[PATCH v11 06/19] mm: slub: introduce virt_to_obj function.

[Andrey Ryabinin]

virt_to_obj takes kmem_cache address, address of slab page,
address x pointing somewhere inside slab object,
and returns address of the beginning of object.

Signed-off-by: Andrey Ryabinin <a.ryabinin@xxxxxxxxxxx>
Acked-by: Christoph Lameter <cl@xxxxxxxxx>
---
 include/linux/slub_def.h | 16 ++++++++++++++++
 1 file changed, 16 insertions(+)

diff --git a/include/linux/slub_def.h b/include/linux/slub_def.h
index 9abf04e..db7d5de 100644
--- a/include/linux/slub_def.h
+++ b/include/linux/slub_def.h
@@ -110,4 +110,20 @@ static inline void sysfs_slab_remove(struct kmem_cache *s)
 }
 #endif
 
+
+/**
+ * virt_to_obj - returns address of the beginning of object.
+ * @s: object's kmem_cache
+ * @slab_page: address of slab page
+ * @x: address within object memory range
+ *
+ * Returns address of the beginning of object
+ */
+static inline void *virt_to_obj(struct kmem_cache *s,
+				const void *slab_page,
+				const void *x)
+{
+	return (void *)x - ((x - slab_page) % s->size);
+}
+
 #endif /* _LINUX_SLUB_DEF_H */
-- 
2.2.2

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