Release 4.18 fs/xfs/scrub/scrub.c
// SPDX-License-Identifier: GPL-2.0+
/*
* Copyright (C) 2017 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_icache.h"
#include "xfs_itable.h"
#include "xfs_alloc.h"
#include "xfs_alloc_btree.h"
#include "xfs_bmap.h"
#include "xfs_bmap_btree.h"
#include "xfs_ialloc.h"
#include "xfs_ialloc_btree.h"
#include "xfs_refcount.h"
#include "xfs_refcount_btree.h"
#include "xfs_rmap.h"
#include "xfs_rmap_btree.h"
#include "xfs_quota.h"
#include "xfs_qm.h"
#include "xfs_errortag.h"
#include "xfs_error.h"
#include "xfs_log.h"
#include "xfs_trans_priv.h"
#include "scrub/xfs_scrub.h"
#include "scrub/scrub.h"
#include "scrub/common.h"
#include "scrub/trace.h"
#include "scrub/btree.h"
#include "scrub/repair.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.
*/
/*
* 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
xfs_scrub_probe(
struct xfs_scrub_context *sc)
{
int error = 0;
if (xfs_scrub_should_terminate(sc, &error))
return error;
return 0;
}
Contributors
| Person | Tokens | Prop | Commits | CommitProp |
| Darrick J. Wong | 31 | 96.88% | 1 | 50.00% |
| Christoph Hellwig | 1 | 3.12% | 1 | 50.00% |
| Total | 32 | 100.00% | 2 | 100.00% |
/* Scrub setup and teardown */
/* Free all the resources and finish the transactions. */
STATIC int
xfs_scrub_teardown(
struct xfs_scrub_context *sc,
struct xfs_inode *ip_in,
int error)
{
xfs_scrub_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)
xfs_iunlock(sc->ip, sc->ilock_flags);
if (sc->ip != ip_in &&
!xfs_internal_inum(sc->mp, sc->ip->i_ino))
iput(VFS_I(sc->ip));
sc->ip = NULL;
}
if (sc->has_quotaofflock)
mutex_unlock(&sc->mp->m_quotainfo->qi_quotaofflock);
if (sc->buf) {
kmem_free(sc->buf);
sc->buf = NULL;
}
return error;
}
Contributors
| Person | Tokens | Prop | Commits | CommitProp |
| Darrick J. Wong | 181 | 100.00% | 7 | 100.00% |
| Total | 181 | 100.00% | 7 | 100.00% |
/* Scrubbing dispatch. */
static const struct xfs_scrub_meta_ops meta_scrub_ops[] = {
[XFS_SCRUB_TYPE_PROBE] = { /* ioctl presence test */
.type = ST_NONE,
.setup = xfs_scrub_setup_fs,
.scrub = xfs_scrub_probe,
.repair = xfs_repair_probe,
},
[XFS_SCRUB_TYPE_SB] = { /* superblock */
.type = ST_PERAG,
.setup = xfs_scrub_setup_fs,
.scrub = xfs_scrub_superblock,
.repair = xfs_repair_superblock,
},
[XFS_SCRUB_TYPE_AGF] = { /* agf */
.type = ST_PERAG,
.setup = xfs_scrub_setup_fs,
.scrub = xfs_scrub_agf,
.repair = xfs_repair_notsupported,
},
[XFS_SCRUB_TYPE_AGFL]= { /* agfl */
.type = ST_PERAG,
.setup = xfs_scrub_setup_fs,
.scrub = xfs_scrub_agfl,
.repair = xfs_repair_notsupported,
},
[XFS_SCRUB_TYPE_AGI] = { /* agi */
.type = ST_PERAG,
.setup = xfs_scrub_setup_fs,
.scrub = xfs_scrub_agi,
.repair = xfs_repair_notsupported,
},
[XFS_SCRUB_TYPE_BNOBT] = { /* bnobt */
.type = ST_PERAG,
.setup = xfs_scrub_setup_ag_allocbt,
.scrub = xfs_scrub_bnobt,
.repair = xfs_repair_notsupported,
},
[XFS_SCRUB_TYPE_CNTBT] = { /* cntbt */
.type = ST_PERAG,
.setup = xfs_scrub_setup_ag_allocbt,
.scrub = xfs_scrub_cntbt,
.repair = xfs_repair_notsupported,
},
[XFS_SCRUB_TYPE_INOBT] = { /* inobt */
.type = ST_PERAG,
.setup = xfs_scrub_setup_ag_iallocbt,
.scrub = xfs_scrub_inobt,
.repair = xfs_repair_notsupported,
},
[XFS_SCRUB_TYPE_FINOBT] = { /* finobt */
.type = ST_PERAG,
.setup = xfs_scrub_setup_ag_iallocbt,
.scrub = xfs_scrub_finobt,
.has = xfs_sb_version_hasfinobt,
.repair = xfs_repair_notsupported,
},
[XFS_SCRUB_TYPE_RMAPBT] = { /* rmapbt */
.type = ST_PERAG,
.setup = xfs_scrub_setup_ag_rmapbt,
.scrub = xfs_scrub_rmapbt,
.has = xfs_sb_version_hasrmapbt,
.repair = xfs_repair_notsupported,
},
[XFS_SCRUB_TYPE_REFCNTBT] = { /* refcountbt */
.type = ST_PERAG,
.setup = xfs_scrub_setup_ag_refcountbt,
.scrub = xfs_scrub_refcountbt,
.has = xfs_sb_version_hasreflink,
.repair = xfs_repair_notsupported,
},
[XFS_SCRUB_TYPE_INODE] = { /* inode record */
.type = ST_INODE,
.setup = xfs_scrub_setup_inode,
.scrub = xfs_scrub_inode,
.repair = xfs_repair_notsupported,
},
[XFS_SCRUB_TYPE_BMBTD] = { /* inode data fork */
.type = ST_INODE,
.setup = xfs_scrub_setup_inode_bmap,
.scrub = xfs_scrub_bmap_data,
.repair = xfs_repair_notsupported,
},
[XFS_SCRUB_TYPE_BMBTA] = { /* inode attr fork */
.type = ST_INODE,
.setup = xfs_scrub_setup_inode_bmap,
.scrub = xfs_scrub_bmap_attr,
.repair = xfs_repair_notsupported,
},
[XFS_SCRUB_TYPE_BMBTC] = { /* inode CoW fork */
.type = ST_INODE,
.setup = xfs_scrub_setup_inode_bmap,
.scrub = xfs_scrub_bmap_cow,
.repair = xfs_repair_notsupported,
},
[XFS_SCRUB_TYPE_DIR] = { /* directory */
.type = ST_INODE,
.setup = xfs_scrub_setup_directory,
.scrub = xfs_scrub_directory,
.repair = xfs_repair_notsupported,
},
[XFS_SCRUB_TYPE_XATTR] = { /* extended attributes */
.type = ST_INODE,
.setup = xfs_scrub_setup_xattr,
.scrub = xfs_scrub_xattr,
.repair = xfs_repair_notsupported,
},
[XFS_SCRUB_TYPE_SYMLINK] = { /* symbolic link */
.type = ST_INODE,
.setup = xfs_scrub_setup_symlink,
.scrub = xfs_scrub_symlink,
.repair = xfs_repair_notsupported,
},
[XFS_SCRUB_TYPE_PARENT] = { /* parent pointers */
.type = ST_INODE,
.setup = xfs_scrub_setup_parent,
.scrub = xfs_scrub_parent,
.repair = xfs_repair_notsupported,
},
[XFS_SCRUB_TYPE_RTBITMAP] = { /* realtime bitmap */
.type = ST_FS,
.setup = xfs_scrub_setup_rt,
.scrub = xfs_scrub_rtbitmap,
.has = xfs_sb_version_hasrealtime,
.repair = xfs_repair_notsupported,
},
[XFS_SCRUB_TYPE_RTSUM] = { /* realtime summary */
.type = ST_FS,
.setup = xfs_scrub_setup_rt,
.scrub = xfs_scrub_rtsummary,
.has = xfs_sb_version_hasrealtime,
.repair = xfs_repair_notsupported,
},
[XFS_SCRUB_TYPE_UQUOTA] = { /* user quota */
.type = ST_FS,
.setup = xfs_scrub_setup_quota,
.scrub = xfs_scrub_quota,
.repair = xfs_repair_notsupported,
},
[XFS_SCRUB_TYPE_GQUOTA] = { /* group quota */
.type = ST_FS,
.setup = xfs_scrub_setup_quota,
.scrub = xfs_scrub_quota,
.repair = xfs_repair_notsupported,
},
[XFS_SCRUB_TYPE_PQUOTA] = { /* project quota */
.type = ST_FS,
.setup = xfs_scrub_setup_quota,
.scrub = xfs_scrub_quota,
.repair = xfs_repair_notsupported,
},
};
/* This isn't a stable feature, warn once per day. */
static inline void
xfs_scrub_experimental_warning(
struct xfs_mount *mp)
{
static struct ratelimit_state scrub_warning = RATELIMIT_STATE_INIT(
"xfs_scrub_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!");
}
Contributors
| Person | Tokens | Prop | Commits | CommitProp |
| Darrick J. Wong | 51 | 100.00% | 1 | 100.00% |
| Total | 51 | 100.00% | 1 | 100.00% |
static int
xfs_scrub_validate_inputs(
struct xfs_mount *mp,
struct xfs_scrub_metadata *sm)
{
int error;
const struct xfs_scrub_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;
}
error = -EOPNOTSUPP;
/*
* We won't scrub any filesystem that doesn't have the ability
* to record unwritten extents. The option was made default in
* 2003, removed from mkfs in 2007, and cannot be disabled in
* v5, so if we find a filesystem without this flag it's either
* really old or totally unsupported. Avoid it either way.
* We also don't support v1-v3 filesystems, which aren't
* mountable.
*/
if (!xfs_sb_version_hasextflgbit(&mp->m_sb))
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;
}
Contributors
| Person | Tokens | Prop | Commits | CommitProp |
| Darrick J. Wong | 154 | 50.49% | 3 | 50.00% |
| Eric Sandeen | 151 | 49.51% | 3 | 50.00% |
| Total | 305 | 100.00% | 6 | 100.00% |
#ifdef CONFIG_XFS_ONLINE_REPAIR
static inline void xfs_scrub_postmortem(struct xfs_scrub_context *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)))
xfs_repair_failure(sc->mp);
}
Contributors
| Person | Tokens | Prop | Commits | CommitProp |
| Darrick J. Wong | 46 | 100.00% | 1 | 100.00% |
| Total | 46 | 100.00% | 1 | 100.00% |
#else
static inline void xfs_scrub_postmortem(struct xfs_scrub_context *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.");
}
Contributors
| Person | Tokens | Prop | Commits | CommitProp |
| Darrick J. Wong | 36 | 100.00% | 1 | 100.00% |
| Total | 36 | 100.00% | 1 | 100.00% |
#endif /* CONFIG_XFS_ONLINE_REPAIR */
/* Dispatch metadata scrubbing. */
int
xfs_scrub_metadata(
struct xfs_inode *ip,
struct xfs_scrub_metadata *sm)
{
struct xfs_scrub_context sc;
struct xfs_mount *mp = ip->i_mount;
bool try_harder = false;
bool already_fixed = false;
int error = 0;
BUILD_BUG_ON(sizeof(meta_scrub_ops) !=
(sizeof(struct xfs_scrub_meta_ops) * XFS_SCRUB_TYPE_NR));
trace_xfs_scrub_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 = xfs_scrub_validate_inputs(mp, sm);
if (error)
goto out;
xfs_scrub_experimental_warning(mp);
retry_op:
/* Set up for the operation. */
memset(&sc, 0, sizeof(sc));
sc.mp = ip->i_mount;
sc.sm = sm;
sc.ops = &meta_scrub_ops[sm->sm_type];
sc.try_harder = try_harder;
sc.sa.agno = NULLAGNUMBER;
error = sc.ops->setup(&sc, ip);
if (error)
goto out_teardown;
/* Scrub for errors. */
error = sc.ops->scrub(&sc);
if (!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 = xfs_scrub_teardown(&sc, ip, 0);
if (error)
goto out;
try_harder = true;
goto retry_op;
} else if (error)
goto out_teardown;
if ((sc.sm->sm_flags & XFS_SCRUB_IFLAG_REPAIR) && !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 = xfs_repair_attempt(ip, &sc, &already_fixed);
if (error == -EAGAIN) {
if (sc.try_harder)
try_harder = true;
error = xfs_scrub_teardown(&sc, ip, 0);
if (error) {
xfs_repair_failure(mp);
goto out;
}
goto retry_op;
}
}
out_nofix:
xfs_scrub_postmortem(&sc);
out_teardown:
error = xfs_scrub_teardown(&sc, ip, error);
out:
trace_xfs_scrub_done(ip, sm, error);
if (error == -EFSCORRUPTED || error == -EFSBADCRC) {
sm->sm_flags |= XFS_SCRUB_OFLAG_CORRUPT;
error = 0;
}
return error;
}
Contributors
| Person | Tokens | Prop | Commits | CommitProp |
| Darrick J. Wong | 365 | 79.52% | 5 | 83.33% |
| Eric Sandeen | 94 | 20.48% | 1 | 16.67% |
| Total | 459 | 100.00% | 6 | 100.00% |
Overall Contributors
| Person | Tokens | Prop | Commits | CommitProp |
| Darrick J. Wong | 1451 | 75.57% | 23 | 82.14% |
| Eric Sandeen | 466 | 24.27% | 3 | 10.71% |
| Dave Chinner | 2 | 0.10% | 1 | 3.57% |
| Christoph Hellwig | 1 | 0.05% | 1 | 3.57% |
| Total | 1920 | 100.00% | 28 | 100.00% |
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