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           = do_sync_read,
  31         .aio_read       = generic_file_aio_read,
  32         .write          = do_sync_write,
  33         .aio_write      = generic_file_aio_write,
  34         .mmap           = generic_file_mmap,
  35         .open           = affs_file_open,
  36         .release        = affs_file_release,
  37         .fsync          = affs_file_fsync,
  38         .splice_read    = generic_file_splice_read,
  39 };
  40
  41 const struct inode_operations affs_file_inode_operations = {
  42         .truncate       = affs_truncate,
  43         .setattr        = affs_notify_change,
  44 };
  45
  46 static int
  47 affs_file_open(struct inode *inode, struct file *filp)
  48 {
  49         pr_debug("AFFS: open(%lu,%d)\n",
  50                  inode->i_ino, atomic_read(&AFFS_I(inode)->i_opencnt));
  51         atomic_inc(&AFFS_I(inode)->i_opencnt);
  52         return 0;
  53 }
  54
  55 static int
  56 affs_file_release(struct inode *inode, struct file *filp)
  57 {
  58         pr_debug("AFFS: release(%lu, %d)\n",
  59                  inode->i_ino, atomic_read(&AFFS_I(inode)->i_opencnt));
  60
  61         if (atomic_dec_and_test(&AFFS_I(inode)->i_opencnt)) {
  62                 mutex_lock(&inode->i_mutex);
  63                 if (inode->i_size != AFFS_I(inode)->mmu_private)
  64                         affs_truncate(inode);
  65                 affs_free_prealloc(inode);
  66                 mutex_unlock(&inode->i_mutex);
  67         }
  68
  69         return 0;
  70 }
  71
  72 static int
  73 affs_grow_extcache(struct inode *inode, u32 lc_idx)
  74 {
  75         struct super_block      *sb = inode->i_sb;
  76         struct buffer_head      *bh;
  77         u32 lc_max;
  78         int i, j, key;
  79
  80         if (!AFFS_I(inode)->i_lc) {
  81                 char *ptr = (char *)get_zeroed_page(GFP_NOFS);
  82                 if (!ptr)
  83                         return -ENOMEM;
  84                 AFFS_I(inode)->i_lc = (u32 *)ptr;
  85                 AFFS_I(inode)->i_ac = (struct affs_ext_key *)(ptr + AFFS_CACHE_SIZE / 2);
  86         }
  87
  88         lc_max = AFFS_LC_SIZE << AFFS_I(inode)->i_lc_shift;
  89
  90         if (AFFS_I(inode)->i_extcnt > lc_max) {
  91                 u32 lc_shift, lc_mask, tmp, off;
  92
  93                 /* need to recalculate linear cache, start from old size */
  94                 lc_shift = AFFS_I(inode)->i_lc_shift;
  95                 tmp = (AFFS_I(inode)->i_extcnt / AFFS_LC_SIZE) >> lc_shift;
  96                 for (; tmp; tmp >>= 1)
  97                         lc_shift++;
  98                 lc_mask = (1 << lc_shift) - 1;
  99
 100                 /* fix idx and old size to new shift */
 101                 lc_idx >>= (lc_shift - AFFS_I(inode)->i_lc_shift);
 102                 AFFS_I(inode)->i_lc_size >>= (lc_shift - AFFS_I(inode)->i_lc_shift);
 103
 104                 /* first shrink old cache to make more space */
 105                 off = 1 << (lc_shift - AFFS_I(inode)->i_lc_shift);
 106                 for (i = 1, j = off; j < AFFS_LC_SIZE; i++, j += off)
 107                         AFFS_I(inode)->i_ac[i] = AFFS_I(inode)->i_ac[j];
 108
 109                 AFFS_I(inode)->i_lc_shift = lc_shift;
 110                 AFFS_I(inode)->i_lc_mask = lc_mask;
 111         }
 112
 113         /* fill cache to the needed index */
 114         i = AFFS_I(inode)->i_lc_size;
 115         AFFS_I(inode)->i_lc_size = lc_idx + 1;
 116         for (; i <= lc_idx; i++) {
 117                 if (!i) {
 118                         AFFS_I(inode)->i_lc[0] = inode->i_ino;
 119                         continue;
 120                 }
 121                 key = AFFS_I(inode)->i_lc[i - 1];
 122                 j = AFFS_I(inode)->i_lc_mask + 1;
 123                 // unlock cache
 124                 for (; j > 0; j--) {
 125                         bh = affs_bread(sb, key);
 126                         if (!bh)
 127                                 goto err;
 128                         key = be32_to_cpu(AFFS_TAIL(sb, bh)->extension);
 129                         affs_brelse(bh);
 130                 }
 131                 // lock cache
 132                 AFFS_I(inode)->i_lc[i] = key;
 133         }
 134
 135         return 0;
 136
 137 err:
 138         // lock cache
 139         return -EIO;
 140 }
 141
 142 static struct buffer_head *
 143 affs_alloc_extblock(struct inode *inode, struct buffer_head *bh, u32 ext)
 144 {
 145         struct super_block *sb = inode->i_sb;
 146         struct buffer_head *new_bh;
 147         u32 blocknr, tmp;
 148
 149         blocknr = affs_alloc_block(inode, bh->b_blocknr);
 150         if (!blocknr)
 151                 return ERR_PTR(-ENOSPC);
 152
 153         new_bh = affs_getzeroblk(sb, blocknr);
 154         if (!new_bh) {
 155                 affs_free_block(sb, blocknr);
 156                 return ERR_PTR(-EIO);
 157         }
 158
 159         AFFS_HEAD(new_bh)->ptype = cpu_to_be32(T_LIST);
 160         AFFS_HEAD(new_bh)->key = cpu_to_be32(blocknr);
 161         AFFS_TAIL(sb, new_bh)->stype = cpu_to_be32(ST_FILE);
 162         AFFS_TAIL(sb, new_bh)->parent = cpu_to_be32(inode->i_ino);
 163         affs_fix_checksum(sb, new_bh);
 164
 165         mark_buffer_dirty_inode(new_bh, inode);
 166
 167         tmp = be32_to_cpu(AFFS_TAIL(sb, bh)->extension);
 168         if (tmp)
 169                 affs_warning(sb, "alloc_ext", "previous extension set (%x)", tmp);
 170         AFFS_TAIL(sb, bh)->extension = cpu_to_be32(blocknr);
 171         affs_adjust_checksum(bh, blocknr - tmp);
 172         mark_buffer_dirty_inode(bh, inode);
 173
 174         AFFS_I(inode)->i_extcnt++;
 175         mark_inode_dirty(inode);
 176
 177         return new_bh;
 178 }
 179
 180 static inline struct buffer_head *
 181 affs_get_extblock(struct inode *inode, u32 ext)
 182 {
 183         /* inline the simplest case: same extended block as last time */
 184         struct buffer_head *bh = AFFS_I(inode)->i_ext_bh;
 185         if (ext == AFFS_I(inode)->i_ext_last)
 186                 get_bh(bh);
 187         else
 188                 /* we have to do more (not inlined) */
 189                 bh = affs_get_extblock_slow(inode, ext);
 190
 191         return bh;
 192 }
 193
 194 static struct buffer_head *
 195 affs_get_extblock_slow(struct inode *inode, u32 ext)
 196 {
 197         struct super_block *sb = inode->i_sb;
 198         struct buffer_head *bh;
 199         u32 ext_key;
 200         u32 lc_idx, lc_off, ac_idx;
 201         u32 tmp, idx;
 202
 203         if (ext == AFFS_I(inode)->i_ext_last + 1) {
 204                 /* read the next extended block from the current one */
 205                 bh = AFFS_I(inode)->i_ext_bh;
 206                 ext_key = be32_to_cpu(AFFS_TAIL(sb, bh)->extension);
 207                 if (ext < AFFS_I(inode)->i_extcnt)
 208                         goto read_ext;
 209                 if (ext > AFFS_I(inode)->i_extcnt)
 210                         BUG();
 211                 bh = affs_alloc_extblock(inode, bh, ext);
 212                 if (IS_ERR(bh))
 213                         return bh;
 214                 goto store_ext;
 215         }
 216
 217         if (ext == 0) {
 218                 /* we seek back to the file header block */
 219                 ext_key = inode->i_ino;
 220                 goto read_ext;
 221         }
 222
 223         if (ext >= AFFS_I(inode)->i_extcnt) {
 224                 struct buffer_head *prev_bh;
 225
 226                 /* allocate a new extended block */
 227                 if (ext > AFFS_I(inode)->i_extcnt)
 228                         BUG();
 229
 230                 /* get previous extended block */
 231                 prev_bh = affs_get_extblock(inode, ext - 1);
 232                 if (IS_ERR(prev_bh))
 233                         return prev_bh;
 234                 bh = affs_alloc_extblock(inode, prev_bh, ext);
 235                 affs_brelse(prev_bh);
 236                 if (IS_ERR(bh))
 237                         return bh;
 238                 goto store_ext;
 239         }
 240
 241 again:
 242         /* check if there is an extended cache and whether it's large enough */
 243         lc_idx = ext >> AFFS_I(inode)->i_lc_shift;
 244         lc_off = ext & AFFS_I(inode)->i_lc_mask;
 245
 246         if (lc_idx >= AFFS_I(inode)->i_lc_size) {
 247                 int err;
 248
 249                 err = affs_grow_extcache(inode, lc_idx);
 250                 if (err)
 251                         return ERR_PTR(err);
 252                 goto again;
 253         }
 254
 255         /* every n'th key we find in the linear cache */
 256         if (!lc_off) {
 257                 ext_key = AFFS_I(inode)->i_lc[lc_idx];
 258                 goto read_ext;
 259         }
 260
 261         /* maybe it's still in the associative cache */
 262         ac_idx = (ext - lc_idx - 1) & AFFS_AC_MASK;
 263         if (AFFS_I(inode)->i_ac[ac_idx].ext == ext) {
 264                 ext_key = AFFS_I(inode)->i_ac[ac_idx].key;
 265                 goto read_ext;
 266         }
 267
 268         /* try to find one of the previous extended blocks */
 269         tmp = ext;
 270         idx = ac_idx;
 271         while (--tmp, --lc_off > 0) {
 272                 idx = (idx - 1) & AFFS_AC_MASK;
 273                 if (AFFS_I(inode)->i_ac[idx].ext == tmp) {
 274                         ext_key = AFFS_I(inode)->i_ac[idx].key;
 275                         goto find_ext;
 276                 }
 277         }
 278
 279         /* fall back to the linear cache */
 280         ext_key = AFFS_I(inode)->i_lc[lc_idx];
 281 find_ext:
 282         /* read all extended blocks until we find the one we need */
 283         //unlock cache
 284         do {
 285                 bh = affs_bread(sb, ext_key);
 286                 if (!bh)
 287                         goto err_bread;
 288                 ext_key = be32_to_cpu(AFFS_TAIL(sb, bh)->extension);
 289                 affs_brelse(bh);
 290                 tmp++;
 291         } while (tmp < ext);
 292         //lock cache
 293
 294         /* store it in the associative cache */
 295         // recalculate ac_idx?
 296         AFFS_I(inode)->i_ac[ac_idx].ext = ext;
 297         AFFS_I(inode)->i_ac[ac_idx].key = ext_key;
 298
 299 read_ext:
 300         /* finally read the right extended block */
 301         //unlock cache
 302         bh = affs_bread(sb, ext_key);
 303         if (!bh)
 304                 goto err_bread;
 305         //lock cache
 306
 307 store_ext:
 308         /* release old cached extended block and store the new one */
 309         affs_brelse(AFFS_I(inode)->i_ext_bh);
 310         AFFS_I(inode)->i_ext_last = ext;
 311         AFFS_I(inode)->i_ext_bh = bh;
 312         get_bh(bh);
 313
 314         return bh;
 315
 316 err_bread:
 317         affs_brelse(bh);
 318         return ERR_PTR(-EIO);
 319 }
 320
 321 static int
 322 affs_get_block(struct inode *inode, sector_t block, struct buffer_head *bh_result, int create)
 323 {
 324         struct super_block      *sb = inode->i_sb;
 325         struct buffer_head      *ext_bh;
 326         u32                      ext;
 327
 328         pr_debug("AFFS: get_block(%u, %lu)\n", (u32)inode->i_ino, (unsigned long)block);
 329
 330         BUG_ON(block > (sector_t)0x7fffffffUL);
 331
 332         if (block >= AFFS_I(inode)->i_blkcnt) {
 333                 if (block > AFFS_I(inode)->i_blkcnt || !create)
 334                         goto err_big;
 335         } else
 336                 create = 0;
 337
 338         //lock cache
 339         affs_lock_ext(inode);
 340
 341         ext = (u32)block / AFFS_SB(sb)->s_hashsize;
 342         block -= ext * AFFS_SB(sb)->s_hashsize;
 343         ext_bh = affs_get_extblock(inode, ext);
 344         if (IS_ERR(ext_bh))
 345                 goto err_ext;
 346         map_bh(bh_result, sb, (sector_t)be32_to_cpu(AFFS_BLOCK(sb, ext_bh, block)));
 347
 348         if (create) {
 349                 u32 blocknr = affs_alloc_block(inode, ext_bh->b_blocknr);
 350                 if (!blocknr)
 351                         goto err_alloc;
 352                 set_buffer_new(bh_result);
 353                 AFFS_I(inode)->mmu_private += AFFS_SB(sb)->s_data_blksize;
 354                 AFFS_I(inode)->i_blkcnt++;
 355
 356                 /* store new block */
 357                 if (bh_result->b_blocknr)
 358                         affs_warning(sb, "get_block", "block already set (%x)", bh_result->b_blocknr);
 359                 AFFS_BLOCK(sb, ext_bh, block) = cpu_to_be32(blocknr);
 360                 AFFS_HEAD(ext_bh)->block_count = cpu_to_be32(block + 1);
 361                 affs_adjust_checksum(ext_bh, blocknr - bh_result->b_blocknr + 1);
 362                 bh_result->b_blocknr = blocknr;
 363
 364                 if (!block) {
 365                         /* insert first block into header block */
 366                         u32 tmp = be32_to_cpu(AFFS_HEAD(ext_bh)->first_data);
 367                         if (tmp)
 368                                 affs_warning(sb, "get_block", "first block already set (%d)", tmp);
 369                         AFFS_HEAD(ext_bh)->first_data = cpu_to_be32(blocknr);
 370                         affs_adjust_checksum(ext_bh, blocknr - tmp);
 371                 }
 372         }
 373
 374         affs_brelse(ext_bh);
 375         //unlock cache
 376         affs_unlock_ext(inode);
 377         return 0;
 378
 379 err_big:
 380         affs_error(inode->i_sb,"get_block","strange block request %d", block);
 381         return -EIO;
 382 err_ext:
 383         // unlock cache
 384         affs_unlock_ext(inode);
 385         return PTR_ERR(ext_bh);
 386 err_alloc:
 387         brelse(ext_bh);
 388         clear_buffer_mapped(bh_result);
 389         bh_result->b_bdev = NULL;
 390         // unlock cache
 391         affs_unlock_ext(inode);
 392         return -ENOSPC;
 393 }
 394
 395 static int affs_writepage(struct page *page, struct writeback_control *wbc)
 396 {
 397         return block_write_full_page(page, affs_get_block, wbc);
 398 }
 399
 400 static int affs_readpage(struct file *file, struct page *page)
 401 {
 402         return block_read_full_page(page, affs_get_block);
 403 }
 404
 405 static int affs_write_begin(struct file *file, struct address_space *mapping,
 406                         loff_t pos, unsigned len, unsigned flags,
 407                         struct page **pagep, void **fsdata)
 408 {
 409         int ret;
 410
 411         *pagep = NULL;
 412         ret = cont_write_begin(file, mapping, pos, len, flags, pagep, fsdata,
 413                                 affs_get_block,
 414                                 &AFFS_I(mapping->host)->mmu_private);
 415         if (unlikely(ret)) {
 416                 loff_t isize = mapping->host->i_size;
 417                 if (pos + len > isize)
 418                         vmtruncate(mapping->host, isize);
 419         }
 420
 421         return ret;
 422 }
 423
 424 static sector_t _affs_bmap(struct address_space *mapping, sector_t block)
 425 {
 426         return generic_block_bmap(mapping,block,affs_get_block);
 427 }
 428
 429 const struct address_space_operations affs_aops = {
 430         .readpage = affs_readpage,
 431         .writepage = affs_writepage,
 432         .write_begin = affs_write_begin,
 433         .write_end = generic_write_end,
 434         .bmap = _affs_bmap
 435 };
 436
 437 static inline struct buffer_head *
 438 affs_bread_ino(struct inode *inode, int block, int create)
 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, create);
 445         if (!err) {
 446                 bh = affs_bread(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_getzeroblk_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_getzeroblk(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 inline struct buffer_head *
 476 affs_getemptyblk_ino(struct inode *inode, int block)
 477 {
 478         struct buffer_head *bh, tmp_bh;
 479         int err;
 480
 481         tmp_bh.b_state = 0;
 482         err = affs_get_block(inode, block, &tmp_bh, 1);
 483         if (!err) {
 484                 bh = affs_getemptyblk(inode->i_sb, tmp_bh.b_blocknr);
 485                 if (bh) {
 486                         bh->b_state |= tmp_bh.b_state;
 487                         return bh;
 488                 }
 489                 err = -EIO;
 490         }
 491         return ERR_PTR(err);
 492 }
 493
 494 static int
 495 affs_do_readpage_ofs(struct file *file, struct page *page, unsigned from, unsigned to)
 496 {
 497         struct inode *inode = page->mapping->host;
 498         struct super_block *sb = inode->i_sb;
 499         struct buffer_head *bh;
 500         char *data;
 501         u32 bidx, boff, bsize;
 502         u32 tmp;
 503
 504         pr_debug("AFFS: read_page(%u, %ld, %d, %d)\n", (u32)inode->i_ino, page->index, from, to);
 505         BUG_ON(from > to || to > PAGE_CACHE_SIZE);
 506         kmap(page);
 507         data = page_address(page);
 508         bsize = AFFS_SB(sb)->s_data_blksize;
 509         tmp = (page->index << PAGE_CACHE_SHIFT) + from;
 510         bidx = tmp / bsize;
 511         boff = tmp % bsize;
 512
 513         while (from < to) {
 514                 bh = affs_bread_ino(inode, bidx, 0);
 515                 if (IS_ERR(bh))
 516                         return PTR_ERR(bh);
 517                 tmp = min(bsize - boff, to - from);
 518                 BUG_ON(from + tmp > to || tmp > bsize);
 519                 memcpy(data + from, AFFS_DATA(bh) + boff, tmp);
 520                 affs_brelse(bh);
 521                 bidx++;
 522                 from += tmp;
 523                 boff = 0;
 524         }
 525         flush_dcache_page(page);
 526         kunmap(page);
 527         return 0;
 528 }
 529
 530 static int
 531 affs_extent_file_ofs(struct inode *inode, u32 newsize)
 532 {
 533         struct super_block *sb = inode->i_sb;
 534         struct buffer_head *bh, *prev_bh;
 535         u32 bidx, boff;
 536         u32 size, bsize;
 537         u32 tmp;
 538
 539         pr_debug("AFFS: extent_file(%u, %d)\n", (u32)inode->i_ino, newsize);
 540         bsize = AFFS_SB(sb)->s_data_blksize;
 541         bh = NULL;
 542         size = AFFS_I(inode)->mmu_private;
 543         bidx = size / bsize;
 544         boff = size % bsize;
 545         if (boff) {
 546                 bh = affs_bread_ino(inode, bidx, 0);
 547                 if (IS_ERR(bh))
 548                         return PTR_ERR(bh);
 549                 tmp = min(bsize - boff, newsize - size);
 550                 BUG_ON(boff + tmp > bsize || tmp > bsize);
 551                 memset(AFFS_DATA(bh) + boff, 0, tmp);
 552                 be32_add_cpu(&AFFS_DATA_HEAD(bh)->size, tmp);
 553                 affs_fix_checksum(sb, bh);
 554                 mark_buffer_dirty_inode(bh, inode);
 555                 size += tmp;
 556                 bidx++;
 557         } else if (bidx) {
 558                 bh = affs_bread_ino(inode, bidx - 1, 0);
 559                 if (IS_ERR(bh))
 560                         return PTR_ERR(bh);
 561         }
 562
 563         while (size < newsize) {
 564                 prev_bh = bh;
 565                 bh = affs_getzeroblk_ino(inode, bidx);
 566                 if (IS_ERR(bh))
 567                         goto out;
 568                 tmp = min(bsize, newsize - size);
 569                 BUG_ON(tmp > bsize);
 570                 AFFS_DATA_HEAD(bh)->ptype = cpu_to_be32(T_DATA);
 571                 AFFS_DATA_HEAD(bh)->key = cpu_to_be32(inode->i_ino);
 572                 AFFS_DATA_HEAD(bh)->sequence = cpu_to_be32(bidx);
 573                 AFFS_DATA_HEAD(bh)->size = cpu_to_be32(tmp);
 574                 affs_fix_checksum(sb, bh);
 575                 bh->b_state &= ~(1UL << BH_New);
 576                 mark_buffer_dirty_inode(bh, inode);
 577                 if (prev_bh) {
 578                         u32 tmp = be32_to_cpu(AFFS_DATA_HEAD(prev_bh)->next);
 579                         if (tmp)
 580                                 affs_warning(sb, "extent_file_ofs", "next block already set for %d (%d)", bidx, tmp);
 581                         AFFS_DATA_HEAD(prev_bh)->next = cpu_to_be32(bh->b_blocknr);
 582                         affs_adjust_checksum(prev_bh, bh->b_blocknr - tmp);
 583                         mark_buffer_dirty_inode(prev_bh, inode);
 584                         affs_brelse(prev_bh);
 585                 }
 586                 size += bsize;
 587                 bidx++;
 588         }
 589         affs_brelse(bh);
 590         inode->i_size = AFFS_I(inode)->mmu_private = newsize;
 591         return 0;
 592
 593 out:
 594         inode->i_size = AFFS_I(inode)->mmu_private = newsize;
 595         return PTR_ERR(bh);
 596 }
 597
 598 static int
 599 affs_readpage_ofs(struct file *file, struct page *page)
 600 {
 601         struct inode *inode = page->mapping->host;
 602         u32 to;
 603         int err;
 604
 605         pr_debug("AFFS: read_page(%u, %ld)\n", (u32)inode->i_ino, page->index);
 606         to = PAGE_CACHE_SIZE;
 607         if (((page->index + 1) << PAGE_CACHE_SHIFT) > inode->i_size) {
 608                 to = inode->i_size & ~PAGE_CACHE_MASK;
 609                 memset(page_address(page) + to, 0, PAGE_CACHE_SIZE - to);
 610         }
 611
 612         err = affs_do_readpage_ofs(file, page, 0, to);
 613         if (!err)
 614                 SetPageUptodate(page);
 615         unlock_page(page);
 616         return err;
 617 }
 618
 619 static int affs_write_begin_ofs(struct file *file, struct address_space *mapping,
 620                                 loff_t pos, unsigned len, unsigned flags,
 621                                 struct page **pagep, void **fsdata)
 622 {
 623         struct inode *inode = mapping->host;
 624         struct page *page;
 625         pgoff_t index;
 626         int err = 0;
 627
 628         pr_debug("AFFS: write_begin(%u, %llu, %llu)\n", (u32)inode->i_ino, (unsigned long long)pos, (unsigned long long)pos + len);
 629         if (pos > AFFS_I(inode)->mmu_private) {
 630                 /* XXX: this probably leaves a too-big i_size in case of
 631                  * failure. Should really be updating i_size at write_end time
 632                  */
 633                 err = affs_extent_file_ofs(inode, pos);
 634                 if (err)
 635                         return err;
 636         }
 637
 638         index = pos >> PAGE_CACHE_SHIFT;
 639         page = grab_cache_page_write_begin(mapping, index, flags);
 640         if (!page)
 641                 return -ENOMEM;
 642         *pagep = page;
 643
 644         if (PageUptodate(page))
 645                 return 0;
 646
 647         /* XXX: inefficient but safe in the face of short writes */
 648         err = affs_do_readpage_ofs(file, page, 0, PAGE_CACHE_SIZE);
 649         if (err) {
 650                 unlock_page(page);
 651                 page_cache_release(page);
 652         }
 653         return err;
 654 }
 655
 656 static int affs_write_end_ofs(struct file *file, struct address_space *mapping,
 657                                 loff_t pos, unsigned len, unsigned copied,
 658                                 struct page *page, void *fsdata)
 659 {
 660         struct inode *inode = mapping->host;
 661         struct super_block *sb = inode->i_sb;
 662         struct buffer_head *bh, *prev_bh;
 663         char *data;
 664         u32 bidx, boff, bsize;
 665         unsigned from, to;
 666         u32 tmp;
 667         int written;
 668
 669         from = pos & (PAGE_CACHE_SIZE - 1);
 670         to = pos + len;
 671         /*
 672          * XXX: not sure if this can handle short copies (len < copied), but
 673          * we don't have to, because the page should always be uptodate here,
 674          * due to write_begin.
 675          */
 676
 677         pr_debug("AFFS: write_begin(%u, %llu, %llu)\n", (u32)inode->i_ino, (unsigned long long)pos, (unsigned long long)pos + len);
 678         bsize = AFFS_SB(sb)->s_data_blksize;
 679         data = page_address(page);
 680
 681         bh = NULL;
 682         written = 0;
 683         tmp = (page->index << PAGE_CACHE_SHIFT) + from;
 684         bidx = tmp / bsize;
 685         boff = tmp % bsize;
 686         if (boff) {
 687                 bh = affs_bread_ino(inode, bidx, 0);
 688                 if (IS_ERR(bh))
 689                         return PTR_ERR(bh);
 690                 tmp = min(bsize - boff, to - from);
 691                 BUG_ON(boff + tmp > bsize || tmp > bsize);
 692                 memcpy(AFFS_DATA(bh) + boff, data + from, tmp);
 693                 be32_add_cpu(&AFFS_DATA_HEAD(bh)->size, tmp);
 694                 affs_fix_checksum(sb, bh);
 695                 mark_buffer_dirty_inode(bh, inode);
 696                 written += tmp;
 697                 from += tmp;
 698                 bidx++;
 699         } else if (bidx) {
 700                 bh = affs_bread_ino(inode, bidx - 1, 0);
 701                 if (IS_ERR(bh))
 702                         return PTR_ERR(bh);
 703         }
 704         while (from + bsize <= to) {
 705                 prev_bh = bh;
 706                 bh = affs_getemptyblk_ino(inode, bidx);
 707                 if (IS_ERR(bh))
 708                         goto out;
 709                 memcpy(AFFS_DATA(bh), data + from, bsize);
 710                 if (buffer_new(bh)) {
 711                         AFFS_DATA_HEAD(bh)->ptype = cpu_to_be32(T_DATA);
 712                         AFFS_DATA_HEAD(bh)->key = cpu_to_be32(inode->i_ino);
 713                         AFFS_DATA_HEAD(bh)->sequence = cpu_to_be32(bidx);
 714                         AFFS_DATA_HEAD(bh)->size = cpu_to_be32(bsize);
 715                         AFFS_DATA_HEAD(bh)->next = 0;
 716                         bh->b_state &= ~(1UL << BH_New);
 717                         if (prev_bh) {
 718                                 u32 tmp = be32_to_cpu(AFFS_DATA_HEAD(prev_bh)->next);
 719                                 if (tmp)
 720                                         affs_warning(sb, "commit_write_ofs", "next block already set for %d (%d)", bidx, tmp);
 721                                 AFFS_DATA_HEAD(prev_bh)->next = cpu_to_be32(bh->b_blocknr);
 722                                 affs_adjust_checksum(prev_bh, bh->b_blocknr - tmp);
 723                                 mark_buffer_dirty_inode(prev_bh, inode);
 724                         }
 725                 }
 726                 affs_brelse(prev_bh);
 727                 affs_fix_checksum(sb, bh);
 728                 mark_buffer_dirty_inode(bh, inode);
 729                 written += bsize;
 730                 from += bsize;
 731                 bidx++;
 732         }
 733         if (from < to) {
 734                 prev_bh = bh;
 735                 bh = affs_bread_ino(inode, bidx, 1);
 736                 if (IS_ERR(bh))
 737                         goto out;
 738                 tmp = min(bsize, to - from);
 739                 BUG_ON(tmp > bsize);
 740                 memcpy(AFFS_DATA(bh), data + from, tmp);
 741                 if (buffer_new(bh)) {
 742                         AFFS_DATA_HEAD(bh)->ptype = cpu_to_be32(T_DATA);
 743                         AFFS_DATA_HEAD(bh)->key = cpu_to_be32(inode->i_ino);
 744                         AFFS_DATA_HEAD(bh)->sequence = cpu_to_be32(bidx);
 745                         AFFS_DATA_HEAD(bh)->size = cpu_to_be32(tmp);
 746                         AFFS_DATA_HEAD(bh)->next = 0;
 747                         bh->b_state &= ~(1UL << BH_New);
 748                         if (prev_bh) {
 749                                 u32 tmp = be32_to_cpu(AFFS_DATA_HEAD(prev_bh)->next);
 750                                 if (tmp)
 751                                         affs_warning(sb, "commit_write_ofs", "next block already set for %d (%d)", bidx, tmp);
 752                                 AFFS_DATA_HEAD(prev_bh)->next = cpu_to_be32(bh->b_blocknr);
 753                                 affs_adjust_checksum(prev_bh, bh->b_blocknr - tmp);
 754                                 mark_buffer_dirty_inode(prev_bh, inode);
 755                         }
 756                 } else if (be32_to_cpu(AFFS_DATA_HEAD(bh)->size) < tmp)
 757                         AFFS_DATA_HEAD(bh)->size = cpu_to_be32(tmp);
 758                 affs_brelse(prev_bh);
 759                 affs_fix_checksum(sb, bh);
 760                 mark_buffer_dirty_inode(bh, inode);
 761                 written += tmp;
 762                 from += tmp;
 763                 bidx++;
 764         }
 765         SetPageUptodate(page);
 766
 767 done:
 768         affs_brelse(bh);
 769         tmp = (page->index << PAGE_CACHE_SHIFT) + from;
 770         if (tmp > inode->i_size)
 771                 inode->i_size = AFFS_I(inode)->mmu_private = tmp;
 772
 773         unlock_page(page);
 774         page_cache_release(page);
 775
 776         return written;
 777
 778 out:
 779         bh = prev_bh;
 780         if (!written)
 781                 written = PTR_ERR(bh);
 782         goto done;
 783 }
 784
 785 const struct address_space_operations affs_aops_ofs = {
 786         .readpage = affs_readpage_ofs,
 787         //.writepage = affs_writepage_ofs,
 788         .write_begin = affs_write_begin_ofs,
 789         .write_end = affs_write_end_ofs
 790 };
 791
 792 /* Free any preallocated blocks. */
 793
 794 void
 795 affs_free_prealloc(struct inode *inode)
 796 {
 797         struct super_block *sb = inode->i_sb;
 798
 799         pr_debug("AFFS: free_prealloc(ino=%lu)\n", inode->i_ino);
 800
 801         while (AFFS_I(inode)->i_pa_cnt) {
 802                 AFFS_I(inode)->i_pa_cnt--;
 803                 affs_free_block(sb, ++AFFS_I(inode)->i_lastalloc);
 804         }
 805 }
 806
 807 /* Truncate (or enlarge) a file to the requested size. */
 808
 809 void
 810 affs_truncate(struct inode *inode)
 811 {
 812         struct super_block *sb = inode->i_sb;
 813         u32 ext, ext_key;
 814         u32 last_blk, blkcnt, blk;
 815         u32 size;
 816         struct buffer_head *ext_bh;
 817         int i;
 818
 819         pr_debug("AFFS: truncate(inode=%d, oldsize=%u, newsize=%u)\n",
 820                  (u32)inode->i_ino, (u32)AFFS_I(inode)->mmu_private, (u32)inode->i_size);
 821
 822         last_blk = 0;
 823         ext = 0;
 824         if (inode->i_size) {
 825                 last_blk = ((u32)inode->i_size - 1) / AFFS_SB(sb)->s_data_blksize;
 826                 ext = last_blk / AFFS_SB(sb)->s_hashsize;
 827         }
 828
 829         if (inode->i_size > AFFS_I(inode)->mmu_private) {
 830                 struct address_space *mapping = inode->i_mapping;
 831                 struct page *page;
 832                 void *fsdata;
 833                 u32 size = inode->i_size;
 834                 int res;
 835
 836                 res = mapping->a_ops->write_begin(NULL, mapping, size, 0, 0, &page, &fsdata);
 837                 if (!res)
 838                         res = mapping->a_ops->write_end(NULL, mapping, size, 0, 0, page, fsdata);
 839                 else
 840                         inode->i_size = AFFS_I(inode)->mmu_private;
 841                 mark_inode_dirty(inode);
 842                 return;
 843         } else if (inode->i_size == AFFS_I(inode)->mmu_private)
 844                 return;
 845
 846         // lock cache
 847         ext_bh = affs_get_extblock(inode, ext);
 848         if (IS_ERR(ext_bh)) {
 849                 affs_warning(sb, "truncate", "unexpected read error for ext block %u (%d)",
 850                              ext, PTR_ERR(ext_bh));
 851                 return;
 852         }
 853         if (AFFS_I(inode)->i_lc) {
 854                 /* clear linear cache */
 855                 i = (ext + 1) >> AFFS_I(inode)->i_lc_shift;
 856                 if (AFFS_I(inode)->i_lc_size > i) {
 857                         AFFS_I(inode)->i_lc_size = i;
 858                         for (; i < AFFS_LC_SIZE; i++)
 859                                 AFFS_I(inode)->i_lc[i] = 0;
 860                 }
 861                 /* clear associative cache */
 862                 for (i = 0; i < AFFS_AC_SIZE; i++)
 863                         if (AFFS_I(inode)->i_ac[i].ext >= ext)
 864                                 AFFS_I(inode)->i_ac[i].ext = 0;
 865         }
 866         ext_key = be32_to_cpu(AFFS_TAIL(sb, ext_bh)->extension);
 867
 868         blkcnt = AFFS_I(inode)->i_blkcnt;
 869         i = 0;
 870         blk = last_blk;
 871         if (inode->i_size) {
 872                 i = last_blk % AFFS_SB(sb)->s_hashsize + 1;
 873                 blk++;
 874         } else
 875                 AFFS_HEAD(ext_bh)->first_data = 0;
 876         AFFS_HEAD(ext_bh)->block_count = cpu_to_be32(i);
 877         size = AFFS_SB(sb)->s_hashsize;
 878         if (size > blkcnt - blk + i)
 879                 size = blkcnt - blk + i;
 880         for (; i < size; i++, blk++) {
 881                 affs_free_block(sb, be32_to_cpu(AFFS_BLOCK(sb, ext_bh, i)));
 882                 AFFS_BLOCK(sb, ext_bh, i) = 0;
 883         }
 884         AFFS_TAIL(sb, ext_bh)->extension = 0;
 885         affs_fix_checksum(sb, ext_bh);
 886         mark_buffer_dirty_inode(ext_bh, inode);
 887         affs_brelse(ext_bh);
 888
 889         if (inode->i_size) {
 890                 AFFS_I(inode)->i_blkcnt = last_blk + 1;
 891                 AFFS_I(inode)->i_extcnt = ext + 1;
 892                 if (AFFS_SB(sb)->s_flags & SF_OFS) {
 893                         struct buffer_head *bh = affs_bread_ino(inode, last_blk, 0);
 894                         u32 tmp;
 895                         if (IS_ERR(bh)) {
 896                                 affs_warning(sb, "truncate", "unexpected read error for last block %u (%d)",
 897                                              ext, PTR_ERR(bh));
 898                                 return;
 899                         }
 900                         tmp = be32_to_cpu(AFFS_DATA_HEAD(bh)->next);
 901                         AFFS_DATA_HEAD(bh)->next = 0;
 902                         affs_adjust_checksum(bh, -tmp);
 903                         affs_brelse(bh);
 904                 }
 905         } else {
 906                 AFFS_I(inode)->i_blkcnt = 0;
 907                 AFFS_I(inode)->i_extcnt = 1;
 908         }
 909         AFFS_I(inode)->mmu_private = inode->i_size;
 910         // unlock cache
 911
 912         while (ext_key) {
 913                 ext_bh = affs_bread(sb, ext_key);
 914                 size = AFFS_SB(sb)->s_hashsize;
 915                 if (size > blkcnt - blk)
 916                         size = blkcnt - blk;
 917                 for (i = 0; i < size; i++, blk++)
 918                         affs_free_block(sb, be32_to_cpu(AFFS_BLOCK(sb, ext_bh, i)));
 919                 affs_free_block(sb, ext_key);
 920                 ext_key = be32_to_cpu(AFFS_TAIL(sb, ext_bh)->extension);
 921                 affs_brelse(ext_bh);
 922         }
 923         affs_free_prealloc(inode);
 924 }
 925
 926 int affs_file_fsync(struct file *filp, loff_t start, loff_t end, int datasync)
 927 {
 928         struct inode *inode = filp->f_mapping->host;
 929         int ret, err;
 930
 931         err = filemap_write_and_wait_range(inode->i_mapping, start, end);
 932         if (err)
 933                 return err;
 934
 935         mutex_lock(&inode->i_mutex);
 936         ret = write_inode_now(inode, 0);
 937         err = sync_blockdev(inode->i_sb->s_bdev);
 938         if (!ret)
 939                 ret = err;
 940         mutex_unlock(&inode->i_mutex);
 941         return ret;
 942 }