xref: /linux/fs/xfs/xfs_log_recover.c (revision d9a9c94dbc8bfeab2b29f860d38e5056894813ec)
1 // SPDX-License-Identifier: GPL-2.0
2 /*
3  * Copyright (c) 2000-2006 Silicon Graphics, Inc.
4  * All Rights Reserved.
5  */
6 #include "xfs.h"
7 #include "xfs_fs.h"
8 #include "xfs_shared.h"
9 #include "xfs_format.h"
10 #include "xfs_log_format.h"
11 #include "xfs_trans_resv.h"
12 #include "xfs_bit.h"
13 #include "xfs_sb.h"
14 #include "xfs_mount.h"
15 #include "xfs_defer.h"
16 #include "xfs_inode.h"
17 #include "xfs_trans.h"
18 #include "xfs_log.h"
19 #include "xfs_log_priv.h"
20 #include "xfs_log_recover.h"
21 #include "xfs_trans_priv.h"
22 #include "xfs_alloc.h"
23 #include "xfs_ialloc.h"
24 #include "xfs_trace.h"
25 #include "xfs_icache.h"
26 #include "xfs_error.h"
27 #include "xfs_buf_item.h"
28 #include "xfs_ag.h"
29 #include "xfs_quota.h"
30 #include "xfs_reflink.h"
31 
32 #define BLK_AVG(blk1, blk2)	((blk1+blk2) >> 1)
33 
34 STATIC int
35 xlog_find_zeroed(
36 	struct xlog	*,
37 	xfs_daddr_t	*);
38 STATIC int
39 xlog_clear_stale_blocks(
40 	struct xlog	*,
41 	xfs_lsn_t);
42 STATIC int
43 xlog_do_recovery_pass(
44         struct xlog *, xfs_daddr_t, xfs_daddr_t, int, xfs_daddr_t *);
45 
46 /*
47  * Sector aligned buffer routines for buffer create/read/write/access
48  */
49 
50 /*
51  * Verify the log-relative block number and length in basic blocks are valid for
52  * an operation involving the given XFS log buffer. Returns true if the fields
53  * are valid, false otherwise.
54  */
55 static inline bool
xlog_verify_bno(struct xlog * log,xfs_daddr_t blk_no,int bbcount)56 xlog_verify_bno(
57 	struct xlog	*log,
58 	xfs_daddr_t	blk_no,
59 	int		bbcount)
60 {
61 	if (blk_no < 0 || blk_no >= log->l_logBBsize)
62 		return false;
63 	if (bbcount <= 0 || (blk_no + bbcount) > log->l_logBBsize)
64 		return false;
65 	return true;
66 }
67 
68 /*
69  * Allocate a buffer to hold log data.  The buffer needs to be able to map to
70  * a range of nbblks basic blocks at any valid offset within the log.
71  */
72 static char *
xlog_alloc_buffer(struct xlog * log,int nbblks)73 xlog_alloc_buffer(
74 	struct xlog	*log,
75 	int		nbblks)
76 {
77 	/*
78 	 * Pass log block 0 since we don't have an addr yet, buffer will be
79 	 * verified on read.
80 	 */
81 	if (XFS_IS_CORRUPT(log->l_mp, !xlog_verify_bno(log, 0, nbblks))) {
82 		xfs_warn(log->l_mp, "Invalid block length (0x%x) for buffer",
83 			nbblks);
84 		return NULL;
85 	}
86 
87 	/*
88 	 * We do log I/O in units of log sectors (a power-of-2 multiple of the
89 	 * basic block size), so we round up the requested size to accommodate
90 	 * the basic blocks required for complete log sectors.
91 	 *
92 	 * In addition, the buffer may be used for a non-sector-aligned block
93 	 * offset, in which case an I/O of the requested size could extend
94 	 * beyond the end of the buffer.  If the requested size is only 1 basic
95 	 * block it will never straddle a sector boundary, so this won't be an
96 	 * issue.  Nor will this be a problem if the log I/O is done in basic
97 	 * blocks (sector size 1).  But otherwise we extend the buffer by one
98 	 * extra log sector to ensure there's space to accommodate this
99 	 * possibility.
100 	 */
101 	if (nbblks > 1 && log->l_sectBBsize > 1)
102 		nbblks += log->l_sectBBsize;
103 	nbblks = round_up(nbblks, log->l_sectBBsize);
104 	return kvzalloc(BBTOB(nbblks), GFP_KERNEL | __GFP_RETRY_MAYFAIL);
105 }
106 
107 /*
108  * Return the address of the start of the given block number's data
109  * in a log buffer.  The buffer covers a log sector-aligned region.
110  */
111 static inline unsigned int
xlog_align(struct xlog * log,xfs_daddr_t blk_no)112 xlog_align(
113 	struct xlog	*log,
114 	xfs_daddr_t	blk_no)
115 {
116 	return BBTOB(blk_no & ((xfs_daddr_t)log->l_sectBBsize - 1));
117 }
118 
119 static int
xlog_do_io(struct xlog * log,xfs_daddr_t blk_no,unsigned int nbblks,char * data,enum req_op op)120 xlog_do_io(
121 	struct xlog		*log,
122 	xfs_daddr_t		blk_no,
123 	unsigned int		nbblks,
124 	char			*data,
125 	enum req_op		op)
126 {
127 	int			error;
128 
129 	if (XFS_IS_CORRUPT(log->l_mp, !xlog_verify_bno(log, blk_no, nbblks))) {
130 		xfs_warn(log->l_mp,
131 			 "Invalid log block/length (0x%llx, 0x%x) for buffer",
132 			 blk_no, nbblks);
133 		return -EFSCORRUPTED;
134 	}
135 
136 	blk_no = round_down(blk_no, log->l_sectBBsize);
137 	nbblks = round_up(nbblks, log->l_sectBBsize);
138 	ASSERT(nbblks > 0);
139 
140 	error = xfs_rw_bdev(log->l_targ->bt_bdev, log->l_logBBstart + blk_no,
141 			BBTOB(nbblks), data, op);
142 	if (error && !xlog_is_shutdown(log)) {
143 		xfs_alert(log->l_mp,
144 			  "log recovery %s I/O error at daddr 0x%llx len %d error %d",
145 			  op == REQ_OP_WRITE ? "write" : "read",
146 			  blk_no, nbblks, error);
147 	}
148 	return error;
149 }
150 
151 STATIC int
xlog_bread_noalign(struct xlog * log,xfs_daddr_t blk_no,int nbblks,char * data)152 xlog_bread_noalign(
153 	struct xlog	*log,
154 	xfs_daddr_t	blk_no,
155 	int		nbblks,
156 	char		*data)
157 {
158 	return xlog_do_io(log, blk_no, nbblks, data, REQ_OP_READ);
159 }
160 
161 STATIC int
xlog_bread(struct xlog * log,xfs_daddr_t blk_no,int nbblks,char * data,char ** offset)162 xlog_bread(
163 	struct xlog	*log,
164 	xfs_daddr_t	blk_no,
165 	int		nbblks,
166 	char		*data,
167 	char		**offset)
168 {
169 	int		error;
170 
171 	error = xlog_do_io(log, blk_no, nbblks, data, REQ_OP_READ);
172 	if (!error)
173 		*offset = data + xlog_align(log, blk_no);
174 	return error;
175 }
176 
177 STATIC int
xlog_bwrite(struct xlog * log,xfs_daddr_t blk_no,int nbblks,char * data)178 xlog_bwrite(
179 	struct xlog	*log,
180 	xfs_daddr_t	blk_no,
181 	int		nbblks,
182 	char		*data)
183 {
184 	return xlog_do_io(log, blk_no, nbblks, data, REQ_OP_WRITE);
185 }
186 
187 #ifdef DEBUG
188 /*
189  * dump debug superblock and log record information
190  */
191 STATIC void
xlog_header_check_dump(xfs_mount_t * mp,xlog_rec_header_t * head)192 xlog_header_check_dump(
193 	xfs_mount_t		*mp,
194 	xlog_rec_header_t	*head)
195 {
196 	xfs_debug(mp, "%s:  SB : uuid = %pU, fmt = %d",
197 		__func__, &mp->m_sb.sb_uuid, XLOG_FMT);
198 	xfs_debug(mp, "    log : uuid = %pU, fmt = %d",
199 		&head->h_fs_uuid, be32_to_cpu(head->h_fmt));
200 }
201 #else
202 #define xlog_header_check_dump(mp, head)
203 #endif
204 
205 /*
206  * check log record header for recovery
207  */
208 STATIC int
xlog_header_check_recover(xfs_mount_t * mp,xlog_rec_header_t * head)209 xlog_header_check_recover(
210 	xfs_mount_t		*mp,
211 	xlog_rec_header_t	*head)
212 {
213 	ASSERT(head->h_magicno == cpu_to_be32(XLOG_HEADER_MAGIC_NUM));
214 
215 	/*
216 	 * IRIX doesn't write the h_fmt field and leaves it zeroed
217 	 * (XLOG_FMT_UNKNOWN). This stops us from trying to recover
218 	 * a dirty log created in IRIX.
219 	 */
220 	if (XFS_IS_CORRUPT(mp, head->h_fmt != cpu_to_be32(XLOG_FMT))) {
221 		xfs_warn(mp,
222 	"dirty log written in incompatible format - can't recover");
223 		xlog_header_check_dump(mp, head);
224 		return -EFSCORRUPTED;
225 	}
226 	if (XFS_IS_CORRUPT(mp, !uuid_equal(&mp->m_sb.sb_uuid,
227 					   &head->h_fs_uuid))) {
228 		xfs_warn(mp,
229 	"dirty log entry has mismatched uuid - can't recover");
230 		xlog_header_check_dump(mp, head);
231 		return -EFSCORRUPTED;
232 	}
233 	return 0;
234 }
235 
236 /*
237  * read the head block of the log and check the header
238  */
239 STATIC int
xlog_header_check_mount(xfs_mount_t * mp,xlog_rec_header_t * head)240 xlog_header_check_mount(
241 	xfs_mount_t		*mp,
242 	xlog_rec_header_t	*head)
243 {
244 	ASSERT(head->h_magicno == cpu_to_be32(XLOG_HEADER_MAGIC_NUM));
245 
246 	if (uuid_is_null(&head->h_fs_uuid)) {
247 		/*
248 		 * IRIX doesn't write the h_fs_uuid or h_fmt fields. If
249 		 * h_fs_uuid is null, we assume this log was last mounted
250 		 * by IRIX and continue.
251 		 */
252 		xfs_warn(mp, "null uuid in log - IRIX style log");
253 	} else if (XFS_IS_CORRUPT(mp, !uuid_equal(&mp->m_sb.sb_uuid,
254 						  &head->h_fs_uuid))) {
255 		xfs_warn(mp, "log has mismatched uuid - can't recover");
256 		xlog_header_check_dump(mp, head);
257 		return -EFSCORRUPTED;
258 	}
259 	return 0;
260 }
261 
262 /*
263  * This routine finds (to an approximation) the first block in the physical
264  * log which contains the given cycle.  It uses a binary search algorithm.
265  * Note that the algorithm can not be perfect because the disk will not
266  * necessarily be perfect.
267  */
268 STATIC int
xlog_find_cycle_start(struct xlog * log,char * buffer,xfs_daddr_t first_blk,xfs_daddr_t * last_blk,uint cycle)269 xlog_find_cycle_start(
270 	struct xlog	*log,
271 	char		*buffer,
272 	xfs_daddr_t	first_blk,
273 	xfs_daddr_t	*last_blk,
274 	uint		cycle)
275 {
276 	char		*offset;
277 	xfs_daddr_t	mid_blk;
278 	xfs_daddr_t	end_blk;
279 	uint		mid_cycle;
280 	int		error;
281 
282 	end_blk = *last_blk;
283 	mid_blk = BLK_AVG(first_blk, end_blk);
284 	while (mid_blk != first_blk && mid_blk != end_blk) {
285 		error = xlog_bread(log, mid_blk, 1, buffer, &offset);
286 		if (error)
287 			return error;
288 		mid_cycle = xlog_get_cycle(offset);
289 		if (mid_cycle == cycle)
290 			end_blk = mid_blk;   /* last_half_cycle == mid_cycle */
291 		else
292 			first_blk = mid_blk; /* first_half_cycle == mid_cycle */
293 		mid_blk = BLK_AVG(first_blk, end_blk);
294 	}
295 	ASSERT((mid_blk == first_blk && mid_blk+1 == end_blk) ||
296 	       (mid_blk == end_blk && mid_blk-1 == first_blk));
297 
298 	*last_blk = end_blk;
299 
300 	return 0;
301 }
302 
303 /*
304  * Check that a range of blocks does not contain stop_on_cycle_no.
305  * Fill in *new_blk with the block offset where such a block is
306  * found, or with -1 (an invalid block number) if there is no such
307  * block in the range.  The scan needs to occur from front to back
308  * and the pointer into the region must be updated since a later
309  * routine will need to perform another test.
310  */
311 STATIC int
xlog_find_verify_cycle(struct xlog * log,xfs_daddr_t start_blk,int nbblks,uint stop_on_cycle_no,xfs_daddr_t * new_blk)312 xlog_find_verify_cycle(
313 	struct xlog	*log,
314 	xfs_daddr_t	start_blk,
315 	int		nbblks,
316 	uint		stop_on_cycle_no,
317 	xfs_daddr_t	*new_blk)
318 {
319 	xfs_daddr_t	i, j;
320 	uint		cycle;
321 	char		*buffer;
322 	xfs_daddr_t	bufblks;
323 	char		*buf = NULL;
324 	int		error = 0;
325 
326 	/*
327 	 * Greedily allocate a buffer big enough to handle the full
328 	 * range of basic blocks we'll be examining.  If that fails,
329 	 * try a smaller size.  We need to be able to read at least
330 	 * a log sector, or we're out of luck.
331 	 */
332 	bufblks = roundup_pow_of_two(nbblks);
333 	while (bufblks > log->l_logBBsize)
334 		bufblks >>= 1;
335 	while (!(buffer = xlog_alloc_buffer(log, bufblks))) {
336 		bufblks >>= 1;
337 		if (bufblks < log->l_sectBBsize)
338 			return -ENOMEM;
339 	}
340 
341 	for (i = start_blk; i < start_blk + nbblks; i += bufblks) {
342 		int	bcount;
343 
344 		bcount = min(bufblks, (start_blk + nbblks - i));
345 
346 		error = xlog_bread(log, i, bcount, buffer, &buf);
347 		if (error)
348 			goto out;
349 
350 		for (j = 0; j < bcount; j++) {
351 			cycle = xlog_get_cycle(buf);
352 			if (cycle == stop_on_cycle_no) {
353 				*new_blk = i+j;
354 				goto out;
355 			}
356 
357 			buf += BBSIZE;
358 		}
359 	}
360 
361 	*new_blk = -1;
362 
363 out:
364 	kvfree(buffer);
365 	return error;
366 }
367 
368 static inline int
xlog_logrec_hblks(struct xlog * log,struct xlog_rec_header * rh)369 xlog_logrec_hblks(struct xlog *log, struct xlog_rec_header *rh)
370 {
371 	if (xfs_has_logv2(log->l_mp)) {
372 		int	h_size = be32_to_cpu(rh->h_size);
373 
374 		if ((be32_to_cpu(rh->h_version) & XLOG_VERSION_2) &&
375 		    h_size > XLOG_HEADER_CYCLE_SIZE)
376 			return DIV_ROUND_UP(h_size, XLOG_HEADER_CYCLE_SIZE);
377 	}
378 	return 1;
379 }
380 
381 /*
382  * Potentially backup over partial log record write.
383  *
384  * In the typical case, last_blk is the number of the block directly after
385  * a good log record.  Therefore, we subtract one to get the block number
386  * of the last block in the given buffer.  extra_bblks contains the number
387  * of blocks we would have read on a previous read.  This happens when the
388  * last log record is split over the end of the physical log.
389  *
390  * extra_bblks is the number of blocks potentially verified on a previous
391  * call to this routine.
392  */
393 STATIC int
xlog_find_verify_log_record(struct xlog * log,xfs_daddr_t start_blk,xfs_daddr_t * last_blk,int extra_bblks)394 xlog_find_verify_log_record(
395 	struct xlog		*log,
396 	xfs_daddr_t		start_blk,
397 	xfs_daddr_t		*last_blk,
398 	int			extra_bblks)
399 {
400 	xfs_daddr_t		i;
401 	char			*buffer;
402 	char			*offset = NULL;
403 	xlog_rec_header_t	*head = NULL;
404 	int			error = 0;
405 	int			smallmem = 0;
406 	int			num_blks = *last_blk - start_blk;
407 	int			xhdrs;
408 
409 	ASSERT(start_blk != 0 || *last_blk != start_blk);
410 
411 	buffer = xlog_alloc_buffer(log, num_blks);
412 	if (!buffer) {
413 		buffer = xlog_alloc_buffer(log, 1);
414 		if (!buffer)
415 			return -ENOMEM;
416 		smallmem = 1;
417 	} else {
418 		error = xlog_bread(log, start_blk, num_blks, buffer, &offset);
419 		if (error)
420 			goto out;
421 		offset += ((num_blks - 1) << BBSHIFT);
422 	}
423 
424 	for (i = (*last_blk) - 1; i >= 0; i--) {
425 		if (i < start_blk) {
426 			/* valid log record not found */
427 			xfs_warn(log->l_mp,
428 		"Log inconsistent (didn't find previous header)");
429 			ASSERT(0);
430 			error = -EFSCORRUPTED;
431 			goto out;
432 		}
433 
434 		if (smallmem) {
435 			error = xlog_bread(log, i, 1, buffer, &offset);
436 			if (error)
437 				goto out;
438 		}
439 
440 		head = (xlog_rec_header_t *)offset;
441 
442 		if (head->h_magicno == cpu_to_be32(XLOG_HEADER_MAGIC_NUM))
443 			break;
444 
445 		if (!smallmem)
446 			offset -= BBSIZE;
447 	}
448 
449 	/*
450 	 * We hit the beginning of the physical log & still no header.  Return
451 	 * to caller.  If caller can handle a return of -1, then this routine
452 	 * will be called again for the end of the physical log.
453 	 */
454 	if (i == -1) {
455 		error = 1;
456 		goto out;
457 	}
458 
459 	/*
460 	 * We have the final block of the good log (the first block
461 	 * of the log record _before_ the head. So we check the uuid.
462 	 */
463 	if ((error = xlog_header_check_mount(log->l_mp, head)))
464 		goto out;
465 
466 	/*
467 	 * We may have found a log record header before we expected one.
468 	 * last_blk will be the 1st block # with a given cycle #.  We may end
469 	 * up reading an entire log record.  In this case, we don't want to
470 	 * reset last_blk.  Only when last_blk points in the middle of a log
471 	 * record do we update last_blk.
472 	 */
473 	xhdrs = xlog_logrec_hblks(log, head);
474 
475 	if (*last_blk - i + extra_bblks !=
476 	    BTOBB(be32_to_cpu(head->h_len)) + xhdrs)
477 		*last_blk = i;
478 
479 out:
480 	kvfree(buffer);
481 	return error;
482 }
483 
484 /*
485  * Head is defined to be the point of the log where the next log write
486  * could go.  This means that incomplete LR writes at the end are
487  * eliminated when calculating the head.  We aren't guaranteed that previous
488  * LR have complete transactions.  We only know that a cycle number of
489  * current cycle number -1 won't be present in the log if we start writing
490  * from our current block number.
491  *
492  * last_blk contains the block number of the first block with a given
493  * cycle number.
494  *
495  * Return: zero if normal, non-zero if error.
496  */
497 STATIC int
xlog_find_head(struct xlog * log,xfs_daddr_t * return_head_blk)498 xlog_find_head(
499 	struct xlog	*log,
500 	xfs_daddr_t	*return_head_blk)
501 {
502 	char		*buffer;
503 	char		*offset;
504 	xfs_daddr_t	new_blk, first_blk, start_blk, last_blk, head_blk;
505 	int		num_scan_bblks;
506 	uint		first_half_cycle, last_half_cycle;
507 	uint		stop_on_cycle;
508 	int		error, log_bbnum = log->l_logBBsize;
509 
510 	/* Is the end of the log device zeroed? */
511 	error = xlog_find_zeroed(log, &first_blk);
512 	if (error < 0) {
513 		xfs_warn(log->l_mp, "empty log check failed");
514 		return error;
515 	}
516 	if (error == 1) {
517 		*return_head_blk = first_blk;
518 
519 		/* Is the whole lot zeroed? */
520 		if (!first_blk) {
521 			/* Linux XFS shouldn't generate totally zeroed logs -
522 			 * mkfs etc write a dummy unmount record to a fresh
523 			 * log so we can store the uuid in there
524 			 */
525 			xfs_warn(log->l_mp, "totally zeroed log");
526 		}
527 
528 		return 0;
529 	}
530 
531 	first_blk = 0;			/* get cycle # of 1st block */
532 	buffer = xlog_alloc_buffer(log, 1);
533 	if (!buffer)
534 		return -ENOMEM;
535 
536 	error = xlog_bread(log, 0, 1, buffer, &offset);
537 	if (error)
538 		goto out_free_buffer;
539 
540 	first_half_cycle = xlog_get_cycle(offset);
541 
542 	last_blk = head_blk = log_bbnum - 1;	/* get cycle # of last block */
543 	error = xlog_bread(log, last_blk, 1, buffer, &offset);
544 	if (error)
545 		goto out_free_buffer;
546 
547 	last_half_cycle = xlog_get_cycle(offset);
548 	ASSERT(last_half_cycle != 0);
549 
550 	/*
551 	 * If the 1st half cycle number is equal to the last half cycle number,
552 	 * then the entire log is stamped with the same cycle number.  In this
553 	 * case, head_blk can't be set to zero (which makes sense).  The below
554 	 * math doesn't work out properly with head_blk equal to zero.  Instead,
555 	 * we set it to log_bbnum which is an invalid block number, but this
556 	 * value makes the math correct.  If head_blk doesn't changed through
557 	 * all the tests below, *head_blk is set to zero at the very end rather
558 	 * than log_bbnum.  In a sense, log_bbnum and zero are the same block
559 	 * in a circular file.
560 	 */
561 	if (first_half_cycle == last_half_cycle) {
562 		/*
563 		 * In this case we believe that the entire log should have
564 		 * cycle number last_half_cycle.  We need to scan backwards
565 		 * from the end verifying that there are no holes still
566 		 * containing last_half_cycle - 1.  If we find such a hole,
567 		 * then the start of that hole will be the new head.  The
568 		 * simple case looks like
569 		 *        x | x ... | x - 1 | x
570 		 * Another case that fits this picture would be
571 		 *        x | x + 1 | x ... | x
572 		 * In this case the head really is somewhere at the end of the
573 		 * log, as one of the latest writes at the beginning was
574 		 * incomplete.
575 		 * One more case is
576 		 *        x | x + 1 | x ... | x - 1 | x
577 		 * This is really the combination of the above two cases, and
578 		 * the head has to end up at the start of the x-1 hole at the
579 		 * end of the log.
580 		 *
581 		 * In the 256k log case, we will read from the beginning to the
582 		 * end of the log and search for cycle numbers equal to x-1.
583 		 * We don't worry about the x+1 blocks that we encounter,
584 		 * because we know that they cannot be the head since the log
585 		 * started with x.
586 		 */
587 		head_blk = log_bbnum;
588 		stop_on_cycle = last_half_cycle - 1;
589 	} else {
590 		/*
591 		 * In this case we want to find the first block with cycle
592 		 * number matching last_half_cycle.  We expect the log to be
593 		 * some variation on
594 		 *        x + 1 ... | x ... | x
595 		 * The first block with cycle number x (last_half_cycle) will
596 		 * be where the new head belongs.  First we do a binary search
597 		 * for the first occurrence of last_half_cycle.  The binary
598 		 * search may not be totally accurate, so then we scan back
599 		 * from there looking for occurrences of last_half_cycle before
600 		 * us.  If that backwards scan wraps around the beginning of
601 		 * the log, then we look for occurrences of last_half_cycle - 1
602 		 * at the end of the log.  The cases we're looking for look
603 		 * like
604 		 *                               v binary search stopped here
605 		 *        x + 1 ... | x | x + 1 | x ... | x
606 		 *                   ^ but we want to locate this spot
607 		 * or
608 		 *        <---------> less than scan distance
609 		 *        x + 1 ... | x ... | x - 1 | x
610 		 *                           ^ we want to locate this spot
611 		 */
612 		stop_on_cycle = last_half_cycle;
613 		error = xlog_find_cycle_start(log, buffer, first_blk, &head_blk,
614 				last_half_cycle);
615 		if (error)
616 			goto out_free_buffer;
617 	}
618 
619 	/*
620 	 * Now validate the answer.  Scan back some number of maximum possible
621 	 * blocks and make sure each one has the expected cycle number.  The
622 	 * maximum is determined by the total possible amount of buffering
623 	 * in the in-core log.  The following number can be made tighter if
624 	 * we actually look at the block size of the filesystem.
625 	 */
626 	num_scan_bblks = min_t(int, log_bbnum, XLOG_TOTAL_REC_SHIFT(log));
627 	if (head_blk >= num_scan_bblks) {
628 		/*
629 		 * We are guaranteed that the entire check can be performed
630 		 * in one buffer.
631 		 */
632 		start_blk = head_blk - num_scan_bblks;
633 		if ((error = xlog_find_verify_cycle(log,
634 						start_blk, num_scan_bblks,
635 						stop_on_cycle, &new_blk)))
636 			goto out_free_buffer;
637 		if (new_blk != -1)
638 			head_blk = new_blk;
639 	} else {		/* need to read 2 parts of log */
640 		/*
641 		 * We are going to scan backwards in the log in two parts.
642 		 * First we scan the physical end of the log.  In this part
643 		 * of the log, we are looking for blocks with cycle number
644 		 * last_half_cycle - 1.
645 		 * If we find one, then we know that the log starts there, as
646 		 * we've found a hole that didn't get written in going around
647 		 * the end of the physical log.  The simple case for this is
648 		 *        x + 1 ... | x ... | x - 1 | x
649 		 *        <---------> less than scan distance
650 		 * If all of the blocks at the end of the log have cycle number
651 		 * last_half_cycle, then we check the blocks at the start of
652 		 * the log looking for occurrences of last_half_cycle.  If we
653 		 * find one, then our current estimate for the location of the
654 		 * first occurrence of last_half_cycle is wrong and we move
655 		 * back to the hole we've found.  This case looks like
656 		 *        x + 1 ... | x | x + 1 | x ...
657 		 *                               ^ binary search stopped here
658 		 * Another case we need to handle that only occurs in 256k
659 		 * logs is
660 		 *        x + 1 ... | x ... | x+1 | x ...
661 		 *                   ^ binary search stops here
662 		 * In a 256k log, the scan at the end of the log will see the
663 		 * x + 1 blocks.  We need to skip past those since that is
664 		 * certainly not the head of the log.  By searching for
665 		 * last_half_cycle-1 we accomplish that.
666 		 */
667 		ASSERT(head_blk <= INT_MAX &&
668 			(xfs_daddr_t) num_scan_bblks >= head_blk);
669 		start_blk = log_bbnum - (num_scan_bblks - head_blk);
670 		if ((error = xlog_find_verify_cycle(log, start_blk,
671 					num_scan_bblks - (int)head_blk,
672 					(stop_on_cycle - 1), &new_blk)))
673 			goto out_free_buffer;
674 		if (new_blk != -1) {
675 			head_blk = new_blk;
676 			goto validate_head;
677 		}
678 
679 		/*
680 		 * Scan beginning of log now.  The last part of the physical
681 		 * log is good.  This scan needs to verify that it doesn't find
682 		 * the last_half_cycle.
683 		 */
684 		start_blk = 0;
685 		ASSERT(head_blk <= INT_MAX);
686 		if ((error = xlog_find_verify_cycle(log,
687 					start_blk, (int)head_blk,
688 					stop_on_cycle, &new_blk)))
689 			goto out_free_buffer;
690 		if (new_blk != -1)
691 			head_blk = new_blk;
692 	}
693 
694 validate_head:
695 	/*
696 	 * Now we need to make sure head_blk is not pointing to a block in
697 	 * the middle of a log record.
698 	 */
699 	num_scan_bblks = XLOG_REC_SHIFT(log);
700 	if (head_blk >= num_scan_bblks) {
701 		start_blk = head_blk - num_scan_bblks; /* don't read head_blk */
702 
703 		/* start ptr at last block ptr before head_blk */
704 		error = xlog_find_verify_log_record(log, start_blk, &head_blk, 0);
705 		if (error == 1)
706 			error = -EIO;
707 		if (error)
708 			goto out_free_buffer;
709 	} else {
710 		start_blk = 0;
711 		ASSERT(head_blk <= INT_MAX);
712 		error = xlog_find_verify_log_record(log, start_blk, &head_blk, 0);
713 		if (error < 0)
714 			goto out_free_buffer;
715 		if (error == 1) {
716 			/* We hit the beginning of the log during our search */
717 			start_blk = log_bbnum - (num_scan_bblks - head_blk);
718 			new_blk = log_bbnum;
719 			ASSERT(start_blk <= INT_MAX &&
720 				(xfs_daddr_t) log_bbnum-start_blk >= 0);
721 			ASSERT(head_blk <= INT_MAX);
722 			error = xlog_find_verify_log_record(log, start_blk,
723 							&new_blk, (int)head_blk);
724 			if (error == 1)
725 				error = -EIO;
726 			if (error)
727 				goto out_free_buffer;
728 			if (new_blk != log_bbnum)
729 				head_blk = new_blk;
730 		} else if (error)
731 			goto out_free_buffer;
732 	}
733 
734 	kvfree(buffer);
735 	if (head_blk == log_bbnum)
736 		*return_head_blk = 0;
737 	else
738 		*return_head_blk = head_blk;
739 	/*
740 	 * When returning here, we have a good block number.  Bad block
741 	 * means that during a previous crash, we didn't have a clean break
742 	 * from cycle number N to cycle number N-1.  In this case, we need
743 	 * to find the first block with cycle number N-1.
744 	 */
745 	return 0;
746 
747 out_free_buffer:
748 	kvfree(buffer);
749 	if (error)
750 		xfs_warn(log->l_mp, "failed to find log head");
751 	return error;
752 }
753 
754 /*
755  * Seek backwards in the log for log record headers.
756  *
757  * Given a starting log block, walk backwards until we find the provided number
758  * of records or hit the provided tail block. The return value is the number of
759  * records encountered or a negative error code. The log block and buffer
760  * pointer of the last record seen are returned in rblk and rhead respectively.
761  */
762 STATIC int
xlog_rseek_logrec_hdr(struct xlog * log,xfs_daddr_t head_blk,xfs_daddr_t tail_blk,int count,char * buffer,xfs_daddr_t * rblk,struct xlog_rec_header ** rhead,bool * wrapped)763 xlog_rseek_logrec_hdr(
764 	struct xlog		*log,
765 	xfs_daddr_t		head_blk,
766 	xfs_daddr_t		tail_blk,
767 	int			count,
768 	char			*buffer,
769 	xfs_daddr_t		*rblk,
770 	struct xlog_rec_header	**rhead,
771 	bool			*wrapped)
772 {
773 	int			i;
774 	int			error;
775 	int			found = 0;
776 	char			*offset = NULL;
777 	xfs_daddr_t		end_blk;
778 
779 	*wrapped = false;
780 
781 	/*
782 	 * Walk backwards from the head block until we hit the tail or the first
783 	 * block in the log.
784 	 */
785 	end_blk = head_blk > tail_blk ? tail_blk : 0;
786 	for (i = (int) head_blk - 1; i >= end_blk; i--) {
787 		error = xlog_bread(log, i, 1, buffer, &offset);
788 		if (error)
789 			goto out_error;
790 
791 		if (*(__be32 *) offset == cpu_to_be32(XLOG_HEADER_MAGIC_NUM)) {
792 			*rblk = i;
793 			*rhead = (struct xlog_rec_header *) offset;
794 			if (++found == count)
795 				break;
796 		}
797 	}
798 
799 	/*
800 	 * If we haven't hit the tail block or the log record header count,
801 	 * start looking again from the end of the physical log. Note that
802 	 * callers can pass head == tail if the tail is not yet known.
803 	 */
804 	if (tail_blk >= head_blk && found != count) {
805 		for (i = log->l_logBBsize - 1; i >= (int) tail_blk; i--) {
806 			error = xlog_bread(log, i, 1, buffer, &offset);
807 			if (error)
808 				goto out_error;
809 
810 			if (*(__be32 *)offset ==
811 			    cpu_to_be32(XLOG_HEADER_MAGIC_NUM)) {
812 				*wrapped = true;
813 				*rblk = i;
814 				*rhead = (struct xlog_rec_header *) offset;
815 				if (++found == count)
816 					break;
817 			}
818 		}
819 	}
820 
821 	return found;
822 
823 out_error:
824 	return error;
825 }
826 
827 /*
828  * Seek forward in the log for log record headers.
829  *
830  * Given head and tail blocks, walk forward from the tail block until we find
831  * the provided number of records or hit the head block. The return value is the
832  * number of records encountered or a negative error code. The log block and
833  * buffer pointer of the last record seen are returned in rblk and rhead
834  * respectively.
835  */
836 STATIC int
xlog_seek_logrec_hdr(struct xlog * log,xfs_daddr_t head_blk,xfs_daddr_t tail_blk,int count,char * buffer,xfs_daddr_t * rblk,struct xlog_rec_header ** rhead,bool * wrapped)837 xlog_seek_logrec_hdr(
838 	struct xlog		*log,
839 	xfs_daddr_t		head_blk,
840 	xfs_daddr_t		tail_blk,
841 	int			count,
842 	char			*buffer,
843 	xfs_daddr_t		*rblk,
844 	struct xlog_rec_header	**rhead,
845 	bool			*wrapped)
846 {
847 	int			i;
848 	int			error;
849 	int			found = 0;
850 	char			*offset = NULL;
851 	xfs_daddr_t		end_blk;
852 
853 	*wrapped = false;
854 
855 	/*
856 	 * Walk forward from the tail block until we hit the head or the last
857 	 * block in the log.
858 	 */
859 	end_blk = head_blk > tail_blk ? head_blk : log->l_logBBsize - 1;
860 	for (i = (int) tail_blk; i <= end_blk; i++) {
861 		error = xlog_bread(log, i, 1, buffer, &offset);
862 		if (error)
863 			goto out_error;
864 
865 		if (*(__be32 *) offset == cpu_to_be32(XLOG_HEADER_MAGIC_NUM)) {
866 			*rblk = i;
867 			*rhead = (struct xlog_rec_header *) offset;
868 			if (++found == count)
869 				break;
870 		}
871 	}
872 
873 	/*
874 	 * If we haven't hit the head block or the log record header count,
875 	 * start looking again from the start of the physical log.
876 	 */
877 	if (tail_blk > head_blk && found != count) {
878 		for (i = 0; i < (int) head_blk; i++) {
879 			error = xlog_bread(log, i, 1, buffer, &offset);
880 			if (error)
881 				goto out_error;
882 
883 			if (*(__be32 *)offset ==
884 			    cpu_to_be32(XLOG_HEADER_MAGIC_NUM)) {
885 				*wrapped = true;
886 				*rblk = i;
887 				*rhead = (struct xlog_rec_header *) offset;
888 				if (++found == count)
889 					break;
890 			}
891 		}
892 	}
893 
894 	return found;
895 
896 out_error:
897 	return error;
898 }
899 
900 /*
901  * Calculate distance from head to tail (i.e., unused space in the log).
902  */
903 static inline int
xlog_tail_distance(struct xlog * log,xfs_daddr_t head_blk,xfs_daddr_t tail_blk)904 xlog_tail_distance(
905 	struct xlog	*log,
906 	xfs_daddr_t	head_blk,
907 	xfs_daddr_t	tail_blk)
908 {
909 	if (head_blk < tail_blk)
910 		return tail_blk - head_blk;
911 
912 	return tail_blk + (log->l_logBBsize - head_blk);
913 }
914 
915 /*
916  * Verify the log tail. This is particularly important when torn or incomplete
917  * writes have been detected near the front of the log and the head has been
918  * walked back accordingly.
919  *
920  * We also have to handle the case where the tail was pinned and the head
921  * blocked behind the tail right before a crash. If the tail had been pushed
922  * immediately prior to the crash and the subsequent checkpoint was only
923  * partially written, it's possible it overwrote the last referenced tail in the
924  * log with garbage. This is not a coherency problem because the tail must have
925  * been pushed before it can be overwritten, but appears as log corruption to
926  * recovery because we have no way to know the tail was updated if the
927  * subsequent checkpoint didn't write successfully.
928  *
929  * Therefore, CRC check the log from tail to head. If a failure occurs and the
930  * offending record is within max iclog bufs from the head, walk the tail
931  * forward and retry until a valid tail is found or corruption is detected out
932  * of the range of a possible overwrite.
933  */
934 STATIC int
xlog_verify_tail(struct xlog * log,xfs_daddr_t head_blk,xfs_daddr_t * tail_blk,int hsize)935 xlog_verify_tail(
936 	struct xlog		*log,
937 	xfs_daddr_t		head_blk,
938 	xfs_daddr_t		*tail_blk,
939 	int			hsize)
940 {
941 	struct xlog_rec_header	*thead;
942 	char			*buffer;
943 	xfs_daddr_t		first_bad;
944 	int			error = 0;
945 	bool			wrapped;
946 	xfs_daddr_t		tmp_tail;
947 	xfs_daddr_t		orig_tail = *tail_blk;
948 
949 	buffer = xlog_alloc_buffer(log, 1);
950 	if (!buffer)
951 		return -ENOMEM;
952 
953 	/*
954 	 * Make sure the tail points to a record (returns positive count on
955 	 * success).
956 	 */
957 	error = xlog_seek_logrec_hdr(log, head_blk, *tail_blk, 1, buffer,
958 			&tmp_tail, &thead, &wrapped);
959 	if (error < 0)
960 		goto out;
961 	if (*tail_blk != tmp_tail)
962 		*tail_blk = tmp_tail;
963 
964 	/*
965 	 * Run a CRC check from the tail to the head. We can't just check
966 	 * MAX_ICLOGS records past the tail because the tail may point to stale
967 	 * blocks cleared during the search for the head/tail. These blocks are
968 	 * overwritten with zero-length records and thus record count is not a
969 	 * reliable indicator of the iclog state before a crash.
970 	 */
971 	first_bad = 0;
972 	error = xlog_do_recovery_pass(log, head_blk, *tail_blk,
973 				      XLOG_RECOVER_CRCPASS, &first_bad);
974 	while ((error == -EFSBADCRC || error == -EFSCORRUPTED) && first_bad) {
975 		int	tail_distance;
976 
977 		/*
978 		 * Is corruption within range of the head? If so, retry from
979 		 * the next record. Otherwise return an error.
980 		 */
981 		tail_distance = xlog_tail_distance(log, head_blk, first_bad);
982 		if (tail_distance > BTOBB(XLOG_MAX_ICLOGS * hsize))
983 			break;
984 
985 		/* skip to the next record; returns positive count on success */
986 		error = xlog_seek_logrec_hdr(log, head_blk, first_bad, 2,
987 				buffer, &tmp_tail, &thead, &wrapped);
988 		if (error < 0)
989 			goto out;
990 
991 		*tail_blk = tmp_tail;
992 		first_bad = 0;
993 		error = xlog_do_recovery_pass(log, head_blk, *tail_blk,
994 					      XLOG_RECOVER_CRCPASS, &first_bad);
995 	}
996 
997 	if (!error && *tail_blk != orig_tail)
998 		xfs_warn(log->l_mp,
999 		"Tail block (0x%llx) overwrite detected. Updated to 0x%llx",
1000 			 orig_tail, *tail_blk);
1001 out:
1002 	kvfree(buffer);
1003 	return error;
1004 }
1005 
1006 /*
1007  * Detect and trim torn writes from the head of the log.
1008  *
1009  * Storage without sector atomicity guarantees can result in torn writes in the
1010  * log in the event of a crash. Our only means to detect this scenario is via
1011  * CRC verification. While we can't always be certain that CRC verification
1012  * failure is due to a torn write vs. an unrelated corruption, we do know that
1013  * only a certain number (XLOG_MAX_ICLOGS) of log records can be written out at
1014  * one time. Therefore, CRC verify up to XLOG_MAX_ICLOGS records at the head of
1015  * the log and treat failures in this range as torn writes as a matter of
1016  * policy. In the event of CRC failure, the head is walked back to the last good
1017  * record in the log and the tail is updated from that record and verified.
1018  */
1019 STATIC int
xlog_verify_head(struct xlog * log,xfs_daddr_t * head_blk,xfs_daddr_t * tail_blk,char * buffer,xfs_daddr_t * rhead_blk,struct xlog_rec_header ** rhead,bool * wrapped)1020 xlog_verify_head(
1021 	struct xlog		*log,
1022 	xfs_daddr_t		*head_blk,	/* in/out: unverified head */
1023 	xfs_daddr_t		*tail_blk,	/* out: tail block */
1024 	char			*buffer,
1025 	xfs_daddr_t		*rhead_blk,	/* start blk of last record */
1026 	struct xlog_rec_header	**rhead,	/* ptr to last record */
1027 	bool			*wrapped)	/* last rec. wraps phys. log */
1028 {
1029 	struct xlog_rec_header	*tmp_rhead;
1030 	char			*tmp_buffer;
1031 	xfs_daddr_t		first_bad;
1032 	xfs_daddr_t		tmp_rhead_blk;
1033 	int			found;
1034 	int			error;
1035 	bool			tmp_wrapped;
1036 
1037 	/*
1038 	 * Check the head of the log for torn writes. Search backwards from the
1039 	 * head until we hit the tail or the maximum number of log record I/Os
1040 	 * that could have been in flight at one time. Use a temporary buffer so
1041 	 * we don't trash the rhead/buffer pointers from the caller.
1042 	 */
1043 	tmp_buffer = xlog_alloc_buffer(log, 1);
1044 	if (!tmp_buffer)
1045 		return -ENOMEM;
1046 	error = xlog_rseek_logrec_hdr(log, *head_blk, *tail_blk,
1047 				      XLOG_MAX_ICLOGS, tmp_buffer,
1048 				      &tmp_rhead_blk, &tmp_rhead, &tmp_wrapped);
1049 	kvfree(tmp_buffer);
1050 	if (error < 0)
1051 		return error;
1052 
1053 	/*
1054 	 * Now run a CRC verification pass over the records starting at the
1055 	 * block found above to the current head. If a CRC failure occurs, the
1056 	 * log block of the first bad record is saved in first_bad.
1057 	 */
1058 	error = xlog_do_recovery_pass(log, *head_blk, tmp_rhead_blk,
1059 				      XLOG_RECOVER_CRCPASS, &first_bad);
1060 	if ((error == -EFSBADCRC || error == -EFSCORRUPTED) && first_bad) {
1061 		/*
1062 		 * We've hit a potential torn write. Reset the error and warn
1063 		 * about it.
1064 		 */
1065 		error = 0;
1066 		xfs_warn(log->l_mp,
1067 "Torn write (CRC failure) detected at log block 0x%llx. Truncating head block from 0x%llx.",
1068 			 first_bad, *head_blk);
1069 
1070 		/*
1071 		 * Get the header block and buffer pointer for the last good
1072 		 * record before the bad record.
1073 		 *
1074 		 * Note that xlog_find_tail() clears the blocks at the new head
1075 		 * (i.e., the records with invalid CRC) if the cycle number
1076 		 * matches the current cycle.
1077 		 */
1078 		found = xlog_rseek_logrec_hdr(log, first_bad, *tail_blk, 1,
1079 				buffer, rhead_blk, rhead, wrapped);
1080 		if (found < 0)
1081 			return found;
1082 		if (found == 0)		/* XXX: right thing to do here? */
1083 			return -EIO;
1084 
1085 		/*
1086 		 * Reset the head block to the starting block of the first bad
1087 		 * log record and set the tail block based on the last good
1088 		 * record.
1089 		 *
1090 		 * Bail out if the updated head/tail match as this indicates
1091 		 * possible corruption outside of the acceptable
1092 		 * (XLOG_MAX_ICLOGS) range. This is a job for xfs_repair...
1093 		 */
1094 		*head_blk = first_bad;
1095 		*tail_blk = BLOCK_LSN(be64_to_cpu((*rhead)->h_tail_lsn));
1096 		if (*head_blk == *tail_blk) {
1097 			ASSERT(0);
1098 			return 0;
1099 		}
1100 	}
1101 	if (error)
1102 		return error;
1103 
1104 	return xlog_verify_tail(log, *head_blk, tail_blk,
1105 				be32_to_cpu((*rhead)->h_size));
1106 }
1107 
1108 /*
1109  * We need to make sure we handle log wrapping properly, so we can't use the
1110  * calculated logbno directly. Make sure it wraps to the correct bno inside the
1111  * log.
1112  *
1113  * The log is limited to 32 bit sizes, so we use the appropriate modulus
1114  * operation here and cast it back to a 64 bit daddr on return.
1115  */
1116 static inline xfs_daddr_t
xlog_wrap_logbno(struct xlog * log,xfs_daddr_t bno)1117 xlog_wrap_logbno(
1118 	struct xlog		*log,
1119 	xfs_daddr_t		bno)
1120 {
1121 	int			mod;
1122 
1123 	div_s64_rem(bno, log->l_logBBsize, &mod);
1124 	return mod;
1125 }
1126 
1127 /*
1128  * Check whether the head of the log points to an unmount record. In other
1129  * words, determine whether the log is clean. If so, update the in-core state
1130  * appropriately.
1131  */
1132 static int
xlog_check_unmount_rec(struct xlog * log,xfs_daddr_t * head_blk,xfs_daddr_t * tail_blk,struct xlog_rec_header * rhead,xfs_daddr_t rhead_blk,char * buffer,bool * clean)1133 xlog_check_unmount_rec(
1134 	struct xlog		*log,
1135 	xfs_daddr_t		*head_blk,
1136 	xfs_daddr_t		*tail_blk,
1137 	struct xlog_rec_header	*rhead,
1138 	xfs_daddr_t		rhead_blk,
1139 	char			*buffer,
1140 	bool			*clean)
1141 {
1142 	struct xlog_op_header	*op_head;
1143 	xfs_daddr_t		umount_data_blk;
1144 	xfs_daddr_t		after_umount_blk;
1145 	int			hblks;
1146 	int			error;
1147 	char			*offset;
1148 
1149 	*clean = false;
1150 
1151 	/*
1152 	 * Look for unmount record. If we find it, then we know there was a
1153 	 * clean unmount. Since 'i' could be the last block in the physical
1154 	 * log, we convert to a log block before comparing to the head_blk.
1155 	 *
1156 	 * Save the current tail lsn to use to pass to xlog_clear_stale_blocks()
1157 	 * below. We won't want to clear the unmount record if there is one, so
1158 	 * we pass the lsn of the unmount record rather than the block after it.
1159 	 */
1160 	hblks = xlog_logrec_hblks(log, rhead);
1161 	after_umount_blk = xlog_wrap_logbno(log,
1162 			rhead_blk + hblks + BTOBB(be32_to_cpu(rhead->h_len)));
1163 
1164 	if (*head_blk == after_umount_blk &&
1165 	    be32_to_cpu(rhead->h_num_logops) == 1) {
1166 		umount_data_blk = xlog_wrap_logbno(log, rhead_blk + hblks);
1167 		error = xlog_bread(log, umount_data_blk, 1, buffer, &offset);
1168 		if (error)
1169 			return error;
1170 
1171 		op_head = (struct xlog_op_header *)offset;
1172 		if (op_head->oh_flags & XLOG_UNMOUNT_TRANS) {
1173 			/*
1174 			 * Set tail and last sync so that newly written log
1175 			 * records will point recovery to after the current
1176 			 * unmount record.
1177 			 */
1178 			xlog_assign_atomic_lsn(&log->l_tail_lsn,
1179 					log->l_curr_cycle, after_umount_blk);
1180 			log->l_ailp->ail_head_lsn =
1181 					atomic64_read(&log->l_tail_lsn);
1182 			*tail_blk = after_umount_blk;
1183 
1184 			*clean = true;
1185 		}
1186 	}
1187 
1188 	return 0;
1189 }
1190 
1191 static void
xlog_set_state(struct xlog * log,xfs_daddr_t head_blk,struct xlog_rec_header * rhead,xfs_daddr_t rhead_blk,bool bump_cycle)1192 xlog_set_state(
1193 	struct xlog		*log,
1194 	xfs_daddr_t		head_blk,
1195 	struct xlog_rec_header	*rhead,
1196 	xfs_daddr_t		rhead_blk,
1197 	bool			bump_cycle)
1198 {
1199 	/*
1200 	 * Reset log values according to the state of the log when we
1201 	 * crashed.  In the case where head_blk == 0, we bump curr_cycle
1202 	 * one because the next write starts a new cycle rather than
1203 	 * continuing the cycle of the last good log record.  At this
1204 	 * point we have guaranteed that all partial log records have been
1205 	 * accounted for.  Therefore, we know that the last good log record
1206 	 * written was complete and ended exactly on the end boundary
1207 	 * of the physical log.
1208 	 */
1209 	log->l_prev_block = rhead_blk;
1210 	log->l_curr_block = (int)head_blk;
1211 	log->l_curr_cycle = be32_to_cpu(rhead->h_cycle);
1212 	if (bump_cycle)
1213 		log->l_curr_cycle++;
1214 	atomic64_set(&log->l_tail_lsn, be64_to_cpu(rhead->h_tail_lsn));
1215 	log->l_ailp->ail_head_lsn = be64_to_cpu(rhead->h_lsn);
1216 }
1217 
1218 /*
1219  * Find the sync block number or the tail of the log.
1220  *
1221  * This will be the block number of the last record to have its
1222  * associated buffers synced to disk.  Every log record header has
1223  * a sync lsn embedded in it.  LSNs hold block numbers, so it is easy
1224  * to get a sync block number.  The only concern is to figure out which
1225  * log record header to believe.
1226  *
1227  * The following algorithm uses the log record header with the largest
1228  * lsn.  The entire log record does not need to be valid.  We only care
1229  * that the header is valid.
1230  *
1231  * We could speed up search by using current head_blk buffer, but it is not
1232  * available.
1233  */
1234 STATIC int
xlog_find_tail(struct xlog * log,xfs_daddr_t * head_blk,xfs_daddr_t * tail_blk)1235 xlog_find_tail(
1236 	struct xlog		*log,
1237 	xfs_daddr_t		*head_blk,
1238 	xfs_daddr_t		*tail_blk)
1239 {
1240 	xlog_rec_header_t	*rhead;
1241 	char			*offset = NULL;
1242 	char			*buffer;
1243 	int			error;
1244 	xfs_daddr_t		rhead_blk;
1245 	xfs_lsn_t		tail_lsn;
1246 	bool			wrapped = false;
1247 	bool			clean = false;
1248 
1249 	/*
1250 	 * Find previous log record
1251 	 */
1252 	if ((error = xlog_find_head(log, head_blk)))
1253 		return error;
1254 	ASSERT(*head_blk < INT_MAX);
1255 
1256 	buffer = xlog_alloc_buffer(log, 1);
1257 	if (!buffer)
1258 		return -ENOMEM;
1259 	if (*head_blk == 0) {				/* special case */
1260 		error = xlog_bread(log, 0, 1, buffer, &offset);
1261 		if (error)
1262 			goto done;
1263 
1264 		if (xlog_get_cycle(offset) == 0) {
1265 			*tail_blk = 0;
1266 			/* leave all other log inited values alone */
1267 			goto done;
1268 		}
1269 	}
1270 
1271 	/*
1272 	 * Search backwards through the log looking for the log record header
1273 	 * block. This wraps all the way back around to the head so something is
1274 	 * seriously wrong if we can't find it.
1275 	 */
1276 	error = xlog_rseek_logrec_hdr(log, *head_blk, *head_blk, 1, buffer,
1277 				      &rhead_blk, &rhead, &wrapped);
1278 	if (error < 0)
1279 		goto done;
1280 	if (!error) {
1281 		xfs_warn(log->l_mp, "%s: couldn't find sync record", __func__);
1282 		error = -EFSCORRUPTED;
1283 		goto done;
1284 	}
1285 	*tail_blk = BLOCK_LSN(be64_to_cpu(rhead->h_tail_lsn));
1286 
1287 	/*
1288 	 * Set the log state based on the current head record.
1289 	 */
1290 	xlog_set_state(log, *head_blk, rhead, rhead_blk, wrapped);
1291 	tail_lsn = atomic64_read(&log->l_tail_lsn);
1292 
1293 	/*
1294 	 * Look for an unmount record at the head of the log. This sets the log
1295 	 * state to determine whether recovery is necessary.
1296 	 */
1297 	error = xlog_check_unmount_rec(log, head_blk, tail_blk, rhead,
1298 				       rhead_blk, buffer, &clean);
1299 	if (error)
1300 		goto done;
1301 
1302 	/*
1303 	 * Verify the log head if the log is not clean (e.g., we have anything
1304 	 * but an unmount record at the head). This uses CRC verification to
1305 	 * detect and trim torn writes. If discovered, CRC failures are
1306 	 * considered torn writes and the log head is trimmed accordingly.
1307 	 *
1308 	 * Note that we can only run CRC verification when the log is dirty
1309 	 * because there's no guarantee that the log data behind an unmount
1310 	 * record is compatible with the current architecture.
1311 	 */
1312 	if (!clean) {
1313 		xfs_daddr_t	orig_head = *head_blk;
1314 
1315 		error = xlog_verify_head(log, head_blk, tail_blk, buffer,
1316 					 &rhead_blk, &rhead, &wrapped);
1317 		if (error)
1318 			goto done;
1319 
1320 		/* update in-core state again if the head changed */
1321 		if (*head_blk != orig_head) {
1322 			xlog_set_state(log, *head_blk, rhead, rhead_blk,
1323 				       wrapped);
1324 			tail_lsn = atomic64_read(&log->l_tail_lsn);
1325 			error = xlog_check_unmount_rec(log, head_blk, tail_blk,
1326 						       rhead, rhead_blk, buffer,
1327 						       &clean);
1328 			if (error)
1329 				goto done;
1330 		}
1331 	}
1332 
1333 	/*
1334 	 * Note that the unmount was clean. If the unmount was not clean, we
1335 	 * need to know this to rebuild the superblock counters from the perag
1336 	 * headers if we have a filesystem using non-persistent counters.
1337 	 */
1338 	if (clean)
1339 		xfs_set_clean(log->l_mp);
1340 
1341 	/*
1342 	 * Make sure that there are no blocks in front of the head
1343 	 * with the same cycle number as the head.  This can happen
1344 	 * because we allow multiple outstanding log writes concurrently,
1345 	 * and the later writes might make it out before earlier ones.
1346 	 *
1347 	 * We use the lsn from before modifying it so that we'll never
1348 	 * overwrite the unmount record after a clean unmount.
1349 	 *
1350 	 * Do this only if we are going to recover the filesystem
1351 	 *
1352 	 * NOTE: This used to say "if (!readonly)"
1353 	 * However on Linux, we can & do recover a read-only filesystem.
1354 	 * We only skip recovery if NORECOVERY is specified on mount,
1355 	 * in which case we would not be here.
1356 	 *
1357 	 * But... if the -device- itself is readonly, just skip this.
1358 	 * We can't recover this device anyway, so it won't matter.
1359 	 */
1360 	if (!xfs_readonly_buftarg(log->l_targ))
1361 		error = xlog_clear_stale_blocks(log, tail_lsn);
1362 
1363 done:
1364 	kvfree(buffer);
1365 
1366 	if (error)
1367 		xfs_warn(log->l_mp, "failed to locate log tail");
1368 	return error;
1369 }
1370 
1371 /*
1372  * Is the log zeroed at all?
1373  *
1374  * The last binary search should be changed to perform an X block read
1375  * once X becomes small enough.  You can then search linearly through
1376  * the X blocks.  This will cut down on the number of reads we need to do.
1377  *
1378  * If the log is partially zeroed, this routine will pass back the blkno
1379  * of the first block with cycle number 0.  It won't have a complete LR
1380  * preceding it.
1381  *
1382  * Return:
1383  *	0  => the log is completely written to
1384  *	1 => use *blk_no as the first block of the log
1385  *	<0 => error has occurred
1386  */
1387 STATIC int
xlog_find_zeroed(struct xlog * log,xfs_daddr_t * blk_no)1388 xlog_find_zeroed(
1389 	struct xlog	*log,
1390 	xfs_daddr_t	*blk_no)
1391 {
1392 	char		*buffer;
1393 	char		*offset;
1394 	uint	        first_cycle, last_cycle;
1395 	xfs_daddr_t	new_blk, last_blk, start_blk;
1396 	xfs_daddr_t     num_scan_bblks;
1397 	int	        error, log_bbnum = log->l_logBBsize;
1398 	int		ret = 1;
1399 
1400 	*blk_no = 0;
1401 
1402 	/* check totally zeroed log */
1403 	buffer = xlog_alloc_buffer(log, 1);
1404 	if (!buffer)
1405 		return -ENOMEM;
1406 	error = xlog_bread(log, 0, 1, buffer, &offset);
1407 	if (error)
1408 		goto out_free_buffer;
1409 
1410 	first_cycle = xlog_get_cycle(offset);
1411 	if (first_cycle == 0) {		/* completely zeroed log */
1412 		*blk_no = 0;
1413 		goto out_free_buffer;
1414 	}
1415 
1416 	/* check partially zeroed log */
1417 	error = xlog_bread(log, log_bbnum-1, 1, buffer, &offset);
1418 	if (error)
1419 		goto out_free_buffer;
1420 
1421 	last_cycle = xlog_get_cycle(offset);
1422 	if (last_cycle != 0) {		/* log completely written to */
1423 		ret = 0;
1424 		goto out_free_buffer;
1425 	}
1426 
1427 	/* we have a partially zeroed log */
1428 	last_blk = log_bbnum-1;
1429 	error = xlog_find_cycle_start(log, buffer, 0, &last_blk, 0);
1430 	if (error)
1431 		goto out_free_buffer;
1432 
1433 	/*
1434 	 * Validate the answer.  Because there is no way to guarantee that
1435 	 * the entire log is made up of log records which are the same size,
1436 	 * we scan over the defined maximum blocks.  At this point, the maximum
1437 	 * is not chosen to mean anything special.   XXXmiken
1438 	 */
1439 	num_scan_bblks = XLOG_TOTAL_REC_SHIFT(log);
1440 	ASSERT(num_scan_bblks <= INT_MAX);
1441 
1442 	if (last_blk < num_scan_bblks)
1443 		num_scan_bblks = last_blk;
1444 	start_blk = last_blk - num_scan_bblks;
1445 
1446 	/*
1447 	 * We search for any instances of cycle number 0 that occur before
1448 	 * our current estimate of the head.  What we're trying to detect is
1449 	 *        1 ... | 0 | 1 | 0...
1450 	 *                       ^ binary search ends here
1451 	 */
1452 	if ((error = xlog_find_verify_cycle(log, start_blk,
1453 					 (int)num_scan_bblks, 0, &new_blk)))
1454 		goto out_free_buffer;
1455 	if (new_blk != -1)
1456 		last_blk = new_blk;
1457 
1458 	/*
1459 	 * Potentially backup over partial log record write.  We don't need
1460 	 * to search the end of the log because we know it is zero.
1461 	 */
1462 	error = xlog_find_verify_log_record(log, start_blk, &last_blk, 0);
1463 	if (error == 1)
1464 		error = -EIO;
1465 	if (error)
1466 		goto out_free_buffer;
1467 
1468 	*blk_no = last_blk;
1469 out_free_buffer:
1470 	kvfree(buffer);
1471 	if (error)
1472 		return error;
1473 	return ret;
1474 }
1475 
1476 /*
1477  * These are simple subroutines used by xlog_clear_stale_blocks() below
1478  * to initialize a buffer full of empty log record headers and write
1479  * them into the log.
1480  */
1481 STATIC void
xlog_add_record(struct xlog * log,char * buf,int cycle,int block,int tail_cycle,int tail_block)1482 xlog_add_record(
1483 	struct xlog		*log,
1484 	char			*buf,
1485 	int			cycle,
1486 	int			block,
1487 	int			tail_cycle,
1488 	int			tail_block)
1489 {
1490 	xlog_rec_header_t	*recp = (xlog_rec_header_t *)buf;
1491 
1492 	memset(buf, 0, BBSIZE);
1493 	recp->h_magicno = cpu_to_be32(XLOG_HEADER_MAGIC_NUM);
1494 	recp->h_cycle = cpu_to_be32(cycle);
1495 	recp->h_version = cpu_to_be32(
1496 			xfs_has_logv2(log->l_mp) ? 2 : 1);
1497 	recp->h_lsn = cpu_to_be64(xlog_assign_lsn(cycle, block));
1498 	recp->h_tail_lsn = cpu_to_be64(xlog_assign_lsn(tail_cycle, tail_block));
1499 	recp->h_fmt = cpu_to_be32(XLOG_FMT);
1500 	memcpy(&recp->h_fs_uuid, &log->l_mp->m_sb.sb_uuid, sizeof(uuid_t));
1501 }
1502 
1503 STATIC int
xlog_write_log_records(struct xlog * log,int cycle,int start_block,int blocks,int tail_cycle,int tail_block)1504 xlog_write_log_records(
1505 	struct xlog	*log,
1506 	int		cycle,
1507 	int		start_block,
1508 	int		blocks,
1509 	int		tail_cycle,
1510 	int		tail_block)
1511 {
1512 	char		*offset;
1513 	char		*buffer;
1514 	int		balign, ealign;
1515 	int		sectbb = log->l_sectBBsize;
1516 	int		end_block = start_block + blocks;
1517 	int		bufblks;
1518 	int		error = 0;
1519 	int		i, j = 0;
1520 
1521 	/*
1522 	 * Greedily allocate a buffer big enough to handle the full
1523 	 * range of basic blocks to be written.  If that fails, try
1524 	 * a smaller size.  We need to be able to write at least a
1525 	 * log sector, or we're out of luck.
1526 	 */
1527 	bufblks = roundup_pow_of_two(blocks);
1528 	while (bufblks > log->l_logBBsize)
1529 		bufblks >>= 1;
1530 	while (!(buffer = xlog_alloc_buffer(log, bufblks))) {
1531 		bufblks >>= 1;
1532 		if (bufblks < sectbb)
1533 			return -ENOMEM;
1534 	}
1535 
1536 	/* We may need to do a read at the start to fill in part of
1537 	 * the buffer in the starting sector not covered by the first
1538 	 * write below.
1539 	 */
1540 	balign = round_down(start_block, sectbb);
1541 	if (balign != start_block) {
1542 		error = xlog_bread_noalign(log, start_block, 1, buffer);
1543 		if (error)
1544 			goto out_free_buffer;
1545 
1546 		j = start_block - balign;
1547 	}
1548 
1549 	for (i = start_block; i < end_block; i += bufblks) {
1550 		int		bcount, endcount;
1551 
1552 		bcount = min(bufblks, end_block - start_block);
1553 		endcount = bcount - j;
1554 
1555 		/* We may need to do a read at the end to fill in part of
1556 		 * the buffer in the final sector not covered by the write.
1557 		 * If this is the same sector as the above read, skip it.
1558 		 */
1559 		ealign = round_down(end_block, sectbb);
1560 		if (j == 0 && (start_block + endcount > ealign)) {
1561 			error = xlog_bread_noalign(log, ealign, sectbb,
1562 					buffer + BBTOB(ealign - start_block));
1563 			if (error)
1564 				break;
1565 
1566 		}
1567 
1568 		offset = buffer + xlog_align(log, start_block);
1569 		for (; j < endcount; j++) {
1570 			xlog_add_record(log, offset, cycle, i+j,
1571 					tail_cycle, tail_block);
1572 			offset += BBSIZE;
1573 		}
1574 		error = xlog_bwrite(log, start_block, endcount, buffer);
1575 		if (error)
1576 			break;
1577 		start_block += endcount;
1578 		j = 0;
1579 	}
1580 
1581 out_free_buffer:
1582 	kvfree(buffer);
1583 	return error;
1584 }
1585 
1586 /*
1587  * This routine is called to blow away any incomplete log writes out
1588  * in front of the log head.  We do this so that we won't become confused
1589  * if we come up, write only a little bit more, and then crash again.
1590  * If we leave the partial log records out there, this situation could
1591  * cause us to think those partial writes are valid blocks since they
1592  * have the current cycle number.  We get rid of them by overwriting them
1593  * with empty log records with the old cycle number rather than the
1594  * current one.
1595  *
1596  * The tail lsn is passed in rather than taken from
1597  * the log so that we will not write over the unmount record after a
1598  * clean unmount in a 512 block log.  Doing so would leave the log without
1599  * any valid log records in it until a new one was written.  If we crashed
1600  * during that time we would not be able to recover.
1601  */
1602 STATIC int
xlog_clear_stale_blocks(struct xlog * log,xfs_lsn_t tail_lsn)1603 xlog_clear_stale_blocks(
1604 	struct xlog	*log,
1605 	xfs_lsn_t	tail_lsn)
1606 {
1607 	int		tail_cycle, head_cycle;
1608 	int		tail_block, head_block;
1609 	int		tail_distance, max_distance;
1610 	int		distance;
1611 	int		error;
1612 
1613 	tail_cycle = CYCLE_LSN(tail_lsn);
1614 	tail_block = BLOCK_LSN(tail_lsn);
1615 	head_cycle = log->l_curr_cycle;
1616 	head_block = log->l_curr_block;
1617 
1618 	/*
1619 	 * Figure out the distance between the new head of the log
1620 	 * and the tail.  We want to write over any blocks beyond the
1621 	 * head that we may have written just before the crash, but
1622 	 * we don't want to overwrite the tail of the log.
1623 	 */
1624 	if (head_cycle == tail_cycle) {
1625 		/*
1626 		 * The tail is behind the head in the physical log,
1627 		 * so the distance from the head to the tail is the
1628 		 * distance from the head to the end of the log plus
1629 		 * the distance from the beginning of the log to the
1630 		 * tail.
1631 		 */
1632 		if (XFS_IS_CORRUPT(log->l_mp,
1633 				   head_block < tail_block ||
1634 				   head_block >= log->l_logBBsize))
1635 			return -EFSCORRUPTED;
1636 		tail_distance = tail_block + (log->l_logBBsize - head_block);
1637 	} else {
1638 		/*
1639 		 * The head is behind the tail in the physical log,
1640 		 * so the distance from the head to the tail is just
1641 		 * the tail block minus the head block.
1642 		 */
1643 		if (XFS_IS_CORRUPT(log->l_mp,
1644 				   head_block >= tail_block ||
1645 				   head_cycle != tail_cycle + 1))
1646 			return -EFSCORRUPTED;
1647 		tail_distance = tail_block - head_block;
1648 	}
1649 
1650 	/*
1651 	 * If the head is right up against the tail, we can't clear
1652 	 * anything.
1653 	 */
1654 	if (tail_distance <= 0) {
1655 		ASSERT(tail_distance == 0);
1656 		return 0;
1657 	}
1658 
1659 	max_distance = XLOG_TOTAL_REC_SHIFT(log);
1660 	/*
1661 	 * Take the smaller of the maximum amount of outstanding I/O
1662 	 * we could have and the distance to the tail to clear out.
1663 	 * We take the smaller so that we don't overwrite the tail and
1664 	 * we don't waste all day writing from the head to the tail
1665 	 * for no reason.
1666 	 */
1667 	max_distance = min(max_distance, tail_distance);
1668 
1669 	if ((head_block + max_distance) <= log->l_logBBsize) {
1670 		/*
1671 		 * We can stomp all the blocks we need to without
1672 		 * wrapping around the end of the log.  Just do it
1673 		 * in a single write.  Use the cycle number of the
1674 		 * current cycle minus one so that the log will look like:
1675 		 *     n ... | n - 1 ...
1676 		 */
1677 		error = xlog_write_log_records(log, (head_cycle - 1),
1678 				head_block, max_distance, tail_cycle,
1679 				tail_block);
1680 		if (error)
1681 			return error;
1682 	} else {
1683 		/*
1684 		 * We need to wrap around the end of the physical log in
1685 		 * order to clear all the blocks.  Do it in two separate
1686 		 * I/Os.  The first write should be from the head to the
1687 		 * end of the physical log, and it should use the current
1688 		 * cycle number minus one just like above.
1689 		 */
1690 		distance = log->l_logBBsize - head_block;
1691 		error = xlog_write_log_records(log, (head_cycle - 1),
1692 				head_block, distance, tail_cycle,
1693 				tail_block);
1694 
1695 		if (error)
1696 			return error;
1697 
1698 		/*
1699 		 * Now write the blocks at the start of the physical log.
1700 		 * This writes the remainder of the blocks we want to clear.
1701 		 * It uses the current cycle number since we're now on the
1702 		 * same cycle as the head so that we get:
1703 		 *    n ... n ... | n - 1 ...
1704 		 *    ^^^^^ blocks we're writing
1705 		 */
1706 		distance = max_distance - (log->l_logBBsize - head_block);
1707 		error = xlog_write_log_records(log, head_cycle, 0, distance,
1708 				tail_cycle, tail_block);
1709 		if (error)
1710 			return error;
1711 	}
1712 
1713 	return 0;
1714 }
1715 
1716 /*
1717  * Release the recovered intent item in the AIL that matches the given intent
1718  * type and intent id.
1719  */
1720 void
xlog_recover_release_intent(struct xlog * log,unsigned short intent_type,uint64_t intent_id)1721 xlog_recover_release_intent(
1722 	struct xlog			*log,
1723 	unsigned short			intent_type,
1724 	uint64_t			intent_id)
1725 {
1726 	struct xfs_defer_pending	*dfp, *n;
1727 
1728 	list_for_each_entry_safe(dfp, n, &log->r_dfops, dfp_list) {
1729 		struct xfs_log_item	*lip = dfp->dfp_intent;
1730 
1731 		if (lip->li_type != intent_type)
1732 			continue;
1733 		if (!lip->li_ops->iop_match(lip, intent_id))
1734 			continue;
1735 
1736 		ASSERT(xlog_item_is_intent(lip));
1737 
1738 		xfs_defer_cancel_recovery(log->l_mp, dfp);
1739 	}
1740 }
1741 
1742 int
xlog_recover_iget(struct xfs_mount * mp,xfs_ino_t ino,struct xfs_inode ** ipp)1743 xlog_recover_iget(
1744 	struct xfs_mount	*mp,
1745 	xfs_ino_t		ino,
1746 	struct xfs_inode	**ipp)
1747 {
1748 	int			error;
1749 
1750 	error = xfs_iget(mp, NULL, ino, 0, 0, ipp);
1751 	if (error)
1752 		return error;
1753 
1754 	error = xfs_qm_dqattach(*ipp);
1755 	if (error) {
1756 		xfs_irele(*ipp);
1757 		return error;
1758 	}
1759 
1760 	if (VFS_I(*ipp)->i_nlink == 0)
1761 		xfs_iflags_set(*ipp, XFS_IRECOVERY);
1762 
1763 	return 0;
1764 }
1765 
1766 /*
1767  * Get an inode so that we can recover a log operation.
1768  *
1769  * Log intent items that target inodes effectively contain a file handle.
1770  * Check that the generation number matches the intent item like we do for
1771  * other file handles.  Log intent items defined after this validation weakness
1772  * was identified must use this function.
1773  */
1774 int
xlog_recover_iget_handle(struct xfs_mount * mp,xfs_ino_t ino,uint32_t gen,struct xfs_inode ** ipp)1775 xlog_recover_iget_handle(
1776 	struct xfs_mount	*mp,
1777 	xfs_ino_t		ino,
1778 	uint32_t		gen,
1779 	struct xfs_inode	**ipp)
1780 {
1781 	struct xfs_inode	*ip;
1782 	int			error;
1783 
1784 	error = xlog_recover_iget(mp, ino, &ip);
1785 	if (error)
1786 		return error;
1787 
1788 	if (VFS_I(ip)->i_generation != gen) {
1789 		xfs_irele(ip);
1790 		return -EFSCORRUPTED;
1791 	}
1792 
1793 	*ipp = ip;
1794 	return 0;
1795 }
1796 
1797 /******************************************************************************
1798  *
1799  *		Log recover routines
1800  *
1801  ******************************************************************************
1802  */
1803 static const struct xlog_recover_item_ops *xlog_recover_item_ops[] = {
1804 	&xlog_buf_item_ops,
1805 	&xlog_inode_item_ops,
1806 	&xlog_dquot_item_ops,
1807 	&xlog_quotaoff_item_ops,
1808 	&xlog_icreate_item_ops,
1809 	&xlog_efi_item_ops,
1810 	&xlog_efd_item_ops,
1811 	&xlog_rui_item_ops,
1812 	&xlog_rud_item_ops,
1813 	&xlog_cui_item_ops,
1814 	&xlog_cud_item_ops,
1815 	&xlog_bui_item_ops,
1816 	&xlog_bud_item_ops,
1817 	&xlog_attri_item_ops,
1818 	&xlog_attrd_item_ops,
1819 	&xlog_xmi_item_ops,
1820 	&xlog_xmd_item_ops,
1821 	&xlog_rtefi_item_ops,
1822 	&xlog_rtefd_item_ops,
1823 	&xlog_rtrui_item_ops,
1824 	&xlog_rtrud_item_ops,
1825 	&xlog_rtcui_item_ops,
1826 	&xlog_rtcud_item_ops,
1827 };
1828 
1829 static const struct xlog_recover_item_ops *
xlog_find_item_ops(struct xlog_recover_item * item)1830 xlog_find_item_ops(
1831 	struct xlog_recover_item		*item)
1832 {
1833 	unsigned int				i;
1834 
1835 	for (i = 0; i < ARRAY_SIZE(xlog_recover_item_ops); i++)
1836 		if (ITEM_TYPE(item) == xlog_recover_item_ops[i]->item_type)
1837 			return xlog_recover_item_ops[i];
1838 
1839 	return NULL;
1840 }
1841 
1842 /*
1843  * Sort the log items in the transaction.
1844  *
1845  * The ordering constraints are defined by the inode allocation and unlink
1846  * behaviour. The rules are:
1847  *
1848  *	1. Every item is only logged once in a given transaction. Hence it
1849  *	   represents the last logged state of the item. Hence ordering is
1850  *	   dependent on the order in which operations need to be performed so
1851  *	   required initial conditions are always met.
1852  *
1853  *	2. Cancelled buffers are recorded in pass 1 in a separate table and
1854  *	   there's nothing to replay from them so we can simply cull them
1855  *	   from the transaction. However, we can't do that until after we've
1856  *	   replayed all the other items because they may be dependent on the
1857  *	   cancelled buffer and replaying the cancelled buffer can remove it
1858  *	   form the cancelled buffer table. Hence they have to be done last.
1859  *
1860  *	3. Inode allocation buffers must be replayed before inode items that
1861  *	   read the buffer and replay changes into it. For filesystems using the
1862  *	   ICREATE transactions, this means XFS_LI_ICREATE objects need to get
1863  *	   treated the same as inode allocation buffers as they create and
1864  *	   initialise the buffers directly.
1865  *
1866  *	4. Inode unlink buffers must be replayed after inode items are replayed.
1867  *	   This ensures that inodes are completely flushed to the inode buffer
1868  *	   in a "free" state before we remove the unlinked inode list pointer.
1869  *
1870  * Hence the ordering needs to be inode allocation buffers first, inode items
1871  * second, inode unlink buffers third and cancelled buffers last.
1872  *
1873  * But there's a problem with that - we can't tell an inode allocation buffer
1874  * apart from a regular buffer, so we can't separate them. We can, however,
1875  * tell an inode unlink buffer from the others, and so we can separate them out
1876  * from all the other buffers and move them to last.
1877  *
1878  * Hence, 4 lists, in order from head to tail:
1879  *	- buffer_list for all buffers except cancelled/inode unlink buffers
1880  *	- item_list for all non-buffer items
1881  *	- inode_buffer_list for inode unlink buffers
1882  *	- cancel_list for the cancelled buffers
1883  *
1884  * Note that we add objects to the tail of the lists so that first-to-last
1885  * ordering is preserved within the lists. Adding objects to the head of the
1886  * list means when we traverse from the head we walk them in last-to-first
1887  * order. For cancelled buffers and inode unlink buffers this doesn't matter,
1888  * but for all other items there may be specific ordering that we need to
1889  * preserve.
1890  */
1891 STATIC int
xlog_recover_reorder_trans(struct xlog * log,struct xlog_recover * trans,int pass)1892 xlog_recover_reorder_trans(
1893 	struct xlog		*log,
1894 	struct xlog_recover	*trans,
1895 	int			pass)
1896 {
1897 	struct xlog_recover_item *item, *n;
1898 	int			error = 0;
1899 	LIST_HEAD(sort_list);
1900 	LIST_HEAD(cancel_list);
1901 	LIST_HEAD(buffer_list);
1902 	LIST_HEAD(inode_buffer_list);
1903 	LIST_HEAD(item_list);
1904 
1905 	list_splice_init(&trans->r_itemq, &sort_list);
1906 	list_for_each_entry_safe(item, n, &sort_list, ri_list) {
1907 		enum xlog_recover_reorder	fate = XLOG_REORDER_ITEM_LIST;
1908 
1909 		item->ri_ops = xlog_find_item_ops(item);
1910 		if (!item->ri_ops) {
1911 			xfs_warn(log->l_mp,
1912 				"%s: unrecognized type of log operation (%d)",
1913 				__func__, ITEM_TYPE(item));
1914 			ASSERT(0);
1915 			/*
1916 			 * return the remaining items back to the transaction
1917 			 * item list so they can be freed in caller.
1918 			 */
1919 			if (!list_empty(&sort_list))
1920 				list_splice_init(&sort_list, &trans->r_itemq);
1921 			error = -EFSCORRUPTED;
1922 			break;
1923 		}
1924 
1925 		if (item->ri_ops->reorder)
1926 			fate = item->ri_ops->reorder(item);
1927 
1928 		switch (fate) {
1929 		case XLOG_REORDER_BUFFER_LIST:
1930 			list_move_tail(&item->ri_list, &buffer_list);
1931 			break;
1932 		case XLOG_REORDER_CANCEL_LIST:
1933 			trace_xfs_log_recover_item_reorder_head(log,
1934 					trans, item, pass);
1935 			list_move(&item->ri_list, &cancel_list);
1936 			break;
1937 		case XLOG_REORDER_INODE_BUFFER_LIST:
1938 			list_move(&item->ri_list, &inode_buffer_list);
1939 			break;
1940 		case XLOG_REORDER_ITEM_LIST:
1941 			trace_xfs_log_recover_item_reorder_tail(log,
1942 							trans, item, pass);
1943 			list_move_tail(&item->ri_list, &item_list);
1944 			break;
1945 		}
1946 	}
1947 
1948 	ASSERT(list_empty(&sort_list));
1949 	if (!list_empty(&buffer_list))
1950 		list_splice(&buffer_list, &trans->r_itemq);
1951 	if (!list_empty(&item_list))
1952 		list_splice_tail(&item_list, &trans->r_itemq);
1953 	if (!list_empty(&inode_buffer_list))
1954 		list_splice_tail(&inode_buffer_list, &trans->r_itemq);
1955 	if (!list_empty(&cancel_list))
1956 		list_splice_tail(&cancel_list, &trans->r_itemq);
1957 	return error;
1958 }
1959 
1960 void
xlog_buf_readahead(struct xlog * log,xfs_daddr_t blkno,uint len,const struct xfs_buf_ops * ops)1961 xlog_buf_readahead(
1962 	struct xlog		*log,
1963 	xfs_daddr_t		blkno,
1964 	uint			len,
1965 	const struct xfs_buf_ops *ops)
1966 {
1967 	if (!xlog_is_buffer_cancelled(log, blkno, len))
1968 		xfs_buf_readahead(log->l_mp->m_ddev_targp, blkno, len, ops);
1969 }
1970 
1971 /*
1972  * Create a deferred work structure for resuming and tracking the progress of a
1973  * log intent item that was found during recovery.
1974  */
1975 void
xlog_recover_intent_item(struct xlog * log,struct xfs_log_item * lip,xfs_lsn_t lsn,const struct xfs_defer_op_type * ops)1976 xlog_recover_intent_item(
1977 	struct xlog			*log,
1978 	struct xfs_log_item		*lip,
1979 	xfs_lsn_t			lsn,
1980 	const struct xfs_defer_op_type	*ops)
1981 {
1982 	ASSERT(xlog_item_is_intent(lip));
1983 
1984 	xfs_defer_start_recovery(lip, &log->r_dfops, ops);
1985 
1986 	/*
1987 	 * Insert the intent into the AIL directly and drop one reference so
1988 	 * that finishing or canceling the work will drop the other.
1989 	 */
1990 	xfs_trans_ail_insert(log->l_ailp, lip, lsn);
1991 	lip->li_ops->iop_unpin(lip, 0);
1992 }
1993 
1994 STATIC int
xlog_recover_items_pass2(struct xlog * log,struct xlog_recover * trans,struct list_head * buffer_list,struct list_head * item_list)1995 xlog_recover_items_pass2(
1996 	struct xlog                     *log,
1997 	struct xlog_recover             *trans,
1998 	struct list_head                *buffer_list,
1999 	struct list_head                *item_list)
2000 {
2001 	struct xlog_recover_item	*item;
2002 	int				error = 0;
2003 
2004 	list_for_each_entry(item, item_list, ri_list) {
2005 		trace_xfs_log_recover_item_recover(log, trans, item,
2006 				XLOG_RECOVER_PASS2);
2007 
2008 		if (item->ri_ops->commit_pass2)
2009 			error = item->ri_ops->commit_pass2(log, buffer_list,
2010 					item, trans->r_lsn);
2011 		if (error)
2012 			return error;
2013 	}
2014 
2015 	return error;
2016 }
2017 
2018 /*
2019  * Perform the transaction.
2020  *
2021  * If the transaction modifies a buffer or inode, do it now.  Otherwise,
2022  * EFIs and EFDs get queued up by adding entries into the AIL for them.
2023  */
2024 STATIC int
xlog_recover_commit_trans(struct xlog * log,struct xlog_recover * trans,int pass,struct list_head * buffer_list)2025 xlog_recover_commit_trans(
2026 	struct xlog		*log,
2027 	struct xlog_recover	*trans,
2028 	int			pass,
2029 	struct list_head	*buffer_list)
2030 {
2031 	int				error = 0;
2032 	int				items_queued = 0;
2033 	struct xlog_recover_item	*item;
2034 	struct xlog_recover_item	*next;
2035 	LIST_HEAD			(ra_list);
2036 	LIST_HEAD			(done_list);
2037 
2038 	#define XLOG_RECOVER_COMMIT_QUEUE_MAX 100
2039 
2040 	hlist_del_init(&trans->r_list);
2041 
2042 	error = xlog_recover_reorder_trans(log, trans, pass);
2043 	if (error)
2044 		return error;
2045 
2046 	list_for_each_entry_safe(item, next, &trans->r_itemq, ri_list) {
2047 		trace_xfs_log_recover_item_recover(log, trans, item, pass);
2048 
2049 		switch (pass) {
2050 		case XLOG_RECOVER_PASS1:
2051 			if (item->ri_ops->commit_pass1)
2052 				error = item->ri_ops->commit_pass1(log, item);
2053 			break;
2054 		case XLOG_RECOVER_PASS2:
2055 			if (item->ri_ops->ra_pass2)
2056 				item->ri_ops->ra_pass2(log, item);
2057 			list_move_tail(&item->ri_list, &ra_list);
2058 			items_queued++;
2059 			if (items_queued >= XLOG_RECOVER_COMMIT_QUEUE_MAX) {
2060 				error = xlog_recover_items_pass2(log, trans,
2061 						buffer_list, &ra_list);
2062 				list_splice_tail_init(&ra_list, &done_list);
2063 				items_queued = 0;
2064 			}
2065 
2066 			break;
2067 		default:
2068 			ASSERT(0);
2069 		}
2070 
2071 		if (error)
2072 			goto out;
2073 	}
2074 
2075 out:
2076 	if (!list_empty(&ra_list)) {
2077 		if (!error)
2078 			error = xlog_recover_items_pass2(log, trans,
2079 					buffer_list, &ra_list);
2080 		list_splice_tail_init(&ra_list, &done_list);
2081 	}
2082 
2083 	if (!list_empty(&done_list))
2084 		list_splice_init(&done_list, &trans->r_itemq);
2085 
2086 	return error;
2087 }
2088 
2089 STATIC void
xlog_recover_add_item(struct list_head * head)2090 xlog_recover_add_item(
2091 	struct list_head	*head)
2092 {
2093 	struct xlog_recover_item *item;
2094 
2095 	item = kzalloc(sizeof(struct xlog_recover_item),
2096 			GFP_KERNEL | __GFP_NOFAIL);
2097 	INIT_LIST_HEAD(&item->ri_list);
2098 	list_add_tail(&item->ri_list, head);
2099 }
2100 
2101 STATIC int
xlog_recover_add_to_cont_trans(struct xlog * log,struct xlog_recover * trans,char * dp,int len)2102 xlog_recover_add_to_cont_trans(
2103 	struct xlog		*log,
2104 	struct xlog_recover	*trans,
2105 	char			*dp,
2106 	int			len)
2107 {
2108 	struct xlog_recover_item *item;
2109 	char			*ptr, *old_ptr;
2110 	int			old_len;
2111 
2112 	/*
2113 	 * If the transaction is empty, the header was split across this and the
2114 	 * previous record. Copy the rest of the header.
2115 	 */
2116 	if (list_empty(&trans->r_itemq)) {
2117 		ASSERT(len <= sizeof(struct xfs_trans_header));
2118 		if (len > sizeof(struct xfs_trans_header)) {
2119 			xfs_warn(log->l_mp, "%s: bad header length", __func__);
2120 			return -EFSCORRUPTED;
2121 		}
2122 
2123 		xlog_recover_add_item(&trans->r_itemq);
2124 		ptr = (char *)&trans->r_theader +
2125 				sizeof(struct xfs_trans_header) - len;
2126 		memcpy(ptr, dp, len);
2127 		return 0;
2128 	}
2129 
2130 	/* take the tail entry */
2131 	item = list_entry(trans->r_itemq.prev, struct xlog_recover_item,
2132 			  ri_list);
2133 
2134 	old_ptr = item->ri_buf[item->ri_cnt-1].i_addr;
2135 	old_len = item->ri_buf[item->ri_cnt-1].i_len;
2136 
2137 	ptr = kvrealloc(old_ptr, len + old_len, GFP_KERNEL);
2138 	if (!ptr)
2139 		return -ENOMEM;
2140 	memcpy(&ptr[old_len], dp, len);
2141 	item->ri_buf[item->ri_cnt-1].i_len += len;
2142 	item->ri_buf[item->ri_cnt-1].i_addr = ptr;
2143 	trace_xfs_log_recover_item_add_cont(log, trans, item, 0);
2144 	return 0;
2145 }
2146 
2147 /*
2148  * The next region to add is the start of a new region.  It could be
2149  * a whole region or it could be the first part of a new region.  Because
2150  * of this, the assumption here is that the type and size fields of all
2151  * format structures fit into the first 32 bits of the structure.
2152  *
2153  * This works because all regions must be 32 bit aligned.  Therefore, we
2154  * either have both fields or we have neither field.  In the case we have
2155  * neither field, the data part of the region is zero length.  We only have
2156  * a log_op_header and can throw away the header since a new one will appear
2157  * later.  If we have at least 4 bytes, then we can determine how many regions
2158  * will appear in the current log item.
2159  */
2160 STATIC int
xlog_recover_add_to_trans(struct xlog * log,struct xlog_recover * trans,char * dp,int len)2161 xlog_recover_add_to_trans(
2162 	struct xlog		*log,
2163 	struct xlog_recover	*trans,
2164 	char			*dp,
2165 	int			len)
2166 {
2167 	struct xfs_inode_log_format	*in_f;			/* any will do */
2168 	struct xlog_recover_item *item;
2169 	char			*ptr;
2170 
2171 	if (!len)
2172 		return 0;
2173 	if (list_empty(&trans->r_itemq)) {
2174 		/* we need to catch log corruptions here */
2175 		if (*(uint *)dp != XFS_TRANS_HEADER_MAGIC) {
2176 			xfs_warn(log->l_mp, "%s: bad header magic number",
2177 				__func__);
2178 			ASSERT(0);
2179 			return -EFSCORRUPTED;
2180 		}
2181 
2182 		if (len > sizeof(struct xfs_trans_header)) {
2183 			xfs_warn(log->l_mp, "%s: bad header length", __func__);
2184 			ASSERT(0);
2185 			return -EFSCORRUPTED;
2186 		}
2187 
2188 		/*
2189 		 * The transaction header can be arbitrarily split across op
2190 		 * records. If we don't have the whole thing here, copy what we
2191 		 * do have and handle the rest in the next record.
2192 		 */
2193 		if (len == sizeof(struct xfs_trans_header))
2194 			xlog_recover_add_item(&trans->r_itemq);
2195 		memcpy(&trans->r_theader, dp, len);
2196 		return 0;
2197 	}
2198 
2199 	ptr = xlog_kvmalloc(len);
2200 	memcpy(ptr, dp, len);
2201 	in_f = (struct xfs_inode_log_format *)ptr;
2202 
2203 	/* take the tail entry */
2204 	item = list_entry(trans->r_itemq.prev, struct xlog_recover_item,
2205 			  ri_list);
2206 	if (item->ri_total != 0 &&
2207 	     item->ri_total == item->ri_cnt) {
2208 		/* tail item is in use, get a new one */
2209 		xlog_recover_add_item(&trans->r_itemq);
2210 		item = list_entry(trans->r_itemq.prev,
2211 					struct xlog_recover_item, ri_list);
2212 	}
2213 
2214 	if (item->ri_total == 0) {		/* first region to be added */
2215 		if (in_f->ilf_size == 0 ||
2216 		    in_f->ilf_size > XLOG_MAX_REGIONS_IN_ITEM) {
2217 			xfs_warn(log->l_mp,
2218 		"bad number of regions (%d) in inode log format",
2219 				  in_f->ilf_size);
2220 			ASSERT(0);
2221 			kvfree(ptr);
2222 			return -EFSCORRUPTED;
2223 		}
2224 
2225 		item->ri_total = in_f->ilf_size;
2226 		item->ri_buf = kzalloc(item->ri_total * sizeof(xfs_log_iovec_t),
2227 				GFP_KERNEL | __GFP_NOFAIL);
2228 	}
2229 
2230 	if (item->ri_total <= item->ri_cnt) {
2231 		xfs_warn(log->l_mp,
2232 	"log item region count (%d) overflowed size (%d)",
2233 				item->ri_cnt, item->ri_total);
2234 		ASSERT(0);
2235 		kvfree(ptr);
2236 		return -EFSCORRUPTED;
2237 	}
2238 
2239 	/* Description region is ri_buf[0] */
2240 	item->ri_buf[item->ri_cnt].i_addr = ptr;
2241 	item->ri_buf[item->ri_cnt].i_len  = len;
2242 	item->ri_cnt++;
2243 	trace_xfs_log_recover_item_add(log, trans, item, 0);
2244 	return 0;
2245 }
2246 
2247 /*
2248  * Free up any resources allocated by the transaction
2249  *
2250  * Remember that EFIs, EFDs, and IUNLINKs are handled later.
2251  */
2252 STATIC void
xlog_recover_free_trans(struct xlog_recover * trans)2253 xlog_recover_free_trans(
2254 	struct xlog_recover	*trans)
2255 {
2256 	struct xlog_recover_item *item, *n;
2257 	int			i;
2258 
2259 	hlist_del_init(&trans->r_list);
2260 
2261 	list_for_each_entry_safe(item, n, &trans->r_itemq, ri_list) {
2262 		/* Free the regions in the item. */
2263 		list_del(&item->ri_list);
2264 		for (i = 0; i < item->ri_cnt; i++)
2265 			kvfree(item->ri_buf[i].i_addr);
2266 		/* Free the item itself */
2267 		kfree(item->ri_buf);
2268 		kfree(item);
2269 	}
2270 	/* Free the transaction recover structure */
2271 	kfree(trans);
2272 }
2273 
2274 /*
2275  * On error or completion, trans is freed.
2276  */
2277 STATIC int
xlog_recovery_process_trans(struct xlog * log,struct xlog_recover * trans,char * dp,unsigned int len,unsigned int flags,int pass,struct list_head * buffer_list)2278 xlog_recovery_process_trans(
2279 	struct xlog		*log,
2280 	struct xlog_recover	*trans,
2281 	char			*dp,
2282 	unsigned int		len,
2283 	unsigned int		flags,
2284 	int			pass,
2285 	struct list_head	*buffer_list)
2286 {
2287 	int			error = 0;
2288 	bool			freeit = false;
2289 
2290 	/* mask off ophdr transaction container flags */
2291 	flags &= ~XLOG_END_TRANS;
2292 	if (flags & XLOG_WAS_CONT_TRANS)
2293 		flags &= ~XLOG_CONTINUE_TRANS;
2294 
2295 	/*
2296 	 * Callees must not free the trans structure. We'll decide if we need to
2297 	 * free it or not based on the operation being done and it's result.
2298 	 */
2299 	switch (flags) {
2300 	/* expected flag values */
2301 	case 0:
2302 	case XLOG_CONTINUE_TRANS:
2303 		error = xlog_recover_add_to_trans(log, trans, dp, len);
2304 		break;
2305 	case XLOG_WAS_CONT_TRANS:
2306 		error = xlog_recover_add_to_cont_trans(log, trans, dp, len);
2307 		break;
2308 	case XLOG_COMMIT_TRANS:
2309 		error = xlog_recover_commit_trans(log, trans, pass,
2310 						  buffer_list);
2311 		/* success or fail, we are now done with this transaction. */
2312 		freeit = true;
2313 		break;
2314 
2315 	/* unexpected flag values */
2316 	case XLOG_UNMOUNT_TRANS:
2317 		/* just skip trans */
2318 		xfs_warn(log->l_mp, "%s: Unmount LR", __func__);
2319 		freeit = true;
2320 		break;
2321 	case XLOG_START_TRANS:
2322 	default:
2323 		xfs_warn(log->l_mp, "%s: bad flag 0x%x", __func__, flags);
2324 		ASSERT(0);
2325 		error = -EFSCORRUPTED;
2326 		break;
2327 	}
2328 	if (error || freeit)
2329 		xlog_recover_free_trans(trans);
2330 	return error;
2331 }
2332 
2333 /*
2334  * Lookup the transaction recovery structure associated with the ID in the
2335  * current ophdr. If the transaction doesn't exist and the start flag is set in
2336  * the ophdr, then allocate a new transaction for future ID matches to find.
2337  * Either way, return what we found during the lookup - an existing transaction
2338  * or nothing.
2339  */
2340 STATIC struct xlog_recover *
xlog_recover_ophdr_to_trans(struct hlist_head rhash[],struct xlog_rec_header * rhead,struct xlog_op_header * ohead)2341 xlog_recover_ophdr_to_trans(
2342 	struct hlist_head	rhash[],
2343 	struct xlog_rec_header	*rhead,
2344 	struct xlog_op_header	*ohead)
2345 {
2346 	struct xlog_recover	*trans;
2347 	xlog_tid_t		tid;
2348 	struct hlist_head	*rhp;
2349 
2350 	tid = be32_to_cpu(ohead->oh_tid);
2351 	rhp = &rhash[XLOG_RHASH(tid)];
2352 	hlist_for_each_entry(trans, rhp, r_list) {
2353 		if (trans->r_log_tid == tid)
2354 			return trans;
2355 	}
2356 
2357 	/*
2358 	 * skip over non-start transaction headers - we could be
2359 	 * processing slack space before the next transaction starts
2360 	 */
2361 	if (!(ohead->oh_flags & XLOG_START_TRANS))
2362 		return NULL;
2363 
2364 	ASSERT(be32_to_cpu(ohead->oh_len) == 0);
2365 
2366 	/*
2367 	 * This is a new transaction so allocate a new recovery container to
2368 	 * hold the recovery ops that will follow.
2369 	 */
2370 	trans = kzalloc(sizeof(struct xlog_recover), GFP_KERNEL | __GFP_NOFAIL);
2371 	trans->r_log_tid = tid;
2372 	trans->r_lsn = be64_to_cpu(rhead->h_lsn);
2373 	INIT_LIST_HEAD(&trans->r_itemq);
2374 	INIT_HLIST_NODE(&trans->r_list);
2375 	hlist_add_head(&trans->r_list, rhp);
2376 
2377 	/*
2378 	 * Nothing more to do for this ophdr. Items to be added to this new
2379 	 * transaction will be in subsequent ophdr containers.
2380 	 */
2381 	return NULL;
2382 }
2383 
2384 STATIC int
xlog_recover_process_ophdr(struct xlog * log,struct hlist_head rhash[],struct xlog_rec_header * rhead,struct xlog_op_header * ohead,char * dp,char * end,int pass,struct list_head * buffer_list)2385 xlog_recover_process_ophdr(
2386 	struct xlog		*log,
2387 	struct hlist_head	rhash[],
2388 	struct xlog_rec_header	*rhead,
2389 	struct xlog_op_header	*ohead,
2390 	char			*dp,
2391 	char			*end,
2392 	int			pass,
2393 	struct list_head	*buffer_list)
2394 {
2395 	struct xlog_recover	*trans;
2396 	unsigned int		len;
2397 	int			error;
2398 
2399 	/* Do we understand who wrote this op? */
2400 	if (ohead->oh_clientid != XFS_TRANSACTION &&
2401 	    ohead->oh_clientid != XFS_LOG) {
2402 		xfs_warn(log->l_mp, "%s: bad clientid 0x%x",
2403 			__func__, ohead->oh_clientid);
2404 		ASSERT(0);
2405 		return -EFSCORRUPTED;
2406 	}
2407 
2408 	/*
2409 	 * Check the ophdr contains all the data it is supposed to contain.
2410 	 */
2411 	len = be32_to_cpu(ohead->oh_len);
2412 	if (dp + len > end) {
2413 		xfs_warn(log->l_mp, "%s: bad length 0x%x", __func__, len);
2414 		WARN_ON(1);
2415 		return -EFSCORRUPTED;
2416 	}
2417 
2418 	trans = xlog_recover_ophdr_to_trans(rhash, rhead, ohead);
2419 	if (!trans) {
2420 		/* nothing to do, so skip over this ophdr */
2421 		return 0;
2422 	}
2423 
2424 	/*
2425 	 * The recovered buffer queue is drained only once we know that all
2426 	 * recovery items for the current LSN have been processed. This is
2427 	 * required because:
2428 	 *
2429 	 * - Buffer write submission updates the metadata LSN of the buffer.
2430 	 * - Log recovery skips items with a metadata LSN >= the current LSN of
2431 	 *   the recovery item.
2432 	 * - Separate recovery items against the same metadata buffer can share
2433 	 *   a current LSN. I.e., consider that the LSN of a recovery item is
2434 	 *   defined as the starting LSN of the first record in which its
2435 	 *   transaction appears, that a record can hold multiple transactions,
2436 	 *   and/or that a transaction can span multiple records.
2437 	 *
2438 	 * In other words, we are allowed to submit a buffer from log recovery
2439 	 * once per current LSN. Otherwise, we may incorrectly skip recovery
2440 	 * items and cause corruption.
2441 	 *
2442 	 * We don't know up front whether buffers are updated multiple times per
2443 	 * LSN. Therefore, track the current LSN of each commit log record as it
2444 	 * is processed and drain the queue when it changes. Use commit records
2445 	 * because they are ordered correctly by the logging code.
2446 	 */
2447 	if (log->l_recovery_lsn != trans->r_lsn &&
2448 	    ohead->oh_flags & XLOG_COMMIT_TRANS) {
2449 		error = xfs_buf_delwri_submit(buffer_list);
2450 		if (error)
2451 			return error;
2452 		log->l_recovery_lsn = trans->r_lsn;
2453 	}
2454 
2455 	return xlog_recovery_process_trans(log, trans, dp, len,
2456 					   ohead->oh_flags, pass, buffer_list);
2457 }
2458 
2459 /*
2460  * There are two valid states of the r_state field.  0 indicates that the
2461  * transaction structure is in a normal state.  We have either seen the
2462  * start of the transaction or the last operation we added was not a partial
2463  * operation.  If the last operation we added to the transaction was a
2464  * partial operation, we need to mark r_state with XLOG_WAS_CONT_TRANS.
2465  *
2466  * NOTE: skip LRs with 0 data length.
2467  */
2468 STATIC int
xlog_recover_process_data(struct xlog * log,struct hlist_head rhash[],struct xlog_rec_header * rhead,char * dp,int pass,struct list_head * buffer_list)2469 xlog_recover_process_data(
2470 	struct xlog		*log,
2471 	struct hlist_head	rhash[],
2472 	struct xlog_rec_header	*rhead,
2473 	char			*dp,
2474 	int			pass,
2475 	struct list_head	*buffer_list)
2476 {
2477 	struct xlog_op_header	*ohead;
2478 	char			*end;
2479 	int			num_logops;
2480 	int			error;
2481 
2482 	end = dp + be32_to_cpu(rhead->h_len);
2483 	num_logops = be32_to_cpu(rhead->h_num_logops);
2484 
2485 	/* check the log format matches our own - else we can't recover */
2486 	if (xlog_header_check_recover(log->l_mp, rhead))
2487 		return -EIO;
2488 
2489 	trace_xfs_log_recover_record(log, rhead, pass);
2490 	while ((dp < end) && num_logops) {
2491 
2492 		ohead = (struct xlog_op_header *)dp;
2493 		dp += sizeof(*ohead);
2494 		if (dp > end) {
2495 			xfs_warn(log->l_mp, "%s: op header overrun", __func__);
2496 			return -EFSCORRUPTED;
2497 		}
2498 
2499 		/* errors will abort recovery */
2500 		error = xlog_recover_process_ophdr(log, rhash, rhead, ohead,
2501 						   dp, end, pass, buffer_list);
2502 		if (error)
2503 			return error;
2504 
2505 		dp += be32_to_cpu(ohead->oh_len);
2506 		num_logops--;
2507 	}
2508 	return 0;
2509 }
2510 
2511 /* Take all the collected deferred ops and finish them in order. */
2512 static int
xlog_finish_defer_ops(struct xfs_mount * mp,struct list_head * capture_list)2513 xlog_finish_defer_ops(
2514 	struct xfs_mount	*mp,
2515 	struct list_head	*capture_list)
2516 {
2517 	struct xfs_defer_capture *dfc, *next;
2518 	struct xfs_trans	*tp;
2519 	int			error = 0;
2520 
2521 	list_for_each_entry_safe(dfc, next, capture_list, dfc_list) {
2522 		struct xfs_trans_res	resv;
2523 		struct xfs_defer_resources dres;
2524 
2525 		/*
2526 		 * Create a new transaction reservation from the captured
2527 		 * information.  Set logcount to 1 to force the new transaction
2528 		 * to regrant every roll so that we can make forward progress
2529 		 * in recovery no matter how full the log might be.
2530 		 */
2531 		resv.tr_logres = dfc->dfc_logres;
2532 		resv.tr_logcount = 1;
2533 		resv.tr_logflags = XFS_TRANS_PERM_LOG_RES;
2534 
2535 		error = xfs_trans_alloc(mp, &resv, dfc->dfc_blkres,
2536 				dfc->dfc_rtxres, XFS_TRANS_RESERVE, &tp);
2537 		if (error) {
2538 			xlog_force_shutdown(mp->m_log, SHUTDOWN_LOG_IO_ERROR);
2539 			return error;
2540 		}
2541 
2542 		/*
2543 		 * Transfer to this new transaction all the dfops we captured
2544 		 * from recovering a single intent item.
2545 		 */
2546 		list_del_init(&dfc->dfc_list);
2547 		xfs_defer_ops_continue(dfc, tp, &dres);
2548 		error = xfs_trans_commit(tp);
2549 		xfs_defer_resources_rele(&dres);
2550 		if (error)
2551 			return error;
2552 	}
2553 
2554 	ASSERT(list_empty(capture_list));
2555 	return 0;
2556 }
2557 
2558 /* Release all the captured defer ops and capture structures in this list. */
2559 static void
xlog_abort_defer_ops(struct xfs_mount * mp,struct list_head * capture_list)2560 xlog_abort_defer_ops(
2561 	struct xfs_mount		*mp,
2562 	struct list_head		*capture_list)
2563 {
2564 	struct xfs_defer_capture	*dfc;
2565 	struct xfs_defer_capture	*next;
2566 
2567 	list_for_each_entry_safe(dfc, next, capture_list, dfc_list) {
2568 		list_del_init(&dfc->dfc_list);
2569 		xfs_defer_ops_capture_abort(mp, dfc);
2570 	}
2571 }
2572 
2573 /*
2574  * When this is called, all of the log intent items which did not have
2575  * corresponding log done items should be in the AIL.  What we do now is update
2576  * the data structures associated with each one.
2577  *
2578  * Since we process the log intent items in normal transactions, they will be
2579  * removed at some point after the commit.  This prevents us from just walking
2580  * down the list processing each one.  We'll use a flag in the intent item to
2581  * skip those that we've already processed and use the AIL iteration mechanism's
2582  * generation count to try to speed this up at least a bit.
2583  *
2584  * When we start, we know that the intents are the only things in the AIL. As we
2585  * process them, however, other items are added to the AIL. Hence we know we
2586  * have started recovery on all the pending intents when we find an non-intent
2587  * item in the AIL.
2588  */
2589 STATIC int
xlog_recover_process_intents(struct xlog * log)2590 xlog_recover_process_intents(
2591 	struct xlog			*log)
2592 {
2593 	LIST_HEAD(capture_list);
2594 	struct xfs_defer_pending	*dfp, *n;
2595 	int				error = 0;
2596 #if defined(DEBUG) || defined(XFS_WARN)
2597 	xfs_lsn_t			last_lsn;
2598 
2599 	last_lsn = xlog_assign_lsn(log->l_curr_cycle, log->l_curr_block);
2600 #endif
2601 
2602 	list_for_each_entry_safe(dfp, n, &log->r_dfops, dfp_list) {
2603 		ASSERT(xlog_item_is_intent(dfp->dfp_intent));
2604 
2605 		/*
2606 		 * We should never see a redo item with a LSN higher than
2607 		 * the last transaction we found in the log at the start
2608 		 * of recovery.
2609 		 */
2610 		ASSERT(XFS_LSN_CMP(last_lsn, dfp->dfp_intent->li_lsn) >= 0);
2611 
2612 		/*
2613 		 * NOTE: If your intent processing routine can create more
2614 		 * deferred ops, you /must/ attach them to the capture list in
2615 		 * the recover routine or else those subsequent intents will be
2616 		 * replayed in the wrong order!
2617 		 *
2618 		 * The recovery function can free the log item, so we must not
2619 		 * access dfp->dfp_intent after it returns.  It must dispose of
2620 		 * @dfp if it returns 0.
2621 		 */
2622 		error = xfs_defer_finish_recovery(log->l_mp, dfp,
2623 				&capture_list);
2624 		if (error)
2625 			break;
2626 	}
2627 	if (error)
2628 		goto err;
2629 
2630 	error = xlog_finish_defer_ops(log->l_mp, &capture_list);
2631 	if (error)
2632 		goto err;
2633 
2634 	return 0;
2635 err:
2636 	xlog_abort_defer_ops(log->l_mp, &capture_list);
2637 	return error;
2638 }
2639 
2640 /*
2641  * A cancel occurs when the mount has failed and we're bailing out.  Release all
2642  * pending log intent items that we haven't started recovery on so they don't
2643  * pin the AIL.
2644  */
2645 STATIC void
xlog_recover_cancel_intents(struct xlog * log)2646 xlog_recover_cancel_intents(
2647 	struct xlog			*log)
2648 {
2649 	struct xfs_defer_pending	*dfp, *n;
2650 
2651 	list_for_each_entry_safe(dfp, n, &log->r_dfops, dfp_list) {
2652 		ASSERT(xlog_item_is_intent(dfp->dfp_intent));
2653 
2654 		xfs_defer_cancel_recovery(log->l_mp, dfp);
2655 	}
2656 }
2657 
2658 /*
2659  * Transfer ownership of the recovered pending work to the recovery transaction
2660  * and try to finish the work.  If there is more work to be done, the dfp will
2661  * remain attached to the transaction.  If not, the dfp is freed.
2662  */
2663 int
xlog_recover_finish_intent(struct xfs_trans * tp,struct xfs_defer_pending * dfp)2664 xlog_recover_finish_intent(
2665 	struct xfs_trans		*tp,
2666 	struct xfs_defer_pending	*dfp)
2667 {
2668 	int				error;
2669 
2670 	list_move(&dfp->dfp_list, &tp->t_dfops);
2671 	error = xfs_defer_finish_one(tp, dfp);
2672 	if (error == -EAGAIN)
2673 		return 0;
2674 	return error;
2675 }
2676 
2677 /*
2678  * This routine performs a transaction to null out a bad inode pointer
2679  * in an agi unlinked inode hash bucket.
2680  */
2681 STATIC void
xlog_recover_clear_agi_bucket(struct xfs_perag * pag,int bucket)2682 xlog_recover_clear_agi_bucket(
2683 	struct xfs_perag	*pag,
2684 	int			bucket)
2685 {
2686 	struct xfs_mount	*mp = pag_mount(pag);
2687 	struct xfs_trans	*tp;
2688 	struct xfs_agi		*agi;
2689 	struct xfs_buf		*agibp;
2690 	int			offset;
2691 	int			error;
2692 
2693 	error = xfs_trans_alloc(mp, &M_RES(mp)->tr_clearagi, 0, 0, 0, &tp);
2694 	if (error)
2695 		goto out_error;
2696 
2697 	error = xfs_read_agi(pag, tp, 0, &agibp);
2698 	if (error)
2699 		goto out_abort;
2700 
2701 	agi = agibp->b_addr;
2702 	agi->agi_unlinked[bucket] = cpu_to_be32(NULLAGINO);
2703 	offset = offsetof(xfs_agi_t, agi_unlinked) +
2704 		 (sizeof(xfs_agino_t) * bucket);
2705 	xfs_trans_log_buf(tp, agibp, offset,
2706 			  (offset + sizeof(xfs_agino_t) - 1));
2707 
2708 	error = xfs_trans_commit(tp);
2709 	if (error)
2710 		goto out_error;
2711 	return;
2712 
2713 out_abort:
2714 	xfs_trans_cancel(tp);
2715 out_error:
2716 	xfs_warn(mp, "%s: failed to clear agi %d. Continuing.", __func__,
2717 			pag_agno(pag));
2718 	return;
2719 }
2720 
2721 static int
xlog_recover_iunlink_bucket(struct xfs_perag * pag,struct xfs_agi * agi,int bucket)2722 xlog_recover_iunlink_bucket(
2723 	struct xfs_perag	*pag,
2724 	struct xfs_agi		*agi,
2725 	int			bucket)
2726 {
2727 	struct xfs_mount	*mp = pag_mount(pag);
2728 	struct xfs_inode	*prev_ip = NULL;
2729 	struct xfs_inode	*ip;
2730 	xfs_agino_t		prev_agino, agino;
2731 	int			error = 0;
2732 
2733 	agino = be32_to_cpu(agi->agi_unlinked[bucket]);
2734 	while (agino != NULLAGINO) {
2735 		error = xfs_iget(mp, NULL, xfs_agino_to_ino(pag, agino), 0, 0,
2736 				&ip);
2737 		if (error)
2738 			break;
2739 
2740 		ASSERT(VFS_I(ip)->i_nlink == 0);
2741 		ASSERT(VFS_I(ip)->i_mode != 0);
2742 		xfs_iflags_clear(ip, XFS_IRECOVERY);
2743 		agino = ip->i_next_unlinked;
2744 
2745 		if (prev_ip) {
2746 			ip->i_prev_unlinked = prev_agino;
2747 			xfs_irele(prev_ip);
2748 
2749 			/*
2750 			 * Ensure the inode is removed from the unlinked list
2751 			 * before we continue so that it won't race with
2752 			 * building the in-memory list here. This could be
2753 			 * serialised with the agibp lock, but that just
2754 			 * serialises via lockstepping and it's much simpler
2755 			 * just to flush the inodegc queue and wait for it to
2756 			 * complete.
2757 			 */
2758 			error = xfs_inodegc_flush(mp);
2759 			if (error)
2760 				break;
2761 		}
2762 
2763 		prev_agino = agino;
2764 		prev_ip = ip;
2765 	}
2766 
2767 	if (prev_ip) {
2768 		int	error2;
2769 
2770 		ip->i_prev_unlinked = prev_agino;
2771 		xfs_irele(prev_ip);
2772 
2773 		error2 = xfs_inodegc_flush(mp);
2774 		if (error2 && !error)
2775 			return error2;
2776 	}
2777 	return error;
2778 }
2779 
2780 /*
2781  * Recover AGI unlinked lists
2782  *
2783  * This is called during recovery to process any inodes which we unlinked but
2784  * not freed when the system crashed.  These inodes will be on the lists in the
2785  * AGI blocks. What we do here is scan all the AGIs and fully truncate and free
2786  * any inodes found on the lists. Each inode is removed from the lists when it
2787  * has been fully truncated and is freed. The freeing of the inode and its
2788  * removal from the list must be atomic.
2789  *
2790  * If everything we touch in the agi processing loop is already in memory, this
2791  * loop can hold the cpu for a long time. It runs without lock contention,
2792  * memory allocation contention, the need wait for IO, etc, and so will run
2793  * until we either run out of inodes to process, run low on memory or we run out
2794  * of log space.
2795  *
2796  * This behaviour is bad for latency on single CPU and non-preemptible kernels,
2797  * and can prevent other filesystem work (such as CIL pushes) from running. This
2798  * can lead to deadlocks if the recovery process runs out of log reservation
2799  * space. Hence we need to yield the CPU when there is other kernel work
2800  * scheduled on this CPU to ensure other scheduled work can run without undue
2801  * latency.
2802  */
2803 static void
xlog_recover_iunlink_ag(struct xfs_perag * pag)2804 xlog_recover_iunlink_ag(
2805 	struct xfs_perag	*pag)
2806 {
2807 	struct xfs_agi		*agi;
2808 	struct xfs_buf		*agibp;
2809 	int			bucket;
2810 	int			error;
2811 
2812 	error = xfs_read_agi(pag, NULL, 0, &agibp);
2813 	if (error) {
2814 		/*
2815 		 * AGI is b0rked. Don't process it.
2816 		 *
2817 		 * We should probably mark the filesystem as corrupt after we've
2818 		 * recovered all the ag's we can....
2819 		 */
2820 		return;
2821 	}
2822 
2823 	/*
2824 	 * Unlock the buffer so that it can be acquired in the normal course of
2825 	 * the transaction to truncate and free each inode.  Because we are not
2826 	 * racing with anyone else here for the AGI buffer, we don't even need
2827 	 * to hold it locked to read the initial unlinked bucket entries out of
2828 	 * the buffer. We keep buffer reference though, so that it stays pinned
2829 	 * in memory while we need the buffer.
2830 	 */
2831 	agi = agibp->b_addr;
2832 	xfs_buf_unlock(agibp);
2833 
2834 	for (bucket = 0; bucket < XFS_AGI_UNLINKED_BUCKETS; bucket++) {
2835 		error = xlog_recover_iunlink_bucket(pag, agi, bucket);
2836 		if (error) {
2837 			/*
2838 			 * Bucket is unrecoverable, so only a repair scan can
2839 			 * free the remaining unlinked inodes. Just empty the
2840 			 * bucket and remaining inodes on it unreferenced and
2841 			 * unfreeable.
2842 			 */
2843 			xlog_recover_clear_agi_bucket(pag, bucket);
2844 		}
2845 	}
2846 
2847 	xfs_buf_rele(agibp);
2848 }
2849 
2850 static void
xlog_recover_process_iunlinks(struct xlog * log)2851 xlog_recover_process_iunlinks(
2852 	struct xlog	*log)
2853 {
2854 	struct xfs_perag	*pag = NULL;
2855 
2856 	while ((pag = xfs_perag_next(log->l_mp, pag)))
2857 		xlog_recover_iunlink_ag(pag);
2858 }
2859 
2860 STATIC void
xlog_unpack_data(struct xlog_rec_header * rhead,char * dp,struct xlog * log)2861 xlog_unpack_data(
2862 	struct xlog_rec_header	*rhead,
2863 	char			*dp,
2864 	struct xlog		*log)
2865 {
2866 	int			i, j, k;
2867 
2868 	for (i = 0; i < BTOBB(be32_to_cpu(rhead->h_len)) &&
2869 		  i < (XLOG_HEADER_CYCLE_SIZE / BBSIZE); i++) {
2870 		*(__be32 *)dp = *(__be32 *)&rhead->h_cycle_data[i];
2871 		dp += BBSIZE;
2872 	}
2873 
2874 	if (xfs_has_logv2(log->l_mp)) {
2875 		xlog_in_core_2_t *xhdr = (xlog_in_core_2_t *)rhead;
2876 		for ( ; i < BTOBB(be32_to_cpu(rhead->h_len)); i++) {
2877 			j = i / (XLOG_HEADER_CYCLE_SIZE / BBSIZE);
2878 			k = i % (XLOG_HEADER_CYCLE_SIZE / BBSIZE);
2879 			*(__be32 *)dp = xhdr[j].hic_xheader.xh_cycle_data[k];
2880 			dp += BBSIZE;
2881 		}
2882 	}
2883 }
2884 
2885 /*
2886  * CRC check, unpack and process a log record.
2887  */
2888 STATIC int
xlog_recover_process(struct xlog * log,struct hlist_head rhash[],struct xlog_rec_header * rhead,char * dp,int pass,struct list_head * buffer_list)2889 xlog_recover_process(
2890 	struct xlog		*log,
2891 	struct hlist_head	rhash[],
2892 	struct xlog_rec_header	*rhead,
2893 	char			*dp,
2894 	int			pass,
2895 	struct list_head	*buffer_list)
2896 {
2897 	__le32			old_crc = rhead->h_crc;
2898 	__le32			crc;
2899 
2900 	crc = xlog_cksum(log, rhead, dp, be32_to_cpu(rhead->h_len));
2901 
2902 	/*
2903 	 * Nothing else to do if this is a CRC verification pass. Just return
2904 	 * if this a record with a non-zero crc. Unfortunately, mkfs always
2905 	 * sets old_crc to 0 so we must consider this valid even on v5 supers.
2906 	 * Otherwise, return EFSBADCRC on failure so the callers up the stack
2907 	 * know precisely what failed.
2908 	 */
2909 	if (pass == XLOG_RECOVER_CRCPASS) {
2910 		if (old_crc && crc != old_crc)
2911 			return -EFSBADCRC;
2912 		return 0;
2913 	}
2914 
2915 	/*
2916 	 * We're in the normal recovery path. Issue a warning if and only if the
2917 	 * CRC in the header is non-zero. This is an advisory warning and the
2918 	 * zero CRC check prevents warnings from being emitted when upgrading
2919 	 * the kernel from one that does not add CRCs by default.
2920 	 */
2921 	if (crc != old_crc) {
2922 		if (old_crc || xfs_has_crc(log->l_mp)) {
2923 			xfs_alert(log->l_mp,
2924 		"log record CRC mismatch: found 0x%x, expected 0x%x.",
2925 					le32_to_cpu(old_crc),
2926 					le32_to_cpu(crc));
2927 			xfs_hex_dump(dp, 32);
2928 		}
2929 
2930 		/*
2931 		 * If the filesystem is CRC enabled, this mismatch becomes a
2932 		 * fatal log corruption failure.
2933 		 */
2934 		if (xfs_has_crc(log->l_mp)) {
2935 			XFS_ERROR_REPORT(__func__, XFS_ERRLEVEL_LOW, log->l_mp);
2936 			return -EFSCORRUPTED;
2937 		}
2938 	}
2939 
2940 	xlog_unpack_data(rhead, dp, log);
2941 
2942 	return xlog_recover_process_data(log, rhash, rhead, dp, pass,
2943 					 buffer_list);
2944 }
2945 
2946 STATIC int
xlog_valid_rec_header(struct xlog * log,struct xlog_rec_header * rhead,xfs_daddr_t blkno,int bufsize)2947 xlog_valid_rec_header(
2948 	struct xlog		*log,
2949 	struct xlog_rec_header	*rhead,
2950 	xfs_daddr_t		blkno,
2951 	int			bufsize)
2952 {
2953 	int			hlen;
2954 
2955 	if (XFS_IS_CORRUPT(log->l_mp,
2956 			   rhead->h_magicno != cpu_to_be32(XLOG_HEADER_MAGIC_NUM)))
2957 		return -EFSCORRUPTED;
2958 	if (XFS_IS_CORRUPT(log->l_mp,
2959 			   (!rhead->h_version ||
2960 			   (be32_to_cpu(rhead->h_version) &
2961 			    (~XLOG_VERSION_OKBITS))))) {
2962 		xfs_warn(log->l_mp, "%s: unrecognised log version (%d).",
2963 			__func__, be32_to_cpu(rhead->h_version));
2964 		return -EFSCORRUPTED;
2965 	}
2966 
2967 	/*
2968 	 * LR body must have data (or it wouldn't have been written)
2969 	 * and h_len must not be greater than LR buffer size.
2970 	 */
2971 	hlen = be32_to_cpu(rhead->h_len);
2972 	if (XFS_IS_CORRUPT(log->l_mp, hlen <= 0 || hlen > bufsize))
2973 		return -EFSCORRUPTED;
2974 
2975 	if (XFS_IS_CORRUPT(log->l_mp,
2976 			   blkno > log->l_logBBsize || blkno > INT_MAX))
2977 		return -EFSCORRUPTED;
2978 	return 0;
2979 }
2980 
2981 /*
2982  * Read the log from tail to head and process the log records found.
2983  * Handle the two cases where the tail and head are in the same cycle
2984  * and where the active portion of the log wraps around the end of
2985  * the physical log separately.  The pass parameter is passed through
2986  * to the routines called to process the data and is not looked at
2987  * here.
2988  */
2989 STATIC int
xlog_do_recovery_pass(struct xlog * log,xfs_daddr_t head_blk,xfs_daddr_t tail_blk,int pass,xfs_daddr_t * first_bad)2990 xlog_do_recovery_pass(
2991 	struct xlog		*log,
2992 	xfs_daddr_t		head_blk,
2993 	xfs_daddr_t		tail_blk,
2994 	int			pass,
2995 	xfs_daddr_t		*first_bad)	/* out: first bad log rec */
2996 {
2997 	xlog_rec_header_t	*rhead;
2998 	xfs_daddr_t		blk_no, rblk_no;
2999 	xfs_daddr_t		rhead_blk;
3000 	char			*offset;
3001 	char			*hbp, *dbp;
3002 	int			error = 0, h_size, h_len;
3003 	int			error2 = 0;
3004 	int			bblks, split_bblks;
3005 	int			hblks = 1, split_hblks, wrapped_hblks;
3006 	int			i;
3007 	struct hlist_head	rhash[XLOG_RHASH_SIZE];
3008 	LIST_HEAD		(buffer_list);
3009 
3010 	ASSERT(head_blk != tail_blk);
3011 	blk_no = rhead_blk = tail_blk;
3012 
3013 	for (i = 0; i < XLOG_RHASH_SIZE; i++)
3014 		INIT_HLIST_HEAD(&rhash[i]);
3015 
3016 	hbp = xlog_alloc_buffer(log, hblks);
3017 	if (!hbp)
3018 		return -ENOMEM;
3019 
3020 	/*
3021 	 * Read the header of the tail block and get the iclog buffer size from
3022 	 * h_size.  Use this to tell how many sectors make up the log header.
3023 	 */
3024 	if (xfs_has_logv2(log->l_mp)) {
3025 		/*
3026 		 * When using variable length iclogs, read first sector of
3027 		 * iclog header and extract the header size from it.  Get a
3028 		 * new hbp that is the correct size.
3029 		 */
3030 		error = xlog_bread(log, tail_blk, 1, hbp, &offset);
3031 		if (error)
3032 			goto bread_err1;
3033 
3034 		rhead = (xlog_rec_header_t *)offset;
3035 
3036 		/*
3037 		 * xfsprogs has a bug where record length is based on lsunit but
3038 		 * h_size (iclog size) is hardcoded to 32k. Now that we
3039 		 * unconditionally CRC verify the unmount record, this means the
3040 		 * log buffer can be too small for the record and cause an
3041 		 * overrun.
3042 		 *
3043 		 * Detect this condition here. Use lsunit for the buffer size as
3044 		 * long as this looks like the mkfs case. Otherwise, return an
3045 		 * error to avoid a buffer overrun.
3046 		 */
3047 		h_size = be32_to_cpu(rhead->h_size);
3048 		h_len = be32_to_cpu(rhead->h_len);
3049 		if (h_len > h_size && h_len <= log->l_mp->m_logbsize &&
3050 		    rhead->h_num_logops == cpu_to_be32(1)) {
3051 			xfs_warn(log->l_mp,
3052 		"invalid iclog size (%d bytes), using lsunit (%d bytes)",
3053 				 h_size, log->l_mp->m_logbsize);
3054 			h_size = log->l_mp->m_logbsize;
3055 		}
3056 
3057 		error = xlog_valid_rec_header(log, rhead, tail_blk, h_size);
3058 		if (error)
3059 			goto bread_err1;
3060 
3061 		/*
3062 		 * This open codes xlog_logrec_hblks so that we can reuse the
3063 		 * fixed up h_size value calculated above.  Without that we'd
3064 		 * still allocate the buffer based on the incorrect on-disk
3065 		 * size.
3066 		 */
3067 		if (h_size > XLOG_HEADER_CYCLE_SIZE &&
3068 		    (rhead->h_version & cpu_to_be32(XLOG_VERSION_2))) {
3069 			hblks = DIV_ROUND_UP(h_size, XLOG_HEADER_CYCLE_SIZE);
3070 			if (hblks > 1) {
3071 				kvfree(hbp);
3072 				hbp = xlog_alloc_buffer(log, hblks);
3073 				if (!hbp)
3074 					return -ENOMEM;
3075 			}
3076 		}
3077 	} else {
3078 		ASSERT(log->l_sectBBsize == 1);
3079 		h_size = XLOG_BIG_RECORD_BSIZE;
3080 	}
3081 
3082 	dbp = xlog_alloc_buffer(log, BTOBB(h_size));
3083 	if (!dbp) {
3084 		kvfree(hbp);
3085 		return -ENOMEM;
3086 	}
3087 
3088 	memset(rhash, 0, sizeof(rhash));
3089 	if (tail_blk > head_blk) {
3090 		/*
3091 		 * Perform recovery around the end of the physical log.
3092 		 * When the head is not on the same cycle number as the tail,
3093 		 * we can't do a sequential recovery.
3094 		 */
3095 		while (blk_no < log->l_logBBsize) {
3096 			/*
3097 			 * Check for header wrapping around physical end-of-log
3098 			 */
3099 			offset = hbp;
3100 			split_hblks = 0;
3101 			wrapped_hblks = 0;
3102 			if (blk_no + hblks <= log->l_logBBsize) {
3103 				/* Read header in one read */
3104 				error = xlog_bread(log, blk_no, hblks, hbp,
3105 						   &offset);
3106 				if (error)
3107 					goto bread_err2;
3108 			} else {
3109 				/* This LR is split across physical log end */
3110 				if (blk_no != log->l_logBBsize) {
3111 					/* some data before physical log end */
3112 					ASSERT(blk_no <= INT_MAX);
3113 					split_hblks = log->l_logBBsize - (int)blk_no;
3114 					ASSERT(split_hblks > 0);
3115 					error = xlog_bread(log, blk_no,
3116 							   split_hblks, hbp,
3117 							   &offset);
3118 					if (error)
3119 						goto bread_err2;
3120 				}
3121 
3122 				/*
3123 				 * Note: this black magic still works with
3124 				 * large sector sizes (non-512) only because:
3125 				 * - we increased the buffer size originally
3126 				 *   by 1 sector giving us enough extra space
3127 				 *   for the second read;
3128 				 * - the log start is guaranteed to be sector
3129 				 *   aligned;
3130 				 * - we read the log end (LR header start)
3131 				 *   _first_, then the log start (LR header end)
3132 				 *   - order is important.
3133 				 */
3134 				wrapped_hblks = hblks - split_hblks;
3135 				error = xlog_bread_noalign(log, 0,
3136 						wrapped_hblks,
3137 						offset + BBTOB(split_hblks));
3138 				if (error)
3139 					goto bread_err2;
3140 			}
3141 			rhead = (xlog_rec_header_t *)offset;
3142 			error = xlog_valid_rec_header(log, rhead,
3143 					split_hblks ? blk_no : 0, h_size);
3144 			if (error)
3145 				goto bread_err2;
3146 
3147 			bblks = (int)BTOBB(be32_to_cpu(rhead->h_len));
3148 			blk_no += hblks;
3149 
3150 			/*
3151 			 * Read the log record data in multiple reads if it
3152 			 * wraps around the end of the log. Note that if the
3153 			 * header already wrapped, blk_no could point past the
3154 			 * end of the log. The record data is contiguous in
3155 			 * that case.
3156 			 */
3157 			if (blk_no + bblks <= log->l_logBBsize ||
3158 			    blk_no >= log->l_logBBsize) {
3159 				rblk_no = xlog_wrap_logbno(log, blk_no);
3160 				error = xlog_bread(log, rblk_no, bblks, dbp,
3161 						   &offset);
3162 				if (error)
3163 					goto bread_err2;
3164 			} else {
3165 				/* This log record is split across the
3166 				 * physical end of log */
3167 				offset = dbp;
3168 				split_bblks = 0;
3169 				if (blk_no != log->l_logBBsize) {
3170 					/* some data is before the physical
3171 					 * end of log */
3172 					ASSERT(!wrapped_hblks);
3173 					ASSERT(blk_no <= INT_MAX);
3174 					split_bblks =
3175 						log->l_logBBsize - (int)blk_no;
3176 					ASSERT(split_bblks > 0);
3177 					error = xlog_bread(log, blk_no,
3178 							split_bblks, dbp,
3179 							&offset);
3180 					if (error)
3181 						goto bread_err2;
3182 				}
3183 
3184 				/*
3185 				 * Note: this black magic still works with
3186 				 * large sector sizes (non-512) only because:
3187 				 * - we increased the buffer size originally
3188 				 *   by 1 sector giving us enough extra space
3189 				 *   for the second read;
3190 				 * - the log start is guaranteed to be sector
3191 				 *   aligned;
3192 				 * - we read the log end (LR header start)
3193 				 *   _first_, then the log start (LR header end)
3194 				 *   - order is important.
3195 				 */
3196 				error = xlog_bread_noalign(log, 0,
3197 						bblks - split_bblks,
3198 						offset + BBTOB(split_bblks));
3199 				if (error)
3200 					goto bread_err2;
3201 			}
3202 
3203 			error = xlog_recover_process(log, rhash, rhead, offset,
3204 						     pass, &buffer_list);
3205 			if (error)
3206 				goto bread_err2;
3207 
3208 			blk_no += bblks;
3209 			rhead_blk = blk_no;
3210 		}
3211 
3212 		ASSERT(blk_no >= log->l_logBBsize);
3213 		blk_no -= log->l_logBBsize;
3214 		rhead_blk = blk_no;
3215 	}
3216 
3217 	/* read first part of physical log */
3218 	while (blk_no < head_blk) {
3219 		error = xlog_bread(log, blk_no, hblks, hbp, &offset);
3220 		if (error)
3221 			goto bread_err2;
3222 
3223 		rhead = (xlog_rec_header_t *)offset;
3224 		error = xlog_valid_rec_header(log, rhead, blk_no, h_size);
3225 		if (error)
3226 			goto bread_err2;
3227 
3228 		/* blocks in data section */
3229 		bblks = (int)BTOBB(be32_to_cpu(rhead->h_len));
3230 		error = xlog_bread(log, blk_no+hblks, bblks, dbp,
3231 				   &offset);
3232 		if (error)
3233 			goto bread_err2;
3234 
3235 		error = xlog_recover_process(log, rhash, rhead, offset, pass,
3236 					     &buffer_list);
3237 		if (error)
3238 			goto bread_err2;
3239 
3240 		blk_no += bblks + hblks;
3241 		rhead_blk = blk_no;
3242 	}
3243 
3244  bread_err2:
3245 	kvfree(dbp);
3246  bread_err1:
3247 	kvfree(hbp);
3248 
3249 	/*
3250 	 * Submit buffers that have been dirtied by the last record recovered.
3251 	 */
3252 	if (!list_empty(&buffer_list)) {
3253 		if (error) {
3254 			/*
3255 			 * If there has been an item recovery error then we
3256 			 * cannot allow partial checkpoint writeback to
3257 			 * occur.  We might have multiple checkpoints with the
3258 			 * same start LSN in this buffer list, and partial
3259 			 * writeback of a checkpoint in this situation can
3260 			 * prevent future recovery of all the changes in the
3261 			 * checkpoints at this start LSN.
3262 			 *
3263 			 * Note: Shutting down the filesystem will result in the
3264 			 * delwri submission marking all the buffers stale,
3265 			 * completing them and cleaning up _XBF_LOGRECOVERY
3266 			 * state without doing any IO.
3267 			 */
3268 			xlog_force_shutdown(log, SHUTDOWN_LOG_IO_ERROR);
3269 		}
3270 		error2 = xfs_buf_delwri_submit(&buffer_list);
3271 	}
3272 
3273 	if (error && first_bad)
3274 		*first_bad = rhead_blk;
3275 
3276 	/*
3277 	 * Transactions are freed at commit time but transactions without commit
3278 	 * records on disk are never committed. Free any that may be left in the
3279 	 * hash table.
3280 	 */
3281 	for (i = 0; i < XLOG_RHASH_SIZE; i++) {
3282 		struct hlist_node	*tmp;
3283 		struct xlog_recover	*trans;
3284 
3285 		hlist_for_each_entry_safe(trans, tmp, &rhash[i], r_list)
3286 			xlog_recover_free_trans(trans);
3287 	}
3288 
3289 	return error ? error : error2;
3290 }
3291 
3292 /*
3293  * Do the recovery of the log.  We actually do this in two phases.
3294  * The two passes are necessary in order to implement the function
3295  * of cancelling a record written into the log.  The first pass
3296  * determines those things which have been cancelled, and the
3297  * second pass replays log items normally except for those which
3298  * have been cancelled.  The handling of the replay and cancellations
3299  * takes place in the log item type specific routines.
3300  *
3301  * The table of items which have cancel records in the log is allocated
3302  * and freed at this level, since only here do we know when all of
3303  * the log recovery has been completed.
3304  */
3305 STATIC int
xlog_do_log_recovery(struct xlog * log,xfs_daddr_t head_blk,xfs_daddr_t tail_blk)3306 xlog_do_log_recovery(
3307 	struct xlog	*log,
3308 	xfs_daddr_t	head_blk,
3309 	xfs_daddr_t	tail_blk)
3310 {
3311 	int		error;
3312 
3313 	ASSERT(head_blk != tail_blk);
3314 
3315 	/*
3316 	 * First do a pass to find all of the cancelled buf log items.
3317 	 * Store them in the buf_cancel_table for use in the second pass.
3318 	 */
3319 	error = xlog_alloc_buf_cancel_table(log);
3320 	if (error)
3321 		return error;
3322 
3323 	error = xlog_do_recovery_pass(log, head_blk, tail_blk,
3324 				      XLOG_RECOVER_PASS1, NULL);
3325 	if (error != 0)
3326 		goto out_cancel;
3327 
3328 	/*
3329 	 * Then do a second pass to actually recover the items in the log.
3330 	 * When it is complete free the table of buf cancel items.
3331 	 */
3332 	error = xlog_do_recovery_pass(log, head_blk, tail_blk,
3333 				      XLOG_RECOVER_PASS2, NULL);
3334 	if (!error)
3335 		xlog_check_buf_cancel_table(log);
3336 out_cancel:
3337 	xlog_free_buf_cancel_table(log);
3338 	return error;
3339 }
3340 
3341 /*
3342  * Do the actual recovery
3343  */
3344 STATIC int
xlog_do_recover(struct xlog * log,xfs_daddr_t head_blk,xfs_daddr_t tail_blk)3345 xlog_do_recover(
3346 	struct xlog		*log,
3347 	xfs_daddr_t		head_blk,
3348 	xfs_daddr_t		tail_blk)
3349 {
3350 	struct xfs_mount	*mp = log->l_mp;
3351 	struct xfs_buf		*bp = mp->m_sb_bp;
3352 	struct xfs_sb		*sbp = &mp->m_sb;
3353 	int			error;
3354 
3355 	trace_xfs_log_recover(log, head_blk, tail_blk);
3356 
3357 	/*
3358 	 * First replay the images in the log.
3359 	 */
3360 	error = xlog_do_log_recovery(log, head_blk, tail_blk);
3361 	if (error)
3362 		return error;
3363 
3364 	if (xlog_is_shutdown(log))
3365 		return -EIO;
3366 
3367 	/*
3368 	 * We now update the tail_lsn since much of the recovery has completed
3369 	 * and there may be space available to use.  If there were no extent or
3370 	 * iunlinks, we can free up the entire log.  This was set in
3371 	 * xlog_find_tail to be the lsn of the last known good LR on disk.  If
3372 	 * there are extent frees or iunlinks they will have some entries in the
3373 	 * AIL; so we look at the AIL to determine how to set the tail_lsn.
3374 	 */
3375 	xfs_ail_assign_tail_lsn(log->l_ailp);
3376 
3377 	/*
3378 	 * Now that we've finished replaying all buffer and inode updates,
3379 	 * re-read the superblock and reverify it.
3380 	 */
3381 	xfs_buf_lock(bp);
3382 	xfs_buf_hold(bp);
3383 	error = _xfs_buf_read(bp);
3384 	if (error) {
3385 		if (!xlog_is_shutdown(log)) {
3386 			xfs_buf_ioerror_alert(bp, __this_address);
3387 			ASSERT(0);
3388 		}
3389 		xfs_buf_relse(bp);
3390 		return error;
3391 	}
3392 
3393 	/* Convert superblock from on-disk format */
3394 	xfs_sb_from_disk(sbp, bp->b_addr);
3395 	xfs_buf_relse(bp);
3396 
3397 	/* re-initialise in-core superblock and geometry structures */
3398 	mp->m_features |= xfs_sb_version_to_features(sbp);
3399 	xfs_reinit_percpu_counters(mp);
3400 
3401 	/* Normal transactions can now occur */
3402 	clear_bit(XLOG_ACTIVE_RECOVERY, &log->l_opstate);
3403 	return 0;
3404 }
3405 
3406 /*
3407  * Perform recovery and re-initialize some log variables in xlog_find_tail.
3408  *
3409  * Return error or zero.
3410  */
3411 int
xlog_recover(struct xlog * log)3412 xlog_recover(
3413 	struct xlog	*log)
3414 {
3415 	xfs_daddr_t	head_blk, tail_blk;
3416 	int		error;
3417 
3418 	/* find the tail of the log */
3419 	error = xlog_find_tail(log, &head_blk, &tail_blk);
3420 	if (error)
3421 		return error;
3422 
3423 	/*
3424 	 * The superblock was read before the log was available and thus the LSN
3425 	 * could not be verified. Check the superblock LSN against the current
3426 	 * LSN now that it's known.
3427 	 */
3428 	if (xfs_has_crc(log->l_mp) &&
3429 	    !xfs_log_check_lsn(log->l_mp, log->l_mp->m_sb.sb_lsn))
3430 		return -EINVAL;
3431 
3432 	if (tail_blk != head_blk) {
3433 		/* There used to be a comment here:
3434 		 *
3435 		 * disallow recovery on read-only mounts.  note -- mount
3436 		 * checks for ENOSPC and turns it into an intelligent
3437 		 * error message.
3438 		 * ...but this is no longer true.  Now, unless you specify
3439 		 * NORECOVERY (in which case this function would never be
3440 		 * called), we just go ahead and recover.  We do this all
3441 		 * under the vfs layer, so we can get away with it unless
3442 		 * the device itself is read-only, in which case we fail.
3443 		 */
3444 		if ((error = xfs_dev_is_read_only(log->l_mp, "recovery"))) {
3445 			return error;
3446 		}
3447 
3448 		/*
3449 		 * Version 5 superblock log feature mask validation. We know the
3450 		 * log is dirty so check if there are any unknown log features
3451 		 * in what we need to recover. If there are unknown features
3452 		 * (e.g. unsupported transactions, then simply reject the
3453 		 * attempt at recovery before touching anything.
3454 		 */
3455 		if (xfs_sb_is_v5(&log->l_mp->m_sb) &&
3456 		    xfs_sb_has_incompat_log_feature(&log->l_mp->m_sb,
3457 					XFS_SB_FEAT_INCOMPAT_LOG_UNKNOWN)) {
3458 			xfs_warn(log->l_mp,
3459 "Superblock has unknown incompatible log features (0x%x) enabled.",
3460 				(log->l_mp->m_sb.sb_features_log_incompat &
3461 					XFS_SB_FEAT_INCOMPAT_LOG_UNKNOWN));
3462 			xfs_warn(log->l_mp,
3463 "The log can not be fully and/or safely recovered by this kernel.");
3464 			xfs_warn(log->l_mp,
3465 "Please recover the log on a kernel that supports the unknown features.");
3466 			return -EINVAL;
3467 		}
3468 
3469 		/*
3470 		 * Delay log recovery if the debug hook is set. This is debug
3471 		 * instrumentation to coordinate simulation of I/O failures with
3472 		 * log recovery.
3473 		 */
3474 		if (xfs_globals.log_recovery_delay) {
3475 			xfs_notice(log->l_mp,
3476 				"Delaying log recovery for %d seconds.",
3477 				xfs_globals.log_recovery_delay);
3478 			msleep(xfs_globals.log_recovery_delay * 1000);
3479 		}
3480 
3481 		xfs_notice(log->l_mp, "Starting recovery (logdev: %s)",
3482 				log->l_mp->m_logname ? log->l_mp->m_logname
3483 						     : "internal");
3484 
3485 		error = xlog_do_recover(log, head_blk, tail_blk);
3486 		set_bit(XLOG_RECOVERY_NEEDED, &log->l_opstate);
3487 	}
3488 	return error;
3489 }
3490 
3491 /*
3492  * In the first part of recovery we replay inodes and buffers and build up the
3493  * list of intents which need to be processed. Here we process the intents and
3494  * clean up the on disk unlinked inode lists. This is separated from the first
3495  * part of recovery so that the root and real-time bitmap inodes can be read in
3496  * from disk in between the two stages.  This is necessary so that we can free
3497  * space in the real-time portion of the file system.
3498  *
3499  * We run this whole process under GFP_NOFS allocation context. We do a
3500  * combination of non-transactional and transactional work, yet we really don't
3501  * want to recurse into the filesystem from direct reclaim during any of this
3502  * processing. This allows all the recovery code run here not to care about the
3503  * memory allocation context it is running in.
3504  */
3505 int
xlog_recover_finish(struct xlog * log)3506 xlog_recover_finish(
3507 	struct xlog	*log)
3508 {
3509 	unsigned int	nofs_flags = memalloc_nofs_save();
3510 	int		error;
3511 
3512 	error = xlog_recover_process_intents(log);
3513 	if (error) {
3514 		/*
3515 		 * Cancel all the unprocessed intent items now so that we don't
3516 		 * leave them pinned in the AIL.  This can cause the AIL to
3517 		 * livelock on the pinned item if anyone tries to push the AIL
3518 		 * (inode reclaim does this) before we get around to
3519 		 * xfs_log_mount_cancel.
3520 		 */
3521 		xlog_recover_cancel_intents(log);
3522 		xfs_alert(log->l_mp, "Failed to recover intents");
3523 		xlog_force_shutdown(log, SHUTDOWN_LOG_IO_ERROR);
3524 		goto out_error;
3525 	}
3526 
3527 	/*
3528 	 * Sync the log to get all the intents out of the AIL.  This isn't
3529 	 * absolutely necessary, but it helps in case the unlink transactions
3530 	 * would have problems pushing the intents out of the way.
3531 	 */
3532 	xfs_log_force(log->l_mp, XFS_LOG_SYNC);
3533 
3534 	xlog_recover_process_iunlinks(log);
3535 
3536 	/*
3537 	 * Recover any CoW staging blocks that are still referenced by the
3538 	 * ondisk refcount metadata.  During mount there cannot be any live
3539 	 * staging extents as we have not permitted any user modifications.
3540 	 * Therefore, it is safe to free them all right now, even on a
3541 	 * read-only mount.
3542 	 */
3543 	error = xfs_reflink_recover_cow(log->l_mp);
3544 	if (error) {
3545 		xfs_alert(log->l_mp,
3546 	"Failed to recover leftover CoW staging extents, err %d.",
3547 				error);
3548 		/*
3549 		 * If we get an error here, make sure the log is shut down
3550 		 * but return zero so that any log items committed since the
3551 		 * end of intents processing can be pushed through the CIL
3552 		 * and AIL.
3553 		 */
3554 		xlog_force_shutdown(log, SHUTDOWN_LOG_IO_ERROR);
3555 		error = 0;
3556 		goto out_error;
3557 	}
3558 
3559 out_error:
3560 	memalloc_nofs_restore(nofs_flags);
3561 	return error;
3562 }
3563 
3564 void
xlog_recover_cancel(struct xlog * log)3565 xlog_recover_cancel(
3566 	struct xlog	*log)
3567 {
3568 	if (xlog_recovery_needed(log))
3569 		xlog_recover_cancel_intents(log);
3570 }
3571 
3572