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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
23static struct dentry *afs_mntpt_lookup(struct inode *dir,
24 struct dentry *dentry,
25 struct nameidata *nd);
26static int afs_mntpt_open(struct inode *inode, struct file *file);
27static void afs_mntpt_expiry_timed_out(struct work_struct *work);
28
29const struct file_operations afs_mntpt_file_operations = {
30 .open = afs_mntpt_open,
31 .llseek = noop_llseek,
32};
33
34const struct inode_operations afs_mntpt_inode_operations = {
35 .lookup = afs_mntpt_lookup,
36 .readlink = page_readlink,
37 .getattr = afs_getattr,
38};
39
40const struct inode_operations afs_autocell_inode_operations = {
41 .getattr = afs_getattr,
42};
43
44static LIST_HEAD(afs_vfsmounts);
45static DECLARE_DELAYED_WORK(afs_mntpt_expiry_timer, afs_mntpt_expiry_timed_out);
46
47static 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 */
53int 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);
95out_free:
96 page_cache_release(page);
97out:
98 _leave(" = %d", ret);
99 return ret;
100}
101
102/*
103 * no valid lookup procedure on this sort of dir
104 */
105static 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 */
123static 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 */
139static 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);
204 memcpy(devname, buf, size);
205 kunmap_atomic(buf);
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
227error:
228 page_cache_release(page);
229error_no_page:
230 free_page((unsigned long) options);
231error_no_options:
232 free_page((unsigned long) devname);
233error_no_devname:
234 _leave(" = %d", ret);
235 return ERR_PTR(ret);
236}
237
238/*
239 * handle an automount point
240 */
241struct vfsmount *afs_d_automount(struct path *path)
242{
243 struct vfsmount *newmnt;
244
245 _enter("{%s}", 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", newmnt);
256 return newmnt;
257}
258
259/*
260 * handle mountpoint expiry timer going off
261 */
262static 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 */
278void 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}