Simplified distributed block storage with strong consistency, like in Ceph
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#include "blockstore_impl.h"
static uint32_t is_power_of_two(uint64_t value)
{
uint32_t l = 0;
while (value > 1)
{
if (value & 1)
{
return 64;
}
value = value >> 1;
l++;
}
return l;
}
void blockstore_impl_t::parse_config(blockstore_config_t & config)
{
// Parse
if (config["readonly"] == "true" || config["readonly"] == "1" || config["readonly"] == "yes")
{
readonly = true;
}
if (config["disable_data_fsync"] == "true" || config["disable_data_fsync"] == "1" || config["disable_data_fsync"] == "yes")
{
disable_data_fsync = true;
}
if (config["disable_meta_fsync"] == "true" || config["disable_meta_fsync"] == "1" || config["disable_meta_fsync"] == "yes")
{
disable_meta_fsync = true;
}
if (config["disable_journal_fsync"] == "true" || config["disable_journal_fsync"] == "1" || config["disable_journal_fsync"] == "yes")
{
disable_journal_fsync = true;
}
metadata_buf_size = strtoull(config["meta_buf_size"].c_str(), NULL, 10);
cfg_journal_size = strtoull(config["journal_size"].c_str(), NULL, 10);
data_device = config["data_device"];
data_offset = strtoull(config["data_offset"].c_str(), NULL, 10);
meta_device = config["meta_device"];
meta_offset = strtoull(config["meta_offset"].c_str(), NULL, 10);
block_size = strtoull(config["block_size"].c_str(), NULL, 10);
inmemory_meta = config["inmemory_metadata"] != "false";
journal_device = config["journal_device"];
journal.offset = strtoull(config["journal_offset"].c_str(), NULL, 10);
journal.sector_count = strtoull(config["journal_sector_buffer_count"].c_str(), NULL, 10);
journal.inmemory = config["inmemory_journal"] != "false";
disk_alignment = strtoull(config["disk_alignment"].c_str(), NULL, 10);
journal_block_size = strtoull(config["journal_block_size"].c_str(), NULL, 10);
meta_block_size = strtoull(config["meta_block_size"].c_str(), NULL, 10);
bitmap_granularity = strtoull(config["bitmap_granularity"].c_str(), NULL, 10);
flusher_count = strtoull(config["flusher_count"].c_str(), NULL, 10);
// Validate
if (!block_size)
{
block_size = (1 << DEFAULT_ORDER);
}
if ((block_order = is_power_of_two(block_size)) >= 64 || block_size < MIN_BLOCK_SIZE || block_size >= MAX_BLOCK_SIZE)
{
throw std::runtime_error("Bad block size");
}
if (!flusher_count)
{
flusher_count = 32;
}
if (!disk_alignment)
{
disk_alignment = 512;
}
else if (disk_alignment % MEM_ALIGNMENT)
{
throw std::runtime_error("disk_alingment must be a multiple of "+std::to_string(MEM_ALIGNMENT));
}
if (!journal_block_size)
{
journal_block_size = 512;
}
else if (journal_block_size % MEM_ALIGNMENT)
{
throw std::runtime_error("journal_block_size must be a multiple of "+std::to_string(MEM_ALIGNMENT));
}
if (!meta_block_size)
{
meta_block_size = 512;
}
else if (meta_block_size % MEM_ALIGNMENT)
{
throw std::runtime_error("meta_block_size must be a multiple of "+std::to_string(MEM_ALIGNMENT));
}
if (data_offset % disk_alignment)
{
throw std::runtime_error("data_offset must be a multiple of disk_alignment = "+std::to_string(disk_alignment));
}
if (!bitmap_granularity)
{
bitmap_granularity = 4096;
}
else if (bitmap_granularity % disk_alignment)
{
throw std::runtime_error("Sparse write tracking granularity must be a multiple of disk_alignment = "+std::to_string(disk_alignment));
}
if (block_size % bitmap_granularity)
{
throw std::runtime_error("Block size must be a multiple of sparse write tracking granularity");
}
if (journal_device == meta_device || meta_device == "" && journal_device == data_device)
{
journal_device = "";
}
if (meta_device == data_device)
{
meta_device = "";
}
if (meta_offset % meta_block_size)
{
throw std::runtime_error("meta_offset must be a multiple of meta_block_size = "+std::to_string(meta_block_size));
}
if (journal.offset % journal_block_size)
{
throw std::runtime_error("journal_offset must be a multiple of journal_block_size = "+std::to_string(journal_block_size));
}
if (journal.sector_count < 2)
{
journal.sector_count = 32;
}
if (metadata_buf_size < 65536)
{
metadata_buf_size = 4*1024*1024;
}
// init some fields
clean_entry_bitmap_size = block_size / bitmap_granularity / 8;
clean_entry_size = sizeof(clean_disk_entry) + clean_entry_bitmap_size;
journal.block_size = journal_block_size;
journal.next_free = journal_block_size;
journal.used_start = journal_block_size;
// no free space because sector is initially unmapped
journal.in_sector_pos = journal_block_size;
}
void blockstore_impl_t::calc_lengths()
{
// data
data_len = data_size - data_offset;
if (data_fd == meta_fd && data_offset < meta_offset)
{
data_len = meta_offset - data_offset;
}
if (data_fd == journal.fd && data_offset < journal.offset)
{
data_len = data_len < journal.offset-data_offset
? data_len : journal.offset-data_offset;
}
// meta
meta_area = (meta_fd == data_fd ? data_size : meta_size) - meta_offset;
if (meta_fd == data_fd && meta_offset <= data_offset)
{
meta_area = data_offset - meta_offset;
}
if (meta_fd == journal.fd && meta_offset <= journal.offset)
{
meta_area = meta_area < journal.offset-meta_offset
? meta_area : journal.offset-meta_offset;
}
// journal
journal.len = (journal.fd == data_fd ? data_size : (journal.fd == meta_fd ? meta_size : journal.device_size)) - journal.offset;
if (journal.fd == data_fd && journal.offset <= data_offset)
{
journal.len = data_offset - journal.offset;
}
if (journal.fd == meta_fd && journal.offset <= meta_offset)
{
journal.len = journal.len < meta_offset-journal.offset
? journal.len : meta_offset-journal.offset;
}
// required metadata size
block_count = data_len / block_size;
meta_len = ((block_count - 1 + meta_block_size / clean_entry_size) / (meta_block_size / clean_entry_size)) * meta_block_size;
if (meta_area < meta_len)
{
throw std::runtime_error("Metadata area is too small, need at least "+std::to_string(meta_len)+" bytes");
}
if (inmemory_meta)
{
metadata_buffer = memalign(MEM_ALIGNMENT, meta_len);
if (!metadata_buffer)
throw std::runtime_error("Failed to allocate memory for the metadata");
}
else if (clean_entry_bitmap_size)
{
clean_bitmap = (uint8_t*)malloc(block_count * clean_entry_bitmap_size);
if (!clean_bitmap)
throw std::runtime_error("Failed to allocate memory for the metadata sparse write bitmap");
}
// requested journal size
if (cfg_journal_size > journal.len)
{
throw std::runtime_error("Requested journal_size is too large");
}
else if (cfg_journal_size > 0)
{
journal.len = cfg_journal_size;
}
if (journal.len < MIN_JOURNAL_SIZE)
{
throw std::runtime_error("Journal is too small, need at least "+std::to_string(MIN_JOURNAL_SIZE)+" bytes");
}
if (journal.inmemory)
{
journal.buffer = memalign(MEM_ALIGNMENT, journal.len);
if (!journal.buffer)
throw std::runtime_error("Failed to allocate memory for journal");
}
}
void check_size(int fd, uint64_t *size, std::string name)
{
int sectsize;
struct stat st;
if (fstat(fd, &st) < 0)
{
throw std::runtime_error("Failed to stat "+name);
}
if (S_ISREG(st.st_mode))
{
*size = st.st_size;
}
else if (S_ISBLK(st.st_mode))
{
if (ioctl(fd, BLKSSZGET, &sectsize) < 0 ||
ioctl(fd, BLKGETSIZE64, size) < 0 ||
sectsize != 512)
{
throw std::runtime_error(name+" sector is not equal to 512 bytes");
}
}
else
{
throw std::runtime_error(name+" is neither a file nor a block device");
}
}
void blockstore_impl_t::open_data()
{
data_fd = open(data_device.c_str(), O_DIRECT|O_RDWR);
if (data_fd == -1)
{
throw std::runtime_error("Failed to open data device");
}
check_size(data_fd, &data_size, "data device");
if (data_offset >= data_size)
{
throw std::runtime_error("data_offset exceeds device size = "+std::to_string(data_size));
}
}
void blockstore_impl_t::open_meta()
{
if (meta_device != "")
{
meta_offset = 0;
meta_fd = open(meta_device.c_str(), O_DIRECT|O_RDWR);
if (meta_fd == -1)
{
throw std::runtime_error("Failed to open metadata device");
}
check_size(meta_fd, &meta_size, "metadata device");
if (meta_offset >= meta_size)
{
throw std::runtime_error("meta_offset exceeds device size = "+std::to_string(meta_size));
}
}
else
{
meta_fd = data_fd;
disable_meta_fsync = disable_data_fsync;
meta_size = 0;
if (meta_offset >= data_size)
{
throw std::runtime_error("meta_offset exceeds device size = "+std::to_string(data_size));
}
}
}
void blockstore_impl_t::open_journal()
{
if (journal_device != "")
{
journal.fd = open(journal_device.c_str(), O_DIRECT|O_RDWR);
if (journal.fd == -1)
{
throw std::runtime_error("Failed to open journal device");
}
check_size(journal.fd, &journal.device_size, "metadata device");
}
else
{
journal.fd = meta_fd;
disable_journal_fsync = disable_meta_fsync;
journal.device_size = 0;
if (journal.offset >= data_size)
{
throw std::runtime_error("journal_offset exceeds device size");
}
}
journal.sector_info = (journal_sector_info_t*)calloc(journal.sector_count, sizeof(journal_sector_info_t));
if (!journal.sector_info)
{
throw std::bad_alloc();
}
if (!journal.inmemory)
{
journal.sector_buf = (uint8_t*)memalign(MEM_ALIGNMENT, journal.sector_count * journal_block_size);
if (!journal.sector_buf)
throw std::bad_alloc();
}
}