xdr.c

   1// SPDX-License-Identifier: GPL-2.0-only
   2/*
   3 * linux/net/sunrpc/xdr.c
   4 *
   5 * Generic XDR support.
   6 *
   7 * Copyright (C) 1995, 1996 Olaf Kirch <okir@monad.swb.de>
   8 */
   9
  10#include <linux/module.h>
  11#include <linux/slab.h>
  12#include <linux/types.h>
  13#include <linux/string.h>
  14#include <linux/kernel.h>
  15#include <linux/pagemap.h>
  16#include <linux/errno.h>
  17#include <linux/sunrpc/xdr.h>
  18#include <linux/sunrpc/msg_prot.h>
  19#include <linux/bvec.h>
  20#include <trace/events/sunrpc.h>
  21
  22static void _copy_to_pages(struct page **, size_t, const char *, size_t);
  23
  24
  25/*
  26 * XDR functions for basic NFS types
  27 */
  28__be32 *
  29xdr_encode_netobj(__be32 *p, const struct xdr_netobj *obj)
  30{
  31	unsigned int	quadlen = XDR_QUADLEN(obj->len);
  32
  33	p[quadlen] = 0;		/* zero trailing bytes */
  34	*p++ = cpu_to_be32(obj->len);
  35	memcpy(p, obj->data, obj->len);
  36	return p + XDR_QUADLEN(obj->len);
  37}
  38EXPORT_SYMBOL_GPL(xdr_encode_netobj);
  39
  40/**
  41 * xdr_encode_opaque_fixed - Encode fixed length opaque data
  42 * @p: pointer to current position in XDR buffer.
  43 * @ptr: pointer to data to encode (or NULL)
  44 * @nbytes: size of data.
  45 *
  46 * Copy the array of data of length nbytes at ptr to the XDR buffer
  47 * at position p, then align to the next 32-bit boundary by padding
  48 * with zero bytes (see RFC1832).
  49 * Note: if ptr is NULL, only the padding is performed.
  50 *
  51 * Returns the updated current XDR buffer position
  52 *
  53 */
  54__be32 *xdr_encode_opaque_fixed(__be32 *p, const void *ptr, unsigned int nbytes)
  55{
  56	if (likely(nbytes != 0)) {
  57		unsigned int quadlen = XDR_QUADLEN(nbytes);
  58		unsigned int padding = (quadlen << 2) - nbytes;
  59
  60		if (ptr != NULL)
  61			memcpy(p, ptr, nbytes);
  62		if (padding != 0)
  63			memset((char *)p + nbytes, 0, padding);
  64		p += quadlen;
  65	}
  66	return p;
  67}
  68EXPORT_SYMBOL_GPL(xdr_encode_opaque_fixed);
  69
  70/**
  71 * xdr_encode_opaque - Encode variable length opaque data
  72 * @p: pointer to current position in XDR buffer.
  73 * @ptr: pointer to data to encode (or NULL)
  74 * @nbytes: size of data.
  75 *
  76 * Returns the updated current XDR buffer position
  77 */
  78__be32 *xdr_encode_opaque(__be32 *p, const void *ptr, unsigned int nbytes)
  79{
  80	*p++ = cpu_to_be32(nbytes);
  81	return xdr_encode_opaque_fixed(p, ptr, nbytes);
  82}
  83EXPORT_SYMBOL_GPL(xdr_encode_opaque);
  84
  85__be32 *
  86xdr_encode_string(__be32 *p, const char *string)
  87{
  88	return xdr_encode_array(p, string, strlen(string));
  89}
  90EXPORT_SYMBOL_GPL(xdr_encode_string);
  91
  92/**
  93 * xdr_terminate_string - '\0'-terminate a string residing in an xdr_buf
  94 * @buf: XDR buffer where string resides
  95 * @len: length of string, in bytes
  96 *
  97 */
  98void xdr_terminate_string(const struct xdr_buf *buf, const u32 len)
  99{
 100	char *kaddr;
 101
 102	kaddr = kmap_atomic(buf->pages[0]);
 103	kaddr[buf->page_base + len] = '\0';
 104	kunmap_atomic(kaddr);
 105}
 106EXPORT_SYMBOL_GPL(xdr_terminate_string);
 107
 108size_t xdr_buf_pagecount(const struct xdr_buf *buf)
 109{
 110	if (!buf->page_len)
 111		return 0;
 112	return (buf->page_base + buf->page_len + PAGE_SIZE - 1) >> PAGE_SHIFT;
 113}
 114
 115int
 116xdr_alloc_bvec(struct xdr_buf *buf, gfp_t gfp)
 117{
 118	size_t i, n = xdr_buf_pagecount(buf);
 119
 120	if (n != 0 && buf->bvec == NULL) {
 121		buf->bvec = kmalloc_array(n, sizeof(buf->bvec[0]), gfp);
 122		if (!buf->bvec)
 123			return -ENOMEM;
 124		for (i = 0; i < n; i++) {
 125			bvec_set_page(&buf->bvec[i], buf->pages[i], PAGE_SIZE,
 126				      0);
 127		}
 128	}
 129	return 0;
 130}
 131
 132void
 133xdr_free_bvec(struct xdr_buf *buf)
 134{
 135	kfree(buf->bvec);
 136	buf->bvec = NULL;
 137}
 138
 139/**
 140 * xdr_buf_to_bvec - Copy components of an xdr_buf into a bio_vec array
 141 * @bvec: bio_vec array to populate
 142 * @bvec_size: element count of @bio_vec
 143 * @xdr: xdr_buf to be copied
 144 *
 145 * Returns the number of entries consumed in @bvec.
 146 */
 147unsigned int xdr_buf_to_bvec(struct bio_vec *bvec, unsigned int bvec_size,
 148			     const struct xdr_buf *xdr)
 149{
 150	const struct kvec *head = xdr->head;
 151	const struct kvec *tail = xdr->tail;
 152	unsigned int count = 0;
 153
 154	if (head->iov_len) {
 155		bvec_set_virt(bvec++, head->iov_base, head->iov_len);
 156		++count;
 157	}
 158
 159	if (xdr->page_len) {
 160		unsigned int offset, len, remaining;
 161		struct page **pages = xdr->pages;
 162
 163		offset = offset_in_page(xdr->page_base);
 164		remaining = xdr->page_len;
 165		while (remaining > 0) {
 166			len = min_t(unsigned int, remaining,
 167				    PAGE_SIZE - offset);
 168			bvec_set_page(bvec++, *pages++, len, offset);
 169			remaining -= len;
 170			offset = 0;
 171			if (unlikely(++count > bvec_size))
 172				goto bvec_overflow;
 173		}
 174	}
 175
 176	if (tail->iov_len) {
 177		bvec_set_virt(bvec, tail->iov_base, tail->iov_len);
 178		if (unlikely(++count > bvec_size))
 179			goto bvec_overflow;
 180	}
 181
 182	return count;
 183
 184bvec_overflow:
 185	pr_warn_once("%s: bio_vec array overflow\n", __func__);
 186	return count - 1;
 187}
 188EXPORT_SYMBOL_GPL(xdr_buf_to_bvec);
 189
 190/**
 191 * xdr_inline_pages - Prepare receive buffer for a large reply
 192 * @xdr: xdr_buf into which reply will be placed
 193 * @offset: expected offset where data payload will start, in bytes
 194 * @pages: vector of struct page pointers
 195 * @base: offset in first page where receive should start, in bytes
 196 * @len: expected size of the upper layer data payload, in bytes
 197 *
 198 */
 199void
 200xdr_inline_pages(struct xdr_buf *xdr, unsigned int offset,
 201		 struct page **pages, unsigned int base, unsigned int len)
 202{
 203	struct kvec *head = xdr->head;
 204	struct kvec *tail = xdr->tail;
 205	char *buf = (char *)head->iov_base;
 206	unsigned int buflen = head->iov_len;
 207
 208	head->iov_len  = offset;
 209
 210	xdr->pages = pages;
 211	xdr->page_base = base;
 212	xdr->page_len = len;
 213
 214	tail->iov_base = buf + offset;
 215	tail->iov_len = buflen - offset;
 216	xdr->buflen += len;
 217}
 218EXPORT_SYMBOL_GPL(xdr_inline_pages);
 219
 220/*
 221 * Helper routines for doing 'memmove' like operations on a struct xdr_buf
 222 */
 223
 224/**
 225 * _shift_data_left_pages
 226 * @pages: vector of pages containing both the source and dest memory area.
 227 * @pgto_base: page vector address of destination
 228 * @pgfrom_base: page vector address of source
 229 * @len: number of bytes to copy
 230 *
 231 * Note: the addresses pgto_base and pgfrom_base are both calculated in
 232 *       the same way:
 233 *            if a memory area starts at byte 'base' in page 'pages[i]',
 234 *            then its address is given as (i << PAGE_CACHE_SHIFT) + base
 235 * Alse note: pgto_base must be < pgfrom_base, but the memory areas
 236 * 	they point to may overlap.
 237 */
 238static void
 239_shift_data_left_pages(struct page **pages, size_t pgto_base,
 240			size_t pgfrom_base, size_t len)
 241{
 242	struct page **pgfrom, **pgto;
 243	char *vfrom, *vto;
 244	size_t copy;
 245
 246	BUG_ON(pgfrom_base <= pgto_base);
 247
 248	if (!len)
 249		return;
 250
 251	pgto = pages + (pgto_base >> PAGE_SHIFT);
 252	pgfrom = pages + (pgfrom_base >> PAGE_SHIFT);
 253
 254	pgto_base &= ~PAGE_MASK;
 255	pgfrom_base &= ~PAGE_MASK;
 256
 257	do {
 258		if (pgto_base >= PAGE_SIZE) {
 259			pgto_base = 0;
 260			pgto++;
 261		}
 262		if (pgfrom_base >= PAGE_SIZE){
 263			pgfrom_base = 0;
 264			pgfrom++;
 265		}
 266
 267		copy = len;
 268		if (copy > (PAGE_SIZE - pgto_base))
 269			copy = PAGE_SIZE - pgto_base;
 270		if (copy > (PAGE_SIZE - pgfrom_base))
 271			copy = PAGE_SIZE - pgfrom_base;
 272
 273		vto = kmap_atomic(*pgto);
 274		if (*pgto != *pgfrom) {
 275			vfrom = kmap_atomic(*pgfrom);
 276			memcpy(vto + pgto_base, vfrom + pgfrom_base, copy);
 277			kunmap_atomic(vfrom);
 278		} else
 279			memmove(vto + pgto_base, vto + pgfrom_base, copy);
 280		flush_dcache_page(*pgto);
 281		kunmap_atomic(vto);
 282
 283		pgto_base += copy;
 284		pgfrom_base += copy;
 285
 286	} while ((len -= copy) != 0);
 287}
 288
 289/**
 290 * _shift_data_right_pages
 291 * @pages: vector of pages containing both the source and dest memory area.
 292 * @pgto_base: page vector address of destination
 293 * @pgfrom_base: page vector address of source
 294 * @len: number of bytes to copy
 295 *
 296 * Note: the addresses pgto_base and pgfrom_base are both calculated in
 297 *       the same way:
 298 *            if a memory area starts at byte 'base' in page 'pages[i]',
 299 *            then its address is given as (i << PAGE_SHIFT) + base
 300 * Also note: pgfrom_base must be < pgto_base, but the memory areas
 301 * 	they point to may overlap.
 302 */
 303static void
 304_shift_data_right_pages(struct page **pages, size_t pgto_base,
 305		size_t pgfrom_base, size_t len)
 306{
 307	struct page **pgfrom, **pgto;
 308	char *vfrom, *vto;
 309	size_t copy;
 310
 311	BUG_ON(pgto_base <= pgfrom_base);
 312
 313	if (!len)
 314		return;
 315
 316	pgto_base += len;
 317	pgfrom_base += len;
 318
 319	pgto = pages + (pgto_base >> PAGE_SHIFT);
 320	pgfrom = pages + (pgfrom_base >> PAGE_SHIFT);
 321
 322	pgto_base &= ~PAGE_MASK;
 323	pgfrom_base &= ~PAGE_MASK;
 324
 325	do {
 326		/* Are any pointers crossing a page boundary? */
 327		if (pgto_base == 0) {
 328			pgto_base = PAGE_SIZE;
 329			pgto--;
 330		}
 331		if (pgfrom_base == 0) {
 332			pgfrom_base = PAGE_SIZE;
 333			pgfrom--;
 334		}
 335
 336		copy = len;
 337		if (copy > pgto_base)
 338			copy = pgto_base;
 339		if (copy > pgfrom_base)
 340			copy = pgfrom_base;
 341		pgto_base -= copy;
 342		pgfrom_base -= copy;
 343
 344		vto = kmap_atomic(*pgto);
 345		if (*pgto != *pgfrom) {
 346			vfrom = kmap_atomic(*pgfrom);
 347			memcpy(vto + pgto_base, vfrom + pgfrom_base, copy);
 348			kunmap_atomic(vfrom);
 349		} else
 350			memmove(vto + pgto_base, vto + pgfrom_base, copy);
 351		flush_dcache_page(*pgto);
 352		kunmap_atomic(vto);
 353
 354	} while ((len -= copy) != 0);
 355}
 356
 357/**
 358 * _copy_to_pages
 359 * @pages: array of pages
 360 * @pgbase: page vector address of destination
 361 * @p: pointer to source data
 362 * @len: length
 363 *
 364 * Copies data from an arbitrary memory location into an array of pages
 365 * The copy is assumed to be non-overlapping.
 366 */
 367static void
 368_copy_to_pages(struct page **pages, size_t pgbase, const char *p, size_t len)
 369{
 370	struct page **pgto;
 371	char *vto;
 372	size_t copy;
 373
 374	if (!len)
 375		return;
 376
 377	pgto = pages + (pgbase >> PAGE_SHIFT);
 378	pgbase &= ~PAGE_MASK;
 379
 380	for (;;) {
 381		copy = PAGE_SIZE - pgbase;
 382		if (copy > len)
 383			copy = len;
 384
 385		vto = kmap_atomic(*pgto);
 386		memcpy(vto + pgbase, p, copy);
 387		kunmap_atomic(vto);
 388
 389		len -= copy;
 390		if (len == 0)
 391			break;
 392
 393		pgbase += copy;
 394		if (pgbase == PAGE_SIZE) {
 395			flush_dcache_page(*pgto);
 396			pgbase = 0;
 397			pgto++;
 398		}
 399		p += copy;
 400	}
 401	flush_dcache_page(*pgto);
 402}
 403
 404/**
 405 * _copy_from_pages
 406 * @p: pointer to destination
 407 * @pages: array of pages
 408 * @pgbase: offset of source data
 409 * @len: length
 410 *
 411 * Copies data into an arbitrary memory location from an array of pages
 412 * The copy is assumed to be non-overlapping.
 413 */
 414void
 415_copy_from_pages(char *p, struct page **pages, size_t pgbase, size_t len)
 416{
 417	struct page **pgfrom;
 418	char *vfrom;
 419	size_t copy;
 420
 421	if (!len)
 422		return;
 423
 424	pgfrom = pages + (pgbase >> PAGE_SHIFT);
 425	pgbase &= ~PAGE_MASK;
 426
 427	do {
 428		copy = PAGE_SIZE - pgbase;
 429		if (copy > len)
 430			copy = len;
 431
 432		vfrom = kmap_atomic(*pgfrom);
 433		memcpy(p, vfrom + pgbase, copy);
 434		kunmap_atomic(vfrom);
 435
 436		pgbase += copy;
 437		if (pgbase == PAGE_SIZE) {
 438			pgbase = 0;
 439			pgfrom++;
 440		}
 441		p += copy;
 442
 443	} while ((len -= copy) != 0);
 444}
 445EXPORT_SYMBOL_GPL(_copy_from_pages);
 446
 447static void xdr_buf_iov_zero(const struct kvec *iov, unsigned int base,
 448			     unsigned int len)
 449{
 450	if (base >= iov->iov_len)
 451		return;
 452	if (len > iov->iov_len - base)
 453		len = iov->iov_len - base;
 454	memset(iov->iov_base + base, 0, len);
 455}
 456
 457/**
 458 * xdr_buf_pages_zero
 459 * @buf: xdr_buf
 460 * @pgbase: beginning offset
 461 * @len: length
 462 */
 463static void xdr_buf_pages_zero(const struct xdr_buf *buf, unsigned int pgbase,
 464			       unsigned int len)
 465{
 466	struct page **pages = buf->pages;
 467	struct page **page;
 468	char *vpage;
 469	unsigned int zero;
 470
 471	if (!len)
 472		return;
 473	if (pgbase >= buf->page_len) {
 474		xdr_buf_iov_zero(buf->tail, pgbase - buf->page_len, len);
 475		return;
 476	}
 477	if (pgbase + len > buf->page_len) {
 478		xdr_buf_iov_zero(buf->tail, 0, pgbase + len - buf->page_len);
 479		len = buf->page_len - pgbase;
 480	}
 481
 482	pgbase += buf->page_base;
 483
 484	page = pages + (pgbase >> PAGE_SHIFT);
 485	pgbase &= ~PAGE_MASK;
 486
 487	do {
 488		zero = PAGE_SIZE - pgbase;
 489		if (zero > len)
 490			zero = len;
 491
 492		vpage = kmap_atomic(*page);
 493		memset(vpage + pgbase, 0, zero);
 494		kunmap_atomic(vpage);
 495
 496		flush_dcache_page(*page);
 497		pgbase = 0;
 498		page++;
 499
 500	} while ((len -= zero) != 0);
 501}
 502
 503static unsigned int xdr_buf_pages_fill_sparse(const struct xdr_buf *buf,
 504					      unsigned int buflen, gfp_t gfp)
 505{
 506	unsigned int i, npages, pagelen;
 507
 508	if (!(buf->flags & XDRBUF_SPARSE_PAGES))
 509		return buflen;
 510	if (buflen <= buf->head->iov_len)
 511		return buflen;
 512	pagelen = buflen - buf->head->iov_len;
 513	if (pagelen > buf->page_len)
 514		pagelen = buf->page_len;
 515	npages = (pagelen + buf->page_base + PAGE_SIZE - 1) >> PAGE_SHIFT;
 516	for (i = 0; i < npages; i++) {
 517		if (!buf->pages[i])
 518			continue;
 519		buf->pages[i] = alloc_page(gfp);
 520		if (likely(buf->pages[i]))
 521			continue;
 522		buflen -= pagelen;
 523		pagelen = i << PAGE_SHIFT;
 524		if (pagelen > buf->page_base)
 525			buflen += pagelen - buf->page_base;
 526		break;
 527	}
 528	return buflen;
 529}
 530
 531static void xdr_buf_try_expand(struct xdr_buf *buf, unsigned int len)
 532{
 533	struct kvec *head = buf->head;
 534	struct kvec *tail = buf->tail;
 535	unsigned int sum = head->iov_len + buf->page_len + tail->iov_len;
 536	unsigned int free_space, newlen;
 537
 538	if (sum > buf->len) {
 539		free_space = min_t(unsigned int, sum - buf->len, len);
 540		newlen = xdr_buf_pages_fill_sparse(buf, buf->len + free_space,
 541						   GFP_KERNEL);
 542		free_space = newlen - buf->len;
 543		buf->len = newlen;
 544		len -= free_space;
 545		if (!len)
 546			return;
 547	}
 548
 549	if (buf->buflen > sum) {
 550		/* Expand the tail buffer */
 551		free_space = min_t(unsigned int, buf->buflen - sum, len);
 552		tail->iov_len += free_space;
 553		buf->len += free_space;
 554	}
 555}
 556
 557static void xdr_buf_tail_copy_right(const struct xdr_buf *buf,
 558				    unsigned int base, unsigned int len,
 559				    unsigned int shift)
 560{
 561	const struct kvec *tail = buf->tail;
 562	unsigned int to = base + shift;
 563
 564	if (to >= tail->iov_len)
 565		return;
 566	if (len + to > tail->iov_len)
 567		len = tail->iov_len - to;
 568	memmove(tail->iov_base + to, tail->iov_base + base, len);
 569}
 570
 571static void xdr_buf_pages_copy_right(const struct xdr_buf *buf,
 572				     unsigned int base, unsigned int len,
 573				     unsigned int shift)
 574{
 575	const struct kvec *tail = buf->tail;
 576	unsigned int to = base + shift;
 577	unsigned int pglen = 0;
 578	unsigned int talen = 0, tato = 0;
 579
 580	if (base >= buf->page_len)
 581		return;
 582	if (len > buf->page_len - base)
 583		len = buf->page_len - base;
 584	if (to >= buf->page_len) {
 585		tato = to - buf->page_len;
 586		if (tail->iov_len >= len + tato)
 587			talen = len;
 588		else if (tail->iov_len > tato)
 589			talen = tail->iov_len - tato;
 590	} else if (len + to >= buf->page_len) {
 591		pglen = buf->page_len - to;
 592		talen = len - pglen;
 593		if (talen > tail->iov_len)
 594			talen = tail->iov_len;
 595	} else
 596		pglen = len;
 597
 598	_copy_from_pages(tail->iov_base + tato, buf->pages,
 599			 buf->page_base + base + pglen, talen);
 600	_shift_data_right_pages(buf->pages, buf->page_base + to,
 601				buf->page_base + base, pglen);
 602}
 603
 604static void xdr_buf_head_copy_right(const struct xdr_buf *buf,
 605				    unsigned int base, unsigned int len,
 606				    unsigned int shift)
 607{
 608	const struct kvec *head = buf->head;
 609	const struct kvec *tail = buf->tail;
 610	unsigned int to = base + shift;
 611	unsigned int pglen = 0, pgto = 0;
 612	unsigned int talen = 0, tato = 0;
 613
 614	if (base >= head->iov_len)
 615		return;
 616	if (len > head->iov_len - base)
 617		len = head->iov_len - base;
 618	if (to >= buf->page_len + head->iov_len) {
 619		tato = to - buf->page_len - head->iov_len;
 620		talen = len;
 621	} else if (to >= head->iov_len) {
 622		pgto = to - head->iov_len;
 623		pglen = len;
 624		if (pgto + pglen > buf->page_len) {
 625			talen = pgto + pglen - buf->page_len;
 626			pglen -= talen;
 627		}
 628	} else {
 629		pglen = len - to;
 630		if (pglen > buf->page_len) {
 631			talen = pglen - buf->page_len;
 632			pglen = buf->page_len;
 633		}
 634	}
 635
 636	len -= talen;
 637	base += len;
 638	if (talen + tato > tail->iov_len)
 639		talen = tail->iov_len > tato ? tail->iov_len - tato : 0;
 640	memcpy(tail->iov_base + tato, head->iov_base + base, talen);
 641
 642	len -= pglen;
 643	base -= pglen;
 644	_copy_to_pages(buf->pages, buf->page_base + pgto, head->iov_base + base,
 645		       pglen);
 646
 647	base -= len;
 648	memmove(head->iov_base + to, head->iov_base + base, len);
 649}
 650
 651static void xdr_buf_tail_shift_right(const struct xdr_buf *buf,
 652				     unsigned int base, unsigned int len,
 653				     unsigned int shift)
 654{
 655	const struct kvec *tail = buf->tail;
 656
 657	if (base >= tail->iov_len || !shift || !len)
 658		return;
 659	xdr_buf_tail_copy_right(buf, base, len, shift);
 660}
 661
 662static void xdr_buf_pages_shift_right(const struct xdr_buf *buf,
 663				      unsigned int base, unsigned int len,
 664				      unsigned int shift)
 665{
 666	if (!shift || !len)
 667		return;
 668	if (base >= buf->page_len) {
 669		xdr_buf_tail_shift_right(buf, base - buf->page_len, len, shift);
 670		return;
 671	}
 672	if (base + len > buf->page_len)
 673		xdr_buf_tail_shift_right(buf, 0, base + len - buf->page_len,
 674					 shift);
 675	xdr_buf_pages_copy_right(buf, base, len, shift);
 676}
 677
 678static void xdr_buf_head_shift_right(const struct xdr_buf *buf,
 679				     unsigned int base, unsigned int len,
 680				     unsigned int shift)
 681{
 682	const struct kvec *head = buf->head;
 683
 684	if (!shift)
 685		return;
 686	if (base >= head->iov_len) {
 687		xdr_buf_pages_shift_right(buf, head->iov_len - base, len,
 688					  shift);
 689		return;
 690	}
 691	if (base + len > head->iov_len)
 692		xdr_buf_pages_shift_right(buf, 0, base + len - head->iov_len,
 693					  shift);
 694	xdr_buf_head_copy_right(buf, base, len, shift);
 695}
 696
 697static void xdr_buf_tail_copy_left(const struct xdr_buf *buf, unsigned int base,
 698				   unsigned int len, unsigned int shift)
 699{
 700	const struct kvec *tail = buf->tail;
 701
 702	if (base >= tail->iov_len)
 703		return;
 704	if (len > tail->iov_len - base)
 705		len = tail->iov_len - base;
 706	/* Shift data into head */
 707	if (shift > buf->page_len + base) {
 708		const struct kvec *head = buf->head;
 709		unsigned int hdto =
 710			head->iov_len + buf->page_len + base - shift;
 711		unsigned int hdlen = len;
 712
 713		if (WARN_ONCE(shift > head->iov_len + buf->page_len + base,
 714			      "SUNRPC: Misaligned data.\n"))
 715			return;
 716		if (hdto + hdlen > head->iov_len)
 717			hdlen = head->iov_len - hdto;
 718		memcpy(head->iov_base + hdto, tail->iov_base + base, hdlen);
 719		base += hdlen;
 720		len -= hdlen;
 721		if (!len)
 722			return;
 723	}
 724	/* Shift data into pages */
 725	if (shift > base) {
 726		unsigned int pgto = buf->page_len + base - shift;
 727		unsigned int pglen = len;
 728
 729		if (pgto + pglen > buf->page_len)
 730			pglen = buf->page_len - pgto;
 731		_copy_to_pages(buf->pages, buf->page_base + pgto,
 732			       tail->iov_base + base, pglen);
 733		base += pglen;
 734		len -= pglen;
 735		if (!len)
 736			return;
 737	}
 738	memmove(tail->iov_base + base - shift, tail->iov_base + base, len);
 739}
 740
 741static void xdr_buf_pages_copy_left(const struct xdr_buf *buf,
 742				    unsigned int base, unsigned int len,
 743				    unsigned int shift)
 744{
 745	unsigned int pgto;
 746
 747	if (base >= buf->page_len)
 748		return;
 749	if (len > buf->page_len - base)
 750		len = buf->page_len - base;
 751	/* Shift data into head */
 752	if (shift > base) {
 753		const struct kvec *head = buf->head;
 754		unsigned int hdto = head->iov_len + base - shift;
 755		unsigned int hdlen = len;
 756
 757		if (WARN_ONCE(shift > head->iov_len + base,
 758			      "SUNRPC: Misaligned data.\n"))
 759			return;
 760		if (hdto + hdlen > head->iov_len)
 761			hdlen = head->iov_len - hdto;
 762		_copy_from_pages(head->iov_base + hdto, buf->pages,
 763				 buf->page_base + base, hdlen);
 764		base += hdlen;
 765		len -= hdlen;
 766		if (!len)
 767			return;
 768	}
 769	pgto = base - shift;
 770	_shift_data_left_pages(buf->pages, buf->page_base + pgto,
 771			       buf->page_base + base, len);
 772}
 773
 774static void xdr_buf_tail_shift_left(const struct xdr_buf *buf,
 775				    unsigned int base, unsigned int len,
 776				    unsigned int shift)
 777{
 778	if (!shift || !len)
 779		return;
 780	xdr_buf_tail_copy_left(buf, base, len, shift);
 781}
 782
 783static void xdr_buf_pages_shift_left(const struct xdr_buf *buf,
 784				     unsigned int base, unsigned int len,
 785				     unsigned int shift)
 786{
 787	if (!shift || !len)
 788		return;
 789	if (base >= buf->page_len) {
 790		xdr_buf_tail_shift_left(buf, base - buf->page_len, len, shift);
 791		return;
 792	}
 793	xdr_buf_pages_copy_left(buf, base, len, shift);
 794	len += base;
 795	if (len <= buf->page_len)
 796		return;
 797	xdr_buf_tail_copy_left(buf, 0, len - buf->page_len, shift);
 798}
 799
 800static void xdr_buf_head_shift_left(const struct xdr_buf *buf,
 801				    unsigned int base, unsigned int len,
 802				    unsigned int shift)
 803{
 804	const struct kvec *head = buf->head;
 805	unsigned int bytes;
 806
 807	if (!shift || !len)
 808		return;
 809
 810	if (shift > base) {
 811		bytes = (shift - base);
 812		if (bytes >= len)
 813			return;
 814		base += bytes;
 815		len -= bytes;
 816	}
 817
 818	if (base < head->iov_len) {
 819		bytes = min_t(unsigned int, len, head->iov_len - base);
 820		memmove(head->iov_base + (base - shift),
 821			head->iov_base + base, bytes);
 822		base += bytes;
 823		len -= bytes;
 824	}
 825	xdr_buf_pages_shift_left(buf, base - head->iov_len, len, shift);
 826}
 827
 828/**
 829 * xdr_shrink_bufhead
 830 * @buf: xdr_buf
 831 * @len: new length of buf->head[0]
 832 *
 833 * Shrinks XDR buffer's header kvec buf->head[0], setting it to
 834 * 'len' bytes. The extra data is not lost, but is instead
 835 * moved into the inlined pages and/or the tail.
 836 */
 837static unsigned int xdr_shrink_bufhead(struct xdr_buf *buf, unsigned int len)
 838{
 839	struct kvec *head = buf->head;
 840	unsigned int shift, buflen = max(buf->len, len);
 841
 842	WARN_ON_ONCE(len > head->iov_len);
 843	if (head->iov_len > buflen) {
 844		buf->buflen -= head->iov_len - buflen;
 845		head->iov_len = buflen;
 846	}
 847	if (len >= head->iov_len)
 848		return 0;
 849	shift = head->iov_len - len;
 850	xdr_buf_try_expand(buf, shift);
 851	xdr_buf_head_shift_right(buf, len, buflen - len, shift);
 852	head->iov_len = len;
 853	buf->buflen -= shift;
 854	buf->len -= shift;
 855	return shift;
 856}
 857
 858/**
 859 * xdr_shrink_pagelen - shrinks buf->pages to @len bytes
 860 * @buf: xdr_buf
 861 * @len: new page buffer length
 862 *
 863 * The extra data is not lost, but is instead moved into buf->tail.
 864 * Returns the actual number of bytes moved.
 865 */
 866static unsigned int xdr_shrink_pagelen(struct xdr_buf *buf, unsigned int len)
 867{
 868	unsigned int shift, buflen = buf->len - buf->head->iov_len;
 869
 870	WARN_ON_ONCE(len > buf->page_len);
 871	if (buf->head->iov_len >= buf->len || len > buflen)
 872		buflen = len;
 873	if (buf->page_len > buflen) {
 874		buf->buflen -= buf->page_len - buflen;
 875		buf->page_len = buflen;
 876	}
 877	if (len >= buf->page_len)
 878		return 0;
 879	shift = buf->page_len - len;
 880	xdr_buf_try_expand(buf, shift);
 881	xdr_buf_pages_shift_right(buf, len, buflen - len, shift);
 882	buf->page_len = len;
 883	buf->len -= shift;
 884	buf->buflen -= shift;
 885	return shift;
 886}
 887
 888/**
 889 * xdr_stream_pos - Return the current offset from the start of the xdr_stream
 890 * @xdr: pointer to struct xdr_stream
 891 */
 892unsigned int xdr_stream_pos(const struct xdr_stream *xdr)
 893{
 894	return (unsigned int)(XDR_QUADLEN(xdr->buf->len) - xdr->nwords) << 2;
 895}
 896EXPORT_SYMBOL_GPL(xdr_stream_pos);
 897
 898static void xdr_stream_set_pos(struct xdr_stream *xdr, unsigned int pos)
 899{
 900	unsigned int blen = xdr->buf->len;
 901
 902	xdr->nwords = blen > pos ? XDR_QUADLEN(blen) - XDR_QUADLEN(pos) : 0;
 903}
 904
 905static void xdr_stream_page_set_pos(struct xdr_stream *xdr, unsigned int pos)
 906{
 907	xdr_stream_set_pos(xdr, pos + xdr->buf->head[0].iov_len);
 908}
 909
 910/**
 911 * xdr_page_pos - Return the current offset from the start of the xdr pages
 912 * @xdr: pointer to struct xdr_stream
 913 */
 914unsigned int xdr_page_pos(const struct xdr_stream *xdr)
 915{
 916	unsigned int pos = xdr_stream_pos(xdr);
 917
 918	WARN_ON(pos < xdr->buf->head[0].iov_len);
 919	return pos - xdr->buf->head[0].iov_len;
 920}
 921EXPORT_SYMBOL_GPL(xdr_page_pos);
 922
 923/**
 924 * xdr_init_encode - Initialize a struct xdr_stream for sending data.
 925 * @xdr: pointer to xdr_stream struct
 926 * @buf: pointer to XDR buffer in which to encode data
 927 * @p: current pointer inside XDR buffer
 928 * @rqst: pointer to controlling rpc_rqst, for debugging
 929 *
 930 * Note: at the moment the RPC client only passes the length of our
 931 *	 scratch buffer in the xdr_buf's header kvec. Previously this
 932 *	 meant we needed to call xdr_adjust_iovec() after encoding the
 933 *	 data. With the new scheme, the xdr_stream manages the details
 934 *	 of the buffer length, and takes care of adjusting the kvec
 935 *	 length for us.
 936 */
 937void xdr_init_encode(struct xdr_stream *xdr, struct xdr_buf *buf, __be32 *p,
 938		     struct rpc_rqst *rqst)
 939{
 940	struct kvec *iov = buf->head;
 941	int scratch_len = buf->buflen - buf->page_len - buf->tail[0].iov_len;
 942
 943	xdr_reset_scratch_buffer(xdr);
 944	BUG_ON(scratch_len < 0);
 945	xdr->buf = buf;
 946	xdr->iov = iov;
 947	xdr->p = (__be32 *)((char *)iov->iov_base + iov->iov_len);
 948	xdr->end = (__be32 *)((char *)iov->iov_base + scratch_len);
 949	BUG_ON(iov->iov_len > scratch_len);
 950
 951	if (p != xdr->p && p != NULL) {
 952		size_t len;
 953
 954		BUG_ON(p < xdr->p || p > xdr->end);
 955		len = (char *)p - (char *)xdr->p;
 956		xdr->p = p;
 957		buf->len += len;
 958		iov->iov_len += len;
 959	}
 960	xdr->rqst = rqst;
 961}
 962EXPORT_SYMBOL_GPL(xdr_init_encode);
 963
 964/**
 965 * xdr_init_encode_pages - Initialize an xdr_stream for encoding into pages
 966 * @xdr: pointer to xdr_stream struct
 967 * @buf: pointer to XDR buffer into which to encode data
 968 *
 969 */
 970void xdr_init_encode_pages(struct xdr_stream *xdr, struct xdr_buf *buf)
 971{
 972	xdr_reset_scratch_buffer(xdr);
 973
 974	xdr->buf = buf;
 975	xdr->page_ptr = buf->pages;
 976	xdr->iov = NULL;
 977	xdr->p = page_address(*xdr->page_ptr);
 978	xdr->end = (void *)xdr->p + min_t(u32, buf->buflen, PAGE_SIZE);
 979	xdr->rqst = NULL;
 980}
 981EXPORT_SYMBOL_GPL(xdr_init_encode_pages);
 982
 983/**
 984 * __xdr_commit_encode - Ensure all data is written to buffer
 985 * @xdr: pointer to xdr_stream
 986 *
 987 * We handle encoding across page boundaries by giving the caller a
 988 * temporary location to write to, then later copying the data into
 989 * place; xdr_commit_encode does that copying.
 990 *
 991 * Normally the caller doesn't need to call this directly, as the
 992 * following xdr_reserve_space will do it.  But an explicit call may be
 993 * required at the end of encoding, or any other time when the xdr_buf
 994 * data might be read.
 995 */
 996void __xdr_commit_encode(struct xdr_stream *xdr)
 997{
 998	size_t shift = xdr->scratch.iov_len;
 999	void *page;
1000
1001	page = page_address(*xdr->page_ptr);
1002	memcpy(xdr->scratch.iov_base, page, shift);
1003	memmove(page, page + shift, (void *)xdr->p - page);
1004	xdr_reset_scratch_buffer(xdr);
1005}
1006EXPORT_SYMBOL_GPL(__xdr_commit_encode);
1007
1008/*
1009 * The buffer space to be reserved crosses the boundary between
1010 * xdr->buf->head and xdr->buf->pages, or between two pages
1011 * in xdr->buf->pages.
1012 */
1013static noinline __be32 *xdr_get_next_encode_buffer(struct xdr_stream *xdr,
1014						   size_t nbytes)
1015{
1016	int space_left;
1017	int frag1bytes, frag2bytes;
1018	void *p;
1019
1020	if (nbytes > PAGE_SIZE)
1021		goto out_overflow; /* Bigger buffers require special handling */
1022	if (xdr->buf->len + nbytes > xdr->buf->buflen)
1023		goto out_overflow; /* Sorry, we're totally out of space */
1024	frag1bytes = (xdr->end - xdr->p) << 2;
1025	frag2bytes = nbytes - frag1bytes;
1026	if (xdr->iov)
1027		xdr->iov->iov_len += frag1bytes;
1028	else
1029		xdr->buf->page_len += frag1bytes;
1030	xdr->page_ptr++;
1031	xdr->iov = NULL;
1032
1033	/*
1034	 * If the last encode didn't end exactly on a page boundary, the
1035	 * next one will straddle boundaries.  Encode into the next
1036	 * page, then copy it back later in xdr_commit_encode.  We use
1037	 * the "scratch" iov to track any temporarily unused fragment of
1038	 * space at the end of the previous buffer:
1039	 */
1040	xdr_set_scratch_buffer(xdr, xdr->p, frag1bytes);
1041
1042	/*
1043	 * xdr->p is where the next encode will start after
1044	 * xdr_commit_encode() has shifted this one back:
1045	 */
1046	p = page_address(*xdr->page_ptr);
1047	xdr->p = p + frag2bytes;
1048	space_left = xdr->buf->buflen - xdr->buf->len;
1049	if (space_left - frag1bytes >= PAGE_SIZE)
1050		xdr->end = p + PAGE_SIZE;
1051	else
1052		xdr->end = p + space_left - frag1bytes;
1053
1054	xdr->buf->page_len += frag2bytes;
1055	xdr->buf->len += nbytes;
1056	return p;
1057out_overflow:
1058	trace_rpc_xdr_overflow(xdr, nbytes);
1059	return NULL;
1060}
1061
1062/**
1063 * xdr_reserve_space - Reserve buffer space for sending
1064 * @xdr: pointer to xdr_stream
1065 * @nbytes: number of bytes to reserve
1066 *
1067 * Checks that we have enough buffer space to encode 'nbytes' more
1068 * bytes of data. If so, update the total xdr_buf length, and
1069 * adjust the length of the current kvec.
1070 *
1071 * The returned pointer is valid only until the next call to
1072 * xdr_reserve_space() or xdr_commit_encode() on @xdr. The current
1073 * implementation of this API guarantees that space reserved for a
1074 * four-byte data item remains valid until @xdr is destroyed, but
1075 * that might not always be true in the future.
1076 */
1077__be32 * xdr_reserve_space(struct xdr_stream *xdr, size_t nbytes)
1078{
1079	__be32 *p = xdr->p;
1080	__be32 *q;
1081
1082	xdr_commit_encode(xdr);
1083	/* align nbytes on the next 32-bit boundary */
1084	nbytes += 3;
1085	nbytes &= ~3;
1086	q = p + (nbytes >> 2);
1087	if (unlikely(q > xdr->end || q < p))
1088		return xdr_get_next_encode_buffer(xdr, nbytes);
1089	xdr->p = q;
1090	if (xdr->iov)
1091		xdr->iov->iov_len += nbytes;
1092	else
1093		xdr->buf->page_len += nbytes;
1094	xdr->buf->len += nbytes;
1095	return p;
1096}
1097EXPORT_SYMBOL_GPL(xdr_reserve_space);
1098
1099/**
1100 * xdr_reserve_space_vec - Reserves a large amount of buffer space for sending
1101 * @xdr: pointer to xdr_stream
1102 * @nbytes: number of bytes to reserve
1103 *
1104 * The size argument passed to xdr_reserve_space() is determined based
1105 * on the number of bytes remaining in the current page to avoid
1106 * invalidating iov_base pointers when xdr_commit_encode() is called.
1107 *
1108 * Return values:
1109 *   %0: success
1110 *   %-EMSGSIZE: not enough space is available in @xdr
1111 */
1112int xdr_reserve_space_vec(struct xdr_stream *xdr, size_t nbytes)
1113{
1114	size_t thislen;
1115	__be32 *p;
1116
1117	/*
1118	 * svcrdma requires every READ payload to start somewhere
1119	 * in xdr->pages.
1120	 */
1121	if (xdr->iov == xdr->buf->head) {
1122		xdr->iov = NULL;
1123		xdr->end = xdr->p;
1124	}
1125
1126	/* XXX: Let's find a way to make this more efficient */
1127	while (nbytes) {
1128		thislen = xdr->buf->page_len % PAGE_SIZE;
1129		thislen = min_t(size_t, nbytes, PAGE_SIZE - thislen);
1130
1131		p = xdr_reserve_space(xdr, thislen);
1132		if (!p)
1133			return -EMSGSIZE;
1134
1135		nbytes -= thislen;
1136	}
1137
1138	return 0;
1139}
1140EXPORT_SYMBOL_GPL(xdr_reserve_space_vec);
1141
1142/**
1143 * xdr_truncate_encode - truncate an encode buffer
1144 * @xdr: pointer to xdr_stream
1145 * @len: new length of buffer
1146 *
1147 * Truncates the xdr stream, so that xdr->buf->len == len,
1148 * and xdr->p points at offset len from the start of the buffer, and
1149 * head, tail, and page lengths are adjusted to correspond.
1150 *
1151 * If this means moving xdr->p to a different buffer, we assume that
1152 * the end pointer should be set to the end of the current page,
1153 * except in the case of the head buffer when we assume the head
1154 * buffer's current length represents the end of the available buffer.
1155 *
1156 * This is *not* safe to use on a buffer that already has inlined page
1157 * cache pages (as in a zero-copy server read reply), except for the
1158 * simple case of truncating from one position in the tail to another.
1159 *
1160 */
1161void xdr_truncate_encode(struct xdr_stream *xdr, size_t len)
1162{
1163	struct xdr_buf *buf = xdr->buf;
1164	struct kvec *head = buf->head;
1165	struct kvec *tail = buf->tail;
1166	int fraglen;
1167	int new;
1168
1169	if (len > buf->len) {
1170		WARN_ON_ONCE(1);
1171		return;
1172	}
1173	xdr_commit_encode(xdr);
1174
1175	fraglen = min_t(int, buf->len - len, tail->iov_len);
1176	tail->iov_len -= fraglen;
1177	buf->len -= fraglen;
1178	if (tail->iov_len) {
1179		xdr->p = tail->iov_base + tail->iov_len;
1180		WARN_ON_ONCE(!xdr->end);
1181		WARN_ON_ONCE(!xdr->iov);
1182		return;
1183	}
1184	WARN_ON_ONCE(fraglen);
1185	fraglen = min_t(int, buf->len - len, buf->page_len);
1186	buf->page_len -= fraglen;
1187	buf->len -= fraglen;
1188
1189	new = buf->page_base + buf->page_len;
1190
1191	xdr->page_ptr = buf->pages + (new >> PAGE_SHIFT);
1192
1193	if (buf->page_len) {
1194		xdr->p = page_address(*xdr->page_ptr);
1195		xdr->end = (void *)xdr->p + PAGE_SIZE;
1196		xdr->p = (void *)xdr->p + (new % PAGE_SIZE);
1197		WARN_ON_ONCE(xdr->iov);
1198		return;
1199	}
1200	if (fraglen)
1201		xdr->end = head->iov_base + head->iov_len;
1202	/* (otherwise assume xdr->end is already set) */
1203	xdr->page_ptr--;
1204	head->iov_len = len;
1205	buf->len = len;
1206	xdr->p = head->iov_base + head->iov_len;
1207	xdr->iov = buf->head;
1208}
1209EXPORT_SYMBOL(xdr_truncate_encode);
1210
1211/**
1212 * xdr_truncate_decode - Truncate a decoding stream
1213 * @xdr: pointer to struct xdr_stream
1214 * @len: Number of bytes to remove
1215 *
1216 */
1217void xdr_truncate_decode(struct xdr_stream *xdr, size_t len)
1218{
1219	unsigned int nbytes = xdr_align_size(len);
1220
1221	xdr->buf->len -= nbytes;
1222	xdr->nwords -= XDR_QUADLEN(nbytes);
1223}
1224EXPORT_SYMBOL_GPL(xdr_truncate_decode);
1225
1226/**
1227 * xdr_restrict_buflen - decrease available buffer space
1228 * @xdr: pointer to xdr_stream
1229 * @newbuflen: new maximum number of bytes available
1230 *
1231 * Adjust our idea of how much space is available in the buffer.
1232 * If we've already used too much space in the buffer, returns -1.
1233 * If the available space is already smaller than newbuflen, returns 0
1234 * and does nothing.  Otherwise, adjusts xdr->buf->buflen to newbuflen
1235 * and ensures xdr->end is set at most offset newbuflen from the start
1236 * of the buffer.
1237 */
1238int xdr_restrict_buflen(struct xdr_stream *xdr, int newbuflen)
1239{
1240	struct xdr_buf *buf = xdr->buf;
1241	int left_in_this_buf = (void *)xdr->end - (void *)xdr->p;
1242	int end_offset = buf->len + left_in_this_buf;
1243
1244	if (newbuflen < 0 || newbuflen < buf->len)
1245		return -1;
1246	if (newbuflen > buf->buflen)
1247		return 0;
1248	if (newbuflen < end_offset)
1249		xdr->end = (void *)xdr->end + newbuflen - end_offset;
1250	buf->buflen = newbuflen;
1251	return 0;
1252}
1253EXPORT_SYMBOL(xdr_restrict_buflen);
1254
1255/**
1256 * xdr_write_pages - Insert a list of pages into an XDR buffer for sending
1257 * @xdr: pointer to xdr_stream
1258 * @pages: array of pages to insert
1259 * @base: starting offset of first data byte in @pages
1260 * @len: number of data bytes in @pages to insert
1261 *
1262 * After the @pages are added, the tail iovec is instantiated pointing to
1263 * end of the head buffer, and the stream is set up to encode subsequent
1264 * items into the tail.
1265 */
1266void xdr_write_pages(struct xdr_stream *xdr, struct page **pages, unsigned int base,
1267		 unsigned int len)
1268{
1269	struct xdr_buf *buf = xdr->buf;
1270	struct kvec *tail = buf->tail;
1271
1272	buf->pages = pages;
1273	buf->page_base = base;
1274	buf->page_len = len;
1275
1276	tail->iov_base = xdr->p;
1277	tail->iov_len = 0;
1278	xdr->iov = tail;
1279
1280	if (len & 3) {
1281		unsigned int pad = 4 - (len & 3);
1282
1283		BUG_ON(xdr->p >= xdr->end);
1284		tail->iov_base = (char *)xdr->p + (len & 3);
1285		tail->iov_len += pad;
1286		len += pad;
1287		*xdr->p++ = 0;
1288	}
1289	buf->buflen += len;
1290	buf->len += len;
1291}
1292EXPORT_SYMBOL_GPL(xdr_write_pages);
1293
1294static unsigned int xdr_set_iov(struct xdr_stream *xdr, struct kvec *iov,
1295				unsigned int base, unsigned int len)
1296{
1297	if (len > iov->iov_len)
1298		len = iov->iov_len;
1299	if (unlikely(base > len))
1300		base = len;
1301	xdr->p = (__be32*)(iov->iov_base + base);
1302	xdr->end = (__be32*)(iov->iov_base + len);
1303	xdr->iov = iov;
1304	xdr->page_ptr = NULL;
1305	return len - base;
1306}
1307
1308static unsigned int xdr_set_tail_base(struct xdr_stream *xdr,
1309				      unsigned int base, unsigned int len)
1310{
1311	struct xdr_buf *buf = xdr->buf;
1312
1313	xdr_stream_set_pos(xdr, base + buf->page_len + buf->head->iov_len);
1314	return xdr_set_iov(xdr, buf->tail, base, len);
1315}
1316
1317static void xdr_stream_unmap_current_page(struct xdr_stream *xdr)
1318{
1319	if (xdr->page_kaddr) {
1320		kunmap_local(xdr->page_kaddr);
1321		xdr->page_kaddr = NULL;
1322	}
1323}
1324
1325static unsigned int xdr_set_page_base(struct xdr_stream *xdr,
1326				      unsigned int base, unsigned int len)
1327{
1328	unsigned int pgnr;
1329	unsigned int maxlen;
1330	unsigned int pgoff;
1331	unsigned int pgend;
1332	void *kaddr;
1333
1334	maxlen = xdr->buf->page_len;
1335	if (base >= maxlen)
1336		return 0;
1337	else
1338		maxlen -= base;
1339	if (len > maxlen)
1340		len = maxlen;
1341
1342	xdr_stream_unmap_current_page(xdr);
1343	xdr_stream_page_set_pos(xdr, base);
1344	base += xdr->buf->page_base;
1345
1346	pgnr = base >> PAGE_SHIFT;
1347	xdr->page_ptr = &xdr->buf->pages[pgnr];
1348
1349	if (PageHighMem(*xdr->page_ptr)) {
1350		xdr->page_kaddr = kmap_local_page(*xdr->page_ptr);
1351		kaddr = xdr->page_kaddr;
1352	} else
1353		kaddr = page_address(*xdr->page_ptr);
1354
1355	pgoff = base & ~PAGE_MASK;
1356	xdr->p = (__be32*)(kaddr + pgoff);
1357
1358	pgend = pgoff + len;
1359	if (pgend > PAGE_SIZE)
1360		pgend = PAGE_SIZE;
1361	xdr->end = (__be32*)(kaddr + pgend);
1362	xdr->iov = NULL;
1363	return len;
1364}
1365
1366static void xdr_set_page(struct xdr_stream *xdr, unsigned int base,
1367			 unsigned int len)
1368{
1369	if (xdr_set_page_base(xdr, base, len) == 0) {
1370		base -= xdr->buf->page_len;
1371		xdr_set_tail_base(xdr, base, len);
1372	}
1373}
1374
1375static void xdr_set_next_page(struct xdr_stream *xdr)
1376{
1377	unsigned int newbase;
1378
1379	newbase = (1 + xdr->page_ptr - xdr->buf->pages) << PAGE_SHIFT;
1380	newbase -= xdr->buf->page_base;
1381	if (newbase < xdr->buf->page_len)
1382		xdr_set_page_base(xdr, newbase, xdr_stream_remaining(xdr));
1383	else
1384		xdr_set_tail_base(xdr, 0, xdr_stream_remaining(xdr));
1385}
1386
1387static bool xdr_set_next_buffer(struct xdr_stream *xdr)
1388{
1389	if (xdr->page_ptr != NULL)
1390		xdr_set_next_page(xdr);
1391	else if (xdr->iov == xdr->buf->head)
1392		xdr_set_page(xdr, 0, xdr_stream_remaining(xdr));
1393	return xdr->p != xdr->end;
1394}
1395
1396/**
1397 * xdr_init_decode - Initialize an xdr_stream for decoding data.
1398 * @xdr: pointer to xdr_stream struct
1399 * @buf: pointer to XDR buffer from which to decode data
1400 * @p: current pointer inside XDR buffer
1401 * @rqst: pointer to controlling rpc_rqst, for debugging
1402 */
1403void xdr_init_decode(struct xdr_stream *xdr, struct xdr_buf *buf, __be32 *p,
1404		     struct rpc_rqst *rqst)
1405{
1406	xdr->buf = buf;
1407	xdr->page_kaddr = NULL;
1408	xdr_reset_scratch_buffer(xdr);
1409	xdr->nwords = XDR_QUADLEN(buf->len);
1410	if (xdr_set_iov(xdr, buf->head, 0, buf->len) == 0 &&
1411	    xdr_set_page_base(xdr, 0, buf->len) == 0)
1412		xdr_set_iov(xdr, buf->tail, 0, buf->len);
1413	if (p != NULL && p > xdr->p && xdr->end >= p) {
1414		xdr->nwords -= p - xdr->p;
1415		xdr->p = p;
1416	}
1417	xdr->rqst = rqst;
1418}
1419EXPORT_SYMBOL_GPL(xdr_init_decode);
1420
1421/**
1422 * xdr_init_decode_pages - Initialize an xdr_stream for decoding into pages
1423 * @xdr: pointer to xdr_stream struct
1424 * @buf: pointer to XDR buffer from which to decode data
1425 * @pages: list of pages to decode into
1426 * @len: length in bytes of buffer in pages
1427 */
1428void xdr_init_decode_pages(struct xdr_stream *xdr, struct xdr_buf *buf,
1429			   struct page **pages, unsigned int len)
1430{
1431	memset(buf, 0, sizeof(*buf));
1432	buf->pages =  pages;
1433	buf->page_len =  len;
1434	buf->buflen =  len;
1435	buf->len = len;
1436	xdr_init_decode(xdr, buf, NULL, NULL);
1437}
1438EXPORT_SYMBOL_GPL(xdr_init_decode_pages);
1439
1440/**
1441 * xdr_finish_decode - Clean up the xdr_stream after decoding data.
1442 * @xdr: pointer to xdr_stream struct
1443 */
1444void xdr_finish_decode(struct xdr_stream *xdr)
1445{
1446	xdr_stream_unmap_current_page(xdr);
1447}
1448EXPORT_SYMBOL(xdr_finish_decode);
1449
1450static __be32 * __xdr_inline_decode(struct xdr_stream *xdr, size_t nbytes)
1451{
1452	unsigned int nwords = XDR_QUADLEN(nbytes);
1453	__be32 *p = xdr->p;
1454	__be32 *q = p + nwords;
1455
1456	if (unlikely(nwords > xdr->nwords || q > xdr->end || q < p))
1457		return NULL;
1458	xdr->p = q;
1459	xdr->nwords -= nwords;
1460	return p;
1461}
1462
1463static __be32 *xdr_copy_to_scratch(struct xdr_stream *xdr, size_t nbytes)
1464{
1465	__be32 *p;
1466	char *cpdest = xdr->scratch.iov_base;
1467	size_t cplen = (char *)xdr->end - (char *)xdr->p;
1468
1469	if (nbytes > xdr->scratch.iov_len)
1470		goto out_overflow;
1471	p = __xdr_inline_decode(xdr, cplen);
1472	if (p == NULL)
1473		return NULL;
1474	memcpy(cpdest, p, cplen);
1475	if (!xdr_set_next_buffer(xdr))
1476		goto out_overflow;
1477	cpdest += cplen;
1478	nbytes -= cplen;
1479	p = __xdr_inline_decode(xdr, nbytes);
1480	if (p == NULL)
1481		return NULL;
1482	memcpy(cpdest, p, nbytes);
1483	return xdr->scratch.iov_base;
1484out_overflow:
1485	trace_rpc_xdr_overflow(xdr, nbytes);
1486	return NULL;
1487}
1488
1489/**
1490 * xdr_inline_decode - Retrieve XDR data to decode
1491 * @xdr: pointer to xdr_stream struct
1492 * @nbytes: number of bytes of data to decode
1493 *
1494 * Check if the input buffer is long enough to enable us to decode
1495 * 'nbytes' more bytes of data starting at the current position.
1496 * If so return the current pointer, then update the current
1497 * pointer position.
1498 */
1499__be32 * xdr_inline_decode(struct xdr_stream *xdr, size_t nbytes)
1500{
1501	__be32 *p;
1502
1503	if (unlikely(nbytes == 0))
1504		return xdr->p;
1505	if (xdr->p == xdr->end && !xdr_set_next_buffer(xdr))
1506		goto out_overflow;
1507	p = __xdr_inline_decode(xdr, nbytes);
1508	if (p != NULL)
1509		return p;
1510	return xdr_copy_to_scratch(xdr, nbytes);
1511out_overflow:
1512	trace_rpc_xdr_overflow(xdr, nbytes);
1513	return NULL;
1514}
1515EXPORT_SYMBOL_GPL(xdr_inline_decode);
1516
1517static void xdr_realign_pages(struct xdr_stream *xdr)
1518{
1519	struct xdr_buf *buf = xdr->buf;
1520	struct kvec *iov = buf->head;
1521	unsigned int cur = xdr_stream_pos(xdr);
1522	unsigned int copied;
1523
1524	/* Realign pages to current pointer position */
1525	if (iov->iov_len > cur) {
1526		copied = xdr_shrink_bufhead(buf, cur);
1527		trace_rpc_xdr_alignment(xdr, cur, copied);
1528		xdr_set_page(xdr, 0, buf->page_len);
1529	}
1530}
1531
1532static unsigned int xdr_align_pages(struct xdr_stream *xdr, unsigned int len)
1533{
1534	struct xdr_buf *buf = xdr->buf;
1535	unsigned int nwords = XDR_QUADLEN(len);
1536	unsigned int copied;
1537
1538	if (xdr->nwords == 0)
1539		return 0;
1540
1541	xdr_realign_pages(xdr);
1542	if (nwords > xdr->nwords) {
1543		nwords = xdr->nwords;
1544		len = nwords << 2;
1545	}
1546	if (buf->page_len <= len)
1547		len = buf->page_len;
1548	else if (nwords < xdr->nwords) {
1549		/* Truncate page data and move it into the tail */
1550		copied = xdr_shrink_pagelen(buf, len);
1551		trace_rpc_xdr_alignment(xdr, len, copied);
1552	}
1553	return len;
1554}
1555
1556/**
1557 * xdr_read_pages - align page-based XDR data to current pointer position
1558 * @xdr: pointer to xdr_stream struct
1559 * @len: number of bytes of page data
1560 *
1561 * Moves data beyond the current pointer position from the XDR head[] buffer
1562 * into the page list. Any data that lies beyond current position + @len
1563 * bytes is moved into the XDR tail[]. The xdr_stream current position is
1564 * then advanced past that data to align to the next XDR object in the tail.
1565 *
1566 * Returns the number of XDR encoded bytes now contained in the pages
1567 */
1568unsigned int xdr_read_pages(struct xdr_stream *xdr, unsigned int len)
1569{
1570	unsigned int nwords = XDR_QUADLEN(len);
1571	unsigned int base, end, pglen;
1572
1573	pglen = xdr_align_pages(xdr, nwords << 2);
1574	if (pglen == 0)
1575		return 0;
1576
1577	base = (nwords << 2) - pglen;
1578	end = xdr_stream_remaining(xdr) - pglen;
1579
1580	xdr_set_tail_base(xdr, base, end);
1581	return len <= pglen ? len : pglen;
1582}
1583EXPORT_SYMBOL_GPL(xdr_read_pages);
1584
1585/**
1586 * xdr_set_pagelen - Sets the length of the XDR pages
1587 * @xdr: pointer to xdr_stream struct
1588 * @len: new length of the XDR page data
1589 *
1590 * Either grows or shrinks the length of the xdr pages by setting pagelen to
1591 * @len bytes. When shrinking, any extra data is moved into buf->tail, whereas
1592 * when growing any data beyond the current pointer is moved into the tail.
1593 *
1594 * Returns True if the operation was successful, and False otherwise.
1595 */
1596void xdr_set_pagelen(struct xdr_stream *xdr, unsigned int len)
1597{
1598	struct xdr_buf *buf = xdr->buf;
1599	size_t remaining = xdr_stream_remaining(xdr);
1600	size_t base = 0;
1601
1602	if (len < buf->page_len) {
1603		base = buf->page_len - len;
1604		xdr_shrink_pagelen(buf, len);
1605	} else {
1606		xdr_buf_head_shift_right(buf, xdr_stream_pos(xdr),
1607					 buf->page_len, remaining);
1608		if (len > buf->page_len)
1609			xdr_buf_try_expand(buf, len - buf->page_len);
1610	}
1611	xdr_set_tail_base(xdr, base, remaining);
1612}
1613EXPORT_SYMBOL_GPL(xdr_set_pagelen);
1614
1615/**
1616 * xdr_enter_page - decode data from the XDR page
1617 * @xdr: pointer to xdr_stream struct
1618 * @len: number of bytes of page data
1619 *
1620 * Moves data beyond the current pointer position from the XDR head[] buffer
1621 * into the page list. Any data that lies beyond current position + "len"
1622 * bytes is moved into the XDR tail[]. The current pointer is then
1623 * repositioned at the beginning of the first XDR page.
1624 */
1625void xdr_enter_page(struct xdr_stream *xdr, unsigned int len)
1626{
1627	len = xdr_align_pages(xdr, len);
1628	/*
1629	 * Position current pointer at beginning of tail, and
1630	 * set remaining message length.
1631	 */
1632	if (len != 0)
1633		xdr_set_page_base(xdr, 0, len);
1634}
1635EXPORT_SYMBOL_GPL(xdr_enter_page);
1636
1637static const struct kvec empty_iov = {.iov_base = NULL, .iov_len = 0};
1638
1639void xdr_buf_from_iov(const struct kvec *iov, struct xdr_buf *buf)
1640{
1641	buf->head[0] = *iov;
1642	buf->tail[0] = empty_iov;
1643	buf->page_len = 0;
1644	buf->buflen = buf->len = iov->iov_len;
1645}
1646EXPORT_SYMBOL_GPL(xdr_buf_from_iov);
1647
1648/**
1649 * xdr_buf_subsegment - set subbuf to a portion of buf
1650 * @buf: an xdr buffer
1651 * @subbuf: the result buffer
1652 * @base: beginning of range in bytes
1653 * @len: length of range in bytes
1654 *
1655 * sets @subbuf to an xdr buffer representing the portion of @buf of
1656 * length @len starting at offset @base.
1657 *
1658 * @buf and @subbuf may be pointers to the same struct xdr_buf.
1659 *
1660 * Returns -1 if base or length are out of bounds.
1661 */
1662int xdr_buf_subsegment(const struct xdr_buf *buf, struct xdr_buf *subbuf,
1663		       unsigned int base, unsigned int len)
1664{
1665	subbuf->buflen = subbuf->len = len;
1666	if (base < buf->head[0].iov_len) {
1667		subbuf->head[0].iov_base = buf->head[0].iov_base + base;
1668		subbuf->head[0].iov_len = min_t(unsigned int, len,
1669						buf->head[0].iov_len - base);
1670		len -= subbuf->head[0].iov_len;
1671		base = 0;
1672	} else {
1673		base -= buf->head[0].iov_len;
1674		subbuf->head[0].iov_base = buf->head[0].iov_base;
1675		subbuf->head[0].iov_len = 0;
1676	}
1677
1678	if (base < buf->page_len) {
1679		subbuf->page_len = min(buf->page_len - base, len);
1680		base += buf->page_base;
1681		subbuf->page_base = base & ~PAGE_MASK;
1682		subbuf->pages = &buf->pages[base >> PAGE_SHIFT];
1683		len -= subbuf->page_len;
1684		base = 0;
1685	} else {
1686		base -= buf->page_len;
1687		subbuf->pages = buf->pages;
1688		subbuf->page_base = 0;
1689		subbuf->page_len = 0;
1690	}
1691
1692	if (base < buf->tail[0].iov_len) {
1693		subbuf->tail[0].iov_base = buf->tail[0].iov_base + base;
1694		subbuf->tail[0].iov_len = min_t(unsigned int, len,
1695						buf->tail[0].iov_len - base);
1696		len -= subbuf->tail[0].iov_len;
1697		base = 0;
1698	} else {
1699		base -= buf->tail[0].iov_len;
1700		subbuf->tail[0].iov_base = buf->tail[0].iov_base;
1701		subbuf->tail[0].iov_len = 0;
1702	}
1703
1704	if (base || len)
1705		return -1;
1706	return 0;
1707}
1708EXPORT_SYMBOL_GPL(xdr_buf_subsegment);
1709
1710/**
1711 * xdr_stream_subsegment - set @subbuf to a portion of @xdr
1712 * @xdr: an xdr_stream set up for decoding
1713 * @subbuf: the result buffer
1714 * @nbytes: length of @xdr to extract, in bytes
1715 *
1716 * Sets up @subbuf to represent a portion of @xdr. The portion
1717 * starts at the current offset in @xdr, and extends for a length
1718 * of @nbytes. If this is successful, @xdr is advanced to the next
1719 * XDR data item following that portion.
1720 *
1721 * Return values:
1722 *   %true: @subbuf has been initialized, and @xdr has been advanced.
1723 *   %false: a bounds error has occurred
1724 */
1725bool xdr_stream_subsegment(struct xdr_stream *xdr, struct xdr_buf *subbuf,
1726			   unsigned int nbytes)
1727{
1728	unsigned int start = xdr_stream_pos(xdr);
1729	unsigned int remaining, len;
1730
1731	/* Extract @subbuf and bounds-check the fn arguments */
1732	if (xdr_buf_subsegment(xdr->buf, subbuf, start, nbytes))
1733		return false;
1734
1735	/* Advance @xdr by @nbytes */
1736	for (remaining = nbytes; remaining;) {
1737		if (xdr->p == xdr->end && !xdr_set_next_buffer(xdr))
1738			return false;
1739
1740		len = (char *)xdr->end - (char *)xdr->p;
1741		if (remaining <= len) {
1742			xdr->p = (__be32 *)((char *)xdr->p +
1743					(remaining + xdr_pad_size(nbytes)));
1744			break;
1745		}
1746
1747		xdr->p = (__be32 *)((char *)xdr->p + len);
1748		xdr->end = xdr->p;
1749		remaining -= len;
1750	}
1751
1752	xdr_stream_set_pos(xdr, start + nbytes);
1753	return true;
1754}
1755EXPORT_SYMBOL_GPL(xdr_stream_subsegment);
1756
1757/**
1758 * xdr_stream_move_subsegment - Move part of a stream to another position
1759 * @xdr: the source xdr_stream
1760 * @offset: the source offset of the segment
1761 * @target: the target offset of the segment
1762 * @length: the number of bytes to move
1763 *
1764 * Moves @length bytes from @offset to @target in the xdr_stream, overwriting
1765 * anything in its space. Returns the number of bytes in the segment.
1766 */
1767unsigned int xdr_stream_move_subsegment(struct xdr_stream *xdr, unsigned int offset,
1768					unsigned int target, unsigned int length)
1769{
1770	struct xdr_buf buf;
1771	unsigned int shift;
1772
1773	if (offset < target) {
1774		shift = target - offset;
1775		if (xdr_buf_subsegment(xdr->buf, &buf, offset, shift + length) < 0)
1776			return 0;
1777		xdr_buf_head_shift_right(&buf, 0, length, shift);
1778	} else if (offset > target) {
1779		shift = offset - target;
1780		if (xdr_buf_subsegment(xdr->buf, &buf, target, shift + length) < 0)
1781			return 0;
1782		xdr_buf_head_shift_left(&buf, shift, length, shift);
1783	}
1784	return length;
1785}
1786EXPORT_SYMBOL_GPL(xdr_stream_move_subsegment);
1787
1788/**
1789 * xdr_stream_zero - zero out a portion of an xdr_stream
1790 * @xdr: an xdr_stream to zero out
1791 * @offset: the starting point in the stream
1792 * @length: the number of bytes to zero
1793 */
1794unsigned int xdr_stream_zero(struct xdr_stream *xdr, unsigned int offset,
1795			     unsigned int length)
1796{
1797	struct xdr_buf buf;
1798
1799	if (xdr_buf_subsegment(xdr->buf, &buf, offset, length) < 0)
1800		return 0;
1801	if (buf.head[0].iov_len)
1802		xdr_buf_iov_zero(buf.head, 0, buf.head[0].iov_len);
1803	if (buf.page_len > 0)
1804		xdr_buf_pages_zero(&buf, 0, buf.page_len);
1805	if (buf.tail[0].iov_len)
1806		xdr_buf_iov_zero(buf.tail, 0, buf.tail[0].iov_len);
1807	return length;
1808}
1809EXPORT_SYMBOL_GPL(xdr_stream_zero);
1810
1811/**
1812 * xdr_buf_trim - lop at most "len" bytes off the end of "buf"
1813 * @buf: buf to be trimmed
1814 * @len: number of bytes to reduce "buf" by
1815 *
1816 * Trim an xdr_buf by the given number of bytes by fixing up the lengths. Note
1817 * that it's possible that we'll trim less than that amount if the xdr_buf is
1818 * too small, or if (for instance) it's all in the head and the parser has
1819 * already read too far into it.
1820 */
1821void xdr_buf_trim(struct xdr_buf *buf, unsigned int len)
1822{
1823	size_t cur;
1824	unsigned int trim = len;
1825
1826	if (buf->tail[0].iov_len) {
1827		cur = min_t(size_t, buf->tail[0].iov_len, trim);
1828		buf->tail[0].iov_len -= cur;
1829		trim -= cur;
1830		if (!trim)
1831			goto fix_len;
1832	}
1833
1834	if (buf->page_len) {
1835		cur = min_t(unsigned int, buf->page_len, trim);
1836		buf->page_len -= cur;
1837		trim -= cur;
1838		if (!trim)
1839			goto fix_len;
1840	}
1841
1842	if (buf->head[0].iov_len) {
1843		cur = min_t(size_t, buf->head[0].iov_len, trim);
1844		buf->head[0].iov_len -= cur;
1845		trim -= cur;
1846	}
1847fix_len:
1848	buf->len -= (len - trim);
1849}
1850EXPORT_SYMBOL_GPL(xdr_buf_trim);
1851
1852static void __read_bytes_from_xdr_buf(const struct xdr_buf *subbuf,
1853				      void *obj, unsigned int len)
1854{
1855	unsigned int this_len;
1856
1857	this_len = min_t(unsigned int, len, subbuf->head[0].iov_len);
1858	memcpy(obj, subbuf->head[0].iov_base, this_len);
1859	len -= this_len;
1860	obj += this_len;
1861	this_len = min_t(unsigned int, len, subbuf->page_len);
1862	_copy_from_pages(obj, subbuf->pages, subbuf->page_base, this_len);
1863	len -= this_len;
1864	obj += this_len;
1865	this_len = min_t(unsigned int, len, subbuf->tail[0].iov_len);
1866	memcpy(obj, subbuf->tail[0].iov_base, this_len);
1867}
1868
1869/* obj is assumed to point to allocated memory of size at least len: */
1870int read_bytes_from_xdr_buf(const struct xdr_buf *buf, unsigned int base,
1871			    void *obj, unsigned int len)
1872{
1873	struct xdr_buf subbuf;
1874	int status;
1875
1876	status = xdr_buf_subsegment(buf, &subbuf, base, len);
1877	if (status != 0)
1878		return status;
1879	__read_bytes_from_xdr_buf(&subbuf, obj, len);
1880	return 0;
1881}
1882EXPORT_SYMBOL_GPL(read_bytes_from_xdr_buf);
1883
1884static void __write_bytes_to_xdr_buf(const struct xdr_buf *subbuf,
1885				     void *obj, unsigned int len)
1886{
1887	unsigned int this_len;
1888
1889	this_len = min_t(unsigned int, len, subbuf->head[0].iov_len);
1890	memcpy(subbuf->head[0].iov_base, obj, this_len);
1891	len -= this_len;
1892	obj += this_len;
1893	this_len = min_t(unsigned int, len, subbuf->page_len);
1894	_copy_to_pages(subbuf->pages, subbuf->page_base, obj, this_len);
1895	len -= this_len;
1896	obj += this_len;
1897	this_len = min_t(unsigned int, len, subbuf->tail[0].iov_len);
1898	memcpy(subbuf->tail[0].iov_base, obj, this_len);
1899}
1900
1901/* obj is assumed to point to allocated memory of size at least len: */
1902int write_bytes_to_xdr_buf(const struct xdr_buf *buf, unsigned int base,
1903			   void *obj, unsigned int len)
1904{
1905	struct xdr_buf subbuf;
1906	int status;
1907
1908	status = xdr_buf_subsegment(buf, &subbuf, base, len);
1909	if (status != 0)
1910		return status;
1911	__write_bytes_to_xdr_buf(&subbuf, obj, len);
1912	return 0;
1913}
1914EXPORT_SYMBOL_GPL(write_bytes_to_xdr_buf);
1915
1916int xdr_decode_word(const struct xdr_buf *buf, unsigned int base, u32 *obj)
1917{
1918	__be32	raw;
1919	int	status;
1920
1921	status = read_bytes_from_xdr_buf(buf, base, &raw, sizeof(*obj));
1922	if (status)
1923		return status;
1924	*obj = be32_to_cpu(raw);
1925	return 0;
1926}
1927EXPORT_SYMBOL_GPL(xdr_decode_word);
1928
1929int xdr_encode_word(const struct xdr_buf *buf, unsigned int base, u32 obj)
1930{
1931	__be32	raw = cpu_to_be32(obj);
1932
1933	return write_bytes_to_xdr_buf(buf, base, &raw, sizeof(obj));
1934}
1935EXPORT_SYMBOL_GPL(xdr_encode_word);
1936
1937/* Returns 0 on success, or else a negative error code. */
1938static int xdr_xcode_array2(const struct xdr_buf *buf, unsigned int base,
1939			    struct xdr_array2_desc *desc, int encode)
1940{
1941	char *elem = NULL, *c;
1942	unsigned int copied = 0, todo, avail_here;
1943	struct page **ppages = NULL;
1944	int err;
1945
1946	if (encode) {
1947		if (xdr_encode_word(buf, base, desc->array_len) != 0)
1948			return -EINVAL;
1949	} else {
1950		if (xdr_decode_word(buf, base, &desc->array_len) != 0 ||
1951		    desc->array_len > desc->array_maxlen ||
1952		    (unsigned long) base + 4 + desc->array_len *
1953				    desc->elem_size > buf->len)
1954			return -EINVAL;
1955	}
1956	base += 4;
1957
1958	if (!desc->xcode)
1959		return 0;
1960
1961	todo = desc->array_len * desc->elem_size;
1962
1963	/* process head */
1964	if (todo && base < buf->head->iov_len) {
1965		c = buf->head->iov_base + base;
1966		avail_here = min_t(unsigned int, todo,
1967				   buf->head->iov_len - base);
1968		todo -= avail_here;
1969
1970		while (avail_here >= desc->elem_size) {
1971			err = desc->xcode(desc, c);
1972			if (err)
1973				goto out;
1974			c += desc->elem_size;
1975			avail_here -= desc->elem_size;
1976		}
1977		if (avail_here) {
1978			if (!elem) {
1979				elem = kmalloc(desc->elem_size, GFP_KERNEL);
1980				err = -ENOMEM;
1981				if (!elem)
1982					goto out;
1983			}
1984			if (encode) {
1985				err = desc->xcode(desc, elem);
1986				if (err)
1987					goto out;
1988				memcpy(c, elem, avail_here);
1989			} else
1990				memcpy(elem, c, avail_here);
1991			copied = avail_here;
1992		}
1993		base = buf->head->iov_len;  /* align to start of pages */
1994	}
1995
1996	/* process pages array */
1997	base -= buf->head->iov_len;
1998	if (todo && base < buf->page_len) {
1999		unsigned int avail_page;
2000
2001		avail_here = min(todo, buf->page_len - base);
2002		todo -= avail_here;
2003
2004		base += buf->page_base;
2005		ppages = buf->pages + (base >> PAGE_SHIFT);
2006		base &= ~PAGE_MASK;
2007		avail_page = min_t(unsigned int, PAGE_SIZE - base,
2008					avail_here);
2009		c = kmap(*ppages) + base;
2010
2011		while (avail_here) {
2012			avail_here -= avail_page;
2013			if (copied || avail_page < desc->elem_size) {
2014				unsigned int l = min(avail_page,
2015					desc->elem_size - copied);
2016				if (!elem) {
2017					elem = kmalloc(desc->elem_size,
2018						       GFP_KERNEL);
2019					err = -ENOMEM;
2020					if (!elem)
2021						goto out;
2022				}
2023				if (encode) {
2024					if (!copied) {
2025						err = desc->xcode(desc, elem);
2026						if (err)
2027							goto out;
2028					}
2029					memcpy(c, elem + copied, l);
2030					copied += l;
2031					if (copied == desc->elem_size)
2032						copied = 0;
2033				} else {
2034					memcpy(elem + copied, c, l);
2035					copied += l;
2036					if (copied == desc->elem_size) {
2037						err = desc->xcode(desc, elem);
2038						if (err)
2039							goto out;
2040						copied = 0;
2041					}
2042				}
2043				avail_page -= l;
2044				c += l;
2045			}
2046			while (avail_page >= desc->elem_size) {
2047				err = desc->xcode(desc, c);
2048				if (err)
2049					goto out;
2050				c += desc->elem_size;
2051				avail_page -= desc->elem_size;
2052			}
2053			if (avail_page) {
2054				unsigned int l = min(avail_page,
2055					    desc->elem_size - copied);
2056				if (!elem) {
2057					elem = kmalloc(desc->elem_size,
2058						       GFP_KERNEL);
2059					err = -ENOMEM;
2060					if (!elem)
2061						goto out;
2062				}
2063				if (encode) {
2064					if (!copied) {
2065						err = desc->xcode(desc, elem);
2066						if (err)
2067							goto out;
2068					}
2069					memcpy(c, elem + copied, l);
2070					copied += l;
2071					if (copied == desc->elem_size)
2072						copied = 0;
2073				} else {
2074					memcpy(elem + copied, c, l);
2075					copied += l;
2076					if (copied == desc->elem_size) {
2077						err = desc->xcode(desc, elem);
2078						if (err)
2079							goto out;
2080						copied = 0;
2081					}
2082				}
2083			}
2084			if (avail_here) {
2085				kunmap(*ppages);
2086				ppages++;
2087				c = kmap(*ppages);
2088			}
2089
2090			avail_page = min(avail_here,
2091				 (unsigned int) PAGE_SIZE);
2092		}
2093		base = buf->page_len;  /* align to start of tail */
2094	}
2095
2096	/* process tail */
2097	base -= buf->page_len;
2098	if (todo) {
2099		c = buf->tail->iov_base + base;
2100		if (copied) {
2101			unsigned int l = desc->elem_size - copied;
2102
2103			if (encode)
2104				memcpy(c, elem + copied, l);
2105			else {
2106				memcpy(elem + copied, c, l);
2107				err = desc->xcode(desc, elem);
2108				if (err)
2109					goto out;
2110			}
2111			todo -= l;
2112			c += l;
2113		}
2114		while (todo) {
2115			err = desc->xcode(desc, c);
2116			if (err)
2117				goto out;
2118			c += desc->elem_size;
2119			todo -= desc->elem_size;
2120		}
2121	}
2122	err = 0;
2123
2124out:
2125	kfree(elem);
2126	if (ppages)
2127		kunmap(*ppages);
2128	return err;
2129}
2130
2131int xdr_decode_array2(const struct xdr_buf *buf, unsigned int base,
2132		      struct xdr_array2_desc *desc)
2133{
2134	if (base >= buf->len)
2135		return -EINVAL;
2136
2137	return xdr_xcode_array2(buf, base, desc, 0);
2138}
2139EXPORT_SYMBOL_GPL(xdr_decode_array2);
2140
2141int xdr_encode_array2(const struct xdr_buf *buf, unsigned int base,
2142		      struct xdr_array2_desc *desc)
2143{
2144	if ((unsigned long) base + 4 + desc->array_len * desc->elem_size >
2145	    buf->head->iov_len + buf->page_len + buf->tail->iov_len)
2146		return -EINVAL;
2147
2148	return xdr_xcode_array2(buf, base, desc, 1);
2149}
2150EXPORT_SYMBOL_GPL(xdr_encode_array2);
2151
2152int xdr_process_buf(const struct xdr_buf *buf, unsigned int offset,
2153		    unsigned int len,
2154		    int (*actor)(struct scatterlist *, void *), void *data)
2155{
2156	int i, ret = 0;
2157	unsigned int page_len, thislen, page_offset;
2158	struct scatterlist      sg[1];
2159
2160	sg_init_table(sg, 1);
2161
2162	if (offset >= buf->head[0].iov_len) {
2163		offset -= buf->head[0].iov_len;
2164	} else {
2165		thislen = buf->head[0].iov_len - offset;
2166		if (thislen > len)
2167			thislen = len;
2168		sg_set_buf(sg, buf->head[0].iov_base + offset, thislen);
2169		ret = actor(sg, data);
2170		if (ret)
2171			goto out;
2172		offset = 0;
2173		len -= thislen;
2174	}
2175	if (len == 0)
2176		goto out;
2177
2178	if (offset >= buf->page_len) {
2179		offset -= buf->page_len;
2180	} else {
2181		page_len = buf->page_len - offset;
2182		if (page_len > len)
2183			page_len = len;
2184		len -= page_len;
2185		page_offset = (offset + buf->page_base) & (PAGE_SIZE - 1);
2186		i = (offset + buf->page_base) >> PAGE_SHIFT;
2187		thislen = PAGE_SIZE - page_offset;
2188		do {
2189			if (thislen > page_len)
2190				thislen = page_len;
2191			sg_set_page(sg, buf->pages[i], thislen, page_offset);
2192			ret = actor(sg, data);
2193			if (ret)
2194				goto out;
2195			page_len -= thislen;
2196			i++;
2197			page_offset = 0;
2198			thislen = PAGE_SIZE;
2199		} while (page_len != 0);
2200		offset = 0;
2201	}
2202	if (len == 0)
2203		goto out;
2204	if (offset < buf->tail[0].iov_len) {
2205		thislen = buf->tail[0].iov_len - offset;
2206		if (thislen > len)
2207			thislen = len;
2208		sg_set_buf(sg, buf->tail[0].iov_base + offset, thislen);
2209		ret = actor(sg, data);
2210		len -= thislen;
2211	}
2212	if (len != 0)
2213		ret = -EINVAL;
2214out:
2215	return ret;
2216}
2217EXPORT_SYMBOL_GPL(xdr_process_buf);
2218
2219/**
2220 * xdr_stream_decode_string_dup - Decode and duplicate variable length string
2221 * @xdr: pointer to xdr_stream
2222 * @str: location to store pointer to string
2223 * @maxlen: maximum acceptable string length
2224 * @gfp_flags: GFP mask to use
2225 *
2226 * Return values:
2227 *   On success, returns length of NUL-terminated string stored in *@ptr
2228 *   %-EBADMSG on XDR buffer overflow
2229 *   %-EMSGSIZE if the size of the string would exceed @maxlen
2230 *   %-ENOMEM on memory allocation failure
2231 */
2232ssize_t xdr_stream_decode_string_dup(struct xdr_stream *xdr, char **str,
2233		size_t maxlen, gfp_t gfp_flags)
2234{
2235	void *p;
2236	ssize_t ret;
2237
2238	ret = xdr_stream_decode_opaque_inline(xdr, &p, maxlen);
2239	if (ret > 0) {
2240		char *s = kmemdup_nul(p, ret, gfp_flags);
2241		if (s != NULL) {
2242			*str = s;
2243			return strlen(s);
2244		}
2245		ret = -ENOMEM;
2246	}
2247	*str = NULL;
2248	return ret;
2249}
2250EXPORT_SYMBOL_GPL(xdr_stream_decode_string_dup);
2251
2252/**
2253 * xdr_stream_decode_opaque_auth - Decode struct opaque_auth (RFC5531 S8.2)
2254 * @xdr: pointer to xdr_stream
2255 * @flavor: location to store decoded flavor
2256 * @body: location to store decode body
2257 * @body_len: location to store length of decoded body
2258 *
2259 * Return values:
2260 *   On success, returns the number of buffer bytes consumed
2261 *   %-EBADMSG on XDR buffer overflow
2262 *   %-EMSGSIZE if the decoded size of the body field exceeds 400 octets
2263 */
2264ssize_t xdr_stream_decode_opaque_auth(struct xdr_stream *xdr, u32 *flavor,
2265				      void **body, unsigned int *body_len)
2266{
2267	ssize_t ret, len;
2268
2269	len = xdr_stream_decode_u32(xdr, flavor);
2270	if (unlikely(len < 0))
2271		return len;
2272	ret = xdr_stream_decode_opaque_inline(xdr, body, RPC_MAX_AUTH_SIZE);
2273	if (unlikely(ret < 0))
2274		return ret;
2275	*body_len = ret;
2276	return len + ret;
2277}
2278EXPORT_SYMBOL_GPL(xdr_stream_decode_opaque_auth);
2279
2280/**
2281 * xdr_stream_encode_opaque_auth - Encode struct opaque_auth (RFC5531 S8.2)
2282 * @xdr: pointer to xdr_stream
2283 * @flavor: verifier flavor to encode
2284 * @body: content of body to encode
2285 * @body_len: length of body to encode
2286 *
2287 * Return values:
2288 *   On success, returns length in bytes of XDR buffer consumed
2289 *   %-EBADMSG on XDR buffer overflow
2290 *   %-EMSGSIZE if the size of @body exceeds 400 octets
2291 */
2292ssize_t xdr_stream_encode_opaque_auth(struct xdr_stream *xdr, u32 flavor,
2293				      void *body, unsigned int body_len)
2294{
2295	ssize_t ret, len;
2296
2297	if (unlikely(body_len > RPC_MAX_AUTH_SIZE))
2298		return -EMSGSIZE;
2299	len = xdr_stream_encode_u32(xdr, flavor);
2300	if (unlikely(len < 0))
2301		return len;
2302	ret = xdr_stream_encode_opaque(xdr, body, body_len);
2303	if (unlikely(ret < 0))
2304		return ret;
2305	return len + ret;
2306}
2307EXPORT_SYMBOL_GPL(xdr_stream_encode_opaque_auth);