xfs: dispatch metadata scrub subcommands
Create structures needed to hold scrubbing context and dispatch incoming commands to the individual scrubbers. Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com> Reviewed-by: Dave Chinner <dchinner@redhat.com>
This commit is contained in:
Darrick J. Wong
parent
36fd6e863c
commit
a56371865e
3 changed files with 262 additions and 1 deletions
|
|
@ -44,11 +44,205 @@
|
|||
#include "scrub/scrub.h"
|
||||
#include "scrub/trace.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 setup and teardown */
|
||||
|
||||
/* Free all the resources and finish the transactions. */
|
||||
STATIC int
|
||||
xfs_scrub_teardown(
|
||||
struct xfs_scrub_context *sc,
|
||||
int error)
|
||||
{
|
||||
if (sc->tp) {
|
||||
xfs_trans_cancel(sc->tp);
|
||||
sc->tp = NULL;
|
||||
}
|
||||
return error;
|
||||
}
|
||||
|
||||
/* Scrubbing dispatch. */
|
||||
|
||||
static const struct xfs_scrub_meta_ops meta_scrub_ops[] = {
|
||||
};
|
||||
|
||||
/* 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)
|
||||
{
|
||||
return -EOPNOTSUPP;
|
||||
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;
|
||||
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, 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, 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;
|
||||
}
|
||||
|
|
|
|||
|
|
@ -20,6 +20,30 @@
|
|||
#ifndef __XFS_SCRUB_SCRUB_H__
|
||||
#define __XFS_SCRUB_SCRUB_H__
|
||||
|
||||
struct xfs_scrub_context;
|
||||
|
||||
struct xfs_scrub_meta_ops {
|
||||
/* Acquire whatever resources are needed for the operation. */
|
||||
int (*setup)(struct xfs_scrub_context *,
|
||||
struct xfs_inode *);
|
||||
|
||||
/* Examine metadata for errors. */
|
||||
int (*scrub)(struct xfs_scrub_context *);
|
||||
|
||||
/* Decide if we even have this piece of metadata. */
|
||||
bool (*has)(struct xfs_sb *);
|
||||
};
|
||||
|
||||
struct xfs_scrub_context {
|
||||
/* General scrub state. */
|
||||
struct xfs_mount *mp;
|
||||
struct xfs_scrub_metadata *sm;
|
||||
const struct xfs_scrub_meta_ops *ops;
|
||||
struct xfs_trans *tp;
|
||||
struct xfs_inode *ip;
|
||||
bool try_harder;
|
||||
};
|
||||
|
||||
/* Metadata scrubbers */
|
||||
|
||||
#endif /* __XFS_SCRUB_SCRUB_H__ */
|
||||
|
|
|
|||
|
|
@ -25,6 +25,49 @@
|
|||
|
||||
#include <linux/tracepoint.h>
|
||||
|
||||
DECLARE_EVENT_CLASS(xfs_scrub_class,
|
||||
TP_PROTO(struct xfs_inode *ip, struct xfs_scrub_metadata *sm,
|
||||
int error),
|
||||
TP_ARGS(ip, sm, error),
|
||||
TP_STRUCT__entry(
|
||||
__field(dev_t, dev)
|
||||
__field(xfs_ino_t, ino)
|
||||
__field(unsigned int, type)
|
||||
__field(xfs_agnumber_t, agno)
|
||||
__field(xfs_ino_t, inum)
|
||||
__field(unsigned int, gen)
|
||||
__field(unsigned int, flags)
|
||||
__field(int, error)
|
||||
),
|
||||
TP_fast_assign(
|
||||
__entry->dev = ip->i_mount->m_super->s_dev;
|
||||
__entry->ino = ip->i_ino;
|
||||
__entry->type = sm->sm_type;
|
||||
__entry->agno = sm->sm_agno;
|
||||
__entry->inum = sm->sm_ino;
|
||||
__entry->gen = sm->sm_gen;
|
||||
__entry->flags = sm->sm_flags;
|
||||
__entry->error = error;
|
||||
),
|
||||
TP_printk("dev %d:%d ino %llu type %u agno %u inum %llu gen %u flags 0x%x error %d",
|
||||
MAJOR(__entry->dev), MINOR(__entry->dev),
|
||||
__entry->ino,
|
||||
__entry->type,
|
||||
__entry->agno,
|
||||
__entry->inum,
|
||||
__entry->gen,
|
||||
__entry->flags,
|
||||
__entry->error)
|
||||
)
|
||||
#define DEFINE_SCRUB_EVENT(name) \
|
||||
DEFINE_EVENT(xfs_scrub_class, name, \
|
||||
TP_PROTO(struct xfs_inode *ip, struct xfs_scrub_metadata *sm, \
|
||||
int error), \
|
||||
TP_ARGS(ip, sm, error))
|
||||
|
||||
DEFINE_SCRUB_EVENT(xfs_scrub_start);
|
||||
DEFINE_SCRUB_EVENT(xfs_scrub_done);
|
||||
|
||||
#endif /* _TRACE_XFS_SCRUB_TRACE_H */
|
||||
|
||||
#undef TRACE_INCLUDE_PATH
|
||||
|
|
|
|||
Loading…
Reference in a new issue