xfs: allow setting and clearing of log incompat feature flags

Log incompat feature flags in the superblock exist for one purpose: to
protect the contents of a dirty log from replay on a kernel that isn't
prepared to handle those dirty contents.  This means that they can be
cleared if (a) we know the log is clean and (b) we know that there
aren't any other threads in the system that might be setting or relying
upon a log incompat flag.

Therefore, clear the log incompat flags when we've finished recovering
the log, when we're unmounting cleanly, remounting read-only, or
freezing; and provide a function so that subsequent patches can start
using this.

Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Allison Henderson <allison.henderson@oracle.com>
Reviewed-by: Chandan Babu R <chandanrlinux@gmail.com>

1 files changed, 14 insertions, 0 deletions

diff --git a/fs/xfs/xfs_log.c b/fs/xfs/xfs_log.c
index eb8341027cc7..e0d4ffce7a8a 100644
--- a/fs/xfs/xfs_log.c
+++ b/fs/xfs/xfs_log.c
@@ -972,6 +972,20 @@ int
 xfs_log_quiesce(
 	struct xfs_mount	*mp)
 {
+	/*
+	 * Clear log incompat features since we're quiescing the log.  Report
+	 * failures, though it's not fatal to have a higher log feature
+	 * protection level than the log contents actually require.
+	 */
+	if (xfs_clear_incompat_log_features(mp)) {
+		int error;
+
+		error = xfs_sync_sb(mp, false);
+		if (error)
+			xfs_warn(mp,
+	"Failed to clear log incompat features on quiesce");
+	}
+
 	cancel_delayed_work_sync(&mp->m_log->l_work);
 	xfs_log_force(mp, XFS_LOG_SYNC);