1 files changed, 64 insertions, 0 deletions

diff --git a/mm/shmem.c b/mm/shmem.c
index 4ef9797bd430..855eaf5b8d5b 100644
--- a/mm/shmem.c
+++ b/mm/shmem.c
@@ -2559,6 +2559,45 @@ out4:
         return error;
 }
 
+#ifdef CONFIG_CGROUP_MEM_RES_CTLR
+/**
+ * mem_cgroup_get_shmem_target - find a page or entry assigned to the shmem file
+ * @inode: the inode to be searched
+ * @pgoff: the offset to be searched
+ * @pagep: the pointer for the found page to be stored
+ * @ent: the pointer for the found swap entry to be stored
+ *
+ * If a page is found, refcount of it is incremented. Callers should handle
+ * these refcount.
+ */
+void mem_cgroup_get_shmem_target(struct inode *inode, pgoff_t pgoff,
+                                        struct page **pagep, swp_entry_t *ent)
+{
+        swp_entry_t entry = { .val = 0 }, *ptr;
+        struct page *page = NULL;
+        struct shmem_inode_info *info = SHMEM_I(inode);
+
+        if ((pgoff << PAGE_CACHE_SHIFT) >= i_size_read(inode))
+                goto out;
+
+        spin_lock(&info->lock);
+        ptr = shmem_swp_entry(info, pgoff, NULL);
+#ifdef CONFIG_SWAP
+        if (ptr && ptr->val) {
+                entry.val = ptr->val;
+                page = find_get_page(&swapper_space, entry.val);
+        } else
+#endif
+                page = find_get_page(inode->i_mapping, pgoff);
+        if (ptr)
+                shmem_swp_unmap(ptr);
+        spin_unlock(&info->lock);
+out:
+        *pagep = page;
+        *ent = entry;
+}
+#endif
+
 #else /* !CONFIG_SHMEM */
 
 /*
@@ -2598,6 +2637,31 @@ int shmem_lock(struct file *file, int lock, struct user_struct *user)
         return 0;
 }
 
+#ifdef CONFIG_CGROUP_MEM_RES_CTLR
+/**
+ * mem_cgroup_get_shmem_target - find a page or entry assigned to the shmem file
+ * @inode: the inode to be searched
+ * @pgoff: the offset to be searched
+ * @pagep: the pointer for the found page to be stored
+ * @ent: the pointer for the found swap entry to be stored
+ *
+ * If a page is found, refcount of it is incremented. Callers should handle
+ * these refcount.
+ */
+void mem_cgroup_get_shmem_target(struct inode *inode, pgoff_t pgoff,
+                                        struct page **pagep, swp_entry_t *ent)
+{
+        struct page *page = NULL;
+
+        if ((pgoff << PAGE_CACHE_SHIFT) >= i_size_read(inode))
+                goto out;
+        page = find_get_page(inode->i_mapping, pgoff);
+out:
+        *pagep = page;
+        *ent = (swp_entry_t){ .val = 0 };
+}
+#endif
+
 #define shmem_vm_ops                            generic_file_vm_ops
 #define shmem_file_operations                   ramfs_file_operations
 #define shmem_get_inode(sb, dir, mode, dev, flags)      ramfs_get_inode(sb, dir, mode, dev)