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

[Pavel Butsykin]

On 17.05.2018 13:05, Kirill Tkhai wrote:
> 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).
> 

ok, thanks.

>> +		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.
>

And what is the meaning of this check:
"!strncmp(name, kio_pcs_ops.name, FUSE_KIO_NAME)" ?

We also already have this check. I assumed this can protect against
possible mistakes in the future.

>> +
>> +	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
>