xfs/scrub/agheader.c

// SPDX-License-Identifier: GPL-2.0-or-later
/*
 * Copyright (C) 2017-2023 Oracle.  All Rights Reserved.
 * Author: Darrick J. Wong <djwong@kernel.org>
 */
#include "xfs.h"
#include "xfs_fs.h"
#include "xfs_shared.h"
#include "xfs_format.h"
#include "xfs_trans_resv.h"
#include "xfs_mount.h"
#include "xfs_btree.h"
#include "xfs_sb.h"
#include "xfs_alloc.h"
#include "xfs_ialloc.h"
#include "xfs_rmap.h"
#include "xfs_ag.h"
#include "xfs_inode.h"
#include "scrub/scrub.h"
#include "scrub/common.h"

int
xchk_setup_agheader(
	struct xfs_scrub	*sc)
{
	if (xchk_need_intent_drain(sc))
		xchk_fsgates_enable(sc, XCHK_FSGATES_DRAIN);
	return xchk_setup_fs(sc);
}

/* Superblock */

/* Cross-reference with the other btrees. */
STATIC void
xchk_superblock_xref(
	struct xfs_scrub	*sc,
	struct xfs_buf		*bp)
{
	struct xfs_mount	*mp = sc->mp;
	xfs_agnumber_t		agno = sc->sm->sm_agno;
	xfs_agblock_t		agbno;
	int			error;

	if (sc->sm->sm_flags & XFS_SCRUB_OFLAG_CORRUPT)
		return;

	agbno = XFS_SB_BLOCK(mp);

	error = xchk_ag_init_existing(sc, agno, &sc->sa);
	if (!xchk_xref_process_error(sc, agno, agbno, &error))
		return;

	xchk_xref_is_used_space(sc, agbno, 1);
	xchk_xref_is_not_inode_chunk(sc, agbno, 1);
	xchk_xref_is_only_owned_by(sc, agbno, 1, &XFS_RMAP_OINFO_FS);
	xchk_xref_is_not_shared(sc, agbno, 1);
	xchk_xref_is_not_cow_staging(sc, agbno, 1);

	/* scrub teardown will take care of sc->sa for us */
}

/*
 * Calculate the ondisk superblock size in bytes given the feature set of the
 * mounted filesystem (aka the primary sb).  This is subtlely different from
 * the logic in xfs_repair, which computes the size of a secondary sb given the
 * featureset listed in the secondary sb.
 */
STATIC size_t
xchk_superblock_ondisk_size(
	struct xfs_mount	*mp)
{
	if (xfs_has_zoned(mp))
		return offsetofend(struct xfs_dsb, sb_rtreserved);
	if (xfs_has_metadir(mp))
		return offsetofend(struct xfs_dsb, sb_pad);
	if (xfs_has_metauuid(mp))
		return offsetofend(struct xfs_dsb, sb_meta_uuid);
	if (xfs_has_crc(mp))
		return offsetofend(struct xfs_dsb, sb_lsn);
	if (xfs_sb_version_hasmorebits(&mp->m_sb))
		return offsetofend(struct xfs_dsb, sb_bad_features2);
	if (xfs_has_logv2(mp))
		return offsetofend(struct xfs_dsb, sb_logsunit);
	if (xfs_has_sector(mp))
		return offsetofend(struct xfs_dsb, sb_logsectsize);
	/* only support dirv2 or more recent */
	return offsetofend(struct xfs_dsb, sb_dirblklog);
}

/*
 * Scrub the filesystem superblock.
 *
 * Note: We do /not/ attempt to check AG 0's superblock.  Mount is
 * responsible for validating all the geometry information in sb 0, so
 * if the filesystem is capable of initiating online scrub, then clearly
 * sb 0 is ok and we can use its information to check everything else.
 */
int
xchk_superblock(
	struct xfs_scrub	*sc)
{
	struct xfs_mount	*mp = sc->mp;
	struct xfs_buf		*bp;
	struct xfs_dsb		*sb;
	struct xfs_perag	*pag;
	size_t			sblen;
	xfs_agnumber_t		agno;
	uint32_t		v2_ok;
	__be32			features_mask;
	int			error;
	__be16			vernum_mask;

	agno = sc->sm->sm_agno;
	if (agno == 0)
		return 0;

	/*
	 * Grab an active reference to the perag structure.  If we can't get
	 * it, we're racing with something that's tearing down the AG, so
	 * signal that the AG no longer exists.
	 */
	pag = xfs_perag_get(mp, agno);
	if (!pag)
		return -ENOENT;

	error = xfs_sb_read_secondary(mp, sc->tp, agno, &bp);
	/*
	 * The superblock verifier can return several different error codes
	 * if it thinks the superblock doesn't look right.  For a mount these
	 * would all get bounced back to userspace, but if we're here then the
	 * fs mounted successfully, which means that this secondary superblock
	 * is simply incorrect.  Treat all these codes the same way we treat
	 * any corruption.
	 */
	switch (error) {
	case -EINVAL:	/* also -EWRONGFS */
	case -ENOSYS:
	case -EFBIG:
		error = -EFSCORRUPTED;
		fallthrough;
	default:
		break;
	}
	if (!xchk_process_error(sc, agno, XFS_SB_BLOCK(mp), &error))
		goto out_pag;

	sb = bp->b_addr;

	/*
	 * Verify the geometries match.  Fields that are permanently
	 * set by mkfs are checked; fields that can be updated later
	 * (and are not propagated to backup superblocks) are preen
	 * checked.
	 */
	if (sb->sb_blocksize != cpu_to_be32(mp->m_sb.sb_blocksize))
		xchk_block_set_corrupt(sc, bp);

	if (sb->sb_dblocks != cpu_to_be64(mp->m_sb.sb_dblocks))
		xchk_block_set_corrupt(sc, bp);

	if (sb->sb_rblocks != cpu_to_be64(mp->m_sb.sb_rblocks))
		xchk_block_set_corrupt(sc, bp);

	if (sb->sb_rextents != cpu_to_be64(mp->m_sb.sb_rextents))
		xchk_block_set_corrupt(sc, bp);

	if (!uuid_equal(&sb->sb_uuid, &mp->m_sb.sb_uuid))
		xchk_block_set_preen(sc, bp);

	if (sb->sb_logstart != cpu_to_be64(mp->m_sb.sb_logstart))
		xchk_block_set_corrupt(sc, bp);

	if (sb->sb_rootino != cpu_to_be64(mp->m_sb.sb_rootino))
		xchk_block_set_preen(sc, bp);

	if (xfs_has_metadir(sc->mp)) {
		if (sb->sb_rbmino != cpu_to_be64(0))
			xchk_block_set_corrupt(sc, bp);

		if (sb->sb_rsumino != cpu_to_be64(0))
			xchk_block_set_corrupt(sc, bp);
	} else {
		if (sb->sb_rbmino != cpu_to_be64(mp->m_sb.sb_rbmino))
			xchk_block_set_preen(sc, bp);

		if (sb->sb_rsumino != cpu_to_be64(mp->m_sb.sb_rsumino))
			xchk_block_set_preen(sc, bp);
	}

	if (sb->sb_rextsize != cpu_to_be32(mp->m_sb.sb_rextsize))
		xchk_block_set_corrupt(sc, bp);

	if (sb->sb_agblocks != cpu_to_be32(mp->m_sb.sb_agblocks))
		xchk_block_set_corrupt(sc, bp);

	if (sb->sb_agcount != cpu_to_be32(mp->m_sb.sb_agcount))
		xchk_block_set_corrupt(sc, bp);

	if (sb->sb_rbmblocks != cpu_to_be32(mp->m_sb.sb_rbmblocks))
		xchk_block_set_corrupt(sc, bp);

	if (sb->sb_logblocks != cpu_to_be32(mp->m_sb.sb_logblocks))
		xchk_block_set_corrupt(sc, bp);

	/* Check sb_versionnum bits that are set at mkfs time. */
	vernum_mask = cpu_to_be16(XFS_SB_VERSION_NUMBITS |
				  XFS_SB_VERSION_ALIGNBIT |
				  XFS_SB_VERSION_DALIGNBIT |
				  XFS_SB_VERSION_SHAREDBIT |
				  XFS_SB_VERSION_LOGV2BIT |
				  XFS_SB_VERSION_SECTORBIT |
				  XFS_SB_VERSION_EXTFLGBIT |
				  XFS_SB_VERSION_DIRV2BIT);
	if ((sb->sb_versionnum & vernum_mask) !=
	    (cpu_to_be16(mp->m_sb.sb_versionnum) & vernum_mask))
		xchk_block_set_corrupt(sc, bp);

	/* Check sb_versionnum bits that can be set after mkfs time. */
	vernum_mask = cpu_to_be16(XFS_SB_VERSION_ATTRBIT |
				  XFS_SB_VERSION_NLINKBIT |
				  XFS_SB_VERSION_QUOTABIT);
	if ((sb->sb_versionnum & vernum_mask) !=
	    (cpu_to_be16(mp->m_sb.sb_versionnum) & vernum_mask))
		xchk_block_set_preen(sc, bp);

	if (sb->sb_sectsize != cpu_to_be16(mp->m_sb.sb_sectsize))
		xchk_block_set_corrupt(sc, bp);

	if (sb->sb_inodesize != cpu_to_be16(mp->m_sb.sb_inodesize))
		xchk_block_set_corrupt(sc, bp);

	if (sb->sb_inopblock != cpu_to_be16(mp->m_sb.sb_inopblock))
		xchk_block_set_corrupt(sc, bp);

	if (memcmp(sb->sb_fname, mp->m_sb.sb_fname, sizeof(sb->sb_fname)))
		xchk_block_set_preen(sc, bp);

	if (sb->sb_blocklog != mp->m_sb.sb_blocklog)
		xchk_block_set_corrupt(sc, bp);

	if (sb->sb_sectlog != mp->m_sb.sb_sectlog)
		xchk_block_set_corrupt(sc, bp);

	if (sb->sb_inodelog != mp->m_sb.sb_inodelog)
		xchk_block_set_corrupt(sc, bp);

	if (sb->sb_inopblog != mp->m_sb.sb_inopblog)
		xchk_block_set_corrupt(sc, bp);

	if (sb->sb_agblklog != mp->m_sb.sb_agblklog)
		xchk_block_set_corrupt(sc, bp);

	if (sb->sb_rextslog != mp->m_sb.sb_rextslog)
		xchk_block_set_corrupt(sc, bp);

	if (sb->sb_imax_pct != mp->m_sb.sb_imax_pct)
		xchk_block_set_preen(sc, bp);

	/*
	 * Skip the summary counters since we track them in memory anyway.
	 * sb_icount, sb_ifree, sb_fdblocks, sb_frexents
	 */

	if (xfs_has_metadir(mp)) {
		if (sb->sb_uquotino != cpu_to_be64(0))
			xchk_block_set_corrupt(sc, bp);

		if (sb->sb_gquotino != cpu_to_be64(0))
			xchk_block_set_preen(sc, bp);
	} else {
		if (sb->sb_uquotino != cpu_to_be64(mp->m_sb.sb_uquotino))
			xchk_block_set_preen(sc, bp);

		if (sb->sb_gquotino != cpu_to_be64(mp->m_sb.sb_gquotino))
			xchk_block_set_preen(sc, bp);
	}

	/*
	 * Skip the quota flags since repair will force quotacheck.
	 * sb_qflags
	 */

	if (sb->sb_flags != mp->m_sb.sb_flags)
		xchk_block_set_corrupt(sc, bp);

	if (sb->sb_shared_vn != mp->m_sb.sb_shared_vn)
		xchk_block_set_corrupt(sc, bp);

	if (sb->sb_inoalignmt != cpu_to_be32(mp->m_sb.sb_inoalignmt))
		xchk_block_set_corrupt(sc, bp);

	if (sb->sb_unit != cpu_to_be32(mp->m_sb.sb_unit))
		xchk_block_set_preen(sc, bp);

	if (sb->sb_width != cpu_to_be32(mp->m_sb.sb_width))
		xchk_block_set_preen(sc, bp);

	if (sb->sb_dirblklog != mp->m_sb.sb_dirblklog)
		xchk_block_set_corrupt(sc, bp);

	if (sb->sb_logsectlog != mp->m_sb.sb_logsectlog)
		xchk_block_set_corrupt(sc, bp);

	if (sb->sb_logsectsize != cpu_to_be16(mp->m_sb.sb_logsectsize))
		xchk_block_set_corrupt(sc, bp);

	if (sb->sb_logsunit != cpu_to_be32(mp->m_sb.sb_logsunit))
		xchk_block_set_corrupt(sc, bp);

	/* Do we see any invalid bits in sb_features2? */
	if (!xfs_sb_version_hasmorebits(&mp->m_sb)) {
		if (sb->sb_features2 != 0)
			xchk_block_set_corrupt(sc, bp);
	} else {
		v2_ok = XFS_SB_VERSION2_OKBITS;
		if (xfs_sb_is_v5(&mp->m_sb))
			v2_ok |= XFS_SB_VERSION2_CRCBIT;

		if (!!(sb->sb_features2 & cpu_to_be32(~v2_ok)))
			xchk_block_set_corrupt(sc, bp);

		if (sb->sb_features2 != sb->sb_bad_features2)
			xchk_block_set_preen(sc, bp);
	}

	/* Check sb_features2 flags that are set at mkfs time. */
	features_mask = cpu_to_be32(XFS_SB_VERSION2_LAZYSBCOUNTBIT |
				    XFS_SB_VERSION2_PROJID32BIT |
				    XFS_SB_VERSION2_CRCBIT |
				    XFS_SB_VERSION2_FTYPE);
	if ((sb->sb_features2 & features_mask) !=
	    (cpu_to_be32(mp->m_sb.sb_features2) & features_mask))
		xchk_block_set_corrupt(sc, bp);

	/* Check sb_features2 flags that can be set after mkfs time. */
	features_mask = cpu_to_be32(XFS_SB_VERSION2_ATTR2BIT);
	if ((sb->sb_features2 & features_mask) !=
	    (cpu_to_be32(mp->m_sb.sb_features2) & features_mask))
		xchk_block_set_preen(sc, bp);

	if (!xfs_has_crc(mp)) {
		/* all v5 fields must be zero */
		if (memchr_inv(&sb->sb_features_compat, 0,
				sizeof(struct xfs_dsb) -
				offsetof(struct xfs_dsb, sb_features_compat)))
			xchk_block_set_corrupt(sc, bp);
	} else {
		/* compat features must match */
		if (sb->sb_features_compat !=
				cpu_to_be32(mp->m_sb.sb_features_compat))
			xchk_block_set_corrupt(sc, bp);

		/* ro compat features must match */
		if (sb->sb_features_ro_compat !=
				cpu_to_be32(mp->m_sb.sb_features_ro_compat))
			xchk_block_set_corrupt(sc, bp);

		/*
		 * NEEDSREPAIR is ignored on a secondary super, so we should
		 * clear it when we find it, though it's not a corruption.
		 */
		features_mask = cpu_to_be32(XFS_SB_FEAT_INCOMPAT_NEEDSREPAIR);
		if ((cpu_to_be32(mp->m_sb.sb_features_incompat) ^
				sb->sb_features_incompat) & features_mask)
			xchk_block_set_preen(sc, bp);

		/* all other incompat features must match */
		if ((cpu_to_be32(mp->m_sb.sb_features_incompat) ^
				sb->sb_features_incompat) & ~features_mask)
			xchk_block_set_corrupt(sc, bp);

		/*
		 * log incompat features protect newer log record types from
		 * older log recovery code.  Log recovery doesn't check the
		 * secondary supers, so we can clear these if needed.
		 */
		if (sb->sb_features_log_incompat)
			xchk_block_set_preen(sc, bp);

		/* Don't care about sb_crc */

		if (sb->sb_spino_align != cpu_to_be32(mp->m_sb.sb_spino_align))
			xchk_block_set_corrupt(sc, bp);

		if (xfs_has_metadir(mp)) {
			if (sb->sb_pquotino != cpu_to_be64(0))
				xchk_block_set_corrupt(sc, bp);
		} else {
			if (sb->sb_pquotino != cpu_to_be64(mp->m_sb.sb_pquotino))
				xchk_block_set_preen(sc, bp);
		}

		/* Don't care about sb_lsn */
	}

	if (xfs_has_metauuid(mp)) {
		/* The metadata UUID must be the same for all supers */
		if (!uuid_equal(&sb->sb_meta_uuid, &mp->m_sb.sb_meta_uuid))
			xchk_block_set_corrupt(sc, bp);
	}

	if (xfs_has_metadir(mp)) {
		if (sb->sb_metadirino != cpu_to_be64(mp->m_sb.sb_metadirino))
			xchk_block_set_preen(sc, bp);

		if (sb->sb_rgcount != cpu_to_be32(mp->m_sb.sb_rgcount))
			xchk_block_set_corrupt(sc, bp);

		if (sb->sb_rgextents != cpu_to_be32(mp->m_sb.sb_rgextents))
			xchk_block_set_corrupt(sc, bp);

		if (sb->sb_rgblklog != mp->m_sb.sb_rgblklog)
			xchk_block_set_corrupt(sc, bp);

		if (memchr_inv(sb->sb_pad, 0, sizeof(sb->sb_pad)))
			xchk_block_set_corrupt(sc, bp);
	}

	/* Everything else must be zero. */
	sblen = xchk_superblock_ondisk_size(mp);
	if (memchr_inv((char *)sb + sblen, 0, BBTOB(bp->b_length) - sblen))
		xchk_block_set_corrupt(sc, bp);

	xchk_superblock_xref(sc, bp);
out_pag:
	xfs_perag_put(pag);
	return error;
}

/* AGF */

/* Tally freespace record lengths. */
STATIC int
xchk_agf_record_bno_lengths(
	struct xfs_btree_cur		*cur,
	const struct xfs_alloc_rec_incore *rec,
	void				*priv)
{
	xfs_extlen_t			*blocks = priv;

	(*blocks) += rec->ar_blockcount;
	return 0;
}

/* Check agf_freeblks */
static inline void
xchk_agf_xref_freeblks(
	struct xfs_scrub	*sc)
{
	struct xfs_agf		*agf = sc->sa.agf_bp->b_addr;
	xfs_extlen_t		blocks = 0;
	int			error;

	if (!sc->sa.bno_cur)
		return;

	error = xfs_alloc_query_all(sc->sa.bno_cur,
			xchk_agf_record_bno_lengths, &blocks);
	if (!xchk_should_check_xref(sc, &error, &sc->sa.bno_cur))
		return;
	if (blocks != be32_to_cpu(agf->agf_freeblks))
		xchk_block_xref_set_corrupt(sc, sc->sa.agf_bp);
}

/* Cross reference the AGF with the cntbt (freespace by length btree) */
static inline void
xchk_agf_xref_cntbt(
	struct xfs_scrub	*sc)
{
	struct xfs_agf		*agf = sc->sa.agf_bp->b_addr;
	xfs_agblock_t		agbno;
	xfs_extlen_t		blocks;
	int			have;
	int			error;

	if (!sc->sa.cnt_cur)
		return;

	/* Any freespace at all? */
	error = xfs_alloc_lookup_le(sc->sa.cnt_cur, 0, -1U, &have);
	if (!xchk_should_check_xref(sc, &error, &sc->sa.cnt_cur))
		return;
	if (!have) {
		if (agf->agf_freeblks != cpu_to_be32(0))
			xchk_block_xref_set_corrupt(sc, sc->sa.agf_bp);
		return;
	}

	/* Check agf_longest */
	error = xfs_alloc_get_rec(sc->sa.cnt_cur, &agbno, &blocks, &have);
	if (!xchk_should_check_xref(sc, &error, &sc->sa.cnt_cur))
		return;
	if (!have || blocks != be32_to_cpu(agf->agf_longest))
		xchk_block_xref_set_corrupt(sc, sc->sa.agf_bp);
}

/* Check the btree block counts in the AGF against the btrees. */
STATIC void
xchk_agf_xref_btreeblks(
	struct xfs_scrub	*sc)
{
	struct xfs_agf		*agf = sc->sa.agf_bp->b_addr;
	struct xfs_mount	*mp = sc->mp;
	xfs_filblks_t		blocks;
	xfs_agblock_t		btreeblks;
	int			error;

	/* agf_btreeblks didn't exist before lazysbcount */
	if (!xfs_has_lazysbcount(sc->mp))
		return;

	/* Check agf_rmap_blocks; set up for agf_btreeblks check */
	if (sc->sa.rmap_cur) {
		error = xfs_btree_count_blocks(sc->sa.rmap_cur, &blocks);
		if (!xchk_should_check_xref(sc, &error, &sc->sa.rmap_cur))
			return;
		btreeblks = blocks - 1;
		if (blocks != be32_to_cpu(agf->agf_rmap_blocks))
			xchk_block_xref_set_corrupt(sc, sc->sa.agf_bp);
	} else {
		btreeblks = 0;
	}

	/*
	 * No rmap cursor; we can't xref if we have the rmapbt feature.
	 * We also can't do it if we're missing the free space btree cursors.
	 */
	if ((xfs_has_rmapbt(mp) && !sc->sa.rmap_cur) ||
	    !sc->sa.bno_cur || !sc->sa.cnt_cur)
		return;

	/* Check agf_btreeblks */
	error = xfs_btree_count_blocks(sc->sa.bno_cur, &blocks);
	if (!xchk_should_check_xref(sc, &error, &sc->sa.bno_cur))
		return;
	btreeblks += blocks - 1;

	error = xfs_btree_count_blocks(sc->sa.cnt_cur, &blocks);
	if (!xchk_should_check_xref(sc, &error, &sc->sa.cnt_cur))
		return;
	btreeblks += blocks - 1;

	if (btreeblks != be32_to_cpu(agf->agf_btreeblks))
		xchk_block_xref_set_corrupt(sc, sc->sa.agf_bp);
}

/* Check agf_refcount_blocks against tree size */
static inline void
xchk_agf_xref_refcblks(
	struct xfs_scrub	*sc)
{
	struct xfs_agf		*agf = sc->sa.agf_bp->b_addr;
	xfs_filblks_t		blocks;
	int			error;

	if (!sc->sa.refc_cur)
		return;

	error = xfs_btree_count_blocks(sc->sa.refc_cur, &blocks);
	if (!xchk_should_check_xref(sc, &error, &sc->sa.refc_cur))
		return;
	if (blocks != be32_to_cpu(agf->agf_refcount_blocks))
		xchk_block_xref_set_corrupt(sc, sc->sa.agf_bp);
}

/* Cross-reference with the other btrees. */
STATIC void
xchk_agf_xref(
	struct xfs_scrub	*sc)
{
	struct xfs_mount	*mp = sc->mp;
	xfs_agblock_t		agbno;

	if (sc->sm->sm_flags & XFS_SCRUB_OFLAG_CORRUPT)
		return;

	agbno = XFS_AGF_BLOCK(mp);

	xchk_ag_btcur_init(sc, &sc->sa);

	xchk_xref_is_used_space(sc, agbno, 1);
	xchk_agf_xref_freeblks(sc);
	xchk_agf_xref_cntbt(sc);
	xchk_xref_is_not_inode_chunk(sc, agbno, 1);
	xchk_xref_is_only_owned_by(sc, agbno, 1, &XFS_RMAP_OINFO_FS);
	xchk_agf_xref_btreeblks(sc);
	xchk_xref_is_not_shared(sc, agbno, 1);
	xchk_xref_is_not_cow_staging(sc, agbno, 1);
	xchk_agf_xref_refcblks(sc);

	/* scrub teardown will take care of sc->sa for us */
}

/* Scrub the AGF. */
int
xchk_agf(
	struct xfs_scrub	*sc)
{
	struct xfs_mount	*mp = sc->mp;
	struct xfs_agf		*agf;
	struct xfs_perag	*pag;
	xfs_agnumber_t		agno = sc->sm->sm_agno;
	xfs_agblock_t		agbno;
	xfs_agblock_t		eoag;
	xfs_agblock_t		agfl_first;
	xfs_agblock_t		agfl_last;
	xfs_agblock_t		agfl_count;
	xfs_agblock_t		fl_count;
	int			level;
	int			error = 0;

	error = xchk_ag_read_headers(sc, agno, &sc->sa);
	if (!xchk_process_error(sc, agno, XFS_AGF_BLOCK(sc->mp), &error))
		goto out;
	xchk_buffer_recheck(sc, sc->sa.agf_bp);

	agf = sc->sa.agf_bp->b_addr;
	pag = sc->sa.pag;

	/* Check the AG length */
	eoag = be32_to_cpu(agf->agf_length);
	if (eoag != pag_group(pag)->xg_block_count)
		xchk_block_set_corrupt(sc, sc->sa.agf_bp);

	/* Check the AGF btree roots and levels */
	agbno = be32_to_cpu(agf->agf_bno_root);
	if (!xfs_verify_agbno(pag, agbno))
		xchk_block_set_corrupt(sc, sc->sa.agf_bp);

	agbno = be32_to_cpu(agf->agf_cnt_root);
	if (!xfs_verify_agbno(pag, agbno))
		xchk_block_set_corrupt(sc, sc->sa.agf_bp);

	level = be32_to_cpu(agf->agf_bno_level);
	if (level <= 0 || level > mp->m_alloc_maxlevels)
		xchk_block_set_corrupt(sc, sc->sa.agf_bp);

	level = be32_to_cpu(agf->agf_cnt_level);
	if (level <= 0 || level > mp->m_alloc_maxlevels)
		xchk_block_set_corrupt(sc, sc->sa.agf_bp);

	if (xfs_has_rmapbt(mp)) {
		agbno = be32_to_cpu(agf->agf_rmap_root);
		if (!xfs_verify_agbno(pag, agbno))
			xchk_block_set_corrupt(sc, sc->sa.agf_bp);

		level = be32_to_cpu(agf->agf_rmap_level);
		if (level <= 0 || level > mp->m_rmap_maxlevels)
			xchk_block_set_corrupt(sc, sc->sa.agf_bp);
	}

	if (xfs_has_reflink(mp)) {
		agbno = be32_to_cpu(agf->agf_refcount_root);
		if (!xfs_verify_agbno(pag, agbno))
			xchk_block_set_corrupt(sc, sc->sa.agf_bp);

		level = be32_to_cpu(agf->agf_refcount_level);
		if (level <= 0 || level > mp->m_refc_maxlevels)
			xchk_block_set_corrupt(sc, sc->sa.agf_bp);
	}

	/* Check the AGFL counters */
	agfl_first = be32_to_cpu(agf->agf_flfirst);
	agfl_last = be32_to_cpu(agf->agf_fllast);
	agfl_count = be32_to_cpu(agf->agf_flcount);
	if (agfl_last > agfl_first)
		fl_count = agfl_last - agfl_first + 1;
	else
		fl_count = xfs_agfl_size(mp) - agfl_first + agfl_last + 1;
	if (agfl_count != 0 && fl_count != agfl_count)
		xchk_block_set_corrupt(sc, sc->sa.agf_bp);

	/* Do the incore counters match? */
	if (pag->pagf_freeblks != be32_to_cpu(agf->agf_freeblks))
		xchk_block_set_corrupt(sc, sc->sa.agf_bp);
	if (pag->pagf_flcount != be32_to_cpu(agf->agf_flcount))
		xchk_block_set_corrupt(sc, sc->sa.agf_bp);
	if (xfs_has_lazysbcount(sc->mp) &&
	    pag->pagf_btreeblks != be32_to_cpu(agf->agf_btreeblks))
		xchk_block_set_corrupt(sc, sc->sa.agf_bp);

	xchk_agf_xref(sc);
out:
	return error;
}

/* AGFL */

struct xchk_agfl_info {
	/* Number of AGFL entries that the AGF claims are in use. */
	unsigned int		agflcount;

	/* Number of AGFL entries that we found. */
	unsigned int		nr_entries;

	/* Buffer to hold AGFL entries for extent checking. */
	xfs_agblock_t		*entries;

	struct xfs_buf		*agfl_bp;
	struct xfs_scrub	*sc;
};

/* Cross-reference with the other btrees. */
STATIC void
xchk_agfl_block_xref(
	struct xfs_scrub	*sc,
	xfs_agblock_t		agbno)
{
	if (sc->sm->sm_flags & XFS_SCRUB_OFLAG_CORRUPT)
		return;

	xchk_xref_is_used_space(sc, agbno, 1);
	xchk_xref_is_not_inode_chunk(sc, agbno, 1);
	xchk_xref_is_only_owned_by(sc, agbno, 1, &XFS_RMAP_OINFO_AG);
	xchk_xref_is_not_shared(sc, agbno, 1);
	xchk_xref_is_not_cow_staging(sc, agbno, 1);
}

/* Scrub an AGFL block. */
STATIC int
xchk_agfl_block(
	struct xfs_mount	*mp,
	xfs_agblock_t		agbno,
	void			*priv)
{
	struct xchk_agfl_info	*sai = priv;
	struct xfs_scrub	*sc = sai->sc;

	if (xfs_verify_agbno(sc->sa.pag, agbno) &&
	    sai->nr_entries < sai->agflcount)
		sai->entries[sai->nr_entries++] = agbno;
	else
		xchk_block_set_corrupt(sc, sai->agfl_bp);

	xchk_agfl_block_xref(sc, agbno);

	if (sc->sm->sm_flags & XFS_SCRUB_OFLAG_CORRUPT)
		return -ECANCELED;

	return 0;
}

static int
xchk_agblock_cmp(
	const void		*pa,
	const void		*pb)
{
	const xfs_agblock_t	*a = pa;
	const xfs_agblock_t	*b = pb;

	return (int)*a - (int)*b;
}

/* Cross-reference with the other btrees. */
STATIC void
xchk_agfl_xref(
	struct xfs_scrub	*sc)
{
	struct xfs_mount	*mp = sc->mp;
	xfs_agblock_t		agbno;

	if (sc->sm->sm_flags & XFS_SCRUB_OFLAG_CORRUPT)
		return;

	agbno = XFS_AGFL_BLOCK(mp);

	xchk_ag_btcur_init(sc, &sc->sa);

	xchk_xref_is_used_space(sc, agbno, 1);
	xchk_xref_is_not_inode_chunk(sc, agbno, 1);
	xchk_xref_is_only_owned_by(sc, agbno, 1, &XFS_RMAP_OINFO_FS);
	xchk_xref_is_not_shared(sc, agbno, 1);
	xchk_xref_is_not_cow_staging(sc, agbno, 1);

	/*
	 * Scrub teardown will take care of sc->sa for us.  Leave sc->sa
	 * active so that the agfl block xref can use it too.
	 */
}

/* Scrub the AGFL. */
int
xchk_agfl(
	struct xfs_scrub	*sc)
{
	struct xchk_agfl_info	sai = {
		.sc		= sc,
	};
	struct xfs_agf		*agf;
	xfs_agnumber_t		agno = sc->sm->sm_agno;
	unsigned int		i;
	int			error;

	/* Lock the AGF and AGI so that nobody can touch this AG. */
	error = xchk_ag_read_headers(sc, agno, &sc->sa);
	if (!xchk_process_error(sc, agno, XFS_AGFL_BLOCK(sc->mp), &error))
		return error;
	if (!sc->sa.agf_bp)
		return -EFSCORRUPTED;

	/* Try to read the AGFL, and verify its structure if we get it. */
	error = xfs_alloc_read_agfl(sc->sa.pag, sc->tp, &sai.agfl_bp);
	if (!xchk_process_error(sc, agno, XFS_AGFL_BLOCK(sc->mp), &error))
		return error;
	xchk_buffer_recheck(sc, sai.agfl_bp);

	xchk_agfl_xref(sc);

	if (sc->sm->sm_flags & XFS_SCRUB_OFLAG_CORRUPT)
		goto out;

	/* Allocate buffer to ensure uniqueness of AGFL entries. */
	agf = sc->sa.agf_bp->b_addr;
	sai.agflcount = be32_to_cpu(agf->agf_flcount);
	if (sai.agflcount > xfs_agfl_size(sc->mp)) {
		xchk_block_set_corrupt(sc, sc->sa.agf_bp);
		goto out;
	}
	sai.entries = kvcalloc(sai.agflcount, sizeof(xfs_agblock_t),
			       XCHK_GFP_FLAGS);
	if (!sai.entries) {
		error = -ENOMEM;
		goto out;
	}

	/* Check the blocks in the AGFL. */
	error = xfs_agfl_walk(sc->mp, sc->sa.agf_bp->b_addr, sai.agfl_bp,
			xchk_agfl_block, &sai);
	if (error == -ECANCELED) {
		error = 0;
		goto out_free;
	}
	if (error)
		goto out_free;

	if (sai.agflcount != sai.nr_entries) {
		xchk_block_set_corrupt(sc, sc->sa.agf_bp);
		goto out_free;
	}

	/* Sort entries, check for duplicates. */
	sort(sai.entries, sai.nr_entries, sizeof(sai.entries[0]),
			xchk_agblock_cmp, NULL);
	for (i = 1; i < sai.nr_entries; i++) {
		if (sai.entries[i] == sai.entries[i - 1]) {
			xchk_block_set_corrupt(sc, sc->sa.agf_bp);
			break;
		}
	}

out_free:
	kvfree(sai.entries);
out:
	return error;
}

/* AGI */

/* Check agi_count/agi_freecount */
static inline void
xchk_agi_xref_icounts(
	struct xfs_scrub	*sc)
{
	struct xfs_agi		*agi = sc->sa.agi_bp->b_addr;
	xfs_agino_t		icount;
	xfs_agino_t		freecount;
	int			error;

	if (!sc->sa.ino_cur)
		return;

	error = xfs_ialloc_count_inodes(sc->sa.ino_cur, &icount, &freecount);
	if (!xchk_should_check_xref(sc, &error, &sc->sa.ino_cur))
		return;
	if (be32_to_cpu(agi->agi_count) != icount ||
	    be32_to_cpu(agi->agi_freecount) != freecount)
		xchk_block_xref_set_corrupt(sc, sc->sa.agi_bp);
}

/* Check agi_[fi]blocks against tree size */
static inline void
xchk_agi_xref_fiblocks(
	struct xfs_scrub	*sc)
{
	struct xfs_agi		*agi = sc->sa.agi_bp->b_addr;
	xfs_filblks_t		blocks;
	int			error = 0;

	if (!xfs_has_inobtcounts(sc->mp))
		return;

	if (sc->sa.ino_cur) {
		error = xfs_btree_count_blocks(sc->sa.ino_cur, &blocks);
		if (!xchk_should_check_xref(sc, &error, &sc->sa.ino_cur))
			return;
		if (blocks != be32_to_cpu(agi->agi_iblocks))
			xchk_block_xref_set_corrupt(sc, sc->sa.agi_bp);
	}

	if (sc->sa.fino_cur) {
		error = xfs_btree_count_blocks(sc->sa.fino_cur, &blocks);
		if (!xchk_should_check_xref(sc, &error, &sc->sa.fino_cur))
			return;
		if (blocks != be32_to_cpu(agi->agi_fblocks))
			xchk_block_xref_set_corrupt(sc, sc->sa.agi_bp);
	}
}

/* Cross-reference with the other btrees. */
STATIC void
xchk_agi_xref(
	struct xfs_scrub	*sc)
{
	struct xfs_mount	*mp = sc->mp;
	xfs_agblock_t		agbno;

	if (sc->sm->sm_flags & XFS_SCRUB_OFLAG_CORRUPT)
		return;

	agbno = XFS_AGI_BLOCK(mp);

	xchk_ag_btcur_init(sc, &sc->sa);

	xchk_xref_is_used_space(sc, agbno, 1);
	xchk_xref_is_not_inode_chunk(sc, agbno, 1);
	xchk_agi_xref_icounts(sc);
	xchk_xref_is_only_owned_by(sc, agbno, 1, &XFS_RMAP_OINFO_FS);
	xchk_xref_is_not_shared(sc, agbno, 1);
	xchk_xref_is_not_cow_staging(sc, agbno, 1);
	xchk_agi_xref_fiblocks(sc);

	/* scrub teardown will take care of sc->sa for us */
}

/*
 * Check the unlinked buckets for links to bad inodes.  We hold the AGI, so
 * there cannot be any threads updating unlinked list pointers in this AG.
 */
STATIC void
xchk_iunlink(
	struct xfs_scrub	*sc,
	struct xfs_agi		*agi)
{
	unsigned int		i;
	struct xfs_inode	*ip;

	for (i = 0; i < XFS_AGI_UNLINKED_BUCKETS; i++) {
		xfs_agino_t	agino = be32_to_cpu(agi->agi_unlinked[i]);

		while (agino != NULLAGINO) {
			if (agino % XFS_AGI_UNLINKED_BUCKETS != i) {
				xchk_block_set_corrupt(sc, sc->sa.agi_bp);
				return;
			}

			ip = xfs_iunlink_lookup(sc->sa.pag, agino);
			if (!ip) {
				xchk_block_set_corrupt(sc, sc->sa.agi_bp);
				return;
			}

			if (!xfs_inode_on_unlinked_list(ip)) {
				xchk_block_set_corrupt(sc, sc->sa.agi_bp);
				return;
			}

			agino = ip->i_next_unlinked;
		}
	}
}

/* Scrub the AGI. */
int
xchk_agi(
	struct xfs_scrub	*sc)
{
	struct xfs_mount	*mp = sc->mp;
	struct xfs_agi		*agi;
	struct xfs_perag	*pag;
	struct xfs_ino_geometry	*igeo = M_IGEO(sc->mp);
	xfs_agnumber_t		agno = sc->sm->sm_agno;
	xfs_agblock_t		agbno;
	xfs_agblock_t		eoag;
	xfs_agino_t		agino;
	xfs_agino_t		first_agino;
	xfs_agino_t		last_agino;
	xfs_agino_t		icount;
	int			i;
	int			level;
	int			error = 0;

	error = xchk_ag_read_headers(sc, agno, &sc->sa);
	if (!xchk_process_error(sc, agno, XFS_AGI_BLOCK(sc->mp), &error))
		goto out;
	xchk_buffer_recheck(sc, sc->sa.agi_bp);

	agi = sc->sa.agi_bp->b_addr;
	pag = sc->sa.pag;

	/* Check the AG length */
	eoag = be32_to_cpu(agi->agi_length);
	if (eoag != pag_group(pag)->xg_block_count)
		xchk_block_set_corrupt(sc, sc->sa.agi_bp);

	/* Check btree roots and levels */
	agbno = be32_to_cpu(agi->agi_root);
	if (!xfs_verify_agbno(pag, agbno))
		xchk_block_set_corrupt(sc, sc->sa.agi_bp);

	level = be32_to_cpu(agi->agi_level);
	if (level <= 0 || level > igeo->inobt_maxlevels)
		xchk_block_set_corrupt(sc, sc->sa.agi_bp);

	if (xfs_has_finobt(mp)) {
		agbno = be32_to_cpu(agi->agi_free_root);
		if (!xfs_verify_agbno(pag, agbno))
			xchk_block_set_corrupt(sc, sc->sa.agi_bp);

		level = be32_to_cpu(agi->agi_free_level);
		if (level <= 0 || level > igeo->inobt_maxlevels)
			xchk_block_set_corrupt(sc, sc->sa.agi_bp);
	}

	/* Check inode counters */
	xfs_agino_range(mp, agno, &first_agino, &last_agino);
	icount = be32_to_cpu(agi->agi_count);
	if (icount > last_agino - first_agino + 1 ||
	    icount < be32_to_cpu(agi->agi_freecount))
		xchk_block_set_corrupt(sc, sc->sa.agi_bp);

	/* Check inode pointers */
	agino = be32_to_cpu(agi->agi_newino);
	if (!xfs_verify_agino_or_null(pag, agino))
		xchk_block_set_corrupt(sc, sc->sa.agi_bp);

	agino = be32_to_cpu(agi->agi_dirino);
	if (!xfs_verify_agino_or_null(pag, agino))
		xchk_block_set_corrupt(sc, sc->sa.agi_bp);

	/* Check unlinked inode buckets */
	for (i = 0; i < XFS_AGI_UNLINKED_BUCKETS; i++) {
		agino = be32_to_cpu(agi->agi_unlinked[i]);
		if (!xfs_verify_agino_or_null(pag, agino))
			xchk_block_set_corrupt(sc, sc->sa.agi_bp);
	}

	if (agi->agi_pad32 != cpu_to_be32(0))
		xchk_block_set_corrupt(sc, sc->sa.agi_bp);

	/* Do the incore counters match? */
	if (pag->pagi_count != be32_to_cpu(agi->agi_count))
		xchk_block_set_corrupt(sc, sc->sa.agi_bp);
	if (pag->pagi_freecount != be32_to_cpu(agi->agi_freecount))
		xchk_block_set_corrupt(sc, sc->sa.agi_bp);

	xchk_iunlink(sc, agi);

	xchk_agi_xref(sc);
out:
	return error;
}