// SPDX-License-Identifier: GPL-2.0+
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/*
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* Copyright (C) 2017 Oracle. All Rights Reserved.
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* Author: Darrick J. Wong <darrick.wong@oracle.com>
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*/
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#include "xfs.h"
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#include "xfs_fs.h"
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#include "xfs_shared.h"
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#include "xfs_format.h"
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#include "xfs_trans_resv.h"
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#include "xfs_mount.h"
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#include "xfs_log_format.h"
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#include "xfs_trans.h"
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#include "xfs_inode.h"
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#include "xfs_quota.h"
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#include "xfs_qm.h"
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#include "xfs_errortag.h"
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#include "xfs_error.h"
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#include "xfs_scrub.h"
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#include "scrub/scrub.h"
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#include "scrub/common.h"
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#include "scrub/trace.h"
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#include "scrub/repair.h"
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#include "scrub/health.h"
|
|
/*
|
* Online Scrub and Repair
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*
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* 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
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* scrub & repair, on the other hand, enables us to check the metadata
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* for obvious errors while carefully stepping around the filesystem's
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* ongoing operations, locking rules, etc.
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*
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* Given that most XFS metadata consist of records stored in a btree,
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* most of the checking functions iterate the btree blocks themselves
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* looking for irregularities. When a record block is encountered, each
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* record can be checked for obviously bad values. Record values can
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* also be cross-referenced against other btrees to look for potential
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* misunderstandings between pieces of metadata.
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*
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* It is expected that the checkers responsible for per-AG metadata
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* structures will lock the AG headers (AGI, AGF, AGFL), iterate the
|
* metadata structure, and perform any relevant cross-referencing before
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* unlocking the AG and returning the results to userspace. These
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* scrubbers must not keep an AG locked for too long to avoid tying up
|
* the block and inode allocators.
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*
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* 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
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* 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.
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*
|
* 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
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* the corruption. Therefore, each scrubber will allocate an empty
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* transaction, attach buffers to it, and cancel the transaction at the
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* end of the scrub run. Cancelling a non-dirty transaction simply
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* unlocks the buffers.
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*
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* There are four pieces of data that scrub can communicate to
|
* userspace. The first is the error code (errno), which can be used to
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* communicate operational errors in performing the scrub. There are
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* also three flags that can be set in the scrub context. If the data
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* structure itself is corrupt, the CORRUPT flag will be set. If
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* the metadata is correct but otherwise suboptimal, the PREEN flag
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* will be set.
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*
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* We perform secondary validation of filesystem metadata by
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* cross-referencing every record with all other available metadata.
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* For example, for block mapping extents, we verify that there are no
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* 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
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* XCORRUPT flag; btree query function errors are noted by setting the
|
* XFAIL flag and deleting the cursor to prevent further attempts to
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* cross-reference with a defective btree.
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*
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* 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.
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*
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* Generally speaking, the repair code has the following code structure:
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* 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.
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*
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* A quick note on symbol prefixes:
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* - "xfs_" are general XFS symbols.
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* - "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
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* probe the kernel's abilities to scrub (and repair) the metadata. We
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* 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.
|
*/
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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 */
|
|
/* Free all the resources and finish the transactions. */
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STATIC int
|
xchk_teardown(
|
struct xfs_scrub *sc,
|
struct xfs_inode *ip_in,
|
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;
|
}
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if (sc->ip) {
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if (sc->ilock_flags)
|
xfs_iunlock(sc->ip, sc->ilock_flags);
|
if (sc->ip != ip_in &&
|
!xfs_internal_inum(sc->mp, sc->ip->i_ino))
|
xfs_irele(sc->ip);
|
sc->ip = NULL;
|
}
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sb_end_write(sc->mp->m_super);
|
if (sc->flags & XCHK_REAPING_DISABLED)
|
xchk_start_reaping(sc);
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if (sc->flags & XCHK_HAS_QUOTAOFFLOCK) {
|
mutex_unlock(&sc->mp->m_quotainfo->qi_quotaofflock);
|
sc->flags &= ~XCHK_HAS_QUOTAOFFLOCK;
|
}
|
if (sc->buf) {
|
kmem_free(sc->buf);
|
sc->buf = NULL;
|
}
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return error;
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}
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/* Scrubbing dispatch. */
|
|
static const struct xchk_meta_ops meta_scrub_ops[] = {
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[XFS_SCRUB_TYPE_PROBE] = { /* ioctl presence test */
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.type = ST_NONE,
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.setup = xchk_setup_fs,
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.scrub = xchk_probe,
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.repair = xrep_probe,
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},
|
[XFS_SCRUB_TYPE_SB] = { /* superblock */
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.type = ST_PERAG,
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.setup = xchk_setup_fs,
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.scrub = xchk_superblock,
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.repair = xrep_superblock,
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},
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[XFS_SCRUB_TYPE_AGF] = { /* agf */
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.type = ST_PERAG,
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.setup = xchk_setup_fs,
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.scrub = xchk_agf,
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.repair = xrep_agf,
|
},
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[XFS_SCRUB_TYPE_AGFL]= { /* agfl */
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.type = ST_PERAG,
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.setup = xchk_setup_fs,
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.scrub = xchk_agfl,
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.repair = xrep_agfl,
|
},
|
[XFS_SCRUB_TYPE_AGI] = { /* agi */
|
.type = ST_PERAG,
|
.setup = xchk_setup_fs,
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.scrub = xchk_agi,
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.repair = xrep_agi,
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},
|
[XFS_SCRUB_TYPE_BNOBT] = { /* bnobt */
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.type = ST_PERAG,
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.setup = xchk_setup_ag_allocbt,
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.scrub = xchk_bnobt,
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.repair = xrep_notsupported,
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},
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[XFS_SCRUB_TYPE_CNTBT] = { /* cntbt */
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.type = ST_PERAG,
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.setup = xchk_setup_ag_allocbt,
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.scrub = xchk_cntbt,
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.repair = xrep_notsupported,
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},
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[XFS_SCRUB_TYPE_INOBT] = { /* inobt */
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.type = ST_PERAG,
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.setup = xchk_setup_ag_iallocbt,
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.scrub = xchk_inobt,
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.repair = xrep_notsupported,
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},
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[XFS_SCRUB_TYPE_FINOBT] = { /* finobt */
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.type = ST_PERAG,
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.setup = xchk_setup_ag_iallocbt,
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.scrub = xchk_finobt,
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.has = xfs_sb_version_hasfinobt,
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.repair = xrep_notsupported,
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},
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[XFS_SCRUB_TYPE_RMAPBT] = { /* rmapbt */
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.type = ST_PERAG,
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.setup = xchk_setup_ag_rmapbt,
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.scrub = xchk_rmapbt,
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.has = xfs_sb_version_hasrmapbt,
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.repair = xrep_notsupported,
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},
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[XFS_SCRUB_TYPE_REFCNTBT] = { /* refcountbt */
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.type = ST_PERAG,
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.setup = xchk_setup_ag_refcountbt,
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.scrub = xchk_refcountbt,
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.has = xfs_sb_version_hasreflink,
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.repair = xrep_notsupported,
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},
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[XFS_SCRUB_TYPE_INODE] = { /* inode record */
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.type = ST_INODE,
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.setup = xchk_setup_inode,
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.scrub = xchk_inode,
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.repair = xrep_notsupported,
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},
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[XFS_SCRUB_TYPE_BMBTD] = { /* inode data fork */
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.type = ST_INODE,
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.setup = xchk_setup_inode_bmap,
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.scrub = xchk_bmap_data,
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.repair = xrep_notsupported,
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},
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[XFS_SCRUB_TYPE_BMBTA] = { /* inode attr fork */
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.type = ST_INODE,
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.setup = xchk_setup_inode_bmap,
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.scrub = xchk_bmap_attr,
|
.repair = xrep_notsupported,
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},
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[XFS_SCRUB_TYPE_BMBTC] = { /* inode CoW fork */
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.type = ST_INODE,
|
.setup = xchk_setup_inode_bmap,
|
.scrub = xchk_bmap_cow,
|
.repair = xrep_notsupported,
|
},
|
[XFS_SCRUB_TYPE_DIR] = { /* directory */
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.type = ST_INODE,
|
.setup = xchk_setup_directory,
|
.scrub = xchk_directory,
|
.repair = xrep_notsupported,
|
},
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[XFS_SCRUB_TYPE_XATTR] = { /* extended attributes */
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.type = ST_INODE,
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.setup = xchk_setup_xattr,
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.scrub = xchk_xattr,
|
.repair = xrep_notsupported,
|
},
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[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_rt,
|
.scrub = xchk_rtbitmap,
|
.has = xfs_sb_version_hasrealtime,
|
.repair = xrep_notsupported,
|
},
|
[XFS_SCRUB_TYPE_RTSUM] = { /* realtime summary */
|
.type = ST_FS,
|
.setup = xchk_setup_rt,
|
.scrub = xchk_rtsummary,
|
.has = xfs_sb_version_hasrealtime,
|
.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,
|
},
|
};
|
|
/* This isn't a stable feature, warn once per day. */
|
static inline void
|
xchk_experimental_warning(
|
struct xfs_mount *mp)
|
{
|
static struct ratelimit_state scrub_warning = RATELIMIT_STATE_INIT(
|
"xchk_warning", 86400 * HZ, 1);
|
ratelimit_set_flags(&scrub_warning, RATELIMIT_MSG_ON_RELEASE);
|
|
if (__ratelimit(&scrub_warning))
|
xfs_alert(mp,
|
"EXPERIMENTAL online scrub feature in use. Use at your own risk!");
|
}
|
|
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->m_sb))
|
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;
|
}
|
|
/*
|
* 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_sb_version_hascrc(&mp->m_sb))
|
goto out;
|
|
error = -EROFS;
|
if (mp->m_flags & XFS_MOUNT_RDONLY)
|
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 xfs_inode *ip,
|
struct xfs_scrub_metadata *sm)
|
{
|
struct xfs_scrub sc = {
|
.mp = ip->i_mount,
|
.sm = sm,
|
.sa = {
|
.agno = NULLAGNUMBER,
|
},
|
};
|
struct xfs_mount *mp = ip->i_mount;
|
int error = 0;
|
|
BUILD_BUG_ON(sizeof(meta_scrub_ops) !=
|
(sizeof(struct xchk_meta_ops) * XFS_SCRUB_TYPE_NR));
|
|
trace_xchk_start(ip, sm, error);
|
|
/* Forbidden if we are shut down or mounted norecovery. */
|
error = -ESHUTDOWN;
|
if (XFS_FORCED_SHUTDOWN(mp))
|
goto out;
|
error = -ENOTRECOVERABLE;
|
if (mp->m_flags & XFS_MOUNT_NORECOVERY)
|
goto out;
|
|
error = xchk_validate_inputs(mp, sm);
|
if (error)
|
goto out;
|
|
xchk_experimental_warning(mp);
|
|
sc.ops = &meta_scrub_ops[sm->sm_type];
|
sc.sick_mask = xchk_health_mask_for_scrub_type(sm->sm_type);
|
retry_op:
|
/*
|
* If freeze runs concurrently with a scrub, the freeze can be delayed
|
* indefinitely as we walk the filesystem and iterate over metadata
|
* buffers. Freeze quiesces the log (which waits for the buffer LRU to
|
* be emptied) and that won't happen while checking is running.
|
*/
|
sb_start_write(mp->m_super);
|
|
/* Set up for the operation. */
|
error = sc.ops->setup(&sc, ip);
|
if (error)
|
goto out_teardown;
|
|
/* Scrub for errors. */
|
error = sc.ops->scrub(&sc);
|
if (!(sc.flags & XCHK_TRY_HARDER) && error == -EDEADLOCK) {
|
/*
|
* 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, ip, 0);
|
if (error)
|
goto out;
|
sc.flags |= XCHK_TRY_HARDER;
|
goto retry_op;
|
} else if (error)
|
goto out_teardown;
|
|
xchk_update_health(&sc);
|
|
if ((sc.sm->sm_flags & XFS_SCRUB_IFLAG_REPAIR) &&
|
!(sc.flags & XREP_ALREADY_FIXED)) {
|
bool needs_fix;
|
|
/* Let debug users force us into the repair routines. */
|
if (XFS_TEST_ERROR(false, mp, XFS_ERRTAG_FORCE_SCRUB_REPAIR))
|
sc.sm->sm_flags |= XFS_SCRUB_OFLAG_CORRUPT;
|
|
needs_fix = (sc.sm->sm_flags & (XFS_SCRUB_OFLAG_CORRUPT |
|
XFS_SCRUB_OFLAG_XCORRUPT |
|
XFS_SCRUB_OFLAG_PREEN));
|
/*
|
* 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(ip, &sc);
|
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, ip, 0);
|
if (error) {
|
xrep_failure(mp);
|
goto out;
|
}
|
goto retry_op;
|
}
|
}
|
|
out_nofix:
|
xchk_postmortem(&sc);
|
out_teardown:
|
error = xchk_teardown(&sc, ip, error);
|
out:
|
trace_xchk_done(ip, sm, error);
|
if (error == -EFSCORRUPTED || error == -EFSBADCRC) {
|
sm->sm_flags |= XFS_SCRUB_OFLAG_CORRUPT;
|
error = 0;
|
}
|
return error;
|
}
|
