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From: Andrey Ryabinin <a.ryabinin@samsung.com>
Subject: [PATCH v5 06/12] mm: slub: introduce virt_to_obj function.
Date: Mon, 27 Oct 2014 19:46:53 +0300
Message-id: <1414428419-17860-7-git-send-email-a.ryabinin@samsung.com>
In-reply-to: <1414428419-17860-1-git-send-email-a.ryabinin@samsung.com>
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 <1414428419-17860-1-git-send-email-a.ryabinin@samsung.com>
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To: Andrew Morton <akpm@linux-foundation.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>, Dave Hansen <dave.hansen@intel.com>, Andi Kleen <andi@firstfloor.org>, Vegard Nossum <vegard.nossum@gmail.com>, "H. Peter Anvin" <hpa@zytor.com>, Dave Jones <davej@redhat.com>, x86@kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, Pekka Enberg <penberg@kernel.org>, David Rientjes <rientjes@google.com>

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

Signed-off-by: Andrey Ryabinin <a.ryabinin@samsung.com>
---
 include/linux/slub_def.h | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/include/linux/slub_def.h b/include/linux/slub_def.h
index d82abd4..c75bc1d 100644
--- a/include/linux/slub_def.h
+++ b/include/linux/slub_def.h
@@ -110,4 +110,9 @@ static inline void sysfs_slab_remove(struct kmem_cache *s)
 }
 #endif
 
+static inline void *virt_to_obj(struct kmem_cache *s, void *slab_page, void *x)
+{
+	return x - ((x - slab_page) % s->size);
+}
+
 #endif /* _LINUX_SLUB_DEF_H */
-- 
2.1.2

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