Initial import

1 files changed, 1486 insertions, 0 deletions

diff --git a/fs/nilfs2/super.c b/fs/nilfs2/super.c
new file mode 100644
index 000000000..f47585bfe
--- /dev/null
+++ b/fs/nilfs2/super.c
@@ -0,0 +1,1486 @@
+/*
+ * super.c - NILFS module and super block management.
+ *
+ * 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 Ryusuke Konishi <ryusuke@osrg.net>
+ */
+/*
+ *  linux/fs/ext2/super.c
+ *
+ * Copyright (C) 1992, 1993, 1994, 1995
+ * Remy Card (card@masi.ibp.fr)
+ * Laboratoire MASI - Institut Blaise Pascal
+ * Universite Pierre et Marie Curie (Paris VI)
+ *
+ *  from
+ *
+ *  linux/fs/minix/inode.c
+ *
+ *  Copyright (C) 1991, 1992  Linus Torvalds
+ *
+ *  Big-endian to little-endian byte-swapping/bitmaps by
+ *        David S. Miller (davem@caip.rutgers.edu), 1995
+ */
+
+#include <linux/module.h>
+#include <linux/string.h>
+#include <linux/slab.h>
+#include <linux/init.h>
+#include <linux/blkdev.h>
+#include <linux/parser.h>
+#include <linux/crc32.h>
+#include <linux/vfs.h>
+#include <linux/writeback.h>
+#include <linux/seq_file.h>
+#include <linux/mount.h>
+#include "nilfs.h"
+#include "export.h"
+#include "mdt.h"
+#include "alloc.h"
+#include "btree.h"
+#include "btnode.h"
+#include "page.h"
+#include "cpfile.h"
+#include "sufile.h" /* nilfs_sufile_resize(), nilfs_sufile_set_alloc_range() */
+#include "ifile.h"
+#include "dat.h"
+#include "segment.h"
+#include "segbuf.h"
+
+MODULE_AUTHOR("NTT Corp.");
+MODULE_DESCRIPTION("A New Implementation of the Log-structured Filesystem "
+		   "(NILFS)");
+MODULE_LICENSE("GPL");
+
+static struct kmem_cache *nilfs_inode_cachep;
+struct kmem_cache *nilfs_transaction_cachep;
+struct kmem_cache *nilfs_segbuf_cachep;
+struct kmem_cache *nilfs_btree_path_cache;
+
+static int nilfs_setup_super(struct super_block *sb, int is_mount);
+static int nilfs_remount(struct super_block *sb, int *flags, char *data);
+
+static void nilfs_set_error(struct super_block *sb)
+{
+	struct the_nilfs *nilfs = sb->s_fs_info;
+	struct nilfs_super_block **sbp;
+
+	down_write(&nilfs->ns_sem);
+	if (!(nilfs->ns_mount_state & NILFS_ERROR_FS)) {
+		nilfs->ns_mount_state |= NILFS_ERROR_FS;
+		sbp = nilfs_prepare_super(sb, 0);
+		if (likely(sbp)) {
+			sbp[0]->s_state |= cpu_to_le16(NILFS_ERROR_FS);
+			if (sbp[1])
+				sbp[1]->s_state |= cpu_to_le16(NILFS_ERROR_FS);
+			nilfs_commit_super(sb, NILFS_SB_COMMIT_ALL);
+		}
+	}
+	up_write(&nilfs->ns_sem);
+}
+
+/**
+ * nilfs_error() - report failure condition on a filesystem
+ *
+ * nilfs_error() sets an ERROR_FS flag on the superblock as well as
+ * reporting an error message.  It should be called when NILFS detects
+ * incoherences or defects of meta data on disk.  As for sustainable
+ * errors such as a single-shot I/O error, nilfs_warning() or the printk()
+ * function should be used instead.
+ *
+ * The segment constructor must not call this function because it can
+ * kill itself.
+ */
+void nilfs_error(struct super_block *sb, const char *function,
+		 const char *fmt, ...)
+{
+	struct the_nilfs *nilfs = sb->s_fs_info;
+	struct va_format vaf;
+	va_list args;
+
+	va_start(args, fmt);
+
+	vaf.fmt = fmt;
+	vaf.va = &args;
+
+	printk(KERN_CRIT "NILFS error (device %s): %s: %pV\n",
+	       sb->s_id, function, &vaf);
+
+	va_end(args);
+
+	if (!(sb->s_flags & MS_RDONLY)) {
+		nilfs_set_error(sb);
+
+		if (nilfs_test_opt(nilfs, ERRORS_RO)) {
+			printk(KERN_CRIT "Remounting filesystem read-only\n");
+			sb->s_flags |= MS_RDONLY;
+		}
+	}
+
+	if (nilfs_test_opt(nilfs, ERRORS_PANIC))
+		panic("NILFS (device %s): panic forced after error\n",
+		      sb->s_id);
+}
+
+void nilfs_warning(struct super_block *sb, const char *function,
+		   const char *fmt, ...)
+{
+	struct va_format vaf;
+	va_list args;
+
+	va_start(args, fmt);
+
+	vaf.fmt = fmt;
+	vaf.va = &args;
+
+	printk(KERN_WARNING "NILFS warning (device %s): %s: %pV\n",
+	       sb->s_id, function, &vaf);
+
+	va_end(args);
+}
+
+
+struct inode *nilfs_alloc_inode(struct super_block *sb)
+{
+	struct nilfs_inode_info *ii;
+
+	ii = kmem_cache_alloc(nilfs_inode_cachep, GFP_NOFS);
+	if (!ii)
+		return NULL;
+	ii->i_bh = NULL;
+	ii->i_state = 0;
+	ii->i_cno = 0;
+	ii->vfs_inode.i_version = 1;
+	nilfs_mapping_init(&ii->i_btnode_cache, &ii->vfs_inode);
+	return &ii->vfs_inode;
+}
+
+static void nilfs_i_callback(struct rcu_head *head)
+{
+	struct inode *inode = container_of(head, struct inode, i_rcu);
+	struct nilfs_mdt_info *mdi = NILFS_MDT(inode);
+
+	if (mdi) {
+		kfree(mdi->mi_bgl); /* kfree(NULL) is safe */
+		kfree(mdi);
+	}
+	kmem_cache_free(nilfs_inode_cachep, NILFS_I(inode));
+}
+
+void nilfs_destroy_inode(struct inode *inode)
+{
+	call_rcu(&inode->i_rcu, nilfs_i_callback);
+}
+
+static int nilfs_sync_super(struct super_block *sb, int flag)
+{
+	struct the_nilfs *nilfs = sb->s_fs_info;
+	int err;
+
+ retry:
+	set_buffer_dirty(nilfs->ns_sbh[0]);
+	if (nilfs_test_opt(nilfs, BARRIER)) {
+		err = __sync_dirty_buffer(nilfs->ns_sbh[0],
+					  WRITE_SYNC | WRITE_FLUSH_FUA);
+	} else {
+		err = sync_dirty_buffer(nilfs->ns_sbh[0]);
+	}
+
+	if (unlikely(err)) {
+		printk(KERN_ERR
+		       "NILFS: unable to write superblock (err=%d)\n", err);
+		if (err == -EIO && nilfs->ns_sbh[1]) {
+			/*
+			 * sbp[0] points to newer log than sbp[1],
+			 * so copy sbp[0] to sbp[1] to take over sbp[0].
+			 */
+			memcpy(nilfs->ns_sbp[1], nilfs->ns_sbp[0],
+			       nilfs->ns_sbsize);
+			nilfs_fall_back_super_block(nilfs);
+			goto retry;
+		}
+	} else {
+		struct nilfs_super_block *sbp = nilfs->ns_sbp[0];
+
+		nilfs->ns_sbwcount++;
+
+		/*
+		 * The latest segment becomes trailable from the position
+		 * written in superblock.
+		 */
+		clear_nilfs_discontinued(nilfs);
+
+		/* update GC protection for recent segments */
+		if (nilfs->ns_sbh[1]) {
+			if (flag == NILFS_SB_COMMIT_ALL) {
+				set_buffer_dirty(nilfs->ns_sbh[1]);
+				if (sync_dirty_buffer(nilfs->ns_sbh[1]) < 0)
+					goto out;
+			}
+			if (le64_to_cpu(nilfs->ns_sbp[1]->s_last_cno) <
+			    le64_to_cpu(nilfs->ns_sbp[0]->s_last_cno))
+				sbp = nilfs->ns_sbp[1];
+		}
+
+		spin_lock(&nilfs->ns_last_segment_lock);
+		nilfs->ns_prot_seq = le64_to_cpu(sbp->s_last_seq);
+		spin_unlock(&nilfs->ns_last_segment_lock);
+	}
+ out:
+	return err;
+}
+
+void nilfs_set_log_cursor(struct nilfs_super_block *sbp,
+			  struct the_nilfs *nilfs)
+{
+	sector_t nfreeblocks;
+
+	/* nilfs->ns_sem must be locked by the caller. */
+	nilfs_count_free_blocks(nilfs, &nfreeblocks);
+	sbp->s_free_blocks_count = cpu_to_le64(nfreeblocks);
+
+	spin_lock(&nilfs->ns_last_segment_lock);
+	sbp->s_last_seq = cpu_to_le64(nilfs->ns_last_seq);
+	sbp->s_last_pseg = cpu_to_le64(nilfs->ns_last_pseg);
+	sbp->s_last_cno = cpu_to_le64(nilfs->ns_last_cno);
+	spin_unlock(&nilfs->ns_last_segment_lock);
+}
+
+struct nilfs_super_block **nilfs_prepare_super(struct super_block *sb,
+					       int flip)
+{
+	struct the_nilfs *nilfs = sb->s_fs_info;
+	struct nilfs_super_block **sbp = nilfs->ns_sbp;
+
+	/* nilfs->ns_sem must be locked by the caller. */
+	if (sbp[0]->s_magic != cpu_to_le16(NILFS_SUPER_MAGIC)) {
+		if (sbp[1] &&
+		    sbp[1]->s_magic == cpu_to_le16(NILFS_SUPER_MAGIC)) {
+			memcpy(sbp[0], sbp[1], nilfs->ns_sbsize);
+		} else {
+			printk(KERN_CRIT "NILFS: superblock broke on dev %s\n",
+			       sb->s_id);
+			return NULL;
+		}
+	} else if (sbp[1] &&
+		   sbp[1]->s_magic != cpu_to_le16(NILFS_SUPER_MAGIC)) {
+			memcpy(sbp[1], sbp[0], nilfs->ns_sbsize);
+	}
+
+	if (flip && sbp[1])
+		nilfs_swap_super_block(nilfs);
+
+	return sbp;
+}
+
+int nilfs_commit_super(struct super_block *sb, int flag)
+{
+	struct the_nilfs *nilfs = sb->s_fs_info;
+	struct nilfs_super_block **sbp = nilfs->ns_sbp;
+	time_t t;
+
+	/* nilfs->ns_sem must be locked by the caller. */
+	t = get_seconds();
+	nilfs->ns_sbwtime = t;
+	sbp[0]->s_wtime = cpu_to_le64(t);
+	sbp[0]->s_sum = 0;
+	sbp[0]->s_sum = cpu_to_le32(crc32_le(nilfs->ns_crc_seed,
+					     (unsigned char *)sbp[0],
+					     nilfs->ns_sbsize));
+	if (flag == NILFS_SB_COMMIT_ALL && sbp[1]) {
+		sbp[1]->s_wtime = sbp[0]->s_wtime;
+		sbp[1]->s_sum = 0;
+		sbp[1]->s_sum = cpu_to_le32(crc32_le(nilfs->ns_crc_seed,
+					    (unsigned char *)sbp[1],
+					    nilfs->ns_sbsize));
+	}
+	clear_nilfs_sb_dirty(nilfs);
+	nilfs->ns_flushed_device = 1;
+	/* make sure store to ns_flushed_device cannot be reordered */
+	smp_wmb();
+	return nilfs_sync_super(sb, flag);
+}
+
+/**
+ * nilfs_cleanup_super() - write filesystem state for cleanup
+ * @sb: super block instance to be unmounted or degraded to read-only
+ *
+ * This function restores state flags in the on-disk super block.
+ * This will set "clean" flag (i.e. NILFS_VALID_FS) unless the
+ * filesystem was not clean previously.
+ */
+int nilfs_cleanup_super(struct super_block *sb)
+{
+	struct the_nilfs *nilfs = sb->s_fs_info;
+	struct nilfs_super_block **sbp;
+	int flag = NILFS_SB_COMMIT;
+	int ret = -EIO;
+
+	sbp = nilfs_prepare_super(sb, 0);
+	if (sbp) {
+		sbp[0]->s_state = cpu_to_le16(nilfs->ns_mount_state);
+		nilfs_set_log_cursor(sbp[0], nilfs);
+		if (sbp[1] && sbp[0]->s_last_cno == sbp[1]->s_last_cno) {
+			/*
+			 * make the "clean" flag also to the opposite
+			 * super block if both super blocks point to
+			 * the same checkpoint.
+			 */
+			sbp[1]->s_state = sbp[0]->s_state;
+			flag = NILFS_SB_COMMIT_ALL;
+		}
+		ret = nilfs_commit_super(sb, flag);
+	}
+	return ret;
+}
+
+/**
+ * nilfs_move_2nd_super - relocate secondary super block
+ * @sb: super block instance
+ * @sb2off: new offset of the secondary super block (in bytes)
+ */
+static int nilfs_move_2nd_super(struct super_block *sb, loff_t sb2off)
+{
+	struct the_nilfs *nilfs = sb->s_fs_info;
+	struct buffer_head *nsbh;
+	struct nilfs_super_block *nsbp;
+	sector_t blocknr, newblocknr;
+	unsigned long offset;
+	int sb2i = -1;  /* array index of the secondary superblock */
+	int ret = 0;
+
+	/* nilfs->ns_sem must be locked by the caller. */
+	if (nilfs->ns_sbh[1] &&
+	    nilfs->ns_sbh[1]->b_blocknr > nilfs->ns_first_data_block) {
+		sb2i = 1;
+		blocknr = nilfs->ns_sbh[1]->b_blocknr;
+	} else if (nilfs->ns_sbh[0]->b_blocknr > nilfs->ns_first_data_block) {
+		sb2i = 0;
+		blocknr = nilfs->ns_sbh[0]->b_blocknr;
+	}
+	if (sb2i >= 0 && (u64)blocknr << nilfs->ns_blocksize_bits == sb2off)
+		goto out;  /* super block location is unchanged */
+
+	/* Get new super block buffer */
+	newblocknr = sb2off >> nilfs->ns_blocksize_bits;
+	offset = sb2off & (nilfs->ns_blocksize - 1);
+	nsbh = sb_getblk(sb, newblocknr);
+	if (!nsbh) {
+		printk(KERN_WARNING
+		       "NILFS warning: unable to move secondary superblock "
+		       "to block %llu\n", (unsigned long long)newblocknr);
+		ret = -EIO;
+		goto out;
+	}
+	nsbp = (void *)nsbh->b_data + offset;
+	memset(nsbp, 0, nilfs->ns_blocksize);
+
+	if (sb2i >= 0) {
+		memcpy(nsbp, nilfs->ns_sbp[sb2i], nilfs->ns_sbsize);
+		brelse(nilfs->ns_sbh[sb2i]);
+		nilfs->ns_sbh[sb2i] = nsbh;
+		nilfs->ns_sbp[sb2i] = nsbp;
+	} else if (nilfs->ns_sbh[0]->b_blocknr < nilfs->ns_first_data_block) {
+		/* secondary super block will be restored to index 1 */
+		nilfs->ns_sbh[1] = nsbh;
+		nilfs->ns_sbp[1] = nsbp;
+	} else {
+		brelse(nsbh);
+	}
+out:
+	return ret;
+}
+
+/**
+ * nilfs_resize_fs - resize the filesystem
+ * @sb: super block instance
+ * @newsize: new size of the filesystem (in bytes)
+ */
+int nilfs_resize_fs(struct super_block *sb, __u64 newsize)
+{
+	struct the_nilfs *nilfs = sb->s_fs_info;
+	struct nilfs_super_block **sbp;
+	__u64 devsize, newnsegs;
+	loff_t sb2off;
+	int ret;
+
+	ret = -ERANGE;
+	devsize = i_size_read(sb->s_bdev->bd_inode);
+	if (newsize > devsize)
+		goto out;
+
+	/*
+	 * Write lock is required to protect some functions depending
+	 * on the number of segments, the number of reserved segments,
+	 * and so forth.
+	 */
+	down_write(&nilfs->ns_segctor_sem);
+
+	sb2off = NILFS_SB2_OFFSET_BYTES(newsize);
+	newnsegs = sb2off >> nilfs->ns_blocksize_bits;
+	do_div(newnsegs, nilfs->ns_blocks_per_segment);
+
+	ret = nilfs_sufile_resize(nilfs->ns_sufile, newnsegs);
+	up_write(&nilfs->ns_segctor_sem);
+	if (ret < 0)
+		goto out;
+
+	ret = nilfs_construct_segment(sb);
+	if (ret < 0)
+		goto out;
+
+	down_write(&nilfs->ns_sem);
+	nilfs_move_2nd_super(sb, sb2off);
+	ret = -EIO;
+	sbp = nilfs_prepare_super(sb, 0);
+	if (likely(sbp)) {
+		nilfs_set_log_cursor(sbp[0], nilfs);
+		/*
+		 * Drop NILFS_RESIZE_FS flag for compatibility with
+		 * mount-time resize which may be implemented in a
+		 * future release.
+		 */
+		sbp[0]->s_state = cpu_to_le16(le16_to_cpu(sbp[0]->s_state) &
+					      ~NILFS_RESIZE_FS);
+		sbp[0]->s_dev_size = cpu_to_le64(newsize);
+		sbp[0]->s_nsegments = cpu_to_le64(nilfs->ns_nsegments);
+		if (sbp[1])
+			memcpy(sbp[1], sbp[0], nilfs->ns_sbsize);
+		ret = nilfs_commit_super(sb, NILFS_SB_COMMIT_ALL);
+	}
+	up_write(&nilfs->ns_sem);
+
+	/*
+	 * Reset the range of allocatable segments last.  This order
+	 * is important in the case of expansion because the secondary
+	 * superblock must be protected from log write until migration
+	 * completes.
+	 */
+	if (!ret)
+		nilfs_sufile_set_alloc_range(nilfs->ns_sufile, 0, newnsegs - 1);
+out:
+	return ret;
+}
+
+static void nilfs_put_super(struct super_block *sb)
+{
+	struct the_nilfs *nilfs = sb->s_fs_info;
+
+	nilfs_detach_log_writer(sb);
+
+	if (!(sb->s_flags & MS_RDONLY)) {
+		down_write(&nilfs->ns_sem);
+		nilfs_cleanup_super(sb);
+		up_write(&nilfs->ns_sem);
+	}
+
+	iput(nilfs->ns_sufile);
+	iput(nilfs->ns_cpfile);
+	iput(nilfs->ns_dat);
+
+	destroy_nilfs(nilfs);
+	sb->s_fs_info = NULL;
+}
+
+static int nilfs_sync_fs(struct super_block *sb, int wait)
+{
+	struct the_nilfs *nilfs = sb->s_fs_info;
+	struct nilfs_super_block **sbp;
+	int err = 0;
+
+	/* This function is called when super block should be written back */
+	if (wait)
+		err = nilfs_construct_segment(sb);
+
+	down_write(&nilfs->ns_sem);
+	if (nilfs_sb_dirty(nilfs)) {
+		sbp = nilfs_prepare_super(sb, nilfs_sb_will_flip(nilfs));
+		if (likely(sbp)) {
+			nilfs_set_log_cursor(sbp[0], nilfs);
+			nilfs_commit_super(sb, NILFS_SB_COMMIT);
+		}
+	}
+	up_write(&nilfs->ns_sem);
+
+	if (!err)
+		err = nilfs_flush_device(nilfs);
+
+	return err;
+}
+
+int nilfs_attach_checkpoint(struct super_block *sb, __u64 cno, int curr_mnt,
+			    struct nilfs_root **rootp)
+{
+	struct the_nilfs *nilfs = sb->s_fs_info;
+	struct nilfs_root *root;
+	struct nilfs_checkpoint *raw_cp;
+	struct buffer_head *bh_cp;
+	int err = -ENOMEM;
+
+	root = nilfs_find_or_create_root(
+		nilfs, curr_mnt ? NILFS_CPTREE_CURRENT_CNO : cno);
+	if (!root)
+		return err;
+
+	if (root->ifile)
+		goto reuse; /* already attached checkpoint */
+
+	down_read(&nilfs->ns_segctor_sem);
+	err = nilfs_cpfile_get_checkpoint(nilfs->ns_cpfile, cno, 0, &raw_cp,
+					  &bh_cp);
+	up_read(&nilfs->ns_segctor_sem);
+	if (unlikely(err)) {
+		if (err == -ENOENT || err == -EINVAL) {
+			printk(KERN_ERR
+			       "NILFS: Invalid checkpoint "
+			       "(checkpoint number=%llu)\n",
+			       (unsigned long long)cno);
+			err = -EINVAL;
+		}
+		goto failed;
+	}
+
+	err = nilfs_ifile_read(sb, root, nilfs->ns_inode_size,
+			       &raw_cp->cp_ifile_inode, &root->ifile);
+	if (err)
+		goto failed_bh;
+
+	atomic64_set(&root->inodes_count,
+			le64_to_cpu(raw_cp->cp_inodes_count));
+	atomic64_set(&root->blocks_count,
+			le64_to_cpu(raw_cp->cp_blocks_count));
+
+	nilfs_cpfile_put_checkpoint(nilfs->ns_cpfile, cno, bh_cp);
+
+ reuse:
+	*rootp = root;
+	return 0;
+
+ failed_bh:
+	nilfs_cpfile_put_checkpoint(nilfs->ns_cpfile, cno, bh_cp);
+ failed:
+	nilfs_put_root(root);
+
+	return err;
+}
+
+static int nilfs_freeze(struct super_block *sb)
+{
+	struct the_nilfs *nilfs = sb->s_fs_info;
+	int err;
+
+	if (sb->s_flags & MS_RDONLY)
+		return 0;
+
+	/* Mark super block clean */
+	down_write(&nilfs->ns_sem);
+	err = nilfs_cleanup_super(sb);
+	up_write(&nilfs->ns_sem);
+	return err;
+}
+
+static int nilfs_unfreeze(struct super_block *sb)
+{
+	struct the_nilfs *nilfs = sb->s_fs_info;
+
+	if (sb->s_flags & MS_RDONLY)
+		return 0;
+
+	down_write(&nilfs->ns_sem);
+	nilfs_setup_super(sb, false);
+	up_write(&nilfs->ns_sem);
+	return 0;
+}
+
+static int nilfs_statfs(struct dentry *dentry, struct kstatfs *buf)
+{
+	struct super_block *sb = dentry->d_sb;
+	struct nilfs_root *root = NILFS_I(d_inode(dentry))->i_root;
+	struct the_nilfs *nilfs = root->nilfs;
+	u64 id = huge_encode_dev(sb->s_bdev->bd_dev);
+	unsigned long long blocks;
+	unsigned long overhead;
+	unsigned long nrsvblocks;
+	sector_t nfreeblocks;
+	u64 nmaxinodes, nfreeinodes;
+	int err;
+
+	/*
+	 * Compute all of the segment blocks
+	 *
+	 * The blocks before first segment and after last segment
+	 * are excluded.
+	 */
+	blocks = nilfs->ns_blocks_per_segment * nilfs->ns_nsegments
+		- nilfs->ns_first_data_block;
+	nrsvblocks = nilfs->ns_nrsvsegs * nilfs->ns_blocks_per_segment;
+
+	/*
+	 * Compute the overhead
+	 *
+	 * When distributing meta data blocks outside segment structure,
+	 * We must count them as the overhead.
+	 */
+	overhead = 0;
+
+	err = nilfs_count_free_blocks(nilfs, &nfreeblocks);
+	if (unlikely(err))
+		return err;
+
+	err = nilfs_ifile_count_free_inodes(root->ifile,
+					    &nmaxinodes, &nfreeinodes);
+	if (unlikely(err)) {
+		printk(KERN_WARNING
+			"NILFS warning: fail to count free inodes: err %d.\n",
+			err);
+		if (err == -ERANGE) {
+			/*
+			 * If nilfs_palloc_count_max_entries() returns
+			 * -ERANGE error code then we simply treat
+			 * curent inodes count as maximum possible and
+			 * zero as free inodes value.
+			 */
+			nmaxinodes = atomic64_read(&root->inodes_count);
+			nfreeinodes = 0;
+			err = 0;
+		} else
+			return err;
+	}
+
+	buf->f_type = NILFS_SUPER_MAGIC;
+	buf->f_bsize = sb->s_blocksize;
+	buf->f_blocks = blocks - overhead;
+	buf->f_bfree = nfreeblocks;
+	buf->f_bavail = (buf->f_bfree >= nrsvblocks) ?
+		(buf->f_bfree - nrsvblocks) : 0;
+	buf->f_files = nmaxinodes;
+	buf->f_ffree = nfreeinodes;
+	buf->f_namelen = NILFS_NAME_LEN;
+	buf->f_fsid.val[0] = (u32)id;
+	buf->f_fsid.val[1] = (u32)(id >> 32);
+
+	return 0;
+}
+
+static int nilfs_show_options(struct seq_file *seq, struct dentry *dentry)
+{
+	struct super_block *sb = dentry->d_sb;
+	struct the_nilfs *nilfs = sb->s_fs_info;
+	struct nilfs_root *root = NILFS_I(d_inode(dentry))->i_root;
+
+	if (!nilfs_test_opt(nilfs, BARRIER))
+		seq_puts(seq, ",nobarrier");
+	if (root->cno != NILFS_CPTREE_CURRENT_CNO)
+		seq_printf(seq, ",cp=%llu", (unsigned long long)root->cno);
+	if (nilfs_test_opt(nilfs, ERRORS_PANIC))
+		seq_puts(seq, ",errors=panic");
+	if (nilfs_test_opt(nilfs, ERRORS_CONT))
+		seq_puts(seq, ",errors=continue");
+	if (nilfs_test_opt(nilfs, STRICT_ORDER))
+		seq_puts(seq, ",order=strict");
+	if (nilfs_test_opt(nilfs, NORECOVERY))
+		seq_puts(seq, ",norecovery");
+	if (nilfs_test_opt(nilfs, DISCARD))
+		seq_puts(seq, ",discard");
+
+	return 0;
+}
+
+static const struct super_operations nilfs_sops = {
+	.alloc_inode    = nilfs_alloc_inode,
+	.destroy_inode  = nilfs_destroy_inode,
+	.dirty_inode    = nilfs_dirty_inode,
+	.evict_inode    = nilfs_evict_inode,
+	.put_super      = nilfs_put_super,
+	.sync_fs        = nilfs_sync_fs,
+	.freeze_fs	= nilfs_freeze,
+	.unfreeze_fs	= nilfs_unfreeze,
+	.statfs         = nilfs_statfs,
+	.remount_fs     = nilfs_remount,
+	.show_options = nilfs_show_options
+};
+
+enum {
+	Opt_err_cont, Opt_err_panic, Opt_err_ro,
+	Opt_barrier, Opt_nobarrier, Opt_snapshot, Opt_order, Opt_norecovery,
+	Opt_discard, Opt_nodiscard, Opt_err,
+};
+
+static match_table_t tokens = {
+	{Opt_err_cont, "errors=continue"},
+	{Opt_err_panic, "errors=panic"},
+	{Opt_err_ro, "errors=remount-ro"},
+	{Opt_barrier, "barrier"},
+	{Opt_nobarrier, "nobarrier"},
+	{Opt_snapshot, "cp=%u"},
+	{Opt_order, "order=%s"},
+	{Opt_norecovery, "norecovery"},
+	{Opt_discard, "discard"},
+	{Opt_nodiscard, "nodiscard"},
+	{Opt_err, NULL}
+};
+
+static int parse_options(char *options, struct super_block *sb, int is_remount)
+{
+	struct the_nilfs *nilfs = sb->s_fs_info;
+	char *p;
+	substring_t args[MAX_OPT_ARGS];
+
+	if (!options)
+		return 1;
+
+	while ((p = strsep(&options, ",")) != NULL) {
+		int token;
+		if (!*p)
+			continue;
+
+		token = match_token(p, tokens, args);
+		switch (token) {
+		case Opt_barrier:
+			nilfs_set_opt(nilfs, BARRIER);
+			break;
+		case Opt_nobarrier:
+			nilfs_clear_opt(nilfs, BARRIER);
+			break;
+		case Opt_order:
+			if (strcmp(args[0].from, "relaxed") == 0)
+				/* Ordered data semantics */
+				nilfs_clear_opt(nilfs, STRICT_ORDER);
+			else if (strcmp(args[0].from, "strict") == 0)
+				/* Strict in-order semantics */
+				nilfs_set_opt(nilfs, STRICT_ORDER);
+			else
+				return 0;
+			break;
+		case Opt_err_panic:
+			nilfs_write_opt(nilfs, ERROR_MODE, ERRORS_PANIC);
+			break;
+		case Opt_err_ro:
+			nilfs_write_opt(nilfs, ERROR_MODE, ERRORS_RO);
+			break;
+		case Opt_err_cont:
+			nilfs_write_opt(nilfs, ERROR_MODE, ERRORS_CONT);
+			break;
+		case Opt_snapshot:
+			if (is_remount) {
+				printk(KERN_ERR
+				       "NILFS: \"%s\" option is invalid "
+				       "for remount.\n", p);
+				return 0;
+			}
+			break;
+		case Opt_norecovery:
+			nilfs_set_opt(nilfs, NORECOVERY);
+			break;
+		case Opt_discard:
+			nilfs_set_opt(nilfs, DISCARD);
+			break;
+		case Opt_nodiscard:
+			nilfs_clear_opt(nilfs, DISCARD);
+			break;
+		default:
+			printk(KERN_ERR
+			       "NILFS: Unrecognized mount option \"%s\"\n", p);
+			return 0;
+		}
+	}
+	return 1;
+}
+
+static inline void
+nilfs_set_default_options(struct super_block *sb,
+			  struct nilfs_super_block *sbp)
+{
+	struct the_nilfs *nilfs = sb->s_fs_info;
+
+	nilfs->ns_mount_opt =
+		NILFS_MOUNT_ERRORS_RO | NILFS_MOUNT_BARRIER;
+}
+
+static int nilfs_setup_super(struct super_block *sb, int is_mount)
+{
+	struct the_nilfs *nilfs = sb->s_fs_info;
+	struct nilfs_super_block **sbp;
+	int max_mnt_count;
+	int mnt_count;
+
+	/* nilfs->ns_sem must be locked by the caller. */
+	sbp = nilfs_prepare_super(sb, 0);
+	if (!sbp)
+		return -EIO;
+
+	if (!is_mount)
+		goto skip_mount_setup;
+
+	max_mnt_count = le16_to_cpu(sbp[0]->s_max_mnt_count);
+	mnt_count = le16_to_cpu(sbp[0]->s_mnt_count);
+
+	if (nilfs->ns_mount_state & NILFS_ERROR_FS) {
+		printk(KERN_WARNING
+		       "NILFS warning: mounting fs with errors\n");
+#if 0
+	} else if (max_mnt_count >= 0 && mnt_count >= max_mnt_count) {
+		printk(KERN_WARNING
+		       "NILFS warning: maximal mount count reached\n");
+#endif
+	}
+	if (!max_mnt_count)
+		sbp[0]->s_max_mnt_count = cpu_to_le16(NILFS_DFL_MAX_MNT_COUNT);
+
+	sbp[0]->s_mnt_count = cpu_to_le16(mnt_count + 1);
+	sbp[0]->s_mtime = cpu_to_le64(get_seconds());
+
+skip_mount_setup:
+	sbp[0]->s_state =
+		cpu_to_le16(le16_to_cpu(sbp[0]->s_state) & ~NILFS_VALID_FS);
+	/* synchronize sbp[1] with sbp[0] */
+	if (sbp[1])
+		memcpy(sbp[1], sbp[0], nilfs->ns_sbsize);
+	return nilfs_commit_super(sb, NILFS_SB_COMMIT_ALL);
+}
+
+struct nilfs_super_block *nilfs_read_super_block(struct super_block *sb,
+						 u64 pos, int blocksize,
+						 struct buffer_head **pbh)
+{
+	unsigned long long sb_index = pos;
+	unsigned long offset;
+
+	offset = do_div(sb_index, blocksize);
+	*pbh = sb_bread(sb, sb_index);
+	if (!*pbh)
+		return NULL;
+	return (struct nilfs_super_block *)((char *)(*pbh)->b_data + offset);
+}
+
+int nilfs_store_magic_and_option(struct super_block *sb,
+				 struct nilfs_super_block *sbp,
+				 char *data)
+{
+	struct the_nilfs *nilfs = sb->s_fs_info;
+
+	sb->s_magic = le16_to_cpu(sbp->s_magic);
+
+	/* FS independent flags */
+#ifdef NILFS_ATIME_DISABLE
+	sb->s_flags |= MS_NOATIME;
+#endif
+
+	nilfs_set_default_options(sb, sbp);
+
+	nilfs->ns_resuid = le16_to_cpu(sbp->s_def_resuid);
+	nilfs->ns_resgid = le16_to_cpu(sbp->s_def_resgid);
+	nilfs->ns_interval = le32_to_cpu(sbp->s_c_interval);
+	nilfs->ns_watermark = le32_to_cpu(sbp->s_c_block_max);
+
+	return !parse_options(data, sb, 0) ? -EINVAL : 0 ;
+}
+
+int nilfs_check_feature_compatibility(struct super_block *sb,
+				      struct nilfs_super_block *sbp)
+{
+	__u64 features;
+
+	features = le64_to_cpu(sbp->s_feature_incompat) &
+		~NILFS_FEATURE_INCOMPAT_SUPP;
+	if (features) {
+		printk(KERN_ERR "NILFS: couldn't mount because of unsupported "
+		       "optional features (%llx)\n",
+		       (unsigned long long)features);
+		return -EINVAL;
+	}
+	features = le64_to_cpu(sbp->s_feature_compat_ro) &
+		~NILFS_FEATURE_COMPAT_RO_SUPP;
+	if (!(sb->s_flags & MS_RDONLY) && features) {
+		printk(KERN_ERR "NILFS: couldn't mount RDWR because of "
+		       "unsupported optional features (%llx)\n",
+		       (unsigned long long)features);
+		return -EINVAL;
+	}
+	return 0;
+}
+
+static int nilfs_get_root_dentry(struct super_block *sb,
+				 struct nilfs_root *root,
+				 struct dentry **root_dentry)
+{
+	struct inode *inode;
+	struct dentry *dentry;
+	int ret = 0;
+
+	inode = nilfs_iget(sb, root, NILFS_ROOT_INO);
+	if (IS_ERR(inode)) {
+		printk(KERN_ERR "NILFS: get root inode failed\n");
+		ret = PTR_ERR(inode);
+		goto out;
+	}
+	if (!S_ISDIR(inode->i_mode) || !inode->i_blocks || !inode->i_size) {
+		iput(inode);
+		printk(KERN_ERR "NILFS: corrupt root inode.\n");
+		ret = -EINVAL;
+		goto out;
+	}
+
+	if (root->cno == NILFS_CPTREE_CURRENT_CNO) {
+		dentry = d_find_alias(inode);
+		if (!dentry) {
+			dentry = d_make_root(inode);
+			if (!dentry) {
+				ret = -ENOMEM;
+				goto failed_dentry;
+			}
+		} else {
+			iput(inode);
+		}
+	} else {
+		dentry = d_obtain_root(inode);
+		if (IS_ERR(dentry)) {
+			ret = PTR_ERR(dentry);
+			goto failed_dentry;
+		}
+	}
+	*root_dentry = dentry;
+ out:
+	return ret;
+
+ failed_dentry:
+	printk(KERN_ERR "NILFS: get root dentry failed\n");
+	goto out;
+}
+
+static int nilfs_attach_snapshot(struct super_block *s, __u64 cno,
+				 struct dentry **root_dentry)
+{
+	struct the_nilfs *nilfs = s->s_fs_info;
+	struct nilfs_root *root;
+	int ret;
+
+	mutex_lock(&nilfs->ns_snapshot_mount_mutex);
+
+	down_read(&nilfs->ns_segctor_sem);
+	ret = nilfs_cpfile_is_snapshot(nilfs->ns_cpfile, cno);
+	up_read(&nilfs->ns_segctor_sem);
+	if (ret < 0) {
+		ret = (ret == -ENOENT) ? -EINVAL : ret;
+		goto out;
+	} else if (!ret) {
+		printk(KERN_ERR "NILFS: The specified checkpoint is "
+		       "not a snapshot (checkpoint number=%llu).\n",
+		       (unsigned long long)cno);
+		ret = -EINVAL;
+		goto out;
+	}
+
+	ret = nilfs_attach_checkpoint(s, cno, false, &root);
+	if (ret) {
+		printk(KERN_ERR "NILFS: error loading snapshot "
+		       "(checkpoint number=%llu).\n",
+	       (unsigned long long)cno);
+		goto out;
+	}
+	ret = nilfs_get_root_dentry(s, root, root_dentry);
+	nilfs_put_root(root);
+ out:
+	mutex_unlock(&nilfs->ns_snapshot_mount_mutex);
+	return ret;
+}
+
+/**
+ * nilfs_tree_is_busy() - try to shrink dentries of a checkpoint
+ * @root_dentry: root dentry of the tree to be shrunk
+ *
+ * This function returns true if the tree was in-use.
+ */
+static bool nilfs_tree_is_busy(struct dentry *root_dentry)
+{
+	shrink_dcache_parent(root_dentry);
+	return d_count(root_dentry) > 1;
+}
+
+int nilfs_checkpoint_is_mounted(struct super_block *sb, __u64 cno)
+{
+	struct the_nilfs *nilfs = sb->s_fs_info;
+	struct nilfs_root *root;
+	struct inode *inode;
+	struct dentry *dentry;
+	int ret;
+
+	if (cno > nilfs->ns_cno)
+		return false;
+
+	if (cno >= nilfs_last_cno(nilfs))
+		return true;	/* protect recent checkpoints */
+
+	ret = false;
+	root = nilfs_lookup_root(nilfs, cno);
+	if (root) {
+		inode = nilfs_ilookup(sb, root, NILFS_ROOT_INO);
+		if (inode) {
+			dentry = d_find_alias(inode);
+			if (dentry) {
+				ret = nilfs_tree_is_busy(dentry);
+				dput(dentry);
+			}
+			iput(inode);
+		}
+		nilfs_put_root(root);
+	}
+	return ret;
+}
+
+/**
+ * nilfs_fill_super() - initialize a super block instance
+ * @sb: super_block
+ * @data: mount options
+ * @silent: silent mode flag
+ *
+ * This function is called exclusively by nilfs->ns_mount_mutex.
+ * So, the recovery process is protected from other simultaneous mounts.
+ */
+static int
+nilfs_fill_super(struct super_block *sb, void *data, int silent)
+{
+	struct the_nilfs *nilfs;
+	struct nilfs_root *fsroot;
+	__u64 cno;
+	int err;
+
+	nilfs = alloc_nilfs(sb->s_bdev);
+	if (!nilfs)
+		return -ENOMEM;
+
+	sb->s_fs_info = nilfs;
+
+	err = init_nilfs(nilfs, sb, (char *)data);
+	if (err)
+		goto failed_nilfs;
+
+	sb->s_op = &nilfs_sops;
+	sb->s_export_op = &nilfs_export_ops;
+	sb->s_root = NULL;
+	sb->s_time_gran = 1;
+	sb->s_max_links = NILFS_LINK_MAX;
+
+	sb->s_bdi = &bdev_get_queue(sb->s_bdev)->backing_dev_info;
+
+	err = load_nilfs(nilfs, sb);
+	if (err)
+		goto failed_nilfs;
+
+	cno = nilfs_last_cno(nilfs);
+	err = nilfs_attach_checkpoint(sb, cno, true, &fsroot);
+	if (err) {
+		printk(KERN_ERR "NILFS: error loading last checkpoint "
+		       "(checkpoint number=%llu).\n", (unsigned long long)cno);
+		goto failed_unload;
+	}
+
+	if (!(sb->s_flags & MS_RDONLY)) {
+		err = nilfs_attach_log_writer(sb, fsroot);
+		if (err)
+			goto failed_checkpoint;
+	}
+
+	err = nilfs_get_root_dentry(sb, fsroot, &sb->s_root);
+	if (err)
+		goto failed_segctor;
+
+	nilfs_put_root(fsroot);
+
+	if (!(sb->s_flags & MS_RDONLY)) {
+		down_write(&nilfs->ns_sem);
+		nilfs_setup_super(sb, true);
+		up_write(&nilfs->ns_sem);
+	}
+
+	return 0;
+
+ failed_segctor:
+	nilfs_detach_log_writer(sb);
+
+ failed_checkpoint:
+	nilfs_put_root(fsroot);
+
+ failed_unload:
+	iput(nilfs->ns_sufile);
+	iput(nilfs->ns_cpfile);
+	iput(nilfs->ns_dat);
+
+ failed_nilfs:
+	destroy_nilfs(nilfs);
+	return err;
+}
+
+static int nilfs_remount(struct super_block *sb, int *flags, char *data)
+{
+	struct the_nilfs *nilfs = sb->s_fs_info;
+	unsigned long old_sb_flags;
+	unsigned long old_mount_opt;
+	int err;
+
+	sync_filesystem(sb);
+	old_sb_flags = sb->s_flags;
+	old_mount_opt = nilfs->ns_mount_opt;
+
+	if (!parse_options(data, sb, 1)) {
+		err = -EINVAL;
+		goto restore_opts;
+	}
+	sb->s_flags = (sb->s_flags & ~MS_POSIXACL);
+
+	err = -EINVAL;
+
+	if (!nilfs_valid_fs(nilfs)) {
+		printk(KERN_WARNING "NILFS (device %s): couldn't "
+		       "remount because the filesystem is in an "
+		       "incomplete recovery state.\n", sb->s_id);
+		goto restore_opts;
+	}
+
+	if ((*flags & MS_RDONLY) == (sb->s_flags & MS_RDONLY))
+		goto out;
+	if (*flags & MS_RDONLY) {
+		/* Shutting down log writer */
+		nilfs_detach_log_writer(sb);
+		sb->s_flags |= MS_RDONLY;
+
+		/*
+		 * Remounting a valid RW partition RDONLY, so set
+		 * the RDONLY flag and then mark the partition as valid again.
+		 */
+		down_write(&nilfs->ns_sem);
+		nilfs_cleanup_super(sb);
+		up_write(&nilfs->ns_sem);
+	} else {
+		__u64 features;
+		struct nilfs_root *root;
+
+		/*
+		 * Mounting a RDONLY partition read-write, so reread and
+		 * store the current valid flag.  (It may have been changed
+		 * by fsck since we originally mounted the partition.)
+		 */
+		down_read(&nilfs->ns_sem);
+		features = le64_to_cpu(nilfs->ns_sbp[0]->s_feature_compat_ro) &
+			~NILFS_FEATURE_COMPAT_RO_SUPP;
+		up_read(&nilfs->ns_sem);
+		if (features) {
+			printk(KERN_WARNING "NILFS (device %s): couldn't "
+			       "remount RDWR because of unsupported optional "
+			       "features (%llx)\n",
+			       sb->s_id, (unsigned long long)features);
+			err = -EROFS;
+			goto restore_opts;
+		}
+
+		sb->s_flags &= ~MS_RDONLY;
+
+		root = NILFS_I(d_inode(sb->s_root))->i_root;
+		err = nilfs_attach_log_writer(sb, root);
+		if (err)
+			goto restore_opts;
+
+		down_write(&nilfs->ns_sem);
+		nilfs_setup_super(sb, true);
+		up_write(&nilfs->ns_sem);
+	}
+ out:
+	return 0;
+
+ restore_opts:
+	sb->s_flags = old_sb_flags;
+	nilfs->ns_mount_opt = old_mount_opt;
+	return err;
+}
+
+struct nilfs_super_data {
+	struct block_device *bdev;
+	__u64 cno;
+	int flags;
+};
+
+/**
+ * nilfs_identify - pre-read mount options needed to identify mount instance
+ * @data: mount options
+ * @sd: nilfs_super_data
+ */
+static int nilfs_identify(char *data, struct nilfs_super_data *sd)
+{
+	char *p, *options = data;
+	substring_t args[MAX_OPT_ARGS];
+	int token;
+	int ret = 0;
+
+	do {
+		p = strsep(&options, ",");
+		if (p != NULL && *p) {
+			token = match_token(p, tokens, args);
+			if (token == Opt_snapshot) {
+				if (!(sd->flags & MS_RDONLY)) {
+					ret++;
+				} else {
+					sd->cno = simple_strtoull(args[0].from,
+								  NULL, 0);
+					/*
+					 * No need to see the end pointer;
+					 * match_token() has done syntax
+					 * checking.
+					 */
+					if (sd->cno == 0)
+						ret++;
+				}
+			}
+			if (ret)
+				printk(KERN_ERR
+				       "NILFS: invalid mount option: %s\n", p);
+		}
+		if (!options)
+			break;
+		BUG_ON(options == data);
+		*(options - 1) = ',';
+	} while (!ret);
+	return ret;
+}
+
+static int nilfs_set_bdev_super(struct super_block *s, void *data)
+{
+	s->s_bdev = data;
+	s->s_dev = s->s_bdev->bd_dev;
+	return 0;
+}
+
+static int nilfs_test_bdev_super(struct super_block *s, void *data)
+{
+	return (void *)s->s_bdev == data;
+}
+
+static struct dentry *
+nilfs_mount(struct file_system_type *fs_type, int flags,
+	     const char *dev_name, void *data)
+{
+	struct nilfs_super_data sd;
+	struct super_block *s;
+	fmode_t mode = FMODE_READ | FMODE_EXCL;
+	struct dentry *root_dentry;
+	int err, s_new = false;
+
+	if (!(flags & MS_RDONLY))
+		mode |= FMODE_WRITE;
+
+	sd.bdev = blkdev_get_by_path(dev_name, mode, fs_type);
+	if (IS_ERR(sd.bdev))
+		return ERR_CAST(sd.bdev);
+
+	sd.cno = 0;
+	sd.flags = flags;
+	if (nilfs_identify((char *)data, &sd)) {
+		err = -EINVAL;
+		goto failed;
+	}
+
+	/*
+	 * once the super is inserted into the list by sget, s_umount
+	 * will protect the lockfs code from trying to start a snapshot
+	 * while we are mounting
+	 */
+	mutex_lock(&sd.bdev->bd_fsfreeze_mutex);
+	if (sd.bdev->bd_fsfreeze_count > 0) {
+		mutex_unlock(&sd.bdev->bd_fsfreeze_mutex);
+		err = -EBUSY;
+		goto failed;
+	}
+	s = sget(fs_type, nilfs_test_bdev_super, nilfs_set_bdev_super, flags,
+		 sd.bdev);
+	mutex_unlock(&sd.bdev->bd_fsfreeze_mutex);
+	if (IS_ERR(s)) {
+		err = PTR_ERR(s);
+		goto failed;
+	}
+
+	if (!s->s_root) {
+		char b[BDEVNAME_SIZE];
+
+		s_new = true;
+
+		/* New superblock instance created */
+		s->s_mode = mode;
+		strlcpy(s->s_id, bdevname(sd.bdev, b), sizeof(s->s_id));
+		sb_set_blocksize(s, block_size(sd.bdev));
+
+		err = nilfs_fill_super(s, data, flags & MS_SILENT ? 1 : 0);
+		if (err)
+			goto failed_super;
+
+		s->s_flags |= MS_ACTIVE;
+	} else if (!sd.cno) {
+		if (nilfs_tree_is_busy(s->s_root)) {
+			if ((flags ^ s->s_flags) & MS_RDONLY) {
+				printk(KERN_ERR "NILFS: the device already "
+				       "has a %s mount.\n",
+				       (s->s_flags & MS_RDONLY) ?
+				       "read-only" : "read/write");
+				err = -EBUSY;
+				goto failed_super;
+			}
+		} else {
+			/*
+			 * Try remount to setup mount states if the current
+			 * tree is not mounted and only snapshots use this sb.
+			 */
+			err = nilfs_remount(s, &flags, data);
+			if (err)
+				goto failed_super;
+		}
+	}
+
+	if (sd.cno) {
+		err = nilfs_attach_snapshot(s, sd.cno, &root_dentry);
+		if (err)
+			goto failed_super;
+	} else {
+		root_dentry = dget(s->s_root);
+	}
+
+	if (!s_new)
+		blkdev_put(sd.bdev, mode);
+
+	return root_dentry;
+
+ failed_super:
+	deactivate_locked_super(s);
+
+ failed:
+	if (!s_new)
+		blkdev_put(sd.bdev, mode);
+	return ERR_PTR(err);
+}
+
+struct file_system_type nilfs_fs_type = {
+	.owner    = THIS_MODULE,
+	.name     = "nilfs2",
+	.mount    = nilfs_mount,
+	.kill_sb  = kill_block_super,
+	.fs_flags = FS_REQUIRES_DEV,
+};
+MODULE_ALIAS_FS("nilfs2");
+
+static void nilfs_inode_init_once(void *obj)
+{
+	struct nilfs_inode_info *ii = obj;
+
+	INIT_LIST_HEAD(&ii->i_dirty);
+#ifdef CONFIG_NILFS_XATTR
+	init_rwsem(&ii->xattr_sem);
+#endif
+	address_space_init_once(&ii->i_btnode_cache);
+	ii->i_bmap = &ii->i_bmap_data;
+	inode_init_once(&ii->vfs_inode);
+}
+
+static void nilfs_segbuf_init_once(void *obj)
+{
+	memset(obj, 0, sizeof(struct nilfs_segment_buffer));
+}
+
+static void nilfs_destroy_cachep(void)
+{
+	/*
+	 * Make sure all delayed rcu free inodes are flushed before we
+	 * destroy cache.
+	 */
+	rcu_barrier();
+
+	if (nilfs_inode_cachep)
+		kmem_cache_destroy(nilfs_inode_cachep);
+	if (nilfs_transaction_cachep)
+		kmem_cache_destroy(nilfs_transaction_cachep);
+	if (nilfs_segbuf_cachep)
+		kmem_cache_destroy(nilfs_segbuf_cachep);
+	if (nilfs_btree_path_cache)
+		kmem_cache_destroy(nilfs_btree_path_cache);
+}
+
+static int __init nilfs_init_cachep(void)
+{
+	nilfs_inode_cachep = kmem_cache_create("nilfs2_inode_cache",
+			sizeof(struct nilfs_inode_info), 0,
+			SLAB_RECLAIM_ACCOUNT, nilfs_inode_init_once);
+	if (!nilfs_inode_cachep)
+		goto fail;
+
+	nilfs_transaction_cachep = kmem_cache_create("nilfs2_transaction_cache",
+			sizeof(struct nilfs_transaction_info), 0,
+			SLAB_RECLAIM_ACCOUNT, NULL);
+	if (!nilfs_transaction_cachep)
+		goto fail;
+
+	nilfs_segbuf_cachep = kmem_cache_create("nilfs2_segbuf_cache",
+			sizeof(struct nilfs_segment_buffer), 0,
+			SLAB_RECLAIM_ACCOUNT, nilfs_segbuf_init_once);
+	if (!nilfs_segbuf_cachep)
+		goto fail;
+
+	nilfs_btree_path_cache = kmem_cache_create("nilfs2_btree_path_cache",
+			sizeof(struct nilfs_btree_path) * NILFS_BTREE_LEVEL_MAX,
+			0, 0, NULL);
+	if (!nilfs_btree_path_cache)
+		goto fail;
+
+	return 0;
+
+fail:
+	nilfs_destroy_cachep();
+	return -ENOMEM;
+}
+
+static int __init init_nilfs_fs(void)
+{
+	int err;
+
+	err = nilfs_init_cachep();
+	if (err)
+		goto fail;
+
+	err = nilfs_sysfs_init();
+	if (err)
+		goto free_cachep;
+
+	err = register_filesystem(&nilfs_fs_type);
+	if (err)
+		goto deinit_sysfs_entry;
+
+	printk(KERN_INFO "NILFS version 2 loaded\n");
+	return 0;
+
+deinit_sysfs_entry:
+	nilfs_sysfs_exit();
+free_cachep:
+	nilfs_destroy_cachep();
+fail:
+	return err;
+}
+
+static void __exit exit_nilfs_fs(void)
+{
+	nilfs_destroy_cachep();
+	nilfs_sysfs_exit();
+	unregister_filesystem(&nilfs_fs_type);
+}
+
+module_init(init_nilfs_fs)
+module_exit(exit_nilfs_fs)