1/*
2 * linux/net/sunrpc/xdr.c
3 *
4 * Generic XDR support.
5 *
6 * Copyright (C) 1995, 1996 Olaf Kirch <okir@monad.swb.de>
7 */
8
9#include <linux/module.h>
10#include <linux/slab.h>
11#include <linux/types.h>
12#include <linux/string.h>
13#include <linux/kernel.h>
14#include <linux/pagemap.h>
15#include <linux/errno.h>
16#include <linux/sunrpc/xdr.h>
17#include <linux/sunrpc/msg_prot.h>
18
19/*
20 * XDR functions for basic NFS types
21 */
22__be32 *
23xdr_encode_netobj(__be32 *p, const struct xdr_netobj *obj)
24{
25	unsigned int	quadlen = XDR_QUADLEN(obj->len);
26
27	p[quadlen] = 0;		/* zero trailing bytes */
28	*p++ = cpu_to_be32(obj->len);
29	memcpy(p, obj->data, obj->len);
30	return p + XDR_QUADLEN(obj->len);
31}
32EXPORT_SYMBOL_GPL(xdr_encode_netobj);
33
34__be32 *
35xdr_decode_netobj(__be32 *p, struct xdr_netobj *obj)
36{
37	unsigned int	len;
38
39	if ((len = be32_to_cpu(*p++)) > XDR_MAX_NETOBJ)
40		return NULL;
41	obj->len  = len;
42	obj->data = (u8 *) p;
43	return p + XDR_QUADLEN(len);
44}
45EXPORT_SYMBOL_GPL(xdr_decode_netobj);
46
47/**
48 * xdr_encode_opaque_fixed - Encode fixed length opaque data
49 * @p: pointer to current position in XDR buffer.
50 * @ptr: pointer to data to encode (or NULL)
51 * @nbytes: size of data.
52 *
53 * Copy the array of data of length nbytes at ptr to the XDR buffer
54 * at position p, then align to the next 32-bit boundary by padding
55 * with zero bytes (see RFC1832).
56 * Note: if ptr is NULL, only the padding is performed.
57 *
58 * Returns the updated current XDR buffer position
59 *
60 */
61__be32 *xdr_encode_opaque_fixed(__be32 *p, const void *ptr, unsigned int nbytes)
62{
63	if (likely(nbytes != 0)) {
64		unsigned int quadlen = XDR_QUADLEN(nbytes);
65		unsigned int padding = (quadlen << 2) - nbytes;
66
67		if (ptr != NULL)
68			memcpy(p, ptr, nbytes);
69		if (padding != 0)
70			memset((char *)p + nbytes, 0, padding);
71		p += quadlen;
72	}
73	return p;
74}
75EXPORT_SYMBOL_GPL(xdr_encode_opaque_fixed);
76
77/**
78 * xdr_encode_opaque - Encode variable length opaque data
79 * @p: pointer to current position in XDR buffer.
80 * @ptr: pointer to data to encode (or NULL)
81 * @nbytes: size of data.
82 *
83 * Returns the updated current XDR buffer position
84 */
85__be32 *xdr_encode_opaque(__be32 *p, const void *ptr, unsigned int nbytes)
86{
87	*p++ = cpu_to_be32(nbytes);
88	return xdr_encode_opaque_fixed(p, ptr, nbytes);
89}
90EXPORT_SYMBOL_GPL(xdr_encode_opaque);
91
92__be32 *
93xdr_encode_string(__be32 *p, const char *string)
94{
95	return xdr_encode_array(p, string, strlen(string));
96}
97EXPORT_SYMBOL_GPL(xdr_encode_string);
98
99__be32 *
100xdr_decode_string_inplace(__be32 *p, char **sp,
101			  unsigned int *lenp, unsigned int maxlen)
102{
103	u32 len;
104
105	len = be32_to_cpu(*p++);
106	if (len > maxlen)
107		return NULL;
108	*lenp = len;
109	*sp = (char *) p;
110	return p + XDR_QUADLEN(len);
111}
112EXPORT_SYMBOL_GPL(xdr_decode_string_inplace);
113
114/**
115 * xdr_terminate_string - '\0'-terminate a string residing in an xdr_buf
116 * @buf: XDR buffer where string resides
117 * @len: length of string, in bytes
118 *
119 */
120void
121xdr_terminate_string(struct xdr_buf *buf, const u32 len)
122{
123	char *kaddr;
124
125	kaddr = kmap_atomic(buf->pages[0]);
126	kaddr[buf->page_base + len] = '\0';
127	kunmap_atomic(kaddr);
128}
129EXPORT_SYMBOL_GPL(xdr_terminate_string);
130
131void
132xdr_inline_pages(struct xdr_buf *xdr, unsigned int offset,
133		 struct page **pages, unsigned int base, unsigned int len)
134{
135	struct kvec *head = xdr->head;
136	struct kvec *tail = xdr->tail;
137	char *buf = (char *)head->iov_base;
138	unsigned int buflen = head->iov_len;
139
140	head->iov_len  = offset;
141
142	xdr->pages = pages;
143	xdr->page_base = base;
144	xdr->page_len = len;
145
146	tail->iov_base = buf + offset;
147	tail->iov_len = buflen - offset;
148
149	xdr->buflen += len;
150}
151EXPORT_SYMBOL_GPL(xdr_inline_pages);
152
153/*
154 * Helper routines for doing 'memmove' like operations on a struct xdr_buf
155 */
156
157/**
158 * _shift_data_right_pages
159 * @pages: vector of pages containing both the source and dest memory area.
160 * @pgto_base: page vector address of destination
161 * @pgfrom_base: page vector address of source
162 * @len: number of bytes to copy
163 *
164 * Note: the addresses pgto_base and pgfrom_base are both calculated in
165 *       the same way:
166 *            if a memory area starts at byte 'base' in page 'pages[i]',
167 *            then its address is given as (i << PAGE_CACHE_SHIFT) + base
168 * Also note: pgfrom_base must be < pgto_base, but the memory areas
169 * 	they point to may overlap.
170 */
171static void
172_shift_data_right_pages(struct page **pages, size_t pgto_base,
173		size_t pgfrom_base, size_t len)
174{
175	struct page **pgfrom, **pgto;
176	char *vfrom, *vto;
177	size_t copy;
178
179	BUG_ON(pgto_base <= pgfrom_base);
180
181	pgto_base += len;
182	pgfrom_base += len;
183
184	pgto = pages + (pgto_base >> PAGE_CACHE_SHIFT);
185	pgfrom = pages + (pgfrom_base >> PAGE_CACHE_SHIFT);
186
187	pgto_base &= ~PAGE_CACHE_MASK;
188	pgfrom_base &= ~PAGE_CACHE_MASK;
189
190	do {
191		/* Are any pointers crossing a page boundary? */
192		if (pgto_base == 0) {
193			pgto_base = PAGE_CACHE_SIZE;
194			pgto--;
195		}
196		if (pgfrom_base == 0) {
197			pgfrom_base = PAGE_CACHE_SIZE;
198			pgfrom--;
199		}
200
201		copy = len;
202		if (copy > pgto_base)
203			copy = pgto_base;
204		if (copy > pgfrom_base)
205			copy = pgfrom_base;
206		pgto_base -= copy;
207		pgfrom_base -= copy;
208
209		vto = kmap_atomic(*pgto);
210		if (*pgto != *pgfrom) {
211			vfrom = kmap_atomic(*pgfrom);
212			memcpy(vto + pgto_base, vfrom + pgfrom_base, copy);
213			kunmap_atomic(vfrom);
214		} else
215			memmove(vto + pgto_base, vto + pgfrom_base, copy);
216		flush_dcache_page(*pgto);
217		kunmap_atomic(vto);
218
219	} while ((len -= copy) != 0);
220}
221
222/**
223 * _copy_to_pages
224 * @pages: array of pages
225 * @pgbase: page vector address of destination
226 * @p: pointer to source data
227 * @len: length
228 *
229 * Copies data from an arbitrary memory location into an array of pages
230 * The copy is assumed to be non-overlapping.
231 */
232static void
233_copy_to_pages(struct page **pages, size_t pgbase, const char *p, size_t len)
234{
235	struct page **pgto;
236	char *vto;
237	size_t copy;
238
239	pgto = pages + (pgbase >> PAGE_CACHE_SHIFT);
240	pgbase &= ~PAGE_CACHE_MASK;
241
242	for (;;) {
243		copy = PAGE_CACHE_SIZE - pgbase;
244		if (copy > len)
245			copy = len;
246
247		vto = kmap_atomic(*pgto);
248		memcpy(vto + pgbase, p, copy);
249		kunmap_atomic(vto);
250
251		len -= copy;
252		if (len == 0)
253			break;
254
255		pgbase += copy;
256		if (pgbase == PAGE_CACHE_SIZE) {
257			flush_dcache_page(*pgto);
258			pgbase = 0;
259			pgto++;
260		}
261		p += copy;
262	}
263	flush_dcache_page(*pgto);
264}
265
266/**
267 * _copy_from_pages
268 * @p: pointer to destination
269 * @pages: array of pages
270 * @pgbase: offset of source data
271 * @len: length
272 *
273 * Copies data into an arbitrary memory location from an array of pages
274 * The copy is assumed to be non-overlapping.
275 */
276void
277_copy_from_pages(char *p, struct page **pages, size_t pgbase, size_t len)
278{
279	struct page **pgfrom;
280	char *vfrom;
281	size_t copy;
282
283	pgfrom = pages + (pgbase >> PAGE_CACHE_SHIFT);
284	pgbase &= ~PAGE_CACHE_MASK;
285
286	do {
287		copy = PAGE_CACHE_SIZE - pgbase;
288		if (copy > len)
289			copy = len;
290
291		vfrom = kmap_atomic(*pgfrom);
292		memcpy(p, vfrom + pgbase, copy);
293		kunmap_atomic(vfrom);
294
295		pgbase += copy;
296		if (pgbase == PAGE_CACHE_SIZE) {
297			pgbase = 0;
298			pgfrom++;
299		}
300		p += copy;
301
302	} while ((len -= copy) != 0);
303}
304EXPORT_SYMBOL_GPL(_copy_from_pages);
305
306/**
307 * xdr_shrink_bufhead
308 * @buf: xdr_buf
309 * @len: bytes to remove from buf->head[0]
310 *
311 * Shrinks XDR buffer's header kvec buf->head[0] by
312 * 'len' bytes. The extra data is not lost, but is instead
313 * moved into the inlined pages and/or the tail.
314 */
315static void
316xdr_shrink_bufhead(struct xdr_buf *buf, size_t len)
317{
318	struct kvec *head, *tail;
319	size_t copy, offs;
320	unsigned int pglen = buf->page_len;
321
322	tail = buf->tail;
323	head = buf->head;
324
325	WARN_ON_ONCE(len > head->iov_len);
326	if (len > head->iov_len)
327		len = head->iov_len;
328
329	/* Shift the tail first */
330	if (tail->iov_len != 0) {
331		if (tail->iov_len > len) {
332			copy = tail->iov_len - len;
333			memmove((char *)tail->iov_base + len,
334					tail->iov_base, copy);
335		}
336		/* Copy from the inlined pages into the tail */
337		copy = len;
338		if (copy > pglen)
339			copy = pglen;
340		offs = len - copy;
341		if (offs >= tail->iov_len)
342			copy = 0;
343		else if (copy > tail->iov_len - offs)
344			copy = tail->iov_len - offs;
345		if (copy != 0)
346			_copy_from_pages((char *)tail->iov_base + offs,
347					buf->pages,
348					buf->page_base + pglen + offs - len,
349					copy);
350		/* Do we also need to copy data from the head into the tail ? */
351		if (len > pglen) {
352			offs = copy = len - pglen;
353			if (copy > tail->iov_len)
354				copy = tail->iov_len;
355			memcpy(tail->iov_base,
356					(char *)head->iov_base +
357					head->iov_len - offs,
358					copy);
359		}
360	}
361	/* Now handle pages */
362	if (pglen != 0) {
363		if (pglen > len)
364			_shift_data_right_pages(buf->pages,
365					buf->page_base + len,
366					buf->page_base,
367					pglen - len);
368		copy = len;
369		if (len > pglen)
370			copy = pglen;
371		_copy_to_pages(buf->pages, buf->page_base,
372				(char *)head->iov_base + head->iov_len - len,
373				copy);
374	}
375	head->iov_len -= len;
376	buf->buflen -= len;
377	/* Have we truncated the message? */
378	if (buf->len > buf->buflen)
379		buf->len = buf->buflen;
380}
381
382/**
383 * xdr_shrink_pagelen
384 * @buf: xdr_buf
385 * @len: bytes to remove from buf->pages
386 *
387 * Shrinks XDR buffer's page array buf->pages by
388 * 'len' bytes. The extra data is not lost, but is instead
389 * moved into the tail.
390 */
391static void
392xdr_shrink_pagelen(struct xdr_buf *buf, size_t len)
393{
394	struct kvec *tail;
395	size_t copy;
396	unsigned int pglen = buf->page_len;
397	unsigned int tailbuf_len;
398
399	tail = buf->tail;
400	BUG_ON (len > pglen);
401
402	tailbuf_len = buf->buflen - buf->head->iov_len - buf->page_len;
403
404	/* Shift the tail first */
405	if (tailbuf_len != 0) {
406		unsigned int free_space = tailbuf_len - tail->iov_len;
407
408		if (len < free_space)
409			free_space = len;
410		tail->iov_len += free_space;
411
412		copy = len;
413		if (tail->iov_len > len) {
414			char *p = (char *)tail->iov_base + len;
415			memmove(p, tail->iov_base, tail->iov_len - len);
416		} else
417			copy = tail->iov_len;
418		/* Copy from the inlined pages into the tail */
419		_copy_from_pages((char *)tail->iov_base,
420				buf->pages, buf->page_base + pglen - len,
421				copy);
422	}
423	buf->page_len -= len;
424	buf->buflen -= len;
425	/* Have we truncated the message? */
426	if (buf->len > buf->buflen)
427		buf->len = buf->buflen;
428}
429
430void
431xdr_shift_buf(struct xdr_buf *buf, size_t len)
432{
433	xdr_shrink_bufhead(buf, len);
434}
435EXPORT_SYMBOL_GPL(xdr_shift_buf);
436
437/**
438 * xdr_stream_pos - Return the current offset from the start of the xdr_stream
439 * @xdr: pointer to struct xdr_stream
440 */
441unsigned int xdr_stream_pos(const struct xdr_stream *xdr)
442{
443	return (unsigned int)(XDR_QUADLEN(xdr->buf->len) - xdr->nwords) << 2;
444}
445EXPORT_SYMBOL_GPL(xdr_stream_pos);
446
447/**
448 * xdr_init_encode - Initialize a struct xdr_stream for sending data.
449 * @xdr: pointer to xdr_stream struct
450 * @buf: pointer to XDR buffer in which to encode data
451 * @p: current pointer inside XDR buffer
452 *
453 * Note: at the moment the RPC client only passes the length of our
454 *	 scratch buffer in the xdr_buf's header kvec. Previously this
455 *	 meant we needed to call xdr_adjust_iovec() after encoding the
456 *	 data. With the new scheme, the xdr_stream manages the details
457 *	 of the buffer length, and takes care of adjusting the kvec
458 *	 length for us.
459 */
460void xdr_init_encode(struct xdr_stream *xdr, struct xdr_buf *buf, __be32 *p)
461{
462	struct kvec *iov = buf->head;
463	int scratch_len = buf->buflen - buf->page_len - buf->tail[0].iov_len;
464
465	xdr_set_scratch_buffer(xdr, NULL, 0);
466	BUG_ON(scratch_len < 0);
467	xdr->buf = buf;
468	xdr->iov = iov;
469	xdr->p = (__be32 *)((char *)iov->iov_base + iov->iov_len);
470	xdr->end = (__be32 *)((char *)iov->iov_base + scratch_len);
471	BUG_ON(iov->iov_len > scratch_len);
472
473	if (p != xdr->p && p != NULL) {
474		size_t len;
475
476		BUG_ON(p < xdr->p || p > xdr->end);
477		len = (char *)p - (char *)xdr->p;
478		xdr->p = p;
479		buf->len += len;
480		iov->iov_len += len;
481	}
482}
483EXPORT_SYMBOL_GPL(xdr_init_encode);
484
485/**
486 * xdr_commit_encode - Ensure all data is written to buffer
487 * @xdr: pointer to xdr_stream
488 *
489 * We handle encoding across page boundaries by giving the caller a
490 * temporary location to write to, then later copying the data into
491 * place; xdr_commit_encode does that copying.
492 *
493 * Normally the caller doesn't need to call this directly, as the
494 * following xdr_reserve_space will do it.  But an explicit call may be
495 * required at the end of encoding, or any other time when the xdr_buf
496 * data might be read.
497 */
498void xdr_commit_encode(struct xdr_stream *xdr)
499{
500	int shift = xdr->scratch.iov_len;
501	void *page;
502
503	if (shift == 0)
504		return;
505	page = page_address(*xdr->page_ptr);
506	memcpy(xdr->scratch.iov_base, page, shift);
507	memmove(page, page + shift, (void *)xdr->p - page);
508	xdr->scratch.iov_len = 0;
509}
510EXPORT_SYMBOL_GPL(xdr_commit_encode);
511
512static __be32 *xdr_get_next_encode_buffer(struct xdr_stream *xdr,
513		size_t nbytes)
514{
515	static __be32 *p;
516	int space_left;
517	int frag1bytes, frag2bytes;
518
519	if (nbytes > PAGE_SIZE)
520		return NULL; /* Bigger buffers require special handling */
521	if (xdr->buf->len + nbytes > xdr->buf->buflen)
522		return NULL; /* Sorry, we're totally out of space */
523	frag1bytes = (xdr->end - xdr->p) << 2;
524	frag2bytes = nbytes - frag1bytes;
525	if (xdr->iov)
526		xdr->iov->iov_len += frag1bytes;
527	else
528		xdr->buf->page_len += frag1bytes;
529	xdr->page_ptr++;
530	xdr->iov = NULL;
531	/*
532	 * If the last encode didn't end exactly on a page boundary, the
533	 * next one will straddle boundaries.  Encode into the next
534	 * page, then copy it back later in xdr_commit_encode.  We use
535	 * the "scratch" iov to track any temporarily unused fragment of
536	 * space at the end of the previous buffer:
537	 */
538	xdr->scratch.iov_base = xdr->p;
539	xdr->scratch.iov_len = frag1bytes;
540	p = page_address(*xdr->page_ptr);
541	/*
542	 * Note this is where the next encode will start after we've
543	 * shifted this one back:
544	 */
545	xdr->p = (void *)p + frag2bytes;
546	space_left = xdr->buf->buflen - xdr->buf->len;
547	xdr->end = (void *)p + min_t(int, space_left, PAGE_SIZE);
548	xdr->buf->page_len += frag2bytes;
549	xdr->buf->len += nbytes;
550	return p;
551}
552
553/**
554 * xdr_reserve_space - Reserve buffer space for sending
555 * @xdr: pointer to xdr_stream
556 * @nbytes: number of bytes to reserve
557 *
558 * Checks that we have enough buffer space to encode 'nbytes' more
559 * bytes of data. If so, update the total xdr_buf length, and
560 * adjust the length of the current kvec.
561 */
562__be32 * xdr_reserve_space(struct xdr_stream *xdr, size_t nbytes)
563{
564	__be32 *p = xdr->p;
565	__be32 *q;
566
567	xdr_commit_encode(xdr);
568	/* align nbytes on the next 32-bit boundary */
569	nbytes += 3;
570	nbytes &= ~3;
571	q = p + (nbytes >> 2);
572	if (unlikely(q > xdr->end || q < p))
573		return xdr_get_next_encode_buffer(xdr, nbytes);
574	xdr->p = q;
575	if (xdr->iov)
576		xdr->iov->iov_len += nbytes;
577	else
578		xdr->buf->page_len += nbytes;
579	xdr->buf->len += nbytes;
580	return p;
581}
582EXPORT_SYMBOL_GPL(xdr_reserve_space);
583
584/**
585 * xdr_truncate_encode - truncate an encode buffer
586 * @xdr: pointer to xdr_stream
587 * @len: new length of buffer
588 *
589 * Truncates the xdr stream, so that xdr->buf->len == len,
590 * and xdr->p points at offset len from the start of the buffer, and
591 * head, tail, and page lengths are adjusted to correspond.
592 *
593 * If this means moving xdr->p to a different buffer, we assume that
594 * that the end pointer should be set to the end of the current page,
595 * except in the case of the head buffer when we assume the head
596 * buffer's current length represents the end of the available buffer.
597 *
598 * This is *not* safe to use on a buffer that already has inlined page
599 * cache pages (as in a zero-copy server read reply), except for the
600 * simple case of truncating from one position in the tail to another.
601 *
602 */
603void xdr_truncate_encode(struct xdr_stream *xdr, size_t len)
604{
605	struct xdr_buf *buf = xdr->buf;
606	struct kvec *head = buf->head;
607	struct kvec *tail = buf->tail;
608	int fraglen;
609	int new;
610
611	if (len > buf->len) {
612		WARN_ON_ONCE(1);
613		return;
614	}
615	xdr_commit_encode(xdr);
616
617	fraglen = min_t(int, buf->len - len, tail->iov_len);
618	tail->iov_len -= fraglen;
619	buf->len -= fraglen;
620	if (tail->iov_len) {
621		xdr->p = tail->iov_base + tail->iov_len;
622		WARN_ON_ONCE(!xdr->end);
623		WARN_ON_ONCE(!xdr->iov);
624		return;
625	}
626	WARN_ON_ONCE(fraglen);
627	fraglen = min_t(int, buf->len - len, buf->page_len);
628	buf->page_len -= fraglen;
629	buf->len -= fraglen;
630
631	new = buf->page_base + buf->page_len;
632
633	xdr->page_ptr = buf->pages + (new >> PAGE_SHIFT);
634
635	if (buf->page_len) {
636		xdr->p = page_address(*xdr->page_ptr);
637		xdr->end = (void *)xdr->p + PAGE_SIZE;
638		xdr->p = (void *)xdr->p + (new % PAGE_SIZE);
639		WARN_ON_ONCE(xdr->iov);
640		return;
641	}
642	if (fraglen) {
643		xdr->end = head->iov_base + head->iov_len;
644		xdr->page_ptr--;
645	}
646	/* (otherwise assume xdr->end is already set) */
647	head->iov_len = len;
648	buf->len = len;
649	xdr->p = head->iov_base + head->iov_len;
650	xdr->iov = buf->head;
651}
652EXPORT_SYMBOL(xdr_truncate_encode);
653
654/**
655 * xdr_restrict_buflen - decrease available buffer space
656 * @xdr: pointer to xdr_stream
657 * @newbuflen: new maximum number of bytes available
658 *
659 * Adjust our idea of how much space is available in the buffer.
660 * If we've already used too much space in the buffer, returns -1.
661 * If the available space is already smaller than newbuflen, returns 0
662 * and does nothing.  Otherwise, adjusts xdr->buf->buflen to newbuflen
663 * and ensures xdr->end is set at most offset newbuflen from the start
664 * of the buffer.
665 */
666int xdr_restrict_buflen(struct xdr_stream *xdr, int newbuflen)
667{
668	struct xdr_buf *buf = xdr->buf;
669	int left_in_this_buf = (void *)xdr->end - (void *)xdr->p;
670	int end_offset = buf->len + left_in_this_buf;
671
672	if (newbuflen < 0 || newbuflen < buf->len)
673		return -1;
674	if (newbuflen > buf->buflen)
675		return 0;
676	if (newbuflen < end_offset)
677		xdr->end = (void *)xdr->end + newbuflen - end_offset;
678	buf->buflen = newbuflen;
679	return 0;
680}
681EXPORT_SYMBOL(xdr_restrict_buflen);
682
683/**
684 * xdr_write_pages - Insert a list of pages into an XDR buffer for sending
685 * @xdr: pointer to xdr_stream
686 * @pages: list of pages
687 * @base: offset of first byte
688 * @len: length of data in bytes
689 *
690 */
691void xdr_write_pages(struct xdr_stream *xdr, struct page **pages, unsigned int base,
692		 unsigned int len)
693{
694	struct xdr_buf *buf = xdr->buf;
695	struct kvec *iov = buf->tail;
696	buf->pages = pages;
697	buf->page_base = base;
698	buf->page_len = len;
699
700	iov->iov_base = (char *)xdr->p;
701	iov->iov_len  = 0;
702	xdr->iov = iov;
703
704	if (len & 3) {
705		unsigned int pad = 4 - (len & 3);
706
707		BUG_ON(xdr->p >= xdr->end);
708		iov->iov_base = (char *)xdr->p + (len & 3);
709		iov->iov_len  += pad;
710		len += pad;
711		*xdr->p++ = 0;
712	}
713	buf->buflen += len;
714	buf->len += len;
715}
716EXPORT_SYMBOL_GPL(xdr_write_pages);
717
718static void xdr_set_iov(struct xdr_stream *xdr, struct kvec *iov,
719		unsigned int len)
720{
721	if (len > iov->iov_len)
722		len = iov->iov_len;
723	xdr->p = (__be32*)iov->iov_base;
724	xdr->end = (__be32*)(iov->iov_base + len);
725	xdr->iov = iov;
726	xdr->page_ptr = NULL;
727}
728
729static int xdr_set_page_base(struct xdr_stream *xdr,
730		unsigned int base, unsigned int len)
731{
732	unsigned int pgnr;
733	unsigned int maxlen;
734	unsigned int pgoff;
735	unsigned int pgend;
736	void *kaddr;
737
738	maxlen = xdr->buf->page_len;
739	if (base >= maxlen)
740		return -EINVAL;
741	maxlen -= base;
742	if (len > maxlen)
743		len = maxlen;
744
745	base += xdr->buf->page_base;
746
747	pgnr = base >> PAGE_SHIFT;
748	xdr->page_ptr = &xdr->buf->pages[pgnr];
749	kaddr = page_address(*xdr->page_ptr);
750
751	pgoff = base & ~PAGE_MASK;
752	xdr->p = (__be32*)(kaddr + pgoff);
753
754	pgend = pgoff + len;
755	if (pgend > PAGE_SIZE)
756		pgend = PAGE_SIZE;
757	xdr->end = (__be32*)(kaddr + pgend);
758	xdr->iov = NULL;
759	return 0;
760}
761
762static void xdr_set_next_page(struct xdr_stream *xdr)
763{
764	unsigned int newbase;
765
766	newbase = (1 + xdr->page_ptr - xdr->buf->pages) << PAGE_SHIFT;
767	newbase -= xdr->buf->page_base;
768
769	if (xdr_set_page_base(xdr, newbase, PAGE_SIZE) < 0)
770		xdr_set_iov(xdr, xdr->buf->tail, xdr->buf->len);
771}
772
773static bool xdr_set_next_buffer(struct xdr_stream *xdr)
774{
775	if (xdr->page_ptr != NULL)
776		xdr_set_next_page(xdr);
777	else if (xdr->iov == xdr->buf->head) {
778		if (xdr_set_page_base(xdr, 0, PAGE_SIZE) < 0)
779			xdr_set_iov(xdr, xdr->buf->tail, xdr->buf->len);
780	}
781	return xdr->p != xdr->end;
782}
783
784/**
785 * xdr_init_decode - Initialize an xdr_stream for decoding data.
786 * @xdr: pointer to xdr_stream struct
787 * @buf: pointer to XDR buffer from which to decode data
788 * @p: current pointer inside XDR buffer
789 */
790void xdr_init_decode(struct xdr_stream *xdr, struct xdr_buf *buf, __be32 *p)
791{
792	xdr->buf = buf;
793	xdr->scratch.iov_base = NULL;
794	xdr->scratch.iov_len = 0;
795	xdr->nwords = XDR_QUADLEN(buf->len);
796	if (buf->head[0].iov_len != 0)
797		xdr_set_iov(xdr, buf->head, buf->len);
798	else if (buf->page_len != 0)
799		xdr_set_page_base(xdr, 0, buf->len);
800	if (p != NULL && p > xdr->p && xdr->end >= p) {
801		xdr->nwords -= p - xdr->p;
802		xdr->p = p;
803	}
804}
805EXPORT_SYMBOL_GPL(xdr_init_decode);
806
807/**
808 * xdr_init_decode - Initialize an xdr_stream for decoding data.
809 * @xdr: pointer to xdr_stream struct
810 * @buf: pointer to XDR buffer from which to decode data
811 * @pages: list of pages to decode into
812 * @len: length in bytes of buffer in pages
813 */
814void xdr_init_decode_pages(struct xdr_stream *xdr, struct xdr_buf *buf,
815			   struct page **pages, unsigned int len)
816{
817	memset(buf, 0, sizeof(*buf));
818	buf->pages =  pages;
819	buf->page_len =  len;
820	buf->buflen =  len;
821	buf->len = len;
822	xdr_init_decode(xdr, buf, NULL);
823}
824EXPORT_SYMBOL_GPL(xdr_init_decode_pages);
825
826static __be32 * __xdr_inline_decode(struct xdr_stream *xdr, size_t nbytes)
827{
828	unsigned int nwords = XDR_QUADLEN(nbytes);
829	__be32 *p = xdr->p;
830	__be32 *q = p + nwords;
831
832	if (unlikely(nwords > xdr->nwords || q > xdr->end || q < p))
833		return NULL;
834	xdr->p = q;
835	xdr->nwords -= nwords;
836	return p;
837}
838
839/**
840 * xdr_set_scratch_buffer - Attach a scratch buffer for decoding data.
841 * @xdr: pointer to xdr_stream struct
842 * @buf: pointer to an empty buffer
843 * @buflen: size of 'buf'
844 *
845 * The scratch buffer is used when decoding from an array of pages.
846 * If an xdr_inline_decode() call spans across page boundaries, then
847 * we copy the data into the scratch buffer in order to allow linear
848 * access.
849 */
850void xdr_set_scratch_buffer(struct xdr_stream *xdr, void *buf, size_t buflen)
851{
852	xdr->scratch.iov_base = buf;
853	xdr->scratch.iov_len = buflen;
854}
855EXPORT_SYMBOL_GPL(xdr_set_scratch_buffer);
856
857static __be32 *xdr_copy_to_scratch(struct xdr_stream *xdr, size_t nbytes)
858{
859	__be32 *p;
860	void *cpdest = xdr->scratch.iov_base;
861	size_t cplen = (char *)xdr->end - (char *)xdr->p;
862
863	if (nbytes > xdr->scratch.iov_len)
864		return NULL;
865	memcpy(cpdest, xdr->p, cplen);
866	cpdest += cplen;
867	nbytes -= cplen;
868	if (!xdr_set_next_buffer(xdr))
869		return NULL;
870	p = __xdr_inline_decode(xdr, nbytes);
871	if (p == NULL)
872		return NULL;
873	memcpy(cpdest, p, nbytes);
874	return xdr->scratch.iov_base;
875}
876
877/**
878 * xdr_inline_decode - Retrieve XDR data to decode
879 * @xdr: pointer to xdr_stream struct
880 * @nbytes: number of bytes of data to decode
881 *
882 * Check if the input buffer is long enough to enable us to decode
883 * 'nbytes' more bytes of data starting at the current position.
884 * If so return the current pointer, then update the current
885 * pointer position.
886 */
887__be32 * xdr_inline_decode(struct xdr_stream *xdr, size_t nbytes)
888{
889	__be32 *p;
890
891	if (nbytes == 0)
892		return xdr->p;
893	if (xdr->p == xdr->end && !xdr_set_next_buffer(xdr))
894		return NULL;
895	p = __xdr_inline_decode(xdr, nbytes);
896	if (p != NULL)
897		return p;
898	return xdr_copy_to_scratch(xdr, nbytes);
899}
900EXPORT_SYMBOL_GPL(xdr_inline_decode);
901
902static unsigned int xdr_align_pages(struct xdr_stream *xdr, unsigned int len)
903{
904	struct xdr_buf *buf = xdr->buf;
905	struct kvec *iov;
906	unsigned int nwords = XDR_QUADLEN(len);
907	unsigned int cur = xdr_stream_pos(xdr);
908
909	if (xdr->nwords == 0)
910		return 0;
911	/* Realign pages to current pointer position */
912	iov  = buf->head;
913	if (iov->iov_len > cur) {
914		xdr_shrink_bufhead(buf, iov->iov_len - cur);
915		xdr->nwords = XDR_QUADLEN(buf->len - cur);
916	}
917
918	if (nwords > xdr->nwords) {
919		nwords = xdr->nwords;
920		len = nwords << 2;
921	}
922	if (buf->page_len <= len)
923		len = buf->page_len;
924	else if (nwords < xdr->nwords) {
925		/* Truncate page data and move it into the tail */
926		xdr_shrink_pagelen(buf, buf->page_len - len);
927		xdr->nwords = XDR_QUADLEN(buf->len - cur);
928	}
929	return len;
930}
931
932/**
933 * xdr_read_pages - Ensure page-based XDR data to decode is aligned at current pointer position
934 * @xdr: pointer to xdr_stream struct
935 * @len: number of bytes of page data
936 *
937 * Moves data beyond the current pointer position from the XDR head[] buffer
938 * into the page list. Any data that lies beyond current position + "len"
939 * bytes is moved into the XDR tail[].
940 *
941 * Returns the number of XDR encoded bytes now contained in the pages
942 */
943unsigned int xdr_read_pages(struct xdr_stream *xdr, unsigned int len)
944{
945	struct xdr_buf *buf = xdr->buf;
946	struct kvec *iov;
947	unsigned int nwords;
948	unsigned int end;
949	unsigned int padding;
950
951	len = xdr_align_pages(xdr, len);
952	if (len == 0)
953		return 0;
954	nwords = XDR_QUADLEN(len);
955	padding = (nwords << 2) - len;
956	xdr->iov = iov = buf->tail;
957	/* Compute remaining message length.  */
958	end = ((xdr->nwords - nwords) << 2) + padding;
959	if (end > iov->iov_len)
960		end = iov->iov_len;
961
962	/*
963	 * Position current pointer at beginning of tail, and
964	 * set remaining message length.
965	 */
966	xdr->p = (__be32 *)((char *)iov->iov_base + padding);
967	xdr->end = (__be32 *)((char *)iov->iov_base + end);
968	xdr->page_ptr = NULL;
969	xdr->nwords = XDR_QUADLEN(end - padding);
970	return len;
971}
972EXPORT_SYMBOL_GPL(xdr_read_pages);
973
974/**
975 * xdr_enter_page - decode data from the XDR page
976 * @xdr: pointer to xdr_stream struct
977 * @len: number of bytes of page data
978 *
979 * Moves data beyond the current pointer position from the XDR head[] buffer
980 * into the page list. Any data that lies beyond current position + "len"
981 * bytes is moved into the XDR tail[]. The current pointer is then
982 * repositioned at the beginning of the first XDR page.
983 */
984void xdr_enter_page(struct xdr_stream *xdr, unsigned int len)
985{
986	len = xdr_align_pages(xdr, len);
987	/*
988	 * Position current pointer at beginning of tail, and
989	 * set remaining message length.
990	 */
991	if (len != 0)
992		xdr_set_page_base(xdr, 0, len);
993}
994EXPORT_SYMBOL_GPL(xdr_enter_page);
995
996static struct kvec empty_iov = {.iov_base = NULL, .iov_len = 0};
997
998void
999xdr_buf_from_iov(struct kvec *iov, struct xdr_buf *buf)
1000{
1001	buf->head[0] = *iov;
1002	buf->tail[0] = empty_iov;
1003	buf->page_len = 0;
1004	buf->buflen = buf->len = iov->iov_len;
1005}
1006EXPORT_SYMBOL_GPL(xdr_buf_from_iov);
1007
1008/**
1009 * xdr_buf_subsegment - set subbuf to a portion of buf
1010 * @buf: an xdr buffer
1011 * @subbuf: the result buffer
1012 * @base: beginning of range in bytes
1013 * @len: length of range in bytes
1014 *
1015 * sets @subbuf to an xdr buffer representing the portion of @buf of
1016 * length @len starting at offset @base.
1017 *
1018 * @buf and @subbuf may be pointers to the same struct xdr_buf.
1019 *
1020 * Returns -1 if base of length are out of bounds.
1021 */
1022int
1023xdr_buf_subsegment(struct xdr_buf *buf, struct xdr_buf *subbuf,
1024			unsigned int base, unsigned int len)
1025{
1026	subbuf->buflen = subbuf->len = len;
1027	if (base < buf->head[0].iov_len) {
1028		subbuf->head[0].iov_base = buf->head[0].iov_base + base;
1029		subbuf->head[0].iov_len = min_t(unsigned int, len,
1030						buf->head[0].iov_len - base);
1031		len -= subbuf->head[0].iov_len;
1032		base = 0;
1033	} else {
1034		base -= buf->head[0].iov_len;
1035		subbuf->head[0].iov_len = 0;
1036	}
1037
1038	if (base < buf->page_len) {
1039		subbuf->page_len = min(buf->page_len - base, len);
1040		base += buf->page_base;
1041		subbuf->page_base = base & ~PAGE_CACHE_MASK;
1042		subbuf->pages = &buf->pages[base >> PAGE_CACHE_SHIFT];
1043		len -= subbuf->page_len;
1044		base = 0;
1045	} else {
1046		base -= buf->page_len;
1047		subbuf->page_len = 0;
1048	}
1049
1050	if (base < buf->tail[0].iov_len) {
1051		subbuf->tail[0].iov_base = buf->tail[0].iov_base + base;
1052		subbuf->tail[0].iov_len = min_t(unsigned int, len,
1053						buf->tail[0].iov_len - base);
1054		len -= subbuf->tail[0].iov_len;
1055		base = 0;
1056	} else {
1057		base -= buf->tail[0].iov_len;
1058		subbuf->tail[0].iov_len = 0;
1059	}
1060
1061	if (base || len)
1062		return -1;
1063	return 0;
1064}
1065EXPORT_SYMBOL_GPL(xdr_buf_subsegment);
1066
1067/**
1068 * xdr_buf_trim - lop at most "len" bytes off the end of "buf"
1069 * @buf: buf to be trimmed
1070 * @len: number of bytes to reduce "buf" by
1071 *
1072 * Trim an xdr_buf by the given number of bytes by fixing up the lengths. Note
1073 * that it's possible that we'll trim less than that amount if the xdr_buf is
1074 * too small, or if (for instance) it's all in the head and the parser has
1075 * already read too far into it.
1076 */
1077void xdr_buf_trim(struct xdr_buf *buf, unsigned int len)
1078{
1079	size_t cur;
1080	unsigned int trim = len;
1081
1082	if (buf->tail[0].iov_len) {
1083		cur = min_t(size_t, buf->tail[0].iov_len, trim);
1084		buf->tail[0].iov_len -= cur;
1085		trim -= cur;
1086		if (!trim)
1087			goto fix_len;
1088	}
1089
1090	if (buf->page_len) {
1091		cur = min_t(unsigned int, buf->page_len, trim);
1092		buf->page_len -= cur;
1093		trim -= cur;
1094		if (!trim)
1095			goto fix_len;
1096	}
1097
1098	if (buf->head[0].iov_len) {
1099		cur = min_t(size_t, buf->head[0].iov_len, trim);
1100		buf->head[0].iov_len -= cur;
1101		trim -= cur;
1102	}
1103fix_len:
1104	buf->len -= (len - trim);
1105}
1106EXPORT_SYMBOL_GPL(xdr_buf_trim);
1107
1108static void __read_bytes_from_xdr_buf(struct xdr_buf *subbuf, void *obj, unsigned int len)
1109{
1110	unsigned int this_len;
1111
1112	this_len = min_t(unsigned int, len, subbuf->head[0].iov_len);
1113	memcpy(obj, subbuf->head[0].iov_base, this_len);
1114	len -= this_len;
1115	obj += this_len;
1116	this_len = min_t(unsigned int, len, subbuf->page_len);
1117	if (this_len)
1118		_copy_from_pages(obj, subbuf->pages, subbuf->page_base, this_len);
1119	len -= this_len;
1120	obj += this_len;
1121	this_len = min_t(unsigned int, len, subbuf->tail[0].iov_len);
1122	memcpy(obj, subbuf->tail[0].iov_base, this_len);
1123}
1124
1125/* obj is assumed to point to allocated memory of size at least len: */
1126int read_bytes_from_xdr_buf(struct xdr_buf *buf, unsigned int base, void *obj, unsigned int len)
1127{
1128	struct xdr_buf subbuf;
1129	int status;
1130
1131	status = xdr_buf_subsegment(buf, &subbuf, base, len);
1132	if (status != 0)
1133		return status;
1134	__read_bytes_from_xdr_buf(&subbuf, obj, len);
1135	return 0;
1136}
1137EXPORT_SYMBOL_GPL(read_bytes_from_xdr_buf);
1138
1139static void __write_bytes_to_xdr_buf(struct xdr_buf *subbuf, void *obj, unsigned int len)
1140{
1141	unsigned int this_len;
1142
1143	this_len = min_t(unsigned int, len, subbuf->head[0].iov_len);
1144	memcpy(subbuf->head[0].iov_base, obj, this_len);
1145	len -= this_len;
1146	obj += this_len;
1147	this_len = min_t(unsigned int, len, subbuf->page_len);
1148	if (this_len)
1149		_copy_to_pages(subbuf->pages, subbuf->page_base, obj, this_len);
1150	len -= this_len;
1151	obj += this_len;
1152	this_len = min_t(unsigned int, len, subbuf->tail[0].iov_len);
1153	memcpy(subbuf->tail[0].iov_base, obj, this_len);
1154}
1155
1156/* obj is assumed to point to allocated memory of size at least len: */
1157int write_bytes_to_xdr_buf(struct xdr_buf *buf, unsigned int base, void *obj, unsigned int len)
1158{
1159	struct xdr_buf subbuf;
1160	int status;
1161
1162	status = xdr_buf_subsegment(buf, &subbuf, base, len);
1163	if (status != 0)
1164		return status;
1165	__write_bytes_to_xdr_buf(&subbuf, obj, len);
1166	return 0;
1167}
1168EXPORT_SYMBOL_GPL(write_bytes_to_xdr_buf);
1169
1170int
1171xdr_decode_word(struct xdr_buf *buf, unsigned int base, u32 *obj)
1172{
1173	__be32	raw;
1174	int	status;
1175
1176	status = read_bytes_from_xdr_buf(buf, base, &raw, sizeof(*obj));
1177	if (status)
1178		return status;
1179	*obj = be32_to_cpu(raw);
1180	return 0;
1181}
1182EXPORT_SYMBOL_GPL(xdr_decode_word);
1183
1184int
1185xdr_encode_word(struct xdr_buf *buf, unsigned int base, u32 obj)
1186{
1187	__be32	raw = cpu_to_be32(obj);
1188
1189	return write_bytes_to_xdr_buf(buf, base, &raw, sizeof(obj));
1190}
1191EXPORT_SYMBOL_GPL(xdr_encode_word);
1192
1193/* If the netobj starting offset bytes from the start of xdr_buf is contained
1194 * entirely in the head or the tail, set object to point to it; otherwise
1195 * try to find space for it at the end of the tail, copy it there, and
1196 * set obj to point to it. */
1197int xdr_buf_read_netobj(struct xdr_buf *buf, struct xdr_netobj *obj, unsigned int offset)
1198{
1199	struct xdr_buf subbuf;
1200
1201	if (xdr_decode_word(buf, offset, &obj->len))
1202		return -EFAULT;
1203	if (xdr_buf_subsegment(buf, &subbuf, offset + 4, obj->len))
1204		return -EFAULT;
1205
1206	/* Is the obj contained entirely in the head? */
1207	obj->data = subbuf.head[0].iov_base;
1208	if (subbuf.head[0].iov_len == obj->len)
1209		return 0;
1210	/* ..or is the obj contained entirely in the tail? */
1211	obj->data = subbuf.tail[0].iov_base;
1212	if (subbuf.tail[0].iov_len == obj->len)
1213		return 0;
1214
1215	/* use end of tail as storage for obj:
1216	 * (We don't copy to the beginning because then we'd have
1217	 * to worry about doing a potentially overlapping copy.
1218	 * This assumes the object is at most half the length of the
1219	 * tail.) */
1220	if (obj->len > buf->buflen - buf->len)
1221		return -ENOMEM;
1222	if (buf->tail[0].iov_len != 0)
1223		obj->data = buf->tail[0].iov_base + buf->tail[0].iov_len;
1224	else
1225		obj->data = buf->head[0].iov_base + buf->head[0].iov_len;
1226	__read_bytes_from_xdr_buf(&subbuf, obj->data, obj->len);
1227	return 0;
1228}
1229EXPORT_SYMBOL_GPL(xdr_buf_read_netobj);
1230
1231/* Returns 0 on success, or else a negative error code. */
1232static int
1233xdr_xcode_array2(struct xdr_buf *buf, unsigned int base,
1234		 struct xdr_array2_desc *desc, int encode)
1235{
1236	char *elem = NULL, *c;
1237	unsigned int copied = 0, todo, avail_here;
1238	struct page **ppages = NULL;
1239	int err;
1240
1241	if (encode) {
1242		if (xdr_encode_word(buf, base, desc->array_len) != 0)
1243			return -EINVAL;
1244	} else {
1245		if (xdr_decode_word(buf, base, &desc->array_len) != 0 ||
1246		    desc->array_len > desc->array_maxlen ||
1247		    (unsigned long) base + 4 + desc->array_len *
1248				    desc->elem_size > buf->len)
1249			return -EINVAL;
1250	}
1251	base += 4;
1252
1253	if (!desc->xcode)
1254		return 0;
1255
1256	todo = desc->array_len * desc->elem_size;
1257
1258	/* process head */
1259	if (todo && base < buf->head->iov_len) {
1260		c = buf->head->iov_base + base;
1261		avail_here = min_t(unsigned int, todo,
1262				   buf->head->iov_len - base);
1263		todo -= avail_here;
1264
1265		while (avail_here >= desc->elem_size) {
1266			err = desc->xcode(desc, c);
1267			if (err)
1268				goto out;
1269			c += desc->elem_size;
1270			avail_here -= desc->elem_size;
1271		}
1272		if (avail_here) {
1273			if (!elem) {
1274				elem = kmalloc(desc->elem_size, GFP_KERNEL);
1275				err = -ENOMEM;
1276				if (!elem)
1277					goto out;
1278			}
1279			if (encode) {
1280				err = desc->xcode(desc, elem);
1281				if (err)
1282					goto out;
1283				memcpy(c, elem, avail_here);
1284			} else
1285				memcpy(elem, c, avail_here);
1286			copied = avail_here;
1287		}
1288		base = buf->head->iov_len;  /* align to start of pages */
1289	}
1290
1291	/* process pages array */
1292	base -= buf->head->iov_len;
1293	if (todo && base < buf->page_len) {
1294		unsigned int avail_page;
1295
1296		avail_here = min(todo, buf->page_len - base);
1297		todo -= avail_here;
1298
1299		base += buf->page_base;
1300		ppages = buf->pages + (base >> PAGE_CACHE_SHIFT);
1301		base &= ~PAGE_CACHE_MASK;
1302		avail_page = min_t(unsigned int, PAGE_CACHE_SIZE - base,
1303					avail_here);
1304		c = kmap(*ppages) + base;
1305
1306		while (avail_here) {
1307			avail_here -= avail_page;
1308			if (copied || avail_page < desc->elem_size) {
1309				unsigned int l = min(avail_page,
1310					desc->elem_size - copied);
1311				if (!elem) {
1312					elem = kmalloc(desc->elem_size,
1313						       GFP_KERNEL);
1314					err = -ENOMEM;
1315					if (!elem)
1316						goto out;
1317				}
1318				if (encode) {
1319					if (!copied) {
1320						err = desc->xcode(desc, elem);
1321						if (err)
1322							goto out;
1323					}
1324					memcpy(c, elem + copied, l);
1325					copied += l;
1326					if (copied == desc->elem_size)
1327						copied = 0;
1328				} else {
1329					memcpy(elem + copied, c, l);
1330					copied += l;
1331					if (copied == desc->elem_size) {
1332						err = desc->xcode(desc, elem);
1333						if (err)
1334							goto out;
1335						copied = 0;
1336					}
1337				}
1338				avail_page -= l;
1339				c += l;
1340			}
1341			while (avail_page >= desc->elem_size) {
1342				err = desc->xcode(desc, c);
1343				if (err)
1344					goto out;
1345				c += desc->elem_size;
1346				avail_page -= desc->elem_size;
1347			}
1348			if (avail_page) {
1349				unsigned int l = min(avail_page,
1350					    desc->elem_size - copied);
1351				if (!elem) {
1352					elem = kmalloc(desc->elem_size,
1353						       GFP_KERNEL);
1354					err = -ENOMEM;
1355					if (!elem)
1356						goto out;
1357				}
1358				if (encode) {
1359					if (!copied) {
1360						err = desc->xcode(desc, elem);
1361						if (err)
1362							goto out;
1363					}
1364					memcpy(c, elem + copied, l);
1365					copied += l;
1366					if (copied == desc->elem_size)
1367						copied = 0;
1368				} else {
1369					memcpy(elem + copied, c, l);
1370					copied += l;
1371					if (copied == desc->elem_size) {
1372						err = desc->xcode(desc, elem);
1373						if (err)
1374							goto out;
1375						copied = 0;
1376					}
1377				}
1378			}
1379			if (avail_here) {
1380				kunmap(*ppages);
1381				ppages++;
1382				c = kmap(*ppages);
1383			}
1384
1385			avail_page = min(avail_here,
1386				 (unsigned int) PAGE_CACHE_SIZE);
1387		}
1388		base = buf->page_len;  /* align to start of tail */
1389	}
1390
1391	/* process tail */
1392	base -= buf->page_len;
1393	if (todo) {
1394		c = buf->tail->iov_base + base;
1395		if (copied) {
1396			unsigned int l = desc->elem_size - copied;
1397
1398			if (encode)
1399				memcpy(c, elem + copied, l);
1400			else {
1401				memcpy(elem + copied, c, l);
1402				err = desc->xcode(desc, elem);
1403				if (err)
1404					goto out;
1405			}
1406			todo -= l;
1407			c += l;
1408		}
1409		while (todo) {
1410			err = desc->xcode(desc, c);
1411			if (err)
1412				goto out;
1413			c += desc->elem_size;
1414			todo -= desc->elem_size;
1415		}
1416	}
1417	err = 0;
1418
1419out:
1420	kfree(elem);
1421	if (ppages)
1422		kunmap(*ppages);
1423	return err;
1424}
1425
1426int
1427xdr_decode_array2(struct xdr_buf *buf, unsigned int base,
1428		  struct xdr_array2_desc *desc)
1429{
1430	if (base >= buf->len)
1431		return -EINVAL;
1432
1433	return xdr_xcode_array2(buf, base, desc, 0);
1434}
1435EXPORT_SYMBOL_GPL(xdr_decode_array2);
1436
1437int
1438xdr_encode_array2(struct xdr_buf *buf, unsigned int base,
1439		  struct xdr_array2_desc *desc)
1440{
1441	if ((unsigned long) base + 4 + desc->array_len * desc->elem_size >
1442	    buf->head->iov_len + buf->page_len + buf->tail->iov_len)
1443		return -EINVAL;
1444
1445	return xdr_xcode_array2(buf, base, desc, 1);
1446}
1447EXPORT_SYMBOL_GPL(xdr_encode_array2);
1448
1449int
1450xdr_process_buf(struct xdr_buf *buf, unsigned int offset, unsigned int len,
1451		int (*actor)(struct scatterlist *, void *), void *data)
1452{
1453	int i, ret = 0;
1454	unsigned int page_len, thislen, page_offset;
1455	struct scatterlist      sg[1];
1456
1457	sg_init_table(sg, 1);
1458
1459	if (offset >= buf->head[0].iov_len) {
1460		offset -= buf->head[0].iov_len;
1461	} else {
1462		thislen = buf->head[0].iov_len - offset;
1463		if (thislen > len)
1464			thislen = len;
1465		sg_set_buf(sg, buf->head[0].iov_base + offset, thislen);
1466		ret = actor(sg, data);
1467		if (ret)
1468			goto out;
1469		offset = 0;
1470		len -= thislen;
1471	}
1472	if (len == 0)
1473		goto out;
1474
1475	if (offset >= buf->page_len) {
1476		offset -= buf->page_len;
1477	} else {
1478		page_len = buf->page_len - offset;
1479		if (page_len > len)
1480			page_len = len;
1481		len -= page_len;
1482		page_offset = (offset + buf->page_base) & (PAGE_CACHE_SIZE - 1);
1483		i = (offset + buf->page_base) >> PAGE_CACHE_SHIFT;
1484		thislen = PAGE_CACHE_SIZE - page_offset;
1485		do {
1486			if (thislen > page_len)
1487				thislen = page_len;
1488			sg_set_page(sg, buf->pages[i], thislen, page_offset);
1489			ret = actor(sg, data);
1490			if (ret)
1491				goto out;
1492			page_len -= thislen;
1493			i++;
1494			page_offset = 0;
1495			thislen = PAGE_CACHE_SIZE;
1496		} while (page_len != 0);
1497		offset = 0;
1498	}
1499	if (len == 0)
1500		goto out;
1501	if (offset < buf->tail[0].iov_len) {
1502		thislen = buf->tail[0].iov_len - offset;
1503		if (thislen > len)
1504			thislen = len;
1505		sg_set_buf(sg, buf->tail[0].iov_base + offset, thislen);
1506		ret = actor(sg, data);
1507		len -= thislen;
1508	}
1509	if (len != 0)
1510		ret = -EINVAL;
1511out:
1512	return ret;
1513}
1514EXPORT_SYMBOL_GPL(xdr_process_buf);
1515
1516