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 /* ugly, but we want the fast path here */ \ 54 if (eb->map_token && offset >= eb->map_start && \ 55 offset + sizeof(((type *)0)->member) <= eb->map_start + \ 56 eb->map_len) { \ 57 p = (type *)(eb->kaddr + part_offset - eb->map_start); \ 58 return le##bits##_to_cpu(p->member); \ 59 } \ 60 { \ 61 int err; \ 62 char *map_token; \ 63 char *kaddr; \ 64 int unmap_on_exit = (eb->map_token == NULL); \ 65 unsigned long map_start; \ 66 unsigned long map_len; \ 67 u##bits res; \ 68 err = map_extent_buffer(eb, offset, \ 69 sizeof(((type *)0)->member), \ 70 &map_token, &kaddr, \ 71 &map_start, &map_len, KM_USER1); \ 72 if (err) { \ 73 __le##bits leres; \ 74 read_eb_member(eb, s, type, member, &leres); \ 75 return le##bits##_to_cpu(leres); \ 76 } \ 77 p = (type *)(kaddr + part_offset - map_start); \ 78 res = le##bits##_to_cpu(p->member); \ 79 if (unmap_on_exit) \ 80 unmap_extent_buffer(eb, map_token, KM_USER1); \ 81 return res; \ 82 } \ 83} \ 84void btrfs_set_##name(struct extent_buffer *eb, \ 85 type *s, u##bits val) \ 86{ \ 87 unsigned long part_offset = (unsigned long)s; \ 88 unsigned long offset = part_offset + offsetof(type, member); \ 89 type *p; \ 90 /* ugly, but we want the fast path here */ \ 91 if (eb->map_token && offset >= eb->map_start && \ 92 offset + sizeof(((type *)0)->member) <= eb->map_start + \ 93 eb->map_len) { \ 94 p = (type *)(eb->kaddr + part_offset - eb->map_start); \ 95 p->member = cpu_to_le##bits(val); \ 96 return; \ 97 } \ 98 { \ 99 int err; \ 100 char *map_token; \ 101 char *kaddr; \ 102 int unmap_on_exit = (eb->map_token == NULL); \ 103 unsigned long map_start; \ 104 unsigned long map_len; \ 105 err = map_extent_buffer(eb, offset, \ 106 sizeof(((type *)0)->member), \ 107 &map_token, &kaddr, \ 108 &map_start, &map_len, KM_USER1); \ 109 if (err) { \ 110 __le##bits val2; \ 111 val2 = cpu_to_le##bits(val); \ 112 write_eb_member(eb, s, type, member, &val2); \ 113 return; \ 114 } \ 115 p = (type *)(kaddr + part_offset - map_start); \ 116 p->member = cpu_to_le##bits(val); \ 117 if (unmap_on_exit) \ 118 unmap_extent_buffer(eb, map_token, KM_USER1); \ 119 } \ 120} 121 122#include "ctree.h" 123 124void btrfs_node_key(struct extent_buffer *eb, 125 struct btrfs_disk_key *disk_key, int nr) 126{ 127 unsigned long ptr = btrfs_node_key_ptr_offset(nr); 128 if (eb->map_token && ptr >= eb->map_start && 129 ptr + sizeof(*disk_key) <= eb->map_start + eb->map_len) { 130 memcpy(disk_key, eb->kaddr + ptr - eb->map_start, 131 sizeof(*disk_key)); 132 return; 133 } else if (eb->map_token) { 134 unmap_extent_buffer(eb, eb->map_token, KM_USER1); 135 eb->map_token = NULL; 136 } 137 read_eb_member(eb, (struct btrfs_key_ptr *)ptr, 138 struct btrfs_key_ptr, key, disk_key); 139} 140