1 // SPDX-License-Identifier: GPL-2.0 2 /* 3 * Copyright (C) 2007 Oracle. All rights reserved. 4 */ 5 6 #include <asm/unaligned.h> 7 8 #include "ctree.h" 9 get_unaligned_le8(const void * p)10 static inline u8 get_unaligned_le8(const void *p) 11 { 12 return *(u8 *)p; 13 } 14 put_unaligned_le8(u8 val,void * p)15 static inline void put_unaligned_le8(u8 val, void *p) 16 { 17 *(u8 *)p = val; 18 } 19 20 /* 21 * this is some deeply nasty code. 22 * 23 * The end result is that anyone who #includes ctree.h gets a 24 * declaration for the btrfs_set_foo functions and btrfs_foo functions, 25 * which are wrappers of btrfs_set_token_#bits functions and 26 * btrfs_get_token_#bits functions, which are defined in this file. 27 * 28 * These setget functions do all the extent_buffer related mapping 29 * required to efficiently read and write specific fields in the extent 30 * buffers. Every pointer to metadata items in btrfs is really just 31 * an unsigned long offset into the extent buffer which has been 32 * cast to a specific type. This gives us all the gcc type checking. 33 * 34 * The extent buffer api is used to do the page spanning work required to 35 * have a metadata blocksize different from the page size. 36 * 37 * There are 2 variants defined, one with a token pointer and one without. 38 */ 39 40 #define DEFINE_BTRFS_SETGET_BITS(bits) \ 41 u##bits btrfs_get_token_##bits(const struct extent_buffer *eb, \ 42 const void *ptr, unsigned long off, \ 43 struct btrfs_map_token *token) \ 44 { \ 45 unsigned long part_offset = (unsigned long)ptr; \ 46 unsigned long offset = part_offset + off; \ 47 void *p; \ 48 int err; \ 49 char *kaddr; \ 50 unsigned long map_start; \ 51 unsigned long map_len; \ 52 int size = sizeof(u##bits); \ 53 u##bits res; \ 54 \ 55 ASSERT(token); \ 56 ASSERT(token->eb == eb); \ 57 \ 58 if (token->kaddr && token->offset <= offset && \ 59 (token->offset + PAGE_SIZE >= offset + size)) { \ 60 kaddr = token->kaddr; \ 61 p = kaddr + part_offset - token->offset; \ 62 res = get_unaligned_le##bits(p + off); \ 63 return res; \ 64 } \ 65 err = map_private_extent_buffer(eb, offset, size, \ 66 &kaddr, &map_start, &map_len); \ 67 if (err) { \ 68 __le##bits leres; \ 69 \ 70 read_extent_buffer(eb, &leres, offset, size); \ 71 return le##bits##_to_cpu(leres); \ 72 } \ 73 p = kaddr + part_offset - map_start; \ 74 res = get_unaligned_le##bits(p + off); \ 75 token->kaddr = kaddr; \ 76 token->offset = map_start; \ 77 return res; \ 78 } \ 79 u##bits btrfs_get_##bits(const struct extent_buffer *eb, \ 80 const void *ptr, unsigned long off) \ 81 { \ 82 unsigned long part_offset = (unsigned long)ptr; \ 83 unsigned long offset = part_offset + off; \ 84 void *p; \ 85 int err; \ 86 char *kaddr; \ 87 unsigned long map_start; \ 88 unsigned long map_len; \ 89 int size = sizeof(u##bits); \ 90 u##bits res; \ 91 \ 92 err = map_private_extent_buffer(eb, offset, size, \ 93 &kaddr, &map_start, &map_len); \ 94 if (err) { \ 95 __le##bits leres; \ 96 \ 97 read_extent_buffer(eb, &leres, offset, size); \ 98 return le##bits##_to_cpu(leres); \ 99 } \ 100 p = kaddr + part_offset - map_start; \ 101 res = get_unaligned_le##bits(p + off); \ 102 return res; \ 103 } \ 104 void btrfs_set_token_##bits(struct extent_buffer *eb, \ 105 const void *ptr, unsigned long off, \ 106 u##bits val, \ 107 struct btrfs_map_token *token) \ 108 { \ 109 unsigned long part_offset = (unsigned long)ptr; \ 110 unsigned long offset = part_offset + off; \ 111 void *p; \ 112 int err; \ 113 char *kaddr; \ 114 unsigned long map_start; \ 115 unsigned long map_len; \ 116 int size = sizeof(u##bits); \ 117 \ 118 ASSERT(token); \ 119 ASSERT(token->eb == eb); \ 120 \ 121 if (token->kaddr && token->offset <= offset && \ 122 (token->offset + PAGE_SIZE >= offset + size)) { \ 123 kaddr = token->kaddr; \ 124 p = kaddr + part_offset - token->offset; \ 125 put_unaligned_le##bits(val, p + off); \ 126 return; \ 127 } \ 128 err = map_private_extent_buffer(eb, offset, size, \ 129 &kaddr, &map_start, &map_len); \ 130 if (err) { \ 131 __le##bits val2; \ 132 \ 133 val2 = cpu_to_le##bits(val); \ 134 write_extent_buffer(eb, &val2, offset, size); \ 135 return; \ 136 } \ 137 p = kaddr + part_offset - map_start; \ 138 put_unaligned_le##bits(val, p + off); \ 139 token->kaddr = kaddr; \ 140 token->offset = map_start; \ 141 } \ 142 void btrfs_set_##bits(struct extent_buffer *eb, void *ptr, \ 143 unsigned long off, u##bits val) \ 144 { \ 145 unsigned long part_offset = (unsigned long)ptr; \ 146 unsigned long offset = part_offset + off; \ 147 void *p; \ 148 int err; \ 149 char *kaddr; \ 150 unsigned long map_start; \ 151 unsigned long map_len; \ 152 int size = sizeof(u##bits); \ 153 \ 154 err = map_private_extent_buffer(eb, offset, size, \ 155 &kaddr, &map_start, &map_len); \ 156 if (err) { \ 157 __le##bits val2; \ 158 \ 159 val2 = cpu_to_le##bits(val); \ 160 write_extent_buffer(eb, &val2, offset, size); \ 161 return; \ 162 } \ 163 p = kaddr + part_offset - map_start; \ 164 put_unaligned_le##bits(val, p + off); \ 165 } 166 167 DEFINE_BTRFS_SETGET_BITS(8) 168 DEFINE_BTRFS_SETGET_BITS(16) 169 DEFINE_BTRFS_SETGET_BITS(32) 170 DEFINE_BTRFS_SETGET_BITS(64) 171 btrfs_node_key(const struct extent_buffer * eb,struct btrfs_disk_key * disk_key,int nr)172 void btrfs_node_key(const struct extent_buffer *eb, 173 struct btrfs_disk_key *disk_key, int nr) 174 { 175 unsigned long ptr = btrfs_node_key_ptr_offset(nr); 176 read_eb_member(eb, (struct btrfs_key_ptr *)ptr, 177 struct btrfs_key_ptr, key, disk_key); 178 } 179