[PATCH 01/18] xfs: add a repair revalidation function pointer

["Darrick J. Wong" <darrick.wong@oracle.com>]

From: Darrick J. Wong <darrick.wong@oracle.com>

Allow repair functions to set a separate function pointer to validate
the metadata that they've rebuilt.  This prevents us from exiting from a
repair function that rebuilds both A and B without checking that both A
and B can pass a scrub test.  We'll need this for the free space and
inode btree repair strategies.

Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
---
 fs/xfs/scrub/scrub.c |    5 ++++-
 fs/xfs/scrub/scrub.h |    8 ++++++++
 2 files changed, 12 insertions(+), 1 deletion(-)


diff --git a/fs/xfs/scrub/scrub.c b/fs/xfs/scrub/scrub.c
index 15c8c5f3f688..0f0b64d7164b 100644
--- a/fs/xfs/scrub/scrub.c
+++ b/fs/xfs/scrub/scrub.c
@@ -495,7 +495,10 @@ xfs_scrub_metadata(
 		goto out_teardown;
 
 	/* Scrub for errors. */
-	error = sc.ops->scrub(&sc);
+	if ((sc.flags & XREP_ALREADY_FIXED) && sc.ops->repair_eval != NULL)
+		error = sc.ops->repair_eval(&sc);
+	else
+		error = sc.ops->scrub(&sc);
 	if (!(sc.flags & XCHK_TRY_HARDER) && error == -EDEADLOCK) {
 		/*
 		 * Scrubbers return -EDEADLOCK to mean 'try harder'.
diff --git a/fs/xfs/scrub/scrub.h b/fs/xfs/scrub/scrub.h
index ad1ceb44a628..94a30637a127 100644
--- a/fs/xfs/scrub/scrub.h
+++ b/fs/xfs/scrub/scrub.h
@@ -27,6 +27,14 @@ struct xchk_meta_ops {
 	/* Repair or optimize the metadata. */
 	int		(*repair)(struct xfs_scrub *);
 
+	/*
+	 * Re-scrub the metadata we repaired, in case there's extra work that
+	 * we need to do to check our repair work.  If this is NULL, we'll use
+	 * the ->scrub function pointer, assuming that the regular scrub is
+	 * sufficient.
+	 */
+	int		(*repair_eval)(struct xfs_scrub *sc);
+
 	/* Decide if we even have this piece of metadata. */
 	bool		(*has)(struct xfs_sb *);