lib/ext2fs/unix_io.c

   1 /*
   2  * unix_io.c --- This is the Unix (well, really POSIX) implementation
   3  *      of the I/O manager.
   4  *
   5  * Implements a one-block write-through cache.
   6  *
   7  * Includes support for Windows NT support under Cygwin.
   8  *
   9  * Copyright (C) 1993, 1994, 1995, 1996, 1997, 1998, 1999, 2000, 2001,
  10  *      2002 by Theodore Ts'o.
  11  *
  12  * %Begin-Header%
  13  * This file may be redistributed under the terms of the GNU Library
  14  * General Public License, version 2.
  15  * %End-Header%
  16  */
  17
  18 #define _LARGEFILE_SOURCE
  19 #define _LARGEFILE64_SOURCE
  20 #define _GNU_SOURCE
  21
  22 #include <stdio.h>
  23 #include <string.h>
  24 #if HAVE_UNISTD_H
  25 #include <unistd.h>
  26 #endif
  27 #if HAVE_ERRNO_H
  28 #include <errno.h>
  29 #endif
  30 #include <fcntl.h>
  31 #include <time.h>
  32 #ifdef __linux__
  33 #include <sys/utsname.h>
  34 #endif
  35 #ifdef HAVE_SYS_IOCTL_H
  36 #include <sys/ioctl.h>
  37 #endif
  38 #ifdef HAVE_SYS_MOUNT_H
  39 #include <sys/mount.h>
  40 #endif
  41 #if HAVE_SYS_STAT_H
  42 #include <sys/stat.h>
  43 #endif
  44 #if HAVE_SYS_TYPES_H
  45 #include <sys/types.h>
  46 #endif
  47 #if HAVE_SYS_RESOURCE_H
  48 #include <sys/resource.h>
  49 #endif
  50
  51 #if defined(__linux__) && defined(_IO) && !defined(BLKROGET)
  52 #define BLKROGET   _IO(0x12, 94) /* Get read-only status (0 = read_write).  */
  53 #endif
  54
  55 #if defined(__linux__) && defined(_IO) && !defined(BLKSSZGET)
  56 #define BLKSSZGET  _IO(0x12,104)/* get block device sector size */
  57 #endif
  58
  59 #undef ALIGN_DEBUG
  60
  61 #include "ext2_fs.h"
  62 #include "ext2fs.h"
  63
  64 /*
  65  * For checking structure magic numbers...
  66  */
  67
  68 #define EXT2_CHECK_MAGIC(struct, code) \
  69           if ((struct)->magic != (code)) return (code)
  70
  71 struct unix_cache {
  72         char            *buf;
  73         unsigned long   block;
  74         int             access_time;
  75         unsigned        dirty:1;
  76         unsigned        in_use:1;
  77 };
  78
  79 #define CACHE_SIZE 8
  80 #define WRITE_DIRECT_SIZE 4     /* Must be smaller than CACHE_SIZE */
  81 #define READ_DIRECT_SIZE 4      /* Should be smaller than CACHE_SIZE */
  82
  83 struct unix_private_data {
  84         int     magic;
  85         int     dev;
  86         int     flags;
  87         int     align;
  88         int     access_time;
  89         ext2_loff_t offset;
  90         struct unix_cache cache[CACHE_SIZE];
  91         void    *bounce;
  92         struct struct_io_stats io_stats;
  93 };
  94
  95 #define IS_ALIGNED(n, align) ((((unsigned long) n) & \
  96                                ((unsigned long) ((align)-1))) == 0)
  97
  98 static errcode_t unix_open(const char *name, int flags, io_channel *channel);
  99 static errcode_t unix_close(io_channel channel);
 100 static errcode_t unix_set_blksize(io_channel channel, int blksize);
 101 static errcode_t unix_read_blk(io_channel channel, unsigned long block,
 102                                int count, void *data);
 103 static errcode_t unix_write_blk(io_channel channel, unsigned long block,
 104                                 int count, const void *data);
 105 static errcode_t unix_flush(io_channel channel);
 106 static errcode_t unix_write_byte(io_channel channel, unsigned long offset,
 107                                 int size, const void *data);
 108 static errcode_t unix_set_option(io_channel channel, const char *option,
 109                                  const char *arg);
 110 static errcode_t unix_get_stats(io_channel channel, io_stats *stats)
 111 ;
 112 static void reuse_cache(io_channel channel, struct unix_private_data *data,
 113                  struct unix_cache *cache, unsigned long long block);
 114 static errcode_t unix_read_blk64(io_channel channel, unsigned long long block,
 115                                int count, void *data);
 116 static errcode_t unix_write_blk64(io_channel channel, unsigned long long block,
 117                                 int count, const void *data);
 118 static errcode_t unix_discard(io_channel channel, unsigned long long block,
 119                               unsigned long long count);
 120
 121 static struct struct_io_manager struct_unix_manager = {
 122         EXT2_ET_MAGIC_IO_MANAGER,
 123         "Unix I/O Manager",
 124         unix_open,
 125         unix_close,
 126         unix_set_blksize,
 127         unix_read_blk,
 128         unix_write_blk,
 129         unix_flush,
 130         unix_write_byte,
 131         unix_set_option,
 132         unix_get_stats,
 133         unix_read_blk64,
 134         unix_write_blk64,
 135         unix_discard,
 136 };
 137
 138 io_manager unix_io_manager = &struct_unix_manager;
 139
 140 static errcode_t unix_get_stats(io_channel channel, io_stats *stats)
 141 {
 142         errcode_t       retval = 0;
 143
 144         struct unix_private_data *data;
 145
 146         EXT2_CHECK_MAGIC(channel, EXT2_ET_MAGIC_IO_CHANNEL);
 147         data = (struct unix_private_data *) channel->private_data;
 148         EXT2_CHECK_MAGIC(data, EXT2_ET_MAGIC_UNIX_IO_CHANNEL);
 149
 150         if (stats)
 151                 *stats = &data->io_stats;
 152
 153         return retval;
 154 }
 155
 156 /*
 157  * Here are the raw I/O functions
 158  */
 159 static errcode_t raw_read_blk(io_channel channel,
 160                               struct unix_private_data *data,
 161                               unsigned long long block,
 162                               int count, void *buf)
 163 {
 164         errcode_t       retval;
 165         ssize_t         size;
 166         ext2_loff_t     location;
 167         int             actual = 0;
 168
 169         size = (count < 0) ? -count : count * channel->block_size;
 170         data->io_stats.bytes_read += size;
 171         location = ((ext2_loff_t) block * channel->block_size) + data->offset;
 172         if (ext2fs_llseek(data->dev, location, SEEK_SET) != location) {
 173                 retval = errno ? errno : EXT2_ET_LLSEEK_FAILED;
 174                 goto error_out;
 175         }
 176         if ((data->align == 0) ||
 177             ((IS_ALIGNED(buf, data->align)) && IS_ALIGNED(size, data->align))) {
 178                 actual = read(data->dev, buf, size);
 179                 if (actual != size) {
 180                 short_read:
 181                         if (actual < 0)
 182                                 actual = 0;
 183                         retval = EXT2_ET_SHORT_READ;
 184                         goto error_out;
 185                 }
 186                 return 0;
 187         }
 188
 189 #ifdef ALIGN_DEBUG
 190         printf("raw_read_blk: O_DIRECT fallback: %p %lu\n", buf,
 191                (unsigned long) size);
 192 #endif
 193
 194         /*
 195          * The buffer or size which we're trying to read isn't aligned
 196          * to the O_DIRECT rules, so we need to do this the hard way...
 197          */
 198         while (size > 0) {
 199                 actual = read(data->dev, data->bounce, channel->block_size);
 200                 if (actual != channel->block_size)
 201                         goto short_read;
 202                 actual = size;
 203                 if (size > channel->block_size)
 204                         actual = channel->block_size;
 205                 memcpy(buf, data->bounce, actual);
 206                 size -= actual;
 207                 buf += actual;
 208         }
 209         return 0;
 210
 211 error_out:
 212         memset((char *) buf+actual, 0, size-actual);
 213         if (channel->read_error)
 214                 retval = (channel->read_error)(channel, block, count, buf,
 215                                                size, actual, retval);
 216         return retval;
 217 }
 218
 219 static errcode_t raw_write_blk(io_channel channel,
 220                                struct unix_private_data *data,
 221                                unsigned long long block,
 222                                int count, const void *buf)
 223 {
 224         ssize_t         size;
 225         ext2_loff_t     location;
 226         int             actual = 0;
 227         errcode_t       retval;
 228
 229         if (count == 1)
 230                 size = channel->block_size;
 231         else {
 232                 if (count < 0)
 233                         size = -count;
 234                 else
 235                         size = count * channel->block_size;
 236         }
 237         data->io_stats.bytes_written += size;
 238
 239         location = ((ext2_loff_t) block * channel->block_size) + data->offset;
 240         if (ext2fs_llseek(data->dev, location, SEEK_SET) != location) {
 241                 retval = errno ? errno : EXT2_ET_LLSEEK_FAILED;
 242                 goto error_out;
 243         }
 244
 245         if ((data->align == 0) ||
 246             ((IS_ALIGNED(buf, data->align)) && IS_ALIGNED(size, data->align))) {
 247                 actual = write(data->dev, buf, size);
 248                 if (actual != size) {
 249                 short_write:
 250                         retval = EXT2_ET_SHORT_WRITE;
 251                         goto error_out;
 252                 }
 253                 return 0;
 254         }
 255
 256 #ifdef ALIGN_DEBUG
 257         printf("raw_write_blk: O_DIRECT fallback: %p %lu\n", buf,
 258                (unsigned long) size);
 259 #endif
 260         /*
 261          * The buffer or size which we're trying to write isn't aligned
 262          * to the O_DIRECT rules, so we need to do this the hard way...
 263          */
 264         while (size > 0) {
 265                 if (size < channel->block_size) {
 266                         actual = read(data->dev, data->bounce,
 267                                       channel->block_size);
 268                         if (actual != channel->block_size) {
 269                                 retval = EXT2_ET_SHORT_READ;
 270                                 goto error_out;
 271                         }
 272                 }
 273                 actual = size;
 274                 if (size > channel->block_size)
 275                         actual = channel->block_size;
 276                 memcpy(data->bounce, buf, actual);
 277                 actual = write(data->dev, data->bounce, channel->block_size);
 278                 if (actual != channel->block_size)
 279                         goto short_write;
 280                 size -= actual;
 281                 buf += actual;
 282         }
 283         return 0;
 284
 285 error_out:
 286         if (channel->write_error)
 287                 retval = (channel->write_error)(channel, block, count, buf,
 288                                                 size, actual, retval);
 289         return retval;
 290 }
 291
 292
 293 /*
 294  * Here we implement the cache functions
 295  */
 296
 297 /* Allocate the cache buffers */
 298 static errcode_t alloc_cache(io_channel channel,
 299                              struct unix_private_data *data)
 300 {
 301         errcode_t               retval;
 302         struct unix_cache       *cache;
 303         int                     i;
 304
 305         data->access_time = 0;
 306         for (i=0, cache = data->cache; i < CACHE_SIZE; i++, cache++) {
 307                 cache->block = 0;
 308                 cache->access_time = 0;
 309                 cache->dirty = 0;
 310                 cache->in_use = 0;
 311                 if (cache->buf)
 312                         ext2fs_free_mem(&cache->buf);
 313                 retval = ext2fs_get_memalign(channel->block_size,
 314                                              data->align, &cache->buf);
 315                 if (retval)
 316                         return retval;
 317         }
 318         if (data->align) {
 319                 if (data->bounce)
 320                         ext2fs_free_mem(&data->bounce);
 321                 retval = ext2fs_get_memalign(channel->block_size, data->align,
 322                                              &data->bounce);
 323         }
 324         return retval;
 325 }
 326
 327 /* Free the cache buffers */
 328 static void free_cache(struct unix_private_data *data)
 329 {
 330         struct unix_cache       *cache;
 331         int                     i;
 332
 333         data->access_time = 0;
 334         for (i=0, cache = data->cache; i < CACHE_SIZE; i++, cache++) {
 335                 cache->block = 0;
 336                 cache->access_time = 0;
 337                 cache->dirty = 0;
 338                 cache->in_use = 0;
 339                 if (cache->buf)
 340                         ext2fs_free_mem(&cache->buf);
 341         }
 342         if (data->bounce)
 343                 ext2fs_free_mem(&data->bounce);
 344 }
 345
 346 #ifndef NO_IO_CACHE
 347 /*
 348  * Try to find a block in the cache.  If the block is not found, and
 349  * eldest is a non-zero pointer, then fill in eldest with the cache
 350  * entry to that should be reused.
 351  */
 352 static struct unix_cache *find_cached_block(struct unix_private_data *data,
 353                                             unsigned long long block,
 354                                             struct unix_cache **eldest)
 355 {
 356         struct unix_cache       *cache, *unused_cache, *oldest_cache;
 357         int                     i;
 358
 359         unused_cache = oldest_cache = 0;
 360         for (i=0, cache = data->cache; i < CACHE_SIZE; i++, cache++) {
 361                 if (!cache->in_use) {
 362                         if (!unused_cache)
 363                                 unused_cache = cache;
 364                         continue;
 365                 }
 366                 if (cache->block == block) {
 367                         cache->access_time = ++data->access_time;
 368                         return cache;
 369                 }
 370                 if (!oldest_cache ||
 371                     (cache->access_time < oldest_cache->access_time))
 372                         oldest_cache = cache;
 373         }
 374         if (eldest)
 375                 *eldest = (unused_cache) ? unused_cache : oldest_cache;
 376         return 0;
 377 }
 378
 379 /*
 380  * Reuse a particular cache entry for another block.
 381  */
 382 static void reuse_cache(io_channel channel, struct unix_private_data *data,
 383                  struct unix_cache *cache, unsigned long long block)
 384 {
 385         if (cache->dirty && cache->in_use)
 386                 raw_write_blk(channel, data, cache->block, 1, cache->buf);
 387
 388         cache->in_use = 1;
 389         cache->dirty = 0;
 390         cache->block = block;
 391         cache->access_time = ++data->access_time;
 392 }
 393
 394 /*
 395  * Flush all of the blocks in the cache
 396  */
 397 static errcode_t flush_cached_blocks(io_channel channel,
 398                                      struct unix_private_data *data,
 399                                      int invalidate)
 400
 401 {
 402         struct unix_cache       *cache;
 403         errcode_t               retval, retval2;
 404         int                     i;
 405
 406         retval2 = 0;
 407         for (i=0, cache = data->cache; i < CACHE_SIZE; i++, cache++) {
 408                 if (!cache->in_use)
 409                         continue;
 410
 411                 if (invalidate)
 412                         cache->in_use = 0;
 413
 414                 if (!cache->dirty)
 415                         continue;
 416
 417                 retval = raw_write_blk(channel, data,
 418                                        cache->block, 1, cache->buf);
 419                 if (retval)
 420                         retval2 = retval;
 421                 else
 422                         cache->dirty = 0;
 423         }
 424         return retval2;
 425 }
 426 #endif /* NO_IO_CACHE */
 427
 428 #ifdef __linux__
 429 #ifndef BLKDISCARDZEROES
 430 #define BLKDISCARDZEROES _IO(0x12,124)
 431 #endif
 432 #endif
 433
 434 static errcode_t unix_open(const char *name, int flags, io_channel *channel)
 435 {
 436         io_channel      io = NULL;
 437         struct unix_private_data *data = NULL;
 438         errcode_t       retval;
 439         int             open_flags, zeroes = 0;
 440         struct stat     st;
 441 #ifdef __linux__
 442         struct          utsname ut;
 443 #endif
 444
 445         if (name == 0)
 446                 return EXT2_ET_BAD_DEVICE_NAME;
 447         retval = ext2fs_get_mem(sizeof(struct struct_io_channel), &io);
 448         if (retval)
 449                 return retval;
 450         memset(io, 0, sizeof(struct struct_io_channel));
 451         io->magic = EXT2_ET_MAGIC_IO_CHANNEL;
 452         retval = ext2fs_get_mem(sizeof(struct unix_private_data), &data);
 453         if (retval)
 454                 goto cleanup;
 455
 456         io->manager = unix_io_manager;
 457         retval = ext2fs_get_mem(strlen(name)+1, &io->name);
 458         if (retval)
 459                 goto cleanup;
 460
 461         strcpy(io->name, name);
 462         io->private_data = data;
 463         io->block_size = 1024;
 464         io->read_error = 0;
 465         io->write_error = 0;
 466         io->refcount = 1;
 467
 468         memset(data, 0, sizeof(struct unix_private_data));
 469         data->magic = EXT2_ET_MAGIC_UNIX_IO_CHANNEL;
 470         data->io_stats.num_fields = 2;
 471
 472         open_flags = (flags & IO_FLAG_RW) ? O_RDWR : O_RDONLY;
 473         if (flags & IO_FLAG_EXCLUSIVE)
 474                 open_flags |= O_EXCL;
 475         if (flags & IO_FLAG_DIRECT_IO)
 476                 open_flags |= O_DIRECT;
 477         data->flags = flags;
 478
 479 #ifdef HAVE_OPEN64
 480         data->dev = open64(io->name, open_flags);
 481 #else
 482         data->dev = open(io->name, open_flags);
 483 #endif
 484         if (data->dev < 0) {
 485                 retval = errno;
 486                 goto cleanup;
 487         }
 488
 489 #ifdef BLKSSZGET
 490         if (flags & IO_FLAG_DIRECT_IO) {
 491                 if (ioctl(data->dev, BLKSSZGET, &data->align) != 0)
 492                         data->align = io->block_size;
 493         }
 494 #endif
 495
 496 #ifdef BLKDISCARDZEROES
 497         ioctl(data->dev, BLKDISCARDZEROES, &zeroes);
 498         if (zeroes)
 499                 io->flags |= CHANNEL_FLAGS_DISCARD_ZEROES;
 500 #endif
 501
 502 #if defined(__CYGWIN__) || defined(__FreeBSD__) || defined(__FreeBSD_kernel__)
 503         /*
 504          * Some operating systems require that the buffers be aligned,
 505          * regardless of O_DIRECT
 506          */
 507         data->align = 512;
 508 #endif
 509
 510
 511         if ((retval = alloc_cache(io, data)))
 512                 goto cleanup;
 513
 514 #ifdef BLKROGET
 515         if (flags & IO_FLAG_RW) {
 516                 int error;
 517                 int readonly = 0;
 518
 519                 /* Is the block device actually writable? */
 520                 error = ioctl(data->dev, BLKROGET, &readonly);
 521                 if (!error && readonly) {
 522                         close(data->dev);
 523                         retval = EPERM;
 524                         goto cleanup;
 525                 }
 526         }
 527 #endif
 528
 529 #ifdef __linux__
 530 #undef RLIM_INFINITY
 531 #if (defined(__alpha__) || ((defined(__sparc__) || defined(__mips__)) && (SIZEOF_LONG == 4)))
 532 #define RLIM_INFINITY   ((unsigned long)(~0UL>>1))
 533 #else
 534 #define RLIM_INFINITY  (~0UL)
 535 #endif
 536         /*
 537          * Work around a bug in 2.4.10-2.4.18 kernels where writes to
 538          * block devices are wrongly getting hit by the filesize
 539          * limit.  This workaround isn't perfect, since it won't work
 540          * if glibc wasn't built against 2.2 header files.  (Sigh.)
 541          *
 542          */
 543         if ((flags & IO_FLAG_RW) &&
 544             (uname(&ut) == 0) &&
 545             ((ut.release[0] == '2') && (ut.release[1] == '.') &&
 546              (ut.release[2] == '4') && (ut.release[3] == '.') &&
 547              (ut.release[4] == '1') && (ut.release[5] >= '0') &&
 548              (ut.release[5] < '8')) &&
 549             (fstat(data->dev, &st) == 0) &&
 550             (S_ISBLK(st.st_mode))) {
 551                 struct rlimit   rlim;
 552
 553                 rlim.rlim_cur = rlim.rlim_max = (unsigned long) RLIM_INFINITY;
 554                 setrlimit(RLIMIT_FSIZE, &rlim);
 555                 getrlimit(RLIMIT_FSIZE, &rlim);
 556                 if (((unsigned long) rlim.rlim_cur) <
 557                     ((unsigned long) rlim.rlim_max)) {
 558                         rlim.rlim_cur = rlim.rlim_max;
 559                         setrlimit(RLIMIT_FSIZE, &rlim);
 560                 }
 561         }
 562 #endif
 563         *channel = io;
 564         return 0;
 565
 566 cleanup:
 567         if (data) {
 568                 free_cache(data);
 569                 ext2fs_free_mem(&data);
 570         }
 571         if (io)
 572                 ext2fs_free_mem(&io);
 573         return retval;
 574 }
 575
 576 static errcode_t unix_close(io_channel channel)
 577 {
 578         struct unix_private_data *data;
 579         errcode_t       retval = 0;
 580
 581         EXT2_CHECK_MAGIC(channel, EXT2_ET_MAGIC_IO_CHANNEL);
 582         data = (struct unix_private_data *) channel->private_data;
 583         EXT2_CHECK_MAGIC(data, EXT2_ET_MAGIC_UNIX_IO_CHANNEL);
 584
 585         if (--channel->refcount > 0)
 586                 return 0;
 587
 588 #ifndef NO_IO_CACHE
 589         retval = flush_cached_blocks(channel, data, 0);
 590 #endif
 591
 592         if (close(data->dev) < 0)
 593                 retval = errno;
 594         free_cache(data);
 595
 596         ext2fs_free_mem(&channel->private_data);
 597         if (channel->name)
 598                 ext2fs_free_mem(&channel->name);
 599         ext2fs_free_mem(&channel);
 600         return retval;
 601 }
 602
 603 static errcode_t unix_set_blksize(io_channel channel, int blksize)
 604 {
 605         struct unix_private_data *data;
 606         errcode_t               retval;
 607
 608         EXT2_CHECK_MAGIC(channel, EXT2_ET_MAGIC_IO_CHANNEL);
 609         data = (struct unix_private_data *) channel->private_data;
 610         EXT2_CHECK_MAGIC(data, EXT2_ET_MAGIC_UNIX_IO_CHANNEL);
 611
 612         if (channel->block_size != blksize) {
 613 #ifndef NO_IO_CACHE
 614                 if ((retval = flush_cached_blocks(channel, data, 0)))
 615                         return retval;
 616 #endif
 617
 618                 channel->block_size = blksize;
 619                 free_cache(data);
 620                 if ((retval = alloc_cache(channel, data)))
 621                         return retval;
 622         }
 623         return 0;
 624 }
 625
 626
 627 static errcode_t unix_read_blk64(io_channel channel, unsigned long long block,
 628                                int count, void *buf)
 629 {
 630         struct unix_private_data *data;
 631         struct unix_cache *cache, *reuse[READ_DIRECT_SIZE];
 632         errcode_t       retval;
 633         char            *cp;
 634         int             i, j;
 635
 636         EXT2_CHECK_MAGIC(channel, EXT2_ET_MAGIC_IO_CHANNEL);
 637         data = (struct unix_private_data *) channel->private_data;
 638         EXT2_CHECK_MAGIC(data, EXT2_ET_MAGIC_UNIX_IO_CHANNEL);
 639
 640 #ifdef NO_IO_CACHE
 641         return raw_read_blk(channel, data, block, count, buf);
 642 #else
 643         /*
 644          * If we're doing an odd-sized read or a very large read,
 645          * flush out the cache and then do a direct read.
 646          */
 647         if (count < 0 || count > WRITE_DIRECT_SIZE) {
 648                 if ((retval = flush_cached_blocks(channel, data, 0)))
 649                         return retval;
 650                 return raw_read_blk(channel, data, block, count, buf);
 651         }
 652
 653         cp = buf;
 654         while (count > 0) {
 655                 /* If it's in the cache, use it! */
 656                 if ((cache = find_cached_block(data, block, &reuse[0]))) {
 657 #ifdef DEBUG
 658                         printf("Using cached block %lu\n", block);
 659 #endif
 660                         memcpy(cp, cache->buf, channel->block_size);
 661                         count--;
 662                         block++;
 663                         cp += channel->block_size;
 664                         continue;
 665                 }
 666                 if (count == 1) {
 667                         /*
 668                          * Special case where we read directly into the
 669                          * cache buffer; important in the O_DIRECT case
 670                          */
 671                         cache = reuse[0];
 672                         reuse_cache(channel, data, cache, block);
 673                         if ((retval = raw_read_blk(channel, data, block, 1,
 674                                                    cache->buf))) {
 675                                 cache->in_use = 0;
 676                                 return retval;
 677                         }
 678                         memcpy(cp, cache->buf, channel->block_size);
 679                         return 0;
 680                 }
 681
 682                 /*
 683                  * Find the number of uncached blocks so we can do a
 684                  * single read request
 685                  */
 686                 for (i=1; i < count; i++)
 687                         if (find_cached_block(data, block+i, &reuse[i]))
 688                                 break;
 689 #ifdef DEBUG
 690                 printf("Reading %d blocks starting at %lu\n", i, block);
 691 #endif
 692                 if ((retval = raw_read_blk(channel, data, block, i, cp)))
 693                         return retval;
 694
 695                 /* Save the results in the cache */
 696                 for (j=0; j < i; j++) {
 697                         count--;
 698                         cache = reuse[j];
 699                         reuse_cache(channel, data, cache, block++);
 700                         memcpy(cache->buf, cp, channel->block_size);
 701                         cp += channel->block_size;
 702                 }
 703         }
 704         return 0;
 705 #endif /* NO_IO_CACHE */
 706 }
 707
 708 static errcode_t unix_read_blk(io_channel channel, unsigned long block,
 709                                int count, void *buf)
 710 {
 711         return unix_read_blk64(channel, block, count, buf);
 712 }
 713
 714 static errcode_t unix_write_blk64(io_channel channel, unsigned long long block,
 715                                 int count, const void *buf)
 716 {
 717         struct unix_private_data *data;
 718         struct unix_cache *cache, *reuse;
 719         errcode_t       retval = 0;
 720         const char      *cp;
 721         int             writethrough;
 722
 723         EXT2_CHECK_MAGIC(channel, EXT2_ET_MAGIC_IO_CHANNEL);
 724         data = (struct unix_private_data *) channel->private_data;
 725         EXT2_CHECK_MAGIC(data, EXT2_ET_MAGIC_UNIX_IO_CHANNEL);
 726
 727 #ifdef NO_IO_CACHE
 728         return raw_write_blk(channel, data, block, count, buf);
 729 #else
 730         /*
 731          * If we're doing an odd-sized write or a very large write,
 732          * flush out the cache completely and then do a direct write.
 733          */
 734         if (count < 0 || count > WRITE_DIRECT_SIZE) {
 735                 if ((retval = flush_cached_blocks(channel, data, 1)))
 736                         return retval;
 737                 return raw_write_blk(channel, data, block, count, buf);
 738         }
 739
 740         /*
 741          * For a moderate-sized multi-block write, first force a write
 742          * if we're in write-through cache mode, and then fill the
 743          * cache with the blocks.
 744          */
 745         writethrough = channel->flags & CHANNEL_FLAGS_WRITETHROUGH;
 746         if (writethrough)
 747                 retval = raw_write_blk(channel, data, block, count, buf);
 748
 749         cp = buf;
 750         while (count > 0) {
 751                 cache = find_cached_block(data, block, &reuse);
 752                 if (!cache) {
 753                         cache = reuse;
 754                         reuse_cache(channel, data, cache, block);
 755                 }
 756                 memcpy(cache->buf, cp, channel->block_size);
 757                 cache->dirty = !writethrough;
 758                 count--;
 759                 block++;
 760                 cp += channel->block_size;
 761         }
 762         return retval;
 763 #endif /* NO_IO_CACHE */
 764 }
 765
 766 static errcode_t unix_write_blk(io_channel channel, unsigned long block,
 767                                 int count, const void *buf)
 768 {
 769         return unix_write_blk64(channel, block, count, buf);
 770 }
 771
 772 static errcode_t unix_write_byte(io_channel channel, unsigned long offset,
 773                                  int size, const void *buf)
 774 {
 775         struct unix_private_data *data;
 776         errcode_t       retval = 0;
 777         ssize_t         actual;
 778
 779         EXT2_CHECK_MAGIC(channel, EXT2_ET_MAGIC_IO_CHANNEL);
 780         data = (struct unix_private_data *) channel->private_data;
 781         EXT2_CHECK_MAGIC(data, EXT2_ET_MAGIC_UNIX_IO_CHANNEL);
 782
 783         if (data->align != 0) {
 784 #ifdef ALIGN_DEBUG
 785                 printf("unix_write_byte: O_DIRECT fallback\n");
 786 #endif
 787                 return EXT2_ET_UNIMPLEMENTED;
 788         }
 789
 790 #ifndef NO_IO_CACHE
 791         /*
 792          * Flush out the cache completely
 793          */
 794         if ((retval = flush_cached_blocks(channel, data, 1)))
 795                 return retval;
 796 #endif
 797
 798         if (lseek(data->dev, offset + data->offset, SEEK_SET) < 0)
 799                 return errno;
 800
 801         actual = write(data->dev, buf, size);
 802         if (actual != size)
 803                 return EXT2_ET_SHORT_WRITE;
 804
 805         return 0;
 806 }
 807
 808 /*
 809  * Flush data buffers to disk.
 810  */
 811 static errcode_t unix_flush(io_channel channel)
 812 {
 813         struct unix_private_data *data;
 814         errcode_t retval = 0;
 815
 816         EXT2_CHECK_MAGIC(channel, EXT2_ET_MAGIC_IO_CHANNEL);
 817         data = (struct unix_private_data *) channel->private_data;
 818         EXT2_CHECK_MAGIC(data, EXT2_ET_MAGIC_UNIX_IO_CHANNEL);
 819
 820 #ifndef NO_IO_CACHE
 821         retval = flush_cached_blocks(channel, data, 0);
 822 #endif
 823         fsync(data->dev);
 824         return retval;
 825 }
 826
 827 static errcode_t unix_set_option(io_channel channel, const char *option,
 828                                  const char *arg)
 829 {
 830         struct unix_private_data *data;
 831         unsigned long long tmp;
 832         char *end;
 833
 834         EXT2_CHECK_MAGIC(channel, EXT2_ET_MAGIC_IO_CHANNEL);
 835         data = (struct unix_private_data *) channel->private_data;
 836         EXT2_CHECK_MAGIC(data, EXT2_ET_MAGIC_UNIX_IO_CHANNEL);
 837
 838         if (!strcmp(option, "offset")) {
 839                 if (!arg)
 840                         return EXT2_ET_INVALID_ARGUMENT;
 841
 842                 tmp = strtoull(arg, &end, 0);
 843                 if (*end)
 844                         return EXT2_ET_INVALID_ARGUMENT;
 845                 data->offset = tmp;
 846                 if (data->offset < 0)
 847                         return EXT2_ET_INVALID_ARGUMENT;
 848                 return 0;
 849         }
 850         return EXT2_ET_INVALID_ARGUMENT;
 851 }
 852
 853 #if defined(__linux__) && !defined(BLKDISCARD)
 854 #define BLKDISCARD      _IO(0x12,119)
 855 #endif
 856
 857 static errcode_t unix_discard(io_channel channel, unsigned long long block,
 858                               unsigned long long count)
 859 {
 860 #ifdef BLKDISCARD
 861         struct unix_private_data *data;
 862         __uint64_t      range[2];
 863         int             ret;
 864
 865         EXT2_CHECK_MAGIC(channel, EXT2_ET_MAGIC_IO_CHANNEL);
 866         data = (struct unix_private_data *) channel->private_data;
 867         EXT2_CHECK_MAGIC(data, EXT2_ET_MAGIC_UNIX_IO_CHANNEL);
 868
 869         range[0] = (__uint64_t)(block) * channel->block_size;
 870         range[1] = (__uint64_t)(count) * channel->block_size;
 871
 872         ret = ioctl(data->dev, BLKDISCARD, &range);
 873         if (ret < 0)
 874                 return errno;
 875         return 0;
 876 #else
 877         return EXT2_ET_UNIMPLEMENTED;
 878 #endif
 879 }