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Optimise echfs file loading by caching allocation map

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This commit is contained in:
mintsuki 2020-04-19 00:58:33 +02:00
parent 6a9c5f3c35
commit 9358a4febc
2 changed files with 20 additions and 16 deletions
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35
src/fs/echfs.c
View File

@ -17,21 +17,7 @@ struct echfs_identity_table {
#define FILE_TYPE 0
static int read_block(struct echfs_file_handle *file, void *buf, uint64_t block, uint64_t offset, uint64_t count) {
// Load the file.
uint64_t block_val = file->dir_entry.payload;
for (uint64_t i = 0; i < block; i++) {
if (block_val == END_OF_CHAIN)
return -1;
// Read the next block.
read_partition(file->disk, &file->part, &block_val, file->alloc_table_offset + block_val * sizeof(uint64_t),
sizeof(uint64_t));
}
if (block_val == END_OF_CHAIN)
return -1;
return read_partition(file->disk, &file->part, buf, (block_val * file->block_size) + offset, count);
return read_partition(file->disk, &file->part, buf, (file->alloc_map[block] * file->block_size) + offset, count);
}
int echfs_read(struct echfs_file_handle *file, void *buf, uint64_t loc, uint64_t count) {
@ -95,10 +81,27 @@ int echfs_open(struct echfs_file_handle *ret, int disk, int partition, const cha
if (!strcmp(filename, ret->dir_entry.name) &&
ret->dir_entry.parent_id == ROOT_DIR_ID &&
ret->dir_entry.type == FILE_TYPE) {
return 0;
goto found;
}
}
print("echfs: file %s not found\n", filename);
return -1;
found:;
// Load the allocation map.
uint64_t file_block_count = DIV_ROUNDUP(ret->dir_entry.size, ret->block_size);
ret->alloc_map = balloc(file_block_count * sizeof(uint64_t));
ret->alloc_map[0] = ret->dir_entry.payload;
for (uint64_t i = 1; i < file_block_count; i++) {
// Read the next block.
read_partition(ret->disk, &ret->part,
&ret->alloc_map[i],
ret->alloc_table_offset + ret->alloc_map[i-1] * sizeof(uint64_t),
sizeof(uint64_t));
}
return 0;
}

1
src/fs/echfs.h
View File

@ -27,6 +27,7 @@ struct echfs_file_handle {
uint64_t alloc_table_size;
uint64_t alloc_table_offset;
uint64_t dir_offset;
uint64_t *alloc_map;
struct echfs_dir_entry dir_entry;
};