/* SPDX-License-Identifier: GPL-2.0-or-later */
/* AFS fileserver XDR types
 *
 * Copyright (C) 2018 Red Hat, Inc. All Rights Reserved.
 * Written by David Howells (dhowells@redhat.com)
 */

#ifndef XDR_FS_H
#define XDR_FS_H

struct afs_xdr_AFSFetchStatus {
        __be32  if_version;
#define AFS_FSTATUS_VERSION     1
        __be32  type;
        __be32  nlink;
        __be32  size_lo;
        __be32  data_version_lo;
        __be32  author;
        __be32  owner;
        __be32  caller_access;
        __be32  anon_access;
        __be32  mode;
        __be32  parent_vnode;
        __be32  parent_unique;
        __be32  seg_size;
        __be32  mtime_client;
        __be32  mtime_server;
        __be32  group;
        __be32  sync_counter;
        __be32  data_version_hi;
        __be32  lock_count;
        __be32  size_hi;
        __be32  abort_code;
} __packed;

#define AFS_DIR_HASHTBL_SIZE    128
#define AFS_DIR_DIRENT_SIZE     32
#define AFS_DIR_SLOTS_PER_BLOCK 64
#define AFS_DIR_BLOCK_SIZE      2048
#define AFS_DIR_BLOCKS_PER_PAGE (PAGE_SIZE / AFS_DIR_BLOCK_SIZE)
#define AFS_DIR_MAX_SLOTS       65536
#define AFS_DIR_BLOCKS_WITH_CTR 128
#define AFS_DIR_MAX_BLOCKS      1023
#define AFS_DIR_RESV_BLOCKS     1
#define AFS_DIR_RESV_BLOCKS0    13

/*
 * Directory entry structure.
 */
union afs_xdr_dirent {
        struct {
                u8              valid;
                u8              unused[1];
                __be16          hash_next;
                __be32          vnode;
                __be32          unique;
                u8              name[];
                /* When determining the number of dirent slots needed to
                 * represent a directory entry, name should be assumed to be 16
                 * bytes, due to a now-standardised (mis)calculation, but it is
                 * in fact 20 bytes in size.  afs_dir_calc_slots() should be
                 * used for this.
                 *
                 * For names longer than (16 or) 20 bytes, extra slots should
                 * be annexed to this one using the extended_name format.
                 */
        } u;
        u8                      extended_name[32];
} __packed;

/*
 * Directory block header (one at the beginning of every 2048-byte block).
 */
struct afs_xdr_dir_hdr {
        __be16          npages;
        __be16          magic;
#define AFS_DIR_MAGIC htons(1234)
        u8              reserved;
        u8              bitmap[8];
        u8              pad[19];
} __packed;

/*
 * Directory block layout
 */
union afs_xdr_dir_block {
        struct afs_xdr_dir_hdr          hdr;

        struct {
                struct afs_xdr_dir_hdr  hdr;
                u8                      alloc_ctrs[AFS_DIR_BLOCKS_WITH_CTR];
                __be16                  hashtable[AFS_DIR_HASHTBL_SIZE];
        } meta;

        union afs_xdr_dirent    dirents[AFS_DIR_SLOTS_PER_BLOCK];
} __packed;

/*
 * Directory layout on a linux VM page.
 */
struct afs_xdr_dir_page {
        union afs_xdr_dir_block blocks[AFS_DIR_BLOCKS_PER_PAGE];
};

/*
 * Calculate the number of dirent slots required for any given name length.
 * The calculation is made assuming the part of the name in the first slot is
 * 16 bytes, rather than 20, but this miscalculation is now standardised.
 */
static inline unsigned int afs_dir_calc_slots(size_t name_len)
{
        name_len++; /* NUL-terminated */
        return 1 + ((name_len + 15) / AFS_DIR_DIRENT_SIZE);
}

#endif /* XDR_FS_H */