1/* 2 * Copyright (C) 2007 Oracle. All rights reserved. 3 * 4 * This program is free software; you can redistribute it and/or 5 * modify it under the terms of the GNU General Public 6 * License v2 as published by the Free Software Foundation. 7 * 8 * This program is distributed in the hope that it will be useful, 9 * but WITHOUT ANY WARRANTY; without even the implied warranty of 10 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU 11 * General Public License for more details. 12 * 13 * You should have received a copy of the GNU General Public 14 * License along with this program; if not, write to the 15 * Free Software Foundation, Inc., 59 Temple Place - Suite 330, 16 * Boston, MA 021110-1307, USA. 17 */ 18 19#include <linux/highmem.h> 20 21/* this is some deeply nasty code. ctree.h has a different 22 * definition for this BTRFS_SETGET_FUNCS macro, behind a #ifndef 23 * 24 * The end result is that anyone who #includes ctree.h gets a 25 * declaration for the btrfs_set_foo functions and btrfs_foo functions 26 * 27 * This file declares the macros and then #includes ctree.h, which results 28 * in cpp creating the function here based on the template below. 29 * 30 * These setget functions do all the extent_buffer related mapping 31 * required to efficiently read and write specific fields in the extent 32 * buffers. Every pointer to metadata items in btrfs is really just 33 * an unsigned long offset into the extent buffer which has been 34 * cast to a specific type. This gives us all the gcc type checking. 35 * 36 * The extent buffer api is used to do all the kmapping and page 37 * spanning work required to get extent buffers in highmem and have 38 * a metadata blocksize different from the page size. 39 * 40 * The macro starts with a simple function prototype declaration so that 41 * sparse won't complain about it being static. 42 */ 43 44#define BTRFS_SETGET_FUNCS(name, type, member, bits) \ 45u##bits btrfs_##name(struct extent_buffer *eb, type *s); \ 46void btrfs_set_##name(struct extent_buffer *eb, type *s, u##bits val); \ 47u##bits btrfs_##name(struct extent_buffer *eb, \ 48 type *s) \ 49{ \ 50 unsigned long part_offset = (unsigned long)s; \ 51 unsigned long offset = part_offset + offsetof(type, member); \ 52 type *p; \ 53 int err; \ 54 char *kaddr; \ 55 unsigned long map_start; \ 56 unsigned long map_len; \ 57 u##bits res; \ 58 err = map_private_extent_buffer(eb, offset, \ 59 sizeof(((type *)0)->member), \ 60 &kaddr, &map_start, &map_len); \ 61 if (err) { \ 62 __le##bits leres; \ 63 read_eb_member(eb, s, type, member, &leres); \ 64 return le##bits##_to_cpu(leres); \ 65 } \ 66 p = (type *)(kaddr + part_offset - map_start); \ 67 res = le##bits##_to_cpu(p->member); \ 68 return res; \ 69} \ 70void btrfs_set_##name(struct extent_buffer *eb, \ 71 type *s, u##bits val) \ 72{ \ 73 unsigned long part_offset = (unsigned long)s; \ 74 unsigned long offset = part_offset + offsetof(type, member); \ 75 type *p; \ 76 int err; \ 77 char *kaddr; \ 78 unsigned long map_start; \ 79 unsigned long map_len; \ 80 err = map_private_extent_buffer(eb, offset, \ 81 sizeof(((type *)0)->member), \ 82 &kaddr, &map_start, &map_len); \ 83 if (err) { \ 84 __le##bits val2; \ 85 val2 = cpu_to_le##bits(val); \ 86 write_eb_member(eb, s, type, member, &val2); \ 87 return; \ 88 } \ 89 p = (type *)(kaddr + part_offset - map_start); \ 90 p->member = cpu_to_le##bits(val); \ 91} 92 93#include "ctree.h" 94 95void btrfs_node_key(struct extent_buffer *eb, 96 struct btrfs_disk_key *disk_key, int nr) 97{ 98 unsigned long ptr = btrfs_node_key_ptr_offset(nr); 99 read_eb_member(eb, (struct btrfs_key_ptr *)ptr, 100 struct btrfs_key_ptr, key, disk_key); 101} 102