From: Andrey Ryabinin <a.ryabinin@samsung.com>
To: linux-kernel@vger.kernel.org
Cc: Andrey Ryabinin <a.ryabinin@samsung.com>,
        Dmitry Vyukov <dvyukov@google.com>,
        Konstantin Serebryany <kcc@google.com>,
        Dmitry Chernenkov <dmitryc@google.com>,
        Andrey Konovalov <adech.fo@gmail.com>,
        Yuri Gribov <tetra2005@gmail.com>,
        Konstantin Khlebnikov <koct9i@gmail.com>,
        Sasha Levin <sasha.levin@oracle.com>, Christoph Lameter <cl@linux.com>,
        Joonsoo Kim <iamjoonsoo.kim@lge.com>,
        Andrew Morton <akpm@linux-foundation.org>,
        Dave Hansen <dave.hansen@intel.com>, Andi Kleen <andi@firstfloor.org>,
        x86@kernel.org, linux-mm@kvack.org, Pekka Enberg <penberg@kernel.org>,
        David Rientjes <rientjes@google.com>
Subject: [PATCH v11 06/19] mm: slub: introduce virt_to_obj function.
Date: Tue, 03 Feb 2015 20:42:59 +0300
Message-id: <1422985392-28652-7-git-send-email-a.ryabinin@samsung.com>
In-reply-to: <1422985392-28652-1-git-send-email-a.ryabinin@samsung.com>
References: <1404905415-9046-1-git-send-email-a.ryabinin@samsung.com>
 <1422985392-28652-1-git-send-email-a.ryabinin@samsung.com>
Sender: linux-kernel-owner@vger.kernel.org
Content-Length: 1276
Lines: 43

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@samsung.com>
Acked-by: Christoph Lameter <cl@linux.com>
---
 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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