linux-kernel - Re: [PATCH 1/4] iomap: make sure iomap_adjust_read_range() are aligned with block

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Message-ID: <20250914124006.3597588-1-alexjlzheng@tencent.com>
Date: Sun, 14 Sep 2025 20:40:06 +0800
From: Jinliang Zheng <alexjlzheng@...il.com>
To: kernel@...kajraghav.com
Cc: alexjlzheng@...il.com,
	alexjlzheng@...cent.com,
	brauner@...nel.org,
	djwong@...nel.org,
	hch@...radead.org,
	linux-fsdevel@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	linux-xfs@...r.kernel.org,
	yi.zhang@...wei.com
Subject: Re: [PATCH 1/4] iomap: make sure iomap_adjust_read_range() are aligned with block_size

On Sun, 14 Sep 2025 13:45:16 +0200, kernel@...kajraghav.com wrote:
> On Sat, Sep 14, 2025 at 11:37:15AM +0800, alexjlzheng@...il.com wrote:
> > From: Jinliang Zheng <alexjlzheng@...cent.com>
> > 
> > iomap_folio_state marks the uptodate state in units of block_size, so
> > it is better to check that pos and length are aligned with block_size.
> > 
> > Signed-off-by: Jinliang Zheng <alexjlzheng@...cent.com>
> > ---
> >  fs/iomap/buffered-io.c | 3 +++
> >  1 file changed, 3 insertions(+)
> > 
> > diff --git a/fs/iomap/buffered-io.c b/fs/iomap/buffered-io.c
> > index fd827398afd2..0c38333933c6 100644
> > --- a/fs/iomap/buffered-io.c
> > +++ b/fs/iomap/buffered-io.c
> > @@ -234,6 +234,9 @@ static void iomap_adjust_read_range(struct inode *inode, struct folio *folio,
> >  	unsigned first = poff >> block_bits;
> >  	unsigned last = (poff + plen - 1) >> block_bits;
> >  
> > +	WARN_ON(*pos & (block_size - 1));
> > +	WARN_ON(length & (block_size - 1));
> Any reason you chose WARN_ON instead of WARN_ON_ONCE?

I just think it's a fatal error that deserves attention every time
it's triggered.

> 
> I don't see WARN_ON being used in iomap/buffered-io.c.

I'm not sure if there are any community guidelines for using these
two macros. If there are, please let me know and I'll be happy to
follow them as a guide.

thanks,
Jinliang Zheng. :)

> --
> Pankaj