[PATCHv2 02/13] mm, thp, tmpfs: add function to alloc huge page for tmpfs

[Ning Qu <quning@google.com>]

Add function to alloc huge page for tmpfs when needed.

Signed-off-by: Ning Qu <quning@gmail.com>
---
 mm/shmem.c | 29 +++++++++++++++++++++++++++++
 1 file changed, 29 insertions(+)

diff --git a/mm/shmem.c b/mm/shmem.c
index 8297623..a857ba8 100644
--- a/mm/shmem.c
+++ b/mm/shmem.c
@@ -949,6 +949,28 @@ static struct page *shmem_alloc_page(gfp_t gfp,
 
 	return page;
 }
+
+static struct page *shmem_alloc_hugepage(gfp_t gfp,
+			struct shmem_inode_info *info, pgoff_t index)
+{
+	struct vm_area_struct pvma;
+	struct page *page;
+
+	/* Create a pseudo vma that just contains the policy */
+	pvma.vm_start = 0;
+	pvma.vm_pgoff = index;
+	pvma.vm_ops = NULL;
+	pvma.vm_policy = mpol_shared_policy_lookup(&info->policy, index);
+	pvma.vm_flags = VM_HUGEPAGE;
+
+	page = alloc_hugepage_vma(transparent_hugepage_defrag(&pvma), &pvma,
+					0, numa_node_id(), gfp);
+
+	/* Drop reference taken by mpol_shared_policy_lookup() */
+	mpol_cond_put(pvma.vm_policy);
+
+	return page;
+}
 #else /* !CONFIG_NUMA */
 #ifdef CONFIG_TMPFS
 static inline void shmem_show_mpol(struct seq_file *seq, struct mempolicy *mpol)
@@ -967,6 +989,13 @@ static inline struct page *shmem_alloc_page(gfp_t gfp,
 {
 	return alloc_page(gfp);
 }
+
+static inline struct page *shmem_alloc_hugepage(gfp_t gfp,
+			struct shmem_inode_info *info, pgoff_t index)
+{
+	BUG();
+	return NULL;
+}
 #endif /* CONFIG_NUMA */
 
 #if !defined(CONFIG_NUMA) || !defined(CONFIG_TMPFS)
-- 
1.8.4

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