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From: Al Viro <viro@zeniv.linux.org.uk>
To: "Fabio M. De Francesco" <fmdefrancesco@gmail.com>
Cc: Evgeniy Dushistov <dushistov@mail.ru>,
	Christian Brauner <brauner@kernel.org>,
	linux-kernel@vger.kernel.org, bpf@vger.kernel.org,
	"Venkataramanan, Anirudh" <anirudh.venkataramanan@intel.com>,
	Ira Weiny <ira.weiny@intel.com>
Subject: Re: [RESEND PATCH v4] fs/ufs: Replace kmap() with kmap_local_page()
Date: Fri, 25 Nov 2022 22:50:56 +0000	[thread overview]
Message-ID: <Y4FG0O7VWTTng5yh@ZenIV> (raw)
In-Reply-To: <Y4E++JERgUMoqfjG@ZenIV>

On Fri, Nov 25, 2022 at 10:17:28PM +0000, Al Viro wrote:

> The bottom line:
> 	* teach your ufs_put_page() to accept any address within the page
> 	* flip the ways you return page and address in ufs_get_page()
> 	* use offset_in_page(addr) instead of these addr - page_address(page)
> and you'll get a much smaller patch, with a lot less noise in it.
> What's more, offset_in_page() part can be carved out into a separate
> commit - it's valid on its own, and it makes both halves easier to
> follow.
> 
> AFAICS, similar observations apply in your sysvfs patch; the point about
> calling conventions for ufs_get_page() definitely applies there, and
> stronger than for ufs - those casts are eye-watering...

As the matter of fact, I'd probably split it into 3 steps:
	1) switch the calling conventions of ufs_get_page() - callers follow
it with something like kaddr = page_address(page); and that change makes
sense on its own.  Isolated and easy to follow.
	2) offset_in_page() changes.  Again, separate, stands on its own and
is easy to follow.
	3) kmap_local() switch itself - pass address to ufs_put_page(), etc.
Considerably smaller and less cluttered than your current variant.

  reply	other threads:[~2022-11-25 22:51 UTC|newest]

Thread overview: 7+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-10-16 16:38 [RESEND PATCH v4] fs/ufs: Replace kmap() with kmap_local_page() Fabio M. De Francesco
2022-11-25 16:19 ` Fabio M. De Francesco
2022-11-25 22:17 ` Al Viro
2022-11-25 22:50   ` Al Viro [this message]
2022-11-26 14:12     ` Fabio M. De Francesco
2022-11-27 16:15       ` Al Viro
2022-11-28 23:06         ` Fabio M. De Francesco

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