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 = page_address(eb->pages[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 pages do 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_page_index(member_offset);     \
  64         const unsigned long oip = get_eb_offset_in_page(token->eb,      \
  65                                                         member_offset); \
  66         const int size = sizeof(u##bits);                               \
  67         u8 lebytes[sizeof(u##bits)];                                    \
  68         const int part = PAGE_SIZE - oip;                               \
  69                                                                         \
  70         ASSERT(token);                                                  \
  71         ASSERT(token->kaddr);                                           \
  72         ASSERT(check_setget_bounds(token->eb, ptr, off, size));         \
  73         if (token->offset <= member_offset &&                           \
  74             member_offset + size <= token->offset + PAGE_SIZE) {        \
  75                 return get_unaligned_le##bits(token->kaddr + oip);      \
  76         }                                                               \
  77         token->kaddr = page_address(token->eb->pages[idx]);             \
  78         token->offset = idx << PAGE_SHIFT;                              \
  79         if (INLINE_EXTENT_BUFFER_PAGES == 1 || oip + size <= PAGE_SIZE ) \
  80                 return get_unaligned_le##bits(token->kaddr + oip);      \
  81                                                                         \
  82         memcpy(lebytes, token->kaddr + oip, part);                      \
  83         token->kaddr = page_address(token->eb->pages[idx + 1]);         \
  84         token->offset = (idx + 1) << PAGE_SHIFT;                        \
  85         memcpy(lebytes + part, token->kaddr, size - part);              \
  86         return get_unaligned_le##bits(lebytes);                         \
  87 }                                                                       \
  88 u##bits btrfs_get_##bits(const struct extent_buffer *eb,                \
  89                          const void *ptr, unsigned long off)            \
  90 {                                                                       \
  91         const unsigned long member_offset = (unsigned long)ptr + off;   \
  92         const unsigned long oip = get_eb_offset_in_page(eb, member_offset); \
  93         const unsigned long idx = get_eb_page_index(member_offset);     \
  94         char *kaddr = page_address(eb->pages[idx]);                     \
  95         const int size = sizeof(u##bits);                               \
  96         const int part = PAGE_SIZE - oip;                               \
  97         u8 lebytes[sizeof(u##bits)];                                    \
  98                                                                         \
  99         ASSERT(check_setget_bounds(eb, ptr, off, size));                \
 100         if (INLINE_EXTENT_BUFFER_PAGES == 1 || oip + size <= PAGE_SIZE) \
 101                 return get_unaligned_le##bits(kaddr + oip);             \
 102                                                                         \
 103         memcpy(lebytes, kaddr + oip, part);                             \
 104         kaddr = page_address(eb->pages[idx + 1]);                       \
 105         memcpy(lebytes + part, kaddr, size - part);                     \
 106         return get_unaligned_le##bits(lebytes);                         \
 107 }                                                                       \
 108 void btrfs_set_token_##bits(struct btrfs_map_token *token,              \
 109                             const void *ptr, unsigned long off,         \
 110                             u##bits val)                                \
 111 {                                                                       \
 112         const unsigned long member_offset = (unsigned long)ptr + off;   \
 113         const unsigned long idx = get_eb_page_index(member_offset);     \
 114         const unsigned long oip = get_eb_offset_in_page(token->eb,      \
 115                                                         member_offset); \
 116         const int size = sizeof(u##bits);                               \
 117         u8 lebytes[sizeof(u##bits)];                                    \
 118         const int part = PAGE_SIZE - oip;                               \
 119                                                                         \
 120         ASSERT(token);                                                  \
 121         ASSERT(token->kaddr);                                           \
 122         ASSERT(check_setget_bounds(token->eb, ptr, off, size));         \
 123         if (token->offset <= member_offset &&                           \
 124             member_offset + size <= token->offset + PAGE_SIZE) {        \
 125                 put_unaligned_le##bits(val, token->kaddr + oip);        \
 126                 return;                                                 \
 127         }                                                               \
 128         token->kaddr = page_address(token->eb->pages[idx]);             \
 129         token->offset = idx << PAGE_SHIFT;                              \
 130         if (INLINE_EXTENT_BUFFER_PAGES == 1 || oip + size <= PAGE_SIZE) { \
 131                 put_unaligned_le##bits(val, token->kaddr + oip);        \
 132                 return;                                                 \
 133         }                                                               \
 134         put_unaligned_le##bits(val, lebytes);                           \
 135         memcpy(token->kaddr + oip, lebytes, part);                      \
 136         token->kaddr = page_address(token->eb->pages[idx + 1]);         \
 137         token->offset = (idx + 1) << PAGE_SHIFT;                        \
 138         memcpy(token->kaddr, lebytes + part, size - part);              \
 139 }                                                                       \
 140 void btrfs_set_##bits(const struct extent_buffer *eb, void *ptr,        \
 141                       unsigned long off, u##bits val)                   \
 142 {                                                                       \
 143         const unsigned long member_offset = (unsigned long)ptr + off;   \
 144         const unsigned long oip = get_eb_offset_in_page(eb, member_offset); \
 145         const unsigned long idx = get_eb_page_index(member_offset);     \
 146         char *kaddr = page_address(eb->pages[idx]);                     \
 147         const int size = sizeof(u##bits);                               \
 148         const int part = PAGE_SIZE - oip;                               \
 149         u8 lebytes[sizeof(u##bits)];                                    \
 150                                                                         \
 151         ASSERT(check_setget_bounds(eb, ptr, off, size));                \
 152         if (INLINE_EXTENT_BUFFER_PAGES == 1 || oip + size <= PAGE_SIZE) { \
 153                 put_unaligned_le##bits(val, kaddr + oip);               \
 154                 return;                                                 \
 155         }                                                               \
 156                                                                         \
 157         put_unaligned_le##bits(val, lebytes);                           \
 158         memcpy(kaddr + oip, lebytes, part);                             \
 159         kaddr = page_address(eb->pages[idx + 1]);                       \
 160         memcpy(kaddr, lebytes + part, size - part);                     \
 161 }
 162
 163 DEFINE_BTRFS_SETGET_BITS(8)
 164 DEFINE_BTRFS_SETGET_BITS(16)
 165 DEFINE_BTRFS_SETGET_BITS(32)
 166 DEFINE_BTRFS_SETGET_BITS(64)
 167
 168 void btrfs_node_key(const struct extent_buffer *eb,
 169                     struct btrfs_disk_key *disk_key, int nr)
 170 {
 171         unsigned long ptr = btrfs_node_key_ptr_offset(eb, nr);
 172         read_eb_member(eb, (struct btrfs_key_ptr *)ptr,
 173                        struct btrfs_key_ptr, key, disk_key);
 174 }