diff --git a/fs/nilfs2/gcinode.c b/fs/nilfs2/gcinode.c
new file mode 100644
index 0000000..0013952
--- /dev/null
+++ b/fs/nilfs2/gcinode.c
@@ -0,0 +1,270 @@
+/*
+ * gcinode.c - NILFS memory inode for GC
+ *
+ * Copyright (C) 2005-2008 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 Seiji Kihara <kihara@osrg.net>, Amagai Yoshiji <amagai@osrg.net>,
+ *            and Ryusuke Konishi <ryusuke@osrg.net>.
+ * Revised by Ryusuke Konishi <ryusuke@osrg.net>.
+ *
+ */
+
+#include <linux/buffer_head.h>
+#include <linux/mpage.h>
+#include <linux/hash.h>
+#include <linux/swap.h>
+#include "nilfs.h"
+#include "page.h"
+#include "mdt.h"
+#include "dat.h"
+#include "ifile.h"
+
+static struct address_space_operations def_gcinode_aops = {};
+/* XXX need def_gcinode_iops/fops? */
+
+/*
+ * nilfs_gccache_submit_read_data() - add data buffer and submit read request
+ * @inode - gc inode
+ * @blkoff - dummy offset treated as the key for the page cache
+ * @pbn - physical block number of the block
+ * @vbn - virtual block number of the block, 0 for non-virtual block
+ * @out_bh - indirect pointer to a buffer_head struct to receive the results
+ *
+ * Description: nilfs_gccache_submit_read_data() registers the data buffer
+ * specified by @pbn to the GC pagecache with the key @blkoff.
+ * This function sets @vbn (@pbn if @vbn is zero) in b_blocknr of the buffer.
+ *
+ * Return Value: On success, 0 is returned. On Error, one of the following
+ * negative error code is returned.
+ *
+ * %-EIO - I/O error.
+ *
+ * %-ENOMEM - Insufficient amount of memory available.
+ *
+ * %-ENOENT - The block specified with @pbn does not exist.
+ */
+int nilfs_gccache_submit_read_data(struct inode *inode, sector_t blkoff,
+				   sector_t pbn, __u64 vbn,
+				   struct buffer_head **out_bh)
+{
+	struct buffer_head *bh;
+	int err;
+
+	bh = nilfs_grab_buffer(inode, inode->i_mapping, blkoff, 0);
+	if (unlikely(!bh))
+		return -ENOMEM;
+
+	if (buffer_uptodate(bh))
+		goto out;
+
+	if (pbn == 0) {
+		struct inode *dat_inode = NILFS_I_NILFS(inode)->ns_dat;
+					  /* use original dat, not gc dat. */
+		err = nilfs_dat_translate(dat_inode, vbn, &pbn);
+		if (unlikely(err)) { /* -EIO, -ENOMEM, -ENOENT */
+			brelse(bh);
+			goto failed;
+		}
+	}
+
+	lock_buffer(bh);
+	if (buffer_uptodate(bh)) {
+		unlock_buffer(bh);
+		goto out;
+	}
+
+	if (!buffer_mapped(bh)) {
+		bh->b_bdev = NILFS_I_NILFS(inode)->ns_bdev;
+		set_buffer_mapped(bh);
+	}
+	bh->b_blocknr = pbn;
+	bh->b_end_io = end_buffer_read_sync;
+	get_bh(bh);
+	submit_bh(READ, bh);
+	if (vbn)
+		bh->b_blocknr = vbn;
+ out:
+	err = 0;
+	*out_bh = bh;
+
+ failed:
+	unlock_page(bh->b_page);
+	page_cache_release(bh->b_page);
+	return err;
+}
+
+/*
+ * nilfs_gccache_submit_read_node() - add node buffer and submit read request
+ * @inode - gc inode
+ * @pbn - physical block number for the block
+ * @vbn - virtual block number for the block
+ * @out_bh - indirect pointer to a buffer_head struct to receive the results
+ *
+ * Description: nilfs_gccache_submit_read_node() registers the node buffer
+ * specified by @vbn to the GC pagecache.  @pbn can be supplied by the
+ * caller to avoid translation of the disk block address.
+ *
+ * Return Value: On success, 0 is returned. On Error, one of the following
+ * negative error code is returned.
+ *
+ * %-EIO - I/O error.
+ *
+ * %-ENOMEM - Insufficient amount of memory available.
+ */
+int nilfs_gccache_submit_read_node(struct inode *inode, sector_t pbn,
+				   __u64 vbn, struct buffer_head **out_bh)
+{
+	int ret = nilfs_btnode_submit_block(&NILFS_I(inode)->i_btnode_cache,
+					    vbn ? : pbn, pbn, out_bh, 0);
+	if (ret == -EEXIST) /* internal code (cache hit) */
+		ret = 0;
+	return ret;
+}
+
+int nilfs_gccache_wait_and_mark_dirty(struct buffer_head *bh)
+{
+	wait_on_buffer(bh);
+	if (!buffer_uptodate(bh))
+		return -EIO;
+	if (buffer_dirty(bh))
+		return -EEXIST;
+
+	if (buffer_nilfs_node(bh))
+		nilfs_btnode_mark_dirty(bh);
+	else
+		nilfs_mdt_mark_buffer_dirty(bh);
+	return 0;
+}
+
+/*
+ * nilfs_init_gccache() - allocate and initialize gc_inode hash table
+ * @nilfs - the_nilfs
+ *
+ * Return Value: On success, 0.
+ * On error, a negative error code is returned.
+ */
+int nilfs_init_gccache(struct the_nilfs *nilfs)
+{
+	int loop;
+
+	BUG_ON(nilfs->ns_gc_inodes_h);
+
+	INIT_LIST_HEAD(&nilfs->ns_gc_inodes);
+
+	nilfs->ns_gc_inodes_h =
+		kmalloc(sizeof(struct hlist_head) * NILFS_GCINODE_HASH_SIZE,
+			GFP_NOFS);
+	if (nilfs->ns_gc_inodes_h == NULL)
+		return -ENOMEM;
+
+	for (loop = 0; loop < NILFS_GCINODE_HASH_SIZE; loop++)
+		INIT_HLIST_HEAD(&nilfs->ns_gc_inodes_h[loop]);
+	return 0;
+}
+
+/*
+ * nilfs_destroy_gccache() - free gc_inode hash table
+ * @nilfs - the nilfs
+ */
+void nilfs_destroy_gccache(struct the_nilfs *nilfs)
+{
+	if (nilfs->ns_gc_inodes_h) {
+		nilfs_remove_all_gcinode(nilfs);
+		kfree(nilfs->ns_gc_inodes_h);
+		nilfs->ns_gc_inodes_h = NULL;
+	}
+}
+
+static struct inode *alloc_gcinode(struct the_nilfs *nilfs, ino_t ino,
+				   __u64 cno)
+{
+	struct inode *inode = nilfs_mdt_new_common(nilfs, NULL, ino, GFP_NOFS);
+	struct nilfs_inode_info *ii;
+
+	if (!inode)
+		return NULL;
+
+	inode->i_op = NULL;
+	inode->i_fop = NULL;
+	inode->i_mapping->a_ops = &def_gcinode_aops;
+
+	ii = NILFS_I(inode);
+	ii->i_cno = cno;
+	ii->i_flags = 0;
+	ii->i_state = 1 << NILFS_I_GCINODE;
+	ii->i_bh = NULL;
+	ii->i_dtime = 0;
+	nilfs_bmap_init_gc(ii->i_bmap);
+
+	return inode;
+}
+
+static unsigned long ihash(ino_t ino, __u64 cno)
+{
+	return hash_long((unsigned long)((ino << 2) + cno),
+			 NILFS_GCINODE_HASH_BITS);
+}
+
+/*
+ * nilfs_gc_iget() - find or create gc inode with specified (ino,cno)
+ */
+struct inode *nilfs_gc_iget(struct the_nilfs *nilfs, ino_t ino, __u64 cno)
+{
+	struct hlist_head *head = nilfs->ns_gc_inodes_h + ihash(ino, cno);
+	struct hlist_node *node;
+	struct inode *inode;
+
+	hlist_for_each_entry(inode, node, head, i_hash) {
+		if (inode->i_ino == ino && NILFS_I(inode)->i_cno == cno)
+			return inode;
+	}
+
+	inode = alloc_gcinode(nilfs, ino, cno);
+	if (likely(inode)) {
+		hlist_add_head(&inode->i_hash, head);
+		list_add(&NILFS_I(inode)->i_dirty, &nilfs->ns_gc_inodes);
+	}
+	return inode;
+}
+
+/*
+ * nilfs_clear_gcinode() - clear and free a gc inode
+ */
+void nilfs_clear_gcinode(struct inode *inode)
+{
+	nilfs_mdt_clear(inode);
+	nilfs_mdt_destroy(inode);
+}
+
+/*
+ * nilfs_remove_all_gcinode() - remove all inodes from the_nilfs
+ */
+void nilfs_remove_all_gcinode(struct the_nilfs *nilfs)
+{
+	struct hlist_head *head = nilfs->ns_gc_inodes_h;
+	struct hlist_node *node, *n;
+	struct inode *inode;
+	int loop;
+
+	for (loop = 0; loop < NILFS_GCINODE_HASH_SIZE; loop++, head++) {
+		hlist_for_each_entry_safe(inode, node, n, head, i_hash) {
+			hlist_del_init(&inode->i_hash);
+			list_del_init(&NILFS_I(inode)->i_dirty);
+			nilfs_clear_gcinode(inode); /* might sleep */
+		}
+	}
+}