fs/read_write.c

   1 /*
   2  *  linux/fs/read_write.c
   3  *
   4  *  Copyright (C) 1991, 1992  Linus Torvalds
   5  */
   6
   7 #include <linux/slab.h>
   8 #include <linux/stat.h>
   9 #include <linux/fcntl.h>
  10 #include <linux/file.h>
  11 #include <linux/uio.h>
  12 #include <linux/smp_lock.h>
  13 #include <linux/fsnotify.h>
  14 #include <linux/security.h>
  15 #include <linux/module.h>
  16 #include <linux/syscalls.h>
  17 #include <linux/pagemap.h>
  18
  19 #include <asm/uaccess.h>
  20 #include <asm/unistd.h>
  21
  22 const struct file_operations generic_ro_fops = {
  23         .llseek         = generic_file_llseek,
  24         .read           = generic_file_read,
  25         .mmap           = generic_file_readonly_mmap,
  26         .sendfile       = generic_file_sendfile,
  27 };
  28
  29 EXPORT_SYMBOL(generic_ro_fops);
  30
  31 loff_t generic_file_llseek(struct file *file, loff_t offset, int origin)
  32 {
  33         long long retval;
  34         struct inode *inode = file->f_mapping->host;
  35
  36         mutex_lock(&inode->i_mutex);
  37         switch (origin) {
  38                 case 2:
  39                         offset += inode->i_size;
  40                         break;
  41                 case 1:
  42                         offset += file->f_pos;
  43         }
  44         retval = -EINVAL;
  45         if (offset>=0 && offset<=inode->i_sb->s_maxbytes) {
  46                 if (offset != file->f_pos) {
  47                         file->f_pos = offset;
  48                         file->f_version = 0;
  49                 }
  50                 retval = offset;
  51         }
  52         mutex_unlock(&inode->i_mutex);
  53         return retval;
  54 }
  55
  56 EXPORT_SYMBOL(generic_file_llseek);
  57
  58 loff_t remote_llseek(struct file *file, loff_t offset, int origin)
  59 {
  60         long long retval;
  61
  62         lock_kernel();
  63         switch (origin) {
  64                 case 2:
  65                         offset += i_size_read(file->f_dentry->d_inode);
  66                         break;
  67                 case 1:
  68                         offset += file->f_pos;
  69         }
  70         retval = -EINVAL;
  71         if (offset>=0 && offset<=file->f_dentry->d_inode->i_sb->s_maxbytes) {
  72                 if (offset != file->f_pos) {
  73                         file->f_pos = offset;
  74                         file->f_version = 0;
  75                 }
  76                 retval = offset;
  77         }
  78         unlock_kernel();
  79         return retval;
  80 }
  81 EXPORT_SYMBOL(remote_llseek);
  82
  83 loff_t no_llseek(struct file *file, loff_t offset, int origin)
  84 {
  85         return -ESPIPE;
  86 }
  87 EXPORT_SYMBOL(no_llseek);
  88
  89 loff_t default_llseek(struct file *file, loff_t offset, int origin)
  90 {
  91         long long retval;
  92
  93         lock_kernel();
  94         switch (origin) {
  95                 case 2:
  96                         offset += i_size_read(file->f_dentry->d_inode);
  97                         break;
  98                 case 1:
  99                         offset += file->f_pos;
 100         }
 101         retval = -EINVAL;
 102         if (offset >= 0) {
 103                 if (offset != file->f_pos) {
 104                         file->f_pos = offset;
 105                         file->f_version = 0;
 106                 }
 107                 retval = offset;
 108         }
 109         unlock_kernel();
 110         return retval;
 111 }
 112 EXPORT_SYMBOL(default_llseek);
 113
 114 loff_t vfs_llseek(struct file *file, loff_t offset, int origin)
 115 {
 116         loff_t (*fn)(struct file *, loff_t, int);
 117
 118         fn = no_llseek;
 119         if (file->f_mode & FMODE_LSEEK) {
 120                 fn = default_llseek;
 121                 if (file->f_op && file->f_op->llseek)
 122                         fn = file->f_op->llseek;
 123         }
 124         return fn(file, offset, origin);
 125 }
 126 EXPORT_SYMBOL(vfs_llseek);
 127
 128 asmlinkage off_t sys_lseek(unsigned int fd, off_t offset, unsigned int origin)
 129 {
 130         off_t retval;
 131         struct file * file;
 132         int fput_needed;
 133
 134         retval = -EBADF;
 135         file = fget_light(fd, &fput_needed);
 136         if (!file)
 137                 goto bad;
 138
 139         retval = -EINVAL;
 140         if (origin <= 2) {
 141                 loff_t res = vfs_llseek(file, offset, origin);
 142                 retval = res;
 143                 if (res != (loff_t)retval)
 144                         retval = -EOVERFLOW;    /* LFS: should only happen on 32 bit platforms */
 145         }
 146         fput_light(file, fput_needed);
 147 bad:
 148         return retval;
 149 }
 150
 151 #ifdef __ARCH_WANT_SYS_LLSEEK
 152 asmlinkage long sys_llseek(unsigned int fd, unsigned long offset_high,
 153                            unsigned long offset_low, loff_t __user * result,
 154                            unsigned int origin)
 155 {
 156         int retval;
 157         struct file * file;
 158         loff_t offset;
 159         int fput_needed;
 160
 161         retval = -EBADF;
 162         file = fget_light(fd, &fput_needed);
 163         if (!file)
 164                 goto bad;
 165
 166         retval = -EINVAL;
 167         if (origin > 2)
 168                 goto out_putf;
 169
 170         offset = vfs_llseek(file, ((loff_t) offset_high << 32) | offset_low,
 171                         origin);
 172
 173         retval = (int)offset;
 174         if (offset >= 0) {
 175                 retval = -EFAULT;
 176                 if (!copy_to_user(result, &offset, sizeof(offset)))
 177                         retval = 0;
 178         }
 179 out_putf:
 180         fput_light(file, fput_needed);
 181 bad:
 182         return retval;
 183 }
 184 #endif
 185
 186 /*
 187  * rw_verify_area doesn't like huge counts. We limit
 188  * them to something that fits in "int" so that others
 189  * won't have to do range checks all the time.
 190  */
 191 #define MAX_RW_COUNT (INT_MAX & PAGE_CACHE_MASK)
 192
 193 int rw_verify_area(int read_write, struct file *file, loff_t *ppos, size_t count)
 194 {
 195         struct inode *inode;
 196         loff_t pos;
 197
 198         if (unlikely((ssize_t) count < 0))
 199                 goto Einval;
 200         pos = *ppos;
 201         if (unlikely((pos < 0) || (loff_t) (pos + count) < 0))
 202                 goto Einval;
 203
 204         inode = file->f_dentry->d_inode;
 205         if (unlikely(inode->i_flock && MANDATORY_LOCK(inode))) {
 206                 int retval = locks_mandatory_area(
 207                         read_write == READ ? FLOCK_VERIFY_READ : FLOCK_VERIFY_WRITE,
 208                         inode, file, pos, count);
 209                 if (retval < 0)
 210                         return retval;
 211         }
 212         return count > MAX_RW_COUNT ? MAX_RW_COUNT : count;
 213
 214 Einval:
 215         return -EINVAL;
 216 }
 217
 218 static void wait_on_retry_sync_kiocb(struct kiocb *iocb)
 219 {
 220         set_current_state(TASK_UNINTERRUPTIBLE);
 221         if (!kiocbIsKicked(iocb))
 222                 schedule();
 223         else
 224                 kiocbClearKicked(iocb);
 225         __set_current_state(TASK_RUNNING);
 226 }
 227
 228 ssize_t do_sync_read(struct file *filp, char __user *buf, size_t len, loff_t *ppos)
 229 {
 230         struct kiocb kiocb;
 231         ssize_t ret;
 232
 233         init_sync_kiocb(&kiocb, filp);
 234         kiocb.ki_pos = *ppos;
 235         while (-EIOCBRETRY ==
 236                 (ret = filp->f_op->aio_read(&kiocb, buf, len, kiocb.ki_pos)))
 237                 wait_on_retry_sync_kiocb(&kiocb);
 238
 239         if (-EIOCBQUEUED == ret)
 240                 ret = wait_on_sync_kiocb(&kiocb);
 241         *ppos = kiocb.ki_pos;
 242         return ret;
 243 }
 244
 245 EXPORT_SYMBOL(do_sync_read);
 246
 247 ssize_t vfs_read(struct file *file, char __user *buf, size_t count, loff_t *pos)
 248 {
 249         ssize_t ret;
 250
 251         if (!(file->f_mode & FMODE_READ))
 252                 return -EBADF;
 253         if (!file->f_op || (!file->f_op->read && !file->f_op->aio_read))
 254                 return -EINVAL;
 255         if (unlikely(!access_ok(VERIFY_WRITE, buf, count)))
 256                 return -EFAULT;
 257
 258         ret = rw_verify_area(READ, file, pos, count);
 259         if (ret >= 0) {
 260                 count = ret;
 261                 ret = security_file_permission (file, MAY_READ);
 262                 if (!ret) {
 263                         if (file->f_op->read)
 264                                 ret = file->f_op->read(file, buf, count, pos);
 265                         else
 266                                 ret = do_sync_read(file, buf, count, pos);
 267                         if (ret > 0) {
 268                                 fsnotify_access(file->f_dentry);
 269                                 current->rchar += ret;
 270                         }
 271                         current->syscr++;
 272                 }
 273         }
 274
 275         return ret;
 276 }
 277
 278 EXPORT_SYMBOL(vfs_read);
 279
 280 ssize_t do_sync_write(struct file *filp, const char __user *buf, size_t len, loff_t *ppos)
 281 {
 282         struct kiocb kiocb;
 283         ssize_t ret;
 284
 285         init_sync_kiocb(&kiocb, filp);
 286         kiocb.ki_pos = *ppos;
 287         while (-EIOCBRETRY ==
 288                (ret = filp->f_op->aio_write(&kiocb, buf, len, kiocb.ki_pos)))
 289                 wait_on_retry_sync_kiocb(&kiocb);
 290
 291         if (-EIOCBQUEUED == ret)
 292                 ret = wait_on_sync_kiocb(&kiocb);
 293         *ppos = kiocb.ki_pos;
 294         return ret;
 295 }
 296
 297 EXPORT_SYMBOL(do_sync_write);
 298
 299 ssize_t vfs_write(struct file *file, const char __user *buf, size_t count, loff_t *pos)
 300 {
 301         ssize_t ret;
 302
 303         if (!(file->f_mode & FMODE_WRITE))
 304                 return -EBADF;
 305         if (!file->f_op || (!file->f_op->write && !file->f_op->aio_write))
 306                 return -EINVAL;
 307         if (unlikely(!access_ok(VERIFY_READ, buf, count)))
 308                 return -EFAULT;
 309
 310         ret = rw_verify_area(WRITE, file, pos, count);
 311         if (ret >= 0) {
 312                 count = ret;
 313                 ret = security_file_permission (file, MAY_WRITE);
 314                 if (!ret) {
 315                         if (file->f_op->write)
 316                                 ret = file->f_op->write(file, buf, count, pos);
 317                         else
 318                                 ret = do_sync_write(file, buf, count, pos);
 319                         if (ret > 0) {
 320                                 fsnotify_modify(file->f_dentry);
 321                                 current->wchar += ret;
 322                         }
 323                         current->syscw++;
 324                 }
 325         }
 326
 327         return ret;
 328 }
 329
 330 EXPORT_SYMBOL(vfs_write);
 331
 332 static inline loff_t file_pos_read(struct file *file)
 333 {
 334         return file->f_pos;
 335 }
 336
 337 static inline void file_pos_write(struct file *file, loff_t pos)
 338 {
 339         file->f_pos = pos;
 340 }
 341
 342 asmlinkage ssize_t sys_read(unsigned int fd, char __user * buf, size_t count)
 343 {
 344         struct file *file;
 345         ssize_t ret = -EBADF;
 346         int fput_needed;
 347
 348         file = fget_light(fd, &fput_needed);
 349         if (file) {
 350                 loff_t pos = file_pos_read(file);
 351                 ret = vfs_read(file, buf, count, &pos);
 352                 file_pos_write(file, pos);
 353                 fput_light(file, fput_needed);
 354         }
 355
 356         return ret;
 357 }
 358 EXPORT_SYMBOL_GPL(sys_read);
 359
 360 asmlinkage ssize_t sys_write(unsigned int fd, const char __user * buf, size_t count)
 361 {
 362         struct file *file;
 363         ssize_t ret = -EBADF;
 364         int fput_needed;
 365
 366         file = fget_light(fd, &fput_needed);
 367         if (file) {
 368                 loff_t pos = file_pos_read(file);
 369                 ret = vfs_write(file, buf, count, &pos);
 370                 file_pos_write(file, pos);
 371                 fput_light(file, fput_needed);
 372         }
 373
 374         return ret;
 375 }
 376
 377 asmlinkage ssize_t sys_pread64(unsigned int fd, char __user *buf,
 378                              size_t count, loff_t pos)
 379 {
 380         struct file *file;
 381         ssize_t ret = -EBADF;
 382         int fput_needed;
 383
 384         if (pos < 0)
 385                 return -EINVAL;
 386
 387         file = fget_light(fd, &fput_needed);
 388         if (file) {
 389                 ret = -ESPIPE;
 390                 if (file->f_mode & FMODE_PREAD)
 391                         ret = vfs_read(file, buf, count, &pos);
 392                 fput_light(file, fput_needed);
 393         }
 394
 395         return ret;
 396 }
 397
 398 asmlinkage ssize_t sys_pwrite64(unsigned int fd, const char __user *buf,
 399                               size_t count, loff_t pos)
 400 {
 401         struct file *file;
 402         ssize_t ret = -EBADF;
 403         int fput_needed;
 404
 405         if (pos < 0)
 406                 return -EINVAL;
 407
 408         file = fget_light(fd, &fput_needed);
 409         if (file) {
 410                 ret = -ESPIPE;
 411                 if (file->f_mode & FMODE_PWRITE)
 412                         ret = vfs_write(file, buf, count, &pos);
 413                 fput_light(file, fput_needed);
 414         }
 415
 416         return ret;
 417 }
 418
 419 /*
 420  * Reduce an iovec's length in-place.  Return the resulting number of segments
 421  */
 422 unsigned long iov_shorten(struct iovec *iov, unsigned long nr_segs, size_t to)
 423 {
 424         unsigned long seg = 0;
 425         size_t len = 0;
 426
 427         while (seg < nr_segs) {
 428                 seg++;
 429                 if (len + iov->iov_len >= to) {
 430                         iov->iov_len = to - len;
 431                         break;
 432                 }
 433                 len += iov->iov_len;
 434                 iov++;
 435         }
 436         return seg;
 437 }
 438
 439 EXPORT_SYMBOL(iov_shorten);
 440
 441 /* A write operation does a read from user space and vice versa */
 442 #define vrfy_dir(type) ((type) == READ ? VERIFY_WRITE : VERIFY_READ)
 443
 444 static ssize_t do_readv_writev(int type, struct file *file,
 445                                const struct iovec __user * uvector,
 446                                unsigned long nr_segs, loff_t *pos)
 447 {
 448         typedef ssize_t (*io_fn_t)(struct file *, char __user *, size_t, loff_t *);
 449         typedef ssize_t (*iov_fn_t)(struct file *, const struct iovec *, unsigned long, loff_t *);
 450
 451         size_t tot_len;
 452         struct iovec iovstack[UIO_FASTIOV];
 453         struct iovec *iov=iovstack, *vector;
 454         ssize_t ret;
 455         int seg;
 456         io_fn_t fn;
 457         iov_fn_t fnv;
 458
 459         /*
 460          * SuS says "The readv() function *may* fail if the iovcnt argument
 461          * was less than or equal to 0, or greater than {IOV_MAX}.  Linux has
 462          * traditionally returned zero for zero segments, so...
 463          */
 464         ret = 0;
 465         if (nr_segs == 0)
 466                 goto out;
 467
 468         /*
 469          * First get the "struct iovec" from user memory and
 470          * verify all the pointers
 471          */
 472         ret = -EINVAL;
 473         if (nr_segs > UIO_MAXIOV)
 474                 goto out;
 475         if (!file->f_op)
 476                 goto out;
 477         if (nr_segs > UIO_FASTIOV) {
 478                 ret = -ENOMEM;
 479                 iov = kmalloc(nr_segs*sizeof(struct iovec), GFP_KERNEL);
 480                 if (!iov)
 481                         goto out;
 482         }
 483         ret = -EFAULT;
 484         if (copy_from_user(iov, uvector, nr_segs*sizeof(*uvector)))
 485                 goto out;
 486
 487         /*
 488          * Single unix specification:
 489          * We should -EINVAL if an element length is not >= 0 and fitting an
 490          * ssize_t.  The total length is fitting an ssize_t
 491          *
 492          * Be careful here because iov_len is a size_t not an ssize_t
 493          */
 494         tot_len = 0;
 495         ret = -EINVAL;
 496         for (seg = 0; seg < nr_segs; seg++) {
 497                 void __user *buf = iov[seg].iov_base;
 498                 ssize_t len = (ssize_t)iov[seg].iov_len;
 499
 500                 if (len < 0)    /* size_t not fitting an ssize_t .. */
 501                         goto out;
 502                 if (unlikely(!access_ok(vrfy_dir(type), buf, len)))
 503                         goto Efault;
 504                 tot_len += len;
 505                 if ((ssize_t)tot_len < 0) /* maths overflow on the ssize_t */
 506                         goto out;
 507         }
 508         if (tot_len == 0) {
 509                 ret = 0;
 510                 goto out;
 511         }
 512
 513         ret = rw_verify_area(type, file, pos, tot_len);
 514         if (ret < 0)
 515                 goto out;
 516         ret = security_file_permission(file, type == READ ? MAY_READ : MAY_WRITE);
 517         if (ret)
 518                 goto out;
 519
 520         fnv = NULL;
 521         if (type == READ) {
 522                 fn = file->f_op->read;
 523                 fnv = file->f_op->readv;
 524         } else {
 525                 fn = (io_fn_t)file->f_op->write;
 526                 fnv = file->f_op->writev;
 527         }
 528         if (fnv) {
 529                 ret = fnv(file, iov, nr_segs, pos);
 530                 goto out;
 531         }
 532
 533         /* Do it by hand, with file-ops */
 534         ret = 0;
 535         vector = iov;
 536         while (nr_segs > 0) {
 537                 void __user * base;
 538                 size_t len;
 539                 ssize_t nr;
 540
 541                 base = vector->iov_base;
 542                 len = vector->iov_len;
 543                 vector++;
 544                 nr_segs--;
 545
 546                 nr = fn(file, base, len, pos);
 547
 548                 if (nr < 0) {
 549                         if (!ret) ret = nr;
 550                         break;
 551                 }
 552                 ret += nr;
 553                 if (nr != len)
 554                         break;
 555         }
 556 out:
 557         if (iov != iovstack)
 558                 kfree(iov);
 559         if ((ret + (type == READ)) > 0) {
 560                 if (type == READ)
 561                         fsnotify_access(file->f_dentry);
 562                 else
 563                         fsnotify_modify(file->f_dentry);
 564         }
 565         return ret;
 566 Efault:
 567         ret = -EFAULT;
 568         goto out;
 569 }
 570
 571 ssize_t vfs_readv(struct file *file, const struct iovec __user *vec,
 572                   unsigned long vlen, loff_t *pos)
 573 {
 574         if (!(file->f_mode & FMODE_READ))
 575                 return -EBADF;
 576         if (!file->f_op || (!file->f_op->readv && !file->f_op->read))
 577                 return -EINVAL;
 578
 579         return do_readv_writev(READ, file, vec, vlen, pos);
 580 }
 581
 582 EXPORT_SYMBOL(vfs_readv);
 583
 584 ssize_t vfs_writev(struct file *file, const struct iovec __user *vec,
 585                    unsigned long vlen, loff_t *pos)
 586 {
 587         if (!(file->f_mode & FMODE_WRITE))
 588                 return -EBADF;
 589         if (!file->f_op || (!file->f_op->writev && !file->f_op->write))
 590                 return -EINVAL;
 591
 592         return do_readv_writev(WRITE, file, vec, vlen, pos);
 593 }
 594
 595 EXPORT_SYMBOL(vfs_writev);
 596
 597 asmlinkage ssize_t
 598 sys_readv(unsigned long fd, const struct iovec __user *vec, unsigned long vlen)
 599 {
 600         struct file *file;
 601         ssize_t ret = -EBADF;
 602         int fput_needed;
 603
 604         file = fget_light(fd, &fput_needed);
 605         if (file) {
 606                 loff_t pos = file_pos_read(file);
 607                 ret = vfs_readv(file, vec, vlen, &pos);
 608                 file_pos_write(file, pos);
 609                 fput_light(file, fput_needed);
 610         }
 611
 612         if (ret > 0)
 613                 current->rchar += ret;
 614         current->syscr++;
 615         return ret;
 616 }
 617
 618 asmlinkage ssize_t
 619 sys_writev(unsigned long fd, const struct iovec __user *vec, unsigned long vlen)
 620 {
 621         struct file *file;
 622         ssize_t ret = -EBADF;
 623         int fput_needed;
 624
 625         file = fget_light(fd, &fput_needed);
 626         if (file) {
 627                 loff_t pos = file_pos_read(file);
 628                 ret = vfs_writev(file, vec, vlen, &pos);
 629                 file_pos_write(file, pos);
 630                 fput_light(file, fput_needed);
 631         }
 632
 633         if (ret > 0)
 634                 current->wchar += ret;
 635         current->syscw++;
 636         return ret;
 637 }
 638
 639 static ssize_t do_sendfile(int out_fd, int in_fd, loff_t *ppos,
 640                            size_t count, loff_t max)
 641 {
 642         struct file * in_file, * out_file;
 643         struct inode * in_inode, * out_inode;
 644         loff_t pos;
 645         ssize_t retval;
 646         int fput_needed_in, fput_needed_out;
 647
 648         /*
 649          * Get input file, and verify that it is ok..
 650          */
 651         retval = -EBADF;
 652         in_file = fget_light(in_fd, &fput_needed_in);
 653         if (!in_file)
 654                 goto out;
 655         if (!(in_file->f_mode & FMODE_READ))
 656                 goto fput_in;
 657         retval = -EINVAL;
 658         in_inode = in_file->f_dentry->d_inode;
 659         if (!in_inode)
 660                 goto fput_in;
 661         if (!in_file->f_op || !in_file->f_op->sendfile)
 662                 goto fput_in;
 663         retval = -ESPIPE;
 664         if (!ppos)
 665                 ppos = &in_file->f_pos;
 666         else
 667                 if (!(in_file->f_mode & FMODE_PREAD))
 668                         goto fput_in;
 669         retval = rw_verify_area(READ, in_file, ppos, count);
 670         if (retval < 0)
 671                 goto fput_in;
 672         count = retval;
 673
 674         retval = security_file_permission (in_file, MAY_READ);
 675         if (retval)
 676                 goto fput_in;
 677
 678         /*
 679          * Get output file, and verify that it is ok..
 680          */
 681         retval = -EBADF;
 682         out_file = fget_light(out_fd, &fput_needed_out);
 683         if (!out_file)
 684                 goto fput_in;
 685         if (!(out_file->f_mode & FMODE_WRITE))
 686                 goto fput_out;
 687         retval = -EINVAL;
 688         if (!out_file->f_op || !out_file->f_op->sendpage)
 689                 goto fput_out;
 690         out_inode = out_file->f_dentry->d_inode;
 691         retval = rw_verify_area(WRITE, out_file, &out_file->f_pos, count);
 692         if (retval < 0)
 693                 goto fput_out;
 694         count = retval;
 695
 696         retval = security_file_permission (out_file, MAY_WRITE);
 697         if (retval)
 698                 goto fput_out;
 699
 700         if (!max)
 701                 max = min(in_inode->i_sb->s_maxbytes, out_inode->i_sb->s_maxbytes);
 702
 703         pos = *ppos;
 704         retval = -EINVAL;
 705         if (unlikely(pos < 0))
 706                 goto fput_out;
 707         if (unlikely(pos + count > max)) {
 708                 retval = -EOVERFLOW;
 709                 if (pos >= max)
 710                         goto fput_out;
 711                 count = max - pos;
 712         }
 713
 714         retval = in_file->f_op->sendfile(in_file, ppos, count, file_send_actor, out_file);
 715
 716         if (retval > 0) {
 717                 current->rchar += retval;
 718                 current->wchar += retval;
 719         }
 720         current->syscr++;
 721         current->syscw++;
 722
 723         if (*ppos > max)
 724                 retval = -EOVERFLOW;
 725
 726 fput_out:
 727         fput_light(out_file, fput_needed_out);
 728 fput_in:
 729         fput_light(in_file, fput_needed_in);
 730 out:
 731         return retval;
 732 }
 733
 734 asmlinkage ssize_t sys_sendfile(int out_fd, int in_fd, off_t __user *offset, size_t count)
 735 {
 736         loff_t pos;
 737         off_t off;
 738         ssize_t ret;
 739
 740         if (offset) {
 741                 if (unlikely(get_user(off, offset)))
 742                         return -EFAULT;
 743                 pos = off;
 744                 ret = do_sendfile(out_fd, in_fd, &pos, count, MAX_NON_LFS);
 745                 if (unlikely(put_user(pos, offset)))
 746                         return -EFAULT;
 747                 return ret;
 748         }
 749
 750         return do_sendfile(out_fd, in_fd, NULL, count, 0);
 751 }
 752
 753 asmlinkage ssize_t sys_sendfile64(int out_fd, int in_fd, loff_t __user *offset, size_t count)
 754 {
 755         loff_t pos;
 756         ssize_t ret;
 757
 758         if (offset) {
 759                 if (unlikely(copy_from_user(&pos, offset, sizeof(loff_t))))
 760                         return -EFAULT;
 761                 ret = do_sendfile(out_fd, in_fd, &pos, count, 0);
 762                 if (unlikely(put_user(pos, offset)))
 763                         return -EFAULT;
 764                 return ret;
 765         }
 766
 767         return do_sendfile(out_fd, in_fd, NULL, count, 0);
 768 }