diff options
Diffstat (limited to 'fs/xfs/scrub/scrub.c')
| -rw-r--r-- | fs/xfs/scrub/scrub.c | 620 |
1 files changed, 620 insertions, 0 deletions
diff --git a/fs/xfs/scrub/scrub.c b/fs/xfs/scrub/scrub.c new file mode 100644 index 000000000..4849efcaa --- /dev/null +++ b/fs/xfs/scrub/scrub.c @@ -0,0 +1,620 @@ +// 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_log_format.h" +#include "xfs_trans.h" +#include "xfs_inode.h" +#include "xfs_quota.h" +#include "xfs_qm.h" +#include "xfs_errortag.h" +#include "xfs_error.h" +#include "xfs_scrub.h" +#include "scrub/scrub.h" +#include "scrub/common.h" +#include "scrub/trace.h" +#include "scrub/repair.h" +#include "scrub/health.h" +#include "scrub/stats.h" +#include "scrub/xfile.h" + +/* + * Online Scrub and Repair + * + * Traditionally, XFS (the kernel driver) did not know how to check or + * repair on-disk data structures. That task was left to the xfs_check + * and xfs_repair tools, both of which require taking the filesystem + * offline for a thorough but time consuming examination. Online + * scrub & repair, on the other hand, enables us to check the metadata + * for obvious errors while carefully stepping around the filesystem's + * ongoing operations, locking rules, etc. + * + * Given that most XFS metadata consist of records stored in a btree, + * most of the checking functions iterate the btree blocks themselves + * looking for irregularities. When a record block is encountered, each + * record can be checked for obviously bad values. Record values can + * also be cross-referenced against other btrees to look for potential + * misunderstandings between pieces of metadata. + * + * It is expected that the checkers responsible for per-AG metadata + * structures will lock the AG headers (AGI, AGF, AGFL), iterate the + * metadata structure, and perform any relevant cross-referencing before + * unlocking the AG and returning the results to userspace. These + * scrubbers must not keep an AG locked for too long to avoid tying up + * the block and inode allocators. + * + * Block maps and b-trees rooted in an inode present a special challenge + * because they can involve extents from any AG. The general scrubber + * structure of lock -> check -> xref -> unlock still holds, but AG + * locking order rules /must/ be obeyed to avoid deadlocks. The + * ordering rule, of course, is that we must lock in increasing AG + * order. Helper functions are provided to track which AG headers we've + * already locked. If we detect an imminent locking order violation, we + * can signal a potential deadlock, in which case the scrubber can jump + * out to the top level, lock all the AGs in order, and retry the scrub. + * + * For file data (directories, extended attributes, symlinks) scrub, we + * can simply lock the inode and walk the data. For btree data + * (directories and attributes) we follow the same btree-scrubbing + * strategy outlined previously to check the records. + * + * We use a bit of trickery with transactions to avoid buffer deadlocks + * if there is a cycle in the metadata. The basic problem is that + * travelling down a btree involves locking the current buffer at each + * tree level. If a pointer should somehow point back to a buffer that + * we've already examined, we will deadlock due to the second buffer + * locking attempt. Note however that grabbing a buffer in transaction + * context links the locked buffer to the transaction. If we try to + * re-grab the buffer in the context of the same transaction, we avoid + * the second lock attempt and continue. Between the verifier and the + * scrubber, something will notice that something is amiss and report + * the corruption. Therefore, each scrubber will allocate an empty + * transaction, attach buffers to it, and cancel the transaction at the + * end of the scrub run. Cancelling a non-dirty transaction simply + * unlocks the buffers. + * + * There are four pieces of data that scrub can communicate to + * userspace. The first is the error code (errno), which can be used to + * communicate operational errors in performing the scrub. There are + * also three flags that can be set in the scrub context. If the data + * structure itself is corrupt, the CORRUPT flag will be set. If + * the metadata is correct but otherwise suboptimal, the PREEN flag + * will be set. + * + * We perform secondary validation of filesystem metadata by + * cross-referencing every record with all other available metadata. + * For example, for block mapping extents, we verify that there are no + * records in the free space and inode btrees corresponding to that + * space extent and that there is a corresponding entry in the reverse + * mapping btree. Inconsistent metadata is noted by setting the + * XCORRUPT flag; btree query function errors are noted by setting the + * XFAIL flag and deleting the cursor to prevent further attempts to + * cross-reference with a defective btree. + * + * If a piece of metadata proves corrupt or suboptimal, the userspace + * program can ask the kernel to apply some tender loving care (TLC) to + * the metadata object by setting the REPAIR flag and re-calling the + * scrub ioctl. "Corruption" is defined by metadata violating the + * on-disk specification; operations cannot continue if the violation is + * left untreated. It is possible for XFS to continue if an object is + * "suboptimal", however performance may be degraded. Repairs are + * usually performed by rebuilding the metadata entirely out of + * redundant metadata. Optimizing, on the other hand, can sometimes be + * done without rebuilding entire structures. + * + * Generally speaking, the repair code has the following code structure: + * Lock -> scrub -> repair -> commit -> re-lock -> re-scrub -> unlock. + * The first check helps us figure out if we need to rebuild or simply + * optimize the structure so that the rebuild knows what to do. The + * second check evaluates the completeness of the repair; that is what + * is reported to userspace. + * + * A quick note on symbol prefixes: + * - "xfs_" are general XFS symbols. + * - "xchk_" are symbols related to metadata checking. + * - "xrep_" are symbols related to metadata repair. + * - "xfs_scrub_" are symbols that tie online fsck to the rest of XFS. + */ + +/* + * Scrub probe -- userspace uses this to probe if we're willing to scrub + * or repair a given mountpoint. This will be used by xfs_scrub to + * probe the kernel's abilities to scrub (and repair) the metadata. We + * do this by validating the ioctl inputs from userspace, preparing the + * filesystem for a scrub (or a repair) operation, and immediately + * returning to userspace. Userspace can use the returned errno and + * structure state to decide (in broad terms) if scrub/repair are + * supported by the running kernel. + */ +static int +xchk_probe( + struct xfs_scrub *sc) +{ + int error = 0; + + if (xchk_should_terminate(sc, &error)) + return error; + + return 0; +} + +/* Scrub setup and teardown */ + +static inline void +xchk_fsgates_disable( + struct xfs_scrub *sc) +{ + if (!(sc->flags & XCHK_FSGATES_ALL)) + return; + + trace_xchk_fsgates_disable(sc, sc->flags & XCHK_FSGATES_ALL); + + if (sc->flags & XCHK_FSGATES_DRAIN) + xfs_drain_wait_disable(); + + sc->flags &= ~XCHK_FSGATES_ALL; +} + +/* Free all the resources and finish the transactions. */ +STATIC int +xchk_teardown( + struct xfs_scrub *sc, + int error) +{ + xchk_ag_free(sc, &sc->sa); + if (sc->tp) { + if (error == 0 && (sc->sm->sm_flags & XFS_SCRUB_IFLAG_REPAIR)) + error = xfs_trans_commit(sc->tp); + else + xfs_trans_cancel(sc->tp); + sc->tp = NULL; + } + if (sc->ip) { + if (sc->ilock_flags) + xchk_iunlock(sc, sc->ilock_flags); + xchk_irele(sc, sc->ip); + sc->ip = NULL; + } + if (sc->flags & XCHK_HAVE_FREEZE_PROT) { + sc->flags &= ~XCHK_HAVE_FREEZE_PROT; + mnt_drop_write_file(sc->file); + } + if (sc->xfile) { + xfile_destroy(sc->xfile); + sc->xfile = NULL; + } + if (sc->buf) { + if (sc->buf_cleanup) + sc->buf_cleanup(sc->buf); + kvfree(sc->buf); + sc->buf_cleanup = NULL; + sc->buf = NULL; + } + + xchk_fsgates_disable(sc); + return error; +} + +/* Scrubbing dispatch. */ + +static const struct xchk_meta_ops meta_scrub_ops[] = { + [XFS_SCRUB_TYPE_PROBE] = { /* ioctl presence test */ + .type = ST_NONE, + .setup = xchk_setup_fs, + .scrub = xchk_probe, + .repair = xrep_probe, + }, + [XFS_SCRUB_TYPE_SB] = { /* superblock */ + .type = ST_PERAG, + .setup = xchk_setup_agheader, + .scrub = xchk_superblock, + .repair = xrep_superblock, + }, + [XFS_SCRUB_TYPE_AGF] = { /* agf */ + .type = ST_PERAG, + .setup = xchk_setup_agheader, + .scrub = xchk_agf, + .repair = xrep_agf, + }, + [XFS_SCRUB_TYPE_AGFL]= { /* agfl */ + .type = ST_PERAG, + .setup = xchk_setup_agheader, + .scrub = xchk_agfl, + .repair = xrep_agfl, + }, + [XFS_SCRUB_TYPE_AGI] = { /* agi */ + .type = ST_PERAG, + .setup = xchk_setup_agheader, + .scrub = xchk_agi, + .repair = xrep_agi, + }, + [XFS_SCRUB_TYPE_BNOBT] = { /* bnobt */ + .type = ST_PERAG, + .setup = xchk_setup_ag_allocbt, + .scrub = xchk_bnobt, + .repair = xrep_notsupported, + }, + [XFS_SCRUB_TYPE_CNTBT] = { /* cntbt */ + .type = ST_PERAG, + .setup = xchk_setup_ag_allocbt, + .scrub = xchk_cntbt, + .repair = xrep_notsupported, + }, + [XFS_SCRUB_TYPE_INOBT] = { /* inobt */ + .type = ST_PERAG, + .setup = xchk_setup_ag_iallocbt, + .scrub = xchk_inobt, + .repair = xrep_notsupported, + }, + [XFS_SCRUB_TYPE_FINOBT] = { /* finobt */ + .type = ST_PERAG, + .setup = xchk_setup_ag_iallocbt, + .scrub = xchk_finobt, + .has = xfs_has_finobt, + .repair = xrep_notsupported, + }, + [XFS_SCRUB_TYPE_RMAPBT] = { /* rmapbt */ + .type = ST_PERAG, + .setup = xchk_setup_ag_rmapbt, + .scrub = xchk_rmapbt, + .has = xfs_has_rmapbt, + .repair = xrep_notsupported, + }, + [XFS_SCRUB_TYPE_REFCNTBT] = { /* refcountbt */ + .type = ST_PERAG, + .setup = xchk_setup_ag_refcountbt, + .scrub = xchk_refcountbt, + .has = xfs_has_reflink, + .repair = xrep_notsupported, + }, + [XFS_SCRUB_TYPE_INODE] = { /* inode record */ + .type = ST_INODE, + .setup = xchk_setup_inode, + .scrub = xchk_inode, + .repair = xrep_notsupported, + }, + [XFS_SCRUB_TYPE_BMBTD] = { /* inode data fork */ + .type = ST_INODE, + .setup = xchk_setup_inode_bmap, + .scrub = xchk_bmap_data, + .repair = xrep_notsupported, + }, + [XFS_SCRUB_TYPE_BMBTA] = { /* inode attr fork */ + .type = ST_INODE, + .setup = xchk_setup_inode_bmap, + .scrub = xchk_bmap_attr, + .repair = xrep_notsupported, + }, + [XFS_SCRUB_TYPE_BMBTC] = { /* inode CoW fork */ + .type = ST_INODE, + .setup = xchk_setup_inode_bmap, + .scrub = xchk_bmap_cow, + .repair = xrep_notsupported, + }, + [XFS_SCRUB_TYPE_DIR] = { /* directory */ + .type = ST_INODE, + .setup = xchk_setup_directory, + .scrub = xchk_directory, + .repair = xrep_notsupported, + }, + [XFS_SCRUB_TYPE_XATTR] = { /* extended attributes */ + .type = ST_INODE, + .setup = xchk_setup_xattr, + .scrub = xchk_xattr, + .repair = xrep_notsupported, + }, + [XFS_SCRUB_TYPE_SYMLINK] = { /* symbolic link */ + .type = ST_INODE, + .setup = xchk_setup_symlink, + .scrub = xchk_symlink, + .repair = xrep_notsupported, + }, + [XFS_SCRUB_TYPE_PARENT] = { /* parent pointers */ + .type = ST_INODE, + .setup = xchk_setup_parent, + .scrub = xchk_parent, + .repair = xrep_notsupported, + }, + [XFS_SCRUB_TYPE_RTBITMAP] = { /* realtime bitmap */ + .type = ST_FS, + .setup = xchk_setup_rtbitmap, + .scrub = xchk_rtbitmap, + .has = xfs_has_realtime, + .repair = xrep_notsupported, + }, + [XFS_SCRUB_TYPE_RTSUM] = { /* realtime summary */ + .type = ST_FS, + .setup = xchk_setup_rtsummary, + .scrub = xchk_rtsummary, + .has = xfs_has_realtime, + .repair = xrep_notsupported, + }, + [XFS_SCRUB_TYPE_UQUOTA] = { /* user quota */ + .type = ST_FS, + .setup = xchk_setup_quota, + .scrub = xchk_quota, + .repair = xrep_notsupported, + }, + [XFS_SCRUB_TYPE_GQUOTA] = { /* group quota */ + .type = ST_FS, + .setup = xchk_setup_quota, + .scrub = xchk_quota, + .repair = xrep_notsupported, + }, + [XFS_SCRUB_TYPE_PQUOTA] = { /* project quota */ + .type = ST_FS, + .setup = xchk_setup_quota, + .scrub = xchk_quota, + .repair = xrep_notsupported, + }, + [XFS_SCRUB_TYPE_FSCOUNTERS] = { /* fs summary counters */ + .type = ST_FS, + .setup = xchk_setup_fscounters, + .scrub = xchk_fscounters, + .repair = xrep_notsupported, + }, +}; + +static int +xchk_validate_inputs( + struct xfs_mount *mp, + struct xfs_scrub_metadata *sm) +{ + int error; + const struct xchk_meta_ops *ops; + + error = -EINVAL; + /* Check our inputs. */ + sm->sm_flags &= ~XFS_SCRUB_FLAGS_OUT; + if (sm->sm_flags & ~XFS_SCRUB_FLAGS_IN) + goto out; + /* sm_reserved[] must be zero */ + if (memchr_inv(sm->sm_reserved, 0, sizeof(sm->sm_reserved))) + goto out; + + error = -ENOENT; + /* Do we know about this type of metadata? */ + if (sm->sm_type >= XFS_SCRUB_TYPE_NR) + goto out; + ops = &meta_scrub_ops[sm->sm_type]; + if (ops->setup == NULL || ops->scrub == NULL) + goto out; + /* Does this fs even support this type of metadata? */ + if (ops->has && !ops->has(mp)) + goto out; + + error = -EINVAL; + /* restricting fields must be appropriate for type */ + switch (ops->type) { + case ST_NONE: + case ST_FS: + if (sm->sm_ino || sm->sm_gen || sm->sm_agno) + goto out; + break; + case ST_PERAG: + if (sm->sm_ino || sm->sm_gen || + sm->sm_agno >= mp->m_sb.sb_agcount) + goto out; + break; + case ST_INODE: + if (sm->sm_agno || (sm->sm_gen && !sm->sm_ino)) + goto out; + break; + default: + goto out; + } + + /* No rebuild without repair. */ + if ((sm->sm_flags & XFS_SCRUB_IFLAG_FORCE_REBUILD) && + !(sm->sm_flags & XFS_SCRUB_IFLAG_REPAIR)) + return -EINVAL; + + /* + * We only want to repair read-write v5+ filesystems. Defer the check + * for ops->repair until after our scrub confirms that we need to + * perform repairs so that we avoid failing due to not supporting + * repairing an object that doesn't need repairs. + */ + if (sm->sm_flags & XFS_SCRUB_IFLAG_REPAIR) { + error = -EOPNOTSUPP; + if (!xfs_has_crc(mp)) + goto out; + + error = -EROFS; + if (xfs_is_readonly(mp)) + goto out; + } + + error = 0; +out: + return error; +} + +#ifdef CONFIG_XFS_ONLINE_REPAIR +static inline void xchk_postmortem(struct xfs_scrub *sc) +{ + /* + * Userspace asked us to repair something, we repaired it, rescanned + * it, and the rescan says it's still broken. Scream about this in + * the system logs. + */ + if ((sc->sm->sm_flags & XFS_SCRUB_IFLAG_REPAIR) && + (sc->sm->sm_flags & (XFS_SCRUB_OFLAG_CORRUPT | + XFS_SCRUB_OFLAG_XCORRUPT))) + xrep_failure(sc->mp); +} +#else +static inline void xchk_postmortem(struct xfs_scrub *sc) +{ + /* + * Userspace asked us to scrub something, it's broken, and we have no + * way of fixing it. Scream in the logs. + */ + if (sc->sm->sm_flags & (XFS_SCRUB_OFLAG_CORRUPT | + XFS_SCRUB_OFLAG_XCORRUPT)) + xfs_alert_ratelimited(sc->mp, + "Corruption detected during scrub."); +} +#endif /* CONFIG_XFS_ONLINE_REPAIR */ + +/* Dispatch metadata scrubbing. */ +int +xfs_scrub_metadata( + struct file *file, + struct xfs_scrub_metadata *sm) +{ + struct xchk_stats_run run = { }; + struct xfs_scrub *sc; + struct xfs_mount *mp = XFS_I(file_inode(file))->i_mount; + u64 check_start; + int error = 0; + + BUILD_BUG_ON(sizeof(meta_scrub_ops) != + (sizeof(struct xchk_meta_ops) * XFS_SCRUB_TYPE_NR)); + + trace_xchk_start(XFS_I(file_inode(file)), sm, error); + + /* Forbidden if we are shut down or mounted norecovery. */ + error = -ESHUTDOWN; + if (xfs_is_shutdown(mp)) + goto out; + error = -ENOTRECOVERABLE; + if (xfs_has_norecovery(mp)) + goto out; + + error = xchk_validate_inputs(mp, sm); + if (error) + goto out; + + xfs_warn_mount(mp, XFS_OPSTATE_WARNED_SCRUB, + "EXPERIMENTAL online scrub feature in use. Use at your own risk!"); + + sc = kzalloc(sizeof(struct xfs_scrub), XCHK_GFP_FLAGS); + if (!sc) { + error = -ENOMEM; + goto out; + } + + sc->mp = mp; + sc->file = file; + sc->sm = sm; + sc->ops = &meta_scrub_ops[sm->sm_type]; + sc->sick_mask = xchk_health_mask_for_scrub_type(sm->sm_type); +retry_op: + /* + * When repairs are allowed, prevent freezing or readonly remount while + * scrub is running with a real transaction. + */ + if (sm->sm_flags & XFS_SCRUB_IFLAG_REPAIR) { + error = mnt_want_write_file(sc->file); + if (error) + goto out_sc; + + sc->flags |= XCHK_HAVE_FREEZE_PROT; + } + + /* Set up for the operation. */ + error = sc->ops->setup(sc); + if (error == -EDEADLOCK && !(sc->flags & XCHK_TRY_HARDER)) + goto try_harder; + if (error == -ECHRNG && !(sc->flags & XCHK_NEED_DRAIN)) + goto need_drain; + if (error) + goto out_teardown; + + /* Scrub for errors. */ + check_start = xchk_stats_now(); + error = sc->ops->scrub(sc); + run.scrub_ns += xchk_stats_elapsed_ns(check_start); + if (error == -EDEADLOCK && !(sc->flags & XCHK_TRY_HARDER)) + goto try_harder; + if (error == -ECHRNG && !(sc->flags & XCHK_NEED_DRAIN)) + goto need_drain; + if (error || (sm->sm_flags & XFS_SCRUB_OFLAG_INCOMPLETE)) + goto out_teardown; + + xchk_update_health(sc); + + if ((sc->sm->sm_flags & XFS_SCRUB_IFLAG_REPAIR) && + !(sc->flags & XREP_ALREADY_FIXED)) { + bool needs_fix = xchk_needs_repair(sc->sm); + + /* Userspace asked us to rebuild the structure regardless. */ + if (sc->sm->sm_flags & XFS_SCRUB_IFLAG_FORCE_REBUILD) + needs_fix = true; + + /* Let debug users force us into the repair routines. */ + if (XFS_TEST_ERROR(needs_fix, mp, XFS_ERRTAG_FORCE_SCRUB_REPAIR)) + needs_fix = true; + + /* + * If userspace asked for a repair but it wasn't necessary, + * report that back to userspace. + */ + if (!needs_fix) { + sc->sm->sm_flags |= XFS_SCRUB_OFLAG_NO_REPAIR_NEEDED; + goto out_nofix; + } + + /* + * If it's broken, userspace wants us to fix it, and we haven't + * already tried to fix it, then attempt a repair. + */ + error = xrep_attempt(sc, &run); + if (error == -EAGAIN) { + /* + * Either the repair function succeeded or it couldn't + * get all the resources it needs; either way, we go + * back to the beginning and call the scrub function. + */ + error = xchk_teardown(sc, 0); + if (error) { + xrep_failure(mp); + goto out_sc; + } + goto retry_op; + } + } + +out_nofix: + xchk_postmortem(sc); +out_teardown: + error = xchk_teardown(sc, error); +out_sc: + if (error != -ENOENT) + xchk_stats_merge(mp, sm, &run); + kfree(sc); +out: + trace_xchk_done(XFS_I(file_inode(file)), sm, error); + if (error == -EFSCORRUPTED || error == -EFSBADCRC) { + sm->sm_flags |= XFS_SCRUB_OFLAG_CORRUPT; + error = 0; + } + return error; +need_drain: + error = xchk_teardown(sc, 0); + if (error) + goto out_sc; + sc->flags |= XCHK_NEED_DRAIN; + run.retries++; + goto retry_op; +try_harder: + /* + * Scrubbers return -EDEADLOCK to mean 'try harder'. Tear down + * everything we hold, then set up again with preparation for + * worst-case scenarios. + */ + error = xchk_teardown(sc, 0); + if (error) + goto out_sc; + sc->flags |= XCHK_TRY_HARDER; + run.retries++; + goto retry_op; +} |