Revert "SERVER-67036 remove floor for collMod cappedSize option to be consistent with create command"

This reverts commit 51e661694db82f5751f86a2efdd83c2427c32ed1.

2 files changed, 3 insertions, 9 deletions

diff --git a/jstests/core/capped_resize.js b/jstests/core/capped_resize.js
index 06baab6b21e..38cc7abd9a0 100644
--- a/jstests/core/capped_resize.js
+++ b/jstests/core/capped_resize.js
@@ -83,14 +83,6 @@ let verifyLimitUpdate = function(updates) {
     assert.eq(stats.count, initialDocSize);
     assert.lte(stats.size, maxSize);
 
-    // We used to not allow resizing the size of a capped collection below 4096 bytes. This
-    // restriction was lifted in SERVER-67036.
-    // We should see a reduction in collection size and count relative to the previous test case.
-    verifyLimitUpdate({cappedSize: 256});
-    stats = assert.commandWorked(cappedColl.stats());
-    assert.lt(stats.count, initialDocSize);
-    assert.lt(stats.size, maxSize);
-
     // We expect the resizing of a capped collection to fail when maxSize <= 0 and maxSize >
     // maxSizeCeiling.
     const negativeSize = -1 * maxSize;
diff --git a/src/mongo/db/catalog/coll_mod.cpp b/src/mongo/db/catalog/coll_mod.cpp
index 8af0ba8efc9..ca5f29ae55e 100644
--- a/src/mongo/db/catalog/coll_mod.cpp
+++ b/src/mongo/db/catalog/coll_mod.cpp
@@ -175,11 +175,13 @@ StatusWith<std::pair<ParsedCollModRequest, BSONObj>> parseCollModRequest(Operati
         }
 
         if (auto& cappedSize = cmr.getCappedSize()) {
+            static constexpr long long minCappedSize = 4096;
             auto swCappedSize = CollectionOptions::checkAndAdjustCappedSize(*cappedSize);
             if (!swCappedSize.isOK()) {
                 return swCappedSize.getStatus();
             }
-            parsed.cappedSize = swCappedSize.getValue();
+            parsed.cappedSize =
+                (swCappedSize.getValue() < minCappedSize) ? minCappedSize : swCappedSize.getValue();
             oplogEntryBuilder.append(CollMod::kCappedSizeFieldName, *cappedSize);
         }
         if (auto& cappedMax = cmr.getCappedMax()) {