linux/fs/xfs/scrub/rmap.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_log_format.h"
#include "xfs_trans_resv.h"
#include "xfs_mount.h"
#include "xfs_trans.h"
#include "xfs_btree.h"
#include "xfs_rmap.h"
#include "xfs_refcount.h"
#include "xfs_ag.h"
#include "xfs_bit.h"
#include "xfs_alloc.h"
#include "xfs_alloc_btree.h"
#include "xfs_ialloc_btree.h"
#include "xfs_refcount_btree.h"
#include "scrub/scrub.h"
#include "scrub/common.h"
#include "scrub/btree.h"
#include "scrub/bitmap.h"

/*
 * Set us up to scrub reverse mapping btrees.
 */
int
xchk_setup_ag_rmapbt(
	struct xfs_scrub	*sc)
{
	if (xchk_need_intent_drain(sc))
		xchk_fsgates_enable(sc, XCHK_FSGATES_DRAIN);

	return xchk_setup_ag_btree(sc, false);
}

/* Reverse-mapping scrubber. */

struct xchk_rmap {
	/*
	 * The furthest-reaching of the rmapbt records that we've already
	 * processed.  This enables us to detect overlapping records for space
	 * allocations that cannot be shared.
	 */
	struct xfs_rmap_irec	overlap_rec;

	/*
	 * The previous rmapbt record, so that we can check for two records
	 * that could be one.
	 */
	struct xfs_rmap_irec	prev_rec;

	/* Bitmaps containing all blocks for each type of AG metadata. */
	struct xagb_bitmap	fs_owned;
	struct xagb_bitmap	log_owned;
	struct xagb_bitmap	ag_owned;
	struct xagb_bitmap	inobt_owned;
	struct xagb_bitmap	refcbt_owned;

	/* Did we complete the AG space metadata bitmaps? */
	bool			bitmaps_complete;
};

/* Cross-reference a rmap against the refcount btree. */
STATIC void
xchk_rmapbt_xref_refc(
	struct xfs_scrub	*sc,
	struct xfs_rmap_irec	*irec)
{
	xfs_agblock_t		fbno;
	xfs_extlen_t		flen;
	bool			non_inode;
	bool			is_bmbt;
	bool			is_attr;
	bool			is_unwritten;
	int			error;

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

	non_inode = XFS_RMAP_NON_INODE_OWNER(irec->rm_owner);
	is_bmbt = irec->rm_flags & XFS_RMAP_BMBT_BLOCK;
	is_attr = irec->rm_flags & XFS_RMAP_ATTR_FORK;
	is_unwritten = irec->rm_flags & XFS_RMAP_UNWRITTEN;

	/* If this is shared, must be a data fork extent. */
	error = xfs_refcount_find_shared(sc->sa.refc_cur, irec->rm_startblock,
			irec->rm_blockcount, &fbno, &flen, false);
	if (!xchk_should_check_xref(sc, &error, &sc->sa.refc_cur))
		return;
	if (flen != 0 && (non_inode || is_attr || is_bmbt || is_unwritten))
		xchk_btree_xref_set_corrupt(sc, sc->sa.refc_cur, 0);
}

/* Cross-reference with the other btrees. */
STATIC void
xchk_rmapbt_xref(
	struct xfs_scrub	*sc,
	struct xfs_rmap_irec	*irec)
{
	xfs_agblock_t		agbno = irec->rm_startblock;
	xfs_extlen_t		len = irec->rm_blockcount;

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

	xchk_xref_is_used_space(sc, agbno, len);
	if (irec->rm_owner == XFS_RMAP_OWN_INODES)
		xchk_xref_is_inode_chunk(sc, agbno, len);
	else
		xchk_xref_is_not_inode_chunk(sc, agbno, len);
	if (irec->rm_owner == XFS_RMAP_OWN_COW)
		xchk_xref_is_cow_staging(sc, irec->rm_startblock,
				irec->rm_blockcount);
	else
		xchk_rmapbt_xref_refc(sc, irec);
}

/*
 * Check for bogus UNWRITTEN flags in the rmapbt node block keys.
 *
 * In reverse mapping records, the file mapping extent state
 * (XFS_RMAP_OFF_UNWRITTEN) is a record attribute, not a key field.  It is not
 * involved in lookups in any way.  In older kernels, the functions that
 * convert rmapbt records to keys forgot to filter out the extent state bit,
 * even though the key comparison functions have filtered the flag correctly.
 * If we spot an rmap key with the unwritten bit set in rm_offset, we should
 * mark the btree as needing optimization to rebuild the btree without those
 * flags.
 */
STATIC void
xchk_rmapbt_check_unwritten_in_keyflags(
	struct xchk_btree	*bs)
{
	struct xfs_scrub	*sc = bs->sc;
	struct xfs_btree_cur	*cur = bs->cur;
	struct xfs_btree_block	*keyblock;
	union xfs_btree_key	*lkey, *hkey;
	__be64			badflag = cpu_to_be64(XFS_RMAP_OFF_UNWRITTEN);
	unsigned int		level;

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

	for (level = 1; level < cur->bc_nlevels; level++) {
		struct xfs_buf	*bp;
		unsigned int	ptr;

		/* Only check the first time we've seen this node block. */
		if (cur->bc_levels[level].ptr > 1)
			continue;

		keyblock = xfs_btree_get_block(cur, level, &bp);
		for (ptr = 1; ptr <= be16_to_cpu(keyblock->bb_numrecs); ptr++) {
			lkey = xfs_btree_key_addr(cur, ptr, keyblock);

			if (lkey->rmap.rm_offset & badflag) {
				xchk_btree_set_preen(sc, cur, level);
				break;
			}

			hkey = xfs_btree_high_key_addr(cur, ptr, keyblock);
			if (hkey->rmap.rm_offset & badflag) {
				xchk_btree_set_preen(sc, cur, level);
				break;
			}
		}
	}
}

static inline bool
xchk_rmapbt_is_shareable(
	struct xfs_scrub		*sc,
	const struct xfs_rmap_irec	*irec)
{
	if (!xfs_has_reflink(sc->mp))
		return false;
	if (XFS_RMAP_NON_INODE_OWNER(irec->rm_owner))
		return false;
	if (irec->rm_flags & (XFS_RMAP_BMBT_BLOCK | XFS_RMAP_ATTR_FORK |
			      XFS_RMAP_UNWRITTEN))
		return false;
	return true;
}

/* Flag failures for records that overlap but cannot. */
STATIC void
xchk_rmapbt_check_overlapping(
	struct xchk_btree		*bs,
	struct xchk_rmap		*cr,
	const struct xfs_rmap_irec	*irec)
{
	xfs_agblock_t			pnext, inext;

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

	/* No previous record? */
	if (cr->overlap_rec.rm_blockcount == 0)
		goto set_prev;

	/* Do overlap_rec and irec overlap? */
	pnext = cr->overlap_rec.rm_startblock + cr->overlap_rec.rm_blockcount;
	if (pnext <= irec->rm_startblock)
		goto set_prev;

	/* Overlap is only allowed if both records are data fork mappings. */
	if (!xchk_rmapbt_is_shareable(bs->sc, &cr->overlap_rec) ||
	    !xchk_rmapbt_is_shareable(bs->sc, irec))
		xchk_btree_set_corrupt(bs->sc, bs->cur, 0);

	/* Save whichever rmap record extends furthest. */
	inext = irec->rm_startblock + irec->rm_blockcount;
	if (pnext > inext)
		return;

set_prev:
	memcpy(&cr->overlap_rec, irec, sizeof(struct xfs_rmap_irec));
}

/* Decide if two reverse-mapping records can be merged. */
static inline bool
xchk_rmap_mergeable(
	struct xchk_rmap		*cr,
	const struct xfs_rmap_irec	*r2)
{
	const struct xfs_rmap_irec	*r1 = &cr->prev_rec;

	/* Ignore if prev_rec is not yet initialized. */
	if (cr->prev_rec.rm_blockcount == 0)
		return false;

	if (r1->rm_owner != r2->rm_owner)
		return false;
	if (r1->rm_startblock + r1->rm_blockcount != r2->rm_startblock)
		return false;
	if ((unsigned long long)r1->rm_blockcount + r2->rm_blockcount >
	    XFS_RMAP_LEN_MAX)
		return false;
	if (XFS_RMAP_NON_INODE_OWNER(r2->rm_owner))
		return true;
	/* must be an inode owner below here */
	if (r1->rm_flags != r2->rm_flags)
		return false;
	if (r1->rm_flags & XFS_RMAP_BMBT_BLOCK)
		return true;
	return r1->rm_offset + r1->rm_blockcount == r2->rm_offset;
}

/* Flag failures for records that could be merged. */
STATIC void
xchk_rmapbt_check_mergeable(
	struct xchk_btree		*bs,
	struct xchk_rmap		*cr,
	const struct xfs_rmap_irec	*irec)
{
	if (bs->sc->sm->sm_flags & XFS_SCRUB_OFLAG_CORRUPT)
		return;

	if (xchk_rmap_mergeable(cr, irec))
		xchk_btree_set_corrupt(bs->sc, bs->cur, 0);

	memcpy(&cr->prev_rec, irec, sizeof(struct xfs_rmap_irec));
}

/* Compare an rmap for AG metadata against the metadata walk. */
STATIC int
xchk_rmapbt_mark_bitmap(
	struct xchk_btree		*bs,
	struct xchk_rmap		*cr,
	const struct xfs_rmap_irec	*irec)
{
	struct xfs_scrub		*sc = bs->sc;
	struct xagb_bitmap		*bmp = NULL;
	xfs_extlen_t			fsbcount = irec->rm_blockcount;

	/*
	 * Skip corrupt records.  It is essential that we detect records in the
	 * btree that cannot overlap but do, flag those as CORRUPT, and skip
	 * the bitmap comparison to avoid generating false XCORRUPT reports.
	 */
	if (sc->sm->sm_flags & XFS_SCRUB_OFLAG_CORRUPT)
		return 0;

	/*
	 * If the AG metadata walk didn't complete, there's no point in
	 * comparing against partial results.
	 */
	if (!cr->bitmaps_complete)
		return 0;

	switch (irec->rm_owner) {
	case XFS_RMAP_OWN_FS:
		bmp = &cr->fs_owned;
		break;
	case XFS_RMAP_OWN_LOG:
		bmp = &cr->log_owned;
		break;
	case XFS_RMAP_OWN_AG:
		bmp = &cr->ag_owned;
		break;
	case XFS_RMAP_OWN_INOBT:
		bmp = &cr->inobt_owned;
		break;
	case XFS_RMAP_OWN_REFC:
		bmp = &cr->refcbt_owned;
		break;
	}

	if (!bmp)
		return 0;

	if (xagb_bitmap_test(bmp, irec->rm_startblock, &fsbcount)) {
		/*
		 * The start of this reverse mapping corresponds to a set
		 * region in the bitmap.  If the mapping covers more area than
		 * the set region, then it covers space that wasn't found by
		 * the AG metadata walk.
		 */
		if (fsbcount < irec->rm_blockcount)
			xchk_btree_xref_set_corrupt(bs->sc,
					bs->sc->sa.rmap_cur, 0);
	} else {
		/*
		 * The start of this reverse mapping does not correspond to a
		 * completely set region in the bitmap.  The region wasn't
		 * fully set by walking the AG metadata, so this is a
		 * cross-referencing corruption.
		 */
		xchk_btree_xref_set_corrupt(bs->sc, bs->sc->sa.rmap_cur, 0);
	}

	/* Unset the region so that we can detect missing rmap records. */
	return xagb_bitmap_clear(bmp, irec->rm_startblock, irec->rm_blockcount);
}

/* Scrub an rmapbt record. */
STATIC int
xchk_rmapbt_rec(
	struct xchk_btree	*bs,
	const union xfs_btree_rec *rec)
{
	struct xchk_rmap	*cr = bs->private;
	struct xfs_rmap_irec	irec;

	if (xfs_rmap_btrec_to_irec(rec, &irec) != NULL ||
	    xfs_rmap_check_irec(bs->cur, &irec) != NULL) {
		xchk_btree_set_corrupt(bs->sc, bs->cur, 0);
		return 0;
	}

	xchk_rmapbt_check_unwritten_in_keyflags(bs);
	xchk_rmapbt_check_mergeable(bs, cr, &irec);
	xchk_rmapbt_check_overlapping(bs, cr, &irec);
	xchk_rmapbt_xref(bs->sc, &irec);

	return xchk_rmapbt_mark_bitmap(bs, cr, &irec);
}

/* Add an AGFL block to the rmap list. */
STATIC int
xchk_rmapbt_walk_agfl(
	struct xfs_mount	*mp,
	xfs_agblock_t		agbno,
	void			*priv)
{
	struct xagb_bitmap	*bitmap = priv;

	return xagb_bitmap_set(bitmap, agbno, 1);
}

/*
 * Set up bitmaps mapping all the AG metadata to compare with the rmapbt
 * records.
 *
 * Grab our own btree cursors here if the scrub setup function didn't give us a
 * btree cursor due to reports of poor health.  We need to find out if the
 * rmapbt disagrees with primary metadata btrees to tag the rmapbt as being
 * XCORRUPT.
 */
STATIC int
xchk_rmapbt_walk_ag_metadata(
	struct xfs_scrub	*sc,
	struct xchk_rmap	*cr)
{
	struct xfs_mount	*mp = sc->mp;
	struct xfs_buf		*agfl_bp;
	struct xfs_agf		*agf = sc->sa.agf_bp->b_addr;
	struct xfs_btree_cur	*cur;
	int			error;

	/* OWN_FS: AG headers */
	error = xagb_bitmap_set(&cr->fs_owned, XFS_SB_BLOCK(mp),
			XFS_AGFL_BLOCK(mp) - XFS_SB_BLOCK(mp) + 1);
	if (error)
		goto out;

	/* OWN_LOG: Internal log */
	if (xfs_ag_contains_log(mp, sc->sa.pag->pag_agno)) {
		error = xagb_bitmap_set(&cr->log_owned,
				XFS_FSB_TO_AGBNO(mp, mp->m_sb.sb_logstart),
				mp->m_sb.sb_logblocks);
		if (error)
			goto out;
	}

	/* OWN_AG: bnobt, cntbt, rmapbt, and AGFL */
	cur = sc->sa.bno_cur;
	if (!cur)
		cur = xfs_allocbt_init_cursor(sc->mp, sc->tp, sc->sa.agf_bp,
				sc->sa.pag, XFS_BTNUM_BNO);
	error = xagb_bitmap_set_btblocks(&cr->ag_owned, cur);
	if (cur != sc->sa.bno_cur)
		xfs_btree_del_cursor(cur, error);
	if (error)
		goto out;

	cur = sc->sa.cnt_cur;
	if (!cur)
		cur = xfs_allocbt_init_cursor(sc->mp, sc->tp, sc->sa.agf_bp,
				sc->sa.pag, XFS_BTNUM_CNT);
	error = xagb_bitmap_set_btblocks(&cr->ag_owned, cur);
	if (cur != sc->sa.cnt_cur)
		xfs_btree_del_cursor(cur, error);
	if (error)
		goto out;

	error = xagb_bitmap_set_btblocks(&cr->ag_owned, sc->sa.rmap_cur);
	if (error)
		goto out;

	error = xfs_alloc_read_agfl(sc->sa.pag, sc->tp, &agfl_bp);
	if (error)
		goto out;

	error = xfs_agfl_walk(sc->mp, agf, agfl_bp, xchk_rmapbt_walk_agfl,
			&cr->ag_owned);
	xfs_trans_brelse(sc->tp, agfl_bp);
	if (error)
		goto out;

	/* OWN_INOBT: inobt, finobt */
	cur = sc->sa.ino_cur;
	if (!cur)
		cur = xfs_inobt_init_cursor(sc->sa.pag, sc->tp, sc->sa.agi_bp,
				XFS_BTNUM_INO);
	error = xagb_bitmap_set_btblocks(&cr->inobt_owned, cur);
	if (cur != sc->sa.ino_cur)
		xfs_btree_del_cursor(cur, error);
	if (error)
		goto out;

	if (xfs_has_finobt(sc->mp)) {
		cur = sc->sa.fino_cur;
		if (!cur)
			cur = xfs_inobt_init_cursor(sc->sa.pag, sc->tp,
					sc->sa.agi_bp, XFS_BTNUM_FINO);
		error = xagb_bitmap_set_btblocks(&cr->inobt_owned, cur);
		if (cur != sc->sa.fino_cur)
			xfs_btree_del_cursor(cur, error);
		if (error)
			goto out;
	}

	/* OWN_REFC: refcountbt */
	if (xfs_has_reflink(sc->mp)) {
		cur = sc->sa.refc_cur;
		if (!cur)
			cur = xfs_refcountbt_init_cursor(sc->mp, sc->tp,
					sc->sa.agf_bp, sc->sa.pag);
		error = xagb_bitmap_set_btblocks(&cr->refcbt_owned, cur);
		if (cur != sc->sa.refc_cur)
			xfs_btree_del_cursor(cur, error);
		if (error)
			goto out;
	}

out:
	/*
	 * If there's an error, set XFAIL and disable the bitmap
	 * cross-referencing checks, but proceed with the scrub anyway.
	 */
	if (error)
		xchk_btree_xref_process_error(sc, sc->sa.rmap_cur,
				sc->sa.rmap_cur->bc_nlevels - 1, &error);
	else
		cr->bitmaps_complete = true;
	return 0;
}

/*
 * Check for set regions in the bitmaps; if there are any, the rmap records do
 * not describe all the AG metadata.
 */
STATIC void
xchk_rmapbt_check_bitmaps(
	struct xfs_scrub	*sc,
	struct xchk_rmap	*cr)
{
	struct xfs_btree_cur	*cur = sc->sa.rmap_cur;
	unsigned int		level;

	if (sc->sm->sm_flags & (XFS_SCRUB_OFLAG_CORRUPT |
				XFS_SCRUB_OFLAG_XFAIL))
		return;
	if (!cur)
		return;
	level = cur->bc_nlevels - 1;

	/*
	 * Any bitmap with bits still set indicates that the reverse mapping
	 * doesn't cover the entire primary structure.
	 */
	if (xagb_bitmap_hweight(&cr->fs_owned) != 0)
		xchk_btree_xref_set_corrupt(sc, cur, level);

	if (xagb_bitmap_hweight(&cr->log_owned) != 0)
		xchk_btree_xref_set_corrupt(sc, cur, level);

	if (xagb_bitmap_hweight(&cr->ag_owned) != 0)
		xchk_btree_xref_set_corrupt(sc, cur, level);

	if (xagb_bitmap_hweight(&cr->inobt_owned) != 0)
		xchk_btree_xref_set_corrupt(sc, cur, level);

	if (xagb_bitmap_hweight(&cr->refcbt_owned) != 0)
		xchk_btree_xref_set_corrupt(sc, cur, level);
}

/* Scrub the rmap btree for some AG. */
int
xchk_rmapbt(
	struct xfs_scrub	*sc)
{
	struct xchk_rmap	*cr;
	int			error;

	cr = kzalloc(sizeof(struct xchk_rmap), XCHK_GFP_FLAGS);
	if (!cr)
		return -ENOMEM;

	xagb_bitmap_init(&cr->fs_owned);
	xagb_bitmap_init(&cr->log_owned);
	xagb_bitmap_init(&cr->ag_owned);
	xagb_bitmap_init(&cr->inobt_owned);
	xagb_bitmap_init(&cr->refcbt_owned);

	error = xchk_rmapbt_walk_ag_metadata(sc, cr);
	if (error)
		goto out;

	error = xchk_btree(sc, sc->sa.rmap_cur, xchk_rmapbt_rec,
			&XFS_RMAP_OINFO_AG, cr);
	if (error)
		goto out;

	xchk_rmapbt_check_bitmaps(sc, cr);

out:
	xagb_bitmap_destroy(&cr->refcbt_owned);
	xagb_bitmap_destroy(&cr->inobt_owned);
	xagb_bitmap_destroy(&cr->ag_owned);
	xagb_bitmap_destroy(&cr->log_owned);
	xagb_bitmap_destroy(&cr->fs_owned);
	kfree(cr);
	return error;
}

/* xref check that the extent is owned only by a given owner */
void
xchk_xref_is_only_owned_by(
	struct xfs_scrub		*sc,
	xfs_agblock_t			bno,
	xfs_extlen_t			len,
	const struct xfs_owner_info	*oinfo)
{
	struct xfs_rmap_matches		res;
	int				error;

	if (!sc->sa.rmap_cur || xchk_skip_xref(sc->sm))
		return;

	error = xfs_rmap_count_owners(sc->sa.rmap_cur, bno, len, oinfo, &res);
	if (!xchk_should_check_xref(sc, &error, &sc->sa.rmap_cur))
		return;
	if (res.matches != 1)
		xchk_btree_xref_set_corrupt(sc, sc->sa.rmap_cur, 0);
	if (res.bad_non_owner_matches)
		xchk_btree_xref_set_corrupt(sc, sc->sa.rmap_cur, 0);
	if (res.non_owner_matches)
		xchk_btree_xref_set_corrupt(sc, sc->sa.rmap_cur, 0);
}

/* xref check that the extent is not owned by a given owner */
void
xchk_xref_is_not_owned_by(
	struct xfs_scrub		*sc,
	xfs_agblock_t			bno,
	xfs_extlen_t			len,
	const struct xfs_owner_info	*oinfo)
{
	struct xfs_rmap_matches		res;
	int				error;

	if (!sc->sa.rmap_cur || xchk_skip_xref(sc->sm))
		return;

	error = xfs_rmap_count_owners(sc->sa.rmap_cur, bno, len, oinfo, &res);
	if (!xchk_should_check_xref(sc, &error, &sc->sa.rmap_cur))
		return;
	if (res.matches != 0)
		xchk_btree_xref_set_corrupt(sc, sc->sa.rmap_cur, 0);
	if (res.bad_non_owner_matches)
		xchk_btree_xref_set_corrupt(sc, sc->sa.rmap_cur, 0);
}

/* xref check that the extent has no reverse mapping at all */
void
xchk_xref_has_no_owner(
	struct xfs_scrub	*sc,
	xfs_agblock_t		bno,
	xfs_extlen_t		len)
{
	enum xbtree_recpacking	outcome;
	int			error;

	if (!sc->sa.rmap_cur || xchk_skip_xref(sc->sm))
		return;

	error = xfs_rmap_has_records(sc->sa.rmap_cur, bno, len, &outcome);
	if (!xchk_should_check_xref(sc, &error, &sc->sa.rmap_cur))
		return;
	if (outcome != XBTREE_RECPACKING_EMPTY)
		xchk_btree_xref_set_corrupt(sc, sc->sa.rmap_cur, 0);
}