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11#include <linux/exportfs.h>
12#include <linux/fs.h>
13#include <linux/file.h>
14#include <linux/module.h>
15#include <linux/mount.h>
16#include <linux/namei.h>
17#include <linux/sched.h>
18
19#define dprintk(fmt, args...) do{}while(0)
20
21
22static int get_name(const struct path *path, char *name, struct dentry *child);
23
24
25static int exportfs_get_name(struct vfsmount *mnt, struct dentry *dir,
26 char *name, struct dentry *child)
27{
28 const struct export_operations *nop = dir->d_sb->s_export_op;
29 struct path path = {.mnt = mnt, .dentry = dir};
30
31 if (nop->get_name)
32 return nop->get_name(dir, name, child);
33 else
34 return get_name(&path, name, child);
35}
36
37
38
39
40static struct dentry *
41find_acceptable_alias(struct dentry *result,
42 int (*acceptable)(void *context, struct dentry *dentry),
43 void *context)
44{
45 struct dentry *dentry, *toput = NULL;
46 struct inode *inode;
47
48 if (acceptable(context, result))
49 return result;
50
51 inode = result->d_inode;
52 spin_lock(&inode->i_lock);
53 hlist_for_each_entry(dentry, &inode->i_dentry, d_alias) {
54 dget(dentry);
55 spin_unlock(&inode->i_lock);
56 if (toput)
57 dput(toput);
58 if (dentry != result && acceptable(context, dentry)) {
59 dput(result);
60 return dentry;
61 }
62 spin_lock(&inode->i_lock);
63 toput = dentry;
64 }
65 spin_unlock(&inode->i_lock);
66
67 if (toput)
68 dput(toput);
69 return NULL;
70}
71
72
73
74
75static struct dentry *
76find_disconnected_root(struct dentry *dentry)
77{
78 dget(dentry);
79 while (!IS_ROOT(dentry)) {
80 struct dentry *parent = dget_parent(dentry);
81
82 if (!(parent->d_flags & DCACHE_DISCONNECTED)) {
83 dput(parent);
84 break;
85 }
86
87 dput(dentry);
88 dentry = parent;
89 }
90 return dentry;
91}
92
93
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96
97
98static int
99reconnect_path(struct vfsmount *mnt, struct dentry *target_dir, char *nbuf)
100{
101 int noprogress = 0;
102 int err = -ESTALE;
103
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109
110
111
112 while (target_dir->d_flags & DCACHE_DISCONNECTED && noprogress++ < 10) {
113 struct dentry *pd = find_disconnected_root(target_dir);
114
115 if (!IS_ROOT(pd)) {
116
117 spin_lock(&pd->d_lock);
118 pd->d_flags &= ~DCACHE_DISCONNECTED;
119 spin_unlock(&pd->d_lock);
120 noprogress = 0;
121 } else if (pd == mnt->mnt_sb->s_root) {
122 printk(KERN_ERR "export: Eeek filesystem root is not connected, impossible\n");
123 spin_lock(&pd->d_lock);
124 pd->d_flags &= ~DCACHE_DISCONNECTED;
125 spin_unlock(&pd->d_lock);
126 noprogress = 0;
127 } else {
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142
143 struct dentry *ppd = ERR_PTR(-EACCES);
144 struct dentry *npd;
145
146 mutex_lock(&pd->d_inode->i_mutex);
147 if (mnt->mnt_sb->s_export_op->get_parent)
148 ppd = mnt->mnt_sb->s_export_op->get_parent(pd);
149 mutex_unlock(&pd->d_inode->i_mutex);
150
151 if (IS_ERR(ppd)) {
152 err = PTR_ERR(ppd);
153 dprintk("%s: get_parent of %ld failed, err %d\n",
154 __func__, pd->d_inode->i_ino, err);
155 dput(pd);
156 break;
157 }
158
159 dprintk("%s: find name of %lu in %lu\n", __func__,
160 pd->d_inode->i_ino, ppd->d_inode->i_ino);
161 err = exportfs_get_name(mnt, ppd, nbuf, pd);
162 if (err) {
163 dput(ppd);
164 dput(pd);
165 if (err == -ENOENT)
166
167
168
169 continue;
170 break;
171 }
172 dprintk("%s: found name: %s\n", __func__, nbuf);
173 mutex_lock(&ppd->d_inode->i_mutex);
174 npd = lookup_one_len(nbuf, ppd, strlen(nbuf));
175 mutex_unlock(&ppd->d_inode->i_mutex);
176 if (IS_ERR(npd)) {
177 err = PTR_ERR(npd);
178 dprintk("%s: lookup failed: %d\n",
179 __func__, err);
180 dput(ppd);
181 dput(pd);
182 break;
183 }
184
185
186
187
188
189 if (npd == pd)
190 noprogress = 0;
191 else
192 printk("%s: npd != pd\n", __func__);
193 dput(npd);
194 dput(ppd);
195 if (IS_ROOT(pd)) {
196
197 dput(pd);
198 break;
199 }
200 }
201 dput(pd);
202 }
203
204 if (target_dir->d_flags & DCACHE_DISCONNECTED) {
205
206 if (!err)
207 err = -ESTALE;
208 return err;
209 }
210
211 return 0;
212}
213
214struct getdents_callback {
215 char *name;
216
217 unsigned long ino;
218 int found;
219 int sequence;
220};
221
222
223
224
225
226static int filldir_one(void * __buf, const char * name, int len,
227 loff_t pos, u64 ino, unsigned int d_type)
228{
229 struct getdents_callback *buf = __buf;
230 int result = 0;
231
232 buf->sequence++;
233 if (buf->ino == ino) {
234 memcpy(buf->name, name, len);
235 buf->name[len] = '\0';
236 buf->found = 1;
237 result = -1;
238 }
239 return result;
240}
241
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250
251static int get_name(const struct path *path, char *name, struct dentry *child)
252{
253 const struct cred *cred = current_cred();
254 struct inode *dir = path->dentry->d_inode;
255 int error;
256 struct file *file;
257 struct getdents_callback buffer;
258
259 error = -ENOTDIR;
260 if (!dir || !S_ISDIR(dir->i_mode))
261 goto out;
262 error = -EINVAL;
263 if (!dir->i_fop)
264 goto out;
265
266
267
268 file = dentry_open(path, O_RDONLY, cred);
269 error = PTR_ERR(file);
270 if (IS_ERR(file))
271 goto out;
272
273 error = -EINVAL;
274 if (!file->f_op->readdir)
275 goto out_close;
276
277 buffer.name = name;
278 buffer.ino = child->d_inode->i_ino;
279 buffer.found = 0;
280 buffer.sequence = 0;
281 while (1) {
282 int old_seq = buffer.sequence;
283
284 error = vfs_readdir(file, filldir_one, &buffer);
285 if (buffer.found) {
286 error = 0;
287 break;
288 }
289
290 if (error < 0)
291 break;
292
293 error = -ENOENT;
294 if (old_seq == buffer.sequence)
295 break;
296 }
297
298out_close:
299 fput(file);
300out:
301 return error;
302}
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315
316static int export_encode_fh(struct inode *inode, struct fid *fid,
317 int *max_len, struct inode *parent)
318{
319 int len = *max_len;
320 int type = FILEID_INO32_GEN;
321
322 if (parent && (len < 4)) {
323 *max_len = 4;
324 return FILEID_INVALID;
325 } else if (len < 2) {
326 *max_len = 2;
327 return FILEID_INVALID;
328 }
329
330 len = 2;
331 fid->i32.ino = inode->i_ino;
332 fid->i32.gen = inode->i_generation;
333 if (parent) {
334 fid->i32.parent_ino = parent->i_ino;
335 fid->i32.parent_gen = parent->i_generation;
336 len = 4;
337 type = FILEID_INO32_GEN_PARENT;
338 }
339 *max_len = len;
340 return type;
341}
342
343int exportfs_encode_inode_fh(struct inode *inode, struct fid *fid,
344 int *max_len, struct inode *parent)
345{
346 const struct export_operations *nop = inode->i_sb->s_export_op;
347
348 if (nop && nop->encode_fh)
349 return nop->encode_fh(inode, fid->raw, max_len, parent);
350
351 return export_encode_fh(inode, fid, max_len, parent);
352}
353EXPORT_SYMBOL_GPL(exportfs_encode_inode_fh);
354
355int exportfs_encode_fh(struct dentry *dentry, struct fid *fid, int *max_len,
356 int connectable)
357{
358 int error;
359 struct dentry *p = NULL;
360 struct inode *inode = dentry->d_inode, *parent = NULL;
361
362 if (connectable && !S_ISDIR(inode->i_mode)) {
363 p = dget_parent(dentry);
364
365
366
367
368 parent = p->d_inode;
369 }
370
371 error = exportfs_encode_inode_fh(inode, fid, max_len, parent);
372 dput(p);
373
374 return error;
375}
376EXPORT_SYMBOL_GPL(exportfs_encode_fh);
377
378struct dentry *exportfs_decode_fh(struct vfsmount *mnt, struct fid *fid,
379 int fh_len, int fileid_type,
380 int (*acceptable)(void *, struct dentry *), void *context)
381{
382 const struct export_operations *nop = mnt->mnt_sb->s_export_op;
383 struct dentry *result, *alias;
384 char nbuf[NAME_MAX+1];
385 int err;
386
387
388
389
390 if (!nop || !nop->fh_to_dentry)
391 return ERR_PTR(-ESTALE);
392 result = nop->fh_to_dentry(mnt->mnt_sb, fid, fh_len, fileid_type);
393 if (!result)
394 result = ERR_PTR(-ESTALE);
395 if (IS_ERR(result))
396 return result;
397
398 if (S_ISDIR(result->d_inode->i_mode)) {
399
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401
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404
405
406
407 if (result->d_flags & DCACHE_DISCONNECTED) {
408 err = reconnect_path(mnt, result, nbuf);
409 if (err)
410 goto err_result;
411 }
412
413 if (!acceptable(context, result)) {
414 err = -EACCES;
415 goto err_result;
416 }
417
418 return result;
419 } else {
420
421
422
423 struct dentry *target_dir, *nresult;
424
425
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427
428
429
430
431
432
433
434 alias = find_acceptable_alias(result, acceptable, context);
435 if (alias)
436 return alias;
437
438
439
440
441
442 err = -ESTALE;
443 if (!nop->fh_to_parent)
444 goto err_result;
445
446 target_dir = nop->fh_to_parent(mnt->mnt_sb, fid,
447 fh_len, fileid_type);
448 if (!target_dir)
449 goto err_result;
450 err = PTR_ERR(target_dir);
451 if (IS_ERR(target_dir))
452 goto err_result;
453
454
455
456
457
458
459 err = reconnect_path(mnt, target_dir, nbuf);
460 if (err) {
461 dput(target_dir);
462 goto err_result;
463 }
464
465
466
467
468
469
470 err = exportfs_get_name(mnt, target_dir, nbuf, result);
471 if (!err) {
472 mutex_lock(&target_dir->d_inode->i_mutex);
473 nresult = lookup_one_len(nbuf, target_dir,
474 strlen(nbuf));
475 mutex_unlock(&target_dir->d_inode->i_mutex);
476 if (!IS_ERR(nresult)) {
477 if (nresult->d_inode) {
478 dput(result);
479 result = nresult;
480 } else
481 dput(nresult);
482 }
483 }
484
485
486
487
488
489 dput(target_dir);
490
491
492
493
494
495 alias = find_acceptable_alias(result, acceptable, context);
496 if (!alias) {
497 err = -EACCES;
498 goto err_result;
499 }
500
501 return alias;
502 }
503
504 err_result:
505 dput(result);
506 return ERR_PTR(err);
507}
508EXPORT_SYMBOL_GPL(exportfs_decode_fh);
509
510MODULE_LICENSE("GPL");
511