summaryrefslogtreecommitdiffstats
path: root/fs/cifs/link.c
blob: 970fcf2adb08c3ffa7992b6924974e19811ede07 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
/*
 *   fs/cifs/link.c
 *
 *   Copyright (C) International Business Machines  Corp., 2002,2008
 *   Author(s): Steve French (sfrench@us.ibm.com)
 *
 *   This library is free software; you can redistribute it and/or modify
 *   it under the terms of the GNU Lesser General Public License as published
 *   by the Free Software Foundation; either version 2.1 of the License, or
 *   (at your option) any later version.
 *
 *   This library is distributed in the hope that it will be useful,
 *   but WITHOUT ANY WARRANTY; without even the implied warranty of
 *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See
 *   the GNU Lesser General Public License for more details.
 *
 *   You should have received a copy of the GNU Lesser General Public License
 *   along with this library; if not, write to the Free Software
 *   Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
 */
#include <linux/fs.h>
#include <linux/stat.h>
#include <linux/slab.h>
#include <linux/namei.h>
#include "cifsfs.h"
#include "cifspdu.h"
#include "cifsglob.h"
#include "cifsproto.h"
#include "cifs_debug.h"
#include "cifs_fs_sb.h"
#include "cifs_unicode.h"
#include "smb2proto.h"
#include "cifs_ioctl.h"

/*
 * M-F Symlink Functions - Begin
 */

#define CIFS_MF_SYMLINK_LEN_OFFSET (4+1)
#define CIFS_MF_SYMLINK_MD5_OFFSET (CIFS_MF_SYMLINK_LEN_OFFSET+(4+1))
#define CIFS_MF_SYMLINK_LINK_OFFSET (CIFS_MF_SYMLINK_MD5_OFFSET+(32+1))
#define CIFS_MF_SYMLINK_LINK_MAXLEN (1024)
#define CIFS_MF_SYMLINK_FILE_SIZE \
	(CIFS_MF_SYMLINK_LINK_OFFSET + CIFS_MF_SYMLINK_LINK_MAXLEN)

#define CIFS_MF_SYMLINK_LEN_FORMAT "XSym\n%04u\n"
#define CIFS_MF_SYMLINK_MD5_FORMAT "%16phN\n"
#define CIFS_MF_SYMLINK_MD5_ARGS(md5_hash) md5_hash

static int
symlink_hash(unsigned int link_len, const char *link_str, u8 *md5_hash)
{
	int rc;
	struct crypto_shash *md5 = NULL;
	struct sdesc *sdescmd5 = NULL;

	rc = cifs_alloc_hash("md5", &md5, &sdescmd5);
	if (rc)
		goto symlink_hash_err;

	rc = crypto_shash_init(&sdescmd5->shash);
	if (rc) {
		cifs_dbg(VFS, "%s: Could not init md5 shash\n", __func__);
		goto symlink_hash_err;
	}
	rc = crypto_shash_update(&sdescmd5->shash, link_str, link_len);
	if (rc) {
		cifs_dbg(VFS, "%s: Could not update with link_str\n", __func__);
		goto symlink_hash_err;
	}
	rc = crypto_shash_final(&sdescmd5->shash, md5_hash);
	if (rc)
		cifs_dbg(VFS, "%s: Could not generate md5 hash\n", __func__);

symlink_hash_err:
	cifs_free_hash(&md5, &sdescmd5);
	return rc;
}

static int
parse_mf_symlink(const u8 *buf, unsigned int buf_len, unsigned int *_link_len,
		 char **_link_str)
{
	int rc;
	unsigned int link_len;
	const char *md5_str1;
	const char *link_str;
	u8 md5_hash[16];
	char md5_str2[34];

	if (buf_len != CIFS_MF_SYMLINK_FILE_SIZE)
		return -EINVAL;

	md5_str1 = (const char *)&buf[CIFS_MF_SYMLINK_MD5_OFFSET];
	link_str = (const char *)&buf[CIFS_MF_SYMLINK_LINK_OFFSET];

	rc = sscanf(buf, CIFS_MF_SYMLINK_LEN_FORMAT, &link_len);
	if (rc != 1)
		return -EINVAL;

	rc = symlink_hash(link_len, link_str, md5_hash);
	if (rc) {
		cifs_dbg(FYI, "%s: MD5 hash failure: %d\n", __func__, rc);
		return rc;
	}

	scnprintf(md5_str2, sizeof(md5_str2),
		  CIFS_MF_SYMLINK_MD5_FORMAT,
		  CIFS_MF_SYMLINK_MD5_ARGS(md5_hash));

	if (strncmp(md5_str1, md5_str2, 17) != 0)
		return -EINVAL;

	if (_link_str) {
		*_link_str = kstrndup(link_str, link_len, GFP_KERNEL);
		if (!*_link_str)
			return -ENOMEM;
	}

	*_link_len = link_len;
	return 0;
}

static int
format_mf_symlink(u8 *buf, unsigned int buf_len, const char *link_str)
{
	int rc;
	unsigned int link_len;
	unsigned int ofs;
	u8 md5_hash[16];

	if (buf_len != CIFS_MF_SYMLINK_FILE_SIZE)
		return -EINVAL;

	link_len = strlen(link_str);

	if (link_len > CIFS_MF_SYMLINK_LINK_MAXLEN)
		return -ENAMETOOLONG;

	rc = symlink_hash(link_len, link_str, md5_hash);
	if (rc) {
		cifs_dbg(FYI, "%s: MD5 hash failure: %d\n", __func__, rc);
		return rc;
	}

	scnprintf(buf, buf_len,
		  CIFS_MF_SYMLINK_LEN_FORMAT CIFS_MF_SYMLINK_MD5_FORMAT,
		  link_len,
		  CIFS_MF_SYMLINK_MD5_ARGS(md5_hash));

	ofs = CIFS_MF_SYMLINK_LINK_OFFSET;
	memcpy(buf + ofs, link_str, link_len);

	ofs += link_len;
	if (ofs < CIFS_MF_SYMLINK_FILE_SIZE) {
		buf[ofs] = '\n';
		ofs++;
	}

	while (ofs < CIFS_MF_SYMLINK_FILE_SIZE) {
		buf[ofs] = ' ';
		ofs++;
	}

	return 0;
}

bool
couldbe_mf_symlink(const struct cifs_fattr *fattr)
{
	if (!S_ISREG(fattr->cf_mode))
		/* it's not a symlink */
		return false;

	if (fattr->cf_eof != CIFS_MF_SYMLINK_FILE_SIZE)
		/* it's not a symlink */
		return false;

	return true;
}

static int
create_mf_symlink(const unsigned int xid, struct cifs_tcon *tcon,
		  struct cifs_sb_info *cifs_sb, const char *fromName,
		  const char *toName)
{
	int rc;
	u8 *buf;
	unsigned int bytes_written = 0;

	buf = kmalloc(CIFS_MF_SYMLINK_FILE_SIZE, GFP_KERNEL);
	if (!buf)
		return -ENOMEM;

	rc = format_mf_symlink(buf, CIFS_MF_SYMLINK_FILE_SIZE, toName);
	if (rc)
		goto out;

	if (tcon->ses->server->ops->create_mf_symlink)
		rc = tcon->ses->server->ops->create_mf_symlink(xid, tcon,
					cifs_sb, fromName, buf, &bytes_written);
	else
		rc = -EOPNOTSUPP;

	if (rc)
		goto out;

	if (bytes_written != CIFS_MF_SYMLINK_FILE_SIZE)
		rc = -EIO;
out:
	kfree(buf);
	return rc;
}

static int
query_mf_symlink(const unsigned int xid, struct cifs_tcon *tcon,
		 struct cifs_sb_info *cifs_sb, const unsigned char *path,
		 char **symlinkinfo)
{
	int rc;
	u8 *buf = NULL;
	unsigned int link_len = 0;
	unsigned int bytes_read = 0;

	buf = kmalloc(CIFS_MF_SYMLINK_FILE_SIZE, GFP_KERNEL);
	if (!buf)
		return -ENOMEM;

	if (tcon->ses->server->ops->query_mf_symlink)
		rc = tcon->ses->server->ops->query_mf_symlink(xid, tcon,
					      cifs_sb, path, buf, &bytes_read);
	else
		rc = -ENOSYS;

	if (rc)
		goto out;

	if (bytes_read == 0) { /* not a symlink */
		rc = -EINVAL;
		goto out;
	}

	rc = parse_mf_symlink(buf, bytes_read, &link_len, symlinkinfo);
out:
	kfree(buf);
	return rc;
}

int
check_mf_symlink(unsigned int xid, struct cifs_tcon *tcon,
		 struct cifs_sb_info *cifs_sb, struct cifs_fattr *fattr,
		 const unsigned char *path)
{
	int rc;
	u8 *buf = NULL;
	unsigned int link_len = 0;
	unsigned int bytes_read = 0;

	if (!couldbe_mf_symlink(fattr))
		/* it's not a symlink */
		return 0;

	buf = kmalloc(CIFS_MF_SYMLINK_FILE_SIZE, GFP_KERNEL);
	if (!buf)
		return -ENOMEM;

	if (tcon->ses->server->ops->query_mf_symlink)
		rc = tcon->ses->server->ops->query_mf_symlink(xid, tcon,
					      cifs_sb, path, buf, &bytes_read);
	else
		rc = -ENOSYS;

	if (rc)
		goto out;

	if (bytes_read == 0) /* not a symlink */
		goto out;

	rc = parse_mf_symlink(buf, bytes_read, &link_len, NULL);
	if (rc == -EINVAL) {
		/* it's not a symlink */
		rc = 0;
		goto out;
	}

	if (rc != 0)
		goto out;

	/* it is a symlink */
	fattr->cf_eof = link_len;
	fattr->cf_mode &= ~S_IFMT;
	fattr->cf_mode |= S_IFLNK | S_IRWXU | S_IRWXG | S_IRWXO;
	fattr->cf_dtype = DT_LNK;
out:
	kfree(buf);
	return rc;
}

/*
 * SMB 1.0 Protocol specific functions
 */

int
cifs_query_mf_symlink(unsigned int xid, struct cifs_tcon *tcon,
		      struct cifs_sb_info *cifs_sb, const unsigned char *path,
		      char *pbuf, unsigned int *pbytes_read)
{
	int rc;
	int oplock = 0;
	struct cifs_fid fid;
	struct cifs_open_parms oparms;
	struct cifs_io_parms io_parms = {0};
	int buf_type = CIFS_NO_BUFFER;
	FILE_ALL_INFO file_info;

	oparms.tcon = tcon;
	oparms.cifs_sb = cifs_sb;
	oparms.desired_access = GENERIC_READ;
	oparms.create_options = cifs_create_options(cifs_sb, CREATE_NOT_DIR);
	oparms.disposition = FILE_OPEN;
	oparms.path = path;
	oparms.fid = &fid;
	oparms.reconnect = false;

	rc = CIFS_open(xid, &oparms, &oplock, &file_info);
	if (rc)
		return rc;

	if (file_info.EndOfFile != cpu_to_le64(CIFS_MF_SYMLINK_FILE_SIZE)) {
		rc = -ENOENT;
		/* it's not a symlink */
		goto out;
	}

	io_parms.netfid = fid.netfid;
	io_parms.pid = current->tgid;
	io_parms.tcon = tcon;
	io_parms.offset = 0;
	io_parms.length = CIFS_MF_SYMLINK_FILE_SIZE;

	rc = CIFSSMBRead(xid, &io_parms, pbytes_read, &pbuf, &buf_type);
out:
	CIFSSMBClose(xid, tcon, fid.netfid);
	return rc;
}

int
cifs_create_mf_symlink(unsigned int xid, struct cifs_tcon *tcon,
		       struct cifs_sb_info *cifs_sb, const unsigned char *path,
		       char *pbuf, unsigned int *pbytes_written)
{
	int rc;
	int oplock = 0;
	struct cifs_fid fid;
	struct cifs_open_parms oparms;
	struct cifs_io_parms io_parms = {0};

	oparms.tcon = tcon;
	oparms.cifs_sb = cifs_sb;
	oparms.desired_access = GENERIC_WRITE;
	oparms.create_options = cifs_create_options(cifs_sb, CREATE_NOT_DIR);
	oparms.disposition = FILE_CREATE;
	oparms.path = path;
	oparms.fid = &fid;
	oparms.reconnect = false;

	rc = CIFS_open(xid, &oparms, &oplock, NULL);
	if (rc)
		return rc;

	io_parms.netfid = fid.netfid;
	io_parms.pid = current->tgid;
	io_parms.tcon = tcon;
	io_parms.offset = 0;
	io_parms.length = CIFS_MF_SYMLINK_FILE_SIZE;

	rc = CIFSSMBWrite(xid, &io_parms, pbytes_written, pbuf);
	CIFSSMBClose(xid, tcon, fid.netfid);
	return rc;
}

/*
 * SMB 2.1/SMB3 Protocol specific functions
 */
int
smb3_query_mf_symlink(unsigned int xid, struct cifs_tcon *tcon,
		      struct cifs_sb_info *cifs_sb, const unsigned char *path,
		      char *pbuf, unsigned int *pbytes_read)
{
	int rc;
	struct cifs_fid fid;
	struct cifs_open_parms oparms;
	struct cifs_io_parms io_parms = {0};
	int buf_type = CIFS_NO_BUFFER;
	__le16 *utf16_path;
	__u8 oplock = SMB2_OPLOCK_LEVEL_NONE;
	struct smb2_file_all_info *pfile_info = NULL;

	oparms.tcon = tcon;
	oparms.cifs_sb = cifs_sb;
	oparms.desired_access = GENERIC_READ;
	oparms.create_options = cifs_create_options(cifs_sb, CREATE_NOT_DIR);
	oparms.disposition = FILE_OPEN;
	oparms.fid = &fid;
	oparms.reconnect = false;

	utf16_path = cifs_convert_path_to_utf16(path, cifs_sb);
	if (utf16_path == NULL)
		return -ENOMEM;

	pfile_info = kzalloc(sizeof(struct smb2_file_all_info) + PATH_MAX * 2,
			     GFP_KERNEL);

	if (pfile_info == NULL) {
		kfree(utf16_path);
		return  -ENOMEM;
	}

	rc = SMB2_open(xid, &oparms, utf16_path, &oplock, pfile_info, NULL,
		       NULL, NULL);
	if (rc)
		goto qmf_out_open_fail;

	if (pfile_info->EndOfFile != cpu_to_le64(CIFS_MF_SYMLINK_FILE_SIZE)) {
		/* it's not a symlink */
		rc = -ENOENT; /* Is there a better rc to return? */
		goto qmf_out;
	}

	io_parms.netfid = fid.netfid;
	io_parms.pid = current->tgid;
	io_parms.tcon = tcon;
	io_parms.offset = 0;
	io_parms.length = CIFS_MF_SYMLINK_FILE_SIZE;
	io_parms.persistent_fid = fid.persistent_fid;
	io_parms.volatile_fid = fid.volatile_fid;
	rc = SMB2_read(xid, &io_parms, pbytes_read, &pbuf, &buf_type);
qmf_out:
	SMB2_close(xid, tcon, fid.persistent_fid, fid.volatile_fid);
qmf_out_open_fail:
	kfree(utf16_path);
	kfree(pfile_info);
	return rc;
}

int
smb3_create_mf_symlink(unsigned int xid, struct cifs_tcon *tcon,
		       struct cifs_sb_info *cifs_sb, const unsigned char *path,
		       char *pbuf, unsigned int *pbytes_written)
{
	int rc;
	struct cifs_fid fid;
	struct cifs_open_parms oparms;
	struct cifs_io_parms io_parms = {0};
	__le16 *utf16_path;
	__u8 oplock = SMB2_OPLOCK_LEVEL_NONE;
	struct kvec iov[2];

	cifs_dbg(FYI, "%s: path: %s\n", __func__, path);

	utf16_path = cifs_convert_path_to_utf16(path, cifs_sb);
	if (!utf16_path)
		return -ENOMEM;

	oparms.tcon = tcon;
	oparms.cifs_sb = cifs_sb;
	oparms.desired_access = GENERIC_WRITE;
	oparms.create_options = cifs_create_options(cifs_sb, CREATE_NOT_DIR);
	oparms.disposition = FILE_CREATE;
	oparms.fid = &fid;
	oparms.reconnect = false;

	rc = SMB2_open(xid, &oparms, utf16_path, &oplock, NULL, NULL,
		       NULL, NULL);
	if (rc) {
		kfree(utf16_path);
		return rc;
	}

	io_parms.netfid = fid.netfid;
	io_parms.pid = current->tgid;
	io_parms.tcon = tcon;
	io_parms.offset = 0;
	io_parms.length = CIFS_MF_SYMLINK_FILE_SIZE;
	io_parms.persistent_fid = fid.persistent_fid;
	io_parms.volatile_fid = fid.volatile_fid;

	/* iov[0] is reserved for smb header */
	iov[1].iov_base = pbuf;
	iov[1].iov_len = CIFS_MF_SYMLINK_FILE_SIZE;

	rc = SMB2_write(xid, &io_parms, pbytes_written, iov, 1);

	/* Make sure we wrote all of the symlink data */
	if ((rc == 0) && (*pbytes_written != CIFS_MF_SYMLINK_FILE_SIZE))
		rc = -EIO;

	SMB2_close(xid, tcon, fid.persistent_fid, fid.volatile_fid);

	kfree(utf16_path);
	return rc;
}

/*
 * M-F Symlink Functions - End
 */

int
cifs_hardlink(struct dentry *old_file, struct inode *inode,
	      struct dentry *direntry)
{
	int rc = -EACCES;
	unsigned int xid;
	const char *from_name, *to_name;
	void *page1, *page2;
	struct cifs_sb_info *cifs_sb = CIFS_SB(inode->i_sb);
	struct tcon_link *tlink;
	struct cifs_tcon *tcon;
	struct TCP_Server_Info *server;
	struct cifsInodeInfo *cifsInode;

	if (unlikely(cifs_forced_shutdown(cifs_sb)))
		return -EIO;

	tlink = cifs_sb_tlink(cifs_sb);
	if (IS_ERR(tlink))
		return PTR_ERR(tlink);
	tcon = tlink_tcon(tlink);

	xid = get_xid();
	page1 = alloc_dentry_path();
	page2 = alloc_dentry_path();

	from_name = build_path_from_dentry(old_file, page1);
	if (IS_ERR(from_name)) {
		rc = PTR_ERR(from_name);
		goto cifs_hl_exit;
	}
	to_name = build_path_from_dentry(direntry, page2);
	if (IS_ERR(to_name)) {
		rc = PTR_ERR(to_name);
		goto cifs_hl_exit;
	}

	if (tcon->unix_ext)
		rc = CIFSUnixCreateHardLink(xid, tcon, from_name, to_name,
					    cifs_sb->local_nls,
					    cifs_remap(cifs_sb));
	else {
		server = tcon->ses->server;
		if (!server->ops->create_hardlink) {
			rc = -ENOSYS;
			goto cifs_hl_exit;
		}
		rc = server->ops->create_hardlink(xid, tcon, from_name, to_name,
						  cifs_sb);
		if ((rc == -EIO) || (rc == -EINVAL))
			rc = -EOPNOTSUPP;
	}

	d_drop(direntry);	/* force new lookup from server of target */

	/*
	 * if source file is cached (oplocked) revalidate will not go to server
	 * until the file is closed or oplock broken so update nlinks locally
	 */
	if (d_really_is_positive(old_file)) {
		cifsInode = CIFS_I(d_inode(old_file));
		if (rc == 0) {
			spin_lock(&d_inode(old_file)->i_lock);
			inc_nlink(d_inode(old_file));
			spin_unlock(&d_inode(old_file)->i_lock);

			/*
			 * parent dir timestamps will update from srv within a
			 * second, would it really be worth it to set the parent
			 * dir cifs inode time to zero to force revalidate
			 * (faster) for it too?
			 */
		}
		/*
		 * if not oplocked will force revalidate to get info on source
		 * file from srv.  Note Samba server prior to 4.2 has bug -
		 * not updating src file ctime on hardlinks but Windows servers
		 * handle it properly
		 */
		cifsInode->time = 0;

		/*
		 * Will update parent dir timestamps from srv within a second.
		 * Would it really be worth it to set the parent dir (cifs
		 * inode) time field to zero to force revalidate on parent
		 * directory faster ie
		 *
		 * CIFS_I(inode)->time = 0;
		 */
	}

cifs_hl_exit:
	free_dentry_path(page1);
	free_dentry_path(page2);
	free_xid(xid);
	cifs_put_tlink(tlink);
	return rc;
}

const char *
cifs_get_link(struct dentry *direntry, struct inode *inode,
	      struct delayed_call *done)
{
	int rc = -ENOMEM;
	unsigned int xid;
	const char *full_path;
	void *page;
	char *target_path = NULL;
	struct cifs_sb_info *cifs_sb = CIFS_SB(inode->i_sb);
	struct tcon_link *tlink = NULL;
	struct cifs_tcon *tcon;
	struct TCP_Server_Info *server;

	if (!direntry)
		return ERR_PTR(-ECHILD);

	xid = get_xid();

	tlink = cifs_sb_tlink(cifs_sb);
	if (IS_ERR(tlink)) {
		free_xid(xid);
		return ERR_CAST(tlink);
	}
	tcon = tlink_tcon(tlink);
	server = tcon->ses->server;

	page = alloc_dentry_path();
	full_path = build_path_from_dentry(direntry, page);
	if (IS_ERR(full_path)) {
		free_xid(xid);
		cifs_put_tlink(tlink);
		free_dentry_path(page);
		return ERR_CAST(full_path);
	}

	cifs_dbg(FYI, "Full path: %s inode = 0x%p\n", full_path, inode);

	rc = -EACCES;
	/*
	 * First try Minshall+French Symlinks, if configured
	 * and fallback to UNIX Extensions Symlinks.
	 */
	if (cifs_sb->mnt_cifs_flags & CIFS_MOUNT_MF_SYMLINKS)
		rc = query_mf_symlink(xid, tcon, cifs_sb, full_path,
				      &target_path);

	if (rc != 0 && server->ops->query_symlink) {
		struct cifsInodeInfo *cifsi = CIFS_I(inode);
		bool reparse_point = false;

		if (cifsi->cifsAttrs & ATTR_REPARSE)
			reparse_point = true;

		rc = server->ops->query_symlink(xid, tcon, cifs_sb, full_path,
						&target_path, reparse_point);
	}

	free_dentry_path(page);
	free_xid(xid);
	cifs_put_tlink(tlink);
	if (rc != 0) {
		kfree(target_path);
		return ERR_PTR(rc);
	}
	set_delayed_call(done, kfree_link, target_path);
	return target_path;
}

int
cifs_symlink(struct user_namespace *mnt_userns, struct inode *inode,
	     struct dentry *direntry, const char *symname)
{
	int rc = -EOPNOTSUPP;
	unsigned int xid;
	struct cifs_sb_info *cifs_sb = CIFS_SB(inode->i_sb);
	struct tcon_link *tlink;
	struct cifs_tcon *pTcon;
	const char *full_path;
	void *page;
	struct inode *newinode = NULL;

	if (unlikely(cifs_forced_shutdown(cifs_sb)))
		return -EIO;

	page = alloc_dentry_path();
	if (!page)
		return -ENOMEM;

	xid = get_xid();

	tlink = cifs_sb_tlink(cifs_sb);
	if (IS_ERR(tlink)) {
		rc = PTR_ERR(tlink);
		goto symlink_exit;
	}
	pTcon = tlink_tcon(tlink);

	full_path = build_path_from_dentry(direntry, page);
	if (IS_ERR(full_path)) {
		rc = PTR_ERR(full_path);
		goto symlink_exit;
	}

	cifs_dbg(FYI, "Full path: %s\n", full_path);
	cifs_dbg(FYI, "symname is %s\n", symname);

	/* BB what if DFS and this volume is on different share? BB */
	if (cifs_sb->mnt_cifs_flags & CIFS_MOUNT_MF_SYMLINKS)
		rc = create_mf_symlink(xid, pTcon, cifs_sb, full_path, symname);
	else if (pTcon->unix_ext)
		rc = CIFSUnixCreateSymLink(xid, pTcon, full_path, symname,
					   cifs_sb->local_nls,
					   cifs_remap(cifs_sb));
	/* else
	   rc = CIFSCreateReparseSymLink(xid, pTcon, fromName, toName,
					cifs_sb_target->local_nls); */

	if (rc == 0) {
		if (pTcon->posix_extensions)
			rc = smb311_posix_get_inode_info(&newinode, full_path, inode->i_sb, xid);
		else if (pTcon->unix_ext)
			rc = cifs_get_inode_info_unix(&newinode, full_path,
						      inode->i_sb, xid);
		else
			rc = cifs_get_inode_info(&newinode, full_path, NULL,
						 inode->i_sb, xid, NULL);

		if (rc != 0) {
			cifs_dbg(FYI, "Create symlink ok, getinodeinfo fail rc = %d\n",
				 rc);
		} else {
			d_instantiate(direntry, newinode);
		}
	}
symlink_exit:
	free_dentry_path(page);
	cifs_put_tlink(tlink);
	free_xid(xid);
	return rc;
}