Beispiel #1
0
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;
}
Beispiel #2
0
/**
 * 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_sb_info *sbi;
	struct nilfs_root *fsroot;
	struct backing_dev_info *bdi;
	__u64 cno;
	int err;

	sbi = kzalloc(sizeof(*sbi), GFP_KERNEL);
	if (!sbi)
		return -ENOMEM;

	sb->s_fs_info = sbi;
	sbi->s_super = sb;

	nilfs = alloc_nilfs(sb->s_bdev);
	if (!nilfs) {
		err = -ENOMEM;
		goto failed_sbi;
	}
	sbi->s_nilfs = nilfs;

	err = init_nilfs(nilfs, sbi, (char *)data);
	if (err)
		goto failed_nilfs;

	spin_lock_init(&sbi->s_inode_lock);
	INIT_LIST_HEAD(&sbi->s_dirty_files);

	/*
	 * Following initialization is overlapped because
	 * nilfs_sb_info structure has been cleared at the beginning.
	 * But we reserve them to keep our interest and make ready
	 * for the future change.
	 */
	get_random_bytes(&sbi->s_next_generation,
			 sizeof(sbi->s_next_generation));
	spin_lock_init(&sbi->s_next_gen_lock);

	sb->s_op = &nilfs_sops;
	sb->s_export_op = &nilfs_export_ops;
	sb->s_root = NULL;
	sb->s_time_gran = 1;

	bdi = sb->s_bdev->bd_inode->i_mapping->backing_dev_info;
	sb->s_bdi = bdi ? : &default_backing_dev_info;

	err = load_nilfs(nilfs, sbi);
	if (err)
		goto failed_nilfs;

	cno = nilfs_last_cno(nilfs);
	err = nilfs_attach_checkpoint(sbi, 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_segment_constructor(sbi, 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(sbi, true);
		up_write(&nilfs->ns_sem);
	}

	return 0;

 failed_segctor:
	nilfs_detach_segment_constructor(sbi);

 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);

 failed_sbi:
	sb->s_fs_info = NULL;
	kfree(sbi);
	return err;
}
Beispiel #3
0
static int nilfs_remount(struct super_block *sb, int *flags, char *data)
{
	struct nilfs_sb_info *sbi = NILFS_SB(sb);
	struct the_nilfs *nilfs = sbi->s_nilfs;
	unsigned long old_sb_flags;
	unsigned long old_mount_opt;
	int err;

	old_sb_flags = sb->s_flags;
	old_mount_opt = sbi->s_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 the segment constructor */
		nilfs_detach_segment_constructor(sbi);
		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(sbi);
		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(sb->s_root->d_inode)->i_root;
		err = nilfs_attach_segment_constructor(sbi, root);
		if (err)
			goto restore_opts;

		down_write(&nilfs->ns_sem);
		nilfs_setup_super(sbi, true);
		up_write(&nilfs->ns_sem);
	}
 out:
	return 0;

 restore_opts:
	sb->s_flags = old_sb_flags;
	sbi->s_mount_opt = old_mount_opt;
	return err;
}
Beispiel #4
0
/**
 * 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;
	struct backing_dev_info *bdi;
	__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;

	bdi = sb->s_bdev->bd_inode->i_mapping->backing_dev_info;
	sb->s_bdi = bdi ? : &default_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;
}
Beispiel #5
0
static int nilfs_remount(struct super_block *sb, int *flags, char *data)
{
	struct nilfs_sb_info *sbi = NILFS_SB(sb);
	struct nilfs_super_block *sbp;
	struct the_nilfs *nilfs = sbi->s_nilfs;
	unsigned long old_sb_flags;
	struct nilfs_mount_options old_opts;
	int was_snapshot, err;

	down_write(&nilfs->ns_super_sem);
	old_sb_flags = sb->s_flags;
	old_opts.mount_opt = sbi->s_mount_opt;
	old_opts.snapshot_cno = sbi->s_snapshot_cno;
	was_snapshot = nilfs_test_opt(sbi, SNAPSHOT);

	if (!parse_options(data, sb)) {
		err = -EINVAL;
		goto restore_opts;
	}
	sb->s_flags = (sb->s_flags & ~MS_POSIXACL);

	err = -EINVAL;
	if (was_snapshot) {
		if (!(*flags & MS_RDONLY)) {
			printk(KERN_ERR "NILFS (device %s): cannot remount "
			       "snapshot read/write.\n",
			       sb->s_id);
			goto restore_opts;
		} else if (sbi->s_snapshot_cno != old_opts.snapshot_cno) {
			printk(KERN_ERR "NILFS (device %s): cannot "
			       "remount to a different snapshot.\n",
			       sb->s_id);
			goto restore_opts;
		}
	} else {
		if (nilfs_test_opt(sbi, SNAPSHOT)) {
			printk(KERN_ERR "NILFS (device %s): cannot change "
			       "a regular mount to a snapshot.\n",
			       sb->s_id);
			goto restore_opts;
		}
	}

	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 the segment constructor */
		nilfs_detach_segment_constructor(sbi);
		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);
		sbp = nilfs->ns_sbp[0];
		if (!(sbp->s_state & le16_to_cpu(NILFS_VALID_FS)) &&
		    (nilfs->ns_mount_state & NILFS_VALID_FS))
			sbp->s_state = cpu_to_le16(nilfs->ns_mount_state);
		sbp->s_mtime = cpu_to_le64(get_seconds());
		nilfs_commit_super(sbi, 1);
		up_write(&nilfs->ns_sem);
	} else {
		/*
		 * 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.)
		 */
		sb->s_flags &= ~MS_RDONLY;

		err = nilfs_attach_segment_constructor(sbi);
		if (err)
			goto restore_opts;

		down_write(&nilfs->ns_sem);
		nilfs_setup_super(sbi);
		up_write(&nilfs->ns_sem);
	}
 out:
	up_write(&nilfs->ns_super_sem);
	return 0;

 restore_opts:
	sb->s_flags = old_sb_flags;
	sbi->s_mount_opt = old_opts.mount_opt;
	sbi->s_snapshot_cno = old_opts.snapshot_cno;
	up_write(&nilfs->ns_super_sem);
	return err;
}
Beispiel #6
0
/**
 * nilfs_fill_super() - initialize a super block instance
 * @sb: super_block
 * @data: mount options
 * @silent: silent mode flag
 * @nilfs: the_nilfs struct
 *
 * 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_sb_info *sbi;
	struct inode *root;
	__u64 cno;
	int err;

	sbi = kzalloc(sizeof(*sbi), GFP_KERNEL);
	if (!sbi)
		return -ENOMEM;

	sb->s_fs_info = sbi;

	get_nilfs(nilfs);
	sbi->s_nilfs = nilfs;
	sbi->s_super = sb;
	atomic_set(&sbi->s_count, 1);

	err = init_nilfs(nilfs, sbi, (char *)data);
	if (err)
		goto failed_sbi;

	spin_lock_init(&sbi->s_inode_lock);
	INIT_LIST_HEAD(&sbi->s_dirty_files);
	INIT_LIST_HEAD(&sbi->s_list);

	/*
	 * Following initialization is overlapped because
	 * nilfs_sb_info structure has been cleared at the beginning.
	 * But we reserve them to keep our interest and make ready
	 * for the future change.
	 */
	get_random_bytes(&sbi->s_next_generation,
			 sizeof(sbi->s_next_generation));
	spin_lock_init(&sbi->s_next_gen_lock);

	sb->s_op = &nilfs_sops;
	sb->s_export_op = &nilfs_export_ops;
	sb->s_root = NULL;
	sb->s_time_gran = 1;
	sb->s_bdi = nilfs->ns_bdi;

	err = load_nilfs(nilfs, sbi);
	if (err)
		goto failed_sbi;

	cno = nilfs_last_cno(nilfs);

	if (sb->s_flags & MS_RDONLY) {
		if (nilfs_test_opt(sbi, SNAPSHOT)) {
			down_read(&nilfs->ns_segctor_sem);
			err = nilfs_cpfile_is_snapshot(nilfs->ns_cpfile,
						       sbi->s_snapshot_cno);
			up_read(&nilfs->ns_segctor_sem);
			if (err < 0) {
				if (err == -ENOENT)
					err = -EINVAL;
				goto failed_sbi;
			}
			if (!err) {
				printk(KERN_ERR
				       "NILFS: The specified checkpoint is "
				       "not a snapshot "
				       "(checkpoint number=%llu).\n",
				       (unsigned long long)sbi->s_snapshot_cno);
				err = -EINVAL;
				goto failed_sbi;
			}
			cno = sbi->s_snapshot_cno;
		}
	}

	err = nilfs_attach_checkpoint(sbi, cno);
	if (err) {
		printk(KERN_ERR "NILFS: error loading a checkpoint"
		       " (checkpoint number=%llu).\n", (unsigned long long)cno);
		goto failed_sbi;
	}

	if (!(sb->s_flags & MS_RDONLY)) {
		err = nilfs_attach_segment_constructor(sbi);
		if (err)
			goto failed_checkpoint;
	}

	root = nilfs_iget(sb, NILFS_ROOT_INO);
	if (IS_ERR(root)) {
		printk(KERN_ERR "NILFS: get root inode failed\n");
		err = PTR_ERR(root);
		goto failed_segctor;
	}
	if (!S_ISDIR(root->i_mode) || !root->i_blocks || !root->i_size) {
		iput(root);
		printk(KERN_ERR "NILFS: corrupt root inode.\n");
		err = -EINVAL;
		goto failed_segctor;
	}
	sb->s_root = d_alloc_root(root);
	if (!sb->s_root) {
		iput(root);
		printk(KERN_ERR "NILFS: get root dentry failed\n");
		err = -ENOMEM;
		goto failed_segctor;
	}

	if (!(sb->s_flags & MS_RDONLY)) {
		down_write(&nilfs->ns_sem);
		nilfs_setup_super(sbi);
		up_write(&nilfs->ns_sem);
	}

	down_write(&nilfs->ns_super_sem);
	if (!nilfs_test_opt(sbi, SNAPSHOT))
		nilfs->ns_current = sbi;
	up_write(&nilfs->ns_super_sem);

	return 0;

 failed_segctor:
	nilfs_detach_segment_constructor(sbi);

 failed_checkpoint:
	nilfs_detach_checkpoint(sbi);

 failed_sbi:
	put_nilfs(nilfs);
	sb->s_fs_info = NULL;
	nilfs_put_sbinfo(sbi);
	return err;
}
Beispiel #7
0
/**
 * 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);
	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) {
		nilfs_msg(sb, KERN_ERR,
			  "error %d while loading last checkpoint (checkpoint number=%llu)",
			  err, (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;
}
Beispiel #8
0
static int nilfs_remount(struct super_block *sb, int *flags, char *data)
{
	struct nilfs_sb_info *sbi = NILFS_SB(sb);
	struct nilfs_super_block *sbp;
	struct the_nilfs *nilfs = sbi->s_nilfs;
	unsigned long old_sb_flags;
	struct nilfs_mount_options old_opts;
	int err;

	old_sb_flags = sb->s_flags;
	old_opts.mount_opt = sbi->s_mount_opt;
	old_opts.snapshot_cno = sbi->s_snapshot_cno;

	if (!parse_options(data, sb)) {
		err = -EINVAL;
		goto restore_opts;
	}
	sb->s_flags = (sb->s_flags & ~MS_POSIXACL);

	if ((*flags & MS_RDONLY) &&
	    sbi->s_snapshot_cno != old_opts.snapshot_cno) {
		printk(KERN_WARNING "NILFS (device %s): couldn't "
		       "remount to a different snapshot. \n",
		       sb->s_id);
		err = -EINVAL;
		goto restore_opts;
	}

	if ((*flags & MS_RDONLY) == (sb->s_flags & MS_RDONLY))
		goto out;
	if (*flags & MS_RDONLY) {
		/* Shutting down the segment constructor */
		nilfs_detach_segment_constructor(sbi);
		sb->s_flags |= MS_RDONLY;

		sbi->s_snapshot_cno = nilfs_last_cno(nilfs);
		/* nilfs_set_opt(sbi, SNAPSHOT); */

		/*
		 * Remounting a valid RW partition RDONLY, so set
		 * the RDONLY flag and then mark the partition as valid again.
		 */
		down_write(&nilfs->ns_sem);
		sbp = nilfs->ns_sbp[0];
		if (!(sbp->s_state & le16_to_cpu(NILFS_VALID_FS)) &&
		    (nilfs->ns_mount_state & NILFS_VALID_FS))
			sbp->s_state = cpu_to_le16(nilfs->ns_mount_state);
		sbp->s_mtime = cpu_to_le64(get_seconds());
		nilfs_commit_super(sbi, 1);
		up_write(&nilfs->ns_sem);
	} else {
		/*
		 * 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(&sb->s_bdev->bd_mount_sem);
		/* Check existing RW-mount */
		if (test_exclusive_mount(sb->s_type, sb->s_bdev, 0)) {
			printk(KERN_WARNING "NILFS (device %s): couldn't "
			       "remount because a RW-mount exists.\n",
			       sb->s_id);
			err = -EBUSY;
			goto rw_remount_failed;
		}
		if (sbi->s_snapshot_cno != nilfs_last_cno(nilfs)) {
			printk(KERN_WARNING "NILFS (device %s): couldn't "
			       "remount because the current RO-mount is not "
			       "the latest one.\n",
			       sb->s_id);
			err = -EINVAL;
			goto rw_remount_failed;
		}
		sb->s_flags &= ~MS_RDONLY;
		nilfs_clear_opt(sbi, SNAPSHOT);
		sbi->s_snapshot_cno = 0;

		err = nilfs_attach_segment_constructor(sbi);
		if (err)
			goto rw_remount_failed;

		down_write(&nilfs->ns_sem);
		nilfs_setup_super(sbi);
		up_write(&nilfs->ns_sem);

		up(&sb->s_bdev->bd_mount_sem);
	}
 out:
	return 0;

 rw_remount_failed:
	up(&sb->s_bdev->bd_mount_sem);
 restore_opts:
	sb->s_flags = old_sb_flags;
	sbi->s_mount_opt = old_opts.mount_opt;
	sbi->s_snapshot_cno = old_opts.snapshot_cno;
	return err;
}
Beispiel #9
0
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 & ~SB_POSIXACL);

	err = -EINVAL;

	if (!nilfs_valid_fs(nilfs)) {
		nilfs_msg(sb, KERN_WARNING,
			  "couldn't remount because the filesystem is in an incomplete recovery state");
		goto restore_opts;
	}

	if ((bool)(*flags & SB_RDONLY) == sb_rdonly(sb))
		goto out;
	if (*flags & SB_RDONLY) {
		/* Shutting down log writer */
		nilfs_detach_log_writer(sb);
		sb->s_flags |= SB_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) {
			nilfs_msg(sb, KERN_WARNING,
				  "couldn't remount RDWR because of unsupported optional features (%llx)",
				  (unsigned long long)features);
			err = -EROFS;
			goto restore_opts;
		}

		sb->s_flags &= ~SB_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;
}