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From: Gao Xiang <hsiangkao@linux.alibaba.com>
To: Christoph Hellwig <hch@infradead.org>
Cc: "Darrick J. Wong" <djwong@kernel.org>,
	Andreas Gr??nbacher <andreas.gruenbacher@gmail.com>,
	LKML <linux-kernel@vger.kernel.org>,
	Matthew Wilcox <willy@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: Mon, 19 Jul 2021 21:31:15 +0800	[thread overview]
Message-ID: <YPV+o+V7wU32j6m3@B-P7TQMD6M-0146.local> (raw)
In-Reply-To: <YPVe41YqpfGLNsBS@infradead.org>

On Mon, Jul 19, 2021 at 12:15:47PM +0100, Christoph Hellwig wrote:
> On Sat, Jul 17, 2021 at 09:38:18PM +0800, Gao Xiang wrote:
> > >From 62f367245492e389711bcebbf7da5adae586299f Mon Sep 17 00:00:00 2001
> > From: Christoph Hellwig <hch@lst.de>
> > Date: Fri, 16 Jul 2021 10:52:48 +0200
> > Subject: [PATCH] iomap: support tail packing inline read
> 
> I'd still credit this to you as you did all the hard work.

Ok.

> 
> > +	/* inline source data must be inside a single page */
> > +	BUG_ON(iomap->length > PAGE_SIZE - offset_in_page(iomap->inline_data));
> > +	/* handle tail-packing blocks cross the current page into the next */
> > +	if (size > PAGE_SIZE - poff)
> > +		size = PAGE_SIZE - poff;
> 
> This should probably use min or min_t.

Okay, will update.

> 
> >  
> >  	addr = kmap_atomic(page);
> > -	memcpy(addr, iomap->inline_data, size);
> > -	memset(addr + size, 0, PAGE_SIZE - size);
> > +	memcpy(addr + poff, iomap->inline_data - iomap->offset + pos, size);
> > +	memset(addr + poff + size, 0, PAGE_SIZE - poff - size);
> >  	kunmap_atomic(addr);
> > -	SetPageUptodate(page);
> > +	flush_dcache_page(page);
> 
> The flush_dcache_page addition should be a separate patch.

I wondered what is the target order of recent iomap patches, since this is
a quite small change, so I'd like to just rebase on for-next for now . So
ok, I won't touch this in this patchset and I think flush_dcache_page() does
no harm to x86(_64) and arm(64) at least if I remember correctly.

> 
> >  
> >  	if (dio->flags & IOMAP_DIO_WRITE) {
> >  		loff_t size = inode->i_size;
> > @@ -394,7 +395,8 @@ iomap_dio_inline_actor(struct inode *inode, loff_t pos, loff_t length,
> >  			mark_inode_dirty(inode);
> >  		}
> >  	} else {
> > -		copied = copy_to_iter(iomap->inline_data + pos, length, iter);
> > +		copied = copy_to_iter(iomap->inline_data + pos - iomap->offset,
> > +				length, iter);
> 
> We also need to take the offset into account for the write side.
> I guess it would be nice to have a local variable for the inline
> address to not duplicate that calculation multiple times.

ok. Will update.

Thanks,
Gao Xiang


  reply	other threads:[~2021-07-19 13:31 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
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 [this message]
2021-07-16  5:07 ` [PATCH 2/2] erofs: convert all uncompressed cases to iomap Gao Xiang

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