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Date: Mon, 20 Oct 2025 16:57:07 +0200
From: Christoph Hellwig <hch@lst.de>
To: Keith Busch <kbusch@kernel.org>
Cc: Christoph Hellwig <hch@lst.de>, Keith Busch <kbusch@meta.com>,
	dsterba@suse.com, cem@kernel.org, linux-btrfs@vger.kernel.org,
	linux-xfs@vger.kernel.org, Chris Mason <clm@fb.com>
Subject: Re: [PATCH 1/2] xfs: handle bio split errors during gc
Message-ID: <20251020145707.GA31743@lst.de>
References: <20251020144356.693288-1-kbusch@meta.com> <20251020144522.GB30487@lst.de> <aPZNNkSOYr88-8VF@kbusch-mbp>
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On Mon, Oct 20, 2025 at 08:54:46AM -0600, Keith Busch wrote:
> > Ugg, how?  If that actually happens we're toast, so we should find a
> > way to ensure it does not happen.
> 
> You'd have to attempt sending an invalid bvec, like something that can't
> DMA map because you have a byte aligned offset, or the total size is
> smaller than the block device's.
> 
> Not that you're doing anything like that here. This condition should
> never occur in this path because the bio vectors are all nicely aligned.
> It's just for completeness to ensure it doesn't go uncaught for every
> bio split caller.

So this is just from code inspection and you did not actually hit
such a case?

I'll see if I can add some sanity checking for the buffer and
preferably handle this outside the I/O path where error handling
for this doesn't really make sense.