SERVER-7238 fix power of 2 allocation with documents > 8mb

2 files changed, 11 insertions, 4 deletions

diff --git a/src/mongo/db/namespace_details.cpp b/src/mongo/db/namespace_details.cpp
index a830b1210e3..19f3eef4c49 100644
--- a/src/mongo/db/namespace_details.cpp
+++ b/src/mongo/db/namespace_details.cpp
@@ -753,9 +753,15 @@ namespace mongo {
 
         
         if ( isUserFlagSet( Flag_UsePowerOf2Sizes ) ) {
-            int x = bucket( minRecordSize );
-            x = bucketSizes[x];
-            return x;
+            int allocationSize = bucketSizes[ bucket( minRecordSize ) ];
+            if ( allocationSize < minRecordSize ) {
+                // if we get here, it means we're allocating more than 8mb
+                // the highest bucket is 8mb, so the above code will never return more than 8mb for allocationSize
+                // if this happens, we are going to round up to the nearest megabyte
+                fassert( 16439, bucket( minRecordSize ) == MaxBucket );
+                allocationSize = 1 + ( minRecordSize | ( ( 1 << 20 ) - 1 ) );
+            }
+            return allocationSize;
         }
 
         return static_cast<int>(minRecordSize * _paddingFactor);
diff --git a/src/mongo/db/pdfile.cpp b/src/mongo/db/pdfile.cpp
index aea2b6dbafe..701616014e0 100644
--- a/src/mongo/db/pdfile.cpp
+++ b/src/mongo/db/pdfile.cpp
@@ -1450,7 +1450,8 @@ namespace mongo {
         }
 
         int lenWHdr = d->getRecordAllocationSize( len + Record::HeaderSize );
-
+        fassert( 16440, lenWHdr >= ( len + Record::HeaderSize ) );
+        
         // If the collection is capped, check if the new object will violate a unique index
         // constraint before allocating space.
         if (d->nIndexes &&