extent.c

   1 /*
   2  * Copyright (C) 2010 The Android Open Source Project
   3  *
   4  * Licensed under the Apache License, Version 2.0 (the "License");
   5  * you may not use this file except in compliance with the License.
   6  * You may obtain a copy of the License at
   7  *
   8  *      http://www.apache.org/licenses/LICENSE-2.0
   9  *
  10  * Unless required by applicable law or agreed to in writing, software
  11  * distributed under the License is distributed on an "AS IS" BASIS,
  12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  13  * See the License for the specific language governing permissions and
  14  * limitations under the License.
  15  */
  16
  17 #include "ext4_utils.h"
  18 #include "extent.h"
  19
  20 #include <sparse/sparse.h>
  21
  22 #include <inttypes.h>
  23 #include <stdlib.h>
  24 #include <stdio.h>
  25
  26
  27 /* Creates data buffers for the first backing_len bytes of a block allocation
  28    and queues them to be written */
  29 static u8 *extent_create_backing(struct block_allocation *alloc,
  30         u64 backing_len)
  31 {
  32         u8 *data = calloc(backing_len, 1);
  33         if (!data)
  34                 critical_error_errno("calloc");
  35
  36         u8 *ptr = data;
  37         for (; alloc != NULL && backing_len > 0; get_next_region(alloc)) {
  38                 u32 region_block;
  39                 u32 region_len;
  40                 u32 len;
  41                 get_region(alloc, &region_block, &region_len);
  42
  43                 len = min(region_len * info.block_size, backing_len);
  44
  45                 sparse_file_add_data(ext4_sparse_file, ptr, len, region_block);
  46                 ptr += len;
  47                 backing_len -= len;
  48         }
  49
  50         return data;
  51 }
  52
  53 /* Queues each chunk of a file to be written to contiguous data block
  54    regions */
  55 static void extent_create_backing_file(struct block_allocation *alloc,
  56         u64 backing_len, const char *filename)
  57 {
  58         off_t offset = 0;
  59         for (; alloc != NULL && backing_len > 0; get_next_region(alloc)) {
  60                 u32 region_block;
  61                 u32 region_len;
  62                 u32 len;
  63                 get_region(alloc, &region_block, &region_len);
  64
  65                 len = min(region_len * info.block_size, backing_len);
  66
  67                 sparse_file_add_file(ext4_sparse_file, filename, offset, len,
  68                                 region_block);
  69                 offset += len;
  70                 backing_len -= len;
  71         }
  72 }
  73
  74 static struct block_allocation *do_inode_allocate_extents(
  75         struct ext4_inode *inode, u64 len)
  76 {
  77         u32 block_len = DIV_ROUND_UP(len, info.block_size);
  78         struct block_allocation *alloc = allocate_blocks(block_len + 1);
  79         u32 extent_block = 0;
  80         u32 file_block = 0;
  81         struct ext4_extent *extent;
  82         u64 blocks;
  83
  84         if (alloc == NULL) {
  85                 error("Failed to allocate %d blocks\n", block_len + 1);
  86                 return NULL;
  87         }
  88
  89         int allocation_len = block_allocation_num_regions(alloc);
  90         if (allocation_len <= 3) {
  91                 reduce_allocation(alloc, 1);
  92         } else {
  93                 reserve_oob_blocks(alloc, 1);
  94                 extent_block = get_oob_block(alloc, 0);
  95         }
  96
  97         if (!extent_block) {
  98                 struct ext4_extent_header *hdr =
  99                         (struct ext4_extent_header *)&inode->i_block[0];
 100                 hdr->eh_magic = EXT4_EXT_MAGIC;
 101                 hdr->eh_entries = allocation_len;
 102                 hdr->eh_max = 3;
 103                 hdr->eh_generation = 0;
 104                 hdr->eh_depth = 0;
 105
 106                 extent = (struct ext4_extent *)&inode->i_block[3];
 107         } else {
 108                 struct ext4_extent_header *hdr =
 109                         (struct ext4_extent_header *)&inode->i_block[0];
 110                 hdr->eh_magic = EXT4_EXT_MAGIC;
 111                 hdr->eh_entries = 1;
 112                 hdr->eh_max = 3;
 113                 hdr->eh_generation = 0;
 114                 hdr->eh_depth = 1;
 115
 116                 struct ext4_extent_idx *idx =
 117                         (struct ext4_extent_idx *)&inode->i_block[3];
 118                 idx->ei_block = 0;
 119                 idx->ei_leaf_lo = extent_block;
 120                 idx->ei_leaf_hi = 0;
 121                 idx->ei_unused = 0;
 122
 123                 u8 *data = calloc(info.block_size, 1);
 124                 if (!data)
 125                         critical_error_errno("calloc");
 126
 127                 sparse_file_add_data(ext4_sparse_file, data, info.block_size,
 128                                 extent_block);
 129
 130                 if (((int)(info.block_size - sizeof(struct ext4_extent_header) /
 131                                 sizeof(struct ext4_extent))) < allocation_len) {
 132                         error("File size %"PRIu64" is too big to fit in a single extent block\n",
 133                                         len);
 134                         return NULL;
 135                 }
 136
 137                 hdr = (struct ext4_extent_header *)data;
 138                 hdr->eh_magic = EXT4_EXT_MAGIC;
 139                 hdr->eh_entries = allocation_len;
 140                 hdr->eh_max = (info.block_size - sizeof(struct ext4_extent_header)) /
 141                         sizeof(struct ext4_extent);
 142                 hdr->eh_generation = 0;
 143                 hdr->eh_depth = 0;
 144
 145                 extent = (struct ext4_extent *)(data +
 146                         sizeof(struct ext4_extent_header));
 147         }
 148
 149         for (; !last_region(alloc); extent++, get_next_region(alloc)) {
 150                 u32 region_block;
 151                 u32 region_len;
 152
 153                 get_region(alloc, &region_block, &region_len);
 154                 extent->ee_block = file_block;
 155                 extent->ee_len = region_len;
 156                 extent->ee_start_hi = 0;
 157                 extent->ee_start_lo = region_block;
 158                 file_block += region_len;
 159         }
 160
 161         if (extent_block)
 162                 block_len += 1;
 163
 164         blocks = (u64)block_len * info.block_size / 512;
 165
 166         inode->i_flags |= EXT4_EXTENTS_FL;
 167         inode->i_size_lo = len;
 168         inode->i_size_high = len >> 32;
 169         inode->i_blocks_lo = blocks;
 170         inode->osd2.linux2.l_i_blocks_high = blocks >> 32;
 171
 172         rewind_alloc(alloc);
 173
 174         return alloc;
 175 }
 176
 177 /* Allocates enough blocks to hold len bytes, with backing_len bytes in a data
 178    buffer, and connects them to an inode.  Returns a pointer to the data
 179    buffer. */
 180 u8 *inode_allocate_data_extents(struct ext4_inode *inode, u64 len,
 181         u64 backing_len)
 182 {
 183         struct block_allocation *alloc;
 184         u8 *data = NULL;
 185
 186         alloc = do_inode_allocate_extents(inode, len);
 187         if (alloc == NULL) {
 188                 error("failed to allocate extents for %"PRIu64" bytes", len);
 189                 return NULL;
 190         }
 191
 192         if (backing_len) {
 193                 data = extent_create_backing(alloc, backing_len);
 194                 if (!data)
 195                         error("failed to create backing for %"PRIu64" bytes", backing_len);
 196         }
 197
 198         free_alloc(alloc);
 199
 200         return data;
 201 }
 202
 203 /* Allocates enough blocks to hold len bytes, queues them to be written
 204    from a file, and connects them to an inode. */
 205 struct block_allocation* inode_allocate_file_extents(struct ext4_inode *inode, u64 len,
 206         const char *filename)
 207 {
 208         struct block_allocation *alloc;
 209
 210         alloc = do_inode_allocate_extents(inode, len);
 211         if (alloc == NULL) {
 212                 error("failed to allocate extents for %"PRIu64" bytes", len);
 213                 return NULL;
 214         }
 215
 216         extent_create_backing_file(alloc, len, filename);
 217         return alloc;
 218 }
 219
 220 /* Allocates enough blocks to hold len bytes and connects them to an inode */
 221 void inode_allocate_extents(struct ext4_inode *inode, u64 len)
 222 {
 223         struct block_allocation *alloc;
 224
 225         alloc = do_inode_allocate_extents(inode, len);
 226         if (alloc == NULL) {
 227                 error("failed to allocate extents for %"PRIu64" bytes", len);
 228                 return;
 229         }
 230
 231         free_alloc(alloc);
 232 }