nilfs2: clean up indirect function calling conventions

[linux-2.6/mini2440.git] / fs / nilfs2 / bmap.c

/*
 * bmap.c - NILFS block mapping.
 *
 * Copyright (C) 2006-2008 Nippon Telegraph and Telephone Corporation.
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
 *
 * Written by Koji Sato <koji@osrg.net>.
 */

#include <linux/fs.h>
#include <linux/string.h>
#include <linux/errno.h>
#include "nilfs.h"
#include "bmap.h"
#include "sb.h"
#include "btnode.h"
#include "mdt.h"
#include "dat.h"
#include "alloc.h"

int nilfs_bmap_lookup_at_level(struct nilfs_bmap *bmap, __u64 key, int level,
                               __u64 *ptrp)
{
        __u64 ptr;
        int ret;

        down_read(&bmap->b_sem);
        ret = bmap->b_ops->bop_lookup(bmap, key, level, ptrp);
        if (ret < 0)
                goto out;
        if (bmap->b_pops->bpop_translate != NULL) {
                ret = bmap->b_pops->bpop_translate(bmap, *ptrp, &ptr);
                if (ret < 0)
                        goto out;
                *ptrp = ptr;
        }

 out:
        up_read(&bmap->b_sem);
        return ret;
}


/**
 * nilfs_bmap_lookup - find a record
 * @bmap: bmap
 * @key: key
 * @recp: pointer to record
 *
 * Description: nilfs_bmap_lookup() finds a record whose key matches @key in
 * @bmap.
 *
 * Return Value: On success, 0 is returned and the record associated with @key
 * is stored in the place pointed by @recp. On error, one of the following
 * negative error codes is returned.
 *
 * %-EIO - I/O error.
 *
 * %-ENOMEM - Insufficient amount of memory available.
 *
 * %-ENOENT - A record associated with @key does not exist.
 */
int nilfs_bmap_lookup(struct nilfs_bmap *bmap,
                      unsigned long key,
                      unsigned long *recp)
{
        __u64 ptr;
        int ret;

        /* XXX: use macro for level 1 */
        ret = nilfs_bmap_lookup_at_level(bmap, key, 1, &ptr);
        if (recp != NULL)
                *recp = ptr;
        return ret;
}

static int nilfs_bmap_do_insert(struct nilfs_bmap *bmap, __u64 key, __u64 ptr)
{
        __u64 keys[NILFS_BMAP_SMALL_HIGH + 1];
        __u64 ptrs[NILFS_BMAP_SMALL_HIGH + 1];
        int ret, n;

        if (bmap->b_ops->bop_check_insert != NULL) {
                ret = bmap->b_ops->bop_check_insert(bmap, key);
                if (ret > 0) {
                        n = bmap->b_ops->bop_gather_data(
                                bmap, keys, ptrs, NILFS_BMAP_SMALL_HIGH + 1);
                        if (n < 0)
                                return n;
                        ret = nilfs_btree_convert_and_insert(
                                bmap, key, ptr, keys, ptrs, n,
                                NILFS_BMAP_LARGE_LOW, NILFS_BMAP_LARGE_HIGH);
                        if (ret == 0)
                                bmap->b_u.u_flags |= NILFS_BMAP_LARGE;

                        return ret;
                } else if (ret < 0)
                        return ret;
        }

        return bmap->b_ops->bop_insert(bmap, key, ptr);
}

/**
 * nilfs_bmap_insert - insert a new key-record pair into a bmap
 * @bmap: bmap
 * @key: key
 * @rec: record
 *
 * Description: nilfs_bmap_insert() inserts the new key-record pair specified
 * by @key and @rec into @bmap.
 *
 * Return Value: On success, 0 is returned. On error, one of the following
 * negative error codes is returned.
 *
 * %-EIO - I/O error.
 *
 * %-ENOMEM - Insufficient amount of memory available.
 *
 * %-EEXIST - A record associated with @key already exist.
 */
int nilfs_bmap_insert(struct nilfs_bmap *bmap,
                      unsigned long key,
                      unsigned long rec)
{
        int ret;

        down_write(&bmap->b_sem);
        ret = nilfs_bmap_do_insert(bmap, key, rec);
        up_write(&bmap->b_sem);
        return ret;
}

static int nilfs_bmap_do_delete(struct nilfs_bmap *bmap, __u64 key)
{
        __u64 keys[NILFS_BMAP_LARGE_LOW + 1];
        __u64 ptrs[NILFS_BMAP_LARGE_LOW + 1];
        int ret, n;

        if (bmap->b_ops->bop_check_delete != NULL) {
                ret = bmap->b_ops->bop_check_delete(bmap, key);
                if (ret > 0) {
                        n = bmap->b_ops->bop_gather_data(
                                bmap, keys, ptrs, NILFS_BMAP_LARGE_LOW + 1);
                        if (n < 0)
                                return n;
                        ret = nilfs_direct_delete_and_convert(
                                bmap, key, keys, ptrs, n,
                                NILFS_BMAP_SMALL_LOW, NILFS_BMAP_SMALL_HIGH);
                        if (ret == 0)
                                bmap->b_u.u_flags &= ~NILFS_BMAP_LARGE;

                        return ret;
                } else if (ret < 0)
                        return ret;
        }

        return bmap->b_ops->bop_delete(bmap, key);
}

int nilfs_bmap_last_key(struct nilfs_bmap *bmap, unsigned long *key)
{
        __u64 lastkey;
        int ret;

        down_read(&bmap->b_sem);
        ret = bmap->b_ops->bop_last_key(bmap, &lastkey);
        if (!ret)
                *key = lastkey;
        up_read(&bmap->b_sem);
        return ret;
}

/**
 * nilfs_bmap_delete - delete a key-record pair from a bmap
 * @bmap: bmap
 * @key: key
 *
 * Description: nilfs_bmap_delete() deletes the key-record pair specified by
 * @key from @bmap.
 *
 * Return Value: On success, 0 is returned. On error, one of the following
 * negative error codes is returned.
 *
 * %-EIO - I/O error.
 *
 * %-ENOMEM - Insufficient amount of memory available.
 *
 * %-ENOENT - A record associated with @key does not exist.
 */
int nilfs_bmap_delete(struct nilfs_bmap *bmap, unsigned long key)
{
        int ret;

        down_write(&bmap->b_sem);
        ret = nilfs_bmap_do_delete(bmap, key);
        up_write(&bmap->b_sem);
        return ret;
}

static int nilfs_bmap_do_truncate(struct nilfs_bmap *bmap, unsigned long key)
{
        __u64 lastkey;
        int ret;

        ret = bmap->b_ops->bop_last_key(bmap, &lastkey);
        if (ret < 0) {
                if (ret == -ENOENT)
                        ret = 0;
                return ret;
        }

        while (key <= lastkey) {
                ret = nilfs_bmap_do_delete(bmap, lastkey);
                if (ret < 0)
                        return ret;
                ret = bmap->b_ops->bop_last_key(bmap, &lastkey);
                if (ret < 0) {
                        if (ret == -ENOENT)
                                ret = 0;
                        return ret;
                }
        }
        return 0;
}

/**
 * nilfs_bmap_truncate - truncate a bmap to a specified key
 * @bmap: bmap
 * @key: key
 *
 * Description: nilfs_bmap_truncate() removes key-record pairs whose keys are
 * greater than or equal to @key from @bmap.
 *
 * Return Value: On success, 0 is returned. On error, one of the following
 * negative error codes is returned.
 *
 * %-EIO - I/O error.
 *
 * %-ENOMEM - Insufficient amount of memory available.
 */
int nilfs_bmap_truncate(struct nilfs_bmap *bmap, unsigned long key)
{
        int ret;

        down_write(&bmap->b_sem);
        ret = nilfs_bmap_do_truncate(bmap, key);
        up_write(&bmap->b_sem);
        return ret;
}

/**
 * nilfs_bmap_clear - free resources a bmap holds
 * @bmap: bmap
 *
 * Description: nilfs_bmap_clear() frees resources associated with @bmap.
 */
void nilfs_bmap_clear(struct nilfs_bmap *bmap)
{
        down_write(&bmap->b_sem);
        if (bmap->b_ops->bop_clear != NULL)
                bmap->b_ops->bop_clear(bmap);
        up_write(&bmap->b_sem);
}

/**
 * nilfs_bmap_propagate - propagate dirty state
 * @bmap: bmap
 * @bh: buffer head
 *
 * Description: nilfs_bmap_propagate() marks the buffers that directly or
 * indirectly refer to the block specified by @bh dirty.
 *
 * Return Value: On success, 0 is returned. On error, one of the following
 * negative error codes is returned.
 *
 * %-EIO - I/O error.
 *
 * %-ENOMEM - Insufficient amount of memory available.
 */
int nilfs_bmap_propagate(struct nilfs_bmap *bmap, struct buffer_head *bh)
{
        int ret;

        down_write(&bmap->b_sem);
        ret = bmap->b_ops->bop_propagate(bmap, bh);
        up_write(&bmap->b_sem);
        return ret;
}

/**
 * nilfs_bmap_lookup_dirty_buffers -
 * @bmap: bmap
 * @listp: pointer to buffer head list
 */
void nilfs_bmap_lookup_dirty_buffers(struct nilfs_bmap *bmap,
                                     struct list_head *listp)
{
        if (bmap->b_ops->bop_lookup_dirty_buffers != NULL)
                bmap->b_ops->bop_lookup_dirty_buffers(bmap, listp);
}

/**
 * nilfs_bmap_assign - assign a new block number to a block
 * @bmap: bmap
 * @bhp: pointer to buffer head
 * @blocknr: block number
 * @binfo: block information
 *
 * Description: nilfs_bmap_assign() assigns the block number @blocknr to the
 * buffer specified by @bh.
 *
 * Return Value: On success, 0 is returned and the buffer head of a newly
 * create buffer and the block information associated with the buffer are
 * stored in the place pointed by @bh and @binfo, respectively. On error, one
 * of the following negative error codes is returned.
 *
 * %-EIO - I/O error.
 *
 * %-ENOMEM - Insufficient amount of memory available.
 */
int nilfs_bmap_assign(struct nilfs_bmap *bmap,
                      struct buffer_head **bh,
                      unsigned long blocknr,
                      union nilfs_binfo *binfo)
{
        int ret;

        down_write(&bmap->b_sem);
        ret = bmap->b_ops->bop_assign(bmap, bh, blocknr, binfo);
        up_write(&bmap->b_sem);
        return ret;
}

/**
 * nilfs_bmap_mark - mark block dirty
 * @bmap: bmap
 * @key: key
 * @level: level
 *
 * Description: nilfs_bmap_mark() marks the block specified by @key and @level
 * as dirty.
 *
 * Return Value: On success, 0 is returned. On error, one of the following
 * negative error codes is returned.
 *
 * %-EIO - I/O error.
 *
 * %-ENOMEM - Insufficient amount of memory available.
 */
int nilfs_bmap_mark(struct nilfs_bmap *bmap, __u64 key, int level)
{
        int ret;

        if (bmap->b_ops->bop_mark == NULL)
                return 0;

        down_write(&bmap->b_sem);
        ret = bmap->b_ops->bop_mark(bmap, key, level);
        up_write(&bmap->b_sem);
        return ret;
}

/**
 * nilfs_bmap_test_and_clear_dirty - test and clear a bmap dirty state
 * @bmap: bmap
 *
 * Description: nilfs_test_and_clear() is the atomic operation to test and
 * clear the dirty state of @bmap.
 *
 * Return Value: 1 is returned if @bmap is dirty, or 0 if clear.
 */
int nilfs_bmap_test_and_clear_dirty(struct nilfs_bmap *bmap)
{
        int ret;

        down_write(&bmap->b_sem);
        ret = nilfs_bmap_dirty(bmap);
        nilfs_bmap_clear_dirty(bmap);
        up_write(&bmap->b_sem);
        return ret;
}


/*
 * Internal use only
 */

void nilfs_bmap_add_blocks(const struct nilfs_bmap *bmap, int n)
{
        inode_add_bytes(bmap->b_inode, (1 << bmap->b_inode->i_blkbits) * n);
        if (NILFS_MDT(bmap->b_inode))
                nilfs_mdt_mark_dirty(bmap->b_inode);
        else
                mark_inode_dirty(bmap->b_inode);
}

void nilfs_bmap_sub_blocks(const struct nilfs_bmap *bmap, int n)
{
        inode_sub_bytes(bmap->b_inode, (1 << bmap->b_inode->i_blkbits) * n);
        if (NILFS_MDT(bmap->b_inode))
                nilfs_mdt_mark_dirty(bmap->b_inode);
        else
                mark_inode_dirty(bmap->b_inode);
}

int nilfs_bmap_get_block(const struct nilfs_bmap *bmap, __u64 ptr,
                         struct buffer_head **bhp)
{
        return nilfs_btnode_get(&NILFS_BMAP_I(bmap)->i_btnode_cache,
                                ptr, 0, bhp, 0);
}

void nilfs_bmap_put_block(const struct nilfs_bmap *bmap,
                          struct buffer_head *bh)
{
        brelse(bh);
}

int nilfs_bmap_get_new_block(const struct nilfs_bmap *bmap, __u64 ptr,
                             struct buffer_head **bhp)
{
        int ret;

        ret = nilfs_btnode_get(&NILFS_BMAP_I(bmap)->i_btnode_cache,
                               ptr, 0, bhp, 1);
        if (ret < 0)
                return ret;
        set_buffer_nilfs_volatile(*bhp);
        return 0;
}

void nilfs_bmap_delete_block(const struct nilfs_bmap *bmap,
                             struct buffer_head *bh)
{
        nilfs_btnode_delete(bh);
}

__u64 nilfs_bmap_data_get_key(const struct nilfs_bmap *bmap,
                              const struct buffer_head *bh)
{
        struct buffer_head *pbh;
        __u64 key;

        key = page_index(bh->b_page) << (PAGE_CACHE_SHIFT -
                                         bmap->b_inode->i_blkbits);
        for (pbh = page_buffers(bh->b_page); pbh != bh;
             pbh = pbh->b_this_page, key++);

        return key;
}

__u64 nilfs_bmap_find_target_seq(const struct nilfs_bmap *bmap, __u64 key)
{
        __s64 diff;

        diff = key - bmap->b_last_allocated_key;
        if ((nilfs_bmap_keydiff_abs(diff) < NILFS_INODE_BMAP_SIZE) &&
            (bmap->b_last_allocated_ptr != NILFS_BMAP_INVALID_PTR) &&
            (bmap->b_last_allocated_ptr + diff > 0))
                return bmap->b_last_allocated_ptr + diff;
        else
                return NILFS_BMAP_INVALID_PTR;
}

static struct inode *nilfs_bmap_get_dat(const struct nilfs_bmap *bmap)
{
        return nilfs_dat_inode(NILFS_I_NILFS(bmap->b_inode));
}

#define NILFS_BMAP_GROUP_DIV    8
__u64 nilfs_bmap_find_target_in_group(const struct nilfs_bmap *bmap)
{
        struct inode *dat = nilfs_bmap_get_dat(bmap);
        unsigned long entries_per_group = nilfs_palloc_entries_per_group(dat);
        unsigned long group = bmap->b_inode->i_ino / entries_per_group;

        return group * entries_per_group +
                (bmap->b_inode->i_ino % NILFS_BMAP_GROUP_DIV) *
                (entries_per_group / NILFS_BMAP_GROUP_DIV);
}

static int nilfs_bmap_prepare_alloc_v(struct nilfs_bmap *bmap,
                                      union nilfs_bmap_ptr_req *req)
{
        return nilfs_dat_prepare_alloc(nilfs_bmap_get_dat(bmap), &req->bpr_req);
}

static void nilfs_bmap_commit_alloc_v(struct nilfs_bmap *bmap,
                                      union nilfs_bmap_ptr_req *req)
{
        nilfs_dat_commit_alloc(nilfs_bmap_get_dat(bmap), &req->bpr_req);
}

static void nilfs_bmap_abort_alloc_v(struct nilfs_bmap *bmap,
                                     union nilfs_bmap_ptr_req *req)
{
        nilfs_dat_abort_alloc(nilfs_bmap_get_dat(bmap), &req->bpr_req);
}

static int nilfs_bmap_prepare_start_v(struct nilfs_bmap *bmap,
                                      union nilfs_bmap_ptr_req *req)
{
        return nilfs_dat_prepare_start(nilfs_bmap_get_dat(bmap), &req->bpr_req);
}

static void nilfs_bmap_commit_start_v(struct nilfs_bmap *bmap,
                                      union nilfs_bmap_ptr_req *req,
                                      sector_t blocknr)
{
        nilfs_dat_commit_start(nilfs_bmap_get_dat(bmap), &req->bpr_req,
                               blocknr);
}

static void nilfs_bmap_abort_start_v(struct nilfs_bmap *bmap,
                                     union nilfs_bmap_ptr_req *req)
{
        nilfs_dat_abort_start(nilfs_bmap_get_dat(bmap), &req->bpr_req);
}

static int nilfs_bmap_prepare_end_v(struct nilfs_bmap *bmap,
                                    union nilfs_bmap_ptr_req *req)
{
        return nilfs_dat_prepare_end(nilfs_bmap_get_dat(bmap), &req->bpr_req);
}

static void nilfs_bmap_commit_end_v(struct nilfs_bmap *bmap,
                                    union nilfs_bmap_ptr_req *req)
{
        nilfs_dat_commit_end(nilfs_bmap_get_dat(bmap), &req->bpr_req, 0);
}

static void nilfs_bmap_commit_end_vmdt(struct nilfs_bmap *bmap,
                                       union nilfs_bmap_ptr_req *req)
{
        nilfs_dat_commit_end(nilfs_bmap_get_dat(bmap), &req->bpr_req, 1);
}

static void nilfs_bmap_abort_end_v(struct nilfs_bmap *bmap,
                                   union nilfs_bmap_ptr_req *req)
{
        nilfs_dat_abort_end(nilfs_bmap_get_dat(bmap), &req->bpr_req);
}

int nilfs_bmap_move_v(const struct nilfs_bmap *bmap, __u64 vblocknr,
                      sector_t blocknr)
{
        return nilfs_dat_move(nilfs_bmap_get_dat(bmap), vblocknr, blocknr);
}

int nilfs_bmap_mark_dirty(const struct nilfs_bmap *bmap, __u64 vblocknr)
{
        return nilfs_dat_mark_dirty(nilfs_bmap_get_dat(bmap), vblocknr);
}

int nilfs_bmap_prepare_update(struct nilfs_bmap *bmap,
                              union nilfs_bmap_ptr_req *oldreq,
                              union nilfs_bmap_ptr_req *newreq)
{
        int ret;

        ret = bmap->b_pops->bpop_prepare_end_ptr(bmap, oldreq);
        if (ret < 0)
                return ret;
        ret = bmap->b_pops->bpop_prepare_alloc_ptr(bmap, newreq);
        if (ret < 0)
                bmap->b_pops->bpop_abort_end_ptr(bmap, oldreq);

        return ret;
}

void nilfs_bmap_commit_update(struct nilfs_bmap *bmap,
                              union nilfs_bmap_ptr_req *oldreq,
                              union nilfs_bmap_ptr_req *newreq)
{
        bmap->b_pops->bpop_commit_end_ptr(bmap, oldreq);
        bmap->b_pops->bpop_commit_alloc_ptr(bmap, newreq);
}

void nilfs_bmap_abort_update(struct nilfs_bmap *bmap,
                             union nilfs_bmap_ptr_req *oldreq,
                             union nilfs_bmap_ptr_req *newreq)
{
        bmap->b_pops->bpop_abort_end_ptr(bmap, oldreq);
        bmap->b_pops->bpop_abort_alloc_ptr(bmap, newreq);
}

static int nilfs_bmap_translate_v(const struct nilfs_bmap *bmap, __u64 ptr,
                                  __u64 *ptrp)
{
        sector_t blocknr;
        int ret;

        ret = nilfs_dat_translate(nilfs_bmap_get_dat(bmap), ptr, &blocknr);
        if (ret < 0)
                return ret;
        if (ptrp != NULL)
                *ptrp = blocknr;
        return 0;
}

static int nilfs_bmap_prepare_alloc_p(struct nilfs_bmap *bmap,
                                      union nilfs_bmap_ptr_req *req)
{
        /* ignore target ptr */
        req->bpr_ptr = bmap->b_last_allocated_ptr++;
        return 0;
}

static void nilfs_bmap_commit_alloc_p(struct nilfs_bmap *bmap,
                                      union nilfs_bmap_ptr_req *req)
{
        /* do nothing */
}

static void nilfs_bmap_abort_alloc_p(struct nilfs_bmap *bmap,
                                     union nilfs_bmap_ptr_req *req)
{
        bmap->b_last_allocated_ptr--;
}

static const struct nilfs_bmap_ptr_operations nilfs_bmap_ptr_ops_v = {
        .bpop_prepare_alloc_ptr =       nilfs_bmap_prepare_alloc_v,
        .bpop_commit_alloc_ptr  =       nilfs_bmap_commit_alloc_v,
        .bpop_abort_alloc_ptr   =       nilfs_bmap_abort_alloc_v,
        .bpop_prepare_start_ptr =       nilfs_bmap_prepare_start_v,
        .bpop_commit_start_ptr  =       nilfs_bmap_commit_start_v,
        .bpop_abort_start_ptr   =       nilfs_bmap_abort_start_v,
        .bpop_prepare_end_ptr   =       nilfs_bmap_prepare_end_v,
        .bpop_commit_end_ptr    =       nilfs_bmap_commit_end_v,
        .bpop_abort_end_ptr     =       nilfs_bmap_abort_end_v,

        .bpop_translate         =       nilfs_bmap_translate_v,
};

static const struct nilfs_bmap_ptr_operations nilfs_bmap_ptr_ops_vmdt = {
        .bpop_prepare_alloc_ptr =       nilfs_bmap_prepare_alloc_v,
        .bpop_commit_alloc_ptr  =       nilfs_bmap_commit_alloc_v,
        .bpop_abort_alloc_ptr   =       nilfs_bmap_abort_alloc_v,
        .bpop_prepare_start_ptr =       nilfs_bmap_prepare_start_v,
        .bpop_commit_start_ptr  =       nilfs_bmap_commit_start_v,
        .bpop_abort_start_ptr   =       nilfs_bmap_abort_start_v,
        .bpop_prepare_end_ptr   =       nilfs_bmap_prepare_end_v,
        .bpop_commit_end_ptr    =       nilfs_bmap_commit_end_vmdt,
        .bpop_abort_end_ptr     =       nilfs_bmap_abort_end_v,

        .bpop_translate         =       nilfs_bmap_translate_v,
};

static const struct nilfs_bmap_ptr_operations nilfs_bmap_ptr_ops_p = {
        .bpop_prepare_alloc_ptr =       nilfs_bmap_prepare_alloc_p,
        .bpop_commit_alloc_ptr  =       nilfs_bmap_commit_alloc_p,
        .bpop_abort_alloc_ptr   =       nilfs_bmap_abort_alloc_p,
        .bpop_prepare_start_ptr =       NULL,
        .bpop_commit_start_ptr  =       NULL,
        .bpop_abort_start_ptr   =       NULL,
        .bpop_prepare_end_ptr   =       NULL,
        .bpop_commit_end_ptr    =       NULL,
        .bpop_abort_end_ptr     =       NULL,

        .bpop_translate         =       NULL,
};

static const struct nilfs_bmap_ptr_operations nilfs_bmap_ptr_ops_gc = {
        .bpop_prepare_alloc_ptr =       NULL,
        .bpop_commit_alloc_ptr  =       NULL,
        .bpop_abort_alloc_ptr   =       NULL,
        .bpop_prepare_start_ptr =       NULL,
        .bpop_commit_start_ptr  =       NULL,
        .bpop_abort_start_ptr   =       NULL,
        .bpop_prepare_end_ptr   =       NULL,
        .bpop_commit_end_ptr    =       NULL,
        .bpop_abort_end_ptr     =       NULL,

        .bpop_translate         =       NULL,
};

/**
 * nilfs_bmap_read - read a bmap from an inode
 * @bmap: bmap
 * @raw_inode: on-disk inode
 *
 * Description: nilfs_bmap_read() initializes the bmap @bmap.
 *
 * Return Value: On success, 0 is returned. On error, the following negative
 * error code is returned.
 *
 * %-ENOMEM - Insufficient amount of memory available.
 */
int nilfs_bmap_read(struct nilfs_bmap *bmap, struct nilfs_inode *raw_inode)
{
        if (raw_inode == NULL)
                memset(bmap->b_u.u_data, 0, NILFS_BMAP_SIZE);
        else
                memcpy(bmap->b_u.u_data, raw_inode->i_bmap, NILFS_BMAP_SIZE);

        init_rwsem(&bmap->b_sem);
        bmap->b_state = 0;
        bmap->b_inode = &NILFS_BMAP_I(bmap)->vfs_inode;
        switch (bmap->b_inode->i_ino) {
        case NILFS_DAT_INO:
                bmap->b_pops = &nilfs_bmap_ptr_ops_p;
                bmap->b_last_allocated_key = 0; /* XXX: use macro */
                bmap->b_last_allocated_ptr = NILFS_BMAP_NEW_PTR_INIT;
                break;
        case NILFS_CPFILE_INO:
        case NILFS_SUFILE_INO:
                bmap->b_pops = &nilfs_bmap_ptr_ops_vmdt;
                bmap->b_last_allocated_key = 0; /* XXX: use macro */
                bmap->b_last_allocated_ptr = NILFS_BMAP_INVALID_PTR;
                break;
        default:
                bmap->b_pops = &nilfs_bmap_ptr_ops_v;
                bmap->b_last_allocated_key = 0; /* XXX: use macro */
                bmap->b_last_allocated_ptr = NILFS_BMAP_INVALID_PTR;
                break;
        }

        return (bmap->b_u.u_flags & NILFS_BMAP_LARGE) ?
                nilfs_btree_init(bmap,
                                 NILFS_BMAP_LARGE_LOW,
                                 NILFS_BMAP_LARGE_HIGH) :
                nilfs_direct_init(bmap,
                                  NILFS_BMAP_SMALL_LOW,
                                  NILFS_BMAP_SMALL_HIGH);
}

/**
 * nilfs_bmap_write - write back a bmap to an inode
 * @bmap: bmap
 * @raw_inode: on-disk inode
 *
 * Description: nilfs_bmap_write() stores @bmap in @raw_inode.
 */
void nilfs_bmap_write(struct nilfs_bmap *bmap, struct nilfs_inode *raw_inode)
{
        down_write(&bmap->b_sem);
        memcpy(raw_inode->i_bmap, bmap->b_u.u_data,
               NILFS_INODE_BMAP_SIZE * sizeof(__le64));
        if (bmap->b_inode->i_ino == NILFS_DAT_INO)
                bmap->b_last_allocated_ptr = NILFS_BMAP_NEW_PTR_INIT;

        up_write(&bmap->b_sem);
}

void nilfs_bmap_init_gc(struct nilfs_bmap *bmap)
{
        memset(&bmap->b_u, 0, NILFS_BMAP_SIZE);
        init_rwsem(&bmap->b_sem);
        bmap->b_inode = &NILFS_BMAP_I(bmap)->vfs_inode;
        bmap->b_pops = &nilfs_bmap_ptr_ops_gc;
        bmap->b_last_allocated_key = 0;
        bmap->b_last_allocated_ptr = NILFS_BMAP_INVALID_PTR;
        bmap->b_state = 0;
        nilfs_btree_init_gc(bmap);
}

void nilfs_bmap_init_gcdat(struct nilfs_bmap *gcbmap, struct nilfs_bmap *bmap)
{
        memcpy(gcbmap, bmap, sizeof(union nilfs_bmap_union));
        init_rwsem(&gcbmap->b_sem);
        gcbmap->b_inode = &NILFS_BMAP_I(gcbmap)->vfs_inode;
}

void nilfs_bmap_commit_gcdat(struct nilfs_bmap *gcbmap, struct nilfs_bmap *bmap)
{
        memcpy(bmap, gcbmap, sizeof(union nilfs_bmap_union));
        init_rwsem(&bmap->b_sem);
        bmap->b_inode = &NILFS_BMAP_I(bmap)->vfs_inode;
}