1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3 * Copyright (c) 2012 Bryan Schumaker <bjschuma@netapp.com>
4 */
5 #include <linux/init.h>
6 #include <linux/module.h>
7 #include <linux/mount.h>
8 #include <linux/nfs4_mount.h>
9 #include <linux/nfs_fs.h>
10 #include <linux/nfs_ssc.h>
11 #include "delegation.h"
12 #include "internal.h"
13 #include "nfs4_fs.h"
14 #include "nfs4idmap.h"
15 #include "dns_resolve.h"
16 #include "pnfs.h"
17 #include "nfs.h"
18
19 #define NFSDBG_FACILITY NFSDBG_VFS
20
21 static int nfs4_write_inode(struct inode *inode, struct writeback_control *wbc);
22 static void nfs4_evict_inode(struct inode *inode);
23
24 static const struct super_operations nfs4_sops = {
25 .alloc_inode = nfs_alloc_inode,
26 .free_inode = nfs_free_inode,
27 .write_inode = nfs4_write_inode,
28 .drop_inode = nfs_drop_inode,
29 .statfs = nfs_statfs,
30 .evict_inode = nfs4_evict_inode,
31 .umount_begin = nfs_umount_begin,
32 .show_options = nfs_show_options,
33 .show_devname = nfs_show_devname,
34 .show_path = nfs_show_path,
35 .show_stats = nfs_show_stats,
36 };
37
38 struct nfs_subversion nfs_v4 = {
39 .owner = THIS_MODULE,
40 .nfs_fs = &nfs4_fs_type,
41 .rpc_vers = &nfs_version4,
42 .rpc_ops = &nfs_v4_clientops,
43 .sops = &nfs4_sops,
44 .xattr = nfs4_xattr_handlers,
45 };
46
47 static int nfs4_write_inode(struct inode *inode, struct writeback_control *wbc)
48 {
49 int ret = nfs_write_inode(inode, wbc);
50
51 if (ret == 0)
52 ret = pnfs_layoutcommit_inode(inode,
53 wbc->sync_mode == WB_SYNC_ALL);
54 return ret;
55 }
56
57 /*
58 * Clean out any remaining NFSv4 state that might be left over due
59 * to open() calls that passed nfs_atomic_lookup, but failed to call
60 * nfs_open().
61 */
62 static void nfs4_evict_inode(struct inode *inode)
63 {
64 truncate_inode_pages_final(&inode->i_data);
65 clear_inode(inode);
66 /* If we are holding a delegation, return and free it */
67 nfs_inode_evict_delegation(inode);
68 /* Note that above delegreturn would trigger pnfs return-on-close */
69 pnfs_return_layout(inode);
70 pnfs_destroy_layout_final(NFS_I(inode));
71 /* First call standard NFS clear_inode() code */
72 nfs_clear_inode(inode);
73 nfs4_xattr_cache_zap(inode);
74 }
75
76 struct nfs_referral_count {
77 struct list_head list;
78 const struct task_struct *task;
79 unsigned int referral_count;
80 };
81
82 static LIST_HEAD(nfs_referral_count_list);
83 static DEFINE_SPINLOCK(nfs_referral_count_list_lock);
84
85 static struct nfs_referral_count *nfs_find_referral_count(void)
86 {
87 struct nfs_referral_count *p;
88
89 list_for_each_entry(p, &nfs_referral_count_list, list) {
90 if (p->task == current)
91 return p;
92 }
93 return NULL;
94 }
95
96 #define NFS_MAX_NESTED_REFERRALS 2
97
98 static int nfs_referral_loop_protect(void)
99 {
100 struct nfs_referral_count *p, *new;
101 int ret = -ENOMEM;
102
103 new = kmalloc(sizeof(*new), GFP_KERNEL);
104 if (!new)
105 goto out;
106 new->task = current;
107 new->referral_count = 1;
108
109 ret = 0;
110 spin_lock(&nfs_referral_count_list_lock);
111 p = nfs_find_referral_count();
112 if (p != NULL) {
113 if (p->referral_count >= NFS_MAX_NESTED_REFERRALS)
114 ret = -ELOOP;
115 else
116 p->referral_count++;
117 } else {
118 list_add(&new->list, &nfs_referral_count_list);
119 new = NULL;
120 }
121 spin_unlock(&nfs_referral_count_list_lock);
122 kfree(new);
123 out:
124 return ret;
125 }
126
127 static void nfs_referral_loop_unprotect(void)
128 {
129 struct nfs_referral_count *p;
130
131 spin_lock(&nfs_referral_count_list_lock);
132 p = nfs_find_referral_count();
133 p->referral_count--;
134 if (p->referral_count == 0)
135 list_del(&p->list);
136 else
137 p = NULL;
138 spin_unlock(&nfs_referral_count_list_lock);
139 kfree(p);
140 }
141
142 static int do_nfs4_mount(struct nfs_server *server,
143 struct fs_context *fc,
144 const char *hostname,
145 const char *export_path)
146 {
147 struct nfs_fs_context *root_ctx;
148 struct nfs_fs_context *ctx;
149 struct fs_context *root_fc;
150 struct vfsmount *root_mnt;
151 struct dentry *dentry;
152 size_t len;
153 int ret;
154
155 struct fs_parameter param = {
156 .key = "source",
157 .type = fs_value_is_string,
158 .dirfd = -1,
159 };
160
161 struct fs_parameter param_fsc = {
162 .key = "fsc",
163 .type = fs_value_is_string,
164 .dirfd = -1,
165 };
166
167 if (IS_ERR(server))
168 return PTR_ERR(server);
169
170 root_fc = vfs_dup_fs_context(fc);
171 if (IS_ERR(root_fc)) {
172 nfs_free_server(server);
173 return PTR_ERR(root_fc);
174 }
175 kfree(root_fc->source);
176 root_fc->source = NULL;
177
178 ctx = nfs_fc2context(fc);
179 root_ctx = nfs_fc2context(root_fc);
180 root_ctx->internal = true;
181 root_ctx->server = server;
182
183 if (ctx->fscache_uniq) {
184 len = strlen(ctx->fscache_uniq);
185 param_fsc.size = len;
186 param_fsc.string = kmemdup_nul(ctx->fscache_uniq, len, GFP_KERNEL);
187 if (param_fsc.string == NULL) {
188 put_fs_context(root_fc);
189 return -ENOMEM;
190 }
191 ret = vfs_parse_fs_param(root_fc, ¶m_fsc);
192 kfree(param_fsc.string);
193 if (ret < 0) {
194 put_fs_context(root_fc);
195 return ret;
196 }
197 }
198 /* We leave export_path unset as it's not used to find the root. */
199
200 len = strlen(hostname) + 5;
201 param.string = kmalloc(len, GFP_KERNEL);
202 if (param.string == NULL) {
203 put_fs_context(root_fc);
204 return -ENOMEM;
205 }
206
207 /* Does hostname needs to be enclosed in brackets? */
208 if (strchr(hostname, ':'))
209 param.size = snprintf(param.string, len, "[%s]:/", hostname);
210 else
211 param.size = snprintf(param.string, len, "%s:/", hostname);
212 ret = vfs_parse_fs_param(root_fc, ¶m);
213 kfree(param.string);
214 if (ret < 0) {
215 put_fs_context(root_fc);
216 return ret;
217 }
218 root_mnt = fc_mount(root_fc);
219 put_fs_context(root_fc);
220
221 if (IS_ERR(root_mnt))
222 return PTR_ERR(root_mnt);
223
224 ret = nfs_referral_loop_protect();
225 if (ret) {
226 mntput(root_mnt);
227 return ret;
228 }
229
230 dentry = mount_subtree(root_mnt, export_path);
231 nfs_referral_loop_unprotect();
232
233 if (IS_ERR(dentry))
234 return PTR_ERR(dentry);
235
236 fc->root = dentry;
237 return 0;
238 }
239
240 int nfs4_try_get_tree(struct fs_context *fc)
241 {
242 struct nfs_fs_context *ctx = nfs_fc2context(fc);
243 int err;
244
245 dfprintk(MOUNT, "--> nfs4_try_get_tree()\n");
246
247 /* We create a mount for the server's root, walk to the requested
248 * location and then create another mount for that.
249 */
250 err= do_nfs4_mount(nfs4_create_server(fc),
251 fc, ctx->nfs_server.hostname,
252 ctx->nfs_server.export_path);
253 if (err) {
254 nfs_ferrorf(fc, MOUNT, "NFS4: Couldn't follow remote path");
255 dfprintk(MOUNT, "<-- nfs4_try_get_tree() = %d [error]\n", err);
256 } else {
257 dfprintk(MOUNT, "<-- nfs4_try_get_tree() = 0\n");
258 }
259 return err;
260 }
261
262 /*
263 * Create an NFS4 server record on referral traversal
264 */
265 int nfs4_get_referral_tree(struct fs_context *fc)
266 {
267 struct nfs_fs_context *ctx = nfs_fc2context(fc);
268 int err;
269
270 dprintk("--> nfs4_referral_mount()\n");
271
272 /* create a new volume representation */
273 err = do_nfs4_mount(nfs4_create_referral_server(fc),
274 fc, ctx->nfs_server.hostname,
275 ctx->nfs_server.export_path);
276 if (err) {
277 nfs_ferrorf(fc, MOUNT, "NFS4: Couldn't follow remote path");
278 dfprintk(MOUNT, "<-- nfs4_get_referral_tree() = %d [error]\n", err);
279 } else {
280 dfprintk(MOUNT, "<-- nfs4_get_referral_tree() = 0\n");
281 }
282 return err;
283 }
284
285 static int __init init_nfs_v4(void)
286 {
287 int err;
288
289 err = nfs_dns_resolver_init();
290 if (err)
291 goto out;
292
293 err = nfs_idmap_init();
294 if (err)
295 goto out1;
296
297 #ifdef CONFIG_NFS_V4_2
298 err = nfs4_xattr_cache_init();
299 if (err)
300 goto out2;
301 #endif
302
303 err = nfs4_register_sysctl();
304 if (err)
305 goto out2;
306
307 #ifdef CONFIG_NFS_V4_2
308 nfs42_ssc_register_ops();
309 #endif
310 register_nfs_version(&nfs_v4);
311 return 0;
312 out2:
313 nfs_idmap_quit();
314 out1:
315 nfs_dns_resolver_destroy();
316 out:
317 return err;
318 }
319
320 static void __exit exit_nfs_v4(void)
321 {
322 /* Not called in the _init(), conditionally loaded */
323 nfs4_pnfs_v3_ds_connect_unload();
324
325 unregister_nfs_version(&nfs_v4);
326 #ifdef CONFIG_NFS_V4_2
327 nfs4_xattr_cache_exit();
328 nfs42_ssc_unregister_ops();
329 #endif
330 nfs4_unregister_sysctl();
331 nfs_idmap_quit();
332 nfs_dns_resolver_destroy();
333 }
334
335 MODULE_DESCRIPTION("NFSv4 client support");
336 MODULE_LICENSE("GPL");
337
338 module_init(init_nfs_v4);
339 module_exit(exit_nfs_v4);
340
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