From: Brian Foster bfoster@redhat.com
commit 50d25484bebe94320c49dd1347d3330c7063bbdb upstream.
[ Modify xfs_log_unmount_write() to return zero when the log is in a read-only state ]
xfs_log_sbcount() syncs the superblock specifically to accumulate the in-core percpu superblock counters and commit them to disk. This is required to maintain filesystem consistency across quiesce (freeze, read-only mount/remount) or unmount when lazy superblock accounting is enabled because individual transactions do not update the superblock directly.
This mechanism works as expected for writable mounts, but xfs_log_sbcount() skips the update for read-only mounts. Read-only mounts otherwise still allow log recovery and write out an unmount record during log quiesce. If a read-only mount performs log recovery, it can modify the in-core superblock counters and write an unmount record when the filesystem unmounts without ever syncing the in-core counters. This leaves the filesystem with a clean log but in an inconsistent state with regard to lazy sb counters.
Update xfs_log_sbcount() to use the same logic xfs_log_unmount_write() uses to determine when to write an unmount record. This ensures that lazy accounting is always synced before the log is cleaned. Refactor this logic into a new helper to distinguish between a writable filesystem and a writable log. Specifically, the log is writable unless the filesystem is mounted with the norecovery mount option, the underlying log device is read-only, or the filesystem is shutdown. Drop the freeze state check because the update is already allowed during the freezing process and no context calls this function on an already frozen fs. Also, retain the shutdown check in xfs_log_unmount_write() to catch the case where the preceding log force might have triggered a shutdown.
Signed-off-by: Brian Foster bfoster@redhat.com Reviewed-by: Gao Xiang hsiangkao@redhat.com Reviewed-by: Allison Henderson allison.henderson@oracle.com Reviewed-by: Darrick J. Wong darrick.wong@oracle.com Reviewed-by: Bill O'Donnell billodo@redhat.com Reviewed-by: Darrick J. Wong djwong@kernel.org Signed-off-by: Darrick J. Wong djwong@kernel.org Signed-off-by: Chandan Babu R chandan.babu@oracle.com Acked-by: Darrick J. Wong djwong@kernel.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- fs/xfs/xfs_log.c | 28 ++++++++++++++++++++-------- fs/xfs/xfs_log.h | 1 + fs/xfs/xfs_mount.c | 3 +-- 3 files changed, 22 insertions(+), 10 deletions(-)
--- a/fs/xfs/xfs_log.c +++ b/fs/xfs/xfs_log.c @@ -369,6 +369,25 @@ xlog_tic_add_region(xlog_ticket_t *tic, tic->t_res_num++; }
+bool +xfs_log_writable( + struct xfs_mount *mp) +{ + /* + * Never write to the log on norecovery mounts, if the block device is + * read-only, or if the filesystem is shutdown. Read-only mounts still + * allow internal writes for log recovery and unmount purposes, so don't + * restrict that case here. + */ + if (mp->m_flags & XFS_MOUNT_NORECOVERY) + return false; + if (xfs_readonly_buftarg(mp->m_log->l_targ)) + return false; + if (XFS_FORCED_SHUTDOWN(mp)) + return false; + return true; +} + /* * Replenish the byte reservation required by moving the grant write head. */ @@ -895,15 +914,8 @@ xfs_log_unmount_write(xfs_mount_t *mp) #endif int error;
- /* - * Don't write out unmount record on norecovery mounts or ro devices. - * Or, if we are doing a forced umount (typically because of IO errors). - */ - if (mp->m_flags & XFS_MOUNT_NORECOVERY || - xfs_readonly_buftarg(log->l_targ)) { - ASSERT(mp->m_flags & XFS_MOUNT_RDONLY); + if (!xfs_log_writable(mp)) return 0; - }
error = xfs_log_force(mp, XFS_LOG_SYNC); ASSERT(error || !(XLOG_FORCED_SHUTDOWN(log))); --- a/fs/xfs/xfs_log.h +++ b/fs/xfs/xfs_log.h @@ -132,6 +132,7 @@ int xfs_log_reserve(struct xfs_mount * int xfs_log_regrant(struct xfs_mount *mp, struct xlog_ticket *tic); void xfs_log_unmount(struct xfs_mount *mp); int xfs_log_force_umount(struct xfs_mount *mp, int logerror); +bool xfs_log_writable(struct xfs_mount *mp);
struct xlog_ticket *xfs_log_ticket_get(struct xlog_ticket *ticket); void xfs_log_ticket_put(struct xlog_ticket *ticket); --- a/fs/xfs/xfs_mount.c +++ b/fs/xfs/xfs_mount.c @@ -1218,8 +1218,7 @@ xfs_fs_writable( int xfs_log_sbcount(xfs_mount_t *mp) { - /* allow this to proceed during the freeze sequence... */ - if (!xfs_fs_writable(mp, SB_FREEZE_COMPLETE)) + if (!xfs_log_writable(mp)) return 0;
/*