diff --git a/[refs] b/[refs]
index f4ba51cc46a9..1c880488db21 100644
--- a/[refs]
+++ b/[refs]
@@ -1,2 +1,2 @@
 ---
-refs/heads/master: eb178619f930fa2ba2348de332a1ff1c66a31424
+refs/heads/master: f2a459565b02b60408f3f2e5ca992a031319712b
diff --git a/trunk/fs/xfs/xfs_iomap.c b/trunk/fs/xfs/xfs_iomap.c
index add06b4e9a63..364818eef40e 100644
--- a/trunk/fs/xfs/xfs_iomap.c
+++ b/trunk/fs/xfs/xfs_iomap.c
@@ -351,6 +351,15 @@ xfs_iomap_prealloc_size(
 		}
 		if (shift)
 			alloc_blocks >>= shift;
+
+		/*
+		 * If we are still trying to allocate more space than is
+		 * available, squash the prealloc hard. This can happen if we
+		 * have a large file on a small filesystem and the above
+		 * lowspace thresholds are smaller than MAXEXTLEN.
+		 */
+		while (alloc_blocks >= freesp)
+			alloc_blocks >>= 4;
 	}
 
 	if (alloc_blocks < mp->m_writeio_blocks)