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 #if !defined(__FreeBSD__) && !defined(__NetBSD__) && !defined(__OpenBSD__)
  19 #define _XOPEN_SOURCE 600
  20 #define _DARWIN_C_SOURCE
  21 #define _FILE_OFFSET_BITS 64
  22 #ifndef _LARGEFILE_SOURCE
  23 #define _LARGEFILE_SOURCE
  24 #endif
  25 #ifndef _LARGEFILE64_SOURCE
  26 #define _LARGEFILE64_SOURCE
  27 #endif
  28 #ifndef _GNU_SOURCE
  29 #define _GNU_SOURCE
  30 #endif
  31 #endif
  32
  33 #include "config.h"
  34 #include <stdio.h>
  35 #include <string.h>
  36 #if HAVE_UNISTD_H
  37 #include <unistd.h>
  38 #endif
  39 #if HAVE_ERRNO_H
  40 #include <errno.h>
  41 #endif
  42 #include <fcntl.h>
  43 #include <time.h>
  44 #ifdef __linux__
  45 #include <sys/utsname.h>
  46 #endif
  47 #if HAVE_SYS_TYPES_H
  48 #include <sys/types.h>
  49 #endif
  50 #ifdef HAVE_SYS_IOCTL_H
  51 #include <sys/ioctl.h>
  52 #endif
  53 #ifdef HAVE_SYS_MOUNT_H
  54 #include <sys/mount.h>
  55 #endif
  56 #ifdef HAVE_SYS_PRCTL_H
  57 #include <sys/prctl.h>
  58 #else
  59 #define PR_GET_DUMPABLE 3
  60 #endif
  61 #if HAVE_SYS_STAT_H
  62 #include <sys/stat.h>
  63 #endif
  64 #if HAVE_SYS_RESOURCE_H
  65 #include <sys/resource.h>
  66 #endif
  67 #if HAVE_LINUX_FALLOC_H
  68 #include <linux/falloc.h>
  69 #endif
  70 #ifdef HAVE_PTHREAD
  71 #include <pthread.h>
  72 #endif
  73
  74 #if defined(__linux__) && defined(_IO) && !defined(BLKROGET)
  75 #define BLKROGET   _IO(0x12, 94) /* Get read-only status (0 = read_write).  */
  76 #endif
  77
  78 #undef ALIGN_DEBUG
  79
  80 #include "ext2_fs.h"
  81 #include "ext2fs.h"
  82 #include "ext2fsP.h"
  83
  84 /*
  85  * For checking structure magic numbers...
  86  */
  87
  88 #define EXT2_CHECK_MAGIC(struct, code) \
  89           if ((struct)->magic != (code)) return (code)
  90
  91 struct unix_cache {
  92         char                    *buf;
  93         unsigned long long      block;
  94         int                     access_time;
  95         unsigned                dirty:1;
  96         unsigned                in_use:1;
  97         unsigned                write_err:1;
  98 };
  99
 100 #define CACHE_SIZE 8
 101 #define WRITE_DIRECT_SIZE 4     /* Must be smaller than CACHE_SIZE */
 102 #define READ_DIRECT_SIZE 4      /* Should be smaller than CACHE_SIZE */
 103
 104 struct unix_private_data {
 105         int     magic;
 106         int     dev;
 107         int     flags;
 108         int     align;
 109         int     access_time;
 110         ext2_loff_t offset;
 111         struct unix_cache cache[CACHE_SIZE];
 112         void    *bounce;
 113         struct struct_io_stats io_stats;
 114 #ifdef HAVE_PTHREAD
 115         pthread_mutex_t cache_mutex;
 116         pthread_mutex_t bounce_mutex;
 117         pthread_mutex_t stats_mutex;
 118 #endif
 119 };
 120
 121 #define IS_ALIGNED(n, align) ((((uintptr_t) n) & \
 122                                ((uintptr_t) ((align)-1))) == 0)
 123
 124 typedef enum lock_kind {
 125         CACHE_MTX, BOUNCE_MTX, STATS_MTX
 126 } kind_t;
 127
 128 #ifdef HAVE_PTHREAD
 129 static inline pthread_mutex_t *get_mutex(struct unix_private_data *data,
 130                                          kind_t kind)
 131 {
 132         if (data->flags & IO_FLAG_THREADS) {
 133                 switch (kind) {
 134                 case CACHE_MTX:
 135                         return &data->cache_mutex;
 136                 case BOUNCE_MTX:
 137                         return &data->bounce_mutex;
 138                 case STATS_MTX:
 139                         return &data->stats_mutex;
 140                 }
 141         }
 142         return NULL;
 143 }
 144 #endif
 145
 146 static inline void mutex_lock(struct unix_private_data *data, kind_t kind)
 147 {
 148 #ifdef HAVE_PTHREAD
 149         pthread_mutex_t *mtx = get_mutex(data,kind);
 150
 151         if (mtx)
 152                 pthread_mutex_lock(mtx);
 153 #endif
 154 }
 155
 156 static inline void mutex_unlock(struct unix_private_data *data, kind_t kind)
 157 {
 158 #ifdef HAVE_PTHREAD
 159         pthread_mutex_t *mtx = get_mutex(data,kind);
 160
 161         if (mtx)
 162                 pthread_mutex_unlock(mtx);
 163 #endif
 164 }
 165
 166 static errcode_t unix_get_stats(io_channel channel, io_stats *stats)
 167 {
 168         errcode_t       retval = 0;
 169
 170         struct unix_private_data *data;
 171
 172         EXT2_CHECK_MAGIC(channel, EXT2_ET_MAGIC_IO_CHANNEL);
 173         data = (struct unix_private_data *) channel->private_data;
 174         EXT2_CHECK_MAGIC(data, EXT2_ET_MAGIC_UNIX_IO_CHANNEL);
 175
 176         if (stats) {
 177                 mutex_lock(data, STATS_MTX);
 178                 *stats = &data->io_stats;
 179                 mutex_unlock(data, STATS_MTX);
 180         }
 181
 182         return retval;
 183 }
 184
 185 static char *safe_getenv(const char *arg)
 186 {
 187         if ((getuid() != geteuid()) || (getgid() != getegid()))
 188                 return NULL;
 189 #ifdef HAVE_PRCTL
 190         if (prctl(PR_GET_DUMPABLE, 0, 0, 0, 0) == 0)
 191                 return NULL;
 192 #else
 193 #if (defined(linux) && defined(SYS_prctl))
 194         if (syscall(SYS_prctl, PR_GET_DUMPABLE, 0, 0, 0, 0) == 0)
 195                 return NULL;
 196 #endif
 197 #endif
 198
 199 #if defined(HAVE_SECURE_GETENV)
 200         return secure_getenv(arg);
 201 #elif defined(HAVE___SECURE_GETENV)
 202         return __secure_getenv(arg);
 203 #else
 204         return getenv(arg);
 205 #endif
 206 }
 207
 208 /*
 209  * Here are the raw I/O functions
 210  */
 211 static errcode_t raw_read_blk(io_channel channel,
 212                               struct unix_private_data *data,
 213                               unsigned long long block,
 214                               int count, void *bufv)
 215 {
 216         errcode_t       retval;
 217         ssize_t         size;
 218         ext2_loff_t     location;
 219         int             actual = 0;
 220         unsigned char   *buf = bufv;
 221         ssize_t         really_read = 0;
 222         unsigned long long aligned_blk;
 223         int             align_size, offset;
 224
 225         size = (count < 0) ? -count : (ext2_loff_t) count * channel->block_size;
 226         mutex_lock(data, STATS_MTX);
 227         data->io_stats.bytes_read += size;
 228         mutex_unlock(data, STATS_MTX);
 229         location = ((ext2_loff_t) block * channel->block_size) + data->offset;
 230
 231         if (data->flags & IO_FLAG_FORCE_BOUNCE)
 232                 goto bounce_read;
 233
 234 #ifdef HAVE_PREAD64
 235         /* Try an aligned pread */
 236         if ((channel->align == 0) ||
 237             (IS_ALIGNED(buf, channel->align) &&
 238              IS_ALIGNED(location, channel->align) &&
 239              IS_ALIGNED(size, channel->align))) {
 240                 actual = pread64(data->dev, buf, size, location);
 241                 if (actual == size)
 242                         return 0;
 243                 actual = 0;
 244         }
 245 #elif HAVE_PREAD
 246         /* Try an aligned pread */
 247         if ((sizeof(off_t) >= sizeof(ext2_loff_t)) &&
 248             ((channel->align == 0) ||
 249              (IS_ALIGNED(buf, channel->align) &&
 250               IS_ALIGNED(location, channel->align) &&
 251               IS_ALIGNED(size, channel->align)))) {
 252                 actual = pread(data->dev, buf, size, location);
 253                 if (actual == size)
 254                         return 0;
 255                 actual = 0;
 256         }
 257 #endif /* HAVE_PREAD */
 258
 259         if ((channel->align == 0) ||
 260             (IS_ALIGNED(buf, channel->align) &&
 261              IS_ALIGNED(location, channel->align) &&
 262              IS_ALIGNED(size, channel->align))) {
 263                 mutex_lock(data, BOUNCE_MTX);
 264                 if (ext2fs_llseek(data->dev, location, SEEK_SET) < 0) {
 265                         retval = errno ? errno : EXT2_ET_LLSEEK_FAILED;
 266                         goto error_unlock;
 267                 }
 268                 actual = read(data->dev, buf, size);
 269                 if (actual != size) {
 270                 short_read:
 271                         if (actual < 0) {
 272                                 retval = errno;
 273                                 actual = 0;
 274                         } else
 275                                 retval = EXT2_ET_SHORT_READ;
 276                         goto error_unlock;
 277                 }
 278                 goto success_unlock;
 279         }
 280
 281 #ifdef ALIGN_DEBUG
 282         printf("raw_read_blk: O_DIRECT fallback: %p %lu\n", buf,
 283                (unsigned long) size);
 284 #endif
 285
 286         /*
 287          * The buffer or size which we're trying to read isn't aligned
 288          * to the O_DIRECT rules, so we need to do this the hard way...
 289          */
 290 bounce_read:
 291         if (channel->align == 0)
 292                 channel->align = 1;
 293         if ((channel->block_size > channel->align) &&
 294             (channel->block_size % channel->align) == 0)
 295                 align_size = channel->block_size;
 296         else
 297                 align_size = channel->align;
 298         aligned_blk = location / align_size;
 299         offset = location % align_size;
 300
 301         mutex_lock(data, BOUNCE_MTX);
 302         if (ext2fs_llseek(data->dev, aligned_blk * align_size, SEEK_SET) < 0) {
 303                 retval = errno ? errno : EXT2_ET_LLSEEK_FAILED;
 304                 goto error_unlock;
 305         }
 306         while (size > 0) {
 307                 actual = read(data->dev, data->bounce, align_size);
 308                 if (actual != align_size) {
 309                         mutex_unlock(data, BOUNCE_MTX);
 310                         actual = really_read;
 311                         buf -= really_read;
 312                         size += really_read;
 313                         goto short_read;
 314                 }
 315                 if ((actual + offset) > align_size)
 316                         actual = align_size - offset;
 317                 if (actual > size)
 318                         actual = size;
 319                 memcpy(buf, (char *)data->bounce + offset, actual);
 320
 321                 really_read += actual;
 322                 size -= actual;
 323                 buf += actual;
 324                 offset = 0;
 325                 aligned_blk++;
 326         }
 327 success_unlock:
 328         mutex_unlock(data, BOUNCE_MTX);
 329         return 0;
 330
 331 error_unlock:
 332         mutex_unlock(data, BOUNCE_MTX);
 333         if (actual >= 0 && actual < size)
 334                 memset((char *) buf+actual, 0, size-actual);
 335         if (channel->read_error)
 336                 retval = (channel->read_error)(channel, block, count, buf,
 337                                                size, actual, retval);
 338         return retval;
 339 }
 340
 341 #define RAW_WRITE_NO_HANDLER    1
 342
 343 static errcode_t raw_write_blk(io_channel channel,
 344                                struct unix_private_data *data,
 345                                unsigned long long block,
 346                                int count, const void *bufv,
 347                                int flags)
 348 {
 349         ssize_t         size;
 350         ext2_loff_t     location;
 351         int             actual = 0;
 352         errcode_t       retval;
 353         const unsigned char *buf = bufv;
 354         unsigned long long aligned_blk;
 355         int             align_size, offset;
 356
 357         if (count == 1)
 358                 size = channel->block_size;
 359         else {
 360                 if (count < 0)
 361                         size = -count;
 362                 else
 363                         size = (ext2_loff_t) count * channel->block_size;
 364         }
 365         mutex_lock(data, STATS_MTX);
 366         data->io_stats.bytes_written += size;
 367         mutex_unlock(data, STATS_MTX);
 368
 369         location = ((ext2_loff_t) block * channel->block_size) + data->offset;
 370
 371         if (data->flags & IO_FLAG_FORCE_BOUNCE)
 372                 goto bounce_write;
 373
 374 #ifdef HAVE_PWRITE64
 375         /* Try an aligned pwrite */
 376         if ((channel->align == 0) ||
 377             (IS_ALIGNED(buf, channel->align) &&
 378              IS_ALIGNED(location, channel->align) &&
 379              IS_ALIGNED(size, channel->align))) {
 380                 actual = pwrite64(data->dev, buf, size, location);
 381                 if (actual == size)
 382                         return 0;
 383         }
 384 #elif HAVE_PWRITE
 385         /* Try an aligned pwrite */
 386         if ((sizeof(off_t) >= sizeof(ext2_loff_t)) &&
 387             ((channel->align == 0) ||
 388              (IS_ALIGNED(buf, channel->align) &&
 389               IS_ALIGNED(location, channel->align) &&
 390               IS_ALIGNED(size, channel->align)))) {
 391                 actual = pwrite(data->dev, buf, size, location);
 392                 if (actual == size)
 393                         return 0;
 394         }
 395 #endif /* HAVE_PWRITE */
 396
 397         if ((channel->align == 0) ||
 398             (IS_ALIGNED(buf, channel->align) &&
 399              IS_ALIGNED(location, channel->align) &&
 400              IS_ALIGNED(size, channel->align))) {
 401                 mutex_lock(data, BOUNCE_MTX);
 402                 if (ext2fs_llseek(data->dev, location, SEEK_SET) < 0) {
 403                         retval = errno ? errno : EXT2_ET_LLSEEK_FAILED;
 404                         goto error_unlock;
 405                 }
 406                 actual = write(data->dev, buf, size);
 407                 mutex_unlock(data, BOUNCE_MTX);
 408                 if (actual < 0) {
 409                         retval = errno;
 410                         goto error_out;
 411                 }
 412                 if (actual != size) {
 413                 short_write:
 414                         retval = EXT2_ET_SHORT_WRITE;
 415                         goto error_out;
 416                 }
 417                 return 0;
 418         }
 419
 420 #ifdef ALIGN_DEBUG
 421         printf("raw_write_blk: O_DIRECT fallback: %p %lu\n", buf,
 422                (unsigned long) size);
 423 #endif
 424         /*
 425          * The buffer or size which we're trying to write isn't aligned
 426          * to the O_DIRECT rules, so we need to do this the hard way...
 427          */
 428 bounce_write:
 429         if (channel->align == 0)
 430                 channel->align = 1;
 431         if ((channel->block_size > channel->align) &&
 432             (channel->block_size % channel->align) == 0)
 433                 align_size = channel->block_size;
 434         else
 435                 align_size = channel->align;
 436         aligned_blk = location / align_size;
 437         offset = location % align_size;
 438
 439         while (size > 0) {
 440                 int actual_w;
 441
 442                 mutex_lock(data, BOUNCE_MTX);
 443                 if (size < align_size || offset) {
 444                         if (ext2fs_llseek(data->dev, aligned_blk * align_size,
 445                                           SEEK_SET) < 0) {
 446                                 retval = errno ? errno : EXT2_ET_LLSEEK_FAILED;
 447                                 goto error_unlock;
 448                         }
 449                         actual = read(data->dev, data->bounce,
 450                                       align_size);
 451                         if (actual != align_size) {
 452                                 if (actual < 0) {
 453                                         retval = errno;
 454                                         goto error_unlock;
 455                                 }
 456                                 memset((char *) data->bounce + actual, 0,
 457                                        align_size - actual);
 458                         }
 459                 }
 460                 actual = size;
 461                 if ((actual + offset) > align_size)
 462                         actual = align_size - offset;
 463                 if (actual > size)
 464                         actual = size;
 465                 memcpy(((char *)data->bounce) + offset, buf, actual);
 466                 if (ext2fs_llseek(data->dev, aligned_blk * align_size, SEEK_SET) < 0) {
 467                         retval = errno ? errno : EXT2_ET_LLSEEK_FAILED;
 468                         goto error_unlock;
 469                 }
 470                 actual_w = write(data->dev, data->bounce, align_size);
 471                 mutex_unlock(data, BOUNCE_MTX);
 472                 if (actual_w < 0) {
 473                         retval = errno;
 474                         goto error_out;
 475                 }
 476                 if (actual_w != align_size)
 477                         goto short_write;
 478                 size -= actual;
 479                 buf += actual;
 480                 location += actual;
 481                 aligned_blk++;
 482                 offset = 0;
 483         }
 484         return 0;
 485
 486 error_unlock:
 487         mutex_unlock(data, BOUNCE_MTX);
 488 error_out:
 489         if (((flags & RAW_WRITE_NO_HANDLER) == 0) && channel->write_error)
 490                 retval = (channel->write_error)(channel, block, count, buf,
 491                                                 size, actual, retval);
 492         return retval;
 493 }
 494
 495
 496 /*
 497  * Here we implement the cache functions
 498  */
 499
 500 /* Allocate the cache buffers */
 501 static errcode_t alloc_cache(io_channel channel,
 502                              struct unix_private_data *data)
 503 {
 504         errcode_t               retval;
 505         struct unix_cache       *cache;
 506         int                     i;
 507
 508         data->access_time = 0;
 509         for (i=0, cache = data->cache; i < CACHE_SIZE; i++, cache++) {
 510                 cache->block = 0;
 511                 cache->access_time = 0;
 512                 cache->dirty = 0;
 513                 cache->in_use = 0;
 514                 if (cache->buf)
 515                         ext2fs_free_mem(&cache->buf);
 516                 retval = io_channel_alloc_buf(channel, 0, &cache->buf);
 517                 if (retval)
 518                         return retval;
 519         }
 520         if (channel->align || data->flags & IO_FLAG_FORCE_BOUNCE) {
 521                 if (data->bounce)
 522                         ext2fs_free_mem(&data->bounce);
 523                 retval = io_channel_alloc_buf(channel, 0, &data->bounce);
 524         }
 525         return retval;
 526 }
 527
 528 /* Free the cache buffers */
 529 static void free_cache(struct unix_private_data *data)
 530 {
 531         struct unix_cache       *cache;
 532         int                     i;
 533
 534         data->access_time = 0;
 535         for (i=0, cache = data->cache; i < CACHE_SIZE; i++, cache++) {
 536                 cache->block = 0;
 537                 cache->access_time = 0;
 538                 cache->dirty = 0;
 539                 cache->in_use = 0;
 540                 if (cache->buf)
 541                         ext2fs_free_mem(&cache->buf);
 542         }
 543         if (data->bounce)
 544                 ext2fs_free_mem(&data->bounce);
 545 }
 546
 547 #ifndef NO_IO_CACHE
 548 /*
 549  * Try to find a block in the cache.  If the block is not found, and
 550  * eldest is a non-zero pointer, then fill in eldest with the cache
 551  * entry to that should be reused.
 552  */
 553 static struct unix_cache *find_cached_block(struct unix_private_data *data,
 554                                             unsigned long long block,
 555                                             struct unix_cache **eldest)
 556 {
 557         struct unix_cache       *cache, *unused_cache, *oldest_cache;
 558         int                     i;
 559
 560         unused_cache = oldest_cache = 0;
 561         for (i=0, cache = data->cache; i < CACHE_SIZE; i++, cache++) {
 562                 if (!cache->in_use) {
 563                         if (!unused_cache)
 564                                 unused_cache = cache;
 565                         continue;
 566                 }
 567                 if (cache->block == block) {
 568                         cache->access_time = ++data->access_time;
 569                         return cache;
 570                 }
 571                 if (!oldest_cache ||
 572                     (cache->access_time < oldest_cache->access_time))
 573                         oldest_cache = cache;
 574         }
 575         if (eldest)
 576                 *eldest = (unused_cache) ? unused_cache : oldest_cache;
 577         return 0;
 578 }
 579
 580 /*
 581  * Reuse a particular cache entry for another block.
 582  */
 583 static errcode_t reuse_cache(io_channel channel,
 584                 struct unix_private_data *data, struct unix_cache *cache,
 585                 unsigned long long block)
 586 {
 587         if (cache->dirty && cache->in_use) {
 588                 errcode_t retval;
 589
 590                 retval = raw_write_blk(channel, data, cache->block, 1,
 591                                        cache->buf, RAW_WRITE_NO_HANDLER);
 592                 if (retval) {
 593                         cache->write_err = 1;
 594                         return retval;
 595                 }
 596         }
 597
 598         cache->in_use = 1;
 599         cache->dirty = 0;
 600         cache->write_err = 0;
 601         cache->block = block;
 602         cache->access_time = ++data->access_time;
 603         return 0;
 604 }
 605
 606 #define FLUSH_INVALIDATE        0x01
 607 #define FLUSH_NOLOCK            0x02
 608
 609 /*
 610  * Flush all of the blocks in the cache
 611  */
 612 static errcode_t flush_cached_blocks(io_channel channel,
 613                                      struct unix_private_data *data,
 614                                      int flags)
 615 {
 616         struct unix_cache       *cache;
 617         errcode_t               retval, retval2 = 0;
 618         int                     i;
 619         int                     errors_found = 0;
 620
 621         if ((flags & FLUSH_NOLOCK) == 0)
 622                 mutex_lock(data, CACHE_MTX);
 623         for (i=0, cache = data->cache; i < CACHE_SIZE; i++, cache++) {
 624                 if (!cache->in_use || !cache->dirty)
 625                         continue;
 626                 retval = raw_write_blk(channel, data,
 627                                        cache->block, 1, cache->buf,
 628                                        RAW_WRITE_NO_HANDLER);
 629                 if (retval) {
 630                         cache->write_err = 1;
 631                         errors_found = 1;
 632                         retval2 = retval;
 633                 } else {
 634                         cache->dirty = 0;
 635                         cache->write_err = 0;
 636                         if (flags & FLUSH_INVALIDATE)
 637                                 cache->in_use = 0;
 638                 }
 639         }
 640         if ((flags & FLUSH_NOLOCK) == 0)
 641                 mutex_unlock(data, CACHE_MTX);
 642 retry:
 643         while (errors_found) {
 644                 if ((flags & FLUSH_NOLOCK) == 0)
 645                         mutex_lock(data, CACHE_MTX);
 646                 errors_found = 0;
 647                 for (i=0, cache = data->cache; i < CACHE_SIZE; i++, cache++) {
 648                         if (!cache->in_use || !cache->write_err)
 649                                 continue;
 650                         errors_found = 1;
 651                         if (cache->write_err && channel->write_error) {
 652                                 char *err_buf = NULL;
 653                                 unsigned long long err_block = cache->block;
 654
 655                                 cache->dirty = 0;
 656                                 cache->in_use = 0;
 657                                 cache->write_err = 0;
 658                                 if (io_channel_alloc_buf(channel, 0,
 659                                                          &err_buf))
 660                                         err_buf = NULL;
 661                                 else
 662                                         memcpy(err_buf, cache->buf,
 663                                                channel->block_size);
 664                                 mutex_unlock(data, CACHE_MTX);
 665                                 (channel->write_error)(channel, err_block,
 666                                         1, err_buf, channel->block_size, -1,
 667                                         retval2);
 668                                 if (err_buf)
 669                                         ext2fs_free_mem(&err_buf);
 670                                 goto retry;
 671                         } else
 672                                 cache->write_err = 0;
 673                 }
 674                 if ((flags & FLUSH_NOLOCK) == 0)
 675                         mutex_unlock(data, CACHE_MTX);
 676         }
 677         return retval2;
 678 }
 679 #endif /* NO_IO_CACHE */
 680
 681 #ifdef __linux__
 682 #ifndef BLKDISCARDZEROES
 683 #define BLKDISCARDZEROES _IO(0x12,124)
 684 #endif
 685 #endif
 686
 687 int ext2fs_open_file(const char *pathname, int flags, mode_t mode)
 688 {
 689         if (mode)
 690 #if defined(HAVE_OPEN64) && !defined(__OSX_AVAILABLE_BUT_DEPRECATED)
 691                 return open64(pathname, flags, mode);
 692         else
 693                 return open64(pathname, flags);
 694 #else
 695                 return open(pathname, flags, mode);
 696         else
 697                 return open(pathname, flags);
 698 #endif
 699 }
 700
 701 int ext2fs_stat(const char *path, ext2fs_struct_stat *buf)
 702 {
 703 #if defined(HAVE_FSTAT64) && !defined(__OSX_AVAILABLE_BUT_DEPRECATED)
 704         return stat64(path, buf);
 705 #else
 706         return stat(path, buf);
 707 #endif
 708 }
 709
 710 int ext2fs_fstat(int fd, ext2fs_struct_stat *buf)
 711 {
 712 #if defined(HAVE_FSTAT64) && !defined(__OSX_AVAILABLE_BUT_DEPRECATED)
 713         return fstat64(fd, buf);
 714 #else
 715         return fstat(fd, buf);
 716 #endif
 717 }
 718
 719
 720 static errcode_t unix_open_channel(const char *name, int fd,
 721                                    int flags, io_channel *channel,
 722                                    io_manager io_mgr)
 723 {
 724         io_channel      io = NULL;
 725         struct unix_private_data *data = NULL;
 726         errcode_t       retval;
 727         ext2fs_struct_stat st;
 728 #ifdef __linux__
 729         struct          utsname ut;
 730 #endif
 731
 732         if (safe_getenv("UNIX_IO_FORCE_BOUNCE"))
 733                 flags |= IO_FLAG_FORCE_BOUNCE;
 734
 735 #ifdef __linux__
 736         /*
 737          * We need to make sure any previous errors in the block
 738          * device are thrown away, sigh.
 739          */
 740         (void) fsync(fd);
 741 #endif
 742
 743         retval = ext2fs_get_mem(sizeof(struct struct_io_channel), &io);
 744         if (retval)
 745                 goto cleanup;
 746         memset(io, 0, sizeof(struct struct_io_channel));
 747         io->magic = EXT2_ET_MAGIC_IO_CHANNEL;
 748         retval = ext2fs_get_mem(sizeof(struct unix_private_data), &data);
 749         if (retval)
 750                 goto cleanup;
 751
 752         io->manager = io_mgr;
 753         retval = ext2fs_get_mem(strlen(name)+1, &io->name);
 754         if (retval)
 755                 goto cleanup;
 756
 757         strcpy(io->name, name);
 758         io->private_data = data;
 759         io->block_size = 1024;
 760         io->read_error = 0;
 761         io->write_error = 0;
 762         io->refcount = 1;
 763         io->flags = 0;
 764
 765         memset(data, 0, sizeof(struct unix_private_data));
 766         data->magic = EXT2_ET_MAGIC_UNIX_IO_CHANNEL;
 767         data->io_stats.num_fields = 2;
 768         data->flags = flags;
 769         data->dev = fd;
 770
 771 #if defined(O_DIRECT)
 772         if (flags & IO_FLAG_DIRECT_IO)
 773                 io->align = ext2fs_get_dio_alignment(data->dev);
 774 #elif defined(F_NOCACHE)
 775         if (flags & IO_FLAG_DIRECT_IO)
 776                 io->align = 4096;
 777 #endif
 778
 779         /*
 780          * If the device is really a block device, then set the
 781          * appropriate flag, otherwise we can set DISCARD_ZEROES flag
 782          * because we are going to use punch hole instead of discard
 783          * and if it succeed, subsequent read from sparse area returns
 784          * zero.
 785          */
 786         if (ext2fs_fstat(data->dev, &st) == 0) {
 787                 if (ext2fsP_is_disk_device(st.st_mode))
 788                         io->flags |= CHANNEL_FLAGS_BLOCK_DEVICE;
 789                 else
 790                         io->flags |= CHANNEL_FLAGS_DISCARD_ZEROES;
 791         }
 792
 793 #ifdef BLKDISCARDZEROES
 794         {
 795                 int zeroes = 0;
 796                 if (ioctl(data->dev, BLKDISCARDZEROES, &zeroes) == 0 &&
 797                     zeroes)
 798                         io->flags |= CHANNEL_FLAGS_DISCARD_ZEROES;
 799         }
 800 #endif
 801
 802 #if defined(__CYGWIN__)
 803         /*
 804          * Some operating systems require that the buffers be aligned,
 805          * regardless of O_DIRECT
 806          */
 807         if (!io->align)
 808                 io->align = 512;
 809 #endif
 810
 811 #if defined(__FreeBSD__) || defined(__FreeBSD_kernel__)
 812         if (io->flags & CHANNEL_FLAGS_BLOCK_DEVICE) {
 813                 int dio_align = ext2fs_get_dio_alignment(fd);
 814
 815                 if (io->align < dio_align)
 816                         io->align = dio_align;
 817         }
 818 #endif
 819
 820         if ((retval = alloc_cache(io, data)))
 821                 goto cleanup;
 822
 823 #ifdef BLKROGET
 824         if (flags & IO_FLAG_RW) {
 825                 int error;
 826                 int readonly = 0;
 827
 828                 /* Is the block device actually writable? */
 829                 error = ioctl(data->dev, BLKROGET, &readonly);
 830                 if (!error && readonly) {
 831                         retval = EPERM;
 832                         goto cleanup;
 833                 }
 834         }
 835 #endif
 836
 837 #ifdef __linux__
 838 #undef RLIM_INFINITY
 839 #if (defined(__alpha__) || ((defined(__sparc__) || defined(__mips__)) && (SIZEOF_LONG == 4)))
 840 #define RLIM_INFINITY   ((unsigned long)(~0UL>>1))
 841 #else
 842 #define RLIM_INFINITY  (~0UL)
 843 #endif
 844         /*
 845          * Work around a bug in 2.4.10-2.4.18 kernels where writes to
 846          * block devices are wrongly getting hit by the filesize
 847          * limit.  This workaround isn't perfect, since it won't work
 848          * if glibc wasn't built against 2.2 header files.  (Sigh.)
 849          *
 850          */
 851         if ((flags & IO_FLAG_RW) &&
 852             (uname(&ut) == 0) &&
 853             ((ut.release[0] == '2') && (ut.release[1] == '.') &&
 854              (ut.release[2] == '4') && (ut.release[3] == '.') &&
 855              (ut.release[4] == '1') && (ut.release[5] >= '0') &&
 856              (ut.release[5] < '8')) &&
 857             (ext2fs_fstat(data->dev, &st) == 0) &&
 858             (ext2fsP_is_disk_device(st.st_mode))) {
 859                 struct rlimit   rlim;
 860
 861                 rlim.rlim_cur = rlim.rlim_max = (unsigned long) RLIM_INFINITY;
 862                 setrlimit(RLIMIT_FSIZE, &rlim);
 863                 getrlimit(RLIMIT_FSIZE, &rlim);
 864                 if (((unsigned long) rlim.rlim_cur) <
 865                     ((unsigned long) rlim.rlim_max)) {
 866                         rlim.rlim_cur = rlim.rlim_max;
 867                         setrlimit(RLIMIT_FSIZE, &rlim);
 868                 }
 869         }
 870 #endif
 871 #ifdef HAVE_PTHREAD
 872         if (flags & IO_FLAG_THREADS) {
 873                 io->flags |= CHANNEL_FLAGS_THREADS;
 874                 retval = pthread_mutex_init(&data->cache_mutex, NULL);
 875                 if (retval)
 876                         goto cleanup;
 877                 retval = pthread_mutex_init(&data->bounce_mutex, NULL);
 878                 if (retval) {
 879                         pthread_mutex_destroy(&data->cache_mutex);
 880                         goto cleanup;
 881                 }
 882                 retval = pthread_mutex_init(&data->stats_mutex, NULL);
 883                 if (retval) {
 884                         pthread_mutex_destroy(&data->cache_mutex);
 885                         pthread_mutex_destroy(&data->bounce_mutex);
 886                         goto cleanup;
 887                 }
 888         }
 889 #endif
 890         *channel = io;
 891         return 0;
 892
 893 cleanup:
 894         if (data) {
 895                 if (data->dev >= 0)
 896                         close(data->dev);
 897                 free_cache(data);
 898                 ext2fs_free_mem(&data);
 899         }
 900         if (io) {
 901                 if (io->name) {
 902                         ext2fs_free_mem(&io->name);
 903                 }
 904                 ext2fs_free_mem(&io);
 905         }
 906         return retval;
 907 }
 908
 909 static errcode_t unixfd_open(const char *str_fd, int flags,
 910                              io_channel *channel)
 911 {
 912         int fd;
 913         int fd_flags;
 914
 915         fd = atoi(str_fd);
 916 #if defined(HAVE_FCNTL)
 917         fd_flags = fcntl(fd, F_GETFD);
 918         if (fd_flags == -1)
 919                 return EBADF;
 920
 921         flags = 0;
 922         if (fd_flags & O_RDWR)
 923                 flags |= IO_FLAG_RW;
 924         if (fd_flags & O_EXCL)
 925                 flags |= IO_FLAG_EXCLUSIVE;
 926 #if defined(O_DIRECT)
 927         if (fd_flags & O_DIRECT)
 928                 flags |= IO_FLAG_DIRECT_IO;
 929 #endif
 930 #endif  /* HAVE_FCNTL */
 931
 932         return unix_open_channel(str_fd, fd, flags, channel, unixfd_io_manager);
 933 }
 934
 935 static errcode_t unix_open(const char *name, int flags,
 936                            io_channel *channel)
 937 {
 938         int fd = -1;
 939         int open_flags;
 940
 941         if (name == 0)
 942                 return EXT2_ET_BAD_DEVICE_NAME;
 943
 944         open_flags = (flags & IO_FLAG_RW) ? O_RDWR : O_RDONLY;
 945         if (flags & IO_FLAG_EXCLUSIVE)
 946                 open_flags |= O_EXCL;
 947 #if defined(O_DIRECT)
 948         if (flags & IO_FLAG_DIRECT_IO)
 949                 open_flags |= O_DIRECT;
 950 #endif
 951         fd = ext2fs_open_file(name, open_flags, 0);
 952         if (fd < 0)
 953                 return errno;
 954 #if defined(F_NOCACHE) && !defined(IO_DIRECT)
 955         if (flags & IO_FLAG_DIRECT_IO) {
 956                 if (fcntl(fd, F_NOCACHE, 1) < 0)
 957                         return errno;
 958         }
 959 #endif
 960         return unix_open_channel(name, fd, flags, channel, unix_io_manager);
 961 }
 962
 963 static errcode_t unix_close(io_channel channel)
 964 {
 965         struct unix_private_data *data;
 966         errcode_t       retval = 0;
 967
 968         EXT2_CHECK_MAGIC(channel, EXT2_ET_MAGIC_IO_CHANNEL);
 969         data = (struct unix_private_data *) channel->private_data;
 970         EXT2_CHECK_MAGIC(data, EXT2_ET_MAGIC_UNIX_IO_CHANNEL);
 971
 972         if (--channel->refcount > 0)
 973                 return 0;
 974
 975 #ifndef NO_IO_CACHE
 976         retval = flush_cached_blocks(channel, data, 0);
 977 #endif
 978
 979         if (close(data->dev) < 0)
 980                 retval = errno;
 981         free_cache(data);
 982 #ifdef HAVE_PTHREAD
 983         if (data->flags & IO_FLAG_THREADS) {
 984                 pthread_mutex_destroy(&data->cache_mutex);
 985                 pthread_mutex_destroy(&data->bounce_mutex);
 986                 pthread_mutex_destroy(&data->stats_mutex);
 987         }
 988 #endif
 989
 990         ext2fs_free_mem(&channel->private_data);
 991         if (channel->name)
 992                 ext2fs_free_mem(&channel->name);
 993         ext2fs_free_mem(&channel);
 994         return retval;
 995 }
 996
 997 static errcode_t unix_set_blksize(io_channel channel, int blksize)
 998 {
 999         struct unix_private_data *data;
1000         errcode_t               retval = 0;
1001
1002         EXT2_CHECK_MAGIC(channel, EXT2_ET_MAGIC_IO_CHANNEL);
1003         data = (struct unix_private_data *) channel->private_data;
1004         EXT2_CHECK_MAGIC(data, EXT2_ET_MAGIC_UNIX_IO_CHANNEL);
1005
1006         if (channel->block_size != blksize) {
1007                 mutex_lock(data, CACHE_MTX);
1008                 mutex_lock(data, BOUNCE_MTX);
1009 #ifndef NO_IO_CACHE
1010                 if ((retval = flush_cached_blocks(channel, data, FLUSH_NOLOCK))){
1011                         mutex_unlock(data, BOUNCE_MTX);
1012                         mutex_unlock(data, CACHE_MTX);
1013                         return retval;
1014                 }
1015 #endif
1016
1017                 channel->block_size = blksize;
1018                 free_cache(data);
1019                 retval = alloc_cache(channel, data);
1020                 mutex_unlock(data, BOUNCE_MTX);
1021                 mutex_unlock(data, CACHE_MTX);
1022         }
1023         return retval;
1024 }
1025
1026 static errcode_t unix_read_blk64(io_channel channel, unsigned long long block,
1027                                int count, void *buf)
1028 {
1029         struct unix_private_data *data;
1030         struct unix_cache *cache;
1031         errcode_t       retval;
1032         char            *cp;
1033         int             i, j;
1034
1035         EXT2_CHECK_MAGIC(channel, EXT2_ET_MAGIC_IO_CHANNEL);
1036         data = (struct unix_private_data *) channel->private_data;
1037         EXT2_CHECK_MAGIC(data, EXT2_ET_MAGIC_UNIX_IO_CHANNEL);
1038
1039 #ifdef NO_IO_CACHE
1040         return raw_read_blk(channel, data, block, count, buf);
1041 #else
1042         if (data->flags & IO_FLAG_NOCACHE)
1043                 return raw_read_blk(channel, data, block, count, buf);
1044         /*
1045          * If we're doing an odd-sized read or a very large read,
1046          * flush out the cache and then do a direct read.
1047          */
1048         if (count < 0 || count > WRITE_DIRECT_SIZE) {
1049                 if ((retval = flush_cached_blocks(channel, data, 0)))
1050                         return retval;
1051                 return raw_read_blk(channel, data, block, count, buf);
1052         }
1053
1054         cp = buf;
1055         mutex_lock(data, CACHE_MTX);
1056         while (count > 0) {
1057                 /* If it's in the cache, use it! */
1058                 if ((cache = find_cached_block(data, block, NULL))) {
1059 #ifdef DEBUG
1060                         printf("Using cached block %lu\n", block);
1061 #endif
1062                         memcpy(cp, cache->buf, channel->block_size);
1063                         count--;
1064                         block++;
1065                         cp += channel->block_size;
1066                         continue;
1067                 }
1068
1069                 /*
1070                  * Find the number of uncached blocks so we can do a
1071                  * single read request
1072                  */
1073                 for (i=1; i < count; i++)
1074                         if (find_cached_block(data, block+i, NULL))
1075                                 break;
1076 #ifdef DEBUG
1077                 printf("Reading %d blocks starting at %lu\n", i, block);
1078 #endif
1079                 mutex_unlock(data, CACHE_MTX);
1080                 if ((retval = raw_read_blk(channel, data, block, i, cp)))
1081                         return retval;
1082                 mutex_lock(data, CACHE_MTX);
1083
1084                 /* Save the results in the cache */
1085                 for (j=0; j < i; j++) {
1086                         if (!find_cached_block(data, block, &cache)) {
1087                                 retval = reuse_cache(channel, data,
1088                                                      cache, block);
1089                                 if (retval)
1090                                         goto call_write_handler;
1091                                 memcpy(cache->buf, cp, channel->block_size);
1092                         }
1093                         count--;
1094                         block++;
1095                         cp += channel->block_size;
1096                 }
1097         }
1098         mutex_unlock(data, CACHE_MTX);
1099         return 0;
1100
1101 call_write_handler:
1102         if (cache->write_err && channel->write_error) {
1103                 char *err_buf = NULL;
1104                 unsigned long long err_block = cache->block;
1105
1106                 cache->dirty = 0;
1107                 cache->in_use = 0;
1108                 cache->write_err = 0;
1109                 if (io_channel_alloc_buf(channel, 0, &err_buf))
1110                         err_buf = NULL;
1111                 else
1112                         memcpy(err_buf, cache->buf, channel->block_size);
1113                 mutex_unlock(data, CACHE_MTX);
1114                 (channel->write_error)(channel, err_block, 1, err_buf,
1115                                        channel->block_size, -1,
1116                                        retval);
1117                 if (err_buf)
1118                         ext2fs_free_mem(&err_buf);
1119         } else
1120                 mutex_unlock(data, CACHE_MTX);
1121         return retval;
1122 #endif /* NO_IO_CACHE */
1123 }
1124
1125 static errcode_t unix_read_blk(io_channel channel, unsigned long block,
1126                                int count, void *buf)
1127 {
1128         return unix_read_blk64(channel, block, count, buf);
1129 }
1130
1131 static errcode_t unix_write_blk64(io_channel channel, unsigned long long block,
1132                                 int count, const void *buf)
1133 {
1134         struct unix_private_data *data;
1135         struct unix_cache *cache, *reuse;
1136         errcode_t       retval = 0;
1137         const char      *cp;
1138         int             writethrough;
1139
1140         EXT2_CHECK_MAGIC(channel, EXT2_ET_MAGIC_IO_CHANNEL);
1141         data = (struct unix_private_data *) channel->private_data;
1142         EXT2_CHECK_MAGIC(data, EXT2_ET_MAGIC_UNIX_IO_CHANNEL);
1143
1144 #ifdef NO_IO_CACHE
1145         return raw_write_blk(channel, data, block, count, buf, 0);
1146 #else
1147         if (data->flags & IO_FLAG_NOCACHE)
1148                 return raw_write_blk(channel, data, block, count, buf, 0);
1149         /*
1150          * If we're doing an odd-sized write or a very large write,
1151          * flush out the cache completely and then do a direct write.
1152          */
1153         if (count < 0 || count > WRITE_DIRECT_SIZE) {
1154                 if ((retval = flush_cached_blocks(channel, data,
1155                                                   FLUSH_INVALIDATE)))
1156                         return retval;
1157                 return raw_write_blk(channel, data, block, count, buf, 0);
1158         }
1159
1160         /*
1161          * For a moderate-sized multi-block write, first force a write
1162          * if we're in write-through cache mode, and then fill the
1163          * cache with the blocks.
1164          */
1165         writethrough = channel->flags & CHANNEL_FLAGS_WRITETHROUGH;
1166         if (writethrough)
1167                 retval = raw_write_blk(channel, data, block, count, buf, 0);
1168
1169         cp = buf;
1170         mutex_lock(data, CACHE_MTX);
1171         while (count > 0) {
1172                 cache = find_cached_block(data, block, &reuse);
1173                 if (!cache) {
1174                         errcode_t err;
1175
1176                         cache = reuse;
1177                         err = reuse_cache(channel, data, cache, block);
1178                         if (err)
1179                                 goto call_write_handler;
1180                 }
1181                 if (cache->buf != cp)
1182                         memcpy(cache->buf, cp, channel->block_size);
1183                 cache->dirty = !writethrough;
1184                 count--;
1185                 block++;
1186                 cp += channel->block_size;
1187         }
1188         mutex_unlock(data, CACHE_MTX);
1189         return retval;
1190
1191 call_write_handler:
1192         if (cache->write_err && channel->write_error) {
1193                 char *err_buf = NULL;
1194                 unsigned long long err_block = cache->block;
1195
1196                 cache->dirty = 0;
1197                 cache->in_use = 0;
1198                 cache->write_err = 0;
1199                 if (io_channel_alloc_buf(channel, 0, &err_buf))
1200                         err_buf = NULL;
1201                 else
1202                         memcpy(err_buf, cache->buf, channel->block_size);
1203                 mutex_unlock(data, CACHE_MTX);
1204                 (channel->write_error)(channel, err_block, 1, err_buf,
1205                                        channel->block_size, -1,
1206                                        retval);
1207                 if (err_buf)
1208                         ext2fs_free_mem(&err_buf);
1209         } else
1210                 mutex_unlock(data, CACHE_MTX);
1211         return retval;
1212 #endif /* NO_IO_CACHE */
1213 }
1214
1215 static errcode_t unix_cache_readahead(io_channel channel,
1216                                       unsigned long long block,
1217                                       unsigned long long count)
1218 {
1219 #ifdef POSIX_FADV_WILLNEED
1220         struct unix_private_data *data;
1221
1222         data = (struct unix_private_data *)channel->private_data;
1223         EXT2_CHECK_MAGIC(data, EXT2_ET_MAGIC_UNIX_IO_CHANNEL);
1224         return posix_fadvise(data->dev,
1225                              (ext2_loff_t)block * channel->block_size + data->offset,
1226                              (ext2_loff_t)count * channel->block_size,
1227                              POSIX_FADV_WILLNEED);
1228 #else
1229         return EXT2_ET_OP_NOT_SUPPORTED;
1230 #endif
1231 }
1232
1233 static errcode_t unix_write_blk(io_channel channel, unsigned long block,
1234                                 int count, const void *buf)
1235 {
1236         return unix_write_blk64(channel, block, count, buf);
1237 }
1238
1239 static errcode_t unix_write_byte(io_channel channel, unsigned long offset,
1240                                  int size, const void *buf)
1241 {
1242         struct unix_private_data *data;
1243         errcode_t       retval = 0;
1244         ssize_t         actual;
1245
1246         EXT2_CHECK_MAGIC(channel, EXT2_ET_MAGIC_IO_CHANNEL);
1247         data = (struct unix_private_data *) channel->private_data;
1248         EXT2_CHECK_MAGIC(data, EXT2_ET_MAGIC_UNIX_IO_CHANNEL);
1249
1250         if (channel->align != 0) {
1251 #ifdef ALIGN_DEBUG
1252                 printf("unix_write_byte: O_DIRECT fallback\n");
1253 #endif
1254                 return EXT2_ET_UNIMPLEMENTED;
1255         }
1256
1257 #ifndef NO_IO_CACHE
1258         /*
1259          * Flush out the cache completely
1260          */
1261         if ((retval = flush_cached_blocks(channel, data, FLUSH_INVALIDATE)))
1262                 return retval;
1263 #endif
1264
1265         if (lseek(data->dev, offset + data->offset, SEEK_SET) < 0)
1266                 return errno;
1267
1268         actual = write(data->dev, buf, size);
1269         if (actual < 0)
1270                 return errno;
1271         if (actual != size)
1272                 return EXT2_ET_SHORT_WRITE;
1273
1274         return 0;
1275 }
1276
1277 /*
1278  * Flush data buffers to disk.
1279  */
1280 static errcode_t unix_flush(io_channel channel)
1281 {
1282         struct unix_private_data *data;
1283         errcode_t retval = 0;
1284
1285         EXT2_CHECK_MAGIC(channel, EXT2_ET_MAGIC_IO_CHANNEL);
1286         data = (struct unix_private_data *) channel->private_data;
1287         EXT2_CHECK_MAGIC(data, EXT2_ET_MAGIC_UNIX_IO_CHANNEL);
1288
1289 #ifndef NO_IO_CACHE
1290         retval = flush_cached_blocks(channel, data, 0);
1291 #endif
1292 #ifdef HAVE_FSYNC
1293         if (!retval && fsync(data->dev) != 0)
1294                 return errno;
1295 #endif
1296         return retval;
1297 }
1298
1299 static errcode_t unix_set_option(io_channel channel, const char *option,
1300                                  const char *arg)
1301 {
1302         struct unix_private_data *data;
1303         unsigned long long tmp;
1304         errcode_t retval;
1305         char *end;
1306
1307         EXT2_CHECK_MAGIC(channel, EXT2_ET_MAGIC_IO_CHANNEL);
1308         data = (struct unix_private_data *) channel->private_data;
1309         EXT2_CHECK_MAGIC(data, EXT2_ET_MAGIC_UNIX_IO_CHANNEL);
1310
1311         if (!strcmp(option, "offset")) {
1312                 if (!arg)
1313                         return EXT2_ET_INVALID_ARGUMENT;
1314
1315                 tmp = strtoull(arg, &end, 0);
1316                 if (*end)
1317                         return EXT2_ET_INVALID_ARGUMENT;
1318                 data->offset = tmp;
1319                 if (data->offset < 0)
1320                         return EXT2_ET_INVALID_ARGUMENT;
1321                 return 0;
1322         }
1323         if (!strcmp(option, "cache")) {
1324                 if (!arg)
1325                         return EXT2_ET_INVALID_ARGUMENT;
1326                 if (!strcmp(arg, "on")) {
1327                         data->flags &= ~IO_FLAG_NOCACHE;
1328                         return 0;
1329                 }
1330                 if (!strcmp(arg, "off")) {
1331                         retval = flush_cached_blocks(channel, data, 0);
1332                         data->flags |= IO_FLAG_NOCACHE;
1333                         return retval;
1334                 }
1335                 return EXT2_ET_INVALID_ARGUMENT;
1336         }
1337         return EXT2_ET_INVALID_ARGUMENT;
1338 }
1339
1340 #if defined(__linux__) && !defined(BLKDISCARD)
1341 #define BLKDISCARD              _IO(0x12,119)
1342 #endif
1343
1344 static errcode_t unix_discard(io_channel channel, unsigned long long block,
1345                               unsigned long long count)
1346 {
1347         struct unix_private_data *data;
1348         int             ret;
1349
1350         EXT2_CHECK_MAGIC(channel, EXT2_ET_MAGIC_IO_CHANNEL);
1351         data = (struct unix_private_data *) channel->private_data;
1352         EXT2_CHECK_MAGIC(data, EXT2_ET_MAGIC_UNIX_IO_CHANNEL);
1353
1354         if (channel->flags & CHANNEL_FLAGS_BLOCK_DEVICE) {
1355 #ifdef BLKDISCARD
1356                 __u64 range[2];
1357
1358                 range[0] = (__u64)(block) * channel->block_size + data->offset;
1359                 range[1] = (__u64)(count) * channel->block_size;
1360
1361                 ret = ioctl(data->dev, BLKDISCARD, &range);
1362 #else
1363                 goto unimplemented;
1364 #endif
1365         } else {
1366 #if defined(HAVE_FALLOCATE) && defined(FALLOC_FL_PUNCH_HOLE)
1367                 /*
1368                  * If we are not on block device, try to use punch hole
1369                  * to reclaim free space.
1370                  */
1371                 ret = fallocate(data->dev,
1372                                 FALLOC_FL_PUNCH_HOLE | FALLOC_FL_KEEP_SIZE,
1373                                 (off_t)(block) * channel->block_size + data->offset,
1374                                 (off_t)(count) * channel->block_size);
1375 #else
1376                 goto unimplemented;
1377 #endif
1378         }
1379         if (ret < 0) {
1380                 if (errno == EOPNOTSUPP)
1381                         goto unimplemented;
1382                 return errno;
1383         }
1384         return 0;
1385 unimplemented:
1386         return EXT2_ET_UNIMPLEMENTED;
1387 }
1388
1389 /*
1390  * If we know about ZERO_RANGE, try that before we try PUNCH_HOLE because
1391  * ZERO_RANGE doesn't unmap preallocated blocks.  We prefer fallocate because
1392  * it always invalidates page cache, and libext2fs requires that reads after
1393  * ZERO_RANGE return zeroes.
1394  */
1395 static int __unix_zeroout(int fd, off_t offset, off_t len)
1396 {
1397         int ret = -1;
1398
1399 #if defined(HAVE_FALLOCATE) && defined(FALLOC_FL_ZERO_RANGE)
1400         ret = fallocate(fd, FALLOC_FL_ZERO_RANGE, offset, len);
1401         if (ret == 0)
1402                 return 0;
1403 #endif
1404 #if defined(HAVE_FALLOCATE) && defined(FALLOC_FL_PUNCH_HOLE) && defined(FALLOC_FL_KEEP_SIZE)
1405         ret = fallocate(fd, FALLOC_FL_PUNCH_HOLE | FALLOC_FL_KEEP_SIZE,
1406                         offset,  len);
1407         if (ret == 0)
1408                 return 0;
1409 #endif
1410         errno = EOPNOTSUPP;
1411         return ret;
1412 }
1413
1414 /* parameters might not be used if OS doesn't support zeroout */
1415 #if __GNUC_PREREQ (4, 6)
1416 #pragma GCC diagnostic push
1417 #pragma GCC diagnostic ignored "-Wunused-parameter"
1418 #endif
1419 static errcode_t unix_zeroout(io_channel channel, unsigned long long block,
1420                               unsigned long long count)
1421 {
1422         struct unix_private_data *data;
1423         int             ret;
1424
1425         EXT2_CHECK_MAGIC(channel, EXT2_ET_MAGIC_IO_CHANNEL);
1426         data = (struct unix_private_data *) channel->private_data;
1427         EXT2_CHECK_MAGIC(data, EXT2_ET_MAGIC_UNIX_IO_CHANNEL);
1428
1429         if (safe_getenv("UNIX_IO_NOZEROOUT"))
1430                 goto unimplemented;
1431
1432         if (!(channel->flags & CHANNEL_FLAGS_BLOCK_DEVICE)) {
1433                 /* Regular file, try to use truncate/punch/zero. */
1434                 struct stat statbuf;
1435
1436                 if (count == 0)
1437                         return 0;
1438                 /*
1439                  * If we're trying to zero a range past the end of the file,
1440                  * extend the file size, then truncate everything.
1441                  */
1442                 ret = fstat(data->dev, &statbuf);
1443                 if (ret)
1444                         goto err;
1445                 if ((unsigned long long) statbuf.st_size <
1446                         (block + count) * channel->block_size + data->offset) {
1447                         ret = ftruncate(data->dev,
1448                                         (block + count) * channel->block_size + data->offset);
1449                         if (ret)
1450                                 goto err;
1451                 }
1452         }
1453
1454         ret = __unix_zeroout(data->dev,
1455                         (off_t)(block) * channel->block_size + data->offset,
1456                         (off_t)(count) * channel->block_size);
1457 err:
1458         if (ret < 0) {
1459                 if (errno == EOPNOTSUPP)
1460                         goto unimplemented;
1461                 return errno;
1462         }
1463         return 0;
1464 unimplemented:
1465         return EXT2_ET_UNIMPLEMENTED;
1466 }
1467 #if __GNUC_PREREQ (4, 6)
1468 #pragma GCC diagnostic pop
1469 #endif
1470
1471 static struct struct_io_manager struct_unix_manager = {
1472         .magic          = EXT2_ET_MAGIC_IO_MANAGER,
1473         .name           = "Unix I/O Manager",
1474         .open           = unix_open,
1475         .close          = unix_close,
1476         .set_blksize    = unix_set_blksize,
1477         .read_blk       = unix_read_blk,
1478         .write_blk      = unix_write_blk,
1479         .flush          = unix_flush,
1480         .write_byte     = unix_write_byte,
1481         .set_option     = unix_set_option,
1482         .get_stats      = unix_get_stats,
1483         .read_blk64     = unix_read_blk64,
1484         .write_blk64    = unix_write_blk64,
1485         .discard        = unix_discard,
1486         .cache_readahead        = unix_cache_readahead,
1487         .zeroout        = unix_zeroout,
1488 };
1489
1490 io_manager unix_io_manager = &struct_unix_manager;
1491
1492 static struct struct_io_manager struct_unixfd_manager = {
1493         .magic          = EXT2_ET_MAGIC_IO_MANAGER,
1494         .name           = "Unix fd I/O Manager",
1495         .open           = unixfd_open,
1496         .close          = unix_close,
1497         .set_blksize    = unix_set_blksize,
1498         .read_blk       = unix_read_blk,
1499         .write_blk      = unix_write_blk,
1500         .flush          = unix_flush,
1501         .write_byte     = unix_write_byte,
1502         .set_option     = unix_set_option,
1503         .get_stats      = unix_get_stats,
1504         .read_blk64     = unix_read_blk64,
1505         .write_blk64    = unix_write_blk64,
1506         .discard        = unix_discard,
1507         .cache_readahead        = unix_cache_readahead,
1508         .zeroout        = unix_zeroout,
1509 };
1510
1511 io_manager unixfd_io_manager = &struct_unixfd_manager;