ia64/linux-2.6.18-xen.hg

view fs/afs/mntpt.c @ 524:7f8b544237bf

netfront: Allow netfront in domain 0.

This is useful if your physical network device is in a utility domain.

Signed-off-by: Ian Campbell <ian.campbell@citrix.com>
author Keir Fraser <keir.fraser@citrix.com>
date Tue Apr 15 15:18:58 2008 +0100 (2008-04-15)
parents 831230e53067
children
line source
1 /* mntpt.c: 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 */
12 #include <linux/kernel.h>
13 #include <linux/module.h>
14 #include <linux/init.h>
15 #include <linux/sched.h>
16 #include <linux/slab.h>
17 #include <linux/fs.h>
18 #include <linux/pagemap.h>
19 #include <linux/mount.h>
20 #include <linux/namei.h>
21 #include <linux/namespace.h>
22 #include "super.h"
23 #include "cell.h"
24 #include "volume.h"
25 #include "vnode.h"
26 #include "internal.h"
29 static struct dentry *afs_mntpt_lookup(struct inode *dir,
30 struct dentry *dentry,
31 struct nameidata *nd);
32 static int afs_mntpt_open(struct inode *inode, struct file *file);
33 static void *afs_mntpt_follow_link(struct dentry *dentry, struct nameidata *nd);
35 const struct file_operations afs_mntpt_file_operations = {
36 .open = afs_mntpt_open,
37 };
39 struct inode_operations afs_mntpt_inode_operations = {
40 .lookup = afs_mntpt_lookup,
41 .follow_link = afs_mntpt_follow_link,
42 .readlink = page_readlink,
43 .getattr = afs_inode_getattr,
44 };
46 static LIST_HEAD(afs_vfsmounts);
48 static void afs_mntpt_expiry_timed_out(struct afs_timer *timer);
50 struct afs_timer_ops afs_mntpt_expiry_timer_ops = {
51 .timed_out = afs_mntpt_expiry_timed_out,
52 };
54 struct afs_timer afs_mntpt_expiry_timer;
56 unsigned long afs_mntpt_expiry_timeout = 20;
58 /*****************************************************************************/
59 /*
60 * check a symbolic link to see whether it actually encodes a mountpoint
61 * - sets the AFS_VNODE_MOUNTPOINT flag on the vnode appropriately
62 */
63 int afs_mntpt_check_symlink(struct afs_vnode *vnode)
64 {
65 struct page *page;
66 size_t size;
67 char *buf;
68 int ret;
70 _enter("{%u,%u}", vnode->fid.vnode, vnode->fid.unique);
72 /* read the contents of the symlink into the pagecache */
73 page = read_mapping_page(AFS_VNODE_TO_I(vnode)->i_mapping, 0, NULL);
74 if (IS_ERR(page)) {
75 ret = PTR_ERR(page);
76 goto out;
77 }
79 ret = -EIO;
80 wait_on_page_locked(page);
81 buf = kmap(page);
82 if (!PageUptodate(page))
83 goto out_free;
84 if (PageError(page))
85 goto out_free;
87 /* examine the symlink's contents */
88 size = vnode->status.size;
89 _debug("symlink to %*.*s", size, (int) size, buf);
91 if (size > 2 &&
92 (buf[0] == '%' || buf[0] == '#') &&
93 buf[size - 1] == '.'
94 ) {
95 _debug("symlink is a mountpoint");
96 spin_lock(&vnode->lock);
97 vnode->flags |= AFS_VNODE_MOUNTPOINT;
98 spin_unlock(&vnode->lock);
99 }
101 ret = 0;
103 out_free:
104 kunmap(page);
105 page_cache_release(page);
106 out:
107 _leave(" = %d", ret);
108 return ret;
110 } /* end afs_mntpt_check_symlink() */
112 /*****************************************************************************/
113 /*
114 * no valid lookup procedure on this sort of dir
115 */
116 static struct dentry *afs_mntpt_lookup(struct inode *dir,
117 struct dentry *dentry,
118 struct nameidata *nd)
119 {
120 kenter("%p,%p{%p{%s},%s}",
121 dir,
122 dentry,
123 dentry->d_parent,
124 dentry->d_parent ?
125 dentry->d_parent->d_name.name : (const unsigned char *) "",
126 dentry->d_name.name);
128 return ERR_PTR(-EREMOTE);
129 } /* end afs_mntpt_lookup() */
131 /*****************************************************************************/
132 /*
133 * no valid open procedure on this sort of dir
134 */
135 static int afs_mntpt_open(struct inode *inode, struct file *file)
136 {
137 kenter("%p,%p{%p{%s},%s}",
138 inode, file,
139 file->f_dentry->d_parent,
140 file->f_dentry->d_parent ?
141 file->f_dentry->d_parent->d_name.name :
142 (const unsigned char *) "",
143 file->f_dentry->d_name.name);
145 return -EREMOTE;
146 } /* end afs_mntpt_open() */
148 /*****************************************************************************/
149 /*
150 * create a vfsmount to be automounted
151 */
152 static struct vfsmount *afs_mntpt_do_automount(struct dentry *mntpt)
153 {
154 struct afs_super_info *super;
155 struct vfsmount *mnt;
156 struct page *page = NULL;
157 size_t size;
158 char *buf, *devname = NULL, *options = NULL;
159 int ret;
161 kenter("{%s}", mntpt->d_name.name);
163 BUG_ON(!mntpt->d_inode);
165 ret = -EINVAL;
166 size = mntpt->d_inode->i_size;
167 if (size > PAGE_SIZE - 1)
168 goto error;
170 ret = -ENOMEM;
171 devname = (char *) get_zeroed_page(GFP_KERNEL);
172 if (!devname)
173 goto error;
175 options = (char *) get_zeroed_page(GFP_KERNEL);
176 if (!options)
177 goto error;
179 /* read the contents of the AFS special symlink */
180 page = read_mapping_page(mntpt->d_inode->i_mapping, 0, NULL);
181 if (IS_ERR(page)) {
182 ret = PTR_ERR(page);
183 goto error;
184 }
186 ret = -EIO;
187 wait_on_page_locked(page);
188 if (!PageUptodate(page) || PageError(page))
189 goto error;
191 buf = kmap(page);
192 memcpy(devname, buf, size);
193 kunmap(page);
194 page_cache_release(page);
195 page = NULL;
197 /* work out what options we want */
198 super = AFS_FS_S(mntpt->d_sb);
199 memcpy(options, "cell=", 5);
200 strcpy(options + 5, super->volume->cell->name);
201 if (super->volume->type == AFSVL_RWVOL)
202 strcat(options, ",rwpath");
204 /* try and do the mount */
205 kdebug("--- attempting mount %s -o %s ---", devname, options);
206 mnt = vfs_kern_mount(&afs_fs_type, 0, devname, options);
207 kdebug("--- mount result %p ---", mnt);
209 free_page((unsigned long) devname);
210 free_page((unsigned long) options);
211 kleave(" = %p", mnt);
212 return mnt;
214 error:
215 if (page)
216 page_cache_release(page);
217 if (devname)
218 free_page((unsigned long) devname);
219 if (options)
220 free_page((unsigned long) options);
221 kleave(" = %d", ret);
222 return ERR_PTR(ret);
223 } /* end afs_mntpt_do_automount() */
225 /*****************************************************************************/
226 /*
227 * follow a link from a mountpoint directory, thus causing it to be mounted
228 */
229 static void *afs_mntpt_follow_link(struct dentry *dentry, struct nameidata *nd)
230 {
231 struct vfsmount *newmnt;
232 struct dentry *old_dentry;
233 int err;
235 kenter("%p{%s},{%s:%p{%s}}",
236 dentry,
237 dentry->d_name.name,
238 nd->mnt->mnt_devname,
239 dentry,
240 nd->dentry->d_name.name);
242 newmnt = afs_mntpt_do_automount(dentry);
243 if (IS_ERR(newmnt)) {
244 path_release(nd);
245 return (void *)newmnt;
246 }
248 old_dentry = nd->dentry;
249 nd->dentry = dentry;
250 err = do_add_mount(newmnt, nd, 0, &afs_vfsmounts);
251 nd->dentry = old_dentry;
253 path_release(nd);
255 if (!err) {
256 mntget(newmnt);
257 nd->mnt = newmnt;
258 dget(newmnt->mnt_root);
259 nd->dentry = newmnt->mnt_root;
260 }
262 kleave(" = %d", err);
263 return ERR_PTR(err);
264 } /* end afs_mntpt_follow_link() */
266 /*****************************************************************************/
267 /*
268 * handle mountpoint expiry timer going off
269 */
270 static void afs_mntpt_expiry_timed_out(struct afs_timer *timer)
271 {
272 kenter("");
274 mark_mounts_for_expiry(&afs_vfsmounts);
276 afs_kafstimod_add_timer(&afs_mntpt_expiry_timer,
277 afs_mntpt_expiry_timeout * HZ);
279 kleave("");
280 } /* end afs_mntpt_expiry_timed_out() */