/*
   * 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

  /* 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/types.h>

  #include <linux/buffer_head.h>
  #include <linux/journal-head.h>
  #include <linux/stddef.h>

  #include <linux/bit_spinlock.h>

  #include <linux/mutex.h>

  #include <linux/timer.h>

  #include <linux/lockdep.h>

  #include <linux/slab.h>

  #define journal_oom_retry 1
  
  /*

   * Define JBD_PARANOID_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 u8 journal_enable_debug;

  
  #define jbd_debug(n, f, a...)						\
  	do {								\
  		if ((n) <= journal_enable_debug) {			\
  			printk (KERN_DEBUG "(%s, %d): %s: ",		\

  				__FILE__, __LINE__, __func__);	\

  			printk (f, ## a);				\

  		}							\
  	} while (0)
  #else
  #define jbd_debug(f, a...)	/**/
  #endif

  static inline void *jbd_alloc(size_t size, gfp_t flags)
  {
  	return (void *)__get_free_pages(flags, get_order(size));
  }
  
  static inline void jbd_free(void *ptr, size_t size)
  {
  	free_pages((unsigned long)ptr, get_order(size));
  };

  #define JFS_MIN_JOURNAL_BLOCKS 1024

  
  /**
   * 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
  {
  	__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
  
  #ifdef __KERNEL__
  
  #include <linux/fs.h>
  #include <linux/sched.h>

  #include <linux/jbd_common.h>

  #define J_ASSERT(assert)	BUG_ON(!(assert))

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

  #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...)					     \
  	({								     \
  		int val = (expr);					     \
  		if (!val) {						     \
  			printk(KERN_ERR					     \
  				"EXT3-fs unexpected failure: %s;
  ",# expr); \
  			printk(KERN_ERR why "
  ");			     \
  		}							     \
  		val;							     \
  	})
  #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

  struct jbd_revoke_table_s;
  
  /**

   * struct handle_s - this 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_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

   * @h_lockdep_map: lockdep info for debugging lock problems

   */

  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;
  
  	/* 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 */

  
  #ifdef CONFIG_DEBUG_LOCK_ALLOC
  	struct lockdep_map	h_lockdep_map;
  #endif

  };
  
  
  /* 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)
   *
   */

  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]

  	 * [j_list_lock] guards transition of a transaction into T_FINISHED
  	 * state and subsequent call of __journal_drop_transaction()

  	 * FIXME: needs barriers
  	 * KLUDGE: [use j_state_lock]
  	 */
  	enum {
  		T_RUNNING,
  		T_LOCKED,

  		T_FLUSH,
  		T_COMMIT,

  		T_COMMIT_RECORD,

  		T_FINISHED

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

  	unsigned int		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 buffers under writeout during
  	 * commit [j_list_lock]
  	 */
  	struct journal_head	*t_locked_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 all buffers submitted for IO while
  	 * checkpointing. [j_list_lock]
  	 */
  	struct journal_head	*t_checkpoint_io_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;
  
  	/*

  	 * When this transaction started, in nanoseconds [no locking]
  	 */
  	ktime_t			t_start_time;
  
  	/*

  	 * How many handles used this transaction? [t_handle_lock]
  	 */
  	int t_handle_count;

  	/*
  	 * This transaction is being forced and some process is
  	 * waiting for it to finish.
  	 */

  	unsigned int t_synchronous_commit:1;

  };
  
  /**

   * struct journal_s - this 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_state_lock: Protect the various scalars in the journal
   * @j_barrier_count:  Number of processes waiting to create a barrier lock

   * @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_mutex: Mutex 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_list_lock: Protects the buffer lists and internal buffer state.
   * @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_lock: Protect the revoke table
   * @j_revoke: The revoke table - maintains the list of revoked blocks in the
   *     current transaction.
   * @j_revoke_table: alternate revoke tables for j_revoke

   * @j_wbuf: array of buffer_heads for journal_commit_transaction
   * @j_wbufsize: maximum number of buffer_heads allowed in j_wbuf, the
   *	number that will fit in j_blocksize

   * @j_last_sync_writer: most recent pid which did a synchronous write

   * @j_average_commit_time: the average amount of time in nanoseconds it
   *	takes to commit a transaction to the disk.

   * @j_private: An opaque pointer to fs-private information.
   */
  
  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;

  	/*
  	 * 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 mutex		j_checkpoint_mutex;

  
  	/*
  	 * Journal head: identifies the first unused block in the journal.
  	 * [j_state_lock]
  	 */

  	unsigned int		j_head;

  
  	/*
  	 * Journal tail: identifies the oldest still-used block in the journal.
  	 * [j_state_lock]
  	 */

  	unsigned int		j_tail;

  
  	/*
  	 * Journal free: how many free blocks are there in the journal?
  	 * [j_state_lock]
  	 */

  	unsigned int		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 int		j_first;
  	unsigned int		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];
  
  	/*
  	 * array of bhs for journal_commit_transaction
  	 */
  	struct buffer_head	**j_wbuf;
  	int			j_wbufsize;

  	/*
  	 * this is the pid of the last person to run a synchronous operation
  	 * through the journal.
  	 */

  	pid_t			j_last_sync_writer;

  	/*

  	 * the average amount of time in nanoseconds it takes to commit a
  	 * transaction to the disk.  [j_state_lock]
  	 */
  	u64			j_average_commit_time;
  
  	/*

  	 * 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 */
  #define JFS_BARRIER	0x020	/* Use IDE barriers */

  #define JFS_ABORT_ON_SYNCDATA_ERR	0x040  /* Abort the journal on file
  						* data write error in ordered
  						* mode */

  /*

   * 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 int *);

  
  /* Commit management */
  extern void journal_commit_transaction(journal_t *);
  
  /* Checkpoint list management */
  int __journal_clean_checkpoint_list(journal_t *journal);

  int __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,

  			      unsigned 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 *);
  extern int	 journal_get_create_access (handle_t *, struct buffer_head *);
  extern int	 journal_get_undo_access(handle_t *, struct buffer_head *);
  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 *);
  extern int	 journal_forget (handle_t *, struct buffer_head *);
  extern void	 journal_sync_buffer (struct buffer_head *);

  extern void	 journal_invalidatepage(journal_t *,

  				struct page *, unsigned long);

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

  extern int	 journal_stop(handle_t *);
  extern int	 journal_flush (journal_t *);
  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 int	   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      (journal_t *, int);
  extern int	   journal_errno      (journal_t *);
  extern void	   journal_ack_err    (journal_t *);
  extern int	   journal_clear_err  (journal_t *);

  extern int	   journal_bmap(journal_t *, unsigned int, unsigned int *);

  extern int	   journal_force_commit(journal_t *);
  
  /*
   * journal_head management
   */
  struct journal_head *journal_add_journal_head(struct buffer_head *bh);
  struct journal_head *journal_grab_journal_head(struct buffer_head *bh);

  void journal_put_journal_head(struct journal_head *jh);
  
  /*
   * handle management
   */

  extern struct kmem_cache *jbd_handle_cache;

  static inline handle_t *jbd_alloc_handle(gfp_t gfp_flags)

  {
  	return kmem_cache_alloc(jbd_handle_cache, gfp_flags);
  }
  
  static inline void jbd_free_handle(handle_t *handle)
  {
  	kmem_cache_free(jbd_handle_cache, handle);
  }
  
  /* Primary revoke support */
  #define JOURNAL_REVOKE_DEFAULT_HASH 256
  extern int	   journal_init_revoke(journal_t *, int);
  extern void	   journal_destroy_revoke_caches(void);
  extern int	   journal_init_revoke_caches(void);
  
  extern void	   journal_destroy_revoke(journal_t *);
  extern int	   journal_revoke (handle_t *,

  				unsigned int, struct buffer_head *);

  extern int	   journal_cancel_revoke(handle_t *, struct journal_head *);

  extern void	   journal_write_revoke_records(journal_t *,
  						transaction_t *, int);

  
  /* Recovery revoke support */

  extern int	journal_set_revoke(journal_t *, unsigned int, tid_t);
  extern int	journal_test_revoke(journal_t *, unsigned int, tid_t);

  extern void	journal_clear_revoke(journal_t *);

  extern void	journal_switch_revoke_table(journal_t *journal);

  extern void	journal_clear_buffer_revoked_flags(journal_t *journal);

  
  /*
   * The log thread user interface:
   *
   * Request space in the current transaction, and force transaction commit
   * transitions on demand.
   */
  
  int __log_space_left(journal_t *); /* Called with journal locked */
  int log_start_commit(journal_t *journal, tid_t tid);
  int __log_start_commit(journal_t *journal, tid_t tid);
  int journal_start_commit(journal_t *journal, tid_t *tid);
  int journal_force_commit_nested(journal_t *journal);
  int log_wait_commit(journal_t *journal, tid_t tid);
  int log_do_checkpoint(journal_t *journal);

  int journal_trans_will_send_data_barrier(journal_t *journal, tid_t tid);

  
  void __log_wait_for_space(journal_t *journal);
  extern void	__journal_drop_transaction(journal_t *, transaction_t *);
  extern int	cleanup_journal_tail(journal_t *);
  
  /* Debugging code only: */
  
  #define jbd_ENOSYS() \
  do {								           \

  	printk (KERN_ERR "JBD unimplemented function %s
  ", __func__); \

  	current->state = TASK_UNINTERRUPTIBLE;			           \
  	schedule();						           \
  } while (1)
  
  /*
   * is_journal_abort
   *
   * Simple test wrapper function to test the JFS_ABORT state flag.  This
   * bit, when set, indicates that we have had a fatal error somewhere,
   * either inside the journaling layer or indicated to us by the client
   * (eg. ext3), and that we and should not commit any further

   * transactions.

   */
  
  static inline int is_journal_aborted(journal_t *journal)
  {
  	return journal->j_flags & JFS_ABORT;
  }
  
  static inline int is_handle_aborted(handle_t *handle)
  {
  	if (handle->h_aborted)
  		return 1;
  	return is_journal_aborted(handle->h_transaction->t_journal);
  }
  
  static inline void journal_abort_handle(handle_t *handle)
  {
  	handle->h_aborted = 1;
  }
  
  #endif /* __KERNEL__   */
  
  /* 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);
  }
  
  extern int journal_blocks_per_page(struct inode *inode);
  
  /*
   * 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

  extern int jbd_blocks_per_page(struct inode *inode);
  
  #ifdef __KERNEL__
  
  #define buffer_trace_init(bh)	do {} while (0)
  #define print_buffer_fields(bh)	do {} while (0)
  #define print_buffer_trace(bh)	do {} while (0)
  #define BUFFER_TRACE(bh, info)	do {} while (0)
  #define BUFFER_TRACE2(bh, bh2, info)	do {} while (0)
  #define JBUFFER_TRACE(jh, info)	do {} while (0)
  
  #endif	/* __KERNEL__ */

  #endif	/* _LINUX_JBD_H */