[Devel] [PATCH vz9 3/5] fs: introduce is_sb_ve_accessible()

[Kirill Tkhai]

On 22.11.2021 09:20, Nikita Yushchenko wrote:
> This routine checks if any mount of the given superblock is accessible
> from VE, either from root or non-root mount namespace.
> 
> To be used for per-VE sync implementation.
> 
> https://jira.sw.ru/browse/PSBM-44684
> Signed-off-by: Nikita Yushchenko <nikita.yushchenko at virtuozzo.com>

Reviewed-by: Kirill Tkhai <ktkhai at virtuozzo.com>

> ---
>  fs/internal.h  | 10 ++++++++++
>  fs/namespace.c | 17 +++++++++++++++++
>  2 files changed, 27 insertions(+)
> 
> diff --git a/fs/internal.h b/fs/internal.h
> index 82e8eb32ff3d..257e51814d2c 100644
> --- a/fs/internal.h
> +++ b/fs/internal.h
> @@ -96,6 +96,16 @@ int path_mount(const char *dev_name, struct path *path,
>  		const char *type_page, unsigned long flags, void *data_page);
>  int path_umount(struct path *path, int flags);
>  
> +#ifdef CONFIG_VE
> +extern bool is_sb_ve_accessible(struct ve_struct *ve, struct super_block *sb);
> +#else
> +static inline bool is_sb_ve_accessible(struct ve_struct *ve,
> +		struct super_block *sb)
> +{
> +	return true;
> +}
> +#endif
> +
>  /*
>   * fs_struct.c
>   */
> diff --git a/fs/namespace.c b/fs/namespace.c
> index 558fa26bde50..8dbda795b4db 100644
> --- a/fs/namespace.c
> +++ b/fs/namespace.c
> @@ -2832,6 +2832,23 @@ static inline void ve_mount_nr_dec(struct mount *mnt)
>  	mnt->ve_owner = NULL;
>  }
>  
> +bool is_sb_ve_accessible(struct ve_struct *ve, struct super_block *sb)
> +{
> +	struct mount *mnt;
> +	bool ret = false;
> +
> +	lock_mount_hash();
> +	list_for_each_entry(mnt, &sb->s_mounts, mnt_instance) {
> +		if (mnt->ve_owner == ve) {
> +			ret = true;
> +			break;
> +		}
> +	}
> +	unlock_mount_hash();
> +
> +	return ret;
> +}
> +
>  #else /* CONFIG_VE */
>  
>  static inline int ve_mount_allowed(void) { return 1; }
>