From: Gao Xiang <hsiangkao@linux.alibaba.com>
To: Matthew Wilcox <willy@infradead.org>
Cc: "Darrick J. Wong" <djwong@kernel.org>,
"Andreas Grünbacher" <andreas.gruenbacher@gmail.com>,
LKML <linux-kernel@vger.kernel.org>,
"Christoph Hellwig" <hch@infradead.org>,
"Joseph Qi" <joseph.qi@linux.alibaba.com>,
"Liu Bo" <bo.liu@linux.alibaba.com>,
"Linux FS-devel Mailing List" <linux-fsdevel@vger.kernel.org>,
"Liu Jiang" <gerry@linux.alibaba.com>,
linux-erofs@lists.ozlabs.org
Subject: Re: [PATCH 1/2] iomap: support tail packing inline read
Date: Sat, 17 Jul 2021 23:15:58 +0800 [thread overview]
Message-ID: <YPL0LqHzEbUY4zY/@B-P7TQMD6M-0146.local> (raw)
In-Reply-To: <YPLw0uc1jVKI8uKo@casper.infradead.org>
Hi Matthew,
On Sat, Jul 17, 2021 at 04:01:38PM +0100, Matthew Wilcox wrote:
> On Sat, Jul 17, 2021 at 09:38:18PM +0800, Gao Xiang wrote:
> > Sorry about some late. I've revised a version based on Christoph's
> > version and Matthew's thought above. I've preliminary checked with
> > EROFS, if it does make sense, please kindly help check on the gfs2
> > side as well..
>
> I don't understand how this bit works:
This part inherited from the Christoph version without change.
The following thoughts are just my own understanding...
>
> > struct page *page = ctx->cur_page;
> > - struct iomap_page *iop;
> > + struct iomap_page *iop = NULL;
> > bool same_page = false, is_contig = false;
> > loff_t orig_pos = pos;
> > 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;
> > - }
> > + if (iomap->type == IOMAP_INLINE && !pos)
> > + WARN_ON_ONCE(to_iomap_page(page) != NULL);
> > + else
> > + iop = iomap_page_create(inode, page);
>
> Imagine you have a file with bytes 0-2047 in an extent which is !INLINE
> and bytes 2048-2051 in the INLINE extent. When you read the page, first
> you create an iop for the !INLINE extent. Then this function is called
Yes, it first created an iop for the !INLINE extent.
> again for the INLINE extent and you'll hit the WARN_ON_ONCE. No?
If it is called again with another INLINE extent, pos will be non-0?
so (!pos) == false. Am I missing something?
Thanks,
Gao Xiang
>
next prev parent reply other threads:[~2021-07-17 15:16 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-07-16 5:07 [PATCH 0/2] erofs: iomap support for tailpacking cases Gao Xiang
2021-07-16 5:07 ` [PATCH 1/2] iomap: support tail packing inline read Gao Xiang
2021-07-16 9:19 ` Christoph Hellwig
2021-07-16 9:46 ` Gao Xiang
2021-07-16 13:47 ` Matthew Wilcox
2021-07-16 14:38 ` Matthew Wilcox
2021-07-16 13:02 ` Matthew Wilcox
2021-07-16 13:56 ` Gao Xiang
2021-07-16 14:44 ` Matthew Wilcox
2021-07-16 15:03 ` Gao Xiang
2021-07-16 15:53 ` Andreas Grünbacher
2021-07-17 13:38 ` Gao Xiang
2021-07-17 15:01 ` Matthew Wilcox
2021-07-17 15:15 ` Gao Xiang [this message]
2021-07-17 18:40 ` Matthew Wilcox
2021-07-19 11:19 ` Christoph Hellwig
2021-07-19 13:45 ` Gao Xiang
2021-07-19 11:15 ` Christoph Hellwig
2021-07-19 13:31 ` Gao Xiang
2021-07-16 5:07 ` [PATCH 2/2] erofs: convert all uncompressed cases to iomap Gao Xiang
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