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/slab.h>
  27 #include <linux/crc32.h>
  28 #include "nilfs.h"
  29 #include "segment.h"
  30 #include "sufile.h"
  31 #include "page.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_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_SUPER_ROOT:
  75                 printk(KERN_WARNING
  76                        "NILFS warning: Checksum error in super root\n");
  77                 break;
  78         case NILFS_SEG_FAIL_CHECKSUM_FULL:
  79                 printk(KERN_WARNING
  80                        "NILFS warning: Checksum error in segment payload\n");
  81                 break;
  82         case NILFS_SEG_FAIL_CONSISTENCY:
  83                 printk(KERN_WARNING
  84                        "NILFS warning: Inconsistent segment\n");
  85                 break;
  86         case NILFS_SEG_NO_SUPER_ROOT:
  87                 printk(KERN_WARNING
  88                        "NILFS warning: No super root in the last segment\n");
  89                 break;
  90         }
  91         return -EINVAL;
  92 }
  93
  94 /**
  95  * nilfs_compute_checksum - compute checksum of blocks continuously
  96  * @nilfs: nilfs object
  97  * @bhs: buffer head of start block
  98  * @sum: place to store result
  99  * @offset: offset bytes in the first block
 100  * @check_bytes: number of bytes to be checked
 101  * @start: DBN of start block
 102  * @nblock: number of blocks to be checked
 103  */
 104 static int nilfs_compute_checksum(struct the_nilfs *nilfs,
 105                                   struct buffer_head *bhs, u32 *sum,
 106                                   unsigned long offset, u64 check_bytes,
 107                                   sector_t start, unsigned long nblock)
 108 {
 109         unsigned int blocksize = nilfs->ns_blocksize;
 110         unsigned long size;
 111         u32 crc;
 112
 113         BUG_ON(offset >= blocksize);
 114         check_bytes -= offset;
 115         size = min_t(u64, check_bytes, blocksize - offset);
 116         crc = crc32_le(nilfs->ns_crc_seed,
 117                        (unsigned char *)bhs->b_data + offset, size);
 118         if (--nblock > 0) {
 119                 do {
 120                         struct buffer_head *bh;
 121
 122                         bh = __bread(nilfs->ns_bdev, ++start, blocksize);
 123                         if (!bh)
 124                                 return -EIO;
 125                         check_bytes -= size;
 126                         size = min_t(u64, check_bytes, blocksize);
 127                         crc = crc32_le(crc, bh->b_data, size);
 128                         brelse(bh);
 129                 } while (--nblock > 0);
 130         }
 131         *sum = crc;
 132         return 0;
 133 }
 134
 135 /**
 136  * nilfs_read_super_root_block - read super root block
 137  * @nilfs: nilfs object
 138  * @sr_block: disk block number of the super root block
 139  * @pbh: address of a buffer_head pointer to return super root buffer
 140  * @check: CRC check flag
 141  */
 142 int nilfs_read_super_root_block(struct the_nilfs *nilfs, sector_t sr_block,
 143                                 struct buffer_head **pbh, int check)
 144 {
 145         struct buffer_head *bh_sr;
 146         struct nilfs_super_root *sr;
 147         u32 crc;
 148         int ret;
 149
 150         *pbh = NULL;
 151         bh_sr = __bread(nilfs->ns_bdev, sr_block, nilfs->ns_blocksize);
 152         if (unlikely(!bh_sr)) {
 153                 ret = NILFS_SEG_FAIL_IO;
 154                 goto failed;
 155         }
 156
 157         sr = (struct nilfs_super_root *)bh_sr->b_data;
 158         if (check) {
 159                 unsigned bytes = le16_to_cpu(sr->sr_bytes);
 160
 161                 if (bytes == 0 || bytes > nilfs->ns_blocksize) {
 162                         ret = NILFS_SEG_FAIL_CHECKSUM_SUPER_ROOT;
 163                         goto failed_bh;
 164                 }
 165                 if (nilfs_compute_checksum(
 166                             nilfs, bh_sr, &crc, sizeof(sr->sr_sum), bytes,
 167                             sr_block, 1)) {
 168                         ret = NILFS_SEG_FAIL_IO;
 169                         goto failed_bh;
 170                 }
 171                 if (crc != le32_to_cpu(sr->sr_sum)) {
 172                         ret = NILFS_SEG_FAIL_CHECKSUM_SUPER_ROOT;
 173                         goto failed_bh;
 174                 }
 175         }
 176         *pbh = bh_sr;
 177         return 0;
 178
 179  failed_bh:
 180         brelse(bh_sr);
 181
 182  failed:
 183         return nilfs_warn_segment_error(ret);
 184 }
 185
 186 /**
 187  * nilfs_read_log_header - read summary header of the specified log
 188  * @nilfs: nilfs object
 189  * @start_blocknr: start block number of the log
 190  * @sum: pointer to return segment summary structure
 191  */
 192 static struct buffer_head *
 193 nilfs_read_log_header(struct the_nilfs *nilfs, sector_t start_blocknr,
 194                       struct nilfs_segment_summary **sum)
 195 {
 196         struct buffer_head *bh_sum;
 197
 198         bh_sum = __bread(nilfs->ns_bdev, start_blocknr, nilfs->ns_blocksize);
 199         if (bh_sum)
 200                 *sum = (struct nilfs_segment_summary *)bh_sum->b_data;
 201         return bh_sum;
 202 }
 203
 204 /**
 205  * nilfs_validate_log - verify consistency of log
 206  * @nilfs: nilfs object
 207  * @seg_seq: sequence number of segment
 208  * @bh_sum: buffer head of summary block
 209  * @sum: segment summary struct
 210  */
 211 static int nilfs_validate_log(struct the_nilfs *nilfs, u64 seg_seq,
 212                               struct buffer_head *bh_sum,
 213                               struct nilfs_segment_summary *sum)
 214 {
 215         unsigned long nblock;
 216         u32 crc;
 217         int ret;
 218
 219         ret = NILFS_SEG_FAIL_MAGIC;
 220         if (le32_to_cpu(sum->ss_magic) != NILFS_SEGSUM_MAGIC)
 221                 goto out;
 222
 223         ret = NILFS_SEG_FAIL_SEQ;
 224         if (le64_to_cpu(sum->ss_seq) != seg_seq)
 225                 goto out;
 226
 227         nblock = le32_to_cpu(sum->ss_nblocks);
 228         ret = NILFS_SEG_FAIL_CONSISTENCY;
 229         if (unlikely(nblock == 0 || nblock > nilfs->ns_blocks_per_segment))
 230                 /* This limits the number of blocks read in the CRC check */
 231                 goto out;
 232
 233         ret = NILFS_SEG_FAIL_IO;
 234         if (nilfs_compute_checksum(nilfs, bh_sum, &crc, sizeof(sum->ss_datasum),
 235                                    ((u64)nblock << nilfs->ns_blocksize_bits),
 236                                    bh_sum->b_blocknr, nblock))
 237                 goto out;
 238
 239         ret = NILFS_SEG_FAIL_CHECKSUM_FULL;
 240         if (crc != le32_to_cpu(sum->ss_datasum))
 241                 goto out;
 242         ret = 0;
 243 out:
 244         return ret;
 245 }
 246
 247 /**
 248  * nilfs_read_summary_info - read an item on summary blocks of a log
 249  * @nilfs: nilfs object
 250  * @pbh: the current buffer head on summary blocks [in, out]
 251  * @offset: the current byte offset on summary blocks [in, out]
 252  * @bytes: byte size of the item to be read
 253  */
 254 static void *nilfs_read_summary_info(struct the_nilfs *nilfs,
 255                                      struct buffer_head **pbh,
 256                                      unsigned int *offset, unsigned int bytes)
 257 {
 258         void *ptr;
 259         sector_t blocknr;
 260
 261         BUG_ON((*pbh)->b_size < *offset);
 262         if (bytes > (*pbh)->b_size - *offset) {
 263                 blocknr = (*pbh)->b_blocknr;
 264                 brelse(*pbh);
 265                 *pbh = __bread(nilfs->ns_bdev, blocknr + 1,
 266                                nilfs->ns_blocksize);
 267                 if (unlikely(!*pbh))
 268                         return NULL;
 269                 *offset = 0;
 270         }
 271         ptr = (*pbh)->b_data + *offset;
 272         *offset += bytes;
 273         return ptr;
 274 }
 275
 276 /**
 277  * nilfs_skip_summary_info - skip items on summary blocks of a log
 278  * @nilfs: nilfs object
 279  * @pbh: the current buffer head on summary blocks [in, out]
 280  * @offset: the current byte offset on summary blocks [in, out]
 281  * @bytes: byte size of the item to be skipped
 282  * @count: number of items to be skipped
 283  */
 284 static void nilfs_skip_summary_info(struct the_nilfs *nilfs,
 285                                     struct buffer_head **pbh,
 286                                     unsigned int *offset, unsigned int bytes,
 287                                     unsigned long count)
 288 {
 289         unsigned int rest_item_in_current_block
 290                 = ((*pbh)->b_size - *offset) / bytes;
 291
 292         if (count <= rest_item_in_current_block) {
 293                 *offset += bytes * count;
 294         } else {
 295                 sector_t blocknr = (*pbh)->b_blocknr;
 296                 unsigned int nitem_per_block = (*pbh)->b_size / bytes;
 297                 unsigned int bcnt;
 298
 299                 count -= rest_item_in_current_block;
 300                 bcnt = DIV_ROUND_UP(count, nitem_per_block);
 301                 *offset = bytes * (count - (bcnt - 1) * nitem_per_block);
 302
 303                 brelse(*pbh);
 304                 *pbh = __bread(nilfs->ns_bdev, blocknr + bcnt,
 305                                nilfs->ns_blocksize);
 306         }
 307 }
 308
 309 /**
 310  * nilfs_scan_dsync_log - get block information of a log written for data sync
 311  * @nilfs: nilfs object
 312  * @start_blocknr: start block number of the log
 313  * @sum: log summary information
 314  * @head: list head to add nilfs_recovery_block struct
 315  */
 316 static int nilfs_scan_dsync_log(struct the_nilfs *nilfs, sector_t start_blocknr,
 317                                 struct nilfs_segment_summary *sum,
 318                                 struct list_head *head)
 319 {
 320         struct buffer_head *bh;
 321         unsigned int offset;
 322         u32 nfinfo, sumbytes;
 323         sector_t blocknr;
 324         ino_t ino;
 325         int err = -EIO;
 326
 327         nfinfo = le32_to_cpu(sum->ss_nfinfo);
 328         if (!nfinfo)
 329                 return 0;
 330
 331         sumbytes = le32_to_cpu(sum->ss_sumbytes);
 332         blocknr = start_blocknr + DIV_ROUND_UP(sumbytes, nilfs->ns_blocksize);
 333         bh = __bread(nilfs->ns_bdev, start_blocknr, nilfs->ns_blocksize);
 334         if (unlikely(!bh))
 335                 goto out;
 336
 337         offset = le16_to_cpu(sum->ss_bytes);
 338         for (;;) {
 339                 unsigned long nblocks, ndatablk, nnodeblk;
 340                 struct nilfs_finfo *finfo;
 341
 342                 finfo = nilfs_read_summary_info(nilfs, &bh, &offset,
 343                                                 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 = nilfs_read_summary_info(nilfs, &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 data sync logs */
 376                 nilfs_skip_summary_info(nilfs, &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 struct nilfs_segment_entry {
 399         struct list_head        list;
 400         __u64                   segnum;
 401 };
 402
 403 static int nilfs_segment_list_add(struct list_head *head, __u64 segnum)
 404 {
 405         struct nilfs_segment_entry *ent = kmalloc(sizeof(*ent), GFP_NOFS);
 406
 407         if (unlikely(!ent))
 408                 return -ENOMEM;
 409
 410         ent->segnum = segnum;
 411         INIT_LIST_HEAD(&ent->list);
 412         list_add_tail(&ent->list, head);
 413         return 0;
 414 }
 415
 416 void nilfs_dispose_segment_list(struct list_head *head)
 417 {
 418         while (!list_empty(head)) {
 419                 struct nilfs_segment_entry *ent
 420                         = list_entry(head->next,
 421                                      struct nilfs_segment_entry, list);
 422                 list_del(&ent->list);
 423                 kfree(ent);
 424         }
 425 }
 426
 427 static int nilfs_prepare_segment_for_recovery(struct the_nilfs *nilfs,
 428                                               struct super_block *sb,
 429                                               struct nilfs_recovery_info *ri)
 430 {
 431         struct list_head *head = &ri->ri_used_segments;
 432         struct nilfs_segment_entry *ent, *n;
 433         struct inode *sufile = nilfs->ns_sufile;
 434         __u64 segnum[4];
 435         int err;
 436         int i;
 437
 438         segnum[0] = nilfs->ns_segnum;
 439         segnum[1] = nilfs->ns_nextnum;
 440         segnum[2] = ri->ri_segnum;
 441         segnum[3] = ri->ri_nextnum;
 442
 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         return err;
 483 }
 484
 485 static int nilfs_recovery_copy_block(struct the_nilfs *nilfs,
 486                                      struct nilfs_recovery_block *rb,
 487                                      struct page *page)
 488 {
 489         struct buffer_head *bh_org;
 490         void *kaddr;
 491
 492         bh_org = __bread(nilfs->ns_bdev, rb->blocknr, nilfs->ns_blocksize);
 493         if (unlikely(!bh_org))
 494                 return -EIO;
 495
 496         kaddr = kmap_atomic(page, KM_USER0);
 497         memcpy(kaddr + bh_offset(bh_org), bh_org->b_data, bh_org->b_size);
 498         kunmap_atomic(kaddr, KM_USER0);
 499         brelse(bh_org);
 500         return 0;
 501 }
 502
 503 static int nilfs_recover_dsync_blocks(struct the_nilfs *nilfs,
 504                                       struct super_block *sb,
 505                                       struct nilfs_root *root,
 506                                       struct list_head *head,
 507                                       unsigned long *nr_salvaged_blocks)
 508 {
 509         struct inode *inode;
 510         struct nilfs_recovery_block *rb, *n;
 511         unsigned blocksize = nilfs->ns_blocksize;
 512         struct page *page;
 513         loff_t pos;
 514         int err = 0, err2 = 0;
 515
 516         list_for_each_entry_safe(rb, n, head, list) {
 517                 inode = nilfs_iget(sb, root, rb->ino);
 518                 if (IS_ERR(inode)) {
 519                         err = PTR_ERR(inode);
 520                         inode = NULL;
 521                         goto failed_inode;
 522                 }
 523
 524                 pos = rb->blkoff << inode->i_blkbits;
 525                 err = block_write_begin(inode->i_mapping, pos, blocksize,
 526                                         0, &page, nilfs_get_block);
 527                 if (unlikely(err)) {
 528                         loff_t isize = inode->i_size;
 529                         if (pos + blocksize > isize)
 530                                 vmtruncate(inode, isize);
 531                         goto failed_inode;
 532                 }
 533
 534                 err = nilfs_recovery_copy_block(nilfs, rb, page);
 535                 if (unlikely(err))
 536                         goto failed_page;
 537
 538                 err = nilfs_set_file_dirty(inode, 1);
 539                 if (unlikely(err))
 540                         goto failed_page;
 541
 542                 block_write_end(NULL, inode->i_mapping, pos, blocksize,
 543                                 blocksize, page, NULL);
 544
 545                 unlock_page(page);
 546                 page_cache_release(page);
 547
 548                 (*nr_salvaged_blocks)++;
 549                 goto next;
 550
 551  failed_page:
 552                 unlock_page(page);
 553                 page_cache_release(page);
 554
 555  failed_inode:
 556                 printk(KERN_WARNING
 557                        "NILFS warning: error recovering data block "
 558                        "(err=%d, ino=%lu, block-offset=%llu)\n",
 559                        err, (unsigned long)rb->ino,
 560                        (unsigned long long)rb->blkoff);
 561                 if (!err2)
 562                         err2 = err;
 563  next:
 564                 iput(inode); /* iput(NULL) is just ignored */
 565                 list_del_init(&rb->list);
 566                 kfree(rb);
 567         }
 568         return err2;
 569 }
 570
 571 /**
 572  * nilfs_do_roll_forward - salvage logical segments newer than the latest
 573  * checkpoint
 574  * @nilfs: nilfs object
 575  * @sb: super block instance
 576  * @ri: pointer to a nilfs_recovery_info
 577  */
 578 static int nilfs_do_roll_forward(struct the_nilfs *nilfs,
 579                                  struct super_block *sb,
 580                                  struct nilfs_root *root,
 581                                  struct nilfs_recovery_info *ri)
 582 {
 583         struct buffer_head *bh_sum = NULL;
 584         struct nilfs_segment_summary *sum;
 585         sector_t pseg_start;
 586         sector_t seg_start, seg_end;  /* Starting/ending DBN of full segment */
 587         unsigned long nsalvaged_blocks = 0;
 588         unsigned int flags;
 589         u64 seg_seq;
 590         __u64 segnum, nextnum = 0;
 591         int empty_seg = 0;
 592         int err = 0, ret;
 593         LIST_HEAD(dsync_blocks);  /* list of data blocks to be recovered */
 594         enum {
 595                 RF_INIT_ST,
 596                 RF_DSYNC_ST,   /* scanning data-sync segments */
 597         };
 598         int state = RF_INIT_ST;
 599
 600         pseg_start = ri->ri_lsegs_start;
 601         seg_seq = ri->ri_lsegs_start_seq;
 602         segnum = nilfs_get_segnum_of_block(nilfs, pseg_start);
 603         nilfs_get_segment_range(nilfs, segnum, &seg_start, &seg_end);
 604
 605         while (segnum != ri->ri_segnum || pseg_start <= ri->ri_pseg_start) {
 606                 brelse(bh_sum);
 607                 bh_sum = nilfs_read_log_header(nilfs, pseg_start, &sum);
 608                 if (!bh_sum) {
 609                         err = -EIO;
 610                         goto failed;
 611                 }
 612
 613                 ret = nilfs_validate_log(nilfs, seg_seq, bh_sum, sum);
 614                 if (ret) {
 615                         if (ret == NILFS_SEG_FAIL_IO) {
 616                                 err = -EIO;
 617                                 goto failed;
 618                         }
 619                         goto strayed;
 620                 }
 621
 622                 flags = le16_to_cpu(sum->ss_flags);
 623                 if (flags & NILFS_SS_SR)
 624                         goto confused;
 625
 626                 /* Found a valid partial segment; do recovery actions */
 627                 nextnum = nilfs_get_segnum_of_block(nilfs,
 628                                                     le64_to_cpu(sum->ss_next));
 629                 empty_seg = 0;
 630                 nilfs->ns_ctime = le64_to_cpu(sum->ss_create);
 631                 if (!(flags & NILFS_SS_GC))
 632                         nilfs->ns_nongc_ctime = nilfs->ns_ctime;
 633
 634                 switch (state) {
 635                 case RF_INIT_ST:
 636                         if (!(flags & NILFS_SS_LOGBGN) ||
 637                             !(flags & NILFS_SS_SYNDT))
 638                                 goto try_next_pseg;
 639                         state = RF_DSYNC_ST;
 640                         /* Fall through */
 641                 case RF_DSYNC_ST:
 642                         if (!(flags & NILFS_SS_SYNDT))
 643                                 goto confused;
 644
 645                         err = nilfs_scan_dsync_log(nilfs, pseg_start, sum,
 646                                                    &dsync_blocks);
 647                         if (unlikely(err))
 648                                 goto failed;
 649                         if (flags & NILFS_SS_LOGEND) {
 650                                 err = nilfs_recover_dsync_blocks(
 651                                         nilfs, sb, root, &dsync_blocks,
 652                                         &nsalvaged_blocks);
 653                                 if (unlikely(err))
 654                                         goto failed;
 655                                 state = RF_INIT_ST;
 656                         }
 657                         break; /* Fall through to try_next_pseg */
 658                 }
 659
 660  try_next_pseg:
 661                 if (pseg_start == ri->ri_lsegs_end)
 662                         break;
 663                 pseg_start += le32_to_cpu(sum->ss_nblocks);
 664                 if (pseg_start < seg_end)
 665                         continue;
 666                 goto feed_segment;
 667
 668  strayed:
 669                 if (pseg_start == ri->ri_lsegs_end)
 670                         break;
 671
 672  feed_segment:
 673                 /* Looking to the next full segment */
 674                 if (empty_seg++)
 675                         break;
 676                 seg_seq++;
 677                 segnum = nextnum;
 678                 nilfs_get_segment_range(nilfs, segnum, &seg_start, &seg_end);
 679                 pseg_start = seg_start;
 680         }
 681
 682         if (nsalvaged_blocks) {
 683                 printk(KERN_INFO "NILFS (device %s): salvaged %lu blocks\n",
 684                        sb->s_id, nsalvaged_blocks);
 685                 ri->ri_need_recovery = NILFS_RECOVERY_ROLLFORWARD_DONE;
 686         }
 687  out:
 688         brelse(bh_sum);
 689         dispose_recovery_list(&dsync_blocks);
 690         return err;
 691
 692  confused:
 693         err = -EINVAL;
 694  failed:
 695         printk(KERN_ERR
 696                "NILFS (device %s): Error roll-forwarding "
 697                "(err=%d, pseg block=%llu). ",
 698                sb->s_id, err, (unsigned long long)pseg_start);
 699         goto out;
 700 }
 701
 702 static void nilfs_finish_roll_forward(struct the_nilfs *nilfs,
 703                                       struct nilfs_recovery_info *ri)
 704 {
 705         struct buffer_head *bh;
 706         int err;
 707
 708         if (nilfs_get_segnum_of_block(nilfs, ri->ri_lsegs_start) !=
 709             nilfs_get_segnum_of_block(nilfs, ri->ri_super_root))
 710                 return;
 711
 712         bh = __getblk(nilfs->ns_bdev, ri->ri_lsegs_start, nilfs->ns_blocksize);
 713         BUG_ON(!bh);
 714         memset(bh->b_data, 0, bh->b_size);
 715         set_buffer_dirty(bh);
 716         err = sync_dirty_buffer(bh);
 717         if (unlikely(err))
 718                 printk(KERN_WARNING
 719                        "NILFS warning: buffer sync write failed during "
 720                        "post-cleaning of recovery.\n");
 721         brelse(bh);
 722 }
 723
 724 /**
 725  * nilfs_salvage_orphan_logs - salvage logs written after the latest checkpoint
 726  * @nilfs: nilfs object
 727  * @sb: super block instance
 728  * @ri: pointer to a nilfs_recovery_info struct to store search results.
 729  *
 730  * Return Value: On success, 0 is returned.  On error, one of the following
 731  * negative error code is returned.
 732  *
 733  * %-EINVAL - Inconsistent filesystem state.
 734  *
 735  * %-EIO - I/O error
 736  *
 737  * %-ENOSPC - No space left on device (only in a panic state).
 738  *
 739  * %-ERESTARTSYS - Interrupted.
 740  *
 741  * %-ENOMEM - Insufficient memory available.
 742  */
 743 int nilfs_salvage_orphan_logs(struct the_nilfs *nilfs,
 744                               struct super_block *sb,
 745                               struct nilfs_recovery_info *ri)
 746 {
 747         struct nilfs_root *root;
 748         int err;
 749
 750         if (ri->ri_lsegs_start == 0 || ri->ri_lsegs_end == 0)
 751                 return 0;
 752
 753         err = nilfs_attach_checkpoint(sb, ri->ri_cno, true, &root);
 754         if (unlikely(err)) {
 755                 printk(KERN_ERR
 756                        "NILFS: error loading the latest checkpoint.\n");
 757                 return err;
 758         }
 759
 760         err = nilfs_do_roll_forward(nilfs, sb, root, ri);
 761         if (unlikely(err))
 762                 goto failed;
 763
 764         if (ri->ri_need_recovery == NILFS_RECOVERY_ROLLFORWARD_DONE) {
 765                 err = nilfs_prepare_segment_for_recovery(nilfs, sb, ri);
 766                 if (unlikely(err)) {
 767                         printk(KERN_ERR "NILFS: Error preparing segments for "
 768                                "recovery.\n");
 769                         goto failed;
 770                 }
 771
 772                 err = nilfs_attach_log_writer(sb, root);
 773                 if (unlikely(err))
 774                         goto failed;
 775
 776                 set_nilfs_discontinued(nilfs);
 777                 err = nilfs_construct_segment(sb);
 778                 nilfs_detach_log_writer(sb);
 779
 780                 if (unlikely(err)) {
 781                         printk(KERN_ERR "NILFS: Oops! recovery failed. "
 782                                "(err=%d)\n", err);
 783                         goto failed;
 784                 }
 785
 786                 nilfs_finish_roll_forward(nilfs, ri);
 787         }
 788
 789  failed:
 790         nilfs_put_root(root);
 791         return err;
 792 }
 793
 794 /**
 795  * nilfs_search_super_root - search the latest valid super root
 796  * @nilfs: the_nilfs
 797  * @ri: pointer to a nilfs_recovery_info struct to store search results.
 798  *
 799  * nilfs_search_super_root() looks for the latest super-root from a partial
 800  * segment pointed by the superblock.  It sets up struct the_nilfs through
 801  * this search. It fills nilfs_recovery_info (ri) required for recovery.
 802  *
 803  * Return Value: On success, 0 is returned.  On error, one of the following
 804  * negative error code is returned.
 805  *
 806  * %-EINVAL - No valid segment found
 807  *
 808  * %-EIO - I/O error
 809  *
 810  * %-ENOMEM - Insufficient memory available.
 811  */
 812 int nilfs_search_super_root(struct the_nilfs *nilfs,
 813                             struct nilfs_recovery_info *ri)
 814 {
 815         struct buffer_head *bh_sum = NULL;
 816         struct nilfs_segment_summary *sum;
 817         sector_t pseg_start, pseg_end, sr_pseg_start = 0;
 818         sector_t seg_start, seg_end; /* range of full segment (block number) */
 819         sector_t b, end;
 820         unsigned long nblocks;
 821         unsigned int flags;
 822         u64 seg_seq;
 823         __u64 segnum, nextnum = 0;
 824         __u64 cno;
 825         LIST_HEAD(segments);
 826         int empty_seg = 0, scan_newer = 0;
 827         int ret;
 828
 829         pseg_start = nilfs->ns_last_pseg;
 830         seg_seq = nilfs->ns_last_seq;
 831         cno = nilfs->ns_last_cno;
 832         segnum = nilfs_get_segnum_of_block(nilfs, pseg_start);
 833
 834         /* Calculate range of segment */
 835         nilfs_get_segment_range(nilfs, segnum, &seg_start, &seg_end);
 836
 837         /* Read ahead segment */
 838         b = seg_start;
 839         while (b <= seg_end)
 840                 __breadahead(nilfs->ns_bdev, b++, nilfs->ns_blocksize);
 841
 842         for (;;) {
 843                 brelse(bh_sum);
 844                 ret = NILFS_SEG_FAIL_IO;
 845                 bh_sum = nilfs_read_log_header(nilfs, pseg_start, &sum);
 846                 if (!bh_sum)
 847                         goto failed;
 848
 849                 ret = nilfs_validate_log(nilfs, seg_seq, bh_sum, sum);
 850                 if (ret) {
 851                         if (ret == NILFS_SEG_FAIL_IO)
 852                                 goto failed;
 853                         goto strayed;
 854                 }
 855
 856                 nblocks = le32_to_cpu(sum->ss_nblocks);
 857                 pseg_end = pseg_start + nblocks - 1;
 858                 if (unlikely(pseg_end > seg_end)) {
 859                         ret = NILFS_SEG_FAIL_CONSISTENCY;
 860                         goto strayed;
 861                 }
 862
 863                 /* A valid partial segment */
 864                 ri->ri_pseg_start = pseg_start;
 865                 ri->ri_seq = seg_seq;
 866                 ri->ri_segnum = segnum;
 867                 nextnum = nilfs_get_segnum_of_block(nilfs,
 868                                                     le64_to_cpu(sum->ss_next));
 869                 ri->ri_nextnum = nextnum;
 870                 empty_seg = 0;
 871
 872                 flags = le16_to_cpu(sum->ss_flags);
 873                 if (!(flags & NILFS_SS_SR) && !scan_newer) {
 874                         /* This will never happen because a superblock
 875                            (last_segment) always points to a pseg
 876                            having a super root. */
 877                         ret = NILFS_SEG_FAIL_CONSISTENCY;
 878                         goto failed;
 879                 }
 880
 881                 if (pseg_start == seg_start) {
 882                         nilfs_get_segment_range(nilfs, nextnum, &b, &end);
 883                         while (b <= end)
 884                                 __breadahead(nilfs->ns_bdev, b++,
 885                                              nilfs->ns_blocksize);
 886                 }
 887                 if (!(flags & NILFS_SS_SR)) {
 888                         if (!ri->ri_lsegs_start && (flags & NILFS_SS_LOGBGN)) {
 889                                 ri->ri_lsegs_start = pseg_start;
 890                                 ri->ri_lsegs_start_seq = seg_seq;
 891                         }
 892                         if (flags & NILFS_SS_LOGEND)
 893                                 ri->ri_lsegs_end = pseg_start;
 894                         goto try_next_pseg;
 895                 }
 896
 897                 /* A valid super root was found. */
 898                 ri->ri_cno = cno++;
 899                 ri->ri_super_root = pseg_end;
 900                 ri->ri_lsegs_start = ri->ri_lsegs_end = 0;
 901
 902                 nilfs_dispose_segment_list(&segments);
 903                 sr_pseg_start = pseg_start;
 904                 nilfs->ns_pseg_offset = pseg_start + nblocks - seg_start;
 905                 nilfs->ns_seg_seq = seg_seq;
 906                 nilfs->ns_segnum = segnum;
 907                 nilfs->ns_cno = cno;  /* nilfs->ns_cno = ri->ri_cno + 1 */
 908                 nilfs->ns_ctime = le64_to_cpu(sum->ss_create);
 909                 nilfs->ns_nextnum = nextnum;
 910
 911                 if (scan_newer)
 912                         ri->ri_need_recovery = NILFS_RECOVERY_SR_UPDATED;
 913                 else {
 914                         if (nilfs->ns_mount_state & NILFS_VALID_FS)
 915                                 goto super_root_found;
 916                         scan_newer = 1;
 917                 }
 918
 919  try_next_pseg:
 920                 /* Standing on a course, or met an inconsistent state */
 921                 pseg_start += nblocks;
 922                 if (pseg_start < seg_end)
 923                         continue;
 924                 goto feed_segment;
 925
 926  strayed:
 927                 /* Off the trail */
 928                 if (!scan_newer)
 929                         /*
 930                          * This can happen if a checkpoint was written without
 931                          * barriers, or as a result of an I/O failure.
 932                          */
 933                         goto failed;
 934
 935  feed_segment:
 936                 /* Looking to the next full segment */
 937                 if (empty_seg++)
 938                         goto super_root_found; /* found a valid super root */
 939
 940                 ret = nilfs_segment_list_add(&segments, segnum);
 941                 if (unlikely(ret))
 942                         goto failed;
 943
 944                 seg_seq++;
 945                 segnum = nextnum;
 946                 nilfs_get_segment_range(nilfs, segnum, &seg_start, &seg_end);
 947                 pseg_start = seg_start;
 948         }
 949
 950  super_root_found:
 951         /* Updating pointers relating to the latest checkpoint */
 952         brelse(bh_sum);
 953         list_splice_tail(&segments, &ri->ri_used_segments);
 954         nilfs->ns_last_pseg = sr_pseg_start;
 955         nilfs->ns_last_seq = nilfs->ns_seg_seq;
 956         nilfs->ns_last_cno = ri->ri_cno;
 957         return 0;
 958
 959  failed:
 960         brelse(bh_sum);
 961         nilfs_dispose_segment_list(&segments);
 962         return (ret < 0) ? ret : nilfs_warn_segment_error(ret);
 963 }