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1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * linux/fs/nfs/namespace.c
4 *
5 * Copyright (C) 2005 Trond Myklebust <Trond.Myklebust@netapp.com>
6 * - Modified by David Howells <dhowells@redhat.com>
7 *
8 * NFS namespace
9 */
10
11#include <linux/module.h>
12#include <linux/dcache.h>
13#include <linux/gfp.h>
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>
20#include <linux/sunrpc/gss_api.h>
21#include "internal.h"
22#include "nfs.h"
23
24#define NFSDBG_FACILITY NFSDBG_VFS
25
26static void nfs_expire_automounts(struct work_struct *work);
27
28static LIST_HEAD(nfs_automount_list);
29static DECLARE_DELAYED_WORK(nfs_automount_task, nfs_expire_automounts);
30int nfs_mountpoint_expiry_timeout = 500 * HZ;
31
32/*
33 * nfs_path - reconstruct the path given an arbitrary dentry
34 * @base - used to return pointer to the end of devname part of path
35 * @dentry_in - pointer to dentry
36 * @buffer - result buffer
37 * @buflen_in - length of buffer
38 * @flags - options (see below)
39 *
40 * Helper function for constructing the server pathname
41 * by arbitrary hashed dentry.
42 *
43 * This is mainly for use in figuring out the path on the
44 * server side when automounting on top of an existing partition
45 * and in generating /proc/mounts and friends.
46 *
47 * Supported flags:
48 * NFS_PATH_CANONICAL: ensure there is exactly one slash after
49 * the original device (export) name
50 * (if unset, the original name is returned verbatim)
51 */
52char *nfs_path(char **p, struct dentry *dentry_in, char *buffer,
53 ssize_t buflen_in, unsigned flags)
54{
55 char *end;
56 int namelen;
57 unsigned seq;
58 const char *base;
59 struct dentry *dentry;
60 ssize_t buflen;
61
62rename_retry:
63 buflen = buflen_in;
64 dentry = dentry_in;
65 end = buffer+buflen;
66 *--end = '\0';
67 buflen--;
68
69 seq = read_seqbegin(&rename_lock);
70 rcu_read_lock();
71 while (1) {
72 spin_lock(&dentry->d_lock);
73 if (IS_ROOT(dentry))
74 break;
75 namelen = dentry->d_name.len;
76 buflen -= namelen + 1;
77 if (buflen < 0)
78 goto Elong_unlock;
79 end -= namelen;
80 memcpy(end, dentry->d_name.name, namelen);
81 *--end = '/';
82 spin_unlock(&dentry->d_lock);
83 dentry = dentry->d_parent;
84 }
85 if (read_seqretry(&rename_lock, seq)) {
86 spin_unlock(&dentry->d_lock);
87 rcu_read_unlock();
88 goto rename_retry;
89 }
90 if ((flags & NFS_PATH_CANONICAL) && *end != '/') {
91 if (--buflen < 0) {
92 spin_unlock(&dentry->d_lock);
93 rcu_read_unlock();
94 goto Elong;
95 }
96 *--end = '/';
97 }
98 *p = end;
99 base = dentry->d_fsdata;
100 if (!base) {
101 spin_unlock(&dentry->d_lock);
102 rcu_read_unlock();
103 WARN_ON(1);
104 return end;
105 }
106 namelen = strlen(base);
107 if (*end == '/') {
108 /* Strip off excess slashes in base string */
109 while (namelen > 0 && base[namelen - 1] == '/')
110 namelen--;
111 }
112 buflen -= namelen;
113 if (buflen < 0) {
114 spin_unlock(&dentry->d_lock);
115 rcu_read_unlock();
116 goto Elong;
117 }
118 end -= namelen;
119 memcpy(end, base, namelen);
120 spin_unlock(&dentry->d_lock);
121 rcu_read_unlock();
122 return end;
123Elong_unlock:
124 spin_unlock(&dentry->d_lock);
125 rcu_read_unlock();
126 if (read_seqretry(&rename_lock, seq))
127 goto rename_retry;
128Elong:
129 return ERR_PTR(-ENAMETOOLONG);
130}
131EXPORT_SYMBOL_GPL(nfs_path);
132
133/*
134 * nfs_d_automount - Handle crossing a mountpoint on the server
135 * @path - The mountpoint
136 *
137 * When we encounter a mountpoint on the server, we want to set up
138 * a mountpoint on the client too, to prevent inode numbers from
139 * colliding, and to allow "df" to work properly.
140 * On NFSv4, we also want to allow for the fact that different
141 * filesystems may be migrated to different servers in a failover
142 * situation, and that different filesystems may want to use
143 * different security flavours.
144 */
145struct vfsmount *nfs_d_automount(struct path *path)
146{
147 struct nfs_fs_context *ctx;
148 struct fs_context *fc;
149 struct vfsmount *mnt = ERR_PTR(-ENOMEM);
150 struct nfs_server *server = NFS_SERVER(d_inode(path->dentry));
151 struct nfs_client *client = server->nfs_client;
152 int timeout = READ_ONCE(nfs_mountpoint_expiry_timeout);
153 int ret;
154
155 if (IS_ROOT(path->dentry))
156 return ERR_PTR(-ESTALE);
157
158 /* Open a new filesystem context, transferring parameters from the
159 * parent superblock, including the network namespace.
160 */
161 fc = fs_context_for_submount(path->mnt->mnt_sb->s_type, path->dentry);
162 if (IS_ERR(fc))
163 return ERR_CAST(fc);
164
165 ctx = nfs_fc2context(fc);
166 ctx->clone_data.dentry = path->dentry;
167 ctx->clone_data.sb = path->dentry->d_sb;
168 ctx->clone_data.fattr = nfs_alloc_fattr();
169 if (!ctx->clone_data.fattr)
170 goto out_fc;
171
172 if (fc->net_ns != client->cl_net) {
173 put_net(fc->net_ns);
174 fc->net_ns = get_net(client->cl_net);
175 }
176
177 /* for submounts we want the same server; referrals will reassign */
178 memcpy(&ctx->nfs_server.address, &client->cl_addr, client->cl_addrlen);
179 ctx->nfs_server.addrlen = client->cl_addrlen;
180 ctx->nfs_server.port = server->port;
181
182 ctx->version = client->rpc_ops->version;
183 ctx->minorversion = client->cl_minorversion;
184 ctx->nfs_mod = client->cl_nfs_mod;
185 __module_get(ctx->nfs_mod->owner);
186
187 ret = client->rpc_ops->submount(fc, server);
188 if (ret < 0) {
189 mnt = ERR_PTR(ret);
190 goto out_fc;
191 }
192
193 up_write(&fc->root->d_sb->s_umount);
194 mnt = vfs_create_mount(fc);
195 if (IS_ERR(mnt))
196 goto out_fc;
197
198 mntget(mnt); /* prevent immediate expiration */
199 if (timeout <= 0)
200 goto out_fc;
201
202 mnt_set_expiry(mnt, &nfs_automount_list);
203 schedule_delayed_work(&nfs_automount_task, timeout);
204
205out_fc:
206 put_fs_context(fc);
207 return mnt;
208}
209
210static int
211nfs_namespace_getattr(struct user_namespace *mnt_userns,
212 const struct path *path, struct kstat *stat,
213 u32 request_mask, unsigned int query_flags)
214{
215 if (NFS_FH(d_inode(path->dentry))->size != 0)
216 return nfs_getattr(mnt_userns, path, stat, request_mask,
217 query_flags);
218 generic_fillattr(&init_user_ns, d_inode(path->dentry), stat);
219 return 0;
220}
221
222static int
223nfs_namespace_setattr(struct user_namespace *mnt_userns, struct dentry *dentry,
224 struct iattr *attr)
225{
226 if (NFS_FH(d_inode(dentry))->size != 0)
227 return nfs_setattr(mnt_userns, dentry, attr);
228 return -EACCES;
229}
230
231const struct inode_operations nfs_mountpoint_inode_operations = {
232 .getattr = nfs_getattr,
233 .setattr = nfs_setattr,
234};
235
236const struct inode_operations nfs_referral_inode_operations = {
237 .getattr = nfs_namespace_getattr,
238 .setattr = nfs_namespace_setattr,
239};
240
241static void nfs_expire_automounts(struct work_struct *work)
242{
243 struct list_head *list = &nfs_automount_list;
244 int timeout = READ_ONCE(nfs_mountpoint_expiry_timeout);
245
246 mark_mounts_for_expiry(list);
247 if (!list_empty(list) && timeout > 0)
248 schedule_delayed_work(&nfs_automount_task, timeout);
249}
250
251void nfs_release_automount_timer(void)
252{
253 if (list_empty(&nfs_automount_list))
254 cancel_delayed_work(&nfs_automount_task);
255}
256
257/**
258 * nfs_do_submount - set up mountpoint when crossing a filesystem boundary
259 * @fc: pointer to struct nfs_fs_context
260 *
261 */
262int nfs_do_submount(struct fs_context *fc)
263{
264 struct nfs_fs_context *ctx = nfs_fc2context(fc);
265 struct dentry *dentry = ctx->clone_data.dentry;
266 struct nfs_server *server;
267 char *buffer, *p;
268 int ret;
269
270 /* create a new volume representation */
271 server = ctx->nfs_mod->rpc_ops->clone_server(NFS_SB(ctx->clone_data.sb),
272 ctx->mntfh,
273 ctx->clone_data.fattr,
274 ctx->selected_flavor);
275
276 if (IS_ERR(server))
277 return PTR_ERR(server);
278
279 ctx->server = server;
280
281 buffer = kmalloc(4096, GFP_USER);
282 if (!buffer)
283 return -ENOMEM;
284
285 ctx->internal = true;
286 ctx->clone_data.inherited_bsize = ctx->clone_data.sb->s_blocksize_bits;
287
288 p = nfs_devname(dentry, buffer, 4096);
289 if (IS_ERR(p)) {
290 nfs_errorf(fc, "NFS: Couldn't determine submount pathname");
291 ret = PTR_ERR(p);
292 } else {
293 ret = vfs_parse_fs_string(fc, "source", p, buffer + 4096 - p);
294 if (!ret)
295 ret = vfs_get_tree(fc);
296 }
297 kfree(buffer);
298 return ret;
299}
300EXPORT_SYMBOL_GPL(nfs_do_submount);
301
302int nfs_submount(struct fs_context *fc, struct nfs_server *server)
303{
304 struct nfs_fs_context *ctx = nfs_fc2context(fc);
305 struct dentry *dentry = ctx->clone_data.dentry;
306 struct dentry *parent = dget_parent(dentry);
307 int err;
308
309 /* Look it up again to get its attributes */
310 err = server->nfs_client->rpc_ops->lookup(d_inode(parent), dentry,
311 ctx->mntfh, ctx->clone_data.fattr,
312 NULL);
313 dput(parent);
314 if (err != 0)
315 return err;
316
317 ctx->selected_flavor = server->client->cl_auth->au_flavor;
318 return nfs_do_submount(fc);
319}
320EXPORT_SYMBOL_GPL(nfs_submount);
321
322static int param_set_nfs_timeout(const char *val, const struct kernel_param *kp)
323{
324 long num;
325 int ret;
326
327 if (!val)
328 return -EINVAL;
329 ret = kstrtol(val, 0, &num);
330 if (ret)
331 return -EINVAL;
332 if (num > 0) {
333 if (num >= INT_MAX / HZ)
334 num = INT_MAX;
335 else
336 num *= HZ;
337 *((int *)kp->arg) = num;
338 if (!list_empty(&nfs_automount_list))
339 mod_delayed_work(system_wq, &nfs_automount_task, num);
340 } else {
341 *((int *)kp->arg) = -1*HZ;
342 cancel_delayed_work(&nfs_automount_task);
343 }
344 return 0;
345}
346
347static int param_get_nfs_timeout(char *buffer, const struct kernel_param *kp)
348{
349 long num = *((int *)kp->arg);
350
351 if (num > 0) {
352 if (num >= INT_MAX - (HZ - 1))
353 num = INT_MAX / HZ;
354 else
355 num = (num + (HZ - 1)) / HZ;
356 } else
357 num = -1;
358 return scnprintf(buffer, PAGE_SIZE, "%li\n", num);
359}
360
361static const struct kernel_param_ops param_ops_nfs_timeout = {
362 .set = param_set_nfs_timeout,
363 .get = param_get_nfs_timeout,
364};
365#define param_check_nfs_timeout(name, p) __param_check(name, p, int)
366
367module_param(nfs_mountpoint_expiry_timeout, nfs_timeout, 0644);
368MODULE_PARM_DESC(nfs_mountpoint_expiry_timeout,
369 "Set the NFS automounted mountpoint timeout value (seconds)."
370 "Values <= 0 turn expiration off.");
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/dcache.h>
11#include <linux/gfp.h>
12#include <linux/mount.h>
13#include <linux/namei.h>
14#include <linux/nfs_fs.h>
15#include <linux/string.h>
16#include <linux/sunrpc/clnt.h>
17#include <linux/vfs.h>
18#include <linux/sunrpc/gss_api.h>
19#include "internal.h"
20
21#define NFSDBG_FACILITY NFSDBG_VFS
22
23static void nfs_expire_automounts(struct work_struct *work);
24
25static LIST_HEAD(nfs_automount_list);
26static DECLARE_DELAYED_WORK(nfs_automount_task, nfs_expire_automounts);
27int nfs_mountpoint_expiry_timeout = 500 * HZ;
28
29static struct vfsmount *nfs_do_submount(struct dentry *dentry,
30 struct nfs_fh *fh,
31 struct nfs_fattr *fattr,
32 rpc_authflavor_t authflavor);
33
34/*
35 * nfs_path - reconstruct the path given an arbitrary dentry
36 * @base - used to return pointer to the end of devname part of path
37 * @dentry - pointer to dentry
38 * @buffer - result buffer
39 * @buflen - length of buffer
40 *
41 * Helper function for constructing the server pathname
42 * by arbitrary hashed dentry.
43 *
44 * This is mainly for use in figuring out the path on the
45 * server side when automounting on top of an existing partition
46 * and in generating /proc/mounts and friends.
47 */
48char *nfs_path(char **p, struct dentry *dentry, char *buffer, ssize_t buflen)
49{
50 char *end;
51 int namelen;
52 unsigned seq;
53 const char *base;
54
55rename_retry:
56 end = buffer+buflen;
57 *--end = '\0';
58 buflen--;
59
60 seq = read_seqbegin(&rename_lock);
61 rcu_read_lock();
62 while (1) {
63 spin_lock(&dentry->d_lock);
64 if (IS_ROOT(dentry))
65 break;
66 namelen = dentry->d_name.len;
67 buflen -= namelen + 1;
68 if (buflen < 0)
69 goto Elong_unlock;
70 end -= namelen;
71 memcpy(end, dentry->d_name.name, namelen);
72 *--end = '/';
73 spin_unlock(&dentry->d_lock);
74 dentry = dentry->d_parent;
75 }
76 if (read_seqretry(&rename_lock, seq)) {
77 spin_unlock(&dentry->d_lock);
78 rcu_read_unlock();
79 goto rename_retry;
80 }
81 if (*end != '/') {
82 if (--buflen < 0) {
83 spin_unlock(&dentry->d_lock);
84 rcu_read_unlock();
85 goto Elong;
86 }
87 *--end = '/';
88 }
89 *p = end;
90 base = dentry->d_fsdata;
91 if (!base) {
92 spin_unlock(&dentry->d_lock);
93 rcu_read_unlock();
94 WARN_ON(1);
95 return end;
96 }
97 namelen = strlen(base);
98 /* Strip off excess slashes in base string */
99 while (namelen > 0 && base[namelen - 1] == '/')
100 namelen--;
101 buflen -= namelen;
102 if (buflen < 0) {
103 spin_unlock(&dentry->d_lock);
104 rcu_read_unlock();
105 goto Elong;
106 }
107 end -= namelen;
108 memcpy(end, base, namelen);
109 spin_unlock(&dentry->d_lock);
110 rcu_read_unlock();
111 return end;
112Elong_unlock:
113 spin_unlock(&dentry->d_lock);
114 rcu_read_unlock();
115 if (read_seqretry(&rename_lock, seq))
116 goto rename_retry;
117Elong:
118 return ERR_PTR(-ENAMETOOLONG);
119}
120
121#ifdef CONFIG_NFS_V4
122rpc_authflavor_t nfs_find_best_sec(struct nfs4_secinfo_flavors *flavors)
123{
124 struct gss_api_mech *mech;
125 struct xdr_netobj oid;
126 int i;
127 rpc_authflavor_t pseudoflavor = RPC_AUTH_UNIX;
128
129 for (i = 0; i < flavors->num_flavors; i++) {
130 struct nfs4_secinfo_flavor *flavor;
131 flavor = &flavors->flavors[i];
132
133 if (flavor->flavor == RPC_AUTH_NULL || flavor->flavor == RPC_AUTH_UNIX) {
134 pseudoflavor = flavor->flavor;
135 break;
136 } else if (flavor->flavor == RPC_AUTH_GSS) {
137 oid.len = flavor->gss.sec_oid4.len;
138 oid.data = flavor->gss.sec_oid4.data;
139 mech = gss_mech_get_by_OID(&oid);
140 if (!mech)
141 continue;
142 pseudoflavor = gss_svc_to_pseudoflavor(mech, flavor->gss.service);
143 gss_mech_put(mech);
144 break;
145 }
146 }
147
148 return pseudoflavor;
149}
150
151static int nfs_negotiate_security(const struct dentry *parent,
152 const struct dentry *dentry,
153 rpc_authflavor_t *flavor)
154{
155 struct page *page;
156 struct nfs4_secinfo_flavors *flavors;
157 int (*secinfo)(struct inode *, const struct qstr *, struct nfs4_secinfo_flavors *);
158 int ret = -EPERM;
159
160 secinfo = NFS_PROTO(parent->d_inode)->secinfo;
161 if (secinfo != NULL) {
162 page = alloc_page(GFP_KERNEL);
163 if (!page) {
164 ret = -ENOMEM;
165 goto out;
166 }
167 flavors = page_address(page);
168 ret = secinfo(parent->d_inode, &dentry->d_name, flavors);
169 *flavor = nfs_find_best_sec(flavors);
170 put_page(page);
171 }
172
173out:
174 return ret;
175}
176
177static int nfs_lookup_with_sec(struct nfs_server *server, struct dentry *parent,
178 struct dentry *dentry, struct path *path,
179 struct nfs_fh *fh, struct nfs_fattr *fattr,
180 rpc_authflavor_t *flavor)
181{
182 struct rpc_clnt *clone;
183 struct rpc_auth *auth;
184 int err;
185
186 err = nfs_negotiate_security(parent, path->dentry, flavor);
187 if (err < 0)
188 goto out;
189 clone = rpc_clone_client(server->client);
190 auth = rpcauth_create(*flavor, clone);
191 if (!auth) {
192 err = -EIO;
193 goto out_shutdown;
194 }
195 err = server->nfs_client->rpc_ops->lookup(clone, parent->d_inode,
196 &path->dentry->d_name,
197 fh, fattr);
198out_shutdown:
199 rpc_shutdown_client(clone);
200out:
201 return err;
202}
203#else /* CONFIG_NFS_V4 */
204static inline int nfs_lookup_with_sec(struct nfs_server *server,
205 struct dentry *parent, struct dentry *dentry,
206 struct path *path, struct nfs_fh *fh,
207 struct nfs_fattr *fattr,
208 rpc_authflavor_t *flavor)
209{
210 return -EPERM;
211}
212#endif /* CONFIG_NFS_V4 */
213
214/*
215 * nfs_d_automount - Handle crossing a mountpoint on the server
216 * @path - The mountpoint
217 *
218 * When we encounter a mountpoint on the server, we want to set up
219 * a mountpoint on the client too, to prevent inode numbers from
220 * colliding, and to allow "df" to work properly.
221 * On NFSv4, we also want to allow for the fact that different
222 * filesystems may be migrated to different servers in a failover
223 * situation, and that different filesystems may want to use
224 * different security flavours.
225 */
226struct vfsmount *nfs_d_automount(struct path *path)
227{
228 struct vfsmount *mnt;
229 struct nfs_server *server = NFS_SERVER(path->dentry->d_inode);
230 struct dentry *parent;
231 struct nfs_fh *fh = NULL;
232 struct nfs_fattr *fattr = NULL;
233 int err;
234 rpc_authflavor_t flavor = RPC_AUTH_UNIX;
235
236 dprintk("--> nfs_d_automount()\n");
237
238 mnt = ERR_PTR(-ESTALE);
239 if (IS_ROOT(path->dentry))
240 goto out_nofree;
241
242 mnt = ERR_PTR(-ENOMEM);
243 fh = nfs_alloc_fhandle();
244 fattr = nfs_alloc_fattr();
245 if (fh == NULL || fattr == NULL)
246 goto out;
247
248 dprintk("%s: enter\n", __func__);
249
250 /* Look it up again to get its attributes */
251 parent = dget_parent(path->dentry);
252 err = server->nfs_client->rpc_ops->lookup(server->client, parent->d_inode,
253 &path->dentry->d_name,
254 fh, fattr);
255 if (err == -EPERM && NFS_PROTO(parent->d_inode)->secinfo != NULL)
256 err = nfs_lookup_with_sec(server, parent, path->dentry, path, fh, fattr, &flavor);
257 dput(parent);
258 if (err != 0) {
259 mnt = ERR_PTR(err);
260 goto out;
261 }
262
263 if (fattr->valid & NFS_ATTR_FATTR_V4_REFERRAL)
264 mnt = nfs_do_refmount(path->dentry);
265 else
266 mnt = nfs_do_submount(path->dentry, fh, fattr, flavor);
267 if (IS_ERR(mnt))
268 goto out;
269
270 dprintk("%s: done, success\n", __func__);
271 mntget(mnt); /* prevent immediate expiration */
272 mnt_set_expiry(mnt, &nfs_automount_list);
273 schedule_delayed_work(&nfs_automount_task, nfs_mountpoint_expiry_timeout);
274
275out:
276 nfs_free_fattr(fattr);
277 nfs_free_fhandle(fh);
278out_nofree:
279 dprintk("<-- nfs_follow_mountpoint() = %p\n", mnt);
280 return mnt;
281}
282
283const struct inode_operations nfs_mountpoint_inode_operations = {
284 .getattr = nfs_getattr,
285};
286
287const struct inode_operations nfs_referral_inode_operations = {
288};
289
290static void nfs_expire_automounts(struct work_struct *work)
291{
292 struct list_head *list = &nfs_automount_list;
293
294 mark_mounts_for_expiry(list);
295 if (!list_empty(list))
296 schedule_delayed_work(&nfs_automount_task, nfs_mountpoint_expiry_timeout);
297}
298
299void nfs_release_automount_timer(void)
300{
301 if (list_empty(&nfs_automount_list))
302 cancel_delayed_work(&nfs_automount_task);
303}
304
305/*
306 * Clone a mountpoint of the appropriate type
307 */
308static struct vfsmount *nfs_do_clone_mount(struct nfs_server *server,
309 const char *devname,
310 struct nfs_clone_mount *mountdata)
311{
312#ifdef CONFIG_NFS_V4
313 struct vfsmount *mnt = ERR_PTR(-EINVAL);
314 switch (server->nfs_client->rpc_ops->version) {
315 case 2:
316 case 3:
317 mnt = vfs_kern_mount(&nfs_xdev_fs_type, 0, devname, mountdata);
318 break;
319 case 4:
320 mnt = vfs_kern_mount(&nfs4_xdev_fs_type, 0, devname, mountdata);
321 }
322 return mnt;
323#else
324 return vfs_kern_mount(&nfs_xdev_fs_type, 0, devname, mountdata);
325#endif
326}
327
328/**
329 * nfs_do_submount - set up mountpoint when crossing a filesystem boundary
330 * @dentry - parent directory
331 * @fh - filehandle for new root dentry
332 * @fattr - attributes for new root inode
333 * @authflavor - security flavor to use when performing the mount
334 *
335 */
336static struct vfsmount *nfs_do_submount(struct dentry *dentry,
337 struct nfs_fh *fh,
338 struct nfs_fattr *fattr,
339 rpc_authflavor_t authflavor)
340{
341 struct nfs_clone_mount mountdata = {
342 .sb = dentry->d_sb,
343 .dentry = dentry,
344 .fh = fh,
345 .fattr = fattr,
346 .authflavor = authflavor,
347 };
348 struct vfsmount *mnt = ERR_PTR(-ENOMEM);
349 char *page = (char *) __get_free_page(GFP_USER);
350 char *devname;
351
352 dprintk("--> nfs_do_submount()\n");
353
354 dprintk("%s: submounting on %s/%s\n", __func__,
355 dentry->d_parent->d_name.name,
356 dentry->d_name.name);
357 if (page == NULL)
358 goto out;
359 devname = nfs_devname(dentry, page, PAGE_SIZE);
360 mnt = (struct vfsmount *)devname;
361 if (IS_ERR(devname))
362 goto free_page;
363 mnt = nfs_do_clone_mount(NFS_SB(dentry->d_sb), devname, &mountdata);
364free_page:
365 free_page((unsigned long)page);
366out:
367 dprintk("%s: done\n", __func__);
368
369 dprintk("<-- nfs_do_submount() = %p\n", mnt);
370 return mnt;
371}