/*
* 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 */
#include "jfs_compat.h"
#define JFS_DEBUG
#define jfs_debug jbd_debug
#define journal_oom_retry 1
/*
* Define JBD_PARANIOD_IOFAIL to cause a kernel BUG() if ext3 finds
* certain classes of error which can occur due to failed IOs. Under
* normal use we want ext3 to continue after such errors, because
* hardware _can_ fail, but for debugging purposes when running tests on
* known-good hardware we may want to trap these errors.
*/
#undef JBD_PARANOID_IOFAIL
/*
* The default maximum commit age, in seconds.
*/
#define JBD_DEFAULT_MAX_COMMIT_AGE 5
#ifdef CONFIG_JBD_DEBUG
/*
* Define JBD_EXPENSIVE_CHECKING to enable more expensive internal
* consistency checks. By default we don't do this unless
* CONFIG_JBD_DEBUG is on.
*/
#define JBD_EXPENSIVE_CHECKING
extern u8 journal_enable_debug;
#define jbd_debug(n, f, a...) \
do { \
if ((n) <= journal_enable_debug) { \
printk (KERN_DEBUG "(%s, %d): %s: ", \
__FILE__, __LINE__, __FUNCTION__); \
printk (f, ## a); \
} \
} while (0)
#else
#define jbd_debug(f, a...) /**/
#endif
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
/*
* Internal structures used by the logging mechanism:
*/
#define JFS_MAGIC_NUMBER 0xc03b3998U /* The first 4 bytes of /dev/random! */
/*
* On-disk structures
*/
/*
* Descriptor block types:
*/
#define JFS_DESCRIPTOR_BLOCK 1
#define JFS_COMMIT_BLOCK 2
#define JFS_SUPERBLOCK_V1 3
#define JFS_SUPERBLOCK_V2 4
#define JFS_REVOKE_BLOCK 5
/*
* Standard header for all descriptor blocks:
*/
typedef struct journal_header_s
{
__be32 h_magic;
__be32 h_blocktype;
__be32 h_sequence;
} journal_header_t;
/*
* The block tag: used to describe a single buffer in the journal
*/
typedef struct journal_block_tag_s
{
__be32 t_blocknr; /* The on-disk block number */
__be32 t_flags; /* See below */
} journal_block_tag_t;
/*
* The revoke descriptor: used on disk to describe a series of blocks to
* be revoked from the log
*/
typedef struct journal_revoke_header_s
{
journal_header_t r_header;
__be32 r_count; /* Count of bytes used in the block */
} journal_revoke_header_t;
/* Definitions for the journal tag flags word: */
#define JFS_FLAG_ESCAPE 1 /* on-disk block is escaped */
#define JFS_FLAG_SAME_UUID 2 /* block has same uuid as previous */
#define JFS_FLAG_DELETED 4 /* block deleted by this transaction */
#define JFS_FLAG_LAST_TAG 8 /* last tag in this descriptor block */
/*
* The journal superblock. All fields are in big-endian byte order.
*/
typedef struct journal_superblock_s
{
/* 0x0000 */
journal_header_t s_header;
/* 0x000C */
/* Static information describing the journal */
__be32 s_blocksize; /* journal device blocksize */
__be32 s_maxlen; /* total blocks in journal file */
__be32 s_first; /* first block of log information */
/* 0x0018 */
/* Dynamic information describing the current state of the log */
__be32 s_sequence; /* first commit ID expected in log */
__be32 s_start; /* blocknr of start of log */
/* 0x0020 */
/* Error value, as set by journal_abort(). */
__be32 s_errno;
/* 0x0024 */
/* Remaining fields are only valid in a version-2 superblock */
__be32 s_feature_compat; /* compatible feature set */
__be32 s_feature_incompat; /* incompatible feature set */
__be32 s_feature_ro_compat; /* readonly-compatible feature set */
/* 0x0030 */
__u8 s_uuid[16]; /* 128-bit uuid for journal */
/* 0x0040 */
__be32 s_nr_users; /* Nr of filesystems sharing log */
__be32 s_dynsuper; /* Blocknr of dynamic superblock copy*/
/* 0x0048 */
__be32 s_max_transaction; /* Limit of journal blocks per trans.*/
__be32 s_max_trans_data; /* Limit of data blocks per trans. */
/* 0x0050 */
__u32 s_padding[44];
/* 0x0100 */
__u8 s_users[16*48]; /* ids of all fs'es sharing the log */
/* 0x0400 */
} journal_superblock_t;
#define JFS_HAS_COMPAT_FEATURE(j,mask) \
((j)->j_format_version >= 2 && \
((j)->j_superblock->s_feature_compat & cpu_to_be32((mask))))
#define JFS_HAS_RO_COMPAT_FEATURE(j,mask) \
((j)->j_format_version >= 2 && \
((j)->j_superblock->s_feature_ro_compat & cpu_to_be32((mask))))
#define JFS_HAS_INCOMPAT_FEATURE(j,mask) \
((j)->j_format_version >= 2 && \
((j)->j_superblock->s_feature_incompat & cpu_to_be32((mask))))
#define JFS_FEATURE_INCOMPAT_REVOKE 0x00000001
/* Features known to this kernel version: */
#define JFS_KNOWN_COMPAT_FEATURES 0
#define JFS_KNOWN_ROCOMPAT_FEATURES 0
#define JFS_KNOWN_INCOMPAT_FEATURES JFS_FEATURE_INCOMPAT_REVOKE
/* Comparison functions for transaction IDs: perform comparisons using
* modulo arithmetic so that they work over sequence number wraps. */
static __inline__ int tid_gt(tid_t x, tid_t y)
{
int difference = (x - y);
return (difference > 0);
}
static __inline__ int tid_geq(tid_t x, tid_t y)
{
int difference = (x - y);
return (difference >= 0);
}
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);
#endif /* _LINUX_JBD_H */