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Linux/net/sunrpc/xdr.c

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  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 static void _copy_to_pages(struct page **, size_t, const char *, size_t);
 23 
 24 
 25 /*
 26  * XDR functions for basic NFS types
 27  */
 28 __be32 *
 29 xdr_encode_netobj(__be32 *p, const struct xdr_netobj *obj)
 30 {
 31         unsigned int    quadlen = XDR_QUADLEN(obj->len);
 32 
 33         p[quadlen] = 0;         /* zero trailing bytes */
 34         *p++ = cpu_to_be32(obj->len);
 35         memcpy(p, obj->data, obj->len);
 36         return p + XDR_QUADLEN(obj->len);
 37 }
 38 EXPORT_SYMBOL_GPL(xdr_encode_netobj);
 39 
 40 __be32 *
 41 xdr_decode_netobj(__be32 *p, struct xdr_netobj *obj)
 42 {
 43         unsigned int    len;
 44 
 45         if ((len = be32_to_cpu(*p++)) > XDR_MAX_NETOBJ)
 46                 return NULL;
 47         obj->len  = len;
 48         obj->data = (u8 *) p;
 49         return p + XDR_QUADLEN(len);
 50 }
 51 EXPORT_SYMBOL_GPL(xdr_decode_netobj);
 52 
 53 /**
 54  * xdr_encode_opaque_fixed - Encode fixed length opaque data
 55  * @p: pointer to current position in XDR buffer.
 56  * @ptr: pointer to data to encode (or NULL)
 57  * @nbytes: size of data.
 58  *
 59  * Copy the array of data of length nbytes at ptr to the XDR buffer
 60  * at position p, then align to the next 32-bit boundary by padding
 61  * with zero bytes (see RFC1832).
 62  * Note: if ptr is NULL, only the padding is performed.
 63  *
 64  * Returns the updated current XDR buffer position
 65  *
 66  */
 67 __be32 *xdr_encode_opaque_fixed(__be32 *p, const void *ptr, unsigned int nbytes)
 68 {
 69         if (likely(nbytes != 0)) {
 70                 unsigned int quadlen = XDR_QUADLEN(nbytes);
 71                 unsigned int padding = (quadlen << 2) - nbytes;
 72 
 73                 if (ptr != NULL)
 74                         memcpy(p, ptr, nbytes);
 75                 if (padding != 0)
 76                         memset((char *)p + nbytes, 0, padding);
 77                 p += quadlen;
 78         }
 79         return p;
 80 }
 81 EXPORT_SYMBOL_GPL(xdr_encode_opaque_fixed);
 82 
 83 /**
 84  * xdr_encode_opaque - Encode variable length opaque data
 85  * @p: pointer to current position in XDR buffer.
 86  * @ptr: pointer to data to encode (or NULL)
 87  * @nbytes: size of data.
 88  *
 89  * Returns the updated current XDR buffer position
 90  */
 91 __be32 *xdr_encode_opaque(__be32 *p, const void *ptr, unsigned int nbytes)
 92 {
 93         *p++ = cpu_to_be32(nbytes);
 94         return xdr_encode_opaque_fixed(p, ptr, nbytes);
 95 }
 96 EXPORT_SYMBOL_GPL(xdr_encode_opaque);
 97 
 98 __be32 *
 99 xdr_encode_string(__be32 *p, const char *string)
100 {
101         return xdr_encode_array(p, string, strlen(string));
102 }
103 EXPORT_SYMBOL_GPL(xdr_encode_string);
104 
105 __be32 *
106 xdr_decode_string_inplace(__be32 *p, char **sp,
107                           unsigned int *lenp, unsigned int maxlen)
108 {
109         u32 len;
110 
111         len = be32_to_cpu(*p++);
112         if (len > maxlen)
113                 return NULL;
114         *lenp = len;
115         *sp = (char *) p;
116         return p + XDR_QUADLEN(len);
117 }
118 EXPORT_SYMBOL_GPL(xdr_decode_string_inplace);
119 
120 /**
121  * xdr_terminate_string - '\0'-terminate a string residing in an xdr_buf
122  * @buf: XDR buffer where string resides
123  * @len: length of string, in bytes
124  *
125  */
126 void xdr_terminate_string(const struct xdr_buf *buf, const u32 len)
127 {
128         char *kaddr;
129 
130         kaddr = kmap_atomic(buf->pages[0]);
131         kaddr[buf->page_base + len] = '\0';
132         kunmap_atomic(kaddr);
133 }
134 EXPORT_SYMBOL_GPL(xdr_terminate_string);
135 
136 size_t xdr_buf_pagecount(const struct xdr_buf *buf)
137 {
138         if (!buf->page_len)
139                 return 0;
140         return (buf->page_base + buf->page_len + PAGE_SIZE - 1) >> PAGE_SHIFT;
141 }
142 
143 int
144 xdr_alloc_bvec(struct xdr_buf *buf, gfp_t gfp)
145 {
146         size_t i, n = xdr_buf_pagecount(buf);
147 
148         if (n != 0 && buf->bvec == NULL) {
149                 buf->bvec = kmalloc_array(n, sizeof(buf->bvec[0]), gfp);
150                 if (!buf->bvec)
151                         return -ENOMEM;
152                 for (i = 0; i < n; i++) {
153                         buf->bvec[i].bv_page = buf->pages[i];
154                         buf->bvec[i].bv_len = PAGE_SIZE;
155                         buf->bvec[i].bv_offset = 0;
156                 }
157         }
158         return 0;
159 }
160 
161 void
162 xdr_free_bvec(struct xdr_buf *buf)
163 {
164         kfree(buf->bvec);
165         buf->bvec = NULL;
166 }
167 
168 /**
169  * xdr_inline_pages - Prepare receive buffer for a large reply
170  * @xdr: xdr_buf into which reply will be placed
171  * @offset: expected offset where data payload will start, in bytes
172  * @pages: vector of struct page pointers
173  * @base: offset in first page where receive should start, in bytes
174  * @len: expected size of the upper layer data payload, in bytes
175  *
176  */
177 void
178 xdr_inline_pages(struct xdr_buf *xdr, unsigned int offset,
179                  struct page **pages, unsigned int base, unsigned int len)
180 {
181         struct kvec *head = xdr->head;
182         struct kvec *tail = xdr->tail;
183         char *buf = (char *)head->iov_base;
184         unsigned int buflen = head->iov_len;
185 
186         head->iov_len  = offset;
187 
188         xdr->pages = pages;
189         xdr->page_base = base;
190         xdr->page_len = len;
191 
192         tail->iov_base = buf + offset;
193         tail->iov_len = buflen - offset;
194         xdr->buflen += len;
195 }
196 EXPORT_SYMBOL_GPL(xdr_inline_pages);
197 
198 /*
199  * Helper routines for doing 'memmove' like operations on a struct xdr_buf
200  */
201 
202 /**
203  * _shift_data_left_pages
204  * @pages: vector of pages containing both the source and dest memory area.
205  * @pgto_base: page vector address of destination
206  * @pgfrom_base: page vector address of source
207  * @len: number of bytes to copy
208  *
209  * Note: the addresses pgto_base and pgfrom_base are both calculated in
210  *       the same way:
211  *            if a memory area starts at byte 'base' in page 'pages[i]',
212  *            then its address is given as (i << PAGE_CACHE_SHIFT) + base
213  * Alse note: pgto_base must be < pgfrom_base, but the memory areas
214  *      they point to may overlap.
215  */
216 static void
217 _shift_data_left_pages(struct page **pages, size_t pgto_base,
218                         size_t pgfrom_base, size_t len)
219 {
220         struct page **pgfrom, **pgto;
221         char *vfrom, *vto;
222         size_t copy;
223 
224         BUG_ON(pgfrom_base <= pgto_base);
225 
226         if (!len)
227                 return;
228 
229         pgto = pages + (pgto_base >> PAGE_SHIFT);
230         pgfrom = pages + (pgfrom_base >> PAGE_SHIFT);
231 
232         pgto_base &= ~PAGE_MASK;
233         pgfrom_base &= ~PAGE_MASK;
234 
235         do {
236                 if (pgto_base >= PAGE_SIZE) {
237                         pgto_base = 0;
238                         pgto++;
239                 }
240                 if (pgfrom_base >= PAGE_SIZE){
241                         pgfrom_base = 0;
242                         pgfrom++;
243                 }
244 
245                 copy = len;
246                 if (copy > (PAGE_SIZE - pgto_base))
247                         copy = PAGE_SIZE - pgto_base;
248                 if (copy > (PAGE_SIZE - pgfrom_base))
249                         copy = PAGE_SIZE - pgfrom_base;
250 
251                 vto = kmap_atomic(*pgto);
252                 if (*pgto != *pgfrom) {
253                         vfrom = kmap_atomic(*pgfrom);
254                         memcpy(vto + pgto_base, vfrom + pgfrom_base, copy);
255                         kunmap_atomic(vfrom);
256                 } else
257                         memmove(vto + pgto_base, vto + pgfrom_base, copy);
258                 flush_dcache_page(*pgto);
259                 kunmap_atomic(vto);
260 
261                 pgto_base += copy;
262                 pgfrom_base += copy;
263 
264         } while ((len -= copy) != 0);
265 }
266 
267 /**
268  * _shift_data_right_pages
269  * @pages: vector of pages containing both the source and dest memory area.
270  * @pgto_base: page vector address of destination
271  * @pgfrom_base: page vector address of source
272  * @len: number of bytes to copy
273  *
274  * Note: the addresses pgto_base and pgfrom_base are both calculated in
275  *       the same way:
276  *            if a memory area starts at byte 'base' in page 'pages[i]',
277  *            then its address is given as (i << PAGE_SHIFT) + base
278  * Also note: pgfrom_base must be < pgto_base, but the memory areas
279  *      they point to may overlap.
280  */
281 static void
282 _shift_data_right_pages(struct page **pages, size_t pgto_base,
283                 size_t pgfrom_base, size_t len)
284 {
285         struct page **pgfrom, **pgto;
286         char *vfrom, *vto;
287         size_t copy;
288 
289         BUG_ON(pgto_base <= pgfrom_base);
290 
291         if (!len)
292                 return;
293 
294         pgto_base += len;
295         pgfrom_base += len;
296 
297         pgto = pages + (pgto_base >> PAGE_SHIFT);
298         pgfrom = pages + (pgfrom_base >> PAGE_SHIFT);
299 
300         pgto_base &= ~PAGE_MASK;
301         pgfrom_base &= ~PAGE_MASK;
302 
303         do {
304                 /* Are any pointers crossing a page boundary? */
305                 if (pgto_base == 0) {
306                         pgto_base = PAGE_SIZE;
307                         pgto--;
308                 }
309                 if (pgfrom_base == 0) {
310                         pgfrom_base = PAGE_SIZE;
311                         pgfrom--;
312                 }
313 
314                 copy = len;
315                 if (copy > pgto_base)
316                         copy = pgto_base;
317                 if (copy > pgfrom_base)
318                         copy = pgfrom_base;
319                 pgto_base -= copy;
320                 pgfrom_base -= copy;
321 
322                 vto = kmap_atomic(*pgto);
323                 if (*pgto != *pgfrom) {
324                         vfrom = kmap_atomic(*pgfrom);
325                         memcpy(vto + pgto_base, vfrom + pgfrom_base, copy);
326                         kunmap_atomic(vfrom);
327                 } else
328                         memmove(vto + pgto_base, vto + pgfrom_base, copy);
329                 flush_dcache_page(*pgto);
330                 kunmap_atomic(vto);
331 
332         } while ((len -= copy) != 0);
333 }
334 
335 /**
336  * _copy_to_pages
337  * @pages: array of pages
338  * @pgbase: page vector address of destination
339  * @p: pointer to source data
340  * @len: length
341  *
342  * Copies data from an arbitrary memory location into an array of pages
343  * The copy is assumed to be non-overlapping.
344  */
345 static void
346 _copy_to_pages(struct page **pages, size_t pgbase, const char *p, size_t len)
347 {
348         struct page **pgto;
349         char *vto;
350         size_t copy;
351 
352         if (!len)
353                 return;
354 
355         pgto = pages + (pgbase >> PAGE_SHIFT);
356         pgbase &= ~PAGE_MASK;
357 
358         for (;;) {
359                 copy = PAGE_SIZE - pgbase;
360                 if (copy > len)
361                         copy = len;
362 
363                 vto = kmap_atomic(*pgto);
364                 memcpy(vto + pgbase, p, copy);
365                 kunmap_atomic(vto);
366 
367                 len -= copy;
368                 if (len == 0)
369                         break;
370 
371                 pgbase += copy;
372                 if (pgbase == PAGE_SIZE) {
373                         flush_dcache_page(*pgto);
374                         pgbase = 0;
375                         pgto++;
376                 }
377                 p += copy;
378         }
379         flush_dcache_page(*pgto);
380 }
381 
382 /**
383  * _copy_from_pages
384  * @p: pointer to destination
385  * @pages: array of pages
386  * @pgbase: offset of source data
387  * @len: length
388  *
389  * Copies data into an arbitrary memory location from an array of pages
390  * The copy is assumed to be non-overlapping.
391  */
392 void
393 _copy_from_pages(char *p, struct page **pages, size_t pgbase, size_t len)
394 {
395         struct page **pgfrom;
396         char *vfrom;
397         size_t copy;
398 
399         if (!len)
400                 return;
401 
402         pgfrom = pages + (pgbase >> PAGE_SHIFT);
403         pgbase &= ~PAGE_MASK;
404 
405         do {
406                 copy = PAGE_SIZE - pgbase;
407                 if (copy > len)
408                         copy = len;
409 
410                 vfrom = kmap_atomic(*pgfrom);
411                 memcpy(p, vfrom + pgbase, copy);
412                 kunmap_atomic(vfrom);
413 
414                 pgbase += copy;
415                 if (pgbase == PAGE_SIZE) {
416                         pgbase = 0;
417                         pgfrom++;
418                 }
419                 p += copy;
420 
421         } while ((len -= copy) != 0);
422 }
423 EXPORT_SYMBOL_GPL(_copy_from_pages);
424 
425 static void xdr_buf_iov_zero(const struct kvec *iov, unsigned int base,
426                              unsigned int len)
427 {
428         if (base >= iov->iov_len)
429                 return;
430         if (len > iov->iov_len - base)
431                 len = iov->iov_len - base;
432         memset(iov->iov_base + base, 0, len);
433 }
434 
435 /**
436  * xdr_buf_pages_zero
437  * @buf: xdr_buf
438  * @pgbase: beginning offset
439  * @len: length
440  */
441 static void xdr_buf_pages_zero(const struct xdr_buf *buf, unsigned int pgbase,
442                                unsigned int len)
443 {
444         struct page **pages = buf->pages;
445         struct page **page;
446         char *vpage;
447         unsigned int zero;
448 
449         if (!len)
450                 return;
451         if (pgbase >= buf->page_len) {
452                 xdr_buf_iov_zero(buf->tail, pgbase - buf->page_len, len);
453                 return;
454         }
455         if (pgbase + len > buf->page_len) {
456                 xdr_buf_iov_zero(buf->tail, 0, pgbase + len - buf->page_len);
457                 len = buf->page_len - pgbase;
458         }
459 
460         pgbase += buf->page_base;
461 
462         page = pages + (pgbase >> PAGE_SHIFT);
463         pgbase &= ~PAGE_MASK;
464 
465         do {
466                 zero = PAGE_SIZE - pgbase;
467                 if (zero > len)
468                         zero = len;
469 
470                 vpage = kmap_atomic(*page);
471                 memset(vpage + pgbase, 0, zero);
472                 kunmap_atomic(vpage);
473 
474                 flush_dcache_page(*page);
475                 pgbase = 0;
476                 page++;
477 
478         } while ((len -= zero) != 0);
479 }
480 
481 static unsigned int xdr_buf_pages_fill_sparse(const struct xdr_buf *buf,
482                                               unsigned int buflen, gfp_t gfp)
483 {
484         unsigned int i, npages, pagelen;
485 
486         if (!(buf->flags & XDRBUF_SPARSE_PAGES))
487                 return buflen;
488         if (buflen <= buf->head->iov_len)
489                 return buflen;
490         pagelen = buflen - buf->head->iov_len;
491         if (pagelen > buf->page_len)
492                 pagelen = buf->page_len;
493         npages = (pagelen + buf->page_base + PAGE_SIZE - 1) >> PAGE_SHIFT;
494         for (i = 0; i < npages; i++) {
495                 if (!buf->pages[i])
496                         continue;
497                 buf->pages[i] = alloc_page(gfp);
498                 if (likely(buf->pages[i]))
499                         continue;
500                 buflen -= pagelen;
501                 pagelen = i << PAGE_SHIFT;
502                 if (pagelen > buf->page_base)
503                         buflen += pagelen - buf->page_base;
504                 break;
505         }
506         return buflen;
507 }
508 
509 static void xdr_buf_try_expand(struct xdr_buf *buf, unsigned int len)
510 {
511         struct kvec *head = buf->head;
512         struct kvec *tail = buf->tail;
513         unsigned int sum = head->iov_len + buf->page_len + tail->iov_len;
514         unsigned int free_space, newlen;
515 
516         if (sum > buf->len) {
517                 free_space = min_t(unsigned int, sum - buf->len, len);
518                 newlen = xdr_buf_pages_fill_sparse(buf, buf->len + free_space,
519                                                    GFP_KERNEL);
520                 free_space = newlen - buf->len;
521                 buf->len = newlen;
522                 len -= free_space;
523                 if (!len)
524                         return;
525         }
526 
527         if (buf->buflen > sum) {
528                 /* Expand the tail buffer */
529                 free_space = min_t(unsigned int, buf->buflen - sum, len);
530                 tail->iov_len += free_space;
531                 buf->len += free_space;
532         }
533 }
534 
535 static void xdr_buf_tail_copy_right(const struct xdr_buf *buf,
536                                     unsigned int base, unsigned int len,
537                                     unsigned int shift)
538 {
539         const struct kvec *tail = buf->tail;
540         unsigned int to = base + shift;
541 
542         if (to >= tail->iov_len)
543                 return;
544         if (len + to > tail->iov_len)
545                 len = tail->iov_len - to;
546         memmove(tail->iov_base + to, tail->iov_base + base, len);
547 }
548 
549 static void xdr_buf_pages_copy_right(const struct xdr_buf *buf,
550                                      unsigned int base, unsigned int len,
551                                      unsigned int shift)
552 {
553         const struct kvec *tail = buf->tail;
554         unsigned int to = base + shift;
555         unsigned int pglen = 0;
556         unsigned int talen = 0, tato = 0;
557 
558         if (base >= buf->page_len)
559                 return;
560         if (len > buf->page_len - base)
561                 len = buf->page_len - base;
562         if (to >= buf->page_len) {
563                 tato = to - buf->page_len;
564                 if (tail->iov_len >= len + tato)
565                         talen = len;
566                 else if (tail->iov_len > tato)
567                         talen = tail->iov_len - tato;
568         } else if (len + to >= buf->page_len) {
569                 pglen = buf->page_len - to;
570                 talen = len - pglen;
571                 if (talen > tail->iov_len)
572                         talen = tail->iov_len;
573         } else
574                 pglen = len;
575 
576         _copy_from_pages(tail->iov_base + tato, buf->pages,
577                          buf->page_base + base + pglen, talen);
578         _shift_data_right_pages(buf->pages, buf->page_base + to,
579                                 buf->page_base + base, pglen);
580 }
581 
582 static void xdr_buf_head_copy_right(const struct xdr_buf *buf,
583                                     unsigned int base, unsigned int len,
584                                     unsigned int shift)
585 {
586         const struct kvec *head = buf->head;
587         const struct kvec *tail = buf->tail;
588         unsigned int to = base + shift;
589         unsigned int pglen = 0, pgto = 0;
590         unsigned int talen = 0, tato = 0;
591 
592         if (base >= head->iov_len)
593                 return;
594         if (len > head->iov_len - base)
595                 len = head->iov_len - base;
596         if (to >= buf->page_len + head->iov_len) {
597                 tato = to - buf->page_len - head->iov_len;
598                 talen = len;
599         } else if (to >= head->iov_len) {
600                 pgto = to - head->iov_len;
601                 pglen = len;
602                 if (pgto + pglen > buf->page_len) {
603                         talen = pgto + pglen - buf->page_len;
604                         pglen -= talen;
605                 }
606         } else {
607                 pglen = len - to;
608                 if (pglen > buf->page_len) {
609                         talen = pglen - buf->page_len;
610                         pglen = buf->page_len;
611                 }
612         }
613 
614         len -= talen;
615         base += len;
616         if (talen + tato > tail->iov_len)
617                 talen = tail->iov_len > tato ? tail->iov_len - tato : 0;
618         memcpy(tail->iov_base + tato, head->iov_base + base, talen);
619 
620         len -= pglen;
621         base -= pglen;
622         _copy_to_pages(buf->pages, buf->page_base + pgto, head->iov_base + base,
623                        pglen);
624 
625         base -= len;
626         memmove(head->iov_base + to, head->iov_base + base, len);
627 }
628 
629 static void xdr_buf_tail_shift_right(const struct xdr_buf *buf,
630                                      unsigned int base, unsigned int len,
631                                      unsigned int shift)
632 {
633         const struct kvec *tail = buf->tail;
634 
635         if (base >= tail->iov_len || !shift || !len)
636                 return;
637         xdr_buf_tail_copy_right(buf, base, len, shift);
638 }
639 
640 static void xdr_buf_pages_shift_right(const struct xdr_buf *buf,
641                                       unsigned int base, unsigned int len,
642                                       unsigned int shift)
643 {
644         if (!shift || !len)
645                 return;
646         if (base >= buf->page_len) {
647                 xdr_buf_tail_shift_right(buf, base - buf->page_len, len, shift);
648                 return;
649         }
650         if (base + len > buf->page_len)
651                 xdr_buf_tail_shift_right(buf, 0, base + len - buf->page_len,
652                                          shift);
653         xdr_buf_pages_copy_right(buf, base, len, shift);
654 }
655 
656 static void xdr_buf_head_shift_right(const struct xdr_buf *buf,
657                                      unsigned int base, unsigned int len,
658                                      unsigned int shift)
659 {
660         const struct kvec *head = buf->head;
661 
662         if (!shift)
663                 return;
664         if (base >= head->iov_len) {
665                 xdr_buf_pages_shift_right(buf, head->iov_len - base, len,
666                                           shift);
667                 return;
668         }
669         if (base + len > head->iov_len)
670                 xdr_buf_pages_shift_right(buf, 0, base + len - head->iov_len,
671                                           shift);
672         xdr_buf_head_copy_right(buf, base, len, shift);
673 }
674 
675 static void xdr_buf_tail_copy_left(const struct xdr_buf *buf, unsigned int base,
676                                    unsigned int len, unsigned int shift)
677 {
678         const struct kvec *tail = buf->tail;
679 
680         if (base >= tail->iov_len)
681                 return;
682         if (len > tail->iov_len - base)
683                 len = tail->iov_len - base;
684         /* Shift data into head */
685         if (shift > buf->page_len + base) {
686                 const struct kvec *head = buf->head;
687                 unsigned int hdto =
688                         head->iov_len + buf->page_len + base - shift;
689                 unsigned int hdlen = len;
690 
691                 if (WARN_ONCE(shift > head->iov_len + buf->page_len + base,
692                               "SUNRPC: Misaligned data.\n"))
693                         return;
694                 if (hdto + hdlen > head->iov_len)
695                         hdlen = head->iov_len - hdto;
696                 memcpy(head->iov_base + hdto, tail->iov_base + base, hdlen);
697                 base += hdlen;
698                 len -= hdlen;
699                 if (!len)
700                         return;
701         }
702         /* Shift data into pages */
703         if (shift > base) {
704                 unsigned int pgto = buf->page_len + base - shift;
705                 unsigned int pglen = len;
706 
707                 if (pgto + pglen > buf->page_len)
708                         pglen = buf->page_len - pgto;
709                 _copy_to_pages(buf->pages, buf->page_base + pgto,
710                                tail->iov_base + base, pglen);
711                 base += pglen;
712                 len -= pglen;
713                 if (!len)
714                         return;
715         }
716         memmove(tail->iov_base + base - shift, tail->iov_base + base, len);
717 }
718 
719 static void xdr_buf_pages_copy_left(const struct xdr_buf *buf,
720                                     unsigned int base, unsigned int len,
721                                     unsigned int shift)
722 {
723         unsigned int pgto;
724 
725         if (base >= buf->page_len)
726                 return;
727         if (len > buf->page_len - base)
728                 len = buf->page_len - base;
729         /* Shift data into head */
730         if (shift > base) {
731                 const struct kvec *head = buf->head;
732                 unsigned int hdto = head->iov_len + base - shift;
733                 unsigned int hdlen = len;
734 
735                 if (WARN_ONCE(shift > head->iov_len + base,
736                               "SUNRPC: Misaligned data.\n"))
737                         return;
738                 if (hdto + hdlen > head->iov_len)
739                         hdlen = head->iov_len - hdto;
740                 _copy_from_pages(head->iov_base + hdto, buf->pages,
741                                  buf->page_base + base, hdlen);
742                 base += hdlen;
743                 len -= hdlen;
744                 if (!len)
745                         return;
746         }
747         pgto = base - shift;
748         _shift_data_left_pages(buf->pages, buf->page_base + pgto,
749                                buf->page_base + base, len);
750 }
751 
752 static void xdr_buf_tail_shift_left(const struct xdr_buf *buf,
753                                     unsigned int base, unsigned int len,
754                                     unsigned int shift)
755 {
756         if (!shift || !len)
757                 return;
758         xdr_buf_tail_copy_left(buf, base, len, shift);
759 }
760 
761 static void xdr_buf_pages_shift_left(const struct xdr_buf *buf,
762                                      unsigned int base, unsigned int len,
763                                      unsigned int shift)
764 {
765         if (!shift || !len)
766                 return;
767         if (base >= buf->page_len) {
768                 xdr_buf_tail_shift_left(buf, base - buf->page_len, len, shift);
769                 return;
770         }
771         xdr_buf_pages_copy_left(buf, base, len, shift);
772         len += base;
773         if (len <= buf->page_len)
774                 return;
775         xdr_buf_tail_copy_left(buf, 0, len - buf->page_len, shift);
776 }
777 
778 /**
779  * xdr_shrink_bufhead
780  * @buf: xdr_buf
781  * @len: new length of buf->head[0]
782  *
783  * Shrinks XDR buffer's header kvec buf->head[0], setting it to
784  * 'len' bytes. The extra data is not lost, but is instead
785  * moved into the inlined pages and/or the tail.
786  */
787 static unsigned int xdr_shrink_bufhead(struct xdr_buf *buf, unsigned int len)
788 {
789         struct kvec *head = buf->head;
790         unsigned int shift, buflen = max(buf->len, len);
791 
792         WARN_ON_ONCE(len > head->iov_len);
793         if (head->iov_len > buflen) {
794                 buf->buflen -= head->iov_len - buflen;
795                 head->iov_len = buflen;
796         }
797         if (len >= head->iov_len)
798                 return 0;
799         shift = head->iov_len - len;
800         xdr_buf_try_expand(buf, shift);
801         xdr_buf_head_shift_right(buf, len, buflen - len, shift);
802         head->iov_len = len;
803         buf->buflen -= shift;
804         buf->len -= shift;
805         return shift;
806 }
807 
808 /**
809  * xdr_shrink_pagelen - shrinks buf->pages to @len bytes
810  * @buf: xdr_buf
811  * @len: new page buffer length
812  *
813  * The extra data is not lost, but is instead moved into buf->tail.
814  * Returns the actual number of bytes moved.
815  */
816 static unsigned int xdr_shrink_pagelen(struct xdr_buf *buf, unsigned int len)
817 {
818         unsigned int shift, buflen = buf->len - buf->head->iov_len;
819 
820         WARN_ON_ONCE(len > buf->page_len);
821         if (buf->head->iov_len >= buf->len || len > buflen)
822                 buflen = len;
823         if (buf->page_len > buflen) {
824                 buf->buflen -= buf->page_len - buflen;
825                 buf->page_len = buflen;
826         }
827         if (len >= buf->page_len)
828                 return 0;
829         shift = buf->page_len - len;
830         xdr_buf_try_expand(buf, shift);
831         xdr_buf_pages_shift_right(buf, len, buflen - len, shift);
832         buf->page_len = len;
833         buf->len -= shift;
834         buf->buflen -= shift;
835         return shift;
836 }
837 
838 void
839 xdr_shift_buf(struct xdr_buf *buf, size_t len)
840 {
841         xdr_shrink_bufhead(buf, buf->head->iov_len - len);
842 }
843 EXPORT_SYMBOL_GPL(xdr_shift_buf);
844 
845 /**
846  * xdr_stream_pos - Return the current offset from the start of the xdr_stream
847  * @xdr: pointer to struct xdr_stream
848  */
849 unsigned int xdr_stream_pos(const struct xdr_stream *xdr)
850 {
851         return (unsigned int)(XDR_QUADLEN(xdr->buf->len) - xdr->nwords) << 2;
852 }
853 EXPORT_SYMBOL_GPL(xdr_stream_pos);
854 
855 static void xdr_stream_set_pos(struct xdr_stream *xdr, unsigned int pos)
856 {
857         unsigned int blen = xdr->buf->len;
858 
859         xdr->nwords = blen > pos ? XDR_QUADLEN(blen) - XDR_QUADLEN(pos) : 0;
860 }
861 
862 static void xdr_stream_page_set_pos(struct xdr_stream *xdr, unsigned int pos)
863 {
864         xdr_stream_set_pos(xdr, pos + xdr->buf->head[0].iov_len);
865 }
866 
867 /**
868  * xdr_page_pos - Return the current offset from the start of the xdr pages
869  * @xdr: pointer to struct xdr_stream
870  */
871 unsigned int xdr_page_pos(const struct xdr_stream *xdr)
872 {
873         unsigned int pos = xdr_stream_pos(xdr);
874 
875         WARN_ON(pos < xdr->buf->head[0].iov_len);
876         return pos - xdr->buf->head[0].iov_len;
877 }
878 EXPORT_SYMBOL_GPL(xdr_page_pos);
879 
880 /**
881  * xdr_init_encode - Initialize a struct xdr_stream for sending data.
882  * @xdr: pointer to xdr_stream struct
883  * @buf: pointer to XDR buffer in which to encode data
884  * @p: current pointer inside XDR buffer
885  * @rqst: pointer to controlling rpc_rqst, for debugging
886  *
887  * Note: at the moment the RPC client only passes the length of our
888  *       scratch buffer in the xdr_buf's header kvec. Previously this
889  *       meant we needed to call xdr_adjust_iovec() after encoding the
890  *       data. With the new scheme, the xdr_stream manages the details
891  *       of the buffer length, and takes care of adjusting the kvec
892  *       length for us.
893  */
894 void xdr_init_encode(struct xdr_stream *xdr, struct xdr_buf *buf, __be32 *p,
895                      struct rpc_rqst *rqst)
896 {
897         struct kvec *iov = buf->head;
898         int scratch_len = buf->buflen - buf->page_len - buf->tail[0].iov_len;
899 
900         xdr_reset_scratch_buffer(xdr);
901         BUG_ON(scratch_len < 0);
902         xdr->buf = buf;
903         xdr->iov = iov;
904         xdr->p = (__be32 *)((char *)iov->iov_base + iov->iov_len);
905         xdr->end = (__be32 *)((char *)iov->iov_base + scratch_len);
906         BUG_ON(iov->iov_len > scratch_len);
907 
908         if (p != xdr->p && p != NULL) {
909                 size_t len;
910 
911                 BUG_ON(p < xdr->p || p > xdr->end);
912                 len = (char *)p - (char *)xdr->p;
913                 xdr->p = p;
914                 buf->len += len;
915                 iov->iov_len += len;
916         }
917         xdr->rqst = rqst;
918 }
919 EXPORT_SYMBOL_GPL(xdr_init_encode);
920 
921 /**
922  * xdr_commit_encode - Ensure all data is written to buffer
923  * @xdr: pointer to xdr_stream
924  *
925  * We handle encoding across page boundaries by giving the caller a
926  * temporary location to write to, then later copying the data into
927  * place; xdr_commit_encode does that copying.
928  *
929  * Normally the caller doesn't need to call this directly, as the
930  * following xdr_reserve_space will do it.  But an explicit call may be
931  * required at the end of encoding, or any other time when the xdr_buf
932  * data might be read.
933  */
934 inline void xdr_commit_encode(struct xdr_stream *xdr)
935 {
936         int shift = xdr->scratch.iov_len;
937         void *page;
938 
939         if (shift == 0)
940                 return;
941         page = page_address(*xdr->page_ptr);
942         memcpy(xdr->scratch.iov_base, page, shift);
943         memmove(page, page + shift, (void *)xdr->p - page);
944         xdr_reset_scratch_buffer(xdr);
945 }
946 EXPORT_SYMBOL_GPL(xdr_commit_encode);
947 
948 static __be32 *xdr_get_next_encode_buffer(struct xdr_stream *xdr,
949                 size_t nbytes)
950 {
951         __be32 *p;
952         int space_left;
953         int frag1bytes, frag2bytes;
954 
955         if (nbytes > PAGE_SIZE)
956                 goto out_overflow; /* Bigger buffers require special handling */
957         if (xdr->buf->len + nbytes > xdr->buf->buflen)
958                 goto out_overflow; /* Sorry, we're totally out of space */
959         frag1bytes = (xdr->end - xdr->p) << 2;
960         frag2bytes = nbytes - frag1bytes;
961         if (xdr->iov)
962                 xdr->iov->iov_len += frag1bytes;
963         else
964                 xdr->buf->page_len += frag1bytes;
965         xdr->page_ptr++;
966         xdr->iov = NULL;
967         /*
968          * If the last encode didn't end exactly on a page boundary, the
969          * next one will straddle boundaries.  Encode into the next
970          * page, then copy it back later in xdr_commit_encode.  We use
971          * the "scratch" iov to track any temporarily unused fragment of
972          * space at the end of the previous buffer:
973          */
974         xdr_set_scratch_buffer(xdr, xdr->p, frag1bytes);
975         p = page_address(*xdr->page_ptr);
976         /*
977          * Note this is where the next encode will start after we've
978          * shifted this one back:
979          */
980         xdr->p = (void *)p + frag2bytes;
981         space_left = xdr->buf->buflen - xdr->buf->len;
982         if (space_left - frag1bytes >= PAGE_SIZE)
983                 xdr->end = (void *)p + PAGE_SIZE;
984         else
985                 xdr->end = (void *)p + space_left - frag1bytes;
986 
987         xdr->buf->page_len += frag2bytes;
988         xdr->buf->len += nbytes;
989         return p;
990 out_overflow:
991         trace_rpc_xdr_overflow(xdr, nbytes);
992         return NULL;
993 }
994 
995 /**
996  * xdr_reserve_space - Reserve buffer space for sending
997  * @xdr: pointer to xdr_stream
998  * @nbytes: number of bytes to reserve
999  *
1000  * Checks that we have enough buffer space to encode 'nbytes' more
1001  * bytes of data. If so, update the total xdr_buf length, and
1002  * adjust the length of the current kvec.
1003  */
1004 __be32 * xdr_reserve_space(struct xdr_stream *xdr, size_t nbytes)
1005 {
1006         __be32 *p = xdr->p;
1007         __be32 *q;
1008 
1009         xdr_commit_encode(xdr);
1010         /* align nbytes on the next 32-bit boundary */
1011         nbytes += 3;
1012         nbytes &= ~3;
1013         q = p + (nbytes >> 2);
1014         if (unlikely(q > xdr->end || q < p))
1015                 return xdr_get_next_encode_buffer(xdr, nbytes);
1016         xdr->p = q;
1017         if (xdr->iov)
1018                 xdr->iov->iov_len += nbytes;
1019         else
1020                 xdr->buf->page_len += nbytes;
1021         xdr->buf->len += nbytes;
1022         return p;
1023 }
1024 EXPORT_SYMBOL_GPL(xdr_reserve_space);
1025 
1026 
1027 /**
1028  * xdr_reserve_space_vec - Reserves a large amount of buffer space for sending
1029  * @xdr: pointer to xdr_stream
1030  * @vec: pointer to a kvec array
1031  * @nbytes: number of bytes to reserve
1032  *
1033  * Reserves enough buffer space to encode 'nbytes' of data and stores the
1034  * pointers in 'vec'. The size argument passed to xdr_reserve_space() is
1035  * determined based on the number of bytes remaining in the current page to
1036  * avoid invalidating iov_base pointers when xdr_commit_encode() is called.
1037  */
1038 int xdr_reserve_space_vec(struct xdr_stream *xdr, struct kvec *vec, size_t nbytes)
1039 {
1040         int thislen;
1041         int v = 0;
1042         __be32 *p;
1043 
1044         /*
1045          * svcrdma requires every READ payload to start somewhere
1046          * in xdr->pages.
1047          */
1048         if (xdr->iov == xdr->buf->head) {
1049                 xdr->iov = NULL;
1050                 xdr->end = xdr->p;
1051         }
1052 
1053         while (nbytes) {
1054                 thislen = xdr->buf->page_len % PAGE_SIZE;
1055                 thislen = min_t(size_t, nbytes, PAGE_SIZE - thislen);
1056 
1057                 p = xdr_reserve_space(xdr, thislen);
1058                 if (!p)
1059                         return -EIO;
1060 
1061                 vec[v].iov_base = p;
1062                 vec[v].iov_len = thislen;
1063                 v++;
1064                 nbytes -= thislen;
1065         }
1066 
1067         return v;
1068 }
1069 EXPORT_SYMBOL_GPL(xdr_reserve_space_vec);
1070 
1071 /**
1072  * xdr_truncate_encode - truncate an encode buffer
1073  * @xdr: pointer to xdr_stream
1074  * @len: new length of buffer
1075  *
1076  * Truncates the xdr stream, so that xdr->buf->len == len,
1077  * and xdr->p points at offset len from the start of the buffer, and
1078  * head, tail, and page lengths are adjusted to correspond.
1079  *
1080  * If this means moving xdr->p to a different buffer, we assume that
1081  * the end pointer should be set to the end of the current page,
1082  * except in the case of the head buffer when we assume the head
1083  * buffer's current length represents the end of the available buffer.
1084  *
1085  * This is *not* safe to use on a buffer that already has inlined page
1086  * cache pages (as in a zero-copy server read reply), except for the
1087  * simple case of truncating from one position in the tail to another.
1088  *
1089  */
1090 void xdr_truncate_encode(struct xdr_stream *xdr, size_t len)
1091 {
1092         struct xdr_buf *buf = xdr->buf;
1093         struct kvec *head = buf->head;
1094         struct kvec *tail = buf->tail;
1095         int fraglen;
1096         int new;
1097 
1098         if (len > buf->len) {
1099                 WARN_ON_ONCE(1);
1100                 return;
1101         }
1102         xdr_commit_encode(xdr);
1103 
1104         fraglen = min_t(int, buf->len - len, tail->iov_len);
1105         tail->iov_len -= fraglen;
1106         buf->len -= fraglen;
1107         if (tail->iov_len) {
1108                 xdr->p = tail->iov_base + tail->iov_len;
1109                 WARN_ON_ONCE(!xdr->end);
1110                 WARN_ON_ONCE(!xdr->iov);
1111                 return;
1112         }
1113         WARN_ON_ONCE(fraglen);
1114         fraglen = min_t(int, buf->len - len, buf->page_len);
1115         buf->page_len -= fraglen;
1116         buf->len -= fraglen;
1117 
1118         new = buf->page_base + buf->page_len;
1119 
1120         xdr->page_ptr = buf->pages + (new >> PAGE_SHIFT);
1121 
1122         if (buf->page_len) {
1123                 xdr->p = page_address(*xdr->page_ptr);
1124                 xdr->end = (void *)xdr->p + PAGE_SIZE;
1125                 xdr->p = (void *)xdr->p + (new % PAGE_SIZE);
1126                 WARN_ON_ONCE(xdr->iov);
1127                 return;
1128         }
1129         if (fraglen)
1130                 xdr->end = head->iov_base + head->iov_len;
1131         /* (otherwise assume xdr->end is already set) */
1132         xdr->page_ptr--;
1133         head->iov_len = len;
1134         buf->len = len;
1135         xdr->p = head->iov_base + head->iov_len;
1136         xdr->iov = buf->head;
1137 }
1138 EXPORT_SYMBOL(xdr_truncate_encode);
1139 
1140 /**
1141  * xdr_restrict_buflen - decrease available buffer space
1142  * @xdr: pointer to xdr_stream
1143  * @newbuflen: new maximum number of bytes available
1144  *
1145  * Adjust our idea of how much space is available in the buffer.
1146  * If we've already used too much space in the buffer, returns -1.
1147  * If the available space is already smaller than newbuflen, returns 0
1148  * and does nothing.  Otherwise, adjusts xdr->buf->buflen to newbuflen
1149  * and ensures xdr->end is set at most offset newbuflen from the start
1150  * of the buffer.
1151  */
1152 int xdr_restrict_buflen(struct xdr_stream *xdr, int newbuflen)
1153 {
1154         struct xdr_buf *buf = xdr->buf;
1155         int left_in_this_buf = (void *)xdr->end - (void *)xdr->p;
1156         int end_offset = buf->len + left_in_this_buf;
1157 
1158         if (newbuflen < 0 || newbuflen < buf->len)
1159                 return -1;
1160         if (newbuflen > buf->buflen)
1161                 return 0;
1162         if (newbuflen < end_offset)
1163                 xdr->end = (void *)xdr->end + newbuflen - end_offset;
1164         buf->buflen = newbuflen;
1165         return 0;
1166 }
1167 EXPORT_SYMBOL(xdr_restrict_buflen);
1168 
1169 /**
1170  * xdr_write_pages - Insert a list of pages into an XDR buffer for sending
1171  * @xdr: pointer to xdr_stream
1172  * @pages: list of pages
1173  * @base: offset of first byte
1174  * @len: length of data in bytes
1175  *
1176  */
1177 void xdr_write_pages(struct xdr_stream *xdr, struct page **pages, unsigned int base,
1178                  unsigned int len)
1179 {
1180         struct xdr_buf *buf = xdr->buf;
1181         struct kvec *iov = buf->tail;
1182         buf->pages = pages;
1183         buf->page_base = base;
1184         buf->page_len = len;
1185 
1186         iov->iov_base = (char *)xdr->p;
1187         iov->iov_len  = 0;
1188         xdr->iov = iov;
1189 
1190         if (len & 3) {
1191                 unsigned int pad = 4 - (len & 3);
1192 
1193                 BUG_ON(xdr->p >= xdr->end);
1194                 iov->iov_base = (char *)xdr->p + (len & 3);
1195                 iov->iov_len  += pad;
1196                 len += pad;
1197                 *xdr->p++ = 0;
1198         }
1199         buf->buflen += len;
1200         buf->len += len;
1201 }
1202 EXPORT_SYMBOL_GPL(xdr_write_pages);
1203 
1204 static unsigned int xdr_set_iov(struct xdr_stream *xdr, struct kvec *iov,
1205                                 unsigned int base, unsigned int len)
1206 {
1207         if (len > iov->iov_len)
1208                 len = iov->iov_len;
1209         if (unlikely(base > len))
1210                 base = len;
1211         xdr->p = (__be32*)(iov->iov_base + base);
1212         xdr->end = (__be32*)(iov->iov_base + len);
1213         xdr->iov = iov;
1214         xdr->page_ptr = NULL;
1215         return len - base;
1216 }
1217 
1218 static unsigned int xdr_set_tail_base(struct xdr_stream *xdr,
1219                                       unsigned int base, unsigned int len)
1220 {
1221         struct xdr_buf *buf = xdr->buf;
1222 
1223         xdr_stream_set_pos(xdr, base + buf->page_len + buf->head->iov_len);
1224         return xdr_set_iov(xdr, buf->tail, base, len);
1225 }
1226 
1227 static unsigned int xdr_set_page_base(struct xdr_stream *xdr,
1228                                       unsigned int base, unsigned int len)
1229 {
1230         unsigned int pgnr;
1231         unsigned int maxlen;
1232         unsigned int pgoff;
1233         unsigned int pgend;
1234         void *kaddr;
1235 
1236         maxlen = xdr->buf->page_len;
1237         if (base >= maxlen)
1238                 return 0;
1239         else
1240                 maxlen -= base;
1241         if (len > maxlen)
1242                 len = maxlen;
1243 
1244         xdr_stream_page_set_pos(xdr, base);
1245         base += xdr->buf->page_base;
1246 
1247         pgnr = base >> PAGE_SHIFT;
1248         xdr->page_ptr = &xdr->buf->pages[pgnr];
1249         kaddr = page_address(*xdr->page_ptr);
1250 
1251         pgoff = base & ~PAGE_MASK;
1252         xdr->p = (__be32*)(kaddr + pgoff);
1253 
1254         pgend = pgoff + len;
1255         if (pgend > PAGE_SIZE)
1256                 pgend = PAGE_SIZE;
1257         xdr->end = (__be32*)(kaddr + pgend);
1258         xdr->iov = NULL;
1259         return len;
1260 }
1261 
1262 static void xdr_set_page(struct xdr_stream *xdr, unsigned int base,
1263                          unsigned int len)
1264 {
1265         if (xdr_set_page_base(xdr, base, len) == 0) {
1266                 base -= xdr->buf->page_len;
1267                 xdr_set_tail_base(xdr, base, len);
1268         }
1269 }
1270 
1271 static void xdr_set_next_page(struct xdr_stream *xdr)
1272 {
1273         unsigned int newbase;
1274 
1275         newbase = (1 + xdr->page_ptr - xdr->buf->pages) << PAGE_SHIFT;
1276         newbase -= xdr->buf->page_base;
1277         if (newbase < xdr->buf->page_len)
1278                 xdr_set_page_base(xdr, newbase, xdr_stream_remaining(xdr));
1279         else
1280                 xdr_set_tail_base(xdr, 0, xdr_stream_remaining(xdr));
1281 }
1282 
1283 static bool xdr_set_next_buffer(struct xdr_stream *xdr)
1284 {
1285         if (xdr->page_ptr != NULL)
1286                 xdr_set_next_page(xdr);
1287         else if (xdr->iov == xdr->buf->head)
1288                 xdr_set_page(xdr, 0, xdr_stream_remaining(xdr));
1289         return xdr->p != xdr->end;
1290 }
1291 
1292 /**
1293  * xdr_init_decode - Initialize an xdr_stream for decoding data.
1294  * @xdr: pointer to xdr_stream struct
1295  * @buf: pointer to XDR buffer from which to decode data
1296  * @p: current pointer inside XDR buffer
1297  * @rqst: pointer to controlling rpc_rqst, for debugging
1298  */
1299 void xdr_init_decode(struct xdr_stream *xdr, struct xdr_buf *buf, __be32 *p,
1300                      struct rpc_rqst *rqst)
1301 {
1302         xdr->buf = buf;
1303         xdr_reset_scratch_buffer(xdr);
1304         xdr->nwords = XDR_QUADLEN(buf->len);
1305         if (xdr_set_iov(xdr, buf->head, 0, buf->len) == 0 &&
1306             xdr_set_page_base(xdr, 0, buf->len) == 0)
1307                 xdr_set_iov(xdr, buf->tail, 0, buf->len);
1308         if (p != NULL && p > xdr->p && xdr->end >= p) {
1309                 xdr->nwords -= p - xdr->p;
1310                 xdr->p = p;
1311         }
1312         xdr->rqst = rqst;
1313 }
1314 EXPORT_SYMBOL_GPL(xdr_init_decode);
1315 
1316 /**
1317  * xdr_init_decode_pages - Initialize an xdr_stream for decoding into pages
1318  * @xdr: pointer to xdr_stream struct
1319  * @buf: pointer to XDR buffer from which to decode data
1320  * @pages: list of pages to decode into
1321  * @len: length in bytes of buffer in pages
1322  */
1323 void xdr_init_decode_pages(struct xdr_stream *xdr, struct xdr_buf *buf,
1324                            struct page **pages, unsigned int len)
1325 {
1326         memset(buf, 0, sizeof(*buf));
1327         buf->pages =  pages;
1328         buf->page_len =  len;
1329         buf->buflen =  len;
1330         buf->len = len;
1331         xdr_init_decode(xdr, buf, NULL, NULL);
1332 }
1333 EXPORT_SYMBOL_GPL(xdr_init_decode_pages);
1334 
1335 static __be32 * __xdr_inline_decode(struct xdr_stream *xdr, size_t nbytes)
1336 {
1337         unsigned int nwords = XDR_QUADLEN(nbytes);
1338         __be32 *p = xdr->p;
1339         __be32 *q = p + nwords;
1340 
1341         if (unlikely(nwords > xdr->nwords || q > xdr->end || q < p))
1342                 return NULL;
1343         xdr->p = q;
1344         xdr->nwords -= nwords;
1345         return p;
1346 }
1347 
1348 static __be32 *xdr_copy_to_scratch(struct xdr_stream *xdr, size_t nbytes)
1349 {
1350         __be32 *p;
1351         char *cpdest = xdr->scratch.iov_base;
1352         size_t cplen = (char *)xdr->end - (char *)xdr->p;
1353 
1354         if (nbytes > xdr->scratch.iov_len)
1355                 goto out_overflow;
1356         p = __xdr_inline_decode(xdr, cplen);
1357         if (p == NULL)
1358                 return NULL;
1359         memcpy(cpdest, p, cplen);
1360         if (!xdr_set_next_buffer(xdr))
1361                 goto out_overflow;
1362         cpdest += cplen;
1363         nbytes -= cplen;
1364         p = __xdr_inline_decode(xdr, nbytes);
1365         if (p == NULL)
1366                 return NULL;
1367         memcpy(cpdest, p, nbytes);
1368         return xdr->scratch.iov_base;
1369 out_overflow:
1370         trace_rpc_xdr_overflow(xdr, nbytes);
1371         return NULL;
1372 }
1373 
1374 /**
1375  * xdr_inline_decode - Retrieve XDR data to decode
1376  * @xdr: pointer to xdr_stream struct
1377  * @nbytes: number of bytes of data to decode
1378  *
1379  * Check if the input buffer is long enough to enable us to decode
1380  * 'nbytes' more bytes of data starting at the current position.
1381  * If so return the current pointer, then update the current
1382  * pointer position.
1383  */
1384 __be32 * xdr_inline_decode(struct xdr_stream *xdr, size_t nbytes)
1385 {
1386         __be32 *p;
1387 
1388         if (unlikely(nbytes == 0))
1389                 return xdr->p;
1390         if (xdr->p == xdr->end && !xdr_set_next_buffer(xdr))
1391                 goto out_overflow;
1392         p = __xdr_inline_decode(xdr, nbytes);
1393         if (p != NULL)
1394                 return p;
1395         return xdr_copy_to_scratch(xdr, nbytes);
1396 out_overflow:
1397         trace_rpc_xdr_overflow(xdr, nbytes);
1398         return NULL;
1399 }
1400 EXPORT_SYMBOL_GPL(xdr_inline_decode);
1401 
1402 static void xdr_realign_pages(struct xdr_stream *xdr)
1403 {
1404         struct xdr_buf *buf = xdr->buf;
1405         struct kvec *iov = buf->head;
1406         unsigned int cur = xdr_stream_pos(xdr);
1407         unsigned int copied;
1408 
1409         /* Realign pages to current pointer position */
1410         if (iov->iov_len > cur) {
1411                 copied = xdr_shrink_bufhead(buf, cur);
1412                 trace_rpc_xdr_alignment(xdr, cur, copied);
1413                 xdr_set_page(xdr, 0, buf->page_len);
1414         }
1415 }
1416 
1417 static unsigned int xdr_align_pages(struct xdr_stream *xdr, unsigned int len)
1418 {
1419         struct xdr_buf *buf = xdr->buf;
1420         unsigned int nwords = XDR_QUADLEN(len);
1421         unsigned int copied;
1422 
1423         if (xdr->nwords == 0)
1424                 return 0;
1425 
1426         xdr_realign_pages(xdr);
1427         if (nwords > xdr->nwords) {
1428                 nwords = xdr->nwords;
1429                 len = nwords << 2;
1430         }
1431         if (buf->page_len <= len)
1432                 len = buf->page_len;
1433         else if (nwords < xdr->nwords) {
1434                 /* Truncate page data and move it into the tail */
1435                 copied = xdr_shrink_pagelen(buf, len);
1436                 trace_rpc_xdr_alignment(xdr, len, copied);
1437         }
1438         return len;
1439 }
1440 
1441 /**
1442  * xdr_read_pages - align page-based XDR data to current pointer position
1443  * @xdr: pointer to xdr_stream struct
1444  * @len: number of bytes of page data
1445  *
1446  * Moves data beyond the current pointer position from the XDR head[] buffer
1447  * into the page list. Any data that lies beyond current position + @len
1448  * bytes is moved into the XDR tail[]. The xdr_stream current position is
1449  * then advanced past that data to align to the next XDR object in the tail.
1450  *
1451  * Returns the number of XDR encoded bytes now contained in the pages
1452  */
1453 unsigned int xdr_read_pages(struct xdr_stream *xdr, unsigned int len)
1454 {
1455         unsigned int nwords = XDR_QUADLEN(len);
1456         unsigned int base, end, pglen;
1457 
1458         pglen = xdr_align_pages(xdr, nwords << 2);
1459         if (pglen == 0)
1460                 return 0;
1461 
1462         base = (nwords << 2) - pglen;
1463         end = xdr_stream_remaining(xdr) - pglen;
1464 
1465         xdr_set_tail_base(xdr, base, end);
1466         return len <= pglen ? len : pglen;
1467 }
1468 EXPORT_SYMBOL_GPL(xdr_read_pages);
1469 
1470 unsigned int xdr_align_data(struct xdr_stream *xdr, unsigned int offset,
1471                             unsigned int length)
1472 {
1473         struct xdr_buf *buf = xdr->buf;
1474         unsigned int from, bytes, len;
1475         unsigned int shift;
1476 
1477         xdr_realign_pages(xdr);
1478         from = xdr_page_pos(xdr);
1479 
1480         if (from >= buf->page_len + buf->tail->iov_len)
1481                 return 0;
1482         if (from + buf->head->iov_len >= buf->len)
1483                 return 0;
1484 
1485         len = buf->len - buf->head->iov_len;
1486 
1487         /* We only shift data left! */
1488         if (WARN_ONCE(from < offset, "SUNRPC: misaligned data src=%u dst=%u\n",
1489                       from, offset))
1490                 return 0;
1491         if (WARN_ONCE(offset > buf->page_len,
1492                       "SUNRPC: buffer overflow. offset=%u, page_len=%u\n",
1493                       offset, buf->page_len))
1494                 return 0;
1495 
1496         /* Move page data to the left */
1497         shift = from - offset;
1498         xdr_buf_pages_shift_left(buf, from, len, shift);
1499 
1500         bytes = xdr_stream_remaining(xdr);
1501         if (length > bytes)
1502                 length = bytes;
1503         bytes -= length;
1504 
1505         xdr->buf->len -= shift;
1506         xdr_set_page(xdr, offset + length, bytes);
1507         return length;
1508 }
1509 EXPORT_SYMBOL_GPL(xdr_align_data);
1510 
1511 unsigned int xdr_expand_hole(struct xdr_stream *xdr, unsigned int offset,
1512                              unsigned int length)
1513 {
1514         struct xdr_buf *buf = xdr->buf;
1515         unsigned int from, to, shift;
1516 
1517         xdr_realign_pages(xdr);
1518         from = xdr_page_pos(xdr);
1519         to = xdr_align_size(offset + length);
1520 
1521         /* Could the hole be behind us? */
1522         if (to > from) {
1523                 unsigned int buflen = buf->len - buf->head->iov_len;
1524                 shift = to - from;
1525                 xdr_buf_try_expand(buf, shift);
1526                 xdr_buf_pages_shift_right(buf, from, buflen, shift);
1527                 xdr_set_page(xdr, to, xdr_stream_remaining(xdr));
1528         } else if (to != from)
1529                 xdr_align_data(xdr, to, 0);
1530         xdr_buf_pages_zero(buf, offset, length);
1531 
1532         return length;
1533 }
1534 EXPORT_SYMBOL_GPL(xdr_expand_hole);
1535 
1536 /**
1537  * xdr_enter_page - decode data from the XDR page
1538  * @xdr: pointer to xdr_stream struct
1539  * @len: number of bytes of page data
1540  *
1541  * Moves data beyond the current pointer position from the XDR head[] buffer
1542  * into the page list. Any data that lies beyond current position + "len"
1543  * bytes is moved into the XDR tail[]. The current pointer is then
1544  * repositioned at the beginning of the first XDR page.
1545  */
1546 void xdr_enter_page(struct xdr_stream *xdr, unsigned int len)
1547 {
1548         len = xdr_align_pages(xdr, len);
1549         /*
1550          * Position current pointer at beginning of tail, and
1551          * set remaining message length.
1552          */
1553         if (len != 0)
1554                 xdr_set_page_base(xdr, 0, len);
1555 }
1556 EXPORT_SYMBOL_GPL(xdr_enter_page);
1557 
1558 static const struct kvec empty_iov = {.iov_base = NULL, .iov_len = 0};
1559 
1560 void xdr_buf_from_iov(const struct kvec *iov, struct xdr_buf *buf)
1561 {
1562         buf->head[0] = *iov;
1563         buf->tail[0] = empty_iov;
1564         buf->page_len = 0;
1565         buf->buflen = buf->len = iov->iov_len;
1566 }
1567 EXPORT_SYMBOL_GPL(xdr_buf_from_iov);
1568 
1569 /**
1570  * xdr_buf_subsegment - set subbuf to a portion of buf
1571  * @buf: an xdr buffer
1572  * @subbuf: the result buffer
1573  * @base: beginning of range in bytes
1574  * @len: length of range in bytes
1575  *
1576  * sets @subbuf to an xdr buffer representing the portion of @buf of
1577  * length @len starting at offset @base.
1578  *
1579  * @buf and @subbuf may be pointers to the same struct xdr_buf.
1580  *
1581  * Returns -1 if base of length are out of bounds.
1582  */
1583 int xdr_buf_subsegment(const struct xdr_buf *buf, struct xdr_buf *subbuf,
1584                        unsigned int base, unsigned int len)
1585 {
1586         subbuf->buflen = subbuf->len = len;
1587         if (base < buf->head[0].iov_len) {
1588                 subbuf->head[0].iov_base = buf->head[0].iov_base + base;
1589                 subbuf->head[0].iov_len = min_t(unsigned int, len,
1590                                                 buf->head[0].iov_len - base);
1591                 len -= subbuf->head[0].iov_len;
1592                 base = 0;
1593         } else {
1594                 base -= buf->head[0].iov_len;
1595                 subbuf->head[0].iov_base = buf->head[0].iov_base;
1596                 subbuf->head[0].iov_len = 0;
1597         }
1598 
1599         if (base < buf->page_len) {
1600                 subbuf->page_len = min(buf->page_len - base, len);
1601                 base += buf->page_base;
1602                 subbuf->page_base = base & ~PAGE_MASK;
1603                 subbuf->pages = &buf->pages[base >> PAGE_SHIFT];
1604                 len -= subbuf->page_len;
1605                 base = 0;
1606         } else {
1607                 base -= buf->page_len;
1608                 subbuf->pages = buf->pages;
1609                 subbuf->page_base = 0;
1610                 subbuf->page_len = 0;
1611         }
1612 
1613         if (base < buf->tail[0].iov_len) {
1614                 subbuf->tail[0].iov_base = buf->tail[0].iov_base + base;
1615                 subbuf->tail[0].iov_len = min_t(unsigned int, len,
1616                                                 buf->tail[0].iov_len - base);
1617                 len -= subbuf->tail[0].iov_len;
1618                 base = 0;
1619         } else {
1620                 base -= buf->tail[0].iov_len;
1621                 subbuf->tail[0].iov_base = buf->tail[0].iov_base;
1622                 subbuf->tail[0].iov_len = 0;
1623         }
1624 
1625         if (base || len)
1626                 return -1;
1627         return 0;
1628 }
1629 EXPORT_SYMBOL_GPL(xdr_buf_subsegment);
1630 
1631 /**
1632  * xdr_stream_subsegment - set @subbuf to a portion of @xdr
1633  * @xdr: an xdr_stream set up for decoding
1634  * @subbuf: the result buffer
1635  * @nbytes: length of @xdr to extract, in bytes
1636  *
1637  * Sets up @subbuf to represent a portion of @xdr. The portion
1638  * starts at the current offset in @xdr, and extends for a length
1639  * of @nbytes. If this is successful, @xdr is advanced to the next
1640  * XDR data item following that portion.
1641  *
1642  * Return values:
1643  *   %true: @subbuf has been initialized, and @xdr has been advanced.
1644  *   %false: a bounds error has occurred
1645  */
1646 bool xdr_stream_subsegment(struct xdr_stream *xdr, struct xdr_buf *subbuf,
1647                            unsigned int nbytes)
1648 {
1649         unsigned int start = xdr_stream_pos(xdr);
1650         unsigned int remaining, len;
1651 
1652         /* Extract @subbuf and bounds-check the fn arguments */
1653         if (xdr_buf_subsegment(xdr->buf, subbuf, start, nbytes))
1654                 return false;
1655 
1656         /* Advance @xdr by @nbytes */
1657         for (remaining = nbytes; remaining;) {
1658                 if (xdr->p == xdr->end && !xdr_set_next_buffer(xdr))
1659                         return false;
1660 
1661                 len = (char *)xdr->end - (char *)xdr->p;
1662                 if (remaining <= len) {
1663                         xdr->p = (__be32 *)((char *)xdr->p +
1664                                         (remaining + xdr_pad_size(nbytes)));
1665                         break;
1666                 }
1667 
1668                 xdr->p = (__be32 *)((char *)xdr->p + len);
1669                 xdr->end = xdr->p;
1670                 remaining -= len;
1671         }
1672 
1673         xdr_stream_set_pos(xdr, start + nbytes);
1674         return true;
1675 }
1676 EXPORT_SYMBOL_GPL(xdr_stream_subsegment);
1677 
1678 /**
1679  * xdr_buf_trim - lop at most "len" bytes off the end of "buf"
1680  * @buf: buf to be trimmed
1681  * @len: number of bytes to reduce "buf" by
1682  *
1683  * Trim an xdr_buf by the given number of bytes by fixing up the lengths. Note
1684  * that it's possible that we'll trim less than that amount if the xdr_buf is
1685  * too small, or if (for instance) it's all in the head and the parser has
1686  * already read too far into it.
1687  */
1688 void xdr_buf_trim(struct xdr_buf *buf, unsigned int len)
1689 {
1690         size_t cur;
1691         unsigned int trim = len;
1692 
1693         if (buf->tail[0].iov_len) {
1694                 cur = min_t(size_t, buf->tail[0].iov_len, trim);
1695                 buf->tail[0].iov_len -= cur;
1696                 trim -= cur;
1697                 if (!trim)
1698                         goto fix_len;
1699         }
1700 
1701         if (buf->page_len) {
1702                 cur = min_t(unsigned int, buf->page_len, trim);
1703                 buf->page_len -= cur;
1704                 trim -= cur;
1705                 if (!trim)
1706                         goto fix_len;
1707         }
1708 
1709         if (buf->head[0].iov_len) {
1710                 cur = min_t(size_t, buf->head[0].iov_len, trim);
1711                 buf->head[0].iov_len -= cur;
1712                 trim -= cur;
1713         }
1714 fix_len:
1715         buf->len -= (len - trim);
1716 }
1717 EXPORT_SYMBOL_GPL(xdr_buf_trim);
1718 
1719 static void __read_bytes_from_xdr_buf(const struct xdr_buf *subbuf,
1720                                       void *obj, unsigned int len)
1721 {
1722         unsigned int this_len;
1723 
1724         this_len = min_t(unsigned int, len, subbuf->head[0].iov_len);
1725         memcpy(obj, subbuf->head[0].iov_base, this_len);
1726         len -= this_len;
1727         obj += this_len;
1728         this_len = min_t(unsigned int, len, subbuf->page_len);
1729         _copy_from_pages(obj, subbuf->pages, subbuf->page_base, this_len);
1730         len -= this_len;
1731         obj += this_len;
1732         this_len = min_t(unsigned int, len, subbuf->tail[0].iov_len);
1733         memcpy(obj, subbuf->tail[0].iov_base, this_len);
1734 }
1735 
1736 /* obj is assumed to point to allocated memory of size at least len: */
1737 int read_bytes_from_xdr_buf(const struct xdr_buf *buf, unsigned int base,
1738                             void *obj, unsigned int len)
1739 {
1740         struct xdr_buf subbuf;
1741         int status;
1742 
1743         status = xdr_buf_subsegment(buf, &subbuf, base, len);
1744         if (status != 0)
1745                 return status;
1746         __read_bytes_from_xdr_buf(&subbuf, obj, len);
1747         return 0;
1748 }
1749 EXPORT_SYMBOL_GPL(read_bytes_from_xdr_buf);
1750 
1751 static void __write_bytes_to_xdr_buf(const struct xdr_buf *subbuf,
1752                                      void *obj, unsigned int len)
1753 {
1754         unsigned int this_len;
1755 
1756         this_len = min_t(unsigned int, len, subbuf->head[0].iov_len);
1757         memcpy(subbuf->head[0].iov_base, obj, this_len);
1758         len -= this_len;
1759         obj += this_len;
1760         this_len = min_t(unsigned int, len, subbuf->page_len);
1761         _copy_to_pages(subbuf->pages, subbuf->page_base, obj, this_len);
1762         len -= this_len;
1763         obj += this_len;
1764         this_len = min_t(unsigned int, len, subbuf->tail[0].iov_len);
1765         memcpy(subbuf->tail[0].iov_base, obj, this_len);
1766 }
1767 
1768 /* obj is assumed to point to allocated memory of size at least len: */
1769 int write_bytes_to_xdr_buf(const struct xdr_buf *buf, unsigned int base,
1770                            void *obj, unsigned int len)
1771 {
1772         struct xdr_buf subbuf;
1773         int status;
1774 
1775         status = xdr_buf_subsegment(buf, &subbuf, base, len);
1776         if (status != 0)
1777                 return status;
1778         __write_bytes_to_xdr_buf(&subbuf, obj, len);
1779         return 0;
1780 }
1781 EXPORT_SYMBOL_GPL(write_bytes_to_xdr_buf);
1782 
1783 int xdr_decode_word(const struct xdr_buf *buf, unsigned int base, u32 *obj)
1784 {
1785         __be32  raw;
1786         int     status;
1787 
1788         status = read_bytes_from_xdr_buf(buf, base, &raw, sizeof(*obj));
1789         if (status)
1790                 return status;
1791         *obj = be32_to_cpu(raw);
1792         return 0;
1793 }
1794 EXPORT_SYMBOL_GPL(xdr_decode_word);
1795 
1796 int xdr_encode_word(const struct xdr_buf *buf, unsigned int base, u32 obj)
1797 {
1798         __be32  raw = cpu_to_be32(obj);
1799 
1800         return write_bytes_to_xdr_buf(buf, base, &raw, sizeof(obj));
1801 }
1802 EXPORT_SYMBOL_GPL(xdr_encode_word);
1803 
1804 /* Returns 0 on success, or else a negative error code. */
1805 static int xdr_xcode_array2(const struct xdr_buf *buf, unsigned int base,
1806                             struct xdr_array2_desc *desc, int encode)
1807 {
1808         char *elem = NULL, *c;
1809         unsigned int copied = 0, todo, avail_here;
1810         struct page **ppages = NULL;
1811         int err;
1812 
1813         if (encode) {
1814                 if (xdr_encode_word(buf, base, desc->array_len) != 0)
1815                         return -EINVAL;
1816         } else {
1817                 if (xdr_decode_word(buf, base, &desc->array_len) != 0 ||
1818                     desc->array_len > desc->array_maxlen ||
1819                     (unsigned long) base + 4 + desc->array_len *
1820                                     desc->elem_size > buf->len)
1821                         return -EINVAL;
1822         }
1823         base += 4;
1824 
1825         if (!desc->xcode)
1826                 return 0;
1827 
1828         todo = desc->array_len * desc->elem_size;
1829 
1830         /* process head */
1831         if (todo && base < buf->head->iov_len) {
1832                 c = buf->head->iov_base + base;
1833                 avail_here = min_t(unsigned int, todo,
1834                                    buf->head->iov_len - base);
1835                 todo -= avail_here;
1836 
1837                 while (avail_here >= desc->elem_size) {
1838                         err = desc->xcode(desc, c);
1839                         if (err)
1840                                 goto out;
1841                         c += desc->elem_size;
1842                         avail_here -= desc->elem_size;
1843                 }
1844                 if (avail_here) {
1845                         if (!elem) {
1846                                 elem = kmalloc(desc->elem_size, GFP_KERNEL);
1847                                 err = -ENOMEM;
1848                                 if (!elem)
1849                                         goto out;
1850                         }
1851                         if (encode) {
1852                                 err = desc->xcode(desc, elem);
1853                                 if (err)
1854                                         goto out;
1855                                 memcpy(c, elem, avail_here);
1856                         } else
1857                                 memcpy(elem, c, avail_here);
1858                         copied = avail_here;
1859                 }
1860                 base = buf->head->iov_len;  /* align to start of pages */
1861         }
1862 
1863         /* process pages array */
1864         base -= buf->head->iov_len;
1865         if (todo && base < buf->page_len) {
1866                 unsigned int avail_page;
1867 
1868                 avail_here = min(todo, buf->page_len - base);
1869                 todo -= avail_here;
1870 
1871                 base += buf->page_base;
1872                 ppages = buf->pages + (base >> PAGE_SHIFT);
1873                 base &= ~PAGE_MASK;
1874                 avail_page = min_t(unsigned int, PAGE_SIZE - base,
1875                                         avail_here);
1876                 c = kmap(*ppages) + base;
1877 
1878                 while (avail_here) {
1879                         avail_here -= avail_page;
1880                         if (copied || avail_page < desc->elem_size) {
1881                                 unsigned int l = min(avail_page,
1882                                         desc->elem_size - copied);
1883                                 if (!elem) {
1884                                         elem = kmalloc(desc->elem_size,
1885                                                        GFP_KERNEL);
1886                                         err = -ENOMEM;
1887                                         if (!elem)
1888                                                 goto out;
1889                                 }
1890                                 if (encode) {
1891                                         if (!copied) {
1892                                                 err = desc->xcode(desc, elem);
1893                                                 if (err)
1894                                                         goto out;
1895                                         }
1896                                         memcpy(c, elem + copied, l);
1897                                         copied += l;
1898                                         if (copied == desc->elem_size)
1899                                                 copied = 0;
1900                                 } else {
1901                                         memcpy(elem + copied, c, l);
1902                                         copied += l;
1903                                         if (copied == desc->elem_size) {
1904                                                 err = desc->xcode(desc, elem);
1905                                                 if (err)
1906                                                         goto out;
1907                                                 copied = 0;
1908                                         }
1909                                 }
1910                                 avail_page -= l;
1911                                 c += l;
1912                         }
1913                         while (avail_page >= desc->elem_size) {
1914                                 err = desc->xcode(desc, c);
1915                                 if (err)
1916                                         goto out;
1917                                 c += desc->elem_size;
1918                                 avail_page -= desc->elem_size;
1919                         }
1920                         if (avail_page) {
1921                                 unsigned int l = min(avail_page,
1922                                             desc->elem_size - copied);
1923                                 if (!elem) {
1924                                         elem = kmalloc(desc->elem_size,
1925                                                        GFP_KERNEL);
1926                                         err = -ENOMEM;
1927                                         if (!elem)
1928                                                 goto out;
1929                                 }
1930                                 if (encode) {
1931                                         if (!copied) {
1932                                                 err = desc->xcode(desc, elem);
1933                                                 if (err)
1934                                                         goto out;
1935                                         }
1936                                         memcpy(c, elem + copied, l);
1937                                         copied += l;
1938                                         if (copied == desc->elem_size)
1939                                                 copied = 0;
1940                                 } else {
1941                                         memcpy(elem + copied, c, l);
1942                                         copied += l;
1943                                         if (copied == desc->elem_size) {
1944                                                 err = desc->xcode(desc, elem);
1945                                                 if (err)
1946                                                         goto out;
1947                                                 copied = 0;
1948                                         }
1949                                 }
1950                         }
1951                         if (avail_here) {
1952                                 kunmap(*ppages);
1953                                 ppages++;
1954                                 c = kmap(*ppages);
1955                         }
1956 
1957                         avail_page = min(avail_here,
1958                                  (unsigned int) PAGE_SIZE);
1959                 }
1960                 base = buf->page_len;  /* align to start of tail */
1961         }
1962 
1963         /* process tail */
1964         base -= buf->page_len;
1965         if (todo) {
1966                 c = buf->tail->iov_base + base;
1967                 if (copied) {
1968                         unsigned int l = desc->elem_size - copied;
1969 
1970                         if (encode)
1971                                 memcpy(c, elem + copied, l);
1972                         else {
1973                                 memcpy(elem + copied, c, l);
1974                                 err = desc->xcode(desc, elem);
1975                                 if (err)
1976                                         goto out;
1977                         }
1978                         todo -= l;
1979                         c += l;
1980                 }
1981                 while (todo) {
1982                         err = desc->xcode(desc, c);
1983                         if (err)
1984                                 goto out;
1985                         c += desc->elem_size;
1986                         todo -= desc->elem_size;
1987                 }
1988         }
1989         err = 0;
1990 
1991 out:
1992         kfree(elem);
1993         if (ppages)
1994                 kunmap(*ppages);
1995         return err;
1996 }
1997 
1998 int xdr_decode_array2(const struct xdr_buf *buf, unsigned int base,
1999                       struct xdr_array2_desc *desc)
2000 {
2001         if (base >= buf->len)
2002                 return -EINVAL;
2003 
2004         return xdr_xcode_array2(buf, base, desc, 0);
2005 }
2006 EXPORT_SYMBOL_GPL(xdr_decode_array2);
2007 
2008 int xdr_encode_array2(const struct xdr_buf *buf, unsigned int base,
2009                       struct xdr_array2_desc *desc)
2010 {
2011         if ((unsigned long) base + 4 + desc->array_len * desc->elem_size >
2012             buf->head->iov_len + buf->page_len + buf->tail->iov_len)
2013                 return -EINVAL;
2014 
2015         return xdr_xcode_array2(buf, base, desc, 1);
2016 }
2017 EXPORT_SYMBOL_GPL(xdr_encode_array2);
2018 
2019 int xdr_process_buf(const struct xdr_buf *buf, unsigned int offset,
2020                     unsigned int len,
2021                     int (*actor)(struct scatterlist *, void *), void *data)
2022 {
2023         int i, ret = 0;
2024         unsigned int page_len, thislen, page_offset;
2025         struct scatterlist      sg[1];
2026 
2027         sg_init_table(sg, 1);
2028 
2029         if (offset >= buf->head[0].iov_len) {
2030                 offset -= buf->head[0].iov_len;
2031         } else {
2032                 thislen = buf->head[0].iov_len - offset;
2033                 if (thislen > len)
2034                         thislen = len;
2035                 sg_set_buf(sg, buf->head[0].iov_base + offset, thislen);
2036                 ret = actor(sg, data);
2037                 if (ret)
2038                         goto out;
2039                 offset = 0;
2040                 len -= thislen;
2041         }
2042         if (len == 0)
2043                 goto out;
2044 
2045         if (offset >= buf->page_len) {
2046                 offset -= buf->page_len;
2047         } else {
2048                 page_len = buf->page_len - offset;
2049                 if (page_len > len)
2050                         page_len = len;
2051                 len -= page_len;
2052                 page_offset = (offset + buf->page_base) & (PAGE_SIZE - 1);
2053                 i = (offset + buf->page_base) >> PAGE_SHIFT;
2054                 thislen = PAGE_SIZE - page_offset;
2055                 do {
2056                         if (thislen > page_len)
2057                                 thislen = page_len;
2058                         sg_set_page(sg, buf->pages[i], thislen, page_offset);
2059                         ret = actor(sg, data);
2060                         if (ret)
2061                                 goto out;
2062                         page_len -= thislen;
2063                         i++;
2064                         page_offset = 0;
2065                         thislen = PAGE_SIZE;
2066                 } while (page_len != 0);
2067                 offset = 0;
2068         }
2069         if (len == 0)
2070                 goto out;
2071         if (offset < buf->tail[0].iov_len) {
2072                 thislen = buf->tail[0].iov_len - offset;
2073                 if (thislen > len)
2074                         thislen = len;
2075                 sg_set_buf(sg, buf->tail[0].iov_base + offset, thislen);
2076                 ret = actor(sg, data);
2077                 len -= thislen;
2078         }
2079         if (len != 0)
2080                 ret = -EINVAL;
2081 out:
2082         return ret;
2083 }
2084 EXPORT_SYMBOL_GPL(xdr_process_buf);
2085 
2086 /**
2087  * xdr_stream_decode_opaque - Decode variable length opaque
2088  * @xdr: pointer to xdr_stream
2089  * @ptr: location to store opaque data
2090  * @size: size of storage buffer @ptr
2091  *
2092  * Return values:
2093  *   On success, returns size of object stored in *@ptr
2094  *   %-EBADMSG on XDR buffer overflow
2095  *   %-EMSGSIZE on overflow of storage buffer @ptr
2096  */
2097 ssize_t xdr_stream_decode_opaque(struct xdr_stream *xdr, void *ptr, size_t size)
2098 {
2099         ssize_t ret;
2100         void *p;
2101 
2102         ret = xdr_stream_decode_opaque_inline(xdr, &p, size);
2103         if (ret <= 0)
2104                 return ret;
2105         memcpy(ptr, p, ret);
2106         return ret;
2107 }
2108 EXPORT_SYMBOL_GPL(xdr_stream_decode_opaque);
2109 
2110 /**
2111  * xdr_stream_decode_opaque_dup - Decode and duplicate variable length opaque
2112  * @xdr: pointer to xdr_stream
2113  * @ptr: location to store pointer to opaque data
2114  * @maxlen: maximum acceptable object size
2115  * @gfp_flags: GFP mask to use
2116  *
2117  * Return values:
2118  *   On success, returns size of object stored in *@ptr
2119  *   %-EBADMSG on XDR buffer overflow
2120  *   %-EMSGSIZE if the size of the object would exceed @maxlen
2121  *   %-ENOMEM on memory allocation failure
2122  */
2123 ssize_t xdr_stream_decode_opaque_dup(struct xdr_stream *xdr, void **ptr,
2124                 size_t maxlen, gfp_t gfp_flags)
2125 {
2126         ssize_t ret;
2127         void *p;
2128 
2129         ret = xdr_stream_decode_opaque_inline(xdr, &p, maxlen);
2130         if (ret > 0) {
2131                 *ptr = kmemdup(p, ret, gfp_flags);
2132                 if (*ptr != NULL)
2133                         return ret;
2134                 ret = -ENOMEM;
2135         }
2136         *ptr = NULL;
2137         return ret;
2138 }
2139 EXPORT_SYMBOL_GPL(xdr_stream_decode_opaque_dup);
2140 
2141 /**
2142  * xdr_stream_decode_string - Decode variable length string
2143  * @xdr: pointer to xdr_stream
2144  * @str: location to store string
2145  * @size: size of storage buffer @str
2146  *
2147  * Return values:
2148  *   On success, returns length of NUL-terminated string stored in *@str
2149  *   %-EBADMSG on XDR buffer overflow
2150  *   %-EMSGSIZE on overflow of storage buffer @str
2151  */
2152 ssize_t xdr_stream_decode_string(struct xdr_stream *xdr, char *str, size_t size)
2153 {
2154         ssize_t ret;
2155         void *p;
2156 
2157         ret = xdr_stream_decode_opaque_inline(xdr, &p, size);
2158         if (ret > 0) {
2159                 memcpy(str, p, ret);
2160                 str[ret] = '\0';
2161                 return strlen(str);
2162         }
2163         *str = '\0';
2164         return ret;
2165 }
2166 EXPORT_SYMBOL_GPL(xdr_stream_decode_string);
2167 
2168 /**
2169  * xdr_stream_decode_string_dup - Decode and duplicate variable length string
2170  * @xdr: pointer to xdr_stream
2171  * @str: location to store pointer to string
2172  * @maxlen: maximum acceptable string length
2173  * @gfp_flags: GFP mask to use
2174  *
2175  * Return values:
2176  *   On success, returns length of NUL-terminated string stored in *@ptr
2177  *   %-EBADMSG on XDR buffer overflow
2178  *   %-EMSGSIZE if the size of the string would exceed @maxlen
2179  *   %-ENOMEM on memory allocation failure
2180  */
2181 ssize_t xdr_stream_decode_string_dup(struct xdr_stream *xdr, char **str,
2182                 size_t maxlen, gfp_t gfp_flags)
2183 {
2184         void *p;
2185         ssize_t ret;
2186 
2187         ret = xdr_stream_decode_opaque_inline(xdr, &p, maxlen);
2188         if (ret > 0) {
2189                 char *s = kmemdup_nul(p, ret, gfp_flags);
2190                 if (s != NULL) {
2191                         *str = s;
2192                         return strlen(s);
2193                 }
2194                 ret = -ENOMEM;
2195         }
2196         *str = NULL;
2197         return ret;
2198 }
2199 EXPORT_SYMBOL_GPL(xdr_stream_decode_string_dup);
2200 

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