[PATCH v2 4/6] mm: mempolicy: intruduce a helper huge_nodemask()

[Huang Shijie <shijie.huang@xxxxxxx>]

This patch intruduces a new helper huge_nodemask(),
we can use it to get the node mask.

This idea of the function is from the huge_zonelist().

Signed-off-by: Huang Shijie <shijie.huang@xxxxxxx>
---
 include/linux/mempolicy.h |  8 ++++++++
 mm/mempolicy.c            | 20 ++++++++++++++++++++
 2 files changed, 28 insertions(+)

diff --git a/include/linux/mempolicy.h b/include/linux/mempolicy.h
index 5e5b296..01173c6 100644
--- a/include/linux/mempolicy.h
+++ b/include/linux/mempolicy.h
@@ -145,6 +145,8 @@ extern void mpol_rebind_task(struct task_struct *tsk, const nodemask_t *new,
 				enum mpol_rebind_step step);
 extern void mpol_rebind_mm(struct mm_struct *mm, nodemask_t *new);
 
+extern nodemask_t *huge_nodemask(struct vm_area_struct *vma,
+				unsigned long addr);
 extern struct zonelist *huge_zonelist(struct vm_area_struct *vma,
 				unsigned long addr, gfp_t gfp_flags,
 				struct mempolicy **mpol, nodemask_t **nodemask);
@@ -261,6 +263,12 @@ static inline void mpol_rebind_mm(struct mm_struct *mm, nodemask_t *new)
 {
 }
 
+static inline nodemask_t *huge_nodemask(struct vm_area_struct *vma,
+				unsigned long addr)
+{
+	return NULL;
+}
+
 static inline struct zonelist *huge_zonelist(struct vm_area_struct *vma,
 				unsigned long addr, gfp_t gfp_flags,
 				struct mempolicy **mpol, nodemask_t **nodemask)
diff --git a/mm/mempolicy.c b/mm/mempolicy.c
index 6d3639e..4830dd6 100644
--- a/mm/mempolicy.c
+++ b/mm/mempolicy.c
@@ -1800,6 +1800,26 @@ static inline unsigned interleave_nid(struct mempolicy *pol,
 
 #ifdef CONFIG_HUGETLBFS
 /*
+ * huge_nodemask(@vma, @addr)
+ * @vma: virtual memory area whose policy is sought
+ * @addr: address in @vma for shared policy lookup and interleave policy
+ *
+ * If the effective policy is BIND, returns a pointer to the mempolicy's
+ * @nodemask.
+ */
+nodemask_t *huge_nodemask(struct vm_area_struct *vma, unsigned long addr)
+{
+	nodemask_t *nodes_mask = NULL;
+	struct mempolicy *mpol = get_vma_policy(vma, addr);
+
+	if (mpol->mode == MPOL_BIND)
+		nodes_mask = &mpol->v.nodes;
+	mpol_cond_put(mpol);
+
+	return nodes_mask;
+}
+
+/*
  * huge_zonelist(@vma, @addr, @gfp_flags, @mpol)
  * @vma: virtual memory area whose policy is sought
  * @addr: address in @vma for shared policy lookup and interleave policy
-- 
2.5.5

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