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Date:   Mon, 4 Jul 2022 05:00:14 -0700
From:   Christoph Hellwig <hch@infradead.org>
To:     fdmanana@kernel.org
Cc:     linux-btrfs@vger.kernel.org
Subject: Re: [PATCH 2/3] btrfs: don't fallback to buffered IO for NOWAIT
 direct IO writes
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References: <cover.1656934419.git.fdmanana@suse.com>
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>  buffered:
> +	/*
> +	 * If we are in a NOWAIT context, then return -EAGAIN to signal the caller
> +	 * it must retry the operation in a context where blocking is acceptable,
> +	 * since we currently don't have NOWAIT semantics support for buffered IO

.. more overly long comments here.

> +	 * and may block there for many reasons (reserving space for example).
> +	 */
> +	if (iocb->ki_flags & IOCB_NOWAIT) {
> +		err = -EAGAIN;
> +		goto out;
> +	}

but more importantly, shouldn't this be above the buffered label? The
only places that jumps to it is the alignment check, and if the
alignment is incorrect now, it won't get any better in a workqueue
context.