Re: [PATCH v4 1/3] fs: allow per-device dax status checking for filesystems

[Dave Jiang <dave.jiang@intel.com>]

On 02/15/2018 10:52 AM, Christoph Hellwig wrote:
>>  /**
>> - * __bdev_dax_supported() - Check if the device supports dax for filesystem
>> + * bdev_dax_supported() - Check if the device supports dax for filesystem
>>   * @sb: The superblock of the device
>> + * @bdev: block device to check
>>   * @blocksize: The block size of the device
>>   *
>>   * This is a library function for filesystems to check if the block device
>> @@ -82,9 +83,9 @@ EXPORT_SYMBOL_GPL(fs_dax_get_by_bdev);
>>   *
>>   * Return: negative errno if unsupported, 0 if supported.
>>   */
>> -int __bdev_dax_supported(struct super_block *sb, int blocksize)
>> +int bdev_dax_supported(struct super_block *sb, struct block_device *bdev,
>> +		       int blocksize)
>>  {
>> -	struct block_device *bdev = sb->s_bdev;
>>  	struct dax_device *dax_dev;
>>  	pgoff_t pgoff;
>>  	int err, id;
> 
> This now only uses sb for sb->s_id.  It might be better to use bdevname
> to print the device name and don't bother passing a sb at all.
> 

I think Darrick wanted to keep the API the same for non-XFS users. I'm
ok with dropping the passed in sb if Darrick has no objections.