net/sunrpc/xdr.c

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