[Devel] [PATCH 2/2] fs/fuse kio_pcs: check fuse_conn args

[Kirill Tkhai]

Hi, Pasha,

On 17.05.2018 12:40, Pavel Butsykin wrote:
> Allow initialization of kdirect only for vstorage/pstorage.
> 
> Signed-off-by: Pavel Butsykin <pbutsykin at virtuozzo.com>
> ---
>  drivers/block/ploop/dev.c          |  4 ----
>  fs/fuse/kio/pcs/pcs_fuse_kdirect.c | 23 +++++++++++++++++------
>  include/linux/fs.h                 |  5 +++++
>  3 files changed, 22 insertions(+), 10 deletions(-)
> 
> diff --git a/drivers/block/ploop/dev.c b/drivers/block/ploop/dev.c
> index 0e72656ec8f9..c6094144c7a5 100644
> --- a/drivers/block/ploop/dev.c
> +++ b/drivers/block/ploop/dev.c
> @@ -3880,10 +3880,6 @@ static int ploop_truncate(struct ploop_device * plo, unsigned long arg)
>  	return err;
>  }
>  
> -#define IS_PSTORAGE(sb) (sb->s_magic == FUSE_SUPER_MAGIC && \
> -			 (!strcmp(sb->s_subtype, "pstorage") || \
> -			  !strcmp(sb->s_subtype, "vstorage")))
> -
>  static int ploop_bd_full(struct backing_dev_info *bdi, long long nr, int root)
>  {
>  	struct ploop_device *plo      = bdi->congested_data;
> diff --git a/fs/fuse/kio/pcs/pcs_fuse_kdirect.c b/fs/fuse/kio/pcs/pcs_fuse_kdirect.c
> index b8503d55e246..4b9c4a304571 100644
> --- a/fs/fuse/kio/pcs/pcs_fuse_kdirect.c
> +++ b/fs/fuse/kio/pcs/pcs_fuse_kdirect.c
> @@ -144,13 +144,24 @@ void kpcs_conn_abort(struct fuse_conn *fc)
>  }
>  
>  static int kpcs_probe(struct fuse_conn *fc, char *name)
> -
>  {
> -	printk("%s TODO IMPLEMENT check fuse_conn args here!\n", __FUNCTION__);
> -	if (!strncmp(name, kio_pcs_ops.name, FUSE_KIO_NAME))
> -		return 1;
> +	if (strncmp(name, kio_pcs_ops.name, FUSE_KIO_NAME)) {
> +		printk(KERN_ERR "FUSE: kio_pcs: invalid kio_ops name: %s\n", name);

Despite there was printk() without error level modifier (which is not correct),
and printk(KERN_ERR) is better, let's follow the modern Linux kernel style,
which anyway will be requested in case of submitting patches to mainstream.
pr_err() is more likely to use for such the printing (see the rest of pr_* in printk.h).

> +		return 0;
> +	}
>  
> -	return 0;
> +	if (!(fc->flags & FUSE_KDIRECT_IO)) {
> +		printk(KERN_ERR "FUSE: kio_pcs: kdirect is not enabled\n");
> +		return 0;
> +	}

I don't think this is needed, since we already check for this bit in fuse_fill_super()
before call of fuse_kio_get(). But I'm not insist on this.

> +
> +	if (!IS_PSTORAGE(fc->sb)) {
> +		printk(KERN_ERR "FUSE: kio_pcs: kdirect is only available for"
> +			            "pstorage/vstorage fuse mount\n");
> +		return 0;
> +	}
> +
> +	return 1;
>  }
>  
>  
> @@ -1202,7 +1213,7 @@ err:
>  static struct fuse_kio_ops kio_pcs_ops = {
>  	.name		= "pcs",
>  	.owner		= THIS_MODULE,
> -	.probe		= kpcs_probe, /*TODO: check sb->dev name */
> +	.probe		= kpcs_probe,
>  
>  	.conn_init	= kpcs_conn_init,
>  	.conn_fini	= kpcs_conn_fini,
> diff --git a/include/linux/fs.h b/include/linux/fs.h
> index a1dc3521f979..21770550b6c1 100644
> --- a/include/linux/fs.h
> +++ b/include/linux/fs.h
> @@ -1713,6 +1713,11 @@ struct super_block {
>  	struct list_lru		s_inode_lru ____cacheline_aligned_in_smp;
>  };
>  
> +#define IS_PSTORAGE(sb) ((sb)->s_magic == FUSE_SUPER_MAGIC && \
> +			 (sb)->s_subtype && \
> +			 (!strcmp((sb)->s_subtype, "pstorage") || \
> +			  !strcmp((sb)->s_subtype, "vstorage")))
> +
>  extern const unsigned super_block_wrapper_version;
>  struct super_block_wrapper {
>  	struct super_block sb;
> 

Thanks,
Kirill