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 inline u8 get_unaligned_le8(const void *p)
  11 {
  12        return *(u8 *)p;
  13 }
  14
  15 static inline void put_unaligned_le8(u8 val, void *p)
  16 {
  17        *(u8 *)p = val;
  18 }
  19
  20 static bool check_setget_bounds(const struct extent_buffer *eb,
  21                                 const void *ptr, unsigned off, int size)
  22 {
  23         const unsigned long member_offset = (unsigned long)ptr + off;
  24
  25         if (member_offset > eb->len) {
  26                 btrfs_warn(eb->fs_info,
  27         "bad eb member start: ptr 0x%lx start %llu member offset %lu size %d",
  28                         (unsigned long)ptr, eb->start, member_offset, size);
  29                 return false;
  30         }
  31         if (member_offset + size > eb->len) {
  32                 btrfs_warn(eb->fs_info,
  33         "bad eb member end: ptr 0x%lx start %llu member offset %lu size %d",
  34                         (unsigned long)ptr, eb->start, member_offset, size);
  35                 return false;
  36         }
  37
  38         return true;
  39 }
  40
  41 /*
  42  * Macro templates that define helpers to read/write extent buffer data of a
  43  * given size, that are also used via ctree.h for access to item members by
  44  * specialized helpers.
  45  *
  46  * Generic helpers:
  47  * - btrfs_set_8 (for 8/16/32/64)
  48  * - btrfs_get_8 (for 8/16/32/64)
  49  *
  50  * Generic helpers with a token (cached address of the most recently accessed
  51  * page):
  52  * - btrfs_set_token_8 (for 8/16/32/64)
  53  * - btrfs_get_token_8 (for 8/16/32/64)
  54  *
  55  * The set/get functions handle data spanning two pages transparently, in case
  56  * metadata block size is larger than page.  Every pointer to metadata items is
  57  * an offset into the extent buffer page array, cast to a specific type.  This
  58  * gives us all the type checking.
  59  *
  60  * The extent buffer pages stored in the array pages do not form a contiguous
  61  * phyusical range, but the API functions assume the linear offset to the range
  62  * from 0 to metadata node size.
  63  */
  64
  65 #define DEFINE_BTRFS_SETGET_BITS(bits)                                  \
  66 u##bits btrfs_get_token_##bits(struct btrfs_map_token *token,           \
  67                                const void *ptr, unsigned long off)      \
  68 {                                                                       \
  69         const unsigned long member_offset = (unsigned long)ptr + off;   \
  70         const unsigned long idx = member_offset >> PAGE_SHIFT;          \
  71         const unsigned long oip = offset_in_page(member_offset);        \
  72         const int size = sizeof(u##bits);                               \
  73         u8 lebytes[sizeof(u##bits)];                                    \
  74         const int part = PAGE_SIZE - oip;                               \
  75                                                                         \
  76         ASSERT(token);                                                  \
  77         ASSERT(token->kaddr);                                           \
  78         ASSERT(check_setget_bounds(token->eb, ptr, off, size));         \
  79         if (token->offset <= member_offset &&                           \
  80             member_offset + size <= token->offset + PAGE_SIZE) {        \
  81                 return get_unaligned_le##bits(token->kaddr + oip);      \
  82         }                                                               \
  83         token->kaddr = page_address(token->eb->pages[idx]);             \
  84         token->offset = idx << PAGE_SHIFT;                              \
  85         if (oip + size <= PAGE_SIZE)                                    \
  86                 return get_unaligned_le##bits(token->kaddr + oip);      \
  87                                                                         \
  88         memcpy(lebytes, token->kaddr + oip, part);                      \
  89         token->kaddr = page_address(token->eb->pages[idx + 1]);         \
  90         token->offset = (idx + 1) << PAGE_SHIFT;                        \
  91         memcpy(lebytes + part, token->kaddr, size - part);              \
  92         return get_unaligned_le##bits(lebytes);                         \
  93 }                                                                       \
  94 u##bits btrfs_get_##bits(const struct extent_buffer *eb,                \
  95                          const void *ptr, unsigned long off)            \
  96 {                                                                       \
  97         const unsigned long member_offset = (unsigned long)ptr + off;   \
  98         const unsigned long oip = offset_in_page(member_offset);        \
  99         const unsigned long idx = member_offset >> PAGE_SHIFT;          \
 100         char *kaddr = page_address(eb->pages[idx]);                     \
 101         const int size = sizeof(u##bits);                               \
 102         const int part = PAGE_SIZE - oip;                               \
 103         u8 lebytes[sizeof(u##bits)];                                    \
 104                                                                         \
 105         ASSERT(check_setget_bounds(eb, ptr, off, size));                \
 106         if (oip + size <= PAGE_SIZE)                                    \
 107                 return get_unaligned_le##bits(kaddr + oip);             \
 108                                                                         \
 109         memcpy(lebytes, kaddr + oip, part);                             \
 110         kaddr = page_address(eb->pages[idx + 1]);                       \
 111         memcpy(lebytes + part, kaddr, size - part);                     \
 112         return get_unaligned_le##bits(lebytes);                         \
 113 }                                                                       \
 114 void btrfs_set_token_##bits(struct btrfs_map_token *token,              \
 115                             const void *ptr, unsigned long off,         \
 116                             u##bits val)                                \
 117 {                                                                       \
 118         const unsigned long member_offset = (unsigned long)ptr + off;   \
 119         const unsigned long idx = member_offset >> PAGE_SHIFT;          \
 120         const unsigned long oip = offset_in_page(member_offset);        \
 121         const int size = sizeof(u##bits);                               \
 122         u8 lebytes[sizeof(u##bits)];                                    \
 123         const int part = PAGE_SIZE - oip;                               \
 124                                                                         \
 125         ASSERT(token);                                                  \
 126         ASSERT(token->kaddr);                                           \
 127         ASSERT(check_setget_bounds(token->eb, ptr, off, size));         \
 128         if (token->offset <= member_offset &&                           \
 129             member_offset + size <= token->offset + PAGE_SIZE) {        \
 130                 put_unaligned_le##bits(val, token->kaddr + oip);        \
 131                 return;                                                 \
 132         }                                                               \
 133         token->kaddr = page_address(token->eb->pages[idx]);             \
 134         token->offset = idx << PAGE_SHIFT;                              \
 135         if (oip + size <= PAGE_SIZE) {                                  \
 136                 put_unaligned_le##bits(val, token->kaddr + oip);        \
 137                 return;                                                 \
 138         }                                                               \
 139         put_unaligned_le##bits(val, lebytes);                           \
 140         memcpy(token->kaddr + oip, lebytes, part);                      \
 141         token->kaddr = page_address(token->eb->pages[idx + 1]);         \
 142         token->offset = (idx + 1) << PAGE_SHIFT;                        \
 143         memcpy(token->kaddr, lebytes + part, size - part);              \
 144 }                                                                       \
 145 void btrfs_set_##bits(const struct extent_buffer *eb, void *ptr,        \
 146                       unsigned long off, u##bits val)                   \
 147 {                                                                       \
 148         const unsigned long member_offset = (unsigned long)ptr + off;   \
 149         const unsigned long oip = offset_in_page(member_offset);        \
 150         const unsigned long idx = member_offset >> PAGE_SHIFT;          \
 151         char *kaddr = page_address(eb->pages[idx]);                     \
 152         const int size = sizeof(u##bits);                               \
 153         const int part = PAGE_SIZE - oip;                               \
 154         u8 lebytes[sizeof(u##bits)];                                    \
 155                                                                         \
 156         ASSERT(check_setget_bounds(eb, ptr, off, size));                \
 157         if (oip + size <= PAGE_SIZE) {                                  \
 158                 put_unaligned_le##bits(val, kaddr + oip);               \
 159                 return;                                                 \
 160         }                                                               \
 161                                                                         \
 162         put_unaligned_le##bits(val, lebytes);                           \
 163         memcpy(kaddr + oip, lebytes, part);                             \
 164         kaddr = page_address(eb->pages[idx + 1]);                       \
 165         memcpy(kaddr, lebytes + part, size - part);                     \
 166 }
 167
 168 DEFINE_BTRFS_SETGET_BITS(8)
 169 DEFINE_BTRFS_SETGET_BITS(16)
 170 DEFINE_BTRFS_SETGET_BITS(32)
 171 DEFINE_BTRFS_SETGET_BITS(64)
 172
 173 void btrfs_node_key(const struct extent_buffer *eb,
 174                     struct btrfs_disk_key *disk_key, int nr)
 175 {
 176         unsigned long ptr = btrfs_node_key_ptr_offset(nr);
 177         read_eb_member(eb, (struct btrfs_key_ptr *)ptr,
 178                        struct btrfs_key_ptr, key, disk_key);
 179 }