a65917156e
The extent_buffers have a very complex interface where we use HIGHMEM for metadata and try to cache a kmap mapping to access the memory. The next commit adds reader/writer locks, and concurrent use of this kmap cache would make it even more complex. This commit drops the ability to use HIGHMEM with extent buffers, and rips out all of the related code. Signed-off-by: Chris Mason <chris.mason@oracle.com>
101 lines
3.6 KiB
C
101 lines
3.6 KiB
C
/*
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* Copyright (C) 2007 Oracle. All rights reserved.
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public
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* License v2 as published by the Free Software Foundation.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* General Public License for more details.
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*
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* You should have received a copy of the GNU General Public
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* License along with this program; if not, write to the
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* Free Software Foundation, Inc., 59 Temple Place - Suite 330,
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* Boston, MA 021110-1307, USA.
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*/
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#include <linux/highmem.h>
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/* this is some deeply nasty code. ctree.h has a different
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* definition for this BTRFS_SETGET_FUNCS macro, behind a #ifndef
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*
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* The end result is that anyone who #includes ctree.h gets a
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* declaration for the btrfs_set_foo functions and btrfs_foo functions
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*
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* This file declares the macros and then #includes ctree.h, which results
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* in cpp creating the function here based on the template below.
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*
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* These setget functions do all the extent_buffer related mapping
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* required to efficiently read and write specific fields in the extent
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* buffers. Every pointer to metadata items in btrfs is really just
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* an unsigned long offset into the extent buffer which has been
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* cast to a specific type. This gives us all the gcc type checking.
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*
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* The extent buffer api is used to do all the kmapping and page
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* spanning work required to get extent buffers in highmem and have
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* a metadata blocksize different from the page size.
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*
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* The macro starts with a simple function prototype declaration so that
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* sparse won't complain about it being static.
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*/
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#define BTRFS_SETGET_FUNCS(name, type, member, bits) \
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u##bits btrfs_##name(struct extent_buffer *eb, type *s); \
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void btrfs_set_##name(struct extent_buffer *eb, type *s, u##bits val); \
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u##bits btrfs_##name(struct extent_buffer *eb, \
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type *s) \
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{ \
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unsigned long part_offset = (unsigned long)s; \
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unsigned long offset = part_offset + offsetof(type, member); \
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type *p; \
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int err; \
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char *kaddr; \
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unsigned long map_start; \
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unsigned long map_len; \
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u##bits res; \
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err = map_private_extent_buffer(eb, offset, \
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sizeof(((type *)0)->member), \
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&kaddr, &map_start, &map_len); \
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if (err) { \
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__le##bits leres; \
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read_eb_member(eb, s, type, member, &leres); \
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return le##bits##_to_cpu(leres); \
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} \
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p = (type *)(kaddr + part_offset - map_start); \
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res = le##bits##_to_cpu(p->member); \
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return res; \
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} \
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void btrfs_set_##name(struct extent_buffer *eb, \
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type *s, u##bits val) \
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{ \
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unsigned long part_offset = (unsigned long)s; \
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unsigned long offset = part_offset + offsetof(type, member); \
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type *p; \
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int err; \
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char *kaddr; \
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unsigned long map_start; \
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unsigned long map_len; \
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err = map_private_extent_buffer(eb, offset, \
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sizeof(((type *)0)->member), \
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&kaddr, &map_start, &map_len); \
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if (err) { \
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__le##bits val2; \
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val2 = cpu_to_le##bits(val); \
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write_eb_member(eb, s, type, member, &val2); \
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return; \
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} \
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p = (type *)(kaddr + part_offset - map_start); \
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p->member = cpu_to_le##bits(val); \
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}
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#include "ctree.h"
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void btrfs_node_key(struct extent_buffer *eb,
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struct btrfs_disk_key *disk_key, int nr)
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{
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unsigned long ptr = btrfs_node_key_ptr_offset(nr);
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read_eb_member(eb, (struct btrfs_key_ptr *)ptr,
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struct btrfs_key_ptr, key, disk_key);
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}
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