SERVER-53675 Allow validate to fix up multikey metadata

This allows foreground validation to fix up the following multikey
metadata inconsistencies:

* An index is multikey but there are no multikey fields
* An index has multikeyPaths covering fields that are not multikey
* An index does not have multikeyPaths but there are multikey documents (for pre-3.4 indexes)

If any changes were made, a warning is included to the validate output
and the 'repaired' flag is set to true.

1 files changed, 19 insertions, 2 deletions

diff --git a/src/mongo/db/commands/validate.cpp b/src/mongo/db/commands/validate.cpp
index c1d787a49bb..bdde2c3156a 100644
--- a/src/mongo/db/commands/validate.cpp
+++ b/src/mongo/db/commands/validate.cpp
@@ -212,8 +212,25 @@ public:
             return CollectionValidation::ValidateMode::kForeground;
         }();
 
-        auto repairMode = repair ? CollectionValidation::RepairMode::kRepair
-                                 : CollectionValidation::RepairMode::kNone;
+        auto repairMode = [&] {
+            switch (mode) {
+                case CollectionValidation::ValidateMode::kForeground:
+                case CollectionValidation::ValidateMode::kForegroundFull:
+                case CollectionValidation::ValidateMode::kForegroundFullIndexOnly:
+                    // Foreground validation may not repair data while running as a replica set node
+                    // because we do not have timestamps that are required to perform writes.
+                    if (replCoord->isReplEnabled()) {
+                        return CollectionValidation::RepairMode::kNone;
+                    }
+                    if (repair) {
+                        return CollectionValidation::RepairMode::kFixErrors;
+                    }
+                    // Foreground validation will adjust multikey metadata by default.
+                    return CollectionValidation::RepairMode::kAdjustMultikey;
+                default:
+                    return CollectionValidation::RepairMode::kNone;
+            }
+        }();
 
         if (repair) {
             opCtx->recoveryUnit()->setPrepareConflictBehavior(