1// SPDX-License-Identifier: GPL-2.0+
  2/*
  3 * recovery.c - NILFS recovery logic
  4 *
  5 * Copyright (C) 2005-2008 Nippon Telegraph and Telephone Corporation.
  6 *
  7 * Written by Ryusuke Konishi.
  8 */
  9
 10#include <linux/buffer_head.h>
 11#include <linux/blkdev.h>
 12#include <linux/swap.h>
 13#include <linux/slab.h>
 14#include <linux/crc32.h>
 15#include "nilfs.h"
 16#include "segment.h"
 17#include "sufile.h"
 18#include "page.h"
 19#include "segbuf.h"
 20
 21/*
 22 * Segment check result
 23 */
 24enum {
 25	NILFS_SEG_VALID,
 26	NILFS_SEG_NO_SUPER_ROOT,
 27	NILFS_SEG_FAIL_IO,
 28	NILFS_SEG_FAIL_MAGIC,
 29	NILFS_SEG_FAIL_SEQ,
 30	NILFS_SEG_FAIL_CHECKSUM_SUPER_ROOT,
 31	NILFS_SEG_FAIL_CHECKSUM_FULL,
 32	NILFS_SEG_FAIL_CONSISTENCY,
 33};
 34
 35/* work structure for recovery */
 36struct nilfs_recovery_block {
 37	ino_t ino;		/*
 38				 * Inode number of the file that this block
 39				 * belongs to
 40				 */
 41	sector_t blocknr;	/* block number */
 42	__u64 vblocknr;		/* virtual block number */
 43	unsigned long blkoff;	/* File offset of the data block (per block) */
 44	struct list_head list;
 45};
 46
 47
 48static int nilfs_warn_segment_error(struct super_block *sb, int err)
 49{
 50	const char *msg = NULL;
 51
 52	switch (err) {
 53	case NILFS_SEG_FAIL_IO:
 54		nilfs_msg(sb, KERN_ERR, "I/O error reading segment");
 55		return -EIO;
 56	case NILFS_SEG_FAIL_MAGIC:
 57		msg = "Magic number mismatch";
 58		break;
 59	case NILFS_SEG_FAIL_SEQ:
 60		msg = "Sequence number mismatch";
 61		break;
 62	case NILFS_SEG_FAIL_CHECKSUM_SUPER_ROOT:
 63		msg = "Checksum error in super root";
 64		break;
 65	case NILFS_SEG_FAIL_CHECKSUM_FULL:
 66		msg = "Checksum error in segment payload";
 67		break;
 68	case NILFS_SEG_FAIL_CONSISTENCY:
 69		msg = "Inconsistency found";
 70		break;
 71	case NILFS_SEG_NO_SUPER_ROOT:
 72		msg = "No super root in the last segment";
 73		break;
 74	default:
 75		nilfs_msg(sb, KERN_ERR, "unrecognized segment error %d", err);
 76		return -EINVAL;
 77	}
 78	nilfs_msg(sb, KERN_WARNING, "invalid segment: %s", msg);
 79	return -EINVAL;
 80}
 81
 82/**
 83 * nilfs_compute_checksum - compute checksum of blocks continuously
 84 * @nilfs: nilfs object
 85 * @bhs: buffer head of start block
 86 * @sum: place to store result
 87 * @offset: offset bytes in the first block
 88 * @check_bytes: number of bytes to be checked
 89 * @start: DBN of start block
 90 * @nblock: number of blocks to be checked
 91 */
 92static int nilfs_compute_checksum(struct the_nilfs *nilfs,
 93				  struct buffer_head *bhs, u32 *sum,
 94				  unsigned long offset, u64 check_bytes,
 95				  sector_t start, unsigned long nblock)
 96{
 97	unsigned int blocksize = nilfs->ns_blocksize;
 98	unsigned long size;
 99	u32 crc;
100
101	BUG_ON(offset >= blocksize);
102	check_bytes -= offset;
103	size = min_t(u64, check_bytes, blocksize - offset);
104	crc = crc32_le(nilfs->ns_crc_seed,
105		       (unsigned char *)bhs->b_data + offset, size);
106	if (--nblock > 0) {
107		do {
108			struct buffer_head *bh;
109
110			bh = __bread(nilfs->ns_bdev, ++start, blocksize);
111			if (!bh)
112				return -EIO;
113			check_bytes -= size;
114			size = min_t(u64, check_bytes, blocksize);
115			crc = crc32_le(crc, bh->b_data, size);
116			brelse(bh);
117		} while (--nblock > 0);
118	}
119	*sum = crc;
120	return 0;
121}
122
123/**
124 * nilfs_read_super_root_block - read super root block
125 * @nilfs: nilfs object
126 * @sr_block: disk block number of the super root block
127 * @pbh: address of a buffer_head pointer to return super root buffer
128 * @check: CRC check flag
129 */
130int nilfs_read_super_root_block(struct the_nilfs *nilfs, sector_t sr_block,
131				struct buffer_head **pbh, int check)
132{
133	struct buffer_head *bh_sr;
134	struct nilfs_super_root *sr;
135	u32 crc;
136	int ret;
137
138	*pbh = NULL;
139	bh_sr = __bread(nilfs->ns_bdev, sr_block, nilfs->ns_blocksize);
140	if (unlikely(!bh_sr)) {
141		ret = NILFS_SEG_FAIL_IO;
142		goto failed;
143	}
144
145	sr = (struct nilfs_super_root *)bh_sr->b_data;
146	if (check) {
147		unsigned int bytes = le16_to_cpu(sr->sr_bytes);
148
149		if (bytes == 0 || bytes > nilfs->ns_blocksize) {
150			ret = NILFS_SEG_FAIL_CHECKSUM_SUPER_ROOT;
151			goto failed_bh;
152		}
153		if (nilfs_compute_checksum(
154			    nilfs, bh_sr, &crc, sizeof(sr->sr_sum), bytes,
155			    sr_block, 1)) {
156			ret = NILFS_SEG_FAIL_IO;
157			goto failed_bh;
158		}
159		if (crc != le32_to_cpu(sr->sr_sum)) {
160			ret = NILFS_SEG_FAIL_CHECKSUM_SUPER_ROOT;
161			goto failed_bh;
162		}
163	}
164	*pbh = bh_sr;
165	return 0;
166
167 failed_bh:
168	brelse(bh_sr);
169
170 failed:
171	return nilfs_warn_segment_error(nilfs->ns_sb, ret);
172}
173
174/**
175 * nilfs_read_log_header - read summary header of the specified log
176 * @nilfs: nilfs object
177 * @start_blocknr: start block number of the log
178 * @sum: pointer to return segment summary structure
179 */
180static struct buffer_head *
181nilfs_read_log_header(struct the_nilfs *nilfs, sector_t start_blocknr,
182		      struct nilfs_segment_summary **sum)
183{
184	struct buffer_head *bh_sum;
185
186	bh_sum = __bread(nilfs->ns_bdev, start_blocknr, nilfs->ns_blocksize);
187	if (bh_sum)
188		*sum = (struct nilfs_segment_summary *)bh_sum->b_data;
189	return bh_sum;
190}
191
192/**
193 * nilfs_validate_log - verify consistency of log
194 * @nilfs: nilfs object
195 * @seg_seq: sequence number of segment
196 * @bh_sum: buffer head of summary block
197 * @sum: segment summary struct
198 */
199static int nilfs_validate_log(struct the_nilfs *nilfs, u64 seg_seq,
200			      struct buffer_head *bh_sum,
201			      struct nilfs_segment_summary *sum)
202{
203	unsigned long nblock;
204	u32 crc;
205	int ret;
206
207	ret = NILFS_SEG_FAIL_MAGIC;
208	if (le32_to_cpu(sum->ss_magic) != NILFS_SEGSUM_MAGIC)
209		goto out;
210
211	ret = NILFS_SEG_FAIL_SEQ;
212	if (le64_to_cpu(sum->ss_seq) != seg_seq)
213		goto out;
214
215	nblock = le32_to_cpu(sum->ss_nblocks);
216	ret = NILFS_SEG_FAIL_CONSISTENCY;
217	if (unlikely(nblock == 0 || nblock > nilfs->ns_blocks_per_segment))
218		/* This limits the number of blocks read in the CRC check */
219		goto out;
220
221	ret = NILFS_SEG_FAIL_IO;
222	if (nilfs_compute_checksum(nilfs, bh_sum, &crc, sizeof(sum->ss_datasum),
223				   ((u64)nblock << nilfs->ns_blocksize_bits),
224				   bh_sum->b_blocknr, nblock))
225		goto out;
226
227	ret = NILFS_SEG_FAIL_CHECKSUM_FULL;
228	if (crc != le32_to_cpu(sum->ss_datasum))
229		goto out;
230	ret = 0;
231out:
232	return ret;
233}
234
235/**
236 * nilfs_read_summary_info - read an item on summary blocks of a log
237 * @nilfs: nilfs object
238 * @pbh: the current buffer head on summary blocks [in, out]
239 * @offset: the current byte offset on summary blocks [in, out]
240 * @bytes: byte size of the item to be read
241 */
242static void *nilfs_read_summary_info(struct the_nilfs *nilfs,
243				     struct buffer_head **pbh,
244				     unsigned int *offset, unsigned int bytes)
245{
246	void *ptr;
247	sector_t blocknr;
248
249	BUG_ON((*pbh)->b_size < *offset);
250	if (bytes > (*pbh)->b_size - *offset) {
251		blocknr = (*pbh)->b_blocknr;
252		brelse(*pbh);
253		*pbh = __bread(nilfs->ns_bdev, blocknr + 1,
254			       nilfs->ns_blocksize);
255		if (unlikely(!*pbh))
256			return NULL;
257		*offset = 0;
258	}
259	ptr = (*pbh)->b_data + *offset;
260	*offset += bytes;
261	return ptr;
262}
263
264/**
265 * nilfs_skip_summary_info - skip items on summary blocks of a log
266 * @nilfs: nilfs object
267 * @pbh: the current buffer head on summary blocks [in, out]
268 * @offset: the current byte offset on summary blocks [in, out]
269 * @bytes: byte size of the item to be skipped
270 * @count: number of items to be skipped
271 */
272static void nilfs_skip_summary_info(struct the_nilfs *nilfs,
273				    struct buffer_head **pbh,
274				    unsigned int *offset, unsigned int bytes,
275				    unsigned long count)
276{
277	unsigned int rest_item_in_current_block
278		= ((*pbh)->b_size - *offset) / bytes;
279
280	if (count <= rest_item_in_current_block) {
281		*offset += bytes * count;
282	} else {
283		sector_t blocknr = (*pbh)->b_blocknr;
284		unsigned int nitem_per_block = (*pbh)->b_size / bytes;
285		unsigned int bcnt;
286
287		count -= rest_item_in_current_block;
288		bcnt = DIV_ROUND_UP(count, nitem_per_block);
289		*offset = bytes * (count - (bcnt - 1) * nitem_per_block);
290
291		brelse(*pbh);
292		*pbh = __bread(nilfs->ns_bdev, blocknr + bcnt,
293			       nilfs->ns_blocksize);
294	}
295}
296
297/**
298 * nilfs_scan_dsync_log - get block information of a log written for data sync
299 * @nilfs: nilfs object
300 * @start_blocknr: start block number of the log
301 * @sum: log summary information
302 * @head: list head to add nilfs_recovery_block struct
303 */
304static int nilfs_scan_dsync_log(struct the_nilfs *nilfs, sector_t start_blocknr,
305				struct nilfs_segment_summary *sum,
306				struct list_head *head)
307{
308	struct buffer_head *bh;
309	unsigned int offset;
310	u32 nfinfo, sumbytes;
311	sector_t blocknr;
312	ino_t ino;
313	int err = -EIO;
314
315	nfinfo = le32_to_cpu(sum->ss_nfinfo);
316	if (!nfinfo)
317		return 0;
318
319	sumbytes = le32_to_cpu(sum->ss_sumbytes);
320	blocknr = start_blocknr + DIV_ROUND_UP(sumbytes, nilfs->ns_blocksize);
321	bh = __bread(nilfs->ns_bdev, start_blocknr, nilfs->ns_blocksize);
322	if (unlikely(!bh))
323		goto out;
324
325	offset = le16_to_cpu(sum->ss_bytes);
326	for (;;) {
327		unsigned long nblocks, ndatablk, nnodeblk;
328		struct nilfs_finfo *finfo;
329
330		finfo = nilfs_read_summary_info(nilfs, &bh, &offset,
331						sizeof(*finfo));
332		if (unlikely(!finfo))
333			goto out;
334
335		ino = le64_to_cpu(finfo->fi_ino);
336		nblocks = le32_to_cpu(finfo->fi_nblocks);
337		ndatablk = le32_to_cpu(finfo->fi_ndatablk);
338		nnodeblk = nblocks - ndatablk;
339
340		while (ndatablk-- > 0) {
341			struct nilfs_recovery_block *rb;
342			struct nilfs_binfo_v *binfo;
343
344			binfo = nilfs_read_summary_info(nilfs, &bh, &offset,
345							sizeof(*binfo));
346			if (unlikely(!binfo))
347				goto out;
348
349			rb = kmalloc(sizeof(*rb), GFP_NOFS);
350			if (unlikely(!rb)) {
351				err = -ENOMEM;
352				goto out;
353			}
354			rb->ino = ino;
355			rb->blocknr = blocknr++;
356			rb->vblocknr = le64_to_cpu(binfo->bi_vblocknr);
357			rb->blkoff = le64_to_cpu(binfo->bi_blkoff);
358			/* INIT_LIST_HEAD(&rb->list); */
359			list_add_tail(&rb->list, head);
360		}
361		if (--nfinfo == 0)
362			break;
363		blocknr += nnodeblk; /* always 0 for data sync logs */
364		nilfs_skip_summary_info(nilfs, &bh, &offset, sizeof(__le64),
365					nnodeblk);
366		if (unlikely(!bh))
367			goto out;
368	}
369	err = 0;
370 out:
371	brelse(bh);   /* brelse(NULL) is just ignored */
372	return err;
373}
374
375static void dispose_recovery_list(struct list_head *head)
376{
377	while (!list_empty(head)) {
378		struct nilfs_recovery_block *rb;
379
380		rb = list_first_entry(head, struct nilfs_recovery_block, list);
381		list_del(&rb->list);
382		kfree(rb);
383	}
384}
385
386struct nilfs_segment_entry {
387	struct list_head	list;
388	__u64			segnum;
389};
390
391static int nilfs_segment_list_add(struct list_head *head, __u64 segnum)
392{
393	struct nilfs_segment_entry *ent = kmalloc(sizeof(*ent), GFP_NOFS);
394
395	if (unlikely(!ent))
396		return -ENOMEM;
397
398	ent->segnum = segnum;
399	INIT_LIST_HEAD(&ent->list);
400	list_add_tail(&ent->list, head);
401	return 0;
402}
403
404void nilfs_dispose_segment_list(struct list_head *head)
405{
406	while (!list_empty(head)) {
407		struct nilfs_segment_entry *ent;
408
409		ent = list_first_entry(head, struct nilfs_segment_entry, list);
410		list_del(&ent->list);
411		kfree(ent);
412	}
413}
414
415static int nilfs_prepare_segment_for_recovery(struct the_nilfs *nilfs,
416					      struct super_block *sb,
417					      struct nilfs_recovery_info *ri)
418{
419	struct list_head *head = &ri->ri_used_segments;
420	struct nilfs_segment_entry *ent, *n;
421	struct inode *sufile = nilfs->ns_sufile;
422	__u64 segnum[4];
423	int err;
424	int i;
425
426	segnum[0] = nilfs->ns_segnum;
427	segnum[1] = nilfs->ns_nextnum;
428	segnum[2] = ri->ri_segnum;
429	segnum[3] = ri->ri_nextnum;
430
431	/*
432	 * Releasing the next segment of the latest super root.
433	 * The next segment is invalidated by this recovery.
434	 */
435	err = nilfs_sufile_free(sufile, segnum[1]);
436	if (unlikely(err))
437		goto failed;
438
439	for (i = 1; i < 4; i++) {
440		err = nilfs_segment_list_add(head, segnum[i]);
441		if (unlikely(err))
442			goto failed;
443	}
444
445	/*
446	 * Collecting segments written after the latest super root.
447	 * These are marked dirty to avoid being reallocated in the next write.
448	 */
449	list_for_each_entry_safe(ent, n, head, list) {
450		if (ent->segnum != segnum[0]) {
451			err = nilfs_sufile_scrap(sufile, ent->segnum);
452			if (unlikely(err))
453				goto failed;
454		}
455		list_del(&ent->list);
456		kfree(ent);
457	}
458
459	/* Allocate new segments for recovery */
460	err = nilfs_sufile_alloc(sufile, &segnum[0]);
461	if (unlikely(err))
462		goto failed;
463
464	nilfs->ns_pseg_offset = 0;
465	nilfs->ns_seg_seq = ri->ri_seq + 2;
466	nilfs->ns_nextnum = nilfs->ns_segnum = segnum[0];
467
468 failed:
469	/* No need to recover sufile because it will be destroyed on error */
470	return err;
471}
472
473static int nilfs_recovery_copy_block(struct the_nilfs *nilfs,
474				     struct nilfs_recovery_block *rb,
475				     struct page *page)
476{
477	struct buffer_head *bh_org;
478	void *kaddr;
479
480	bh_org = __bread(nilfs->ns_bdev, rb->blocknr, nilfs->ns_blocksize);
481	if (unlikely(!bh_org))
482		return -EIO;
483
484	kaddr = kmap_atomic(page);
485	memcpy(kaddr + bh_offset(bh_org), bh_org->b_data, bh_org->b_size);
486	kunmap_atomic(kaddr);
487	brelse(bh_org);
488	return 0;
489}
490
491static int nilfs_recover_dsync_blocks(struct the_nilfs *nilfs,
492				      struct super_block *sb,
493				      struct nilfs_root *root,
494				      struct list_head *head,
495				      unsigned long *nr_salvaged_blocks)
496{
497	struct inode *inode;
498	struct nilfs_recovery_block *rb, *n;
499	unsigned int blocksize = nilfs->ns_blocksize;
500	struct page *page;
501	loff_t pos;
502	int err = 0, err2 = 0;
503
504	list_for_each_entry_safe(rb, n, head, list) {
505		inode = nilfs_iget(sb, root, rb->ino);
506		if (IS_ERR(inode)) {
507			err = PTR_ERR(inode);
508			inode = NULL;
509			goto failed_inode;
510		}
511
512		pos = rb->blkoff << inode->i_blkbits;
513		err = block_write_begin(inode->i_mapping, pos, blocksize,
514					0, &page, nilfs_get_block);
515		if (unlikely(err)) {
516			loff_t isize = inode->i_size;
517
518			if (pos + blocksize > isize)
519				nilfs_write_failed(inode->i_mapping,
520							pos + blocksize);
521			goto failed_inode;
522		}
523
524		err = nilfs_recovery_copy_block(nilfs, rb, page);
525		if (unlikely(err))
526			goto failed_page;
527
528		err = nilfs_set_file_dirty(inode, 1);
529		if (unlikely(err))
530			goto failed_page;
531
532		block_write_end(NULL, inode->i_mapping, pos, blocksize,
533				blocksize, page, NULL);
534
535		unlock_page(page);
536		put_page(page);
537
538		(*nr_salvaged_blocks)++;
539		goto next;
540
541 failed_page:
542		unlock_page(page);
543		put_page(page);
544
545 failed_inode:
546		nilfs_msg(sb, KERN_WARNING,
547			  "error %d recovering data block (ino=%lu, block-offset=%llu)",
548			  err, (unsigned long)rb->ino,
549			  (unsigned long long)rb->blkoff);
550		if (!err2)
551			err2 = err;
552 next:
553		iput(inode); /* iput(NULL) is just ignored */
554		list_del_init(&rb->list);
555		kfree(rb);
556	}
557	return err2;
558}
559
560/**
561 * nilfs_do_roll_forward - salvage logical segments newer than the latest
562 * checkpoint
563 * @nilfs: nilfs object
564 * @sb: super block instance
565 * @ri: pointer to a nilfs_recovery_info
566 */
567static int nilfs_do_roll_forward(struct the_nilfs *nilfs,
568				 struct super_block *sb,
569				 struct nilfs_root *root,
570				 struct nilfs_recovery_info *ri)
571{
572	struct buffer_head *bh_sum = NULL;
573	struct nilfs_segment_summary *sum = NULL;
574	sector_t pseg_start;
575	sector_t seg_start, seg_end;  /* Starting/ending DBN of full segment */
576	unsigned long nsalvaged_blocks = 0;
577	unsigned int flags;
578	u64 seg_seq;
579	__u64 segnum, nextnum = 0;
580	int empty_seg = 0;
581	int err = 0, ret;
582	LIST_HEAD(dsync_blocks);  /* list of data blocks to be recovered */
583	enum {
584		RF_INIT_ST,
585		RF_DSYNC_ST,   /* scanning data-sync segments */
586	};
587	int state = RF_INIT_ST;
588
589	pseg_start = ri->ri_lsegs_start;
590	seg_seq = ri->ri_lsegs_start_seq;
591	segnum = nilfs_get_segnum_of_block(nilfs, pseg_start);
592	nilfs_get_segment_range(nilfs, segnum, &seg_start, &seg_end);
593
594	while (segnum != ri->ri_segnum || pseg_start <= ri->ri_pseg_start) {
595		brelse(bh_sum);
596		bh_sum = nilfs_read_log_header(nilfs, pseg_start, &sum);
597		if (!bh_sum) {
598			err = -EIO;
599			goto failed;
600		}
601
602		ret = nilfs_validate_log(nilfs, seg_seq, bh_sum, sum);
603		if (ret) {
604			if (ret == NILFS_SEG_FAIL_IO) {
605				err = -EIO;
606				goto failed;
607			}
608			goto strayed;
609		}
610
611		flags = le16_to_cpu(sum->ss_flags);
612		if (flags & NILFS_SS_SR)
613			goto confused;
614
615		/* Found a valid partial segment; do recovery actions */
616		nextnum = nilfs_get_segnum_of_block(nilfs,
617						    le64_to_cpu(sum->ss_next));
618		empty_seg = 0;
619		nilfs->ns_ctime = le64_to_cpu(sum->ss_create);
620		if (!(flags & NILFS_SS_GC))
621			nilfs->ns_nongc_ctime = nilfs->ns_ctime;
622
623		switch (state) {
624		case RF_INIT_ST:
625			if (!(flags & NILFS_SS_LOGBGN) ||
626			    !(flags & NILFS_SS_SYNDT))
627				goto try_next_pseg;
628			state = RF_DSYNC_ST;
629			/* Fall through */
630		case RF_DSYNC_ST:
631			if (!(flags & NILFS_SS_SYNDT))
632				goto confused;
633
634			err = nilfs_scan_dsync_log(nilfs, pseg_start, sum,
635						   &dsync_blocks);
636			if (unlikely(err))
637				goto failed;
638			if (flags & NILFS_SS_LOGEND) {
639				err = nilfs_recover_dsync_blocks(
640					nilfs, sb, root, &dsync_blocks,
641					&nsalvaged_blocks);
642				if (unlikely(err))
643					goto failed;
644				state = RF_INIT_ST;
645			}
646			break; /* Fall through to try_next_pseg */
647		}
648
649 try_next_pseg:
650		if (pseg_start == ri->ri_lsegs_end)
651			break;
652		pseg_start += le32_to_cpu(sum->ss_nblocks);
653		if (pseg_start < seg_end)
654			continue;
655		goto feed_segment;
656
657 strayed:
658		if (pseg_start == ri->ri_lsegs_end)
659			break;
660
661 feed_segment:
662		/* Looking to the next full segment */
663		if (empty_seg++)
664			break;
665		seg_seq++;
666		segnum = nextnum;
667		nilfs_get_segment_range(nilfs, segnum, &seg_start, &seg_end);
668		pseg_start = seg_start;
669	}
670
671	if (nsalvaged_blocks) {
672		nilfs_msg(sb, KERN_INFO, "salvaged %lu blocks",
673			  nsalvaged_blocks);
674		ri->ri_need_recovery = NILFS_RECOVERY_ROLLFORWARD_DONE;
675	}
676 out:
677	brelse(bh_sum);
678	dispose_recovery_list(&dsync_blocks);
679	return err;
680
681 confused:
682	err = -EINVAL;
683 failed:
684	nilfs_msg(sb, KERN_ERR,
685		  "error %d roll-forwarding partial segment at blocknr = %llu",
686		  err, (unsigned long long)pseg_start);
687	goto out;
688}
689
690static void nilfs_finish_roll_forward(struct the_nilfs *nilfs,
691				      struct nilfs_recovery_info *ri)
692{
693	struct buffer_head *bh;
694	int err;
695
696	if (nilfs_get_segnum_of_block(nilfs, ri->ri_lsegs_start) !=
697	    nilfs_get_segnum_of_block(nilfs, ri->ri_super_root))
698		return;
699
700	bh = __getblk(nilfs->ns_bdev, ri->ri_lsegs_start, nilfs->ns_blocksize);
701	BUG_ON(!bh);
702	memset(bh->b_data, 0, bh->b_size);
703	set_buffer_dirty(bh);
704	err = sync_dirty_buffer(bh);
705	if (unlikely(err))
706		nilfs_msg(nilfs->ns_sb, KERN_WARNING,
707			  "buffer sync write failed during post-cleaning of recovery.");
708	brelse(bh);
709}
710
711/**
712 * nilfs_salvage_orphan_logs - salvage logs written after the latest checkpoint
713 * @nilfs: nilfs object
714 * @sb: super block instance
715 * @ri: pointer to a nilfs_recovery_info struct to store search results.
716 *
717 * Return Value: On success, 0 is returned.  On error, one of the following
718 * negative error code is returned.
719 *
720 * %-EINVAL - Inconsistent filesystem state.
721 *
722 * %-EIO - I/O error
723 *
724 * %-ENOSPC - No space left on device (only in a panic state).
725 *
726 * %-ERESTARTSYS - Interrupted.
727 *
728 * %-ENOMEM - Insufficient memory available.
729 */
730int nilfs_salvage_orphan_logs(struct the_nilfs *nilfs,
731			      struct super_block *sb,
732			      struct nilfs_recovery_info *ri)
733{
734	struct nilfs_root *root;
735	int err;
736
737	if (ri->ri_lsegs_start == 0 || ri->ri_lsegs_end == 0)
738		return 0;
739
740	err = nilfs_attach_checkpoint(sb, ri->ri_cno, true, &root);
741	if (unlikely(err)) {
742		nilfs_msg(sb, KERN_ERR,
743			  "error %d loading the latest checkpoint", err);
744		return err;
745	}
746
747	err = nilfs_do_roll_forward(nilfs, sb, root, ri);
748	if (unlikely(err))
749		goto failed;
750
751	if (ri->ri_need_recovery == NILFS_RECOVERY_ROLLFORWARD_DONE) {
752		err = nilfs_prepare_segment_for_recovery(nilfs, sb, ri);
753		if (unlikely(err)) {
754			nilfs_msg(sb, KERN_ERR,
755				  "error %d preparing segment for recovery",
756				  err);
757			goto failed;
758		}
759
760		err = nilfs_attach_log_writer(sb, root);
761		if (unlikely(err))
762			goto failed;
763
764		set_nilfs_discontinued(nilfs);
765		err = nilfs_construct_segment(sb);
766		nilfs_detach_log_writer(sb);
767
768		if (unlikely(err)) {
769			nilfs_msg(sb, KERN_ERR,
770				  "error %d writing segment for recovery",
771				  err);
772			goto failed;
773		}
774
775		nilfs_finish_roll_forward(nilfs, ri);
776	}
777
778 failed:
779	nilfs_put_root(root);
780	return err;
781}
782
783/**
784 * nilfs_search_super_root - search the latest valid super root
785 * @nilfs: the_nilfs
786 * @ri: pointer to a nilfs_recovery_info struct to store search results.
787 *
788 * nilfs_search_super_root() looks for the latest super-root from a partial
789 * segment pointed by the superblock.  It sets up struct the_nilfs through
790 * this search. It fills nilfs_recovery_info (ri) required for recovery.
791 *
792 * Return Value: On success, 0 is returned.  On error, one of the following
793 * negative error code is returned.
794 *
795 * %-EINVAL - No valid segment found
796 *
797 * %-EIO - I/O error
798 *
799 * %-ENOMEM - Insufficient memory available.
800 */
801int nilfs_search_super_root(struct the_nilfs *nilfs,
802			    struct nilfs_recovery_info *ri)
803{
804	struct buffer_head *bh_sum = NULL;
805	struct nilfs_segment_summary *sum = NULL;
806	sector_t pseg_start, pseg_end, sr_pseg_start = 0;
807	sector_t seg_start, seg_end; /* range of full segment (block number) */
808	sector_t b, end;
809	unsigned long nblocks;
810	unsigned int flags;
811	u64 seg_seq;
812	__u64 segnum, nextnum = 0;
813	__u64 cno;
814	LIST_HEAD(segments);
815	int empty_seg = 0, scan_newer = 0;
816	int ret;
817
818	pseg_start = nilfs->ns_last_pseg;
819	seg_seq = nilfs->ns_last_seq;
820	cno = nilfs->ns_last_cno;
821	segnum = nilfs_get_segnum_of_block(nilfs, pseg_start);
822
823	/* Calculate range of segment */
824	nilfs_get_segment_range(nilfs, segnum, &seg_start, &seg_end);
825
826	/* Read ahead segment */
827	b = seg_start;
828	while (b <= seg_end)
829		__breadahead(nilfs->ns_bdev, b++, nilfs->ns_blocksize);
830
831	for (;;) {
832		brelse(bh_sum);
833		ret = NILFS_SEG_FAIL_IO;
834		bh_sum = nilfs_read_log_header(nilfs, pseg_start, &sum);
835		if (!bh_sum)
836			goto failed;
837
838		ret = nilfs_validate_log(nilfs, seg_seq, bh_sum, sum);
839		if (ret) {
840			if (ret == NILFS_SEG_FAIL_IO)
841				goto failed;
842			goto strayed;
843		}
844
845		nblocks = le32_to_cpu(sum->ss_nblocks);
846		pseg_end = pseg_start + nblocks - 1;
847		if (unlikely(pseg_end > seg_end)) {
848			ret = NILFS_SEG_FAIL_CONSISTENCY;
849			goto strayed;
850		}
851
852		/* A valid partial segment */
853		ri->ri_pseg_start = pseg_start;
854		ri->ri_seq = seg_seq;
855		ri->ri_segnum = segnum;
856		nextnum = nilfs_get_segnum_of_block(nilfs,
857						    le64_to_cpu(sum->ss_next));
858		ri->ri_nextnum = nextnum;
859		empty_seg = 0;
860
861		flags = le16_to_cpu(sum->ss_flags);
862		if (!(flags & NILFS_SS_SR) && !scan_newer) {
863			/*
864			 * This will never happen because a superblock
865			 * (last_segment) always points to a pseg with
866			 * a super root.
867			 */
868			ret = NILFS_SEG_FAIL_CONSISTENCY;
869			goto failed;
870		}
871
872		if (pseg_start == seg_start) {
873			nilfs_get_segment_range(nilfs, nextnum, &b, &end);
874			while (b <= end)
875				__breadahead(nilfs->ns_bdev, b++,
876					     nilfs->ns_blocksize);
877		}
878		if (!(flags & NILFS_SS_SR)) {
879			if (!ri->ri_lsegs_start && (flags & NILFS_SS_LOGBGN)) {
880				ri->ri_lsegs_start = pseg_start;
881				ri->ri_lsegs_start_seq = seg_seq;
882			}
883			if (flags & NILFS_SS_LOGEND)
884				ri->ri_lsegs_end = pseg_start;
885			goto try_next_pseg;
886		}
887
888		/* A valid super root was found. */
889		ri->ri_cno = cno++;
890		ri->ri_super_root = pseg_end;
891		ri->ri_lsegs_start = ri->ri_lsegs_end = 0;
892
893		nilfs_dispose_segment_list(&segments);
894		sr_pseg_start = pseg_start;
895		nilfs->ns_pseg_offset = pseg_start + nblocks - seg_start;
896		nilfs->ns_seg_seq = seg_seq;
897		nilfs->ns_segnum = segnum;
898		nilfs->ns_cno = cno;  /* nilfs->ns_cno = ri->ri_cno + 1 */
899		nilfs->ns_ctime = le64_to_cpu(sum->ss_create);
900		nilfs->ns_nextnum = nextnum;
901
902		if (scan_newer)
903			ri->ri_need_recovery = NILFS_RECOVERY_SR_UPDATED;
904		else {
905			if (nilfs->ns_mount_state & NILFS_VALID_FS)
906				goto super_root_found;
907			scan_newer = 1;
908		}
909
910 try_next_pseg:
911		/* Standing on a course, or met an inconsistent state */
912		pseg_start += nblocks;
913		if (pseg_start < seg_end)
914			continue;
915		goto feed_segment;
916
917 strayed:
918		/* Off the trail */
919		if (!scan_newer)
920			/*
921			 * This can happen if a checkpoint was written without
922			 * barriers, or as a result of an I/O failure.
923			 */
924			goto failed;
925
926 feed_segment:
927		/* Looking to the next full segment */
928		if (empty_seg++)
929			goto super_root_found; /* found a valid super root */
930
931		ret = nilfs_segment_list_add(&segments, segnum);
932		if (unlikely(ret))
933			goto failed;
934
935		seg_seq++;
936		segnum = nextnum;
937		nilfs_get_segment_range(nilfs, segnum, &seg_start, &seg_end);
938		pseg_start = seg_start;
939	}
940
941 super_root_found:
942	/* Updating pointers relating to the latest checkpoint */
943	brelse(bh_sum);
944	list_splice_tail(&segments, &ri->ri_used_segments);
945	nilfs->ns_last_pseg = sr_pseg_start;
946	nilfs->ns_last_seq = nilfs->ns_seg_seq;
947	nilfs->ns_last_cno = ri->ri_cno;
948	return 0;
949
950 failed:
951	brelse(bh_sum);
952	nilfs_dispose_segment_list(&segments);
953	return ret < 0 ? ret : nilfs_warn_segment_error(nilfs->ns_sb, ret);
954}