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Merge branch 'core-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel...
[mirror_ubuntu-bionic-kernel.git] / fs / nfs / namespace.c
1 /*
2 * linux/fs/nfs/namespace.c
3 *
4 * Copyright (C) 2005 Trond Myklebust <Trond.Myklebust@netapp.com>
5 * - Modified by David Howells <dhowells@redhat.com>
6 *
7 * NFS namespace
8 */
9
10 #include <linux/module.h>
11 #include <linux/dcache.h>
12 #include <linux/gfp.h>
13 #include <linux/mount.h>
14 #include <linux/namei.h>
15 #include <linux/nfs_fs.h>
16 #include <linux/string.h>
17 #include <linux/sunrpc/clnt.h>
18 #include <linux/vfs.h>
19 #include <linux/sunrpc/gss_api.h>
20 #include "internal.h"
21
22 #define NFSDBG_FACILITY NFSDBG_VFS
23
24 static void nfs_expire_automounts(struct work_struct *work);
25
26 static LIST_HEAD(nfs_automount_list);
27 static DECLARE_DELAYED_WORK(nfs_automount_task, nfs_expire_automounts);
28 int nfs_mountpoint_expiry_timeout = 500 * HZ;
29
30 /*
31 * nfs_path - reconstruct the path given an arbitrary dentry
32 * @base - used to return pointer to the end of devname part of path
33 * @dentry - pointer to dentry
34 * @buffer - result buffer
35 * @buflen - length of buffer
36 * @flags - options (see below)
37 *
38 * Helper function for constructing the server pathname
39 * by arbitrary hashed dentry.
40 *
41 * This is mainly for use in figuring out the path on the
42 * server side when automounting on top of an existing partition
43 * and in generating /proc/mounts and friends.
44 *
45 * Supported flags:
46 * NFS_PATH_CANONICAL: ensure there is exactly one slash after
47 * the original device (export) name
48 * (if unset, the original name is returned verbatim)
49 */
50 char *nfs_path(char **p, struct dentry *dentry, char *buffer, ssize_t buflen,
51 unsigned flags)
52 {
53 char *end;
54 int namelen;
55 unsigned seq;
56 const char *base;
57
58 rename_retry:
59 end = buffer+buflen;
60 *--end = '\0';
61 buflen--;
62
63 seq = read_seqbegin(&rename_lock);
64 rcu_read_lock();
65 while (1) {
66 spin_lock(&dentry->d_lock);
67 if (IS_ROOT(dentry))
68 break;
69 namelen = dentry->d_name.len;
70 buflen -= namelen + 1;
71 if (buflen < 0)
72 goto Elong_unlock;
73 end -= namelen;
74 memcpy(end, dentry->d_name.name, namelen);
75 *--end = '/';
76 spin_unlock(&dentry->d_lock);
77 dentry = dentry->d_parent;
78 }
79 if (read_seqretry(&rename_lock, seq)) {
80 spin_unlock(&dentry->d_lock);
81 rcu_read_unlock();
82 goto rename_retry;
83 }
84 if ((flags & NFS_PATH_CANONICAL) && *end != '/') {
85 if (--buflen < 0) {
86 spin_unlock(&dentry->d_lock);
87 rcu_read_unlock();
88 goto Elong;
89 }
90 *--end = '/';
91 }
92 *p = end;
93 base = dentry->d_fsdata;
94 if (!base) {
95 spin_unlock(&dentry->d_lock);
96 rcu_read_unlock();
97 WARN_ON(1);
98 return end;
99 }
100 namelen = strlen(base);
101 if (flags & NFS_PATH_CANONICAL) {
102 /* Strip off excess slashes in base string */
103 while (namelen > 0 && base[namelen - 1] == '/')
104 namelen--;
105 }
106 buflen -= namelen;
107 if (buflen < 0) {
108 spin_unlock(&dentry->d_lock);
109 rcu_read_unlock();
110 goto Elong;
111 }
112 end -= namelen;
113 memcpy(end, base, namelen);
114 spin_unlock(&dentry->d_lock);
115 rcu_read_unlock();
116 return end;
117 Elong_unlock:
118 spin_unlock(&dentry->d_lock);
119 rcu_read_unlock();
120 if (read_seqretry(&rename_lock, seq))
121 goto rename_retry;
122 Elong:
123 return ERR_PTR(-ENAMETOOLONG);
124 }
125 EXPORT_SYMBOL_GPL(nfs_path);
126
127 /*
128 * nfs_d_automount - Handle crossing a mountpoint on the server
129 * @path - The mountpoint
130 *
131 * When we encounter a mountpoint on the server, we want to set up
132 * a mountpoint on the client too, to prevent inode numbers from
133 * colliding, and to allow "df" to work properly.
134 * On NFSv4, we also want to allow for the fact that different
135 * filesystems may be migrated to different servers in a failover
136 * situation, and that different filesystems may want to use
137 * different security flavours.
138 */
139 struct vfsmount *nfs_d_automount(struct path *path)
140 {
141 struct vfsmount *mnt;
142 struct nfs_server *server = NFS_SERVER(d_inode(path->dentry));
143 struct nfs_fh *fh = NULL;
144 struct nfs_fattr *fattr = NULL;
145
146 dprintk("--> nfs_d_automount()\n");
147
148 mnt = ERR_PTR(-ESTALE);
149 if (IS_ROOT(path->dentry))
150 goto out_nofree;
151
152 mnt = ERR_PTR(-ENOMEM);
153 fh = nfs_alloc_fhandle();
154 fattr = nfs_alloc_fattr();
155 if (fh == NULL || fattr == NULL)
156 goto out;
157
158 dprintk("%s: enter\n", __func__);
159
160 mnt = server->nfs_client->rpc_ops->submount(server, path->dentry, fh, fattr);
161 if (IS_ERR(mnt))
162 goto out;
163
164 dprintk("%s: done, success\n", __func__);
165 mntget(mnt); /* prevent immediate expiration */
166 mnt_set_expiry(mnt, &nfs_automount_list);
167 schedule_delayed_work(&nfs_automount_task, nfs_mountpoint_expiry_timeout);
168
169 out:
170 nfs_free_fattr(fattr);
171 nfs_free_fhandle(fh);
172 out_nofree:
173 if (IS_ERR(mnt))
174 dprintk("<-- %s(): error %ld\n", __func__, PTR_ERR(mnt));
175 else
176 dprintk("<-- %s() = %p\n", __func__, mnt);
177 return mnt;
178 }
179
180 static int
181 nfs_namespace_getattr(struct vfsmount *mnt, struct dentry *dentry, struct kstat *stat)
182 {
183 if (NFS_FH(d_inode(dentry))->size != 0)
184 return nfs_getattr(mnt, dentry, stat);
185 generic_fillattr(d_inode(dentry), stat);
186 return 0;
187 }
188
189 static int
190 nfs_namespace_setattr(struct dentry *dentry, struct iattr *attr)
191 {
192 if (NFS_FH(d_inode(dentry))->size != 0)
193 return nfs_setattr(dentry, attr);
194 return -EACCES;
195 }
196
197 const struct inode_operations nfs_mountpoint_inode_operations = {
198 .getattr = nfs_getattr,
199 .setattr = nfs_setattr,
200 };
201
202 const struct inode_operations nfs_referral_inode_operations = {
203 .getattr = nfs_namespace_getattr,
204 .setattr = nfs_namespace_setattr,
205 };
206
207 static void nfs_expire_automounts(struct work_struct *work)
208 {
209 struct list_head *list = &nfs_automount_list;
210
211 mark_mounts_for_expiry(list);
212 if (!list_empty(list))
213 schedule_delayed_work(&nfs_automount_task, nfs_mountpoint_expiry_timeout);
214 }
215
216 void nfs_release_automount_timer(void)
217 {
218 if (list_empty(&nfs_automount_list))
219 cancel_delayed_work(&nfs_automount_task);
220 }
221
222 /*
223 * Clone a mountpoint of the appropriate type
224 */
225 static struct vfsmount *nfs_do_clone_mount(struct nfs_server *server,
226 const char *devname,
227 struct nfs_clone_mount *mountdata)
228 {
229 return vfs_kern_mount(&nfs_xdev_fs_type, 0, devname, mountdata);
230 }
231
232 /**
233 * nfs_do_submount - set up mountpoint when crossing a filesystem boundary
234 * @dentry - parent directory
235 * @fh - filehandle for new root dentry
236 * @fattr - attributes for new root inode
237 * @authflavor - security flavor to use when performing the mount
238 *
239 */
240 struct vfsmount *nfs_do_submount(struct dentry *dentry, struct nfs_fh *fh,
241 struct nfs_fattr *fattr, rpc_authflavor_t authflavor)
242 {
243 struct nfs_clone_mount mountdata = {
244 .sb = dentry->d_sb,
245 .dentry = dentry,
246 .fh = fh,
247 .fattr = fattr,
248 .authflavor = authflavor,
249 };
250 struct vfsmount *mnt = ERR_PTR(-ENOMEM);
251 char *page = (char *) __get_free_page(GFP_USER);
252 char *devname;
253
254 dprintk("--> nfs_do_submount()\n");
255
256 dprintk("%s: submounting on %pd2\n", __func__,
257 dentry);
258 if (page == NULL)
259 goto out;
260 devname = nfs_devname(dentry, page, PAGE_SIZE);
261 mnt = (struct vfsmount *)devname;
262 if (IS_ERR(devname))
263 goto free_page;
264 mnt = nfs_do_clone_mount(NFS_SB(dentry->d_sb), devname, &mountdata);
265 free_page:
266 free_page((unsigned long)page);
267 out:
268 dprintk("%s: done\n", __func__);
269
270 dprintk("<-- nfs_do_submount() = %p\n", mnt);
271 return mnt;
272 }
273 EXPORT_SYMBOL_GPL(nfs_do_submount);
274
275 struct vfsmount *nfs_submount(struct nfs_server *server, struct dentry *dentry,
276 struct nfs_fh *fh, struct nfs_fattr *fattr)
277 {
278 int err;
279 struct dentry *parent = dget_parent(dentry);
280
281 /* Look it up again to get its attributes */
282 err = server->nfs_client->rpc_ops->lookup(d_inode(parent), &dentry->d_name, fh, fattr, NULL);
283 dput(parent);
284 if (err != 0)
285 return ERR_PTR(err);
286
287 return nfs_do_submount(dentry, fh, fattr, server->client->cl_auth->au_flavor);
288 }
289 EXPORT_SYMBOL_GPL(nfs_submount);