nilfs2: do not use nilfs_segsum_info structure in recovery code
[linux-3.10.git] / 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 nilfs_sb_info *sbi,
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         nilfs_attach_writer(nilfs, sbi);
444         /*
445          * Releasing the next segment of the latest super root.
446          * The next segment is invalidated by this recovery.
447          */
448         err = nilfs_sufile_free(sufile, segnum[1]);
449         if (unlikely(err))
450                 goto failed;
451
452         for (i = 1; i < 4; i++) {
453                 err = nilfs_segment_list_add(head, segnum[i]);
454                 if (unlikely(err))
455                         goto failed;
456         }
457
458         /*
459          * Collecting segments written after the latest super root.
460          * These are marked dirty to avoid being reallocated in the next write.
461          */
462         list_for_each_entry_safe(ent, n, head, list) {
463                 if (ent->segnum != segnum[0]) {
464                         err = nilfs_sufile_scrap(sufile, ent->segnum);
465                         if (unlikely(err))
466                                 goto failed;
467                 }
468                 list_del(&ent->list);
469                 kfree(ent);
470         }
471
472         /* Allocate new segments for recovery */
473         err = nilfs_sufile_alloc(sufile, &segnum[0]);
474         if (unlikely(err))
475                 goto failed;
476
477         nilfs->ns_pseg_offset = 0;
478         nilfs->ns_seg_seq = ri->ri_seq + 2;
479         nilfs->ns_nextnum = nilfs->ns_segnum = segnum[0];
480
481  failed:
482         /* No need to recover sufile because it will be destroyed on error */
483         nilfs_detach_writer(nilfs, sbi);
484         return err;
485 }
486
487 static int nilfs_recovery_copy_block(struct the_nilfs *nilfs,
488                                      struct nilfs_recovery_block *rb,
489                                      struct page *page)
490 {
491         struct buffer_head *bh_org;
492         void *kaddr;
493
494         bh_org = __bread(nilfs->ns_bdev, rb->blocknr, nilfs->ns_blocksize);
495         if (unlikely(!bh_org))
496                 return -EIO;
497
498         kaddr = kmap_atomic(page, KM_USER0);
499         memcpy(kaddr + bh_offset(bh_org), bh_org->b_data, bh_org->b_size);
500         kunmap_atomic(kaddr, KM_USER0);
501         brelse(bh_org);
502         return 0;
503 }
504
505 static int nilfs_recover_dsync_blocks(struct the_nilfs *nilfs,
506                                       struct nilfs_sb_info *sbi,
507                                       struct list_head *head,
508                                       unsigned long *nr_salvaged_blocks)
509 {
510         struct inode *inode;
511         struct nilfs_recovery_block *rb, *n;
512         unsigned blocksize = nilfs->ns_blocksize;
513         struct page *page;
514         loff_t pos;
515         int err = 0, err2 = 0;
516
517         list_for_each_entry_safe(rb, n, head, list) {
518                 inode = nilfs_iget(sbi->s_super, rb->ino);
519                 if (IS_ERR(inode)) {
520                         err = PTR_ERR(inode);
521                         inode = NULL;
522                         goto failed_inode;
523                 }
524
525                 pos = rb->blkoff << inode->i_blkbits;
526                 page = NULL;
527                 err = block_write_begin(NULL, inode->i_mapping, pos, blocksize,
528                                         0, &page, NULL, nilfs_get_block);
529                 if (unlikely(err))
530                         goto failed_inode;
531
532                 err = nilfs_recovery_copy_block(nilfs, rb, page);
533                 if (unlikely(err))
534                         goto failed_page;
535
536                 err = nilfs_set_file_dirty(sbi, inode, 1);
537                 if (unlikely(err))
538                         goto failed_page;
539
540                 block_write_end(NULL, inode->i_mapping, pos, blocksize,
541                                 blocksize, page, NULL);
542
543                 unlock_page(page);
544                 page_cache_release(page);
545
546                 (*nr_salvaged_blocks)++;
547                 goto next;
548
549  failed_page:
550                 unlock_page(page);
551                 page_cache_release(page);
552
553  failed_inode:
554                 printk(KERN_WARNING
555                        "NILFS warning: error recovering data block "
556                        "(err=%d, ino=%lu, block-offset=%llu)\n",
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  * @sbi: nilfs_sb_info
574  * @ri: pointer to a nilfs_recovery_info
575  */
576 static int nilfs_do_roll_forward(struct the_nilfs *nilfs,
577                                  struct nilfs_sb_info *sbi,
578                                  struct nilfs_recovery_info *ri)
579 {
580         struct buffer_head *bh_sum = NULL;
581         struct nilfs_segment_summary *sum;
582         sector_t pseg_start;
583         sector_t seg_start, seg_end;  /* Starting/ending DBN of full segment */
584         unsigned long nsalvaged_blocks = 0;
585         unsigned int flags;
586         u64 seg_seq;
587         __u64 segnum, nextnum = 0;
588         int empty_seg = 0;
589         int err = 0, ret;
590         LIST_HEAD(dsync_blocks);  /* list of data blocks to be recovered */
591         enum {
592                 RF_INIT_ST,
593                 RF_DSYNC_ST,   /* scanning data-sync segments */
594         };
595         int state = RF_INIT_ST;
596
597         nilfs_attach_writer(nilfs, sbi);
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, sbi, &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                 printk(KERN_INFO "NILFS (device %s): salvaged %lu blocks\n",
682                        sbi->s_super->s_id, 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         nilfs_detach_writer(nilfs, sbi);
689         return err;
690
691  confused:
692         err = -EINVAL;
693  failed:
694         printk(KERN_ERR
695                "NILFS (device %s): Error roll-forwarding "
696                "(err=%d, pseg block=%llu). ",
697                sbi->s_super->s_id, err, (unsigned long long)pseg_start);
698         goto out;
699 }
700
701 static void nilfs_finish_roll_forward(struct the_nilfs *nilfs,
702                                       struct nilfs_recovery_info *ri)
703 {
704         struct buffer_head *bh;
705         int err;
706
707         if (nilfs_get_segnum_of_block(nilfs, ri->ri_lsegs_start) !=
708             nilfs_get_segnum_of_block(nilfs, ri->ri_super_root))
709                 return;
710
711         bh = __getblk(nilfs->ns_bdev, ri->ri_lsegs_start, nilfs->ns_blocksize);
712         BUG_ON(!bh);
713         memset(bh->b_data, 0, bh->b_size);
714         set_buffer_dirty(bh);
715         err = sync_dirty_buffer(bh);
716         if (unlikely(err))
717                 printk(KERN_WARNING
718                        "NILFS warning: buffer sync write failed during "
719                        "post-cleaning of recovery.\n");
720         brelse(bh);
721 }
722
723 /**
724  * nilfs_salvage_orphan_logs - salvage logs written after the latest checkpoint
725  * @nilfs: nilfs object
726  * @sbi: nilfs_sb_info
727  * @ri: pointer to a nilfs_recovery_info struct to store search results.
728  *
729  * Return Value: On success, 0 is returned.  On error, one of the following
730  * negative error code is returned.
731  *
732  * %-EINVAL - Inconsistent filesystem state.
733  *
734  * %-EIO - I/O error
735  *
736  * %-ENOSPC - No space left on device (only in a panic state).
737  *
738  * %-ERESTARTSYS - Interrupted.
739  *
740  * %-ENOMEM - Insufficient memory available.
741  */
742 int nilfs_salvage_orphan_logs(struct the_nilfs *nilfs,
743                               struct nilfs_sb_info *sbi,
744                               struct nilfs_recovery_info *ri)
745 {
746         int err;
747
748         if (ri->ri_lsegs_start == 0 || ri->ri_lsegs_end == 0)
749                 return 0;
750
751         err = nilfs_attach_checkpoint(sbi, ri->ri_cno);
752         if (unlikely(err)) {
753                 printk(KERN_ERR
754                        "NILFS: error loading the latest checkpoint.\n");
755                 return err;
756         }
757
758         err = nilfs_do_roll_forward(nilfs, sbi, ri);
759         if (unlikely(err))
760                 goto failed;
761
762         if (ri->ri_need_recovery == NILFS_RECOVERY_ROLLFORWARD_DONE) {
763                 err = nilfs_prepare_segment_for_recovery(nilfs, sbi, ri);
764                 if (unlikely(err)) {
765                         printk(KERN_ERR "NILFS: Error preparing segments for "
766                                "recovery.\n");
767                         goto failed;
768                 }
769
770                 err = nilfs_attach_segment_constructor(sbi);
771                 if (unlikely(err))
772                         goto failed;
773
774                 set_nilfs_discontinued(nilfs);
775                 err = nilfs_construct_segment(sbi->s_super);
776                 nilfs_detach_segment_constructor(sbi);
777
778                 if (unlikely(err)) {
779                         printk(KERN_ERR "NILFS: Oops! recovery failed. "
780                                "(err=%d)\n", err);
781                         goto failed;
782                 }
783
784                 nilfs_finish_roll_forward(nilfs, ri);
785         }
786
787  failed:
788         nilfs_detach_checkpoint(sbi);
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 int nilfs_search_super_root(struct the_nilfs *nilfs,
809                             struct nilfs_recovery_info *ri)
810 {
811         struct buffer_head *bh_sum = NULL;
812         struct nilfs_segment_summary *sum;
813         sector_t pseg_start, pseg_end, sr_pseg_start = 0;
814         sector_t seg_start, seg_end; /* range of full segment (block number) */
815         sector_t b, end;
816         unsigned long nblocks;
817         unsigned int flags;
818         u64 seg_seq;
819         __u64 segnum, nextnum = 0;
820         __u64 cno;
821         LIST_HEAD(segments);
822         int empty_seg = 0, scan_newer = 0;
823         int ret;
824
825         pseg_start = nilfs->ns_last_pseg;
826         seg_seq = nilfs->ns_last_seq;
827         cno = nilfs->ns_last_cno;
828         segnum = nilfs_get_segnum_of_block(nilfs, pseg_start);
829
830         /* Calculate range of segment */
831         nilfs_get_segment_range(nilfs, segnum, &seg_start, &seg_end);
832
833         /* Read ahead segment */
834         b = seg_start;
835         while (b <= seg_end)
836                 __breadahead(nilfs->ns_bdev, b++, nilfs->ns_blocksize);
837
838         for (;;) {
839                 brelse(bh_sum);
840                 ret = NILFS_SEG_FAIL_IO;
841                 bh_sum = nilfs_read_log_header(nilfs, pseg_start, &sum);
842                 if (!bh_sum)
843                         goto failed;
844
845                 ret = nilfs_validate_log(nilfs, seg_seq, bh_sum, sum);
846                 if (ret) {
847                         if (ret == NILFS_SEG_FAIL_IO)
848                                 goto failed;
849                         goto strayed;
850                 }
851
852                 nblocks = le32_to_cpu(sum->ss_nblocks);
853                 pseg_end = pseg_start + nblocks - 1;
854                 if (unlikely(pseg_end > seg_end)) {
855                         ret = NILFS_SEG_FAIL_CONSISTENCY;
856                         goto strayed;
857                 }
858
859                 /* A valid partial segment */
860                 ri->ri_pseg_start = pseg_start;
861                 ri->ri_seq = seg_seq;
862                 ri->ri_segnum = segnum;
863                 nextnum = nilfs_get_segnum_of_block(nilfs,
864                                                     le64_to_cpu(sum->ss_next));
865                 ri->ri_nextnum = nextnum;
866                 empty_seg = 0;
867
868                 flags = le16_to_cpu(sum->ss_flags);
869                 if (!(flags & NILFS_SS_SR) && !scan_newer) {
870                         /* This will never happen because a superblock
871                            (last_segment) always points to a pseg
872                            having a super root. */
873                         ret = NILFS_SEG_FAIL_CONSISTENCY;
874                         goto failed;
875                 }
876
877                 if (pseg_start == seg_start) {
878                         nilfs_get_segment_range(nilfs, nextnum, &b, &end);
879                         while (b <= end)
880                                 __breadahead(nilfs->ns_bdev, b++,
881                                              nilfs->ns_blocksize);
882                 }
883                 if (!(flags & NILFS_SS_SR)) {
884                         if (!ri->ri_lsegs_start && (flags & NILFS_SS_LOGBGN)) {
885                                 ri->ri_lsegs_start = pseg_start;
886                                 ri->ri_lsegs_start_seq = seg_seq;
887                         }
888                         if (flags & NILFS_SS_LOGEND)
889                                 ri->ri_lsegs_end = pseg_start;
890                         goto try_next_pseg;
891                 }
892
893                 /* A valid super root was found. */
894                 ri->ri_cno = cno++;
895                 ri->ri_super_root = pseg_end;
896                 ri->ri_lsegs_start = ri->ri_lsegs_end = 0;
897
898                 nilfs_dispose_segment_list(&segments);
899                 sr_pseg_start = pseg_start;
900                 nilfs->ns_pseg_offset = pseg_start + nblocks - seg_start;
901                 nilfs->ns_seg_seq = seg_seq;
902                 nilfs->ns_segnum = segnum;
903                 nilfs->ns_cno = cno;  /* nilfs->ns_cno = ri->ri_cno + 1 */
904                 nilfs->ns_ctime = le64_to_cpu(sum->ss_create);
905                 nilfs->ns_nextnum = nextnum;
906
907                 if (scan_newer)
908                         ri->ri_need_recovery = NILFS_RECOVERY_SR_UPDATED;
909                 else {
910                         if (nilfs->ns_mount_state & NILFS_VALID_FS)
911                                 goto super_root_found;
912                         scan_newer = 1;
913                 }
914
915  try_next_pseg:
916                 /* Standing on a course, or met an inconsistent state */
917                 pseg_start += nblocks;
918                 if (pseg_start < seg_end)
919                         continue;
920                 goto feed_segment;
921
922  strayed:
923                 /* Off the trail */
924                 if (!scan_newer)
925                         /*
926                          * This can happen if a checkpoint was written without
927                          * barriers, or as a result of an I/O failure.
928                          */
929                         goto failed;
930
931  feed_segment:
932                 /* Looking to the next full segment */
933                 if (empty_seg++)
934                         goto super_root_found; /* found a valid super root */
935
936                 ret = nilfs_segment_list_add(&segments, segnum);
937                 if (unlikely(ret))
938                         goto failed;
939
940                 seg_seq++;
941                 segnum = nextnum;
942                 nilfs_get_segment_range(nilfs, segnum, &seg_start, &seg_end);
943                 pseg_start = seg_start;
944         }
945
946  super_root_found:
947         /* Updating pointers relating to the latest checkpoint */
948         brelse(bh_sum);
949         list_splice_tail(&segments, &ri->ri_used_segments);
950         nilfs->ns_last_pseg = sr_pseg_start;
951         nilfs->ns_last_seq = nilfs->ns_seg_seq;
952         nilfs->ns_last_cno = ri->ri_cno;
953         return 0;
954
955  failed:
956         brelse(bh_sum);
957         nilfs_dispose_segment_list(&segments);
958         return (ret < 0) ? ret : nilfs_warn_segment_error(ret);
959 }