xref: /openbmc/linux/net/9p/client.c (revision 643d1f7f)
1 /*
2  * net/9p/clnt.c
3  *
4  * 9P Client
5  *
6  *  Copyright (C) 2007 by Latchesar Ionkov <lucho@ionkov.net>
7  *
8  *  This program is free software; you can redistribute it and/or modify
9  *  it under the terms of the GNU General Public License version 2
10  *  as published by the Free Software Foundation.
11  *
12  *  This program is distributed in the hope that it will be useful,
13  *  but WITHOUT ANY WARRANTY; without even the implied warranty of
14  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
15  *  GNU General Public License for more details.
16  *
17  *  You should have received a copy of the GNU General Public License
18  *  along with this program; if not, write to:
19  *  Free Software Foundation
20  *  51 Franklin Street, Fifth Floor
21  *  Boston, MA  02111-1301  USA
22  *
23  */
24 
25 #include <linux/module.h>
26 #include <linux/errno.h>
27 #include <linux/fs.h>
28 #include <linux/idr.h>
29 #include <linux/mutex.h>
30 #include <linux/sched.h>
31 #include <linux/uaccess.h>
32 #include <net/9p/9p.h>
33 #include <linux/parser.h>
34 #include <net/9p/transport.h>
35 #include <net/9p/conn.h>
36 #include <net/9p/client.h>
37 
38 static struct p9_fid *p9_fid_create(struct p9_client *clnt);
39 static void p9_fid_destroy(struct p9_fid *fid);
40 static struct p9_stat *p9_clone_stat(struct p9_stat *st, int dotu);
41 
42 struct p9_client *p9_client_create(struct p9_trans *trans, int msize,
43 								   int dotu)
44 {
45 	int err, n;
46 	struct p9_client *clnt;
47 	struct p9_fcall *tc, *rc;
48 	struct p9_str *version;
49 
50 	err = 0;
51 	tc = NULL;
52 	rc = NULL;
53 	clnt = kmalloc(sizeof(struct p9_client), GFP_KERNEL);
54 	if (!clnt)
55 		return ERR_PTR(-ENOMEM);
56 
57 	P9_DPRINTK(P9_DEBUG_9P, "clnt %p trans %p msize %d dotu %d\n",
58 		clnt, trans, msize, dotu);
59 	spin_lock_init(&clnt->lock);
60 	clnt->trans = trans;
61 	clnt->msize = msize;
62 	clnt->dotu = dotu;
63 	INIT_LIST_HEAD(&clnt->fidlist);
64 	clnt->fidpool = p9_idpool_create();
65 	if (!clnt->fidpool) {
66 		err = PTR_ERR(clnt->fidpool);
67 		clnt->fidpool = NULL;
68 		goto error;
69 	}
70 
71 	clnt->conn = p9_conn_create(clnt->trans, clnt->msize, &clnt->dotu);
72 	if (IS_ERR(clnt->conn)) {
73 		err = PTR_ERR(clnt->conn);
74 		clnt->conn = NULL;
75 		goto error;
76 	}
77 
78 	tc = p9_create_tversion(clnt->msize, clnt->dotu?"9P2000.u":"9P2000");
79 	if (IS_ERR(tc)) {
80 		err = PTR_ERR(tc);
81 		tc = NULL;
82 		goto error;
83 	}
84 
85 	err = p9_conn_rpc(clnt->conn, tc, &rc);
86 	if (err)
87 		goto error;
88 
89 	version = &rc->params.rversion.version;
90 	if (version->len == 8 && !memcmp(version->str, "9P2000.u", 8))
91 		clnt->dotu = 1;
92 	else if (version->len == 6 && !memcmp(version->str, "9P2000", 6))
93 		clnt->dotu = 0;
94 	else {
95 		err = -EREMOTEIO;
96 		goto error;
97 	}
98 
99 	n = rc->params.rversion.msize;
100 	if (n < clnt->msize)
101 		clnt->msize = n;
102 
103 	kfree(tc);
104 	kfree(rc);
105 	return clnt;
106 
107 error:
108 	kfree(tc);
109 	kfree(rc);
110 	p9_client_destroy(clnt);
111 	return ERR_PTR(err);
112 }
113 EXPORT_SYMBOL(p9_client_create);
114 
115 void p9_client_destroy(struct p9_client *clnt)
116 {
117 	struct p9_fid *fid, *fidptr;
118 
119 	P9_DPRINTK(P9_DEBUG_9P, "clnt %p\n", clnt);
120 	if (clnt->conn) {
121 		p9_conn_destroy(clnt->conn);
122 		clnt->conn = NULL;
123 	}
124 
125 	if (clnt->trans) {
126 		clnt->trans->close(clnt->trans);
127 		kfree(clnt->trans);
128 		clnt->trans = NULL;
129 	}
130 
131 	list_for_each_entry_safe(fid, fidptr, &clnt->fidlist, flist)
132 		p9_fid_destroy(fid);
133 
134 	if (clnt->fidpool)
135 		p9_idpool_destroy(clnt->fidpool);
136 
137 	kfree(clnt);
138 }
139 EXPORT_SYMBOL(p9_client_destroy);
140 
141 void p9_client_disconnect(struct p9_client *clnt)
142 {
143 	P9_DPRINTK(P9_DEBUG_9P, "clnt %p\n", clnt);
144 	clnt->trans->status = Disconnected;
145 	p9_conn_cancel(clnt->conn, -EIO);
146 }
147 EXPORT_SYMBOL(p9_client_disconnect);
148 
149 struct p9_fid *p9_client_attach(struct p9_client *clnt, struct p9_fid *afid,
150 	char *uname, u32 n_uname, char *aname)
151 {
152 	int err;
153 	struct p9_fcall *tc, *rc;
154 	struct p9_fid *fid;
155 
156 	P9_DPRINTK(P9_DEBUG_9P, "clnt %p afid %d uname %s aname %s\n",
157 		clnt, afid?afid->fid:-1, uname, aname);
158 	err = 0;
159 	tc = NULL;
160 	rc = NULL;
161 
162 	fid = p9_fid_create(clnt);
163 	if (IS_ERR(fid)) {
164 		err = PTR_ERR(fid);
165 		fid = NULL;
166 		goto error;
167 	}
168 
169 	tc = p9_create_tattach(fid->fid, afid?afid->fid:P9_NOFID, uname, aname,
170 		n_uname, clnt->dotu);
171 	if (IS_ERR(tc)) {
172 		err = PTR_ERR(tc);
173 		tc = NULL;
174 		goto error;
175 	}
176 
177 	err = p9_conn_rpc(clnt->conn, tc, &rc);
178 	if (err)
179 		goto error;
180 
181 	memmove(&fid->qid, &rc->params.rattach.qid, sizeof(struct p9_qid));
182 	kfree(tc);
183 	kfree(rc);
184 	return fid;
185 
186 error:
187 	kfree(tc);
188 	kfree(rc);
189 	if (fid)
190 		p9_fid_destroy(fid);
191 	return ERR_PTR(err);
192 }
193 EXPORT_SYMBOL(p9_client_attach);
194 
195 struct p9_fid *p9_client_auth(struct p9_client *clnt, char *uname,
196 	u32 n_uname, char *aname)
197 {
198 	int err;
199 	struct p9_fcall *tc, *rc;
200 	struct p9_fid *fid;
201 
202 	P9_DPRINTK(P9_DEBUG_9P, "clnt %p uname %s aname %s\n", clnt, uname,
203 									aname);
204 	err = 0;
205 	tc = NULL;
206 	rc = NULL;
207 
208 	fid = p9_fid_create(clnt);
209 	if (IS_ERR(fid)) {
210 		err = PTR_ERR(fid);
211 		fid = NULL;
212 		goto error;
213 	}
214 
215 	tc = p9_create_tauth(fid->fid, uname, aname, n_uname, clnt->dotu);
216 	if (IS_ERR(tc)) {
217 		err = PTR_ERR(tc);
218 		tc = NULL;
219 		goto error;
220 	}
221 
222 	err = p9_conn_rpc(clnt->conn, tc, &rc);
223 	if (err)
224 		goto error;
225 
226 	memmove(&fid->qid, &rc->params.rauth.qid, sizeof(struct p9_qid));
227 	kfree(tc);
228 	kfree(rc);
229 	return fid;
230 
231 error:
232 	kfree(tc);
233 	kfree(rc);
234 	if (fid)
235 		p9_fid_destroy(fid);
236 	return ERR_PTR(err);
237 }
238 EXPORT_SYMBOL(p9_client_auth);
239 
240 struct p9_fid *p9_client_walk(struct p9_fid *oldfid, int nwname, char **wnames,
241 	int clone)
242 {
243 	int err;
244 	struct p9_fcall *tc, *rc;
245 	struct p9_client *clnt;
246 	struct p9_fid *fid;
247 
248 	P9_DPRINTK(P9_DEBUG_9P, "fid %d nwname %d wname[0] %s\n",
249 		oldfid->fid, nwname, wnames?wnames[0]:NULL);
250 	err = 0;
251 	tc = NULL;
252 	rc = NULL;
253 	clnt = oldfid->clnt;
254 	if (clone) {
255 		fid = p9_fid_create(clnt);
256 		if (IS_ERR(fid)) {
257 			err = PTR_ERR(fid);
258 			fid = NULL;
259 			goto error;
260 		}
261 
262 		fid->uid = oldfid->uid;
263 	} else
264 		fid = oldfid;
265 
266 	tc = p9_create_twalk(oldfid->fid, fid->fid, nwname, wnames);
267 	if (IS_ERR(tc)) {
268 		err = PTR_ERR(tc);
269 		tc = NULL;
270 		goto error;
271 	}
272 
273 	err = p9_conn_rpc(clnt->conn, tc, &rc);
274 	if (err) {
275 		if (rc && rc->id == P9_RWALK)
276 			goto clunk_fid;
277 		else
278 			goto error;
279 	}
280 
281 	if (rc->params.rwalk.nwqid != nwname) {
282 		err = -ENOENT;
283 		goto clunk_fid;
284 	}
285 
286 	if (nwname)
287 		memmove(&fid->qid,
288 			&rc->params.rwalk.wqids[rc->params.rwalk.nwqid - 1],
289 			sizeof(struct p9_qid));
290 	else
291 		fid->qid = oldfid->qid;
292 
293 	kfree(tc);
294 	kfree(rc);
295 	return fid;
296 
297 clunk_fid:
298 	kfree(tc);
299 	kfree(rc);
300 	rc = NULL;
301 	tc = p9_create_tclunk(fid->fid);
302 	if (IS_ERR(tc)) {
303 		err = PTR_ERR(tc);
304 		tc = NULL;
305 		goto error;
306 	}
307 
308 	p9_conn_rpc(clnt->conn, tc, &rc);
309 
310 error:
311 	kfree(tc);
312 	kfree(rc);
313 	if (fid && (fid != oldfid))
314 		p9_fid_destroy(fid);
315 
316 	return ERR_PTR(err);
317 }
318 EXPORT_SYMBOL(p9_client_walk);
319 
320 int p9_client_open(struct p9_fid *fid, int mode)
321 {
322 	int err;
323 	struct p9_fcall *tc, *rc;
324 	struct p9_client *clnt;
325 
326 	P9_DPRINTK(P9_DEBUG_9P, "fid %d mode %d\n", fid->fid, mode);
327 	err = 0;
328 	tc = NULL;
329 	rc = NULL;
330 	clnt = fid->clnt;
331 
332 	if (fid->mode != -1)
333 		return -EINVAL;
334 
335 	tc = p9_create_topen(fid->fid, mode);
336 	if (IS_ERR(tc)) {
337 		err = PTR_ERR(tc);
338 		tc = NULL;
339 		goto done;
340 	}
341 
342 	err = p9_conn_rpc(clnt->conn, tc, &rc);
343 	if (err)
344 		goto done;
345 
346 	fid->mode = mode;
347 	fid->iounit = rc->params.ropen.iounit;
348 
349 done:
350 	kfree(tc);
351 	kfree(rc);
352 	return err;
353 }
354 EXPORT_SYMBOL(p9_client_open);
355 
356 int p9_client_fcreate(struct p9_fid *fid, char *name, u32 perm, int mode,
357 		     char *extension)
358 {
359 	int err;
360 	struct p9_fcall *tc, *rc;
361 	struct p9_client *clnt;
362 
363 	P9_DPRINTK(P9_DEBUG_9P, "fid %d name %s perm %d mode %d\n", fid->fid,
364 		name, perm, mode);
365 	err = 0;
366 	tc = NULL;
367 	rc = NULL;
368 	clnt = fid->clnt;
369 
370 	if (fid->mode != -1)
371 		return -EINVAL;
372 
373 	tc = p9_create_tcreate(fid->fid, name, perm, mode, extension,
374 							       clnt->dotu);
375 	if (IS_ERR(tc)) {
376 		err = PTR_ERR(tc);
377 		tc = NULL;
378 		goto done;
379 	}
380 
381 	err = p9_conn_rpc(clnt->conn, tc, &rc);
382 	if (err)
383 		goto done;
384 
385 	fid->mode = mode;
386 	fid->iounit = rc->params.ropen.iounit;
387 
388 done:
389 	kfree(tc);
390 	kfree(rc);
391 	return err;
392 }
393 EXPORT_SYMBOL(p9_client_fcreate);
394 
395 int p9_client_clunk(struct p9_fid *fid)
396 {
397 	int err;
398 	struct p9_fcall *tc, *rc;
399 	struct p9_client *clnt;
400 
401 	P9_DPRINTK(P9_DEBUG_9P, "fid %d\n", fid->fid);
402 	err = 0;
403 	tc = NULL;
404 	rc = NULL;
405 	clnt = fid->clnt;
406 
407 	tc = p9_create_tclunk(fid->fid);
408 	if (IS_ERR(tc)) {
409 		err = PTR_ERR(tc);
410 		tc = NULL;
411 		goto done;
412 	}
413 
414 	err = p9_conn_rpc(clnt->conn, tc, &rc);
415 	if (err)
416 		goto done;
417 
418 	p9_fid_destroy(fid);
419 
420 done:
421 	kfree(tc);
422 	kfree(rc);
423 	return err;
424 }
425 EXPORT_SYMBOL(p9_client_clunk);
426 
427 int p9_client_remove(struct p9_fid *fid)
428 {
429 	int err;
430 	struct p9_fcall *tc, *rc;
431 	struct p9_client *clnt;
432 
433 	P9_DPRINTK(P9_DEBUG_9P, "fid %d\n", fid->fid);
434 	err = 0;
435 	tc = NULL;
436 	rc = NULL;
437 	clnt = fid->clnt;
438 
439 	tc = p9_create_tremove(fid->fid);
440 	if (IS_ERR(tc)) {
441 		err = PTR_ERR(tc);
442 		tc = NULL;
443 		goto done;
444 	}
445 
446 	err = p9_conn_rpc(clnt->conn, tc, &rc);
447 	if (err)
448 		goto done;
449 
450 	p9_fid_destroy(fid);
451 
452 done:
453 	kfree(tc);
454 	kfree(rc);
455 	return err;
456 }
457 EXPORT_SYMBOL(p9_client_remove);
458 
459 int p9_client_read(struct p9_fid *fid, char *data, u64 offset, u32 count)
460 {
461 	int err, n, rsize, total;
462 	struct p9_fcall *tc, *rc;
463 	struct p9_client *clnt;
464 
465 	P9_DPRINTK(P9_DEBUG_9P, "fid %d offset %llu %d\n", fid->fid,
466 					(long long unsigned) offset, count);
467 	err = 0;
468 	tc = NULL;
469 	rc = NULL;
470 	clnt = fid->clnt;
471 	total = 0;
472 
473 	rsize = fid->iounit;
474 	if (!rsize || rsize > clnt->msize-P9_IOHDRSZ)
475 		rsize = clnt->msize - P9_IOHDRSZ;
476 
477 	do {
478 		if (count < rsize)
479 			rsize = count;
480 
481 		tc = p9_create_tread(fid->fid, offset, rsize);
482 		if (IS_ERR(tc)) {
483 			err = PTR_ERR(tc);
484 			tc = NULL;
485 			goto error;
486 		}
487 
488 		err = p9_conn_rpc(clnt->conn, tc, &rc);
489 		if (err)
490 			goto error;
491 
492 		n = rc->params.rread.count;
493 		if (n > count)
494 			n = count;
495 
496 		memmove(data, rc->params.rread.data, n);
497 		count -= n;
498 		data += n;
499 		offset += n;
500 		total += n;
501 		kfree(tc);
502 		tc = NULL;
503 		kfree(rc);
504 		rc = NULL;
505 	} while (count > 0 && n == rsize);
506 
507 	return total;
508 
509 error:
510 	kfree(tc);
511 	kfree(rc);
512 	return err;
513 }
514 EXPORT_SYMBOL(p9_client_read);
515 
516 int p9_client_write(struct p9_fid *fid, char *data, u64 offset, u32 count)
517 {
518 	int err, n, rsize, total;
519 	struct p9_fcall *tc, *rc;
520 	struct p9_client *clnt;
521 
522 	P9_DPRINTK(P9_DEBUG_9P, "fid %d offset %llu count %d\n", fid->fid,
523 					(long long unsigned) offset, count);
524 	err = 0;
525 	tc = NULL;
526 	rc = NULL;
527 	clnt = fid->clnt;
528 	total = 0;
529 
530 	rsize = fid->iounit;
531 	if (!rsize || rsize > clnt->msize-P9_IOHDRSZ)
532 		rsize = clnt->msize - P9_IOHDRSZ;
533 
534 	do {
535 		if (count < rsize)
536 			rsize = count;
537 
538 		tc = p9_create_twrite(fid->fid, offset, rsize, data);
539 		if (IS_ERR(tc)) {
540 			err = PTR_ERR(tc);
541 			tc = NULL;
542 			goto error;
543 		}
544 
545 		err = p9_conn_rpc(clnt->conn, tc, &rc);
546 		if (err)
547 			goto error;
548 
549 		n = rc->params.rread.count;
550 		count -= n;
551 		data += n;
552 		offset += n;
553 		total += n;
554 		kfree(tc);
555 		tc = NULL;
556 		kfree(rc);
557 		rc = NULL;
558 	} while (count > 0);
559 
560 	return total;
561 
562 error:
563 	kfree(tc);
564 	kfree(rc);
565 	return err;
566 }
567 EXPORT_SYMBOL(p9_client_write);
568 
569 int
570 p9_client_uread(struct p9_fid *fid, char __user *data, u64 offset, u32 count)
571 {
572 	int err, n, rsize, total;
573 	struct p9_fcall *tc, *rc;
574 	struct p9_client *clnt;
575 
576 	P9_DPRINTK(P9_DEBUG_9P, "fid %d offset %llu count %d\n", fid->fid,
577 					(long long unsigned) offset, count);
578 	err = 0;
579 	tc = NULL;
580 	rc = NULL;
581 	clnt = fid->clnt;
582 	total = 0;
583 
584 	rsize = fid->iounit;
585 	if (!rsize || rsize > clnt->msize-P9_IOHDRSZ)
586 		rsize = clnt->msize - P9_IOHDRSZ;
587 
588 	do {
589 		if (count < rsize)
590 			rsize = count;
591 
592 		tc = p9_create_tread(fid->fid, offset, rsize);
593 		if (IS_ERR(tc)) {
594 			err = PTR_ERR(tc);
595 			tc = NULL;
596 			goto error;
597 		}
598 
599 		err = p9_conn_rpc(clnt->conn, tc, &rc);
600 		if (err)
601 			goto error;
602 
603 		n = rc->params.rread.count;
604 		if (n > count)
605 			n = count;
606 
607 		err = copy_to_user(data, rc->params.rread.data, n);
608 		if (err) {
609 			err = -EFAULT;
610 			goto error;
611 		}
612 
613 		count -= n;
614 		data += n;
615 		offset += n;
616 		total += n;
617 		kfree(tc);
618 		tc = NULL;
619 		kfree(rc);
620 		rc = NULL;
621 	} while (count > 0 && n == rsize);
622 
623 	return total;
624 
625 error:
626 	kfree(tc);
627 	kfree(rc);
628 	return err;
629 }
630 EXPORT_SYMBOL(p9_client_uread);
631 
632 int
633 p9_client_uwrite(struct p9_fid *fid, const char __user *data, u64 offset,
634 								   u32 count)
635 {
636 	int err, n, rsize, total;
637 	struct p9_fcall *tc, *rc;
638 	struct p9_client *clnt;
639 
640 	P9_DPRINTK(P9_DEBUG_9P, "fid %d offset %llu count %d\n", fid->fid,
641 					(long long unsigned) offset, count);
642 	err = 0;
643 	tc = NULL;
644 	rc = NULL;
645 	clnt = fid->clnt;
646 	total = 0;
647 
648 	rsize = fid->iounit;
649 	if (!rsize || rsize > clnt->msize-P9_IOHDRSZ)
650 		rsize = clnt->msize - P9_IOHDRSZ;
651 
652 	do {
653 		if (count < rsize)
654 			rsize = count;
655 
656 		tc = p9_create_twrite_u(fid->fid, offset, rsize, data);
657 		if (IS_ERR(tc)) {
658 			err = PTR_ERR(tc);
659 			tc = NULL;
660 			goto error;
661 		}
662 
663 		err = p9_conn_rpc(clnt->conn, tc, &rc);
664 		if (err)
665 			goto error;
666 
667 		n = rc->params.rread.count;
668 		count -= n;
669 		data += n;
670 		offset += n;
671 		total += n;
672 		kfree(tc);
673 		tc = NULL;
674 		kfree(rc);
675 		rc = NULL;
676 	} while (count > 0);
677 
678 	return total;
679 
680 error:
681 	kfree(tc);
682 	kfree(rc);
683 	return err;
684 }
685 EXPORT_SYMBOL(p9_client_uwrite);
686 
687 int p9_client_readn(struct p9_fid *fid, char *data, u64 offset, u32 count)
688 {
689 	int n, total;
690 
691 	P9_DPRINTK(P9_DEBUG_9P, "fid %d offset %llu count %d\n", fid->fid,
692 					(long long unsigned) offset, count);
693 	n = 0;
694 	total = 0;
695 	while (count) {
696 		n = p9_client_read(fid, data, offset, count);
697 		if (n <= 0)
698 			break;
699 
700 		data += n;
701 		offset += n;
702 		count -= n;
703 		total += n;
704 	}
705 
706 	if (n < 0)
707 		total = n;
708 
709 	return total;
710 }
711 EXPORT_SYMBOL(p9_client_readn);
712 
713 struct p9_stat *p9_client_stat(struct p9_fid *fid)
714 {
715 	int err;
716 	struct p9_fcall *tc, *rc;
717 	struct p9_client *clnt;
718 	struct p9_stat *ret;
719 
720 	P9_DPRINTK(P9_DEBUG_9P, "fid %d\n", fid->fid);
721 	err = 0;
722 	tc = NULL;
723 	rc = NULL;
724 	ret = NULL;
725 	clnt = fid->clnt;
726 
727 	tc = p9_create_tstat(fid->fid);
728 	if (IS_ERR(tc)) {
729 		err = PTR_ERR(tc);
730 		tc = NULL;
731 		goto error;
732 	}
733 
734 	err = p9_conn_rpc(clnt->conn, tc, &rc);
735 	if (err)
736 		goto error;
737 
738 	ret = p9_clone_stat(&rc->params.rstat.stat, clnt->dotu);
739 	if (IS_ERR(ret)) {
740 		err = PTR_ERR(ret);
741 		ret = NULL;
742 		goto error;
743 	}
744 
745 	kfree(tc);
746 	kfree(rc);
747 	return ret;
748 
749 error:
750 	kfree(tc);
751 	kfree(rc);
752 	kfree(ret);
753 	return ERR_PTR(err);
754 }
755 EXPORT_SYMBOL(p9_client_stat);
756 
757 int p9_client_wstat(struct p9_fid *fid, struct p9_wstat *wst)
758 {
759 	int err;
760 	struct p9_fcall *tc, *rc;
761 	struct p9_client *clnt;
762 
763 	P9_DPRINTK(P9_DEBUG_9P, "fid %d\n", fid->fid);
764 	err = 0;
765 	tc = NULL;
766 	rc = NULL;
767 	clnt = fid->clnt;
768 
769 	tc = p9_create_twstat(fid->fid, wst, clnt->dotu);
770 	if (IS_ERR(tc)) {
771 		err = PTR_ERR(tc);
772 		tc = NULL;
773 		goto done;
774 	}
775 
776 	err = p9_conn_rpc(clnt->conn, tc, &rc);
777 
778 done:
779 	kfree(tc);
780 	kfree(rc);
781 	return err;
782 }
783 EXPORT_SYMBOL(p9_client_wstat);
784 
785 struct p9_stat *p9_client_dirread(struct p9_fid *fid, u64 offset)
786 {
787 	int err, n, m;
788 	struct p9_fcall *tc, *rc;
789 	struct p9_client *clnt;
790 	struct p9_stat st, *ret;
791 
792 	P9_DPRINTK(P9_DEBUG_9P, "fid %d offset %llu\n", fid->fid,
793 						(long long unsigned) offset);
794 	err = 0;
795 	tc = NULL;
796 	rc = NULL;
797 	ret = NULL;
798 	clnt = fid->clnt;
799 
800 	/* if the offset is below or above the current response, free it */
801 	if (offset < fid->rdir_fpos || (fid->rdir_fcall &&
802 		offset >= fid->rdir_fpos+fid->rdir_fcall->params.rread.count)) {
803 		fid->rdir_pos = 0;
804 		if (fid->rdir_fcall)
805 			fid->rdir_fpos += fid->rdir_fcall->params.rread.count;
806 
807 		kfree(fid->rdir_fcall);
808 		fid->rdir_fcall = NULL;
809 		if (offset < fid->rdir_fpos)
810 			fid->rdir_fpos = 0;
811 	}
812 
813 	if (!fid->rdir_fcall) {
814 		n = fid->iounit;
815 		if (!n || n > clnt->msize-P9_IOHDRSZ)
816 			n = clnt->msize - P9_IOHDRSZ;
817 
818 		while (1) {
819 			if (fid->rdir_fcall) {
820 				fid->rdir_fpos +=
821 					fid->rdir_fcall->params.rread.count;
822 				kfree(fid->rdir_fcall);
823 				fid->rdir_fcall = NULL;
824 			}
825 
826 			tc = p9_create_tread(fid->fid, fid->rdir_fpos, n);
827 			if (IS_ERR(tc)) {
828 				err = PTR_ERR(tc);
829 				tc = NULL;
830 				goto error;
831 			}
832 
833 			err = p9_conn_rpc(clnt->conn, tc, &rc);
834 			if (err)
835 				goto error;
836 
837 			n = rc->params.rread.count;
838 			if (n == 0)
839 				goto done;
840 
841 			fid->rdir_fcall = rc;
842 			rc = NULL;
843 			if (offset >= fid->rdir_fpos &&
844 						offset < fid->rdir_fpos+n)
845 				break;
846 		}
847 
848 		fid->rdir_pos = 0;
849 	}
850 
851 	m = offset - fid->rdir_fpos;
852 	if (m < 0)
853 		goto done;
854 
855 	n = p9_deserialize_stat(fid->rdir_fcall->params.rread.data + m,
856 		fid->rdir_fcall->params.rread.count - m, &st, clnt->dotu);
857 
858 	if (!n) {
859 		err = -EIO;
860 		goto error;
861 	}
862 
863 	fid->rdir_pos += n;
864 	st.size = n;
865 	ret = p9_clone_stat(&st, clnt->dotu);
866 	if (IS_ERR(ret)) {
867 		err = PTR_ERR(ret);
868 		ret = NULL;
869 		goto error;
870 	}
871 
872 done:
873 	kfree(tc);
874 	kfree(rc);
875 	return ret;
876 
877 error:
878 	kfree(tc);
879 	kfree(rc);
880 	kfree(ret);
881 	return ERR_PTR(err);
882 }
883 EXPORT_SYMBOL(p9_client_dirread);
884 
885 static struct p9_stat *p9_clone_stat(struct p9_stat *st, int dotu)
886 {
887 	int n;
888 	char *p;
889 	struct p9_stat *ret;
890 
891 	n = sizeof(struct p9_stat) + st->name.len + st->uid.len + st->gid.len +
892 		st->muid.len;
893 
894 	if (dotu)
895 		n += st->extension.len;
896 
897 	ret = kmalloc(n, GFP_KERNEL);
898 	if (!ret)
899 		return ERR_PTR(-ENOMEM);
900 
901 	memmove(ret, st, sizeof(struct p9_stat));
902 	p = ((char *) ret) + sizeof(struct p9_stat);
903 	memmove(p, st->name.str, st->name.len);
904 	p += st->name.len;
905 	memmove(p, st->uid.str, st->uid.len);
906 	p += st->uid.len;
907 	memmove(p, st->gid.str, st->gid.len);
908 	p += st->gid.len;
909 	memmove(p, st->muid.str, st->muid.len);
910 	p += st->muid.len;
911 
912 	if (dotu) {
913 		memmove(p, st->extension.str, st->extension.len);
914 		p += st->extension.len;
915 	}
916 
917 	return ret;
918 }
919 
920 static struct p9_fid *p9_fid_create(struct p9_client *clnt)
921 {
922 	int err;
923 	struct p9_fid *fid;
924 
925 	P9_DPRINTK(P9_DEBUG_9P, "clnt %p\n", clnt);
926 	fid = kmalloc(sizeof(struct p9_fid), GFP_KERNEL);
927 	if (!fid)
928 		return ERR_PTR(-ENOMEM);
929 
930 	fid->fid = p9_idpool_get(clnt->fidpool);
931 	if (fid->fid < 0) {
932 		err = -ENOSPC;
933 		goto error;
934 	}
935 
936 	memset(&fid->qid, 0, sizeof(struct p9_qid));
937 	fid->mode = -1;
938 	fid->rdir_fpos = 0;
939 	fid->rdir_pos = 0;
940 	fid->rdir_fcall = NULL;
941 	fid->uid = current->fsuid;
942 	fid->clnt = clnt;
943 	fid->aux = NULL;
944 
945 	spin_lock(&clnt->lock);
946 	list_add(&fid->flist, &clnt->fidlist);
947 	spin_unlock(&clnt->lock);
948 
949 	return fid;
950 
951 error:
952 	kfree(fid);
953 	return ERR_PTR(err);
954 }
955 
956 static void p9_fid_destroy(struct p9_fid *fid)
957 {
958 	struct p9_client *clnt;
959 
960 	P9_DPRINTK(P9_DEBUG_9P, "fid %d\n", fid->fid);
961 	clnt = fid->clnt;
962 	p9_idpool_put(fid->fid, clnt->fidpool);
963 	spin_lock(&clnt->lock);
964 	list_del(&fid->flist);
965 	spin_unlock(&clnt->lock);
966 	kfree(fid->rdir_fcall);
967 	kfree(fid);
968 }
969