diff options
Diffstat (limited to 'fs/btrfs/struct-funcs.c')
| -rw-r--r-- | fs/btrfs/struct-funcs.c | 132 |
1 files changed, 132 insertions, 0 deletions
diff --git a/fs/btrfs/struct-funcs.c b/fs/btrfs/struct-funcs.c new file mode 100644 index 000000000000..cdedbe144d45 --- /dev/null +++ b/fs/btrfs/struct-funcs.c @@ -0,0 +1,132 @@ +/* + * 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); +} |
