fs/nilfs2/recovery.c

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