fs/logfs/readwrite.c

   1 /*
   2  * fs/logfs/readwrite.c
   3  *
   4  * As should be obvious for Linux kernel code, license is GPLv2
   5  *
   6  * Copyright (c) 2005-2008 Joern Engel <joern@logfs.org>
   7  *
   8  *
   9  * Actually contains five sets of very similar functions:
  10  * read         read blocks from a file
  11  * seek_hole    find next hole
  12  * seek_data    find next data block
  13  * valid        check whether a block still belongs to a file
  14  * write        write blocks to a file
  15  * delete       delete a block (for directories and ifile)
  16  * rewrite      move existing blocks of a file to a new location (gc helper)
  17  * truncate     truncate a file
  18  */
  19 #include "logfs.h"
  20 #include <linux/sched.h>
  21 #include <linux/slab.h>
  22
  23 static u64 adjust_bix(u64 bix, level_t level)
  24 {
  25         switch (level) {
  26         case 0:
  27                 return bix;
  28         case LEVEL(1):
  29                 return max_t(u64, bix, I0_BLOCKS);
  30         case LEVEL(2):
  31                 return max_t(u64, bix, I1_BLOCKS);
  32         case LEVEL(3):
  33                 return max_t(u64, bix, I2_BLOCKS);
  34         case LEVEL(4):
  35                 return max_t(u64, bix, I3_BLOCKS);
  36         case LEVEL(5):
  37                 return max_t(u64, bix, I4_BLOCKS);
  38         default:
  39                 WARN_ON(1);
  40                 return bix;
  41         }
  42 }
  43
  44 static inline u64 maxbix(u8 height)
  45 {
  46         return 1ULL << (LOGFS_BLOCK_BITS * height);
  47 }
  48
  49 /**
  50  * The inode address space is cut in two halves.  Lower half belongs to data
  51  * pages, upper half to indirect blocks.  If the high bit (INDIRECT_BIT) is
  52  * set, the actual block index (bix) and level can be derived from the page
  53  * index.
  54  *
  55  * The lowest three bits of the block index are set to 0 after packing and
  56  * unpacking.  Since the lowest n bits (9 for 4KiB blocksize) are ignored
  57  * anyway this is harmless.
  58  */
  59 #define ARCH_SHIFT      (BITS_PER_LONG - 32)
  60 #define INDIRECT_BIT    (0x80000000UL << ARCH_SHIFT)
  61 #define LEVEL_SHIFT     (28 + ARCH_SHIFT)
  62 static inline pgoff_t first_indirect_block(void)
  63 {
  64         return INDIRECT_BIT | (1ULL << LEVEL_SHIFT);
  65 }
  66
  67 pgoff_t logfs_pack_index(u64 bix, level_t level)
  68 {
  69         pgoff_t index;
  70
  71         BUG_ON(bix >= INDIRECT_BIT);
  72         if (level == 0)
  73                 return bix;
  74
  75         index  = INDIRECT_BIT;
  76         index |= (__force long)level << LEVEL_SHIFT;
  77         index |= bix >> ((__force u8)level * LOGFS_BLOCK_BITS);
  78         return index;
  79 }
  80
  81 void logfs_unpack_index(pgoff_t index, u64 *bix, level_t *level)
  82 {
  83         u8 __level;
  84
  85         if (!(index & INDIRECT_BIT)) {
  86                 *bix = index;
  87                 *level = 0;
  88                 return;
  89         }
  90
  91         __level = (index & ~INDIRECT_BIT) >> LEVEL_SHIFT;
  92         *level = LEVEL(__level);
  93         *bix = (index << (__level * LOGFS_BLOCK_BITS)) & ~INDIRECT_BIT;
  94         *bix = adjust_bix(*bix, *level);
  95         return;
  96 }
  97 #undef ARCH_SHIFT
  98 #undef INDIRECT_BIT
  99 #undef LEVEL_SHIFT
 100
 101 /*
 102  * Time is stored as nanoseconds since the epoch.
 103  */
 104 static struct timespec be64_to_timespec(__be64 betime)
 105 {
 106         return ns_to_timespec(be64_to_cpu(betime));
 107 }
 108
 109 static __be64 timespec_to_be64(struct timespec tsp)
 110 {
 111         return cpu_to_be64((u64)tsp.tv_sec * NSEC_PER_SEC + tsp.tv_nsec);
 112 }
 113
 114 static void logfs_disk_to_inode(struct logfs_disk_inode *di, struct inode*inode)
 115 {
 116         struct logfs_inode *li = logfs_inode(inode);
 117         int i;
 118
 119         inode->i_mode   = be16_to_cpu(di->di_mode);
 120         li->li_height   = di->di_height;
 121         li->li_flags    = be32_to_cpu(di->di_flags);
 122         i_uid_write(inode, be32_to_cpu(di->di_uid));
 123         i_gid_write(inode, be32_to_cpu(di->di_gid));
 124         inode->i_size   = be64_to_cpu(di->di_size);
 125         logfs_set_blocks(inode, be64_to_cpu(di->di_used_bytes));
 126         inode->i_atime  = be64_to_timespec(di->di_atime);
 127         inode->i_ctime  = be64_to_timespec(di->di_ctime);
 128         inode->i_mtime  = be64_to_timespec(di->di_mtime);
 129         set_nlink(inode, be32_to_cpu(di->di_refcount));
 130         inode->i_generation = be32_to_cpu(di->di_generation);
 131
 132         switch (inode->i_mode & S_IFMT) {
 133         case S_IFSOCK:  /* fall through */
 134         case S_IFBLK:   /* fall through */
 135         case S_IFCHR:   /* fall through */
 136         case S_IFIFO:
 137                 inode->i_rdev = be64_to_cpu(di->di_data[0]);
 138                 break;
 139         case S_IFDIR:   /* fall through */
 140         case S_IFREG:   /* fall through */
 141         case S_IFLNK:
 142                 for (i = 0; i < LOGFS_EMBEDDED_FIELDS; i++)
 143                         li->li_data[i] = be64_to_cpu(di->di_data[i]);
 144                 break;
 145         default:
 146                 BUG();
 147         }
 148 }
 149
 150 static void logfs_inode_to_disk(struct inode *inode, struct logfs_disk_inode*di)
 151 {
 152         struct logfs_inode *li = logfs_inode(inode);
 153         int i;
 154
 155         di->di_mode     = cpu_to_be16(inode->i_mode);
 156         di->di_height   = li->li_height;
 157         di->di_pad      = 0;
 158         di->di_flags    = cpu_to_be32(li->li_flags);
 159         di->di_uid      = cpu_to_be32(i_uid_read(inode));
 160         di->di_gid      = cpu_to_be32(i_gid_read(inode));
 161         di->di_size     = cpu_to_be64(i_size_read(inode));
 162         di->di_used_bytes = cpu_to_be64(li->li_used_bytes);
 163         di->di_atime    = timespec_to_be64(inode->i_atime);
 164         di->di_ctime    = timespec_to_be64(inode->i_ctime);
 165         di->di_mtime    = timespec_to_be64(inode->i_mtime);
 166         di->di_refcount = cpu_to_be32(inode->i_nlink);
 167         di->di_generation = cpu_to_be32(inode->i_generation);
 168
 169         switch (inode->i_mode & S_IFMT) {
 170         case S_IFSOCK:  /* fall through */
 171         case S_IFBLK:   /* fall through */
 172         case S_IFCHR:   /* fall through */
 173         case S_IFIFO:
 174                 di->di_data[0] = cpu_to_be64(inode->i_rdev);
 175                 break;
 176         case S_IFDIR:   /* fall through */
 177         case S_IFREG:   /* fall through */
 178         case S_IFLNK:
 179                 for (i = 0; i < LOGFS_EMBEDDED_FIELDS; i++)
 180                         di->di_data[i] = cpu_to_be64(li->li_data[i]);
 181                 break;
 182         default:
 183                 BUG();
 184         }
 185 }
 186
 187 static void __logfs_set_blocks(struct inode *inode)
 188 {
 189         struct super_block *sb = inode->i_sb;
 190         struct logfs_inode *li = logfs_inode(inode);
 191
 192         inode->i_blocks = ULONG_MAX;
 193         if (li->li_used_bytes >> sb->s_blocksize_bits < ULONG_MAX)
 194                 inode->i_blocks = ALIGN(li->li_used_bytes, 512) >> 9;
 195 }
 196
 197 void logfs_set_blocks(struct inode *inode, u64 bytes)
 198 {
 199         struct logfs_inode *li = logfs_inode(inode);
 200
 201         li->li_used_bytes = bytes;
 202         __logfs_set_blocks(inode);
 203 }
 204
 205 static void prelock_page(struct super_block *sb, struct page *page, int lock)
 206 {
 207         struct logfs_super *super = logfs_super(sb);
 208
 209         BUG_ON(!PageLocked(page));
 210         if (lock) {
 211                 BUG_ON(PagePreLocked(page));
 212                 SetPagePreLocked(page);
 213         } else {
 214                 /* We are in GC path. */
 215                 if (PagePreLocked(page))
 216                         super->s_lock_count++;
 217                 else
 218                         SetPagePreLocked(page);
 219         }
 220 }
 221
 222 static void preunlock_page(struct super_block *sb, struct page *page, int lock)
 223 {
 224         struct logfs_super *super = logfs_super(sb);
 225
 226         BUG_ON(!PageLocked(page));
 227         if (lock)
 228                 ClearPagePreLocked(page);
 229         else {
 230                 /* We are in GC path. */
 231                 BUG_ON(!PagePreLocked(page));
 232                 if (super->s_lock_count)
 233                         super->s_lock_count--;
 234                 else
 235                         ClearPagePreLocked(page);
 236         }
 237 }
 238
 239 /*
 240  * Logfs is prone to an AB-BA deadlock where one task tries to acquire
 241  * s_write_mutex with a locked page and GC tries to get that page while holding
 242  * s_write_mutex.
 243  * To solve this issue logfs will ignore the page lock iff the page in question
 244  * is waiting for s_write_mutex.  We annotate this fact by setting PG_pre_locked
 245  * in addition to PG_locked.
 246  */
 247 void logfs_get_wblocks(struct super_block *sb, struct page *page, int lock)
 248 {
 249         struct logfs_super *super = logfs_super(sb);
 250
 251         if (page)
 252                 prelock_page(sb, page, lock);
 253
 254         if (lock) {
 255                 mutex_lock(&super->s_write_mutex);
 256                 logfs_gc_pass(sb);
 257                 /* FIXME: We also have to check for shadowed space
 258                  * and mempool fill grade */
 259         }
 260 }
 261
 262 void logfs_put_wblocks(struct super_block *sb, struct page *page, int lock)
 263 {
 264         struct logfs_super *super = logfs_super(sb);
 265
 266         if (page)
 267                 preunlock_page(sb, page, lock);
 268         /* Order matters - we must clear PG_pre_locked before releasing
 269          * s_write_mutex or we could race against another task. */
 270         if (lock)
 271                 mutex_unlock(&super->s_write_mutex);
 272 }
 273
 274 static struct page *logfs_get_read_page(struct inode *inode, u64 bix,
 275                 level_t level)
 276 {
 277         return find_or_create_page(inode->i_mapping,
 278                         logfs_pack_index(bix, level), GFP_NOFS);
 279 }
 280
 281 static void logfs_put_read_page(struct page *page)
 282 {
 283         unlock_page(page);
 284         page_cache_release(page);
 285 }
 286
 287 static void logfs_lock_write_page(struct page *page)
 288 {
 289         int loop = 0;
 290
 291         while (unlikely(!trylock_page(page))) {
 292                 if (loop++ > 0x1000) {
 293                         /* Has been observed once so far... */
 294                         printk(KERN_ERR "stack at %p\n", &loop);
 295                         BUG();
 296                 }
 297                 if (PagePreLocked(page)) {
 298                         /* Holder of page lock is waiting for us, it
 299                          * is safe to use this page. */
 300                         break;
 301                 }
 302                 /* Some other process has this page locked and has
 303                  * nothing to do with us.  Wait for it to finish.
 304                  */
 305                 schedule();
 306         }
 307         BUG_ON(!PageLocked(page));
 308 }
 309
 310 static struct page *logfs_get_write_page(struct inode *inode, u64 bix,
 311                 level_t level)
 312 {
 313         struct address_space *mapping = inode->i_mapping;
 314         pgoff_t index = logfs_pack_index(bix, level);
 315         struct page *page;
 316         int err;
 317
 318 repeat:
 319         page = find_get_page(mapping, index);
 320         if (!page) {
 321                 page = __page_cache_alloc(GFP_NOFS);
 322                 if (!page)
 323                         return NULL;
 324                 err = add_to_page_cache_lru(page, mapping, index, GFP_NOFS);
 325                 if (unlikely(err)) {
 326                         page_cache_release(page);
 327                         if (err == -EEXIST)
 328                                 goto repeat;
 329                         return NULL;
 330                 }
 331         } else logfs_lock_write_page(page);
 332         BUG_ON(!PageLocked(page));
 333         return page;
 334 }
 335
 336 static void logfs_unlock_write_page(struct page *page)
 337 {
 338         if (!PagePreLocked(page))
 339                 unlock_page(page);
 340 }
 341
 342 static void logfs_put_write_page(struct page *page)
 343 {
 344         logfs_unlock_write_page(page);
 345         page_cache_release(page);
 346 }
 347
 348 static struct page *logfs_get_page(struct inode *inode, u64 bix, level_t level,
 349                 int rw)
 350 {
 351         if (rw == READ)
 352                 return logfs_get_read_page(inode, bix, level);
 353         else
 354                 return logfs_get_write_page(inode, bix, level);
 355 }
 356
 357 static void logfs_put_page(struct page *page, int rw)
 358 {
 359         if (rw == READ)
 360                 logfs_put_read_page(page);
 361         else
 362                 logfs_put_write_page(page);
 363 }
 364
 365 static unsigned long __get_bits(u64 val, int skip, int no)
 366 {
 367         u64 ret = val;
 368
 369         ret >>= skip * no;
 370         ret <<= 64 - no;
 371         ret >>= 64 - no;
 372         return ret;
 373 }
 374
 375 static unsigned long get_bits(u64 val, level_t skip)
 376 {
 377         return __get_bits(val, (__force int)skip, LOGFS_BLOCK_BITS);
 378 }
 379
 380 static inline void init_shadow_tree(struct super_block *sb,
 381                 struct shadow_tree *tree)
 382 {
 383         struct logfs_super *super = logfs_super(sb);
 384
 385         btree_init_mempool64(&tree->new, super->s_btree_pool);
 386         btree_init_mempool64(&tree->old, super->s_btree_pool);
 387 }
 388
 389 static void indirect_write_block(struct logfs_block *block)
 390 {
 391         struct page *page;
 392         struct inode *inode;
 393         int ret;
 394
 395         page = block->page;
 396         inode = page->mapping->host;
 397         logfs_lock_write_page(page);
 398         ret = logfs_write_buf(inode, page, 0);
 399         logfs_unlock_write_page(page);
 400         /*
 401          * This needs some rework.  Unless you want your filesystem to run
 402          * completely synchronously (you don't), the filesystem will always
 403          * report writes as 'successful' before the actual work has been
 404          * done.  The actual work gets done here and this is where any errors
 405          * will show up.  And there isn't much we can do about it, really.
 406          *
 407          * Some attempts to fix the errors (move from bad blocks, retry io,...)
 408          * have already been done, so anything left should be either a broken
 409          * device or a bug somewhere in logfs itself.  Being relatively new,
 410          * the odds currently favor a bug, so for now the line below isn't
 411          * entirely tasteles.
 412          */
 413         BUG_ON(ret);
 414 }
 415
 416 static void inode_write_block(struct logfs_block *block)
 417 {
 418         struct inode *inode;
 419         int ret;
 420
 421         inode = block->inode;
 422         if (inode->i_ino == LOGFS_INO_MASTER)
 423                 logfs_write_anchor(inode->i_sb);
 424         else {
 425                 ret = __logfs_write_inode(inode, NULL, 0);
 426                 /* see indirect_write_block comment */
 427                 BUG_ON(ret);
 428         }
 429 }
 430
 431 /*
 432  * This silences a false, yet annoying gcc warning.  I hate it when my editor
 433  * jumps into bitops.h each time I recompile this file.
 434  * TODO: Complain to gcc folks about this and upgrade compiler.
 435  */
 436 static unsigned long fnb(const unsigned long *addr,
 437                 unsigned long size, unsigned long offset)
 438 {
 439         return find_next_bit(addr, size, offset);
 440 }
 441
 442 static __be64 inode_val0(struct inode *inode)
 443 {
 444         struct logfs_inode *li = logfs_inode(inode);
 445         u64 val;
 446
 447         /*
 448          * Explicit shifting generates good code, but must match the format
 449          * of the structure.  Add some paranoia just in case.
 450          */
 451         BUILD_BUG_ON(offsetof(struct logfs_disk_inode, di_mode) != 0);
 452         BUILD_BUG_ON(offsetof(struct logfs_disk_inode, di_height) != 2);
 453         BUILD_BUG_ON(offsetof(struct logfs_disk_inode, di_flags) != 4);
 454
 455         val =   (u64)inode->i_mode << 48 |
 456                 (u64)li->li_height << 40 |
 457                 (u64)li->li_flags;
 458         return cpu_to_be64(val);
 459 }
 460
 461 static int inode_write_alias(struct super_block *sb,
 462                 struct logfs_block *block, write_alias_t *write_one_alias)
 463 {
 464         struct inode *inode = block->inode;
 465         struct logfs_inode *li = logfs_inode(inode);
 466         unsigned long pos;
 467         u64 ino , bix;
 468         __be64 val;
 469         level_t level;
 470         int err;
 471
 472         for (pos = 0; ; pos++) {
 473                 pos = fnb(block->alias_map, LOGFS_BLOCK_FACTOR, pos);
 474                 if (pos >= LOGFS_EMBEDDED_FIELDS + INODE_POINTER_OFS)
 475                         return 0;
 476
 477                 switch (pos) {
 478                 case INODE_HEIGHT_OFS:
 479                         val = inode_val0(inode);
 480                         break;
 481                 case INODE_USED_OFS:
 482                         val = cpu_to_be64(li->li_used_bytes);
 483                         break;
 484                 case INODE_SIZE_OFS:
 485                         val = cpu_to_be64(i_size_read(inode));
 486                         break;
 487                 case INODE_POINTER_OFS ... INODE_POINTER_OFS + LOGFS_EMBEDDED_FIELDS - 1:
 488                         val = cpu_to_be64(li->li_data[pos - INODE_POINTER_OFS]);
 489                         break;
 490                 default:
 491                         BUG();
 492                 }
 493
 494                 ino = LOGFS_INO_MASTER;
 495                 bix = inode->i_ino;
 496                 level = LEVEL(0);
 497                 err = write_one_alias(sb, ino, bix, level, pos, val);
 498                 if (err)
 499                         return err;
 500         }
 501 }
 502
 503 static int indirect_write_alias(struct super_block *sb,
 504                 struct logfs_block *block, write_alias_t *write_one_alias)
 505 {
 506         unsigned long pos;
 507         struct page *page = block->page;
 508         u64 ino , bix;
 509         __be64 *child, val;
 510         level_t level;
 511         int err;
 512
 513         for (pos = 0; ; pos++) {
 514                 pos = fnb(block->alias_map, LOGFS_BLOCK_FACTOR, pos);
 515                 if (pos >= LOGFS_BLOCK_FACTOR)
 516                         return 0;
 517
 518                 ino = page->mapping->host->i_ino;
 519                 logfs_unpack_index(page->index, &bix, &level);
 520                 child = kmap_atomic(page);
 521                 val = child[pos];
 522                 kunmap_atomic(child);
 523                 err = write_one_alias(sb, ino, bix, level, pos, val);
 524                 if (err)
 525                         return err;
 526         }
 527 }
 528
 529 int logfs_write_obj_aliases_pagecache(struct super_block *sb)
 530 {
 531         struct logfs_super *super = logfs_super(sb);
 532         struct logfs_block *block;
 533         int err;
 534
 535         list_for_each_entry(block, &super->s_object_alias, alias_list) {
 536                 err = block->ops->write_alias(sb, block, write_alias_journal);
 537                 if (err)
 538                         return err;
 539         }
 540         return 0;
 541 }
 542
 543 void __free_block(struct super_block *sb, struct logfs_block *block)
 544 {
 545         BUG_ON(!list_empty(&block->item_list));
 546         list_del(&block->alias_list);
 547         mempool_free(block, logfs_super(sb)->s_block_pool);
 548 }
 549
 550 static void inode_free_block(struct super_block *sb, struct logfs_block *block)
 551 {
 552         struct inode *inode = block->inode;
 553
 554         logfs_inode(inode)->li_block = NULL;
 555         __free_block(sb, block);
 556 }
 557
 558 static void indirect_free_block(struct super_block *sb,
 559                 struct logfs_block *block)
 560 {
 561         struct page *page = block->page;
 562
 563         if (PagePrivate(page)) {
 564                 ClearPagePrivate(page);
 565                 page_cache_release(page);
 566                 set_page_private(page, 0);
 567         }
 568         __free_block(sb, block);
 569 }
 570
 571
 572 static struct logfs_block_ops inode_block_ops = {
 573         .write_block = inode_write_block,
 574         .free_block = inode_free_block,
 575         .write_alias = inode_write_alias,
 576 };
 577
 578 struct logfs_block_ops indirect_block_ops = {
 579         .write_block = indirect_write_block,
 580         .free_block = indirect_free_block,
 581         .write_alias = indirect_write_alias,
 582 };
 583
 584 struct logfs_block *__alloc_block(struct super_block *sb,
 585                 u64 ino, u64 bix, level_t level)
 586 {
 587         struct logfs_super *super = logfs_super(sb);
 588         struct logfs_block *block;
 589
 590         block = mempool_alloc(super->s_block_pool, GFP_NOFS);
 591         memset(block, 0, sizeof(*block));
 592         INIT_LIST_HEAD(&block->alias_list);
 593         INIT_LIST_HEAD(&block->item_list);
 594         block->sb = sb;
 595         block->ino = ino;
 596         block->bix = bix;
 597         block->level = level;
 598         return block;
 599 }
 600
 601 static void alloc_inode_block(struct inode *inode)
 602 {
 603         struct logfs_inode *li = logfs_inode(inode);
 604         struct logfs_block *block;
 605
 606         if (li->li_block)
 607                 return;
 608
 609         block = __alloc_block(inode->i_sb, LOGFS_INO_MASTER, inode->i_ino, 0);
 610         block->inode = inode;
 611         li->li_block = block;
 612         block->ops = &inode_block_ops;
 613 }
 614
 615 void initialize_block_counters(struct page *page, struct logfs_block *block,
 616                 __be64 *array, int page_is_empty)
 617 {
 618         u64 ptr;
 619         int i, start;
 620
 621         block->partial = 0;
 622         block->full = 0;
 623         start = 0;
 624         if (page->index < first_indirect_block()) {
 625                 /* Counters are pointless on level 0 */
 626                 return;
 627         }
 628         if (page->index == first_indirect_block()) {
 629                 /* Skip unused pointers */
 630                 start = I0_BLOCKS;
 631                 block->full = I0_BLOCKS;
 632         }
 633         if (!page_is_empty) {
 634                 for (i = start; i < LOGFS_BLOCK_FACTOR; i++) {
 635                         ptr = be64_to_cpu(array[i]);
 636                         if (ptr)
 637                                 block->partial++;
 638                         if (ptr & LOGFS_FULLY_POPULATED)
 639                                 block->full++;
 640                 }
 641         }
 642 }
 643
 644 static void alloc_data_block(struct inode *inode, struct page *page)
 645 {
 646         struct logfs_block *block;
 647         u64 bix;
 648         level_t level;
 649
 650         if (PagePrivate(page))
 651                 return;
 652
 653         logfs_unpack_index(page->index, &bix, &level);
 654         block = __alloc_block(inode->i_sb, inode->i_ino, bix, level);
 655         block->page = page;
 656
 657         SetPagePrivate(page);
 658         page_cache_get(page);
 659         set_page_private(page, (unsigned long) block);
 660
 661         block->ops = &indirect_block_ops;
 662 }
 663
 664 static void alloc_indirect_block(struct inode *inode, struct page *page,
 665                 int page_is_empty)
 666 {
 667         struct logfs_block *block;
 668         __be64 *array;
 669
 670         if (PagePrivate(page))
 671                 return;
 672
 673         alloc_data_block(inode, page);
 674
 675         block = logfs_block(page);
 676         array = kmap_atomic(page);
 677         initialize_block_counters(page, block, array, page_is_empty);
 678         kunmap_atomic(array);
 679 }
 680
 681 static void block_set_pointer(struct page *page, int index, u64 ptr)
 682 {
 683         struct logfs_block *block = logfs_block(page);
 684         __be64 *array;
 685         u64 oldptr;
 686
 687         BUG_ON(!block);
 688         array = kmap_atomic(page);
 689         oldptr = be64_to_cpu(array[index]);
 690         array[index] = cpu_to_be64(ptr);
 691         kunmap_atomic(array);
 692         SetPageUptodate(page);
 693
 694         block->full += !!(ptr & LOGFS_FULLY_POPULATED)
 695                 - !!(oldptr & LOGFS_FULLY_POPULATED);
 696         block->partial += !!ptr - !!oldptr;
 697 }
 698
 699 static u64 block_get_pointer(struct page *page, int index)
 700 {
 701         __be64 *block;
 702         u64 ptr;
 703
 704         block = kmap_atomic(page);
 705         ptr = be64_to_cpu(block[index]);
 706         kunmap_atomic(block);
 707         return ptr;
 708 }
 709
 710 static int logfs_read_empty(struct page *page)
 711 {
 712         zero_user_segment(page, 0, PAGE_CACHE_SIZE);
 713         return 0;
 714 }
 715
 716 static int logfs_read_direct(struct inode *inode, struct page *page)
 717 {
 718         struct logfs_inode *li = logfs_inode(inode);
 719         pgoff_t index = page->index;
 720         u64 block;
 721
 722         block = li->li_data[index];
 723         if (!block)
 724                 return logfs_read_empty(page);
 725
 726         return logfs_segment_read(inode, page, block, index, 0);
 727 }
 728
 729 static int logfs_read_loop(struct inode *inode, struct page *page,
 730                 int rw_context)
 731 {
 732         struct logfs_inode *li = logfs_inode(inode);
 733         u64 bix, bofs = li->li_data[INDIRECT_INDEX];
 734         level_t level, target_level;
 735         int ret;
 736         struct page *ipage;
 737
 738         logfs_unpack_index(page->index, &bix, &target_level);
 739         if (!bofs)
 740                 return logfs_read_empty(page);
 741
 742         if (bix >= maxbix(li->li_height))
 743                 return logfs_read_empty(page);
 744
 745         for (level = LEVEL(li->li_height);
 746                         (__force u8)level > (__force u8)target_level;
 747                         level = SUBLEVEL(level)){
 748                 ipage = logfs_get_page(inode, bix, level, rw_context);
 749                 if (!ipage)
 750                         return -ENOMEM;
 751
 752                 ret = logfs_segment_read(inode, ipage, bofs, bix, level);
 753                 if (ret) {
 754                         logfs_put_read_page(ipage);
 755                         return ret;
 756                 }
 757
 758                 bofs = block_get_pointer(ipage, get_bits(bix, SUBLEVEL(level)));
 759                 logfs_put_page(ipage, rw_context);
 760                 if (!bofs)
 761                         return logfs_read_empty(page);
 762         }
 763
 764         return logfs_segment_read(inode, page, bofs, bix, 0);
 765 }
 766
 767 static int logfs_read_block(struct inode *inode, struct page *page,
 768                 int rw_context)
 769 {
 770         pgoff_t index = page->index;
 771
 772         if (index < I0_BLOCKS)
 773                 return logfs_read_direct(inode, page);
 774         return logfs_read_loop(inode, page, rw_context);
 775 }
 776
 777 static int logfs_exist_loop(struct inode *inode, u64 bix)
 778 {
 779         struct logfs_inode *li = logfs_inode(inode);
 780         u64 bofs = li->li_data[INDIRECT_INDEX];
 781         level_t level;
 782         int ret;
 783         struct page *ipage;
 784
 785         if (!bofs)
 786                 return 0;
 787         if (bix >= maxbix(li->li_height))
 788                 return 0;
 789
 790         for (level = LEVEL(li->li_height); level != 0; level = SUBLEVEL(level)) {
 791                 ipage = logfs_get_read_page(inode, bix, level);
 792                 if (!ipage)
 793                         return -ENOMEM;
 794
 795                 ret = logfs_segment_read(inode, ipage, bofs, bix, level);
 796                 if (ret) {
 797                         logfs_put_read_page(ipage);
 798                         return ret;
 799                 }
 800
 801                 bofs = block_get_pointer(ipage, get_bits(bix, SUBLEVEL(level)));
 802                 logfs_put_read_page(ipage);
 803                 if (!bofs)
 804                         return 0;
 805         }
 806
 807         return 1;
 808 }
 809
 810 int logfs_exist_block(struct inode *inode, u64 bix)
 811 {
 812         struct logfs_inode *li = logfs_inode(inode);
 813
 814         if (bix < I0_BLOCKS)
 815                 return !!li->li_data[bix];
 816         return logfs_exist_loop(inode, bix);
 817 }
 818
 819 static u64 seek_holedata_direct(struct inode *inode, u64 bix, int data)
 820 {
 821         struct logfs_inode *li = logfs_inode(inode);
 822
 823         for (; bix < I0_BLOCKS; bix++)
 824                 if (data ^ (li->li_data[bix] == 0))
 825                         return bix;
 826         return I0_BLOCKS;
 827 }
 828
 829 static u64 seek_holedata_loop(struct inode *inode, u64 bix, int data)
 830 {
 831         struct logfs_inode *li = logfs_inode(inode);
 832         __be64 *rblock;
 833         u64 increment, bofs = li->li_data[INDIRECT_INDEX];
 834         level_t level;
 835         int ret, slot;
 836         struct page *page;
 837
 838         BUG_ON(!bofs);
 839
 840         for (level = LEVEL(li->li_height); level != 0; level = SUBLEVEL(level)) {
 841                 increment = 1 << (LOGFS_BLOCK_BITS * ((__force u8)level-1));
 842                 page = logfs_get_read_page(inode, bix, level);
 843                 if (!page)
 844                         return bix;
 845
 846                 ret = logfs_segment_read(inode, page, bofs, bix, level);
 847                 if (ret) {
 848                         logfs_put_read_page(page);
 849                         return bix;
 850                 }
 851
 852                 slot = get_bits(bix, SUBLEVEL(level));
 853                 rblock = kmap_atomic(page);
 854                 while (slot < LOGFS_BLOCK_FACTOR) {
 855                         if (data && (rblock[slot] != 0))
 856                                 break;
 857                         if (!data && !(be64_to_cpu(rblock[slot]) & LOGFS_FULLY_POPULATED))
 858                                 break;
 859                         slot++;
 860                         bix += increment;
 861                         bix &= ~(increment - 1);
 862                 }
 863                 if (slot >= LOGFS_BLOCK_FACTOR) {
 864                         kunmap_atomic(rblock);
 865                         logfs_put_read_page(page);
 866                         return bix;
 867                 }
 868                 bofs = be64_to_cpu(rblock[slot]);
 869                 kunmap_atomic(rblock);
 870                 logfs_put_read_page(page);
 871                 if (!bofs) {
 872                         BUG_ON(data);
 873                         return bix;
 874                 }
 875         }
 876         return bix;
 877 }
 878
 879 /**
 880  * logfs_seek_hole - find next hole starting at a given block index
 881  * @inode:              inode to search in
 882  * @bix:                block index to start searching
 883  *
 884  * Returns next hole.  If the file doesn't contain any further holes, the
 885  * block address next to eof is returned instead.
 886  */
 887 u64 logfs_seek_hole(struct inode *inode, u64 bix)
 888 {
 889         struct logfs_inode *li = logfs_inode(inode);
 890
 891         if (bix < I0_BLOCKS) {
 892                 bix = seek_holedata_direct(inode, bix, 0);
 893                 if (bix < I0_BLOCKS)
 894                         return bix;
 895         }
 896
 897         if (!li->li_data[INDIRECT_INDEX])
 898                 return bix;
 899         else if (li->li_data[INDIRECT_INDEX] & LOGFS_FULLY_POPULATED)
 900                 bix = maxbix(li->li_height);
 901         else if (bix >= maxbix(li->li_height))
 902                 return bix;
 903         else {
 904                 bix = seek_holedata_loop(inode, bix, 0);
 905                 if (bix < maxbix(li->li_height))
 906                         return bix;
 907                 /* Should not happen anymore.  But if some port writes semi-
 908                  * corrupt images (as this one used to) we might run into it.
 909                  */
 910                 WARN_ON_ONCE(bix == maxbix(li->li_height));
 911         }
 912
 913         return bix;
 914 }
 915
 916 static u64 __logfs_seek_data(struct inode *inode, u64 bix)
 917 {
 918         struct logfs_inode *li = logfs_inode(inode);
 919
 920         if (bix < I0_BLOCKS) {
 921                 bix = seek_holedata_direct(inode, bix, 1);
 922                 if (bix < I0_BLOCKS)
 923                         return bix;
 924         }
 925
 926         if (bix < maxbix(li->li_height)) {
 927                 if (!li->li_data[INDIRECT_INDEX])
 928                         bix = maxbix(li->li_height);
 929                 else
 930                         return seek_holedata_loop(inode, bix, 1);
 931         }
 932
 933         return bix;
 934 }
 935
 936 /**
 937  * logfs_seek_data - find next data block after a given block index
 938  * @inode:              inode to search in
 939  * @bix:                block index to start searching
 940  *
 941  * Returns next data block.  If the file doesn't contain any further data
 942  * blocks, the last block in the file is returned instead.
 943  */
 944 u64 logfs_seek_data(struct inode *inode, u64 bix)
 945 {
 946         struct super_block *sb = inode->i_sb;
 947         u64 ret, end;
 948
 949         ret = __logfs_seek_data(inode, bix);
 950         end = i_size_read(inode) >> sb->s_blocksize_bits;
 951         if (ret >= end)
 952                 ret = max(bix, end);
 953         return ret;
 954 }
 955
 956 static int logfs_is_valid_direct(struct logfs_inode *li, u64 bix, u64 ofs)
 957 {
 958         return pure_ofs(li->li_data[bix]) == ofs;
 959 }
 960
 961 static int __logfs_is_valid_loop(struct inode *inode, u64 bix,
 962                 u64 ofs, u64 bofs)
 963 {
 964         struct logfs_inode *li = logfs_inode(inode);
 965         level_t level;
 966         int ret;
 967         struct page *page;
 968
 969         for (level = LEVEL(li->li_height); level != 0; level = SUBLEVEL(level)){
 970                 page = logfs_get_write_page(inode, bix, level);
 971                 BUG_ON(!page);
 972
 973                 ret = logfs_segment_read(inode, page, bofs, bix, level);
 974                 if (ret) {
 975                         logfs_put_write_page(page);
 976                         return 0;
 977                 }
 978
 979                 bofs = block_get_pointer(page, get_bits(bix, SUBLEVEL(level)));
 980                 logfs_put_write_page(page);
 981                 if (!bofs)
 982                         return 0;
 983
 984                 if (pure_ofs(bofs) == ofs)
 985                         return 1;
 986         }
 987         return 0;
 988 }
 989
 990 static int logfs_is_valid_loop(struct inode *inode, u64 bix, u64 ofs)
 991 {
 992         struct logfs_inode *li = logfs_inode(inode);
 993         u64 bofs = li->li_data[INDIRECT_INDEX];
 994
 995         if (!bofs)
 996                 return 0;
 997
 998         if (bix >= maxbix(li->li_height))
 999                 return 0;
1000
1001         if (pure_ofs(bofs) == ofs)
1002                 return 1;
1003
1004         return __logfs_is_valid_loop(inode, bix, ofs, bofs);
1005 }
1006
1007 static int __logfs_is_valid_block(struct inode *inode, u64 bix, u64 ofs)
1008 {
1009         struct logfs_inode *li = logfs_inode(inode);
1010
1011         if ((inode->i_nlink == 0) && atomic_read(&inode->i_count) == 1)
1012                 return 0;
1013
1014         if (bix < I0_BLOCKS)
1015                 return logfs_is_valid_direct(li, bix, ofs);
1016         return logfs_is_valid_loop(inode, bix, ofs);
1017 }
1018
1019 /**
1020  * logfs_is_valid_block - check whether this block is still valid
1021  *
1022  * @sb:         superblock
1023  * @ofs:        block physical offset
1024  * @ino:        block inode number
1025  * @bix:        block index
1026  * @gc_level:   block level
1027  *
1028  * Returns 0 if the block is invalid, 1 if it is valid and 2 if it will
1029  * become invalid once the journal is written.
1030  */
1031 int logfs_is_valid_block(struct super_block *sb, u64 ofs, u64 ino, u64 bix,
1032                 gc_level_t gc_level)
1033 {
1034         struct logfs_super *super = logfs_super(sb);
1035         struct inode *inode;
1036         int ret, cookie;
1037
1038         /* Umount closes a segment with free blocks remaining.  Those
1039          * blocks are by definition invalid. */
1040         if (ino == -1)
1041                 return 0;
1042
1043         LOGFS_BUG_ON((u64)(u_long)ino != ino, sb);
1044
1045         inode = logfs_safe_iget(sb, ino, &cookie);
1046         if (IS_ERR(inode))
1047                 goto invalid;
1048
1049         ret = __logfs_is_valid_block(inode, bix, ofs);
1050         logfs_safe_iput(inode, cookie);
1051         if (ret)
1052                 return ret;
1053
1054 invalid:
1055         /* Block is nominally invalid, but may still sit in the shadow tree,
1056          * waiting for a journal commit.
1057          */
1058         if (btree_lookup64(&super->s_shadow_tree.old, ofs))
1059                 return 2;
1060         return 0;
1061 }
1062
1063 int logfs_readpage_nolock(struct page *page)
1064 {
1065         struct inode *inode = page->mapping->host;
1066         int ret = -EIO;
1067
1068         ret = logfs_read_block(inode, page, READ);
1069
1070         if (ret) {
1071                 ClearPageUptodate(page);
1072                 SetPageError(page);
1073         } else {
1074                 SetPageUptodate(page);
1075                 ClearPageError(page);
1076         }
1077         flush_dcache_page(page);
1078
1079         return ret;
1080 }
1081
1082 static int logfs_reserve_bytes(struct inode *inode, int bytes)
1083 {
1084         struct logfs_super *super = logfs_super(inode->i_sb);
1085         u64 available = super->s_free_bytes + super->s_dirty_free_bytes
1086                         - super->s_dirty_used_bytes - super->s_dirty_pages;
1087
1088         if (!bytes)
1089                 return 0;
1090
1091         if (available < bytes)
1092                 return -ENOSPC;
1093
1094         if (available < bytes + super->s_root_reserve &&
1095                         !capable(CAP_SYS_RESOURCE))
1096                 return -ENOSPC;
1097
1098         return 0;
1099 }
1100
1101 int get_page_reserve(struct inode *inode, struct page *page)
1102 {
1103         struct logfs_super *super = logfs_super(inode->i_sb);
1104         struct logfs_block *block = logfs_block(page);
1105         int ret;
1106
1107         if (block && block->reserved_bytes)
1108                 return 0;
1109
1110         logfs_get_wblocks(inode->i_sb, page, WF_LOCK);
1111         while ((ret = logfs_reserve_bytes(inode, 6 * LOGFS_MAX_OBJECTSIZE)) &&
1112                         !list_empty(&super->s_writeback_list)) {
1113                 block = list_entry(super->s_writeback_list.next,
1114                                 struct logfs_block, alias_list);
1115                 block->ops->write_block(block);
1116         }
1117         if (!ret) {
1118                 alloc_data_block(inode, page);
1119                 block = logfs_block(page);
1120                 block->reserved_bytes += 6 * LOGFS_MAX_OBJECTSIZE;
1121                 super->s_dirty_pages += 6 * LOGFS_MAX_OBJECTSIZE;
1122                 list_move_tail(&block->alias_list, &super->s_writeback_list);
1123         }
1124         logfs_put_wblocks(inode->i_sb, page, WF_LOCK);
1125         return ret;
1126 }
1127
1128 /*
1129  * We are protected by write lock.  Push victims up to superblock level
1130  * and release transaction when appropriate.
1131  */
1132 /* FIXME: This is currently called from the wrong spots. */
1133 static void logfs_handle_transaction(struct inode *inode,
1134                 struct logfs_transaction *ta)
1135 {
1136         struct logfs_super *super = logfs_super(inode->i_sb);
1137
1138         if (!ta)
1139                 return;
1140         logfs_inode(inode)->li_block->ta = NULL;
1141
1142         if (inode->i_ino != LOGFS_INO_MASTER) {
1143                 BUG(); /* FIXME: Yes, this needs more thought */
1144                 /* just remember the transaction until inode is written */
1145                 //BUG_ON(logfs_inode(inode)->li_transaction);
1146                 //logfs_inode(inode)->li_transaction = ta;
1147                 return;
1148         }
1149
1150         switch (ta->state) {
1151         case CREATE_1: /* fall through */
1152         case UNLINK_1:
1153                 BUG_ON(super->s_victim_ino);
1154                 super->s_victim_ino = ta->ino;
1155                 break;
1156         case CREATE_2: /* fall through */
1157         case UNLINK_2:
1158                 BUG_ON(super->s_victim_ino != ta->ino);
1159                 super->s_victim_ino = 0;
1160                 /* transaction ends here - free it */
1161                 kfree(ta);
1162                 break;
1163         case CROSS_RENAME_1:
1164                 BUG_ON(super->s_rename_dir);
1165                 BUG_ON(super->s_rename_pos);
1166                 super->s_rename_dir = ta->dir;
1167                 super->s_rename_pos = ta->pos;
1168                 break;
1169         case CROSS_RENAME_2:
1170                 BUG_ON(super->s_rename_dir != ta->dir);
1171                 BUG_ON(super->s_rename_pos != ta->pos);
1172                 super->s_rename_dir = 0;
1173                 super->s_rename_pos = 0;
1174                 kfree(ta);
1175                 break;
1176         case TARGET_RENAME_1:
1177                 BUG_ON(super->s_rename_dir);
1178                 BUG_ON(super->s_rename_pos);
1179                 BUG_ON(super->s_victim_ino);
1180                 super->s_rename_dir = ta->dir;
1181                 super->s_rename_pos = ta->pos;
1182                 super->s_victim_ino = ta->ino;
1183                 break;
1184         case TARGET_RENAME_2:
1185                 BUG_ON(super->s_rename_dir != ta->dir);
1186                 BUG_ON(super->s_rename_pos != ta->pos);
1187                 BUG_ON(super->s_victim_ino != ta->ino);
1188                 super->s_rename_dir = 0;
1189                 super->s_rename_pos = 0;
1190                 break;
1191         case TARGET_RENAME_3:
1192                 BUG_ON(super->s_rename_dir);
1193                 BUG_ON(super->s_rename_pos);
1194                 BUG_ON(super->s_victim_ino != ta->ino);
1195                 super->s_victim_ino = 0;
1196                 kfree(ta);
1197                 break;
1198         default:
1199                 BUG();
1200         }
1201 }
1202
1203 /*
1204  * Not strictly a reservation, but rather a check that we still have enough
1205  * space to satisfy the write.
1206  */
1207 static int logfs_reserve_blocks(struct inode *inode, int blocks)
1208 {
1209         return logfs_reserve_bytes(inode, blocks * LOGFS_MAX_OBJECTSIZE);
1210 }
1211
1212 struct write_control {
1213         u64 ofs;
1214         long flags;
1215 };
1216
1217 static struct logfs_shadow *alloc_shadow(struct inode *inode, u64 bix,
1218                 level_t level, u64 old_ofs)
1219 {
1220         struct logfs_super *super = logfs_super(inode->i_sb);
1221         struct logfs_shadow *shadow;
1222
1223         shadow = mempool_alloc(super->s_shadow_pool, GFP_NOFS);
1224         memset(shadow, 0, sizeof(*shadow));
1225         shadow->ino = inode->i_ino;
1226         shadow->bix = bix;
1227         shadow->gc_level = expand_level(inode->i_ino, level);
1228         shadow->old_ofs = old_ofs & ~LOGFS_FULLY_POPULATED;
1229         return shadow;
1230 }
1231
1232 static void free_shadow(struct inode *inode, struct logfs_shadow *shadow)
1233 {
1234         struct logfs_super *super = logfs_super(inode->i_sb);
1235
1236         mempool_free(shadow, super->s_shadow_pool);
1237 }
1238
1239 static void mark_segment(struct shadow_tree *tree, u32 segno)
1240 {
1241         int err;
1242
1243         if (!btree_lookup32(&tree->segment_map, segno)) {
1244                 err = btree_insert32(&tree->segment_map, segno, (void *)1,
1245                                 GFP_NOFS);
1246                 BUG_ON(err);
1247                 tree->no_shadowed_segments++;
1248         }
1249 }
1250
1251 /**
1252  * fill_shadow_tree - Propagate shadow tree changes due to a write
1253  * @inode:      Inode owning the page
1254  * @page:       Struct page that was written
1255  * @shadow:     Shadow for the current write
1256  *
1257  * Writes in logfs can result in two semi-valid objects.  The old object
1258  * is still valid as long as it can be reached by following pointers on
1259  * the medium.  Only when writes propagate all the way up to the journal
1260  * has the new object safely replaced the old one.
1261  *
1262  * To handle this problem, a struct logfs_shadow is used to represent
1263  * every single write.  It is attached to the indirect block, which is
1264  * marked dirty.  When the indirect block is written, its shadows are
1265  * handed up to the next indirect block (or inode).  Untimately they
1266  * will reach the master inode and be freed upon journal commit.
1267  *
1268  * This function handles a single step in the propagation.  It adds the
1269  * shadow for the current write to the tree, along with any shadows in
1270  * the page's tree, in case it was an indirect block.  If a page is
1271  * written, the inode parameter is left NULL, if an inode is written,
1272  * the page parameter is left NULL.
1273  */
1274 static void fill_shadow_tree(struct inode *inode, struct page *page,
1275                 struct logfs_shadow *shadow)
1276 {
1277         struct logfs_super *super = logfs_super(inode->i_sb);
1278         struct logfs_block *block = logfs_block(page);
1279         struct shadow_tree *tree = &super->s_shadow_tree;
1280
1281         if (PagePrivate(page)) {
1282                 if (block->alias_map)
1283                         super->s_no_object_aliases -= bitmap_weight(
1284                                         block->alias_map, LOGFS_BLOCK_FACTOR);
1285                 logfs_handle_transaction(inode, block->ta);
1286                 block->ops->free_block(inode->i_sb, block);
1287         }
1288         if (shadow) {
1289                 if (shadow->old_ofs)
1290                         btree_insert64(&tree->old, shadow->old_ofs, shadow,
1291                                         GFP_NOFS);
1292                 else
1293                         btree_insert64(&tree->new, shadow->new_ofs, shadow,
1294                                         GFP_NOFS);
1295
1296                 super->s_dirty_used_bytes += shadow->new_len;
1297                 super->s_dirty_free_bytes += shadow->old_len;
1298                 mark_segment(tree, shadow->old_ofs >> super->s_segshift);
1299                 mark_segment(tree, shadow->new_ofs >> super->s_segshift);
1300         }
1301 }
1302
1303 static void logfs_set_alias(struct super_block *sb, struct logfs_block *block,
1304                 long child_no)
1305 {
1306         struct logfs_super *super = logfs_super(sb);
1307
1308         if (block->inode && block->inode->i_ino == LOGFS_INO_MASTER) {
1309                 /* Aliases in the master inode are pointless. */
1310                 return;
1311         }
1312
1313         if (!test_bit(child_no, block->alias_map)) {
1314                 set_bit(child_no, block->alias_map);
1315                 super->s_no_object_aliases++;
1316         }
1317         list_move_tail(&block->alias_list, &super->s_object_alias);
1318 }
1319
1320 /*
1321  * Object aliases can and often do change the size and occupied space of a
1322  * file.  So not only do we have to change the pointers, we also have to
1323  * change inode->i_size and li->li_used_bytes.  Which is done by setting
1324  * another two object aliases for the inode itself.
1325  */
1326 static void set_iused(struct inode *inode, struct logfs_shadow *shadow)
1327 {
1328         struct logfs_inode *li = logfs_inode(inode);
1329
1330         if (shadow->new_len == shadow->old_len)
1331                 return;
1332
1333         alloc_inode_block(inode);
1334         li->li_used_bytes += shadow->new_len - shadow->old_len;
1335         __logfs_set_blocks(inode);
1336         logfs_set_alias(inode->i_sb, li->li_block, INODE_USED_OFS);
1337         logfs_set_alias(inode->i_sb, li->li_block, INODE_SIZE_OFS);
1338 }
1339
1340 static int logfs_write_i0(struct inode *inode, struct page *page,
1341                 struct write_control *wc)
1342 {
1343         struct logfs_shadow *shadow;
1344         u64 bix;
1345         level_t level;
1346         int full, err = 0;
1347
1348         logfs_unpack_index(page->index, &bix, &level);
1349         if (wc->ofs == 0)
1350                 if (logfs_reserve_blocks(inode, 1))
1351                         return -ENOSPC;
1352
1353         shadow = alloc_shadow(inode, bix, level, wc->ofs);
1354         if (wc->flags & WF_WRITE)
1355                 err = logfs_segment_write(inode, page, shadow);
1356         if (wc->flags & WF_DELETE)
1357                 logfs_segment_delete(inode, shadow);
1358         if (err) {
1359                 free_shadow(inode, shadow);
1360                 return err;
1361         }
1362
1363         set_iused(inode, shadow);
1364         full = 1;
1365         if (level != 0) {
1366                 alloc_indirect_block(inode, page, 0);
1367                 full = logfs_block(page)->full == LOGFS_BLOCK_FACTOR;
1368         }
1369         fill_shadow_tree(inode, page, shadow);
1370         wc->ofs = shadow->new_ofs;
1371         if (wc->ofs && full)
1372                 wc->ofs |= LOGFS_FULLY_POPULATED;
1373         return 0;
1374 }
1375
1376 static int logfs_write_direct(struct inode *inode, struct page *page,
1377                 long flags)
1378 {
1379         struct logfs_inode *li = logfs_inode(inode);
1380         struct write_control wc = {
1381                 .ofs = li->li_data[page->index],
1382                 .flags = flags,
1383         };
1384         int err;
1385
1386         alloc_inode_block(inode);
1387
1388         err = logfs_write_i0(inode, page, &wc);
1389         if (err)
1390                 return err;
1391
1392         li->li_data[page->index] = wc.ofs;
1393         logfs_set_alias(inode->i_sb, li->li_block,
1394                         page->index + INODE_POINTER_OFS);
1395         return 0;
1396 }
1397
1398 static int ptr_change(u64 ofs, struct page *page)
1399 {
1400         struct logfs_block *block = logfs_block(page);
1401         int empty0, empty1, full0, full1;
1402
1403         empty0 = ofs == 0;
1404         empty1 = block->partial == 0;
1405         if (empty0 != empty1)
1406                 return 1;
1407
1408         /* The !! is necessary to shrink result to int */
1409         full0 = !!(ofs & LOGFS_FULLY_POPULATED);
1410         full1 = block->full == LOGFS_BLOCK_FACTOR;
1411         if (full0 != full1)
1412                 return 1;
1413         return 0;
1414 }
1415
1416 static int __logfs_write_rec(struct inode *inode, struct page *page,
1417                 struct write_control *this_wc,
1418                 pgoff_t bix, level_t target_level, level_t level)
1419 {
1420         int ret, page_empty = 0;
1421         int child_no = get_bits(bix, SUBLEVEL(level));
1422         struct page *ipage;
1423         struct write_control child_wc = {
1424                 .flags = this_wc->flags,
1425         };
1426
1427         ipage = logfs_get_write_page(inode, bix, level);
1428         if (!ipage)
1429                 return -ENOMEM;
1430
1431         if (this_wc->ofs) {
1432                 ret = logfs_segment_read(inode, ipage, this_wc->ofs, bix, level);
1433                 if (ret)
1434                         goto out;
1435         } else if (!PageUptodate(ipage)) {
1436                 page_empty = 1;
1437                 logfs_read_empty(ipage);
1438         }
1439
1440         child_wc.ofs = block_get_pointer(ipage, child_no);
1441
1442         if ((__force u8)level-1 > (__force u8)target_level)
1443                 ret = __logfs_write_rec(inode, page, &child_wc, bix,
1444                                 target_level, SUBLEVEL(level));
1445         else
1446                 ret = logfs_write_i0(inode, page, &child_wc);
1447
1448         if (ret)
1449                 goto out;
1450
1451         alloc_indirect_block(inode, ipage, page_empty);
1452         block_set_pointer(ipage, child_no, child_wc.ofs);
1453         /* FIXME: first condition seems superfluous */
1454         if (child_wc.ofs || logfs_block(ipage)->partial)
1455                 this_wc->flags |= WF_WRITE;
1456         /* the condition on this_wc->ofs ensures that we won't consume extra
1457          * space for indirect blocks in the future, which we cannot reserve */
1458         if (!this_wc->ofs || ptr_change(this_wc->ofs, ipage))
1459                 ret = logfs_write_i0(inode, ipage, this_wc);
1460         else
1461                 logfs_set_alias(inode->i_sb, logfs_block(ipage), child_no);
1462 out:
1463         logfs_put_write_page(ipage);
1464         return ret;
1465 }
1466
1467 static int logfs_write_rec(struct inode *inode, struct page *page,
1468                 pgoff_t bix, level_t target_level, long flags)
1469 {
1470         struct logfs_inode *li = logfs_inode(inode);
1471         struct write_control wc = {
1472                 .ofs = li->li_data[INDIRECT_INDEX],
1473                 .flags = flags,
1474         };
1475         int ret;
1476
1477         alloc_inode_block(inode);
1478
1479         if (li->li_height > (__force u8)target_level)
1480                 ret = __logfs_write_rec(inode, page, &wc, bix, target_level,
1481                                 LEVEL(li->li_height));
1482         else
1483                 ret = logfs_write_i0(inode, page, &wc);
1484         if (ret)
1485                 return ret;
1486
1487         if (li->li_data[INDIRECT_INDEX] != wc.ofs) {
1488                 li->li_data[INDIRECT_INDEX] = wc.ofs;
1489                 logfs_set_alias(inode->i_sb, li->li_block,
1490                                 INDIRECT_INDEX + INODE_POINTER_OFS);
1491         }
1492         return ret;
1493 }
1494
1495 void logfs_add_transaction(struct inode *inode, struct logfs_transaction *ta)
1496 {
1497         alloc_inode_block(inode);
1498         logfs_inode(inode)->li_block->ta = ta;
1499 }
1500
1501 void logfs_del_transaction(struct inode *inode, struct logfs_transaction *ta)
1502 {
1503         struct logfs_block *block = logfs_inode(inode)->li_block;
1504
1505         if (block && block->ta)
1506                 block->ta = NULL;
1507 }
1508
1509 static int grow_inode(struct inode *inode, u64 bix, level_t level)
1510 {
1511         struct logfs_inode *li = logfs_inode(inode);
1512         u8 height = (__force u8)level;
1513         struct page *page;
1514         struct write_control wc = {
1515                 .flags = WF_WRITE,
1516         };
1517         int err;
1518
1519         BUG_ON(height > 5 || li->li_height > 5);
1520         while (height > li->li_height || bix >= maxbix(li->li_height)) {
1521                 page = logfs_get_write_page(inode, I0_BLOCKS + 1,
1522                                 LEVEL(li->li_height + 1));
1523                 if (!page)
1524                         return -ENOMEM;
1525                 logfs_read_empty(page);
1526                 alloc_indirect_block(inode, page, 1);
1527                 block_set_pointer(page, 0, li->li_data[INDIRECT_INDEX]);
1528                 err = logfs_write_i0(inode, page, &wc);
1529                 logfs_put_write_page(page);
1530                 if (err)
1531                         return err;
1532                 li->li_data[INDIRECT_INDEX] = wc.ofs;
1533                 wc.ofs = 0;
1534                 li->li_height++;
1535                 logfs_set_alias(inode->i_sb, li->li_block, INODE_HEIGHT_OFS);
1536         }
1537         return 0;
1538 }
1539
1540 static int __logfs_write_buf(struct inode *inode, struct page *page, long flags)
1541 {
1542         struct logfs_super *super = logfs_super(inode->i_sb);
1543         pgoff_t index = page->index;
1544         u64 bix;
1545         level_t level;
1546         int err;
1547
1548         flags |= WF_WRITE | WF_DELETE;
1549         inode->i_ctime = inode->i_mtime = CURRENT_TIME;
1550
1551         logfs_unpack_index(index, &bix, &level);
1552         if (logfs_block(page) && logfs_block(page)->reserved_bytes)
1553                 super->s_dirty_pages -= logfs_block(page)->reserved_bytes;
1554
1555         if (index < I0_BLOCKS)
1556                 return logfs_write_direct(inode, page, flags);
1557
1558         bix = adjust_bix(bix, level);
1559         err = grow_inode(inode, bix, level);
1560         if (err)
1561                 return err;
1562         return logfs_write_rec(inode, page, bix, level, flags);
1563 }
1564
1565 int logfs_write_buf(struct inode *inode, struct page *page, long flags)
1566 {
1567         struct super_block *sb = inode->i_sb;
1568         int ret;
1569
1570         logfs_get_wblocks(sb, page, flags & WF_LOCK);
1571         ret = __logfs_write_buf(inode, page, flags);
1572         logfs_put_wblocks(sb, page, flags & WF_LOCK);
1573         return ret;
1574 }
1575
1576 static int __logfs_delete(struct inode *inode, struct page *page)
1577 {
1578         long flags = WF_DELETE;
1579         int err;
1580
1581         inode->i_ctime = inode->i_mtime = CURRENT_TIME;
1582
1583         if (page->index < I0_BLOCKS)
1584                 return logfs_write_direct(inode, page, flags);
1585         err = grow_inode(inode, page->index, 0);
1586         if (err)
1587                 return err;
1588         return logfs_write_rec(inode, page, page->index, 0, flags);
1589 }
1590
1591 int logfs_delete(struct inode *inode, pgoff_t index,
1592                 struct shadow_tree *shadow_tree)
1593 {
1594         struct super_block *sb = inode->i_sb;
1595         struct page *page;
1596         int ret;
1597
1598         page = logfs_get_read_page(inode, index, 0);
1599         if (!page)
1600                 return -ENOMEM;
1601
1602         logfs_get_wblocks(sb, page, 1);
1603         ret = __logfs_delete(inode, page);
1604         logfs_put_wblocks(sb, page, 1);
1605
1606         logfs_put_read_page(page);
1607
1608         return ret;
1609 }
1610
1611 int logfs_rewrite_block(struct inode *inode, u64 bix, u64 ofs,
1612                 gc_level_t gc_level, long flags)
1613 {
1614         level_t level = shrink_level(gc_level);
1615         struct page *page;
1616         int err;
1617
1618         page = logfs_get_write_page(inode, bix, level);
1619         if (!page)
1620                 return -ENOMEM;
1621
1622         err = logfs_segment_read(inode, page, ofs, bix, level);
1623         if (!err) {
1624                 if (level != 0)
1625                         alloc_indirect_block(inode, page, 0);
1626                 err = logfs_write_buf(inode, page, flags);
1627                 if (!err && shrink_level(gc_level) == 0) {
1628                         /* Rewrite cannot mark the inode dirty but has to
1629                          * write it immediately.
1630                          * Q: Can't we just create an alias for the inode
1631                          * instead?  And if not, why not?
1632                          */
1633                         if (inode->i_ino == LOGFS_INO_MASTER)
1634                                 logfs_write_anchor(inode->i_sb);
1635                         else {
1636                                 err = __logfs_write_inode(inode, page, flags);
1637                         }
1638                 }
1639         }
1640         logfs_put_write_page(page);
1641         return err;
1642 }
1643
1644 static int truncate_data_block(struct inode *inode, struct page *page,
1645                 u64 ofs, struct logfs_shadow *shadow, u64 size)
1646 {
1647         loff_t pageofs = page->index << inode->i_sb->s_blocksize_bits;
1648         u64 bix;
1649         level_t level;
1650         int err;
1651
1652         /* Does truncation happen within this page? */
1653         if (size <= pageofs || size - pageofs >= PAGE_SIZE)
1654                 return 0;
1655
1656         logfs_unpack_index(page->index, &bix, &level);
1657         BUG_ON(level != 0);
1658
1659         err = logfs_segment_read(inode, page, ofs, bix, level);
1660         if (err)
1661                 return err;
1662
1663         zero_user_segment(page, size - pageofs, PAGE_CACHE_SIZE);
1664         return logfs_segment_write(inode, page, shadow);
1665 }
1666
1667 static int logfs_truncate_i0(struct inode *inode, struct page *page,
1668                 struct write_control *wc, u64 size)
1669 {
1670         struct logfs_shadow *shadow;
1671         u64 bix;
1672         level_t level;
1673         int err = 0;
1674
1675         logfs_unpack_index(page->index, &bix, &level);
1676         BUG_ON(level != 0);
1677         shadow = alloc_shadow(inode, bix, level, wc->ofs);
1678
1679         err = truncate_data_block(inode, page, wc->ofs, shadow, size);
1680         if (err) {
1681                 free_shadow(inode, shadow);
1682                 return err;
1683         }
1684
1685         logfs_segment_delete(inode, shadow);
1686         set_iused(inode, shadow);
1687         fill_shadow_tree(inode, page, shadow);
1688         wc->ofs = shadow->new_ofs;
1689         return 0;
1690 }
1691
1692 static int logfs_truncate_direct(struct inode *inode, u64 size)
1693 {
1694         struct logfs_inode *li = logfs_inode(inode);
1695         struct write_control wc;
1696         struct page *page;
1697         int e;
1698         int err;
1699
1700         alloc_inode_block(inode);
1701
1702         for (e = I0_BLOCKS - 1; e >= 0; e--) {
1703                 if (size > (e+1) * LOGFS_BLOCKSIZE)
1704                         break;
1705
1706                 wc.ofs = li->li_data[e];
1707                 if (!wc.ofs)
1708                         continue;
1709
1710                 page = logfs_get_write_page(inode, e, 0);
1711                 if (!page)
1712                         return -ENOMEM;
1713                 err = logfs_segment_read(inode, page, wc.ofs, e, 0);
1714                 if (err) {
1715                         logfs_put_write_page(page);
1716                         return err;
1717                 }
1718                 err = logfs_truncate_i0(inode, page, &wc, size);
1719                 logfs_put_write_page(page);
1720                 if (err)
1721                         return err;
1722
1723                 li->li_data[e] = wc.ofs;
1724         }
1725         return 0;
1726 }
1727
1728 /* FIXME: these need to become per-sb once we support different blocksizes */
1729 static u64 __logfs_step[] = {
1730         1,
1731         I1_BLOCKS,
1732         I2_BLOCKS,
1733         I3_BLOCKS,
1734 };
1735
1736 static u64 __logfs_start_index[] = {
1737         I0_BLOCKS,
1738         I1_BLOCKS,
1739         I2_BLOCKS,
1740         I3_BLOCKS
1741 };
1742
1743 static inline u64 logfs_step(level_t level)
1744 {
1745         return __logfs_step[(__force u8)level];
1746 }
1747
1748 static inline u64 logfs_factor(u8 level)
1749 {
1750         return __logfs_step[level] * LOGFS_BLOCKSIZE;
1751 }
1752
1753 static inline u64 logfs_start_index(level_t level)
1754 {
1755         return __logfs_start_index[(__force u8)level];
1756 }
1757
1758 static void logfs_unpack_raw_index(pgoff_t index, u64 *bix, level_t *level)
1759 {
1760         logfs_unpack_index(index, bix, level);
1761         if (*bix <= logfs_start_index(SUBLEVEL(*level)))
1762                 *bix = 0;
1763 }
1764
1765 static int __logfs_truncate_rec(struct inode *inode, struct page *ipage,
1766                 struct write_control *this_wc, u64 size)
1767 {
1768         int truncate_happened = 0;
1769         int e, err = 0;
1770         u64 bix, child_bix, next_bix;
1771         level_t level;
1772         struct page *page;
1773         struct write_control child_wc = { /* FIXME: flags */ };
1774
1775         logfs_unpack_raw_index(ipage->index, &bix, &level);
1776         err = logfs_segment_read(inode, ipage, this_wc->ofs, bix, level);
1777         if (err)
1778                 return err;
1779
1780         for (e = LOGFS_BLOCK_FACTOR - 1; e >= 0; e--) {
1781                 child_bix = bix + e * logfs_step(SUBLEVEL(level));
1782                 next_bix = child_bix + logfs_step(SUBLEVEL(level));
1783                 if (size > next_bix * LOGFS_BLOCKSIZE)
1784                         break;
1785
1786                 child_wc.ofs = pure_ofs(block_get_pointer(ipage, e));
1787                 if (!child_wc.ofs)
1788                         continue;
1789
1790                 page = logfs_get_write_page(inode, child_bix, SUBLEVEL(level));
1791                 if (!page)
1792                         return -ENOMEM;
1793
1794                 if ((__force u8)level > 1)
1795                         err = __logfs_truncate_rec(inode, page, &child_wc, size);
1796                 else
1797                         err = logfs_truncate_i0(inode, page, &child_wc, size);
1798                 logfs_put_write_page(page);
1799                 if (err)
1800                         return err;
1801
1802                 truncate_happened = 1;
1803                 alloc_indirect_block(inode, ipage, 0);
1804                 block_set_pointer(ipage, e, child_wc.ofs);
1805         }
1806
1807         if (!truncate_happened) {
1808                 printk("ineffectual truncate (%lx, %lx, %llx)\n", inode->i_ino, ipage->index, size);
1809                 return 0;
1810         }
1811
1812         this_wc->flags = WF_DELETE;
1813         if (logfs_block(ipage)->partial)
1814                 this_wc->flags |= WF_WRITE;
1815
1816         return logfs_write_i0(inode, ipage, this_wc);
1817 }
1818
1819 static int logfs_truncate_rec(struct inode *inode, u64 size)
1820 {
1821         struct logfs_inode *li = logfs_inode(inode);
1822         struct write_control wc = {
1823                 .ofs = li->li_data[INDIRECT_INDEX],
1824         };
1825         struct page *page;
1826         int err;
1827
1828         alloc_inode_block(inode);
1829
1830         if (!wc.ofs)
1831                 return 0;
1832
1833         page = logfs_get_write_page(inode, 0, LEVEL(li->li_height));
1834         if (!page)
1835                 return -ENOMEM;
1836
1837         err = __logfs_truncate_rec(inode, page, &wc, size);
1838         logfs_put_write_page(page);
1839         if (err)
1840                 return err;
1841
1842         if (li->li_data[INDIRECT_INDEX] != wc.ofs)
1843                 li->li_data[INDIRECT_INDEX] = wc.ofs;
1844         return 0;
1845 }
1846
1847 static int __logfs_truncate(struct inode *inode, u64 size)
1848 {
1849         int ret;
1850
1851         if (size >= logfs_factor(logfs_inode(inode)->li_height))
1852                 return 0;
1853
1854         ret = logfs_truncate_rec(inode, size);
1855         if (ret)
1856                 return ret;
1857
1858         return logfs_truncate_direct(inode, size);
1859 }
1860
1861 /*
1862  * Truncate, by changing the segment file, can consume a fair amount
1863  * of resources.  So back off from time to time and do some GC.
1864  * 8 or 2048 blocks should be well within safety limits even if
1865  * every single block resided in a different segment.
1866  */
1867 #define TRUNCATE_STEP   (8 * 1024 * 1024)
1868 int logfs_truncate(struct inode *inode, u64 target)
1869 {
1870         struct super_block *sb = inode->i_sb;
1871         u64 size = i_size_read(inode);
1872         int err = 0;
1873
1874         size = ALIGN(size, TRUNCATE_STEP);
1875         while (size > target) {
1876                 if (size > TRUNCATE_STEP)
1877                         size -= TRUNCATE_STEP;
1878                 else
1879                         size = 0;
1880                 if (size < target)
1881                         size = target;
1882
1883                 logfs_get_wblocks(sb, NULL, 1);
1884                 err = __logfs_truncate(inode, size);
1885                 if (!err)
1886                         err = __logfs_write_inode(inode, NULL, 0);
1887                 logfs_put_wblocks(sb, NULL, 1);
1888         }
1889
1890         if (!err) {
1891                 err = inode_newsize_ok(inode, target);
1892                 if (err)
1893                         goto out;
1894
1895                 truncate_setsize(inode, target);
1896         }
1897
1898  out:
1899         /* I don't trust error recovery yet. */
1900         WARN_ON(err);
1901         return err;
1902 }
1903
1904 static void move_page_to_inode(struct inode *inode, struct page *page)
1905 {
1906         struct logfs_inode *li = logfs_inode(inode);
1907         struct logfs_block *block = logfs_block(page);
1908
1909         if (!block)
1910                 return;
1911
1912         log_blockmove("move_page_to_inode(%llx, %llx, %x)\n",
1913                         block->ino, block->bix, block->level);
1914         BUG_ON(li->li_block);
1915         block->ops = &inode_block_ops;
1916         block->inode = inode;
1917         li->li_block = block;
1918
1919         block->page = NULL;
1920         if (PagePrivate(page)) {
1921                 ClearPagePrivate(page);
1922                 page_cache_release(page);
1923                 set_page_private(page, 0);
1924         }
1925 }
1926
1927 static void move_inode_to_page(struct page *page, struct inode *inode)
1928 {
1929         struct logfs_inode *li = logfs_inode(inode);
1930         struct logfs_block *block = li->li_block;
1931
1932         if (!block)
1933                 return;
1934
1935         log_blockmove("move_inode_to_page(%llx, %llx, %x)\n",
1936                         block->ino, block->bix, block->level);
1937         BUG_ON(PagePrivate(page));
1938         block->ops = &indirect_block_ops;
1939         block->page = page;
1940
1941         if (!PagePrivate(page)) {
1942                 SetPagePrivate(page);
1943                 page_cache_get(page);
1944                 set_page_private(page, (unsigned long) block);
1945         }
1946
1947         block->inode = NULL;
1948         li->li_block = NULL;
1949 }
1950
1951 int logfs_read_inode(struct inode *inode)
1952 {
1953         struct super_block *sb = inode->i_sb;
1954         struct logfs_super *super = logfs_super(sb);
1955         struct inode *master_inode = super->s_master_inode;
1956         struct page *page;
1957         struct logfs_disk_inode *di;
1958         u64 ino = inode->i_ino;
1959
1960         if (ino << sb->s_blocksize_bits > i_size_read(master_inode))
1961                 return -ENODATA;
1962         if (!logfs_exist_block(master_inode, ino))
1963                 return -ENODATA;
1964
1965         page = read_cache_page(master_inode->i_mapping, ino,
1966                         (filler_t *)logfs_readpage, NULL);
1967         if (IS_ERR(page))
1968                 return PTR_ERR(page);
1969
1970         di = kmap_atomic(page);
1971         logfs_disk_to_inode(di, inode);
1972         kunmap_atomic(di);
1973         move_page_to_inode(inode, page);
1974         page_cache_release(page);
1975         return 0;
1976 }
1977
1978 /* Caller must logfs_put_write_page(page); */
1979 static struct page *inode_to_page(struct inode *inode)
1980 {
1981         struct inode *master_inode = logfs_super(inode->i_sb)->s_master_inode;
1982         struct logfs_disk_inode *di;
1983         struct page *page;
1984
1985         BUG_ON(inode->i_ino == LOGFS_INO_MASTER);
1986
1987         page = logfs_get_write_page(master_inode, inode->i_ino, 0);
1988         if (!page)
1989                 return NULL;
1990
1991         di = kmap_atomic(page);
1992         logfs_inode_to_disk(inode, di);
1993         kunmap_atomic(di);
1994         move_inode_to_page(page, inode);
1995         return page;
1996 }
1997
1998 static int do_write_inode(struct inode *inode)
1999 {
2000         struct super_block *sb = inode->i_sb;
2001         struct inode *master_inode = logfs_super(sb)->s_master_inode;
2002         loff_t size = (inode->i_ino + 1) << inode->i_sb->s_blocksize_bits;
2003         struct page *page;
2004         int err;
2005
2006         BUG_ON(inode->i_ino == LOGFS_INO_MASTER);
2007         /* FIXME: lock inode */
2008
2009         if (i_size_read(master_inode) < size)
2010                 i_size_write(master_inode, size);
2011
2012         /* TODO: Tell vfs this inode is clean now */
2013
2014         page = inode_to_page(inode);
2015         if (!page)
2016                 return -ENOMEM;
2017
2018         /* FIXME: transaction is part of logfs_block now.  Is that enough? */
2019         err = logfs_write_buf(master_inode, page, 0);
2020         if (err)
2021                 move_page_to_inode(inode, page);
2022
2023         logfs_put_write_page(page);
2024         return err;
2025 }
2026
2027 static void logfs_mod_segment_entry(struct super_block *sb, u32 segno,
2028                 int write,
2029                 void (*change_se)(struct logfs_segment_entry *, long),
2030                 long arg)
2031 {
2032         struct logfs_super *super = logfs_super(sb);
2033         struct inode *inode;
2034         struct page *page;
2035         struct logfs_segment_entry *se;
2036         pgoff_t page_no;
2037         int child_no;
2038
2039         page_no = segno >> (sb->s_blocksize_bits - 3);
2040         child_no = segno & ((sb->s_blocksize >> 3) - 1);
2041
2042         inode = super->s_segfile_inode;
2043         page = logfs_get_write_page(inode, page_no, 0);
2044         BUG_ON(!page); /* FIXME: We need some reserve page for this case */
2045         if (!PageUptodate(page))
2046                 logfs_read_block(inode, page, WRITE);
2047
2048         if (write)
2049                 alloc_indirect_block(inode, page, 0);
2050         se = kmap_atomic(page);
2051         change_se(se + child_no, arg);
2052         if (write) {
2053                 logfs_set_alias(sb, logfs_block(page), child_no);
2054                 BUG_ON((int)be32_to_cpu(se[child_no].valid) > super->s_segsize);
2055         }
2056         kunmap_atomic(se);
2057
2058         logfs_put_write_page(page);
2059 }
2060
2061 static void __get_segment_entry(struct logfs_segment_entry *se, long _target)
2062 {
2063         struct logfs_segment_entry *target = (void *)_target;
2064
2065         *target = *se;
2066 }
2067
2068 void logfs_get_segment_entry(struct super_block *sb, u32 segno,
2069                 struct logfs_segment_entry *se)
2070 {
2071         logfs_mod_segment_entry(sb, segno, 0, __get_segment_entry, (long)se);
2072 }
2073
2074 static void __set_segment_used(struct logfs_segment_entry *se, long increment)
2075 {
2076         u32 valid;
2077
2078         valid = be32_to_cpu(se->valid);
2079         valid += increment;
2080         se->valid = cpu_to_be32(valid);
2081 }
2082
2083 void logfs_set_segment_used(struct super_block *sb, u64 ofs, int increment)
2084 {
2085         struct logfs_super *super = logfs_super(sb);
2086         u32 segno = ofs >> super->s_segshift;
2087
2088         if (!increment)
2089                 return;
2090
2091         logfs_mod_segment_entry(sb, segno, 1, __set_segment_used, increment);
2092 }
2093
2094 static void __set_segment_erased(struct logfs_segment_entry *se, long ec_level)
2095 {
2096         se->ec_level = cpu_to_be32(ec_level);
2097 }
2098
2099 void logfs_set_segment_erased(struct super_block *sb, u32 segno, u32 ec,
2100                 gc_level_t gc_level)
2101 {
2102         u32 ec_level = ec << 4 | (__force u8)gc_level;
2103
2104         logfs_mod_segment_entry(sb, segno, 1, __set_segment_erased, ec_level);
2105 }
2106
2107 static void __set_segment_reserved(struct logfs_segment_entry *se, long ignore)
2108 {
2109         se->valid = cpu_to_be32(RESERVED);
2110 }
2111
2112 void logfs_set_segment_reserved(struct super_block *sb, u32 segno)
2113 {
2114         logfs_mod_segment_entry(sb, segno, 1, __set_segment_reserved, 0);
2115 }
2116
2117 static void __set_segment_unreserved(struct logfs_segment_entry *se,
2118                 long ec_level)
2119 {
2120         se->valid = 0;
2121         se->ec_level = cpu_to_be32(ec_level);
2122 }
2123
2124 void logfs_set_segment_unreserved(struct super_block *sb, u32 segno, u32 ec)
2125 {
2126         u32 ec_level = ec << 4;
2127
2128         logfs_mod_segment_entry(sb, segno, 1, __set_segment_unreserved,
2129                         ec_level);
2130 }
2131
2132 int __logfs_write_inode(struct inode *inode, struct page *page, long flags)
2133 {
2134         struct super_block *sb = inode->i_sb;
2135         int ret;
2136
2137         logfs_get_wblocks(sb, page, flags & WF_LOCK);
2138         ret = do_write_inode(inode);
2139         logfs_put_wblocks(sb, page, flags & WF_LOCK);
2140         return ret;
2141 }
2142
2143 static int do_delete_inode(struct inode *inode)
2144 {
2145         struct super_block *sb = inode->i_sb;
2146         struct inode *master_inode = logfs_super(sb)->s_master_inode;
2147         struct page *page;
2148         int ret;
2149
2150         page = logfs_get_write_page(master_inode, inode->i_ino, 0);
2151         if (!page)
2152                 return -ENOMEM;
2153
2154         move_inode_to_page(page, inode);
2155
2156         logfs_get_wblocks(sb, page, 1);
2157         ret = __logfs_delete(master_inode, page);
2158         logfs_put_wblocks(sb, page, 1);
2159
2160         logfs_put_write_page(page);
2161         return ret;
2162 }
2163
2164 /*
2165  * ZOMBIE inodes have already been deleted before and should remain dead,
2166  * if it weren't for valid checking.  No need to kill them again here.
2167  */
2168 void logfs_evict_inode(struct inode *inode)
2169 {
2170         struct super_block *sb = inode->i_sb;
2171         struct logfs_inode *li = logfs_inode(inode);
2172         struct logfs_block *block = li->li_block;
2173         struct page *page;
2174
2175         if (!inode->i_nlink) {
2176                 if (!(li->li_flags & LOGFS_IF_ZOMBIE)) {
2177                         li->li_flags |= LOGFS_IF_ZOMBIE;
2178                         if (i_size_read(inode) > 0)
2179                                 logfs_truncate(inode, 0);
2180                         do_delete_inode(inode);
2181                 }
2182         }
2183         truncate_inode_pages_final(&inode->i_data);
2184         clear_inode(inode);
2185
2186         /* Cheaper version of write_inode.  All changes are concealed in
2187          * aliases, which are moved back.  No write to the medium happens.
2188          */
2189         /* Only deleted files may be dirty at this point */
2190         BUG_ON(inode->i_state & I_DIRTY && inode->i_nlink);
2191         if (!block)
2192                 return;
2193         if ((logfs_super(sb)->s_flags & LOGFS_SB_FLAG_SHUTDOWN)) {
2194                 block->ops->free_block(inode->i_sb, block);
2195                 return;
2196         }
2197
2198         page = inode_to_page(inode);
2199         BUG_ON(!page); /* FIXME: Use emergency page */
2200         logfs_put_write_page(page);
2201 }
2202
2203 void btree_write_block(struct logfs_block *block)
2204 {
2205         struct inode *inode;
2206         struct page *page;
2207         int err, cookie;
2208
2209         inode = logfs_safe_iget(block->sb, block->ino, &cookie);
2210         page = logfs_get_write_page(inode, block->bix, block->level);
2211
2212         err = logfs_readpage_nolock(page);
2213         BUG_ON(err);
2214         BUG_ON(!PagePrivate(page));
2215         BUG_ON(logfs_block(page) != block);
2216         err = __logfs_write_buf(inode, page, 0);
2217         BUG_ON(err);
2218         BUG_ON(PagePrivate(page) || page->private);
2219
2220         logfs_put_write_page(page);
2221         logfs_safe_iput(inode, cookie);
2222 }
2223
2224 /**
2225  * logfs_inode_write - write inode or dentry objects
2226  *
2227  * @inode:              parent inode (ifile or directory)
2228  * @buf:                object to write (inode or dentry)
2229  * @count:              object size
2230  * @bix:                block index
2231  * @flags:              write flags
2232  * @shadow_tree:        shadow below this inode
2233  *
2234  * FIXME: All caller of this put a 200-300 byte variable on the stack,
2235  * only to call here and do a memcpy from that stack variable.  A good
2236  * example of wasted performance and stack space.
2237  */
2238 int logfs_inode_write(struct inode *inode, const void *buf, size_t count,
2239                 loff_t bix, long flags, struct shadow_tree *shadow_tree)
2240 {
2241         loff_t pos = bix << inode->i_sb->s_blocksize_bits;
2242         int err;
2243         struct page *page;
2244         void *pagebuf;
2245
2246         BUG_ON(pos & (LOGFS_BLOCKSIZE-1));
2247         BUG_ON(count > LOGFS_BLOCKSIZE);
2248         page = logfs_get_write_page(inode, bix, 0);
2249         if (!page)
2250                 return -ENOMEM;
2251
2252         pagebuf = kmap_atomic(page);
2253         memcpy(pagebuf, buf, count);
2254         flush_dcache_page(page);
2255         kunmap_atomic(pagebuf);
2256
2257         if (i_size_read(inode) < pos + LOGFS_BLOCKSIZE)
2258                 i_size_write(inode, pos + LOGFS_BLOCKSIZE);
2259
2260         err = logfs_write_buf(inode, page, flags);
2261         logfs_put_write_page(page);
2262         return err;
2263 }
2264
2265 int logfs_open_segfile(struct super_block *sb)
2266 {
2267         struct logfs_super *super = logfs_super(sb);
2268         struct inode *inode;
2269
2270         inode = logfs_read_meta_inode(sb, LOGFS_INO_SEGFILE);
2271         if (IS_ERR(inode))
2272                 return PTR_ERR(inode);
2273         super->s_segfile_inode = inode;
2274         return 0;
2275 }
2276
2277 int logfs_init_rw(struct super_block *sb)
2278 {
2279         struct logfs_super *super = logfs_super(sb);
2280         int min_fill = 3 * super->s_no_blocks;
2281
2282         INIT_LIST_HEAD(&super->s_object_alias);
2283         INIT_LIST_HEAD(&super->s_writeback_list);
2284         mutex_init(&super->s_write_mutex);
2285         super->s_block_pool = mempool_create_kmalloc_pool(min_fill,
2286                         sizeof(struct logfs_block));
2287         super->s_shadow_pool = mempool_create_kmalloc_pool(min_fill,
2288                         sizeof(struct logfs_shadow));
2289         return 0;
2290 }
2291
2292 void logfs_cleanup_rw(struct super_block *sb)
2293 {
2294         struct logfs_super *super = logfs_super(sb);
2295
2296         logfs_mempool_destroy(super->s_block_pool);
2297         logfs_mempool_destroy(super->s_shadow_pool);
2298 }