source: svn/trunk/newcon3bcm2_21bu/toolchain/mips-linux-uclibc/include/linux/jbd.h

/*
 * linux/include/linux/jbd.h
 * 
 * Written by Stephen C. Tweedie <sct@redhat.com>
 *
 * Copyright 1998-2000 Red Hat, Inc --- All Rights Reserved
 *
 * This file is part of the Linux kernel and is made available under
 * the terms of the GNU General Public License, version 2, or at your
 * option, any later version, incorporated herein by reference.
 *
 * Definitions for transaction data structures for the buffer cache
 * filesystem journaling support.
 */

#ifndef _LINUX_JBD_H
#define _LINUX_JBD_H

#if defined(CONFIG_JBD) || defined(CONFIG_JBD_MODULE)

/* Allow this file to be included directly into e2fsprogs */
#include "jfs_compat.h"
#define JFS_DEBUG
#define jfs_debug jbd_debug

#define journal_oom_retry 1

/*
 * Define JBD_PARANIOD_IOFAIL to cause a kernel BUG() if ext3 finds
 * certain classes of error which can occur due to failed IOs.  Under
 * normal use we want ext3 to continue after such errors, because
 * hardware _can_ fail, but for debugging purposes when running tests on
 * known-good hardware we may want to trap these errors.
 */
#undef JBD_PARANOID_IOFAIL

/*
 * The default maximum commit age, in seconds.
 */
#define JBD_DEFAULT_MAX_COMMIT_AGE 5

#ifdef CONFIG_JBD_DEBUG
/*
 * Define JBD_EXPENSIVE_CHECKING to enable more expensive internal
 * consistency checks.  By default we don't do this unless
 * CONFIG_JBD_DEBUG is on.
 */
#define JBD_EXPENSIVE_CHECKING
extern int journal_enable_debug;

#define jbd_debug(n, f, a...)                                           \
        do {                                                            \
                if ((n) <= journal_enable_debug) {                      \
                        printk (KERN_DEBUG "(%s, %d): %s: ",            \
                                __FILE__, __LINE__, __FUNCTION__);      \
                        printk (f, ## a);                               \
                }                                                       \
        } while (0)
#else
#define jbd_debug(f, a...)      /**/
#endif

extern void * __jbd_kmalloc (const char *where, size_t size, int flags, int retry);
#define jbd_kmalloc(size, flags) \
        __jbd_kmalloc(__FUNCTION__, (size), (flags), journal_oom_retry)
#define jbd_rep_kmalloc(size, flags) \
        __jbd_kmalloc(__FUNCTION__, (size), (flags), 1)

#define JFS_MIN_JOURNAL_BLOCKS 1024


/*
 * Internal structures used by the logging mechanism:
 */

#define JFS_MAGIC_NUMBER 0xc03b3998U /* The first 4 bytes of /dev/random! */

/*
 * On-disk structures
 */

/* 
 * Descriptor block types:
 */

#define JFS_DESCRIPTOR_BLOCK    1
#define JFS_COMMIT_BLOCK        2
#define JFS_SUPERBLOCK_V1       3
#define JFS_SUPERBLOCK_V2       4
#define JFS_REVOKE_BLOCK        5

/*
 * Standard header for all descriptor blocks:
 */
typedef struct journal_header_s
{
        __be32          h_magic;
        __be32          h_blocktype;
        __be32          h_sequence;
} journal_header_t;


/* 
 * The block tag: used to describe a single buffer in the journal 
 */
typedef struct journal_block_tag_s
{
        __be32          t_blocknr;      /* The on-disk block number */
        __be32          t_flags;        /* See below */
} journal_block_tag_t;

/* 
 * The revoke descriptor: used on disk to describe a series of blocks to
 * be revoked from the log 
 */
typedef struct journal_revoke_header_s
{
        journal_header_t r_header;
        __be32           r_count;       /* Count of bytes used in the block */
} journal_revoke_header_t;


/* Definitions for the journal tag flags word: */
#define JFS_FLAG_ESCAPE         1       /* on-disk block is escaped */
#define JFS_FLAG_SAME_UUID      2       /* block has same uuid as previous */
#define JFS_FLAG_DELETED        4       /* block deleted by this transaction */
#define JFS_FLAG_LAST_TAG       8       /* last tag in this descriptor block */


/*
 * The journal superblock.  All fields are in big-endian byte order.
 */
typedef struct journal_superblock_s
{
/* 0x0000 */
        journal_header_t s_header;

/* 0x000C */
        /* Static information describing the journal */
        __be32  s_blocksize;            /* journal device blocksize */
        __be32  s_maxlen;               /* total blocks in journal file */
        __be32  s_first;                /* first block of log information */

/* 0x0018 */
        /* Dynamic information describing the current state of the log */
        __be32  s_sequence;             /* first commit ID expected in log */
        __be32  s_start;                /* blocknr of start of log */

/* 0x0020 */
        /* Error value, as set by journal_abort(). */
        __be32  s_errno;

/* 0x0024 */
        /* Remaining fields are only valid in a version-2 superblock */
        __be32  s_feature_compat;       /* compatible feature set */
        __be32  s_feature_incompat;     /* incompatible feature set */
        __be32  s_feature_ro_compat;    /* readonly-compatible feature set */
/* 0x0030 */
        __u8    s_uuid[16];             /* 128-bit uuid for journal */

/* 0x0040 */
        __be32  s_nr_users;             /* Nr of filesystems sharing log */

        __be32  s_dynsuper;             /* Blocknr of dynamic superblock copy*/

/* 0x0048 */
        __be32  s_max_transaction;      /* Limit of journal blocks per trans.*/
        __be32  s_max_trans_data;       /* Limit of data blocks per trans. */

/* 0x0050 */
        __u32   s_padding[44];

/* 0x0100 */
        __u8    s_users[16*48];         /* ids of all fs'es sharing the log */
/* 0x0400 */
} journal_superblock_t;

#define JFS_HAS_COMPAT_FEATURE(j,mask)                                  \
        ((j)->j_format_version >= 2 &&                                  \
         ((j)->j_superblock->s_feature_compat & cpu_to_be32((mask))))
#define JFS_HAS_RO_COMPAT_FEATURE(j,mask)                               \
        ((j)->j_format_version >= 2 &&                                  \
         ((j)->j_superblock->s_feature_ro_compat & cpu_to_be32((mask))))
#define JFS_HAS_INCOMPAT_FEATURE(j,mask)                                \
        ((j)->j_format_version >= 2 &&                                  \
         ((j)->j_superblock->s_feature_incompat & cpu_to_be32((mask))))

#define JFS_FEATURE_INCOMPAT_REVOKE     0x00000001

/* Features known to this kernel version: */
#define JFS_KNOWN_COMPAT_FEATURES       0
#define JFS_KNOWN_ROCOMPAT_FEATURES     0
#define JFS_KNOWN_INCOMPAT_FEATURES     JFS_FEATURE_INCOMPAT_REVOKE


/* Comparison functions for transaction IDs: perform comparisons using
 * modulo arithmetic so that they work over sequence number wraps. */

static inline int tid_gt(tid_t x, tid_t y)
{
        int difference = (x - y);
        return (difference > 0);
}

static inline int tid_geq(tid_t x, tid_t y)
{
        int difference = (x - y);
        return (difference >= 0);
}


/*
 * Return the minimum number of blocks which must be free in the journal
 * before a new transaction may be started.  Must be called under j_state_lock.
 */
static inline int jbd_space_needed(journal_t *journal)
{
        int nblocks = journal->j_max_transaction_buffers;
        if (journal->j_committing_transaction)
                nblocks += journal->j_committing_transaction->
                                        t_outstanding_credits;
        return nblocks;
}

/*
 * Definitions which augment the buffer_head layer
 */

/* journaling buffer types */
#define BJ_None         0       /* Not journaled */
#define BJ_SyncData     1       /* Normal data: flush before commit */
#define BJ_Metadata     2       /* Normal journaled metadata */
#define BJ_Forget       3       /* Buffer superseded by this transaction */
#define BJ_IO           4       /* Buffer is for temporary IO use */
#define BJ_Shadow       5       /* Buffer contents being shadowed to the log */
#define BJ_LogCtl       6       /* Buffer contains log descriptors */
#define BJ_Reserved     7       /* Buffer is reserved for access by journal */
#define BJ_Locked       8       /* Locked for I/O during commit */
#define BJ_Types        9
 


#endif  /* CONFIG_JBD || CONFIG_JBD_MODULE */

/*
 * Compatibility no-ops which allow the kernel to compile without CONFIG_JBD
 * go here.
 */

#endif  /* _LINUX_JBD_H */