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// SPDX-License-Identifier: GPL-2.0+
/*
* Copyright (C) 2019 Oracle. All Rights Reserved.
* Author: Darrick J. Wong <darrick.wong@oracle.com>
*/
#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_defer.h"
#include "xfs_btree.h"
#include "xfs_bit.h"
#include "xfs_log_format.h"
#include "xfs_trans.h"
#include "xfs_sb.h"
#include "xfs_inode.h"
#include "xfs_alloc.h"
#include "xfs_ialloc.h"
#include "xfs_rmap.h"
#include "xfs_error.h"
#include "xfs_errortag.h"
#include "xfs_icache.h"
#include "xfs_health.h"
#include "xfs_bmap.h"
#include "scrub/xfs_scrub.h"
#include "scrub/scrub.h"
#include "scrub/common.h"
#include "scrub/trace.h"
#include "scrub/repair.h"
/*
* FS Summary Counters
* ===================
*
* The basics of filesystem summary counter checking are that we iterate the
* AGs counting the number of free blocks, free space btree blocks, per-AG
* reservations, inodes, delayed allocation reservations, and free inodes.
* Then we compare what we computed against the in-core counters.
*
* However, the reality is that summary counters are a tricky beast to check.
* While we /could/ freeze the filesystem and scramble around the AGs counting
* the free blocks, in practice we prefer not do that for a scan because
* freezing is costly. To get around this, we added a per-cpu counter of the
* delalloc reservations so that we can rotor around the AGs relatively
* quickly, and we allow the counts to be slightly off because we're not
* taking any locks while we do this.
*/
int
xchk_setup_fscounters(
struct xfs_scrub *sc,
struct xfs_inode *ip)
{
int error;
sc->buf = kmem_zalloc(sizeof(struct xchk_fscounters), KM_SLEEP);
if (!sc->buf)
return -ENOMEM;
/*
* Pause background reclaim while we're scrubbing to reduce the
* likelihood of background perturbations to the counters throwing
* off our calculations.
*
* If we're repairing, we need to prevent any other thread from
* changing the global fs summary counters while we're repairing them.
* This requires the fs to be frozen, which will disable background
* reclaim and purge all inactive inodes.
*/
if (sc->sm->sm_flags & XFS_SCRUB_IFLAG_REPAIR) {
error = xchk_fs_freeze(sc);
if (error)
return error;
} else {
xchk_disable_reclaim(sc);
}
return xchk_trans_alloc(sc, 0);
}
/*
* Calculate what the global in-core counters ought to be from the AG header
* contents. Callers can compare this to the actual in-core counters to
* calculate by how much both in-core and on-disk counters need to be
* adjusted.
*/
STATIC int
xchk_fscounters_calc(
struct xfs_scrub *sc,
struct xchk_fscounters *fsc)
{
struct xfs_mount *mp = sc->mp;
struct xfs_buf *agi_bp;
struct xfs_buf *agf_bp;
struct xfs_agi *agi;
struct xfs_agf *agf;
struct xfs_perag *pag;
uint64_t delayed;
xfs_agnumber_t agno;
int error;
for (agno = 0; agno < mp->m_sb.sb_agcount; agno++) {
/* Lock both AG headers. */
error = xfs_ialloc_read_agi(mp, sc->tp, agno, &agi_bp);
if (error)
return error;
error = xfs_alloc_read_agf(mp, sc->tp, agno, 0, &agf_bp);
if (error)
return error;
if (!agf_bp)
return -ENOMEM;
/* Count all the inodes */
agi = XFS_BUF_TO_AGI(agi_bp);
fsc->icount += be32_to_cpu(agi->agi_count);
fsc->ifree += be32_to_cpu(agi->agi_freecount);
/* Add up the free/freelist/bnobt/cntbt blocks */
agf = XFS_BUF_TO_AGF(agf_bp);
fsc->fdblocks += be32_to_cpu(agf->agf_freeblks);
fsc->fdblocks += be32_to_cpu(agf->agf_flcount);
fsc->fdblocks += be32_to_cpu(agf->agf_btreeblks);
/*
* Per-AG reservations are taken out of the incore counters,
* so they must be left out of the free blocks computation.
*/
pag = xfs_perag_get(mp, agno);
fsc->fdblocks -= pag->pag_meta_resv.ar_reserved;
fsc->fdblocks -= pag->pag_rmapbt_resv.ar_orig_reserved;
xfs_perag_put(pag);
xfs_trans_brelse(sc->tp, agf_bp);
xfs_trans_brelse(sc->tp, agi_bp);
}
/*
* The global incore space reservation is taken from the incore
* counters, so leave that out of the computation.
*/
fsc->fdblocks -= mp->m_resblks_avail;
/*
* Delayed allocation reservations are taken out of the incore counters
* but not recorded on disk, so leave them and their indlen blocks out
* of the computation.
*/
delayed = percpu_counter_sum(&mp->m_delayed_blks);
fsc->fdblocks -= delayed;
trace_xchk_fscounters_calc(mp, fsc->icount, fsc->ifree, fsc->fdblocks,
delayed);
/* Bail out if the values we compute are totally nonsense. */
if (!xfs_verify_icount(mp, fsc->icount) ||
fsc->fdblocks > mp->m_sb.sb_dblocks ||
fsc->ifree > fsc->icount)
return -EFSCORRUPTED;
return 0;
}
/*
* Is the @counter within an acceptable range of @expected?
*
* Currently that means 1/16th (6%) or @nr_range of the @expected value.
* If we're repairing then we require an exact match.
*/
static inline bool
xchk_fscounter_within_range(
struct xfs_scrub *sc,
struct percpu_counter *counter,
uint64_t expected,
uint64_t nr_range)
{
int64_t value = percpu_counter_sum(counter);
uint64_t range;
if (sc->sm->sm_flags & XFS_SCRUB_IFLAG_REPAIR)
range = 0;
else
range = max_t(uint64_t, expected >> 4, nr_range);
if (value < 0)
return false;
if (range < expected && value < expected - range)
return false;
if ((int64_t)(expected + range) >= 0 && value > expected + range)
return false;
return true;
}
/* Check the superblock counters. */
int
xchk_fscounters(
struct xfs_scrub *sc)
{
struct xfs_mount *mp = sc->mp;
struct xchk_fscounters *fsc = sc->buf;
int64_t icount, ifree, fdblocks;
int error;
icount = percpu_counter_sum(&sc->mp->m_icount);
ifree = percpu_counter_sum(&sc->mp->m_ifree);
fdblocks = percpu_counter_sum(&sc->mp->m_fdblocks);
if (icount < 0 || ifree < 0 || fdblocks < 0)
xchk_block_set_corrupt(sc, mp->m_sb_bp);
/* See if icount is obviously wrong. */
if (!xfs_verify_icount(mp, icount))
xchk_block_set_corrupt(sc, mp->m_sb_bp);
/* See if fdblocks / ifree are obviously wrong. */
if (fdblocks > mp->m_sb.sb_dblocks)
xchk_block_set_corrupt(sc, mp->m_sb_bp);
if (ifree > icount)
xchk_block_set_corrupt(sc, mp->m_sb_bp);
/* If we already know it's bad, we can skip the AG iteration. */
if (sc->sm->sm_flags & XFS_SCRUB_OFLAG_CORRUPT)
return 0;
/* Counters seem ok, but let's count them. */
error = xchk_fscounters_calc(sc, fsc);
if (!xchk_process_error(sc, 0, XFS_SB_BLOCK(sc->mp), &error))
return error;
/*
* Compare the in-core counters with whatever we counted. We'll
* consider the inode counts ok if they're within 1024 inodes, and the
* free block counts if they're within 1/64th of the filesystem size.
*/
if (!xchk_fscounter_within_range(sc, &mp->m_icount, fsc->icount, 1024))
xchk_block_set_corrupt(sc, mp->m_sb_bp);
if (!xchk_fscounter_within_range(sc, &mp->m_ifree, fsc->ifree, 1024))
xchk_block_set_corrupt(sc, mp->m_sb_bp);
if (!xchk_fscounter_within_range(sc, &mp->m_fdblocks, fsc->fdblocks,
mp->m_sb.sb_dblocks >> 6))
xchk_block_set_corrupt(sc, mp->m_sb_bp);
return 0;
}
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