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-rw-r--r--fs/xfs/xfs_ondisk.h21
1 files changed, 21 insertions, 0 deletions
diff --git a/fs/xfs/xfs_ondisk.h b/fs/xfs/xfs_ondisk.h
index d3e04d20d8d4..c8ba98fae30a 100644
--- a/fs/xfs/xfs_ondisk.h
+++ b/fs/xfs/xfs_ondisk.h
@@ -125,6 +125,27 @@ xfs_check_ondisk_structs(void)
XFS_CHECK_STRUCT_SIZE(struct xfs_inode_log_format, 56);
XFS_CHECK_STRUCT_SIZE(struct xfs_qoff_logformat, 20);
XFS_CHECK_STRUCT_SIZE(struct xfs_trans_header, 16);
+
+ /*
+ * The v5 superblock format extended several v4 header structures with
+ * additional data. While new fields are only accessible on v5
+ * superblocks, it's important that the v5 structures place original v4
+ * fields/headers in the correct location on-disk. For example, we must
+ * be able to find magic values at the same location in certain blocks
+ * regardless of superblock version.
+ *
+ * The following checks ensure that various v5 data structures place the
+ * subset of v4 metadata associated with the same type of block at the
+ * start of the on-disk block. If there is no data structure definition
+ * for certain types of v4 blocks, traverse down to the first field of
+ * common metadata (e.g., magic value) and make sure it is at offset
+ * zero.
+ */
+ XFS_CHECK_OFFSET(struct xfs_dir3_leaf, hdr.info.hdr, 0);
+ XFS_CHECK_OFFSET(struct xfs_da3_intnode, hdr.info.hdr, 0);
+ XFS_CHECK_OFFSET(struct xfs_dir3_data_hdr, hdr.magic, 0);
+ XFS_CHECK_OFFSET(struct xfs_dir3_free, hdr.hdr.magic, 0);
+ XFS_CHECK_OFFSET(struct xfs_attr3_leafblock, hdr.info.hdr, 0);
}
#endif /* __XFS_ONDISK_H */