make_ext4fs/extent.c

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/*
* Copyright (C) 2010 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#include "ext4_utils.h"
#include "extent.h"
#include <sparse/sparse.h>
#include <inttypes.h>
#include <stdlib.h>
#include <stdio.h>
/* Creates data buffers for the first backing_len bytes of a block allocation
and queues them to be written */
static u8 *extent_create_backing(struct block_allocation *alloc,
u64 backing_len)
{
u8 *data = calloc(backing_len, 1);
if (!data)
critical_error_errno("calloc");
u8 *ptr = data;
for (; alloc != NULL && backing_len > 0; get_next_region(alloc)) {
u32 region_block;
u32 region_len;
u32 len;
get_region(alloc, &region_block, &region_len);
len = min(region_len * info.block_size, backing_len);
sparse_file_add_data(ext4_sparse_file, ptr, len, region_block);
ptr += len;
backing_len -= len;
}
return data;
}
/* Queues each chunk of a file to be written to contiguous data block
regions */
static void extent_create_backing_file(struct block_allocation *alloc,
u64 backing_len, const char *filename)
{
off_t offset = 0;
for (; alloc != NULL && backing_len > 0; get_next_region(alloc)) {
u32 region_block;
u32 region_len;
u32 len;
get_region(alloc, &region_block, &region_len);
len = min(region_len * info.block_size, backing_len);
sparse_file_add_file(ext4_sparse_file, filename, offset, len,
region_block);
offset += len;
backing_len -= len;
}
}
static struct block_allocation *do_inode_allocate_extents(
struct ext4_inode *inode, u64 len)
{
u32 block_len = DIV_ROUND_UP(len, info.block_size);
struct block_allocation *alloc = allocate_blocks(block_len + 1);
u32 extent_block = 0;
u32 file_block = 0;
struct ext4_extent *extent;
u64 blocks;
if (alloc == NULL) {
error("Failed to allocate %d blocks\n", block_len + 1);
return NULL;
}
int allocation_len = block_allocation_num_regions(alloc);
if (allocation_len <= 3) {
reduce_allocation(alloc, 1);
} else {
reserve_oob_blocks(alloc, 1);
extent_block = get_oob_block(alloc, 0);
}
if (!extent_block) {
struct ext4_extent_header *hdr =
(struct ext4_extent_header *)&inode->i_block[0];
hdr->eh_magic = EXT4_EXT_MAGIC;
hdr->eh_entries = allocation_len;
hdr->eh_max = 3;
hdr->eh_generation = 0;
hdr->eh_depth = 0;
extent = (struct ext4_extent *)&inode->i_block[3];
} else {
struct ext4_extent_header *hdr =
(struct ext4_extent_header *)&inode->i_block[0];
hdr->eh_magic = EXT4_EXT_MAGIC;
hdr->eh_entries = 1;
hdr->eh_max = 3;
hdr->eh_generation = 0;
hdr->eh_depth = 1;
struct ext4_extent_idx *idx =
(struct ext4_extent_idx *)&inode->i_block[3];
idx->ei_block = 0;
idx->ei_leaf_lo = extent_block;
idx->ei_leaf_hi = 0;
idx->ei_unused = 0;
u8 *data = calloc(info.block_size, 1);
if (!data)
critical_error_errno("calloc");
sparse_file_add_data(ext4_sparse_file, data, info.block_size,
extent_block);
if (((int)(info.block_size - sizeof(struct ext4_extent_header) /
sizeof(struct ext4_extent))) < allocation_len) {
error("File size %"PRIu64" is too big to fit in a single extent block\n",
len);
return NULL;
}
hdr = (struct ext4_extent_header *)data;
hdr->eh_magic = EXT4_EXT_MAGIC;
hdr->eh_entries = allocation_len;
hdr->eh_max = (info.block_size - sizeof(struct ext4_extent_header)) /
sizeof(struct ext4_extent);
hdr->eh_generation = 0;
hdr->eh_depth = 0;
extent = (struct ext4_extent *)(data +
sizeof(struct ext4_extent_header));
}
for (; !last_region(alloc); extent++, get_next_region(alloc)) {
u32 region_block;
u32 region_len;
get_region(alloc, &region_block, &region_len);
extent->ee_block = file_block;
extent->ee_len = region_len;
extent->ee_start_hi = 0;
extent->ee_start_lo = region_block;
file_block += region_len;
}
if (extent_block)
block_len += 1;
blocks = (u64)block_len * info.block_size / 512;
inode->i_flags |= EXT4_EXTENTS_FL;
inode->i_size_lo = len;
inode->i_size_high = len >> 32;
inode->i_blocks_lo = blocks;
inode->osd2.linux2.l_i_blocks_high = blocks >> 32;
rewind_alloc(alloc);
return alloc;
}
/* Allocates enough blocks to hold len bytes, with backing_len bytes in a data
buffer, and connects them to an inode. Returns a pointer to the data
buffer. */
u8 *inode_allocate_data_extents(struct ext4_inode *inode, u64 len,
u64 backing_len)
{
struct block_allocation *alloc;
u8 *data = NULL;
alloc = do_inode_allocate_extents(inode, len);
if (alloc == NULL) {
error("failed to allocate extents for %"PRIu64" bytes", len);
return NULL;
}
if (backing_len) {
data = extent_create_backing(alloc, backing_len);
if (!data)
error("failed to create backing for %"PRIu64" bytes", backing_len);
}
free_alloc(alloc);
return data;
}
/* Allocates enough blocks to hold len bytes, queues them to be written
from a file, and connects them to an inode. */
struct block_allocation* inode_allocate_file_extents(struct ext4_inode *inode, u64 len,
const char *filename)
{
struct block_allocation *alloc;
alloc = do_inode_allocate_extents(inode, len);
if (alloc == NULL) {
error("failed to allocate extents for %"PRIu64" bytes", len);
return NULL;
}
extent_create_backing_file(alloc, len, filename);
return alloc;
}
/* Allocates enough blocks to hold len bytes and connects them to an inode */
void inode_allocate_extents(struct ext4_inode *inode, u64 len)
{
struct block_allocation *alloc;
alloc = do_inode_allocate_extents(inode, len);
if (alloc == NULL) {
error("failed to allocate extents for %"PRIu64" bytes", len);
return;
}
free_alloc(alloc);
}