Update the incrementalfs.h header

One struct's field was wrong

Bug: 151229003
Test: Unit tests
Change-Id: Ife53bcb7d71cfaf148cc37ada4714d93ce9b468a
Merged-In: Ife53bcb7d71cfaf148cc37ada4714d93ce9b468a
diff --git a/incfs/incfs.cpp b/incfs/incfs.cpp
index 80b920b..0142f0e 100644
--- a/incfs/incfs.cpp
+++ b/incfs/incfs.cpp
@@ -863,7 +863,7 @@
     if (fd < 0) {
         return -errno;
     }
-    struct incfs_permit_fill args = {.file_descriptor = (uint64_t)fd.get()};
+    struct incfs_permit_fill args = {.file_descriptor = (uint32_t)fd.get()};
     auto err = ::ioctl(cmd, INCFS_IOC_PERMIT_FILL, &args);
     if (err < 0) {
         return -errno;
diff --git a/incfs/kernel-headers/linux/incrementalfs.h b/incfs/kernel-headers/linux/incrementalfs.h
index 5d799a9..d0c8da5 100644
--- a/incfs/kernel-headers/linux/incrementalfs.h
+++ b/incfs/kernel-headers/linux/incrementalfs.h
@@ -52,7 +52,7 @@
 
 /*
  * Fill in one or more data block. This may only be called on a handle
- * opened with INCFS_IOC_OPEN_FOR_FILLING
+ * passed as a parameter to INCFS_IOC_PERMIT_FILLING
  *
  * Returns number of blocks filled in, or error if none were
  */
@@ -154,7 +154,7 @@
  */
 struct incfs_permit_fill {
 	/* File to permit fills on */
-	__u64 file_descriptor;
+	__u32 file_descriptor;
 };
 
 enum incfs_hash_tree_algorithm {