| From | Jiri Slaby <> | Subject | [PATCH 3.12 141/142] libxfs: pack the agfl header structure so XFS_AGFL_SIZE is correct | Date | Wed, 24 Feb 2016 11:05:36 +0100 |
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From: "Darrick J. Wong" <darrick.wong@oracle.com>
3.12-stable review patch. If anyone has any objections, please let me know.
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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> Signed-off-by: Jiri Slaby <jslaby@suse.cz> --- 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 1cb740afd674..78ec58fc282e 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 -- 2.7.1
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