diff options
Diffstat (limited to 'fs/xfs/scrub/fscounters.c')
| -rw-r--r-- | fs/xfs/scrub/fscounters.c | 188 |
1 files changed, 151 insertions, 37 deletions
diff --git a/fs/xfs/scrub/fscounters.c b/fs/xfs/scrub/fscounters.c index e382a35e98d8..05be757668bb 100644 --- a/fs/xfs/scrub/fscounters.c +++ b/fs/xfs/scrub/fscounters.c @@ -1,4 +1,4 @@ -// SPDX-License-Identifier: GPL-2.0+ +// SPDX-License-Identifier: GPL-2.0-or-later /* * Copyright (C) 2019-2023 Oracle. All Rights Reserved. * Author: Darrick J. Wong <djwong@kernel.org> @@ -8,6 +8,8 @@ #include "xfs_shared.h" #include "xfs_format.h" #include "xfs_trans_resv.h" +#include "xfs_log_format.h" +#include "xfs_trans.h" #include "xfs_mount.h" #include "xfs_alloc.h" #include "xfs_ialloc.h" @@ -16,6 +18,7 @@ #include "xfs_ag.h" #include "xfs_rtalloc.h" #include "xfs_inode.h" +#include "xfs_icache.h" #include "scrub/scrub.h" #include "scrub/common.h" #include "scrub/trace.h" @@ -53,6 +56,7 @@ struct xchk_fscounters { uint64_t frextents; unsigned long long icount_min; unsigned long long icount_max; + bool frozen; }; /* @@ -123,6 +127,82 @@ xchk_fscount_warmup( return error; } +static inline int +xchk_fsfreeze( + struct xfs_scrub *sc) +{ + int error; + + error = freeze_super(sc->mp->m_super, FREEZE_HOLDER_KERNEL); + trace_xchk_fsfreeze(sc, error); + return error; +} + +static inline int +xchk_fsthaw( + struct xfs_scrub *sc) +{ + int error; + + /* This should always succeed, we have a kernel freeze */ + error = thaw_super(sc->mp->m_super, FREEZE_HOLDER_KERNEL); + trace_xchk_fsthaw(sc, error); + return error; +} + +/* + * We couldn't stabilize the filesystem long enough to sample all the variables + * that comprise the summary counters and compare them to the percpu counters. + * We need to disable all writer threads, which means taking the first two + * freeze levels to put userspace to sleep, and the third freeze level to + * prevent background threads from starting new transactions. Take one level + * more to prevent other callers from unfreezing the filesystem while we run. + */ +STATIC int +xchk_fscounters_freeze( + struct xfs_scrub *sc) +{ + struct xchk_fscounters *fsc = sc->buf; + int error = 0; + + if (sc->flags & XCHK_HAVE_FREEZE_PROT) { + sc->flags &= ~XCHK_HAVE_FREEZE_PROT; + mnt_drop_write_file(sc->file); + } + + /* Try to grab a kernel freeze. */ + while ((error = xchk_fsfreeze(sc)) == -EBUSY) { + if (xchk_should_terminate(sc, &error)) + return error; + + delay(HZ / 10); + } + if (error) + return error; + + fsc->frozen = true; + return 0; +} + +/* Thaw the filesystem after checking or repairing fscounters. */ +STATIC void +xchk_fscounters_cleanup( + void *buf) +{ + struct xchk_fscounters *fsc = buf; + struct xfs_scrub *sc = fsc->sc; + int error; + + if (!fsc->frozen) + return; + + error = xchk_fsthaw(sc); + if (error) + xfs_emerg(sc->mp, "still frozen after scrub, err=%d", error); + else + fsc->frozen = false; +} + int xchk_setup_fscounters( struct xfs_scrub *sc) @@ -140,6 +220,7 @@ xchk_setup_fscounters( sc->buf = kzalloc(sizeof(struct xchk_fscounters), XCHK_GFP_FLAGS); if (!sc->buf) return -ENOMEM; + sc->buf_cleanup = xchk_fscounters_cleanup; fsc = sc->buf; fsc->sc = sc; @@ -150,7 +231,18 @@ xchk_setup_fscounters( if (error) return error; - return xchk_trans_alloc(sc, 0); + /* + * Pause all writer activity in the filesystem while we're scrubbing to + * reduce the likelihood of background perturbations to the counters + * throwing off our calculations. + */ + if (sc->flags & XCHK_TRY_HARDER) { + error = xchk_fscounters_freeze(sc); + if (error) + return error; + } + + return xfs_trans_alloc_empty(sc->mp, &sc->tp); } /* @@ -290,8 +382,7 @@ retry: if (fsc->ifree > fsc->icount) { if (tries--) goto retry; - xchk_set_incomplete(sc); - return 0; + return -EDEADLOCK; } return 0; @@ -367,6 +458,8 @@ xchk_fscount_count_frextents( * Otherwise, we /might/ have a problem. If the change in the summations is * more than we want to tolerate, the filesystem is probably busy and we should * just send back INCOMPLETE and see if userspace will try again. + * + * If we're repairing then we require an exact match. */ static inline bool xchk_fscount_within_range( @@ -396,21 +489,7 @@ xchk_fscount_within_range( if (expected >= min_value && expected <= max_value) return true; - /* - * If the difference between the two summations is too large, the fs - * might just be busy and so we'll mark the scrub incomplete. Return - * true here so that we don't mark the counter corrupt. - * - * XXX: In the future when userspace can grant scrub permission to - * quiesce the filesystem to solve the outsized variance problem, this - * check should be moved up and the return code changed to signal to - * userspace that we need quiesce permission. - */ - if (max_value - min_value >= XCHK_FSCOUNT_MIN_VARIANCE) { - xchk_set_incomplete(sc); - return true; - } - + /* Everything else is bad. */ return false; } @@ -422,6 +501,7 @@ xchk_fscounters( struct xfs_mount *mp = sc->mp; struct xchk_fscounters *fsc = sc->buf; int64_t icount, ifree, fdblocks, frextents; + bool try_again = false; int error; /* Snapshot the percpu counters. */ @@ -431,9 +511,26 @@ xchk_fscounters( frextents = percpu_counter_sum(&mp->m_frextents); /* No negative values, please! */ - if (icount < 0 || ifree < 0 || fdblocks < 0 || frextents < 0) + if (icount < 0 || ifree < 0) xchk_set_corrupt(sc); + /* + * If the filesystem is not frozen, the counter summation calls above + * can race with xfs_mod_freecounter, which subtracts a requested space + * reservation from the counter and undoes the subtraction if that made + * the counter go negative. Therefore, it's possible to see negative + * values here, and we should only flag that as a corruption if we + * froze the fs. This is much more likely to happen with frextents + * since there are no reserved pools. + */ + if (fdblocks < 0 || frextents < 0) { + if (!fsc->frozen) + return -EDEADLOCK; + + xchk_set_corrupt(sc); + return 0; + } + /* See if icount is obviously wrong. */ if (icount < fsc->icount_min || icount > fsc->icount_max) xchk_set_corrupt(sc); @@ -447,12 +544,6 @@ xchk_fscounters( xchk_set_corrupt(sc); /* - * XXX: We can't quiesce percpu counter updates, so exit early. - * This can be re-enabled when we gain exclusive freeze functionality. - */ - return 0; - - /* * If ifree exceeds icount by more than the minimum variance then * something's probably wrong with the counters. */ @@ -463,8 +554,6 @@ xchk_fscounters( error = xchk_fscount_aggregate_agcounts(sc, fsc); if (!xchk_process_error(sc, 0, XFS_SB_BLOCK(mp), &error)) return error; - if (sc->sm->sm_flags & XFS_SCRUB_OFLAG_INCOMPLETE) - return 0; /* Count the free extents counter for rt volumes. */ error = xchk_fscount_count_frextents(sc, fsc); @@ -473,20 +562,45 @@ xchk_fscounters( if (sc->sm->sm_flags & XFS_SCRUB_OFLAG_INCOMPLETE) return 0; - /* Compare the in-core counters with whatever we counted. */ - if (!xchk_fscount_within_range(sc, icount, &mp->m_icount, fsc->icount)) - xchk_set_corrupt(sc); + /* + * Compare the in-core counters with whatever we counted. If the fs is + * frozen, we treat the discrepancy as a corruption because the freeze + * should have stabilized the counter values. Otherwise, we need + * userspace to call us back having granted us freeze permission. + */ + if (!xchk_fscount_within_range(sc, icount, &mp->m_icount, + fsc->icount)) { + if (fsc->frozen) + xchk_set_corrupt(sc); + else + try_again = true; + } - if (!xchk_fscount_within_range(sc, ifree, &mp->m_ifree, fsc->ifree)) - xchk_set_corrupt(sc); + if (!xchk_fscount_within_range(sc, ifree, &mp->m_ifree, fsc->ifree)) { + if (fsc->frozen) + xchk_set_corrupt(sc); + else + try_again = true; + } if (!xchk_fscount_within_range(sc, fdblocks, &mp->m_fdblocks, - fsc->fdblocks)) - xchk_set_corrupt(sc); + fsc->fdblocks)) { + if (fsc->frozen) + xchk_set_corrupt(sc); + else + try_again = true; + } if (!xchk_fscount_within_range(sc, frextents, &mp->m_frextents, - fsc->frextents)) - xchk_set_corrupt(sc); + fsc->frextents)) { + if (fsc->frozen) + xchk_set_corrupt(sc); + else + try_again = true; + } + + if (try_again) + return -EDEADLOCK; return 0; } |