lib/ext2fs/alloc.c

   1 /*
   2  * alloc.c --- allocate new inodes, blocks for ext2fs
   3  *
   4  * Copyright (C) 1993, 1994, 1995, 1996 Theodore Ts'o.
   5  *
   6  * %Begin-Header%
   7  * This file may be redistributed under the terms of the GNU Library
   8  * General Public License, version 2.
   9  * %End-Header%
  10  */
  11
  12 #include "config.h"
  13 #include <stdio.h>
  14 #if HAVE_UNISTD_H
  15 #include <unistd.h>
  16 #endif
  17 #include <time.h>
  18 #include <string.h>
  19 #if HAVE_SYS_STAT_H
  20 #include <sys/stat.h>
  21 #endif
  22 #if HAVE_SYS_TYPES_H
  23 #include <sys/types.h>
  24 #endif
  25
  26 #include "ext2_fs.h"
  27 #include "ext2fs.h"
  28
  29 #define min(a, b) ((a) < (b) ? (a) : (b))
  30
  31 #undef DEBUG
  32
  33 #ifdef DEBUG
  34 # define dbg_printf(f, a...)  do {printf(f, ## a); fflush(stdout); } while (0)
  35 #else
  36 # define dbg_printf(f, a...)
  37 #endif
  38
  39 /*
  40  * Clear the uninit block bitmap flag if necessary
  41  */
  42 static void clear_block_uninit(ext2_filsys fs, dgrp_t group)
  43 {
  44         if (!ext2fs_has_group_desc_csum(fs) ||
  45             !(ext2fs_bg_flags_test(fs, group, EXT2_BG_BLOCK_UNINIT)))
  46                 return;
  47
  48         /* uninit block bitmaps are now initialized in read_bitmaps() */
  49
  50         ext2fs_bg_flags_clear(fs, group, EXT2_BG_BLOCK_UNINIT);
  51         ext2fs_group_desc_csum_set(fs, group);
  52         ext2fs_mark_super_dirty(fs);
  53         ext2fs_mark_bb_dirty(fs);
  54 }
  55
  56 /*
  57  * Check for uninit inode bitmaps and deal with them appropriately
  58  */
  59 static void check_inode_uninit(ext2_filsys fs, ext2fs_inode_bitmap map,
  60                           dgrp_t group)
  61 {
  62         ext2_ino_t      i, ino;
  63
  64         if (!ext2fs_has_group_desc_csum(fs) ||
  65             !(ext2fs_bg_flags_test(fs, group, EXT2_BG_INODE_UNINIT)))
  66                 return;
  67
  68         ino = (group * fs->super->s_inodes_per_group) + 1;
  69         for (i=0; i < fs->super->s_inodes_per_group; i++, ino++)
  70                 ext2fs_fast_unmark_inode_bitmap2(map, ino);
  71
  72         ext2fs_bg_flags_clear(fs, group, EXT2_BG_INODE_UNINIT);
  73         /* Mimics what the kernel does */
  74         ext2fs_bg_flags_clear(fs, group, EXT2_BG_BLOCK_UNINIT);
  75         ext2fs_group_desc_csum_set(fs, group);
  76         ext2fs_mark_ib_dirty(fs);
  77         ext2fs_mark_super_dirty(fs);
  78 }
  79
  80 /*
  81  * Right now, just search forward from the parent directory's block
  82  * group to find the next free inode.
  83  *
  84  * Should have a special policy for directories.
  85  */
  86 errcode_t ext2fs_new_inode(ext2_filsys fs, ext2_ino_t dir,
  87                            int mode EXT2FS_ATTR((unused)),
  88                            ext2fs_inode_bitmap map, ext2_ino_t *ret)
  89 {
  90         ext2_ino_t      start_inode = 0;
  91         ext2_ino_t      i, ino_in_group, upto, first_zero;
  92         errcode_t       retval;
  93         dgrp_t          group;
  94
  95         EXT2_CHECK_MAGIC(fs, EXT2_ET_MAGIC_EXT2FS_FILSYS);
  96
  97         if (!map)
  98                 map = fs->inode_map;
  99         if (!map)
 100                 return EXT2_ET_NO_INODE_BITMAP;
 101
 102         if (dir > 0) {
 103                 group = (dir - 1) / EXT2_INODES_PER_GROUP(fs->super);
 104                 start_inode = (group * EXT2_INODES_PER_GROUP(fs->super)) + 1;
 105         }
 106         if (start_inode < EXT2_FIRST_INODE(fs->super))
 107                 start_inode = EXT2_FIRST_INODE(fs->super);
 108         if (start_inode > fs->super->s_inodes_count)
 109                 return EXT2_ET_INODE_ALLOC_FAIL;
 110         i = start_inode;
 111         do {
 112                 ino_in_group = (i - 1) % EXT2_INODES_PER_GROUP(fs->super);
 113                 group = (i - 1) / EXT2_INODES_PER_GROUP(fs->super);
 114
 115                 check_inode_uninit(fs, map, group);
 116                 upto = i + (EXT2_INODES_PER_GROUP(fs->super) - ino_in_group);
 117                 if (i < start_inode && upto >= start_inode)
 118                         upto = start_inode - 1;
 119                 if (upto > fs->super->s_inodes_count)
 120                         upto = fs->super->s_inodes_count;
 121
 122                 retval = ext2fs_find_first_zero_inode_bitmap2(map, i, upto,
 123                                                               &first_zero);
 124                 if (retval == 0) {
 125                         i = first_zero;
 126                         break;
 127                 }
 128                 if (retval != ENOENT)
 129                         return EXT2_ET_INODE_ALLOC_FAIL;
 130                 i = upto + 1;
 131                 if (i > fs->super->s_inodes_count)
 132                         i = EXT2_FIRST_INODE(fs->super);
 133         } while (i != start_inode);
 134
 135         if (ext2fs_test_inode_bitmap2(map, i))
 136                 return EXT2_ET_INODE_ALLOC_FAIL;
 137         *ret = i;
 138         return 0;
 139 }
 140
 141 /*
 142  * Stupid algorithm --- we now just search forward starting from the
 143  * goal.  Should put in a smarter one someday....
 144  */
 145 errcode_t ext2fs_new_block2(ext2_filsys fs, blk64_t goal,
 146                            ext2fs_block_bitmap map, blk64_t *ret)
 147 {
 148         errcode_t retval;
 149         blk64_t b = 0;
 150         errcode_t (*gab)(ext2_filsys fs, blk64_t goal, blk64_t *ret);
 151
 152         EXT2_CHECK_MAGIC(fs, EXT2_ET_MAGIC_EXT2FS_FILSYS);
 153
 154         if (!map && fs->get_alloc_block) {
 155                 /*
 156                  * In case there are clients out there whose get_alloc_block
 157                  * handlers call ext2fs_new_block2 with a NULL block map,
 158                  * temporarily swap out the function pointer so that we don't
 159                  * end up in an infinite loop.
 160                  */
 161                 gab = fs->get_alloc_block;
 162                 fs->get_alloc_block = NULL;
 163                 retval = gab(fs, goal, &b);
 164                 fs->get_alloc_block = gab;
 165                 goto allocated;
 166         }
 167         if (!map)
 168                 map = fs->block_map;
 169         if (!map)
 170                 return EXT2_ET_NO_BLOCK_BITMAP;
 171         if (!goal || (goal >= ext2fs_blocks_count(fs->super)))
 172                 goal = fs->super->s_first_data_block;
 173         goal &= ~EXT2FS_CLUSTER_MASK(fs);
 174
 175         retval = ext2fs_find_first_zero_block_bitmap2(map,
 176                         goal, ext2fs_blocks_count(fs->super) - 1, &b);
 177         if ((retval == ENOENT) && (goal != fs->super->s_first_data_block))
 178                 retval = ext2fs_find_first_zero_block_bitmap2(map,
 179                         fs->super->s_first_data_block, goal - 1, &b);
 180 allocated:
 181         if (retval == ENOENT)
 182                 return EXT2_ET_BLOCK_ALLOC_FAIL;
 183         if (retval)
 184                 return retval;
 185
 186         clear_block_uninit(fs, ext2fs_group_of_blk2(fs, b));
 187         *ret = b;
 188         return 0;
 189 }
 190
 191 errcode_t ext2fs_new_block(ext2_filsys fs, blk_t goal,
 192                            ext2fs_block_bitmap map, blk_t *ret)
 193 {
 194         errcode_t retval;
 195         blk64_t val;
 196         retval = ext2fs_new_block2(fs, goal, map, &val);
 197         if (!retval)
 198                 *ret = (blk_t) val;
 199         return retval;
 200 }
 201
 202 /*
 203  * This function zeros out the allocated block, and updates all of the
 204  * appropriate filesystem records.
 205  */
 206 errcode_t ext2fs_alloc_block2(ext2_filsys fs, blk64_t goal,
 207                              char *block_buf, blk64_t *ret)
 208 {
 209         errcode_t       retval;
 210         blk64_t         block;
 211
 212         if (fs->get_alloc_block) {
 213                 retval = (fs->get_alloc_block)(fs, goal, &block);
 214                 if (retval)
 215                         goto fail;
 216         } else {
 217                 if (!fs->block_map) {
 218                         retval = ext2fs_read_block_bitmap(fs);
 219                         if (retval)
 220                                 goto fail;
 221                 }
 222
 223                 retval = ext2fs_new_block2(fs, goal, 0, &block);
 224                 if (retval)
 225                         goto fail;
 226         }
 227
 228         if (block_buf) {
 229                 memset(block_buf, 0, fs->blocksize);
 230                 retval = io_channel_write_blk64(fs->io, block, 1, block_buf);
 231         } else
 232                 retval = ext2fs_zero_blocks2(fs, block, 1, NULL, NULL);
 233         if (retval)
 234                 goto fail;
 235
 236         ext2fs_block_alloc_stats2(fs, block, +1);
 237         *ret = block;
 238
 239 fail:
 240         return retval;
 241 }
 242
 243 errcode_t ext2fs_alloc_block(ext2_filsys fs, blk_t goal,
 244                              char *block_buf, blk_t *ret)
 245 {
 246         errcode_t retval;
 247         blk64_t val;
 248         retval = ext2fs_alloc_block2(fs, goal, block_buf, &val);
 249         if (!retval)
 250                 *ret = (blk_t) val;
 251         return retval;
 252 }
 253
 254 errcode_t ext2fs_get_free_blocks2(ext2_filsys fs, blk64_t start, blk64_t finish,
 255                                  int num, ext2fs_block_bitmap map, blk64_t *ret)
 256 {
 257         blk64_t b = start;
 258         int     c_ratio;
 259
 260         EXT2_CHECK_MAGIC(fs, EXT2_ET_MAGIC_EXT2FS_FILSYS);
 261
 262         if (!map)
 263                 map = fs->block_map;
 264         if (!map)
 265                 return EXT2_ET_NO_BLOCK_BITMAP;
 266         if (!b)
 267                 b = fs->super->s_first_data_block;
 268         if (!finish)
 269                 finish = start;
 270         if (!num)
 271                 num = 1;
 272         c_ratio = 1 << ext2fs_get_bitmap_granularity(map);
 273         b &= ~(c_ratio - 1);
 274         finish &= ~(c_ratio -1);
 275         do {
 276                 if (b + num - 1 >= ext2fs_blocks_count(fs->super)) {
 277                         if (finish > start)
 278                                 return EXT2_ET_BLOCK_ALLOC_FAIL;
 279                         b = fs->super->s_first_data_block;
 280                 }
 281                 if (ext2fs_fast_test_block_bitmap_range2(map, b, num)) {
 282                         *ret = b;
 283                         return 0;
 284                 }
 285                 b += c_ratio;
 286         } while (b != finish);
 287         return EXT2_ET_BLOCK_ALLOC_FAIL;
 288 }
 289
 290 errcode_t ext2fs_get_free_blocks(ext2_filsys fs, blk_t start, blk_t finish,
 291                                  int num, ext2fs_block_bitmap map, blk_t *ret)
 292 {
 293         errcode_t retval;
 294         blk64_t val;
 295         retval = ext2fs_get_free_blocks2(fs, start, finish, num, map, &val);
 296         if(!retval)
 297                 *ret = (blk_t) val;
 298         return retval;
 299 }
 300
 301 void ext2fs_set_alloc_block_callback(ext2_filsys fs,
 302                                      errcode_t (*func)(ext2_filsys fs,
 303                                                        blk64_t goal,
 304                                                        blk64_t *ret),
 305                                      errcode_t (**old)(ext2_filsys fs,
 306                                                        blk64_t goal,
 307                                                        blk64_t *ret))
 308 {
 309         if (!fs || fs->magic != EXT2_ET_MAGIC_EXT2FS_FILSYS)
 310                 return;
 311
 312         if (old)
 313                 *old = fs->get_alloc_block;
 314
 315         fs->get_alloc_block = func;
 316 }
 317
 318 blk64_t ext2fs_find_inode_goal(ext2_filsys fs, ext2_ino_t ino,
 319                                struct ext2_inode *inode, blk64_t lblk)
 320 {
 321         dgrp_t                  group;
 322         __u8                    log_flex;
 323         struct ext2fs_extent    extent;
 324         ext2_extent_handle_t    handle = NULL;
 325         errcode_t               err;
 326
 327         if (inode == NULL || ext2fs_inode_data_blocks2(fs, inode) == 0)
 328                 goto no_blocks;
 329
 330         if (inode->i_flags & EXT4_INLINE_DATA_FL)
 331                 goto no_blocks;
 332
 333         if (inode->i_flags & EXT4_EXTENTS_FL) {
 334                 err = ext2fs_extent_open2(fs, ino, inode, &handle);
 335                 if (err)
 336                         goto no_blocks;
 337                 err = ext2fs_extent_goto2(handle, 0, lblk);
 338                 if (err)
 339                         goto no_blocks;
 340                 err = ext2fs_extent_get(handle, EXT2_EXTENT_CURRENT, &extent);
 341                 if (err)
 342                         goto no_blocks;
 343                 ext2fs_extent_free(handle);
 344                 return extent.e_pblk + (lblk - extent.e_lblk);
 345         }
 346
 347         /* block mapped file; see if block zero is mapped? */
 348         if (inode->i_block[0])
 349                 return inode->i_block[0];
 350
 351 no_blocks:
 352         ext2fs_extent_free(handle);
 353         log_flex = fs->super->s_log_groups_per_flex;
 354         group = ext2fs_group_of_ino(fs, ino);
 355         if (log_flex)
 356                 group = group & ~((1 << (log_flex)) - 1);
 357         return ext2fs_group_first_block2(fs, group);
 358 }
 359
 360 /*
 361  * Starting at _goal_, scan around the filesystem to find a run of free blocks
 362  * that's at least _len_ blocks long.  Possible flags:
 363  * - EXT2_NEWRANGE_EXACT_GOAL: The range of blocks must start at _goal_.
 364  * - EXT2_NEWRANGE_MIN_LENGTH: do not return a allocation shorter than _len_.
 365  * - EXT2_NEWRANGE_ZERO_BLOCKS: Zero blocks pblk to pblk+plen before returning.
 366  *
 367  * The starting block is returned in _pblk_ and the length is returned via
 368  * _plen_.  The blocks are not marked in the bitmap; the caller must mark
 369  * however much of the returned run they actually use, hopefully via
 370  * ext2fs_block_alloc_stats_range().
 371  *
 372  * This function can return a range that is longer than what was requested.
 373  */
 374 errcode_t ext2fs_new_range(ext2_filsys fs, int flags, blk64_t goal,
 375                            blk64_t len, ext2fs_block_bitmap map, blk64_t *pblk,
 376                            blk64_t *plen)
 377 {
 378         errcode_t retval;
 379         blk64_t start, end, b;
 380         int looped = 0;
 381         blk64_t max_blocks = ext2fs_blocks_count(fs->super);
 382
 383         dbg_printf("%s: flags=0x%x goal=%llu len=%llu\n", __func__, flags,
 384                    goal, len);
 385         EXT2_CHECK_MAGIC(fs, EXT2_ET_MAGIC_EXT2FS_FILSYS);
 386         if (len == 0 || (flags & ~EXT2_NEWRANGE_ALL_FLAGS))
 387                 return EXT2_ET_INVALID_ARGUMENT;
 388         if (!map)
 389                 map = fs->block_map;
 390         if (!map)
 391                 return EXT2_ET_NO_BLOCK_BITMAP;
 392         if (!goal || goal >= ext2fs_blocks_count(fs->super))
 393                 goal = fs->super->s_first_data_block;
 394
 395         start = goal;
 396         while (!looped || start <= goal) {
 397                 retval = ext2fs_find_first_zero_block_bitmap2(map, start,
 398                                                               max_blocks - 1,
 399                                                               &start);
 400                 if (retval == ENOENT) {
 401                         /*
 402                          * If there are no free blocks beyond the starting
 403                          * point, try scanning the whole filesystem, unless the
 404                          * user told us only to allocate from _goal_, or if
 405                          * we're already scanning the whole filesystem.
 406                          */
 407                         if (flags & EXT2_NEWRANGE_FIXED_GOAL ||
 408                             start == fs->super->s_first_data_block)
 409                                 goto fail;
 410                         start = fs->super->s_first_data_block;
 411                         continue;
 412                 } else if (retval)
 413                         goto errout;
 414
 415                 if (flags & EXT2_NEWRANGE_FIXED_GOAL && start != goal)
 416                         goto fail;
 417
 418                 b = min(start + len - 1, max_blocks - 1);
 419                 retval =  ext2fs_find_first_set_block_bitmap2(map, start, b,
 420                                                               &end);
 421                 if (retval == ENOENT)
 422                         end = b + 1;
 423                 else if (retval)
 424                         goto errout;
 425
 426                 if (!(flags & EXT2_NEWRANGE_MIN_LENGTH) ||
 427                     (end - start) >= len) {
 428                         /* Success! */
 429                         *pblk = start;
 430                         *plen = end - start;
 431                         dbg_printf("%s: new_range goal=%llu--%llu "
 432                                    "blk=%llu--%llu %llu\n",
 433                                    __func__, goal, goal + len - 1,
 434                                    *pblk, *pblk + *plen - 1, *plen);
 435
 436                         for (b = start; b < end;
 437                              b += fs->super->s_blocks_per_group)
 438                                 clear_block_uninit(fs,
 439                                                 ext2fs_group_of_blk2(fs, b));
 440                         return 0;
 441                 }
 442
 443                 if (flags & EXT2_NEWRANGE_FIXED_GOAL)
 444                         goto fail;
 445                 start = end;
 446                 if (start >= max_blocks) {
 447                         if (looped)
 448                                 goto fail;
 449                         looped = 1;
 450                         start = fs->super->s_first_data_block;
 451                 }
 452         }
 453
 454 fail:
 455         retval = EXT2_ET_BLOCK_ALLOC_FAIL;
 456 errout:
 457         return retval;
 458 }
 459
 460 errcode_t ext2fs_alloc_range(ext2_filsys fs, int flags, blk64_t goal,
 461                              blk_t len, blk64_t *ret)
 462 {
 463         int newr_flags = EXT2_NEWRANGE_MIN_LENGTH;
 464         errcode_t retval;
 465         blk64_t plen;
 466
 467         EXT2_CHECK_MAGIC(fs, EXT2_ET_MAGIC_EXT2FS_FILSYS);
 468         if (len == 0 || (flags & ~EXT2_ALLOCRANGE_ALL_FLAGS))
 469                 return EXT2_ET_INVALID_ARGUMENT;
 470
 471         if (flags & EXT2_ALLOCRANGE_FIXED_GOAL)
 472                 newr_flags |= EXT2_NEWRANGE_FIXED_GOAL;
 473
 474         retval = ext2fs_new_range(fs, newr_flags, goal, len, NULL, ret, &plen);
 475         if (retval)
 476                 return retval;
 477
 478         if (plen < len)
 479                 return EXT2_ET_BLOCK_ALLOC_FAIL;
 480
 481         if (flags & EXT2_ALLOCRANGE_ZERO_BLOCKS) {
 482                 retval = ext2fs_zero_blocks2(fs, *ret, len, NULL, NULL);
 483                 if (retval)
 484                         return retval;
 485         }
 486
 487         ext2fs_block_alloc_stats_range(fs, *ret, len, +1);
 488         return retval;
 489 }