330 lines
8.5 KiB
C++
330 lines
8.5 KiB
C++
/*
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* \brief Block device file system
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* \author Josef Soentgen
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* \author Norman Feske
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* \date 2013-12-20
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*/
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/*
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* Copyright (C) 2013-2014 Genode Labs GmbH
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*
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* This file is part of the Genode OS framework, which is distributed
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* under the terms of the GNU General Public License version 2.
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*/
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#ifndef _INCLUDE__VFS__BLOCK_FILE_SYSTEM_H_
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#define _INCLUDE__VFS__BLOCK_FILE_SYSTEM_H_
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#include <base/allocator_avl.h>
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#include <block_session/connection.h>
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#include <vfs/single_file_system.h>
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namespace Vfs { class Block_file_system; }
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class Vfs::Block_file_system : public Single_file_system
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{
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private:
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struct Label
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{
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enum { LABEL_MAX_LEN = 64 };
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char string[LABEL_MAX_LEN];
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Label(Xml_node config)
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{
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string[0] = 0;
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try { config.attribute("label").value(string, sizeof(string)); }
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catch (...) { }
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}
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} _label;
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/*
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* Serialize access to packet stream of the block session
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*/
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Lock _lock;
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char *_block_buffer;
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unsigned _block_buffer_count;
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Genode::Allocator_avl _tx_block_alloc;
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Block::Connection _block;
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Genode::size_t _block_size;
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Block::sector_t _block_count;
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Block::Session::Operations _block_ops;
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Block::Session::Tx::Source *_tx_source;
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bool _readable;
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bool _writeable;
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file_size _block_io(file_size nr, void *buf, file_size sz,
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bool write, bool bulk = false)
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{
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Lock::Guard guard(_lock);
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Block::Packet_descriptor::Opcode op;
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op = write ? Block::Packet_descriptor::WRITE : Block::Packet_descriptor::READ;
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file_size packet_size = bulk ? sz : _block_size;
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file_size packet_count = bulk ? (sz / _block_size) : 1;
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/* sanity check */
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if (packet_count > _block_buffer_count) {
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packet_size = _block_buffer_count * _block_size;
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packet_count = _block_buffer_count;
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}
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Block::Packet_descriptor p(_tx_source->alloc_packet(packet_size), op,
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nr, packet_count);
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if (write)
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Genode::memcpy(_tx_source->packet_content(p), buf, packet_size);
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_tx_source->submit_packet(p);
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p = _tx_source->get_acked_packet();
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if (!p.succeeded()) {
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PERR("Could not read block(s)");
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_tx_source->release_packet(p);
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return 0;
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}
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if (!write)
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Genode::memcpy(buf, _tx_source->packet_content(p), packet_size);
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_tx_source->release_packet(p);
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return packet_size;
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}
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public:
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Block_file_system(Xml_node config)
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:
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Single_file_system(NODE_TYPE_BLOCK_DEVICE, name(), config),
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_label(config),
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_block_buffer(0),
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_block_buffer_count(1),
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_tx_block_alloc(env()->heap()),
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_block(&_tx_block_alloc, 128*1024, _label.string),
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_tx_source(_block.tx()),
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_readable(false),
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_writeable(false)
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{
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try { config.attribute("block_buffer_count").value(&_block_buffer_count); }
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catch (...) { }
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_block.info(&_block_count, &_block_size, &_block_ops);
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_readable = _block_ops.supported(Block::Packet_descriptor::READ);
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_writeable = _block_ops.supported(Block::Packet_descriptor::WRITE);
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_block_buffer = new (env()->heap()) char[_block_buffer_count * _block_size];
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}
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~Block_file_system()
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{
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destroy(env()->heap(), _block_buffer);
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}
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static char const *name() { return "block"; }
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/*********************************
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** Directory service interface **
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*********************************/
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Stat_result stat(char const *path, Stat &out) override
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{
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Stat_result const result = Single_file_system::stat(path, out);
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out.size = _block_count * _block_size;
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return result;
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}
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/********************************
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** File I/O service interface **
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********************************/
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Write_result write(Vfs_handle *vfs_handle, char const *buf,
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file_size count, file_size &out_count) override
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{
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if (!_writeable) {
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PERR("block device is not writeable");
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return WRITE_ERR_INVALID;
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}
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file_size seek_offset = vfs_handle->seek();
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file_size written = 0;
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while (count > 0) {
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file_size displ = 0;
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file_size length = 0;
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file_size nbytes = 0;
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file_size blk_nr = seek_offset / _block_size;
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displ = seek_offset % _block_size;
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if ((displ + count) > _block_size)
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length = (_block_size - displ);
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else
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length = count;
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/*
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* We take a shortcut and write as much as possible without
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* using the block buffer if the offset is aligned on a block
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* boundary and the count is a multiple of the block size,
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* e.g. 4K writes will be written at once.
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*
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* XXX this is quite hackish because we have to omit partial
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* blocks at the end.
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*/
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if (displ == 0 && (count % _block_size) >= 0 && !(count < _block_size)) {
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file_size bytes_left = count - (count % _block_size);
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nbytes = _block_io(blk_nr, (void*)(buf + written),
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bytes_left, true, true);
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if (nbytes == 0) {
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PERR("error while write block:%llu from block device",
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blk_nr);
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return WRITE_ERR_INVALID;
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}
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written += nbytes;
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count -= nbytes;
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continue;
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}
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/*
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* The offset is not aligned on a block boundary. Therefore
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* we need to read the block to the block buffer first and
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* put the buffer content at the right offset before we can
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* write the whole block back. In addition if length is less
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* than block size, we also have to read the block first.
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*/
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if (displ > 0 || length < _block_size) {
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PWRN("offset:%llu block_size:%zd displacement:%llu length:%llu",
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seek_offset, _block_size, displ, length);
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_block_io(blk_nr, _block_buffer, _block_size, false);
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/* rewind seek offset to account for the block read */
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seek_offset -= _block_size;
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}
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Genode::memcpy(_block_buffer + displ, buf + written, length);
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nbytes = _block_io(blk_nr, _block_buffer, _block_size, true);
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if ((unsigned)nbytes != _block_size) {
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PERR("error while writing block:%llu from Block_device",
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blk_nr);
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return WRITE_ERR_INVALID;
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}
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written += length;
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count -= length;
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}
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out_count = written;
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return WRITE_OK;
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}
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Read_result read(Vfs_handle *vfs_handle, char *dst, file_size count,
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file_size &out_count) override
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{
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if (!_readable) {
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PERR("block device is not readable");
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return READ_ERR_INVALID;
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}
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file_size seek_offset = vfs_handle->seek();
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file_size read = 0;
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while (count > 0) {
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file_size displ = 0;
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file_size length = 0;
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file_size nbytes = 0;
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file_size blk_nr = seek_offset / _block_size;
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displ = seek_offset % _block_size;
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if ((displ + count) > _block_size)
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length = (_block_size - displ);
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else
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length = count;
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/*
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* We take a shortcut and read the blocks all at once if t he
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* offset is aligned on a block boundary and we the count is a
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* multiple of the block size, e.g. 4K reads will be read at
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* once.
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*
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* XXX this is quite hackish because we have to omit partial
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* blocks at the end.
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*/
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if (displ == 0 && (count % _block_size) >= 0 && !(count < _block_size)) {
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file_size bytes_left = count - (count % _block_size);
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nbytes = _block_io(blk_nr, dst + read, bytes_left, false, true);
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if (nbytes == 0) {
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PERR("error while reading block:%llu from block device",
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blk_nr);
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return READ_ERR_INVALID;
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}
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read += nbytes;
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count -= nbytes;
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continue;
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}
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if (displ > 0)
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PWRN("offset:%llu is not aligned to block_size:%zu"
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" displacement:%llu", seek_offset, _block_size,
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displ);
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nbytes = _block_io(blk_nr, _block_buffer, _block_size, false);
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if ((unsigned)nbytes != _block_size) {
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PERR("error while reading block:%llu from block device",
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blk_nr);
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return READ_ERR_INVALID;
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}
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Genode::memcpy(dst + read, _block_buffer + displ, length);
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read += length;
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count -= length;
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}
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out_count = read;
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return READ_OK;
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}
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Ftruncate_result ftruncate(Vfs_handle *vfs_handle, file_size) override
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{
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return FTRUNCATE_OK;
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}
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Ioctl_result ioctl(Vfs_handle *vfs_handle, Ioctl_opcode opcode, Ioctl_arg,
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Ioctl_out &out) override
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{
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switch (opcode) {
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case IOCTL_OP_DIOCGMEDIASIZE:
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out.diocgmediasize.size = _block_count * _block_size;
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return IOCTL_OK;
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default:
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PDBG("invalid ioctl request %d", opcode);
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break;
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}
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/* never reached */
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return IOCTL_ERR_INVALID;
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}
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};
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#endif /* _INCLUDE__VFS__BLOCK_FILE_SYSTEM_H_ */
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