Release 4.15 fs/xfs/scrub/scrub.c
/*
* Copyright (C) 2017 Oracle. All Rights Reserved.
*
* Author: Darrick J. Wong <darrick.wong@oracle.com>
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version 2
* of the License, or (at your option) any later version.
*
* This program is distributed in the hope that it would be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write the Free Software Foundation,
* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301, USA.
*/
#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 "scrub/xfs_scrub.h"
#include "scrub/scrub.h"
#include "scrub/common.h"
#include "scrub/trace.h"
#include "scrub/btree.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.
*/
/*
* 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 (sc->sm->sm_ino || sc->sm->sm_agno)
return -EINVAL;
if (xfs_scrub_should_terminate(sc, &error))
return error;
return 0;
}
Contributors
| Person | Tokens | Prop | Commits | CommitProp |
| Darrick J. Wong | 49 | 98.00% | 1 | 50.00% |
| Christoph Hellwig | 1 | 2.00% | 1 | 50.00% |
| Total | 50 | 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) {
xfs_trans_cancel(sc->tp);
sc->tp = NULL;
}
if (sc->ip) {
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->buf) {
kmem_free(sc->buf);
sc->buf = NULL;
}
return error;
}
Contributors
| Person | Tokens | Prop | Commits | CommitProp |
| Darrick J. Wong | 131 | 100.00% | 4 | 100.00% |
| Total | 131 | 100.00% | 4 | 100.00% |
/* Scrubbing dispatch. */
static const struct xfs_scrub_meta_ops meta_scrub_ops[] = {
{ /* ioctl presence test */
.setup = xfs_scrub_setup_fs,
.scrub = xfs_scrub_probe,
},
{ /* superblock */
.setup = xfs_scrub_setup_ag_header,
.scrub = xfs_scrub_superblock,
},
{ /* agf */
.setup = xfs_scrub_setup_ag_header,
.scrub = xfs_scrub_agf,
},
{ /* agfl */
.setup = xfs_scrub_setup_ag_header,
.scrub = xfs_scrub_agfl,
},
{ /* agi */
.setup = xfs_scrub_setup_ag_header,
.scrub = xfs_scrub_agi,
},
{ /* bnobt */
.setup = xfs_scrub_setup_ag_allocbt,
.scrub = xfs_scrub_bnobt,
},
{ /* cntbt */
.setup = xfs_scrub_setup_ag_allocbt,
.scrub = xfs_scrub_cntbt,
},
{ /* inobt */
.setup = xfs_scrub_setup_ag_iallocbt,
.scrub = xfs_scrub_inobt,
},
{ /* finobt */
.setup = xfs_scrub_setup_ag_iallocbt,
.scrub = xfs_scrub_finobt,
.has = xfs_sb_version_hasfinobt,
},
{ /* rmapbt */
.setup = xfs_scrub_setup_ag_rmapbt,
.scrub = xfs_scrub_rmapbt,
.has = xfs_sb_version_hasrmapbt,
},
{ /* refcountbt */
.setup = xfs_scrub_setup_ag_refcountbt,
.scrub = xfs_scrub_refcountbt,
.has = xfs_sb_version_hasreflink,
},
{ /* inode record */
.setup = xfs_scrub_setup_inode,
.scrub = xfs_scrub_inode,
},
{ /* inode data fork */
.setup = xfs_scrub_setup_inode_bmap,
.scrub = xfs_scrub_bmap_data,
},
{ /* inode attr fork */
.setup = xfs_scrub_setup_inode_bmap,
.scrub = xfs_scrub_bmap_attr,
},
{ /* inode CoW fork */
.setup = xfs_scrub_setup_inode_bmap,
.scrub = xfs_scrub_bmap_cow,
},
{ /* directory */
.setup = xfs_scrub_setup_directory,
.scrub = xfs_scrub_directory,
},
{ /* extended attributes */
.setup = xfs_scrub_setup_xattr,
.scrub = xfs_scrub_xattr,
},
{ /* symbolic link */
.setup = xfs_scrub_setup_symlink,
.scrub = xfs_scrub_symlink,
},
{ /* parent pointers */
.setup = xfs_scrub_setup_parent,
.scrub = xfs_scrub_parent,
},
{ /* realtime bitmap */
.setup = xfs_scrub_setup_rt,
.scrub = xfs_scrub_rtbitmap,
.has = xfs_sb_version_hasrealtime,
},
{ /* realtime summary */
.setup = xfs_scrub_setup_rt,
.scrub = xfs_scrub_rtsummary,
.has = xfs_sb_version_hasrealtime,
},
{ /* user quota */
.setup = xfs_scrub_setup_quota,
.scrub = xfs_scrub_quota,
},
{ /* group quota */
.setup = xfs_scrub_setup_quota,
.scrub = xfs_scrub_quota,
},
{ /* project quota */
.setup = xfs_scrub_setup_quota,
.scrub = xfs_scrub_quota,
},
};
/* 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% |
/* 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;
const struct xfs_scrub_meta_ops *ops;
bool try_harder = false;
int error = 0;
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;
/* Check our inputs. */
error = -EINVAL;
sm->sm_flags &= ~XFS_SCRUB_FLAGS_OUT;
if (sm->sm_flags & ~XFS_SCRUB_FLAGS_IN)
goto out;
if (memchr_inv(sm->sm_reserved, 0, sizeof(sm->sm_reserved)))
goto out;
/* Do we know about this type of metadata? */
error = -ENOENT;
if (sm->sm_type >= XFS_SCRUB_TYPE_NR)
goto out;
ops = &meta_scrub_ops[sm->sm_type];
if (ops->scrub == NULL)
goto out;
/*
* 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.
*/
error = -EOPNOTSUPP;
if (!xfs_sb_version_hasextflgbit(&mp->m_sb))
goto out;
/* Does this fs even support this type of metadata? */
error = -ENOENT;
if (ops->has && !ops->has(&mp->m_sb))
goto out;
/* We don't know how to repair anything yet. */
error = -EOPNOTSUPP;
if (sm->sm_flags & XFS_SCRUB_IFLAG_REPAIR)
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 = ops;
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_OFLAG_CORRUPT |
XFS_SCRUB_OFLAG_XCORRUPT))
xfs_alert_ratelimited(mp, "Corruption detected during scrub.");
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 | 441 | 100.00% | 4 | 100.00% |
| Total | 441 | 100.00% | 4 | 100.00% |
Overall Contributors
| Person | Tokens | Prop | Commits | CommitProp |
| Darrick J. Wong | 1116 | 99.91% | 19 | 95.00% |
| Christoph Hellwig | 1 | 0.09% | 1 | 5.00% |
| Total | 1117 | 100.00% | 20 | 100.00% |
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