xfs_log_recover.c

   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
  34STATIC int
  35xlog_find_zeroed(
  36	struct xlog	*,
  37	xfs_daddr_t	*);
  38STATIC int
  39xlog_clear_stale_blocks(
  40	struct xlog	*,
  41	xfs_lsn_t);
  42STATIC int
  43xlog_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 */
  55static inline bool
  56xlog_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 */
  72static char *
  73xlog_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 */
 111static inline unsigned int
 112xlog_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
 119static int
 120xlog_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
 151STATIC int
 152xlog_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
 161STATIC int
 162xlog_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
 177STATIC int
 178xlog_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 */
 191STATIC void
 192xlog_header_check_dump(
 193	struct xfs_mount		*mp,
 194	struct xlog_rec_header		*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 */
 208STATIC int
 209xlog_header_check_recover(
 210	struct xfs_mount	*mp,
 211	struct xlog_rec_header	*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 */
 239STATIC int
 240xlog_header_check_mount(
 241	struct xfs_mount	*mp,
 242	struct xlog_rec_header	*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 */
 268STATIC int
 269xlog_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 */
 311STATIC int
 312xlog_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
 363out:
 364	kvfree(buffer);
 365	return error;
 366}
 367
 368static inline int
 369xlog_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 */
 393STATIC int
 394xlog_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	struct xlog_rec_header	*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 = (struct xlog_rec_header *)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
 479out:
 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 */
 497STATIC int
 498xlog_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
 694validate_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
 747out_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 */
 762STATIC int
 763xlog_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
 823out_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 */
 836STATIC int
 837xlog_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
 896out_error:
 897	return error;
 898}
 899
 900/*
 901 * Calculate distance from head to tail (i.e., unused space in the log).
 902 */
 903static inline int
 904xlog_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 */
 934STATIC int
 935xlog_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);
1001out:
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 */
1019STATIC int
1020xlog_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 */
1116static inline xfs_daddr_t
1117xlog_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 */
1132static int
1133xlog_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
1191static void
1192xlog_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 */
1234STATIC int
1235xlog_find_tail(
1236	struct xlog		*log,
1237	xfs_daddr_t		*head_blk,
1238	xfs_daddr_t		*tail_blk)
1239{
1240	struct xlog_rec_header	*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
1363done:
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 */
1387STATIC int
1388xlog_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;
1469out_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 */
1481STATIC void
1482xlog_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	struct xlog_rec_header	*recp = (struct xlog_rec_header *)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
1503STATIC int
1504xlog_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
1581out_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 */
1602STATIC int
1603xlog_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 */
1720void
1721xlog_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
1742int
1743xlog_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 */
1774int
1775xlog_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 */
1803static 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
1829static const struct xlog_recover_item_ops *
1830xlog_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 */
1891STATIC int
1892xlog_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
1960void
1961xlog_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 */
1975void
1976xlog_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
1994STATIC int
1995xlog_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 */
2024STATIC int
2025xlog_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
2075out:
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
2089STATIC void
2090xlog_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
2101STATIC int
2102xlog_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].iov_base;
2135	old_len = item->ri_buf[item->ri_cnt-1].iov_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].iov_len += len;
2142	item->ri_buf[item->ri_cnt-1].iov_base = 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 */
2160STATIC int
2161xlog_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 = kcalloc(item->ri_total, sizeof(*item->ri_buf),
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].iov_base = ptr;
2241	item->ri_buf[item->ri_cnt].iov_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 */
2252STATIC void
2253xlog_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].iov_base);
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 */
2277STATIC int
2278xlog_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 */
2340STATIC struct xlog_recover *
2341xlog_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
2384STATIC int
2385xlog_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 */
2468STATIC int
2469xlog_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. */
2512static int
2513xlog_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. */
2559static void
2560xlog_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 */
2589STATIC int
2590xlog_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;
2635err:
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 */
2645STATIC void
2646xlog_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 */
2663int
2664xlog_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 */
2681STATIC void
2682xlog_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
2713out_abort:
2714	xfs_trans_cancel(tp);
2715out_error:
2716	xfs_warn(mp, "%s: failed to clear agi %d. Continuing.", __func__,
2717			pag_agno(pag));
2718	return;
2719}
2720
2721static int
2722xlog_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 */
2803static void
2804xlog_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
2850static void
2851xlog_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
2860STATIC void
2861xlog_unpack_data(
2862	struct xlog_rec_header	*rhead,
2863	char			*dp,
2864	struct xlog		*log)
2865{
2866	int			i;
2867
2868	for (i = 0; i < BTOBB(be32_to_cpu(rhead->h_len)); i++) {
2869		*(__be32 *)dp = *xlog_cycle_data(rhead, i);
2870		dp += BBSIZE;
2871	}
2872}
2873
2874/*
2875 * CRC check, unpack and process a log record.
2876 */
2877STATIC int
2878xlog_recover_process(
2879	struct xlog		*log,
2880	struct hlist_head	rhash[],
2881	struct xlog_rec_header	*rhead,
2882	char			*dp,
2883	int			pass,
2884	struct list_head	*buffer_list)
2885{
2886	__le32			expected_crc = rhead->h_crc, crc, other_crc;
2887
2888	crc = xlog_cksum(log, rhead, dp, XLOG_REC_SIZE,
2889			be32_to_cpu(rhead->h_len));
2890
2891	/*
2892	 * Look at the end of the struct xlog_rec_header definition in
2893	 * xfs_log_format.h for the glory details.
2894	 */
2895	if (expected_crc && crc != expected_crc) {
2896		other_crc = xlog_cksum(log, rhead, dp, XLOG_REC_SIZE_OTHER,
2897				be32_to_cpu(rhead->h_len));
2898		if (other_crc == expected_crc) {
2899			xfs_notice_once(log->l_mp,
2900	"Fixing up incorrect CRC due to padding.");
2901			crc = other_crc;
2902		}
2903	}
2904
2905	/*
2906	 * Nothing else to do if this is a CRC verification pass. Just return
2907	 * if this a record with a non-zero crc. Unfortunately, mkfs always
2908	 * sets expected_crc to 0 so we must consider this valid even on v5
2909	 * supers.  Otherwise, return EFSBADCRC on failure so the callers up the
2910	 * stack know precisely what failed.
2911	 */
2912	if (pass == XLOG_RECOVER_CRCPASS) {
2913		if (expected_crc && crc != expected_crc)
2914			return -EFSBADCRC;
2915		return 0;
2916	}
2917
2918	/*
2919	 * We're in the normal recovery path. Issue a warning if and only if the
2920	 * CRC in the header is non-zero. This is an advisory warning and the
2921	 * zero CRC check prevents warnings from being emitted when upgrading
2922	 * the kernel from one that does not add CRCs by default.
2923	 */
2924	if (crc != expected_crc) {
2925		if (expected_crc || xfs_has_crc(log->l_mp)) {
2926			xfs_alert(log->l_mp,
2927		"log record CRC mismatch: found 0x%x, expected 0x%x.",
2928					le32_to_cpu(expected_crc),
2929					le32_to_cpu(crc));
2930			xfs_hex_dump(dp, 32);
2931		}
2932
2933		/*
2934		 * If the filesystem is CRC enabled, this mismatch becomes a
2935		 * fatal log corruption failure.
2936		 */
2937		if (xfs_has_crc(log->l_mp)) {
2938			XFS_ERROR_REPORT(__func__, XFS_ERRLEVEL_LOW, log->l_mp);
2939			return -EFSCORRUPTED;
2940		}
2941	}
2942
2943	xlog_unpack_data(rhead, dp, log);
2944
2945	return xlog_recover_process_data(log, rhash, rhead, dp, pass,
2946					 buffer_list);
2947}
2948
2949STATIC int
2950xlog_valid_rec_header(
2951	struct xlog		*log,
2952	struct xlog_rec_header	*rhead,
2953	xfs_daddr_t		blkno,
2954	int			bufsize)
2955{
2956	int			hlen;
2957
2958	if (XFS_IS_CORRUPT(log->l_mp,
2959			   rhead->h_magicno != cpu_to_be32(XLOG_HEADER_MAGIC_NUM)))
2960		return -EFSCORRUPTED;
2961	if (XFS_IS_CORRUPT(log->l_mp,
2962			   (!rhead->h_version ||
2963			   (be32_to_cpu(rhead->h_version) &
2964			    (~XLOG_VERSION_OKBITS))))) {
2965		xfs_warn(log->l_mp, "%s: unrecognised log version (%d).",
2966			__func__, be32_to_cpu(rhead->h_version));
2967		return -EFSCORRUPTED;
2968	}
2969
2970	/*
2971	 * LR body must have data (or it wouldn't have been written)
2972	 * and h_len must not be greater than LR buffer size.
2973	 */
2974	hlen = be32_to_cpu(rhead->h_len);
2975	if (XFS_IS_CORRUPT(log->l_mp, hlen <= 0 || hlen > bufsize))
2976		return -EFSCORRUPTED;
2977
2978	if (XFS_IS_CORRUPT(log->l_mp,
2979			   blkno > log->l_logBBsize || blkno > INT_MAX))
2980		return -EFSCORRUPTED;
2981	return 0;
2982}
2983
2984/*
2985 * Read the log from tail to head and process the log records found.
2986 * Handle the two cases where the tail and head are in the same cycle
2987 * and where the active portion of the log wraps around the end of
2988 * the physical log separately.  The pass parameter is passed through
2989 * to the routines called to process the data and is not looked at
2990 * here.
2991 */
2992STATIC int
2993xlog_do_recovery_pass(
2994	struct xlog		*log,
2995	xfs_daddr_t		head_blk,
2996	xfs_daddr_t		tail_blk,
2997	int			pass,
2998	xfs_daddr_t		*first_bad)	/* out: first bad log rec */
2999{
3000	struct xlog_rec_header	*rhead;
3001	xfs_daddr_t		blk_no, rblk_no;
3002	xfs_daddr_t		rhead_blk;
3003	char			*offset;
3004	char			*hbp, *dbp;
3005	int			error = 0, h_size, h_len;
3006	int			error2 = 0;
3007	int			bblks, split_bblks;
3008	int			hblks = 1, split_hblks, wrapped_hblks;
3009	int			i;
3010	struct hlist_head	rhash[XLOG_RHASH_SIZE];
3011	LIST_HEAD		(buffer_list);
3012
3013	ASSERT(head_blk != tail_blk);
3014	blk_no = rhead_blk = tail_blk;
3015
3016	for (i = 0; i < XLOG_RHASH_SIZE; i++)
3017		INIT_HLIST_HEAD(&rhash[i]);
3018
3019	hbp = xlog_alloc_buffer(log, hblks);
3020	if (!hbp)
3021		return -ENOMEM;
3022
3023	/*
3024	 * Read the header of the tail block and get the iclog buffer size from
3025	 * h_size.  Use this to tell how many sectors make up the log header.
3026	 */
3027	if (xfs_has_logv2(log->l_mp)) {
3028		/*
3029		 * When using variable length iclogs, read first sector of
3030		 * iclog header and extract the header size from it.  Get a
3031		 * new hbp that is the correct size.
3032		 */
3033		error = xlog_bread(log, tail_blk, 1, hbp, &offset);
3034		if (error)
3035			goto bread_err1;
3036
3037		rhead = (struct xlog_rec_header *)offset;
3038
3039		/*
3040		 * xfsprogs has a bug where record length is based on lsunit but
3041		 * h_size (iclog size) is hardcoded to 32k. Now that we
3042		 * unconditionally CRC verify the unmount record, this means the
3043		 * log buffer can be too small for the record and cause an
3044		 * overrun.
3045		 *
3046		 * Detect this condition here. Use lsunit for the buffer size as
3047		 * long as this looks like the mkfs case. Otherwise, return an
3048		 * error to avoid a buffer overrun.
3049		 */
3050		h_size = be32_to_cpu(rhead->h_size);
3051		h_len = be32_to_cpu(rhead->h_len);
3052		if (h_len > h_size && h_len <= log->l_mp->m_logbsize &&
3053		    rhead->h_num_logops == cpu_to_be32(1)) {
3054			xfs_warn(log->l_mp,
3055		"invalid iclog size (%d bytes), using lsunit (%d bytes)",
3056				 h_size, log->l_mp->m_logbsize);
3057			h_size = log->l_mp->m_logbsize;
3058		}
3059
3060		error = xlog_valid_rec_header(log, rhead, tail_blk, h_size);
3061		if (error)
3062			goto bread_err1;
3063
3064		/*
3065		 * This open codes xlog_logrec_hblks so that we can reuse the
3066		 * fixed up h_size value calculated above.  Without that we'd
3067		 * still allocate the buffer based on the incorrect on-disk
3068		 * size.
3069		 */
3070		if (h_size > XLOG_HEADER_CYCLE_SIZE &&
3071		    (rhead->h_version & cpu_to_be32(XLOG_VERSION_2))) {
3072			hblks = DIV_ROUND_UP(h_size, XLOG_HEADER_CYCLE_SIZE);
3073			if (hblks > 1) {
3074				kvfree(hbp);
3075				hbp = xlog_alloc_buffer(log, hblks);
3076				if (!hbp)
3077					return -ENOMEM;
3078			}
3079		}
3080	} else {
3081		ASSERT(log->l_sectBBsize == 1);
3082		h_size = XLOG_BIG_RECORD_BSIZE;
3083	}
3084
3085	dbp = xlog_alloc_buffer(log, BTOBB(h_size));
3086	if (!dbp) {
3087		kvfree(hbp);
3088		return -ENOMEM;
3089	}
3090
3091	memset(rhash, 0, sizeof(rhash));
3092	if (tail_blk > head_blk) {
3093		/*
3094		 * Perform recovery around the end of the physical log.
3095		 * When the head is not on the same cycle number as the tail,
3096		 * we can't do a sequential recovery.
3097		 */
3098		while (blk_no < log->l_logBBsize) {
3099			/*
3100			 * Check for header wrapping around physical end-of-log
3101			 */
3102			offset = hbp;
3103			split_hblks = 0;
3104			wrapped_hblks = 0;
3105			if (blk_no + hblks <= log->l_logBBsize) {
3106				/* Read header in one read */
3107				error = xlog_bread(log, blk_no, hblks, hbp,
3108						   &offset);
3109				if (error)
3110					goto bread_err2;
3111			} else {
3112				/* This LR is split across physical log end */
3113				if (blk_no != log->l_logBBsize) {
3114					/* some data before physical log end */
3115					ASSERT(blk_no <= INT_MAX);
3116					split_hblks = log->l_logBBsize - (int)blk_no;
3117					ASSERT(split_hblks > 0);
3118					error = xlog_bread(log, blk_no,
3119							   split_hblks, hbp,
3120							   &offset);
3121					if (error)
3122						goto bread_err2;
3123				}
3124
3125				/*
3126				 * Note: this black magic still works with
3127				 * large sector sizes (non-512) only because:
3128				 * - we increased the buffer size originally
3129				 *   by 1 sector giving us enough extra space
3130				 *   for the second read;
3131				 * - the log start is guaranteed to be sector
3132				 *   aligned;
3133				 * - we read the log end (LR header start)
3134				 *   _first_, then the log start (LR header end)
3135				 *   - order is important.
3136				 */
3137				wrapped_hblks = hblks - split_hblks;
3138				error = xlog_bread_noalign(log, 0,
3139						wrapped_hblks,
3140						offset + BBTOB(split_hblks));
3141				if (error)
3142					goto bread_err2;
3143			}
3144			rhead = (struct xlog_rec_header *)offset;
3145			error = xlog_valid_rec_header(log, rhead,
3146					split_hblks ? blk_no : 0, h_size);
3147			if (error)
3148				goto bread_err2;
3149
3150			bblks = (int)BTOBB(be32_to_cpu(rhead->h_len));
3151			blk_no += hblks;
3152
3153			/*
3154			 * Read the log record data in multiple reads if it
3155			 * wraps around the end of the log. Note that if the
3156			 * header already wrapped, blk_no could point past the
3157			 * end of the log. The record data is contiguous in
3158			 * that case.
3159			 */
3160			if (blk_no + bblks <= log->l_logBBsize ||
3161			    blk_no >= log->l_logBBsize) {
3162				rblk_no = xlog_wrap_logbno(log, blk_no);
3163				error = xlog_bread(log, rblk_no, bblks, dbp,
3164						   &offset);
3165				if (error)
3166					goto bread_err2;
3167			} else {
3168				/* This log record is split across the
3169				 * physical end of log */
3170				offset = dbp;
3171				split_bblks = 0;
3172				if (blk_no != log->l_logBBsize) {
3173					/* some data is before the physical
3174					 * end of log */
3175					ASSERT(!wrapped_hblks);
3176					ASSERT(blk_no <= INT_MAX);
3177					split_bblks =
3178						log->l_logBBsize - (int)blk_no;
3179					ASSERT(split_bblks > 0);
3180					error = xlog_bread(log, blk_no,
3181							split_bblks, dbp,
3182							&offset);
3183					if (error)
3184						goto bread_err2;
3185				}
3186
3187				/*
3188				 * Note: this black magic still works with
3189				 * large sector sizes (non-512) only because:
3190				 * - we increased the buffer size originally
3191				 *   by 1 sector giving us enough extra space
3192				 *   for the second read;
3193				 * - the log start is guaranteed to be sector
3194				 *   aligned;
3195				 * - we read the log end (LR header start)
3196				 *   _first_, then the log start (LR header end)
3197				 *   - order is important.
3198				 */
3199				error = xlog_bread_noalign(log, 0,
3200						bblks - split_bblks,
3201						offset + BBTOB(split_bblks));
3202				if (error)
3203					goto bread_err2;
3204			}
3205
3206			error = xlog_recover_process(log, rhash, rhead, offset,
3207						     pass, &buffer_list);
3208			if (error)
3209				goto bread_err2;
3210
3211			blk_no += bblks;
3212			rhead_blk = blk_no;
3213		}
3214
3215		ASSERT(blk_no >= log->l_logBBsize);
3216		blk_no -= log->l_logBBsize;
3217		rhead_blk = blk_no;
3218	}
3219
3220	/* read first part of physical log */
3221	while (blk_no < head_blk) {
3222		error = xlog_bread(log, blk_no, hblks, hbp, &offset);
3223		if (error)
3224			goto bread_err2;
3225
3226		rhead = (struct xlog_rec_header *)offset;
3227		error = xlog_valid_rec_header(log, rhead, blk_no, h_size);
3228		if (error)
3229			goto bread_err2;
3230
3231		/* blocks in data section */
3232		bblks = (int)BTOBB(be32_to_cpu(rhead->h_len));
3233		error = xlog_bread(log, blk_no+hblks, bblks, dbp,
3234				   &offset);
3235		if (error)
3236			goto bread_err2;
3237
3238		error = xlog_recover_process(log, rhash, rhead, offset, pass,
3239					     &buffer_list);
3240		if (error)
3241			goto bread_err2;
3242
3243		blk_no += bblks + hblks;
3244		rhead_blk = blk_no;
3245	}
3246
3247 bread_err2:
3248	kvfree(dbp);
3249 bread_err1:
3250	kvfree(hbp);
3251
3252	/*
3253	 * Submit buffers that have been dirtied by the last record recovered.
3254	 */
3255	if (!list_empty(&buffer_list)) {
3256		if (error) {
3257			/*
3258			 * If there has been an item recovery error then we
3259			 * cannot allow partial checkpoint writeback to
3260			 * occur.  We might have multiple checkpoints with the
3261			 * same start LSN in this buffer list, and partial
3262			 * writeback of a checkpoint in this situation can
3263			 * prevent future recovery of all the changes in the
3264			 * checkpoints at this start LSN.
3265			 *
3266			 * Note: Shutting down the filesystem will result in the
3267			 * delwri submission marking all the buffers stale,
3268			 * completing them and cleaning up _XBF_LOGRECOVERY
3269			 * state without doing any IO.
3270			 */
3271			xlog_force_shutdown(log, SHUTDOWN_LOG_IO_ERROR);
3272		}
3273		error2 = xfs_buf_delwri_submit(&buffer_list);
3274	}
3275
3276	if (error && first_bad)
3277		*first_bad = rhead_blk;
3278
3279	/*
3280	 * Transactions are freed at commit time but transactions without commit
3281	 * records on disk are never committed. Free any that may be left in the
3282	 * hash table.
3283	 */
3284	for (i = 0; i < XLOG_RHASH_SIZE; i++) {
3285		struct hlist_node	*tmp;
3286		struct xlog_recover	*trans;
3287
3288		hlist_for_each_entry_safe(trans, tmp, &rhash[i], r_list)
3289			xlog_recover_free_trans(trans);
3290	}
3291
3292	return error ? error : error2;
3293}
3294
3295/*
3296 * Do the recovery of the log.  We actually do this in two phases.
3297 * The two passes are necessary in order to implement the function
3298 * of cancelling a record written into the log.  The first pass
3299 * determines those things which have been cancelled, and the
3300 * second pass replays log items normally except for those which
3301 * have been cancelled.  The handling of the replay and cancellations
3302 * takes place in the log item type specific routines.
3303 *
3304 * The table of items which have cancel records in the log is allocated
3305 * and freed at this level, since only here do we know when all of
3306 * the log recovery has been completed.
3307 */
3308STATIC int
3309xlog_do_log_recovery(
3310	struct xlog	*log,
3311	xfs_daddr_t	head_blk,
3312	xfs_daddr_t	tail_blk)
3313{
3314	int		error;
3315
3316	ASSERT(head_blk != tail_blk);
3317
3318	/*
3319	 * First do a pass to find all of the cancelled buf log items.
3320	 * Store them in the buf_cancel_table for use in the second pass.
3321	 */
3322	error = xlog_alloc_buf_cancel_table(log);
3323	if (error)
3324		return error;
3325
3326	error = xlog_do_recovery_pass(log, head_blk, tail_blk,
3327				      XLOG_RECOVER_PASS1, NULL);
3328	if (error != 0)
3329		goto out_cancel;
3330
3331	/*
3332	 * Then do a second pass to actually recover the items in the log.
3333	 * When it is complete free the table of buf cancel items.
3334	 */
3335	error = xlog_do_recovery_pass(log, head_blk, tail_blk,
3336				      XLOG_RECOVER_PASS2, NULL);
3337	if (!error)
3338		xlog_check_buf_cancel_table(log);
3339out_cancel:
3340	xlog_free_buf_cancel_table(log);
3341	return error;
3342}
3343
3344/*
3345 * Do the actual recovery
3346 */
3347STATIC int
3348xlog_do_recover(
3349	struct xlog		*log,
3350	xfs_daddr_t		head_blk,
3351	xfs_daddr_t		tail_blk)
3352{
3353	struct xfs_mount	*mp = log->l_mp;
3354	struct xfs_buf		*bp = mp->m_sb_bp;
3355	struct xfs_sb		*sbp = &mp->m_sb;
3356	int			error;
3357
3358	trace_xfs_log_recover(log, head_blk, tail_blk);
3359
3360	/*
3361	 * First replay the images in the log.
3362	 */
3363	error = xlog_do_log_recovery(log, head_blk, tail_blk);
3364	if (error)
3365		return error;
3366
3367	if (xlog_is_shutdown(log))
3368		return -EIO;
3369
3370	/*
3371	 * We now update the tail_lsn since much of the recovery has completed
3372	 * and there may be space available to use.  If there were no extent or
3373	 * iunlinks, we can free up the entire log.  This was set in
3374	 * xlog_find_tail to be the lsn of the last known good LR on disk.  If
3375	 * there are extent frees or iunlinks they will have some entries in the
3376	 * AIL; so we look at the AIL to determine how to set the tail_lsn.
3377	 */
3378	xfs_ail_assign_tail_lsn(log->l_ailp);
3379
3380	/*
3381	 * Now that we've finished replaying all buffer and inode updates,
3382	 * re-read the superblock and reverify it.
3383	 */
3384	xfs_buf_lock(bp);
3385	xfs_buf_hold(bp);
3386	error = _xfs_buf_read(bp);
3387	if (error) {
3388		if (!xlog_is_shutdown(log)) {
3389			xfs_buf_ioerror_alert(bp, __this_address);
3390			ASSERT(0);
3391		}
3392		xfs_buf_relse(bp);
3393		return error;
3394	}
3395
3396	/* Convert superblock from on-disk format */
3397	xfs_sb_from_disk(sbp, bp->b_addr);
3398	xfs_buf_relse(bp);
3399
3400	/* re-initialise in-core superblock and geometry structures */
3401	mp->m_features |= xfs_sb_version_to_features(sbp);
3402	xfs_reinit_percpu_counters(mp);
3403
3404	/* Normal transactions can now occur */
3405	clear_bit(XLOG_ACTIVE_RECOVERY, &log->l_opstate);
3406	return 0;
3407}
3408
3409/*
3410 * Perform recovery and re-initialize some log variables in xlog_find_tail.
3411 *
3412 * Return error or zero.
3413 */
3414int
3415xlog_recover(
3416	struct xlog	*log)
3417{
3418	xfs_daddr_t	head_blk, tail_blk;
3419	int		error;
3420
3421	/* find the tail of the log */
3422	error = xlog_find_tail(log, &head_blk, &tail_blk);
3423	if (error)
3424		return error;
3425
3426	/*
3427	 * The superblock was read before the log was available and thus the LSN
3428	 * could not be verified. Check the superblock LSN against the current
3429	 * LSN now that it's known.
3430	 */
3431	if (xfs_has_crc(log->l_mp) &&
3432	    !xfs_log_check_lsn(log->l_mp, log->l_mp->m_sb.sb_lsn))
3433		return -EINVAL;
3434
3435	if (tail_blk != head_blk) {
3436		/* There used to be a comment here:
3437		 *
3438		 * disallow recovery on read-only mounts.  note -- mount
3439		 * checks for ENOSPC and turns it into an intelligent
3440		 * error message.
3441		 * ...but this is no longer true.  Now, unless you specify
3442		 * NORECOVERY (in which case this function would never be
3443		 * called), we just go ahead and recover.  We do this all
3444		 * under the vfs layer, so we can get away with it unless
3445		 * the device itself is read-only, in which case we fail.
3446		 */
3447		if ((error = xfs_dev_is_read_only(log->l_mp, "recovery"))) {
3448			return error;
3449		}
3450
3451		/*
3452		 * Version 5 superblock log feature mask validation. We know the
3453		 * log is dirty so check if there are any unknown log features
3454		 * in what we need to recover. If there are unknown features
3455		 * (e.g. unsupported transactions, then simply reject the
3456		 * attempt at recovery before touching anything.
3457		 */
3458		if (xfs_sb_is_v5(&log->l_mp->m_sb) &&
3459		    xfs_sb_has_incompat_log_feature(&log->l_mp->m_sb,
3460					XFS_SB_FEAT_INCOMPAT_LOG_UNKNOWN)) {
3461			xfs_warn(log->l_mp,
3462"Superblock has unknown incompatible log features (0x%x) enabled.",
3463				(log->l_mp->m_sb.sb_features_log_incompat &
3464					XFS_SB_FEAT_INCOMPAT_LOG_UNKNOWN));
3465			xfs_warn(log->l_mp,
3466"The log can not be fully and/or safely recovered by this kernel.");
3467			xfs_warn(log->l_mp,
3468"Please recover the log on a kernel that supports the unknown features.");
3469			return -EINVAL;
3470		}
3471
3472		/*
3473		 * Delay log recovery if the debug hook is set. This is debug
3474		 * instrumentation to coordinate simulation of I/O failures with
3475		 * log recovery.
3476		 */
3477		if (xfs_globals.log_recovery_delay) {
3478			xfs_notice(log->l_mp,
3479				"Delaying log recovery for %d seconds.",
3480				xfs_globals.log_recovery_delay);
3481			msleep(xfs_globals.log_recovery_delay * 1000);
3482		}
3483
3484		xfs_notice(log->l_mp, "Starting recovery (logdev: %s)",
3485				log->l_mp->m_logname ? log->l_mp->m_logname
3486						     : "internal");
3487
3488		error = xlog_do_recover(log, head_blk, tail_blk);
3489		set_bit(XLOG_RECOVERY_NEEDED, &log->l_opstate);
3490	}
3491	return error;
3492}
3493
3494/*
3495 * In the first part of recovery we replay inodes and buffers and build up the
3496 * list of intents which need to be processed. Here we process the intents and
3497 * clean up the on disk unlinked inode lists. This is separated from the first
3498 * part of recovery so that the root and real-time bitmap inodes can be read in
3499 * from disk in between the two stages.  This is necessary so that we can free
3500 * space in the real-time portion of the file system.
3501 *
3502 * We run this whole process under GFP_NOFS allocation context. We do a
3503 * combination of non-transactional and transactional work, yet we really don't
3504 * want to recurse into the filesystem from direct reclaim during any of this
3505 * processing. This allows all the recovery code run here not to care about the
3506 * memory allocation context it is running in.
3507 */
3508int
3509xlog_recover_finish(
3510	struct xlog	*log)
3511{
3512	unsigned int	nofs_flags = memalloc_nofs_save();
3513	int		error;
3514
3515	error = xlog_recover_process_intents(log);
3516	if (error) {
3517		/*
3518		 * Cancel all the unprocessed intent items now so that we don't
3519		 * leave them pinned in the AIL.  This can cause the AIL to
3520		 * livelock on the pinned item if anyone tries to push the AIL
3521		 * (inode reclaim does this) before we get around to
3522		 * xfs_log_mount_cancel.
3523		 */
3524		xlog_recover_cancel_intents(log);
3525		xfs_alert(log->l_mp, "Failed to recover intents");
3526		xlog_force_shutdown(log, SHUTDOWN_LOG_IO_ERROR);
3527		goto out_error;
3528	}
3529
3530	/*
3531	 * Sync the log to get all the intents out of the AIL.  This isn't
3532	 * absolutely necessary, but it helps in case the unlink transactions
3533	 * would have problems pushing the intents out of the way.
3534	 */
3535	xfs_log_force(log->l_mp, XFS_LOG_SYNC);
3536
3537	xlog_recover_process_iunlinks(log);
3538
3539	/*
3540	 * Recover any CoW staging blocks that are still referenced by the
3541	 * ondisk refcount metadata.  During mount there cannot be any live
3542	 * staging extents as we have not permitted any user modifications.
3543	 * Therefore, it is safe to free them all right now, even on a
3544	 * read-only mount.
3545	 */
3546	error = xfs_reflink_recover_cow(log->l_mp);
3547	if (error) {
3548		xfs_alert(log->l_mp,
3549	"Failed to recover leftover CoW staging extents, err %d.",
3550				error);
3551		/*
3552		 * If we get an error here, make sure the log is shut down
3553		 * but return zero so that any log items committed since the
3554		 * end of intents processing can be pushed through the CIL
3555		 * and AIL.
3556		 */
3557		xlog_force_shutdown(log, SHUTDOWN_LOG_IO_ERROR);
3558		error = 0;
3559		goto out_error;
3560	}
3561
3562out_error:
3563	memalloc_nofs_restore(nofs_flags);
3564	return error;
3565}
3566
3567void
3568xlog_recover_cancel(
3569	struct xlog	*log)
3570{
3571	if (xlog_recovery_needed(log))
3572		xlog_recover_cancel_intents(log);
3573}
3574