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jbd2.h
1313 lines (1109 loc) · 39.2 KB
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jbd2.h
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/*
* 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>
#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
static inline void *jbd2_alloc(size_t size, gfp_t flags)
{
return (void *)__get_free_pages(flags, get_order(size));
}
static inline void jbd2_free(void *ptr, size_t size)
{
free_pages((unsigned long)ptr, get_order(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 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 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>
#define J_ASSERT(assert) BUG_ON(!(assert))
#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
#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
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 */
BH_Unshadow, /* Dummy bit, for BJ_Shadow wakeup filtering */
BH_JBDPrivateStart, /* First bit available for private use by FS */
};
BUFFER_FNS(JBD, jbd)
BUFFER_FNS(JWrite, jwrite)
BUFFER_FNS(JBDDirty, jbddirty)
TAS_BUFFER_FNS(JBDDirty, jbddirty)
BUFFER_FNS(Revoked, revoked)
TAS_BUFFER_FNS(Revoked, revoked)
BUFFER_FNS(RevokeValid, revokevalid)
TAS_BUFFER_FNS(RevokeValid, revokevalid)
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);
}
/* 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 int 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 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
};
/*
* 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_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 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]
*/
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;
/*
* 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
*/
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 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
*/