntpt_lookup, |
36 | .readlink = page_readlink, |
37 | .getattr = afs_getattr, |
38 | }; |
39 | |
40 | const struct inode_operations afs_autocell_inode_operations = { |
41 | .getattr = afs_getattr, |
42 | }; |
43 | |
44 | static LIST_HEAD(afs_vfsmounts); |
45 | static DECLARE_DELAYED_WORK(afs_mntpt_expiry_timer, afs_mntpt_expiry_timed_out); |
46 | |
47 | static unsigned long afs_mntpt_expiry_timeout = 10 * 60; |
48 | |
49 | /* |
50 | * check a symbolic link to see whether it actually encodes a mountpoint |
51 | * - sets the AFS_VNODE_MOUNTPOINT flag on the vnode appropriately |
52 | */ |
53 | int afs_mntpt_check_symlink(struct afs_vnode *vnode, struct key *key) |
54 | { |
55 | struct page *page; |
56 | size_t size; |
57 | char *buf; |
58 | int ret; |
59 | |
60 | _enter("{%x:%u,%u}", |
61 | vnode->fid.vid, vnode->fid.vnode, vnode->fid.unique); |
62 | |
63 | /* read the contents of the symlink into the pagecache */ |
64 | page = read_cache_page(AFS_VNODE_TO_I(vnode)->i_mapping, 0, |
65 | afs_page_filler, key); |
66 | if (IS_ERR(page)) { |
67 | ret = PTR_ERR(page); |
68 | goto out; |
69 | } |
70 | |
71 | ret = -EIO; |
72 | if (PageError(page)) |
73 | goto out_free; |
74 | |
75 | buf = kmap(page); |
76 | |
77 | /* examine the symlink's contents */ |
78 | size = vnode->status.size; |
79 | _debug("symlink to %*.*s", (int) size, (int) size, buf); |
80 | |
81 | if (size > 2 && |
82 | (buf[0] == '%' || buf[0] == '#') && |
83 | buf[size - 1] == '.' |
84 | ) { |
85 | _debug("symlink is a mountpoint"); |
86 | spin_lock(&vnode->lock); |
87 | set_bit(AFS_VNODE_MOUNTPOINT, &vnode->flags); |
88 | vnode->vfs_inode.i_flags |= S_AUTOMOUNT; |
89 | spin_unlock(&vnode->lock); |
90 | } |
91 | |
92 | ret = 0; |
93 | |
94 | kunmap(page); |
95 | out_free: |
96 | page_cache_release(page); |
97 | out: |
98 | _leave(" = %d", ret); |
99 | return ret; |
100 | } |
101 | |
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 | { |
109 | _enter("%p,%p{%p{%s},%s}", |
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); |
118 | } |
119 | |
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 | { |
125 | _enter("%p,%p{%p{%s},%s}", |
126 | inode, file, |
127 | file->f_path.dentry->d_parent, |
128 | file->f_path.dentry->d_parent ? |
129 | file->f_path.dentry->d_parent->d_name.name : |
130 | (const unsigned char *) "", |
131 | file->f_path.dentry->d_name.name); |
132 | |
133 | return -EREMOTE; |
134 | } |
135 | |
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 afs_vnode *vnode; |
144 | struct page *page; |
145 | char *devname, *options; |
146 | bool rwpath = false; |
147 | int ret; |
148 | |
149 | _enter("{%s}", mntpt->d_name.name); |
150 | |
151 | BUG_ON(!mntpt->d_inode); |
152 | |
153 | ret = -ENOMEM; |
154 | devname = (char *) get_zeroed_page(GFP_KERNEL); |
155 | if (!devname) |
156 | goto error_no_devname; |
157 | |
158 | options = (char *) get_zeroed_page(GFP_KERNEL); |
159 | if (!options) |
160 | goto error_no_options; |
161 | |
162 | vnode = AFS_FS_I(mntpt->d_inode); |
163 | if (test_bit(AFS_VNODE_PSEUDODIR, &vnode->flags)) { |
164 | /* if the directory is a pseudo directory, use the d_name */ |
165 | static const char afs_root_cell[] = ":root.cell."; |
166 | unsigned size = mntpt->d_name.len; |
167 | |
168 | ret = -ENOENT; |
169 | if (size < 2 || size > AFS_MAXCELLNAME) |
170 | goto error_no_page; |
171 | |
172 | if (mntpt->d_name.name[0] == '.') { |
173 | devname[0] = '#'; |
174 | memcpy(devname + 1, mntpt->d_name.name, size - 1); |
175 | memcpy(devname + size, afs_root_cell, |
176 | sizeof(afs_root_cell)); |
177 | rwpath = true; |
178 | } else { |
179 | devname[0] = '%'; |
180 | memcpy(devname + 1, mntpt->d_name.name, size); |
181 | memcpy(devname + size + 1, afs_root_cell, |
182 | sizeof(afs_root_cell)); |
183 | } |
184 | } else { |
185 | /* read the contents of the AFS special symlink */ |
186 | loff_t size = i_size_read(mntpt->d_inode); |
187 | char *buf; |
188 | |
189 | ret = -EINVAL; |
190 | if (size > PAGE_SIZE - 1) |
191 | goto error_no_page; |
192 | |
193 | page = read_mapping_page(mntpt->d_inode->i_mapping, 0, NULL); |
194 | if (IS_ERR(page)) { |
195 | ret = PTR_ERR(page); |
196 | goto error_no_page; |
197 | } |
198 | |
199 | ret = -EIO; |
200 | if (PageError(page)) |
201 | goto error; |
202 | |
203 | buf = kmap_atomic(page, KM_USER0); |
204 | memcpy(devname, buf, size); |
205 | kunmap_atomic(buf, KM_USER0); |
206 | page_cache_release(page); |
207 | page = NULL; |
208 | } |
209 | |
210 | /* work out what options we want */ |
211 | super = AFS_FS_S(mntpt->d_sb); |
212 | memcpy(options, "cell=", 5); |
213 | strcpy(options + 5, super->volume->cell->name); |
214 | if (super->volume->type == AFSVL_RWVOL || rwpath) |
215 | strcat(options, ",rwpath"); |
216 | |
217 | /* try and do the mount */ |
218 | _debug("--- attempting mount %s -o %s ---", devname, options); |
219 | mnt = vfs_kern_mount(&afs_fs_type, 0, devname, options); |
220 | _debug("--- mount result %p ---", mnt); |
221 | |
222 | free_page((unsigned long) devname); |
223 | free_page((unsigned long) options); |
224 | _leave(" = %p", mnt); |
225 | return mnt; |
226 | |
227 | error: |
228 | page_cache_release(page); |
229 | error_no_page: |
230 | free_page((unsigned long) options); |
231 | error_no_options: |
232 | free_page((unsigned long) devname); |
233 | error_no_devname: |
234 | _leave(" = %d", ret); |
235 | return ERR_PTR(ret); |
236 | } |
237 | |
238 | /* |
239 | * handle an automount point |
240 | */ |
241 | struct vfsmount *afs_d_automount(struct path *path) |
242 | { |
243 | struct vfsmount *newmnt; |
244 | |
245 | _enter("{%s,%s}", path->mnt->mnt_devname, path->dentry->d_name.name); |
246 | |
247 | newmnt = afs_mntpt_do_automount(path->dentry); |
248 | if (IS_ERR(newmnt)) |
249 | return newmnt; |
250 | |
251 | mntget(newmnt); /* prevent immediate expiration */ |
252 | mnt_set_expiry(newmnt, &afs_vfsmounts); |
253 | queue_delayed_work(afs_wq, &afs_mntpt_expiry_timer, |
254 | afs_mntpt_expiry_timeout * HZ); |
255 | _leave(" = %p {%s}", newmnt, newmnt->mnt_devname); |
256 | return newmnt; |
257 | } |
258 | |
259 | /* |
260 | * handle mountpoint expiry timer going off |
261 | */ |
262 | static void afs_mntpt_expiry_timed_out(struct work_struct *work) |
263 | { |
264 | _enter(""); |
265 | |
266 | if (!list_empty(&afs_vfsmounts)) { |
267 | mark_mounts_for_expiry(&afs_vfsmounts); |
268 | queue_delayed_work(afs_wq, &afs_mntpt_expiry_timer, |
269 | afs_mntpt_expiry_timeout * HZ); |
270 | } |
271 | |
272 | _leave(""); |
273 | } |
274 | |
275 | /* |
276 | * kill the AFS mountpoint timer if it's still running |
277 | */ |
278 | void afs_mntpt_kill_timer(void) |
279 | { |
280 | _enter(""); |
281 | |
282 | ASSERT(list_empty(&afs_vfsmounts)); |
283 | cancel_delayed_work_sync(&afs_mntpt_expiry_timer); |
284 | } |
285 |
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