cregit-Linux how code gets into the kernel

Release 4.10 fs/nilfs2/super.c

Directory: fs/nilfs2
/*
 * 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.
 *
 * Written by Ryusuke Konishi.
 */
/*
 *  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);




void __nilfs_msg(struct super_block *sb, const char *level, const char *fmt,
		 ...)
{
	struct va_format vaf;
	va_list args;

	va_start(args, fmt);
	vaf.fmt = fmt;
	vaf.va = &args;
	if (sb)
		printk("%sNILFS (%s): %pV\n", level, sb->s_id, &vaf);
	else
		printk("%sNILFS: %pV\n", level, &vaf);
	va_end(args);
}


Contributors
PersonTokensPropCommitsCommitProp
ryusuke konishiryusuke konishi83100.00%1100.00%


Total83100.00%1100.00%






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);
}


Contributors
PersonTokensPropCommitsCommitProp
ryusuke konishiryusuke konishi7362.39%360.00%


jiro sekibajiro sekiba4437.61%240.00%


Total117100.00%5100.00%



/**
 * __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.  This function should be called when
 * NILFS detects incoherences or defects of meta data on disk.
 *
 * This implements the body of nilfs_error() macro.  Normally,
 * nilfs_error() should be used.  As for sustainable errors such as a
 * single-shot I/O error, nilfs_msg() should be used instead.
 *
 * Callers should not add a trailing newline since this will do it.
 */



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);
}


Contributors
PersonTokensPropCommitsCommitProp
ryusuke konishiryusuke konishi11785.40%685.71%


joe perchesjoe perches2014.60%114.29%


Total137100.00%7100.00%






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;
}


Contributors
PersonTokensPropCommitsCommitProp
ryusuke konishiryusuke konishi79100.00%5100.00%


Total79100.00%5100.00%






static void nilfs_i_callback(struct rcu_head *head)
{
	struct inode *inode = container_of(head, struct inode, i_rcu);

	if (nilfs_is_metadata_file_inode(inode))
		nilfs_mdt_destroy(inode);

	kmem_cache_free(nilfs_inode_cachep, NILFS_I(inode));
}


Contributors
PersonTokensPropCommitsCommitProp
ryusuke konishiryusuke konishi3062.50%375.00%


nick pigginnick piggin1837.50%125.00%


Total48100.00%4100.00%






void nilfs_destroy_inode(struct inode *inode)
{
	call_rcu(&inode->i_rcu, nilfs_i_callback);
}


Contributors
PersonTokensPropCommitsCommitProp
nick pigginnick piggin20100.00%1100.00%


Total20100.00%1100.00%






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],
					  REQ_SYNC | REQ_PREFLUSH | REQ_FUA);
	} else {
		err = sync_dirty_buffer(nilfs->ns_sbh[0]);
	}

	if (unlikely(err)) {
		nilfs_msg(sb, KERN_ERR, "unable to write superblock: err=%d",
			  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;
}


Contributors
PersonTokensPropCommitsCommitProp
ryusuke konishiryusuke konishi20270.14%770.00%


jiro sekibajiro sekiba6522.57%110.00%


christoph hellwigchristoph hellwig217.29%220.00%


Total288100.00%10100.00%






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);
}


Contributors
PersonTokensPropCommitsCommitProp
ryusuke konishiryusuke konishi85100.00%1100.00%


Total85100.00%1100.00%






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 {
			nilfs_msg(sb, KERN_CRIT, "superblock broke");
			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;
}


Contributors
PersonTokensPropCommitsCommitProp
jiro sekibajiro sekiba8250.93%225.00%


ryusuke konishiryusuke konishi7949.07%675.00%


Total161100.00%8100.00%






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);
}


Contributors
PersonTokensPropCommitsCommitProp
ryusuke konishiryusuke konishi10656.08%666.67%


jiro sekibajiro sekiba7338.62%222.22%


andreas rohnerandreas rohner105.29%111.11%


Total189100.00%9100.00%



/**
 * 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;
}


Contributors
PersonTokensPropCommitsCommitProp
jiro sekibajiro sekiba7457.36%240.00%


ryusuke konishiryusuke konishi5542.64%360.00%


Total129100.00%5100.00%



/**
 * 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) {
		nilfs_msg(sb, KERN_WARNING,
			  "unable to move secondary superblock to block %llu",
			  (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;
}


Contributors
PersonTokensPropCommitsCommitProp
ryusuke konishiryusuke konishi343100.00%3100.00%


Total343100.00%3100.00%



/**
 * 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;
}


Contributors
PersonTokensPropCommitsCommitProp
ryusuke konishiryusuke konishi304100.00%1100.00%


Total304100.00%1100.00%






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;
}


Contributors
PersonTokensPropCommitsCommitProp
ryusuke konishiryusuke konishi91100.00%7100.00%


Total91100.00%7100.00%






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;
}


Contributors
PersonTokensPropCommitsCommitProp
jiro sekibajiro sekiba6955.65%337.50%


ryusuke konishiryusuke konishi4334.68%450.00%


andreas rohnerandreas rohner129.68%112.50%


Total124100.00%8100.00%






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) {
			nilfs_msg(sb, KERN_ERR,
				  "Invalid checkpoint (checkpoint number=%llu)",
				  (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;
}


Contributors
PersonTokensPropCommitsCommitProp
ryusuke konishiryusuke konishi25193.31%1083.33%


zhang qiangzhang qiang165.95%18.33%


vyacheslav dubeykovyacheslav dubeyko20.74%18.33%


Total269100.00%12100.00%






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;
}


Contributors
PersonTokensPropCommitsCommitProp
ryusuke konishiryusuke konishi61100.00%4100.00%


Total61100.00%4100.00%






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;
}


Contributors
PersonTokensPropCommitsCommitProp
ryusuke konishiryusuke konishi57100.00%4100.00%


Total57100.00%4100.00%






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)) {
		nilfs_msg(sb, KERN_WARNING,
			  "failed to count free inodes: err=%d", 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->