Re: [PATCH] Documentation: document the design of iomap and how to port

[Ritesh Harjani (IBM) <ritesh.list@gmail.com>]

"Darrick J. Wong" <djwong@kernel.org> writes:

> On Tue, Jun 11, 2024 at 12:13:22PM +0530, Ritesh Harjani wrote:
>> "Darrick J. Wong" <djwong@kernel.org> writes:
>> 

<snip>
>> >> > + * ``addr`` describes the device address, in bytes.
>> >> > +
>> >> > + * ``bdev`` describes the block device for this mapping.
>> >> > +   This only needs to be set for mapped or unwritten operations.
>> >> > +
>> >> > + * ``dax_dev`` describes the DAX device for this mapping.
>> >> > +   This only needs to be set for mapped or unwritten operations, and
>> >> > +   only for a fsdax operation.
>> >> 
>> >> Looks like we can make this union (bdev and dax_dev). Since depending
>> >> upon IOMAP_DAX or not we only set either dax_dev or bdev.
>> >
>> > Separate patch. ;)
>> >
>> 
>> Yes, in a way I was trying to get an opinion from you and others on
>> whether it make sense to make bdev and dax_dev as union :)
>> 
>> Looks like this series [1] could be the reason for that. 
>> 
>> [1]: https://lore.kernel.org/all/20211129102203.2243509-1-hch@lst.de/#t
>> 
>> I also don't see any reference to dax code from fs/iomap/buffered-io.c
>> So maybe we don't need this dax.h header in this file.
>> 
>> diff --git a/fs/iomap/buffered-io.c b/fs/iomap/buffered-io.c
>> index c5802a459334..e1a6cca3cec2 100644
>> --- a/fs/iomap/buffered-io.c
>> +++ b/fs/iomap/buffered-io.c
>> @@ -10,7 +10,6 @@
>>  #include <linux/pagemap.h>
>>  #include <linux/uio.h>
>>  #include <linux/buffer_head.h>
>> -#include <linux/dax.h>
>>  #include <linux/writeback.h>
>>  #include <linux/list_sort.h>
>>  #include <linux/swap.h>
>
> Yes, given that both you and hch have mentioned it, could one of you
> send a cleanup series for that?
>

Sure, Thanks Darrick and Christoph.
I can queue this with my other work where I am improving iomap for
indirect-block mapping, so that it will be easier to get testing done on
all of this together.

-ritesh