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From: Goldwyn Rodrigues <rgoldwyn@suse.de>
To: Qu Wenruo <quwenruo.btrfs@gmx.com>
Cc: darrick.wong@oracle.com, linux-btrfs@vger.kernel.org,
	fdmanana@gmail.com, linux-fsdevel@vger.kernel.org, hch@lst.de
Subject: Re: [PATCH 0/3] Transient errors in Direct I/O
Date: Thu, 11 Jun 2020 09:11:27 -0500	[thread overview]
Message-ID: <20200611141127.ir7b3ohd3c3qtunu@fiona> (raw)
In-Reply-To: <3e11c9ae-15c5-c52a-2e8a-14756a5ef967@gmx.com>

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On 13:31 10/06, Qu Wenruo wrote:
> 
> 
> On 2020/6/6 上午4:48, Goldwyn Rodrigues wrote:
> > In current scenarios, for XFS, it would mean that a page invalidation
> > would end up being a writeback error. So, if iomap returns zero, fall
> > back to biffered I/O. XFS has never supported fallback to buffered I/O.
> > I hope it is not "never will" ;)
> > 
> > With mixed buffered and direct writes in btrfs, the pages may not be
> > released the extent may be locked in the ordered extents cleanup thread,
> 
> I'm wondering can we handle this case in a different way.
> 
> In fact btrfs has its own special handling for invalidating pages.
> Btrfs will first look for any ordered extents covering the page, finish
> the ordered extent manually, then invalidate the page.
> 
> I'm not sure why invalidate_inode_pages2_range() used in dio iomap code
> does not use the fs specific invalidatepage(), but only do_lander_page()
> then releasepage().
> 
> Shouldn'y we btrfs implement the lander_page() to handle ordered extents
> properly?
> Or is there any special requirement?
> 

The problem is aops->launder_page() is called only if PG_Dirty is
set. In this case it is not because we just performed a writeback.

Also, it is not just ordered ordered extent writeback which may lock
the extent, a buffered read can lock as well.

-- 
Goldwyn

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  reply	other threads:[~2020-06-11 14:11 UTC|newest]

Thread overview: 13+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-06-05 20:48 Goldwyn Rodrigues
2020-06-05 20:48 ` [PATCH 1/3] iomap: dio Return zero in case of unsuccessful pagecache invalidation Goldwyn Rodrigues
2020-06-06  3:13   ` Matthew Wilcox
2020-06-05 20:48 ` [PATCH 2/3] btrfs: Wait for extent bits to release page Goldwyn Rodrigues
2020-06-08 10:20   ` Filipe Manana
2020-06-08 12:13     ` Goldwyn Rodrigues
2020-06-05 20:48 ` [PATCH 3/3] xfs: fallback to buffered I/O if direct I/O is short Goldwyn Rodrigues
2020-06-10  2:59 ` [PATCH 0/3] Transient errors in Direct I/O Dave Chinner
2020-06-10  5:05   ` Dave Chinner
2020-06-11 14:13     ` Goldwyn Rodrigues
2020-06-10  5:31 ` Qu Wenruo
2020-06-11 14:11   ` Goldwyn Rodrigues [this message]
2020-06-12 12:56     ` Qu Wenruo

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