| From | Luis Henriques <> | Subject | [PATCH 3.16.y-ckt 070/180] libxfs: pack the agfl header structure so XFS_AGFL_SIZE is correct | Date | Wed, 3 Feb 2016 22:31:16 +0000 |
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3.16.7-ckt24 -stable review patch. If anyone has any objections, please let me know.
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From: "Darrick J. Wong" <darrick.wong@oracle.com>
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 <darrick.wong@oracle.com> Reviewed-by: Dave Chinner <dchinner@redhat.com> Signed-off-by: Dave Chinner <david@fromorbit.com> [ luis: backported to 3.16: - file rename: fs/xfs/libxfs/xfs_format.h -> fs/xfs/xfs_ag.h ] Signed-off-by: Luis Henriques <luis.henriques@canonical.com> --- fs/xfs/xfs_ag.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/fs/xfs/xfs_ag.h b/fs/xfs/xfs_ag.h index 6e247a99f5db..5899b64f5786 100644 --- a/fs/xfs/xfs_ag.h +++ b/fs/xfs/xfs_ag.h @@ -232,7 +232,7 @@ 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)
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