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From: Matthew Wilcox <willy@infradead.org>
To: Gao Xiang <hsiangkao@linux.alibaba.com>
Cc: "Darrick J . Wong" <djwong@kernel.org>,
	Andreas Gruenbacher <andreas.gruenbacher@gmail.com>,
	LKML <linux-kernel@vger.kernel.org>,
	linux-fsdevel@vger.kernel.org, linux-erofs@lists.ozlabs.org,
	Christoph Hellwig <hch@lst.de>
Subject: Re: [PATCH v3] iomap: support tail packing inline read
Date: Mon, 19 Jul 2021 16:02:30 +0100	[thread overview]
Message-ID: <YPWUBhxhoaEp8Frn@casper.infradead.org> (raw)
In-Reply-To: <20210719144747.189634-1-hsiangkao@linux.alibaba.com>

On Mon, Jul 19, 2021 at 10:47:47PM +0800, Gao Xiang wrote:
> @@ -246,18 +245,19 @@ iomap_readpage_actor(struct inode *inode, loff_t pos, loff_t length, void *data,
>  	unsigned poff, plen;
>  	sector_t sector;
>  
> -	if (iomap->type == IOMAP_INLINE) {
> -		WARN_ON_ONCE(pos);
> -		iomap_read_inline_data(inode, page, iomap);
> -		return PAGE_SIZE;
> -	}
> -
> -	/* zero post-eof blocks as the page may be mapped */
>  	iop = iomap_page_create(inode, page);
> +	/* needs to skip some leading uptodated blocks */
>  	iomap_adjust_read_range(inode, iop, &pos, length, &poff, &plen);
>  	if (plen == 0)
>  		goto done;
>  
> +	if (iomap->type == IOMAP_INLINE) {
> +		iomap_read_inline_data(inode, page, iomap, pos);
> +		plen = PAGE_SIZE - poff;
> +		goto done;
> +	}

This is going to break Andreas' case that he just patched to work.
GFS2 needs for there to _not_ be an iop for inline data.  That's
why I said we need to sort out when to create an iop before moving
the IOMAP_INLINE case below the creation of the iop.

If we're not going to do that first, then I recommend leaving the
IOMAP_INLINE case where it is and changing it to ...

	if (iomap->type == IOMAP_INLINE)
		return iomap_read_inline_data(inode, page, iomap, pos);

... and have iomap_read_inline_data() return the number of bytes that
it copied + zeroed (ie PAGE_SIZE - poff).


  reply	other threads:[~2021-07-19 15:05 UTC|newest]

Thread overview: 13+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-07-19 14:47 Gao Xiang
2021-07-19 15:02 ` Matthew Wilcox [this message]
2021-07-19 15:13   ` Christoph Hellwig
2021-07-19 16:11     ` Gao Xiang
2021-07-19 16:31       ` Matthew Wilcox
2021-07-19 16:45         ` Gao Xiang
2021-07-19 15:29   ` Gao Xiang
2021-07-19 15:31     ` Andreas Grünbacher
2021-07-19 15:36       ` Gao Xiang
2021-07-20 11:23 ` Andreas Grünbacher
2021-07-20 12:10   ` Gao Xiang
2021-07-20 11:34 ` Andreas Grünbacher
2021-07-20 12:23   ` Gao Xiang

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