fs/btrfs/accessors.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * Copyright (C) 2007 Oracle.  All rights reserved.
   4  */
   5
   6 #include <linux/unaligned.h>
   7 #include "messages.h"
   8 #include "extent_io.h"
   9 #include "fs.h"
  10 #include "accessors.h"
  11
  12 static bool check_setget_bounds(const struct extent_buffer *eb,
  13                                 const void *ptr, unsigned off, int size)
  14 {
  15         const unsigned long member_offset = (unsigned long)ptr + off;
  16
  17         if (unlikely(member_offset + size > eb->len)) {
  18                 btrfs_warn(eb->fs_info,
  19                 "bad eb member %s: ptr 0x%lx start %llu member offset %lu size %d",
  20                         (member_offset > eb->len ? "start" : "end"),
  21                         (unsigned long)ptr, eb->start, member_offset, size);
  22                 return false;
  23         }
  24
  25         return true;
  26 }
  27
  28 void btrfs_init_map_token(struct btrfs_map_token *token, struct extent_buffer *eb)
  29 {
  30         token->eb = eb;
  31         token->kaddr = folio_address(eb->folios[0]);
  32         token->offset = 0;
  33 }
  34
  35 /*
  36  * Macro templates that define helpers to read/write extent buffer data of a
  37  * given size, that are also used via ctree.h for access to item members by
  38  * specialized helpers.
  39  *
  40  * Generic helpers:
  41  * - btrfs_set_8 (for 8/16/32/64)
  42  * - btrfs_get_8 (for 8/16/32/64)
  43  *
  44  * Generic helpers with a token (cached address of the most recently accessed
  45  * page):
  46  * - btrfs_set_token_8 (for 8/16/32/64)
  47  * - btrfs_get_token_8 (for 8/16/32/64)
  48  *
  49  * The set/get functions handle data spanning two pages transparently, in case
  50  * metadata block size is larger than page.  Every pointer to metadata items is
  51  * an offset into the extent buffer page array, cast to a specific type.  This
  52  * gives us all the type checking.
  53  *
  54  * The extent buffer pages stored in the array folios may not form a contiguous
  55  * phyusical range, but the API functions assume the linear offset to the range
  56  * from 0 to metadata node size.
  57  */
  58
  59 #define DEFINE_BTRFS_SETGET_BITS(bits)                                  \
  60 u##bits btrfs_get_token_##bits(struct btrfs_map_token *token,           \
  61                                const void *ptr, unsigned long off)      \
  62 {                                                                       \
  63         const unsigned long member_offset = (unsigned long)ptr + off;   \
  64         const unsigned long idx = get_eb_folio_index(token->eb, member_offset); \
  65         const unsigned long oil = get_eb_offset_in_folio(token->eb,     \
  66                                                          member_offset);\
  67         const int unit_size = token->eb->folio_size;                    \
  68         const int unit_shift = token->eb->folio_shift;                  \
  69         const int size = sizeof(u##bits);                               \
  70         u8 lebytes[sizeof(u##bits)];                                    \
  71         const int part = unit_size - oil;                               \
  72                                                                         \
  73         ASSERT(token);                                                  \
  74         ASSERT(token->kaddr);                                           \
  75         ASSERT(check_setget_bounds(token->eb, ptr, off, size));         \
  76         if (token->offset <= member_offset &&                           \
  77             member_offset + size <= token->offset + unit_size) {        \
  78                 return get_unaligned_le##bits(token->kaddr + oil);      \
  79         }                                                               \
  80         token->kaddr = folio_address(token->eb->folios[idx]);           \
  81         token->offset = idx << unit_shift;                              \
  82         if (INLINE_EXTENT_BUFFER_PAGES == 1 || oil + size <= unit_size) \
  83                 return get_unaligned_le##bits(token->kaddr + oil);      \
  84                                                                         \
  85         memcpy(lebytes, token->kaddr + oil, part);                      \
  86         token->kaddr = folio_address(token->eb->folios[idx + 1]);       \
  87         token->offset = (idx + 1) << unit_shift;                        \
  88         memcpy(lebytes + part, token->kaddr, size - part);              \
  89         return get_unaligned_le##bits(lebytes);                         \
  90 }                                                                       \
  91 u##bits btrfs_get_##bits(const struct extent_buffer *eb,                \
  92                          const void *ptr, unsigned long off)            \
  93 {                                                                       \
  94         const unsigned long member_offset = (unsigned long)ptr + off;   \
  95         const unsigned long idx = get_eb_folio_index(eb, member_offset);\
  96         const unsigned long oil = get_eb_offset_in_folio(eb,            \
  97                                                          member_offset);\
  98         const int unit_size = eb->folio_size;                           \
  99         char *kaddr = folio_address(eb->folios[idx]);                   \
 100         const int size = sizeof(u##bits);                               \
 101         const int part = unit_size - oil;                               \
 102         u8 lebytes[sizeof(u##bits)];                                    \
 103                                                                         \
 104         ASSERT(check_setget_bounds(eb, ptr, off, size));                \
 105         if (INLINE_EXTENT_BUFFER_PAGES == 1 || oil + size <= unit_size) \
 106                 return get_unaligned_le##bits(kaddr + oil);             \
 107                                                                         \
 108         memcpy(lebytes, kaddr + oil, part);                             \
 109         kaddr = folio_address(eb->folios[idx + 1]);                     \
 110         memcpy(lebytes + part, kaddr, size - part);                     \
 111         return get_unaligned_le##bits(lebytes);                         \
 112 }                                                                       \
 113 void btrfs_set_token_##bits(struct btrfs_map_token *token,              \
 114                             const void *ptr, unsigned long off,         \
 115                             u##bits val)                                \
 116 {                                                                       \
 117         const unsigned long member_offset = (unsigned long)ptr + off;   \
 118         const unsigned long idx = get_eb_folio_index(token->eb, member_offset); \
 119         const unsigned long oil = get_eb_offset_in_folio(token->eb,     \
 120                                                          member_offset);\
 121         const int unit_size = token->eb->folio_size;                    \
 122         const int unit_shift = token->eb->folio_shift;                  \
 123         const int size = sizeof(u##bits);                               \
 124         u8 lebytes[sizeof(u##bits)];                                    \
 125         const int part = unit_size - oil;                               \
 126                                                                         \
 127         ASSERT(token);                                                  \
 128         ASSERT(token->kaddr);                                           \
 129         ASSERT(check_setget_bounds(token->eb, ptr, off, size));         \
 130         if (token->offset <= member_offset &&                           \
 131             member_offset + size <= token->offset + unit_size) {        \
 132                 put_unaligned_le##bits(val, token->kaddr + oil);        \
 133                 return;                                                 \
 134         }                                                               \
 135         token->kaddr = folio_address(token->eb->folios[idx]);           \
 136         token->offset = idx << unit_shift;                              \
 137         if (INLINE_EXTENT_BUFFER_PAGES == 1 ||                          \
 138             oil + size <= unit_size) {                                  \
 139                 put_unaligned_le##bits(val, token->kaddr + oil);        \
 140                 return;                                                 \
 141         }                                                               \
 142         put_unaligned_le##bits(val, lebytes);                           \
 143         memcpy(token->kaddr + oil, lebytes, part);                      \
 144         token->kaddr = folio_address(token->eb->folios[idx + 1]);       \
 145         token->offset = (idx + 1) << unit_shift;                        \
 146         memcpy(token->kaddr, lebytes + part, size - part);              \
 147 }                                                                       \
 148 void btrfs_set_##bits(const struct extent_buffer *eb, void *ptr,        \
 149                       unsigned long off, u##bits val)                   \
 150 {                                                                       \
 151         const unsigned long member_offset = (unsigned long)ptr + off;   \
 152         const unsigned long idx = get_eb_folio_index(eb, member_offset);\
 153         const unsigned long oil = get_eb_offset_in_folio(eb,            \
 154                                                          member_offset);\
 155         const int unit_size = eb->folio_size;                           \
 156         char *kaddr = folio_address(eb->folios[idx]);                   \
 157         const int size = sizeof(u##bits);                               \
 158         const int part = unit_size - oil;                               \
 159         u8 lebytes[sizeof(u##bits)];                                    \
 160                                                                         \
 161         ASSERT(check_setget_bounds(eb, ptr, off, size));                \
 162         if (INLINE_EXTENT_BUFFER_PAGES == 1 ||                          \
 163             oil + size <= unit_size) {                                  \
 164                 put_unaligned_le##bits(val, kaddr + oil);               \
 165                 return;                                                 \
 166         }                                                               \
 167                                                                         \
 168         put_unaligned_le##bits(val, lebytes);                           \
 169         memcpy(kaddr + oil, lebytes, part);                             \
 170         kaddr = folio_address(eb->folios[idx + 1]);                     \
 171         memcpy(kaddr, lebytes + part, size - part);                     \
 172 }
 173
 174 DEFINE_BTRFS_SETGET_BITS(8)
 175 DEFINE_BTRFS_SETGET_BITS(16)
 176 DEFINE_BTRFS_SETGET_BITS(32)
 177 DEFINE_BTRFS_SETGET_BITS(64)
 178
 179 void btrfs_node_key(const struct extent_buffer *eb,
 180                     struct btrfs_disk_key *disk_key, int nr)
 181 {
 182         unsigned long ptr = btrfs_node_key_ptr_offset(eb, nr);
 183         read_eb_member(eb, (struct btrfs_key_ptr *)ptr,
 184                        struct btrfs_key_ptr, key, disk_key);
 185 }