[PATCH] jbd2: initial copy of files from jbd

This is a simple copy of the files in fs/jbd to fs/jbd2 and
/usr/incude/linux/[ext4_]jbd.h to /usr/include/[ext4_]jbd2.h

Signed-off-by: Dave Kleikamp <shaggy@austin.ibm.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

2 files changed, 1366 insertions, 0 deletions

diff --git a/include/linux/ext4_jbd2.h b/include/linux/ext4_jbd2.h
new file mode 100644
index 000000000000..3dbf6c779037
--- /dev/null
+++ b/include/linux/ext4_jbd2.h
@@ -0,0 +1,268 @@
+/*
+ * linux/include/linux/ext4_jbd.h
+ *
+ * Written by Stephen C. Tweedie <sct@redhat.com>, 1999
+ *
+ * Copyright 1998--1999 Red Hat corp --- 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.
+ *
+ * Ext4-specific journaling extensions.
+ */
+
+#ifndef _LINUX_EXT4_JBD_H
+#define _LINUX_EXT4_JBD_H
+
+#include <linux/fs.h>
+#include <linux/jbd.h>
+#include <linux/ext4_fs.h>
+
+#define EXT4_JOURNAL(inode)     (EXT4_SB((inode)->i_sb)->s_journal)
+
+/* Define the number of blocks we need to account to a transaction to
+ * modify one block of data.
+ *
+ * We may have to touch one inode, one bitmap buffer, up to three
+ * indirection blocks, the group and superblock summaries, and the data
+ * block to complete the transaction.  */
+
+#define EXT4_SINGLEDATA_TRANS_BLOCKS    8U
+
+/* Extended attribute operations touch at most two data buffers,
+ * two bitmap buffers, and two group summaries, in addition to the inode
+ * and the superblock, which are already accounted for. */
+
+#define EXT4_XATTR_TRANS_BLOCKS         6U
+
+/* Define the minimum size for a transaction which modifies data.  This
+ * needs to take into account the fact that we may end up modifying two
+ * quota files too (one for the group, one for the user quota).  The
+ * superblock only gets updated once, of course, so don't bother
+ * counting that again for the quota updates. */
+
+#define EXT4_DATA_TRANS_BLOCKS(sb)      (EXT4_SINGLEDATA_TRANS_BLOCKS + \
+                                         EXT4_XATTR_TRANS_BLOCKS - 2 + \
+                                         2*EXT4_QUOTA_TRANS_BLOCKS(sb))
+
+/* Delete operations potentially hit one directory's namespace plus an
+ * entire inode, plus arbitrary amounts of bitmap/indirection data.  Be
+ * generous.  We can grow the delete transaction later if necessary. */
+
+#define EXT4_DELETE_TRANS_BLOCKS(sb)    (2 * EXT4_DATA_TRANS_BLOCKS(sb) + 64)
+
+/* Define an arbitrary limit for the amount of data we will anticipate
+ * writing to any given transaction.  For unbounded transactions such as
+ * write(2) and truncate(2) we can write more than this, but we always
+ * start off at the maximum transaction size and grow the transaction
+ * optimistically as we go. */
+
+#define EXT4_MAX_TRANS_DATA             64U
+
+/* We break up a large truncate or write transaction once the handle's
+ * buffer credits gets this low, we need either to extend the
+ * transaction or to start a new one.  Reserve enough space here for
+ * inode, bitmap, superblock, group and indirection updates for at least
+ * one block, plus two quota updates.  Quota allocations are not
+ * needed. */
+
+#define EXT4_RESERVE_TRANS_BLOCKS       12U
+
+#define EXT4_INDEX_EXTRA_TRANS_BLOCKS   8
+
+#ifdef CONFIG_QUOTA
+/* Amount of blocks needed for quota update - we know that the structure was
+ * allocated so we need to update only inode+data */
+#define EXT4_QUOTA_TRANS_BLOCKS(sb) (test_opt(sb, QUOTA) ? 2 : 0)
+/* Amount of blocks needed for quota insert/delete - we do some block writes
+ * but inode, sb and group updates are done only once */
+#define EXT4_QUOTA_INIT_BLOCKS(sb) (test_opt(sb, QUOTA) ? (DQUOT_INIT_ALLOC*\
+                (EXT4_SINGLEDATA_TRANS_BLOCKS-3)+3+DQUOT_INIT_REWRITE) : 0)
+#define EXT4_QUOTA_DEL_BLOCKS(sb) (test_opt(sb, QUOTA) ? (DQUOT_DEL_ALLOC*\
+                (EXT4_SINGLEDATA_TRANS_BLOCKS-3)+3+DQUOT_DEL_REWRITE) : 0)
+#else
+#define EXT4_QUOTA_TRANS_BLOCKS(sb) 0
+#define EXT4_QUOTA_INIT_BLOCKS(sb) 0
+#define EXT4_QUOTA_DEL_BLOCKS(sb) 0
+#endif
+
+int
+ext4_mark_iloc_dirty(handle_t *handle,
+                     struct inode *inode,
+                     struct ext4_iloc *iloc);
+
+/*
+ * On success, We end up with an outstanding reference count against
+ * iloc->bh.  This _must_ be cleaned up later.
+ */
+
+int ext4_reserve_inode_write(handle_t *handle, struct inode *inode,
+                        struct ext4_iloc *iloc);
+
+int ext4_mark_inode_dirty(handle_t *handle, struct inode *inode);
+
+/*
+ * Wrapper functions with which ext4 calls into JBD.  The intent here is
+ * to allow these to be turned into appropriate stubs so ext4 can control
+ * ext2 filesystems, so ext2+ext4 systems only nee one fs.  This work hasn't
+ * been done yet.
+ */
+
+void ext4_journal_abort_handle(const char *caller, const char *err_fn,
+                struct buffer_head *bh, handle_t *handle, int err);
+
+static inline int
+__ext4_journal_get_undo_access(const char *where, handle_t *handle,
+                                struct buffer_head *bh)
+{
+        int err = journal_get_undo_access(handle, bh);
+        if (err)
+                ext4_journal_abort_handle(where, __FUNCTION__, bh, handle,err);
+        return err;
+}
+
+static inline int
+__ext4_journal_get_write_access(const char *where, handle_t *handle,
+                                struct buffer_head *bh)
+{
+        int err = journal_get_write_access(handle, bh);
+        if (err)
+                ext4_journal_abort_handle(where, __FUNCTION__, bh, handle,err);
+        return err;
+}
+
+static inline void
+ext4_journal_release_buffer(handle_t *handle, struct buffer_head *bh)
+{
+        journal_release_buffer(handle, bh);
+}
+
+static inline int
+__ext4_journal_forget(const char *where, handle_t *handle, struct buffer_head *bh)
+{
+        int err = journal_forget(handle, bh);
+        if (err)
+                ext4_journal_abort_handle(where, __FUNCTION__, bh, handle,err);
+        return err;
+}
+
+static inline int
+__ext4_journal_revoke(const char *where, handle_t *handle,
+                      unsigned long blocknr, struct buffer_head *bh)
+{
+        int err = journal_revoke(handle, blocknr, bh);
+        if (err)
+                ext4_journal_abort_handle(where, __FUNCTION__, bh, handle,err);
+        return err;
+}
+
+static inline int
+__ext4_journal_get_create_access(const char *where,
+                                 handle_t *handle, struct buffer_head *bh)
+{
+        int err = journal_get_create_access(handle, bh);
+        if (err)
+                ext4_journal_abort_handle(where, __FUNCTION__, bh, handle,err);
+        return err;
+}
+
+static inline int
+__ext4_journal_dirty_metadata(const char *where,
+                              handle_t *handle, struct buffer_head *bh)
+{
+        int err = journal_dirty_metadata(handle, bh);
+        if (err)
+                ext4_journal_abort_handle(where, __FUNCTION__, bh, handle,err);
+        return err;
+}
+
+
+#define ext4_journal_get_undo_access(handle, bh) \
+        __ext4_journal_get_undo_access(__FUNCTION__, (handle), (bh))
+#define ext4_journal_get_write_access(handle, bh) \
+        __ext4_journal_get_write_access(__FUNCTION__, (handle), (bh))
+#define ext4_journal_revoke(handle, blocknr, bh) \
+        __ext4_journal_revoke(__FUNCTION__, (handle), (blocknr), (bh))
+#define ext4_journal_get_create_access(handle, bh) \
+        __ext4_journal_get_create_access(__FUNCTION__, (handle), (bh))
+#define ext4_journal_dirty_metadata(handle, bh) \
+        __ext4_journal_dirty_metadata(__FUNCTION__, (handle), (bh))
+#define ext4_journal_forget(handle, bh) \
+        __ext4_journal_forget(__FUNCTION__, (handle), (bh))
+
+int ext4_journal_dirty_data(handle_t *handle, struct buffer_head *bh);
+
+handle_t *ext4_journal_start_sb(struct super_block *sb, int nblocks);
+int __ext4_journal_stop(const char *where, handle_t *handle);
+
+static inline handle_t *ext4_journal_start(struct inode *inode, int nblocks)
+{
+        return ext4_journal_start_sb(inode->i_sb, nblocks);
+}
+
+#define ext4_journal_stop(handle) \
+        __ext4_journal_stop(__FUNCTION__, (handle))
+
+static inline handle_t *ext4_journal_current_handle(void)
+{
+        return journal_current_handle();
+}
+
+static inline int ext4_journal_extend(handle_t *handle, int nblocks)
+{
+        return journal_extend(handle, nblocks);
+}
+
+static inline int ext4_journal_restart(handle_t *handle, int nblocks)
+{
+        return journal_restart(handle, nblocks);
+}
+
+static inline int ext4_journal_blocks_per_page(struct inode *inode)
+{
+        return journal_blocks_per_page(inode);
+}
+
+static inline int ext4_journal_force_commit(journal_t *journal)
+{
+        return journal_force_commit(journal);
+}
+
+/* super.c */
+int ext4_force_commit(struct super_block *sb);
+
+static inline int ext4_should_journal_data(struct inode *inode)
+{
+        if (!S_ISREG(inode->i_mode))
+                return 1;
+        if (test_opt(inode->i_sb, DATA_FLAGS) == EXT4_MOUNT_JOURNAL_DATA)
+                return 1;
+        if (EXT4_I(inode)->i_flags & EXT4_JOURNAL_DATA_FL)
+                return 1;
+        return 0;
+}
+
+static inline int ext4_should_order_data(struct inode *inode)
+{
+        if (!S_ISREG(inode->i_mode))
+                return 0;
+        if (EXT4_I(inode)->i_flags & EXT4_JOURNAL_DATA_FL)
+                return 0;
+        if (test_opt(inode->i_sb, DATA_FLAGS) == EXT4_MOUNT_ORDERED_DATA)
+                return 1;
+        return 0;
+}
+
+static inline int ext4_should_writeback_data(struct inode *inode)
+{
+        if (!S_ISREG(inode->i_mode))
+                return 0;
+        if (EXT4_I(inode)->i_flags & EXT4_JOURNAL_DATA_FL)
+                return 0;
+        if (test_opt(inode->i_sb, DATA_FLAGS) == EXT4_MOUNT_WRITEBACK_DATA)
+                return 1;
+        return 0;
+}
+
+#endif  /* _LINUX_EXT4_JBD_H */
diff --git a/include/linux/jbd2.h b/include/linux/jbd2.h
new file mode 100644
index 000000000000..fe89444b1c6f
--- /dev/null
+++ b/include/linux/jbd2.h
@@ -0,0 +1,1098 @@
+/*
+ * 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 <asm/semaphore.h>
+#endif
+
+#define journal_oom_retry 1
+
+/*
+ * Define JBD_PARANIOD_IOFAIL to cause a kernel BUG() if ext3 finds
+ * certain classes of error which can occur due to failed IOs.  Under
+ * normal use we want ext3 to continue after such errors, because
+ * hardware _can_ fail, but for debugging purposes when running tests on
+ * known-good hardware we may want to trap these errors.
+ */
+#undef JBD_PARANOID_IOFAIL
+
+/*
+ * 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 int journal_enable_debug;
+
+#define jbd_debug(n, f, a...)                                           \
+        do {                                                            \
+                if ((n) <= journal_enable_debug) {                      \
+                        printk (KERN_DEBUG "(%s, %d): %s: ",            \
+                                __FILE__, __LINE__, __FUNCTION__);      \
+                        printk (f, ## a);                               \
+                }                                                       \
+        } while (0)
+#else
+#define jbd_debug(f, a...)      /**/
+#endif
+
+extern void * __jbd_kmalloc (const char *where, size_t size, gfp_t flags, int retry);
+extern void * jbd_slab_alloc(size_t size, gfp_t flags);
+extern void jbd_slab_free(void *ptr, size_t size);
+
+#define jbd_kmalloc(size, flags) \
+        __jbd_kmalloc(__FUNCTION__, (size), (flags), journal_oom_retry)
+#define jbd_rep_kmalloc(size, flags) \
+        __jbd_kmalloc(__FUNCTION__, (size), (flags), 1)
+
+#define JFS_MIN_JOURNAL_BLOCKS 1024
+
+#ifdef __KERNEL__
+
+/**
+ * typedef handle_t - The handle_t type represents a single atomic update being performed by some process.
+ *
+ * All filesystem modifications made by the process go
+ * through this handle.  Recursive operations (such as quota operations)
+ * are gathered into a single update.
+ *
+ * The buffer credits field is used to account for journaled buffers
+ * being modified by the running process.  To ensure that there is
+ * enough log space for all outstanding operations, we need to limit the
+ * number of outstanding buffers possible at any time.  When the
+ * operation completes, any buffer credits not used are credited back to
+ * the transaction, so that at all times we know how many buffers the
+ * outstanding updates on a transaction might possibly touch.
+ *
+ * This is an opaque datatype.
+ **/
+typedef struct handle_s         handle_t;       /* Atomic operation type */
+
+
+/**
+ * typedef journal_t - The journal_t maintains all of the journaling state information for a single filesystem.
+ *
+ * journal_t is linked to from the fs superblock structure.
+ *
+ * We use the journal_t to keep track of all outstanding transaction
+ * activity on the filesystem, and to manage the state of the log
+ * writing process.
+ *
+ * This is an opaque datatype.
+ **/
+typedef struct journal_s        journal_t;      /* Journal control structure */
+#endif
+
+/*
+ * Internal structures used by the logging mechanism:
+ */
+
+#define JFS_MAGIC_NUMBER 0xc03b3998U /* The first 4 bytes of /dev/random! */
+
+/*
+ * On-disk structures
+ */
+
+/*
+ * Descriptor block types:
+ */
+
+#define JFS_DESCRIPTOR_BLOCK    1
+#define JFS_COMMIT_BLOCK        2
+#define JFS_SUPERBLOCK_V1       3
+#define JFS_SUPERBLOCK_V2       4
+#define JFS_REVOKE_BLOCK        5
+
+/*
+ * Standard header for all descriptor blocks:
+ */
+typedef struct journal_header_s
+{
+        __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>
+
+#define JBD_ASSERTIONS
+#ifdef JBD_ASSERTIONS
+#define J_ASSERT(assert)                                                \
+do {                                                                    \
+        if (!(assert)) {                                                \
+                printk (KERN_EMERG                                      \
+                        "Assertion failure in %s() at %s:%d: \"%s\"\n", \
+                        __FUNCTION__, __FILE__, __LINE__, # assert);    \
+                BUG();                                                  \
+        }                                                               \
+} while (0)
+
+#if defined(CONFIG_BUFFER_DEBUG)
+void buffer_assertion_failure(struct buffer_head *bh);
+#define J_ASSERT_BH(bh, expr)                                           \
+        do {                                                            \
+                if (!(expr))                                            \
+                        buffer_assertion_failure(bh);                   \
+                J_ASSERT(expr);                                         \
+        } while (0)
+#define J_ASSERT_JH(jh, expr)   J_ASSERT_BH(jh2bh(jh), expr)
+#else
+#define J_ASSERT_BH(bh, expr)   J_ASSERT(expr)
+#define J_ASSERT_JH(jh, expr)   J_ASSERT(expr)
+#endif
+
+#else
+#define J_ASSERT(assert)        do { } while (0)
+#endif          /* JBD_ASSERTIONS */
+
+#if defined(JBD_PARANOID_IOFAIL)
+#define J_EXPECT(expr, why...)          J_ASSERT(expr)
+#define J_EXPECT_BH(bh, expr, why...)   J_ASSERT_BH(bh, expr)
+#define J_EXPECT_JH(jh, expr, why...)   J_ASSERT_JH(jh, expr)
+#else
+#define __journal_expect(expr, why...)                                       \
+        ({                                                                   \
+                int val = (expr);                                            \
+                if (!val) {                                                  \
+                        printk(KERN_ERR                                      \
+                                "EXT3-fs unexpected failure: %s;\n",# 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 */
+};
+
+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);
+}
+
+struct jbd_revoke_table_s;
+
+/**
+ * struct handle_s - The handle_s type is the concrete type associated with
+ *     handle_t.
+ * @h_transaction: Which compound transaction is this update a part of?
+ * @h_buffer_credits: Number of remaining buffers we are allowed to dirty.
+ * @h_ref: Reference count on this handle
+ * @h_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 */
+};
+
+
+/* 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]
+         * 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 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;
+
+        /*
+         * How many handles used this transaction? [t_handle_lock]
+         */
+        int t_handle_count;
+
+};
+
+/**
+ * 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 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_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;
+
+        /*
+         * 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           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;
+
+        pid_t                   j_last_sync_writer;
+
+        /*
+         * 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 */
+
+/*
+ * Function declarations for the journaling transaction and buffer
+ * management
+ */
+
+/* Filing buffers */
+extern void __journal_temp_unlink_buffer(struct journal_head *jh);
+extern void journal_unfile_buffer(journal_t *, struct journal_head *);
+extern void __journal_unfile_buffer(struct journal_head *);
+extern void __journal_refile_buffer(struct journal_head *);
+extern void journal_refile_buffer(journal_t *, struct journal_head *);
+extern void __journal_file_buffer(struct journal_head *, transaction_t *, int);
+extern void __journal_free_buffer(struct journal_head *bh);
+extern void journal_file_buffer(struct journal_head *, transaction_t *, int);
+extern void __journal_clean_data_list(transaction_t *transaction);
+
+/* Log buffer allocation */
+extern struct journal_head * journal_get_descriptor_buffer(journal_t *);
+int journal_next_log_block(journal_t *, unsigned long *);
+
+/* Commit management */
+extern void journal_commit_transaction(journal_t *);
+
+/* Checkpoint list management */
+int __journal_clean_checkpoint_list(journal_t *journal);
+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 long        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 void        journal_destroy    (journal_t *);
+extern int         journal_recover    (journal_t *journal);
+extern int         journal_wipe       (journal_t *, int);
+extern int         journal_skip_recovery        (journal_t *);
+extern void        journal_update_superblock    (journal_t *, int);
+extern void        __journal_abort_hard (journal_t *);
+extern void        journal_abort      (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 long, unsigned long *);
+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_remove_journal_head(struct buffer_head *bh);
+void journal_put_journal_head(struct journal_head *jh);
+
+/*
+ * handle management
+ */
+extern kmem_cache_t *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 long, struct buffer_head *);
+extern int         journal_cancel_revoke(handle_t *, struct journal_head *);
+extern void        journal_write_revoke_records(journal_t *, transaction_t *);
+
+/* Recovery revoke support */
+extern int      journal_set_revoke(journal_t *, unsigned long, tid_t);
+extern int      journal_test_revoke(journal_t *, unsigned long, tid_t);
+extern void     journal_clear_revoke(journal_t *);
+extern void     journal_switch_revoke_table(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);
+
+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\n", __FUNCTION__); \
+        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 */