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