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 #include <linux/splice.h>
  19 #include "read_write.h"
  20
  21 #include <asm/uaccess.h>
  22 #include <asm/unistd.h>
  23
  24 const struct file_operations generic_ro_fops = {
  25         .llseek         = generic_file_llseek,
  26         .read           = do_sync_read,
  27         .aio_read       = generic_file_aio_read,
  28         .mmap           = generic_file_readonly_mmap,
  29         .splice_read    = generic_file_splice_read,
  30 };
  31
  32 EXPORT_SYMBOL(generic_ro_fops);
  33
  34 loff_t
  35 generic_file_llseek_unlocked(struct file *file, loff_t offset, int origin)
  36 {
  37         loff_t retval;
  38         struct inode *inode = file->f_mapping->host;
  39
  40         switch (origin) {
  41                 case SEEK_END:
  42                         offset += inode->i_size;
  43                         break;
  44                 case SEEK_CUR:
  45                         offset += file->f_pos;
  46         }
  47         retval = -EINVAL;
  48         if (offset>=0 && offset<=inode->i_sb->s_maxbytes) {
  49                 /* Special lock needed here? */
  50                 if (offset != file->f_pos) {
  51                         file->f_pos = offset;
  52                         file->f_version = 0;
  53                 }
  54                 retval = offset;
  55         }
  56         return retval;
  57 }
  58 EXPORT_SYMBOL(generic_file_llseek_unlocked);
  59
  60 loff_t generic_file_llseek(struct file *file, loff_t offset, int origin)
  61 {
  62         loff_t n;
  63         mutex_lock(&file->f_dentry->d_inode->i_mutex);
  64         n = generic_file_llseek_unlocked(file, offset, origin);
  65         mutex_unlock(&file->f_dentry->d_inode->i_mutex);
  66         return n;
  67 }
  68 EXPORT_SYMBOL(generic_file_llseek);
  69
  70 loff_t no_llseek(struct file *file, loff_t offset, int origin)
  71 {
  72         return -ESPIPE;
  73 }
  74 EXPORT_SYMBOL(no_llseek);
  75
  76 loff_t default_llseek(struct file *file, loff_t offset, int origin)
  77 {
  78         loff_t retval;
  79
  80         lock_kernel();
  81         switch (origin) {
  82                 case SEEK_END:
  83                         offset += i_size_read(file->f_path.dentry->d_inode);
  84                         break;
  85                 case SEEK_CUR:
  86                         offset += file->f_pos;
  87         }
  88         retval = -EINVAL;
  89         if (offset >= 0) {
  90                 if (offset != file->f_pos) {
  91                         file->f_pos = offset;
  92                         file->f_version = 0;
  93                 }
  94                 retval = offset;
  95         }
  96         unlock_kernel();
  97         return retval;
  98 }
  99 EXPORT_SYMBOL(default_llseek);
 100
 101 loff_t vfs_llseek(struct file *file, loff_t offset, int origin)
 102 {
 103         loff_t (*fn)(struct file *, loff_t, int);
 104
 105         fn = no_llseek;
 106         if (file->f_mode & FMODE_LSEEK) {
 107                 fn = default_llseek;
 108                 if (file->f_op && file->f_op->llseek)
 109                         fn = file->f_op->llseek;
 110         }
 111         return fn(file, offset, origin);
 112 }
 113 EXPORT_SYMBOL(vfs_llseek);
 114
 115 SYSCALL_DEFINE3(lseek, unsigned int, fd, off_t, offset, unsigned int, origin)
 116 {
 117         off_t retval;
 118         struct file * file;
 119         int fput_needed;
 120
 121         retval = -EBADF;
 122         file = fget_light(fd, &fput_needed);
 123         if (!file)
 124                 goto bad;
 125
 126         retval = -EINVAL;
 127         if (origin <= SEEK_MAX) {
 128                 loff_t res = vfs_llseek(file, offset, origin);
 129                 retval = res;
 130                 if (res != (loff_t)retval)
 131                         retval = -EOVERFLOW;    /* LFS: should only happen on 32 bit platforms */
 132         }
 133         fput_light(file, fput_needed);
 134 bad:
 135         return retval;
 136 }
 137
 138 #ifdef __ARCH_WANT_SYS_LLSEEK
 139 SYSCALL_DEFINE5(llseek, unsigned int, fd, unsigned long, offset_high,
 140                 unsigned long, offset_low, loff_t __user *, result,
 141                 unsigned int, origin)
 142 {
 143         int retval;
 144         struct file * file;
 145         loff_t offset;
 146         int fput_needed;
 147
 148         retval = -EBADF;
 149         file = fget_light(fd, &fput_needed);
 150         if (!file)
 151                 goto bad;
 152
 153         retval = -EINVAL;
 154         if (origin > SEEK_MAX)
 155                 goto out_putf;
 156
 157         offset = vfs_llseek(file, ((loff_t) offset_high << 32) | offset_low,
 158                         origin);
 159
 160         retval = (int)offset;
 161         if (offset >= 0) {
 162                 retval = -EFAULT;
 163                 if (!copy_to_user(result, &offset, sizeof(offset)))
 164                         retval = 0;
 165         }
 166 out_putf:
 167         fput_light(file, fput_needed);
 168 bad:
 169         return retval;
 170 }
 171 #endif
 172
 173 /*
 174  * rw_verify_area doesn't like huge counts. We limit
 175  * them to something that fits in "int" so that others
 176  * won't have to do range checks all the time.
 177  */
 178 #define MAX_RW_COUNT (INT_MAX & PAGE_CACHE_MASK)
 179
 180 int rw_verify_area(int read_write, struct file *file, loff_t *ppos, size_t count)
 181 {
 182         struct inode *inode;
 183         loff_t pos;
 184         int retval = -EINVAL;
 185
 186         inode = file->f_path.dentry->d_inode;
 187         if (unlikely((ssize_t) count < 0))
 188                 return retval;
 189         pos = *ppos;
 190         if (unlikely((pos < 0) || (loff_t) (pos + count) < 0))
 191                 return retval;
 192
 193         if (unlikely(inode->i_flock && mandatory_lock(inode))) {
 194                 retval = locks_mandatory_area(
 195                         read_write == READ ? FLOCK_VERIFY_READ : FLOCK_VERIFY_WRITE,
 196                         inode, file, pos, count);
 197                 if (retval < 0)
 198                         return retval;
 199         }
 200         retval = security_file_permission(file,
 201                                 read_write == READ ? MAY_READ : MAY_WRITE);
 202         if (retval)
 203                 return retval;
 204         return count > MAX_RW_COUNT ? MAX_RW_COUNT : count;
 205 }
 206
 207 static void wait_on_retry_sync_kiocb(struct kiocb *iocb)
 208 {
 209         set_current_state(TASK_UNINTERRUPTIBLE);
 210         if (!kiocbIsKicked(iocb))
 211                 schedule();
 212         else
 213                 kiocbClearKicked(iocb);
 214         __set_current_state(TASK_RUNNING);
 215 }
 216
 217 ssize_t do_sync_read(struct file *filp, char __user *buf, size_t len, loff_t *ppos)
 218 {
 219         struct iovec iov = { .iov_base = buf, .iov_len = len };
 220         struct kiocb kiocb;
 221         ssize_t ret;
 222
 223         init_sync_kiocb(&kiocb, filp);
 224         kiocb.ki_pos = *ppos;
 225         kiocb.ki_left = len;
 226
 227         for (;;) {
 228                 ret = filp->f_op->aio_read(&kiocb, &iov, 1, kiocb.ki_pos);
 229                 if (ret != -EIOCBRETRY)
 230                         break;
 231                 wait_on_retry_sync_kiocb(&kiocb);
 232         }
 233
 234         if (-EIOCBQUEUED == ret)
 235                 ret = wait_on_sync_kiocb(&kiocb);
 236         *ppos = kiocb.ki_pos;
 237         return ret;
 238 }
 239
 240 EXPORT_SYMBOL(do_sync_read);
 241
 242 ssize_t vfs_read(struct file *file, char __user *buf, size_t count, loff_t *pos)
 243 {
 244         ssize_t ret;
 245
 246         if (!(file->f_mode & FMODE_READ))
 247                 return -EBADF;
 248         if (!file->f_op || (!file->f_op->read && !file->f_op->aio_read))
 249                 return -EINVAL;
 250         if (unlikely(!access_ok(VERIFY_WRITE, buf, count)))
 251                 return -EFAULT;
 252
 253         ret = rw_verify_area(READ, file, pos, count);
 254         if (ret >= 0) {
 255                 count = ret;
 256                 if (file->f_op->read)
 257                         ret = file->f_op->read(file, buf, count, pos);
 258                 else
 259                         ret = do_sync_read(file, buf, count, pos);
 260                 if (ret > 0) {
 261                         fsnotify_access(file->f_path.dentry);
 262                         add_rchar(current, ret);
 263                 }
 264                 inc_syscr(current);
 265         }
 266
 267         return ret;
 268 }
 269
 270 EXPORT_SYMBOL(vfs_read);
 271
 272 ssize_t do_sync_write(struct file *filp, const char __user *buf, size_t len, loff_t *ppos)
 273 {
 274         struct iovec iov = { .iov_base = (void __user *)buf, .iov_len = len };
 275         struct kiocb kiocb;
 276         ssize_t ret;
 277
 278         init_sync_kiocb(&kiocb, filp);
 279         kiocb.ki_pos = *ppos;
 280         kiocb.ki_left = len;
 281
 282         for (;;) {
 283                 ret = filp->f_op->aio_write(&kiocb, &iov, 1, kiocb.ki_pos);
 284                 if (ret != -EIOCBRETRY)
 285                         break;
 286                 wait_on_retry_sync_kiocb(&kiocb);
 287         }
 288
 289         if (-EIOCBQUEUED == ret)
 290                 ret = wait_on_sync_kiocb(&kiocb);
 291         *ppos = kiocb.ki_pos;
 292         return ret;
 293 }
 294
 295 EXPORT_SYMBOL(do_sync_write);
 296
 297 ssize_t vfs_write(struct file *file, const char __user *buf, size_t count, loff_t *pos)
 298 {
 299         ssize_t ret;
 300
 301         if (!(file->f_mode & FMODE_WRITE))
 302                 return -EBADF;
 303         if (!file->f_op || (!file->f_op->write && !file->f_op->aio_write))
 304                 return -EINVAL;
 305         if (unlikely(!access_ok(VERIFY_READ, buf, count)))
 306                 return -EFAULT;
 307
 308         ret = rw_verify_area(WRITE, file, pos, count);
 309         if (ret >= 0) {
 310                 count = ret;
 311                 if (file->f_op->write)
 312                         ret = file->f_op->write(file, buf, count, pos);
 313                 else
 314                         ret = do_sync_write(file, buf, count, pos);
 315                 if (ret > 0) {
 316                         fsnotify_modify(file->f_path.dentry);
 317                         add_wchar(current, ret);
 318                 }
 319                 inc_syscw(current);
 320         }
 321
 322         return ret;
 323 }
 324
 325 EXPORT_SYMBOL(vfs_write);
 326
 327 static inline loff_t file_pos_read(struct file *file)
 328 {
 329         return file->f_pos;
 330 }
 331
 332 static inline void file_pos_write(struct file *file, loff_t pos)
 333 {
 334         file->f_pos = pos;
 335 }
 336
 337 SYSCALL_DEFINE3(read, unsigned int, fd, char __user *, buf, size_t, count)
 338 {
 339         struct file *file;
 340         ssize_t ret = -EBADF;
 341         int fput_needed;
 342
 343         file = fget_light(fd, &fput_needed);
 344         if (file) {
 345                 loff_t pos = file_pos_read(file);
 346                 ret = vfs_read(file, buf, count, &pos);
 347                 file_pos_write(file, pos);
 348                 fput_light(file, fput_needed);
 349         }
 350
 351         return ret;
 352 }
 353
 354 SYSCALL_DEFINE3(write, unsigned int, fd, const char __user *, buf,
 355                 size_t, count)
 356 {
 357         struct file *file;
 358         ssize_t ret = -EBADF;
 359         int fput_needed;
 360
 361         file = fget_light(fd, &fput_needed);
 362         if (file) {
 363                 loff_t pos = file_pos_read(file);
 364                 ret = vfs_write(file, buf, count, &pos);
 365                 file_pos_write(file, pos);
 366                 fput_light(file, fput_needed);
 367         }
 368
 369         return ret;
 370 }
 371
 372 SYSCALL_DEFINE(pread64)(unsigned int fd, char __user *buf,
 373                         size_t count, loff_t pos)
 374 {
 375         struct file *file;
 376         ssize_t ret = -EBADF;
 377         int fput_needed;
 378
 379         if (pos < 0)
 380                 return -EINVAL;
 381
 382         file = fget_light(fd, &fput_needed);
 383         if (file) {
 384                 ret = -ESPIPE;
 385                 if (file->f_mode & FMODE_PREAD)
 386                         ret = vfs_read(file, buf, count, &pos);
 387                 fput_light(file, fput_needed);
 388         }
 389
 390         return ret;
 391 }
 392 #ifdef CONFIG_HAVE_SYSCALL_WRAPPERS
 393 asmlinkage long SyS_pread64(long fd, long buf, long count, loff_t pos)
 394 {
 395         return SYSC_pread64((unsigned int) fd, (char __user *) buf,
 396                             (size_t) count, pos);
 397 }
 398 SYSCALL_ALIAS(sys_pread64, SyS_pread64);
 399 #endif
 400
 401 SYSCALL_DEFINE(pwrite64)(unsigned int fd, const char __user *buf,
 402                          size_t count, loff_t pos)
 403 {
 404         struct file *file;
 405         ssize_t ret = -EBADF;
 406         int fput_needed;
 407
 408         if (pos < 0)
 409                 return -EINVAL;
 410
 411         file = fget_light(fd, &fput_needed);
 412         if (file) {
 413                 ret = -ESPIPE;
 414                 if (file->f_mode & FMODE_PWRITE)
 415                         ret = vfs_write(file, buf, count, &pos);
 416                 fput_light(file, fput_needed);
 417         }
 418
 419         return ret;
 420 }
 421 #ifdef CONFIG_HAVE_SYSCALL_WRAPPERS
 422 asmlinkage long SyS_pwrite64(long fd, long buf, long count, loff_t pos)
 423 {
 424         return SYSC_pwrite64((unsigned int) fd, (const char __user *) buf,
 425                              (size_t) count, pos);
 426 }
 427 SYSCALL_ALIAS(sys_pwrite64, SyS_pwrite64);
 428 #endif
 429
 430 /*
 431  * Reduce an iovec's length in-place.  Return the resulting number of segments
 432  */
 433 unsigned long iov_shorten(struct iovec *iov, unsigned long nr_segs, size_t to)
 434 {
 435         unsigned long seg = 0;
 436         size_t len = 0;
 437
 438         while (seg < nr_segs) {
 439                 seg++;
 440                 if (len + iov->iov_len >= to) {
 441                         iov->iov_len = to - len;
 442                         break;
 443                 }
 444                 len += iov->iov_len;
 445                 iov++;
 446         }
 447         return seg;
 448 }
 449 EXPORT_SYMBOL(iov_shorten);
 450
 451 ssize_t do_sync_readv_writev(struct file *filp, const struct iovec *iov,
 452                 unsigned long nr_segs, size_t len, loff_t *ppos, iov_fn_t fn)
 453 {
 454         struct kiocb kiocb;
 455         ssize_t ret;
 456
 457         init_sync_kiocb(&kiocb, filp);
 458         kiocb.ki_pos = *ppos;
 459         kiocb.ki_left = len;
 460         kiocb.ki_nbytes = len;
 461
 462         for (;;) {
 463                 ret = fn(&kiocb, iov, nr_segs, kiocb.ki_pos);
 464                 if (ret != -EIOCBRETRY)
 465                         break;
 466                 wait_on_retry_sync_kiocb(&kiocb);
 467         }
 468
 469         if (ret == -EIOCBQUEUED)
 470                 ret = wait_on_sync_kiocb(&kiocb);
 471         *ppos = kiocb.ki_pos;
 472         return ret;
 473 }
 474
 475 /* Do it by hand, with file-ops */
 476 ssize_t do_loop_readv_writev(struct file *filp, struct iovec *iov,
 477                 unsigned long nr_segs, loff_t *ppos, io_fn_t fn)
 478 {
 479         struct iovec *vector = iov;
 480         ssize_t ret = 0;
 481
 482         while (nr_segs > 0) {
 483                 void __user *base;
 484                 size_t len;
 485                 ssize_t nr;
 486
 487                 base = vector->iov_base;
 488                 len = vector->iov_len;
 489                 vector++;
 490                 nr_segs--;
 491
 492                 nr = fn(filp, base, len, ppos);
 493
 494                 if (nr < 0) {
 495                         if (!ret)
 496                                 ret = nr;
 497                         break;
 498                 }
 499                 ret += nr;
 500                 if (nr != len)
 501                         break;
 502         }
 503
 504         return ret;
 505 }
 506
 507 /* A write operation does a read from user space and vice versa */
 508 #define vrfy_dir(type) ((type) == READ ? VERIFY_WRITE : VERIFY_READ)
 509
 510 ssize_t rw_copy_check_uvector(int type, const struct iovec __user * uvector,
 511                               unsigned long nr_segs, unsigned long fast_segs,
 512                               struct iovec *fast_pointer,
 513                               struct iovec **ret_pointer)
 514   {
 515         unsigned long seg;
 516         ssize_t ret;
 517         struct iovec *iov = fast_pointer;
 518
 519         /*
 520          * SuS says "The readv() function *may* fail if the iovcnt argument
 521          * was less than or equal to 0, or greater than {IOV_MAX}.  Linux has
 522          * traditionally returned zero for zero segments, so...
 523          */
 524         if (nr_segs == 0) {
 525                 ret = 0;
 526                 goto out;
 527         }
 528
 529         /*
 530          * First get the "struct iovec" from user memory and
 531          * verify all the pointers
 532          */
 533         if (nr_segs > UIO_MAXIOV) {
 534                 ret = -EINVAL;
 535                 goto out;
 536         }
 537         if (nr_segs > fast_segs) {
 538                 iov = kmalloc(nr_segs*sizeof(struct iovec), GFP_KERNEL);
 539                 if (iov == NULL) {
 540                         ret = -ENOMEM;
 541                         goto out;
 542                 }
 543         }
 544         if (copy_from_user(iov, uvector, nr_segs*sizeof(*uvector))) {
 545                 ret = -EFAULT;
 546                 goto out;
 547         }
 548
 549         /*
 550          * According to the Single Unix Specification we should return EINVAL
 551          * if an element length is < 0 when cast to ssize_t or if the
 552          * total length would overflow the ssize_t return value of the
 553          * system call.
 554          */
 555         ret = 0;
 556         for (seg = 0; seg < nr_segs; seg++) {
 557                 void __user *buf = iov[seg].iov_base;
 558                 ssize_t len = (ssize_t)iov[seg].iov_len;
 559
 560                 /* see if we we're about to use an invalid len or if
 561                  * it's about to overflow ssize_t */
 562                 if (len < 0 || (ret + len < ret)) {
 563                         ret = -EINVAL;
 564                         goto out;
 565                 }
 566                 if (unlikely(!access_ok(vrfy_dir(type), buf, len))) {
 567                         ret = -EFAULT;
 568                         goto out;
 569                 }
 570
 571                 ret += len;
 572         }
 573 out:
 574         *ret_pointer = iov;
 575         return ret;
 576 }
 577
 578 static ssize_t do_readv_writev(int type, struct file *file,
 579                                const struct iovec __user * uvector,
 580                                unsigned long nr_segs, loff_t *pos)
 581 {
 582         size_t tot_len;
 583         struct iovec iovstack[UIO_FASTIOV];
 584         struct iovec *iov = iovstack;
 585         ssize_t ret;
 586         io_fn_t fn;
 587         iov_fn_t fnv;
 588
 589         if (!file->f_op) {
 590                 ret = -EINVAL;
 591                 goto out;
 592         }
 593
 594         ret = rw_copy_check_uvector(type, uvector, nr_segs,
 595                         ARRAY_SIZE(iovstack), iovstack, &iov);
 596         if (ret <= 0)
 597                 goto out;
 598
 599         tot_len = ret;
 600         ret = rw_verify_area(type, file, pos, tot_len);
 601         if (ret < 0)
 602                 goto out;
 603
 604         fnv = NULL;
 605         if (type == READ) {
 606                 fn = file->f_op->read;
 607                 fnv = file->f_op->aio_read;
 608         } else {
 609                 fn = (io_fn_t)file->f_op->write;
 610                 fnv = file->f_op->aio_write;
 611         }
 612
 613         if (fnv)
 614                 ret = do_sync_readv_writev(file, iov, nr_segs, tot_len,
 615                                                 pos, fnv);
 616         else
 617                 ret = do_loop_readv_writev(file, iov, nr_segs, pos, fn);
 618
 619 out:
 620         if (iov != iovstack)
 621                 kfree(iov);
 622         if ((ret + (type == READ)) > 0) {
 623                 if (type == READ)
 624                         fsnotify_access(file->f_path.dentry);
 625                 else
 626                         fsnotify_modify(file->f_path.dentry);
 627         }
 628         return ret;
 629 }
 630
 631 ssize_t vfs_readv(struct file *file, const struct iovec __user *vec,
 632                   unsigned long vlen, loff_t *pos)
 633 {
 634         if (!(file->f_mode & FMODE_READ))
 635                 return -EBADF;
 636         if (!file->f_op || (!file->f_op->aio_read && !file->f_op->read))
 637                 return -EINVAL;
 638
 639         return do_readv_writev(READ, file, vec, vlen, pos);
 640 }
 641
 642 EXPORT_SYMBOL(vfs_readv);
 643
 644 ssize_t vfs_writev(struct file *file, const struct iovec __user *vec,
 645                    unsigned long vlen, loff_t *pos)
 646 {
 647         if (!(file->f_mode & FMODE_WRITE))
 648                 return -EBADF;
 649         if (!file->f_op || (!file->f_op->aio_write && !file->f_op->write))
 650                 return -EINVAL;
 651
 652         return do_readv_writev(WRITE, file, vec, vlen, pos);
 653 }
 654
 655 EXPORT_SYMBOL(vfs_writev);
 656
 657 SYSCALL_DEFINE3(readv, unsigned long, fd, const struct iovec __user *, vec,
 658                 unsigned long, vlen)
 659 {
 660         struct file *file;
 661         ssize_t ret = -EBADF;
 662         int fput_needed;
 663
 664         file = fget_light(fd, &fput_needed);
 665         if (file) {
 666                 loff_t pos = file_pos_read(file);
 667                 ret = vfs_readv(file, vec, vlen, &pos);
 668                 file_pos_write(file, pos);
 669                 fput_light(file, fput_needed);
 670         }
 671
 672         if (ret > 0)
 673                 add_rchar(current, ret);
 674         inc_syscr(current);
 675         return ret;
 676 }
 677
 678 SYSCALL_DEFINE3(writev, unsigned long, fd, const struct iovec __user *, vec,
 679                 unsigned long, vlen)
 680 {
 681         struct file *file;
 682         ssize_t ret = -EBADF;
 683         int fput_needed;
 684
 685         file = fget_light(fd, &fput_needed);
 686         if (file) {
 687                 loff_t pos = file_pos_read(file);
 688                 ret = vfs_writev(file, vec, vlen, &pos);
 689                 file_pos_write(file, pos);
 690                 fput_light(file, fput_needed);
 691         }
 692
 693         if (ret > 0)
 694                 add_wchar(current, ret);
 695         inc_syscw(current);
 696         return ret;
 697 }
 698
 699 static ssize_t do_sendfile(int out_fd, int in_fd, loff_t *ppos,
 700                            size_t count, loff_t max)
 701 {
 702         struct file * in_file, * out_file;
 703         struct inode * in_inode, * out_inode;
 704         loff_t pos;
 705         ssize_t retval;
 706         int fput_needed_in, fput_needed_out, fl;
 707
 708         /*
 709          * Get input file, and verify that it is ok..
 710          */
 711         retval = -EBADF;
 712         in_file = fget_light(in_fd, &fput_needed_in);
 713         if (!in_file)
 714                 goto out;
 715         if (!(in_file->f_mode & FMODE_READ))
 716                 goto fput_in;
 717         retval = -EINVAL;
 718         in_inode = in_file->f_path.dentry->d_inode;
 719         if (!in_inode)
 720                 goto fput_in;
 721         if (!in_file->f_op || !in_file->f_op->splice_read)
 722                 goto fput_in;
 723         retval = -ESPIPE;
 724         if (!ppos)
 725                 ppos = &in_file->f_pos;
 726         else
 727                 if (!(in_file->f_mode & FMODE_PREAD))
 728                         goto fput_in;
 729         retval = rw_verify_area(READ, in_file, ppos, count);
 730         if (retval < 0)
 731                 goto fput_in;
 732         count = retval;
 733
 734         /*
 735          * Get output file, and verify that it is ok..
 736          */
 737         retval = -EBADF;
 738         out_file = fget_light(out_fd, &fput_needed_out);
 739         if (!out_file)
 740                 goto fput_in;
 741         if (!(out_file->f_mode & FMODE_WRITE))
 742                 goto fput_out;
 743         retval = -EINVAL;
 744         if (!out_file->f_op || !out_file->f_op->sendpage)
 745                 goto fput_out;
 746         out_inode = out_file->f_path.dentry->d_inode;
 747         retval = rw_verify_area(WRITE, out_file, &out_file->f_pos, count);
 748         if (retval < 0)
 749                 goto fput_out;
 750         count = retval;
 751
 752         if (!max)
 753                 max = min(in_inode->i_sb->s_maxbytes, out_inode->i_sb->s_maxbytes);
 754
 755         pos = *ppos;
 756         retval = -EINVAL;
 757         if (unlikely(pos < 0))
 758                 goto fput_out;
 759         if (unlikely(pos + count > max)) {
 760                 retval = -EOVERFLOW;
 761                 if (pos >= max)
 762                         goto fput_out;
 763                 count = max - pos;
 764         }
 765
 766         fl = 0;
 767 #if 0
 768         /*
 769          * We need to debate whether we can enable this or not. The
 770          * man page documents EAGAIN return for the output at least,
 771          * and the application is arguably buggy if it doesn't expect
 772          * EAGAIN on a non-blocking file descriptor.
 773          */
 774         if (in_file->f_flags & O_NONBLOCK)
 775                 fl = SPLICE_F_NONBLOCK;
 776 #endif
 777         retval = do_splice_direct(in_file, ppos, out_file, count, fl);
 778
 779         if (retval > 0) {
 780                 add_rchar(current, retval);
 781                 add_wchar(current, retval);
 782         }
 783
 784         inc_syscr(current);
 785         inc_syscw(current);
 786         if (*ppos > max)
 787                 retval = -EOVERFLOW;
 788
 789 fput_out:
 790         fput_light(out_file, fput_needed_out);
 791 fput_in:
 792         fput_light(in_file, fput_needed_in);
 793 out:
 794         return retval;
 795 }
 796
 797 SYSCALL_DEFINE4(sendfile, int, out_fd, int, in_fd, off_t __user *, offset, size_t, count)
 798 {
 799         loff_t pos;
 800         off_t off;
 801         ssize_t ret;
 802
 803         if (offset) {
 804                 if (unlikely(get_user(off, offset)))
 805                         return -EFAULT;
 806                 pos = off;
 807                 ret = do_sendfile(out_fd, in_fd, &pos, count, MAX_NON_LFS);
 808                 if (unlikely(put_user(pos, offset)))
 809                         return -EFAULT;
 810                 return ret;
 811         }
 812
 813         return do_sendfile(out_fd, in_fd, NULL, count, 0);
 814 }
 815
 816 SYSCALL_DEFINE4(sendfile64, int, out_fd, int, in_fd, loff_t __user *, offset, size_t, count)
 817 {
 818         loff_t pos;
 819         ssize_t ret;
 820
 821         if (offset) {
 822                 if (unlikely(copy_from_user(&pos, offset, sizeof(loff_t))))
 823                         return -EFAULT;
 824                 ret = do_sendfile(out_fd, in_fd, &pos, count, 0);
 825                 if (unlikely(put_user(pos, offset)))
 826                         return -EFAULT;
 827                 return ret;
 828         }
 829
 830         return do_sendfile(out_fd, in_fd, NULL, count, 0);
 831 }