Re: [PATCH 1/2] common: introduce zone_capacity() to return a zone capacity

[Naohiro Aota <Naohiro.Aota@wdc.com>]

On Wed, Sep 28, 2022 at 08:32:47AM -0700, Darrick J. Wong wrote:
> On Wed, Sep 28, 2022 at 01:47:15PM +0800, Zorro Lang wrote:
> > On Wed, Sep 28, 2022 at 03:57:08AM +0000, Naohiro Aota wrote:
> > > On Fri, Sep 23, 2022 at 07:51:26PM +0800, Zorro Lang wrote:
> > > > On Fri, Sep 23, 2022 at 08:02:10AM +0000, Johannes Thumshirn wrote:
> > > > > On 22.09.22 17:42, Zorro Lang wrote:
> > > > > >> --- /dev/null
> > > > > >> +++ b/common/zbd
> > > > > > I don't like this abbreviation :-P If others don't open this file and read the
> > > > > > comment in it, they nearly no chance to guess what's this file for.
> > > > > > 
> > > > > 
> > > > > zbd is a well known abbreviation for zoned block devices. I think most
> > > > > people in storage and filesystems know it.
> > > > 
> > > > OK, but we haven't been that "a single character is worth a thousand
> > > > pieces of gold", so we can use a longer name, likes common/zone,
> > > > common/zoned, common/zoned_block, common/zoned_device or something likes
> > > > that. Anyway, that's just my personal opinion, if most of people prefer
> > > > using "common/zbd", I'm fine to have that :) 
> > > 
> > > Sure. I'll use "zoned" as it is more common in the kernel code.
> > > 
> > > > But I hope you can move all zoned block device related helpers to the new
> > > > common file if you'd like to bring in this file, likes what Darrick did in:
> > > > 
> > > > commit 67afd5c742464607994316acb2c6e8303b8af4c5
> > > > Author: Darrick J. Wong <djwong@kernel.org>
> > > > Date:   Tue Aug 9 14:00:46 2022 -0700
> > > > 
> > > >     common/rc: move ext4-specific helpers into a separate common/ext4 file
> > > 
> > > Yes, that will be better to have things in common/zoned. I considered
> > > moving zoned functions (_zone_type, _require_{,non_}zoned_device), but
> > > _require_loop() and _require_dm_target() use _require_non_zoned_device() in
> > > them. So, moving _require_non_zoned_device() will make a dependency from
> > > common/rc to common/zoned, which I considered not much clean. How do you
> > > think of it?
> > 
> > Oh, below commit [1] brought in the coupling of common/rc and zoned helpers.
> > Hmm... that cause all the 3 helpers (_zone_type, _require_{,non_}zoned_device)
> > have to be in common/rc or be imported in common/rc. Looks like we have to
> > keep them in common/rc, except we make a bigger refactor to common/rc, or you'd
> > like to make your 2 new helpers in common/rc too (likes these 3 old ones:)
> > 
> > BTW I doubt if we might need to use more zoned related helpers in common/rc, due
> > to we deal with test devices in common/rc mostly, likes dax. Someone might want
> > a seperated common/dax or common/pmem file one day. The common/rc imports
> > specific fs helpers according to $FSTYP (common/config: _source_specific_fs()).
> > If we need to deal with different kind of device types in common/rc one day, is
> > there a better idea to determine which one should be imported? Welcome any
> > suggestions if anyone has :)
> 
> Leave those three in common/rc and put/move the rest to common/zoned ?
> 
> I think it's fine for common/rc to have helpers that *detect* the
> presence of a blockdev feature, and require tests to source
> common/$feature if they want to do anything clever with that feature.
> After all, the _require_non_zoned_device tests don't care about
> _zone_capacity, right?

Thank you for your suggestions. Yes, _require_non_zoned_device() just read
/sys/block/${sdev}/queue/zoned. I'll do so to leave the three functions in
common/rc and move/create other helpers in common/zoned.

Thanks,

> --D
> 
> > [1]
> > commit 952310a57d9323ae0bb174b50be93107a8895e0c
> > Author: Naohiro Aota <naohiro.aota@wdc.com>
> > Date:   Mon Aug 16 20:35:08 2021 +0900
> > 
> >     common: add zoned block device checks
> > 
> > > 
> > > Moving _filter_blkzone_report() would be fine, though.
> > 
> > Yeah, moving this is fine.
> > 
> > Thanks,
> > Zorro
> > 
> > > 
> > > > Thanks,
> > > > Zorro
> > > > 
> > > > > 
> > > > > 
> > > > 
> > > 
> >