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@xxxxxxxxxx>
---
libxfs/xfs_format.h | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/libxfs/xfs_format.h b/libxfs/xfs_format.h
index 946bcd1..f6100be 100644
--- a/libxfs/xfs_format.h
+++ b/libxfs/xfs_format.h
@@ -787,7 +787,7 @@ 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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