linux-kernel - Re: [PATCH RFC v5 10/10] iomap: Rename ATOMIC flags again

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Message-ID: <Z9If-X3Iach3o_l3@dread.disaster.area>
Date: Thu, 13 Mar 2025 10:59:53 +1100
From: Dave Chinner <david@...morbit.com>
To: Christoph Hellwig <hch@...radead.org>
Cc: John Garry <john.g.garry@...cle.com>, brauner@...nel.org,
	djwong@...nel.org, cem@...nel.org, linux-xfs@...r.kernel.org,
	linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org,
	ojaswin@...ux.ibm.com, ritesh.list@...il.com,
	martin.petersen@...cle.com
Subject: Re: [PATCH RFC v5 10/10] iomap: Rename ATOMIC flags again

On Wed, Mar 12, 2025 at 12:13:42AM -0700, Christoph Hellwig wrote:
> On Mon, Mar 10, 2025 at 06:39:46PM +0000, John Garry wrote:
> > Dave Chinner thought that names IOMAP_ATOMIC_HW and IOMAP_ATOMIC_SW were
> > not appropopiate. Specifically because IOMAP_ATOMIC_HW could actually be
> > realised with a SW-based method in the block or md/dm layers.
> > 
> > So rename to IOMAP_ATOMIC_BIO and IOMAP_ATOMIC_FS.
> 
> Looking over the entire series and the already merged iomap code:
> there should be no reason at all for having IOMAP_ATOMIC_FS.
> The only thing it does is to branch out to
> xfs_atomic_write_sw_iomap_begin from xfs_atomic_write_iomap_begin.
> 
> You can do that in a much simpler and nicer way by just having
> different iomap_ops for the bio based vs file system based atomics.

Agreed - I was going to suggest that, but got distracted by
something else and then forgot about it when I got back to writing
the email...

> I agree with dave that bio is a better term for the bio based
> atomic, but please use the IOMAP_ATOMIC_BIO name above instead
> of the IOMAP_BIO_ATOMIC actually used in the code if you change
> it.

Works for me.

> >   */
> >  static inline blk_opf_t iomap_dio_bio_opflags(struct iomap_dio *dio,
> > -		const struct iomap *iomap, bool use_fua, bool atomic_hw)
> > +		const struct iomap *iomap, bool use_fua, bool bio_atomic)
> 
> Not new here, but these two bools are pretty ugly.
> 
> I'd rather have a
> 
>     blk_opf_t extra_flags;
> 
> in the caller that gets REQ_FUA and REQ_ATOMIC assigned as needed,
> and then just clear 

Yep, that is cleaner..

-Dave.
-- 
Dave Chinner
david@...morbit.com