From e00e3099a6c5adc6d334e14424e9d936f4b9c3c3 Mon Sep 17 00:00:00 2001 From: "Darrick J. Wong" Date: Thu, 14 Jul 2022 11:06:20 -0700 Subject: xfs: teach repair to fix file nlinks Fix the nlinks now too. Signed-off-by: Darrick J. Wong --- fs/xfs/Makefile | 1 + fs/xfs/scrub/nlinks.c | 4 +- fs/xfs/scrub/nlinks.h | 5 +- fs/xfs/scrub/nlinks_repair.c | 225 +++++++++++++++++++++++++++++++++++++++++++ fs/xfs/scrub/repair.h | 2 + fs/xfs/scrub/scrub.c | 2 +- fs/xfs/scrub/trace.h | 3 + 7 files changed, 239 insertions(+), 3 deletions(-) create mode 100644 fs/xfs/scrub/nlinks_repair.c diff --git a/fs/xfs/Makefile b/fs/xfs/Makefile index 4902f6c2aaec..163800ee9109 100644 --- a/fs/xfs/Makefile +++ b/fs/xfs/Makefile @@ -187,6 +187,7 @@ xfs-y += $(addprefix scrub/, \ ialloc_repair.o \ inode_repair.o \ newbt.o \ + nlinks_repair.o \ reap.o \ refcount_repair.o \ repair.o \ diff --git a/fs/xfs/scrub/nlinks.c b/fs/xfs/scrub/nlinks.c index 9b15687386d8..2d75095a365a 100644 --- a/fs/xfs/scrub/nlinks.c +++ b/fs/xfs/scrub/nlinks.c @@ -60,7 +60,9 @@ xchk_setup_nlinks( * set the INCOMPLETE flag even when a negative errno is returned. This care * must be taken with certain errno values (i.e. EFSBADCRC, EFSCORRUPTED, * ECANCELED) that are absorbed into a scrub state flag update by - * xchk_*_process_error. + * xchk_*_process_error. Scrub and repair share the same incore data + * structures, so the INCOMPLETE flag is critical to prevent a repair based on + * insufficient information. * * Because we are scanning a live filesystem, it's possible that another thread * will try to update the link counts for an inode that we've already scanned. diff --git a/fs/xfs/scrub/nlinks.h b/fs/xfs/scrub/nlinks.h index 69cf556b15a3..46baef3c2237 100644 --- a/fs/xfs/scrub/nlinks.h +++ b/fs/xfs/scrub/nlinks.h @@ -81,9 +81,12 @@ struct xchk_nlink { */ #define XCHK_NLINK_WRITTEN (1U << 0) -/* This data item was seen by the check-time compare function. */ +/* Already checked this link count record. */ #define XCHK_NLINK_COMPARE_SCANNED (1U << 1) +/* Already made a repair with this link count record. */ +#define XREP_NLINK_DIRTY (1U << 2) + /* Compute total link count, using large enough variables to detect overflow. */ static inline uint64_t xchk_nlink_total(const struct xchk_nlink *live) diff --git a/fs/xfs/scrub/nlinks_repair.c b/fs/xfs/scrub/nlinks_repair.c new file mode 100644 index 000000000000..48a5e532ffb8 --- /dev/null +++ b/fs/xfs/scrub/nlinks_repair.c @@ -0,0 +1,225 @@ +// SPDX-License-Identifier: GPL-2.0-or-later +/* + * Copyright (C) 2022 Oracle. All Rights Reserved. + * Author: Darrick J. Wong + */ +#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_log_format.h" +#include "xfs_trans.h" +#include "xfs_inode.h" +#include "xfs_icache.h" +#include "xfs_bmap_util.h" +#include "xfs_iwalk.h" +#include "xfs_ialloc.h" +#include "xfs_sb.h" +#include "scrub/scrub.h" +#include "scrub/common.h" +#include "scrub/repair.h" +#include "scrub/xfarray.h" +#include "scrub/iscan.h" +#include "scrub/nlinks.h" +#include "scrub/trace.h" + +/* + * Live Inode Link Count Repair + * ============================ + * + * Use the live inode link count information that we collected to replace the + * nlink values of the incore inodes. A scrub->repair cycle should have left + * the live data and hooks active, so this is safe so long as we make sure the + * inode is locked. + */ + +/* + * Correct the link count of the given inode. Because we have to grab locks + * and resources in a certain order, it's possible that this will be a no-op. + */ +STATIC int +xrep_nlinks_repair_inode( + struct xchk_nlink_ctrs *xnc) +{ + struct xchk_nlink obs; + struct xfs_scrub *sc = xnc->sc; + struct xfs_mount *mp = sc->mp; + struct xfs_inode *ip = sc->ip; + uint64_t total_links; + unsigned int actual_nlink; + int error; + + xfs_ilock(ip, XFS_IOLOCK_EXCL); + + error = xfs_trans_alloc(mp, &M_RES(mp)->tr_link, 0, 0, 0, &sc->tp); + if (error) + goto out_iolock; + + xfs_ilock(ip, XFS_ILOCK_EXCL); + xfs_trans_ijoin(sc->tp, ip, 0); + + mutex_lock(&xnc->lock); + + if (xchk_iscan_aborted(&xnc->collect_iscan)) { + error = -ECANCELED; + goto out_scanlock; + } + + error = xfarray_load_sparse(xnc->nlinks, ip->i_ino, &obs); + if (error) + goto out_scanlock; + + total_links = xchk_nlink_total(&obs); + actual_nlink = VFS_I(ip)->i_nlink; + + /* + * Cannot set more than the maxiumum possible link count. We won't + * touch this file, but we don't want to abort the entire operation, + * so set an explicit error value to avoid static checker warnings and + * return early. + */ + if (total_links > U32_MAX) { + trace_xrep_nlinks_unfixable_inode(mp, ip, &obs); + goto out_nextfile; + } + + /* + * Linked directories should have at least one "child" (the dot entry) + * pointing up to them. + */ + if (S_ISDIR(VFS_I(ip)->i_mode) && actual_nlink > 0 && + obs.children == 0) { + trace_xrep_nlinks_unfixable_inode(mp, ip, &obs); + goto out_nextfile; + } + + /* Non-directories cannot have directories pointing up to them. */ + if (!S_ISDIR(VFS_I(ip)->i_mode) && obs.children != 0) { + trace_xrep_nlinks_unfixable_inode(mp, ip, &obs); + goto out_nextfile; + } + + /* + * We did not find any links to this inode. If the inode agrees, we + * have nothing further to do. If not, the inode has a nonzero link + * count and we don't have anywhere to graft the child onto. Dropping + * a live inode's link count to zero can cause unexpected shutdowns in + * inactivation, so leave it alone. + */ + if (total_links == 0) { + if (actual_nlink != 0) + trace_xrep_nlinks_unfixable_inode(mp, ip, &obs); + goto out_nextfile; + } + + /* Perfect match means we're done with this file. */ + if (total_links == actual_nlink) + goto out_nextfile; + + mutex_unlock(&xnc->lock); + + /* Commit the new link count. */ + trace_xrep_nlinks_update_inode(mp, ip, &obs); + + set_nlink(VFS_I(ip), total_links); + xfs_trans_log_inode(sc->tp, ip, XFS_ILOG_CORE); + error = xfs_trans_commit(sc->tp); + sc->tp = NULL; + if (error) + goto out_ilock; + + xfs_iunlock(ip, XFS_ILOCK_EXCL); + xfs_iunlock(ip, XFS_IOLOCK_EXCL); + return 0; + +out_nextfile: + error = 0; +out_scanlock: + mutex_unlock(&xnc->lock); + xchk_trans_cancel(sc); +out_ilock: + xfs_iunlock(ip, XFS_ILOCK_EXCL); +out_iolock: + xfs_iunlock(ip, XFS_IOLOCK_EXCL); + return error; +} + +/* + * Try to visit every inode in the filesystem for repairs. Move on if we can't + * grab an inode, since we're still making forward progress. + */ +static int +xrep_nlinks_iter( + struct xchk_nlink_ctrs *xnc, + struct xfs_inode **ipp) +{ + int error; + + do { + error = xchk_iscan_iter(xnc->sc, &xnc->compare_iscan, ipp); + } while (error == -EBUSY); + + return error; +} + +/* Commit the new inode link counters. */ +int +xrep_nlinks( + struct xfs_scrub *sc) +{ + struct xchk_nlink_ctrs *xnc = sc->buf; + int error; + + /* + * We need ftype for an accurate count of the number of child + * subdirectory links. Child subdirectories with a back link (dotdot + * entry) but no forward link are unfixable, so we cannot repair the + * link count of the parent directory based on the back link count + * alone. Filesystems without ftype support are rare (old V4) so we + * just skip out here. + */ + if (!xfs_has_ftype(sc->mp)) + return -EOPNOTSUPP; + + /* + * Use the inobt to walk all allocated inodes to compare and fix the + * link counts. Retry iget every tenth of a second for up to 30 + * seconds -- even if repair misses a few inodes, we still try to fix + * as many of them as we can. + */ + xchk_iscan_start(&xnc->compare_iscan, 30000, 100); + ASSERT(sc->ip == NULL); + + while ((error = xrep_nlinks_iter(xnc, &sc->ip)) == 1) { + /* + * Commit the scrub transaction so that we can create repair + * transactions with the correct reservations. + */ + xchk_trans_cancel(sc); + + error = xrep_nlinks_repair_inode(xnc); + xchk_iscan_mark_visited(&xnc->compare_iscan, sc->ip); + xchk_irele(sc, sc->ip); + sc->ip = NULL; + if (error) + break; + + if (xchk_should_terminate(sc, &error)) + break; + + /* + * Create a new empty transaction so that we can advance the + * iscan cursor without deadlocking if the inobt has a cycle. + * We can only push the inactivation workqueues with an empty + * transaction. + */ + error = xchk_trans_alloc_empty(sc); + if (error) + break; + } + xchk_iscan_finish(&xnc->compare_iscan); + + return error; +} diff --git a/fs/xfs/scrub/repair.h b/fs/xfs/scrub/repair.h index 859fba69bd8c..d6aedcbc4e25 100644 --- a/fs/xfs/scrub/repair.h +++ b/fs/xfs/scrub/repair.h @@ -107,6 +107,7 @@ int xrep_inode(struct xfs_scrub *sc); int xrep_bmap_data(struct xfs_scrub *sc); int xrep_bmap_attr(struct xfs_scrub *sc); int xrep_bmap_cow(struct xfs_scrub *sc); +int xrep_nlinks(struct xfs_scrub *sc); #ifdef CONFIG_XFS_RT int xrep_rtbitmap(struct xfs_scrub *sc); @@ -190,6 +191,7 @@ static inline int xrep_setup_rtbitmap(struct xfs_scrub *sc, unsigned int *x) #define xrep_rtbitmap xrep_notsupported #define xrep_quota xrep_notsupported #define xrep_quotacheck xrep_notsupported +#define xrep_nlinks xrep_notsupported #endif /* CONFIG_XFS_ONLINE_REPAIR */ diff --git a/fs/xfs/scrub/scrub.c b/fs/xfs/scrub/scrub.c index 7e06aa98ca82..2c05fbde1f88 100644 --- a/fs/xfs/scrub/scrub.c +++ b/fs/xfs/scrub/scrub.c @@ -379,7 +379,7 @@ static const struct xchk_meta_ops meta_scrub_ops[] = { .type = ST_FS, .setup = xchk_setup_nlinks, .scrub = xchk_nlinks, - .repair = xrep_notsupported, + .repair = xrep_nlinks, }, }; diff --git a/fs/xfs/scrub/trace.h b/fs/xfs/scrub/trace.h index 2457c2de930c..b1184e3f71b4 100644 --- a/fs/xfs/scrub/trace.h +++ b/fs/xfs/scrub/trace.h @@ -1922,6 +1922,9 @@ DEFINE_XREP_DQUOT_EVENT(xrep_disk_dquot); DEFINE_XREP_DQUOT_EVENT(xrep_quotacheck_dquot); #endif /* CONFIG_XFS_QUOTA */ +DEFINE_SCRUB_NLINKS_DIFF_EVENT(xrep_nlinks_update_inode); +DEFINE_SCRUB_NLINKS_DIFF_EVENT(xrep_nlinks_unfixable_inode); + #endif /* IS_ENABLED(CONFIG_XFS_ONLINE_REPAIR) */ #endif /* _TRACE_XFS_SCRUB_TRACE_H */ -- cgit v1.2.3