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   1 /*
   2  * recovery.c - NILFS recovery logic
   3  *
   4  * Copyright (C) 2005-2008 Nippon Telegraph and Telephone Corporation.
   5  *
   6  * This program is free software; you can redistribute it and/or modify
   7  * it under the terms of the GNU General Public License as published by
   8  * the Free Software Foundation; either version 2 of the License, or
   9  * (at your option) any later version.
  10  *
  11  * This program is distributed in the hope that it will be useful,
  12  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14  * GNU General Public License for more details.
  15  *
  16  * You should have received a copy of the GNU General Public License
  17  * along with this program; if not, write to the Free Software
  18  * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
  19  *
  20  * Written by Ryusuke Konishi <ryusuke@osrg.net>
  21  */
  22
  23 #include <linux/buffer_head.h>
  24 #include <linux/blkdev.h>
  25 #include <linux/swap.h>
  26 #include <linux/crc32.h>
  27 #include "nilfs.h"
  28 #include "segment.h"
  29 #include "sufile.h"
  30 #include "page.h"
  31 #include "segbuf.h"
  32
  33 /*
  34  * Segment check result
  35  */
  36 enum {
  37         NILFS_SEG_VALID,
  38         NILFS_SEG_NO_SUPER_ROOT,
  39         NILFS_SEG_FAIL_IO,
  40         NILFS_SEG_FAIL_MAGIC,
  41         NILFS_SEG_FAIL_SEQ,
  42         NILFS_SEG_FAIL_CHECKSUM_SEGSUM,
  43         NILFS_SEG_FAIL_CHECKSUM_SUPER_ROOT,
  44         NILFS_SEG_FAIL_CHECKSUM_FULL,
  45         NILFS_SEG_FAIL_CONSISTENCY,
  46 };
  47
  48 /* work structure for recovery */
  49 struct nilfs_recovery_block {
  50         ino_t ino;              /* Inode number of the file that this block
  51                                    belongs to */
  52         sector_t blocknr;       /* block number */
  53         __u64 vblocknr;         /* virtual block number */
  54         unsigned long blkoff;   /* File offset of the data block (per block) */
  55         struct list_head list;
  56 };
  57
  58
  59 static int nilfs_warn_segment_error(int err)
  60 {
  61         switch (err) {
  62         case NILFS_SEG_FAIL_IO:
  63                 printk(KERN_WARNING
  64                        "NILFS warning: I/O error on loading last segment\n");
  65                 return -EIO;
  66         case NILFS_SEG_FAIL_MAGIC:
  67                 printk(KERN_WARNING
  68                        "NILFS warning: Segment magic number invalid\n");
  69                 break;
  70         case NILFS_SEG_FAIL_SEQ:
  71                 printk(KERN_WARNING
  72                        "NILFS warning: Sequence number mismatch\n");
  73                 break;
  74         case NILFS_SEG_FAIL_CHECKSUM_SEGSUM:
  75                 printk(KERN_WARNING
  76                        "NILFS warning: Checksum error in segment summary\n");
  77                 break;
  78         case NILFS_SEG_FAIL_CHECKSUM_SUPER_ROOT:
  79                 printk(KERN_WARNING
  80                        "NILFS warning: Checksum error in super root\n");
  81                 break;
  82         case NILFS_SEG_FAIL_CHECKSUM_FULL:
  83                 printk(KERN_WARNING
  84                        "NILFS warning: Checksum error in segment payload\n");
  85                 break;
  86         case NILFS_SEG_FAIL_CONSISTENCY:
  87                 printk(KERN_WARNING
  88                        "NILFS warning: Inconsistent segment\n");
  89                 break;
  90         case NILFS_SEG_NO_SUPER_ROOT:
  91                 printk(KERN_WARNING
  92                        "NILFS warning: No super root in the last segment\n");
  93                 break;
  94         }
  95         return -EINVAL;
  96 }
  97
  98 static void store_segsum_info(struct nilfs_segsum_info *ssi,
  99                               struct nilfs_segment_summary *sum,
 100                               unsigned int blocksize)
 101 {
 102         ssi->flags = le16_to_cpu(sum->ss_flags);
 103         ssi->seg_seq = le64_to_cpu(sum->ss_seq);
 104         ssi->ctime = le64_to_cpu(sum->ss_create);
 105         ssi->next = le64_to_cpu(sum->ss_next);
 106         ssi->nblocks = le32_to_cpu(sum->ss_nblocks);
 107         ssi->nfinfo = le32_to_cpu(sum->ss_nfinfo);
 108         ssi->sumbytes = le32_to_cpu(sum->ss_sumbytes);
 109
 110         ssi->nsumblk = DIV_ROUND_UP(ssi->sumbytes, blocksize);
 111         ssi->nfileblk = ssi->nblocks - ssi->nsumblk - !!NILFS_SEG_HAS_SR(ssi);
 112 }
 113
 114 /**
 115  * calc_crc_cont - check CRC of blocks continuously
 116  * @sbi: nilfs_sb_info
 117  * @bhs: buffer head of start block
 118  * @sum: place to store result
 119  * @offset: offset bytes in the first block
 120  * @check_bytes: number of bytes to be checked
 121  * @start: DBN of start block
 122  * @nblock: number of blocks to be checked
 123  */
 124 static int calc_crc_cont(struct nilfs_sb_info *sbi, struct buffer_head *bhs,
 125                          u32 *sum, unsigned long offset, u64 check_bytes,
 126                          sector_t start, unsigned long nblock)
 127 {
 128         unsigned long blocksize = sbi->s_super->s_blocksize;
 129         unsigned long size;
 130         u32 crc;
 131
 132         BUG_ON(offset >= blocksize);
 133         check_bytes -= offset;
 134         size = min_t(u64, check_bytes, blocksize - offset);
 135         crc = crc32_le(sbi->s_nilfs->ns_crc_seed,
 136                        (unsigned char *)bhs->b_data + offset, size);
 137         if (--nblock > 0) {
 138                 do {
 139                         struct buffer_head *bh
 140                                 = sb_bread(sbi->s_super, ++start);
 141                         if (!bh)
 142                                 return -EIO;
 143                         check_bytes -= size;
 144                         size = min_t(u64, check_bytes, blocksize);
 145                         crc = crc32_le(crc, bh->b_data, size);
 146                         brelse(bh);
 147                 } while (--nblock > 0);
 148         }
 149         *sum = crc;
 150         return 0;
 151 }
 152
 153 /**
 154  * nilfs_read_super_root_block - read super root block
 155  * @sb: super_block
 156  * @sr_block: disk block number of the super root block
 157  * @pbh: address of a buffer_head pointer to return super root buffer
 158  * @check: CRC check flag
 159  */
 160 int nilfs_read_super_root_block(struct super_block *sb, sector_t sr_block,
 161                                 struct buffer_head **pbh, int check)
 162 {
 163         struct buffer_head *bh_sr;
 164         struct nilfs_super_root *sr;
 165         u32 crc;
 166         int ret;
 167
 168         *pbh = NULL;
 169         bh_sr = sb_bread(sb, sr_block);
 170         if (unlikely(!bh_sr)) {
 171                 ret = NILFS_SEG_FAIL_IO;
 172                 goto failed;
 173         }
 174
 175         sr = (struct nilfs_super_root *)bh_sr->b_data;
 176         if (check) {
 177                 unsigned bytes = le16_to_cpu(sr->sr_bytes);
 178
 179                 if (bytes == 0 || bytes > sb->s_blocksize) {
 180                         ret = NILFS_SEG_FAIL_CHECKSUM_SUPER_ROOT;
 181                         goto failed_bh;
 182                 }
 183                 if (calc_crc_cont(NILFS_SB(sb), bh_sr, &crc,
 184                                   sizeof(sr->sr_sum), bytes, sr_block, 1)) {
 185                         ret = NILFS_SEG_FAIL_IO;
 186                         goto failed_bh;
 187                 }
 188                 if (crc != le32_to_cpu(sr->sr_sum)) {
 189                         ret = NILFS_SEG_FAIL_CHECKSUM_SUPER_ROOT;
 190                         goto failed_bh;
 191                 }
 192         }
 193         *pbh = bh_sr;
 194         return 0;
 195
 196  failed_bh:
 197         brelse(bh_sr);
 198
 199  failed:
 200         return nilfs_warn_segment_error(ret);
 201 }
 202
 203 /**
 204  * load_segment_summary - read segment summary of the specified partial segment
 205  * @sbi: nilfs_sb_info
 206  * @pseg_start: start disk block number of partial segment
 207  * @seg_seq: sequence number requested
 208  * @ssi: pointer to nilfs_segsum_info struct to store information
 209  * @full_check: full check flag
 210  *              (0: only checks segment summary CRC, 1: data CRC)
 211  */
 212 static int
 213 load_segment_summary(struct nilfs_sb_info *sbi, sector_t pseg_start,
 214                      u64 seg_seq, struct nilfs_segsum_info *ssi,
 215                      int full_check)
 216 {
 217         struct buffer_head *bh_sum;
 218         struct nilfs_segment_summary *sum;
 219         unsigned long offset, nblock;
 220         u64 check_bytes;
 221         u32 crc, crc_sum;
 222         int ret = NILFS_SEG_FAIL_IO;
 223
 224         bh_sum = sb_bread(sbi->s_super, pseg_start);
 225         if (!bh_sum)
 226                 goto out;
 227
 228         sum = (struct nilfs_segment_summary *)bh_sum->b_data;
 229
 230         /* Check consistency of segment summary */
 231         if (le32_to_cpu(sum->ss_magic) != NILFS_SEGSUM_MAGIC) {
 232                 ret = NILFS_SEG_FAIL_MAGIC;
 233                 goto failed;
 234         }
 235         store_segsum_info(ssi, sum, sbi->s_super->s_blocksize);
 236         if (seg_seq != ssi->seg_seq) {
 237                 ret = NILFS_SEG_FAIL_SEQ;
 238                 goto failed;
 239         }
 240         if (full_check) {
 241                 offset = sizeof(sum->ss_datasum);
 242                 check_bytes =
 243                         ((u64)ssi->nblocks << sbi->s_super->s_blocksize_bits);
 244                 nblock = ssi->nblocks;
 245                 crc_sum = le32_to_cpu(sum->ss_datasum);
 246                 ret = NILFS_SEG_FAIL_CHECKSUM_FULL;
 247         } else { /* only checks segment summary */
 248                 offset = sizeof(sum->ss_datasum) + sizeof(sum->ss_sumsum);
 249                 check_bytes = ssi->sumbytes;
 250                 nblock = ssi->nsumblk;
 251                 crc_sum = le32_to_cpu(sum->ss_sumsum);
 252                 ret = NILFS_SEG_FAIL_CHECKSUM_SEGSUM;
 253         }
 254
 255         if (unlikely(nblock == 0 ||
 256                      nblock > sbi->s_nilfs->ns_blocks_per_segment)) {
 257                 /* This limits the number of blocks read in the CRC check */
 258                 ret = NILFS_SEG_FAIL_CONSISTENCY;
 259                 goto failed;
 260         }
 261         if (calc_crc_cont(sbi, bh_sum, &crc, offset, check_bytes,
 262                           pseg_start, nblock)) {
 263                 ret = NILFS_SEG_FAIL_IO;
 264                 goto failed;
 265         }
 266         if (crc == crc_sum)
 267                 ret = 0;
 268  failed:
 269         brelse(bh_sum);
 270  out:
 271         return ret;
 272 }
 273
 274 static void *segsum_get(struct super_block *sb, struct buffer_head **pbh,
 275                         unsigned int *offset, unsigned int bytes)
 276 {
 277         void *ptr;
 278         sector_t blocknr;
 279
 280         BUG_ON((*pbh)->b_size < *offset);
 281         if (bytes > (*pbh)->b_size - *offset) {
 282                 blocknr = (*pbh)->b_blocknr;
 283                 brelse(*pbh);
 284                 *pbh = sb_bread(sb, blocknr + 1);
 285                 if (unlikely(!*pbh))
 286                         return NULL;
 287                 *offset = 0;
 288         }
 289         ptr = (*pbh)->b_data + *offset;
 290         *offset += bytes;
 291         return ptr;
 292 }
 293
 294 static void segsum_skip(struct super_block *sb, struct buffer_head **pbh,
 295                         unsigned int *offset, unsigned int bytes,
 296                         unsigned long count)
 297 {
 298         unsigned int rest_item_in_current_block
 299                 = ((*pbh)->b_size - *offset) / bytes;
 300
 301         if (count <= rest_item_in_current_block) {
 302                 *offset += bytes * count;
 303         } else {
 304                 sector_t blocknr = (*pbh)->b_blocknr;
 305                 unsigned int nitem_per_block = (*pbh)->b_size / bytes;
 306                 unsigned int bcnt;
 307
 308                 count -= rest_item_in_current_block;
 309                 bcnt = DIV_ROUND_UP(count, nitem_per_block);
 310                 *offset = bytes * (count - (bcnt - 1) * nitem_per_block);
 311
 312                 brelse(*pbh);
 313                 *pbh = sb_bread(sb, blocknr + bcnt);
 314         }
 315 }
 316
 317 static int
 318 collect_blocks_from_segsum(struct nilfs_sb_info *sbi, sector_t sum_blocknr,
 319                            struct nilfs_segsum_info *ssi,
 320                            struct list_head *head)
 321 {
 322         struct buffer_head *bh;
 323         unsigned int offset;
 324         unsigned long nfinfo = ssi->nfinfo;
 325         sector_t blocknr = sum_blocknr + ssi->nsumblk;
 326         ino_t ino;
 327         int err = -EIO;
 328
 329         if (!nfinfo)
 330                 return 0;
 331
 332         bh = sb_bread(sbi->s_super, sum_blocknr);
 333         if (unlikely(!bh))
 334                 goto out;
 335
 336         offset = le16_to_cpu(
 337                 ((struct nilfs_segment_summary *)bh->b_data)->ss_bytes);
 338         for (;;) {
 339                 unsigned long nblocks, ndatablk, nnodeblk;
 340                 struct nilfs_finfo *finfo;
 341
 342                 finfo = segsum_get(sbi->s_super, &bh, &offset, sizeof(*finfo));
 343                 if (unlikely(!finfo))
 344                         goto out;
 345
 346                 ino = le64_to_cpu(finfo->fi_ino);
 347                 nblocks = le32_to_cpu(finfo->fi_nblocks);
 348                 ndatablk = le32_to_cpu(finfo->fi_ndatablk);
 349                 nnodeblk = nblocks - ndatablk;
 350
 351                 while (ndatablk-- > 0) {
 352                         struct nilfs_recovery_block *rb;
 353                         struct nilfs_binfo_v *binfo;
 354
 355                         binfo = segsum_get(sbi->s_super, &bh, &offset,
 356                                            sizeof(*binfo));
 357                         if (unlikely(!binfo))
 358                                 goto out;
 359
 360                         rb = kmalloc(sizeof(*rb), GFP_NOFS);
 361                         if (unlikely(!rb)) {
 362                                 err = -ENOMEM;
 363                                 goto out;
 364                         }
 365                         rb->ino = ino;
 366                         rb->blocknr = blocknr++;
 367                         rb->vblocknr = le64_to_cpu(binfo->bi_vblocknr);
 368                         rb->blkoff = le64_to_cpu(binfo->bi_blkoff);
 369                         /* INIT_LIST_HEAD(&rb->list); */
 370                         list_add_tail(&rb->list, head);
 371                 }
 372                 if (--nfinfo == 0)
 373                         break;
 374                 blocknr += nnodeblk; /* always 0 for the data sync segments */
 375                 segsum_skip(sbi->s_super, &bh, &offset, sizeof(__le64),
 376                             nnodeblk);
 377                 if (unlikely(!bh))
 378                         goto out;
 379         }
 380         err = 0;
 381  out:
 382         brelse(bh);   /* brelse(NULL) is just ignored */
 383         return err;
 384 }
 385
 386 static void dispose_recovery_list(struct list_head *head)
 387 {
 388         while (!list_empty(head)) {
 389                 struct nilfs_recovery_block *rb
 390                         = list_entry(head->next,
 391                                      struct nilfs_recovery_block, list);
 392                 list_del(&rb->list);
 393                 kfree(rb);
 394         }
 395 }
 396
 397 struct nilfs_segment_entry {
 398         struct list_head        list;
 399         __u64                   segnum;
 400 };
 401
 402 static int nilfs_segment_list_add(struct list_head *head, __u64 segnum)
 403 {
 404         struct nilfs_segment_entry *ent = kmalloc(sizeof(*ent), GFP_NOFS);
 405
 406         if (unlikely(!ent))
 407                 return -ENOMEM;
 408
 409         ent->segnum = segnum;
 410         INIT_LIST_HEAD(&ent->list);
 411         list_add_tail(&ent->list, head);
 412         return 0;
 413 }
 414
 415 void nilfs_dispose_segment_list(struct list_head *head)
 416 {
 417         while (!list_empty(head)) {
 418                 struct nilfs_segment_entry *ent
 419                         = list_entry(head->next,
 420                                      struct nilfs_segment_entry, list);
 421                 list_del(&ent->list);
 422                 kfree(ent);
 423         }
 424 }
 425
 426 static int nilfs_prepare_segment_for_recovery(struct the_nilfs *nilfs,
 427                                               struct nilfs_sb_info *sbi,
 428                                               struct nilfs_recovery_info *ri)
 429 {
 430         struct list_head *head = &ri->ri_used_segments;
 431         struct nilfs_segment_entry *ent, *n;
 432         struct inode *sufile = nilfs->ns_sufile;
 433         __u64 segnum[4];
 434         int err;
 435         int i;
 436
 437         segnum[0] = nilfs->ns_segnum;
 438         segnum[1] = nilfs->ns_nextnum;
 439         segnum[2] = ri->ri_segnum;
 440         segnum[3] = ri->ri_nextnum;
 441
 442         nilfs_attach_writer(nilfs, sbi);
 443         /*
 444          * Releasing the next segment of the latest super root.
 445          * The next segment is invalidated by this recovery.
 446          */
 447         err = nilfs_sufile_free(sufile, segnum[1]);
 448         if (unlikely(err))
 449                 goto failed;
 450
 451         for (i = 1; i < 4; i++) {
 452                 err = nilfs_segment_list_add(head, segnum[i]);
 453                 if (unlikely(err))
 454                         goto failed;
 455         }
 456
 457         /*
 458          * Collecting segments written after the latest super root.
 459          * These are marked dirty to avoid being reallocated in the next write.
 460          */
 461         list_for_each_entry_safe(ent, n, head, list) {
 462                 if (ent->segnum != segnum[0]) {
 463                         err = nilfs_sufile_scrap(sufile, ent->segnum);
 464                         if (unlikely(err))
 465                                 goto failed;
 466                 }
 467                 list_del(&ent->list);
 468                 kfree(ent);
 469         }
 470
 471         /* Allocate new segments for recovery */
 472         err = nilfs_sufile_alloc(sufile, &segnum[0]);
 473         if (unlikely(err))
 474                 goto failed;
 475
 476         nilfs->ns_pseg_offset = 0;
 477         nilfs->ns_seg_seq = ri->ri_seq + 2;
 478         nilfs->ns_nextnum = nilfs->ns_segnum = segnum[0];
 479
 480  failed:
 481         /* No need to recover sufile because it will be destroyed on error */
 482         nilfs_detach_writer(nilfs, sbi);
 483         return err;
 484 }
 485
 486 static int nilfs_recovery_copy_block(struct nilfs_sb_info *sbi,
 487                                      struct nilfs_recovery_block *rb,
 488                                      struct page *page)
 489 {
 490         struct buffer_head *bh_org;
 491         void *kaddr;
 492
 493         bh_org = sb_bread(sbi->s_super, rb->blocknr);
 494         if (unlikely(!bh_org))
 495                 return -EIO;
 496
 497         kaddr = kmap_atomic(page, KM_USER0);
 498         memcpy(kaddr + bh_offset(bh_org), bh_org->b_data, bh_org->b_size);
 499         kunmap_atomic(kaddr, KM_USER0);
 500         brelse(bh_org);
 501         return 0;
 502 }
 503
 504 static int recover_dsync_blocks(struct nilfs_sb_info *sbi,
 505                                 struct list_head *head,
 506                                 unsigned long *nr_salvaged_blocks)
 507 {
 508         struct inode *inode;
 509         struct nilfs_recovery_block *rb, *n;
 510         unsigned blocksize = sbi->s_super->s_blocksize;
 511         struct page *page;
 512         loff_t pos;
 513         int err = 0, err2 = 0;
 514
 515         list_for_each_entry_safe(rb, n, head, list) {
 516                 inode = nilfs_iget(sbi->s_super, rb->ino);
 517                 if (IS_ERR(inode)) {
 518                         err = PTR_ERR(inode);
 519                         inode = NULL;
 520                         goto failed_inode;
 521                 }
 522
 523                 pos = rb->blkoff << inode->i_blkbits;
 524                 page = NULL;
 525                 err = block_write_begin(NULL, inode->i_mapping, pos, blocksize,
 526                                         0, &page, NULL, nilfs_get_block);
 527                 if (unlikely(err))
 528                         goto failed_inode;
 529
 530                 err = nilfs_recovery_copy_block(sbi, rb, page);
 531                 if (unlikely(err))
 532                         goto failed_page;
 533
 534                 err = nilfs_set_file_dirty(sbi, inode, 1);
 535                 if (unlikely(err))
 536                         goto failed_page;
 537
 538                 block_write_end(NULL, inode->i_mapping, pos, blocksize,
 539                                 blocksize, page, NULL);
 540
 541                 unlock_page(page);
 542                 page_cache_release(page);
 543
 544                 (*nr_salvaged_blocks)++;
 545                 goto next;
 546
 547  failed_page:
 548                 unlock_page(page);
 549                 page_cache_release(page);
 550
 551  failed_inode:
 552                 printk(KERN_WARNING
 553                        "NILFS warning: error recovering data block "
 554                        "(err=%d, ino=%lu, block-offset=%llu)\n",
 555                        err, (unsigned long)rb->ino,
 556                        (unsigned long long)rb->blkoff);
 557                 if (!err2)
 558                         err2 = err;
 559  next:
 560                 iput(inode); /* iput(NULL) is just ignored */
 561                 list_del_init(&rb->list);
 562                 kfree(rb);
 563         }
 564         return err2;
 565 }
 566
 567 /**
 568  * nilfs_do_roll_forward - salvage logical segments newer than the latest
 569  * checkpoint
 570  * @sbi: nilfs_sb_info
 571  * @nilfs: the_nilfs
 572  * @ri: pointer to a nilfs_recovery_info
 573  */
 574 static int nilfs_do_roll_forward(struct the_nilfs *nilfs,
 575                                  struct nilfs_sb_info *sbi,
 576                                  struct nilfs_recovery_info *ri)
 577 {
 578         struct nilfs_segsum_info ssi;
 579         sector_t pseg_start;
 580         sector_t seg_start, seg_end;  /* Starting/ending DBN of full segment */
 581         unsigned long nsalvaged_blocks = 0;
 582         u64 seg_seq;
 583         __u64 segnum, nextnum = 0;
 584         int empty_seg = 0;
 585         int err = 0, ret;
 586         LIST_HEAD(dsync_blocks);  /* list of data blocks to be recovered */
 587         enum {
 588                 RF_INIT_ST,
 589                 RF_DSYNC_ST,   /* scanning data-sync segments */
 590         };
 591         int state = RF_INIT_ST;
 592
 593         nilfs_attach_writer(nilfs, sbi);
 594         pseg_start = ri->ri_lsegs_start;
 595         seg_seq = ri->ri_lsegs_start_seq;
 596         segnum = nilfs_get_segnum_of_block(nilfs, pseg_start);
 597         nilfs_get_segment_range(nilfs, segnum, &seg_start, &seg_end);
 598
 599         while (segnum != ri->ri_segnum || pseg_start <= ri->ri_pseg_start) {
 600
 601                 ret = load_segment_summary(sbi, pseg_start, seg_seq, &ssi, 1);
 602                 if (ret) {
 603                         if (ret == NILFS_SEG_FAIL_IO) {
 604                                 err = -EIO;
 605                                 goto failed;
 606                         }
 607                         goto strayed;
 608                 }
 609                 if (unlikely(NILFS_SEG_HAS_SR(&ssi)))
 610                         goto confused;
 611
 612                 /* Found a valid partial segment; do recovery actions */
 613                 nextnum = nilfs_get_segnum_of_block(nilfs, ssi.next);
 614                 empty_seg = 0;
 615                 nilfs->ns_ctime = ssi.ctime;
 616                 if (!(ssi.flags & NILFS_SS_GC))
 617                         nilfs->ns_nongc_ctime = ssi.ctime;
 618
 619                 switch (state) {
 620                 case RF_INIT_ST:
 621                         if (!NILFS_SEG_LOGBGN(&ssi) || !NILFS_SEG_DSYNC(&ssi))
 622                                 goto try_next_pseg;
 623                         state = RF_DSYNC_ST;
 624                         /* Fall through */
 625                 case RF_DSYNC_ST:
 626                         if (!NILFS_SEG_DSYNC(&ssi))
 627                                 goto confused;
 628
 629                         err = collect_blocks_from_segsum(
 630                                 sbi, pseg_start, &ssi, &dsync_blocks);
 631                         if (unlikely(err))
 632                                 goto failed;
 633                         if (NILFS_SEG_LOGEND(&ssi)) {
 634                                 err = recover_dsync_blocks(
 635                                         sbi, &dsync_blocks, &nsalvaged_blocks);
 636                                 if (unlikely(err))
 637                                         goto failed;
 638                                 state = RF_INIT_ST;
 639                         }
 640                         break; /* Fall through to try_next_pseg */
 641                 }
 642
 643  try_next_pseg:
 644                 if (pseg_start == ri->ri_lsegs_end)
 645                         break;
 646                 pseg_start += ssi.nblocks;
 647                 if (pseg_start < seg_end)
 648                         continue;
 649                 goto feed_segment;
 650
 651  strayed:
 652                 if (pseg_start == ri->ri_lsegs_end)
 653                         break;
 654
 655  feed_segment:
 656                 /* Looking to the next full segment */
 657                 if (empty_seg++)
 658                         break;
 659                 seg_seq++;
 660                 segnum = nextnum;
 661                 nilfs_get_segment_range(nilfs, segnum, &seg_start, &seg_end);
 662                 pseg_start = seg_start;
 663         }
 664
 665         if (nsalvaged_blocks) {
 666                 printk(KERN_INFO "NILFS (device %s): salvaged %lu blocks\n",
 667                        sbi->s_super->s_id, nsalvaged_blocks);
 668                 ri->ri_need_recovery = NILFS_RECOVERY_ROLLFORWARD_DONE;
 669         }
 670  out:
 671         dispose_recovery_list(&dsync_blocks);
 672         nilfs_detach_writer(sbi->s_nilfs, sbi);
 673         return err;
 674
 675  confused:
 676         err = -EINVAL;
 677  failed:
 678         printk(KERN_ERR
 679                "NILFS (device %s): Error roll-forwarding "
 680                "(err=%d, pseg block=%llu). ",
 681                sbi->s_super->s_id, err, (unsigned long long)pseg_start);
 682         goto out;
 683 }
 684
 685 static void nilfs_finish_roll_forward(struct the_nilfs *nilfs,
 686                                       struct nilfs_sb_info *sbi,
 687                                       struct nilfs_recovery_info *ri)
 688 {
 689         struct buffer_head *bh;
 690         int err;
 691
 692         if (nilfs_get_segnum_of_block(nilfs, ri->ri_lsegs_start) !=
 693             nilfs_get_segnum_of_block(nilfs, ri->ri_super_root))
 694                 return;
 695
 696         bh = sb_getblk(sbi->s_super, ri->ri_lsegs_start);
 697         BUG_ON(!bh);
 698         memset(bh->b_data, 0, bh->b_size);
 699         set_buffer_dirty(bh);
 700         err = sync_dirty_buffer(bh);
 701         if (unlikely(err))
 702                 printk(KERN_WARNING
 703                        "NILFS warning: buffer sync write failed during "
 704                        "post-cleaning of recovery.\n");
 705         brelse(bh);
 706 }
 707
 708 /**
 709  * nilfs_recover_logical_segments - salvage logical segments written after
 710  * the latest super root
 711  * @nilfs: the_nilfs
 712  * @sbi: nilfs_sb_info
 713  * @ri: pointer to a nilfs_recovery_info struct to store search results.
 714  *
 715  * Return Value: On success, 0 is returned.  On error, one of the following
 716  * negative error code is returned.
 717  *
 718  * %-EINVAL - Inconsistent filesystem state.
 719  *
 720  * %-EIO - I/O error
 721  *
 722  * %-ENOSPC - No space left on device (only in a panic state).
 723  *
 724  * %-ERESTARTSYS - Interrupted.
 725  *
 726  * %-ENOMEM - Insufficient memory available.
 727  */
 728 int nilfs_recover_logical_segments(struct the_nilfs *nilfs,
 729                                    struct nilfs_sb_info *sbi,
 730                                    struct nilfs_recovery_info *ri)
 731 {
 732         int err;
 733
 734         if (ri->ri_lsegs_start == 0 || ri->ri_lsegs_end == 0)
 735                 return 0;
 736
 737         err = nilfs_attach_checkpoint(sbi, ri->ri_cno);
 738         if (unlikely(err)) {
 739                 printk(KERN_ERR
 740                        "NILFS: error loading the latest checkpoint.\n");
 741                 return err;
 742         }
 743
 744         err = nilfs_do_roll_forward(nilfs, sbi, ri);
 745         if (unlikely(err))
 746                 goto failed;
 747
 748         if (ri->ri_need_recovery == NILFS_RECOVERY_ROLLFORWARD_DONE) {
 749                 err = nilfs_prepare_segment_for_recovery(nilfs, sbi, ri);
 750                 if (unlikely(err)) {
 751                         printk(KERN_ERR "NILFS: Error preparing segments for "
 752                                "recovery.\n");
 753                         goto failed;
 754                 }
 755
 756                 err = nilfs_attach_segment_constructor(sbi);
 757                 if (unlikely(err))
 758                         goto failed;
 759
 760                 set_nilfs_discontinued(nilfs);
 761                 err = nilfs_construct_segment(sbi->s_super);
 762                 nilfs_detach_segment_constructor(sbi);
 763
 764                 if (unlikely(err)) {
 765                         printk(KERN_ERR "NILFS: Oops! recovery failed. "
 766                                "(err=%d)\n", err);
 767                         goto failed;
 768                 }
 769
 770                 nilfs_finish_roll_forward(nilfs, sbi, ri);
 771         }
 772
 773  failed:
 774         nilfs_detach_checkpoint(sbi);
 775         return err;
 776 }
 777
 778 /**
 779  * nilfs_search_super_root - search the latest valid super root
 780  * @nilfs: the_nilfs
 781  * @sbi: nilfs_sb_info
 782  * @ri: pointer to a nilfs_recovery_info struct to store search results.
 783  *
 784  * nilfs_search_super_root() looks for the latest super-root from a partial
 785  * segment pointed by the superblock.  It sets up struct the_nilfs through
 786  * this search. It fills nilfs_recovery_info (ri) required for recovery.
 787  *
 788  * Return Value: On success, 0 is returned.  On error, one of the following
 789  * negative error code is returned.
 790  *
 791  * %-EINVAL - No valid segment found
 792  *
 793  * %-EIO - I/O error
 794  */
 795 int nilfs_search_super_root(struct the_nilfs *nilfs, struct nilfs_sb_info *sbi,
 796                             struct nilfs_recovery_info *ri)
 797 {
 798         struct nilfs_segsum_info ssi;
 799         sector_t pseg_start, pseg_end, sr_pseg_start = 0;
 800         sector_t seg_start, seg_end; /* range of full segment (block number) */
 801         sector_t b, end;
 802         u64 seg_seq;
 803         __u64 segnum, nextnum = 0;
 804         __u64 cno;
 805         LIST_HEAD(segments);
 806         int empty_seg = 0, scan_newer = 0;
 807         int ret;
 808
 809         pseg_start = nilfs->ns_last_pseg;
 810         seg_seq = nilfs->ns_last_seq;
 811         cno = nilfs->ns_last_cno;
 812         segnum = nilfs_get_segnum_of_block(nilfs, pseg_start);
 813
 814         /* Calculate range of segment */
 815         nilfs_get_segment_range(nilfs, segnum, &seg_start, &seg_end);
 816
 817         /* Read ahead segment */
 818         b = seg_start;
 819         while (b <= seg_end)
 820                 sb_breadahead(sbi->s_super, b++);
 821
 822         for (;;) {
 823                 /* Load segment summary */
 824                 ret = load_segment_summary(sbi, pseg_start, seg_seq, &ssi, 1);
 825                 if (ret) {
 826                         if (ret == NILFS_SEG_FAIL_IO)
 827                                 goto failed;
 828                         goto strayed;
 829                 }
 830                 pseg_end = pseg_start + ssi.nblocks - 1;
 831                 if (unlikely(pseg_end > seg_end)) {
 832                         ret = NILFS_SEG_FAIL_CONSISTENCY;
 833                         goto strayed;
 834                 }
 835
 836                 /* A valid partial segment */
 837                 ri->ri_pseg_start = pseg_start;
 838                 ri->ri_seq = seg_seq;
 839                 ri->ri_segnum = segnum;
 840                 nextnum = nilfs_get_segnum_of_block(nilfs, ssi.next);
 841                 ri->ri_nextnum = nextnum;
 842                 empty_seg = 0;
 843
 844                 if (!NILFS_SEG_HAS_SR(&ssi) && !scan_newer) {
 845                         /* This will never happen because a superblock
 846                            (last_segment) always points to a pseg
 847                            having a super root. */
 848                         ret = NILFS_SEG_FAIL_CONSISTENCY;
 849                         goto failed;
 850                 }
 851
 852                 if (pseg_start == seg_start) {
 853                         nilfs_get_segment_range(nilfs, nextnum, &b, &end);
 854                         while (b <= end)
 855                                 sb_breadahead(sbi->s_super, b++);
 856                 }
 857                 if (!NILFS_SEG_HAS_SR(&ssi)) {
 858                         if (!ri->ri_lsegs_start && NILFS_SEG_LOGBGN(&ssi)) {
 859                                 ri->ri_lsegs_start = pseg_start;
 860                                 ri->ri_lsegs_start_seq = seg_seq;
 861                         }
 862                         if (NILFS_SEG_LOGEND(&ssi))
 863                                 ri->ri_lsegs_end = pseg_start;
 864                         goto try_next_pseg;
 865                 }
 866
 867                 /* A valid super root was found. */
 868                 ri->ri_cno = cno++;
 869                 ri->ri_super_root = pseg_end;
 870                 ri->ri_lsegs_start = ri->ri_lsegs_end = 0;
 871
 872                 nilfs_dispose_segment_list(&segments);
 873                 nilfs->ns_pseg_offset = (sr_pseg_start = pseg_start)
 874                         + ssi.nblocks - seg_start;
 875                 nilfs->ns_seg_seq = seg_seq;
 876                 nilfs->ns_segnum = segnum;
 877                 nilfs->ns_cno = cno;  /* nilfs->ns_cno = ri->ri_cno + 1 */
 878                 nilfs->ns_ctime = ssi.ctime;
 879                 nilfs->ns_nextnum = nextnum;
 880
 881                 if (scan_newer)
 882                         ri->ri_need_recovery = NILFS_RECOVERY_SR_UPDATED;
 883                 else {
 884                         if (nilfs->ns_mount_state & NILFS_VALID_FS)
 885                                 goto super_root_found;
 886                         scan_newer = 1;
 887                 }
 888
 889                 /* reset region for roll-forward */
 890                 pseg_start += ssi.nblocks;
 891                 if (pseg_start < seg_end)
 892                         continue;
 893                 goto feed_segment;
 894
 895  try_next_pseg:
 896                 /* Standing on a course, or met an inconsistent state */
 897                 pseg_start += ssi.nblocks;
 898                 if (pseg_start < seg_end)
 899                         continue;
 900                 goto feed_segment;
 901
 902  strayed:
 903                 /* Off the trail */
 904                 if (!scan_newer)
 905                         /*
 906                          * This can happen if a checkpoint was written without
 907                          * barriers, or as a result of an I/O failure.
 908                          */
 909                         goto failed;
 910
 911  feed_segment:
 912                 /* Looking to the next full segment */
 913                 if (empty_seg++)
 914                         goto super_root_found; /* found a valid super root */
 915
 916                 ret = nilfs_segment_list_add(&segments, segnum);
 917                 if (unlikely(ret))
 918                         goto failed;
 919
 920                 seg_seq++;
 921                 segnum = nextnum;
 922                 nilfs_get_segment_range(nilfs, segnum, &seg_start, &seg_end);
 923                 pseg_start = seg_start;
 924         }
 925
 926  super_root_found:
 927         /* Updating pointers relating to the latest checkpoint */
 928         list_splice_tail(&segments, &ri->ri_used_segments);
 929         nilfs->ns_last_pseg = sr_pseg_start;
 930         nilfs->ns_last_seq = nilfs->ns_seg_seq;
 931         nilfs->ns_last_cno = ri->ri_cno;
 932         return 0;
 933
 934  failed:
 935         nilfs_dispose_segment_list(&segments);
 936         return (ret < 0) ? ret : nilfs_warn_segment_error(ret);
 937 }