fs/btrfs/accessors.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * Copyright (C) 2007 Oracle.  All rights reserved.
   4  */
   5
   6 #include <asm/unaligned.h>
   7 #include "messages.h"
   8 #include "ctree.h"
   9 #include "accessors.h"
  10
  11 static bool check_setget_bounds(const struct extent_buffer *eb,
  12                                 const void *ptr, unsigned off, int size)
  13 {
  14         const unsigned long member_offset = (unsigned long)ptr + off;
  15
  16         if (unlikely(member_offset + size > eb->len)) {
  17                 btrfs_warn(eb->fs_info,
  18                 "bad eb member %s: ptr 0x%lx start %llu member offset %lu size %d",
  19                         (member_offset > eb->len ? "start" : "end"),
  20                         (unsigned long)ptr, eb->start, member_offset, size);
  21                 return false;
  22         }
  23
  24         return true;
  25 }
  26
  27 void btrfs_init_map_token(struct btrfs_map_token *token, struct extent_buffer *eb)
  28 {
  29         token->eb = eb;
  30         token->kaddr = folio_address(eb->folios[0]);
  31         token->offset = 0;
  32 }
  33
  34 /*
  35  * Macro templates that define helpers to read/write extent buffer data of a
  36  * given size, that are also used via ctree.h for access to item members by
  37  * specialized helpers.
  38  *
  39  * Generic helpers:
  40  * - btrfs_set_8 (for 8/16/32/64)
  41  * - btrfs_get_8 (for 8/16/32/64)
  42  *
  43  * Generic helpers with a token (cached address of the most recently accessed
  44  * page):
  45  * - btrfs_set_token_8 (for 8/16/32/64)
  46  * - btrfs_get_token_8 (for 8/16/32/64)
  47  *
  48  * The set/get functions handle data spanning two pages transparently, in case
  49  * metadata block size is larger than page.  Every pointer to metadata items is
  50  * an offset into the extent buffer page array, cast to a specific type.  This
  51  * gives us all the type checking.
  52  *
  53  * The extent buffer pages stored in the array folios may not form a contiguous
  54  * phyusical range, but the API functions assume the linear offset to the range
  55  * from 0 to metadata node size.
  56  */
  57
  58 #define DEFINE_BTRFS_SETGET_BITS(bits)                                  \
  59 u##bits btrfs_get_token_##bits(struct btrfs_map_token *token,           \
  60                                const void *ptr, unsigned long off)      \
  61 {                                                                       \
  62         const unsigned long member_offset = (unsigned long)ptr + off;   \
  63         const unsigned long idx = get_eb_folio_index(token->eb, member_offset); \
  64         const unsigned long oil = get_eb_offset_in_folio(token->eb,     \
  65                                                          member_offset);\
  66         const int unit_size = folio_size(token->eb->folios[0]);         \
  67         const int unit_shift = folio_shift(token->eb->folios[0]);       \
  68         const int size = sizeof(u##bits);                               \
  69         u8 lebytes[sizeof(u##bits)];                                    \
  70         const int part = unit_size - oil;                               \
  71                                                                         \
  72         ASSERT(token);                                                  \
  73         ASSERT(token->kaddr);                                           \
  74         ASSERT(check_setget_bounds(token->eb, ptr, off, size));         \
  75         if (token->offset <= member_offset &&                           \
  76             member_offset + size <= token->offset + unit_size) {        \
  77                 return get_unaligned_le##bits(token->kaddr + oil);      \
  78         }                                                               \
  79         token->kaddr = folio_address(token->eb->folios[idx]);           \
  80         token->offset = idx << unit_shift;                              \
  81         if (INLINE_EXTENT_BUFFER_PAGES == 1 || oil + size <= unit_size) \
  82                 return get_unaligned_le##bits(token->kaddr + oil);      \
  83                                                                         \
  84         memcpy(lebytes, token->kaddr + oil, part);                      \
  85         token->kaddr = folio_address(token->eb->folios[idx + 1]);       \
  86         token->offset = (idx + 1) << unit_shift;                        \
  87         memcpy(lebytes + part, token->kaddr, size - part);              \
  88         return get_unaligned_le##bits(lebytes);                         \
  89 }                                                                       \
  90 u##bits btrfs_get_##bits(const struct extent_buffer *eb,                \
  91                          const void *ptr, unsigned long off)            \
  92 {                                                                       \
  93         const unsigned long member_offset = (unsigned long)ptr + off;   \
  94         const unsigned long idx = get_eb_folio_index(eb, member_offset);\
  95         const unsigned long oil = get_eb_offset_in_folio(eb,            \
  96                                                          member_offset);\
  97         const int unit_size = folio_size(eb->folios[0]);                \
  98         char *kaddr = folio_address(eb->folios[idx]);                   \
  99         const int size = sizeof(u##bits);                               \
 100         const int part = unit_size - oil;                               \
 101         u8 lebytes[sizeof(u##bits)];                                    \
 102                                                                         \
 103         ASSERT(check_setget_bounds(eb, ptr, off, size));                \
 104         if (INLINE_EXTENT_BUFFER_PAGES == 1 || oil + size <= unit_size) \
 105                 return get_unaligned_le##bits(kaddr + oil);             \
 106                                                                         \
 107         memcpy(lebytes, kaddr + oil, part);                             \
 108         kaddr = folio_address(eb->folios[idx + 1]);                     \
 109         memcpy(lebytes + part, kaddr, size - part);                     \
 110         return get_unaligned_le##bits(lebytes);                         \
 111 }                                                                       \
 112 void btrfs_set_token_##bits(struct btrfs_map_token *token,              \
 113                             const void *ptr, unsigned long off,         \
 114                             u##bits val)                                \
 115 {                                                                       \
 116         const unsigned long member_offset = (unsigned long)ptr + off;   \
 117         const unsigned long idx = get_eb_folio_index(token->eb, member_offset); \
 118         const unsigned long oil = get_eb_offset_in_folio(token->eb,     \
 119                                                          member_offset);\
 120         const int unit_size = folio_size(token->eb->folios[0]);         \
 121         const int unit_shift = folio_shift(token->eb->folios[0]);       \
 122         const int size = sizeof(u##bits);                               \
 123         u8 lebytes[sizeof(u##bits)];                                    \
 124         const int part = unit_size - oil;                               \
 125                                                                         \
 126         ASSERT(token);                                                  \
 127         ASSERT(token->kaddr);                                           \
 128         ASSERT(check_setget_bounds(token->eb, ptr, off, size));         \
 129         if (token->offset <= member_offset &&                           \
 130             member_offset + size <= token->offset + unit_size) {        \
 131                 put_unaligned_le##bits(val, token->kaddr + oil);        \
 132                 return;                                                 \
 133         }                                                               \
 134         token->kaddr = folio_address(token->eb->folios[idx]);           \
 135         token->offset = idx << unit_shift;                              \
 136         if (INLINE_EXTENT_BUFFER_PAGES == 1 ||                          \
 137             oil + size <= unit_size) {                                  \
 138                 put_unaligned_le##bits(val, token->kaddr + oil);        \
 139                 return;                                                 \
 140         }                                                               \
 141         put_unaligned_le##bits(val, lebytes);                           \
 142         memcpy(token->kaddr + oil, lebytes, part);                      \
 143         token->kaddr = folio_address(token->eb->folios[idx + 1]);       \
 144         token->offset = (idx + 1) << unit_shift;                        \
 145         memcpy(token->kaddr, lebytes + part, size - part);              \
 146 }                                                                       \
 147 void btrfs_set_##bits(const struct extent_buffer *eb, void *ptr,        \
 148                       unsigned long off, u##bits val)                   \
 149 {                                                                       \
 150         const unsigned long member_offset = (unsigned long)ptr + off;   \
 151         const unsigned long idx = get_eb_folio_index(eb, member_offset);\
 152         const unsigned long oil = get_eb_offset_in_folio(eb,            \
 153                                                          member_offset);\
 154         const int unit_size = folio_size(eb->folios[0]);                \
 155         char *kaddr = folio_address(eb->folios[idx]);                   \
 156         const int size = sizeof(u##bits);                               \
 157         const int part = unit_size - oil;                               \
 158         u8 lebytes[sizeof(u##bits)];                                    \
 159                                                                         \
 160         ASSERT(check_setget_bounds(eb, ptr, off, size));                \
 161         if (INLINE_EXTENT_BUFFER_PAGES == 1 ||                          \
 162             oil + size <= unit_size) {                                  \
 163                 put_unaligned_le##bits(val, kaddr + oil);               \
 164                 return;                                                 \
 165         }                                                               \
 166                                                                         \
 167         put_unaligned_le##bits(val, lebytes);                           \
 168         memcpy(kaddr + oil, lebytes, part);                             \
 169         kaddr = folio_address(eb->folios[idx + 1]);                     \
 170         memcpy(kaddr, lebytes + part, size - part);                     \
 171 }
 172
 173 DEFINE_BTRFS_SETGET_BITS(8)
 174 DEFINE_BTRFS_SETGET_BITS(16)
 175 DEFINE_BTRFS_SETGET_BITS(32)
 176 DEFINE_BTRFS_SETGET_BITS(64)
 177
 178 void btrfs_node_key(const struct extent_buffer *eb,
 179                     struct btrfs_disk_key *disk_key, int nr)
 180 {
 181         unsigned long ptr = btrfs_node_key_ptr_offset(eb, nr);
 182         read_eb_member(eb, (struct btrfs_key_ptr *)ptr,
 183                        struct btrfs_key_ptr, key, disk_key);
 184 }