130 строки
3.9 KiB
C
130 строки
3.9 KiB
C
// SPDX-License-Identifier: GPL-2.0
|
|
/*
|
|
* Copyright (C) 2007 Oracle. All rights reserved.
|
|
*/
|
|
|
|
#include <asm/unaligned.h>
|
|
|
|
#include "ctree.h"
|
|
|
|
static inline u8 get_unaligned_le8(const void *p)
|
|
{
|
|
return *(u8 *)p;
|
|
}
|
|
|
|
static inline void put_unaligned_le8(u8 val, void *p)
|
|
{
|
|
*(u8 *)p = val;
|
|
}
|
|
|
|
/*
|
|
* this is some deeply nasty code.
|
|
*
|
|
* The end result is that anyone who #includes ctree.h gets a
|
|
* declaration for the btrfs_set_foo functions and btrfs_foo functions,
|
|
* which are wrappers of btrfs_set_token_#bits functions and
|
|
* btrfs_get_token_#bits functions, which are defined in this file.
|
|
*
|
|
* These setget functions do all the extent_buffer related mapping
|
|
* required to efficiently read and write specific fields in the extent
|
|
* buffers. Every pointer to metadata items in btrfs is really just
|
|
* an unsigned long offset into the extent buffer which has been
|
|
* cast to a specific type. This gives us all the gcc type checking.
|
|
*
|
|
* The extent buffer api is used to do the page spanning work required to
|
|
* have a metadata blocksize different from the page size.
|
|
*/
|
|
|
|
#define DEFINE_BTRFS_SETGET_BITS(bits) \
|
|
u##bits btrfs_get_token_##bits(const struct extent_buffer *eb, \
|
|
const void *ptr, unsigned long off, \
|
|
struct btrfs_map_token *token) \
|
|
{ \
|
|
unsigned long part_offset = (unsigned long)ptr; \
|
|
unsigned long offset = part_offset + off; \
|
|
void *p; \
|
|
int err; \
|
|
char *kaddr; \
|
|
unsigned long map_start; \
|
|
unsigned long map_len; \
|
|
int size = sizeof(u##bits); \
|
|
u##bits res; \
|
|
\
|
|
if (token && token->kaddr && token->offset <= offset && \
|
|
token->eb == eb && \
|
|
(token->offset + PAGE_SIZE >= offset + size)) { \
|
|
kaddr = token->kaddr; \
|
|
p = kaddr + part_offset - token->offset; \
|
|
res = get_unaligned_le##bits(p + off); \
|
|
return res; \
|
|
} \
|
|
err = map_private_extent_buffer(eb, offset, size, \
|
|
&kaddr, &map_start, &map_len); \
|
|
if (err) { \
|
|
__le##bits leres; \
|
|
\
|
|
read_extent_buffer(eb, &leres, offset, size); \
|
|
return le##bits##_to_cpu(leres); \
|
|
} \
|
|
p = kaddr + part_offset - map_start; \
|
|
res = get_unaligned_le##bits(p + off); \
|
|
if (token) { \
|
|
token->kaddr = kaddr; \
|
|
token->offset = map_start; \
|
|
token->eb = eb; \
|
|
} \
|
|
return res; \
|
|
} \
|
|
void btrfs_set_token_##bits(struct extent_buffer *eb, \
|
|
const void *ptr, unsigned long off, \
|
|
u##bits val, \
|
|
struct btrfs_map_token *token) \
|
|
{ \
|
|
unsigned long part_offset = (unsigned long)ptr; \
|
|
unsigned long offset = part_offset + off; \
|
|
void *p; \
|
|
int err; \
|
|
char *kaddr; \
|
|
unsigned long map_start; \
|
|
unsigned long map_len; \
|
|
int size = sizeof(u##bits); \
|
|
\
|
|
if (token && token->kaddr && token->offset <= offset && \
|
|
token->eb == eb && \
|
|
(token->offset + PAGE_SIZE >= offset + size)) { \
|
|
kaddr = token->kaddr; \
|
|
p = kaddr + part_offset - token->offset; \
|
|
put_unaligned_le##bits(val, p + off); \
|
|
return; \
|
|
} \
|
|
err = map_private_extent_buffer(eb, offset, size, \
|
|
&kaddr, &map_start, &map_len); \
|
|
if (err) { \
|
|
__le##bits val2; \
|
|
\
|
|
val2 = cpu_to_le##bits(val); \
|
|
write_extent_buffer(eb, &val2, offset, size); \
|
|
return; \
|
|
} \
|
|
p = kaddr + part_offset - map_start; \
|
|
put_unaligned_le##bits(val, p + off); \
|
|
if (token) { \
|
|
token->kaddr = kaddr; \
|
|
token->offset = map_start; \
|
|
token->eb = eb; \
|
|
} \
|
|
}
|
|
|
|
DEFINE_BTRFS_SETGET_BITS(8)
|
|
DEFINE_BTRFS_SETGET_BITS(16)
|
|
DEFINE_BTRFS_SETGET_BITS(32)
|
|
DEFINE_BTRFS_SETGET_BITS(64)
|
|
|
|
void btrfs_node_key(const struct extent_buffer *eb,
|
|
struct btrfs_disk_key *disk_key, int nr)
|
|
{
|
|
unsigned long ptr = btrfs_node_key_ptr_offset(nr);
|
|
read_eb_member(eb, (struct btrfs_key_ptr *)ptr,
|
|
struct btrfs_key_ptr, key, disk_key);
|
|
}
|