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
  22/*
  23 * XDR functions for basic NFS types
  24 */
  25__be32 *
  26xdr_encode_netobj(__be32 *p, const struct xdr_netobj *obj)
  27{
  28	unsigned int	quadlen = XDR_QUADLEN(obj->len);
  29
  30	p[quadlen] = 0;		/* zero trailing bytes */
  31	*p++ = cpu_to_be32(obj->len);
  32	memcpy(p, obj->data, obj->len);
  33	return p + XDR_QUADLEN(obj->len);
  34}
  35EXPORT_SYMBOL_GPL(xdr_encode_netobj);
  36
  37__be32 *
  38xdr_decode_netobj(__be32 *p, struct xdr_netobj *obj)
  39{
  40	unsigned int	len;
  41
  42	if ((len = be32_to_cpu(*p++)) > XDR_MAX_NETOBJ)
  43		return NULL;
  44	obj->len  = len;
  45	obj->data = (u8 *) p;
  46	return p + XDR_QUADLEN(len);
  47}
  48EXPORT_SYMBOL_GPL(xdr_decode_netobj);
  49
  50/**
  51 * xdr_encode_opaque_fixed - Encode fixed length opaque data
  52 * @p: pointer to current position in XDR buffer.
  53 * @ptr: pointer to data to encode (or NULL)
  54 * @nbytes: size of data.
  55 *
  56 * Copy the array of data of length nbytes at ptr to the XDR buffer
  57 * at position p, then align to the next 32-bit boundary by padding
  58 * with zero bytes (see RFC1832).
  59 * Note: if ptr is NULL, only the padding is performed.
  60 *
  61 * Returns the updated current XDR buffer position
  62 *
  63 */
  64__be32 *xdr_encode_opaque_fixed(__be32 *p, const void *ptr, unsigned int nbytes)
  65{
  66	if (likely(nbytes != 0)) {
  67		unsigned int quadlen = XDR_QUADLEN(nbytes);
  68		unsigned int padding = (quadlen << 2) - nbytes;
  69
  70		if (ptr != NULL)
  71			memcpy(p, ptr, nbytes);
  72		if (padding != 0)
  73			memset((char *)p + nbytes, 0, padding);
  74		p += quadlen;
  75	}
  76	return p;
  77}
  78EXPORT_SYMBOL_GPL(xdr_encode_opaque_fixed);
  79
  80/**
  81 * xdr_encode_opaque - Encode variable length opaque data
  82 * @p: pointer to current position in XDR buffer.
  83 * @ptr: pointer to data to encode (or NULL)
  84 * @nbytes: size of data.
  85 *
  86 * Returns the updated current XDR buffer position
  87 */
  88__be32 *xdr_encode_opaque(__be32 *p, const void *ptr, unsigned int nbytes)
  89{
  90	*p++ = cpu_to_be32(nbytes);
  91	return xdr_encode_opaque_fixed(p, ptr, nbytes);
  92}
  93EXPORT_SYMBOL_GPL(xdr_encode_opaque);
  94
  95__be32 *
  96xdr_encode_string(__be32 *p, const char *string)
  97{
  98	return xdr_encode_array(p, string, strlen(string));
  99}
 100EXPORT_SYMBOL_GPL(xdr_encode_string);
 101
 102__be32 *
 103xdr_decode_string_inplace(__be32 *p, char **sp,
 104			  unsigned int *lenp, unsigned int maxlen)
 105{
 106	u32 len;
 107
 108	len = be32_to_cpu(*p++);
 109	if (len > maxlen)
 110		return NULL;
 111	*lenp = len;
 112	*sp = (char *) p;
 113	return p + XDR_QUADLEN(len);
 114}
 115EXPORT_SYMBOL_GPL(xdr_decode_string_inplace);
 116
 117/**
 118 * xdr_terminate_string - '\0'-terminate a string residing in an xdr_buf
 119 * @buf: XDR buffer where string resides
 120 * @len: length of string, in bytes
 121 *
 122 */
 123void
 124xdr_terminate_string(struct xdr_buf *buf, const u32 len)
 125{
 126	char *kaddr;
 127
 128	kaddr = kmap_atomic(buf->pages[0]);
 129	kaddr[buf->page_base + len] = '\0';
 130	kunmap_atomic(kaddr);
 131}
 132EXPORT_SYMBOL_GPL(xdr_terminate_string);
 133
 134size_t
 135xdr_buf_pagecount(struct xdr_buf *buf)
 136{
 137	if (!buf->page_len)
 138		return 0;
 139	return (buf->page_base + buf->page_len + PAGE_SIZE - 1) >> PAGE_SHIFT;
 140}
 141
 142int
 143xdr_alloc_bvec(struct xdr_buf *buf, gfp_t gfp)
 144{
 145	size_t i, n = xdr_buf_pagecount(buf);
 146
 147	if (n != 0 && buf->bvec == NULL) {
 148		buf->bvec = kmalloc_array(n, sizeof(buf->bvec[0]), gfp);
 149		if (!buf->bvec)
 150			return -ENOMEM;
 151		for (i = 0; i < n; i++) {
 152			buf->bvec[i].bv_page = buf->pages[i];
 153			buf->bvec[i].bv_len = PAGE_SIZE;
 154			buf->bvec[i].bv_offset = 0;
 155		}
 156	}
 157	return 0;
 158}
 159
 160void
 161xdr_free_bvec(struct xdr_buf *buf)
 162{
 163	kfree(buf->bvec);
 164	buf->bvec = NULL;
 165}
 166
 167/**
 168 * xdr_inline_pages - Prepare receive buffer for a large reply
 169 * @xdr: xdr_buf into which reply will be placed
 170 * @offset: expected offset where data payload will start, in bytes
 171 * @pages: vector of struct page pointers
 172 * @base: offset in first page where receive should start, in bytes
 173 * @len: expected size of the upper layer data payload, in bytes
 174 *
 175 */
 176void
 177xdr_inline_pages(struct xdr_buf *xdr, unsigned int offset,
 178		 struct page **pages, unsigned int base, unsigned int len)
 179{
 180	struct kvec *head = xdr->head;
 181	struct kvec *tail = xdr->tail;
 182	char *buf = (char *)head->iov_base;
 183	unsigned int buflen = head->iov_len;
 184
 185	head->iov_len  = offset;
 186
 187	xdr->pages = pages;
 188	xdr->page_base = base;
 189	xdr->page_len = len;
 190
 191	tail->iov_base = buf + offset;
 192	tail->iov_len = buflen - offset;
 193	if ((xdr->page_len & 3) == 0)
 194		tail->iov_len -= sizeof(__be32);
 195
 196	xdr->buflen += len;
 197}
 198EXPORT_SYMBOL_GPL(xdr_inline_pages);
 199
 200/*
 201 * Helper routines for doing 'memmove' like operations on a struct xdr_buf
 202 */
 203
 204/**
 205 * _shift_data_right_pages
 206 * @pages: vector of pages containing both the source and dest memory area.
 207 * @pgto_base: page vector address of destination
 208 * @pgfrom_base: page vector address of source
 209 * @len: number of bytes to copy
 210 *
 211 * Note: the addresses pgto_base and pgfrom_base are both calculated in
 212 *       the same way:
 213 *            if a memory area starts at byte 'base' in page 'pages[i]',
 214 *            then its address is given as (i << PAGE_SHIFT) + base
 215 * Also note: pgfrom_base must be < pgto_base, but the memory areas
 216 * 	they point to may overlap.
 217 */
 218static void
 219_shift_data_right_pages(struct page **pages, size_t pgto_base,
 220		size_t pgfrom_base, size_t len)
 221{
 222	struct page **pgfrom, **pgto;
 223	char *vfrom, *vto;
 224	size_t copy;
 225
 226	BUG_ON(pgto_base <= pgfrom_base);
 227
 228	pgto_base += len;
 229	pgfrom_base += len;
 230
 231	pgto = pages + (pgto_base >> PAGE_SHIFT);
 232	pgfrom = pages + (pgfrom_base >> PAGE_SHIFT);
 233
 234	pgto_base &= ~PAGE_MASK;
 235	pgfrom_base &= ~PAGE_MASK;
 236
 237	do {
 238		/* Are any pointers crossing a page boundary? */
 239		if (pgto_base == 0) {
 240			pgto_base = PAGE_SIZE;
 241			pgto--;
 242		}
 243		if (pgfrom_base == 0) {
 244			pgfrom_base = PAGE_SIZE;
 245			pgfrom--;
 246		}
 247
 248		copy = len;
 249		if (copy > pgto_base)
 250			copy = pgto_base;
 251		if (copy > pgfrom_base)
 252			copy = pgfrom_base;
 253		pgto_base -= copy;
 254		pgfrom_base -= copy;
 255
 256		vto = kmap_atomic(*pgto);
 257		if (*pgto != *pgfrom) {
 258			vfrom = kmap_atomic(*pgfrom);
 259			memcpy(vto + pgto_base, vfrom + pgfrom_base, copy);
 260			kunmap_atomic(vfrom);
 261		} else
 262			memmove(vto + pgto_base, vto + pgfrom_base, copy);
 263		flush_dcache_page(*pgto);
 264		kunmap_atomic(vto);
 265
 266	} while ((len -= copy) != 0);
 267}
 268
 269/**
 270 * _copy_to_pages
 271 * @pages: array of pages
 272 * @pgbase: page vector address of destination
 273 * @p: pointer to source data
 274 * @len: length
 275 *
 276 * Copies data from an arbitrary memory location into an array of pages
 277 * The copy is assumed to be non-overlapping.
 278 */
 279static void
 280_copy_to_pages(struct page **pages, size_t pgbase, const char *p, size_t len)
 281{
 282	struct page **pgto;
 283	char *vto;
 284	size_t copy;
 285
 286	pgto = pages + (pgbase >> PAGE_SHIFT);
 287	pgbase &= ~PAGE_MASK;
 288
 289	for (;;) {
 290		copy = PAGE_SIZE - pgbase;
 291		if (copy > len)
 292			copy = len;
 293
 294		vto = kmap_atomic(*pgto);
 295		memcpy(vto + pgbase, p, copy);
 296		kunmap_atomic(vto);
 297
 298		len -= copy;
 299		if (len == 0)
 300			break;
 301
 302		pgbase += copy;
 303		if (pgbase == PAGE_SIZE) {
 304			flush_dcache_page(*pgto);
 305			pgbase = 0;
 306			pgto++;
 307		}
 308		p += copy;
 309	}
 310	flush_dcache_page(*pgto);
 311}
 312
 313/**
 314 * _copy_from_pages
 315 * @p: pointer to destination
 316 * @pages: array of pages
 317 * @pgbase: offset of source data
 318 * @len: length
 319 *
 320 * Copies data into an arbitrary memory location from an array of pages
 321 * The copy is assumed to be non-overlapping.
 322 */
 323void
 324_copy_from_pages(char *p, struct page **pages, size_t pgbase, size_t len)
 325{
 326	struct page **pgfrom;
 327	char *vfrom;
 328	size_t copy;
 329
 330	pgfrom = pages + (pgbase >> PAGE_SHIFT);
 331	pgbase &= ~PAGE_MASK;
 332
 333	do {
 334		copy = PAGE_SIZE - pgbase;
 335		if (copy > len)
 336			copy = len;
 337
 338		vfrom = kmap_atomic(*pgfrom);
 339		memcpy(p, vfrom + pgbase, copy);
 340		kunmap_atomic(vfrom);
 341
 342		pgbase += copy;
 343		if (pgbase == PAGE_SIZE) {
 344			pgbase = 0;
 345			pgfrom++;
 346		}
 347		p += copy;
 348
 349	} while ((len -= copy) != 0);
 350}
 351EXPORT_SYMBOL_GPL(_copy_from_pages);
 352
 353/**
 354 * xdr_shrink_bufhead
 355 * @buf: xdr_buf
 356 * @len: bytes to remove from buf->head[0]
 357 *
 358 * Shrinks XDR buffer's header kvec buf->head[0] by
 359 * 'len' bytes. The extra data is not lost, but is instead
 360 * moved into the inlined pages and/or the tail.
 361 */
 362static unsigned int
 363xdr_shrink_bufhead(struct xdr_buf *buf, size_t len)
 364{
 365	struct kvec *head, *tail;
 366	size_t copy, offs;
 367	unsigned int pglen = buf->page_len;
 368	unsigned int result;
 369
 370	result = 0;
 371	tail = buf->tail;
 372	head = buf->head;
 373
 374	WARN_ON_ONCE(len > head->iov_len);
 375	if (len > head->iov_len)
 376		len = head->iov_len;
 377
 378	/* Shift the tail first */
 379	if (tail->iov_len != 0) {
 380		if (tail->iov_len > len) {
 381			copy = tail->iov_len - len;
 382			memmove((char *)tail->iov_base + len,
 383					tail->iov_base, copy);
 384			result += copy;
 385		}
 386		/* Copy from the inlined pages into the tail */
 387		copy = len;
 388		if (copy > pglen)
 389			copy = pglen;
 390		offs = len - copy;
 391		if (offs >= tail->iov_len)
 392			copy = 0;
 393		else if (copy > tail->iov_len - offs)
 394			copy = tail->iov_len - offs;
 395		if (copy != 0) {
 396			_copy_from_pages((char *)tail->iov_base + offs,
 397					buf->pages,
 398					buf->page_base + pglen + offs - len,
 399					copy);
 400			result += copy;
 401		}
 402		/* Do we also need to copy data from the head into the tail ? */
 403		if (len > pglen) {
 404			offs = copy = len - pglen;
 405			if (copy > tail->iov_len)
 406				copy = tail->iov_len;
 407			memcpy(tail->iov_base,
 408					(char *)head->iov_base +
 409					head->iov_len - offs,
 410					copy);
 411			result += copy;
 412		}
 413	}
 414	/* Now handle pages */
 415	if (pglen != 0) {
 416		if (pglen > len)
 417			_shift_data_right_pages(buf->pages,
 418					buf->page_base + len,
 419					buf->page_base,
 420					pglen - len);
 421		copy = len;
 422		if (len > pglen)
 423			copy = pglen;
 424		_copy_to_pages(buf->pages, buf->page_base,
 425				(char *)head->iov_base + head->iov_len - len,
 426				copy);
 427		result += copy;
 428	}
 429	head->iov_len -= len;
 430	buf->buflen -= len;
 431	/* Have we truncated the message? */
 432	if (buf->len > buf->buflen)
 433		buf->len = buf->buflen;
 434
 435	return result;
 436}
 437
 438/**
 439 * xdr_shrink_pagelen - shrinks buf->pages by up to @len bytes
 440 * @buf: xdr_buf
 441 * @len: bytes to remove from buf->pages
 442 *
 443 * The extra data is not lost, but is instead moved into buf->tail.
 444 * Returns the actual number of bytes moved.
 
 445 */
 446static unsigned int
 447xdr_shrink_pagelen(struct xdr_buf *buf, size_t len)
 448{
 449	struct kvec *tail;
 450	size_t copy;
 451	unsigned int pglen = buf->page_len;
 452	unsigned int tailbuf_len;
 453	unsigned int result;
 454
 455	result = 0;
 456	tail = buf->tail;
 457	if (len > buf->page_len)
 458		len = buf-> page_len;
 459	tailbuf_len = buf->buflen - buf->head->iov_len - buf->page_len;
 460
 461	/* Shift the tail first */
 462	if (tailbuf_len != 0) {
 463		unsigned int free_space = tailbuf_len - tail->iov_len;
 464
 465		if (len < free_space)
 466			free_space = len;
 467		tail->iov_len += free_space;
 468
 469		copy = len;
 470		if (tail->iov_len > len) {
 471			char *p = (char *)tail->iov_base + len;
 472			memmove(p, tail->iov_base, tail->iov_len - len);
 473			result += tail->iov_len - len;
 474		} else
 475			copy = tail->iov_len;
 476		/* Copy from the inlined pages into the tail */
 477		_copy_from_pages((char *)tail->iov_base,
 478				buf->pages, buf->page_base + pglen - len,
 479				copy);
 480		result += copy;
 481	}
 482	buf->page_len -= len;
 483	buf->buflen -= len;
 484	/* Have we truncated the message? */
 485	if (buf->len > buf->buflen)
 486		buf->len = buf->buflen;
 487
 488	return result;
 489}
 490
 491void
 492xdr_shift_buf(struct xdr_buf *buf, size_t len)
 493{
 494	xdr_shrink_bufhead(buf, len);
 495}
 496EXPORT_SYMBOL_GPL(xdr_shift_buf);
 497
 498/**
 499 * xdr_stream_pos - Return the current offset from the start of the xdr_stream
 500 * @xdr: pointer to struct xdr_stream
 501 */
 502unsigned int xdr_stream_pos(const struct xdr_stream *xdr)
 503{
 504	return (unsigned int)(XDR_QUADLEN(xdr->buf->len) - xdr->nwords) << 2;
 505}
 506EXPORT_SYMBOL_GPL(xdr_stream_pos);
 507
 508/**
 509 * xdr_init_encode - Initialize a struct xdr_stream for sending data.
 510 * @xdr: pointer to xdr_stream struct
 511 * @buf: pointer to XDR buffer in which to encode data
 512 * @p: current pointer inside XDR buffer
 513 * @rqst: pointer to controlling rpc_rqst, for debugging
 514 *
 515 * Note: at the moment the RPC client only passes the length of our
 516 *	 scratch buffer in the xdr_buf's header kvec. Previously this
 517 *	 meant we needed to call xdr_adjust_iovec() after encoding the
 518 *	 data. With the new scheme, the xdr_stream manages the details
 519 *	 of the buffer length, and takes care of adjusting the kvec
 520 *	 length for us.
 521 */
 522void xdr_init_encode(struct xdr_stream *xdr, struct xdr_buf *buf, __be32 *p,
 523		     struct rpc_rqst *rqst)
 524{
 525	struct kvec *iov = buf->head;
 526	int scratch_len = buf->buflen - buf->page_len - buf->tail[0].iov_len;
 527
 528	xdr_set_scratch_buffer(xdr, NULL, 0);
 529	BUG_ON(scratch_len < 0);
 530	xdr->buf = buf;
 531	xdr->iov = iov;
 532	xdr->p = (__be32 *)((char *)iov->iov_base + iov->iov_len);
 533	xdr->end = (__be32 *)((char *)iov->iov_base + scratch_len);
 534	BUG_ON(iov->iov_len > scratch_len);
 535
 536	if (p != xdr->p && p != NULL) {
 537		size_t len;
 538
 539		BUG_ON(p < xdr->p || p > xdr->end);
 540		len = (char *)p - (char *)xdr->p;
 541		xdr->p = p;
 542		buf->len += len;
 543		iov->iov_len += len;
 544	}
 545	xdr->rqst = rqst;
 546}
 547EXPORT_SYMBOL_GPL(xdr_init_encode);
 548
 549/**
 550 * xdr_commit_encode - Ensure all data is written to buffer
 551 * @xdr: pointer to xdr_stream
 552 *
 553 * We handle encoding across page boundaries by giving the caller a
 554 * temporary location to write to, then later copying the data into
 555 * place; xdr_commit_encode does that copying.
 556 *
 557 * Normally the caller doesn't need to call this directly, as the
 558 * following xdr_reserve_space will do it.  But an explicit call may be
 559 * required at the end of encoding, or any other time when the xdr_buf
 560 * data might be read.
 561 */
 562inline void xdr_commit_encode(struct xdr_stream *xdr)
 563{
 564	int shift = xdr->scratch.iov_len;
 565	void *page;
 566
 567	if (shift == 0)
 568		return;
 569	page = page_address(*xdr->page_ptr);
 570	memcpy(xdr->scratch.iov_base, page, shift);
 571	memmove(page, page + shift, (void *)xdr->p - page);
 572	xdr->scratch.iov_len = 0;
 573}
 574EXPORT_SYMBOL_GPL(xdr_commit_encode);
 575
 576static __be32 *xdr_get_next_encode_buffer(struct xdr_stream *xdr,
 577		size_t nbytes)
 578{
 579	__be32 *p;
 580	int space_left;
 581	int frag1bytes, frag2bytes;
 582
 583	if (nbytes > PAGE_SIZE)
 584		goto out_overflow; /* Bigger buffers require special handling */
 585	if (xdr->buf->len + nbytes > xdr->buf->buflen)
 586		goto out_overflow; /* Sorry, we're totally out of space */
 587	frag1bytes = (xdr->end - xdr->p) << 2;
 588	frag2bytes = nbytes - frag1bytes;
 589	if (xdr->iov)
 590		xdr->iov->iov_len += frag1bytes;
 591	else
 592		xdr->buf->page_len += frag1bytes;
 593	xdr->page_ptr++;
 594	xdr->iov = NULL;
 595	/*
 596	 * If the last encode didn't end exactly on a page boundary, the
 597	 * next one will straddle boundaries.  Encode into the next
 598	 * page, then copy it back later in xdr_commit_encode.  We use
 599	 * the "scratch" iov to track any temporarily unused fragment of
 600	 * space at the end of the previous buffer:
 601	 */
 602	xdr->scratch.iov_base = xdr->p;
 603	xdr->scratch.iov_len = frag1bytes;
 604	p = page_address(*xdr->page_ptr);
 605	/*
 606	 * Note this is where the next encode will start after we've
 607	 * shifted this one back:
 608	 */
 609	xdr->p = (void *)p + frag2bytes;
 610	space_left = xdr->buf->buflen - xdr->buf->len;
 611	xdr->end = (void *)p + min_t(int, space_left, PAGE_SIZE);
 612	xdr->buf->page_len += frag2bytes;
 613	xdr->buf->len += nbytes;
 614	return p;
 615out_overflow:
 616	trace_rpc_xdr_overflow(xdr, nbytes);
 617	return NULL;
 618}
 619
 620/**
 621 * xdr_reserve_space - Reserve buffer space for sending
 622 * @xdr: pointer to xdr_stream
 623 * @nbytes: number of bytes to reserve
 624 *
 625 * Checks that we have enough buffer space to encode 'nbytes' more
 626 * bytes of data. If so, update the total xdr_buf length, and
 627 * adjust the length of the current kvec.
 628 */
 629__be32 * xdr_reserve_space(struct xdr_stream *xdr, size_t nbytes)
 630{
 631	__be32 *p = xdr->p;
 632	__be32 *q;
 633
 634	xdr_commit_encode(xdr);
 635	/* align nbytes on the next 32-bit boundary */
 636	nbytes += 3;
 637	nbytes &= ~3;
 638	q = p + (nbytes >> 2);
 639	if (unlikely(q > xdr->end || q < p))
 640		return xdr_get_next_encode_buffer(xdr, nbytes);
 641	xdr->p = q;
 642	if (xdr->iov)
 643		xdr->iov->iov_len += nbytes;
 644	else
 645		xdr->buf->page_len += nbytes;
 646	xdr->buf->len += nbytes;
 647	return p;
 648}
 649EXPORT_SYMBOL_GPL(xdr_reserve_space);
 650
 651/**
 652 * xdr_truncate_encode - truncate an encode buffer
 653 * @xdr: pointer to xdr_stream
 654 * @len: new length of buffer
 655 *
 656 * Truncates the xdr stream, so that xdr->buf->len == len,
 657 * and xdr->p points at offset len from the start of the buffer, and
 658 * head, tail, and page lengths are adjusted to correspond.
 659 *
 660 * If this means moving xdr->p to a different buffer, we assume that
 661 * that the end pointer should be set to the end of the current page,
 662 * except in the case of the head buffer when we assume the head
 663 * buffer's current length represents the end of the available buffer.
 664 *
 665 * This is *not* safe to use on a buffer that already has inlined page
 666 * cache pages (as in a zero-copy server read reply), except for the
 667 * simple case of truncating from one position in the tail to another.
 668 *
 669 */
 670void xdr_truncate_encode(struct xdr_stream *xdr, size_t len)
 671{
 672	struct xdr_buf *buf = xdr->buf;
 673	struct kvec *head = buf->head;
 674	struct kvec *tail = buf->tail;
 675	int fraglen;
 676	int new;
 677
 678	if (len > buf->len) {
 679		WARN_ON_ONCE(1);
 680		return;
 681	}
 682	xdr_commit_encode(xdr);
 683
 684	fraglen = min_t(int, buf->len - len, tail->iov_len);
 685	tail->iov_len -= fraglen;
 686	buf->len -= fraglen;
 687	if (tail->iov_len) {
 688		xdr->p = tail->iov_base + tail->iov_len;
 689		WARN_ON_ONCE(!xdr->end);
 690		WARN_ON_ONCE(!xdr->iov);
 691		return;
 692	}
 693	WARN_ON_ONCE(fraglen);
 694	fraglen = min_t(int, buf->len - len, buf->page_len);
 695	buf->page_len -= fraglen;
 696	buf->len -= fraglen;
 697
 698	new = buf->page_base + buf->page_len;
 699
 700	xdr->page_ptr = buf->pages + (new >> PAGE_SHIFT);
 701
 702	if (buf->page_len) {
 703		xdr->p = page_address(*xdr->page_ptr);
 704		xdr->end = (void *)xdr->p + PAGE_SIZE;
 705		xdr->p = (void *)xdr->p + (new % PAGE_SIZE);
 706		WARN_ON_ONCE(xdr->iov);
 707		return;
 708	}
 709	if (fraglen)
 710		xdr->end = head->iov_base + head->iov_len;
 711	/* (otherwise assume xdr->end is already set) */
 712	xdr->page_ptr--;
 713	head->iov_len = len;
 714	buf->len = len;
 715	xdr->p = head->iov_base + head->iov_len;
 716	xdr->iov = buf->head;
 717}
 718EXPORT_SYMBOL(xdr_truncate_encode);
 719
 720/**
 721 * xdr_restrict_buflen - decrease available buffer space
 722 * @xdr: pointer to xdr_stream
 723 * @newbuflen: new maximum number of bytes available
 724 *
 725 * Adjust our idea of how much space is available in the buffer.
 726 * If we've already used too much space in the buffer, returns -1.
 727 * If the available space is already smaller than newbuflen, returns 0
 728 * and does nothing.  Otherwise, adjusts xdr->buf->buflen to newbuflen
 729 * and ensures xdr->end is set at most offset newbuflen from the start
 730 * of the buffer.
 731 */
 732int xdr_restrict_buflen(struct xdr_stream *xdr, int newbuflen)
 733{
 734	struct xdr_buf *buf = xdr->buf;
 735	int left_in_this_buf = (void *)xdr->end - (void *)xdr->p;
 736	int end_offset = buf->len + left_in_this_buf;
 737
 738	if (newbuflen < 0 || newbuflen < buf->len)
 739		return -1;
 740	if (newbuflen > buf->buflen)
 741		return 0;
 742	if (newbuflen < end_offset)
 743		xdr->end = (void *)xdr->end + newbuflen - end_offset;
 744	buf->buflen = newbuflen;
 745	return 0;
 746}
 747EXPORT_SYMBOL(xdr_restrict_buflen);
 748
 749/**
 750 * xdr_write_pages - Insert a list of pages into an XDR buffer for sending
 751 * @xdr: pointer to xdr_stream
 752 * @pages: list of pages
 753 * @base: offset of first byte
 754 * @len: length of data in bytes
 755 *
 756 */
 757void xdr_write_pages(struct xdr_stream *xdr, struct page **pages, unsigned int base,
 758		 unsigned int len)
 759{
 760	struct xdr_buf *buf = xdr->buf;
 761	struct kvec *iov = buf->tail;
 762	buf->pages = pages;
 763	buf->page_base = base;
 764	buf->page_len = len;
 765
 766	iov->iov_base = (char *)xdr->p;
 767	iov->iov_len  = 0;
 768	xdr->iov = iov;
 769
 770	if (len & 3) {
 771		unsigned int pad = 4 - (len & 3);
 772
 773		BUG_ON(xdr->p >= xdr->end);
 774		iov->iov_base = (char *)xdr->p + (len & 3);
 775		iov->iov_len  += pad;
 776		len += pad;
 777		*xdr->p++ = 0;
 778	}
 779	buf->buflen += len;
 780	buf->len += len;
 781}
 782EXPORT_SYMBOL_GPL(xdr_write_pages);
 783
 784static void xdr_set_iov(struct xdr_stream *xdr, struct kvec *iov,
 785		unsigned int len)
 786{
 787	if (len > iov->iov_len)
 788		len = iov->iov_len;
 789	xdr->p = (__be32*)iov->iov_base;
 790	xdr->end = (__be32*)(iov->iov_base + len);
 791	xdr->iov = iov;
 792	xdr->page_ptr = NULL;
 793}
 794
 795static int xdr_set_page_base(struct xdr_stream *xdr,
 796		unsigned int base, unsigned int len)
 797{
 798	unsigned int pgnr;
 799	unsigned int maxlen;
 800	unsigned int pgoff;
 801	unsigned int pgend;
 802	void *kaddr;
 803
 804	maxlen = xdr->buf->page_len;
 805	if (base >= maxlen)
 806		return -EINVAL;
 807	maxlen -= base;
 808	if (len > maxlen)
 809		len = maxlen;
 810
 811	base += xdr->buf->page_base;
 812
 813	pgnr = base >> PAGE_SHIFT;
 814	xdr->page_ptr = &xdr->buf->pages[pgnr];
 815	kaddr = page_address(*xdr->page_ptr);
 816
 817	pgoff = base & ~PAGE_MASK;
 818	xdr->p = (__be32*)(kaddr + pgoff);
 819
 820	pgend = pgoff + len;
 821	if (pgend > PAGE_SIZE)
 822		pgend = PAGE_SIZE;
 823	xdr->end = (__be32*)(kaddr + pgend);
 824	xdr->iov = NULL;
 825	return 0;
 826}
 827
 828static void xdr_set_next_page(struct xdr_stream *xdr)
 829{
 830	unsigned int newbase;
 831
 832	newbase = (1 + xdr->page_ptr - xdr->buf->pages) << PAGE_SHIFT;
 833	newbase -= xdr->buf->page_base;
 834
 835	if (xdr_set_page_base(xdr, newbase, PAGE_SIZE) < 0)
 836		xdr_set_iov(xdr, xdr->buf->tail, xdr->nwords << 2);
 837}
 838
 839static bool xdr_set_next_buffer(struct xdr_stream *xdr)
 840{
 841	if (xdr->page_ptr != NULL)
 842		xdr_set_next_page(xdr);
 843	else if (xdr->iov == xdr->buf->head) {
 844		if (xdr_set_page_base(xdr, 0, PAGE_SIZE) < 0)
 845			xdr_set_iov(xdr, xdr->buf->tail, xdr->nwords << 2);
 846	}
 847	return xdr->p != xdr->end;
 848}
 849
 850/**
 851 * xdr_init_decode - Initialize an xdr_stream for decoding data.
 852 * @xdr: pointer to xdr_stream struct
 853 * @buf: pointer to XDR buffer from which to decode data
 854 * @p: current pointer inside XDR buffer
 855 * @rqst: pointer to controlling rpc_rqst, for debugging
 856 */
 857void xdr_init_decode(struct xdr_stream *xdr, struct xdr_buf *buf, __be32 *p,
 858		     struct rpc_rqst *rqst)
 859{
 860	xdr->buf = buf;
 861	xdr->scratch.iov_base = NULL;
 862	xdr->scratch.iov_len = 0;
 863	xdr->nwords = XDR_QUADLEN(buf->len);
 864	if (buf->head[0].iov_len != 0)
 865		xdr_set_iov(xdr, buf->head, buf->len);
 866	else if (buf->page_len != 0)
 867		xdr_set_page_base(xdr, 0, buf->len);
 868	else
 869		xdr_set_iov(xdr, buf->head, buf->len);
 870	if (p != NULL && p > xdr->p && xdr->end >= p) {
 871		xdr->nwords -= p - xdr->p;
 872		xdr->p = p;
 873	}
 874	xdr->rqst = rqst;
 875}
 876EXPORT_SYMBOL_GPL(xdr_init_decode);
 877
 878/**
 879 * xdr_init_decode_pages - Initialize an xdr_stream for decoding into pages
 880 * @xdr: pointer to xdr_stream struct
 881 * @buf: pointer to XDR buffer from which to decode data
 882 * @pages: list of pages to decode into
 883 * @len: length in bytes of buffer in pages
 884 */
 885void xdr_init_decode_pages(struct xdr_stream *xdr, struct xdr_buf *buf,
 886			   struct page **pages, unsigned int len)
 887{
 888	memset(buf, 0, sizeof(*buf));
 889	buf->pages =  pages;
 890	buf->page_len =  len;
 891	buf->buflen =  len;
 892	buf->len = len;
 893	xdr_init_decode(xdr, buf, NULL, NULL);
 894}
 895EXPORT_SYMBOL_GPL(xdr_init_decode_pages);
 896
 897static __be32 * __xdr_inline_decode(struct xdr_stream *xdr, size_t nbytes)
 898{
 899	unsigned int nwords = XDR_QUADLEN(nbytes);
 900	__be32 *p = xdr->p;
 901	__be32 *q = p + nwords;
 902
 903	if (unlikely(nwords > xdr->nwords || q > xdr->end || q < p))
 904		return NULL;
 905	xdr->p = q;
 906	xdr->nwords -= nwords;
 907	return p;
 908}
 909
 910/**
 911 * xdr_set_scratch_buffer - Attach a scratch buffer for decoding data.
 912 * @xdr: pointer to xdr_stream struct
 913 * @buf: pointer to an empty buffer
 914 * @buflen: size of 'buf'
 915 *
 916 * The scratch buffer is used when decoding from an array of pages.
 917 * If an xdr_inline_decode() call spans across page boundaries, then
 918 * we copy the data into the scratch buffer in order to allow linear
 919 * access.
 920 */
 921void xdr_set_scratch_buffer(struct xdr_stream *xdr, void *buf, size_t buflen)
 922{
 923	xdr->scratch.iov_base = buf;
 924	xdr->scratch.iov_len = buflen;
 925}
 926EXPORT_SYMBOL_GPL(xdr_set_scratch_buffer);
 927
 928static __be32 *xdr_copy_to_scratch(struct xdr_stream *xdr, size_t nbytes)
 929{
 930	__be32 *p;
 931	char *cpdest = xdr->scratch.iov_base;
 932	size_t cplen = (char *)xdr->end - (char *)xdr->p;
 933
 934	if (nbytes > xdr->scratch.iov_len)
 935		goto out_overflow;
 936	p = __xdr_inline_decode(xdr, cplen);
 937	if (p == NULL)
 938		return NULL;
 939	memcpy(cpdest, p, cplen);
 940	if (!xdr_set_next_buffer(xdr))
 941		goto out_overflow;
 942	cpdest += cplen;
 943	nbytes -= cplen;
 944	p = __xdr_inline_decode(xdr, nbytes);
 945	if (p == NULL)
 946		return NULL;
 947	memcpy(cpdest, p, nbytes);
 948	return xdr->scratch.iov_base;
 949out_overflow:
 950	trace_rpc_xdr_overflow(xdr, nbytes);
 951	return NULL;
 952}
 953
 954/**
 955 * xdr_inline_decode - Retrieve XDR data to decode
 956 * @xdr: pointer to xdr_stream struct
 957 * @nbytes: number of bytes of data to decode
 958 *
 959 * Check if the input buffer is long enough to enable us to decode
 960 * 'nbytes' more bytes of data starting at the current position.
 961 * If so return the current pointer, then update the current
 962 * pointer position.
 963 */
 964__be32 * xdr_inline_decode(struct xdr_stream *xdr, size_t nbytes)
 965{
 966	__be32 *p;
 967
 968	if (unlikely(nbytes == 0))
 969		return xdr->p;
 970	if (xdr->p == xdr->end && !xdr_set_next_buffer(xdr))
 971		goto out_overflow;
 972	p = __xdr_inline_decode(xdr, nbytes);
 973	if (p != NULL)
 974		return p;
 975	return xdr_copy_to_scratch(xdr, nbytes);
 976out_overflow:
 977	trace_rpc_xdr_overflow(xdr, nbytes);
 978	return NULL;
 979}
 980EXPORT_SYMBOL_GPL(xdr_inline_decode);
 981
 982static unsigned int xdr_align_pages(struct xdr_stream *xdr, unsigned int len)
 983{
 984	struct xdr_buf *buf = xdr->buf;
 985	struct kvec *iov;
 986	unsigned int nwords = XDR_QUADLEN(len);
 987	unsigned int cur = xdr_stream_pos(xdr);
 988	unsigned int copied, offset;
 989
 990	if (xdr->nwords == 0)
 991		return 0;
 992
 993	/* Realign pages to current pointer position */
 994	iov = buf->head;
 995	if (iov->iov_len > cur) {
 996		offset = iov->iov_len - cur;
 997		copied = xdr_shrink_bufhead(buf, offset);
 998		trace_rpc_xdr_alignment(xdr, offset, copied);
 999		xdr->nwords = XDR_QUADLEN(buf->len - cur);
1000	}
1001
1002	if (nwords > xdr->nwords) {
1003		nwords = xdr->nwords;
1004		len = nwords << 2;
1005	}
1006	if (buf->page_len <= len)
1007		len = buf->page_len;
1008	else if (nwords < xdr->nwords) {
1009		/* Truncate page data and move it into the tail */
1010		offset = buf->page_len - len;
1011		copied = xdr_shrink_pagelen(buf, offset);
1012		trace_rpc_xdr_alignment(xdr, offset, copied);
1013		xdr->nwords = XDR_QUADLEN(buf->len - cur);
1014	}
1015	return len;
1016}
1017
1018/**
1019 * xdr_read_pages - Ensure page-based XDR data to decode is aligned at current pointer position
1020 * @xdr: pointer to xdr_stream struct
1021 * @len: number of bytes of page data
1022 *
1023 * Moves data beyond the current pointer position from the XDR head[] buffer
1024 * into the page list. Any data that lies beyond current position + "len"
1025 * bytes is moved into the XDR tail[].
1026 *
1027 * Returns the number of XDR encoded bytes now contained in the pages
1028 */
1029unsigned int xdr_read_pages(struct xdr_stream *xdr, unsigned int len)
1030{
1031	struct xdr_buf *buf = xdr->buf;
1032	struct kvec *iov;
1033	unsigned int nwords;
1034	unsigned int end;
1035	unsigned int padding;
1036
1037	len = xdr_align_pages(xdr, len);
1038	if (len == 0)
1039		return 0;
1040	nwords = XDR_QUADLEN(len);
1041	padding = (nwords << 2) - len;
1042	xdr->iov = iov = buf->tail;
1043	/* Compute remaining message length.  */
1044	end = ((xdr->nwords - nwords) << 2) + padding;
1045	if (end > iov->iov_len)
1046		end = iov->iov_len;
1047
1048	/*
1049	 * Position current pointer at beginning of tail, and
1050	 * set remaining message length.
1051	 */
1052	xdr->p = (__be32 *)((char *)iov->iov_base + padding);
1053	xdr->end = (__be32 *)((char *)iov->iov_base + end);
1054	xdr->page_ptr = NULL;
1055	xdr->nwords = XDR_QUADLEN(end - padding);
1056	return len;
1057}
1058EXPORT_SYMBOL_GPL(xdr_read_pages);
1059
1060/**
1061 * xdr_enter_page - decode data from the XDR page
1062 * @xdr: pointer to xdr_stream struct
1063 * @len: number of bytes of page data
1064 *
1065 * Moves data beyond the current pointer position from the XDR head[] buffer
1066 * into the page list. Any data that lies beyond current position + "len"
1067 * bytes is moved into the XDR tail[]. The current pointer is then
1068 * repositioned at the beginning of the first XDR page.
1069 */
1070void xdr_enter_page(struct xdr_stream *xdr, unsigned int len)
1071{
1072	len = xdr_align_pages(xdr, len);
1073	/*
1074	 * Position current pointer at beginning of tail, and
1075	 * set remaining message length.
1076	 */
1077	if (len != 0)
1078		xdr_set_page_base(xdr, 0, len);
1079}
1080EXPORT_SYMBOL_GPL(xdr_enter_page);
1081
1082static const struct kvec empty_iov = {.iov_base = NULL, .iov_len = 0};
1083
1084void
1085xdr_buf_from_iov(struct kvec *iov, struct xdr_buf *buf)
1086{
1087	buf->head[0] = *iov;
1088	buf->tail[0] = empty_iov;
1089	buf->page_len = 0;
1090	buf->buflen = buf->len = iov->iov_len;
1091}
1092EXPORT_SYMBOL_GPL(xdr_buf_from_iov);
1093
1094/**
1095 * xdr_buf_subsegment - set subbuf to a portion of buf
1096 * @buf: an xdr buffer
1097 * @subbuf: the result buffer
1098 * @base: beginning of range in bytes
1099 * @len: length of range in bytes
1100 *
1101 * sets @subbuf to an xdr buffer representing the portion of @buf of
1102 * length @len starting at offset @base.
1103 *
1104 * @buf and @subbuf may be pointers to the same struct xdr_buf.
1105 *
1106 * Returns -1 if base of length are out of bounds.
1107 */
1108int
1109xdr_buf_subsegment(struct xdr_buf *buf, struct xdr_buf *subbuf,
1110			unsigned int base, unsigned int len)
1111{
1112	subbuf->buflen = subbuf->len = len;
1113	if (base < buf->head[0].iov_len) {
1114		subbuf->head[0].iov_base = buf->head[0].iov_base + base;
1115		subbuf->head[0].iov_len = min_t(unsigned int, len,
1116						buf->head[0].iov_len - base);
1117		len -= subbuf->head[0].iov_len;
1118		base = 0;
1119	} else {
1120		base -= buf->head[0].iov_len;
1121		subbuf->head[0].iov_base = buf->head[0].iov_base;
1122		subbuf->head[0].iov_len = 0;
1123	}
1124
1125	if (base < buf->page_len) {
1126		subbuf->page_len = min(buf->page_len - base, len);
1127		base += buf->page_base;
1128		subbuf->page_base = base & ~PAGE_MASK;
1129		subbuf->pages = &buf->pages[base >> PAGE_SHIFT];
1130		len -= subbuf->page_len;
1131		base = 0;
1132	} else {
1133		base -= buf->page_len;
1134		subbuf->pages = buf->pages;
1135		subbuf->page_base = 0;
1136		subbuf->page_len = 0;
1137	}
1138
1139	if (base < buf->tail[0].iov_len) {
1140		subbuf->tail[0].iov_base = buf->tail[0].iov_base + base;
1141		subbuf->tail[0].iov_len = min_t(unsigned int, len,
1142						buf->tail[0].iov_len - base);
1143		len -= subbuf->tail[0].iov_len;
1144		base = 0;
1145	} else {
1146		base -= buf->tail[0].iov_len;
1147		subbuf->tail[0].iov_base = buf->tail[0].iov_base;
1148		subbuf->tail[0].iov_len = 0;
1149	}
1150
1151	if (base || len)
1152		return -1;
1153	return 0;
1154}
1155EXPORT_SYMBOL_GPL(xdr_buf_subsegment);
1156
1157/**
1158 * xdr_buf_trim - lop at most "len" bytes off the end of "buf"
1159 * @buf: buf to be trimmed
1160 * @len: number of bytes to reduce "buf" by
1161 *
1162 * Trim an xdr_buf by the given number of bytes by fixing up the lengths. Note
1163 * that it's possible that we'll trim less than that amount if the xdr_buf is
1164 * too small, or if (for instance) it's all in the head and the parser has
1165 * already read too far into it.
1166 */
1167void xdr_buf_trim(struct xdr_buf *buf, unsigned int len)
1168{
1169	size_t cur;
1170	unsigned int trim = len;
1171
1172	if (buf->tail[0].iov_len) {
1173		cur = min_t(size_t, buf->tail[0].iov_len, trim);
1174		buf->tail[0].iov_len -= cur;
1175		trim -= cur;
1176		if (!trim)
1177			goto fix_len;
1178	}
1179
1180	if (buf->page_len) {
1181		cur = min_t(unsigned int, buf->page_len, trim);
1182		buf->page_len -= cur;
1183		trim -= cur;
1184		if (!trim)
1185			goto fix_len;
1186	}
1187
1188	if (buf->head[0].iov_len) {
1189		cur = min_t(size_t, buf->head[0].iov_len, trim);
1190		buf->head[0].iov_len -= cur;
1191		trim -= cur;
1192	}
1193fix_len:
1194	buf->len -= (len - trim);
1195}
1196EXPORT_SYMBOL_GPL(xdr_buf_trim);
1197
1198static void __read_bytes_from_xdr_buf(struct xdr_buf *subbuf, void *obj, unsigned int len)
1199{
1200	unsigned int this_len;
1201
1202	this_len = min_t(unsigned int, len, subbuf->head[0].iov_len);
1203	memcpy(obj, subbuf->head[0].iov_base, this_len);
1204	len -= this_len;
1205	obj += this_len;
1206	this_len = min_t(unsigned int, len, subbuf->page_len);
1207	if (this_len)
1208		_copy_from_pages(obj, subbuf->pages, subbuf->page_base, this_len);
1209	len -= this_len;
1210	obj += this_len;
1211	this_len = min_t(unsigned int, len, subbuf->tail[0].iov_len);
1212	memcpy(obj, subbuf->tail[0].iov_base, this_len);
1213}
1214
1215/* obj is assumed to point to allocated memory of size at least len: */
1216int read_bytes_from_xdr_buf(struct xdr_buf *buf, unsigned int base, void *obj, unsigned int len)
1217{
1218	struct xdr_buf subbuf;
1219	int status;
1220
1221	status = xdr_buf_subsegment(buf, &subbuf, base, len);
1222	if (status != 0)
1223		return status;
1224	__read_bytes_from_xdr_buf(&subbuf, obj, len);
1225	return 0;
1226}
1227EXPORT_SYMBOL_GPL(read_bytes_from_xdr_buf);
1228
1229static void __write_bytes_to_xdr_buf(struct xdr_buf *subbuf, void *obj, unsigned int len)
1230{
1231	unsigned int this_len;
1232
1233	this_len = min_t(unsigned int, len, subbuf->head[0].iov_len);
1234	memcpy(subbuf->head[0].iov_base, obj, this_len);
1235	len -= this_len;
1236	obj += this_len;
1237	this_len = min_t(unsigned int, len, subbuf->page_len);
1238	if (this_len)
1239		_copy_to_pages(subbuf->pages, subbuf->page_base, obj, this_len);
1240	len -= this_len;
1241	obj += this_len;
1242	this_len = min_t(unsigned int, len, subbuf->tail[0].iov_len);
1243	memcpy(subbuf->tail[0].iov_base, obj, this_len);
1244}
1245
1246/* obj is assumed to point to allocated memory of size at least len: */
1247int write_bytes_to_xdr_buf(struct xdr_buf *buf, unsigned int base, void *obj, unsigned int len)
1248{
1249	struct xdr_buf subbuf;
1250	int status;
1251
1252	status = xdr_buf_subsegment(buf, &subbuf, base, len);
1253	if (status != 0)
1254		return status;
1255	__write_bytes_to_xdr_buf(&subbuf, obj, len);
1256	return 0;
1257}
1258EXPORT_SYMBOL_GPL(write_bytes_to_xdr_buf);
1259
1260int
1261xdr_decode_word(struct xdr_buf *buf, unsigned int base, u32 *obj)
1262{
1263	__be32	raw;
1264	int	status;
1265
1266	status = read_bytes_from_xdr_buf(buf, base, &raw, sizeof(*obj));
1267	if (status)
1268		return status;
1269	*obj = be32_to_cpu(raw);
1270	return 0;
1271}
1272EXPORT_SYMBOL_GPL(xdr_decode_word);
1273
1274int
1275xdr_encode_word(struct xdr_buf *buf, unsigned int base, u32 obj)
1276{
1277	__be32	raw = cpu_to_be32(obj);
1278
1279	return write_bytes_to_xdr_buf(buf, base, &raw, sizeof(obj));
1280}
1281EXPORT_SYMBOL_GPL(xdr_encode_word);
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
1282
1283/* Returns 0 on success, or else a negative error code. */
1284static int
1285xdr_xcode_array2(struct xdr_buf *buf, unsigned int base,
1286		 struct xdr_array2_desc *desc, int encode)
1287{
1288	char *elem = NULL, *c;
1289	unsigned int copied = 0, todo, avail_here;
1290	struct page **ppages = NULL;
1291	int err;
1292
1293	if (encode) {
1294		if (xdr_encode_word(buf, base, desc->array_len) != 0)
1295			return -EINVAL;
1296	} else {
1297		if (xdr_decode_word(buf, base, &desc->array_len) != 0 ||
1298		    desc->array_len > desc->array_maxlen ||
1299		    (unsigned long) base + 4 + desc->array_len *
1300				    desc->elem_size > buf->len)
1301			return -EINVAL;
1302	}
1303	base += 4;
1304
1305	if (!desc->xcode)
1306		return 0;
1307
1308	todo = desc->array_len * desc->elem_size;
1309
1310	/* process head */
1311	if (todo && base < buf->head->iov_len) {
1312		c = buf->head->iov_base + base;
1313		avail_here = min_t(unsigned int, todo,
1314				   buf->head->iov_len - base);
1315		todo -= avail_here;
1316
1317		while (avail_here >= desc->elem_size) {
1318			err = desc->xcode(desc, c);
1319			if (err)
1320				goto out;
1321			c += desc->elem_size;
1322			avail_here -= desc->elem_size;
1323		}
1324		if (avail_here) {
1325			if (!elem) {
1326				elem = kmalloc(desc->elem_size, GFP_KERNEL);
1327				err = -ENOMEM;
1328				if (!elem)
1329					goto out;
1330			}
1331			if (encode) {
1332				err = desc->xcode(desc, elem);
1333				if (err)
1334					goto out;
1335				memcpy(c, elem, avail_here);
1336			} else
1337				memcpy(elem, c, avail_here);
1338			copied = avail_here;
1339		}
1340		base = buf->head->iov_len;  /* align to start of pages */
1341	}
1342
1343	/* process pages array */
1344	base -= buf->head->iov_len;
1345	if (todo && base < buf->page_len) {
1346		unsigned int avail_page;
1347
1348		avail_here = min(todo, buf->page_len - base);
1349		todo -= avail_here;
1350
1351		base += buf->page_base;
1352		ppages = buf->pages + (base >> PAGE_SHIFT);
1353		base &= ~PAGE_MASK;
1354		avail_page = min_t(unsigned int, PAGE_SIZE - base,
1355					avail_here);
1356		c = kmap(*ppages) + base;
1357
1358		while (avail_here) {
1359			avail_here -= avail_page;
1360			if (copied || avail_page < desc->elem_size) {
1361				unsigned int l = min(avail_page,
1362					desc->elem_size - copied);
1363				if (!elem) {
1364					elem = kmalloc(desc->elem_size,
1365						       GFP_KERNEL);
1366					err = -ENOMEM;
1367					if (!elem)
1368						goto out;
1369				}
1370				if (encode) {
1371					if (!copied) {
1372						err = desc->xcode(desc, elem);
1373						if (err)
1374							goto out;
1375					}
1376					memcpy(c, elem + copied, l);
1377					copied += l;
1378					if (copied == desc->elem_size)
1379						copied = 0;
1380				} else {
1381					memcpy(elem + copied, c, l);
1382					copied += l;
1383					if (copied == desc->elem_size) {
1384						err = desc->xcode(desc, elem);
1385						if (err)
1386							goto out;
1387						copied = 0;
1388					}
1389				}
1390				avail_page -= l;
1391				c += l;
1392			}
1393			while (avail_page >= desc->elem_size) {
1394				err = desc->xcode(desc, c);
1395				if (err)
1396					goto out;
1397				c += desc->elem_size;
1398				avail_page -= desc->elem_size;
1399			}
1400			if (avail_page) {
1401				unsigned int l = min(avail_page,
1402					    desc->elem_size - copied);
1403				if (!elem) {
1404					elem = kmalloc(desc->elem_size,
1405						       GFP_KERNEL);
1406					err = -ENOMEM;
1407					if (!elem)
1408						goto out;
1409				}
1410				if (encode) {
1411					if (!copied) {
1412						err = desc->xcode(desc, elem);
1413						if (err)
1414							goto out;
1415					}
1416					memcpy(c, elem + copied, l);
1417					copied += l;
1418					if (copied == desc->elem_size)
1419						copied = 0;
1420				} else {
1421					memcpy(elem + copied, c, l);
1422					copied += l;
1423					if (copied == desc->elem_size) {
1424						err = desc->xcode(desc, elem);
1425						if (err)
1426							goto out;
1427						copied = 0;
1428					}
1429				}
1430			}
1431			if (avail_here) {
1432				kunmap(*ppages);
1433				ppages++;
1434				c = kmap(*ppages);
1435			}
1436
1437			avail_page = min(avail_here,
1438				 (unsigned int) PAGE_SIZE);
1439		}
1440		base = buf->page_len;  /* align to start of tail */
1441	}
1442
1443	/* process tail */
1444	base -= buf->page_len;
1445	if (todo) {
1446		c = buf->tail->iov_base + base;
1447		if (copied) {
1448			unsigned int l = desc->elem_size - copied;
1449
1450			if (encode)
1451				memcpy(c, elem + copied, l);
1452			else {
1453				memcpy(elem + copied, c, l);
1454				err = desc->xcode(desc, elem);
1455				if (err)
1456					goto out;
1457			}
1458			todo -= l;
1459			c += l;
1460		}
1461		while (todo) {
1462			err = desc->xcode(desc, c);
1463			if (err)
1464				goto out;
1465			c += desc->elem_size;
1466			todo -= desc->elem_size;
1467		}
1468	}
1469	err = 0;
1470
1471out:
1472	kfree(elem);
1473	if (ppages)
1474		kunmap(*ppages);
1475	return err;
1476}
1477
1478int
1479xdr_decode_array2(struct xdr_buf *buf, unsigned int base,
1480		  struct xdr_array2_desc *desc)
1481{
1482	if (base >= buf->len)
1483		return -EINVAL;
1484
1485	return xdr_xcode_array2(buf, base, desc, 0);
1486}
1487EXPORT_SYMBOL_GPL(xdr_decode_array2);
1488
1489int
1490xdr_encode_array2(struct xdr_buf *buf, unsigned int base,
1491		  struct xdr_array2_desc *desc)
1492{
1493	if ((unsigned long) base + 4 + desc->array_len * desc->elem_size >
1494	    buf->head->iov_len + buf->page_len + buf->tail->iov_len)
1495		return -EINVAL;
1496
1497	return xdr_xcode_array2(buf, base, desc, 1);
1498}
1499EXPORT_SYMBOL_GPL(xdr_encode_array2);
1500
1501int
1502xdr_process_buf(struct xdr_buf *buf, unsigned int offset, unsigned int len,
1503		int (*actor)(struct scatterlist *, void *), void *data)
1504{
1505	int i, ret = 0;
1506	unsigned int page_len, thislen, page_offset;
1507	struct scatterlist      sg[1];
1508
1509	sg_init_table(sg, 1);
1510
1511	if (offset >= buf->head[0].iov_len) {
1512		offset -= buf->head[0].iov_len;
1513	} else {
1514		thislen = buf->head[0].iov_len - offset;
1515		if (thislen > len)
1516			thislen = len;
1517		sg_set_buf(sg, buf->head[0].iov_base + offset, thislen);
1518		ret = actor(sg, data);
1519		if (ret)
1520			goto out;
1521		offset = 0;
1522		len -= thislen;
1523	}
1524	if (len == 0)
1525		goto out;
1526
1527	if (offset >= buf->page_len) {
1528		offset -= buf->page_len;
1529	} else {
1530		page_len = buf->page_len - offset;
1531		if (page_len > len)
1532			page_len = len;
1533		len -= page_len;
1534		page_offset = (offset + buf->page_base) & (PAGE_SIZE - 1);
1535		i = (offset + buf->page_base) >> PAGE_SHIFT;
1536		thislen = PAGE_SIZE - page_offset;
1537		do {
1538			if (thislen > page_len)
1539				thislen = page_len;
1540			sg_set_page(sg, buf->pages[i], thislen, page_offset);
1541			ret = actor(sg, data);
1542			if (ret)
1543				goto out;
1544			page_len -= thislen;
1545			i++;
1546			page_offset = 0;
1547			thislen = PAGE_SIZE;
1548		} while (page_len != 0);
1549		offset = 0;
1550	}
1551	if (len == 0)
1552		goto out;
1553	if (offset < buf->tail[0].iov_len) {
1554		thislen = buf->tail[0].iov_len - offset;
1555		if (thislen > len)
1556			thislen = len;
1557		sg_set_buf(sg, buf->tail[0].iov_base + offset, thislen);
1558		ret = actor(sg, data);
1559		len -= thislen;
1560	}
1561	if (len != 0)
1562		ret = -EINVAL;
1563out:
1564	return ret;
1565}
1566EXPORT_SYMBOL_GPL(xdr_process_buf);
1567
1568/**
1569 * xdr_stream_decode_opaque - Decode variable length opaque
1570 * @xdr: pointer to xdr_stream
1571 * @ptr: location to store opaque data
1572 * @size: size of storage buffer @ptr
1573 *
1574 * Return values:
1575 *   On success, returns size of object stored in *@ptr
1576 *   %-EBADMSG on XDR buffer overflow
1577 *   %-EMSGSIZE on overflow of storage buffer @ptr
1578 */
1579ssize_t xdr_stream_decode_opaque(struct xdr_stream *xdr, void *ptr, size_t size)
1580{
1581	ssize_t ret;
1582	void *p;
1583
1584	ret = xdr_stream_decode_opaque_inline(xdr, &p, size);
1585	if (ret <= 0)
1586		return ret;
1587	memcpy(ptr, p, ret);
1588	return ret;
1589}
1590EXPORT_SYMBOL_GPL(xdr_stream_decode_opaque);
1591
1592/**
1593 * xdr_stream_decode_opaque_dup - Decode and duplicate variable length opaque
1594 * @xdr: pointer to xdr_stream
1595 * @ptr: location to store pointer to opaque data
1596 * @maxlen: maximum acceptable object size
1597 * @gfp_flags: GFP mask to use
1598 *
1599 * Return values:
1600 *   On success, returns size of object stored in *@ptr
1601 *   %-EBADMSG on XDR buffer overflow
1602 *   %-EMSGSIZE if the size of the object would exceed @maxlen
1603 *   %-ENOMEM on memory allocation failure
1604 */
1605ssize_t xdr_stream_decode_opaque_dup(struct xdr_stream *xdr, void **ptr,
1606		size_t maxlen, gfp_t gfp_flags)
1607{
1608	ssize_t ret;
1609	void *p;
1610
1611	ret = xdr_stream_decode_opaque_inline(xdr, &p, maxlen);
1612	if (ret > 0) {
1613		*ptr = kmemdup(p, ret, gfp_flags);
1614		if (*ptr != NULL)
1615			return ret;
1616		ret = -ENOMEM;
1617	}
1618	*ptr = NULL;
1619	return ret;
1620}
1621EXPORT_SYMBOL_GPL(xdr_stream_decode_opaque_dup);
1622
1623/**
1624 * xdr_stream_decode_string - Decode variable length string
1625 * @xdr: pointer to xdr_stream
1626 * @str: location to store string
1627 * @size: size of storage buffer @str
1628 *
1629 * Return values:
1630 *   On success, returns length of NUL-terminated string stored in *@str
1631 *   %-EBADMSG on XDR buffer overflow
1632 *   %-EMSGSIZE on overflow of storage buffer @str
1633 */
1634ssize_t xdr_stream_decode_string(struct xdr_stream *xdr, char *str, size_t size)
1635{
1636	ssize_t ret;
1637	void *p;
1638
1639	ret = xdr_stream_decode_opaque_inline(xdr, &p, size);
1640	if (ret > 0) {
1641		memcpy(str, p, ret);
1642		str[ret] = '\0';
1643		return strlen(str);
1644	}
1645	*str = '\0';
1646	return ret;
1647}
1648EXPORT_SYMBOL_GPL(xdr_stream_decode_string);
1649
1650/**
1651 * xdr_stream_decode_string_dup - Decode and duplicate variable length string
1652 * @xdr: pointer to xdr_stream
1653 * @str: location to store pointer to string
1654 * @maxlen: maximum acceptable string length
1655 * @gfp_flags: GFP mask to use
1656 *
1657 * Return values:
1658 *   On success, returns length of NUL-terminated string stored in *@ptr
1659 *   %-EBADMSG on XDR buffer overflow
1660 *   %-EMSGSIZE if the size of the string would exceed @maxlen
1661 *   %-ENOMEM on memory allocation failure
1662 */
1663ssize_t xdr_stream_decode_string_dup(struct xdr_stream *xdr, char **str,
1664		size_t maxlen, gfp_t gfp_flags)
1665{
1666	void *p;
1667	ssize_t ret;
1668
1669	ret = xdr_stream_decode_opaque_inline(xdr, &p, maxlen);
1670	if (ret > 0) {
1671		char *s = kmalloc(ret + 1, gfp_flags);
1672		if (s != NULL) {
1673			memcpy(s, p, ret);
1674			s[ret] = '\0';
1675			*str = s;
1676			return strlen(s);
1677		}
1678		ret = -ENOMEM;
1679	}
1680	*str = NULL;
1681	return ret;
1682}
1683EXPORT_SYMBOL_GPL(xdr_stream_decode_string_dup);