linux-kernel - [PATCH 4.9 20/24] gfs2: Avoid alignment hole in struct lm

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Message-Id: <20170324151226.515605209@linuxfoundation.org>
Date:   Fri, 24 Mar 2017 18:58:53 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Andreas Gruenbacher <agruenba@...hat.com>,
        Bob Peterson <rpeterso@...hat.com>
Subject: [PATCH 4.9 20/24] gfs2: Avoid alignment hole in struct lm_lockname

4.9-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Andreas Gruenbacher <agruenba@...hat.com>

commit 28ea06c46fbcab63fd9a55531387b7928a18a590 upstream.

Commit 88ffbf3e03 switches to using rhashtables for glocks, hashing over
the entire struct lm_lockname instead of its individual fields.  On some
architectures, struct lm_lockname contains a hole of uninitialized
memory due to alignment rules, which now leads to incorrect hash values.
Get rid of that hole.

Signed-off-by: Andreas Gruenbacher <agruenba@...hat.com>
Signed-off-by: Bob Peterson <rpeterso@...hat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 fs/gfs2/incore.h |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/fs/gfs2/incore.h
+++ b/fs/gfs2/incore.h
@@ -207,7 +207,7 @@ struct lm_lockname {
 	struct gfs2_sbd *ln_sbd;
 	u64 ln_number;
 	unsigned int ln_type;
-};
+} __packed __aligned(sizeof(int));
 
 #define lm_name_equal(name1, name2) \
         (((name1)->ln_number == (name2)->ln_number) &&	\