/*
* Copyright (C) 2007 Oracle. All rights reserved.
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public
* License v2 as published by the Free Software Foundation.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* General Public License for more details.
*
* You should have received a copy of the GNU General Public
* License along with this program; if not, write to the
* Free Software Foundation, Inc., 59 Temple Place - Suite 330,
* Boston, MA 021110-1307, USA.
*/
#include <linux/highmem.h>
/* this is some deeply nasty code. ctree.h has a different
* definition for this BTRFS_SETGET_FUNCS macro, behind a #ifndef
*
* The end result is that anyone who #includes ctree.h gets a
* declaration for the btrfs_set_foo functions and btrfs_foo functions
*
* This file declares the macros and then #includes ctree.h, which results
* in cpp creating the function here based on the template below.
*
* 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 all the kmapping and page
* spanning work required to get extent buffers in highmem and have
* a metadata blocksize different from the page size.
*/
#define BTRFS_SETGET_FUNCS(name, type, member, bits) \
u##bits btrfs_##name(struct extent_buffer *eb, \
type *s) \
{ \
unsigned long part_offset = (unsigned long)s; \
unsigned long offset = part_offset + offsetof(type, member); \
type *p; \
/* ugly, but we want the fast path here */ \
if (eb->map_token && offset >= eb->map_start && \
offset + sizeof(((type *)0)->member) <= eb->map_start + \
eb->map_len) { \
p = (type *)(eb->kaddr + part_offset - eb->map_start); \
return le##bits##_to_cpu(p->member); \
} \
{ \
int err; \
char *map_token; \
char *kaddr; \
int unmap_on_exit = (eb->map_token == NULL); \
unsigned long map_start; \
unsigned long map_len; \
__le##bits res; \
err = map_extent_buffer(eb, offset, \
sizeof(((type *)0)->member), \
&map_token, &kaddr, \
&map_start, &map_len, KM_USER1); \
if (err) { \
read_eb_member(eb, s, type, member, &res); \
return le##bits##_to_cpu(res); \
} \
p = (type *)(kaddr + part_offset - map_start); \
res = le##bits##_to_cpu(p->member); \
if (unmap_on_exit) \
unmap_extent_buffer(eb, map_token, KM_USER1); \
return res; \
} \
} \
void btrfs_set_##name(struct extent_buffer *eb, \
type *s, u##bits val) \
{ \
unsigned long part_offset = (unsigned long)s; \
unsigned long offset = part_offset + offsetof(type, member); \
type *p; \
/* ugly, but we want the fast path here */ \
if (eb->map_token && offset >= eb->map_start && \
offset + sizeof(((type *)0)->member) <= eb->map_start + \
eb->map_len) { \
p = (type *)(eb->kaddr + part_offset - eb->map_start); \
p->member = cpu_to_le##bits(val); \
return; \
} \
{ \
int err; \
char *map_token; \
char *kaddr; \
int unmap_on_exit = (eb->map_token == NULL); \
unsigned long map_start; \
unsigned long map_len; \
err = map_extent_buffer(eb, offset, \
sizeof(((type *)0)->member), \
&map_token, &kaddr, \
&map_start, &map_len, KM_USER1); \
if (err) { \
val = cpu_to_le##bits(val); \
write_eb_member(eb, s, type, member, &val); \
return; \
} \
p = (type *)(kaddr + part_offset - map_start); \
p->member = cpu_to_le##bits(val); \
if (unmap_on_exit) \
unmap_extent_buffer(eb, map_token, KM_USER1); \
} \
}
#include "ctree.h"
void btrfs_node_key(struct extent_buffer *eb,
struct btrfs_disk_key *disk_key, int nr)
{
unsigned long ptr = btrfs_node_key_ptr_offset(nr);
if (eb->map_token && ptr >= eb->map_start &&
ptr + sizeof(*disk_key) <= eb->map_start + eb->map_len) {
memcpy(disk_key, eb->kaddr + ptr - eb->map_start,
sizeof(*disk_key));
return;
} else if (eb->map_token) {
unmap_extent_buffer(eb, eb->map_token, KM_USER1);
eb->map_token = NULL;
}
read_eb_member(eb, (struct btrfs_key_ptr *)ptr,
struct btrfs_key_ptr, key, disk_key);
}
