Commit | Line | Data |
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457c8996 | 1 | // SPDX-License-Identifier: GPL-2.0-only |
55a97593 TM |
2 | /* |
3 | * linux/fs/nfs/namespace.c | |
4 | * | |
5 | * Copyright (C) 2005 Trond Myklebust <Trond.Myklebust@netapp.com> | |
54ceac45 | 6 | * - Modified by David Howells <dhowells@redhat.com> |
55a97593 TM |
7 | * |
8 | * NFS namespace | |
9 | */ | |
10 | ||
ddda8e0a | 11 | #include <linux/module.h> |
55a97593 | 12 | #include <linux/dcache.h> |
5a0e3ad6 | 13 | #include <linux/gfp.h> |
55a97593 TM |
14 | #include <linux/mount.h> |
15 | #include <linux/namei.h> | |
16 | #include <linux/nfs_fs.h> | |
17 | #include <linux/string.h> | |
18 | #include <linux/sunrpc/clnt.h> | |
19 | #include <linux/vfs.h> | |
7ebb9315 | 20 | #include <linux/sunrpc/gss_api.h> |
f7b422b1 | 21 | #include "internal.h" |
55a97593 TM |
22 | |
23 | #define NFSDBG_FACILITY NFSDBG_VFS | |
24 | ||
65f27f38 | 25 | static void nfs_expire_automounts(struct work_struct *work); |
f7b422b1 | 26 | |
a3dab293 | 27 | static LIST_HEAD(nfs_automount_list); |
65f27f38 | 28 | static DECLARE_DELAYED_WORK(nfs_automount_task, nfs_expire_automounts); |
51d8fa6a TM |
29 | int nfs_mountpoint_expiry_timeout = 500 * HZ; |
30 | ||
f7b422b1 DH |
31 | /* |
32 | * nfs_path - reconstruct the path given an arbitrary dentry | |
b514f872 | 33 | * @base - used to return pointer to the end of devname part of path |
f7b422b1 DH |
34 | * @dentry - pointer to dentry |
35 | * @buffer - result buffer | |
36 | * @buflen - length of buffer | |
97a54868 | 37 | * @flags - options (see below) |
f7b422b1 | 38 | * |
b514f872 AV |
39 | * Helper function for constructing the server pathname |
40 | * by arbitrary hashed dentry. | |
f7b422b1 DH |
41 | * |
42 | * This is mainly for use in figuring out the path on the | |
b514f872 AV |
43 | * server side when automounting on top of an existing partition |
44 | * and in generating /proc/mounts and friends. | |
97a54868 BH |
45 | * |
46 | * Supported flags: | |
47 | * NFS_PATH_CANONICAL: ensure there is exactly one slash after | |
48 | * the original device (export) name | |
49 | * (if unset, the original name is returned verbatim) | |
f7b422b1 | 50 | */ |
97a54868 BH |
51 | char *nfs_path(char **p, struct dentry *dentry, char *buffer, ssize_t buflen, |
52 | unsigned flags) | |
f7b422b1 | 53 | { |
949854d0 | 54 | char *end; |
f7b422b1 | 55 | int namelen; |
949854d0 | 56 | unsigned seq; |
b514f872 | 57 | const char *base; |
f7b422b1 | 58 | |
949854d0 NP |
59 | rename_retry: |
60 | end = buffer+buflen; | |
f7b422b1 DH |
61 | *--end = '\0'; |
62 | buflen--; | |
949854d0 NP |
63 | |
64 | seq = read_seqbegin(&rename_lock); | |
65 | rcu_read_lock(); | |
b514f872 AV |
66 | while (1) { |
67 | spin_lock(&dentry->d_lock); | |
68 | if (IS_ROOT(dentry)) | |
69 | break; | |
f7b422b1 DH |
70 | namelen = dentry->d_name.len; |
71 | buflen -= namelen + 1; | |
72 | if (buflen < 0) | |
ce510193 | 73 | goto Elong_unlock; |
f7b422b1 DH |
74 | end -= namelen; |
75 | memcpy(end, dentry->d_name.name, namelen); | |
76 | *--end = '/'; | |
b514f872 | 77 | spin_unlock(&dentry->d_lock); |
f7b422b1 DH |
78 | dentry = dentry->d_parent; |
79 | } | |
b514f872 AV |
80 | if (read_seqretry(&rename_lock, seq)) { |
81 | spin_unlock(&dentry->d_lock); | |
82 | rcu_read_unlock(); | |
949854d0 | 83 | goto rename_retry; |
b514f872 | 84 | } |
97a54868 | 85 | if ((flags & NFS_PATH_CANONICAL) && *end != '/') { |
b514f872 AV |
86 | if (--buflen < 0) { |
87 | spin_unlock(&dentry->d_lock); | |
88 | rcu_read_unlock(); | |
0b75b35c | 89 | goto Elong; |
b514f872 | 90 | } |
0b75b35c TM |
91 | *--end = '/'; |
92 | } | |
b514f872 AV |
93 | *p = end; |
94 | base = dentry->d_fsdata; | |
95 | if (!base) { | |
96 | spin_unlock(&dentry->d_lock); | |
97 | rcu_read_unlock(); | |
98 | WARN_ON(1); | |
99 | return end; | |
100 | } | |
f7b422b1 | 101 | namelen = strlen(base); |
86a6c211 | 102 | if (*end == '/') { |
97a54868 BH |
103 | /* Strip off excess slashes in base string */ |
104 | while (namelen > 0 && base[namelen - 1] == '/') | |
105 | namelen--; | |
106 | } | |
f7b422b1 | 107 | buflen -= namelen; |
b514f872 | 108 | if (buflen < 0) { |
1c34092a | 109 | spin_unlock(&dentry->d_lock); |
b514f872 | 110 | rcu_read_unlock(); |
f7b422b1 | 111 | goto Elong; |
b514f872 | 112 | } |
f7b422b1 DH |
113 | end -= namelen; |
114 | memcpy(end, base, namelen); | |
b514f872 AV |
115 | spin_unlock(&dentry->d_lock); |
116 | rcu_read_unlock(); | |
f7b422b1 | 117 | return end; |
ce510193 | 118 | Elong_unlock: |
1c34092a | 119 | spin_unlock(&dentry->d_lock); |
949854d0 NP |
120 | rcu_read_unlock(); |
121 | if (read_seqretry(&rename_lock, seq)) | |
122 | goto rename_retry; | |
f7b422b1 DH |
123 | Elong: |
124 | return ERR_PTR(-ENAMETOOLONG); | |
125 | } | |
89d77c8f | 126 | EXPORT_SYMBOL_GPL(nfs_path); |
f7b422b1 | 127 | |
55a97593 | 128 | /* |
36d43a43 DH |
129 | * nfs_d_automount - Handle crossing a mountpoint on the server |
130 | * @path - The mountpoint | |
55a97593 TM |
131 | * |
132 | * When we encounter a mountpoint on the server, we want to set up | |
133 | * a mountpoint on the client too, to prevent inode numbers from | |
134 | * colliding, and to allow "df" to work properly. | |
135 | * On NFSv4, we also want to allow for the fact that different | |
136 | * filesystems may be migrated to different servers in a failover | |
137 | * situation, and that different filesystems may want to use | |
138 | * different security flavours. | |
139 | */ | |
36d43a43 | 140 | struct vfsmount *nfs_d_automount(struct path *path) |
55a97593 TM |
141 | { |
142 | struct vfsmount *mnt; | |
2b0143b5 | 143 | struct nfs_server *server = NFS_SERVER(d_inode(path->dentry)); |
a4d7f168 TM |
144 | struct nfs_fh *fh = NULL; |
145 | struct nfs_fattr *fattr = NULL; | |
55a97593 | 146 | |
36d43a43 | 147 | if (IS_ROOT(path->dentry)) |
e36d48e9 | 148 | return ERR_PTR(-ESTALE); |
44d5759d | 149 | |
36d43a43 | 150 | mnt = ERR_PTR(-ENOMEM); |
a4d7f168 TM |
151 | fh = nfs_alloc_fhandle(); |
152 | fattr = nfs_alloc_fattr(); | |
153 | if (fh == NULL || fattr == NULL) | |
36d43a43 | 154 | goto out; |
a4d7f168 | 155 | |
281cad46 | 156 | mnt = server->nfs_client->rpc_ops->submount(server, path->dentry, fh, fattr); |
55a97593 | 157 | if (IS_ERR(mnt)) |
36d43a43 | 158 | goto out; |
55a97593 | 159 | |
ea5b778a DH |
160 | mntget(mnt); /* prevent immediate expiration */ |
161 | mnt_set_expiry(mnt, &nfs_automount_list); | |
162 | schedule_delayed_work(&nfs_automount_task, nfs_mountpoint_expiry_timeout); | |
36d43a43 | 163 | |
55a97593 | 164 | out: |
a4d7f168 TM |
165 | nfs_free_fattr(fattr); |
166 | nfs_free_fhandle(fh); | |
36d43a43 | 167 | return mnt; |
55a97593 TM |
168 | } |
169 | ||
ab225417 | 170 | static int |
a528d35e DH |
171 | nfs_namespace_getattr(const struct path *path, struct kstat *stat, |
172 | u32 request_mask, unsigned int query_flags) | |
ab225417 | 173 | { |
a528d35e DH |
174 | if (NFS_FH(d_inode(path->dentry))->size != 0) |
175 | return nfs_getattr(path, stat, request_mask, query_flags); | |
176 | generic_fillattr(d_inode(path->dentry), stat); | |
ab225417 TM |
177 | return 0; |
178 | } | |
179 | ||
180 | static int | |
181 | nfs_namespace_setattr(struct dentry *dentry, struct iattr *attr) | |
182 | { | |
2b0143b5 | 183 | if (NFS_FH(d_inode(dentry))->size != 0) |
ab225417 TM |
184 | return nfs_setattr(dentry, attr); |
185 | return -EACCES; | |
186 | } | |
187 | ||
92e1d5be | 188 | const struct inode_operations nfs_mountpoint_inode_operations = { |
55a97593 | 189 | .getattr = nfs_getattr, |
ab225417 | 190 | .setattr = nfs_setattr, |
55a97593 | 191 | }; |
51d8fa6a | 192 | |
92e1d5be | 193 | const struct inode_operations nfs_referral_inode_operations = { |
ab225417 TM |
194 | .getattr = nfs_namespace_getattr, |
195 | .setattr = nfs_namespace_setattr, | |
6b97fd3d MN |
196 | }; |
197 | ||
65f27f38 | 198 | static void nfs_expire_automounts(struct work_struct *work) |
51d8fa6a | 199 | { |
65f27f38 | 200 | struct list_head *list = &nfs_automount_list; |
51d8fa6a TM |
201 | |
202 | mark_mounts_for_expiry(list); | |
203 | if (!list_empty(list)) | |
204 | schedule_delayed_work(&nfs_automount_task, nfs_mountpoint_expiry_timeout); | |
205 | } | |
206 | ||
207 | void nfs_release_automount_timer(void) | |
208 | { | |
3d39c691 | 209 | if (list_empty(&nfs_automount_list)) |
560aef74 | 210 | cancel_delayed_work(&nfs_automount_task); |
51d8fa6a | 211 | } |
f7b422b1 DH |
212 | |
213 | /* | |
214 | * Clone a mountpoint of the appropriate type | |
215 | */ | |
509de811 DH |
216 | static struct vfsmount *nfs_do_clone_mount(struct nfs_server *server, |
217 | const char *devname, | |
f7b422b1 DH |
218 | struct nfs_clone_mount *mountdata) |
219 | { | |
93faccbb | 220 | return vfs_submount(mountdata->dentry, &nfs_xdev_fs_type, devname, mountdata); |
f7b422b1 DH |
221 | } |
222 | ||
223 | /** | |
224 | * nfs_do_submount - set up mountpoint when crossing a filesystem boundary | |
302fad7b TM |
225 | * @dentry: parent directory |
226 | * @fh: filehandle for new root dentry | |
227 | * @fattr: attributes for new root inode | |
228 | * @authflavor: security flavor to use when performing the mount | |
f7b422b1 DH |
229 | * |
230 | */ | |
281cad46 BS |
231 | struct vfsmount *nfs_do_submount(struct dentry *dentry, struct nfs_fh *fh, |
232 | struct nfs_fattr *fattr, rpc_authflavor_t authflavor) | |
f7b422b1 DH |
233 | { |
234 | struct nfs_clone_mount mountdata = { | |
f8ad9c4b | 235 | .sb = dentry->d_sb, |
f7b422b1 DH |
236 | .dentry = dentry, |
237 | .fh = fh, | |
238 | .fattr = fattr, | |
7ebb9315 | 239 | .authflavor = authflavor, |
f7b422b1 | 240 | }; |
e36d48e9 | 241 | struct vfsmount *mnt; |
f7b422b1 DH |
242 | char *page = (char *) __get_free_page(GFP_USER); |
243 | char *devname; | |
244 | ||
f7b422b1 | 245 | if (page == NULL) |
e36d48e9 AS |
246 | return ERR_PTR(-ENOMEM); |
247 | ||
b514f872 | 248 | devname = nfs_devname(dentry, page, PAGE_SIZE); |
f7b422b1 | 249 | if (IS_ERR(devname)) |
fe3b81b4 | 250 | mnt = ERR_CAST(devname); |
e36d48e9 AS |
251 | else |
252 | mnt = nfs_do_clone_mount(NFS_SB(dentry->d_sb), devname, &mountdata); | |
54ceac45 | 253 | |
e36d48e9 | 254 | free_page((unsigned long)page); |
f7b422b1 DH |
255 | return mnt; |
256 | } | |
89d77c8f | 257 | EXPORT_SYMBOL_GPL(nfs_do_submount); |
281cad46 BS |
258 | |
259 | struct vfsmount *nfs_submount(struct nfs_server *server, struct dentry *dentry, | |
260 | struct nfs_fh *fh, struct nfs_fattr *fattr) | |
261 | { | |
262 | int err; | |
263 | struct dentry *parent = dget_parent(dentry); | |
264 | ||
265 | /* Look it up again to get its attributes */ | |
2b0143b5 | 266 | err = server->nfs_client->rpc_ops->lookup(d_inode(parent), &dentry->d_name, fh, fattr, NULL); |
281cad46 BS |
267 | dput(parent); |
268 | if (err != 0) | |
269 | return ERR_PTR(err); | |
270 | ||
271 | return nfs_do_submount(dentry, fh, fattr, server->client->cl_auth->au_flavor); | |
272 | } | |
ddda8e0a | 273 | EXPORT_SYMBOL_GPL(nfs_submount); |