linux-ext4 - Re: [PATCH] writeback: avoid double-writing the inode on a lazytime expiration

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Message-ID: <20200320024639.GH1067245@mit.edu>
Date:   Thu, 19 Mar 2020 22:46:39 -0400
From:   "Theodore Y. Ts'o" <tytso@....edu>
To:     Christoph Hellwig <hch@...radead.org>
Cc:     Dave Chinner <david@...morbit.com>,
        Eric Biggers <ebiggers@...nel.org>,
        Linux Filesystem Development List 
        <linux-fsdevel@...r.kernel.org>,
        Ext4 Developers List <linux-ext4@...r.kernel.org>,
        linux-f2fs-devel@...ts.sourceforge.net, linux-xfs@...r.kernel.org
Subject: Re: [PATCH] writeback: avoid double-writing the inode on a lazytime
 expiration

On Thu, Mar 12, 2020 at 07:34:45AM -0700, Christoph Hellwig wrote:
> I haven't seen the original mail this replies to, but if we could
> get the lazytime expirty by some other means (e.g. an explicit
> callback), XFS could opt out of all the VFS inode tracking again,
> which would simplify a few things.

Part of my thinking of calling 

       inode->i_sb->s_op->dirty_inode(inode, I_DIRTY_TIME_EXPIRED);

So that it would be an explicit callback to XFS.  So why don't I break
this as two patches --- one which uses I_DIRTY_SYNC, as before, and a
second one which changes calls dirty_inode() with
I_DIRTY_TIME_EXPIRED, and with a change to XFS so that it recognizes
I_DIRTY_TIME_EXPIRED as if it were I_DIRTY_SYNC.  If this would then
allow XFS to simplify how it handles VFS tracking, you could do that
in a separate patch.

Does that work?  I'll send out the two patches, and if you can
review/ack the second patch, that would be great.

	       	      	     	  	- Ted