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alistair23-linux/fs/xfs/xfs_ondisk.h
Brian Foster 670105de15 xfs: compile time offset checks for common v4/v5 metadata 
The v5 superblock format added various metadata fields (such as crc,
metadata lsn, owner uuid, etc.) to v4 metadata headers or created
new v5 headers for blocks where no such headers existed on v4. Where
v4 headers did exist, the v5 structures are careful to place v4
metadata at the original location. For example, the magic value is
expected to be at the same location in certain blocks to facilitate
version detection.

While failure of this invariant is likely to cause severe and
obvious problems at runtime, we can detect this condition at compile
time via the more recently added on-disk format check
infrastructure. Since there is no runtime cost, add some offset
checks that start with v5 structure definitions, traverse down to
the first bit of common metadata with v4 and ensure that common
metadata is at the expected offset. Note that we don't care about
blocks which had no v4 header because there is no common metadata in
those cases. No functional changes.

Signed-off-by: Brian Foster <bfoster@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
2019-02-11 16:07:01 -08:00

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// SPDX-License-Identifier: GPL-2.0
/*
* Copyright (c) 2016 Oracle.
* All Rights Reserved.
*/
#ifndef __XFS_ONDISK_H
#define __XFS_ONDISK_H
#define XFS_CHECK_STRUCT_SIZE(structname, size) \
BUILD_BUG_ON_MSG(sizeof(structname) != (size), "XFS: sizeof(" \
#structname ") is wrong, expected " #size)
#define XFS_CHECK_OFFSET(structname, member, off) \
BUILD_BUG_ON_MSG(offsetof(structname, member) != (off), \
"XFS: offsetof(" #structname ", " #member ") is wrong, " \
"expected " #off)
static inline void __init
xfs_check_ondisk_structs(void)
{
/* ag/file structures */
XFS_CHECK_STRUCT_SIZE(struct xfs_acl, 4);
XFS_CHECK_STRUCT_SIZE(struct xfs_acl_entry, 12);
XFS_CHECK_STRUCT_SIZE(struct xfs_agf, 224);
XFS_CHECK_STRUCT_SIZE(struct xfs_agfl, 36);
XFS_CHECK_STRUCT_SIZE(struct xfs_agi, 336);
XFS_CHECK_STRUCT_SIZE(struct xfs_bmbt_key, 8);
XFS_CHECK_STRUCT_SIZE(struct xfs_bmbt_rec, 16);
XFS_CHECK_STRUCT_SIZE(struct xfs_bmdr_block, 4);
XFS_CHECK_STRUCT_SIZE(struct xfs_btree_block_shdr, 48);
XFS_CHECK_STRUCT_SIZE(struct xfs_btree_block_lhdr, 64);
XFS_CHECK_STRUCT_SIZE(struct xfs_btree_block, 72);
XFS_CHECK_STRUCT_SIZE(struct xfs_dinode, 176);
XFS_CHECK_STRUCT_SIZE(struct xfs_disk_dquot, 104);
XFS_CHECK_STRUCT_SIZE(struct xfs_dqblk, 136);
XFS_CHECK_STRUCT_SIZE(struct xfs_dsb, 264);
XFS_CHECK_STRUCT_SIZE(struct xfs_dsymlink_hdr, 56);
XFS_CHECK_STRUCT_SIZE(struct xfs_inobt_key, 4);
XFS_CHECK_STRUCT_SIZE(struct xfs_inobt_rec, 16);
XFS_CHECK_STRUCT_SIZE(struct xfs_refcount_key, 4);
XFS_CHECK_STRUCT_SIZE(struct xfs_refcount_rec, 12);
XFS_CHECK_STRUCT_SIZE(struct xfs_rmap_key, 20);
XFS_CHECK_STRUCT_SIZE(struct xfs_rmap_rec, 24);
XFS_CHECK_STRUCT_SIZE(struct xfs_timestamp, 8);
XFS_CHECK_STRUCT_SIZE(xfs_alloc_key_t, 8);
XFS_CHECK_STRUCT_SIZE(xfs_alloc_ptr_t, 4);
XFS_CHECK_STRUCT_SIZE(xfs_alloc_rec_t, 8);
XFS_CHECK_STRUCT_SIZE(xfs_inobt_ptr_t, 4);
XFS_CHECK_STRUCT_SIZE(xfs_refcount_ptr_t, 4);
XFS_CHECK_STRUCT_SIZE(xfs_rmap_ptr_t, 4);
/* dir/attr trees */
XFS_CHECK_STRUCT_SIZE(struct xfs_attr3_leaf_hdr, 80);
XFS_CHECK_STRUCT_SIZE(struct xfs_attr3_leafblock, 88);
XFS_CHECK_STRUCT_SIZE(struct xfs_attr3_rmt_hdr, 56);
XFS_CHECK_STRUCT_SIZE(struct xfs_da3_blkinfo, 56);
XFS_CHECK_STRUCT_SIZE(struct xfs_da3_intnode, 64);
XFS_CHECK_STRUCT_SIZE(struct xfs_da3_node_hdr, 64);
XFS_CHECK_STRUCT_SIZE(struct xfs_dir3_blk_hdr, 48);
XFS_CHECK_STRUCT_SIZE(struct xfs_dir3_data_hdr, 64);
XFS_CHECK_STRUCT_SIZE(struct xfs_dir3_free, 64);
XFS_CHECK_STRUCT_SIZE(struct xfs_dir3_free_hdr, 64);
XFS_CHECK_STRUCT_SIZE(struct xfs_dir3_leaf, 64);
XFS_CHECK_STRUCT_SIZE(struct xfs_dir3_leaf_hdr, 64);
XFS_CHECK_STRUCT_SIZE(xfs_attr_leaf_entry_t, 8);
XFS_CHECK_STRUCT_SIZE(xfs_attr_leaf_hdr_t, 32);
XFS_CHECK_STRUCT_SIZE(xfs_attr_leaf_map_t, 4);
XFS_CHECK_STRUCT_SIZE(xfs_attr_leaf_name_local_t, 4);
/*
* m68k has problems with xfs_attr_leaf_name_remote_t, but we pad it to
* 4 bytes anyway so it's not obviously a problem. Hence for the moment
* we don't check this structure. This can be re-instated when the attr
* definitions are updated to use c99 VLA definitions.
*
XFS_CHECK_STRUCT_SIZE(xfs_attr_leaf_name_remote_t, 12);
*/
XFS_CHECK_OFFSET(xfs_attr_leaf_name_local_t, valuelen, 0);
XFS_CHECK_OFFSET(xfs_attr_leaf_name_local_t, namelen, 2);
XFS_CHECK_OFFSET(xfs_attr_leaf_name_local_t, nameval, 3);
XFS_CHECK_OFFSET(xfs_attr_leaf_name_remote_t, valueblk, 0);
XFS_CHECK_OFFSET(xfs_attr_leaf_name_remote_t, valuelen, 4);
XFS_CHECK_OFFSET(xfs_attr_leaf_name_remote_t, namelen, 8);
XFS_CHECK_OFFSET(xfs_attr_leaf_name_remote_t, name, 9);
XFS_CHECK_STRUCT_SIZE(xfs_attr_leafblock_t, 40);
XFS_CHECK_OFFSET(xfs_attr_shortform_t, hdr.totsize, 0);
XFS_CHECK_OFFSET(xfs_attr_shortform_t, hdr.count, 2);
XFS_CHECK_OFFSET(xfs_attr_shortform_t, list[0].namelen, 4);
XFS_CHECK_OFFSET(xfs_attr_shortform_t, list[0].valuelen, 5);
XFS_CHECK_OFFSET(xfs_attr_shortform_t, list[0].flags, 6);
XFS_CHECK_OFFSET(xfs_attr_shortform_t, list[0].nameval, 7);
XFS_CHECK_STRUCT_SIZE(xfs_da_blkinfo_t, 12);
XFS_CHECK_STRUCT_SIZE(xfs_da_intnode_t, 16);
XFS_CHECK_STRUCT_SIZE(xfs_da_node_entry_t, 8);
XFS_CHECK_STRUCT_SIZE(xfs_da_node_hdr_t, 16);
XFS_CHECK_STRUCT_SIZE(xfs_dir2_data_free_t, 4);
XFS_CHECK_STRUCT_SIZE(xfs_dir2_data_hdr_t, 16);
XFS_CHECK_OFFSET(xfs_dir2_data_unused_t, freetag, 0);
XFS_CHECK_OFFSET(xfs_dir2_data_unused_t, length, 2);
XFS_CHECK_STRUCT_SIZE(xfs_dir2_free_hdr_t, 16);
XFS_CHECK_STRUCT_SIZE(xfs_dir2_free_t, 16);
XFS_CHECK_STRUCT_SIZE(xfs_dir2_leaf_entry_t, 8);
XFS_CHECK_STRUCT_SIZE(xfs_dir2_leaf_hdr_t, 16);
XFS_CHECK_STRUCT_SIZE(xfs_dir2_leaf_t, 16);
XFS_CHECK_STRUCT_SIZE(xfs_dir2_leaf_tail_t, 4);
XFS_CHECK_STRUCT_SIZE(xfs_dir2_sf_entry_t, 3);
XFS_CHECK_OFFSET(xfs_dir2_sf_entry_t, namelen, 0);
XFS_CHECK_OFFSET(xfs_dir2_sf_entry_t, offset, 1);
XFS_CHECK_OFFSET(xfs_dir2_sf_entry_t, name, 3);
XFS_CHECK_STRUCT_SIZE(xfs_dir2_sf_hdr_t, 10);
/* log structures */
XFS_CHECK_STRUCT_SIZE(struct xfs_dq_logformat, 24);
XFS_CHECK_STRUCT_SIZE(struct xfs_efd_log_format_32, 28);
XFS_CHECK_STRUCT_SIZE(struct xfs_efd_log_format_64, 32);
XFS_CHECK_STRUCT_SIZE(struct xfs_efi_log_format_32, 28);
XFS_CHECK_STRUCT_SIZE(struct xfs_efi_log_format_64, 32);
XFS_CHECK_STRUCT_SIZE(struct xfs_extent_32, 12);
XFS_CHECK_STRUCT_SIZE(struct xfs_extent_64, 16);
XFS_CHECK_STRUCT_SIZE(struct xfs_log_dinode, 176);
XFS_CHECK_STRUCT_SIZE(struct xfs_icreate_log, 28);
XFS_CHECK_STRUCT_SIZE(struct xfs_ictimestamp, 8);
XFS_CHECK_STRUCT_SIZE(struct xfs_inode_log_format_32, 52);
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 */
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