From: Matthew Wilcox <willy@infradead.org>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: linux-ext4@vger.kernel.org, gfs2@lists.linux.dev,
linux-fsdevel@vger.kernel.org, linux-xfs@vger.kernel.org,
"Darrick J . Wong" <djwong@kernel.org>,
linux-erofs@lists.ozlabs.org, Theodore Ts'o <tytso@mit.edu>,
Andreas Dilger <adilger.kernel@dilger.ca>,
Andreas Gruenbacher <agruenba@redhat.com>
Subject: Re: [PATCH 1/3] mm: Add folio_zero_tail() and use it in ext4
Date: Thu, 9 Nov 2023 17:37:28 +0000 [thread overview]
Message-ID: <ZU0Y2NEMMlkHYcr6@casper.infradead.org> (raw)
In-Reply-To: <20231108150606.2ec3cafb290f757f0e4c92d8@linux-foundation.org>
On Wed, Nov 08, 2023 at 03:06:06PM -0800, Andrew Morton wrote:
> >
> > +/**
> > + * folio_zero_tail - Zero the tail of a folio.
> > + * @folio: The folio to zero.
> > + * @kaddr: The address the folio is currently mapped to.
> > + * @offset: The byte offset in the folio to start zeroing at.
>
> That's the argument ordering I would expect.
>
> > + * If you have already used kmap_local_folio() to map a folio, written
> > + * some data to it and now need to zero the end of the folio (and flush
> > + * the dcache), you can use this function. If you do not have the
> > + * folio kmapped (eg the folio has been partially populated by DMA),
> > + * use folio_zero_range() or folio_zero_segment() instead.
> > + *
> > + * Return: An address which can be passed to kunmap_local().
> > + */
> > +static inline __must_check void *folio_zero_tail(struct folio *folio,
> > + size_t offset, void *kaddr)
>
> While that is not. addr,len is far more common that len,addr?
But that's not len! That's offset-in-the-folio. ie we're doing:
memset(folio_address(folio) + offset, 0, folio_size(folio) - offset);
If we were doing:
memset(folio_address(folio), 0, len);
then yes, your suggestion is the right order.
Indeed, having the arguments in the current order would hopefully make
filesystem authors realise that this _isn't_ "len".
next prev parent reply other threads:[~2023-11-09 17:37 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-11-07 21:26 [PATCH 0/3] Add folio_zero_tail() and folio_fill_tail() Matthew Wilcox (Oracle)
2023-11-07 21:26 ` [PATCH 1/3] mm: Add folio_zero_tail() and use it in ext4 Matthew Wilcox (Oracle)
2023-11-08 23:06 ` Andrew Morton
2023-11-09 0:12 ` Andreas Grünbacher
2023-11-09 17:27 ` Andrew Morton
2023-11-09 17:37 ` Matthew Wilcox [this message]
2023-11-09 21:50 ` Andreas Gruenbacher
2023-11-07 21:26 ` [PATCH 2/3] mm: Add folio_fill_tail() and use it in iomap Matthew Wilcox (Oracle)
2023-11-09 21:50 ` Andreas Gruenbacher
2023-11-10 17:09 ` Matthew Wilcox
2023-11-10 17:50 ` Andreas Grünbacher
2023-11-11 4:02 ` Gao Xiang
2023-11-07 21:26 ` [PATCH 3/3] gfs2: Convert stuffed_readpage() to stuffed_read_folio() Matthew Wilcox (Oracle)
2023-11-09 21:52 ` Andreas Gruenbacher
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