/*
* \brief Block device file system
* \author Josef Soentgen
* \author Norman Feske
* \date 2013-12-20
*/
/*
* Copyright (C) 2013-2017 Genode Labs GmbH
*
* This file is part of the Genode OS framework, which is distributed
* under the terms of the GNU Affero General Public License version 3.
*/
#ifndef _INCLUDE__VFS__BLOCK_FILE_SYSTEM_H_
#define _INCLUDE__VFS__BLOCK_FILE_SYSTEM_H_
#include
#include
#include
namespace Vfs { class Block_file_system; }
class Vfs::Block_file_system : public Single_file_system
{
private:
Vfs::Env &_env;
typedef Genode::String<64> Label;
Label _label;
/*
* Serialize access to packet stream of the block session
*/
Mutex _mutex { };
char *_block_buffer;
unsigned _block_buffer_count;
Genode::Allocator_avl _tx_block_alloc { &_env.alloc() };
Block::Connection<> _block {
_env.env(), &_tx_block_alloc, 128*1024, _label.string() };
Block::Session::Info const _info { _block.info() };
Block::Session::Tx::Source *_tx_source;
bool _writeable;
Genode::Signal_receiver _signal_receiver { };
Genode::Signal_context _signal_context { };
Genode::Signal_context_capability _source_submit_cap;
/*
* Noncopyable
*/
Block_file_system(Block_file_system const &);
Block_file_system &operator = (Block_file_system const &);
class Block_vfs_handle : public Single_vfs_handle
{
private:
Genode::Allocator &_alloc;
Label &_label;
Mutex &_mutex;
char *_block_buffer;
unsigned &_block_buffer_count;
Genode::Allocator_avl &_tx_block_alloc;
Block::Connection<> &_block;
Genode::size_t const _block_size;
Block::sector_t const _block_count;
Block::Session::Tx::Source *_tx_source;
bool const _writeable;
Genode::Signal_receiver &_signal_receiver;
Genode::Signal_context &_signal_context;
Genode::Signal_context_capability &_source_submit_cap;
/*
* Noncopyable
*/
Block_vfs_handle(Block_vfs_handle const &);
Block_vfs_handle &operator = (Block_vfs_handle const &);
file_size _block_io(file_size nr, void *buf, file_size sz,
bool write, bool bulk = false)
{
Block::Packet_descriptor::Opcode op;
op = write ? Block::Packet_descriptor::WRITE : Block::Packet_descriptor::READ;
file_size packet_size = bulk ? sz : _block_size;
file_size packet_count = bulk ? (sz / _block_size) : 1;
Block::Packet_descriptor packet;
/* sanity check */
if (packet_count > _block_buffer_count) {
packet_size = _block_buffer_count * _block_size;
packet_count = _block_buffer_count;
}
while (true) {
try {
Mutex::Guard guard(_mutex);
packet = _block.alloc_packet(packet_size);
break;
} catch (Block::Session::Tx::Source::Packet_alloc_failed) {
if (!_tx_source->ready_to_submit())
_signal_receiver.wait_for_signal();
else {
if (packet_count > 1) {
packet_size /= 2;
packet_count /= 2;
}
}
}
}
Mutex::Guard guard(_mutex);
Block::Packet_descriptor p(packet, op, nr, packet_count);
if (write)
Genode::memcpy(_tx_source->packet_content(p), buf, packet_size);
_tx_source->submit_packet(p);
p = _tx_source->get_acked_packet();
if (!p.succeeded()) {
Genode::error("Could not read block(s)");
_tx_source->release_packet(p);
return 0;
}
if (!write)
Genode::memcpy(buf, _tx_source->packet_content(p), packet_size);
_tx_source->release_packet(p);
return packet_size;
}
public:
Block_vfs_handle(Directory_service &ds,
File_io_service &fs,
Genode::Allocator &alloc,
Label &label,
Mutex &mutex,
char *block_buffer,
unsigned &block_buffer_count,
Genode::Allocator_avl &tx_block_alloc,
Block::Connection<> &block,
Genode::size_t block_size,
Block::sector_t block_count,
Block::Session::Tx::Source *tx_source,
bool writeable,
Genode::Signal_receiver &signal_receiver,
Genode::Signal_context &signal_context,
Genode::Signal_context_capability &source_submit_cap)
: Single_vfs_handle(ds, fs, alloc, 0),
_alloc(alloc),
_label(label),
_mutex(mutex),
_block_buffer(block_buffer),
_block_buffer_count(block_buffer_count),
_tx_block_alloc(tx_block_alloc),
_block(block),
_block_size(block_size),
_block_count(block_count),
_tx_source(tx_source),
_writeable(writeable),
_signal_receiver(signal_receiver),
_signal_context(signal_context),
_source_submit_cap(source_submit_cap)
{ }
Read_result read(char *dst, file_size count,
file_size &out_count) override
{
file_size seek_offset = seek();
file_size read = 0;
while (count > 0) {
file_size displ = 0;
file_size length = 0;
file_size nbytes = 0;
file_size blk_nr = seek_offset / _block_size;
displ = seek_offset % _block_size;
if ((displ + count) > _block_size)
length = (_block_size - displ);
else
length = count;
/*
* We take a shortcut and read the blocks all at once if the
* offset is aligned on a block boundary and the count is a
* multiple of the block size, e.g. 4K reads will be read at
* once.
*
* XXX this is quite hackish because we have to omit partial
* blocks at the end.
*/
if (displ == 0 && !(count < _block_size)) {
file_size bytes_left = count - (count % _block_size);
nbytes = _block_io(blk_nr, dst + read, bytes_left, false, true);
if (nbytes == 0) {
Genode::error("error while reading block:", blk_nr, " from block device");
return READ_ERR_INVALID;
}
read += nbytes;
count -= nbytes;
seek_offset += nbytes;
continue;
}
nbytes = _block_io(blk_nr, _block_buffer, _block_size, false);
if ((unsigned)nbytes != _block_size) {
Genode::error("error while reading block:", blk_nr, " from block device");
return READ_ERR_INVALID;
}
Genode::memcpy(dst + read, _block_buffer + displ, length);
read += length;
count -= length;
seek_offset += length;
}
out_count = read;
return READ_OK;
}
Write_result write(char const *buf, file_size count,
file_size &out_count) override
{
if (!_writeable) {
Genode::error("block device is not writeable");
return WRITE_ERR_INVALID;
}
file_size seek_offset = seek();
file_size written = 0;
while (count > 0) {
file_size displ = 0;
file_size length = 0;
file_size nbytes = 0;
file_size blk_nr = seek_offset / _block_size;
displ = seek_offset % _block_size;
if ((displ + count) > _block_size)
length = (_block_size - displ);
else
length = count;
/*
* We take a shortcut and write as much as possible without
* using the block buffer if the offset is aligned on a block
* boundary and the count is a multiple of the block size,
* e.g. 4K writes will be written at once.
*
* XXX this is quite hackish because we have to omit partial
* blocks at the end.
*/
if (displ == 0 && !(count < _block_size)) {
file_size bytes_left = count - (count % _block_size);
nbytes = _block_io(blk_nr, (void*)(buf + written),
bytes_left, true, true);
if (nbytes == 0) {
Genode::error("error while write block:", blk_nr, " to block device");
return WRITE_ERR_INVALID;
}
written += nbytes;
count -= nbytes;
seek_offset += nbytes;
continue;
}
/*
* The offset is not aligned on a block boundary. Therefore
* we need to read the block to the block buffer first and
* put the buffer content at the right offset before we can
* write the whole block back. In addition if length is less
* than block size, we also have to read the block first.
*/
if (displ > 0 || length < _block_size)
_block_io(blk_nr, _block_buffer, _block_size, false);
Genode::memcpy(_block_buffer + displ, buf + written, length);
nbytes = _block_io(blk_nr, _block_buffer, _block_size, true);
if ((unsigned)nbytes != _block_size) {
Genode::error("error while writing block:", blk_nr, " to block_device");
return WRITE_ERR_INVALID;
}
written += length;
count -= length;
seek_offset += length;
}
out_count = written;
return WRITE_OK;
}
Sync_result sync() override
{
/*
* Just in case bail if we cannot submit the packet.
* (Since the plugin operates in a synchronous fashion
* that should not happen.)
*/
if (!_tx_source->ready_to_submit()) {
Genode::error("vfs_block: could not sync blocks");
return SYNC_ERR_INVALID;
}
Block::Packet_descriptor p =
Block::Session::sync_all_packet_descriptor(
_block.info(), Block::Session::Tag { 0 });
_tx_source->submit_packet(p);
p = _tx_source->get_acked_packet();
_tx_source->release_packet(p);
if (!p.succeeded()) {
Genode::error("vfs_block: syncing blocks failed");
return SYNC_ERR_INVALID;
}
return SYNC_OK;
}
bool read_ready() override { return true; }
};
public:
Block_file_system(Vfs::Env &env, Genode::Xml_node config)
:
Single_file_system(Node_type::CONTINUOUS_FILE, name(),
Node_rwx::rw(), config),
_env(env),
_label(config.attribute_value("label", Label())),
_block_buffer(0),
_block_buffer_count(config.attribute_value("block_buffer_count", 1UL)),
_tx_source(_block.tx()),
_writeable(_info.writeable),
_source_submit_cap(_signal_receiver.manage(&_signal_context))
{
_block_buffer = new (_env.alloc())
char[_block_buffer_count * _info.block_size];
_block.tx_channel()->sigh_ready_to_submit(_source_submit_cap);
}
~Block_file_system()
{
_signal_receiver.dissolve(&_signal_context);
destroy(_env.alloc(), _block_buffer);
}
static char const *name() { return "block"; }
char const *type() override { return "block"; }
/*********************************
** Directory service interface **
*********************************/
Open_result open(char const *path, unsigned,
Vfs_handle **out_handle,
Allocator &alloc) override
{
if (!_single_file(path))
return OPEN_ERR_UNACCESSIBLE;
try {
*out_handle = new (alloc) Block_vfs_handle(*this, *this, alloc,
_label, _mutex,
_block_buffer,
_block_buffer_count,
_tx_block_alloc,
_block,
_info.block_size,
_info.block_count,
_tx_source,
_info.writeable,
_signal_receiver,
_signal_context,
_source_submit_cap);
return OPEN_OK;
}
catch (Genode::Out_of_ram) { return OPEN_ERR_OUT_OF_RAM; }
catch (Genode::Out_of_caps) { return OPEN_ERR_OUT_OF_CAPS; }
}
Stat_result stat(char const *path, Stat &out) override
{
Stat_result const result = Single_file_system::stat(path, out);
out.size = _info.block_count * _info.block_size;
return result;
}
/********************************
** File I/O service interface **
********************************/
Ftruncate_result ftruncate(Vfs_handle *, file_size) override
{
return FTRUNCATE_OK;
}
Ioctl_result ioctl(Vfs_handle *, Ioctl_opcode opcode, Ioctl_arg,
Ioctl_out &out) override
{
switch (opcode) {
case IOCTL_OP_DIOCGMEDIASIZE:
out.diocgmediasize.size = _info.block_count * _info.block_size;
return IOCTL_OK;
default:
Genode::warning("invalid ioctl request ", (int)opcode);
break;
}
/* never reached */
return IOCTL_ERR_INVALID;
}
};
#endif /* _INCLUDE__VFS__BLOCK_FILE_SYSTEM_H_ */