From: Darrick J. Wong Date: Mon, 4 Jan 2016 05:13:21 +0000 (+1100) Subject: libxfs: pack the agfl header structure so XFS_AGFL_SIZE is correct X-Git-Url: http://drtracing.org/?a=commitdiff_plain;h=96f859d;p=deliverable%2Flinux.git 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: # 3.10 - 4.4 Signed-off-by: Darrick J. Wong Reviewed-by: Dave Chinner Signed-off-by: Dave Chinner --- diff --git a/fs/xfs/libxfs/xfs_format.h b/fs/xfs/libxfs/xfs_format.h index 8774498ce0ff..e2536bb1c760 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)