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Date: Wed, 10 Dec 2025 18:18:37 +0100
From: Christoph Hellwig <hch@lst.de>
To: Brian Foster <bfoster@redhat.com>
Cc: Christoph Hellwig <hch@lst.de>, cem@kernel.org,
	linux-xfs@vger.kernel.org
Subject: Re: [PATCH] xfs: fix XFS_ERRTAG_FORCE_ZERO_RANGE for zoned file
 system
Message-ID: <20251210171837.GA10275@lst.de>
References: <20251210090400.3642383-1-hch@lst.de> <aTmTl_khrrNz9yLY@bfoster> <20251210154016.GA3851@lst.de> <aTmqe3lDL2BkZe3b@bfoster>
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On Wed, Dec 10, 2025 at 12:14:35PM -0500, Brian Foster wrote:
> Well yeah, it would look something like this at the current site:
> 
> 	if (!is_inode_zoned() && XFS_TEST_ERROR(...) ||
> 	    ac->reserved_blocks == magic_default_res + len)
> 		xfs_zero_range(...);
> 	else
> 		xfs_free_file_space(...);
> 
> ... and the higher level zoned code would clone the XFS_TEST_ERROR() to
> create the block reservation condition to trigger it.
> 
> Alternatively perhaps you could make that check look something like:
> 
> 	if (XFS_TEST_ERROR() && (!ac || ac->res > len))
> 		...
> 	else
> 		...
> 
> ... and let the res side always bump the res in DEBUG mode, with a
> fallback on -ENOSPC or something.

That would be less invasive for sure.  But also a bit weird, as it
encodes quite a lot of detailed knowledge of the reservations here.

I could live with it, but I fear it would have a chance to break
in not very nice ways in the future.