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linux-next/fs/xfs/xfs_super.h
Dave Chinner ddeb14f4fb xfs: quiesce the filesystem after recovery on readonly mount
Recently we've had a number of reports where log recovery on a v5
filesystem has reported corruptions that looked to be caused by
recovery being re-run over the top of an already-recovered
metadata. This has uncovered a bug in recovery (fixed elsewhere)
but the vector that caused this was largely unknown.

A kdump test started tripping over this problem - the system
would be crashed, the kdump kernel and environment would boot and
dump the kernel core image, and then the system would reboot. After
reboot, the root filesystem was triggering log recovery and
corruptions were being detected. The metadumps indicated the above
log recovery issue.

What is happening is that the kdump kernel and environment is
mounting the root device read-only to find the binaries needed to do
it's work. The result of this is that it is running log recovery.
However, because there were unlinked files and EFIs to be processed
by recovery, the completion of phase 1 of log recovery could not
mark the log clean. And because it's a read-only mount, the unmount
process does not write records to the log to mark it clean, either.
Hence on the next mount of the filesystem, log recovery was run
again across all the metadata that had already been recovered and
this is what triggered corruption warnings.

To avoid this problem, we need to ensure that a read-only mount
always updates the log when it completes the second phase of
recovery. We already handle this sort of issue with rw->ro remount
transitions, so the solution is as simple as quiescing the
filesystem at the appropriate time during the mount process. This
results in the log being marked clean so the mount behaviour
recorded in the logs on repeated RO mounts will change (i.e. log
recovery will no longer be run on every mount until a RW mount is
done). This is a user visible change in behaviour, but it is
harmless.

Signed-off-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Eric Sandeen <sandeen@redhat.com>
Signed-off-by: Dave Chinner <david@fromorbit.com>
2016-09-26 08:21:44 +10:00

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C

/*
* Copyright (c) 2000-2005 Silicon Graphics, Inc.
* All Rights Reserved.
*
* 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.
*
* 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
*/
#ifndef __XFS_SUPER_H__
#define __XFS_SUPER_H__
#include <linux/exportfs.h>
#ifdef CONFIG_XFS_QUOTA
extern int xfs_qm_init(void);
extern void xfs_qm_exit(void);
#else
# define xfs_qm_init() (0)
# define xfs_qm_exit() do { } while (0)
#endif
#ifdef CONFIG_XFS_POSIX_ACL
# define XFS_ACL_STRING "ACLs, "
# define set_posix_acl_flag(sb) ((sb)->s_flags |= MS_POSIXACL)
#else
# define XFS_ACL_STRING
# define set_posix_acl_flag(sb) do { } while (0)
#endif
#define XFS_SECURITY_STRING "security attributes, "
#ifdef CONFIG_XFS_RT
# define XFS_REALTIME_STRING "realtime, "
#else
# define XFS_REALTIME_STRING
#endif
#ifdef DEBUG
# define XFS_DBG_STRING "debug"
#else
# define XFS_DBG_STRING "no debug"
#endif
#define XFS_VERSION_STRING "SGI XFS"
#define XFS_BUILD_OPTIONS XFS_ACL_STRING \
XFS_SECURITY_STRING \
XFS_REALTIME_STRING \
XFS_DBG_STRING /* DBG must be last */
struct xfs_inode;
struct xfs_mount;
struct xfs_buftarg;
struct block_device;
extern void xfs_quiesce_attr(struct xfs_mount *mp);
extern void xfs_flush_inodes(struct xfs_mount *mp);
extern void xfs_blkdev_issue_flush(struct xfs_buftarg *);
extern xfs_agnumber_t xfs_set_inode_alloc(struct xfs_mount *,
xfs_agnumber_t agcount);
extern const struct export_operations xfs_export_operations;
extern const struct xattr_handler *xfs_xattr_handlers[];
extern const struct quotactl_ops xfs_quotactl_operations;
extern void xfs_reinit_percpu_counters(struct xfs_mount *mp);
#define XFS_M(sb) ((struct xfs_mount *)((sb)->s_fs_info))
#endif /* __XFS_SUPER_H__ */