Re: [PATCH v2 03/13] fs: implement mknod

[Ahmad Fatoum <a.fatoum@pengutronix.de>]

On 12/9/25 1:51 PM, Sascha Hauer wrote:
> This implements mknod for the barebox VFS. Use the cdevname for
> connecting a device special node with a cdev. In Linux this is done with
> major/minor numbers which shouldn't be necessary for barebox as we do
> not intend to mount filesystems which contain device special nodes, but
> instead create them in ramfs. If a mounted filesystem contains special
> nodes then these won't work with barebox.
> 
> Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

With two minor points below addressed:

Reviewed-by: Ahmad Fatoum <a.fatoum@pengutronix.de>

> ---
>  fs/devfs.c         | 13 +++++++++++++
>  fs/fs.c            | 35 +++++++++++++++++++++++++++++++++++
>  include/fcntl.h    |  6 ++++++
>  include/linux/fs.h | 13 +++++++++++++
>  4 files changed, 67 insertions(+)
> 
> diff --git a/fs/devfs.c b/fs/devfs.c
> index 15c7a63d3949a5fa7c5ec15f58bc9f4c53b7852b..be3272be49e66eb843823b3ff664a1565f326790 100644
> --- a/fs/devfs.c
> +++ b/fs/devfs.c
> @@ -103,6 +103,12 @@ static int devfs_open(struct inode *inode, struct file *f)
>  	struct devfs_inode *node = container_of(inode, struct devfs_inode, inode);
>  	struct cdev *cdev = node->cdev;
>  
> +	if (inode->cdevname) {
> +		cdev = cdev_by_name(inode->cdevname);
> +		if (!cdev)
> +			return -ENOENT;
> +	}
> +
>  	f->f_size = cdev->flags & DEVFS_IS_CHARACTER_DEV ?
>  			FILE_SIZE_STREAM : cdev->size;
>  	f->private_data = cdev;
> @@ -188,6 +194,13 @@ static const struct file_operations devfs_file_operations = {
>  	.memmap = devfs_memmap,
>  };
>  
> +void init_special_inode(struct inode *inode, umode_t mode, const char *cdevname)
> +{
> +	inode->i_mode = mode;
> +	inode->i_fop = &devfs_file_operations;
> +	inode->cdevname = strdup(cdevname);

xstrdup_const? or return an error?

> +}
> +
>  static int devfs_lookup_revalidate(struct dentry *dentry, unsigned int flags)
>  {
>  	struct devfs_inode *dinode;
> diff --git a/fs/fs.c b/fs/fs.c
> index d884726187dd526213f8b51a68a2e0db1bb50e58..45bf89653c7c2e4e9546f1d41f79a6389e0b796d 100644
> --- a/fs/fs.c
> +++ b/fs/fs.c
> @@ -826,6 +826,8 @@ static int dentry_delete_subtree(struct super_block *sb, struct dentry *parent)
>  
>  static void destroy_inode(struct inode *inode)
>  {
> +	free(inode->cdevname);

free_const?

Cheers,
Ahmad

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