xref: /openbmc/linux/fs/nfs/callback_xdr.c (revision e8e0929d)
1 /*
2  * linux/fs/nfs/callback_xdr.c
3  *
4  * Copyright (C) 2004 Trond Myklebust
5  *
6  * NFSv4 callback encode/decode procedures
7  */
8 #include <linux/kernel.h>
9 #include <linux/sunrpc/svc.h>
10 #include <linux/nfs4.h>
11 #include <linux/nfs_fs.h>
12 #include "nfs4_fs.h"
13 #include "callback.h"
14 
15 #define CB_OP_TAGLEN_MAXSZ	(512)
16 #define CB_OP_HDR_RES_MAXSZ	(2 + CB_OP_TAGLEN_MAXSZ)
17 #define CB_OP_GETATTR_BITMAP_MAXSZ	(4)
18 #define CB_OP_GETATTR_RES_MAXSZ	(CB_OP_HDR_RES_MAXSZ + \
19 				CB_OP_GETATTR_BITMAP_MAXSZ + \
20 				2 + 2 + 3 + 3)
21 #define CB_OP_RECALL_RES_MAXSZ	(CB_OP_HDR_RES_MAXSZ)
22 
23 #if defined(CONFIG_NFS_V4_1)
24 #define CB_OP_SEQUENCE_RES_MAXSZ	(CB_OP_HDR_RES_MAXSZ + \
25 					4 + 1 + 3)
26 #endif /* CONFIG_NFS_V4_1 */
27 
28 #define NFSDBG_FACILITY NFSDBG_CALLBACK
29 
30 typedef __be32 (*callback_process_op_t)(void *, void *);
31 typedef __be32 (*callback_decode_arg_t)(struct svc_rqst *, struct xdr_stream *, void *);
32 typedef __be32 (*callback_encode_res_t)(struct svc_rqst *, struct xdr_stream *, void *);
33 
34 
35 struct callback_op {
36 	callback_process_op_t process_op;
37 	callback_decode_arg_t decode_args;
38 	callback_encode_res_t encode_res;
39 	long res_maxsize;
40 };
41 
42 static struct callback_op callback_ops[];
43 
44 static __be32 nfs4_callback_null(struct svc_rqst *rqstp, void *argp, void *resp)
45 {
46 	return htonl(NFS4_OK);
47 }
48 
49 static int nfs4_decode_void(struct svc_rqst *rqstp, __be32 *p, void *dummy)
50 {
51 	return xdr_argsize_check(rqstp, p);
52 }
53 
54 static int nfs4_encode_void(struct svc_rqst *rqstp, __be32 *p, void *dummy)
55 {
56 	return xdr_ressize_check(rqstp, p);
57 }
58 
59 static __be32 *read_buf(struct xdr_stream *xdr, int nbytes)
60 {
61 	__be32 *p;
62 
63 	p = xdr_inline_decode(xdr, nbytes);
64 	if (unlikely(p == NULL))
65 		printk(KERN_WARNING "NFSv4 callback reply buffer overflowed!\n");
66 	return p;
67 }
68 
69 static __be32 decode_string(struct xdr_stream *xdr, unsigned int *len, const char **str)
70 {
71 	__be32 *p;
72 
73 	p = read_buf(xdr, 4);
74 	if (unlikely(p == NULL))
75 		return htonl(NFS4ERR_RESOURCE);
76 	*len = ntohl(*p);
77 
78 	if (*len != 0) {
79 		p = read_buf(xdr, *len);
80 		if (unlikely(p == NULL))
81 			return htonl(NFS4ERR_RESOURCE);
82 		*str = (const char *)p;
83 	} else
84 		*str = NULL;
85 
86 	return 0;
87 }
88 
89 static __be32 decode_fh(struct xdr_stream *xdr, struct nfs_fh *fh)
90 {
91 	__be32 *p;
92 
93 	p = read_buf(xdr, 4);
94 	if (unlikely(p == NULL))
95 		return htonl(NFS4ERR_RESOURCE);
96 	fh->size = ntohl(*p);
97 	if (fh->size > NFS4_FHSIZE)
98 		return htonl(NFS4ERR_BADHANDLE);
99 	p = read_buf(xdr, fh->size);
100 	if (unlikely(p == NULL))
101 		return htonl(NFS4ERR_RESOURCE);
102 	memcpy(&fh->data[0], p, fh->size);
103 	memset(&fh->data[fh->size], 0, sizeof(fh->data) - fh->size);
104 	return 0;
105 }
106 
107 static __be32 decode_bitmap(struct xdr_stream *xdr, uint32_t *bitmap)
108 {
109 	__be32 *p;
110 	unsigned int attrlen;
111 
112 	p = read_buf(xdr, 4);
113 	if (unlikely(p == NULL))
114 		return htonl(NFS4ERR_RESOURCE);
115 	attrlen = ntohl(*p);
116 	p = read_buf(xdr, attrlen << 2);
117 	if (unlikely(p == NULL))
118 		return htonl(NFS4ERR_RESOURCE);
119 	if (likely(attrlen > 0))
120 		bitmap[0] = ntohl(*p++);
121 	if (attrlen > 1)
122 		bitmap[1] = ntohl(*p);
123 	return 0;
124 }
125 
126 static __be32 decode_stateid(struct xdr_stream *xdr, nfs4_stateid *stateid)
127 {
128 	__be32 *p;
129 
130 	p = read_buf(xdr, 16);
131 	if (unlikely(p == NULL))
132 		return htonl(NFS4ERR_RESOURCE);
133 	memcpy(stateid->data, p, 16);
134 	return 0;
135 }
136 
137 static __be32 decode_compound_hdr_arg(struct xdr_stream *xdr, struct cb_compound_hdr_arg *hdr)
138 {
139 	__be32 *p;
140 	__be32 status;
141 
142 	status = decode_string(xdr, &hdr->taglen, &hdr->tag);
143 	if (unlikely(status != 0))
144 		return status;
145 	/* We do not like overly long tags! */
146 	if (hdr->taglen > CB_OP_TAGLEN_MAXSZ - 12) {
147 		printk("NFSv4 CALLBACK %s: client sent tag of length %u\n",
148 				__func__, hdr->taglen);
149 		return htonl(NFS4ERR_RESOURCE);
150 	}
151 	p = read_buf(xdr, 12);
152 	if (unlikely(p == NULL))
153 		return htonl(NFS4ERR_RESOURCE);
154 	hdr->minorversion = ntohl(*p++);
155 	/* Check minor version is zero or one. */
156 	if (hdr->minorversion <= 1) {
157 		p++;	/* skip callback_ident */
158 	} else {
159 		printk(KERN_WARNING "%s: NFSv4 server callback with "
160 			"illegal minor version %u!\n",
161 			__func__, hdr->minorversion);
162 		return htonl(NFS4ERR_MINOR_VERS_MISMATCH);
163 	}
164 	hdr->nops = ntohl(*p);
165 	dprintk("%s: minorversion %d nops %d\n", __func__,
166 		hdr->minorversion, hdr->nops);
167 	return 0;
168 }
169 
170 static __be32 decode_op_hdr(struct xdr_stream *xdr, unsigned int *op)
171 {
172 	__be32 *p;
173 	p = read_buf(xdr, 4);
174 	if (unlikely(p == NULL))
175 		return htonl(NFS4ERR_RESOURCE);
176 	*op = ntohl(*p);
177 	return 0;
178 }
179 
180 static __be32 decode_getattr_args(struct svc_rqst *rqstp, struct xdr_stream *xdr, struct cb_getattrargs *args)
181 {
182 	__be32 status;
183 
184 	status = decode_fh(xdr, &args->fh);
185 	if (unlikely(status != 0))
186 		goto out;
187 	args->addr = svc_addr(rqstp);
188 	status = decode_bitmap(xdr, args->bitmap);
189 out:
190 	dprintk("%s: exit with status = %d\n", __func__, ntohl(status));
191 	return status;
192 }
193 
194 static __be32 decode_recall_args(struct svc_rqst *rqstp, struct xdr_stream *xdr, struct cb_recallargs *args)
195 {
196 	__be32 *p;
197 	__be32 status;
198 
199 	args->addr = svc_addr(rqstp);
200 	status = decode_stateid(xdr, &args->stateid);
201 	if (unlikely(status != 0))
202 		goto out;
203 	p = read_buf(xdr, 4);
204 	if (unlikely(p == NULL)) {
205 		status = htonl(NFS4ERR_RESOURCE);
206 		goto out;
207 	}
208 	args->truncate = ntohl(*p);
209 	status = decode_fh(xdr, &args->fh);
210 out:
211 	dprintk("%s: exit with status = %d\n", __func__, ntohl(status));
212 	return status;
213 }
214 
215 #if defined(CONFIG_NFS_V4_1)
216 
217 static unsigned decode_sessionid(struct xdr_stream *xdr,
218 				 struct nfs4_sessionid *sid)
219 {
220 	uint32_t *p;
221 	int len = NFS4_MAX_SESSIONID_LEN;
222 
223 	p = read_buf(xdr, len);
224 	if (unlikely(p == NULL))
225 		return htonl(NFS4ERR_RESOURCE);
226 
227 	memcpy(sid->data, p, len);
228 	return 0;
229 }
230 
231 static unsigned decode_rc_list(struct xdr_stream *xdr,
232 			       struct referring_call_list *rc_list)
233 {
234 	uint32_t *p;
235 	int i;
236 	unsigned status;
237 
238 	status = decode_sessionid(xdr, &rc_list->rcl_sessionid);
239 	if (status)
240 		goto out;
241 
242 	status = htonl(NFS4ERR_RESOURCE);
243 	p = read_buf(xdr, sizeof(uint32_t));
244 	if (unlikely(p == NULL))
245 		goto out;
246 
247 	rc_list->rcl_nrefcalls = ntohl(*p++);
248 	if (rc_list->rcl_nrefcalls) {
249 		p = read_buf(xdr,
250 			     rc_list->rcl_nrefcalls * 2 * sizeof(uint32_t));
251 		if (unlikely(p == NULL))
252 			goto out;
253 		rc_list->rcl_refcalls = kmalloc(rc_list->rcl_nrefcalls *
254 						sizeof(*rc_list->rcl_refcalls),
255 						GFP_KERNEL);
256 		if (unlikely(rc_list->rcl_refcalls == NULL))
257 			goto out;
258 		for (i = 0; i < rc_list->rcl_nrefcalls; i++) {
259 			rc_list->rcl_refcalls[i].rc_sequenceid = ntohl(*p++);
260 			rc_list->rcl_refcalls[i].rc_slotid = ntohl(*p++);
261 		}
262 	}
263 	status = 0;
264 
265 out:
266 	return status;
267 }
268 
269 static unsigned decode_cb_sequence_args(struct svc_rqst *rqstp,
270 					struct xdr_stream *xdr,
271 					struct cb_sequenceargs *args)
272 {
273 	uint32_t *p;
274 	int i;
275 	unsigned status;
276 
277 	status = decode_sessionid(xdr, &args->csa_sessionid);
278 	if (status)
279 		goto out;
280 
281 	status = htonl(NFS4ERR_RESOURCE);
282 	p = read_buf(xdr, 5 * sizeof(uint32_t));
283 	if (unlikely(p == NULL))
284 		goto out;
285 
286 	args->csa_addr = svc_addr(rqstp);
287 	args->csa_sequenceid = ntohl(*p++);
288 	args->csa_slotid = ntohl(*p++);
289 	args->csa_highestslotid = ntohl(*p++);
290 	args->csa_cachethis = ntohl(*p++);
291 	args->csa_nrclists = ntohl(*p++);
292 	args->csa_rclists = NULL;
293 	if (args->csa_nrclists) {
294 		args->csa_rclists = kmalloc(args->csa_nrclists *
295 					    sizeof(*args->csa_rclists),
296 					    GFP_KERNEL);
297 		if (unlikely(args->csa_rclists == NULL))
298 			goto out;
299 
300 		for (i = 0; i < args->csa_nrclists; i++) {
301 			status = decode_rc_list(xdr, &args->csa_rclists[i]);
302 			if (status)
303 				goto out_free;
304 		}
305 	}
306 	status = 0;
307 
308 	dprintk("%s: sessionid %x:%x:%x:%x sequenceid %u slotid %u "
309 		"highestslotid %u cachethis %d nrclists %u\n",
310 		__func__,
311 		((u32 *)&args->csa_sessionid)[0],
312 		((u32 *)&args->csa_sessionid)[1],
313 		((u32 *)&args->csa_sessionid)[2],
314 		((u32 *)&args->csa_sessionid)[3],
315 		args->csa_sequenceid, args->csa_slotid,
316 		args->csa_highestslotid, args->csa_cachethis,
317 		args->csa_nrclists);
318 out:
319 	dprintk("%s: exit with status = %d\n", __func__, ntohl(status));
320 	return status;
321 
322 out_free:
323 	for (i = 0; i < args->csa_nrclists; i++)
324 		kfree(args->csa_rclists[i].rcl_refcalls);
325 	kfree(args->csa_rclists);
326 	goto out;
327 }
328 
329 #endif /* CONFIG_NFS_V4_1 */
330 
331 static __be32 encode_string(struct xdr_stream *xdr, unsigned int len, const char *str)
332 {
333 	__be32 *p;
334 
335 	p = xdr_reserve_space(xdr, 4 + len);
336 	if (unlikely(p == NULL))
337 		return htonl(NFS4ERR_RESOURCE);
338 	xdr_encode_opaque(p, str, len);
339 	return 0;
340 }
341 
342 #define CB_SUPPORTED_ATTR0 (FATTR4_WORD0_CHANGE|FATTR4_WORD0_SIZE)
343 #define CB_SUPPORTED_ATTR1 (FATTR4_WORD1_TIME_METADATA|FATTR4_WORD1_TIME_MODIFY)
344 static __be32 encode_attr_bitmap(struct xdr_stream *xdr, const uint32_t *bitmap, __be32 **savep)
345 {
346 	__be32 bm[2];
347 	__be32 *p;
348 
349 	bm[0] = htonl(bitmap[0] & CB_SUPPORTED_ATTR0);
350 	bm[1] = htonl(bitmap[1] & CB_SUPPORTED_ATTR1);
351 	if (bm[1] != 0) {
352 		p = xdr_reserve_space(xdr, 16);
353 		if (unlikely(p == NULL))
354 			return htonl(NFS4ERR_RESOURCE);
355 		*p++ = htonl(2);
356 		*p++ = bm[0];
357 		*p++ = bm[1];
358 	} else if (bm[0] != 0) {
359 		p = xdr_reserve_space(xdr, 12);
360 		if (unlikely(p == NULL))
361 			return htonl(NFS4ERR_RESOURCE);
362 		*p++ = htonl(1);
363 		*p++ = bm[0];
364 	} else {
365 		p = xdr_reserve_space(xdr, 8);
366 		if (unlikely(p == NULL))
367 			return htonl(NFS4ERR_RESOURCE);
368 		*p++ = htonl(0);
369 	}
370 	*savep = p;
371 	return 0;
372 }
373 
374 static __be32 encode_attr_change(struct xdr_stream *xdr, const uint32_t *bitmap, uint64_t change)
375 {
376 	__be32 *p;
377 
378 	if (!(bitmap[0] & FATTR4_WORD0_CHANGE))
379 		return 0;
380 	p = xdr_reserve_space(xdr, 8);
381 	if (unlikely(!p))
382 		return htonl(NFS4ERR_RESOURCE);
383 	p = xdr_encode_hyper(p, change);
384 	return 0;
385 }
386 
387 static __be32 encode_attr_size(struct xdr_stream *xdr, const uint32_t *bitmap, uint64_t size)
388 {
389 	__be32 *p;
390 
391 	if (!(bitmap[0] & FATTR4_WORD0_SIZE))
392 		return 0;
393 	p = xdr_reserve_space(xdr, 8);
394 	if (unlikely(!p))
395 		return htonl(NFS4ERR_RESOURCE);
396 	p = xdr_encode_hyper(p, size);
397 	return 0;
398 }
399 
400 static __be32 encode_attr_time(struct xdr_stream *xdr, const struct timespec *time)
401 {
402 	__be32 *p;
403 
404 	p = xdr_reserve_space(xdr, 12);
405 	if (unlikely(!p))
406 		return htonl(NFS4ERR_RESOURCE);
407 	p = xdr_encode_hyper(p, time->tv_sec);
408 	*p = htonl(time->tv_nsec);
409 	return 0;
410 }
411 
412 static __be32 encode_attr_ctime(struct xdr_stream *xdr, const uint32_t *bitmap, const struct timespec *time)
413 {
414 	if (!(bitmap[1] & FATTR4_WORD1_TIME_METADATA))
415 		return 0;
416 	return encode_attr_time(xdr,time);
417 }
418 
419 static __be32 encode_attr_mtime(struct xdr_stream *xdr, const uint32_t *bitmap, const struct timespec *time)
420 {
421 	if (!(bitmap[1] & FATTR4_WORD1_TIME_MODIFY))
422 		return 0;
423 	return encode_attr_time(xdr,time);
424 }
425 
426 static __be32 encode_compound_hdr_res(struct xdr_stream *xdr, struct cb_compound_hdr_res *hdr)
427 {
428 	__be32 status;
429 
430 	hdr->status = xdr_reserve_space(xdr, 4);
431 	if (unlikely(hdr->status == NULL))
432 		return htonl(NFS4ERR_RESOURCE);
433 	status = encode_string(xdr, hdr->taglen, hdr->tag);
434 	if (unlikely(status != 0))
435 		return status;
436 	hdr->nops = xdr_reserve_space(xdr, 4);
437 	if (unlikely(hdr->nops == NULL))
438 		return htonl(NFS4ERR_RESOURCE);
439 	return 0;
440 }
441 
442 static __be32 encode_op_hdr(struct xdr_stream *xdr, uint32_t op, __be32 res)
443 {
444 	__be32 *p;
445 
446 	p = xdr_reserve_space(xdr, 8);
447 	if (unlikely(p == NULL))
448 		return htonl(NFS4ERR_RESOURCE);
449 	*p++ = htonl(op);
450 	*p = res;
451 	return 0;
452 }
453 
454 static __be32 encode_getattr_res(struct svc_rqst *rqstp, struct xdr_stream *xdr, const struct cb_getattrres *res)
455 {
456 	__be32 *savep = NULL;
457 	__be32 status = res->status;
458 
459 	if (unlikely(status != 0))
460 		goto out;
461 	status = encode_attr_bitmap(xdr, res->bitmap, &savep);
462 	if (unlikely(status != 0))
463 		goto out;
464 	status = encode_attr_change(xdr, res->bitmap, res->change_attr);
465 	if (unlikely(status != 0))
466 		goto out;
467 	status = encode_attr_size(xdr, res->bitmap, res->size);
468 	if (unlikely(status != 0))
469 		goto out;
470 	status = encode_attr_ctime(xdr, res->bitmap, &res->ctime);
471 	if (unlikely(status != 0))
472 		goto out;
473 	status = encode_attr_mtime(xdr, res->bitmap, &res->mtime);
474 	*savep = htonl((unsigned int)((char *)xdr->p - (char *)(savep+1)));
475 out:
476 	dprintk("%s: exit with status = %d\n", __func__, ntohl(status));
477 	return status;
478 }
479 
480 #if defined(CONFIG_NFS_V4_1)
481 
482 static unsigned encode_sessionid(struct xdr_stream *xdr,
483 				 const struct nfs4_sessionid *sid)
484 {
485 	uint32_t *p;
486 	int len = NFS4_MAX_SESSIONID_LEN;
487 
488 	p = xdr_reserve_space(xdr, len);
489 	if (unlikely(p == NULL))
490 		return htonl(NFS4ERR_RESOURCE);
491 
492 	memcpy(p, sid, len);
493 	return 0;
494 }
495 
496 static unsigned encode_cb_sequence_res(struct svc_rqst *rqstp,
497 				       struct xdr_stream *xdr,
498 				       const struct cb_sequenceres *res)
499 {
500 	uint32_t *p;
501 	unsigned status = res->csr_status;
502 
503 	if (unlikely(status != 0))
504 		goto out;
505 
506 	encode_sessionid(xdr, &res->csr_sessionid);
507 
508 	p = xdr_reserve_space(xdr, 4 * sizeof(uint32_t));
509 	if (unlikely(p == NULL))
510 		return htonl(NFS4ERR_RESOURCE);
511 
512 	*p++ = htonl(res->csr_sequenceid);
513 	*p++ = htonl(res->csr_slotid);
514 	*p++ = htonl(res->csr_highestslotid);
515 	*p++ = htonl(res->csr_target_highestslotid);
516 out:
517 	dprintk("%s: exit with status = %d\n", __func__, ntohl(status));
518 	return status;
519 }
520 
521 static __be32
522 preprocess_nfs41_op(int nop, unsigned int op_nr, struct callback_op **op)
523 {
524 	if (op_nr == OP_CB_SEQUENCE) {
525 		if (nop != 0)
526 			return htonl(NFS4ERR_SEQUENCE_POS);
527 	} else {
528 		if (nop == 0)
529 			return htonl(NFS4ERR_OP_NOT_IN_SESSION);
530 	}
531 
532 	switch (op_nr) {
533 	case OP_CB_GETATTR:
534 	case OP_CB_RECALL:
535 	case OP_CB_SEQUENCE:
536 		*op = &callback_ops[op_nr];
537 		break;
538 
539 	case OP_CB_LAYOUTRECALL:
540 	case OP_CB_NOTIFY_DEVICEID:
541 	case OP_CB_NOTIFY:
542 	case OP_CB_PUSH_DELEG:
543 	case OP_CB_RECALL_ANY:
544 	case OP_CB_RECALLABLE_OBJ_AVAIL:
545 	case OP_CB_RECALL_SLOT:
546 	case OP_CB_WANTS_CANCELLED:
547 	case OP_CB_NOTIFY_LOCK:
548 		return htonl(NFS4ERR_NOTSUPP);
549 
550 	default:
551 		return htonl(NFS4ERR_OP_ILLEGAL);
552 	}
553 
554 	return htonl(NFS_OK);
555 }
556 
557 #else /* CONFIG_NFS_V4_1 */
558 
559 static __be32
560 preprocess_nfs41_op(int nop, unsigned int op_nr, struct callback_op **op)
561 {
562 	return htonl(NFS4ERR_MINOR_VERS_MISMATCH);
563 }
564 
565 #endif /* CONFIG_NFS_V4_1 */
566 
567 static __be32
568 preprocess_nfs4_op(unsigned int op_nr, struct callback_op **op)
569 {
570 	switch (op_nr) {
571 	case OP_CB_GETATTR:
572 	case OP_CB_RECALL:
573 		*op = &callback_ops[op_nr];
574 		break;
575 	default:
576 		return htonl(NFS4ERR_OP_ILLEGAL);
577 	}
578 
579 	return htonl(NFS_OK);
580 }
581 
582 static __be32 process_op(uint32_t minorversion, int nop,
583 		struct svc_rqst *rqstp,
584 		struct xdr_stream *xdr_in, void *argp,
585 		struct xdr_stream *xdr_out, void *resp)
586 {
587 	struct callback_op *op = &callback_ops[0];
588 	unsigned int op_nr = OP_CB_ILLEGAL;
589 	__be32 status;
590 	long maxlen;
591 	__be32 res;
592 
593 	dprintk("%s: start\n", __func__);
594 	status = decode_op_hdr(xdr_in, &op_nr);
595 	if (unlikely(status)) {
596 		status = htonl(NFS4ERR_OP_ILLEGAL);
597 		goto out;
598 	}
599 
600 	dprintk("%s: minorversion=%d nop=%d op_nr=%u\n",
601 		__func__, minorversion, nop, op_nr);
602 
603 	status = minorversion ? preprocess_nfs41_op(nop, op_nr, &op) :
604 				preprocess_nfs4_op(op_nr, &op);
605 	if (status == htonl(NFS4ERR_OP_ILLEGAL))
606 		op_nr = OP_CB_ILLEGAL;
607 out:
608 	maxlen = xdr_out->end - xdr_out->p;
609 	if (maxlen > 0 && maxlen < PAGE_SIZE) {
610 		if (likely(status == 0 && op->decode_args != NULL))
611 			status = op->decode_args(rqstp, xdr_in, argp);
612 		if (likely(status == 0 && op->process_op != NULL))
613 			status = op->process_op(argp, resp);
614 	} else
615 		status = htonl(NFS4ERR_RESOURCE);
616 
617 	res = encode_op_hdr(xdr_out, op_nr, status);
618 	if (status == 0)
619 		status = res;
620 	if (op->encode_res != NULL && status == 0)
621 		status = op->encode_res(rqstp, xdr_out, resp);
622 	dprintk("%s: done, status = %d\n", __func__, ntohl(status));
623 	return status;
624 }
625 
626 /*
627  * Decode, process and encode a COMPOUND
628  */
629 static __be32 nfs4_callback_compound(struct svc_rqst *rqstp, void *argp, void *resp)
630 {
631 	struct cb_compound_hdr_arg hdr_arg = { 0 };
632 	struct cb_compound_hdr_res hdr_res = { NULL };
633 	struct xdr_stream xdr_in, xdr_out;
634 	__be32 *p;
635 	__be32 status;
636 	unsigned int nops = 0;
637 
638 	dprintk("%s: start\n", __func__);
639 
640 	xdr_init_decode(&xdr_in, &rqstp->rq_arg, rqstp->rq_arg.head[0].iov_base);
641 
642 	p = (__be32*)((char *)rqstp->rq_res.head[0].iov_base + rqstp->rq_res.head[0].iov_len);
643 	xdr_init_encode(&xdr_out, &rqstp->rq_res, p);
644 
645 	status = decode_compound_hdr_arg(&xdr_in, &hdr_arg);
646 	if (status == __constant_htonl(NFS4ERR_RESOURCE))
647 		return rpc_garbage_args;
648 
649 	hdr_res.taglen = hdr_arg.taglen;
650 	hdr_res.tag = hdr_arg.tag;
651 	if (encode_compound_hdr_res(&xdr_out, &hdr_res) != 0)
652 		return rpc_system_err;
653 
654 	while (status == 0 && nops != hdr_arg.nops) {
655 		status = process_op(hdr_arg.minorversion, nops,
656 				    rqstp, &xdr_in, argp, &xdr_out, resp);
657 		nops++;
658 	}
659 
660 	*hdr_res.status = status;
661 	*hdr_res.nops = htonl(nops);
662 	dprintk("%s: done, status = %u\n", __func__, ntohl(status));
663 	return rpc_success;
664 }
665 
666 /*
667  * Define NFS4 callback COMPOUND ops.
668  */
669 static struct callback_op callback_ops[] = {
670 	[0] = {
671 		.res_maxsize = CB_OP_HDR_RES_MAXSZ,
672 	},
673 	[OP_CB_GETATTR] = {
674 		.process_op = (callback_process_op_t)nfs4_callback_getattr,
675 		.decode_args = (callback_decode_arg_t)decode_getattr_args,
676 		.encode_res = (callback_encode_res_t)encode_getattr_res,
677 		.res_maxsize = CB_OP_GETATTR_RES_MAXSZ,
678 	},
679 	[OP_CB_RECALL] = {
680 		.process_op = (callback_process_op_t)nfs4_callback_recall,
681 		.decode_args = (callback_decode_arg_t)decode_recall_args,
682 		.res_maxsize = CB_OP_RECALL_RES_MAXSZ,
683 	},
684 #if defined(CONFIG_NFS_V4_1)
685 	[OP_CB_SEQUENCE] = {
686 		.process_op = (callback_process_op_t)nfs4_callback_sequence,
687 		.decode_args = (callback_decode_arg_t)decode_cb_sequence_args,
688 		.encode_res = (callback_encode_res_t)encode_cb_sequence_res,
689 		.res_maxsize = CB_OP_SEQUENCE_RES_MAXSZ,
690 	},
691 #endif /* CONFIG_NFS_V4_1 */
692 };
693 
694 /*
695  * Define NFS4 callback procedures
696  */
697 static struct svc_procedure nfs4_callback_procedures1[] = {
698 	[CB_NULL] = {
699 		.pc_func = nfs4_callback_null,
700 		.pc_decode = (kxdrproc_t)nfs4_decode_void,
701 		.pc_encode = (kxdrproc_t)nfs4_encode_void,
702 		.pc_xdrressize = 1,
703 	},
704 	[CB_COMPOUND] = {
705 		.pc_func = nfs4_callback_compound,
706 		.pc_encode = (kxdrproc_t)nfs4_encode_void,
707 		.pc_argsize = 256,
708 		.pc_ressize = 256,
709 		.pc_xdrressize = NFS4_CALLBACK_BUFSIZE,
710 	}
711 };
712 
713 struct svc_version nfs4_callback_version1 = {
714 	.vs_vers = 1,
715 	.vs_nproc = ARRAY_SIZE(nfs4_callback_procedures1),
716 	.vs_proc = nfs4_callback_procedures1,
717 	.vs_xdrsize = NFS4_CALLBACK_XDRSIZE,
718 	.vs_dispatch = NULL,
719 };
720 
721