From 96f859d52bcb1c6ea6f3388d39862bf7143e2f30 Mon Sep 17 00:00:00 2001
From: "Darrick J. Wong" <darrick.wong@oracle.com>
Date: Mon, 4 Jan 2016 16:13:21 +1100
Subject: [PATCH] libxfs: pack the agfl header structure so XFS_AGFL_SIZE is
correct
Because struct xfs_agfl is 36 bytes long and has a 64-bit integer
inside it, gcc will quietly round the structure size up to the nearest
64 bits -- in this case, 40 bytes. This results in the XFS_AGFL_SIZE
macro returning incorrect results for v5 filesystems on 64-bit
machines (118 items instead of 119). As a result, a 32-bit xfs_repair
will see garbage in AGFL item 119 and complain.
Therefore, tell gcc not to pad the structure so that the AGFL size
calculation is correct.
cc: <stable@vger.kernel.org> # 3.10 - 4.4
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Signed-off-by: Dave Chinner <david@fromorbit.com>
---
fs/xfs/libxfs/xfs_format.h | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/fs/xfs/libxfs/xfs_format.h b/fs/xfs/libxfs/xfs_format.h
index 8774498ce0ffa..e2536bb1c7600 100644
--- a/fs/xfs/libxfs/xfs_format.h
+++ b/fs/xfs/libxfs/xfs_format.h
@@ -786,7 +786,7 @@ typedef struct xfs_agfl {
__be64 agfl_lsn;
__be32 agfl_crc;
__be32 agfl_bno[]; /* actually XFS_AGFL_SIZE(mp) */
-} xfs_agfl_t;
+} __attribute__((packed)) xfs_agfl_t;
#define XFS_AGFL_CRC_OFF offsetof(struct xfs_agfl, agfl_crc)
--
2.30.2