xref: /openbmc/linux/fs/xfs/xfs_buf_item_recover.c (revision ed84ef1c)
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_mount.h"
14 #include "xfs_trans.h"
15 #include "xfs_buf_item.h"
16 #include "xfs_trans_priv.h"
17 #include "xfs_trace.h"
18 #include "xfs_log.h"
19 #include "xfs_log_priv.h"
20 #include "xfs_log_recover.h"
21 #include "xfs_error.h"
22 #include "xfs_inode.h"
23 #include "xfs_dir2.h"
24 #include "xfs_quota.h"
25 
26 /*
27  * This structure is used during recovery to record the buf log items which
28  * have been canceled and should not be replayed.
29  */
30 struct xfs_buf_cancel {
31 	xfs_daddr_t		bc_blkno;
32 	uint			bc_len;
33 	int			bc_refcount;
34 	struct list_head	bc_list;
35 };
36 
37 static struct xfs_buf_cancel *
38 xlog_find_buffer_cancelled(
39 	struct xlog		*log,
40 	xfs_daddr_t		blkno,
41 	uint			len)
42 {
43 	struct list_head	*bucket;
44 	struct xfs_buf_cancel	*bcp;
45 
46 	if (!log->l_buf_cancel_table)
47 		return NULL;
48 
49 	bucket = XLOG_BUF_CANCEL_BUCKET(log, blkno);
50 	list_for_each_entry(bcp, bucket, bc_list) {
51 		if (bcp->bc_blkno == blkno && bcp->bc_len == len)
52 			return bcp;
53 	}
54 
55 	return NULL;
56 }
57 
58 static bool
59 xlog_add_buffer_cancelled(
60 	struct xlog		*log,
61 	xfs_daddr_t		blkno,
62 	uint			len)
63 {
64 	struct xfs_buf_cancel	*bcp;
65 
66 	/*
67 	 * If we find an existing cancel record, this indicates that the buffer
68 	 * was cancelled multiple times.  To ensure that during pass 2 we keep
69 	 * the record in the table until we reach its last occurrence in the
70 	 * log, a reference count is kept to tell how many times we expect to
71 	 * see this record during the second pass.
72 	 */
73 	bcp = xlog_find_buffer_cancelled(log, blkno, len);
74 	if (bcp) {
75 		bcp->bc_refcount++;
76 		return false;
77 	}
78 
79 	bcp = kmem_alloc(sizeof(struct xfs_buf_cancel), 0);
80 	bcp->bc_blkno = blkno;
81 	bcp->bc_len = len;
82 	bcp->bc_refcount = 1;
83 	list_add_tail(&bcp->bc_list, XLOG_BUF_CANCEL_BUCKET(log, blkno));
84 	return true;
85 }
86 
87 /*
88  * Check if there is and entry for blkno, len in the buffer cancel record table.
89  */
90 bool
91 xlog_is_buffer_cancelled(
92 	struct xlog		*log,
93 	xfs_daddr_t		blkno,
94 	uint			len)
95 {
96 	return xlog_find_buffer_cancelled(log, blkno, len) != NULL;
97 }
98 
99 /*
100  * Check if there is and entry for blkno, len in the buffer cancel record table,
101  * and decremented the reference count on it if there is one.
102  *
103  * Remove the cancel record once the refcount hits zero, so that if the same
104  * buffer is re-used again after its last cancellation we actually replay the
105  * changes made at that point.
106  */
107 static bool
108 xlog_put_buffer_cancelled(
109 	struct xlog		*log,
110 	xfs_daddr_t		blkno,
111 	uint			len)
112 {
113 	struct xfs_buf_cancel	*bcp;
114 
115 	bcp = xlog_find_buffer_cancelled(log, blkno, len);
116 	if (!bcp) {
117 		ASSERT(0);
118 		return false;
119 	}
120 
121 	if (--bcp->bc_refcount == 0) {
122 		list_del(&bcp->bc_list);
123 		kmem_free(bcp);
124 	}
125 	return true;
126 }
127 
128 /* log buffer item recovery */
129 
130 /*
131  * Sort buffer items for log recovery.  Most buffer items should end up on the
132  * buffer list and are recovered first, with the following exceptions:
133  *
134  * 1. XFS_BLF_CANCEL buffers must be processed last because some log items
135  *    might depend on the incor ecancellation record, and replaying a cancelled
136  *    buffer item can remove the incore record.
137  *
138  * 2. XFS_BLF_INODE_BUF buffers are handled after most regular items so that
139  *    we replay di_next_unlinked only after flushing the inode 'free' state
140  *    to the inode buffer.
141  *
142  * See xlog_recover_reorder_trans for more details.
143  */
144 STATIC enum xlog_recover_reorder
145 xlog_recover_buf_reorder(
146 	struct xlog_recover_item	*item)
147 {
148 	struct xfs_buf_log_format	*buf_f = item->ri_buf[0].i_addr;
149 
150 	if (buf_f->blf_flags & XFS_BLF_CANCEL)
151 		return XLOG_REORDER_CANCEL_LIST;
152 	if (buf_f->blf_flags & XFS_BLF_INODE_BUF)
153 		return XLOG_REORDER_INODE_BUFFER_LIST;
154 	return XLOG_REORDER_BUFFER_LIST;
155 }
156 
157 STATIC void
158 xlog_recover_buf_ra_pass2(
159 	struct xlog                     *log,
160 	struct xlog_recover_item        *item)
161 {
162 	struct xfs_buf_log_format	*buf_f = item->ri_buf[0].i_addr;
163 
164 	xlog_buf_readahead(log, buf_f->blf_blkno, buf_f->blf_len, NULL);
165 }
166 
167 /*
168  * Build up the table of buf cancel records so that we don't replay cancelled
169  * data in the second pass.
170  */
171 static int
172 xlog_recover_buf_commit_pass1(
173 	struct xlog			*log,
174 	struct xlog_recover_item	*item)
175 {
176 	struct xfs_buf_log_format	*bf = item->ri_buf[0].i_addr;
177 
178 	if (!xfs_buf_log_check_iovec(&item->ri_buf[0])) {
179 		xfs_err(log->l_mp, "bad buffer log item size (%d)",
180 				item->ri_buf[0].i_len);
181 		return -EFSCORRUPTED;
182 	}
183 
184 	if (!(bf->blf_flags & XFS_BLF_CANCEL))
185 		trace_xfs_log_recover_buf_not_cancel(log, bf);
186 	else if (xlog_add_buffer_cancelled(log, bf->blf_blkno, bf->blf_len))
187 		trace_xfs_log_recover_buf_cancel_add(log, bf);
188 	else
189 		trace_xfs_log_recover_buf_cancel_ref_inc(log, bf);
190 	return 0;
191 }
192 
193 /*
194  * Validate the recovered buffer is of the correct type and attach the
195  * appropriate buffer operations to them for writeback. Magic numbers are in a
196  * few places:
197  *	the first 16 bits of the buffer (inode buffer, dquot buffer),
198  *	the first 32 bits of the buffer (most blocks),
199  *	inside a struct xfs_da_blkinfo at the start of the buffer.
200  */
201 static void
202 xlog_recover_validate_buf_type(
203 	struct xfs_mount		*mp,
204 	struct xfs_buf			*bp,
205 	struct xfs_buf_log_format	*buf_f,
206 	xfs_lsn_t			current_lsn)
207 {
208 	struct xfs_da_blkinfo		*info = bp->b_addr;
209 	uint32_t			magic32;
210 	uint16_t			magic16;
211 	uint16_t			magicda;
212 	char				*warnmsg = NULL;
213 
214 	/*
215 	 * We can only do post recovery validation on items on CRC enabled
216 	 * fielsystems as we need to know when the buffer was written to be able
217 	 * to determine if we should have replayed the item. If we replay old
218 	 * metadata over a newer buffer, then it will enter a temporarily
219 	 * inconsistent state resulting in verification failures. Hence for now
220 	 * just avoid the verification stage for non-crc filesystems
221 	 */
222 	if (!xfs_has_crc(mp))
223 		return;
224 
225 	magic32 = be32_to_cpu(*(__be32 *)bp->b_addr);
226 	magic16 = be16_to_cpu(*(__be16*)bp->b_addr);
227 	magicda = be16_to_cpu(info->magic);
228 	switch (xfs_blft_from_flags(buf_f)) {
229 	case XFS_BLFT_BTREE_BUF:
230 		switch (magic32) {
231 		case XFS_ABTB_CRC_MAGIC:
232 		case XFS_ABTB_MAGIC:
233 			bp->b_ops = &xfs_bnobt_buf_ops;
234 			break;
235 		case XFS_ABTC_CRC_MAGIC:
236 		case XFS_ABTC_MAGIC:
237 			bp->b_ops = &xfs_cntbt_buf_ops;
238 			break;
239 		case XFS_IBT_CRC_MAGIC:
240 		case XFS_IBT_MAGIC:
241 			bp->b_ops = &xfs_inobt_buf_ops;
242 			break;
243 		case XFS_FIBT_CRC_MAGIC:
244 		case XFS_FIBT_MAGIC:
245 			bp->b_ops = &xfs_finobt_buf_ops;
246 			break;
247 		case XFS_BMAP_CRC_MAGIC:
248 		case XFS_BMAP_MAGIC:
249 			bp->b_ops = &xfs_bmbt_buf_ops;
250 			break;
251 		case XFS_RMAP_CRC_MAGIC:
252 			bp->b_ops = &xfs_rmapbt_buf_ops;
253 			break;
254 		case XFS_REFC_CRC_MAGIC:
255 			bp->b_ops = &xfs_refcountbt_buf_ops;
256 			break;
257 		default:
258 			warnmsg = "Bad btree block magic!";
259 			break;
260 		}
261 		break;
262 	case XFS_BLFT_AGF_BUF:
263 		if (magic32 != XFS_AGF_MAGIC) {
264 			warnmsg = "Bad AGF block magic!";
265 			break;
266 		}
267 		bp->b_ops = &xfs_agf_buf_ops;
268 		break;
269 	case XFS_BLFT_AGFL_BUF:
270 		if (magic32 != XFS_AGFL_MAGIC) {
271 			warnmsg = "Bad AGFL block magic!";
272 			break;
273 		}
274 		bp->b_ops = &xfs_agfl_buf_ops;
275 		break;
276 	case XFS_BLFT_AGI_BUF:
277 		if (magic32 != XFS_AGI_MAGIC) {
278 			warnmsg = "Bad AGI block magic!";
279 			break;
280 		}
281 		bp->b_ops = &xfs_agi_buf_ops;
282 		break;
283 	case XFS_BLFT_UDQUOT_BUF:
284 	case XFS_BLFT_PDQUOT_BUF:
285 	case XFS_BLFT_GDQUOT_BUF:
286 #ifdef CONFIG_XFS_QUOTA
287 		if (magic16 != XFS_DQUOT_MAGIC) {
288 			warnmsg = "Bad DQUOT block magic!";
289 			break;
290 		}
291 		bp->b_ops = &xfs_dquot_buf_ops;
292 #else
293 		xfs_alert(mp,
294 	"Trying to recover dquots without QUOTA support built in!");
295 		ASSERT(0);
296 #endif
297 		break;
298 	case XFS_BLFT_DINO_BUF:
299 		if (magic16 != XFS_DINODE_MAGIC) {
300 			warnmsg = "Bad INODE block magic!";
301 			break;
302 		}
303 		bp->b_ops = &xfs_inode_buf_ops;
304 		break;
305 	case XFS_BLFT_SYMLINK_BUF:
306 		if (magic32 != XFS_SYMLINK_MAGIC) {
307 			warnmsg = "Bad symlink block magic!";
308 			break;
309 		}
310 		bp->b_ops = &xfs_symlink_buf_ops;
311 		break;
312 	case XFS_BLFT_DIR_BLOCK_BUF:
313 		if (magic32 != XFS_DIR2_BLOCK_MAGIC &&
314 		    magic32 != XFS_DIR3_BLOCK_MAGIC) {
315 			warnmsg = "Bad dir block magic!";
316 			break;
317 		}
318 		bp->b_ops = &xfs_dir3_block_buf_ops;
319 		break;
320 	case XFS_BLFT_DIR_DATA_BUF:
321 		if (magic32 != XFS_DIR2_DATA_MAGIC &&
322 		    magic32 != XFS_DIR3_DATA_MAGIC) {
323 			warnmsg = "Bad dir data magic!";
324 			break;
325 		}
326 		bp->b_ops = &xfs_dir3_data_buf_ops;
327 		break;
328 	case XFS_BLFT_DIR_FREE_BUF:
329 		if (magic32 != XFS_DIR2_FREE_MAGIC &&
330 		    magic32 != XFS_DIR3_FREE_MAGIC) {
331 			warnmsg = "Bad dir3 free magic!";
332 			break;
333 		}
334 		bp->b_ops = &xfs_dir3_free_buf_ops;
335 		break;
336 	case XFS_BLFT_DIR_LEAF1_BUF:
337 		if (magicda != XFS_DIR2_LEAF1_MAGIC &&
338 		    magicda != XFS_DIR3_LEAF1_MAGIC) {
339 			warnmsg = "Bad dir leaf1 magic!";
340 			break;
341 		}
342 		bp->b_ops = &xfs_dir3_leaf1_buf_ops;
343 		break;
344 	case XFS_BLFT_DIR_LEAFN_BUF:
345 		if (magicda != XFS_DIR2_LEAFN_MAGIC &&
346 		    magicda != XFS_DIR3_LEAFN_MAGIC) {
347 			warnmsg = "Bad dir leafn magic!";
348 			break;
349 		}
350 		bp->b_ops = &xfs_dir3_leafn_buf_ops;
351 		break;
352 	case XFS_BLFT_DA_NODE_BUF:
353 		if (magicda != XFS_DA_NODE_MAGIC &&
354 		    magicda != XFS_DA3_NODE_MAGIC) {
355 			warnmsg = "Bad da node magic!";
356 			break;
357 		}
358 		bp->b_ops = &xfs_da3_node_buf_ops;
359 		break;
360 	case XFS_BLFT_ATTR_LEAF_BUF:
361 		if (magicda != XFS_ATTR_LEAF_MAGIC &&
362 		    magicda != XFS_ATTR3_LEAF_MAGIC) {
363 			warnmsg = "Bad attr leaf magic!";
364 			break;
365 		}
366 		bp->b_ops = &xfs_attr3_leaf_buf_ops;
367 		break;
368 	case XFS_BLFT_ATTR_RMT_BUF:
369 		if (magic32 != XFS_ATTR3_RMT_MAGIC) {
370 			warnmsg = "Bad attr remote magic!";
371 			break;
372 		}
373 		bp->b_ops = &xfs_attr3_rmt_buf_ops;
374 		break;
375 	case XFS_BLFT_SB_BUF:
376 		if (magic32 != XFS_SB_MAGIC) {
377 			warnmsg = "Bad SB block magic!";
378 			break;
379 		}
380 		bp->b_ops = &xfs_sb_buf_ops;
381 		break;
382 #ifdef CONFIG_XFS_RT
383 	case XFS_BLFT_RTBITMAP_BUF:
384 	case XFS_BLFT_RTSUMMARY_BUF:
385 		/* no magic numbers for verification of RT buffers */
386 		bp->b_ops = &xfs_rtbuf_ops;
387 		break;
388 #endif /* CONFIG_XFS_RT */
389 	default:
390 		xfs_warn(mp, "Unknown buffer type %d!",
391 			 xfs_blft_from_flags(buf_f));
392 		break;
393 	}
394 
395 	/*
396 	 * Nothing else to do in the case of a NULL current LSN as this means
397 	 * the buffer is more recent than the change in the log and will be
398 	 * skipped.
399 	 */
400 	if (current_lsn == NULLCOMMITLSN)
401 		return;
402 
403 	if (warnmsg) {
404 		xfs_warn(mp, warnmsg);
405 		ASSERT(0);
406 	}
407 
408 	/*
409 	 * We must update the metadata LSN of the buffer as it is written out to
410 	 * ensure that older transactions never replay over this one and corrupt
411 	 * the buffer. This can occur if log recovery is interrupted at some
412 	 * point after the current transaction completes, at which point a
413 	 * subsequent mount starts recovery from the beginning.
414 	 *
415 	 * Write verifiers update the metadata LSN from log items attached to
416 	 * the buffer. Therefore, initialize a bli purely to carry the LSN to
417 	 * the verifier.
418 	 */
419 	if (bp->b_ops) {
420 		struct xfs_buf_log_item	*bip;
421 
422 		bp->b_flags |= _XBF_LOGRECOVERY;
423 		xfs_buf_item_init(bp, mp);
424 		bip = bp->b_log_item;
425 		bip->bli_item.li_lsn = current_lsn;
426 	}
427 }
428 
429 /*
430  * Perform a 'normal' buffer recovery.  Each logged region of the
431  * buffer should be copied over the corresponding region in the
432  * given buffer.  The bitmap in the buf log format structure indicates
433  * where to place the logged data.
434  */
435 STATIC void
436 xlog_recover_do_reg_buffer(
437 	struct xfs_mount		*mp,
438 	struct xlog_recover_item	*item,
439 	struct xfs_buf			*bp,
440 	struct xfs_buf_log_format	*buf_f,
441 	xfs_lsn_t			current_lsn)
442 {
443 	int			i;
444 	int			bit;
445 	int			nbits;
446 	xfs_failaddr_t		fa;
447 	const size_t		size_disk_dquot = sizeof(struct xfs_disk_dquot);
448 
449 	trace_xfs_log_recover_buf_reg_buf(mp->m_log, buf_f);
450 
451 	bit = 0;
452 	i = 1;  /* 0 is the buf format structure */
453 	while (1) {
454 		bit = xfs_next_bit(buf_f->blf_data_map,
455 				   buf_f->blf_map_size, bit);
456 		if (bit == -1)
457 			break;
458 		nbits = xfs_contig_bits(buf_f->blf_data_map,
459 					buf_f->blf_map_size, bit);
460 		ASSERT(nbits > 0);
461 		ASSERT(item->ri_buf[i].i_addr != NULL);
462 		ASSERT(item->ri_buf[i].i_len % XFS_BLF_CHUNK == 0);
463 		ASSERT(BBTOB(bp->b_length) >=
464 		       ((uint)bit << XFS_BLF_SHIFT) + (nbits << XFS_BLF_SHIFT));
465 
466 		/*
467 		 * The dirty regions logged in the buffer, even though
468 		 * contiguous, may span multiple chunks. This is because the
469 		 * dirty region may span a physical page boundary in a buffer
470 		 * and hence be split into two separate vectors for writing into
471 		 * the log. Hence we need to trim nbits back to the length of
472 		 * the current region being copied out of the log.
473 		 */
474 		if (item->ri_buf[i].i_len < (nbits << XFS_BLF_SHIFT))
475 			nbits = item->ri_buf[i].i_len >> XFS_BLF_SHIFT;
476 
477 		/*
478 		 * Do a sanity check if this is a dquot buffer. Just checking
479 		 * the first dquot in the buffer should do. XXXThis is
480 		 * probably a good thing to do for other buf types also.
481 		 */
482 		fa = NULL;
483 		if (buf_f->blf_flags &
484 		   (XFS_BLF_UDQUOT_BUF|XFS_BLF_PDQUOT_BUF|XFS_BLF_GDQUOT_BUF)) {
485 			if (item->ri_buf[i].i_addr == NULL) {
486 				xfs_alert(mp,
487 					"XFS: NULL dquot in %s.", __func__);
488 				goto next;
489 			}
490 			if (item->ri_buf[i].i_len < size_disk_dquot) {
491 				xfs_alert(mp,
492 					"XFS: dquot too small (%d) in %s.",
493 					item->ri_buf[i].i_len, __func__);
494 				goto next;
495 			}
496 			fa = xfs_dquot_verify(mp, item->ri_buf[i].i_addr, -1);
497 			if (fa) {
498 				xfs_alert(mp,
499 	"dquot corrupt at %pS trying to replay into block 0x%llx",
500 					fa, xfs_buf_daddr(bp));
501 				goto next;
502 			}
503 		}
504 
505 		memcpy(xfs_buf_offset(bp,
506 			(uint)bit << XFS_BLF_SHIFT),	/* dest */
507 			item->ri_buf[i].i_addr,		/* source */
508 			nbits<<XFS_BLF_SHIFT);		/* length */
509  next:
510 		i++;
511 		bit += nbits;
512 	}
513 
514 	/* Shouldn't be any more regions */
515 	ASSERT(i == item->ri_total);
516 
517 	xlog_recover_validate_buf_type(mp, bp, buf_f, current_lsn);
518 }
519 
520 /*
521  * Perform a dquot buffer recovery.
522  * Simple algorithm: if we have found a QUOTAOFF log item of the same type
523  * (ie. USR or GRP), then just toss this buffer away; don't recover it.
524  * Else, treat it as a regular buffer and do recovery.
525  *
526  * Return false if the buffer was tossed and true if we recovered the buffer to
527  * indicate to the caller if the buffer needs writing.
528  */
529 STATIC bool
530 xlog_recover_do_dquot_buffer(
531 	struct xfs_mount		*mp,
532 	struct xlog			*log,
533 	struct xlog_recover_item	*item,
534 	struct xfs_buf			*bp,
535 	struct xfs_buf_log_format	*buf_f)
536 {
537 	uint			type;
538 
539 	trace_xfs_log_recover_buf_dquot_buf(log, buf_f);
540 
541 	/*
542 	 * Filesystems are required to send in quota flags at mount time.
543 	 */
544 	if (!mp->m_qflags)
545 		return false;
546 
547 	type = 0;
548 	if (buf_f->blf_flags & XFS_BLF_UDQUOT_BUF)
549 		type |= XFS_DQTYPE_USER;
550 	if (buf_f->blf_flags & XFS_BLF_PDQUOT_BUF)
551 		type |= XFS_DQTYPE_PROJ;
552 	if (buf_f->blf_flags & XFS_BLF_GDQUOT_BUF)
553 		type |= XFS_DQTYPE_GROUP;
554 	/*
555 	 * This type of quotas was turned off, so ignore this buffer
556 	 */
557 	if (log->l_quotaoffs_flag & type)
558 		return false;
559 
560 	xlog_recover_do_reg_buffer(mp, item, bp, buf_f, NULLCOMMITLSN);
561 	return true;
562 }
563 
564 /*
565  * Perform recovery for a buffer full of inodes.  In these buffers, the only
566  * data which should be recovered is that which corresponds to the
567  * di_next_unlinked pointers in the on disk inode structures.  The rest of the
568  * data for the inodes is always logged through the inodes themselves rather
569  * than the inode buffer and is recovered in xlog_recover_inode_pass2().
570  *
571  * The only time when buffers full of inodes are fully recovered is when the
572  * buffer is full of newly allocated inodes.  In this case the buffer will
573  * not be marked as an inode buffer and so will be sent to
574  * xlog_recover_do_reg_buffer() below during recovery.
575  */
576 STATIC int
577 xlog_recover_do_inode_buffer(
578 	struct xfs_mount		*mp,
579 	struct xlog_recover_item	*item,
580 	struct xfs_buf			*bp,
581 	struct xfs_buf_log_format	*buf_f)
582 {
583 	int				i;
584 	int				item_index = 0;
585 	int				bit = 0;
586 	int				nbits = 0;
587 	int				reg_buf_offset = 0;
588 	int				reg_buf_bytes = 0;
589 	int				next_unlinked_offset;
590 	int				inodes_per_buf;
591 	xfs_agino_t			*logged_nextp;
592 	xfs_agino_t			*buffer_nextp;
593 
594 	trace_xfs_log_recover_buf_inode_buf(mp->m_log, buf_f);
595 
596 	/*
597 	 * Post recovery validation only works properly on CRC enabled
598 	 * filesystems.
599 	 */
600 	if (xfs_has_crc(mp))
601 		bp->b_ops = &xfs_inode_buf_ops;
602 
603 	inodes_per_buf = BBTOB(bp->b_length) >> mp->m_sb.sb_inodelog;
604 	for (i = 0; i < inodes_per_buf; i++) {
605 		next_unlinked_offset = (i * mp->m_sb.sb_inodesize) +
606 			offsetof(xfs_dinode_t, di_next_unlinked);
607 
608 		while (next_unlinked_offset >=
609 		       (reg_buf_offset + reg_buf_bytes)) {
610 			/*
611 			 * The next di_next_unlinked field is beyond
612 			 * the current logged region.  Find the next
613 			 * logged region that contains or is beyond
614 			 * the current di_next_unlinked field.
615 			 */
616 			bit += nbits;
617 			bit = xfs_next_bit(buf_f->blf_data_map,
618 					   buf_f->blf_map_size, bit);
619 
620 			/*
621 			 * If there are no more logged regions in the
622 			 * buffer, then we're done.
623 			 */
624 			if (bit == -1)
625 				return 0;
626 
627 			nbits = xfs_contig_bits(buf_f->blf_data_map,
628 						buf_f->blf_map_size, bit);
629 			ASSERT(nbits > 0);
630 			reg_buf_offset = bit << XFS_BLF_SHIFT;
631 			reg_buf_bytes = nbits << XFS_BLF_SHIFT;
632 			item_index++;
633 		}
634 
635 		/*
636 		 * If the current logged region starts after the current
637 		 * di_next_unlinked field, then move on to the next
638 		 * di_next_unlinked field.
639 		 */
640 		if (next_unlinked_offset < reg_buf_offset)
641 			continue;
642 
643 		ASSERT(item->ri_buf[item_index].i_addr != NULL);
644 		ASSERT((item->ri_buf[item_index].i_len % XFS_BLF_CHUNK) == 0);
645 		ASSERT((reg_buf_offset + reg_buf_bytes) <= BBTOB(bp->b_length));
646 
647 		/*
648 		 * The current logged region contains a copy of the
649 		 * current di_next_unlinked field.  Extract its value
650 		 * and copy it to the buffer copy.
651 		 */
652 		logged_nextp = item->ri_buf[item_index].i_addr +
653 				next_unlinked_offset - reg_buf_offset;
654 		if (XFS_IS_CORRUPT(mp, *logged_nextp == 0)) {
655 			xfs_alert(mp,
656 		"Bad inode buffer log record (ptr = "PTR_FMT", bp = "PTR_FMT"). "
657 		"Trying to replay bad (0) inode di_next_unlinked field.",
658 				item, bp);
659 			return -EFSCORRUPTED;
660 		}
661 
662 		buffer_nextp = xfs_buf_offset(bp, next_unlinked_offset);
663 		*buffer_nextp = *logged_nextp;
664 
665 		/*
666 		 * If necessary, recalculate the CRC in the on-disk inode. We
667 		 * have to leave the inode in a consistent state for whoever
668 		 * reads it next....
669 		 */
670 		xfs_dinode_calc_crc(mp,
671 				xfs_buf_offset(bp, i * mp->m_sb.sb_inodesize));
672 
673 	}
674 
675 	return 0;
676 }
677 
678 /*
679  * V5 filesystems know the age of the buffer on disk being recovered. We can
680  * have newer objects on disk than we are replaying, and so for these cases we
681  * don't want to replay the current change as that will make the buffer contents
682  * temporarily invalid on disk.
683  *
684  * The magic number might not match the buffer type we are going to recover
685  * (e.g. reallocated blocks), so we ignore the xfs_buf_log_format flags.  Hence
686  * extract the LSN of the existing object in the buffer based on it's current
687  * magic number.  If we don't recognise the magic number in the buffer, then
688  * return a LSN of -1 so that the caller knows it was an unrecognised block and
689  * so can recover the buffer.
690  *
691  * Note: we cannot rely solely on magic number matches to determine that the
692  * buffer has a valid LSN - we also need to verify that it belongs to this
693  * filesystem, so we need to extract the object's LSN and compare it to that
694  * which we read from the superblock. If the UUIDs don't match, then we've got a
695  * stale metadata block from an old filesystem instance that we need to recover
696  * over the top of.
697  */
698 static xfs_lsn_t
699 xlog_recover_get_buf_lsn(
700 	struct xfs_mount	*mp,
701 	struct xfs_buf		*bp,
702 	struct xfs_buf_log_format *buf_f)
703 {
704 	uint32_t		magic32;
705 	uint16_t		magic16;
706 	uint16_t		magicda;
707 	void			*blk = bp->b_addr;
708 	uuid_t			*uuid;
709 	xfs_lsn_t		lsn = -1;
710 	uint16_t		blft;
711 
712 	/* v4 filesystems always recover immediately */
713 	if (!xfs_has_crc(mp))
714 		goto recover_immediately;
715 
716 	/*
717 	 * realtime bitmap and summary file blocks do not have magic numbers or
718 	 * UUIDs, so we must recover them immediately.
719 	 */
720 	blft = xfs_blft_from_flags(buf_f);
721 	if (blft == XFS_BLFT_RTBITMAP_BUF || blft == XFS_BLFT_RTSUMMARY_BUF)
722 		goto recover_immediately;
723 
724 	magic32 = be32_to_cpu(*(__be32 *)blk);
725 	switch (magic32) {
726 	case XFS_ABTB_CRC_MAGIC:
727 	case XFS_ABTC_CRC_MAGIC:
728 	case XFS_ABTB_MAGIC:
729 	case XFS_ABTC_MAGIC:
730 	case XFS_RMAP_CRC_MAGIC:
731 	case XFS_REFC_CRC_MAGIC:
732 	case XFS_FIBT_CRC_MAGIC:
733 	case XFS_FIBT_MAGIC:
734 	case XFS_IBT_CRC_MAGIC:
735 	case XFS_IBT_MAGIC: {
736 		struct xfs_btree_block *btb = blk;
737 
738 		lsn = be64_to_cpu(btb->bb_u.s.bb_lsn);
739 		uuid = &btb->bb_u.s.bb_uuid;
740 		break;
741 	}
742 	case XFS_BMAP_CRC_MAGIC:
743 	case XFS_BMAP_MAGIC: {
744 		struct xfs_btree_block *btb = blk;
745 
746 		lsn = be64_to_cpu(btb->bb_u.l.bb_lsn);
747 		uuid = &btb->bb_u.l.bb_uuid;
748 		break;
749 	}
750 	case XFS_AGF_MAGIC:
751 		lsn = be64_to_cpu(((struct xfs_agf *)blk)->agf_lsn);
752 		uuid = &((struct xfs_agf *)blk)->agf_uuid;
753 		break;
754 	case XFS_AGFL_MAGIC:
755 		lsn = be64_to_cpu(((struct xfs_agfl *)blk)->agfl_lsn);
756 		uuid = &((struct xfs_agfl *)blk)->agfl_uuid;
757 		break;
758 	case XFS_AGI_MAGIC:
759 		lsn = be64_to_cpu(((struct xfs_agi *)blk)->agi_lsn);
760 		uuid = &((struct xfs_agi *)blk)->agi_uuid;
761 		break;
762 	case XFS_SYMLINK_MAGIC:
763 		lsn = be64_to_cpu(((struct xfs_dsymlink_hdr *)blk)->sl_lsn);
764 		uuid = &((struct xfs_dsymlink_hdr *)blk)->sl_uuid;
765 		break;
766 	case XFS_DIR3_BLOCK_MAGIC:
767 	case XFS_DIR3_DATA_MAGIC:
768 	case XFS_DIR3_FREE_MAGIC:
769 		lsn = be64_to_cpu(((struct xfs_dir3_blk_hdr *)blk)->lsn);
770 		uuid = &((struct xfs_dir3_blk_hdr *)blk)->uuid;
771 		break;
772 	case XFS_ATTR3_RMT_MAGIC:
773 		/*
774 		 * Remote attr blocks are written synchronously, rather than
775 		 * being logged. That means they do not contain a valid LSN
776 		 * (i.e. transactionally ordered) in them, and hence any time we
777 		 * see a buffer to replay over the top of a remote attribute
778 		 * block we should simply do so.
779 		 */
780 		goto recover_immediately;
781 	case XFS_SB_MAGIC:
782 		/*
783 		 * superblock uuids are magic. We may or may not have a
784 		 * sb_meta_uuid on disk, but it will be set in the in-core
785 		 * superblock. We set the uuid pointer for verification
786 		 * according to the superblock feature mask to ensure we check
787 		 * the relevant UUID in the superblock.
788 		 */
789 		lsn = be64_to_cpu(((struct xfs_dsb *)blk)->sb_lsn);
790 		if (xfs_has_metauuid(mp))
791 			uuid = &((struct xfs_dsb *)blk)->sb_meta_uuid;
792 		else
793 			uuid = &((struct xfs_dsb *)blk)->sb_uuid;
794 		break;
795 	default:
796 		break;
797 	}
798 
799 	if (lsn != (xfs_lsn_t)-1) {
800 		if (!uuid_equal(&mp->m_sb.sb_meta_uuid, uuid))
801 			goto recover_immediately;
802 		return lsn;
803 	}
804 
805 	magicda = be16_to_cpu(((struct xfs_da_blkinfo *)blk)->magic);
806 	switch (magicda) {
807 	case XFS_DIR3_LEAF1_MAGIC:
808 	case XFS_DIR3_LEAFN_MAGIC:
809 	case XFS_ATTR3_LEAF_MAGIC:
810 	case XFS_DA3_NODE_MAGIC:
811 		lsn = be64_to_cpu(((struct xfs_da3_blkinfo *)blk)->lsn);
812 		uuid = &((struct xfs_da3_blkinfo *)blk)->uuid;
813 		break;
814 	default:
815 		break;
816 	}
817 
818 	if (lsn != (xfs_lsn_t)-1) {
819 		if (!uuid_equal(&mp->m_sb.sb_uuid, uuid))
820 			goto recover_immediately;
821 		return lsn;
822 	}
823 
824 	/*
825 	 * We do individual object checks on dquot and inode buffers as they
826 	 * have their own individual LSN records. Also, we could have a stale
827 	 * buffer here, so we have to at least recognise these buffer types.
828 	 *
829 	 * A notd complexity here is inode unlinked list processing - it logs
830 	 * the inode directly in the buffer, but we don't know which inodes have
831 	 * been modified, and there is no global buffer LSN. Hence we need to
832 	 * recover all inode buffer types immediately. This problem will be
833 	 * fixed by logical logging of the unlinked list modifications.
834 	 */
835 	magic16 = be16_to_cpu(*(__be16 *)blk);
836 	switch (magic16) {
837 	case XFS_DQUOT_MAGIC:
838 	case XFS_DINODE_MAGIC:
839 		goto recover_immediately;
840 	default:
841 		break;
842 	}
843 
844 	/* unknown buffer contents, recover immediately */
845 
846 recover_immediately:
847 	return (xfs_lsn_t)-1;
848 
849 }
850 
851 /*
852  * This routine replays a modification made to a buffer at runtime.
853  * There are actually two types of buffer, regular and inode, which
854  * are handled differently.  Inode buffers are handled differently
855  * in that we only recover a specific set of data from them, namely
856  * the inode di_next_unlinked fields.  This is because all other inode
857  * data is actually logged via inode records and any data we replay
858  * here which overlaps that may be stale.
859  *
860  * When meta-data buffers are freed at run time we log a buffer item
861  * with the XFS_BLF_CANCEL bit set to indicate that previous copies
862  * of the buffer in the log should not be replayed at recovery time.
863  * This is so that if the blocks covered by the buffer are reused for
864  * file data before we crash we don't end up replaying old, freed
865  * meta-data into a user's file.
866  *
867  * To handle the cancellation of buffer log items, we make two passes
868  * over the log during recovery.  During the first we build a table of
869  * those buffers which have been cancelled, and during the second we
870  * only replay those buffers which do not have corresponding cancel
871  * records in the table.  See xlog_recover_buf_pass[1,2] above
872  * for more details on the implementation of the table of cancel records.
873  */
874 STATIC int
875 xlog_recover_buf_commit_pass2(
876 	struct xlog			*log,
877 	struct list_head		*buffer_list,
878 	struct xlog_recover_item	*item,
879 	xfs_lsn_t			current_lsn)
880 {
881 	struct xfs_buf_log_format	*buf_f = item->ri_buf[0].i_addr;
882 	struct xfs_mount		*mp = log->l_mp;
883 	struct xfs_buf			*bp;
884 	int				error;
885 	uint				buf_flags;
886 	xfs_lsn_t			lsn;
887 
888 	/*
889 	 * In this pass we only want to recover all the buffers which have
890 	 * not been cancelled and are not cancellation buffers themselves.
891 	 */
892 	if (buf_f->blf_flags & XFS_BLF_CANCEL) {
893 		if (xlog_put_buffer_cancelled(log, buf_f->blf_blkno,
894 				buf_f->blf_len))
895 			goto cancelled;
896 	} else {
897 
898 		if (xlog_is_buffer_cancelled(log, buf_f->blf_blkno,
899 				buf_f->blf_len))
900 			goto cancelled;
901 	}
902 
903 	trace_xfs_log_recover_buf_recover(log, buf_f);
904 
905 	buf_flags = 0;
906 	if (buf_f->blf_flags & XFS_BLF_INODE_BUF)
907 		buf_flags |= XBF_UNMAPPED;
908 
909 	error = xfs_buf_read(mp->m_ddev_targp, buf_f->blf_blkno, buf_f->blf_len,
910 			  buf_flags, &bp, NULL);
911 	if (error)
912 		return error;
913 
914 	/*
915 	 * Recover the buffer only if we get an LSN from it and it's less than
916 	 * the lsn of the transaction we are replaying.
917 	 *
918 	 * Note that we have to be extremely careful of readahead here.
919 	 * Readahead does not attach verfiers to the buffers so if we don't
920 	 * actually do any replay after readahead because of the LSN we found
921 	 * in the buffer if more recent than that current transaction then we
922 	 * need to attach the verifier directly. Failure to do so can lead to
923 	 * future recovery actions (e.g. EFI and unlinked list recovery) can
924 	 * operate on the buffers and they won't get the verifier attached. This
925 	 * can lead to blocks on disk having the correct content but a stale
926 	 * CRC.
927 	 *
928 	 * It is safe to assume these clean buffers are currently up to date.
929 	 * If the buffer is dirtied by a later transaction being replayed, then
930 	 * the verifier will be reset to match whatever recover turns that
931 	 * buffer into.
932 	 */
933 	lsn = xlog_recover_get_buf_lsn(mp, bp, buf_f);
934 	if (lsn && lsn != -1 && XFS_LSN_CMP(lsn, current_lsn) >= 0) {
935 		trace_xfs_log_recover_buf_skip(log, buf_f);
936 		xlog_recover_validate_buf_type(mp, bp, buf_f, NULLCOMMITLSN);
937 		goto out_release;
938 	}
939 
940 	if (buf_f->blf_flags & XFS_BLF_INODE_BUF) {
941 		error = xlog_recover_do_inode_buffer(mp, item, bp, buf_f);
942 		if (error)
943 			goto out_release;
944 	} else if (buf_f->blf_flags &
945 		  (XFS_BLF_UDQUOT_BUF|XFS_BLF_PDQUOT_BUF|XFS_BLF_GDQUOT_BUF)) {
946 		bool	dirty;
947 
948 		dirty = xlog_recover_do_dquot_buffer(mp, log, item, bp, buf_f);
949 		if (!dirty)
950 			goto out_release;
951 	} else {
952 		xlog_recover_do_reg_buffer(mp, item, bp, buf_f, current_lsn);
953 	}
954 
955 	/*
956 	 * Perform delayed write on the buffer.  Asynchronous writes will be
957 	 * slower when taking into account all the buffers to be flushed.
958 	 *
959 	 * Also make sure that only inode buffers with good sizes stay in
960 	 * the buffer cache.  The kernel moves inodes in buffers of 1 block
961 	 * or inode_cluster_size bytes, whichever is bigger.  The inode
962 	 * buffers in the log can be a different size if the log was generated
963 	 * by an older kernel using unclustered inode buffers or a newer kernel
964 	 * running with a different inode cluster size.  Regardless, if
965 	 * the inode buffer size isn't max(blocksize, inode_cluster_size)
966 	 * for *our* value of inode_cluster_size, then we need to keep
967 	 * the buffer out of the buffer cache so that the buffer won't
968 	 * overlap with future reads of those inodes.
969 	 */
970 	if (XFS_DINODE_MAGIC ==
971 	    be16_to_cpu(*((__be16 *)xfs_buf_offset(bp, 0))) &&
972 	    (BBTOB(bp->b_length) != M_IGEO(log->l_mp)->inode_cluster_size)) {
973 		xfs_buf_stale(bp);
974 		error = xfs_bwrite(bp);
975 	} else {
976 		ASSERT(bp->b_mount == mp);
977 		bp->b_flags |= _XBF_LOGRECOVERY;
978 		xfs_buf_delwri_queue(bp, buffer_list);
979 	}
980 
981 out_release:
982 	xfs_buf_relse(bp);
983 	return error;
984 cancelled:
985 	trace_xfs_log_recover_buf_cancel(log, buf_f);
986 	return 0;
987 }
988 
989 const struct xlog_recover_item_ops xlog_buf_item_ops = {
990 	.item_type		= XFS_LI_BUF,
991 	.reorder		= xlog_recover_buf_reorder,
992 	.ra_pass2		= xlog_recover_buf_ra_pass2,
993 	.commit_pass1		= xlog_recover_buf_commit_pass1,
994 	.commit_pass2		= xlog_recover_buf_commit_pass2,
995 };
996