linux/fs/affs/file.c
<<
>>
Prefs
   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
  21static int affs_grow_extcache(struct inode *inode, u32 lc_idx);
  22static struct buffer_head *affs_alloc_extblock(struct inode *inode, struct buffer_head *bh, u32 ext);
  23static inline struct buffer_head *affs_get_extblock(struct inode *inode, u32 ext);
  24static struct buffer_head *affs_get_extblock_slow(struct inode *inode, u32 ext);
  25static int affs_file_open(struct inode *inode, struct file *filp);
  26static int affs_file_release(struct inode *inode, struct file *filp);
  27
  28const 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
  41const struct inode_operations affs_file_inode_operations = {
  42        .truncate       = affs_truncate,
  43        .setattr        = affs_notify_change,
  44};
  45
  46static int
  47affs_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
  55static int
  56affs_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
  72static int
  73affs_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
 137err:
 138        // lock cache
 139        return -EIO;
 140}
 141
 142static struct buffer_head *
 143affs_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
 180static inline struct buffer_head *
 181affs_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
 194static struct buffer_head *
 195affs_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
 241again:
 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];
 281find_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
 299read_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
 307store_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
 316err_bread:
 317        affs_brelse(bh);
 318        return ERR_PTR(-EIO);
 319}
 320
 321static int
 322affs_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
 379err_big:
 380        affs_error(inode->i_sb,"get_block","strange block request %d", block);
 381        return -EIO;
 382err_ext:
 383        // unlock cache
 384        affs_unlock_ext(inode);
 385        return PTR_ERR(ext_bh);
 386err_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
 395static int affs_writepage(struct page *page, struct writeback_control *wbc)
 396{
 397        return block_write_full_page(page, affs_get_block, wbc);
 398}
 399
 400static int affs_readpage(struct file *file, struct page *page)
 401{
 402        return block_read_full_page(page, affs_get_block);
 403}
 404
 405static 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
 424static sector_t _affs_bmap(struct address_space *mapping, sector_t block)
 425{
 426        return generic_block_bmap(mapping,block,affs_get_block);
 427}
 428
 429const struct address_space_operations affs_aops = {
 430        .readpage = affs_readpage,
 431        .writepage = affs_writepage,
 432        .sync_page = block_sync_page,
 433        .write_begin = affs_write_begin,
 434        .write_end = generic_write_end,
 435        .bmap = _affs_bmap
 436};
 437
 438static inline struct buffer_head *
 439affs_bread_ino(struct inode *inode, int block, int create)
 440{
 441        struct buffer_head *bh, tmp_bh;
 442        int err;
 443
 444        tmp_bh.b_state = 0;
 445        err = affs_get_block(inode, block, &tmp_bh, create);
 446        if (!err) {
 447                bh = affs_bread(inode->i_sb, tmp_bh.b_blocknr);
 448                if (bh) {
 449                        bh->b_state |= tmp_bh.b_state;
 450                        return bh;
 451                }
 452                err = -EIO;
 453        }
 454        return ERR_PTR(err);
 455}
 456
 457static inline struct buffer_head *
 458affs_getzeroblk_ino(struct inode *inode, int block)
 459{
 460        struct buffer_head *bh, tmp_bh;
 461        int err;
 462
 463        tmp_bh.b_state = 0;
 464        err = affs_get_block(inode, block, &tmp_bh, 1);
 465        if (!err) {
 466                bh = affs_getzeroblk(inode->i_sb, tmp_bh.b_blocknr);
 467                if (bh) {
 468                        bh->b_state |= tmp_bh.b_state;
 469                        return bh;
 470                }
 471                err = -EIO;
 472        }
 473        return ERR_PTR(err);
 474}
 475
 476static inline struct buffer_head *
 477affs_getemptyblk_ino(struct inode *inode, int block)
 478{
 479        struct buffer_head *bh, tmp_bh;
 480        int err;
 481
 482        tmp_bh.b_state = 0;
 483        err = affs_get_block(inode, block, &tmp_bh, 1);
 484        if (!err) {
 485                bh = affs_getemptyblk(inode->i_sb, tmp_bh.b_blocknr);
 486                if (bh) {
 487                        bh->b_state |= tmp_bh.b_state;
 488                        return bh;
 489                }
 490                err = -EIO;
 491        }
 492        return ERR_PTR(err);
 493}
 494
 495static int
 496affs_do_readpage_ofs(struct file *file, struct page *page, unsigned from, unsigned to)
 497{
 498        struct inode *inode = page->mapping->host;
 499        struct super_block *sb = inode->i_sb;
 500        struct buffer_head *bh;
 501        char *data;
 502        u32 bidx, boff, bsize;
 503        u32 tmp;
 504
 505        pr_debug("AFFS: read_page(%u, %ld, %d, %d)\n", (u32)inode->i_ino, page->index, from, to);
 506        BUG_ON(from > to || to > PAGE_CACHE_SIZE);
 507        kmap(page);
 508        data = page_address(page);
 509        bsize = AFFS_SB(sb)->s_data_blksize;
 510        tmp = (page->index << PAGE_CACHE_SHIFT) + from;
 511        bidx = tmp / bsize;
 512        boff = tmp % bsize;
 513
 514        while (from < to) {
 515                bh = affs_bread_ino(inode, bidx, 0);
 516                if (IS_ERR(bh))
 517                        return PTR_ERR(bh);
 518                tmp = min(bsize - boff, to - from);
 519                BUG_ON(from + tmp > to || tmp > bsize);
 520                memcpy(data + from, AFFS_DATA(bh) + boff, tmp);
 521                affs_brelse(bh);
 522                bidx++;
 523                from += tmp;
 524                boff = 0;
 525        }
 526        flush_dcache_page(page);
 527        kunmap(page);
 528        return 0;
 529}
 530
 531static int
 532affs_extent_file_ofs(struct inode *inode, u32 newsize)
 533{
 534        struct super_block *sb = inode->i_sb;
 535        struct buffer_head *bh, *prev_bh;
 536        u32 bidx, boff;
 537        u32 size, bsize;
 538        u32 tmp;
 539
 540        pr_debug("AFFS: extent_file(%u, %d)\n", (u32)inode->i_ino, newsize);
 541        bsize = AFFS_SB(sb)->s_data_blksize;
 542        bh = NULL;
 543        size = AFFS_I(inode)->mmu_private;
 544        bidx = size / bsize;
 545        boff = size % bsize;
 546        if (boff) {
 547                bh = affs_bread_ino(inode, bidx, 0);
 548                if (IS_ERR(bh))
 549                        return PTR_ERR(bh);
 550                tmp = min(bsize - boff, newsize - size);
 551                BUG_ON(boff + tmp > bsize || tmp > bsize);
 552                memset(AFFS_DATA(bh) + boff, 0, tmp);
 553                be32_add_cpu(&AFFS_DATA_HEAD(bh)->size, tmp);
 554                affs_fix_checksum(sb, bh);
 555                mark_buffer_dirty_inode(bh, inode);
 556                size += tmp;
 557                bidx++;
 558        } else if (bidx) {
 559                bh = affs_bread_ino(inode, bidx - 1, 0);
 560                if (IS_ERR(bh))
 561                        return PTR_ERR(bh);
 562        }
 563
 564        while (size < newsize) {
 565                prev_bh = bh;
 566                bh = affs_getzeroblk_ino(inode, bidx);
 567                if (IS_ERR(bh))
 568                        goto out;
 569                tmp = min(bsize, newsize - size);
 570                BUG_ON(tmp > bsize);
 571                AFFS_DATA_HEAD(bh)->ptype = cpu_to_be32(T_DATA);
 572                AFFS_DATA_HEAD(bh)->key = cpu_to_be32(inode->i_ino);
 573                AFFS_DATA_HEAD(bh)->sequence = cpu_to_be32(bidx);
 574                AFFS_DATA_HEAD(bh)->size = cpu_to_be32(tmp);
 575                affs_fix_checksum(sb, bh);
 576                bh->b_state &= ~(1UL << BH_New);
 577                mark_buffer_dirty_inode(bh, inode);
 578                if (prev_bh) {
 579                        u32 tmp = be32_to_cpu(AFFS_DATA_HEAD(prev_bh)->next);
 580                        if (tmp)
 581                                affs_warning(sb, "extent_file_ofs", "next block already set for %d (%d)", bidx, tmp);
 582                        AFFS_DATA_HEAD(prev_bh)->next = cpu_to_be32(bh->b_blocknr);
 583                        affs_adjust_checksum(prev_bh, bh->b_blocknr - tmp);
 584                        mark_buffer_dirty_inode(prev_bh, inode);
 585                        affs_brelse(prev_bh);
 586                }
 587                size += bsize;
 588                bidx++;
 589        }
 590        affs_brelse(bh);
 591        inode->i_size = AFFS_I(inode)->mmu_private = newsize;
 592        return 0;
 593
 594out:
 595        inode->i_size = AFFS_I(inode)->mmu_private = newsize;
 596        return PTR_ERR(bh);
 597}
 598
 599static int
 600affs_readpage_ofs(struct file *file, struct page *page)
 601{
 602        struct inode *inode = page->mapping->host;
 603        u32 to;
 604        int err;
 605
 606        pr_debug("AFFS: read_page(%u, %ld)\n", (u32)inode->i_ino, page->index);
 607        to = PAGE_CACHE_SIZE;
 608        if (((page->index + 1) << PAGE_CACHE_SHIFT) > inode->i_size) {
 609                to = inode->i_size & ~PAGE_CACHE_MASK;
 610                memset(page_address(page) + to, 0, PAGE_CACHE_SIZE - to);
 611        }
 612
 613        err = affs_do_readpage_ofs(file, page, 0, to);
 614        if (!err)
 615                SetPageUptodate(page);
 616        unlock_page(page);
 617        return err;
 618}
 619
 620static int affs_write_begin_ofs(struct file *file, struct address_space *mapping,
 621                                loff_t pos, unsigned len, unsigned flags,
 622                                struct page **pagep, void **fsdata)
 623{
 624        struct inode *inode = mapping->host;
 625        struct page *page;
 626        pgoff_t index;
 627        int err = 0;
 628
 629        pr_debug("AFFS: write_begin(%u, %llu, %llu)\n", (u32)inode->i_ino, (unsigned long long)pos, (unsigned long long)pos + len);
 630        if (pos > AFFS_I(inode)->mmu_private) {
 631                /* XXX: this probably leaves a too-big i_size in case of
 632                 * failure. Should really be updating i_size at write_end time
 633                 */
 634                err = affs_extent_file_ofs(inode, pos);
 635                if (err)
 636                        return err;
 637        }
 638
 639        index = pos >> PAGE_CACHE_SHIFT;
 640        page = grab_cache_page_write_begin(mapping, index, flags);
 641        if (!page)
 642                return -ENOMEM;
 643        *pagep = page;
 644
 645        if (PageUptodate(page))
 646                return 0;
 647
 648        /* XXX: inefficient but safe in the face of short writes */
 649        err = affs_do_readpage_ofs(file, page, 0, PAGE_CACHE_SIZE);
 650        if (err) {
 651                unlock_page(page);
 652                page_cache_release(page);
 653        }
 654        return err;
 655}
 656
 657static int affs_write_end_ofs(struct file *file, struct address_space *mapping,
 658                                loff_t pos, unsigned len, unsigned copied,
 659                                struct page *page, void *fsdata)
 660{
 661        struct inode *inode = mapping->host;
 662        struct super_block *sb = inode->i_sb;
 663        struct buffer_head *bh, *prev_bh;
 664        char *data;
 665        u32 bidx, boff, bsize;
 666        unsigned from, to;
 667        u32 tmp;
 668        int written;
 669
 670        from = pos & (PAGE_CACHE_SIZE - 1);
 671        to = pos + len;
 672        /*
 673         * XXX: not sure if this can handle short copies (len < copied), but
 674         * we don't have to, because the page should always be uptodate here,
 675         * due to write_begin.
 676         */
 677
 678        pr_debug("AFFS: write_begin(%u, %llu, %llu)\n", (u32)inode->i_ino, (unsigned long long)pos, (unsigned long long)pos + len);
 679        bsize = AFFS_SB(sb)->s_data_blksize;
 680        data = page_address(page);
 681
 682        bh = NULL;
 683        written = 0;
 684        tmp = (page->index << PAGE_CACHE_SHIFT) + from;
 685        bidx = tmp / bsize;
 686        boff = tmp % bsize;
 687        if (boff) {
 688                bh = affs_bread_ino(inode, bidx, 0);
 689                if (IS_ERR(bh))
 690                        return PTR_ERR(bh);
 691                tmp = min(bsize - boff, to - from);
 692                BUG_ON(boff + tmp > bsize || tmp > bsize);
 693                memcpy(AFFS_DATA(bh) + boff, data + from, tmp);
 694                be32_add_cpu(&AFFS_DATA_HEAD(bh)->size, tmp);
 695                affs_fix_checksum(sb, bh);
 696                mark_buffer_dirty_inode(bh, inode);
 697                written += tmp;
 698                from += tmp;
 699                bidx++;
 700        } else if (bidx) {
 701                bh = affs_bread_ino(inode, bidx - 1, 0);
 702                if (IS_ERR(bh))
 703                        return PTR_ERR(bh);
 704        }
 705        while (from + bsize <= to) {
 706                prev_bh = bh;
 707                bh = affs_getemptyblk_ino(inode, bidx);
 708                if (IS_ERR(bh))
 709                        goto out;
 710                memcpy(AFFS_DATA(bh), data + from, bsize);
 711                if (buffer_new(bh)) {
 712                        AFFS_DATA_HEAD(bh)->ptype = cpu_to_be32(T_DATA);
 713                        AFFS_DATA_HEAD(bh)->key = cpu_to_be32(inode->i_ino);
 714                        AFFS_DATA_HEAD(bh)->sequence = cpu_to_be32(bidx);
 715                        AFFS_DATA_HEAD(bh)->size = cpu_to_be32(bsize);
 716                        AFFS_DATA_HEAD(bh)->next = 0;
 717                        bh->b_state &= ~(1UL << BH_New);
 718                        if (prev_bh) {
 719                                u32 tmp = be32_to_cpu(AFFS_DATA_HEAD(prev_bh)->next);
 720                                if (tmp)
 721                                        affs_warning(sb, "commit_write_ofs", "next block already set for %d (%d)", bidx, tmp);
 722                                AFFS_DATA_HEAD(prev_bh)->next = cpu_to_be32(bh->b_blocknr);
 723                                affs_adjust_checksum(prev_bh, bh->b_blocknr - tmp);
 724                                mark_buffer_dirty_inode(prev_bh, inode);
 725                        }
 726                }
 727                affs_brelse(prev_bh);
 728                affs_fix_checksum(sb, bh);
 729                mark_buffer_dirty_inode(bh, inode);
 730                written += bsize;
 731                from += bsize;
 732                bidx++;
 733        }
 734        if (from < to) {
 735                prev_bh = bh;
 736                bh = affs_bread_ino(inode, bidx, 1);
 737                if (IS_ERR(bh))
 738                        goto out;
 739                tmp = min(bsize, to - from);
 740                BUG_ON(tmp > bsize);
 741                memcpy(AFFS_DATA(bh), data + from, tmp);
 742                if (buffer_new(bh)) {
 743                        AFFS_DATA_HEAD(bh)->ptype = cpu_to_be32(T_DATA);
 744                        AFFS_DATA_HEAD(bh)->key = cpu_to_be32(inode->i_ino);
 745                        AFFS_DATA_HEAD(bh)->sequence = cpu_to_be32(bidx);
 746                        AFFS_DATA_HEAD(bh)->size = cpu_to_be32(tmp);
 747                        AFFS_DATA_HEAD(bh)->next = 0;
 748                        bh->b_state &= ~(1UL << BH_New);
 749                        if (prev_bh) {
 750                                u32 tmp = be32_to_cpu(AFFS_DATA_HEAD(prev_bh)->next);
 751                                if (tmp)
 752                                        affs_warning(sb, "commit_write_ofs", "next block already set for %d (%d)", bidx, tmp);
 753                                AFFS_DATA_HEAD(prev_bh)->next = cpu_to_be32(bh->b_blocknr);
 754                                affs_adjust_checksum(prev_bh, bh->b_blocknr - tmp);
 755                                mark_buffer_dirty_inode(prev_bh, inode);
 756                        }
 757                } else if (be32_to_cpu(AFFS_DATA_HEAD(bh)->size) < tmp)
 758                        AFFS_DATA_HEAD(bh)->size = cpu_to_be32(tmp);
 759                affs_brelse(prev_bh);
 760                affs_fix_checksum(sb, bh);
 761                mark_buffer_dirty_inode(bh, inode);
 762                written += tmp;
 763                from += tmp;
 764                bidx++;
 765        }
 766        SetPageUptodate(page);
 767
 768done:
 769        affs_brelse(bh);
 770        tmp = (page->index << PAGE_CACHE_SHIFT) + from;
 771        if (tmp > inode->i_size)
 772                inode->i_size = AFFS_I(inode)->mmu_private = tmp;
 773
 774        unlock_page(page);
 775        page_cache_release(page);
 776
 777        return written;
 778
 779out:
 780        bh = prev_bh;
 781        if (!written)
 782                written = PTR_ERR(bh);
 783        goto done;
 784}
 785
 786const struct address_space_operations affs_aops_ofs = {
 787        .readpage = affs_readpage_ofs,
 788        //.writepage = affs_writepage_ofs,
 789        //.sync_page = affs_sync_page_ofs,
 790        .write_begin = affs_write_begin_ofs,
 791        .write_end = affs_write_end_ofs
 792};
 793
 794/* Free any preallocated blocks. */
 795
 796void
 797affs_free_prealloc(struct inode *inode)
 798{
 799        struct super_block *sb = inode->i_sb;
 800
 801        pr_debug("AFFS: free_prealloc(ino=%lu)\n", inode->i_ino);
 802
 803        while (AFFS_I(inode)->i_pa_cnt) {
 804                AFFS_I(inode)->i_pa_cnt--;
 805                affs_free_block(sb, ++AFFS_I(inode)->i_lastalloc);
 806        }
 807}
 808
 809/* Truncate (or enlarge) a file to the requested size. */
 810
 811void
 812affs_truncate(struct inode *inode)
 813{
 814        struct super_block *sb = inode->i_sb;
 815        u32 ext, ext_key;
 816        u32 last_blk, blkcnt, blk;
 817        u32 size;
 818        struct buffer_head *ext_bh;
 819        int i;
 820
 821        pr_debug("AFFS: truncate(inode=%d, oldsize=%u, newsize=%u)\n",
 822                 (u32)inode->i_ino, (u32)AFFS_I(inode)->mmu_private, (u32)inode->i_size);
 823
 824        last_blk = 0;
 825        ext = 0;
 826        if (inode->i_size) {
 827                last_blk = ((u32)inode->i_size - 1) / AFFS_SB(sb)->s_data_blksize;
 828                ext = last_blk / AFFS_SB(sb)->s_hashsize;
 829        }
 830
 831        if (inode->i_size > AFFS_I(inode)->mmu_private) {
 832                struct address_space *mapping = inode->i_mapping;
 833                struct page *page;
 834                void *fsdata;
 835                u32 size = inode->i_size;
 836                int res;
 837
 838                res = mapping->a_ops->write_begin(NULL, mapping, size, 0, 0, &page, &fsdata);
 839                if (!res)
 840                        res = mapping->a_ops->write_end(NULL, mapping, size, 0, 0, page, fsdata);
 841                else
 842                        inode->i_size = AFFS_I(inode)->mmu_private;
 843                mark_inode_dirty(inode);
 844                return;
 845        } else if (inode->i_size == AFFS_I(inode)->mmu_private)
 846                return;
 847
 848        // lock cache
 849        ext_bh = affs_get_extblock(inode, ext);
 850        if (IS_ERR(ext_bh)) {
 851                affs_warning(sb, "truncate", "unexpected read error for ext block %u (%d)",
 852                             ext, PTR_ERR(ext_bh));
 853                return;
 854        }
 855        if (AFFS_I(inode)->i_lc) {
 856                /* clear linear cache */
 857                i = (ext + 1) >> AFFS_I(inode)->i_lc_shift;
 858                if (AFFS_I(inode)->i_lc_size > i) {
 859                        AFFS_I(inode)->i_lc_size = i;
 860                        for (; i < AFFS_LC_SIZE; i++)
 861                                AFFS_I(inode)->i_lc[i] = 0;
 862                }
 863                /* clear associative cache */
 864                for (i = 0; i < AFFS_AC_SIZE; i++)
 865                        if (AFFS_I(inode)->i_ac[i].ext >= ext)
 866                                AFFS_I(inode)->i_ac[i].ext = 0;
 867        }
 868        ext_key = be32_to_cpu(AFFS_TAIL(sb, ext_bh)->extension);
 869
 870        blkcnt = AFFS_I(inode)->i_blkcnt;
 871        i = 0;
 872        blk = last_blk;
 873        if (inode->i_size) {
 874                i = last_blk % AFFS_SB(sb)->s_hashsize + 1;
 875                blk++;
 876        } else
 877                AFFS_HEAD(ext_bh)->first_data = 0;
 878        AFFS_HEAD(ext_bh)->block_count = cpu_to_be32(i);
 879        size = AFFS_SB(sb)->s_hashsize;
 880        if (size > blkcnt - blk + i)
 881                size = blkcnt - blk + i;
 882        for (; i < size; i++, blk++) {
 883                affs_free_block(sb, be32_to_cpu(AFFS_BLOCK(sb, ext_bh, i)));
 884                AFFS_BLOCK(sb, ext_bh, i) = 0;
 885        }
 886        AFFS_TAIL(sb, ext_bh)->extension = 0;
 887        affs_fix_checksum(sb, ext_bh);
 888        mark_buffer_dirty_inode(ext_bh, inode);
 889        affs_brelse(ext_bh);
 890
 891        if (inode->i_size) {
 892                AFFS_I(inode)->i_blkcnt = last_blk + 1;
 893                AFFS_I(inode)->i_extcnt = ext + 1;
 894                if (AFFS_SB(sb)->s_flags & SF_OFS) {
 895                        struct buffer_head *bh = affs_bread_ino(inode, last_blk, 0);
 896                        u32 tmp;
 897                        if (IS_ERR(bh)) {
 898                                affs_warning(sb, "truncate", "unexpected read error for last block %u (%d)",
 899                                             ext, PTR_ERR(bh));
 900                                return;
 901                        }
 902                        tmp = be32_to_cpu(AFFS_DATA_HEAD(bh)->next);
 903                        AFFS_DATA_HEAD(bh)->next = 0;
 904                        affs_adjust_checksum(bh, -tmp);
 905                        affs_brelse(bh);
 906                }
 907        } else {
 908                AFFS_I(inode)->i_blkcnt = 0;
 909                AFFS_I(inode)->i_extcnt = 1;
 910        }
 911        AFFS_I(inode)->mmu_private = inode->i_size;
 912        // unlock cache
 913
 914        while (ext_key) {
 915                ext_bh = affs_bread(sb, ext_key);
 916                size = AFFS_SB(sb)->s_hashsize;
 917                if (size > blkcnt - blk)
 918                        size = blkcnt - blk;
 919                for (i = 0; i < size; i++, blk++)
 920                        affs_free_block(sb, be32_to_cpu(AFFS_BLOCK(sb, ext_bh, i)));
 921                affs_free_block(sb, ext_key);
 922                ext_key = be32_to_cpu(AFFS_TAIL(sb, ext_bh)->extension);
 923                affs_brelse(ext_bh);
 924        }
 925        affs_free_prealloc(inode);
 926}
 927
 928int affs_file_fsync(struct file *filp, int datasync)
 929{
 930        struct inode *inode = filp->f_mapping->host;
 931        int ret, err;
 932
 933        ret = write_inode_now(inode, 0);
 934        err = sync_blockdev(inode->i_sb->s_bdev);
 935        if (!ret)
 936                ret = err;
 937        return ret;
 938}
 939