Re: [PATCH 01/10] btrfs: remove a bunch of pointles stripe_len arguments

[Christoph Hellwig <hch@lst.de>]

On Mon, Jun 20, 2022 at 07:16:08PM +0200, David Sterba wrote:
> On Fri, Jun 17, 2022 at 12:04:05PM +0200, Christoph Hellwig wrote:
> > The raid56 code assumes a fixed stripe length.
> 
> The code does because it was part of the initial implementation but
> raid56 as a feature wants a configurable stripe size, we have a super
> block member for that. So the question is if passing the parameter is
> such a burden so we'd rather remove it or keep it there though it's a
> fixed value but still part of the design.
> 
> I'd rather keep it there so it gets used eventually, we have ongoing
> work to fix the corner cases of raid56 so removing and adding it back
> causes churn, but I'll give it another thought.

Well, right now it is very much dead code and complicates a lot
of the argument passing as well as bloating the code size.

IFF the superblock member were to be actually used in the future,
it would make sense to expose it in the btrfs_fs_info and use that
instead of the constant, but still skip all the argument passing.

hch@brick:~/work/linux$ size btrfs.o.*
   text	   data	    bss	    dec	    hex	filename
1502453	 125590	  28776	1656819	 1947f3	btrfs.o.new
1502599	 125590	  28776	1656965	 194885	btrfs.o.old