122 lines
5.6 KiB
C
122 lines
5.6 KiB
C
/****************************************************************************
|
|
* fs/mnemofs/mnemofs_master.c
|
|
* Master node of mnemofs.
|
|
*
|
|
* Licensed to the Apache Software Foundation (ASF) under one or more
|
|
* contributor license agreements. See the NOTICE file distributed with
|
|
* this work for additional information regarding copyright ownership. The
|
|
* ASF licenses this file to you under the Apache License, Version 2.0 (the
|
|
* "License"); you may not use this file except in compliance with the
|
|
* License. You may obtain a copy of the License at
|
|
*
|
|
* http://www.apache.org/licenses/LICENSE-2.0
|
|
*
|
|
* Unless required by applicable law or agreed to in writing, software
|
|
* distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
|
|
* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
|
|
* License for the specific language governing permissions and limitations
|
|
* under the License.
|
|
*
|
|
* Alternatively, the contents of this file may be used under the terms of
|
|
* the BSD-3-Clause license:
|
|
*
|
|
* SPDX-License-Identifier: BSD-3-Clause
|
|
*
|
|
* Copyright (c) 2024 Saurav Pal
|
|
*
|
|
* Redistribution and use in source and binary forms, with or without
|
|
* modification, are permitted provided that the following conditions
|
|
* are met:
|
|
* 1. Redistributions of source code must retain the above copyright
|
|
* notice, this list of conditions and the following disclaimer.
|
|
* 2. Redistributions in binary form must reproduce the above copyright
|
|
* notice, this list of conditions and the following disclaimer in the
|
|
* documentation and/or other materials provided with the distribution.
|
|
* 3. Neither the name of the author nor the names of its contributors may
|
|
* be used to endorse or promote products derived from this software
|
|
*
|
|
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS "AS IS" AND
|
|
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
|
|
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
|
|
* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
|
|
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
|
|
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
|
|
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
|
|
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
|
|
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
|
|
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
|
|
* SUCH DAMAGE.
|
|
*
|
|
****************************************************************************/
|
|
|
|
/****************************************************************************
|
|
* In mnemofs, the master node points to the root of the file system. It
|
|
* contains the information about the root, and when the root is updated,
|
|
* the master node needs to point to the updated location, and thus, needs to
|
|
* update the master node.
|
|
*
|
|
* Master nodes sit at the very end of the journal. The last two blocks of
|
|
* the journal are called master blocks, and they are filled with a new
|
|
* entry for a master node everytime it is updated. They are filled in a
|
|
* sequential manner, and thus, the latest master node can be found easily.
|
|
* The two master blocks contain identical information, and exist to be as a
|
|
* backup.
|
|
*
|
|
* The stored master nodes are basically `struct mfs_mn_s` without the
|
|
* redundant `pg` member.
|
|
*
|
|
* The master node also points to the start of the journal, and thus, when
|
|
* the journal moves, a new master node entry is added.
|
|
*
|
|
* A master node update, when written to the file system, marks the end of
|
|
* an update of the file system tree. Thus, at this point, any obsolete data
|
|
* that can be erased, will be erased by the block allocator. Only after
|
|
* writing the master block is the file system tree updated. Before this,
|
|
* the old file system tree is accessible through the older master node, and
|
|
* can be accessed again during power loss.
|
|
****************************************************************************/
|
|
|
|
/****************************************************************************
|
|
* Included Files
|
|
****************************************************************************/
|
|
|
|
#include <nuttx/kmalloc.h>
|
|
#include <sys/stat.h>
|
|
|
|
#include "mnemofs.h"
|
|
|
|
/****************************************************************************
|
|
* Pre-processor Definitions
|
|
****************************************************************************/
|
|
|
|
/****************************************************************************
|
|
* Private Types
|
|
****************************************************************************/
|
|
|
|
/****************************************************************************
|
|
* Private Function Prototypes
|
|
****************************************************************************/
|
|
|
|
/****************************************************************************
|
|
* Private Data
|
|
****************************************************************************/
|
|
|
|
/****************************************************************************
|
|
* Public Data
|
|
****************************************************************************/
|
|
|
|
/****************************************************************************
|
|
* Private Functions
|
|
****************************************************************************/
|
|
|
|
/****************************************************************************
|
|
* Public Functions
|
|
****************************************************************************/
|
|
|
|
int mfs_mn_fmt(FAR struct mfs_sb_s * const sb, const mfs_t jrnl_blk)
|
|
{
|
|
/* TODO */
|
|
|
|
return OK;
|
|
}
|