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authorBrian Foster <bfoster@redhat.com>2015-10-12 07:59:25 +0300
committerDave Chinner <david@fromorbit.com>2015-10-12 07:59:25 +0300
commita45086e27dfa21a4b39134f7505c8f60a3ecdec4 (patch)
treee55bfa2359246fe65e82da6caf3ccd74afc8c46f /fs/xfs/xfs_log.h
parentb7cdc66be54b64daef593894d12ecc405f117829 (diff)
downloadlinux-a45086e27dfa21a4b39134f7505c8f60a3ecdec4.tar.xz
xfs: validate metadata LSNs against log on v5 superblocks
Since the onset of v5 superblocks, the LSN of the last modification has been included in a variety of on-disk data structures. This LSN is used to provide log recovery ordering guarantees (e.g., to ensure an older log recovery item is not replayed over a newer target data structure). While this works correctly from the point a filesystem is formatted and mounted, userspace tools have some problematic behaviors that defeat this mechanism. For example, xfs_repair historically zeroes out the log unconditionally (regardless of whether corruption is detected). If this occurs, the LSN of the filesystem is reset and the log is now in a problematic state with respect to on-disk metadata structures that might have a larger LSN. Until either the log catches up to the highest previously used metadata LSN or each affected data structure is modified and written out without incident (which resets the metadata LSN), log recovery is susceptible to filesystem corruption. This problem is ultimately addressed and repaired in the associated userspace tools. The kernel is still responsible to detect the problem and notify the user that something is wrong. Check the superblock LSN at mount time and fail the mount if it is invalid. From that point on, trigger verifier failure on any metadata I/O where an invalid LSN is detected. This results in a filesystem shutdown and guarantees that we do not log metadata changes with invalid LSNs on disk. Since this is a known issue with a known recovery path, present a warning to instruct the user how to recover. Signed-off-by: Brian Foster <bfoster@redhat.com> Reviewed-by: Dave Chinner <dchinner@redhat.com> Signed-off-by: Dave Chinner <david@fromorbit.com>
Diffstat (limited to 'fs/xfs/xfs_log.h')
-rw-r--r--fs/xfs/xfs_log.h1
1 files changed, 1 insertions, 0 deletions
diff --git a/fs/xfs/xfs_log.h b/fs/xfs/xfs_log.h
index 09d91d3166cd..aa533a7d50f2 100644
--- a/fs/xfs/xfs_log.h
+++ b/fs/xfs/xfs_log.h
@@ -181,5 +181,6 @@ bool xfs_log_item_in_current_chkpt(struct xfs_log_item *lip);
void xfs_log_work_queue(struct xfs_mount *mp);
void xfs_log_worker(struct work_struct *work);
void xfs_log_quiesce(struct xfs_mount *mp);
+bool xfs_log_check_lsn(struct xfs_mount *, xfs_lsn_t);
#endif /* __XFS_LOG_H__ */