Re: [RFC 5/9] SQUASHME: prd: Last fixes for partitions

[Boaz Harrosh <boaz@plexistor.com>]

On 08/14/2014 04:16 PM, Matthew Wilcox wrote:
> On Thu, Aug 14, 2014 at 04:04:53PM +0300, Boaz Harrosh wrote:
>>> @@ -218,13 +218,13 @@ static long prd_direct_access(struct block_device *bdev, sector_t sector,
>>>  {
>>>  	struct prd_device *prd = bdev->bd_disk->private_data;
>>>  
>>> -	if (!prd)
>>> +	if (unlikely(!prd))
>>>  		return -ENODEV;
>>>  
>>>  	*kaddr = prd_lookup_pg_addr(prd, sector);
>>>  	*pfn = prd_lookup_pfn(prd, sector);
>>>  
>>> -	return size;
>>> +	return min_t(long, size, prd->size);
>>
>> This is off course a BUG need to subtract offset, will send version 2
> 
> I was wondering about simplifying the return value for the drivers
> a little.  Something like this:
> 

Sure, looks good

I will produce a V2 for the brd-partitions set to send Jens, sometime
next week.

Thanks
Boaz

> diff --git a/arch/powerpc/sysdev/axonram.c b/arch/powerpc/sysdev/axonram.c
> index 741293f..8709b9f 100644
> --- a/arch/powerpc/sysdev/axonram.c
> +++ b/arch/powerpc/sysdev/axonram.c
> @@ -149,7 +149,7 @@ axon_ram_direct_access(struct block_device *device, sector_t sector,
>  	*kaddr = (void *)(bank->ph_addr + offset);
>  	*pfn = virt_to_phys(*kaddr) >> PAGE_SHIFT;
>  
> -	return min_t(long, size, bank->size - offset);
> +	return bank->size - offset;
>  }
>  
>  static const struct block_device_operations axon_ram_devops = {
> diff --git a/drivers/block/brd.c b/drivers/block/brd.c
> index 3483458..344681a 100644
> --- a/drivers/block/brd.c
> +++ b/drivers/block/brd.c
> @@ -384,9 +384,9 @@ static long brd_direct_access(struct block_device *bdev, sector_t sector,
>  	*kaddr = page_address(page);
>  	*pfn = page_to_pfn(page);
>  
> -	/* Could optimistically check to see if the next page in the
> -	 * file is mapped to the next page of physical RAM */
> -	return min_t(long, PAGE_SIZE, size);
> +	/* If size > PAGE_SIZE, we could look to see if the next page in the
> +	 * file happens to be mapped to the next page of physical RAM */
> +	return PAGE_SIZE;
>  }
>  #else
>  #define brd_direct_access NULL
> diff --git a/drivers/block/prd.c b/drivers/block/prd.c
> index cc0aabf..1cfbd5b 100644
> --- a/drivers/block/prd.c
> +++ b/drivers/block/prd.c
> @@ -216,7 +216,7 @@ static long prd_direct_access(struct block_device *bdev, sector_t sector,
>  	*kaddr = prd_lookup_pg_addr(prd, sector);
>  	*pfn = prd_lookup_pfn(prd, sector);
>  
> -	return size;
> +	return size - (sector * 512);
>  }
>  
>  static const struct block_device_operations prd_fops = {
> diff --git a/drivers/s390/block/dcssblk.c b/drivers/s390/block/dcssblk.c
> index 2ee5556..96bc411 100644
> --- a/drivers/s390/block/dcssblk.c
> +++ b/drivers/s390/block/dcssblk.c
> @@ -881,7 +881,7 @@ dcssblk_direct_access (struct block_device *bdev, sector_t secnum,
>  	*kaddr = (void *) (dev_info->start + offset);
>  	*pfn = virt_to_phys(*kaddr) >> PAGE_SHIFT;
>  
> -	return min_t(long, size, dev_sz - offset);
> +	return dev_sz - offset;
>  }
>  
>  static void
> diff --git a/fs/block_dev.c b/fs/block_dev.c
> index 93ebdd53..ce3e69c 100644
> --- a/fs/block_dev.c
> +++ b/fs/block_dev.c
> @@ -447,6 +447,7 @@ EXPORT_SYMBOL_GPL(bdev_write_page);
>  long bdev_direct_access(struct block_device *bdev, sector_t sector,
>  			void **addr, unsigned long *pfn, long size)
>  {
> +	long max;
>  	const struct block_device_operations *ops = bdev->bd_disk->fops;
>  	if (!ops->direct_access)
>  		return -EOPNOTSUPP;
> @@ -456,8 +457,10 @@ long bdev_direct_access(struct block_device *bdev, sector_t sector,
>  	sector += get_start_sect(bdev);
>  	if (sector % (PAGE_SIZE / 512))
>  		return -EINVAL;
> -	size = ops->direct_access(bdev, sector, addr, pfn, size);
> -	return size ? size : -ERANGE;
> +	max = ops->direct_access(bdev, sector, addr, pfn, size);
> +	if (!max)
> +		return -ERANGE;
> +	return min(max, size);
>  }
>  EXPORT_SYMBOL_GPL(bdev_direct_access);
>  
>