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linux/fs/xfs/xfs_ondisk.h
Darrick J. Wong b7df5e9205 xfs: make struct xfs_buf_log_format have a consistent size 
Increase XFS_BLF_DATAMAP_SIZE by 1 to fill in the implied padding at the
end of struct xfs_buf_log_format.  This makes the size consistent so
that we can check it in xfs_ondisk.h, and will be needed once we start
logging attribute values.

On amd64 we get the following pahole:

struct xfs_buf_log_format {
        short unsigned int         blf_type;       /*     0     2 */
        short unsigned int         blf_size;       /*     2     2 */
        short unsigned int         blf_flags;      /*     4     2 */
        short unsigned int         blf_len;        /*     6     2 */
        long long int              blf_blkno;      /*     8     8 */
        unsigned int               blf_map_size;   /*    16     4 */
        unsigned int               blf_data_map[16]; /*    20    64 */
        /* --- cacheline 1 boundary (64 bytes) was 20 bytes ago --- */

        /* size: 88, cachelines: 2, members: 7 */
        /* padding: 4 */
        /* last cacheline: 24 bytes */
};

But on i386 we get the following:

struct xfs_buf_log_format {
        short unsigned int         blf_type;       /*     0     2 */
        short unsigned int         blf_size;       /*     2     2 */
        short unsigned int         blf_flags;      /*     4     2 */
        short unsigned int         blf_len;        /*     6     2 */
        long long int              blf_blkno;      /*     8     8 */
        unsigned int               blf_map_size;   /*    16     4 */
        unsigned int               blf_data_map[16]; /*    20    64 */
        /* --- cacheline 1 boundary (64 bytes) was 20 bytes ago --- */

        /* size: 84, cachelines: 2, members: 7 */
        /* last cacheline: 20 bytes */
};

Notice how the amd64 compiler inserts 4 bytes of padding to the end of
the structure to ensure 8-byte alignment.  Prior to "xfs: fix memory
corruption during remote attr value buffer invalidation" we would try to
write to blf_data_map[17], which is harmless on amd64 but really bad on
i386.

This shouldn't cause any changes in the ondisk logging formats because
the log code writes out the log vectors with the appropriate size for
the log item's map_size, and log recovery treats the data_map array as a
VLA.

Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
2020-01-16 08:07:23 -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_buf_log_format, 88);
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);
XFS_CHECK_STRUCT_SIZE(struct xfs_bulkstat, 192);
XFS_CHECK_STRUCT_SIZE(struct xfs_inumbers, 24);
XFS_CHECK_STRUCT_SIZE(struct xfs_bulkstat_req, 64);
XFS_CHECK_STRUCT_SIZE(struct xfs_inumbers_req, 64);
}
#endif /* __XFS_ONDISK_H */
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