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-Tag: v3.12.55~2 X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=811848048f1e4d74efaf299b0eba05ef50bc3e4f;p=thirdparty%2Fkernel%2Fstable.git libxfs: pack the agfl header structure so XFS_AGFL_SIZE is correct commit 96f859d52bcb1c6ea6f3388d39862bf7143e2f30 upstream. 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. Signed-off-by: Darrick J. Wong Reviewed-by: Dave Chinner Signed-off-by: Dave Chinner Signed-off-by: Jiri Slaby --- diff --git a/fs/xfs/xfs_ag.h b/fs/xfs/xfs_ag.h index 1cb740afd674e..78ec58fc282e9 100644 --- a/fs/xfs/xfs_ag.h +++ b/fs/xfs/xfs_ag.h @@ -224,7 +224,7 @@ 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; /* * tags for inode radix tree