151 lines
5.6 KiB
C
151 lines
5.6 KiB
C
/* $NetBSD: wapbl_replay.h,v 1.1 2008/11/24 16:05:21 joerg Exp $ */
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/*-
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* Copyright (c) 2003,2008 The NetBSD Foundation, Inc.
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* All rights reserved.
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*
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* This code is derived from software contributed to The NetBSD Foundation
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* by Wasabi Systems, Inc.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
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* ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
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* TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
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* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
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* BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
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* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
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* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
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* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
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* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
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* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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* POSSIBILITY OF SUCH DAMAGE.
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*/
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#ifndef _SYS_WAPBL_REPLAY_H
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#define _SYS_WAPBL_REPLAY_H
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#include <sys/types.h>
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/* The WAPBL journal layout.
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*
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* The journal consists of a header followed by a circular buffer
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* region. The circular data area is described by the header
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* wc_circ_off, wc_circ_size, wc_head and wc_tail fields as bytes
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* from the start of the journal header. New records are inserted
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* at wc_head and the oldest valid record can be found at wc_tail.
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* When ((wc_head == wc_tail) && (wc_head == 0)), the journal is empty.
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* The condition of ((wc_head == wc_tail) && (wc_head != 0))
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* indicates a full journal, although this condition is rare.
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*
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* The journal header as well as its records are marked by a 32bit
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* type tag and length for ease of parsing. Journal records are
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* padded so as to fall on journal device block boundaries.
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*/
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/*
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* The following are the 4 record types used by the journal:
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* Each tag indicates journal data organized by one of the
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* structures used below.
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*/
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enum {
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WAPBL_WC_HEADER = 0x5741424c, /* "WABL", struct wapbl_wc_header */
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WAPBL_WC_INODES, /* struct wapbl_wc_inodelist */
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WAPBL_WC_REVOCATIONS, /* struct wapbl_wc_blocklist */
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WAPBL_WC_BLOCKS, /* struct wapbl_wc_blocklist */
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};
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/* null entry (on disk) */
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/* This structure isn't used directly, but shares its header
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* layout with all the other log structures for the purpose
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* of reading a log structure and determining its type
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*/
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struct wapbl_wc_null {
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uint32_t wc_type; /* WAPBL_WC_* */
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int32_t wc_len;
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uint8_t wc_spare[0]; /* actually longer */
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};
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/* journal header (on-disk)
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* This record is found at the start of the
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* journal, but not within the circular buffer region. As well as
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* describing the journal parameters and matching filesystem, it
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* additionally serves as the atomic update record for journal
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* updates.
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*/
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struct wapbl_wc_header {
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uint32_t wc_type; /* WAPBL_WC_HEADER log magic number */
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int32_t wc_len; /* length of this journal entry */
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uint32_t wc_checksum;
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uint32_t wc_generation;
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int32_t wc_fsid[2];
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uint64_t wc_time;
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uint32_t wc_timensec;
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uint32_t wc_version;
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uint32_t wc_log_dev_bshift;
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uint32_t wc_fs_dev_bshift;
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int64_t wc_head;
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int64_t wc_tail;
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int64_t wc_circ_off; /* offset of of circ buffer region */
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int64_t wc_circ_size; /* size of circular buffer region */
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uint8_t wc_spare[0]; /* actually longer */
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};
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/* list of blocks (on disk)
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* This record is used to describe a set of filesystem blocks,
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* and is used with two type tags, WAPBL_WC_BLOCKS and
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* WAPBL_WC_REVOCATIONS.
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*
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* For WAPBL_WC_BLOCKS, a copy of each listed block can be found
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* starting at the next log device blocksize boundary. starting at
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* one log device block since the start of the record. This contains
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* the bulk of the filesystem journal data which is written using
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* these records before being written into the filesystem.
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*
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* The WAPBL_WC_REVOCATIONS record is used to indicate that any
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* previously listed blocks should not be written into the filesystem.
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* This is important so that deallocated and reallocated data blocks
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* do not get overwritten with stale data from the journal. The
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* revocation records do not contain a copy of any actual block data.
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*/
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struct wapbl_wc_blocklist {
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uint32_t wc_type; /* WAPBL_WC_{REVOCATIONS,BLOCKS} */
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int32_t wc_len;
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int32_t wc_blkcount;
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int32_t wc_unused;
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struct {
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int64_t wc_daddr;
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int32_t wc_unused;
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int32_t wc_dlen;
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} wc_blocks[0]; /* actually longer */
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};
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/* list of inodes (on disk)
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* This record is used to describe the set of inodes which
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* may be allocated but are unlinked. Inodes end up listed here
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* while they are in the process of being initialized and
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* deinitialized. Inodes unlinked while in use by a process
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* will be listed here and the actual deletion must be completed
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* on journal replay.
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*/
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struct wapbl_wc_inodelist {
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uint32_t wc_type; /* WAPBL_WC_INODES */
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int32_t wc_len;
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int32_t wc_inocnt;
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int32_t wc_clear; /* set if previously listed inodes
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hould be ignored */
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struct {
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uint32_t wc_inumber;
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uint32_t wc_imode;
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} wc_inodes[0]; /* actually longer */
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};
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#endif /* _SYS_WAPBL_REPLAY_H */
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