linux-ext4 - Re: [PATCH -next v2 03/22] ext4: only order data when partially block truncating down

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Message-ID: <yrnt4wyocyik4nwcamwk5noc7ilninlt7cmyggzwhwzjjsjzfc@uxdht432fgzm>
Date: Tue, 10 Feb 2026 15:07:49 +0100
From: Jan Kara <jack@...e.cz>
To: Zhang Yi <yi.zhang@...weicloud.com>
Cc: Jan Kara <jack@...e.cz>, linux-ext4@...r.kernel.org, 
	linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org, tytso@....edu, 
	adilger.kernel@...ger.ca, ojaswin@...ux.ibm.com, ritesh.list@...il.com, hch@...radead.org, 
	djwong@...nel.org, yizhang089@...il.com, libaokun1@...wei.com, yangerkun@...wei.com, 
	yukuai@...as.com
Subject: Re: [PATCH -next v2 03/22] ext4: only order data when partially
 block truncating down

On Tue 10-02-26 20:02:51, Zhang Yi wrote:
> On 2/9/2026 4:28 PM, Zhang Yi wrote:
> > On 2/6/2026 11:35 PM, Jan Kara wrote:
> >> On Fri 06-02-26 19:09:53, Zhang Yi wrote:
> >>> On 2/5/2026 11:05 PM, Jan Kara wrote:
> >>>> So how about the following:
> >>>
> >>> Let me see, please correct me if my understanding is wrong, ana there are
> >>> also some points I don't get.
> >>>
> >>>> We expand our io_end processing with the
> >>>> ability to journal i_disksize updates after page writeback completes. Then
> 
> While I was extending the end_io path of buffered_head to support updating
> i_disksize, I found another problem that requires discussion.
> 
> Supporting updates to i_disksize in end_io requires starting a handle, which
> conflicts with the data=ordered mode because folios written back through the
> journal process cannot initiate any handles; otherwise, this may lead to a
> deadlock. This limitation does not affect the iomap path, as it does not use
> the data=ordered mode at all.  However, in the buffered_head path, online
> defragmentation (if this change works, it should be the last user) still uses
> the data=ordered mode.

Right and my intention was to use reserved handle for the i_disksize update
similarly as we currently use reserved handle for unwritten extent
conversion after page writeback is done.

								Honza
-- 
Jan Kara <jack@...e.com>
SUSE Labs, CR