thin-provisioning-tools/space_map_disk.h

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2011-07-22 20:39:56 +05:30
#ifndef SPACE_MAP_DISK_H
#define SPACE_MAP_DISK_H
#include "space_map.h"
#include "transaction_manager.h"
#include "endian.h"
#include "space_map_disk_structures.h"
#include "math.h"
//----------------------------------------------------------------
namespace persistent_data {
namespace sm_disk_detail {
using namespace base;
using namespace persistent_data;
template <uint32_t BlockSize>
class bitmap {
public:
bitmap(typename transaction_manager<BlockSize>::ptr tm,
index_entry const &ie)
: tm_(tm),
ie_(ie) {
}
ref_t lookup(unsigned b) const {
auto rr = tm_->read_lock(ie_.blocknr_);
void const *bits = bitmap_data(rr);
ref_t b1 = test_bit_le(bits, b * 2);
ref_t b2 = test_bit_le(bits, b * 2 + 1);
ref_t result = b2 ? 1 : 0;
result |= b1 ? 0b10 : 0;
return result;
}
void insert(unsigned b, ref_t n) {
auto wr = tm_->shadow(ie_.blocknr_).first;
void *bits = bitmap_data(wr);
bool was_free = !test_bit_le(bits, b * 2) && !test_bit_le(bits, b * 2 + 1);
if (n == 1 || n == 3)
set_bit_le(bits, b * 2 + 1);
else
clear_bit_le(bits, b * 2 + 1);
if (n == 2 || n == 3)
set_bit_le(bits, b * 2);
else
clear_bit_le(bits, b * 2);
ie_.blocknr_ = wr.get_location();
if (was_free && n > 0) {
ie_.nr_free_--;
if (b == ie_.none_free_before_)
ie_.none_free_before_++;
}
if (!was_free && n == 0) {
ie_.nr_free_++;
if (b < ie_.none_free_before_)
ie_.none_free_before_ = b;
}
}
unsigned find_free(unsigned end) {
for (unsigned i = ie_.none_free_before_; i < end; i++) {
if (lookup(i) == 0) {
insert(i, 1);
return i;
}
}
throw std::runtime_error("no free entry in bitmap");
}
index_entry const &get_ie() const {
return ie_;
}
private:
void *bitmap_data(typename transaction_manager<BlockSize>::write_ref &wr) {
bitmap_header *h = reinterpret_cast<bitmap_header *>(&wr.data()[0]);
return h + 1;
}
void const *bitmap_data(typename transaction_manager<BlockSize>::read_ref &rr) const {
bitmap_header const *h = reinterpret_cast<bitmap_header const *>(&rr.data()[0]);
return h + 1;
}
typename transaction_manager<BlockSize>::ptr tm_;
index_entry ie_;
};
struct ref_count_traits {
typedef __le32 disk_type;
typedef uint32_t value_type;
typedef NoOpRefCounter<uint32_t> ref_counter;
static void unpack(disk_type const &d, value_type &v) {
v = to_cpu<value_type>(d);
}
static void pack(value_type const &v, disk_type &d) {
d = to_disk<disk_type>(v);
}
};
template <uint32_t BlockSize>
class sm_disk : public persistent_space_map {
public:
typedef boost::shared_ptr<sm_disk<BlockSize> > ptr;
sm_disk(typename transaction_manager<BlockSize>::ptr tm,
block_address nr_blocks)
: tm_(tm),
entries_per_block_((BlockSize - sizeof(bitmap_header)) * 4),
nr_blocks_(0),
nr_allocated_(0),
bitmaps_(tm_, typename sm_disk_detail::index_entry_traits::ref_counter()),
ref_counts_(tm_, ref_count_traits::ref_counter()) {
extend(nr_blocks);
}
sm_disk(typename transaction_manager<BlockSize>::ptr tm,
sm_root const &root)
: tm_(tm),
nr_blocks_(root.nr_blocks_),
nr_allocated_(root.nr_allocated_),
bitmaps_(tm_, root.bitmap_root_, typename sm_disk::index_entry_traits::ref_counter()),
ref_counts_(tm_, root.ref_count_root_, typename ref_count_traits::ref_counter()) {
}
block_address get_nr_blocks() const {
return nr_blocks_;
}
block_address get_nr_free() const {
return nr_blocks_ - nr_allocated_;
}
ref_t get_count(block_address b) const {
auto count = lookup_bitmap(b);
if (count == 3)
return lookup_ref_count(b);
return count;
}
void set_count(block_address b, ref_t c) {
ref_t old = get_count(b);
if (c == old)
return;
if (c > 2) {
if (old < 3)
insert_bitmap(b, 3);
insert_ref_count(b, c);
} else {
if (old > 2)
remove_ref_count(b);
insert_bitmap(b, c);
}
if (old == 0)
nr_allocated_++;
else if (c == 0)
nr_allocated_--;
}
void commit() {
}
void inc(block_address b) {
// FIXME: 2 get_counts
ref_t old = get_count(b);
set_count(b, old + 1);
}
void dec(block_address b) {
ref_t old = get_count(b);
set_count(b, old - 1);
}
block_address new_block() {
// silly to always start searching from the
// beginning.
block_address nr_indexes = div_up<block_address>(nr_blocks_, entries_per_block_);
for (block_address index = 0; index < nr_indexes; index++) {
uint64_t key[1] = {index};
auto mie = bitmaps_.lookup(key);
if (!mie)
throw runtime_error("bitmap entry missing from btree");
bitmap<BlockSize> bm(tm_, *mie);
block_address b = bm.find_free((index == nr_indexes - 1) ?
nr_blocks_ % entries_per_block_ : entries_per_block_);
bitmaps_.insert(key, bm.get_ie());
nr_allocated_++;
b = (index * entries_per_block_) + b;
assert(get_count(b) == 1);
return b;
}
throw runtime_error("out of space");
}
bool count_possibly_greater_than_one(block_address b) const {
return get_count(b) > 1;
}
size_t root_size() {
return sizeof(sm_root_disk);
}
void copy_root(void *dest, size_t len) {
sm_root_disk d;
sm_root v;
if (len < sizeof(d))
throw runtime_error("root too small");
v.nr_blocks_ = nr_blocks_;
v.nr_allocated_ = nr_allocated_;
v.bitmap_root_ = bitmaps_.get_root();
v.ref_count_root_ = ref_counts_.get_root();
sm_root_traits::pack(v, d);
::memcpy(dest, &d, sizeof(d));
}
private:
void extend(block_address extra_blocks) {
block_address nr_blocks = nr_blocks_ + extra_blocks;
block_address bitmap_count = div_up<block_address>(nr_blocks, entries_per_block_);
block_address old_bitmap_count = div_up<block_address>(nr_blocks_, entries_per_block_);
for (block_address i = old_bitmap_count; i < bitmap_count; i++) {
auto wr = tm_->new_block();
struct index_entry ie;
ie.blocknr_ = wr.get_location();
ie.nr_free_ = i == (bitmap_count - 1) ?
(nr_blocks % entries_per_block_) : entries_per_block_;
ie.none_free_before_ = 0;
uint64_t key[1] = {i};
bitmaps_.insert(key, ie);
}
nr_blocks_ = nr_blocks;
}
ref_t lookup_bitmap(block_address b) const {
uint64_t key[1] = {b / entries_per_block_};
auto mindex = bitmaps_.lookup(key);
if (!mindex)
throw runtime_error("Couldn't lookup bitmap");
bitmap<BlockSize> bm(tm_, *mindex);
return bm.lookup(b % entries_per_block_);
}
void insert_bitmap(block_address b, unsigned n) {
if (n > 3)
throw runtime_error("bitmap can only hold 2 bit values");
uint64_t key[1] = {b / entries_per_block_};
auto mindex = bitmaps_.lookup(key);
if (!mindex)
throw runtime_error("Couldn't lookup bitmap");
bitmap<BlockSize> bm(tm_, *mindex);
bm.insert(b % entries_per_block_, n);
bitmaps_.insert(key, bm.get_ie());
}
ref_t lookup_ref_count(block_address b) const {
uint64_t key[1] = {b};
auto mvalue = ref_counts_.lookup(key);
if (!mvalue)
throw runtime_error("ref count not in tree");
return *mvalue;
}
void insert_ref_count(block_address b, ref_t count) {
uint64_t key[1] = {b};
ref_counts_.insert(key, count);
}
void remove_ref_count(block_address b) {
uint64_t key[1] = {b};
ref_counts_.remove(key);
}
typename transaction_manager<BlockSize>::ptr tm_;
uint32_t entries_per_block_;
block_address nr_blocks_;
block_address nr_allocated_;
btree<1, index_entry_traits, BlockSize> bitmaps_;
btree<1, ref_count_traits, BlockSize> ref_counts_;
};
}
template <uint32_t MetadataBlockSize>
persistent_space_map::ptr
create_disk_sm(typename transaction_manager<MetadataBlockSize>::ptr tm,
block_address nr_blocks)
{
using namespace sm_disk_detail;
return typename persistent_space_map::ptr(
new sm_disk<MetadataBlockSize>(tm, nr_blocks));
}
template <uint32_t MetadataBlockSize>
persistent_space_map::ptr
open_disk_sm(typename transaction_manager<MetadataBlockSize>::ptr tm,
void *root)
{
using namespace sm_disk_detail;
sm_root_disk d;
sm_root v;
::memcpy(&d, root, sizeof(d));
sm_root_traits::unpack(d, v);
return typename persistent_space_map::ptr(
new sm_disk<MetadataBlockSize>(tm, v));
}
}
//----------------------------------------------------------------
#endif