lib/iov_iter.c

   1 #include <linux/export.h>
   2 #include <linux/bvec.h>
   3 #include <linux/uio.h>
   4 #include <linux/pagemap.h>
   5 #include <linux/slab.h>
   6 #include <linux/vmalloc.h>
   7 #include <linux/splice.h>
   8 #include <net/checksum.h>
   9
  10 #define PIPE_PARANOIA /* for now */
  11
  12 #define iterate_iovec(i, n, __v, __p, skip, STEP) {     \
  13         size_t left;                                    \
  14         size_t wanted = n;                              \
  15         __p = i->iov;                                   \
  16         __v.iov_len = min(n, __p->iov_len - skip);      \
  17         if (likely(__v.iov_len)) {                      \
  18                 __v.iov_base = __p->iov_base + skip;    \
  19                 left = (STEP);                          \
  20                 __v.iov_len -= left;                    \
  21                 skip += __v.iov_len;                    \
  22                 n -= __v.iov_len;                       \
  23         } else {                                        \
  24                 left = 0;                               \
  25         }                                               \
  26         while (unlikely(!left && n)) {                  \
  27                 __p++;                                  \
  28                 __v.iov_len = min(n, __p->iov_len);     \
  29                 if (unlikely(!__v.iov_len))             \
  30                         continue;                       \
  31                 __v.iov_base = __p->iov_base;           \
  32                 left = (STEP);                          \
  33                 __v.iov_len -= left;                    \
  34                 skip = __v.iov_len;                     \
  35                 n -= __v.iov_len;                       \
  36         }                                               \
  37         n = wanted - n;                                 \
  38 }
  39
  40 #define iterate_kvec(i, n, __v, __p, skip, STEP) {      \
  41         size_t wanted = n;                              \
  42         __p = i->kvec;                                  \
  43         __v.iov_len = min(n, __p->iov_len - skip);      \
  44         if (likely(__v.iov_len)) {                      \
  45                 __v.iov_base = __p->iov_base + skip;    \
  46                 (void)(STEP);                           \
  47                 skip += __v.iov_len;                    \
  48                 n -= __v.iov_len;                       \
  49         }                                               \
  50         while (unlikely(n)) {                           \
  51                 __p++;                                  \
  52                 __v.iov_len = min(n, __p->iov_len);     \
  53                 if (unlikely(!__v.iov_len))             \
  54                         continue;                       \
  55                 __v.iov_base = __p->iov_base;           \
  56                 (void)(STEP);                           \
  57                 skip = __v.iov_len;                     \
  58                 n -= __v.iov_len;                       \
  59         }                                               \
  60         n = wanted;                                     \
  61 }
  62
  63 #define iterate_bvec(i, n, __v, __bi, skip, STEP) {     \
  64         struct bvec_iter __start;                       \
  65         __start.bi_size = n;                            \
  66         __start.bi_bvec_done = skip;                    \
  67         __start.bi_idx = 0;                             \
  68         for_each_bvec(__v, i->bvec, __bi, __start) {    \
  69                 if (!__v.bv_len)                        \
  70                         continue;                       \
  71                 (void)(STEP);                           \
  72         }                                               \
  73 }
  74
  75 #define iterate_all_kinds(i, n, v, I, B, K) {                   \
  76         if (likely(n)) {                                        \
  77                 size_t skip = i->iov_offset;                    \
  78                 if (unlikely(i->type & ITER_BVEC)) {            \
  79                         struct bio_vec v;                       \
  80                         struct bvec_iter __bi;                  \
  81                         iterate_bvec(i, n, v, __bi, skip, (B))  \
  82                 } else if (unlikely(i->type & ITER_KVEC)) {     \
  83                         const struct kvec *kvec;                \
  84                         struct kvec v;                          \
  85                         iterate_kvec(i, n, v, kvec, skip, (K))  \
  86                 } else {                                        \
  87                         const struct iovec *iov;                \
  88                         struct iovec v;                         \
  89                         iterate_iovec(i, n, v, iov, skip, (I))  \
  90                 }                                               \
  91         }                                                       \
  92 }
  93
  94 #define iterate_and_advance(i, n, v, I, B, K) {                 \
  95         if (unlikely(i->count < n))                             \
  96                 n = i->count;                                   \
  97         if (i->count) {                                         \
  98                 size_t skip = i->iov_offset;                    \
  99                 if (unlikely(i->type & ITER_BVEC)) {            \
 100                         const struct bio_vec *bvec = i->bvec;   \
 101                         struct bio_vec v;                       \
 102                         struct bvec_iter __bi;                  \
 103                         iterate_bvec(i, n, v, __bi, skip, (B))  \
 104                         i->bvec = __bvec_iter_bvec(i->bvec, __bi);      \
 105                         i->nr_segs -= i->bvec - bvec;           \
 106                         skip = __bi.bi_bvec_done;               \
 107                 } else if (unlikely(i->type & ITER_KVEC)) {     \
 108                         const struct kvec *kvec;                \
 109                         struct kvec v;                          \
 110                         iterate_kvec(i, n, v, kvec, skip, (K))  \
 111                         if (skip == kvec->iov_len) {            \
 112                                 kvec++;                         \
 113                                 skip = 0;                       \
 114                         }                                       \
 115                         i->nr_segs -= kvec - i->kvec;           \
 116                         i->kvec = kvec;                         \
 117                 } else {                                        \
 118                         const struct iovec *iov;                \
 119                         struct iovec v;                         \
 120                         iterate_iovec(i, n, v, iov, skip, (I))  \
 121                         if (skip == iov->iov_len) {             \
 122                                 iov++;                          \
 123                                 skip = 0;                       \
 124                         }                                       \
 125                         i->nr_segs -= iov - i->iov;             \
 126                         i->iov = iov;                           \
 127                 }                                               \
 128                 i->count -= n;                                  \
 129                 i->iov_offset = skip;                           \
 130         }                                                       \
 131 }
 132
 133 static int copyout(void __user *to, const void *from, size_t n)
 134 {
 135         if (access_ok(VERIFY_WRITE, to, n)) {
 136                 kasan_check_read(from, n);
 137                 n = raw_copy_to_user(to, from, n);
 138         }
 139         return n;
 140 }
 141
 142 static int copyin(void *to, const void __user *from, size_t n)
 143 {
 144         if (access_ok(VERIFY_READ, from, n)) {
 145                 kasan_check_write(to, n);
 146                 n = raw_copy_from_user(to, from, n);
 147         }
 148         return n;
 149 }
 150
 151 static size_t copy_page_to_iter_iovec(struct page *page, size_t offset, size_t bytes,
 152                          struct iov_iter *i)
 153 {
 154         size_t skip, copy, left, wanted;
 155         const struct iovec *iov;
 156         char __user *buf;
 157         void *kaddr, *from;
 158
 159         if (unlikely(bytes > i->count))
 160                 bytes = i->count;
 161
 162         if (unlikely(!bytes))
 163                 return 0;
 164
 165         might_fault();
 166         wanted = bytes;
 167         iov = i->iov;
 168         skip = i->iov_offset;
 169         buf = iov->iov_base + skip;
 170         copy = min(bytes, iov->iov_len - skip);
 171
 172         if (IS_ENABLED(CONFIG_HIGHMEM) && !fault_in_pages_writeable(buf, copy)) {
 173                 kaddr = kmap_atomic(page);
 174                 from = kaddr + offset;
 175
 176                 /* first chunk, usually the only one */
 177                 left = copyout(buf, from, copy);
 178                 copy -= left;
 179                 skip += copy;
 180                 from += copy;
 181                 bytes -= copy;
 182
 183                 while (unlikely(!left && bytes)) {
 184                         iov++;
 185                         buf = iov->iov_base;
 186                         copy = min(bytes, iov->iov_len);
 187                         left = copyout(buf, from, copy);
 188                         copy -= left;
 189                         skip = copy;
 190                         from += copy;
 191                         bytes -= copy;
 192                 }
 193                 if (likely(!bytes)) {
 194                         kunmap_atomic(kaddr);
 195                         goto done;
 196                 }
 197                 offset = from - kaddr;
 198                 buf += copy;
 199                 kunmap_atomic(kaddr);
 200                 copy = min(bytes, iov->iov_len - skip);
 201         }
 202         /* Too bad - revert to non-atomic kmap */
 203
 204         kaddr = kmap(page);
 205         from = kaddr + offset;
 206         left = copyout(buf, from, copy);
 207         copy -= left;
 208         skip += copy;
 209         from += copy;
 210         bytes -= copy;
 211         while (unlikely(!left && bytes)) {
 212                 iov++;
 213                 buf = iov->iov_base;
 214                 copy = min(bytes, iov->iov_len);
 215                 left = copyout(buf, from, copy);
 216                 copy -= left;
 217                 skip = copy;
 218                 from += copy;
 219                 bytes -= copy;
 220         }
 221         kunmap(page);
 222
 223 done:
 224         if (skip == iov->iov_len) {
 225                 iov++;
 226                 skip = 0;
 227         }
 228         i->count -= wanted - bytes;
 229         i->nr_segs -= iov - i->iov;
 230         i->iov = iov;
 231         i->iov_offset = skip;
 232         return wanted - bytes;
 233 }
 234
 235 static size_t copy_page_from_iter_iovec(struct page *page, size_t offset, size_t bytes,
 236                          struct iov_iter *i)
 237 {
 238         size_t skip, copy, left, wanted;
 239         const struct iovec *iov;
 240         char __user *buf;
 241         void *kaddr, *to;
 242
 243         if (unlikely(bytes > i->count))
 244                 bytes = i->count;
 245
 246         if (unlikely(!bytes))
 247                 return 0;
 248
 249         might_fault();
 250         wanted = bytes;
 251         iov = i->iov;
 252         skip = i->iov_offset;
 253         buf = iov->iov_base + skip;
 254         copy = min(bytes, iov->iov_len - skip);
 255
 256         if (IS_ENABLED(CONFIG_HIGHMEM) && !fault_in_pages_readable(buf, copy)) {
 257                 kaddr = kmap_atomic(page);
 258                 to = kaddr + offset;
 259
 260                 /* first chunk, usually the only one */
 261                 left = copyin(to, buf, copy);
 262                 copy -= left;
 263                 skip += copy;
 264                 to += copy;
 265                 bytes -= copy;
 266
 267                 while (unlikely(!left && bytes)) {
 268                         iov++;
 269                         buf = iov->iov_base;
 270                         copy = min(bytes, iov->iov_len);
 271                         left = copyin(to, buf, copy);
 272                         copy -= left;
 273                         skip = copy;
 274                         to += copy;
 275                         bytes -= copy;
 276                 }
 277                 if (likely(!bytes)) {
 278                         kunmap_atomic(kaddr);
 279                         goto done;
 280                 }
 281                 offset = to - kaddr;
 282                 buf += copy;
 283                 kunmap_atomic(kaddr);
 284                 copy = min(bytes, iov->iov_len - skip);
 285         }
 286         /* Too bad - revert to non-atomic kmap */
 287
 288         kaddr = kmap(page);
 289         to = kaddr + offset;
 290         left = copyin(to, buf, copy);
 291         copy -= left;
 292         skip += copy;
 293         to += copy;
 294         bytes -= copy;
 295         while (unlikely(!left && bytes)) {
 296                 iov++;
 297                 buf = iov->iov_base;
 298                 copy = min(bytes, iov->iov_len);
 299                 left = copyin(to, buf, copy);
 300                 copy -= left;
 301                 skip = copy;
 302                 to += copy;
 303                 bytes -= copy;
 304         }
 305         kunmap(page);
 306
 307 done:
 308         if (skip == iov->iov_len) {
 309                 iov++;
 310                 skip = 0;
 311         }
 312         i->count -= wanted - bytes;
 313         i->nr_segs -= iov - i->iov;
 314         i->iov = iov;
 315         i->iov_offset = skip;
 316         return wanted - bytes;
 317 }
 318
 319 #ifdef PIPE_PARANOIA
 320 static bool sanity(const struct iov_iter *i)
 321 {
 322         struct pipe_inode_info *pipe = i->pipe;
 323         int idx = i->idx;
 324         int next = pipe->curbuf + pipe->nrbufs;
 325         if (i->iov_offset) {
 326                 struct pipe_buffer *p;
 327                 if (unlikely(!pipe->nrbufs))
 328                         goto Bad;       // pipe must be non-empty
 329                 if (unlikely(idx != ((next - 1) & (pipe->buffers - 1))))
 330                         goto Bad;       // must be at the last buffer...
 331
 332                 p = &pipe->bufs[idx];
 333                 if (unlikely(p->offset + p->len != i->iov_offset))
 334                         goto Bad;       // ... at the end of segment
 335         } else {
 336                 if (idx != (next & (pipe->buffers - 1)))
 337                         goto Bad;       // must be right after the last buffer
 338         }
 339         return true;
 340 Bad:
 341         printk(KERN_ERR "idx = %d, offset = %zd\n", i->idx, i->iov_offset);
 342         printk(KERN_ERR "curbuf = %d, nrbufs = %d, buffers = %d\n",
 343                         pipe->curbuf, pipe->nrbufs, pipe->buffers);
 344         for (idx = 0; idx < pipe->buffers; idx++)
 345                 printk(KERN_ERR "[%p %p %d %d]\n",
 346                         pipe->bufs[idx].ops,
 347                         pipe->bufs[idx].page,
 348                         pipe->bufs[idx].offset,
 349                         pipe->bufs[idx].len);
 350         WARN_ON(1);
 351         return false;
 352 }
 353 #else
 354 #define sanity(i) true
 355 #endif
 356
 357 static inline int next_idx(int idx, struct pipe_inode_info *pipe)
 358 {
 359         return (idx + 1) & (pipe->buffers - 1);
 360 }
 361
 362 static size_t copy_page_to_iter_pipe(struct page *page, size_t offset, size_t bytes,
 363                          struct iov_iter *i)
 364 {
 365         struct pipe_inode_info *pipe = i->pipe;
 366         struct pipe_buffer *buf;
 367         size_t off;
 368         int idx;
 369
 370         if (unlikely(bytes > i->count))
 371                 bytes = i->count;
 372
 373         if (unlikely(!bytes))
 374                 return 0;
 375
 376         if (!sanity(i))
 377                 return 0;
 378
 379         off = i->iov_offset;
 380         idx = i->idx;
 381         buf = &pipe->bufs[idx];
 382         if (off) {
 383                 if (offset == off && buf->page == page) {
 384                         /* merge with the last one */
 385                         buf->len += bytes;
 386                         i->iov_offset += bytes;
 387                         goto out;
 388                 }
 389                 idx = next_idx(idx, pipe);
 390                 buf = &pipe->bufs[idx];
 391         }
 392         if (idx == pipe->curbuf && pipe->nrbufs)
 393                 return 0;
 394         pipe->nrbufs++;
 395         buf->ops = &page_cache_pipe_buf_ops;
 396         get_page(buf->page = page);
 397         buf->offset = offset;
 398         buf->len = bytes;
 399         i->iov_offset = offset + bytes;
 400         i->idx = idx;
 401 out:
 402         i->count -= bytes;
 403         return bytes;
 404 }
 405
 406 /*
 407  * Fault in one or more iovecs of the given iov_iter, to a maximum length of
 408  * bytes.  For each iovec, fault in each page that constitutes the iovec.
 409  *
 410  * Return 0 on success, or non-zero if the memory could not be accessed (i.e.
 411  * because it is an invalid address).
 412  */
 413 int iov_iter_fault_in_readable(struct iov_iter *i, size_t bytes)
 414 {
 415         size_t skip = i->iov_offset;
 416         const struct iovec *iov;
 417         int err;
 418         struct iovec v;
 419
 420         if (!(i->type & (ITER_BVEC|ITER_KVEC))) {
 421                 iterate_iovec(i, bytes, v, iov, skip, ({
 422                         err = fault_in_pages_readable(v.iov_base, v.iov_len);
 423                         if (unlikely(err))
 424                         return err;
 425                 0;}))
 426         }
 427         return 0;
 428 }
 429 EXPORT_SYMBOL(iov_iter_fault_in_readable);
 430
 431 void iov_iter_init(struct iov_iter *i, int direction,
 432                         const struct iovec *iov, unsigned long nr_segs,
 433                         size_t count)
 434 {
 435         /* It will get better.  Eventually... */
 436         if (uaccess_kernel()) {
 437                 direction |= ITER_KVEC;
 438                 i->type = direction;
 439                 i->kvec = (struct kvec *)iov;
 440         } else {
 441                 i->type = direction;
 442                 i->iov = iov;
 443         }
 444         i->nr_segs = nr_segs;
 445         i->iov_offset = 0;
 446         i->count = count;
 447 }
 448 EXPORT_SYMBOL(iov_iter_init);
 449
 450 static void memcpy_from_page(char *to, struct page *page, size_t offset, size_t len)
 451 {
 452         char *from = kmap_atomic(page);
 453         memcpy(to, from + offset, len);
 454         kunmap_atomic(from);
 455 }
 456
 457 static void memcpy_to_page(struct page *page, size_t offset, const char *from, size_t len)
 458 {
 459         char *to = kmap_atomic(page);
 460         memcpy(to + offset, from, len);
 461         kunmap_atomic(to);
 462 }
 463
 464 static void memzero_page(struct page *page, size_t offset, size_t len)
 465 {
 466         char *addr = kmap_atomic(page);
 467         memset(addr + offset, 0, len);
 468         kunmap_atomic(addr);
 469 }
 470
 471 static inline bool allocated(struct pipe_buffer *buf)
 472 {
 473         return buf->ops == &default_pipe_buf_ops;
 474 }
 475
 476 static inline void data_start(const struct iov_iter *i, int *idxp, size_t *offp)
 477 {
 478         size_t off = i->iov_offset;
 479         int idx = i->idx;
 480         if (off && (!allocated(&i->pipe->bufs[idx]) || off == PAGE_SIZE)) {
 481                 idx = next_idx(idx, i->pipe);
 482                 off = 0;
 483         }
 484         *idxp = idx;
 485         *offp = off;
 486 }
 487
 488 static size_t push_pipe(struct iov_iter *i, size_t size,
 489                         int *idxp, size_t *offp)
 490 {
 491         struct pipe_inode_info *pipe = i->pipe;
 492         size_t off;
 493         int idx;
 494         ssize_t left;
 495
 496         if (unlikely(size > i->count))
 497                 size = i->count;
 498         if (unlikely(!size))
 499                 return 0;
 500
 501         left = size;
 502         data_start(i, &idx, &off);
 503         *idxp = idx;
 504         *offp = off;
 505         if (off) {
 506                 left -= PAGE_SIZE - off;
 507                 if (left <= 0) {
 508                         pipe->bufs[idx].len += size;
 509                         return size;
 510                 }
 511                 pipe->bufs[idx].len = PAGE_SIZE;
 512                 idx = next_idx(idx, pipe);
 513         }
 514         while (idx != pipe->curbuf || !pipe->nrbufs) {
 515                 struct page *page = alloc_page(GFP_USER);
 516                 if (!page)
 517                         break;
 518                 pipe->nrbufs++;
 519                 pipe->bufs[idx].ops = &default_pipe_buf_ops;
 520                 pipe->bufs[idx].page = page;
 521                 pipe->bufs[idx].offset = 0;
 522                 if (left <= PAGE_SIZE) {
 523                         pipe->bufs[idx].len = left;
 524                         return size;
 525                 }
 526                 pipe->bufs[idx].len = PAGE_SIZE;
 527                 left -= PAGE_SIZE;
 528                 idx = next_idx(idx, pipe);
 529         }
 530         return size - left;
 531 }
 532
 533 static size_t copy_pipe_to_iter(const void *addr, size_t bytes,
 534                                 struct iov_iter *i)
 535 {
 536         struct pipe_inode_info *pipe = i->pipe;
 537         size_t n, off;
 538         int idx;
 539
 540         if (!sanity(i))
 541                 return 0;
 542
 543         bytes = n = push_pipe(i, bytes, &idx, &off);
 544         if (unlikely(!n))
 545                 return 0;
 546         for ( ; n; idx = next_idx(idx, pipe), off = 0) {
 547                 size_t chunk = min_t(size_t, n, PAGE_SIZE - off);
 548                 memcpy_to_page(pipe->bufs[idx].page, off, addr, chunk);
 549                 i->idx = idx;
 550                 i->iov_offset = off + chunk;
 551                 n -= chunk;
 552                 addr += chunk;
 553         }
 554         i->count -= bytes;
 555         return bytes;
 556 }
 557
 558 size_t _copy_to_iter(const void *addr, size_t bytes, struct iov_iter *i)
 559 {
 560         const char *from = addr;
 561         if (unlikely(i->type & ITER_PIPE))
 562                 return copy_pipe_to_iter(addr, bytes, i);
 563         if (iter_is_iovec(i))
 564                 might_fault();
 565         iterate_and_advance(i, bytes, v,
 566                 copyout(v.iov_base, (from += v.iov_len) - v.iov_len, v.iov_len),
 567                 memcpy_to_page(v.bv_page, v.bv_offset,
 568                                (from += v.bv_len) - v.bv_len, v.bv_len),
 569                 memcpy(v.iov_base, (from += v.iov_len) - v.iov_len, v.iov_len)
 570         )
 571
 572         return bytes;
 573 }
 574 EXPORT_SYMBOL(_copy_to_iter);
 575
 576 size_t _copy_from_iter(void *addr, size_t bytes, struct iov_iter *i)
 577 {
 578         char *to = addr;
 579         if (unlikely(i->type & ITER_PIPE)) {
 580                 WARN_ON(1);
 581                 return 0;
 582         }
 583         if (iter_is_iovec(i))
 584                 might_fault();
 585         iterate_and_advance(i, bytes, v,
 586                 copyin((to += v.iov_len) - v.iov_len, v.iov_base, v.iov_len),
 587                 memcpy_from_page((to += v.bv_len) - v.bv_len, v.bv_page,
 588                                  v.bv_offset, v.bv_len),
 589                 memcpy((to += v.iov_len) - v.iov_len, v.iov_base, v.iov_len)
 590         )
 591
 592         return bytes;
 593 }
 594 EXPORT_SYMBOL(_copy_from_iter);
 595
 596 bool _copy_from_iter_full(void *addr, size_t bytes, struct iov_iter *i)
 597 {
 598         char *to = addr;
 599         if (unlikely(i->type & ITER_PIPE)) {
 600                 WARN_ON(1);
 601                 return false;
 602         }
 603         if (unlikely(i->count < bytes))
 604                 return false;
 605
 606         if (iter_is_iovec(i))
 607                 might_fault();
 608         iterate_all_kinds(i, bytes, v, ({
 609                 if (copyin((to += v.iov_len) - v.iov_len,
 610                                       v.iov_base, v.iov_len))
 611                         return false;
 612                 0;}),
 613                 memcpy_from_page((to += v.bv_len) - v.bv_len, v.bv_page,
 614                                  v.bv_offset, v.bv_len),
 615                 memcpy((to += v.iov_len) - v.iov_len, v.iov_base, v.iov_len)
 616         )
 617
 618         iov_iter_advance(i, bytes);
 619         return true;
 620 }
 621 EXPORT_SYMBOL(_copy_from_iter_full);
 622
 623 size_t _copy_from_iter_nocache(void *addr, size_t bytes, struct iov_iter *i)
 624 {
 625         char *to = addr;
 626         if (unlikely(i->type & ITER_PIPE)) {
 627                 WARN_ON(1);
 628                 return 0;
 629         }
 630         iterate_and_advance(i, bytes, v,
 631                 __copy_from_user_inatomic_nocache((to += v.iov_len) - v.iov_len,
 632                                          v.iov_base, v.iov_len),
 633                 memcpy_from_page((to += v.bv_len) - v.bv_len, v.bv_page,
 634                                  v.bv_offset, v.bv_len),
 635                 memcpy((to += v.iov_len) - v.iov_len, v.iov_base, v.iov_len)
 636         )
 637
 638         return bytes;
 639 }
 640 EXPORT_SYMBOL(_copy_from_iter_nocache);
 641
 642 #ifdef CONFIG_ARCH_HAS_UACCESS_FLUSHCACHE
 643 size_t _copy_from_iter_flushcache(void *addr, size_t bytes, struct iov_iter *i)
 644 {
 645         char *to = addr;
 646         if (unlikely(i->type & ITER_PIPE)) {
 647                 WARN_ON(1);
 648                 return 0;
 649         }
 650         iterate_and_advance(i, bytes, v,
 651                 __copy_from_user_flushcache((to += v.iov_len) - v.iov_len,
 652                                          v.iov_base, v.iov_len),
 653                 memcpy_page_flushcache((to += v.bv_len) - v.bv_len, v.bv_page,
 654                                  v.bv_offset, v.bv_len),
 655                 memcpy_flushcache((to += v.iov_len) - v.iov_len, v.iov_base,
 656                         v.iov_len)
 657         )
 658
 659         return bytes;
 660 }
 661 EXPORT_SYMBOL_GPL(_copy_from_iter_flushcache);
 662 #endif
 663
 664 bool _copy_from_iter_full_nocache(void *addr, size_t bytes, struct iov_iter *i)
 665 {
 666         char *to = addr;
 667         if (unlikely(i->type & ITER_PIPE)) {
 668                 WARN_ON(1);
 669                 return false;
 670         }
 671         if (unlikely(i->count < bytes))
 672                 return false;
 673         iterate_all_kinds(i, bytes, v, ({
 674                 if (__copy_from_user_inatomic_nocache((to += v.iov_len) - v.iov_len,
 675                                              v.iov_base, v.iov_len))
 676                         return false;
 677                 0;}),
 678                 memcpy_from_page((to += v.bv_len) - v.bv_len, v.bv_page,
 679                                  v.bv_offset, v.bv_len),
 680                 memcpy((to += v.iov_len) - v.iov_len, v.iov_base, v.iov_len)
 681         )
 682
 683         iov_iter_advance(i, bytes);
 684         return true;
 685 }
 686 EXPORT_SYMBOL(_copy_from_iter_full_nocache);
 687
 688 static inline bool page_copy_sane(struct page *page, size_t offset, size_t n)
 689 {
 690         size_t v = n + offset;
 691         if (likely(n <= v && v <= (PAGE_SIZE << compound_order(page))))
 692                 return true;
 693         WARN_ON(1);
 694         return false;
 695 }
 696
 697 size_t copy_page_to_iter(struct page *page, size_t offset, size_t bytes,
 698                          struct iov_iter *i)
 699 {
 700         if (unlikely(!page_copy_sane(page, offset, bytes)))
 701                 return 0;
 702         if (i->type & (ITER_BVEC|ITER_KVEC)) {
 703                 void *kaddr = kmap_atomic(page);
 704                 size_t wanted = copy_to_iter(kaddr + offset, bytes, i);
 705                 kunmap_atomic(kaddr);
 706                 return wanted;
 707         } else if (likely(!(i->type & ITER_PIPE)))
 708                 return copy_page_to_iter_iovec(page, offset, bytes, i);
 709         else
 710                 return copy_page_to_iter_pipe(page, offset, bytes, i);
 711 }
 712 EXPORT_SYMBOL(copy_page_to_iter);
 713
 714 size_t copy_page_from_iter(struct page *page, size_t offset, size_t bytes,
 715                          struct iov_iter *i)
 716 {
 717         if (unlikely(!page_copy_sane(page, offset, bytes)))
 718                 return 0;
 719         if (unlikely(i->type & ITER_PIPE)) {
 720                 WARN_ON(1);
 721                 return 0;
 722         }
 723         if (i->type & (ITER_BVEC|ITER_KVEC)) {
 724                 void *kaddr = kmap_atomic(page);
 725                 size_t wanted = _copy_from_iter(kaddr + offset, bytes, i);
 726                 kunmap_atomic(kaddr);
 727                 return wanted;
 728         } else
 729                 return copy_page_from_iter_iovec(page, offset, bytes, i);
 730 }
 731 EXPORT_SYMBOL(copy_page_from_iter);
 732
 733 static size_t pipe_zero(size_t bytes, struct iov_iter *i)
 734 {
 735         struct pipe_inode_info *pipe = i->pipe;
 736         size_t n, off;
 737         int idx;
 738
 739         if (!sanity(i))
 740                 return 0;
 741
 742         bytes = n = push_pipe(i, bytes, &idx, &off);
 743         if (unlikely(!n))
 744                 return 0;
 745
 746         for ( ; n; idx = next_idx(idx, pipe), off = 0) {
 747                 size_t chunk = min_t(size_t, n, PAGE_SIZE - off);
 748                 memzero_page(pipe->bufs[idx].page, off, chunk);
 749                 i->idx = idx;
 750                 i->iov_offset = off + chunk;
 751                 n -= chunk;
 752         }
 753         i->count -= bytes;
 754         return bytes;
 755 }
 756
 757 size_t iov_iter_zero(size_t bytes, struct iov_iter *i)
 758 {
 759         if (unlikely(i->type & ITER_PIPE))
 760                 return pipe_zero(bytes, i);
 761         iterate_and_advance(i, bytes, v,
 762                 clear_user(v.iov_base, v.iov_len),
 763                 memzero_page(v.bv_page, v.bv_offset, v.bv_len),
 764                 memset(v.iov_base, 0, v.iov_len)
 765         )
 766
 767         return bytes;
 768 }
 769 EXPORT_SYMBOL(iov_iter_zero);
 770
 771 size_t iov_iter_copy_from_user_atomic(struct page *page,
 772                 struct iov_iter *i, unsigned long offset, size_t bytes)
 773 {
 774         char *kaddr = kmap_atomic(page), *p = kaddr + offset;
 775         if (unlikely(!page_copy_sane(page, offset, bytes))) {
 776                 kunmap_atomic(kaddr);
 777                 return 0;
 778         }
 779         if (unlikely(i->type & ITER_PIPE)) {
 780                 kunmap_atomic(kaddr);
 781                 WARN_ON(1);
 782                 return 0;
 783         }
 784         iterate_all_kinds(i, bytes, v,
 785                 copyin((p += v.iov_len) - v.iov_len, v.iov_base, v.iov_len),
 786                 memcpy_from_page((p += v.bv_len) - v.bv_len, v.bv_page,
 787                                  v.bv_offset, v.bv_len),
 788                 memcpy((p += v.iov_len) - v.iov_len, v.iov_base, v.iov_len)
 789         )
 790         kunmap_atomic(kaddr);
 791         return bytes;
 792 }
 793 EXPORT_SYMBOL(iov_iter_copy_from_user_atomic);
 794
 795 static inline void pipe_truncate(struct iov_iter *i)
 796 {
 797         struct pipe_inode_info *pipe = i->pipe;
 798         if (pipe->nrbufs) {
 799                 size_t off = i->iov_offset;
 800                 int idx = i->idx;
 801                 int nrbufs = (idx - pipe->curbuf) & (pipe->buffers - 1);
 802                 if (off) {
 803                         pipe->bufs[idx].len = off - pipe->bufs[idx].offset;
 804                         idx = next_idx(idx, pipe);
 805                         nrbufs++;
 806                 }
 807                 while (pipe->nrbufs > nrbufs) {
 808                         pipe_buf_release(pipe, &pipe->bufs[idx]);
 809                         idx = next_idx(idx, pipe);
 810                         pipe->nrbufs--;
 811                 }
 812         }
 813 }
 814
 815 static void pipe_advance(struct iov_iter *i, size_t size)
 816 {
 817         struct pipe_inode_info *pipe = i->pipe;
 818         if (unlikely(i->count < size))
 819                 size = i->count;
 820         if (size) {
 821                 struct pipe_buffer *buf;
 822                 size_t off = i->iov_offset, left = size;
 823                 int idx = i->idx;
 824                 if (off) /* make it relative to the beginning of buffer */
 825                         left += off - pipe->bufs[idx].offset;
 826                 while (1) {
 827                         buf = &pipe->bufs[idx];
 828                         if (left <= buf->len)
 829                                 break;
 830                         left -= buf->len;
 831                         idx = next_idx(idx, pipe);
 832                 }
 833                 i->idx = idx;
 834                 i->iov_offset = buf->offset + left;
 835         }
 836         i->count -= size;
 837         /* ... and discard everything past that point */
 838         pipe_truncate(i);
 839 }
 840
 841 void iov_iter_advance(struct iov_iter *i, size_t size)
 842 {
 843         if (unlikely(i->type & ITER_PIPE)) {
 844                 pipe_advance(i, size);
 845                 return;
 846         }
 847         iterate_and_advance(i, size, v, 0, 0, 0)
 848 }
 849 EXPORT_SYMBOL(iov_iter_advance);
 850
 851 void iov_iter_revert(struct iov_iter *i, size_t unroll)
 852 {
 853         if (!unroll)
 854                 return;
 855         if (WARN_ON(unroll > MAX_RW_COUNT))
 856                 return;
 857         i->count += unroll;
 858         if (unlikely(i->type & ITER_PIPE)) {
 859                 struct pipe_inode_info *pipe = i->pipe;
 860                 int idx = i->idx;
 861                 size_t off = i->iov_offset;
 862                 while (1) {
 863                         size_t n = off - pipe->bufs[idx].offset;
 864                         if (unroll < n) {
 865                                 off -= unroll;
 866                                 break;
 867                         }
 868                         unroll -= n;
 869                         if (!unroll && idx == i->start_idx) {
 870                                 off = 0;
 871                                 break;
 872                         }
 873                         if (!idx--)
 874                                 idx = pipe->buffers - 1;
 875                         off = pipe->bufs[idx].offset + pipe->bufs[idx].len;
 876                 }
 877                 i->iov_offset = off;
 878                 i->idx = idx;
 879                 pipe_truncate(i);
 880                 return;
 881         }
 882         if (unroll <= i->iov_offset) {
 883                 i->iov_offset -= unroll;
 884                 return;
 885         }
 886         unroll -= i->iov_offset;
 887         if (i->type & ITER_BVEC) {
 888                 const struct bio_vec *bvec = i->bvec;
 889                 while (1) {
 890                         size_t n = (--bvec)->bv_len;
 891                         i->nr_segs++;
 892                         if (unroll <= n) {
 893                                 i->bvec = bvec;
 894                                 i->iov_offset = n - unroll;
 895                                 return;
 896                         }
 897                         unroll -= n;
 898                 }
 899         } else { /* same logics for iovec and kvec */
 900                 const struct iovec *iov = i->iov;
 901                 while (1) {
 902                         size_t n = (--iov)->iov_len;
 903                         i->nr_segs++;
 904                         if (unroll <= n) {
 905                                 i->iov = iov;
 906                                 i->iov_offset = n - unroll;
 907                                 return;
 908                         }
 909                         unroll -= n;
 910                 }
 911         }
 912 }
 913 EXPORT_SYMBOL(iov_iter_revert);
 914
 915 /*
 916  * Return the count of just the current iov_iter segment.
 917  */
 918 size_t iov_iter_single_seg_count(const struct iov_iter *i)
 919 {
 920         if (unlikely(i->type & ITER_PIPE))
 921                 return i->count;        // it is a silly place, anyway
 922         if (i->nr_segs == 1)
 923                 return i->count;
 924         else if (i->type & ITER_BVEC)
 925                 return min(i->count, i->bvec->bv_len - i->iov_offset);
 926         else
 927                 return min(i->count, i->iov->iov_len - i->iov_offset);
 928 }
 929 EXPORT_SYMBOL(iov_iter_single_seg_count);
 930
 931 void iov_iter_kvec(struct iov_iter *i, int direction,
 932                         const struct kvec *kvec, unsigned long nr_segs,
 933                         size_t count)
 934 {
 935         BUG_ON(!(direction & ITER_KVEC));
 936         i->type = direction;
 937         i->kvec = kvec;
 938         i->nr_segs = nr_segs;
 939         i->iov_offset = 0;
 940         i->count = count;
 941 }
 942 EXPORT_SYMBOL(iov_iter_kvec);
 943
 944 void iov_iter_bvec(struct iov_iter *i, int direction,
 945                         const struct bio_vec *bvec, unsigned long nr_segs,
 946                         size_t count)
 947 {
 948         BUG_ON(!(direction & ITER_BVEC));
 949         i->type = direction;
 950         i->bvec = bvec;
 951         i->nr_segs = nr_segs;
 952         i->iov_offset = 0;
 953         i->count = count;
 954 }
 955 EXPORT_SYMBOL(iov_iter_bvec);
 956
 957 void iov_iter_pipe(struct iov_iter *i, int direction,
 958                         struct pipe_inode_info *pipe,
 959                         size_t count)
 960 {
 961         BUG_ON(direction != ITER_PIPE);
 962         WARN_ON(pipe->nrbufs == pipe->buffers);
 963         i->type = direction;
 964         i->pipe = pipe;
 965         i->idx = (pipe->curbuf + pipe->nrbufs) & (pipe->buffers - 1);
 966         i->iov_offset = 0;
 967         i->count = count;
 968         i->start_idx = i->idx;
 969 }
 970 EXPORT_SYMBOL(iov_iter_pipe);
 971
 972 unsigned long iov_iter_alignment(const struct iov_iter *i)
 973 {
 974         unsigned long res = 0;
 975         size_t size = i->count;
 976
 977         if (unlikely(i->type & ITER_PIPE)) {
 978                 if (size && i->iov_offset && allocated(&i->pipe->bufs[i->idx]))
 979                         return size | i->iov_offset;
 980                 return size;
 981         }
 982         iterate_all_kinds(i, size, v,
 983                 (res |= (unsigned long)v.iov_base | v.iov_len, 0),
 984                 res |= v.bv_offset | v.bv_len,
 985                 res |= (unsigned long)v.iov_base | v.iov_len
 986         )
 987         return res;
 988 }
 989 EXPORT_SYMBOL(iov_iter_alignment);
 990
 991 unsigned long iov_iter_gap_alignment(const struct iov_iter *i)
 992 {
 993         unsigned long res = 0;
 994         size_t size = i->count;
 995
 996         if (unlikely(i->type & ITER_PIPE)) {
 997                 WARN_ON(1);
 998                 return ~0U;
 999         }
1000
1001         iterate_all_kinds(i, size, v,
1002                 (res |= (!res ? 0 : (unsigned long)v.iov_base) |
1003                         (size != v.iov_len ? size : 0), 0),
1004                 (res |= (!res ? 0 : (unsigned long)v.bv_offset) |
1005                         (size != v.bv_len ? size : 0)),
1006                 (res |= (!res ? 0 : (unsigned long)v.iov_base) |
1007                         (size != v.iov_len ? size : 0))
1008                 );
1009         return res;
1010 }
1011 EXPORT_SYMBOL(iov_iter_gap_alignment);
1012
1013 static inline size_t __pipe_get_pages(struct iov_iter *i,
1014                                 size_t maxsize,
1015                                 struct page **pages,
1016                                 int idx,
1017                                 size_t *start)
1018 {
1019         struct pipe_inode_info *pipe = i->pipe;
1020         ssize_t n = push_pipe(i, maxsize, &idx, start);
1021         if (!n)
1022                 return -EFAULT;
1023
1024         maxsize = n;
1025         n += *start;
1026         while (n > 0) {
1027                 get_page(*pages++ = pipe->bufs[idx].page);
1028                 idx = next_idx(idx, pipe);
1029                 n -= PAGE_SIZE;
1030         }
1031
1032         return maxsize;
1033 }
1034
1035 static ssize_t pipe_get_pages(struct iov_iter *i,
1036                    struct page **pages, size_t maxsize, unsigned maxpages,
1037                    size_t *start)
1038 {
1039         unsigned npages;
1040         size_t capacity;
1041         int idx;
1042
1043         if (!maxsize)
1044                 return 0;
1045
1046         if (!sanity(i))
1047                 return -EFAULT;
1048
1049         data_start(i, &idx, start);
1050         /* some of this one + all after this one */
1051         npages = ((i->pipe->curbuf - idx - 1) & (i->pipe->buffers - 1)) + 1;
1052         capacity = min(npages,maxpages) * PAGE_SIZE - *start;
1053
1054         return __pipe_get_pages(i, min(maxsize, capacity), pages, idx, start);
1055 }
1056
1057 ssize_t iov_iter_get_pages(struct iov_iter *i,
1058                    struct page **pages, size_t maxsize, unsigned maxpages,
1059                    size_t *start)
1060 {
1061         if (maxsize > i->count)
1062                 maxsize = i->count;
1063
1064         if (unlikely(i->type & ITER_PIPE))
1065                 return pipe_get_pages(i, pages, maxsize, maxpages, start);
1066         iterate_all_kinds(i, maxsize, v, ({
1067                 unsigned long addr = (unsigned long)v.iov_base;
1068                 size_t len = v.iov_len + (*start = addr & (PAGE_SIZE - 1));
1069                 int n;
1070                 int res;
1071
1072                 if (len > maxpages * PAGE_SIZE)
1073                         len = maxpages * PAGE_SIZE;
1074                 addr &= ~(PAGE_SIZE - 1);
1075                 n = DIV_ROUND_UP(len, PAGE_SIZE);
1076                 res = get_user_pages_fast(addr, n, (i->type & WRITE) != WRITE, pages);
1077                 if (unlikely(res < 0))
1078                         return res;
1079                 return (res == n ? len : res * PAGE_SIZE) - *start;
1080         0;}),({
1081                 /* can't be more than PAGE_SIZE */
1082                 *start = v.bv_offset;
1083                 get_page(*pages = v.bv_page);
1084                 return v.bv_len;
1085         }),({
1086                 return -EFAULT;
1087         })
1088         )
1089         return 0;
1090 }
1091 EXPORT_SYMBOL(iov_iter_get_pages);
1092
1093 static struct page **get_pages_array(size_t n)
1094 {
1095         return kvmalloc_array(n, sizeof(struct page *), GFP_KERNEL);
1096 }
1097
1098 static ssize_t pipe_get_pages_alloc(struct iov_iter *i,
1099                    struct page ***pages, size_t maxsize,
1100                    size_t *start)
1101 {
1102         struct page **p;
1103         size_t n;
1104         int idx;
1105         int npages;
1106
1107         if (!maxsize)
1108                 return 0;
1109
1110         if (!sanity(i))
1111                 return -EFAULT;
1112
1113         data_start(i, &idx, start);
1114         /* some of this one + all after this one */
1115         npages = ((i->pipe->curbuf - idx - 1) & (i->pipe->buffers - 1)) + 1;
1116         n = npages * PAGE_SIZE - *start;
1117         if (maxsize > n)
1118                 maxsize = n;
1119         else
1120                 npages = DIV_ROUND_UP(maxsize + *start, PAGE_SIZE);
1121         p = get_pages_array(npages);
1122         if (!p)
1123                 return -ENOMEM;
1124         n = __pipe_get_pages(i, maxsize, p, idx, start);
1125         if (n > 0)
1126                 *pages = p;
1127         else
1128                 kvfree(p);
1129         return n;
1130 }
1131
1132 ssize_t iov_iter_get_pages_alloc(struct iov_iter *i,
1133                    struct page ***pages, size_t maxsize,
1134                    size_t *start)
1135 {
1136         struct page **p;
1137
1138         if (maxsize > i->count)
1139                 maxsize = i->count;
1140
1141         if (unlikely(i->type & ITER_PIPE))
1142                 return pipe_get_pages_alloc(i, pages, maxsize, start);
1143         iterate_all_kinds(i, maxsize, v, ({
1144                 unsigned long addr = (unsigned long)v.iov_base;
1145                 size_t len = v.iov_len + (*start = addr & (PAGE_SIZE - 1));
1146                 int n;
1147                 int res;
1148
1149                 addr &= ~(PAGE_SIZE - 1);
1150                 n = DIV_ROUND_UP(len, PAGE_SIZE);
1151                 p = get_pages_array(n);
1152                 if (!p)
1153                         return -ENOMEM;
1154                 res = get_user_pages_fast(addr, n, (i->type & WRITE) != WRITE, p);
1155                 if (unlikely(res < 0)) {
1156                         kvfree(p);
1157                         return res;
1158                 }
1159                 *pages = p;
1160                 return (res == n ? len : res * PAGE_SIZE) - *start;
1161         0;}),({
1162                 /* can't be more than PAGE_SIZE */
1163                 *start = v.bv_offset;
1164                 *pages = p = get_pages_array(1);
1165                 if (!p)
1166                         return -ENOMEM;
1167                 get_page(*p = v.bv_page);
1168                 return v.bv_len;
1169         }),({
1170                 return -EFAULT;
1171         })
1172         )
1173         return 0;
1174 }
1175 EXPORT_SYMBOL(iov_iter_get_pages_alloc);
1176
1177 size_t csum_and_copy_from_iter(void *addr, size_t bytes, __wsum *csum,
1178                                struct iov_iter *i)
1179 {
1180         char *to = addr;
1181         __wsum sum, next;
1182         size_t off = 0;
1183         sum = *csum;
1184         if (unlikely(i->type & ITER_PIPE)) {
1185                 WARN_ON(1);
1186                 return 0;
1187         }
1188         iterate_and_advance(i, bytes, v, ({
1189                 int err = 0;
1190                 next = csum_and_copy_from_user(v.iov_base,
1191                                                (to += v.iov_len) - v.iov_len,
1192                                                v.iov_len, 0, &err);
1193                 if (!err) {
1194                         sum = csum_block_add(sum, next, off);
1195                         off += v.iov_len;
1196                 }
1197                 err ? v.iov_len : 0;
1198         }), ({
1199                 char *p = kmap_atomic(v.bv_page);
1200                 next = csum_partial_copy_nocheck(p + v.bv_offset,
1201                                                  (to += v.bv_len) - v.bv_len,
1202                                                  v.bv_len, 0);
1203                 kunmap_atomic(p);
1204                 sum = csum_block_add(sum, next, off);
1205                 off += v.bv_len;
1206         }),({
1207                 next = csum_partial_copy_nocheck(v.iov_base,
1208                                                  (to += v.iov_len) - v.iov_len,
1209                                                  v.iov_len, 0);
1210                 sum = csum_block_add(sum, next, off);
1211                 off += v.iov_len;
1212         })
1213         )
1214         *csum = sum;
1215         return bytes;
1216 }
1217 EXPORT_SYMBOL(csum_and_copy_from_iter);
1218
1219 bool csum_and_copy_from_iter_full(void *addr, size_t bytes, __wsum *csum,
1220                                struct iov_iter *i)
1221 {
1222         char *to = addr;
1223         __wsum sum, next;
1224         size_t off = 0;
1225         sum = *csum;
1226         if (unlikely(i->type & ITER_PIPE)) {
1227                 WARN_ON(1);
1228                 return false;
1229         }
1230         if (unlikely(i->count < bytes))
1231                 return false;
1232         iterate_all_kinds(i, bytes, v, ({
1233                 int err = 0;
1234                 next = csum_and_copy_from_user(v.iov_base,
1235                                                (to += v.iov_len) - v.iov_len,
1236                                                v.iov_len, 0, &err);
1237                 if (err)
1238                         return false;
1239                 sum = csum_block_add(sum, next, off);
1240                 off += v.iov_len;
1241                 0;
1242         }), ({
1243                 char *p = kmap_atomic(v.bv_page);
1244                 next = csum_partial_copy_nocheck(p + v.bv_offset,
1245                                                  (to += v.bv_len) - v.bv_len,
1246                                                  v.bv_len, 0);
1247                 kunmap_atomic(p);
1248                 sum = csum_block_add(sum, next, off);
1249                 off += v.bv_len;
1250         }),({
1251                 next = csum_partial_copy_nocheck(v.iov_base,
1252                                                  (to += v.iov_len) - v.iov_len,
1253                                                  v.iov_len, 0);
1254                 sum = csum_block_add(sum, next, off);
1255                 off += v.iov_len;
1256         })
1257         )
1258         *csum = sum;
1259         iov_iter_advance(i, bytes);
1260         return true;
1261 }
1262 EXPORT_SYMBOL(csum_and_copy_from_iter_full);
1263
1264 size_t csum_and_copy_to_iter(const void *addr, size_t bytes, __wsum *csum,
1265                              struct iov_iter *i)
1266 {
1267         const char *from = addr;
1268         __wsum sum, next;
1269         size_t off = 0;
1270         sum = *csum;
1271         if (unlikely(i->type & ITER_PIPE)) {
1272                 WARN_ON(1);     /* for now */
1273                 return 0;
1274         }
1275         iterate_and_advance(i, bytes, v, ({
1276                 int err = 0;
1277                 next = csum_and_copy_to_user((from += v.iov_len) - v.iov_len,
1278                                              v.iov_base,
1279                                              v.iov_len, 0, &err);
1280                 if (!err) {
1281                         sum = csum_block_add(sum, next, off);
1282                         off += v.iov_len;
1283                 }
1284                 err ? v.iov_len : 0;
1285         }), ({
1286                 char *p = kmap_atomic(v.bv_page);
1287                 next = csum_partial_copy_nocheck((from += v.bv_len) - v.bv_len,
1288                                                  p + v.bv_offset,
1289                                                  v.bv_len, 0);
1290                 kunmap_atomic(p);
1291                 sum = csum_block_add(sum, next, off);
1292                 off += v.bv_len;
1293         }),({
1294                 next = csum_partial_copy_nocheck((from += v.iov_len) - v.iov_len,
1295                                                  v.iov_base,
1296                                                  v.iov_len, 0);
1297                 sum = csum_block_add(sum, next, off);
1298                 off += v.iov_len;
1299         })
1300         )
1301         *csum = sum;
1302         return bytes;
1303 }
1304 EXPORT_SYMBOL(csum_and_copy_to_iter);
1305
1306 int iov_iter_npages(const struct iov_iter *i, int maxpages)
1307 {
1308         size_t size = i->count;
1309         int npages = 0;
1310
1311         if (!size)
1312                 return 0;
1313
1314         if (unlikely(i->type & ITER_PIPE)) {
1315                 struct pipe_inode_info *pipe = i->pipe;
1316                 size_t off;
1317                 int idx;
1318
1319                 if (!sanity(i))
1320                         return 0;
1321
1322                 data_start(i, &idx, &off);
1323                 /* some of this one + all after this one */
1324                 npages = ((pipe->curbuf - idx - 1) & (pipe->buffers - 1)) + 1;
1325                 if (npages >= maxpages)
1326                         return maxpages;
1327         } else iterate_all_kinds(i, size, v, ({
1328                 unsigned long p = (unsigned long)v.iov_base;
1329                 npages += DIV_ROUND_UP(p + v.iov_len, PAGE_SIZE)
1330                         - p / PAGE_SIZE;
1331                 if (npages >= maxpages)
1332                         return maxpages;
1333         0;}),({
1334                 npages++;
1335                 if (npages >= maxpages)
1336                         return maxpages;
1337         }),({
1338                 unsigned long p = (unsigned long)v.iov_base;
1339                 npages += DIV_ROUND_UP(p + v.iov_len, PAGE_SIZE)
1340                         - p / PAGE_SIZE;
1341                 if (npages >= maxpages)
1342                         return maxpages;
1343         })
1344         )
1345         return npages;
1346 }
1347 EXPORT_SYMBOL(iov_iter_npages);
1348
1349 const void *dup_iter(struct iov_iter *new, struct iov_iter *old, gfp_t flags)
1350 {
1351         *new = *old;
1352         if (unlikely(new->type & ITER_PIPE)) {
1353                 WARN_ON(1);
1354                 return NULL;
1355         }
1356         if (new->type & ITER_BVEC)
1357                 return new->bvec = kmemdup(new->bvec,
1358                                     new->nr_segs * sizeof(struct bio_vec),
1359                                     flags);
1360         else
1361                 /* iovec and kvec have identical layout */
1362                 return new->iov = kmemdup(new->iov,
1363                                    new->nr_segs * sizeof(struct iovec),
1364                                    flags);
1365 }
1366 EXPORT_SYMBOL(dup_iter);
1367
1368 /**
1369  * import_iovec() - Copy an array of &struct iovec from userspace
1370  *     into the kernel, check that it is valid, and initialize a new
1371  *     &struct iov_iter iterator to access it.
1372  *
1373  * @type: One of %READ or %WRITE.
1374  * @uvector: Pointer to the userspace array.
1375  * @nr_segs: Number of elements in userspace array.
1376  * @fast_segs: Number of elements in @iov.
1377  * @iov: (input and output parameter) Pointer to pointer to (usually small
1378  *     on-stack) kernel array.
1379  * @i: Pointer to iterator that will be initialized on success.
1380  *
1381  * If the array pointed to by *@iov is large enough to hold all @nr_segs,
1382  * then this function places %NULL in *@iov on return. Otherwise, a new
1383  * array will be allocated and the result placed in *@iov. This means that
1384  * the caller may call kfree() on *@iov regardless of whether the small
1385  * on-stack array was used or not (and regardless of whether this function
1386  * returns an error or not).
1387  *
1388  * Return: 0 on success or negative error code on error.
1389  */
1390 int import_iovec(int type, const struct iovec __user * uvector,
1391                  unsigned nr_segs, unsigned fast_segs,
1392                  struct iovec **iov, struct iov_iter *i)
1393 {
1394         ssize_t n;
1395         struct iovec *p;
1396         n = rw_copy_check_uvector(type, uvector, nr_segs, fast_segs,
1397                                   *iov, &p);
1398         if (n < 0) {
1399                 if (p != *iov)
1400                         kfree(p);
1401                 *iov = NULL;
1402                 return n;
1403         }
1404         iov_iter_init(i, type, p, nr_segs, n);
1405         *iov = p == *iov ? NULL : p;
1406         return 0;
1407 }
1408 EXPORT_SYMBOL(import_iovec);
1409
1410 #ifdef CONFIG_COMPAT
1411 #include <linux/compat.h>
1412
1413 int compat_import_iovec(int type, const struct compat_iovec __user * uvector,
1414                  unsigned nr_segs, unsigned fast_segs,
1415                  struct iovec **iov, struct iov_iter *i)
1416 {
1417         ssize_t n;
1418         struct iovec *p;
1419         n = compat_rw_copy_check_uvector(type, uvector, nr_segs, fast_segs,
1420                                   *iov, &p);
1421         if (n < 0) {
1422                 if (p != *iov)
1423                         kfree(p);
1424                 *iov = NULL;
1425                 return n;
1426         }
1427         iov_iter_init(i, type, p, nr_segs, n);
1428         *iov = p == *iov ? NULL : p;
1429         return 0;
1430 }
1431 #endif
1432
1433 int import_single_range(int rw, void __user *buf, size_t len,
1434                  struct iovec *iov, struct iov_iter *i)
1435 {
1436         if (len > MAX_RW_COUNT)
1437                 len = MAX_RW_COUNT;
1438         if (unlikely(!access_ok(!rw, buf, len)))
1439                 return -EFAULT;
1440
1441         iov->iov_base = buf;
1442         iov->iov_len = len;
1443         iov_iter_init(i, rw, iov, 1, len);
1444         return 0;
1445 }
1446 EXPORT_SYMBOL(import_single_range);