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/*

 * 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) || !defined(__KERNEL__)

/* Allow this file to be included directly into e2fsprogs */

#ifndef __KERNEL__

#include "jfs_compat.h"

#define JFS_DEBUG

#define jfs_debug jbd_debug

#else

#include <linux/buffer_head.h>

#include <linux/journal-head.h>

#include <linux/stddef.h>

#include <asm/semaphore.h>

#endif

#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

#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

#ifdef __KERNEL__

/**

 * typedef handle_t - The handle_t type represents a single atomic update being performed by some process.

 *

 * All filesystem modifications made by the process go

 * through this handle.  Recursive operations (such as quota operations)

 * are gathered into a single update.

 *

 * The buffer credits field is used to account for journaled buffers

 * being modified by the running process.  To ensure that there is

 * enough log space for all outstanding operations, we need to limit the

 * number of outstanding buffers possible at any time.  When the

 * operation completes, any buffer credits not used are credited back to

 * the transaction, so that at all times we know how many buffers the

 * outstanding updates on a transaction might possibly touch.

 *

 * This is an opaque datatype.

 **/

typedef struct handle_s         handle_t;       /* Atomic operation type */

/**

 * typedef journal_t - The journal_t maintains all of the journaling state information for a single filesystem.

 *

 * journal_t is linked to from the fs superblock structure.

 *

 * We use the journal_t to keep track of all outstanding transaction

 * activity on the filesystem, and to manage the state of the log

 * writing process.

 *

 * This is an opaque datatype.

 **/

typedef struct journal_s        journal_t;      /* Journal control structure */

#endif

/*

 * 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

{

        __u32           h_magic;

        __u32           h_blocktype;

        __u32           h_sequence;

} journal_header_t;

/*

 * The block tag: used to describe a single buffer in the journal

 */

typedef struct journal_block_tag_s

{

        __u32           t_blocknr;      /* The on-disk block number */

        __u32           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;

        int              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 */

        __u32   s_blocksize;            /* journal device blocksize */

        __u32   s_maxlen;               /* total blocks in journal file */

        __u32   s_first;                /* first block of log information */

/* 0x0018 */

        /* Dynamic information describing the current state of the log */

        __u32   s_sequence;             /* first commit ID expected in log */

        __u32   s_start;                /* blocknr of start of log */

/* 0x0020 */

        /* Error value, as set by journal_abort(). */

        __s32   s_errno;

/* 0x0024 */

        /* Remaining fields are only valid in a version-2 superblock */

        __u32   s_feature_compat;       /* compatible feature set */

        __u32   s_feature_incompat;     /* incompatible feature set */

        __u32   s_feature_ro_compat;    /* readonly-compatible feature set */

/* 0x0030 */

        __u8    s_uuid[16];             /* 128-bit uuid for journal */

/* 0x0040 */

        __u32   s_nr_users;             /* Nr of filesystems sharing log */

        __u32   s_dynsuper;             /* Blocknr of dynamic superblock copy*/

/* 0x0048 */

        __u32   s_max_transaction;      /* Limit of journal blocks per trans.*/

        __u32   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

#ifdef __KERNEL__

#include <linux/fs.h>

#include <linux/sched.h>

#include <asm/bug.h>

#define JBD_ASSERTIONS

#ifdef JBD_ASSERTIONS

#define J_ASSERT(assert)                                                \

do {                                                                    \

        if (!(assert)) {                                                \

                printk (KERN_EMERG                                      \

                        "Assertion failure in %s() at %s:%d: \"%s\"\n", \

                        __FUNCTION__, __FILE__, __LINE__, # assert);    \

                BUG();                                                  \

        }                                                               \

} while (0)

#if defined(CONFIG_BUFFER_DEBUG)

void buffer_assertion_failure(struct buffer_head *bh);

#define J_ASSERT_BH(bh, expr)                                           \

        do {                                                            \

                if (!(expr))                                            \

                        buffer_assertion_failure(bh);                   \

                J_ASSERT(expr);                                         \

        } while (0)

#define J_ASSERT_JH(jh, expr)   J_ASSERT_BH(jh2bh(jh), expr)

#else

#define J_ASSERT_BH(bh, expr)   J_ASSERT(expr)

#define J_ASSERT_JH(jh, expr)   J_ASSERT(expr)

#endif

#else

#define J_ASSERT(assert)        do { } while (0)

#endif          /* JBD_ASSERTIONS */

#if defined(JBD_PARANOID_IOFAIL)

#define J_EXPECT(expr, why...)          J_ASSERT(expr)

#define J_EXPECT_BH(bh, expr, why...)   J_ASSERT_BH(bh, expr)

#define J_EXPECT_JH(jh, expr, why...)   J_ASSERT_JH(jh, expr)

#else

#define __journal_expect(expr, why...)                                       \

        do {                                                                 \

                if (!(expr)) {                                               \

                        printk(KERN_ERR                                      \

                                "EXT3-fs unexpected failure: %s;\n",# expr); \

                        printk(KERN_ERR why);                                \

                }                                                            \

        } while (0)

#define J_EXPECT(expr, why...)          __journal_expect(expr, ## why)

#define J_EXPECT_BH(bh, expr, why...)   __journal_expect(expr, ## why)

#define J_EXPECT_JH(jh, expr, why...)   __journal_expect(expr, ## why)

#endif

enum jbd_state_bits {

        BH_JBD                  /* Has an attached ext3 journal_head */

          = BH_PrivateStart,

        BH_JWrite,              /* Being written to log (@@@ DEBUGGING) */

        BH_Freed,               /* Has been freed (truncated) */

        BH_Revoked,             /* Has been revoked from the log */

        BH_RevokeValid,         /* Revoked flag is valid */

        BH_JBDDirty,            /* Is dirty but journaled */

        BH_State,               /* Pins most journal_head state */

        BH_JournalHead,         /* Pins bh->b_private and jh->b_bh */

};

BUFFER_FNS(JBD, jbd)

BUFFER_FNS(JWrite, jwrite)

BUFFER_FNS(JBDDirty, jbddirty)

TAS_BUFFER_FNS(JBDDirty, jbddirty)

BUFFER_FNS(Freed, freed)

static inline struct buffer_head *jh2bh(struct journal_head *jh)

{

        return jh->b_bh;

}

static inline struct journal_head *bh2jh(struct buffer_head *bh)

{

        return bh->b_private;

}

static inline void jbd_lock_bh_state(struct buffer_head *bh)

{

        bit_spin_lock(BH_State, &bh->b_state);

}

static inline int jbd_trylock_bh_state(struct buffer_head *bh)

{

        return bit_spin_trylock(BH_State, &bh->b_state);

}

static inline int jbd_is_locked_bh_state(struct buffer_head *bh)

{

        return bit_spin_is_locked(BH_State, &bh->b_state);

}

static inline void jbd_unlock_bh_state(struct buffer_head *bh)

{

        bit_spin_unlock(BH_State, &bh->b_state);

}

static inline void jbd_lock_bh_journal_head(struct buffer_head *bh)

{

        bit_spin_lock(BH_JournalHead, &bh->b_state);

}

static inline void jbd_unlock_bh_journal_head(struct buffer_head *bh)

{

        bit_spin_unlock(BH_JournalHead, &bh->b_state);

}

#define HAVE_JOURNAL_CALLBACK_STATUS

/**

 *   struct journal_callback - Base structure for callback information.

 *   @jcb_list: list information for other callbacks attached to the same handle.

 *   @jcb_func: Function to call with this callback structure.

 *

 *   This struct is a 'seed' structure for a using with your own callback

 *   structs. If you are using callbacks you must allocate one of these

 *   or another struct of your own definition which has this struct

 *   as it's first element and pass it to journal_callback_set().

 *

 *   This is used internally by jbd to maintain callback information.

 *

 *   See journal_callback_set for more information.

 **/

struct journal_callback {

        struct list_head jcb_list;              /* t_jcb_lock */

        void (*jcb_func)(struct journal_callback *jcb, int error);

        /* user data goes here */

};

struct jbd_revoke_table_s;

/**

 * struct handle_s - The handle_s type is the concrete type associated with

 *     handle_t.

 * @h_transaction: Which compound transaction is this update a part of?

 * @h_buffer_credits: Number of remaining buffers we are allowed to dirty.

 * @h_ref: Reference count on this handle

 * @h_jcb: List of application registered callbacks for this handle.

 * @h_err: Field for caller's use to track errors through large fs operations

 * @h_sync: flag for sync-on-close

 * @h_jdata: flag to force data journaling

 * @h_aborted: flag indicating fatal error on handle

 **/

/* Docbook can't yet cope with the bit fields, but will leave the documentation

 * in so it can be fixed later.

 */

struct handle_s

{

        /* Which compound transaction is this update a part of? */

        transaction_t           *h_transaction;

        /* Number of remaining buffers we are allowed to dirty: */

        int                     h_buffer_credits;

        /* Reference count on this handle */

        int                     h_ref;

        /* Field for caller's use to track errors through large fs */

        /* operations */

        int                     h_err;

        /*

         * List of application registered callbacks for this handle. The

         * function(s) will be called after the transaction that this handle is

         * part of has been committed to disk. [t_jcb_lock]

         */

        struct list_head        h_jcb;

        /* Flags [no locking] */

        unsigned int    h_sync:         1;      /* sync-on-close */

        unsigned int    h_jdata:        1;      /* force data journaling */

        unsigned int    h_aborted:      1;      /* fatal error on handle */

};

/* The transaction_t type is the guts of the journaling mechanism.  It

 * tracks a compound transaction through its various states:

 *

 * RUNNING:     accepting new updates

 * LOCKED:      Updates still running but we don't accept new ones

 * RUNDOWN:     Updates are tidying up but have finished requesting

 *              new buffers to modify (state not used for now)

 * FLUSH:       All updates complete, but we are still writing to disk

 * COMMIT:      All data on disk, writing commit record

 * FINISHED:    We still have to keep the transaction for checkpointing.

 *

 * The transaction keeps track of all of the buffers modified by a

 * running transaction, and all of the buffers committed but not yet

 * flushed to home for finished transactions.

 */

/*

 * Lock ranking:

 *

 *    j_list_lock

 *      ->jbd_lock_bh_journal_head()    (This is "innermost")

 *

 *    j_state_lock

 *    ->jbd_lock_bh_state()

 *

 *    jbd_lock_bh_state()

 *    ->j_list_lock

 *

 *    j_state_lock

 *    ->t_handle_lock

 *

 *    j_state_lock

 *    ->j_list_lock                     (journal_unmap_buffer)

 *

 *    t_handle_lock

 *    ->t_jcb_lock

 */

struct transaction_s

{

        /* Pointer to the journal for this transaction. [no locking] */

        journal_t               *t_journal;

        /* Sequence number for this transaction [no locking] */

        tid_t                   t_tid;

        /*

         * Transaction's current state

         * [no locking - only kjournald alters this]

         * FIXME: needs barriers

         * KLUDGE: [use j_state_lock]

         */

        enum {

                T_RUNNING,

                T_LOCKED,

                T_RUNDOWN,

                T_FLUSH,

                T_COMMIT,

                T_FINISHED

        }                       t_state;

        /*

         * Where in the log does this transaction's commit start? [no locking]

         */

        unsigned long           t_log_start;

        /* Number of buffers on the t_buffers list [j_list_lock] */

        int                     t_nr_buffers;

        /*

         * Doubly-linked circular list of all buffers reserved but not yet

         * modified by this transaction [j_list_lock]

         */

        struct journal_head     *t_reserved_list;

        /*

         * Doubly-linked circular list of all metadata buffers owned by this

         * transaction [j_list_lock]

         */

        struct journal_head     *t_buffers;

        /*

         * Doubly-linked circular list of all data buffers still to be

         * flushed before this transaction can be committed [j_list_lock]

         */

        struct journal_head     *t_sync_datalist;

        /*

         * Doubly-linked circular list of all forget buffers (superseded

         * buffers which we can un-checkpoint once this transaction commits)

         * [j_list_lock]

         */

        struct journal_head     *t_forget;

        /*

         * Doubly-linked circular list of all buffers still to be flushed before

         * this transaction can be checkpointed. [j_list_lock]

         */

        struct journal_head     *t_checkpoint_list;

        /*

         * Doubly-linked circular list of temporary buffers currently undergoing

         * IO in the log [j_list_lock]

         */

        struct journal_head     *t_iobuf_list;

        /*

         * Doubly-linked circular list of metadata buffers being shadowed by log

         * IO.  The IO buffers on the iobuf list and the shadow buffers on this

         * list match each other one for one at all times. [j_list_lock]

         */

        struct journal_head     *t_shadow_list;

        /*

         * Doubly-linked circular list of control buffers being written to the

         * log. [j_list_lock]

         */

        struct journal_head     *t_log_list;

        /*

         * Protects info related to handles

         */

        spinlock_t              t_handle_lock;

        /*

         * Number of outstanding updates running on this transaction

         * [t_handle_lock]

         */

        int                     t_updates;

        /*

         * Number of buffers reserved for use by all handles in this transaction

         * handle but not yet modified. [t_handle_lock]

         */

        int                     t_outstanding_credits;

        /*

         * Forward and backward links for the circular list of all transactions

         * awaiting checkpoint. [j_list_lock]

         */

        transaction_t           *t_cpnext, *t_cpprev;

        /*

         * When will the transaction expire (become due for commit), in jiffies?

         * [no locking]

         */

        unsigned long           t_expires;

        /*

         * How many handles used this transaction? [t_handle_lock]

         */

        int t_handle_count;

        /*

         * Protects the callback list

         */

        spinlock_t              t_jcb_lock;

        /*

         * List of registered callback functions for this transaction.

         * Called when the transaction is committed. [t_jcb_lock]

         */

        struct list_head        t_jcb;

};

/**

 * struct journal_s - The journal_s type is the concrete type associated with

 *     journal_t.

 * @j_flags:  General journaling state flags

 * @j_errno:  Is there an outstanding uncleared error on the journal (from a

 *     prior abort)?

 * @j_sb_buffer: First part of superblock buffer

 * @j_superblock: Second part of superblock buffer

 * @j_format_version: Version of the superblock format

 * @j_barrier_count:  Number of processes waiting to create a barrier lock

 * @j_barrier: The barrier lock itself

 * @j_running_transaction: The current running transaction..

 * @j_committing_transaction: the transaction we are pushing to disk

 * @j_checkpoint_transactions: a linked circular list of all transactions

 *  waiting for checkpointing

 * @j_wait_transaction_locked: Wait queue for waiting for a locked transaction

 *  to start committing, or for a barrier lock to be released

 * @j_wait_logspace: Wait queue for waiting for checkpointing to complete

 * @j_wait_done_commit: Wait queue for waiting for commit to complete

 * @j_wait_checkpoint:  Wait queue to trigger checkpointing

 * @j_wait_commit: Wait queue to trigger commit

 * @j_wait_updates: Wait queue to wait for updates to complete

 * @j_checkpoint_sem: Semaphore for locking against concurrent checkpoints

 * @j_head: Journal head - identifies the first unused block in the journal

 * @j_tail: Journal tail - identifies the oldest still-used block in the

 *  journal.

 * @j_free: Journal free - how many free blocks are there in the journal?

 * @j_first: The block number of the first usable block

 * @j_last: The block number one beyond the last usable block

 * @j_dev: Device where we store the journal

 * @j_blocksize: blocksize for the location where we store the journal.

 * @j_blk_offset: starting block offset for into the device where we store the

 *     journal

 * @j_fs_dev: Device which holds the client fs.  For internal journal this will

 *     be equal to j_dev

 * @j_maxlen: Total maximum capacity of the journal region on disk.

 * @j_inode: Optional inode where we store the journal.  If present, all journal

 *     block numbers are mapped into this inode via bmap().

 * @j_tail_sequence:  Sequence number of the oldest transaction in the log

 * @j_transaction_sequence: Sequence number of the next transaction to grant

 * @j_commit_sequence: Sequence number of the most recently committed

 *  transaction

 * @j_commit_request: Sequence number of the most recent transaction wanting

 *     commit

 * @j_uuid: Uuid of client object.

 * @j_task: Pointer to the current commit thread for this journal

 * @j_max_transaction_buffers:  Maximum number of metadata buffers to allow in a

 *     single compound commit transaction

 * @j_commit_interval: What is the maximum transaction lifetime before we begin

 *  a commit?

 * @j_commit_timer:  The timer used to wakeup the commit thread

 * @j_revoke: The revoke table - maintains the list of revoked blocks in the

 *     current transaction.

 */

struct journal_s

{

        /* General journaling state flags [j_state_lock] */

        unsigned long           j_flags;

        /*

         * Is there an outstanding uncleared error on the journal (from a prior

         * abort)? [j_state_lock]

         */

        int                     j_errno;

        /* The superblock buffer */

        struct buffer_head      *j_sb_buffer;

        journal_superblock_t    *j_superblock;

        /* Version of the superblock format */

        int                     j_format_version;

        /*

         * Protect the various scalars in the journal

         */

        spinlock_t              j_state_lock;

        /*

         * Number of processes waiting to create a barrier lock [j_state_lock]

         */

        int                     j_barrier_count;

        /* The barrier lock itself */

        struct semaphore        j_barrier;

        /*

         * Transactions: The current running transaction...

         * [j_state_lock] [caller holding open handle]

         */

        transaction_t           *j_running_transaction;

        /*

         * the transaction we are pushing to disk

         * [j_state_lock] [caller holding open handle]

         */

        transaction_t           *j_committing_transaction;

        /*

         * ... and a linked circular list of all transactions waiting for

         * checkpointing. [j_list_lock]

         */

        transaction_t           *j_checkpoint_transactions;

        /*

         * Wait queue for waiting for a locked transaction to start committing,

         * or for a barrier lock to be released

         */

        wait_queue_head_t       j_wait_transaction_locked;

        /* Wait queue for waiting for checkpointing to complete */

        wait_queue_head_t       j_wait_logspace;

        /* Wait queue for waiting for commit to complete */

        wait_queue_head_t       j_wait_done_commit;

        /* Wait queue to trigger checkpointing */

        wait_queue_head_t       j_wait_checkpoint;

        /* Wait queue to trigger commit */

        wait_queue_head_t       j_wait_commit;

        /* Wait queue to wait for updates to complete */

        wait_queue_head_t       j_wait_updates;

        /* Semaphore for locking against concurrent checkpoints */

        struct semaphore        j_checkpoint_sem;

        /*

         * Journal head: identifies the first unused block in the journal.

         * [j_state_lock]

         */

        unsigned long           j_head;

        /*

         * Journal tail: identifies the oldest still-used block in the journal.

         * [j_state_lock]

         */

        unsigned long           j_tail;

        /*

         * Journal free: how many free blocks are there in the journal?

         * [j_state_lock]

         */

        unsigned long           j_free;

        /*

         * Journal start and end: the block numbers of the first usable block

         * and one beyond the last usable block in the journal. [j_state_lock]

         */

        unsigned long           j_first;

        unsigned long           j_last;

        /*

         * Device, blocksize and starting block offset for the location where we

         * store the journal.

         */

        struct block_device     *j_dev;

        int                     j_blocksize;

        unsigned int            j_blk_offset;

        /*

         * Device which holds the client fs.  For internal journal this will be

         * equal to j_dev.

         */

        struct block_device     *j_fs_dev;

        /* Total maximum capacity of the journal region on disk. */

        unsigned int            j_maxlen;

        /*

         * Protects the buffer lists and internal buffer state.

         */

        spinlock_t              j_list_lock;

        /* Optional inode where we store the journal.  If present, all */

        /* journal block numbers are mapped into this inode via */

        /* bmap(). */

        struct inode            *j_inode;

        /*

         * Sequence number of the oldest transaction in the log [j_state_lock]

         */

        tid_t                   j_tail_sequence;

        /*

         * Sequence number of the next transaction to grant [j_state_lock]

         */

        tid_t                   j_transaction_sequence;

        /*

         * Sequence number of the most recently committed transaction

         * [j_state_lock].

         */

        tid_t                   j_commit_sequence;

        /*

         * Sequence number of the most recent transaction wanting commit

         * [j_state_lock]

         */

        tid_t                   j_commit_request;

        /*

         * Journal uuid: identifies the object (filesystem, LVM volume etc)

         * backed by this journal.  This will eventually be replaced by an array

         * of uuids, allowing us to index multiple devices within a single

         * journal and to perform atomic updates across them.

         */

        __u8                    j_uuid[16];

        /* Pointer to the current commit thread for this journal */

        struct task_struct      *j_task;

        /*

         * Maximum number of metadata buffers to allow in a single compound

         * commit transaction

         */

        int                     j_max_transaction_buffers;

        /*

         * What is the maximum transaction lifetime before we begin a commit?

         */

        unsigned long           j_commit_interval;

        /* The timer used to wakeup the commit thread: */

        struct timer_list       *j_commit_timer;

        /*

         * The revoke table: maintains the list of revoked blocks in the

         * current transaction.  [j_revoke_lock]

         */

        spinlock_t              j_revoke_lock;

        struct jbd_revoke_table_s *j_revoke;

        struct jbd_revoke_table_s *j_revoke_table[2];

        /*

         * An opaque pointer to fs-private information.  ext3 puts its

         * superblock pointer here

         */

        void *j_private;

};

/*

 * Journal flag definitions

 */

#define JFS_UNMOUNT     0x001   /* Journal thread is being destroyed */

#define JFS_ABORT       0x002   /* Journaling has been aborted for errors. */

#define JFS_ACK_ERR     0x004   /* The errno in the sb has been acked */

#define JFS_FLUSHED     0x008   /* The journal superblock has been flushed */

#define JFS_LOADED      0x010   /* The journal superblock has been loaded */

/*

 * Function declarations for the journaling transaction and buffer

 * management

 */

/* Filing buffers */

extern void journal_unfile_buffer(journal_t *, struct journal_head *);

extern void __journal_unfile_buffer(struct journal_head *);

extern void __journal_refile_buffer(struct journal_head *);

extern void journal_refile_buffer(journal_t *, struct journal_head *);

extern void __journal_file_buffer(struct journal_head *, transaction_t *, int);

extern void __journal_free_buffer(struct journal_head *bh);

extern void journal_file_buffer(struct journal_head *, transaction_t *, int);

extern void __journal_clean_data_list(transaction_t *transaction);

/* Log buffer allocation */

extern struct journal_head * journal_get_descriptor_buffer(journal_t *);

int journal_next_log_block(journal_t *, unsigned long *);

/* Commit management */

extern void journal_commit_transaction(journal_t *);

/* Checkpoint list management */

int __journal_clean_checkpoint_list(journal_t *journal);

void __journal_remove_checkpoint(struct journal_head *);

void __journal_insert_checkpoint(struct journal_head *, transaction_t *);

/* Buffer IO */

extern int

journal_write_metadata_buffer(transaction_t       *transaction,

                              struct journal_head  *jh_in,

                              struct journal_head **jh_out,

                              int                  blocknr);

/* Transaction locking */

extern void             __wait_on_journal (journal_t *);

/*

 * Journal locking.

 *

 * We need to lock the journal during transaction state changes so that nobody

 * ever tries to take a handle on the running transaction while we are in the

 * middle of moving it to the commit phase.  j_state_lock does this.

 *

 * Note that the locking is completely interrupt unsafe.  We never touch

 * journal structures from interrupts.

 */

static inline handle_t *journal_current_handle(void)

{

        return current->journal_info;

}

/* The journaling code user interface:

 *

 * Create and destroy handles

 * Register buffer modifications against the current transaction.

 */

extern handle_t *journal_start(journal_t *, int nblocks);

extern int       journal_restart (handle_t *, int nblocks);

extern int       journal_extend (handle_t *, int nblocks);

extern int       journal_get_write_access(handle_t *, struct buffer_head *,

                                                int *credits);

extern int       journal_get_create_access (handle_t *, struct buffer_head *);

extern int       journal_get_undo_access(handle_t *, struct buffer_head *,

                                                int *credits);

extern int       journal_dirty_data (handle_t *, struct buffer_head *);

extern int       journal_dirty_metadata (handle_t *, struct buffer_head *);

extern void      journal_release_buffer (handle_t *, struct buffer_head *,

                                                int credits);

extern void      journal_forget (handle_t *, struct buffer_head *);

extern void      journal_sync_buffer (struct buffer_head *);

extern int       journal_invalidatepage(journal_t *,

                                struct page *, unsigned long);

extern int       journal_try_to_free_buffers(journal_t *, struct page *, int);

extern int       journal_stop(handle_t *);

extern int       journal_flush (journal_t *);

extern void      journal_callback_set(handle_t *handle,

                                      void (*fn)(struct journal_callback *,int),

                                      struct journal_callback *jcb);

extern void      journal_lock_updates (journal_t *);

extern void      journal_unlock_updates (journal_t *);

extern journal_t * journal_init_dev(struct block_device *bdev,

                                struct block_device *fs_dev,

                                int start, int len, int bsize);

extern journal_t * journal_init_inode (struct inode *);

extern int         journal_update_format (journal_t *);

extern int         journal_check_used_features

                   (journal_t *, unsigned long, unsigned long, unsigned long);

extern int         journal_check_available_features

                   (journal_t *, unsigned long, unsigned long, unsigned long);

extern int         journal_set_features

                   (journal_t *, unsigned long, unsigned long, unsigned long);

extern int         journal_create     (journal_t *);

extern int         journal_load       (journal_t *journal);

extern void        journal_destroy    (journal_t *);

extern int         journal_recover    (journal_t *journal);

extern int         journal_wipe       (journal_t *, int);

extern int         journal_skip_recovery        (journal_t *);

extern void        journal_update_superblock    (journal_t *, int);

extern void        __journal_abort_hard (journal_t *);

extern void        __journal_abort_soft (journal_t *, int);