kmem: add slab-specific documentation about the kmem controller

[linux/fpc-iii.git] / fs / ext4 / ext4_jbd2.h

/*
 * ext4_jbd2.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 _EXT4_JBD2_H
#define _EXT4_JBD2_H

#include <linux/fs.h>
#include <linux/jbd2.h>
#include "ext4.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.
 *
 * For extents-enabled fs we may have to allocate and modify up to
 * 5 levels of tree + root which are stored in the inode. */

#define EXT4_SINGLEDATA_TRANS_BLOCKS(sb)                                \
        (EXT4_HAS_INCOMPAT_FEATURE(sb, EXT4_FEATURE_INCOMPAT_EXTENTS)   \
         ? 27U : 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(sb) + \
                                         EXT4_XATTR_TRANS_BLOCKS - 2 + \
                                         EXT4_MAXQUOTAS_TRANS_BLOCKS(sb))

/*
 * Define the number of metadata blocks we need to account to modify data.
 *
 * This include super block, inode block, quota blocks and xattr blocks
 */
#define EXT4_META_TRANS_BLOCKS(sb)      (EXT4_XATTR_TRANS_BLOCKS + \
                                        EXT4_MAXQUOTAS_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 data block */
#define EXT4_QUOTA_TRANS_BLOCKS(sb) ((test_opt(sb, QUOTA) ||\
                EXT4_HAS_RO_COMPAT_FEATURE(sb, EXT4_FEATURE_RO_COMPAT_QUOTA)) ?\
                1 : 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) ||\
                EXT4_HAS_RO_COMPAT_FEATURE(sb, EXT4_FEATURE_RO_COMPAT_QUOTA)) ?\
                (DQUOT_INIT_ALLOC*(EXT4_SINGLEDATA_TRANS_BLOCKS(sb)-3)\
                 +3+DQUOT_INIT_REWRITE) : 0)

#define EXT4_QUOTA_DEL_BLOCKS(sb) ((test_opt(sb, QUOTA) ||\
                EXT4_HAS_RO_COMPAT_FEATURE(sb, EXT4_FEATURE_RO_COMPAT_QUOTA)) ?\
                (DQUOT_DEL_ALLOC*(EXT4_SINGLEDATA_TRANS_BLOCKS(sb)-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
#define EXT4_MAXQUOTAS_TRANS_BLOCKS(sb) (MAXQUOTAS*EXT4_QUOTA_TRANS_BLOCKS(sb))
#define EXT4_MAXQUOTAS_INIT_BLOCKS(sb) (MAXQUOTAS*EXT4_QUOTA_INIT_BLOCKS(sb))
#define EXT4_MAXQUOTAS_DEL_BLOCKS(sb) (MAXQUOTAS*EXT4_QUOTA_DEL_BLOCKS(sb))

/**
 *   struct ext4_journal_cb_entry - Base structure for callback information.
 *
 *   This struct is a 'seed' structure for a using with your own callback
 *   structs. If you are using callbacks you must allocate one of these
 *   or another struct of your own definition which has this struct
 *   as it's first element and pass it to ext4_journal_callback_add().
 */
struct ext4_journal_cb_entry {
        /* list information for other callbacks attached to the same handle */
        struct list_head jce_list;

        /*  Function to call with this callback structure */
        void (*jce_func)(struct super_block *sb,
                         struct ext4_journal_cb_entry *jce, int error);

        /* user data goes here */
};

/**
 * ext4_journal_callback_add: add a function to call after transaction commit
 * @handle: active journal transaction handle to register callback on
 * @func: callback function to call after the transaction has committed:
 *        @sb: superblock of current filesystem for transaction
 *        @jce: returned journal callback data
 *        @rc: journal state at commit (0 = transaction committed properly)
 * @jce: journal callback data (internal and function private data struct)
 *
 * The registered function will be called in the context of the journal thread
 * after the transaction for which the handle was created has completed.
 *
 * No locks are held when the callback function is called, so it is safe to
 * call blocking functions from within the callback, but the callback should
 * not block or run for too long, or the filesystem will be blocked waiting for
 * the next transaction to commit. No journaling functions can be used, or
 * there is a risk of deadlock.
 *
 * There is no guaranteed calling order of multiple registered callbacks on
 * the same transaction.
 */
static inline void ext4_journal_callback_add(handle_t *handle,
                        void (*func)(struct super_block *sb,
                                     struct ext4_journal_cb_entry *jce,
                                     int rc),
                        struct ext4_journal_cb_entry *jce)
{
        struct ext4_sb_info *sbi =
                        EXT4_SB(handle->h_transaction->t_journal->j_private);

        /* Add the jce to transaction's private list */
        jce->jce_func = func;
        spin_lock(&sbi->s_md_lock);
        list_add_tail(&jce->jce_list, &handle->h_transaction->t_private_list);
        spin_unlock(&sbi->s_md_lock);
}

/**
 * ext4_journal_callback_del: delete a registered callback
 * @handle: active journal transaction handle on which callback was registered
 * @jce: registered journal callback entry to unregister
 */
static inline void ext4_journal_callback_del(handle_t *handle,
                                             struct ext4_journal_cb_entry *jce)
{
        struct ext4_sb_info *sbi =
                        EXT4_SB(handle->h_transaction->t_journal->j_private);

        spin_lock(&sbi->s_md_lock);
        list_del_init(&jce->jce_list);
        spin_unlock(&sbi->s_md_lock);
}

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.
 */
void ext4_journal_abort_handle(const char *caller, unsigned int line,
                               const char *err_fn,
                struct buffer_head *bh, handle_t *handle, int err);

int __ext4_journal_get_write_access(const char *where, unsigned int line,
                                    handle_t *handle, struct buffer_head *bh);

int __ext4_forget(const char *where, unsigned int line, handle_t *handle,
                  int is_metadata, struct inode *inode,
                  struct buffer_head *bh, ext4_fsblk_t blocknr);

int __ext4_journal_get_create_access(const char *where, unsigned int line,
                                handle_t *handle, struct buffer_head *bh);

int __ext4_handle_dirty_metadata(const char *where, unsigned int line,
                                 handle_t *handle, struct inode *inode,
                                 struct buffer_head *bh);

int __ext4_handle_dirty_super(const char *where, unsigned int line,
                              handle_t *handle, struct super_block *sb);

#define ext4_journal_get_write_access(handle, bh) \
        __ext4_journal_get_write_access(__func__, __LINE__, (handle), (bh))
#define ext4_forget(handle, is_metadata, inode, bh, block_nr) \
        __ext4_forget(__func__, __LINE__, (handle), (is_metadata), (inode), \
                      (bh), (block_nr))
#define ext4_journal_get_create_access(handle, bh) \
        __ext4_journal_get_create_access(__func__, __LINE__, (handle), (bh))
#define ext4_handle_dirty_metadata(handle, inode, bh) \
        __ext4_handle_dirty_metadata(__func__, __LINE__, (handle), (inode), \
                                     (bh))
#define ext4_handle_dirty_super(handle, sb) \
        __ext4_handle_dirty_super(__func__, __LINE__, (handle), (sb))

handle_t *ext4_journal_start_sb(struct super_block *sb, int nblocks);
int __ext4_journal_stop(const char *where, unsigned int line, handle_t *handle);

#define EXT4_NOJOURNAL_MAX_REF_COUNT ((unsigned long) 4096)

/* Note:  Do not use this for NULL handles.  This is only to determine if
 * a properly allocated handle is using a journal or not. */
static inline int ext4_handle_valid(handle_t *handle)
{
        if ((unsigned long)handle < EXT4_NOJOURNAL_MAX_REF_COUNT)
                return 0;
        return 1;
}

static inline void ext4_handle_sync(handle_t *handle)
{
        if (ext4_handle_valid(handle))
                handle->h_sync = 1;
}

static inline int ext4_handle_is_aborted(handle_t *handle)
{
        if (ext4_handle_valid(handle))
                return is_handle_aborted(handle);
        return 0;
}

static inline int ext4_handle_has_enough_credits(handle_t *handle, int needed)
{
        if (ext4_handle_valid(handle) && handle->h_buffer_credits < needed)
                return 0;
        return 1;
}

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(__func__, __LINE__, (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)
{
        if (ext4_handle_valid(handle))
                return jbd2_journal_extend(handle, nblocks);
        return 0;
}

static inline int ext4_journal_restart(handle_t *handle, int nblocks)
{
        if (ext4_handle_valid(handle))
                return jbd2_journal_restart(handle, nblocks);
        return 0;
}

static inline int ext4_journal_blocks_per_page(struct inode *inode)
{
        if (EXT4_JOURNAL(inode) != NULL)
                return jbd2_journal_blocks_per_page(inode);
        return 0;
}

static inline int ext4_journal_force_commit(journal_t *journal)
{
        if (journal)
                return jbd2_journal_force_commit(journal);
        return 0;
}

static inline int ext4_jbd2_file_inode(handle_t *handle, struct inode *inode)
{
        if (ext4_handle_valid(handle))
                return jbd2_journal_file_inode(handle, EXT4_I(inode)->jinode);
        return 0;
}

static inline void ext4_update_inode_fsync_trans(handle_t *handle,
                                                 struct inode *inode,
                                                 int datasync)
{
        struct ext4_inode_info *ei = EXT4_I(inode);

        if (ext4_handle_valid(handle)) {
                ei->i_sync_tid = handle->h_transaction->t_tid;
                if (datasync)
                        ei->i_datasync_tid = handle->h_transaction->t_tid;
        }
}

/* super.c */
int ext4_force_commit(struct super_block *sb);

/*
 * Ext4 inode journal modes
 */
#define EXT4_INODE_JOURNAL_DATA_MODE    0x01 /* journal data mode */
#define EXT4_INODE_ORDERED_DATA_MODE    0x02 /* ordered data mode */
#define EXT4_INODE_WRITEBACK_DATA_MODE  0x04 /* writeback data mode */

static inline int ext4_inode_journal_mode(struct inode *inode)
{
        if (EXT4_JOURNAL(inode) == NULL)
                return EXT4_INODE_WRITEBACK_DATA_MODE;  /* writeback */
        /* We do not support data journalling with delayed allocation */
        if (!S_ISREG(inode->i_mode) ||
            test_opt(inode->i_sb, DATA_FLAGS) == EXT4_MOUNT_JOURNAL_DATA)
                return EXT4_INODE_JOURNAL_DATA_MODE;    /* journal data */
        if (ext4_test_inode_flag(inode, EXT4_INODE_JOURNAL_DATA) &&
            !test_opt(inode->i_sb, DELALLOC))
                return EXT4_INODE_JOURNAL_DATA_MODE;    /* journal data */
        if (test_opt(inode->i_sb, DATA_FLAGS) == EXT4_MOUNT_ORDERED_DATA)
                return EXT4_INODE_ORDERED_DATA_MODE;    /* ordered */
        if (test_opt(inode->i_sb, DATA_FLAGS) == EXT4_MOUNT_WRITEBACK_DATA)
                return EXT4_INODE_WRITEBACK_DATA_MODE;  /* writeback */
        else
                BUG();
}

static inline int ext4_should_journal_data(struct inode *inode)
{
        return ext4_inode_journal_mode(inode) & EXT4_INODE_JOURNAL_DATA_MODE;
}

static inline int ext4_should_order_data(struct inode *inode)
{
        return ext4_inode_journal_mode(inode) & EXT4_INODE_ORDERED_DATA_MODE;
}

static inline int ext4_should_writeback_data(struct inode *inode)
{
        return ext4_inode_journal_mode(inode) & EXT4_INODE_WRITEBACK_DATA_MODE;
}

/*
 * This function controls whether or not we should try to go down the
 * dioread_nolock code paths, which makes it safe to avoid taking
 * i_mutex for direct I/O reads.  This only works for extent-based
 * files, and it doesn't work if data journaling is enabled, since the
 * dioread_nolock code uses b_private to pass information back to the
 * I/O completion handler, and this conflicts with the jbd's use of
 * b_private.
 */
static inline int ext4_should_dioread_nolock(struct inode *inode)
{
        if (!test_opt(inode->i_sb, DIOREAD_NOLOCK))
                return 0;
        if (!S_ISREG(inode->i_mode))
                return 0;
        if (!(ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS)))
                return 0;
        if (ext4_should_journal_data(inode))
                return 0;
        return 1;
}

#endif  /* _EXT4_JBD2_H */