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Date:   Thu, 19 Jan 2023 10:33:26 -0800
From:   Christoph Hellwig <hch@infradead.org>
To:     Dave Chinner <david@fromorbit.com>
Cc:     linux-xfs@vger.kernel.org
Subject: Re: [PATCH] xfs: don't use BMBT btree split workers for IO completion
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On Thu, Jan 19, 2023 at 12:03:34PM +1100, Dave Chinner wrote:
> The other place we can be called for a BMBT split without a
> preceeding allocation is __xfs_bunmapi() when punching out the
> center of an existing extent. We don't remove extents in the IO
> path, so these operations don't tend to be called with a lot of
> stack consumed. Hence we don't really need to ship the split off to
> a worker thread in these cases, either.

So I agree with the fix.  But the t_firstblock seems a bit opaque.
We do have a lot of comments, which is good but it still feels
a little fragile to me.  Is there a good reason we can't do an
explicit flag to document the intent better?