diff options
Diffstat (limited to 'fs/xfs/scrub/scrub.c')
| -rw-r--r-- | fs/xfs/scrub/scrub.c | 392 |
1 files changed, 392 insertions, 0 deletions
diff --git a/fs/xfs/scrub/scrub.c b/fs/xfs/scrub/scrub.c new file mode 100644 index 000000000000..9c42c4efd01e --- /dev/null +++ b/fs/xfs/scrub/scrub.c @@ -0,0 +1,392 @@ +/* + * 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/scrub.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; +} + +/* 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; +} + +/* 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!"); +} + +/* 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; +} |