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From: "Theodore Y. Ts'o" <tytso@mit.edu>
To: Christoph Hellwig <hch@infradead.org>
Cc: Ext4 Developers List <linux-ext4@vger.kernel.org>,
	linux-f2fs-devel@lists.sourceforge.net,
	linux-xfs@vger.kernel.org, Eric Biggers <ebiggers@kernel.org>,
	Richard Weinberger <richard@nod.at>
Subject: Re: [PATCH 1/2] writeback: avoid double-writing the inode on a lazytime expiration
Date: Wed, 25 Mar 2020 11:21:13 -0400	[thread overview]
Message-ID: <20200325152113.GK53396@mit.edu> (raw)
In-Reply-To: <20200325092057.GA25483@infradead.org>

On Wed, Mar 25, 2020 at 02:20:57AM -0700, Christoph Hellwig wrote:
> >  	spin_unlock(&inode->i_lock);
> >  
> > -	if (dirty & I_DIRTY_TIME)
> > -		mark_inode_dirty_sync(inode);
> > +	/* This was a lazytime expiration; we need to tell the file system */
> > +	if (dirty & I_DIRTY_TIME_EXPIRED && inode->i_sb->s_op->dirty_inode)
> > +		inode->i_sb->s_op->dirty_inode(inode, I_DIRTY_SYNC);
> 
> I think this needs a very clear comment explaining why we don't go
> through __mark_inode_dirty.

I can take the explanation which is in the git commit description and
move it into the comment.

> But as said before I'd rather have a new lazytime_expired operation that
> makes it very clear what is happening.  We currenly have 4 file systems
> (ext4, f2fs, ubifs and xfs) that support lazytime, so this won't really
> be a major churn.

Again, I believe patch #2 does what you want; if it doesn't can you
explain why passing I_DIRTY_TIME_EXPIRED to s_op->dirty_inode() isn't
"a new lazytime expired operation that makes very clear what is
happening"?

I separated out patch #1 and patch #2 because patch #1 preserves
current behavior, and patch #2 modifies XFS code, which I don't want
to push Linus without an XFS reviewed-by.

N.b.  None of the other file systems required a change for patch #2,
so if you want, we can have the XFS tree carry patch #2, and/or
combine that with whatever other simplifying changes that you want.
Or I can combine patch #1 and patch #2, with an XFS Reviewed-by, and
send it through the ext4 tree.

What's your pleasure?

					- Ted


  reply	other threads:[~2020-03-25 15:21 UTC|newest]

Thread overview: 17+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-03-06  0:45 lazytime causing inodes to remain dirty after sync? Eric Biggers
2020-03-07  2:00 ` [PATCH] writeback: avoid double-writing the inode on a lazytime expiration Theodore Ts'o
2020-03-11  3:20   ` Eric Biggers
2020-03-11 12:57     ` Theodore Y. Ts'o
2020-03-12  0:07       ` Dave Chinner
2020-03-12 14:34         ` Christoph Hellwig
2020-03-12 22:39           ` Dave Chinner
2020-03-20  2:46           ` Theodore Y. Ts'o
2020-03-20  2:52             ` [PATCH 1/2] " Theodore Ts'o
2020-03-20  2:52               ` [PATCH 2/2] writeback, xfs: call dirty_inode() with I_DIRTY_TIME_EXPIRED when appropriate Theodore Ts'o
2020-03-23 17:58                 ` Theodore Y. Ts'o
2020-03-24  8:37                   ` Christoph Hellwig
2020-03-24 18:43                     ` Theodore Y. Ts'o
2020-03-25  9:20               ` [PATCH 1/2] writeback: avoid double-writing the inode on a lazytime expiration Christoph Hellwig
2020-03-25 15:21                 ` Theodore Y. Ts'o [this message]
2020-03-25 15:47                   ` Darrick J. Wong
2020-03-11 23:54     ` [PATCH] " Dave Chinner

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