LCOM1920-T02G10

/*        $NetBSD: wapbl_replay.h,v 1.1 2008/11/24 16:05:21 joerg Exp $        */

/*-

 * Copyright (c) 2003,2008 The NetBSD Foundation, Inc.

 * All rights reserved.

 *

 * This code is derived from software contributed to The NetBSD Foundation

 * by Wasabi Systems, Inc.

 *

 * 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.

 *

 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. 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 FOUNDATION 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.

 */

#ifndef _SYS_WAPBL_REPLAY_H

#define        _SYS_WAPBL_REPLAY_H

#include <sys/types.h>

/* The WAPBL journal layout.

 * 

 * The journal consists of a header followed by a circular buffer

 * region.  The circular data area is described by the header

 * wc_circ_off, wc_circ_size, wc_head and wc_tail fields as bytes

 * from the start of the journal header.  New records are inserted

 * at wc_head and the oldest valid record can be found at wc_tail.

 * When ((wc_head == wc_tail) && (wc_head == 0)), the journal is empty.

 * The condition of ((wc_head == wc_tail) && (wc_head != 0))

 * indicates a full journal, although this condition is rare.

 *

 * The journal header as well as its records are marked by a 32bit

 * type tag and length for ease of parsing.  Journal records are

 * padded so as to fall on journal device block boundaries.

 */

/*

 * The following are the 4 record types used by the journal:

 * Each tag indicates journal data organized by one of the

 * structures used below.

 */

enum {

        WAPBL_WC_HEADER = 0x5741424c,        /* "WABL", struct wapbl_wc_header */

        WAPBL_WC_INODES,                /* struct wapbl_wc_inodelist */

        WAPBL_WC_REVOCATIONS,                /* struct wapbl_wc_blocklist */

        WAPBL_WC_BLOCKS,                /* struct wapbl_wc_blocklist */

};

/* null entry (on disk) */

/* This structure isn't used directly, but shares its header

 * layout with all the other log structures for the purpose

 * of reading a log structure and determining its type

 */

struct wapbl_wc_null {

        uint32_t        wc_type;        /* WAPBL_WC_* */

        int32_t                wc_len;

        uint8_t                wc_spare[0];        /* actually longer */

};

/* journal header (on-disk)

 * This record is found at the start of the

 * journal, but not within the circular buffer region.  As well as

 * describing the journal parameters and matching filesystem, it

 * additionally serves as the atomic update record for journal

 * updates.

 */

struct wapbl_wc_header {

        uint32_t        wc_type;        /* WAPBL_WC_HEADER log magic number */

        int32_t                wc_len;                /* length of this journal entry */

        uint32_t        wc_checksum;

        uint32_t        wc_generation;

        int32_t                wc_fsid[2];

        uint64_t        wc_time;

        uint32_t        wc_timensec;

        uint32_t        wc_version;

        uint32_t        wc_log_dev_bshift;

        uint32_t        wc_fs_dev_bshift;

        int64_t                wc_head;

        int64_t                wc_tail;

        int64_t                wc_circ_off;        /* offset of of circ buffer region */

        int64_t                wc_circ_size;        /* size of circular buffer region */

        uint8_t                wc_spare[0];        /* actually longer */

};

/* list of blocks (on disk)

 * This record is used to describe a set of filesystem blocks,

 * and is used with two type tags, WAPBL_WC_BLOCKS and

 * WAPBL_WC_REVOCATIONS.

 * 

 * For WAPBL_WC_BLOCKS, a copy of each listed block can be found

 * starting at the next log device blocksize boundary.  starting at

 * one log device block since the start of the record.  This contains

 * the bulk of the filesystem journal data which is written using

 * these records before being written into the filesystem.

 *

 * The WAPBL_WC_REVOCATIONS record is used to indicate that any

 * previously listed blocks should not be written into the filesystem.

 * This is important so that deallocated and reallocated data blocks

 * do not get overwritten with stale data from the journal.  The

 * revocation records do not contain a copy of any actual block data.

 */

struct wapbl_wc_blocklist {

        uint32_t        wc_type; /* WAPBL_WC_{REVOCATIONS,BLOCKS} */

        int32_t                wc_len;

        int32_t                wc_blkcount;

        int32_t                wc_unused;

        struct {

                int64_t        wc_daddr;

                int32_t        wc_unused;

                int32_t        wc_dlen;

        } wc_blocks[0];                        /* actually longer */

};

/* list of inodes (on disk)

 * This record is used to describe the set of inodes which

 * may be allocated but are unlinked.  Inodes end up listed here

 * while they are in the process of being initialized and

 * deinitialized.  Inodes unlinked while in use by a process

 * will be listed here and the actual deletion must be completed

 * on journal replay.

 */

struct wapbl_wc_inodelist {

        uint32_t        wc_type; /* WAPBL_WC_INODES */

        int32_t                wc_len;

        int32_t                wc_inocnt;

        int32_t                wc_clear;        /* set if previously listed inodes 

                                           hould be ignored */

        struct {

                uint32_t wc_inumber;

                uint32_t wc_imode;

        } wc_inodes[0];                /* actually longer */

};

#endif /* _SYS_WAPBL_REPLAY_H */