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|
/*
* linux/fs/hfs/extent.c
*
* Copyright (C) 1995-1997 Paul H. Hargrove
* (C) 2003 Ardis Technologies <roman@ardistech.com>
* This file may be distributed under the terms of the GNU General Public License.
*
* This file contains the functions related to the extents B-tree.
*/
#include <linux/pagemap.h>
#include "hfs_fs.h"
#include "btree.h"
/*================ File-local functions ================*/
/*
* build_key
*/
static void hfs_ext_build_key(hfs_btree_key *key, u32 cnid, u16 block, u8 type)
{
key->key_len = 7;
key->ext.FkType = type;
key->ext.FNum = cpu_to_be32(cnid);
key->ext.FABN = cpu_to_be16(block);
}
/*
* hfs_ext_compare()
*
* Description:
* This is the comparison function used for the extents B-tree. In
* comparing extent B-tree entries, the file id is the most
* significant field (compared as unsigned ints); the fork type is
* the second most significant field (compared as unsigned chars);
* and the allocation block number field is the least significant
* (compared as unsigned ints).
* Input Variable(s):
* struct hfs_ext_key *key1: pointer to the first key to compare
* struct hfs_ext_key *key2: pointer to the second key to compare
* Output Variable(s):
* NONE
* Returns:
* int: negative if key1<key2, positive if key1>key2, and 0 if key1==key2
* Preconditions:
* key1 and key2 point to "valid" (struct hfs_ext_key)s.
* Postconditions:
* This function has no side-effects */
int hfs_ext_keycmp(const btree_key *key1, const btree_key *key2)
{
__be32 fnum1, fnum2;
__be16 block1, block2;
fnum1 = key1->ext.FNum;
fnum2 = key2->ext.FNum;
if (fnum1 != fnum2)
return be32_to_cpu(fnum1) < be32_to_cpu(fnum2) ? -1 : 1;
if (key1->ext.FkType != key2->ext.FkType)
return key1->ext.FkType < key2->ext.FkType ? -1 : 1;
block1 = key1->ext.FABN;
block2 = key2->ext.FABN;
if (block1 == block2)
return 0;
return be16_to_cpu(block1) < be16_to_cpu(block2) ? -1 : 1;
}
/*
* hfs_ext_find_block
*
* Find a block within an extent record
*/
static u16 hfs_ext_find_block(struct hfs_extent *ext, u16 off)
{
int i;
u16 count;
for (i = 0; i < 3; ext++, i++) {
count = be16_to_cpu(ext->count);
if (off < count)
return be16_to_cpu(ext->block) + off;
off -= count;
}
/* panic? */
return 0;
}
static int hfs_ext_block_count(struct hfs_extent *ext)
{
int i;
u16 count = 0;
for (i = 0; i < 3; ext++, i++)
count += be16_to_cpu(ext->count);
return count;
}
static u16 hfs_ext_lastblock(struct hfs_extent *ext)
{
int i;
ext += 2;
for (i = 0; i < 2; ext--, i++)
if (ext->count)
break;
return be16_to_cpu(ext->block) + be16_to_cpu(ext->count);
}
static int __hfs_ext_write_extent(struct inode *inode, struct hfs_find_data *fd)
{
int res;
hfs_ext_build_key(fd->search_key, inode->i_ino, HFS_I(inode)->cached_start,
HFS_IS_RSRC(inode) ? HFS_FK_RSRC : HFS_FK_DATA);
res = hfs_brec_find(fd);
if (HFS_I(inode)->flags & HFS_FLG_EXT_NEW) {
if (res != -ENOENT)
return res;
hfs_brec_insert(fd, HFS_I(inode)->cached_extents, sizeof(hfs_extent_rec));
HFS_I(inode)->flags &= ~(HFS_FLG_EXT_DIRTY|HFS_FLG_EXT_NEW);
} else {
if (res)
return res;
hfs_bnode_write(fd->bnode, HFS_I(inode)->cached_extents, fd->entryoffset, fd->entrylength);
HFS_I(inode)->flags &= ~HFS_FLG_EXT_DIRTY;
}
return 0;
}
int hfs_ext_write_extent(struct inode *inode)
{
struct hfs_find_data fd;
int res = 0;
if (HFS_I(inode)->flags & HFS_FLG_EXT_DIRTY) {
res = hfs_find_init(HFS_SB(inode->i_sb)->ext_tree, &fd);
if (res)
return res;
res = __hfs_ext_write_extent(inode, &fd);
hfs_find_exit(&fd);
}
return res;
}
static inline int __hfs_ext_read_extent(struct hfs_find_data *fd, struct hfs_extent *extent,
u32 cnid, u32 block, u8 type)
{
int res;
hfs_ext_build_key(fd->search_key, cnid, block, type);
fd->key->ext.FNum = 0;
res = hfs_brec_find(fd);
if (res && res != -ENOENT)
return res;
if (fd->key->ext.FNum != fd->search_key->ext.FNum ||
fd->key->ext.FkType != fd->search_key->ext.FkType)
return -ENOENT;
if (fd->entrylength != sizeof(hfs_extent_rec))
return -EIO;
hfs_bnode_read(fd->bnode, extent, fd->entryoffset, sizeof(hfs_extent_rec));
return 0;
}
static inline int __hfs_ext_cache_extent(struct hfs_find_data *fd, struct inode *inode, u32 block)
{
int res;
if (HFS_I(inode)->flags & HFS_FLG_EXT_DIRTY) {
res = __hfs_ext_write_extent(inode, fd);
if (res)
return res;
}
res = __hfs_ext_read_extent(fd, HFS_I(inode)->cached_extents, inode->i_ino,
block, HFS_IS_RSRC(inode) ? HFS_FK_RSRC : HFS_FK_DATA);
if (!res) {
HFS_I(inode)->cached_start = be16_to_cpu(fd->key->ext.FABN);
HFS_I(inode)->cached_blocks = hfs_ext_block_count(HFS_I(inode)->cached_extents);
} else {
HFS_I(inode)->cached_start = HFS_I(inode)->cached_blocks = 0;
HFS_I(inode)->flags &= ~(HFS_FLG_EXT_DIRTY|HFS_FLG_EXT_NEW);
}
return res;
}
static int hfs_ext_read_extent(struct inode *inode, u16 block)
{
struct hfs_find_data fd;
int res;
if (block >= HFS_I(inode)->cached_start &&
block < HFS_I(inode)->cached_start + HFS_I(inode)->cached_blocks)
return 0;
res = hfs_find_init(HFS_SB(inode->i_sb)->ext_tree, &fd);
if (!res) {
res = __hfs_ext_cache_extent(&fd, inode, block);
hfs_find_exit(&fd);
}
return res;
}
static void hfs_dump_extent(struct hfs_extent *
|