[RFC PATCH 1/6] mm: shmem: Refactor out shmem_shared_policy() function

[Ackerley Tng <ackerleytng@xxxxxxxxxx>]

Refactor out shmem_shared_policy() to allow reading of a file's shared
mempolicy

Signed-off-by: Ackerley Tng <ackerleytng@xxxxxxxxxx>
---
 include/linux/shmem_fs.h |  7 +++++++
 mm/shmem.c               | 10 ++++++----
 2 files changed, 13 insertions(+), 4 deletions(-)

diff --git a/include/linux/shmem_fs.h b/include/linux/shmem_fs.h
index d9e57485a686..bc1eeb4b4bd9 100644
--- a/include/linux/shmem_fs.h
+++ b/include/linux/shmem_fs.h
@@ -134,6 +134,13 @@ static inline bool shmem_file(struct file *file)
 	return shmem_mapping(file->f_mapping);
 }
 
+static inline struct shared_policy *shmem_shared_policy(struct file *file)
+{
+	struct inode *inode = file_inode(file);
+
+	return &SHMEM_I(inode)->policy;
+}
+
 /*
  * If fallocate(FALLOC_FL_KEEP_SIZE) has been used, there may be pages
  * beyond i_size's notion of EOF, which fallocate has committed to reserving:
diff --git a/mm/shmem.c b/mm/shmem.c
index b053cd1f12da..4f801f398454 100644
--- a/mm/shmem.c
+++ b/mm/shmem.c
@@ -2248,20 +2248,22 @@ unsigned long shmem_get_unmapped_area(struct file *file,
 }
 
 #ifdef CONFIG_NUMA
+
 static int shmem_set_policy(struct vm_area_struct *vma, struct mempolicy *mpol)
 {
-	struct inode *inode = file_inode(vma->vm_file);
-	return mpol_set_shared_policy(&SHMEM_I(inode)->policy, vma, mpol);
+	struct shared_policy *info;
+
+	info = shmem_shared_policy(vma->vm_file);
+	return mpol_set_shared_policy(info, vma, mpol);
 }
 
 static struct mempolicy *shmem_get_policy(struct vm_area_struct *vma,
 					  unsigned long addr)
 {
-	struct inode *inode = file_inode(vma->vm_file);
 	pgoff_t index;
 
 	index = ((addr - vma->vm_start) >> PAGE_SHIFT) + vma->vm_pgoff;
-	return mpol_shared_policy_lookup(&SHMEM_I(inode)->policy, index);
+	return mpol_shared_policy_lookup(shmem_shared_policy(vma->vm_file), index);
 }
 #endif
 
-- 
2.40.0.634.g4ca3ef3211-goog