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 asmlinkage off_t sys_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 asmlinkage long sys_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 asmlinkage ssize_t sys_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 asmlinkage ssize_t sys_write(unsigned int fd, const char __user * buf, size_t count)
 355 {
 356         struct file *file;
 357         ssize_t ret = -EBADF;
 358         int fput_needed;
 359
 360         file = fget_light(fd, &fput_needed);
 361         if (file) {
 362                 loff_t pos = file_pos_read(file);
 363                 ret = vfs_write(file, buf, count, &pos);
 364                 file_pos_write(file, pos);
 365                 fput_light(file, fput_needed);
 366         }
 367
 368         return ret;
 369 }
 370
 371 asmlinkage ssize_t sys_pread64(unsigned int fd, char __user *buf,
 372                              size_t count, loff_t pos)
 373 {
 374         struct file *file;
 375         ssize_t ret = -EBADF;
 376         int fput_needed;
 377
 378         if (pos < 0)
 379                 return -EINVAL;
 380
 381         file = fget_light(fd, &fput_needed);
 382         if (file) {
 383                 ret = -ESPIPE;
 384                 if (file->f_mode & FMODE_PREAD)
 385                         ret = vfs_read(file, buf, count, &pos);
 386                 fput_light(file, fput_needed);
 387         }
 388
 389         return ret;
 390 }
 391
 392 asmlinkage ssize_t sys_pwrite64(unsigned int fd, const char __user *buf,
 393                               size_t count, loff_t pos)
 394 {
 395         struct file *file;
 396         ssize_t ret = -EBADF;
 397         int fput_needed;
 398
 399         if (pos < 0)
 400                 return -EINVAL;
 401
 402         file = fget_light(fd, &fput_needed);
 403         if (file) {
 404                 ret = -ESPIPE;
 405                 if (file->f_mode & FMODE_PWRITE)
 406                         ret = vfs_write(file, buf, count, &pos);
 407                 fput_light(file, fput_needed);
 408         }
 409
 410         return ret;
 411 }
 412
 413 /*
 414  * Reduce an iovec's length in-place.  Return the resulting number of segments
 415  */
 416 unsigned long iov_shorten(struct iovec *iov, unsigned long nr_segs, size_t to)
 417 {
 418         unsigned long seg = 0;
 419         size_t len = 0;
 420
 421         while (seg < nr_segs) {
 422                 seg++;
 423                 if (len + iov->iov_len >= to) {
 424                         iov->iov_len = to - len;
 425                         break;
 426                 }
 427                 len += iov->iov_len;
 428                 iov++;
 429         }
 430         return seg;
 431 }
 432 EXPORT_SYMBOL(iov_shorten);
 433
 434 ssize_t do_sync_readv_writev(struct file *filp, const struct iovec *iov,
 435                 unsigned long nr_segs, size_t len, loff_t *ppos, iov_fn_t fn)
 436 {
 437         struct kiocb kiocb;
 438         ssize_t ret;
 439
 440         init_sync_kiocb(&kiocb, filp);
 441         kiocb.ki_pos = *ppos;
 442         kiocb.ki_left = len;
 443         kiocb.ki_nbytes = len;
 444
 445         for (;;) {
 446                 ret = fn(&kiocb, iov, nr_segs, kiocb.ki_pos);
 447                 if (ret != -EIOCBRETRY)
 448                         break;
 449                 wait_on_retry_sync_kiocb(&kiocb);
 450         }
 451
 452         if (ret == -EIOCBQUEUED)
 453                 ret = wait_on_sync_kiocb(&kiocb);
 454         *ppos = kiocb.ki_pos;
 455         return ret;
 456 }
 457
 458 /* Do it by hand, with file-ops */
 459 ssize_t do_loop_readv_writev(struct file *filp, struct iovec *iov,
 460                 unsigned long nr_segs, loff_t *ppos, io_fn_t fn)
 461 {
 462         struct iovec *vector = iov;
 463         ssize_t ret = 0;
 464
 465         while (nr_segs > 0) {
 466                 void __user *base;
 467                 size_t len;
 468                 ssize_t nr;
 469
 470                 base = vector->iov_base;
 471                 len = vector->iov_len;
 472                 vector++;
 473                 nr_segs--;
 474
 475                 nr = fn(filp, base, len, ppos);
 476
 477                 if (nr < 0) {
 478                         if (!ret)
 479                                 ret = nr;
 480                         break;
 481                 }
 482                 ret += nr;
 483                 if (nr != len)
 484                         break;
 485         }
 486
 487         return ret;
 488 }
 489
 490 /* A write operation does a read from user space and vice versa */
 491 #define vrfy_dir(type) ((type) == READ ? VERIFY_WRITE : VERIFY_READ)
 492
 493 ssize_t rw_copy_check_uvector(int type, const struct iovec __user * uvector,
 494                               unsigned long nr_segs, unsigned long fast_segs,
 495                               struct iovec *fast_pointer,
 496                               struct iovec **ret_pointer)
 497   {
 498         unsigned long seg;
 499         ssize_t ret;
 500         struct iovec *iov = fast_pointer;
 501
 502         /*
 503          * SuS says "The readv() function *may* fail if the iovcnt argument
 504          * was less than or equal to 0, or greater than {IOV_MAX}.  Linux has
 505          * traditionally returned zero for zero segments, so...
 506          */
 507         if (nr_segs == 0) {
 508                 ret = 0;
 509                 goto out;
 510         }
 511
 512         /*
 513          * First get the "struct iovec" from user memory and
 514          * verify all the pointers
 515          */
 516         if (nr_segs > UIO_MAXIOV) {
 517                 ret = -EINVAL;
 518                 goto out;
 519         }
 520         if (nr_segs > fast_segs) {
 521                 iov = kmalloc(nr_segs*sizeof(struct iovec), GFP_KERNEL);
 522                 if (iov == NULL) {
 523                         ret = -ENOMEM;
 524                         goto out;
 525                 }
 526         }
 527         if (copy_from_user(iov, uvector, nr_segs*sizeof(*uvector))) {
 528                 ret = -EFAULT;
 529                 goto out;
 530         }
 531
 532         /*
 533          * According to the Single Unix Specification we should return EINVAL
 534          * if an element length is < 0 when cast to ssize_t or if the
 535          * total length would overflow the ssize_t return value of the
 536          * system call.
 537          */
 538         ret = 0;
 539         for (seg = 0; seg < nr_segs; seg++) {
 540                 void __user *buf = iov[seg].iov_base;
 541                 ssize_t len = (ssize_t)iov[seg].iov_len;
 542
 543                 /* see if we we're about to use an invalid len or if
 544                  * it's about to overflow ssize_t */
 545                 if (len < 0 || (ret + len < ret)) {
 546                         ret = -EINVAL;
 547                         goto out;
 548                 }
 549                 if (unlikely(!access_ok(vrfy_dir(type), buf, len))) {
 550                         ret = -EFAULT;
 551                         goto out;
 552                 }
 553
 554                 ret += len;
 555         }
 556 out:
 557         *ret_pointer = iov;
 558         return ret;
 559 }
 560
 561 static ssize_t do_readv_writev(int type, struct file *file,
 562                                const struct iovec __user * uvector,
 563                                unsigned long nr_segs, loff_t *pos)
 564 {
 565         size_t tot_len;
 566         struct iovec iovstack[UIO_FASTIOV];
 567         struct iovec *iov = iovstack;
 568         ssize_t ret;
 569         io_fn_t fn;
 570         iov_fn_t fnv;
 571
 572         if (!file->f_op) {
 573                 ret = -EINVAL;
 574                 goto out;
 575         }
 576
 577         ret = rw_copy_check_uvector(type, uvector, nr_segs,
 578                         ARRAY_SIZE(iovstack), iovstack, &iov);
 579         if (ret <= 0)
 580                 goto out;
 581
 582         tot_len = ret;
 583         ret = rw_verify_area(type, file, pos, tot_len);
 584         if (ret < 0)
 585                 goto out;
 586
 587         fnv = NULL;
 588         if (type == READ) {
 589                 fn = file->f_op->read;
 590                 fnv = file->f_op->aio_read;
 591         } else {
 592                 fn = (io_fn_t)file->f_op->write;
 593                 fnv = file->f_op->aio_write;
 594         }
 595
 596         if (fnv)
 597                 ret = do_sync_readv_writev(file, iov, nr_segs, tot_len,
 598                                                 pos, fnv);
 599         else
 600                 ret = do_loop_readv_writev(file, iov, nr_segs, pos, fn);
 601
 602 out:
 603         if (iov != iovstack)
 604                 kfree(iov);
 605         if ((ret + (type == READ)) > 0) {
 606                 if (type == READ)
 607                         fsnotify_access(file->f_path.dentry);
 608                 else
 609                         fsnotify_modify(file->f_path.dentry);
 610         }
 611         return ret;
 612 }
 613
 614 ssize_t vfs_readv(struct file *file, const struct iovec __user *vec,
 615                   unsigned long vlen, loff_t *pos)
 616 {
 617         if (!(file->f_mode & FMODE_READ))
 618                 return -EBADF;
 619         if (!file->f_op || (!file->f_op->aio_read && !file->f_op->read))
 620                 return -EINVAL;
 621
 622         return do_readv_writev(READ, file, vec, vlen, pos);
 623 }
 624
 625 EXPORT_SYMBOL(vfs_readv);
 626
 627 ssize_t vfs_writev(struct file *file, const struct iovec __user *vec,
 628                    unsigned long vlen, loff_t *pos)
 629 {
 630         if (!(file->f_mode & FMODE_WRITE))
 631                 return -EBADF;
 632         if (!file->f_op || (!file->f_op->aio_write && !file->f_op->write))
 633                 return -EINVAL;
 634
 635         return do_readv_writev(WRITE, file, vec, vlen, pos);
 636 }
 637
 638 EXPORT_SYMBOL(vfs_writev);
 639
 640 asmlinkage ssize_t
 641 sys_readv(unsigned long fd, const struct iovec __user *vec, unsigned long vlen)
 642 {
 643         struct file *file;
 644         ssize_t ret = -EBADF;
 645         int fput_needed;
 646
 647         file = fget_light(fd, &fput_needed);
 648         if (file) {
 649                 loff_t pos = file_pos_read(file);
 650                 ret = vfs_readv(file, vec, vlen, &pos);
 651                 file_pos_write(file, pos);
 652                 fput_light(file, fput_needed);
 653         }
 654
 655         if (ret > 0)
 656                 add_rchar(current, ret);
 657         inc_syscr(current);
 658         return ret;
 659 }
 660
 661 asmlinkage ssize_t
 662 sys_writev(unsigned long fd, const struct iovec __user *vec, unsigned long vlen)
 663 {
 664         struct file *file;
 665         ssize_t ret = -EBADF;
 666         int fput_needed;
 667
 668         file = fget_light(fd, &fput_needed);
 669         if (file) {
 670                 loff_t pos = file_pos_read(file);
 671                 ret = vfs_writev(file, vec, vlen, &pos);
 672                 file_pos_write(file, pos);
 673                 fput_light(file, fput_needed);
 674         }
 675
 676         if (ret > 0)
 677                 add_wchar(current, ret);
 678         inc_syscw(current);
 679         return ret;
 680 }
 681
 682 static ssize_t do_sendfile(int out_fd, int in_fd, loff_t *ppos,
 683                            size_t count, loff_t max)
 684 {
 685         struct file * in_file, * out_file;
 686         struct inode * in_inode, * out_inode;
 687         loff_t pos;
 688         ssize_t retval;
 689         int fput_needed_in, fput_needed_out, fl;
 690
 691         /*
 692          * Get input file, and verify that it is ok..
 693          */
 694         retval = -EBADF;
 695         in_file = fget_light(in_fd, &fput_needed_in);
 696         if (!in_file)
 697                 goto out;
 698         if (!(in_file->f_mode & FMODE_READ))
 699                 goto fput_in;
 700         retval = -EINVAL;
 701         in_inode = in_file->f_path.dentry->d_inode;
 702         if (!in_inode)
 703                 goto fput_in;
 704         if (!in_file->f_op || !in_file->f_op->splice_read)
 705                 goto fput_in;
 706         retval = -ESPIPE;
 707         if (!ppos)
 708                 ppos = &in_file->f_pos;
 709         else
 710                 if (!(in_file->f_mode & FMODE_PREAD))
 711                         goto fput_in;
 712         retval = rw_verify_area(READ, in_file, ppos, count);
 713         if (retval < 0)
 714                 goto fput_in;
 715         count = retval;
 716
 717         /*
 718          * Get output file, and verify that it is ok..
 719          */
 720         retval = -EBADF;
 721         out_file = fget_light(out_fd, &fput_needed_out);
 722         if (!out_file)
 723                 goto fput_in;
 724         if (!(out_file->f_mode & FMODE_WRITE))
 725                 goto fput_out;
 726         retval = -EINVAL;
 727         if (!out_file->f_op || !out_file->f_op->sendpage)
 728                 goto fput_out;
 729         out_inode = out_file->f_path.dentry->d_inode;
 730         retval = rw_verify_area(WRITE, out_file, &out_file->f_pos, count);
 731         if (retval < 0)
 732                 goto fput_out;
 733         count = retval;
 734
 735         if (!max)
 736                 max = min(in_inode->i_sb->s_maxbytes, out_inode->i_sb->s_maxbytes);
 737
 738         pos = *ppos;
 739         retval = -EINVAL;
 740         if (unlikely(pos < 0))
 741                 goto fput_out;
 742         if (unlikely(pos + count > max)) {
 743                 retval = -EOVERFLOW;
 744                 if (pos >= max)
 745                         goto fput_out;
 746                 count = max - pos;
 747         }
 748
 749         fl = 0;
 750 #if 0
 751         /*
 752          * We need to debate whether we can enable this or not. The
 753          * man page documents EAGAIN return for the output at least,
 754          * and the application is arguably buggy if it doesn't expect
 755          * EAGAIN on a non-blocking file descriptor.
 756          */
 757         if (in_file->f_flags & O_NONBLOCK)
 758                 fl = SPLICE_F_NONBLOCK;
 759 #endif
 760         retval = do_splice_direct(in_file, ppos, out_file, count, fl);
 761
 762         if (retval > 0) {
 763                 add_rchar(current, retval);
 764                 add_wchar(current, retval);
 765         }
 766
 767         inc_syscr(current);
 768         inc_syscw(current);
 769         if (*ppos > max)
 770                 retval = -EOVERFLOW;
 771
 772 fput_out:
 773         fput_light(out_file, fput_needed_out);
 774 fput_in:
 775         fput_light(in_file, fput_needed_in);
 776 out:
 777         return retval;
 778 }
 779
 780 asmlinkage ssize_t sys_sendfile(int out_fd, int in_fd, off_t __user *offset, size_t count)
 781 {
 782         loff_t pos;
 783         off_t off;
 784         ssize_t ret;
 785
 786         if (offset) {
 787                 if (unlikely(get_user(off, offset)))
 788                         return -EFAULT;
 789                 pos = off;
 790                 ret = do_sendfile(out_fd, in_fd, &pos, count, MAX_NON_LFS);
 791                 if (unlikely(put_user(pos, offset)))
 792                         return -EFAULT;
 793                 return ret;
 794         }
 795
 796         return do_sendfile(out_fd, in_fd, NULL, count, 0);
 797 }
 798
 799 asmlinkage ssize_t sys_sendfile64(int out_fd, int in_fd, loff_t __user *offset, size_t count)
 800 {
 801         loff_t pos;
 802         ssize_t ret;
 803
 804         if (offset) {
 805                 if (unlikely(copy_from_user(&pos, offset, sizeof(loff_t))))
 806                         return -EFAULT;
 807                 ret = do_sendfile(out_fd, in_fd, &pos, count, 0);
 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 }