linux-kernel - Re: [PATCH 3/5] block: remove support for the host aware zone model

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Message-ID: <dbc4a5b4296effd88ba0ef939aa324df0969545c.camel@mediatek.com>
Date: Tue, 19 Dec 2023 08:08:03 +0000
From: Ed Tsai (蔡宗軒) <Ed.Tsai@...iatek.com>
To: "Naohiro.Aota@....com" <Naohiro.Aota@....com>
CC: "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"dlemoal@...nel.org" <dlemoal@...nel.org>, "virtualization@...ts.linux.dev"
	<virtualization@...ts.linux.dev>, "hch@....de" <hch@....de>,
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	<axboe@...nel.dk>, Chun-Hung Wu (巫駿宏)
	<Chun-hung.Wu@...iatek.com>, "linux-scsi@...r.kernel.org"
	<linux-scsi@...r.kernel.org>, "dm-devel@...ts.linux.dev"
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	<linux-btrfs@...r.kernel.org>, "linux-f2fs-devel@...ts.sourceforge.net"
	<linux-f2fs-devel@...ts.sourceforge.net>, "stefanha@...hat.com"
	<stefanha@...hat.com>
Subject: Re: [PATCH 3/5] block: remove support for the host aware zone model

On Tue, 2023-12-19 at 07:16 +0000, Naohiro Aota wrote:
>  	 
> External email : Please do not click links or open attachments until
> you have verified the sender or the content.
>  On Mon, Dec 18, 2023 at 08:21:22AM +0000, Ed Tsai (蔡宗軒) wrote:
> > On Mon, 2023-12-18 at 15:53 +0900, Damien Le Moal wrote:
> > >  On 2023/12/18 15:15, Ed Tsai (蔡宗軒) wrote:
> > > > Hi Christoph,
> > > > 
> > > > some minor suggestions:
> > > > 
> > > > On Sun, 2023-12-17 at 17:53 +0100, Christoph Hellwig wrote:
> > > >>
> > > >> diff --git a/drivers/md/dm-table.c b/drivers/md/dm-table.c
> > > >> index 198d38b53322c1..260b5b8f2b0d7e 100644
> > > >> --- a/drivers/md/dm-table.c
> > > >> +++ b/drivers/md/dm-table.c
> > > >> @@ -1579,21 +1579,18 @@ bool
> dm_table_has_no_data_devices(struct
> > > >> dm_table *t)
> > > >>  return true;
> > > >>  }
> > > >>  
> > > >> -static int device_not_zoned_model(struct dm_target *ti,
> struct
> > > >> dm_dev *dev,
> > > >> -  sector_t start, sector_t len, void
> > > >> *data)
> > > >> +static int device_not_zoned(struct dm_target *ti, struct
> dm_dev
> > > >> *dev,
> > > >> +    sector_t start, sector_t len, void *data)
> > > >>  {
> > > >> -struct request_queue *q = bdev_get_queue(dev->bdev);
> > > >> -enum blk_zoned_model *zoned_model = data;
> > > >> +bool *zoned = data;
> > > >>  
> > > >> -return blk_queue_zoned_model(q) != *zoned_model;
> > > >> +return bdev_is_zoned(dev->bdev) != *zoned;
> > > >>  }
> > > >>  
> > > >>  static int device_is_zoned_model(struct dm_target *ti, struct
> > > dm_dev
> > > >> *dev,
> > > >>   sector_t start, sector_t len, void
> > > >> *data)
> > > > 
> > > > Seems like the word "model" should also be remove here.
> > > > 
> > > >>  {
> > > >> -struct request_queue *q = bdev_get_queue(dev->bdev);
> > > >> -
> > > >> -return blk_queue_zoned_model(q) != BLK_ZONED_NONE;
> > > >> +return bdev_is_zoned(dev->bdev);
> > > >>  }
> > > >>  
> > > >>  /*
> > > >> @@ -1603,8 +1600,7 @@ static int device_is_zoned_model(struct
> > > >> dm_target *ti, struct dm_dev *dev,
> > > >>   * has the DM_TARGET_MIXED_ZONED_MODEL feature set, the
> devices
> > > can
> > > >> have any
> > > >>   * zoned model with all zoned devices having the same zone
> size.
> > > >>   */
> > > >> -static bool dm_table_supports_zoned_model(struct dm_table *t,
> > > >> -  enum blk_zoned_model
> > > >> zoned_model)
> > > >> +static bool dm_table_supports_zoned(struct dm_table *t, bool
> > > zoned)
> > > >>  {
> > > >>  for (unsigned int i = 0; i < t->num_targets; i++) {
> > > >>  struct dm_target *ti = dm_table_get_target(t, i);
> > > >> @@ -1623,11 +1619,11 @@ static bool
> > > >> dm_table_supports_zoned_model(struct dm_table *t,
> > > >>  
> > > >>  if (dm_target_supports_zoned_hm(ti->type)) {
> > > >>  if (!ti->type->iterate_devices ||
> > > >> -    ti->type->iterate_devices(ti,
> > > >> device_not_zoned_model,
> > > >> -      &zoned_model))
> > > >> +    ti->type->iterate_devices(ti,
> > > >> device_not_zoned,
> > > >> +      &zoned))
> > > >>  return false;
> > > >>  } else if (!dm_target_supports_mixed_zoned_model(ti-
> > > >>> type)) {
> > > >> -if (zoned_model == BLK_ZONED_HM)
> > > >> +if (zoned)
> > > >>  return false;
> > > >>  }
> > > >>  }
> > > > 
> > > > The parameter "bool zoned" is redundant. It should be removed
> from
> > > the
> > > > above 3 functions
> > 
> > The two func, is zoned and not zoned, are essentially the same.
> They
> > can be simplified into one function.
> 
> Both functions are used for iterate_devices's callback in
> dm_table_supports_zoned_model(). As shown in raid_iterate_devices(),
> iterate_devices() returns 0 if the callback func calls on all the
> devices
> returns 0, or returns a non-zero result early otherwise. So, the
> iterate_devices() call returns "true" if any one of the underlying
> devices
> is (zoned|not zoned).
> 
> Since we cannot create lambda as in other fancy languages, we need
> two
> functions...

Not really, there is a "void *data" can be used.

The device_is_zoned_model() is just the same as the device_not_zoned()
with (bool *)data = false.

It's very minor, so is okay to ignore my preference.