Re: [PATCH] fs: Do not mntput() the root device parent

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

On 4/15/26 3:08 PM, Sascha Hauer wrote:
> The vfs rootfs ("/") parent points to itself, so do not call mntput() on
> the parent when it's the root device as the reference counter would
> become negative.
> 
> This doesn't happen in normal configurations as we normally have a ramfs
> mounted at / and we leave fs_remove() early in that case. Some xload
> configurations have a FAT from SD/eMMC mounted at / though which leads
> to a "refcount for mount \"%s\" becomes negative\n" warning.
> 
> Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

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

> ---
>  fs/fs.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/fs/fs.c b/fs/fs.c
> index f1f69a501f..a562fe0fc6 100644
> --- a/fs/fs.c
> +++ b/fs/fs.c
> @@ -874,7 +874,8 @@ static void fs_remove(struct device *dev)
>  	list_for_each_entry_safe(inode, tmp, &sb->s_inodes, i_sb_list)
>  		destroy_inode(inode);
>  
> -	mntput(fsdev->vfsmount.parent);
> +	if (&fsdev->vfsmount != fsdev->vfsmount.parent)

Nitpick: having the rvalue at the left-hand side is a bit unusual for
barebox, e.g. if (1 == x)..

> +		mntput(fsdev->vfsmount.parent);
>  
>  	free(fsdev->backingstore);
>  }

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