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_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_SHIFT);
 185	pgfrom = pages + (pgfrom_base >> PAGE_SHIFT);
 186
 187	pgto_base &= ~PAGE_MASK;
 188	pgfrom_base &= ~PAGE_MASK;
 189
 190	do {
 191		/* Are any pointers crossing a page boundary? */
 192		if (pgto_base == 0) {
 193			pgto_base = PAGE_SIZE;
 194			pgto--;
 195		}
 196		if (pgfrom_base == 0) {
 197			pgfrom_base = PAGE_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_SHIFT);
 240	pgbase &= ~PAGE_MASK;
 241
 242	for (;;) {
 243		copy = PAGE_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_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_SHIFT);
 284	pgbase &= ~PAGE_MASK;
 285
 286	do {
 287		copy = PAGE_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_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->nwords << 2);
 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->nwords << 2);
 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	else
 801		xdr_set_iov(xdr, buf->head, buf->len);
 802	if (p != NULL && p > xdr->p && xdr->end >= p) {
 803		xdr->nwords -= p - xdr->p;
 804		xdr->p = p;
 805	}
 
 806}
 807EXPORT_SYMBOL_GPL(xdr_init_decode);
 808
 809/**
 810 * xdr_init_decode_pages - Initialize an xdr_stream for decoding into pages
 811 * @xdr: pointer to xdr_stream struct
 812 * @buf: pointer to XDR buffer from which to decode data
 813 * @pages: list of pages to decode into
 814 * @len: length in bytes of buffer in pages
 815 */
 816void xdr_init_decode_pages(struct xdr_stream *xdr, struct xdr_buf *buf,
 817			   struct page **pages, unsigned int len)
 818{
 819	memset(buf, 0, sizeof(*buf));
 820	buf->pages =  pages;
 821	buf->page_len =  len;
 822	buf->buflen =  len;
 823	buf->len = len;
 824	xdr_init_decode(xdr, buf, NULL);
 825}
 826EXPORT_SYMBOL_GPL(xdr_init_decode_pages);
 827
 828static __be32 * __xdr_inline_decode(struct xdr_stream *xdr, size_t nbytes)
 829{
 830	unsigned int nwords = XDR_QUADLEN(nbytes);
 831	__be32 *p = xdr->p;
 832	__be32 *q = p + nwords;
 833
 834	if (unlikely(nwords > xdr->nwords || q > xdr->end || q < p))
 835		return NULL;
 836	xdr->p = q;
 837	xdr->nwords -= nwords;
 838	return p;
 839}
 840
 841/**
 842 * xdr_set_scratch_buffer - Attach a scratch buffer for decoding data.
 843 * @xdr: pointer to xdr_stream struct
 844 * @buf: pointer to an empty buffer
 845 * @buflen: size of 'buf'
 846 *
 847 * The scratch buffer is used when decoding from an array of pages.
 848 * If an xdr_inline_decode() call spans across page boundaries, then
 849 * we copy the data into the scratch buffer in order to allow linear
 850 * access.
 851 */
 852void xdr_set_scratch_buffer(struct xdr_stream *xdr, void *buf, size_t buflen)
 853{
 854	xdr->scratch.iov_base = buf;
 855	xdr->scratch.iov_len = buflen;
 856}
 857EXPORT_SYMBOL_GPL(xdr_set_scratch_buffer);
 858
 859static __be32 *xdr_copy_to_scratch(struct xdr_stream *xdr, size_t nbytes)
 860{
 861	__be32 *p;
 862	char *cpdest = xdr->scratch.iov_base;
 863	size_t cplen = (char *)xdr->end - (char *)xdr->p;
 864
 865	if (nbytes > xdr->scratch.iov_len)
 866		return NULL;
 867	p = __xdr_inline_decode(xdr, cplen);
 868	if (p == NULL)
 869		return NULL;
 870	memcpy(cpdest, p, cplen);
 
 
 871	cpdest += cplen;
 872	nbytes -= cplen;
 873	if (!xdr_set_next_buffer(xdr))
 874		return NULL;
 875	p = __xdr_inline_decode(xdr, nbytes);
 876	if (p == NULL)
 877		return NULL;
 878	memcpy(cpdest, p, nbytes);
 879	return xdr->scratch.iov_base;
 
 
 
 880}
 881
 882/**
 883 * xdr_inline_decode - Retrieve XDR data to decode
 884 * @xdr: pointer to xdr_stream struct
 885 * @nbytes: number of bytes of data to decode
 886 *
 887 * Check if the input buffer is long enough to enable us to decode
 888 * 'nbytes' more bytes of data starting at the current position.
 889 * If so return the current pointer, then update the current
 890 * pointer position.
 891 */
 892__be32 * xdr_inline_decode(struct xdr_stream *xdr, size_t nbytes)
 893{
 894	__be32 *p;
 895
 896	if (nbytes == 0)
 897		return xdr->p;
 898	if (xdr->p == xdr->end && !xdr_set_next_buffer(xdr))
 899		return NULL;
 900	p = __xdr_inline_decode(xdr, nbytes);
 901	if (p != NULL)
 902		return p;
 903	return xdr_copy_to_scratch(xdr, nbytes);
 
 
 
 904}
 905EXPORT_SYMBOL_GPL(xdr_inline_decode);
 906
 907static unsigned int xdr_align_pages(struct xdr_stream *xdr, unsigned int len)
 908{
 909	struct xdr_buf *buf = xdr->buf;
 910	struct kvec *iov;
 911	unsigned int nwords = XDR_QUADLEN(len);
 912	unsigned int cur = xdr_stream_pos(xdr);
 
 913
 914	if (xdr->nwords == 0)
 915		return 0;
 
 916	/* Realign pages to current pointer position */
 917	iov  = buf->head;
 918	if (iov->iov_len > cur) {
 919		xdr_shrink_bufhead(buf, iov->iov_len - cur);
 
 
 920		xdr->nwords = XDR_QUADLEN(buf->len - cur);
 921	}
 922
 923	if (nwords > xdr->nwords) {
 924		nwords = xdr->nwords;
 925		len = nwords << 2;
 926	}
 927	if (buf->page_len <= len)
 928		len = buf->page_len;
 929	else if (nwords < xdr->nwords) {
 930		/* Truncate page data and move it into the tail */
 931		xdr_shrink_pagelen(buf, buf->page_len - len);
 
 
 932		xdr->nwords = XDR_QUADLEN(buf->len - cur);
 933	}
 934	return len;
 935}
 936
 937/**
 938 * xdr_read_pages - Ensure page-based XDR data to decode is aligned at current pointer position
 939 * @xdr: pointer to xdr_stream struct
 940 * @len: number of bytes of page data
 941 *
 942 * Moves data beyond the current pointer position from the XDR head[] buffer
 943 * into the page list. Any data that lies beyond current position + "len"
 944 * bytes is moved into the XDR tail[].
 945 *
 946 * Returns the number of XDR encoded bytes now contained in the pages
 947 */
 948unsigned int xdr_read_pages(struct xdr_stream *xdr, unsigned int len)
 949{
 950	struct xdr_buf *buf = xdr->buf;
 951	struct kvec *iov;
 952	unsigned int nwords;
 953	unsigned int end;
 954	unsigned int padding;
 955
 956	len = xdr_align_pages(xdr, len);
 957	if (len == 0)
 958		return 0;
 959	nwords = XDR_QUADLEN(len);
 960	padding = (nwords << 2) - len;
 961	xdr->iov = iov = buf->tail;
 962	/* Compute remaining message length.  */
 963	end = ((xdr->nwords - nwords) << 2) + padding;
 964	if (end > iov->iov_len)
 965		end = iov->iov_len;
 966
 967	/*
 968	 * Position current pointer at beginning of tail, and
 969	 * set remaining message length.
 970	 */
 971	xdr->p = (__be32 *)((char *)iov->iov_base + padding);
 972	xdr->end = (__be32 *)((char *)iov->iov_base + end);
 973	xdr->page_ptr = NULL;
 974	xdr->nwords = XDR_QUADLEN(end - padding);
 975	return len;
 976}
 977EXPORT_SYMBOL_GPL(xdr_read_pages);
 978
 979/**
 980 * xdr_enter_page - decode data from the XDR page
 981 * @xdr: pointer to xdr_stream struct
 982 * @len: number of bytes of page data
 983 *
 984 * Moves data beyond the current pointer position from the XDR head[] buffer
 985 * into the page list. Any data that lies beyond current position + "len"
 986 * bytes is moved into the XDR tail[]. The current pointer is then
 987 * repositioned at the beginning of the first XDR page.
 988 */
 989void xdr_enter_page(struct xdr_stream *xdr, unsigned int len)
 990{
 991	len = xdr_align_pages(xdr, len);
 992	/*
 993	 * Position current pointer at beginning of tail, and
 994	 * set remaining message length.
 995	 */
 996	if (len != 0)
 997		xdr_set_page_base(xdr, 0, len);
 998}
 999EXPORT_SYMBOL_GPL(xdr_enter_page);
1000
1001static struct kvec empty_iov = {.iov_base = NULL, .iov_len = 0};
1002
1003void
1004xdr_buf_from_iov(struct kvec *iov, struct xdr_buf *buf)
1005{
1006	buf->head[0] = *iov;
1007	buf->tail[0] = empty_iov;
1008	buf->page_len = 0;
1009	buf->buflen = buf->len = iov->iov_len;
1010}
1011EXPORT_SYMBOL_GPL(xdr_buf_from_iov);
1012
1013/**
1014 * xdr_buf_subsegment - set subbuf to a portion of buf
1015 * @buf: an xdr buffer
1016 * @subbuf: the result buffer
1017 * @base: beginning of range in bytes
1018 * @len: length of range in bytes
1019 *
1020 * sets @subbuf to an xdr buffer representing the portion of @buf of
1021 * length @len starting at offset @base.
1022 *
1023 * @buf and @subbuf may be pointers to the same struct xdr_buf.
1024 *
1025 * Returns -1 if base of length are out of bounds.
1026 */
1027int
1028xdr_buf_subsegment(struct xdr_buf *buf, struct xdr_buf *subbuf,
1029			unsigned int base, unsigned int len)
1030{
1031	subbuf->buflen = subbuf->len = len;
1032	if (base < buf->head[0].iov_len) {
1033		subbuf->head[0].iov_base = buf->head[0].iov_base + base;
1034		subbuf->head[0].iov_len = min_t(unsigned int, len,
1035						buf->head[0].iov_len - base);
1036		len -= subbuf->head[0].iov_len;
1037		base = 0;
1038	} else {
1039		base -= buf->head[0].iov_len;
 
1040		subbuf->head[0].iov_len = 0;
1041	}
1042
1043	if (base < buf->page_len) {
1044		subbuf->page_len = min(buf->page_len - base, len);
1045		base += buf->page_base;
1046		subbuf->page_base = base & ~PAGE_MASK;
1047		subbuf->pages = &buf->pages[base >> PAGE_SHIFT];
1048		len -= subbuf->page_len;
1049		base = 0;
1050	} else {
1051		base -= buf->page_len;
 
 
1052		subbuf->page_len = 0;
1053	}
1054
1055	if (base < buf->tail[0].iov_len) {
1056		subbuf->tail[0].iov_base = buf->tail[0].iov_base + base;
1057		subbuf->tail[0].iov_len = min_t(unsigned int, len,
1058						buf->tail[0].iov_len - base);
1059		len -= subbuf->tail[0].iov_len;
1060		base = 0;
1061	} else {
1062		base -= buf->tail[0].iov_len;
 
1063		subbuf->tail[0].iov_len = 0;
1064	}
1065
1066	if (base || len)
1067		return -1;
1068	return 0;
1069}
1070EXPORT_SYMBOL_GPL(xdr_buf_subsegment);
1071
1072/**
1073 * xdr_buf_trim - lop at most "len" bytes off the end of "buf"
1074 * @buf: buf to be trimmed
1075 * @len: number of bytes to reduce "buf" by
1076 *
1077 * Trim an xdr_buf by the given number of bytes by fixing up the lengths. Note
1078 * that it's possible that we'll trim less than that amount if the xdr_buf is
1079 * too small, or if (for instance) it's all in the head and the parser has
1080 * already read too far into it.
1081 */
1082void xdr_buf_trim(struct xdr_buf *buf, unsigned int len)
1083{
1084	size_t cur;
1085	unsigned int trim = len;
1086
1087	if (buf->tail[0].iov_len) {
1088		cur = min_t(size_t, buf->tail[0].iov_len, trim);
1089		buf->tail[0].iov_len -= cur;
1090		trim -= cur;
1091		if (!trim)
1092			goto fix_len;
1093	}
1094
1095	if (buf->page_len) {
1096		cur = min_t(unsigned int, buf->page_len, trim);
1097		buf->page_len -= cur;
1098		trim -= cur;
1099		if (!trim)
1100			goto fix_len;
1101	}
1102
1103	if (buf->head[0].iov_len) {
1104		cur = min_t(size_t, buf->head[0].iov_len, trim);
1105		buf->head[0].iov_len -= cur;
1106		trim -= cur;
1107	}
1108fix_len:
1109	buf->len -= (len - trim);
1110}
1111EXPORT_SYMBOL_GPL(xdr_buf_trim);
1112
1113static void __read_bytes_from_xdr_buf(struct xdr_buf *subbuf, void *obj, unsigned int len)
1114{
1115	unsigned int this_len;
1116
1117	this_len = min_t(unsigned int, len, subbuf->head[0].iov_len);
1118	memcpy(obj, subbuf->head[0].iov_base, this_len);
1119	len -= this_len;
1120	obj += this_len;
1121	this_len = min_t(unsigned int, len, subbuf->page_len);
1122	if (this_len)
1123		_copy_from_pages(obj, subbuf->pages, subbuf->page_base, this_len);
1124	len -= this_len;
1125	obj += this_len;
1126	this_len = min_t(unsigned int, len, subbuf->tail[0].iov_len);
1127	memcpy(obj, subbuf->tail[0].iov_base, this_len);
1128}
1129
1130/* obj is assumed to point to allocated memory of size at least len: */
1131int read_bytes_from_xdr_buf(struct xdr_buf *buf, unsigned int base, void *obj, unsigned int len)
1132{
1133	struct xdr_buf subbuf;
1134	int status;
1135
1136	status = xdr_buf_subsegment(buf, &subbuf, base, len);
1137	if (status != 0)
1138		return status;
1139	__read_bytes_from_xdr_buf(&subbuf, obj, len);
1140	return 0;
1141}
1142EXPORT_SYMBOL_GPL(read_bytes_from_xdr_buf);
1143
1144static void __write_bytes_to_xdr_buf(struct xdr_buf *subbuf, void *obj, unsigned int len)
1145{
1146	unsigned int this_len;
1147
1148	this_len = min_t(unsigned int, len, subbuf->head[0].iov_len);
1149	memcpy(subbuf->head[0].iov_base, obj, this_len);
1150	len -= this_len;
1151	obj += this_len;
1152	this_len = min_t(unsigned int, len, subbuf->page_len);
1153	if (this_len)
1154		_copy_to_pages(subbuf->pages, subbuf->page_base, obj, this_len);
1155	len -= this_len;
1156	obj += this_len;
1157	this_len = min_t(unsigned int, len, subbuf->tail[0].iov_len);
1158	memcpy(subbuf->tail[0].iov_base, obj, this_len);
1159}
1160
1161/* obj is assumed to point to allocated memory of size at least len: */
1162int write_bytes_to_xdr_buf(struct xdr_buf *buf, unsigned int base, void *obj, unsigned int len)
1163{
1164	struct xdr_buf subbuf;
1165	int status;
1166
1167	status = xdr_buf_subsegment(buf, &subbuf, base, len);
1168	if (status != 0)
1169		return status;
1170	__write_bytes_to_xdr_buf(&subbuf, obj, len);
1171	return 0;
1172}
1173EXPORT_SYMBOL_GPL(write_bytes_to_xdr_buf);
1174
1175int
1176xdr_decode_word(struct xdr_buf *buf, unsigned int base, u32 *obj)
1177{
1178	__be32	raw;
1179	int	status;
1180
1181	status = read_bytes_from_xdr_buf(buf, base, &raw, sizeof(*obj));
1182	if (status)
1183		return status;
1184	*obj = be32_to_cpu(raw);
1185	return 0;
1186}
1187EXPORT_SYMBOL_GPL(xdr_decode_word);
1188
1189int
1190xdr_encode_word(struct xdr_buf *buf, unsigned int base, u32 obj)
1191{
1192	__be32	raw = cpu_to_be32(obj);
1193
1194	return write_bytes_to_xdr_buf(buf, base, &raw, sizeof(obj));
1195}
1196EXPORT_SYMBOL_GPL(xdr_encode_word);
1197
1198/* If the netobj starting offset bytes from the start of xdr_buf is contained
1199 * entirely in the head or the tail, set object to point to it; otherwise
1200 * try to find space for it at the end of the tail, copy it there, and
1201 * set obj to point to it. */
1202int xdr_buf_read_netobj(struct xdr_buf *buf, struct xdr_netobj *obj, unsigned int offset)
1203{
1204	struct xdr_buf subbuf;
1205
1206	if (xdr_decode_word(buf, offset, &obj->len))
1207		return -EFAULT;
1208	if (xdr_buf_subsegment(buf, &subbuf, offset + 4, obj->len))
1209		return -EFAULT;
1210
1211	/* Is the obj contained entirely in the head? */
1212	obj->data = subbuf.head[0].iov_base;
1213	if (subbuf.head[0].iov_len == obj->len)
1214		return 0;
1215	/* ..or is the obj contained entirely in the tail? */
1216	obj->data = subbuf.tail[0].iov_base;
1217	if (subbuf.tail[0].iov_len == obj->len)
1218		return 0;
1219
1220	/* use end of tail as storage for obj:
1221	 * (We don't copy to the beginning because then we'd have
1222	 * to worry about doing a potentially overlapping copy.
1223	 * This assumes the object is at most half the length of the
1224	 * tail.) */
1225	if (obj->len > buf->buflen - buf->len)
1226		return -ENOMEM;
1227	if (buf->tail[0].iov_len != 0)
1228		obj->data = buf->tail[0].iov_base + buf->tail[0].iov_len;
1229	else
1230		obj->data = buf->head[0].iov_base + buf->head[0].iov_len;
1231	__read_bytes_from_xdr_buf(&subbuf, obj->data, obj->len);
1232	return 0;
1233}
1234EXPORT_SYMBOL_GPL(xdr_buf_read_netobj);
1235
1236/* Returns 0 on success, or else a negative error code. */
1237static int
1238xdr_xcode_array2(struct xdr_buf *buf, unsigned int base,
1239		 struct xdr_array2_desc *desc, int encode)
1240{
1241	char *elem = NULL, *c;
1242	unsigned int copied = 0, todo, avail_here;
1243	struct page **ppages = NULL;
1244	int err;
1245
1246	if (encode) {
1247		if (xdr_encode_word(buf, base, desc->array_len) != 0)
1248			return -EINVAL;
1249	} else {
1250		if (xdr_decode_word(buf, base, &desc->array_len) != 0 ||
1251		    desc->array_len > desc->array_maxlen ||
1252		    (unsigned long) base + 4 + desc->array_len *
1253				    desc->elem_size > buf->len)
1254			return -EINVAL;
1255	}
1256	base += 4;
1257
1258	if (!desc->xcode)
1259		return 0;
1260
1261	todo = desc->array_len * desc->elem_size;
1262
1263	/* process head */
1264	if (todo && base < buf->head->iov_len) {
1265		c = buf->head->iov_base + base;
1266		avail_here = min_t(unsigned int, todo,
1267				   buf->head->iov_len - base);
1268		todo -= avail_here;
1269
1270		while (avail_here >= desc->elem_size) {
1271			err = desc->xcode(desc, c);
1272			if (err)
1273				goto out;
1274			c += desc->elem_size;
1275			avail_here -= desc->elem_size;
1276		}
1277		if (avail_here) {
1278			if (!elem) {
1279				elem = kmalloc(desc->elem_size, GFP_KERNEL);
1280				err = -ENOMEM;
1281				if (!elem)
1282					goto out;
1283			}
1284			if (encode) {
1285				err = desc->xcode(desc, elem);
1286				if (err)
1287					goto out;
1288				memcpy(c, elem, avail_here);
1289			} else
1290				memcpy(elem, c, avail_here);
1291			copied = avail_here;
1292		}
1293		base = buf->head->iov_len;  /* align to start of pages */
1294	}
1295
1296	/* process pages array */
1297	base -= buf->head->iov_len;
1298	if (todo && base < buf->page_len) {
1299		unsigned int avail_page;
1300
1301		avail_here = min(todo, buf->page_len - base);
1302		todo -= avail_here;
1303
1304		base += buf->page_base;
1305		ppages = buf->pages + (base >> PAGE_SHIFT);
1306		base &= ~PAGE_MASK;
1307		avail_page = min_t(unsigned int, PAGE_SIZE - base,
1308					avail_here);
1309		c = kmap(*ppages) + base;
1310
1311		while (avail_here) {
1312			avail_here -= avail_page;
1313			if (copied || avail_page < desc->elem_size) {
1314				unsigned int l = min(avail_page,
1315					desc->elem_size - copied);
1316				if (!elem) {
1317					elem = kmalloc(desc->elem_size,
1318						       GFP_KERNEL);
1319					err = -ENOMEM;
1320					if (!elem)
1321						goto out;
1322				}
1323				if (encode) {
1324					if (!copied) {
1325						err = desc->xcode(desc, elem);
1326						if (err)
1327							goto out;
1328					}
1329					memcpy(c, elem + copied, l);
1330					copied += l;
1331					if (copied == desc->elem_size)
1332						copied = 0;
1333				} else {
1334					memcpy(elem + copied, c, l);
1335					copied += l;
1336					if (copied == desc->elem_size) {
1337						err = desc->xcode(desc, elem);
1338						if (err)
1339							goto out;
1340						copied = 0;
1341					}
1342				}
1343				avail_page -= l;
1344				c += l;
1345			}
1346			while (avail_page >= desc->elem_size) {
1347				err = desc->xcode(desc, c);
1348				if (err)
1349					goto out;
1350				c += desc->elem_size;
1351				avail_page -= desc->elem_size;
1352			}
1353			if (avail_page) {
1354				unsigned int l = min(avail_page,
1355					    desc->elem_size - copied);
1356				if (!elem) {
1357					elem = kmalloc(desc->elem_size,
1358						       GFP_KERNEL);
1359					err = -ENOMEM;
1360					if (!elem)
1361						goto out;
1362				}
1363				if (encode) {
1364					if (!copied) {
1365						err = desc->xcode(desc, elem);
1366						if (err)
1367							goto out;
1368					}
1369					memcpy(c, elem + copied, l);
1370					copied += l;
1371					if (copied == desc->elem_size)
1372						copied = 0;
1373				} else {
1374					memcpy(elem + copied, c, l);
1375					copied += l;
1376					if (copied == desc->elem_size) {
1377						err = desc->xcode(desc, elem);
1378						if (err)
1379							goto out;
1380						copied = 0;
1381					}
1382				}
1383			}
1384			if (avail_here) {
1385				kunmap(*ppages);
1386				ppages++;
1387				c = kmap(*ppages);
1388			}
1389
1390			avail_page = min(avail_here,
1391				 (unsigned int) PAGE_SIZE);
1392		}
1393		base = buf->page_len;  /* align to start of tail */
1394	}
1395
1396	/* process tail */
1397	base -= buf->page_len;
1398	if (todo) {
1399		c = buf->tail->iov_base + base;
1400		if (copied) {
1401			unsigned int l = desc->elem_size - copied;
1402
1403			if (encode)
1404				memcpy(c, elem + copied, l);
1405			else {
1406				memcpy(elem + copied, c, l);
1407				err = desc->xcode(desc, elem);
1408				if (err)
1409					goto out;
1410			}
1411			todo -= l;
1412			c += l;
1413		}
1414		while (todo) {
1415			err = desc->xcode(desc, c);
1416			if (err)
1417				goto out;
1418			c += desc->elem_size;
1419			todo -= desc->elem_size;
1420		}
1421	}
1422	err = 0;
1423
1424out:
1425	kfree(elem);
1426	if (ppages)
1427		kunmap(*ppages);
1428	return err;
1429}
1430
1431int
1432xdr_decode_array2(struct xdr_buf *buf, unsigned int base,
1433		  struct xdr_array2_desc *desc)
1434{
1435	if (base >= buf->len)
1436		return -EINVAL;
1437
1438	return xdr_xcode_array2(buf, base, desc, 0);
1439}
1440EXPORT_SYMBOL_GPL(xdr_decode_array2);
1441
1442int
1443xdr_encode_array2(struct xdr_buf *buf, unsigned int base,
1444		  struct xdr_array2_desc *desc)
1445{
1446	if ((unsigned long) base + 4 + desc->array_len * desc->elem_size >
1447	    buf->head->iov_len + buf->page_len + buf->tail->iov_len)
1448		return -EINVAL;
1449
1450	return xdr_xcode_array2(buf, base, desc, 1);
1451}
1452EXPORT_SYMBOL_GPL(xdr_encode_array2);
1453
1454int
1455xdr_process_buf(struct xdr_buf *buf, unsigned int offset, unsigned int len,
1456		int (*actor)(struct scatterlist *, void *), void *data)
1457{
1458	int i, ret = 0;
1459	unsigned int page_len, thislen, page_offset;
1460	struct scatterlist      sg[1];
1461
1462	sg_init_table(sg, 1);
1463
1464	if (offset >= buf->head[0].iov_len) {
1465		offset -= buf->head[0].iov_len;
1466	} else {
1467		thislen = buf->head[0].iov_len - offset;
1468		if (thislen > len)
1469			thislen = len;
1470		sg_set_buf(sg, buf->head[0].iov_base + offset, thislen);
1471		ret = actor(sg, data);
1472		if (ret)
1473			goto out;
1474		offset = 0;
1475		len -= thislen;
1476	}
1477	if (len == 0)
1478		goto out;
1479
1480	if (offset >= buf->page_len) {
1481		offset -= buf->page_len;
1482	} else {
1483		page_len = buf->page_len - offset;
1484		if (page_len > len)
1485			page_len = len;
1486		len -= page_len;
1487		page_offset = (offset + buf->page_base) & (PAGE_SIZE - 1);
1488		i = (offset + buf->page_base) >> PAGE_SHIFT;
1489		thislen = PAGE_SIZE - page_offset;
1490		do {
1491			if (thislen > page_len)
1492				thislen = page_len;
1493			sg_set_page(sg, buf->pages[i], thislen, page_offset);
1494			ret = actor(sg, data);
1495			if (ret)
1496				goto out;
1497			page_len -= thislen;
1498			i++;
1499			page_offset = 0;
1500			thislen = PAGE_SIZE;
1501		} while (page_len != 0);
1502		offset = 0;
1503	}
1504	if (len == 0)
1505		goto out;
1506	if (offset < buf->tail[0].iov_len) {
1507		thislen = buf->tail[0].iov_len - offset;
1508		if (thislen > len)
1509			thislen = len;
1510		sg_set_buf(sg, buf->tail[0].iov_base + offset, thislen);
1511		ret = actor(sg, data);
1512		len -= thislen;
1513	}
1514	if (len != 0)
1515		ret = -EINVAL;
1516out:
1517	return ret;
1518}
1519EXPORT_SYMBOL_GPL(xdr_process_buf);
1520
1521/**
1522 * xdr_stream_decode_opaque - Decode variable length opaque
1523 * @xdr: pointer to xdr_stream
1524 * @ptr: location to store opaque data
1525 * @size: size of storage buffer @ptr
1526 *
1527 * Return values:
1528 *   On success, returns size of object stored in *@ptr
1529 *   %-EBADMSG on XDR buffer overflow
1530 *   %-EMSGSIZE on overflow of storage buffer @ptr
1531 */
1532ssize_t xdr_stream_decode_opaque(struct xdr_stream *xdr, void *ptr, size_t size)
1533{
1534	ssize_t ret;
1535	void *p;
1536
1537	ret = xdr_stream_decode_opaque_inline(xdr, &p, size);
1538	if (ret <= 0)
1539		return ret;
1540	memcpy(ptr, p, ret);
1541	return ret;
1542}
1543EXPORT_SYMBOL_GPL(xdr_stream_decode_opaque);
1544
1545/**
1546 * xdr_stream_decode_opaque_dup - Decode and duplicate variable length opaque
1547 * @xdr: pointer to xdr_stream
1548 * @ptr: location to store pointer to opaque data
1549 * @maxlen: maximum acceptable object size
1550 * @gfp_flags: GFP mask to use
1551 *
1552 * Return values:
1553 *   On success, returns size of object stored in *@ptr
1554 *   %-EBADMSG on XDR buffer overflow
1555 *   %-EMSGSIZE if the size of the object would exceed @maxlen
1556 *   %-ENOMEM on memory allocation failure
1557 */
1558ssize_t xdr_stream_decode_opaque_dup(struct xdr_stream *xdr, void **ptr,
1559		size_t maxlen, gfp_t gfp_flags)
1560{
1561	ssize_t ret;
1562	void *p;
1563
1564	ret = xdr_stream_decode_opaque_inline(xdr, &p, maxlen);
1565	if (ret > 0) {
1566		*ptr = kmemdup(p, ret, gfp_flags);
1567		if (*ptr != NULL)
1568			return ret;
1569		ret = -ENOMEM;
1570	}
1571	*ptr = NULL;
1572	return ret;
1573}
1574EXPORT_SYMBOL_GPL(xdr_stream_decode_opaque_dup);
1575
1576/**
1577 * xdr_stream_decode_string - Decode variable length string
1578 * @xdr: pointer to xdr_stream
1579 * @str: location to store string
1580 * @size: size of storage buffer @str
1581 *
1582 * Return values:
1583 *   On success, returns length of NUL-terminated string stored in *@str
1584 *   %-EBADMSG on XDR buffer overflow
1585 *   %-EMSGSIZE on overflow of storage buffer @str
1586 */
1587ssize_t xdr_stream_decode_string(struct xdr_stream *xdr, char *str, size_t size)
1588{
1589	ssize_t ret;
1590	void *p;
1591
1592	ret = xdr_stream_decode_opaque_inline(xdr, &p, size);
1593	if (ret > 0) {
1594		memcpy(str, p, ret);
1595		str[ret] = '\0';
1596		return strlen(str);
1597	}
1598	*str = '\0';
1599	return ret;
1600}
1601EXPORT_SYMBOL_GPL(xdr_stream_decode_string);
1602
1603/**
1604 * xdr_stream_decode_string_dup - Decode and duplicate variable length string
1605 * @xdr: pointer to xdr_stream
1606 * @str: location to store pointer to string
1607 * @maxlen: maximum acceptable string length
1608 * @gfp_flags: GFP mask to use
1609 *
1610 * Return values:
1611 *   On success, returns length of NUL-terminated string stored in *@ptr
1612 *   %-EBADMSG on XDR buffer overflow
1613 *   %-EMSGSIZE if the size of the string would exceed @maxlen
1614 *   %-ENOMEM on memory allocation failure
1615 */
1616ssize_t xdr_stream_decode_string_dup(struct xdr_stream *xdr, char **str,
1617		size_t maxlen, gfp_t gfp_flags)
1618{
1619	void *p;
1620	ssize_t ret;
1621
1622	ret = xdr_stream_decode_opaque_inline(xdr, &p, maxlen);
1623	if (ret > 0) {
1624		char *s = kmalloc(ret + 1, gfp_flags);
1625		if (s != NULL) {
1626			memcpy(s, p, ret);
1627			s[ret] = '\0';
1628			*str = s;
1629			return strlen(s);
1630		}
1631		ret = -ENOMEM;
1632	}
1633	*str = NULL;
1634	return ret;
1635}
1636EXPORT_SYMBOL_GPL(xdr_stream_decode_string_dup);