Add MapFlags::hugetlb_with_size method

src/backend/linux_raw/mm/types.rs

@@ -111,6 +111,26 @@ bitflags! {
     }
 }
 
+impl MapFlags {
+    /// Create `MAP_HUGETLB` with provided size of huge page.
+    ///
+    /// Under the hood it computes `MAP_HUGETLB | (huge_page_size_log2 << MAP_HUGE_SHIFT)`.
+    /// `huge_page_size_log2` denotes logarithm of huge page size to use and should between 16 and 63
+    /// (inclusively). For example, `MapFlags::map_hugetlb_with_shift(30)` returns value equal to
+    /// `Some(MapFlags::HUGETLB | MapFlags::HUGE_1GB)`.
+    #[cfg(target_os = "linux")]
+    #[cfg_attr(docsrs, doc(cfg(all())))]
+    pub fn hugetlb_with_size(huge_page_size_log2: u32) -> Option<Self> {
+        use linux_raw_sys::general::{MAP_HUGETLB, MAP_HUGE_SHIFT};
+        if (16..=63).contains(&huge_page_size_log2) {
+            let bits = MAP_HUGETLB | (huge_page_size_log2 << MAP_HUGE_SHIFT);
+            Self::from_bits(bits)
+        } else {
+            None
+        }
+    }
+}
+
 bitflags! {
     /// `MREMAP_*` flags for use with [`mremap`].
     ///