text: /*
   * 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;  /* 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;
  	} else {
  		sb2i = -1;
  		blocknr = 0;
  	}
  	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();
  
  	kmem_cache_destroy(nilfs_inode_cachep);
  	kmem_cache_destroy(nilfs_transaction_cachep);
  	kmem_cache_destroy(nilfs_segbuf_cachep);
  	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)
  