FAILED: patch "[PATCH] libxfs: pack the agfl header structure so XFS_AGFL_SIZE is" failed to apply to 3.14-stable tree

The patch below does not apply to the 3.14-stable tree.
If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <[email protected]>.

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From: "Darrick J. Wong" <[email protected]>
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.

index 8774498ce0ff..e2536bb1c760 100644
@@ -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)