Re: [PATCH v4] erofs: Add support for FS_IOC_GETFSLABEL

[Chao Yu <chao@kernel.org>]

On 9/22/25 17:29, Bo Liu wrote:
> From: Bo Liu (OpenAnolis) <liubo03@inspur.com>
> 
> Add support for reading to the erofs volume label from the
> FS_IOC_GETFSLABEL ioctls.
> 
> Signed-off-by: Bo Liu (OpenAnolis) <liubo03@inspur.com>
> ---
> 
> v1: https://lore.kernel.org/linux-erofs/20250825120617.19746-1-liubo03@inspur.com/
> v2: https://lore.kernel.org/linux-erofs/20250826103926.4424-1-liubo03@inspur.com/
> v3: https://lore.kernel.org/linux-erofs/20250920060455.24002-1-liubo03@inspur.com/
> 
> change since v3:
> - move functions into inode.
> - remove useless comment.
> 
>  fs/erofs/data.c     |  4 ++++
>  fs/erofs/dir.c      |  4 ++++
>  fs/erofs/inode.c    | 40 ++++++++++++++++++++++++++++++++++++----
>  fs/erofs/internal.h |  6 ++++++
>  fs/erofs/super.c    |  8 ++++++++
>  5 files changed, 58 insertions(+), 4 deletions(-)
> 
> diff --git a/fs/erofs/data.c b/fs/erofs/data.c
> index 3b1ba571c728..8ca29962a3dd 100644
> --- a/fs/erofs/data.c
> +++ b/fs/erofs/data.c
> @@ -475,6 +475,10 @@ static loff_t erofs_file_llseek(struct file *file, loff_t offset, int whence)
>  const struct file_operations erofs_file_fops = {
>  	.llseek		= erofs_file_llseek,
>  	.read_iter	= erofs_file_read_iter,
> +	.unlocked_ioctl = erofs_ioctl,
> +#ifdef CONFIG_COMPAT
> +	.compat_ioctl   = erofs_compat_ioctl,
> +#endif
>  	.mmap_prepare	= erofs_file_mmap_prepare,
>  	.get_unmapped_area = thp_get_unmapped_area,
>  	.splice_read	= filemap_splice_read,
> diff --git a/fs/erofs/dir.c b/fs/erofs/dir.c
> index debf469ad6bd..32b4f5aa60c9 100644
> --- a/fs/erofs/dir.c
> +++ b/fs/erofs/dir.c
> @@ -123,4 +123,8 @@ const struct file_operations erofs_dir_fops = {
>  	.llseek		= generic_file_llseek,
>  	.read		= generic_read_dir,
>  	.iterate_shared	= erofs_readdir,
> +	.unlocked_ioctl = erofs_ioctl,
> +#ifdef CONFIG_COMPAT
> +	.compat_ioctl   = erofs_compat_ioctl,
> +#endif
>  };
> diff --git a/fs/erofs/inode.c b/fs/erofs/inode.c
> index 9a2f59721522..7a9a9081f890 100644
> --- a/fs/erofs/inode.c
> +++ b/fs/erofs/inode.c
> @@ -213,10 +213,7 @@ static int erofs_fill_inode(struct inode *inode)
>  	switch (inode->i_mode & S_IFMT) {
>  	case S_IFREG:
>  		inode->i_op = &erofs_generic_iops;
> -		if (erofs_inode_is_data_compressed(vi->datalayout))
> -			inode->i_fop = &generic_ro_fops;
> -		else
> -			inode->i_fop = &erofs_file_fops;
> +		inode->i_fop = &erofs_file_fops;
>  		break;
>  	case S_IFDIR:
>  		inode->i_op = &erofs_dir_iops;
> @@ -341,6 +338,41 @@ int erofs_getattr(struct mnt_idmap *idmap, const struct path *path,
>  	return 0;
>  }
>  
> +static int erofs_ioctl_get_volume_label(struct inode *inode, void __user *arg)
> +{
> +	struct erofs_sb_info *sbi = EROFS_I_SB(inode);
> +	int ret;
> +
> +	if (!sbi->volume_name)
> +		ret = clear_user(arg, 1);
> +	else
> +		ret = copy_to_user(arg, sbi->volume_name,
> +				   strlen(sbi->volume_name));
> +
> +	return ret ? -EFAULT : 0;
> +}
> +
> +long erofs_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
> +{
> +	struct inode *inode = file_inode(filp);
> +	void __user *argp = (void __user *)arg;
> +
> +	switch (cmd) {
> +	case FS_IOC_GETFSLABEL:
> +		return erofs_ioctl_get_volume_label(inode, argp);
> +	default:
> +		return -ENOTTY;
> +	}
> +}
> +
> +#ifdef CONFIG_COMPAT
> +long erofs_compat_ioctl(struct file *filp, unsigned int cmd,
> +			unsigned long arg)
> +{
> +	return erofs_ioctl(filp, cmd, (unsigned long)compat_ptr(arg));
> +}
> +#endif
> +
>  const struct inode_operations erofs_generic_iops = {
>  	.getattr = erofs_getattr,
>  	.listxattr = erofs_listxattr,
> diff --git a/fs/erofs/internal.h b/fs/erofs/internal.h
> index 4ccc5f0ee8df..b70902e00586 100644
> --- a/fs/erofs/internal.h
> +++ b/fs/erofs/internal.h
> @@ -166,6 +166,8 @@ struct erofs_sb_info {
>  	struct erofs_domain *domain;
>  	char *fsid;
>  	char *domain_id;
> +
> +	char *volume_name;
>  };
>  
>  #define EROFS_SB(sb) ((struct erofs_sb_info *)(sb)->s_fs_info)
> @@ -535,6 +537,10 @@ static inline struct bio *erofs_fscache_bio_alloc(struct erofs_map_dev *mdev) {
>  static inline void erofs_fscache_submit_bio(struct bio *bio) {}
>  #endif
>  
> +long erofs_ioctl(struct file *filp, unsigned int cmd, unsigned long arg);

#ifdef CONFIG_COMPAT

> +long erofs_compat_ioctl(struct file *filp, unsigned int cmd,
> +			unsigned long arg);

#endif

Thanks,

> +
>  #define EFSCORRUPTED    EUCLEAN         /* Filesystem is corrupted */
>  
>  #endif	/* __EROFS_INTERNAL_H */
> diff --git a/fs/erofs/super.c b/fs/erofs/super.c
> index 1b529ace4db0..f1535ebe03ec 100644
> --- a/fs/erofs/super.c
> +++ b/fs/erofs/super.c
> @@ -343,6 +343,13 @@ static int erofs_read_superblock(struct super_block *sb)
>  	sbi->fixed_nsec = le32_to_cpu(dsb->fixed_nsec);
>  	super_set_uuid(sb, (void *)dsb->uuid, sizeof(dsb->uuid));
>  
> +	if (dsb->volume_name[0]) {
> +		sbi->volume_name = kstrndup(dsb->volume_name,
> +					    sizeof(dsb->volume_name), GFP_KERNEL);
> +		if (!sbi->volume_name)
> +			return -ENOMEM;
> +	}
> +
>  	/* parse on-disk compression configurations */
>  	ret = z_erofs_parse_cfgs(sb, dsb);
>  	if (ret < 0)
> @@ -822,6 +829,7 @@ static void erofs_sb_free(struct erofs_sb_info *sbi)
>  	kfree(sbi->domain_id);
>  	if (sbi->dif0.file)
>  		fput(sbi->dif0.file);
> +	kfree(sbi->volume_name);
>  	kfree(sbi);
>  }
>