fs/affs/file.c

   1 /*
   2  *  linux/fs/affs/file.c
   3  *
   4  *  (c) 1996  Hans-Joachim Widmaier - Rewritten
   5  *
   6  *  (C) 1993  Ray Burr - Modified for Amiga FFS filesystem.
   7  *
   8  *  (C) 1992  Eric Youngdale Modified for ISO 9660 filesystem.
   9  *
  10  *  (C) 1991  Linus Torvalds - minix filesystem
  11  *
  12  *  affs regular file handling primitives
  13  */
  14
  15 #include "affs.h"
  16
  17 #if PAGE_SIZE < 4096
  18 #error PAGE_SIZE must be at least 4096
  19 #endif
  20
  21 static int affs_grow_extcache(struct inode *inode, u32 lc_idx);
  22 static struct buffer_head *affs_alloc_extblock(struct inode *inode, struct buffer_head *bh, u32 ext);
  23 static inline struct buffer_head *affs_get_extblock(struct inode *inode, u32 ext);
  24 static struct buffer_head *affs_get_extblock_slow(struct inode *inode, u32 ext);
  25 static int affs_file_open(struct inode *inode, struct file *filp);
  26 static int affs_file_release(struct inode *inode, struct file *filp);
  27
  28 const struct file_operations affs_file_operations = {
  29         .llseek         = generic_file_llseek,
  30         .read           = generic_file_read,
  31         .write          = generic_file_write,
  32         .mmap           = generic_file_mmap,
  33         .open           = affs_file_open,
  34         .release        = affs_file_release,
  35         .fsync          = file_fsync,
  36         .sendfile       = generic_file_sendfile,
  37 };
  38
  39 struct inode_operations affs_file_inode_operations = {
  40         .truncate       = affs_truncate,
  41         .setattr        = affs_notify_change,
  42 };
  43
  44 static int
  45 affs_file_open(struct inode *inode, struct file *filp)
  46 {
  47         if (atomic_read(&filp->f_count) != 1)
  48                 return 0;
  49         pr_debug("AFFS: open(%d)\n", AFFS_I(inode)->i_opencnt);
  50         AFFS_I(inode)->i_opencnt++;
  51         return 0;
  52 }
  53
  54 static int
  55 affs_file_release(struct inode *inode, struct file *filp)
  56 {
  57         if (atomic_read(&filp->f_count) != 0)
  58                 return 0;
  59         pr_debug("AFFS: release(%d)\n", AFFS_I(inode)->i_opencnt);
  60         AFFS_I(inode)->i_opencnt--;
  61         if (!AFFS_I(inode)->i_opencnt)
  62                 affs_free_prealloc(inode);
  63
  64         return 0;
  65 }
  66
  67 static int
  68 affs_grow_extcache(struct inode *inode, u32 lc_idx)
  69 {
  70         struct super_block      *sb = inode->i_sb;
  71         struct buffer_head      *bh;
  72         u32 lc_max;
  73         int i, j, key;
  74
  75         if (!AFFS_I(inode)->i_lc) {
  76                 char *ptr = (char *)get_zeroed_page(GFP_NOFS);
  77                 if (!ptr)
  78                         return -ENOMEM;
  79                 AFFS_I(inode)->i_lc = (u32 *)ptr;
  80                 AFFS_I(inode)->i_ac = (struct affs_ext_key *)(ptr + AFFS_CACHE_SIZE / 2);
  81         }
  82
  83         lc_max = AFFS_LC_SIZE << AFFS_I(inode)->i_lc_shift;
  84
  85         if (AFFS_I(inode)->i_extcnt > lc_max) {
  86                 u32 lc_shift, lc_mask, tmp, off;
  87
  88                 /* need to recalculate linear cache, start from old size */
  89                 lc_shift = AFFS_I(inode)->i_lc_shift;
  90                 tmp = (AFFS_I(inode)->i_extcnt / AFFS_LC_SIZE) >> lc_shift;
  91                 for (; tmp; tmp >>= 1)
  92                         lc_shift++;
  93                 lc_mask = (1 << lc_shift) - 1;
  94
  95                 /* fix idx and old size to new shift */
  96                 lc_idx >>= (lc_shift - AFFS_I(inode)->i_lc_shift);
  97                 AFFS_I(inode)->i_lc_size >>= (lc_shift - AFFS_I(inode)->i_lc_shift);
  98
  99                 /* first shrink old cache to make more space */
 100                 off = 1 << (lc_shift - AFFS_I(inode)->i_lc_shift);
 101                 for (i = 1, j = off; j < AFFS_LC_SIZE; i++, j += off)
 102                         AFFS_I(inode)->i_ac[i] = AFFS_I(inode)->i_ac[j];
 103
 104                 AFFS_I(inode)->i_lc_shift = lc_shift;
 105                 AFFS_I(inode)->i_lc_mask = lc_mask;
 106         }
 107
 108         /* fill cache to the needed index */
 109         i = AFFS_I(inode)->i_lc_size;
 110         AFFS_I(inode)->i_lc_size = lc_idx + 1;
 111         for (; i <= lc_idx; i++) {
 112                 if (!i) {
 113                         AFFS_I(inode)->i_lc[0] = inode->i_ino;
 114                         continue;
 115                 }
 116                 key = AFFS_I(inode)->i_lc[i - 1];
 117                 j = AFFS_I(inode)->i_lc_mask + 1;
 118                 // unlock cache
 119                 for (; j > 0; j--) {
 120                         bh = affs_bread(sb, key);
 121                         if (!bh)
 122                                 goto err;
 123                         key = be32_to_cpu(AFFS_TAIL(sb, bh)->extension);
 124                         affs_brelse(bh);
 125                 }
 126                 // lock cache
 127                 AFFS_I(inode)->i_lc[i] = key;
 128         }
 129
 130         return 0;
 131
 132 err:
 133         // lock cache
 134         return -EIO;
 135 }
 136
 137 static struct buffer_head *
 138 affs_alloc_extblock(struct inode *inode, struct buffer_head *bh, u32 ext)
 139 {
 140         struct super_block *sb = inode->i_sb;
 141         struct buffer_head *new_bh;
 142         u32 blocknr, tmp;
 143
 144         blocknr = affs_alloc_block(inode, bh->b_blocknr);
 145         if (!blocknr)
 146                 return ERR_PTR(-ENOSPC);
 147
 148         new_bh = affs_getzeroblk(sb, blocknr);
 149         if (!new_bh) {
 150                 affs_free_block(sb, blocknr);
 151                 return ERR_PTR(-EIO);
 152         }
 153
 154         AFFS_HEAD(new_bh)->ptype = cpu_to_be32(T_LIST);
 155         AFFS_HEAD(new_bh)->key = cpu_to_be32(blocknr);
 156         AFFS_TAIL(sb, new_bh)->stype = cpu_to_be32(ST_FILE);
 157         AFFS_TAIL(sb, new_bh)->parent = cpu_to_be32(inode->i_ino);
 158         affs_fix_checksum(sb, new_bh);
 159
 160         mark_buffer_dirty_inode(new_bh, inode);
 161
 162         tmp = be32_to_cpu(AFFS_TAIL(sb, bh)->extension);
 163         if (tmp)
 164                 affs_warning(sb, "alloc_ext", "previous extension set (%x)", tmp);
 165         AFFS_TAIL(sb, bh)->extension = cpu_to_be32(blocknr);
 166         affs_adjust_checksum(bh, blocknr - tmp);
 167         mark_buffer_dirty_inode(bh, inode);
 168
 169         AFFS_I(inode)->i_extcnt++;
 170         mark_inode_dirty(inode);
 171
 172         return new_bh;
 173 }
 174
 175 static inline struct buffer_head *
 176 affs_get_extblock(struct inode *inode, u32 ext)
 177 {
 178         /* inline the simplest case: same extended block as last time */
 179         struct buffer_head *bh = AFFS_I(inode)->i_ext_bh;
 180         if (ext == AFFS_I(inode)->i_ext_last)
 181                 atomic_inc(&bh->b_count);
 182         else
 183                 /* we have to do more (not inlined) */
 184                 bh = affs_get_extblock_slow(inode, ext);
 185
 186         return bh;
 187 }
 188
 189 static struct buffer_head *
 190 affs_get_extblock_slow(struct inode *inode, u32 ext)
 191 {
 192         struct super_block *sb = inode->i_sb;
 193         struct buffer_head *bh;
 194         u32 ext_key;
 195         u32 lc_idx, lc_off, ac_idx;
 196         u32 tmp, idx;
 197
 198         if (ext == AFFS_I(inode)->i_ext_last + 1) {
 199                 /* read the next extended block from the current one */
 200                 bh = AFFS_I(inode)->i_ext_bh;
 201                 ext_key = be32_to_cpu(AFFS_TAIL(sb, bh)->extension);
 202                 if (ext < AFFS_I(inode)->i_extcnt)
 203                         goto read_ext;
 204                 if (ext > AFFS_I(inode)->i_extcnt)
 205                         BUG();
 206                 bh = affs_alloc_extblock(inode, bh, ext);
 207                 if (IS_ERR(bh))
 208                         return bh;
 209                 goto store_ext;
 210         }
 211
 212         if (ext == 0) {
 213                 /* we seek back to the file header block */
 214                 ext_key = inode->i_ino;
 215                 goto read_ext;
 216         }
 217
 218         if (ext >= AFFS_I(inode)->i_extcnt) {
 219                 struct buffer_head *prev_bh;
 220
 221                 /* allocate a new extended block */
 222                 if (ext > AFFS_I(inode)->i_extcnt)
 223                         BUG();
 224
 225                 /* get previous extended block */
 226                 prev_bh = affs_get_extblock(inode, ext - 1);
 227                 if (IS_ERR(prev_bh))
 228                         return prev_bh;
 229                 bh = affs_alloc_extblock(inode, prev_bh, ext);
 230                 affs_brelse(prev_bh);
 231                 if (IS_ERR(bh))
 232                         return bh;
 233                 goto store_ext;
 234         }
 235
 236 again:
 237         /* check if there is an extended cache and whether it's large enough */
 238         lc_idx = ext >> AFFS_I(inode)->i_lc_shift;
 239         lc_off = ext & AFFS_I(inode)->i_lc_mask;
 240
 241         if (lc_idx >= AFFS_I(inode)->i_lc_size) {
 242                 int err;
 243
 244                 err = affs_grow_extcache(inode, lc_idx);
 245                 if (err)
 246                         return ERR_PTR(err);
 247                 goto again;
 248         }
 249
 250         /* every n'th key we find in the linear cache */
 251         if (!lc_off) {
 252                 ext_key = AFFS_I(inode)->i_lc[lc_idx];
 253                 goto read_ext;
 254         }
 255
 256         /* maybe it's still in the associative cache */
 257         ac_idx = (ext - lc_idx - 1) & AFFS_AC_MASK;
 258         if (AFFS_I(inode)->i_ac[ac_idx].ext == ext) {
 259                 ext_key = AFFS_I(inode)->i_ac[ac_idx].key;
 260                 goto read_ext;
 261         }
 262
 263         /* try to find one of the previous extended blocks */
 264         tmp = ext;
 265         idx = ac_idx;
 266         while (--tmp, --lc_off > 0) {
 267                 idx = (idx - 1) & AFFS_AC_MASK;
 268                 if (AFFS_I(inode)->i_ac[idx].ext == tmp) {
 269                         ext_key = AFFS_I(inode)->i_ac[idx].key;
 270                         goto find_ext;
 271                 }
 272         }
 273
 274         /* fall back to the linear cache */
 275         ext_key = AFFS_I(inode)->i_lc[lc_idx];
 276 find_ext:
 277         /* read all extended blocks until we find the one we need */
 278         //unlock cache
 279         do {
 280                 bh = affs_bread(sb, ext_key);
 281                 if (!bh)
 282                         goto err_bread;
 283                 ext_key = be32_to_cpu(AFFS_TAIL(sb, bh)->extension);
 284                 affs_brelse(bh);
 285                 tmp++;
 286         } while (tmp < ext);
 287         //lock cache
 288
 289         /* store it in the associative cache */
 290         // recalculate ac_idx?
 291         AFFS_I(inode)->i_ac[ac_idx].ext = ext;
 292         AFFS_I(inode)->i_ac[ac_idx].key = ext_key;
 293
 294 read_ext:
 295         /* finally read the right extended block */
 296         //unlock cache
 297         bh = affs_bread(sb, ext_key);
 298         if (!bh)
 299                 goto err_bread;
 300         //lock cache
 301
 302 store_ext:
 303         /* release old cached extended block and store the new one */
 304         affs_brelse(AFFS_I(inode)->i_ext_bh);
 305         AFFS_I(inode)->i_ext_last = ext;
 306         AFFS_I(inode)->i_ext_bh = bh;
 307         atomic_inc(&bh->b_count);
 308
 309         return bh;
 310
 311 err_bread:
 312         affs_brelse(bh);
 313         return ERR_PTR(-EIO);
 314 }
 315
 316 static int
 317 affs_get_block(struct inode *inode, sector_t block, struct buffer_head *bh_result, int create)
 318 {
 319         struct super_block      *sb = inode->i_sb;
 320         struct buffer_head      *ext_bh;
 321         u32                      ext;
 322
 323         pr_debug("AFFS: get_block(%u, %lu)\n", (u32)inode->i_ino, (unsigned long)block);
 324
 325
 326         if (block > (sector_t)0x7fffffffUL)
 327                 BUG();
 328
 329         if (block >= AFFS_I(inode)->i_blkcnt) {
 330                 if (block > AFFS_I(inode)->i_blkcnt || !create)
 331                         goto err_big;
 332         } else
 333                 create = 0;
 334
 335         //lock cache
 336         affs_lock_ext(inode);
 337
 338         ext = (u32)block / AFFS_SB(sb)->s_hashsize;
 339         block -= ext * AFFS_SB(sb)->s_hashsize;
 340         ext_bh = affs_get_extblock(inode, ext);
 341         if (IS_ERR(ext_bh))
 342                 goto err_ext;
 343         map_bh(bh_result, sb, (sector_t)be32_to_cpu(AFFS_BLOCK(sb, ext_bh, block)));
 344
 345         if (create) {
 346                 u32 blocknr = affs_alloc_block(inode, ext_bh->b_blocknr);
 347                 if (!blocknr)
 348                         goto err_alloc;
 349                 set_buffer_new(bh_result);
 350                 AFFS_I(inode)->mmu_private += AFFS_SB(sb)->s_data_blksize;
 351                 AFFS_I(inode)->i_blkcnt++;
 352
 353                 /* store new block */
 354                 if (bh_result->b_blocknr)
 355                         affs_warning(sb, "get_block", "block already set (%x)", bh_result->b_blocknr);
 356                 AFFS_BLOCK(sb, ext_bh, block) = cpu_to_be32(blocknr);
 357                 AFFS_HEAD(ext_bh)->block_count = cpu_to_be32(block + 1);
 358                 affs_adjust_checksum(ext_bh, blocknr - bh_result->b_blocknr + 1);
 359                 bh_result->b_blocknr = blocknr;
 360
 361                 if (!block) {
 362                         /* insert first block into header block */
 363                         u32 tmp = be32_to_cpu(AFFS_HEAD(ext_bh)->first_data);
 364                         if (tmp)
 365                                 affs_warning(sb, "get_block", "first block already set (%d)", tmp);
 366                         AFFS_HEAD(ext_bh)->first_data = cpu_to_be32(blocknr);
 367                         affs_adjust_checksum(ext_bh, blocknr - tmp);
 368                 }
 369         }
 370
 371         affs_brelse(ext_bh);
 372         //unlock cache
 373         affs_unlock_ext(inode);
 374         return 0;
 375
 376 err_big:
 377         affs_error(inode->i_sb,"get_block","strange block request %d", block);
 378         return -EIO;
 379 err_ext:
 380         // unlock cache
 381         affs_unlock_ext(inode);
 382         return PTR_ERR(ext_bh);
 383 err_alloc:
 384         brelse(ext_bh);
 385         clear_buffer_mapped(bh_result);
 386         bh_result->b_bdev = NULL;
 387         // unlock cache
 388         affs_unlock_ext(inode);
 389         return -ENOSPC;
 390 }
 391
 392 static int affs_writepage(struct page *page, struct writeback_control *wbc)
 393 {
 394         return block_write_full_page(page, affs_get_block, wbc);
 395 }
 396 static int affs_readpage(struct file *file, struct page *page)
 397 {
 398         return block_read_full_page(page, affs_get_block);
 399 }
 400 static int affs_prepare_write(struct file *file, struct page *page, unsigned from, unsigned to)
 401 {
 402         return cont_prepare_write(page, from, to, affs_get_block,
 403                 &AFFS_I(page->mapping->host)->mmu_private);
 404 }
 405 static sector_t _affs_bmap(struct address_space *mapping, sector_t block)
 406 {
 407         return generic_block_bmap(mapping,block,affs_get_block);
 408 }
 409 const struct address_space_operations affs_aops = {
 410         .readpage = affs_readpage,
 411         .writepage = affs_writepage,
 412         .sync_page = block_sync_page,
 413         .prepare_write = affs_prepare_write,
 414         .commit_write = generic_commit_write,
 415         .bmap = _affs_bmap
 416 };
 417
 418 static inline struct buffer_head *
 419 affs_bread_ino(struct inode *inode, int block, int create)
 420 {
 421         struct buffer_head *bh, tmp_bh;
 422         int err;
 423
 424         tmp_bh.b_state = 0;
 425         err = affs_get_block(inode, block, &tmp_bh, create);
 426         if (!err) {
 427                 bh = affs_bread(inode->i_sb, tmp_bh.b_blocknr);
 428                 if (bh) {
 429                         bh->b_state |= tmp_bh.b_state;
 430                         return bh;
 431                 }
 432                 err = -EIO;
 433         }
 434         return ERR_PTR(err);
 435 }
 436
 437 static inline struct buffer_head *
 438 affs_getzeroblk_ino(struct inode *inode, int block)
 439 {
 440         struct buffer_head *bh, tmp_bh;
 441         int err;
 442
 443         tmp_bh.b_state = 0;
 444         err = affs_get_block(inode, block, &tmp_bh, 1);
 445         if (!err) {
 446                 bh = affs_getzeroblk(inode->i_sb, tmp_bh.b_blocknr);
 447                 if (bh) {
 448                         bh->b_state |= tmp_bh.b_state;
 449                         return bh;
 450                 }
 451                 err = -EIO;
 452         }
 453         return ERR_PTR(err);
 454 }
 455
 456 static inline struct buffer_head *
 457 affs_getemptyblk_ino(struct inode *inode, int block)
 458 {
 459         struct buffer_head *bh, tmp_bh;
 460         int err;
 461
 462         tmp_bh.b_state = 0;
 463         err = affs_get_block(inode, block, &tmp_bh, 1);
 464         if (!err) {
 465                 bh = affs_getemptyblk(inode->i_sb, tmp_bh.b_blocknr);
 466                 if (bh) {
 467                         bh->b_state |= tmp_bh.b_state;
 468                         return bh;
 469                 }
 470                 err = -EIO;
 471         }
 472         return ERR_PTR(err);
 473 }
 474
 475 static int
 476 affs_do_readpage_ofs(struct file *file, struct page *page, unsigned from, unsigned to)
 477 {
 478         struct inode *inode = page->mapping->host;
 479         struct super_block *sb = inode->i_sb;
 480         struct buffer_head *bh;
 481         char *data;
 482         u32 bidx, boff, bsize;
 483         u32 tmp;
 484
 485         pr_debug("AFFS: read_page(%u, %ld, %d, %d)\n", (u32)inode->i_ino, page->index, from, to);
 486         if (from > to || to > PAGE_CACHE_SIZE)
 487                 BUG();
 488         kmap(page);
 489         data = page_address(page);
 490         bsize = AFFS_SB(sb)->s_data_blksize;
 491         tmp = (page->index << PAGE_CACHE_SHIFT) + from;
 492         bidx = tmp / bsize;
 493         boff = tmp % bsize;
 494
 495         while (from < to) {
 496                 bh = affs_bread_ino(inode, bidx, 0);
 497                 if (IS_ERR(bh))
 498                         return PTR_ERR(bh);
 499                 tmp = min(bsize - boff, to - from);
 500                 if (from + tmp > to || tmp > bsize)
 501                         BUG();
 502                 memcpy(data + from, AFFS_DATA(bh) + boff, tmp);
 503                 affs_brelse(bh);
 504                 bidx++;
 505                 from += tmp;
 506                 boff = 0;
 507         }
 508         flush_dcache_page(page);
 509         kunmap(page);
 510         return 0;
 511 }
 512
 513 static int
 514 affs_extent_file_ofs(struct inode *inode, u32 newsize)
 515 {
 516         struct super_block *sb = inode->i_sb;
 517         struct buffer_head *bh, *prev_bh;
 518         u32 bidx, boff;
 519         u32 size, bsize;
 520         u32 tmp;
 521
 522         pr_debug("AFFS: extent_file(%u, %d)\n", (u32)inode->i_ino, newsize);
 523         bsize = AFFS_SB(sb)->s_data_blksize;
 524         bh = NULL;
 525         size = AFFS_I(inode)->mmu_private;
 526         bidx = size / bsize;
 527         boff = size % bsize;
 528         if (boff) {
 529                 bh = affs_bread_ino(inode, bidx, 0);
 530                 if (IS_ERR(bh))
 531                         return PTR_ERR(bh);
 532                 tmp = min(bsize - boff, newsize - size);
 533                 if (boff + tmp > bsize || tmp > bsize)
 534                         BUG();
 535                 memset(AFFS_DATA(bh) + boff, 0, tmp);
 536                 AFFS_DATA_HEAD(bh)->size = cpu_to_be32(be32_to_cpu(AFFS_DATA_HEAD(bh)->size) + tmp);
 537                 affs_fix_checksum(sb, bh);
 538                 mark_buffer_dirty_inode(bh, inode);
 539                 size += tmp;
 540                 bidx++;
 541         } else if (bidx) {
 542                 bh = affs_bread_ino(inode, bidx - 1, 0);
 543                 if (IS_ERR(bh))
 544                         return PTR_ERR(bh);
 545         }
 546
 547         while (size < newsize) {
 548                 prev_bh = bh;
 549                 bh = affs_getzeroblk_ino(inode, bidx);
 550                 if (IS_ERR(bh))
 551                         goto out;
 552                 tmp = min(bsize, newsize - size);
 553                 if (tmp > bsize)
 554                         BUG();
 555                 AFFS_DATA_HEAD(bh)->ptype = cpu_to_be32(T_DATA);
 556                 AFFS_DATA_HEAD(bh)->key = cpu_to_be32(inode->i_ino);
 557                 AFFS_DATA_HEAD(bh)->sequence = cpu_to_be32(bidx);
 558                 AFFS_DATA_HEAD(bh)->size = cpu_to_be32(tmp);
 559                 affs_fix_checksum(sb, bh);
 560                 bh->b_state &= ~(1UL << BH_New);
 561                 mark_buffer_dirty_inode(bh, inode);
 562                 if (prev_bh) {
 563                         u32 tmp = be32_to_cpu(AFFS_DATA_HEAD(prev_bh)->next);
 564                         if (tmp)
 565                                 affs_warning(sb, "extent_file_ofs", "next block already set for %d (%d)", bidx, tmp);
 566                         AFFS_DATA_HEAD(prev_bh)->next = cpu_to_be32(bh->b_blocknr);
 567                         affs_adjust_checksum(prev_bh, bh->b_blocknr - tmp);
 568                         mark_buffer_dirty_inode(prev_bh, inode);
 569                         affs_brelse(prev_bh);
 570                 }
 571                 size += bsize;
 572                 bidx++;
 573         }
 574         affs_brelse(bh);
 575         inode->i_size = AFFS_I(inode)->mmu_private = newsize;
 576         return 0;
 577
 578 out:
 579         inode->i_size = AFFS_I(inode)->mmu_private = newsize;
 580         return PTR_ERR(bh);
 581 }
 582
 583 static int
 584 affs_readpage_ofs(struct file *file, struct page *page)
 585 {
 586         struct inode *inode = page->mapping->host;
 587         u32 to;
 588         int err;
 589
 590         pr_debug("AFFS: read_page(%u, %ld)\n", (u32)inode->i_ino, page->index);
 591         to = PAGE_CACHE_SIZE;
 592         if (((page->index + 1) << PAGE_CACHE_SHIFT) > inode->i_size) {
 593                 to = inode->i_size & ~PAGE_CACHE_MASK;
 594                 memset(page_address(page) + to, 0, PAGE_CACHE_SIZE - to);
 595         }
 596
 597         err = affs_do_readpage_ofs(file, page, 0, to);
 598         if (!err)
 599                 SetPageUptodate(page);
 600         unlock_page(page);
 601         return err;
 602 }
 603
 604 static int affs_prepare_write_ofs(struct file *file, struct page *page, unsigned from, unsigned to)
 605 {
 606         struct inode *inode = page->mapping->host;
 607         u32 size, offset;
 608         u32 tmp;
 609         int err = 0;
 610
 611         pr_debug("AFFS: prepare_write(%u, %ld, %d, %d)\n", (u32)inode->i_ino, page->index, from, to);
 612         offset = page->index << PAGE_CACHE_SHIFT;
 613         if (offset + from > AFFS_I(inode)->mmu_private) {
 614                 err = affs_extent_file_ofs(inode, offset + from);
 615                 if (err)
 616                         return err;
 617         }
 618         size = inode->i_size;
 619
 620         if (PageUptodate(page))
 621                 return 0;
 622
 623         if (from) {
 624                 err = affs_do_readpage_ofs(file, page, 0, from);
 625                 if (err)
 626                         return err;
 627         }
 628         if (to < PAGE_CACHE_SIZE) {
 629                 char *kaddr = kmap_atomic(page, KM_USER0);
 630
 631                 memset(kaddr + to, 0, PAGE_CACHE_SIZE - to);
 632                 flush_dcache_page(page);
 633                 kunmap_atomic(kaddr, KM_USER0);
 634                 if (size > offset + to) {
 635                         if (size < offset + PAGE_CACHE_SIZE)
 636                                 tmp = size & ~PAGE_CACHE_MASK;
 637                         else
 638                                 tmp = PAGE_CACHE_SIZE;
 639                         err = affs_do_readpage_ofs(file, page, to, tmp);
 640                 }
 641         }
 642         return err;
 643 }
 644
 645 static int affs_commit_write_ofs(struct file *file, struct page *page, unsigned from, unsigned to)
 646 {
 647         struct inode *inode = page->mapping->host;
 648         struct super_block *sb = inode->i_sb;
 649         struct buffer_head *bh, *prev_bh;
 650         char *data;
 651         u32 bidx, boff, bsize;
 652         u32 tmp;
 653         int written;
 654
 655         pr_debug("AFFS: commit_write(%u, %ld, %d, %d)\n", (u32)inode->i_ino, page->index, from, to);
 656         bsize = AFFS_SB(sb)->s_data_blksize;
 657         data = page_address(page);
 658
 659         bh = NULL;
 660         written = 0;
 661         tmp = (page->index << PAGE_CACHE_SHIFT) + from;
 662         bidx = tmp / bsize;
 663         boff = tmp % bsize;
 664         if (boff) {
 665                 bh = affs_bread_ino(inode, bidx, 0);
 666                 if (IS_ERR(bh))
 667                         return PTR_ERR(bh);
 668                 tmp = min(bsize - boff, to - from);
 669                 if (boff + tmp > bsize || tmp > bsize)
 670                         BUG();
 671                 memcpy(AFFS_DATA(bh) + boff, data + from, tmp);
 672                 AFFS_DATA_HEAD(bh)->size = cpu_to_be32(be32_to_cpu(AFFS_DATA_HEAD(bh)->size) + tmp);
 673                 affs_fix_checksum(sb, bh);
 674                 mark_buffer_dirty_inode(bh, inode);
 675                 written += tmp;
 676                 from += tmp;
 677                 bidx++;
 678         } else if (bidx) {
 679                 bh = affs_bread_ino(inode, bidx - 1, 0);
 680                 if (IS_ERR(bh))
 681                         return PTR_ERR(bh);
 682         }
 683         while (from + bsize <= to) {
 684                 prev_bh = bh;
 685                 bh = affs_getemptyblk_ino(inode, bidx);
 686                 if (IS_ERR(bh))
 687                         goto out;
 688                 memcpy(AFFS_DATA(bh), data + from, bsize);
 689                 if (buffer_new(bh)) {
 690                         AFFS_DATA_HEAD(bh)->ptype = cpu_to_be32(T_DATA);
 691                         AFFS_DATA_HEAD(bh)->key = cpu_to_be32(inode->i_ino);
 692                         AFFS_DATA_HEAD(bh)->sequence = cpu_to_be32(bidx);
 693                         AFFS_DATA_HEAD(bh)->size = cpu_to_be32(bsize);
 694                         AFFS_DATA_HEAD(bh)->next = 0;
 695                         bh->b_state &= ~(1UL << BH_New);
 696                         if (prev_bh) {
 697                                 u32 tmp = be32_to_cpu(AFFS_DATA_HEAD(prev_bh)->next);
 698                                 if (tmp)
 699                                         affs_warning(sb, "commit_write_ofs", "next block already set for %d (%d)", bidx, tmp);
 700                                 AFFS_DATA_HEAD(prev_bh)->next = cpu_to_be32(bh->b_blocknr);
 701                                 affs_adjust_checksum(prev_bh, bh->b_blocknr - tmp);
 702                                 mark_buffer_dirty_inode(prev_bh, inode);
 703                         }
 704                 }
 705                 affs_brelse(prev_bh);
 706                 affs_fix_checksum(sb, bh);
 707                 mark_buffer_dirty_inode(bh, inode);
 708                 written += bsize;
 709                 from += bsize;
 710                 bidx++;
 711         }
 712         if (from < to) {
 713                 prev_bh = bh;
 714                 bh = affs_bread_ino(inode, bidx, 1);
 715                 if (IS_ERR(bh))
 716                         goto out;
 717                 tmp = min(bsize, to - from);
 718                 if (tmp > bsize)
 719                         BUG();
 720                 memcpy(AFFS_DATA(bh), data + from, tmp);
 721                 if (buffer_new(bh)) {
 722                         AFFS_DATA_HEAD(bh)->ptype = cpu_to_be32(T_DATA);
 723                         AFFS_DATA_HEAD(bh)->key = cpu_to_be32(inode->i_ino);
 724                         AFFS_DATA_HEAD(bh)->sequence = cpu_to_be32(bidx);
 725                         AFFS_DATA_HEAD(bh)->size = cpu_to_be32(tmp);
 726                         AFFS_DATA_HEAD(bh)->next = 0;
 727                         bh->b_state &= ~(1UL << BH_New);
 728                         if (prev_bh) {
 729                                 u32 tmp = be32_to_cpu(AFFS_DATA_HEAD(prev_bh)->next);
 730                                 if (tmp)
 731                                         affs_warning(sb, "commit_write_ofs", "next block already set for %d (%d)", bidx, tmp);
 732                                 AFFS_DATA_HEAD(prev_bh)->next = cpu_to_be32(bh->b_blocknr);
 733                                 affs_adjust_checksum(prev_bh, bh->b_blocknr - tmp);
 734                                 mark_buffer_dirty_inode(prev_bh, inode);
 735                         }
 736                 } else if (be32_to_cpu(AFFS_DATA_HEAD(bh)->size) < tmp)
 737                         AFFS_DATA_HEAD(bh)->size = cpu_to_be32(tmp);
 738                 affs_brelse(prev_bh);
 739                 affs_fix_checksum(sb, bh);
 740                 mark_buffer_dirty_inode(bh, inode);
 741                 written += tmp;
 742                 from += tmp;
 743                 bidx++;
 744         }
 745         SetPageUptodate(page);
 746
 747 done:
 748         affs_brelse(bh);
 749         tmp = (page->index << PAGE_CACHE_SHIFT) + from;
 750         if (tmp > inode->i_size)
 751                 inode->i_size = AFFS_I(inode)->mmu_private = tmp;
 752
 753         return written;
 754
 755 out:
 756         bh = prev_bh;
 757         if (!written)
 758                 written = PTR_ERR(bh);
 759         goto done;
 760 }
 761
 762 const struct address_space_operations affs_aops_ofs = {
 763         .readpage = affs_readpage_ofs,
 764         //.writepage = affs_writepage_ofs,
 765         //.sync_page = affs_sync_page_ofs,
 766         .prepare_write = affs_prepare_write_ofs,
 767         .commit_write = affs_commit_write_ofs
 768 };
 769
 770 /* Free any preallocated blocks. */
 771
 772 void
 773 affs_free_prealloc(struct inode *inode)
 774 {
 775         struct super_block *sb = inode->i_sb;
 776
 777         pr_debug("AFFS: free_prealloc(ino=%lu)\n", inode->i_ino);
 778
 779         while (AFFS_I(inode)->i_pa_cnt) {
 780                 AFFS_I(inode)->i_pa_cnt--;
 781                 affs_free_block(sb, ++AFFS_I(inode)->i_lastalloc);
 782         }
 783 }
 784
 785 /* Truncate (or enlarge) a file to the requested size. */
 786
 787 void
 788 affs_truncate(struct inode *inode)
 789 {
 790         struct super_block *sb = inode->i_sb;
 791         u32 ext, ext_key;
 792         u32 last_blk, blkcnt, blk;
 793         u32 size;
 794         struct buffer_head *ext_bh;
 795         int i;
 796
 797         pr_debug("AFFS: truncate(inode=%d, oldsize=%u, newsize=%u)\n",
 798                  (u32)inode->i_ino, (u32)AFFS_I(inode)->mmu_private, (u32)inode->i_size);
 799
 800         last_blk = 0;
 801         ext = 0;
 802         if (inode->i_size) {
 803                 last_blk = ((u32)inode->i_size - 1) / AFFS_SB(sb)->s_data_blksize;
 804                 ext = last_blk / AFFS_SB(sb)->s_hashsize;
 805         }
 806
 807         if (inode->i_size > AFFS_I(inode)->mmu_private) {
 808                 struct address_space *mapping = inode->i_mapping;
 809                 struct page *page;
 810                 u32 size = inode->i_size - 1;
 811                 int res;
 812
 813                 page = grab_cache_page(mapping, size >> PAGE_CACHE_SHIFT);
 814                 if (!page)
 815                         return;
 816                 size = (size & (PAGE_CACHE_SIZE - 1)) + 1;
 817                 res = mapping->a_ops->prepare_write(NULL, page, size, size);
 818                 if (!res)
 819                         res = mapping->a_ops->commit_write(NULL, page, size, size);
 820                 unlock_page(page);
 821                 page_cache_release(page);
 822                 mark_inode_dirty(inode);
 823                 return;
 824         } else if (inode->i_size == AFFS_I(inode)->mmu_private)
 825                 return;
 826
 827         // lock cache
 828         ext_bh = affs_get_extblock(inode, ext);
 829         if (IS_ERR(ext_bh)) {
 830                 affs_warning(sb, "truncate", "unexpected read error for ext block %u (%d)",
 831                              ext, PTR_ERR(ext_bh));
 832                 return;
 833         }
 834         if (AFFS_I(inode)->i_lc) {
 835                 /* clear linear cache */
 836                 i = (ext + 1) >> AFFS_I(inode)->i_lc_shift;
 837                 if (AFFS_I(inode)->i_lc_size > i) {
 838                         AFFS_I(inode)->i_lc_size = i;
 839                         for (; i < AFFS_LC_SIZE; i++)
 840                                 AFFS_I(inode)->i_lc[i] = 0;
 841                 }
 842                 /* clear associative cache */
 843                 for (i = 0; i < AFFS_AC_SIZE; i++)
 844                         if (AFFS_I(inode)->i_ac[i].ext >= ext)
 845                                 AFFS_I(inode)->i_ac[i].ext = 0;
 846         }
 847         ext_key = be32_to_cpu(AFFS_TAIL(sb, ext_bh)->extension);
 848
 849         blkcnt = AFFS_I(inode)->i_blkcnt;
 850         i = 0;
 851         blk = last_blk;
 852         if (inode->i_size) {
 853                 i = last_blk % AFFS_SB(sb)->s_hashsize + 1;
 854                 blk++;
 855         } else
 856                 AFFS_HEAD(ext_bh)->first_data = 0;
 857         size = AFFS_SB(sb)->s_hashsize;
 858         if (size > blkcnt - blk + i)
 859                 size = blkcnt - blk + i;
 860         for (; i < size; i++, blk++) {
 861                 affs_free_block(sb, be32_to_cpu(AFFS_BLOCK(sb, ext_bh, i)));
 862                 AFFS_BLOCK(sb, ext_bh, i) = 0;
 863         }
 864         AFFS_TAIL(sb, ext_bh)->extension = 0;
 865         affs_fix_checksum(sb, ext_bh);
 866         mark_buffer_dirty_inode(ext_bh, inode);
 867         affs_brelse(ext_bh);
 868
 869         if (inode->i_size) {
 870                 AFFS_I(inode)->i_blkcnt = last_blk + 1;
 871                 AFFS_I(inode)->i_extcnt = ext + 1;
 872                 if (AFFS_SB(sb)->s_flags & SF_OFS) {
 873                         struct buffer_head *bh = affs_bread_ino(inode, last_blk, 0);
 874                         u32 tmp;
 875                         if (IS_ERR(ext_bh)) {
 876                                 affs_warning(sb, "truncate", "unexpected read error for last block %u (%d)",
 877                                              ext, PTR_ERR(ext_bh));
 878                                 return;
 879                         }
 880                         tmp = be32_to_cpu(AFFS_DATA_HEAD(bh)->next);
 881                         AFFS_DATA_HEAD(bh)->next = 0;
 882                         affs_adjust_checksum(bh, -tmp);
 883                         affs_brelse(bh);
 884                 }
 885         } else {
 886                 AFFS_I(inode)->i_blkcnt = 0;
 887                 AFFS_I(inode)->i_extcnt = 1;
 888         }
 889         AFFS_I(inode)->mmu_private = inode->i_size;
 890         // unlock cache
 891
 892         while (ext_key) {
 893                 ext_bh = affs_bread(sb, ext_key);
 894                 size = AFFS_SB(sb)->s_hashsize;
 895                 if (size > blkcnt - blk)
 896                         size = blkcnt - blk;
 897                 for (i = 0; i < size; i++, blk++)
 898                         affs_free_block(sb, be32_to_cpu(AFFS_BLOCK(sb, ext_bh, i)));
 899                 affs_free_block(sb, ext_key);
 900                 ext_key = be32_to_cpu(AFFS_TAIL(sb, ext_bh)->extension);
 901                 affs_brelse(ext_bh);
 902         }
 903         affs_free_prealloc(inode);
 904 }