nilfs2: integrated block mapping

This adds structures and operations for the block mapping (bmap for
short).  NILFS2 uses direct mappings for short files or B-tree based
mappings for longer files.

Every on-disk data block is held with inodes and managed through this
block mapping.  The nilfs_bmap structure and a set of functions here
provide this capability to the NILFS2 inode.

[penberg@cs.helsinki.fi: remove a bunch of bmap wrapper macros]
[akpm@linux-foundation.org: coding-style fixes]
Signed-off-by: Koji Sato <sato.koji@lab.ntt.co.jp>
Signed-off-by: Ryusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>
Signed-off-by: Pekka Enberg <penberg@cs.helsinki.fi>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 783 insertions, 0 deletions

diff --git a/fs/nilfs2/bmap.c b/fs/nilfs2/bmap.c
new file mode 100644
index 000000000000..6fe72addc9c5
--- /dev/null
+++ b/fs/nilfs2/bmap.c
@@ -0,0 +1,783 @@
+/*
+ * 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;
+}