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  * Written by Ryusuke Konishi.
  17  */
  18
  19 #include <linux/buffer_head.h>
  20 #include <linux/blkdev.h>
  21 #include <linux/swap.h>
  22 #include <linux/slab.h>
  23 #include <linux/crc32.h>
  24 #include "nilfs.h"
  25 #include "segment.h"
  26 #include "sufile.h"
  27 #include "page.h"
  28 #include "segbuf.h"
  29
  30 /*
  31  * Segment check result
  32  */
  33 enum {
  34         NILFS_SEG_VALID,
  35         NILFS_SEG_NO_SUPER_ROOT,
  36         NILFS_SEG_FAIL_IO,
  37         NILFS_SEG_FAIL_MAGIC,
  38         NILFS_SEG_FAIL_SEQ,
  39         NILFS_SEG_FAIL_CHECKSUM_SUPER_ROOT,
  40         NILFS_SEG_FAIL_CHECKSUM_FULL,
  41         NILFS_SEG_FAIL_CONSISTENCY,
  42 };
  43
  44 /* work structure for recovery */
  45 struct nilfs_recovery_block {
  46         ino_t ino;              /*
  47                                  * Inode number of the file that this block
  48                                  * belongs to
  49                                  */
  50         sector_t blocknr;       /* block number */
  51         __u64 vblocknr;         /* virtual block number */
  52         unsigned long blkoff;   /* File offset of the data block (per block) */
  53         struct list_head list;
  54 };
  55
  56
  57 static int nilfs_warn_segment_error(struct super_block *sb, int err)
  58 {
  59         const char *msg = NULL;
  60
  61         switch (err) {
  62         case NILFS_SEG_FAIL_IO:
  63                 nilfs_msg(sb, KERN_ERR, "I/O error reading segment");
  64                 return -EIO;
  65         case NILFS_SEG_FAIL_MAGIC:
  66                 msg = "Magic number mismatch";
  67                 break;
  68         case NILFS_SEG_FAIL_SEQ:
  69                 msg = "Sequence number mismatch";
  70                 break;
  71         case NILFS_SEG_FAIL_CHECKSUM_SUPER_ROOT:
  72                 msg = "Checksum error in super root";
  73                 break;
  74         case NILFS_SEG_FAIL_CHECKSUM_FULL:
  75                 msg = "Checksum error in segment payload";
  76                 break;
  77         case NILFS_SEG_FAIL_CONSISTENCY:
  78                 msg = "Inconsistency found";
  79                 break;
  80         case NILFS_SEG_NO_SUPER_ROOT:
  81                 msg = "No super root in the last segment";
  82                 break;
  83         default:
  84                 nilfs_msg(sb, KERN_ERR, "unrecognized segment error %d", err);
  85                 return -EINVAL;
  86         }
  87         nilfs_msg(sb, KERN_WARNING, "invalid segment: %s", msg);
  88         return -EINVAL;
  89 }
  90
  91 /**
  92  * nilfs_compute_checksum - compute checksum of blocks continuously
  93  * @nilfs: nilfs object
  94  * @bhs: buffer head of start block
  95  * @sum: place to store result
  96  * @offset: offset bytes in the first block
  97  * @check_bytes: number of bytes to be checked
  98  * @start: DBN of start block
  99  * @nblock: number of blocks to be checked
 100  */
 101 static int nilfs_compute_checksum(struct the_nilfs *nilfs,
 102                                   struct buffer_head *bhs, u32 *sum,
 103                                   unsigned long offset, u64 check_bytes,
 104                                   sector_t start, unsigned long nblock)
 105 {
 106         unsigned int blocksize = nilfs->ns_blocksize;
 107         unsigned long size;
 108         u32 crc;
 109
 110         BUG_ON(offset >= blocksize);
 111         check_bytes -= offset;
 112         size = min_t(u64, check_bytes, blocksize - offset);
 113         crc = crc32_le(nilfs->ns_crc_seed,
 114                        (unsigned char *)bhs->b_data + offset, size);
 115         if (--nblock > 0) {
 116                 do {
 117                         struct buffer_head *bh;
 118
 119                         bh = __bread(nilfs->ns_bdev, ++start, blocksize);
 120                         if (!bh)
 121                                 return -EIO;
 122                         check_bytes -= size;
 123                         size = min_t(u64, check_bytes, blocksize);
 124                         crc = crc32_le(crc, bh->b_data, size);
 125                         brelse(bh);
 126                 } while (--nblock > 0);
 127         }
 128         *sum = crc;
 129         return 0;
 130 }
 131
 132 /**
 133  * nilfs_read_super_root_block - read super root block
 134  * @nilfs: nilfs object
 135  * @sr_block: disk block number of the super root block
 136  * @pbh: address of a buffer_head pointer to return super root buffer
 137  * @check: CRC check flag
 138  */
 139 int nilfs_read_super_root_block(struct the_nilfs *nilfs, sector_t sr_block,
 140                                 struct buffer_head **pbh, int check)
 141 {
 142         struct buffer_head *bh_sr;
 143         struct nilfs_super_root *sr;
 144         u32 crc;
 145         int ret;
 146
 147         *pbh = NULL;
 148         bh_sr = __bread(nilfs->ns_bdev, sr_block, nilfs->ns_blocksize);
 149         if (unlikely(!bh_sr)) {
 150                 ret = NILFS_SEG_FAIL_IO;
 151                 goto failed;
 152         }
 153
 154         sr = (struct nilfs_super_root *)bh_sr->b_data;
 155         if (check) {
 156                 unsigned int bytes = le16_to_cpu(sr->sr_bytes);
 157
 158                 if (bytes == 0 || bytes > nilfs->ns_blocksize) {
 159                         ret = NILFS_SEG_FAIL_CHECKSUM_SUPER_ROOT;
 160                         goto failed_bh;
 161                 }
 162                 if (nilfs_compute_checksum(
 163                             nilfs, bh_sr, &crc, sizeof(sr->sr_sum), bytes,
 164                             sr_block, 1)) {
 165                         ret = NILFS_SEG_FAIL_IO;
 166                         goto failed_bh;
 167                 }
 168                 if (crc != le32_to_cpu(sr->sr_sum)) {
 169                         ret = NILFS_SEG_FAIL_CHECKSUM_SUPER_ROOT;
 170                         goto failed_bh;
 171                 }
 172         }
 173         *pbh = bh_sr;
 174         return 0;
 175
 176  failed_bh:
 177         brelse(bh_sr);
 178
 179  failed:
 180         return nilfs_warn_segment_error(nilfs->ns_sb, ret);
 181 }
 182
 183 /**
 184  * nilfs_read_log_header - read summary header of the specified log
 185  * @nilfs: nilfs object
 186  * @start_blocknr: start block number of the log
 187  * @sum: pointer to return segment summary structure
 188  */
 189 static struct buffer_head *
 190 nilfs_read_log_header(struct the_nilfs *nilfs, sector_t start_blocknr,
 191                       struct nilfs_segment_summary **sum)
 192 {
 193         struct buffer_head *bh_sum;
 194
 195         bh_sum = __bread(nilfs->ns_bdev, start_blocknr, nilfs->ns_blocksize);
 196         if (bh_sum)
 197                 *sum = (struct nilfs_segment_summary *)bh_sum->b_data;
 198         return bh_sum;
 199 }
 200
 201 /**
 202  * nilfs_validate_log - verify consistency of log
 203  * @nilfs: nilfs object
 204  * @seg_seq: sequence number of segment
 205  * @bh_sum: buffer head of summary block
 206  * @sum: segment summary struct
 207  */
 208 static int nilfs_validate_log(struct the_nilfs *nilfs, u64 seg_seq,
 209                               struct buffer_head *bh_sum,
 210                               struct nilfs_segment_summary *sum)
 211 {
 212         unsigned long nblock;
 213         u32 crc;
 214         int ret;
 215
 216         ret = NILFS_SEG_FAIL_MAGIC;
 217         if (le32_to_cpu(sum->ss_magic) != NILFS_SEGSUM_MAGIC)
 218                 goto out;
 219
 220         ret = NILFS_SEG_FAIL_SEQ;
 221         if (le64_to_cpu(sum->ss_seq) != seg_seq)
 222                 goto out;
 223
 224         nblock = le32_to_cpu(sum->ss_nblocks);
 225         ret = NILFS_SEG_FAIL_CONSISTENCY;
 226         if (unlikely(nblock == 0 || nblock > nilfs->ns_blocks_per_segment))
 227                 /* This limits the number of blocks read in the CRC check */
 228                 goto out;
 229
 230         ret = NILFS_SEG_FAIL_IO;
 231         if (nilfs_compute_checksum(nilfs, bh_sum, &crc, sizeof(sum->ss_datasum),
 232                                    ((u64)nblock << nilfs->ns_blocksize_bits),
 233                                    bh_sum->b_blocknr, nblock))
 234                 goto out;
 235
 236         ret = NILFS_SEG_FAIL_CHECKSUM_FULL;
 237         if (crc != le32_to_cpu(sum->ss_datasum))
 238                 goto out;
 239         ret = 0;
 240 out:
 241         return ret;
 242 }
 243
 244 /**
 245  * nilfs_read_summary_info - read an item on summary blocks of a log
 246  * @nilfs: nilfs object
 247  * @pbh: the current buffer head on summary blocks [in, out]
 248  * @offset: the current byte offset on summary blocks [in, out]
 249  * @bytes: byte size of the item to be read
 250  */
 251 static void *nilfs_read_summary_info(struct the_nilfs *nilfs,
 252                                      struct buffer_head **pbh,
 253                                      unsigned int *offset, unsigned int bytes)
 254 {
 255         void *ptr;
 256         sector_t blocknr;
 257
 258         BUG_ON((*pbh)->b_size < *offset);
 259         if (bytes > (*pbh)->b_size - *offset) {
 260                 blocknr = (*pbh)->b_blocknr;
 261                 brelse(*pbh);
 262                 *pbh = __bread(nilfs->ns_bdev, blocknr + 1,
 263                                nilfs->ns_blocksize);
 264                 if (unlikely(!*pbh))
 265                         return NULL;
 266                 *offset = 0;
 267         }
 268         ptr = (*pbh)->b_data + *offset;
 269         *offset += bytes;
 270         return ptr;
 271 }
 272
 273 /**
 274  * nilfs_skip_summary_info - skip items on summary blocks of a log
 275  * @nilfs: nilfs object
 276  * @pbh: the current buffer head on summary blocks [in, out]
 277  * @offset: the current byte offset on summary blocks [in, out]
 278  * @bytes: byte size of the item to be skipped
 279  * @count: number of items to be skipped
 280  */
 281 static void nilfs_skip_summary_info(struct the_nilfs *nilfs,
 282                                     struct buffer_head **pbh,
 283                                     unsigned int *offset, unsigned int bytes,
 284                                     unsigned long count)
 285 {
 286         unsigned int rest_item_in_current_block
 287                 = ((*pbh)->b_size - *offset) / bytes;
 288
 289         if (count <= rest_item_in_current_block) {
 290                 *offset += bytes * count;
 291         } else {
 292                 sector_t blocknr = (*pbh)->b_blocknr;
 293                 unsigned int nitem_per_block = (*pbh)->b_size / bytes;
 294                 unsigned int bcnt;
 295
 296                 count -= rest_item_in_current_block;
 297                 bcnt = DIV_ROUND_UP(count, nitem_per_block);
 298                 *offset = bytes * (count - (bcnt - 1) * nitem_per_block);
 299
 300                 brelse(*pbh);
 301                 *pbh = __bread(nilfs->ns_bdev, blocknr + bcnt,
 302                                nilfs->ns_blocksize);
 303         }
 304 }
 305
 306 /**
 307  * nilfs_scan_dsync_log - get block information of a log written for data sync
 308  * @nilfs: nilfs object
 309  * @start_blocknr: start block number of the log
 310  * @sum: log summary information
 311  * @head: list head to add nilfs_recovery_block struct
 312  */
 313 static int nilfs_scan_dsync_log(struct the_nilfs *nilfs, sector_t start_blocknr,
 314                                 struct nilfs_segment_summary *sum,
 315                                 struct list_head *head)
 316 {
 317         struct buffer_head *bh;
 318         unsigned int offset;
 319         u32 nfinfo, sumbytes;
 320         sector_t blocknr;
 321         ino_t ino;
 322         int err = -EIO;
 323
 324         nfinfo = le32_to_cpu(sum->ss_nfinfo);
 325         if (!nfinfo)
 326                 return 0;
 327
 328         sumbytes = le32_to_cpu(sum->ss_sumbytes);
 329         blocknr = start_blocknr + DIV_ROUND_UP(sumbytes, nilfs->ns_blocksize);
 330         bh = __bread(nilfs->ns_bdev, start_blocknr, nilfs->ns_blocksize);
 331         if (unlikely(!bh))
 332                 goto out;
 333
 334         offset = le16_to_cpu(sum->ss_bytes);
 335         for (;;) {
 336                 unsigned long nblocks, ndatablk, nnodeblk;
 337                 struct nilfs_finfo *finfo;
 338
 339                 finfo = nilfs_read_summary_info(nilfs, &bh, &offset,
 340                                                 sizeof(*finfo));
 341                 if (unlikely(!finfo))
 342                         goto out;
 343
 344                 ino = le64_to_cpu(finfo->fi_ino);
 345                 nblocks = le32_to_cpu(finfo->fi_nblocks);
 346                 ndatablk = le32_to_cpu(finfo->fi_ndatablk);
 347                 nnodeblk = nblocks - ndatablk;
 348
 349                 while (ndatablk-- > 0) {
 350                         struct nilfs_recovery_block *rb;
 351                         struct nilfs_binfo_v *binfo;
 352
 353                         binfo = nilfs_read_summary_info(nilfs, &bh, &offset,
 354                                                         sizeof(*binfo));
 355                         if (unlikely(!binfo))
 356                                 goto out;
 357
 358                         rb = kmalloc(sizeof(*rb), GFP_NOFS);
 359                         if (unlikely(!rb)) {
 360                                 err = -ENOMEM;
 361                                 goto out;
 362                         }
 363                         rb->ino = ino;
 364                         rb->blocknr = blocknr++;
 365                         rb->vblocknr = le64_to_cpu(binfo->bi_vblocknr);
 366                         rb->blkoff = le64_to_cpu(binfo->bi_blkoff);
 367                         /* INIT_LIST_HEAD(&rb->list); */
 368                         list_add_tail(&rb->list, head);
 369                 }
 370                 if (--nfinfo == 0)
 371                         break;
 372                 blocknr += nnodeblk; /* always 0 for data sync logs */
 373                 nilfs_skip_summary_info(nilfs, &bh, &offset, sizeof(__le64),
 374                                         nnodeblk);
 375                 if (unlikely(!bh))
 376                         goto out;
 377         }
 378         err = 0;
 379  out:
 380         brelse(bh);   /* brelse(NULL) is just ignored */
 381         return err;
 382 }
 383
 384 static void dispose_recovery_list(struct list_head *head)
 385 {
 386         while (!list_empty(head)) {
 387                 struct nilfs_recovery_block *rb;
 388
 389                 rb = list_first_entry(head, struct nilfs_recovery_block, list);
 390                 list_del(&rb->list);
 391                 kfree(rb);
 392         }
 393 }
 394
 395 struct nilfs_segment_entry {
 396         struct list_head        list;
 397         __u64                   segnum;
 398 };
 399
 400 static int nilfs_segment_list_add(struct list_head *head, __u64 segnum)
 401 {
 402         struct nilfs_segment_entry *ent = kmalloc(sizeof(*ent), GFP_NOFS);
 403
 404         if (unlikely(!ent))
 405                 return -ENOMEM;
 406
 407         ent->segnum = segnum;
 408         INIT_LIST_HEAD(&ent->list);
 409         list_add_tail(&ent->list, head);
 410         return 0;
 411 }
 412
 413 void nilfs_dispose_segment_list(struct list_head *head)
 414 {
 415         while (!list_empty(head)) {
 416                 struct nilfs_segment_entry *ent;
 417
 418                 ent = list_first_entry(head, struct nilfs_segment_entry, list);
 419                 list_del(&ent->list);
 420                 kfree(ent);
 421         }
 422 }
 423
 424 static int nilfs_prepare_segment_for_recovery(struct the_nilfs *nilfs,
 425                                               struct super_block *sb,
 426                                               struct nilfs_recovery_info *ri)
 427 {
 428         struct list_head *head = &ri->ri_used_segments;
 429         struct nilfs_segment_entry *ent, *n;
 430         struct inode *sufile = nilfs->ns_sufile;
 431         __u64 segnum[4];
 432         int err;
 433         int i;
 434
 435         segnum[0] = nilfs->ns_segnum;
 436         segnum[1] = nilfs->ns_nextnum;
 437         segnum[2] = ri->ri_segnum;
 438         segnum[3] = ri->ri_nextnum;
 439
 440         /*
 441          * Releasing the next segment of the latest super root.
 442          * The next segment is invalidated by this recovery.
 443          */
 444         err = nilfs_sufile_free(sufile, segnum[1]);
 445         if (unlikely(err))
 446                 goto failed;
 447
 448         for (i = 1; i < 4; i++) {
 449                 err = nilfs_segment_list_add(head, segnum[i]);
 450                 if (unlikely(err))
 451                         goto failed;
 452         }
 453
 454         /*
 455          * Collecting segments written after the latest super root.
 456          * These are marked dirty to avoid being reallocated in the next write.
 457          */
 458         list_for_each_entry_safe(ent, n, head, list) {
 459                 if (ent->segnum != segnum[0]) {
 460                         err = nilfs_sufile_scrap(sufile, ent->segnum);
 461                         if (unlikely(err))
 462                                 goto failed;
 463                 }
 464                 list_del(&ent->list);
 465                 kfree(ent);
 466         }
 467
 468         /* Allocate new segments for recovery */
 469         err = nilfs_sufile_alloc(sufile, &segnum[0]);
 470         if (unlikely(err))
 471                 goto failed;
 472
 473         nilfs->ns_pseg_offset = 0;
 474         nilfs->ns_seg_seq = ri->ri_seq + 2;
 475         nilfs->ns_nextnum = nilfs->ns_segnum = segnum[0];
 476
 477  failed:
 478         /* No need to recover sufile because it will be destroyed on error */
 479         return err;
 480 }
 481
 482 static int nilfs_recovery_copy_block(struct the_nilfs *nilfs,
 483                                      struct nilfs_recovery_block *rb,
 484                                      struct page *page)
 485 {
 486         struct buffer_head *bh_org;
 487         void *kaddr;
 488
 489         bh_org = __bread(nilfs->ns_bdev, rb->blocknr, nilfs->ns_blocksize);
 490         if (unlikely(!bh_org))
 491                 return -EIO;
 492
 493         kaddr = kmap_atomic(page);
 494         memcpy(kaddr + bh_offset(bh_org), bh_org->b_data, bh_org->b_size);
 495         kunmap_atomic(kaddr);
 496         brelse(bh_org);
 497         return 0;
 498 }
 499
 500 static int nilfs_recover_dsync_blocks(struct the_nilfs *nilfs,
 501                                       struct super_block *sb,
 502                                       struct nilfs_root *root,
 503                                       struct list_head *head,
 504                                       unsigned long *nr_salvaged_blocks)
 505 {
 506         struct inode *inode;
 507         struct nilfs_recovery_block *rb, *n;
 508         unsigned int blocksize = nilfs->ns_blocksize;
 509         struct page *page;
 510         loff_t pos;
 511         int err = 0, err2 = 0;
 512
 513         list_for_each_entry_safe(rb, n, head, list) {
 514                 inode = nilfs_iget(sb, root, rb->ino);
 515                 if (IS_ERR(inode)) {
 516                         err = PTR_ERR(inode);
 517                         inode = NULL;
 518                         goto failed_inode;
 519                 }
 520
 521                 pos = rb->blkoff << inode->i_blkbits;
 522                 err = block_write_begin(inode->i_mapping, pos, blocksize,
 523                                         0, &page, nilfs_get_block);
 524                 if (unlikely(err)) {
 525                         loff_t isize = inode->i_size;
 526
 527                         if (pos + blocksize > isize)
 528                                 nilfs_write_failed(inode->i_mapping,
 529                                                         pos + blocksize);
 530                         goto failed_inode;
 531                 }
 532
 533                 err = nilfs_recovery_copy_block(nilfs, rb, page);
 534                 if (unlikely(err))
 535                         goto failed_page;
 536
 537                 err = nilfs_set_file_dirty(inode, 1);
 538                 if (unlikely(err))
 539                         goto failed_page;
 540
 541                 block_write_end(NULL, inode->i_mapping, pos, blocksize,
 542                                 blocksize, page, NULL);
 543
 544                 unlock_page(page);
 545                 put_page(page);
 546
 547                 (*nr_salvaged_blocks)++;
 548                 goto next;
 549
 550  failed_page:
 551                 unlock_page(page);
 552                 put_page(page);
 553
 554  failed_inode:
 555                 nilfs_msg(sb, KERN_WARNING,
 556                           "error %d recovering data block (ino=%lu, block-offset=%llu)",
 557                           err, (unsigned long)rb->ino,
 558                           (unsigned long long)rb->blkoff);
 559                 if (!err2)
 560                         err2 = err;
 561  next:
 562                 iput(inode); /* iput(NULL) is just ignored */
 563                 list_del_init(&rb->list);
 564                 kfree(rb);
 565         }
 566         return err2;
 567 }
 568
 569 /**
 570  * nilfs_do_roll_forward - salvage logical segments newer than the latest
 571  * checkpoint
 572  * @nilfs: nilfs object
 573  * @sb: super block instance
 574  * @ri: pointer to a nilfs_recovery_info
 575  */
 576 static int nilfs_do_roll_forward(struct the_nilfs *nilfs,
 577                                  struct super_block *sb,
 578                                  struct nilfs_root *root,
 579                                  struct nilfs_recovery_info *ri)
 580 {
 581         struct buffer_head *bh_sum = NULL;
 582         struct nilfs_segment_summary *sum = NULL;
 583         sector_t pseg_start;
 584         sector_t seg_start, seg_end;  /* Starting/ending DBN of full segment */
 585         unsigned long nsalvaged_blocks = 0;
 586         unsigned int flags;
 587         u64 seg_seq;
 588         __u64 segnum, nextnum = 0;
 589         int empty_seg = 0;
 590         int err = 0, ret;
 591         LIST_HEAD(dsync_blocks);  /* list of data blocks to be recovered */
 592         enum {
 593                 RF_INIT_ST,
 594                 RF_DSYNC_ST,   /* scanning data-sync segments */
 595         };
 596         int state = RF_INIT_ST;
 597
 598         pseg_start = ri->ri_lsegs_start;
 599         seg_seq = ri->ri_lsegs_start_seq;
 600         segnum = nilfs_get_segnum_of_block(nilfs, pseg_start);
 601         nilfs_get_segment_range(nilfs, segnum, &seg_start, &seg_end);
 602
 603         while (segnum != ri->ri_segnum || pseg_start <= ri->ri_pseg_start) {
 604                 brelse(bh_sum);
 605                 bh_sum = nilfs_read_log_header(nilfs, pseg_start, &sum);
 606                 if (!bh_sum) {
 607                         err = -EIO;
 608                         goto failed;
 609                 }
 610
 611                 ret = nilfs_validate_log(nilfs, seg_seq, bh_sum, sum);
 612                 if (ret) {
 613                         if (ret == NILFS_SEG_FAIL_IO) {
 614                                 err = -EIO;
 615                                 goto failed;
 616                         }
 617                         goto strayed;
 618                 }
 619
 620                 flags = le16_to_cpu(sum->ss_flags);
 621                 if (flags & NILFS_SS_SR)
 622                         goto confused;
 623
 624                 /* Found a valid partial segment; do recovery actions */
 625                 nextnum = nilfs_get_segnum_of_block(nilfs,
 626                                                     le64_to_cpu(sum->ss_next));
 627                 empty_seg = 0;
 628                 nilfs->ns_ctime = le64_to_cpu(sum->ss_create);
 629                 if (!(flags & NILFS_SS_GC))
 630                         nilfs->ns_nongc_ctime = nilfs->ns_ctime;
 631
 632                 switch (state) {
 633                 case RF_INIT_ST:
 634                         if (!(flags & NILFS_SS_LOGBGN) ||
 635                             !(flags & NILFS_SS_SYNDT))
 636                                 goto try_next_pseg;
 637                         state = RF_DSYNC_ST;
 638                         /* Fall through */
 639                 case RF_DSYNC_ST:
 640                         if (!(flags & NILFS_SS_SYNDT))
 641                                 goto confused;
 642
 643                         err = nilfs_scan_dsync_log(nilfs, pseg_start, sum,
 644                                                    &dsync_blocks);
 645                         if (unlikely(err))
 646                                 goto failed;
 647                         if (flags & NILFS_SS_LOGEND) {
 648                                 err = nilfs_recover_dsync_blocks(
 649                                         nilfs, sb, root, &dsync_blocks,
 650                                         &nsalvaged_blocks);
 651                                 if (unlikely(err))
 652                                         goto failed;
 653                                 state = RF_INIT_ST;
 654                         }
 655                         break; /* Fall through to try_next_pseg */
 656                 }
 657
 658  try_next_pseg:
 659                 if (pseg_start == ri->ri_lsegs_end)
 660                         break;
 661                 pseg_start += le32_to_cpu(sum->ss_nblocks);
 662                 if (pseg_start < seg_end)
 663                         continue;
 664                 goto feed_segment;
 665
 666  strayed:
 667                 if (pseg_start == ri->ri_lsegs_end)
 668                         break;
 669
 670  feed_segment:
 671                 /* Looking to the next full segment */
 672                 if (empty_seg++)
 673                         break;
 674                 seg_seq++;
 675                 segnum = nextnum;
 676                 nilfs_get_segment_range(nilfs, segnum, &seg_start, &seg_end);
 677                 pseg_start = seg_start;
 678         }
 679
 680         if (nsalvaged_blocks) {
 681                 nilfs_msg(sb, KERN_INFO, "salvaged %lu blocks",
 682                           nsalvaged_blocks);
 683                 ri->ri_need_recovery = NILFS_RECOVERY_ROLLFORWARD_DONE;
 684         }
 685  out:
 686         brelse(bh_sum);
 687         dispose_recovery_list(&dsync_blocks);
 688         return err;
 689
 690  confused:
 691         err = -EINVAL;
 692  failed:
 693         nilfs_msg(sb, KERN_ERR,
 694                   "error %d roll-forwarding partial segment at blocknr = %llu",
 695                   err, (unsigned long long)pseg_start);
 696         goto out;
 697 }
 698
 699 static void nilfs_finish_roll_forward(struct the_nilfs *nilfs,
 700                                       struct nilfs_recovery_info *ri)
 701 {
 702         struct buffer_head *bh;
 703         int err;
 704
 705         if (nilfs_get_segnum_of_block(nilfs, ri->ri_lsegs_start) !=
 706             nilfs_get_segnum_of_block(nilfs, ri->ri_super_root))
 707                 return;
 708
 709         bh = __getblk(nilfs->ns_bdev, ri->ri_lsegs_start, nilfs->ns_blocksize);
 710         BUG_ON(!bh);
 711         memset(bh->b_data, 0, bh->b_size);
 712         set_buffer_dirty(bh);
 713         err = sync_dirty_buffer(bh);
 714         if (unlikely(err))
 715                 nilfs_msg(nilfs->ns_sb, KERN_WARNING,
 716                           "buffer sync write failed during post-cleaning of recovery.");
 717         brelse(bh);
 718 }
 719
 720 /**
 721  * nilfs_salvage_orphan_logs - salvage logs written after the latest checkpoint
 722  * @nilfs: nilfs object
 723  * @sb: super block instance
 724  * @ri: pointer to a nilfs_recovery_info struct to store search results.
 725  *
 726  * Return Value: On success, 0 is returned.  On error, one of the following
 727  * negative error code is returned.
 728  *
 729  * %-EINVAL - Inconsistent filesystem state.
 730  *
 731  * %-EIO - I/O error
 732  *
 733  * %-ENOSPC - No space left on device (only in a panic state).
 734  *
 735  * %-ERESTARTSYS - Interrupted.
 736  *
 737  * %-ENOMEM - Insufficient memory available.
 738  */
 739 int nilfs_salvage_orphan_logs(struct the_nilfs *nilfs,
 740                               struct super_block *sb,
 741                               struct nilfs_recovery_info *ri)
 742 {
 743         struct nilfs_root *root;
 744         int err;
 745
 746         if (ri->ri_lsegs_start == 0 || ri->ri_lsegs_end == 0)
 747                 return 0;
 748
 749         err = nilfs_attach_checkpoint(sb, ri->ri_cno, true, &root);
 750         if (unlikely(err)) {
 751                 nilfs_msg(sb, KERN_ERR,
 752                           "error %d loading the latest checkpoint", err);
 753                 return err;
 754         }
 755
 756         err = nilfs_do_roll_forward(nilfs, sb, root, ri);
 757         if (unlikely(err))
 758                 goto failed;
 759
 760         if (ri->ri_need_recovery == NILFS_RECOVERY_ROLLFORWARD_DONE) {
 761                 err = nilfs_prepare_segment_for_recovery(nilfs, sb, ri);
 762                 if (unlikely(err)) {
 763                         nilfs_msg(sb, KERN_ERR,
 764                                   "error %d preparing segment for recovery",
 765                                   err);
 766                         goto failed;
 767                 }
 768
 769                 err = nilfs_attach_log_writer(sb, root);
 770                 if (unlikely(err))
 771                         goto failed;
 772
 773                 set_nilfs_discontinued(nilfs);
 774                 err = nilfs_construct_segment(sb);
 775                 nilfs_detach_log_writer(sb);
 776
 777                 if (unlikely(err)) {
 778                         nilfs_msg(sb, KERN_ERR,
 779                                   "error %d writing segment for recovery",
 780                                   err);
 781                         goto failed;
 782                 }
 783
 784                 nilfs_finish_roll_forward(nilfs, ri);
 785         }
 786
 787  failed:
 788         nilfs_put_root(root);
 789         return err;
 790 }
 791
 792 /**
 793  * nilfs_search_super_root - search the latest valid super root
 794  * @nilfs: the_nilfs
 795  * @ri: pointer to a nilfs_recovery_info struct to store search results.
 796  *
 797  * nilfs_search_super_root() looks for the latest super-root from a partial
 798  * segment pointed by the superblock.  It sets up struct the_nilfs through
 799  * this search. It fills nilfs_recovery_info (ri) required for recovery.
 800  *
 801  * Return Value: On success, 0 is returned.  On error, one of the following
 802  * negative error code is returned.
 803  *
 804  * %-EINVAL - No valid segment found
 805  *
 806  * %-EIO - I/O error
 807  *
 808  * %-ENOMEM - Insufficient memory available.
 809  */
 810 int nilfs_search_super_root(struct the_nilfs *nilfs,
 811                             struct nilfs_recovery_info *ri)
 812 {
 813         struct buffer_head *bh_sum = NULL;
 814         struct nilfs_segment_summary *sum = NULL;
 815         sector_t pseg_start, pseg_end, sr_pseg_start = 0;
 816         sector_t seg_start, seg_end; /* range of full segment (block number) */
 817         sector_t b, end;
 818         unsigned long nblocks;
 819         unsigned int flags;
 820         u64 seg_seq;
 821         __u64 segnum, nextnum = 0;
 822         __u64 cno;
 823         LIST_HEAD(segments);
 824         int empty_seg = 0, scan_newer = 0;
 825         int ret;
 826
 827         pseg_start = nilfs->ns_last_pseg;
 828         seg_seq = nilfs->ns_last_seq;
 829         cno = nilfs->ns_last_cno;
 830         segnum = nilfs_get_segnum_of_block(nilfs, pseg_start);
 831
 832         /* Calculate range of segment */
 833         nilfs_get_segment_range(nilfs, segnum, &seg_start, &seg_end);
 834
 835         /* Read ahead segment */
 836         b = seg_start;
 837         while (b <= seg_end)
 838                 __breadahead(nilfs->ns_bdev, b++, nilfs->ns_blocksize);
 839
 840         for (;;) {
 841                 brelse(bh_sum);
 842                 ret = NILFS_SEG_FAIL_IO;
 843                 bh_sum = nilfs_read_log_header(nilfs, pseg_start, &sum);
 844                 if (!bh_sum)
 845                         goto failed;
 846
 847                 ret = nilfs_validate_log(nilfs, seg_seq, bh_sum, sum);
 848                 if (ret) {
 849                         if (ret == NILFS_SEG_FAIL_IO)
 850                                 goto failed;
 851                         goto strayed;
 852                 }
 853
 854                 nblocks = le32_to_cpu(sum->ss_nblocks);
 855                 pseg_end = pseg_start + nblocks - 1;
 856                 if (unlikely(pseg_end > seg_end)) {
 857                         ret = NILFS_SEG_FAIL_CONSISTENCY;
 858                         goto strayed;
 859                 }
 860
 861                 /* A valid partial segment */
 862                 ri->ri_pseg_start = pseg_start;
 863                 ri->ri_seq = seg_seq;
 864                 ri->ri_segnum = segnum;
 865                 nextnum = nilfs_get_segnum_of_block(nilfs,
 866                                                     le64_to_cpu(sum->ss_next));
 867                 ri->ri_nextnum = nextnum;
 868                 empty_seg = 0;
 869
 870                 flags = le16_to_cpu(sum->ss_flags);
 871                 if (!(flags & NILFS_SS_SR) && !scan_newer) {
 872                         /*
 873                          * This will never happen because a superblock
 874                          * (last_segment) always points to a pseg with
 875                          * a super root.
 876                          */
 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(nilfs->ns_sb, ret);
 963 }