dirty fix to merging

1 files changed, 1282 insertions, 0 deletions

diff --git a/include/linux/jbd2.h b/include/linux/jbd2.h
new file mode 100644
index 00000000..912c30a8
--- /dev/null
+++ b/include/linux/jbd2.h
@@ -0,0 +1,1282 @@
+/*
+ * linux/include/linux/jbd2.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_JBD2_H
+#define _LINUX_JBD2_H
+
+/* Allow this file to be included directly into e2fsprogs */
+#ifndef __KERNEL__
+#include "jfs_compat.h"
+#define JBD2_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/slab.h>
+#endif
+
+#define journal_oom_retry 1
+
+/*
+ * Define JBD2_PARANIOD_IOFAIL to cause a kernel BUG() if ext4 finds
+ * certain classes of error which can occur due to failed IOs.  Under
+ * normal use we want ext4 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 JBD2_PARANOID_IOFAIL
+
+/*
+ * The default maximum commit age, in seconds.
+ */
+#define JBD2_DEFAULT_MAX_COMMIT_AGE 5
+
+#ifdef CONFIG_JBD2_DEBUG
+/*
+ * Define JBD2_EXPENSIVE_CHECKING to enable more expensive internal
+ * consistency checks.  By default we don't do this unless
+ * CONFIG_JBD2_DEBUG is on.
+ */
+#define JBD2_EXPENSIVE_CHECKING
+extern u8 jbd2_journal_enable_debug;
+
+#define jbd_debug(n, f, a...)						\
+	do {								\
+		if ((n) <= jbd2_journal_enable_debug) {			\
+			printk (KERN_DEBUG "(%s, %d): %s: ",		\
+				__FILE__, __LINE__, __func__);	\
+			printk (f, ## a);				\
+		}							\
+	} while (0)
+#else
+#define jbd_debug(f, a...)	/**/
+#endif
+
+extern void *jbd2_alloc(size_t size, gfp_t flags);
+extern void jbd2_free(void *ptr, size_t size);
+
+#define JBD2_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 jbd2_journal_handle 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 JBD2_MAGIC_NUMBER 0xc03b3998U /* The first 4 bytes of /dev/random! */
+
+/*
+ * On-disk structures
+ */
+
+/*
+ * Descriptor block types:
+ */
+
+#define JBD2_DESCRIPTOR_BLOCK	1
+#define JBD2_COMMIT_BLOCK	2
+#define JBD2_SUPERBLOCK_V1	3
+#define JBD2_SUPERBLOCK_V2	4
+#define JBD2_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;
+
+/*
+ * Checksum types.
+ */
+#define JBD2_CRC32_CHKSUM   1
+#define JBD2_MD5_CHKSUM     2
+#define JBD2_SHA1_CHKSUM    3
+
+#define JBD2_CRC32_CHKSUM_SIZE 4
+
+#define JBD2_CHECKSUM_BYTES (32 / sizeof(u32))
+/*
+ * Commit block header for storing transactional checksums:
+ */
+struct commit_header {
+	__be32		h_magic;
+	__be32          h_blocktype;
+	__be32          h_sequence;
+	unsigned char   h_chksum_type;
+	unsigned char   h_chksum_size;
+	unsigned char 	h_padding[2];
+	__be32 		h_chksum[JBD2_CHECKSUM_BYTES];
+	__be64		h_commit_sec;
+	__be32		h_commit_nsec;
+};
+
+/*
+ * The block tag: used to describe a single buffer in the journal.
+ * t_blocknr_high is only used if INCOMPAT_64BIT is set, so this
+ * raw struct shouldn't be used for pointer math or sizeof() - use
+ * journal_tag_bytes(journal) instead to compute this.
+ */
+typedef struct journal_block_tag_s
+{
+	__be32		t_blocknr;	/* The on-disk block number */
+	__be32		t_flags;	/* See below */
+	__be32		t_blocknr_high; /* most-significant high 32bits. */
+} journal_block_tag_t;
+
+#define JBD2_TAG_SIZE32 (offsetof(journal_block_tag_t, t_blocknr_high))
+#define JBD2_TAG_SIZE64 (sizeof(journal_block_tag_t))
+
+/*
+ * The revoke descriptor: used on disk to describe a series of blocks to
+ * be revoked from the log
+ */
+typedef struct jbd2_journal_revoke_header_s
+{
+	journal_header_t r_header;
+	__be32		 r_count;	/* Count of bytes used in the block */
+} jbd2_journal_revoke_header_t;
+
+
+/* Definitions for the journal tag flags word: */
+#define JBD2_FLAG_ESCAPE		1	/* on-disk block is escaped */
+#define JBD2_FLAG_SAME_UUID	2	/* block has same uuid as previous */
+#define JBD2_FLAG_DELETED	4	/* block deleted by this transaction */
+#define JBD2_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 jbd2_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 JBD2_HAS_COMPAT_FEATURE(j,mask)					\
+	((j)->j_format_version >= 2 &&					\
+	 ((j)->j_superblock->s_feature_compat & cpu_to_be32((mask))))
+#define JBD2_HAS_RO_COMPAT_FEATURE(j,mask)				\
+	((j)->j_format_version >= 2 &&					\
+	 ((j)->j_superblock->s_feature_ro_compat & cpu_to_be32((mask))))
+#define JBD2_HAS_INCOMPAT_FEATURE(j,mask)				\
+	((j)->j_format_version >= 2 &&					\
+	 ((j)->j_superblock->s_feature_incompat & cpu_to_be32((mask))))
+
+#define JBD2_FEATURE_COMPAT_CHECKSUM	0x00000001
+
+#define JBD2_FEATURE_INCOMPAT_REVOKE		0x00000001
+#define JBD2_FEATURE_INCOMPAT_64BIT		0x00000002
+#define JBD2_FEATURE_INCOMPAT_ASYNC_COMMIT	0x00000004
+
+/* Features known to this kernel version: */
+#define JBD2_KNOWN_COMPAT_FEATURES	JBD2_FEATURE_COMPAT_CHECKSUM
+#define JBD2_KNOWN_ROCOMPAT_FEATURES	0
+#define JBD2_KNOWN_INCOMPAT_FEATURES	(JBD2_FEATURE_INCOMPAT_REVOKE | \
+					JBD2_FEATURE_INCOMPAT_64BIT | \
+					JBD2_FEATURE_INCOMPAT_ASYNC_COMMIT)
+
+#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(JBD2_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					     \
+			       "JBD2 unexpected failure: %s: %s;\n",	     \
+			       __func__, #expr);			     \
+			printk(KERN_ERR why "\n");			     \
+		}							     \
+		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
+
+/* Flags in jbd_inode->i_flags */
+#define __JI_COMMIT_RUNNING 0
+/* Commit of the inode data in progress. We use this flag to protect us from
+ * concurrent deletion of inode. We cannot use reference to inode for this
+ * since we cannot afford doing last iput() on behalf of kjournald
+ */
+#define JI_COMMIT_RUNNING (1 << __JI_COMMIT_RUNNING)
+
+/**
+ * struct jbd_inode is the structure linking inodes in ordered mode
+ *   present in a transaction so that we can sync them during commit.
+ */
+struct jbd2_inode {
+	/* Which transaction does this inode belong to? Either the running
+	 * transaction or the committing one. [j_list_lock] */
+	transaction_t *i_transaction;
+
+	/* Pointer to the running transaction modifying inode's data in case
+	 * there is already a committing transaction touching it. [j_list_lock] */
+	transaction_t *i_next_transaction;
+
+	/* List of inodes in the i_transaction [j_list_lock] */
+	struct list_head i_list;
+
+	/* VFS inode this inode belongs to [constant during the lifetime
+	 * of the structure] */
+	struct inode *i_vfs_inode;
+
+	/* Flags of inode [j_list_lock] */
+	unsigned long i_flags;
+};
+
+struct jbd2_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_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 jbd2_journal_handle
+{
+	/* 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 */
+	unsigned int	h_cowing:1;	/* COWing block to snapshot */
+
+	/* Number of buffers requested by user:
+	 * (before adding the COW credits factor) */
+	unsigned int	h_base_credits:14;
+
+	/* Number of buffers the user is allowed to dirty:
+	 * (counts only buffers dirtied when !h_cowing) */
+	unsigned int	h_user_credits:14;
+
+
+#ifdef CONFIG_DEBUG_LOCK_ALLOC
+	struct lockdep_map	h_lockdep_map;
+#endif
+
+#ifdef CONFIG_JBD2_DEBUG
+	/* COW debugging counters: */
+	unsigned int h_cow_moved; /* blocks moved to snapshot */
+	unsigned int h_cow_copied; /* blocks copied to snapshot */
+	unsigned int h_cow_ok_jh; /* blocks already COWed during current
+				     transaction */
+	unsigned int h_cow_ok_bitmap; /* blocks not set in COW bitmap */
+	unsigned int h_cow_ok_mapped;/* blocks already mapped in snapshot */
+	unsigned int h_cow_bitmaps; /* COW bitmaps created */
+	unsigned int h_cow_excluded; /* blocks set in exclude bitmap */
+#endif
+};
+
+
+/*
+ * Some stats for checkpoint phase
+ */
+struct transaction_chp_stats_s {
+	unsigned long		cs_chp_time;
+	__u32			cs_forced_to_close;
+	__u32			cs_written;
+	__u32			cs_dropped;
+};
+
+/* 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 kjournald2 alters this]
+	 * [j_list_lock] guards transition of a transaction into T_FINISHED
+	 * state and subsequent call of __jbd2_journal_drop_transaction()
+	 * FIXME: needs barriers
+	 * KLUDGE: [use j_state_lock]
+	 */
+	enum {
+		T_RUNNING,
+		T_LOCKED,
+		T_FLUSH,
+		T_COMMIT,
+		T_COMMIT_DFLUSH,
+		T_COMMIT_JFLUSH,
+		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 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;
+
+	/*
+	 * List of inodes whose data we've modified in data=ordered mode.
+	 * [j_list_lock]
+	 */
+	struct list_head	t_inode_list;
+
+	/*
+	 * Protects info related to handles
+	 */
+	spinlock_t		t_handle_lock;
+
+	/*
+	 * Longest time some handle had to wait for running transaction
+	 */
+	unsigned long		t_max_wait;
+
+	/*
+	 * When transaction started
+	 */
+	unsigned long		t_start;
+
+	/*
+	 * Checkpointing stats [j_checkpoint_sem]
+	 */
+	struct transaction_chp_stats_s t_chp_stats;
+
+	/*
+	 * Number of outstanding updates running on this transaction
+	 * [t_handle_lock]
+	 */
+	atomic_t		t_updates;
+
+	/*
+	 * Number of buffers reserved for use by all handles in this transaction
+	 * handle but not yet modified. [t_handle_lock]
+	 */
+	atomic_t		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]
+	 */
+	atomic_t		t_handle_count;
+
+	/*
+	 * This transaction is being forced and some process is
+	 * waiting for it to finish.
+	 */
+	unsigned int t_synchronous_commit:1;
+
+	/* Disk flush needs to be sent to fs partition [no locking] */
+	int			t_need_data_flush;
+
+	/*
+	 * For use by the filesystem to store fs-specific data
+	 * structures associated with the transaction
+	 */
+	struct list_head	t_private_list;
+};
+
+struct transaction_run_stats_s {
+	unsigned long		rs_wait;
+	unsigned long		rs_running;
+	unsigned long		rs_locked;
+	unsigned long		rs_flushing;
+	unsigned long		rs_logging;
+
+	__u32			rs_handle_count;
+	__u32			rs_blocks;
+	__u32			rs_blocks_logged;
+};
+
+struct transaction_stats_s {
+	unsigned long		ts_tid;
+	struct transaction_run_stats_s run;
+};
+
+static inline unsigned long
+jbd2_time_diff(unsigned long start, unsigned long end)
+{
+	if (end >= start)
+		return end - start;
+
+	return end + (MAX_JIFFY_OFFSET - start);
+}
+
+#define JBD2_NR_BATCH	64
+
+/**
+ * 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_state_lock: Protect the various scalars in the journal
+ * @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_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 jbd2_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_history: Buffer storing the transactions statistics history
+ * @j_history_max: Maximum number of transactions in the statistics history
+ * @j_history_cur: Current number of transactions in the statistics history
+ * @j_history_lock: Protect the transactions statistics history
+ * @j_proc_entry: procfs entry for the jbd statistics directory
+ * @j_stats: Overall statistics
+ * @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
+	 */
+	rwlock_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 mutex		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 mutex		j_checkpoint_mutex;
+
+	/*
+	 * List of buffer heads used by the checkpoint routine.  This
+	 * was moved from jbd2_log_do_checkpoint() to reduce stack
+	 * usage.  Access to this array is controlled by the
+	 * j_checkpoint_mutex.  [j_checkpoint_mutex]
+	 */
+	struct buffer_head	*j_chkpt_bhs[JBD2_NR_BATCH];
+	
+	/*
+	 * 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 long long	j_blk_offset;
+	char			j_devname[BDEVNAME_SIZE+24];
+
+	/*
+	 * 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 jbd2_revoke_table_s *j_revoke;
+	struct jbd2_revoke_table_s *j_revoke_table[2];
+
+	/*
+	 * array of bhs for jbd2_journal_commit_transaction
+	 */
+	struct buffer_head	**j_wbuf;
+	int			j_wbufsize;
+
+	/*
+	 * this is the pid of hte 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 disk. [j_state_lock]
+	 */
+	u64			j_average_commit_time;
+
+	/*
+	 * minimum and maximum times that we should wait for
+	 * additional filesystem operations to get batched into a
+	 * synchronous handle in microseconds
+	 */
+	u32			j_min_batch_time;
+	u32			j_max_batch_time;
+
+	/* This function is called when a transaction is closed */
+	void			(*j_commit_callback)(journal_t *,
+						     transaction_t *);
+
+	/*
+	 * Journal statistics
+	 */
+	spinlock_t		j_history_lock;
+	struct proc_dir_entry	*j_proc_entry;
+	struct transaction_stats_s j_stats;
+
+	/* Failed journal commit ID */
+	unsigned int		j_failed_commit;
+
+	/*
+	 * An opaque pointer to fs-private information.  ext3 puts its
+	 * superblock pointer here
+	 */
+	void *j_private;
+};
+
+/*
+ * Journal flag definitions
+ */
+#define JBD2_UNMOUNT	0x001	/* Journal thread is being destroyed */
+#define JBD2_ABORT	0x002	/* Journaling has been aborted for errors. */
+#define JBD2_ACK_ERR	0x004	/* The errno in the sb has been acked */
+#define JBD2_FLUSHED	0x008	/* The journal superblock has been flushed */
+#define JBD2_LOADED	0x010	/* The journal superblock has been loaded */
+#define JBD2_BARRIER	0x020	/* Use IDE barriers */
+#define JBD2_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 jbd2_journal_unfile_buffer(journal_t *, struct journal_head *);
+extern void __jbd2_journal_refile_buffer(struct journal_head *);
+extern void jbd2_journal_refile_buffer(journal_t *, struct journal_head *);
+extern void __jbd2_journal_file_buffer(struct journal_head *, transaction_t *, int);
+extern void __journal_free_buffer(struct journal_head *bh);
+extern void jbd2_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 * jbd2_journal_get_descriptor_buffer(journal_t *);
+int jbd2_journal_next_log_block(journal_t *, unsigned long long *);
+int jbd2_journal_get_log_tail(journal_t *journal, tid_t *tid,
+			      unsigned long *block);
+void __jbd2_update_log_tail(journal_t *journal, tid_t tid, unsigned long block);
+void jbd2_update_log_tail(journal_t *journal, tid_t tid, unsigned long block);
+
+/* Commit management */
+extern void jbd2_journal_commit_transaction(journal_t *);
+
+/* Checkpoint list management */
+int __jbd2_journal_clean_checkpoint_list(journal_t *journal);
+int __jbd2_journal_remove_checkpoint(struct journal_head *);
+void __jbd2_journal_insert_checkpoint(struct journal_head *, transaction_t *);
+
+
+/*
+ * Triggers
+ */
+
+struct jbd2_buffer_trigger_type {
+	/*
+	 * Fired a the moment data to write to the journal are known to be
+	 * stable - so either at the moment b_frozen_data is created or just
+	 * before a buffer is written to the journal.  mapped_data is a mapped
+	 * buffer that is the frozen data for commit.
+	 */
+	void (*t_frozen)(struct jbd2_buffer_trigger_type *type,
+			 struct buffer_head *bh, void *mapped_data,
+			 size_t size);
+
+	/*
+	 * Fired during journal abort for dirty buffers that will not be
+	 * committed.
+	 */
+	void (*t_abort)(struct jbd2_buffer_trigger_type *type,
+			struct buffer_head *bh);
+};
+
+extern void jbd2_buffer_frozen_trigger(struct journal_head *jh,
+				       void *mapped_data,
+				       struct jbd2_buffer_trigger_type *triggers);
+extern void jbd2_buffer_abort_trigger(struct journal_head *jh,
+				      struct jbd2_buffer_trigger_type *triggers);
+
+/* Buffer IO */
+extern int
+jbd2_journal_write_metadata_buffer(transaction_t	  *transaction,
+			      struct journal_head  *jh_in,
+			      struct journal_head **jh_out,
+			      unsigned long long   blocknr);
+
+/* Transaction locking */
+extern void		__wait_on_journal (journal_t *);
+
+/* Transaction cache support */
+extern void jbd2_journal_destroy_transaction_cache(void);
+extern int  jbd2_journal_init_transaction_cache(void);
+extern void jbd2_journal_free_transaction(transaction_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 *jbd2_journal_start(journal_t *, int nblocks);
+extern handle_t *jbd2__journal_start(journal_t *, int nblocks, gfp_t gfp_mask);
+extern int	 jbd2_journal_restart(handle_t *, int nblocks);
+extern int	 jbd2__journal_restart(handle_t *, int nblocks, gfp_t gfp_mask);
+extern int	 jbd2_journal_extend (handle_t *, int nblocks);
+extern int	 jbd2_journal_get_write_access(handle_t *, struct buffer_head *);
+extern int	 jbd2_journal_get_create_access (handle_t *, struct buffer_head *);
+extern int	 jbd2_journal_get_undo_access(handle_t *, struct buffer_head *);
+void		 jbd2_journal_set_triggers(struct buffer_head *,
+					   struct jbd2_buffer_trigger_type *type);
+extern int	 jbd2_journal_dirty_metadata (handle_t *, struct buffer_head *);
+extern void	 jbd2_journal_release_buffer (handle_t *, struct buffer_head *);
+extern int	 jbd2_journal_forget (handle_t *, struct buffer_head *);
+extern void	 journal_sync_buffer (struct buffer_head *);
+extern void	 jbd2_journal_invalidatepage(journal_t *,
+				struct page *, unsigned long);
+extern int	 jbd2_journal_try_to_free_buffers(journal_t *, struct page *, gfp_t);
+extern int	 jbd2_journal_stop(handle_t *);
+extern int	 jbd2_journal_flush (journal_t *);
+extern void	 jbd2_journal_lock_updates (journal_t *);
+extern void	 jbd2_journal_unlock_updates (journal_t *);
+
+extern journal_t * jbd2_journal_init_dev(struct block_device *bdev,
+				struct block_device *fs_dev,
+				unsigned long long start, int len, int bsize);
+extern journal_t * jbd2_journal_init_inode (struct inode *);
+extern int	   jbd2_journal_update_format (journal_t *);
+extern int	   jbd2_journal_check_used_features
+		   (journal_t *, unsigned long, unsigned long, unsigned long);
+extern int	   jbd2_journal_check_available_features
+		   (journal_t *, unsigned long, unsigned long, unsigned long);
+extern int	   jbd2_journal_set_features
+		   (journal_t *, unsigned long, unsigned long, unsigned long);
+extern void	   jbd2_journal_clear_features
+		   (journal_t *, unsigned long, unsigned long, unsigned long);
+extern int	   jbd2_journal_load       (journal_t *journal);
+extern int	   jbd2_journal_destroy    (journal_t *);
+extern int	   jbd2_journal_recover    (journal_t *journal);
+extern int	   jbd2_journal_wipe       (journal_t *, int);
+extern int	   jbd2_journal_skip_recovery	(journal_t *);
+extern void	   jbd2_journal_update_sb_log_tail	(journal_t *, tid_t,
+				unsigned long, int);
+extern void	   __jbd2_journal_abort_hard	(journal_t *);
+extern void	   jbd2_journal_abort      (journal_t *, int);
+extern int	   jbd2_journal_errno      (journal_t *);
+extern void	   jbd2_journal_ack_err    (journal_t *);
+extern int	   jbd2_journal_clear_err  (journal_t *);
+extern int	   jbd2_journal_bmap(journal_t *, unsigned long, unsigned long long *);
+extern int	   jbd2_journal_force_commit(journal_t *);
+extern int	   jbd2_journal_file_inode(handle_t *handle, struct jbd2_inode *inode);
+extern int	   jbd2_journal_begin_ordered_truncate(journal_t *journal,
+				struct jbd2_inode *inode, loff_t new_size);
+extern void	   jbd2_journal_init_jbd_inode(struct jbd2_inode *jinode, struct inode *inode);
+extern void	   jbd2_journal_release_jbd_inode(journal_t *journal, struct jbd2_inode *jinode);
+
+/*
+ * journal_head management
+ */
+struct journal_head *jbd2_journal_add_journal_head(struct buffer_head *bh);
+struct journal_head *jbd2_journal_grab_journal_head(struct buffer_head *bh);
+void jbd2_journal_put_journal_head(struct journal_head *jh);
+
+/*
+ * handle management
+ */
+extern struct kmem_cache *jbd2_handle_cache;
+
+static inline handle_t *jbd2_alloc_handle(gfp_t gfp_flags)
+{
+	return kmem_cache_alloc(jbd2_handle_cache, gfp_flags);
+}
+
+static inline void jbd2_free_handle(handle_t *handle)
+{
+	kmem_cache_free(jbd2_handle_cache, handle);
+}
+
+/*
+ * jbd2_inode management (optional, for those file systems that want to use
+ * dynamically allocated jbd2_inode structures)
+ */
+extern struct kmem_cache *jbd2_inode_cache;
+
+static inline struct jbd2_inode *jbd2_alloc_inode(gfp_t gfp_flags)
+{
+	return kmem_cache_alloc(jbd2_inode_cache, gfp_flags);
+}
+
+static inline void jbd2_free_inode(struct jbd2_inode *jinode)
+{
+	kmem_cache_free(jbd2_inode_cache, jinode);
+}
+
+/* Primary revoke support */
+#define JOURNAL_REVOKE_DEFAULT_HASH 256
+extern int	   jbd2_journal_init_revoke(journal_t *, int);
+extern void	   jbd2_journal_destroy_revoke_caches(void);
+extern int	   jbd2_journal_init_revoke_caches(void);
+
+extern void	   jbd2_journal_destroy_revoke(journal_t *);
+extern int	   jbd2_journal_revoke (handle_t *, unsigned long long, struct buffer_head *);
+extern int	   jbd2_journal_cancel_revoke(handle_t *, struct journal_head *);
+extern void	   jbd2_journal_write_revoke_records(journal_t *,
+						     transaction_t *, int);
+
+/* Recovery revoke support */
+extern int	jbd2_journal_set_revoke(journal_t *, unsigned long long, tid_t);
+extern int	jbd2_journal_test_revoke(journal_t *, unsigned long long, tid_t);
+extern void	jbd2_journal_clear_revoke(journal_t *);
+extern void	jbd2_journal_switch_revoke_table(journal_t *journal);
+extern void	jbd2_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 __jbd2_log_space_left(journal_t *); /* Called with journal locked */
+int jbd2_log_start_commit(journal_t *journal, tid_t tid);
+int __jbd2_log_start_commit(journal_t *journal, tid_t tid);
+int jbd2_journal_start_commit(journal_t *journal, tid_t *tid);
+int jbd2_journal_force_commit_nested(journal_t *journal);
+int jbd2_log_wait_commit(journal_t *journal, tid_t tid);
+int jbd2_log_do_checkpoint(journal_t *journal);
+int jbd2_trans_will_send_data_barrier(journal_t *journal, tid_t tid);
+
+void __jbd2_log_wait_for_space(journal_t *journal);
+extern void __jbd2_journal_drop_transaction(journal_t *, transaction_t *);
+extern int jbd2_cleanup_journal_tail(journal_t *);
+
+/* Debugging code only: */
+
+#define jbd_ENOSYS() \
+do {								           \
+	printk (KERN_ERR "JBD unimplemented function %s\n", __func__); \
+	current->state = TASK_UNINTERRUPTIBLE;			           \
+	schedule();						           \
+} while (1)
+
+/*
+ * is_journal_abort
+ *
+ * Simple test wrapper function to test the JBD2_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 & JBD2_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 jbd2_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 jbd2_journal_blocks_per_page(struct inode *inode);
+extern size_t journal_tag_bytes(journal_t *journal);
+
+/*
+ * 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 += atomic_read(&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_Metadata	1	/* Normal journaled metadata */
+#define BJ_Forget	2	/* Buffer superseded by this transaction */
+#define BJ_IO		3	/* Buffer is for temporary IO use */
+#define BJ_Shadow	4	/* Buffer contents being shadowed to the log */
+#define BJ_LogCtl	5	/* Buffer contains log descriptors */
+#define BJ_Reserved	6	/* Buffer is reserved for access by journal */
+#define BJ_Types	7
+
+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_JBD2_H */