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Date: Wed, 19 Aug 2026 09:29:02 +0200
From: Christoph Hellwig <hch@lst.de>
To: Kanchan Joshi <joshi.k@samsung.com>
Cc: brauner@kernel.org, hch@lst.de, djwong@kernel.org, dgc@kernel.org,
	jack@suse.cz, cem@kernel.org, axboe@kernel.dk, kbusch@kernel.org,
	ritesh.list@gmail.com, linux-xfs@vger.kernel.org,
	linux-fsdevel@vger.kernel.org, linux-block@vger.kernel.org,
	gost.dev@samsung.com
Subject: Re: [PATCH v4 5/6] xfs: write stream based AG placement
Message-ID: <20260819072902.GA2332@lst.de>
References: <20260717125538.508925-1-joshi.k@samsung.com> <CGME20260717125638epcas5p2fb7128170d2443be3cfe1a7687d0c5fd@epcas5p2.samsung.com> <20260717125538.508925-6-joshi.k@samsung.com>
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User-Agent: Mutt/1.5.17 (2007-11-01)

On Fri, Jul 17, 2026 at 06:25:37PM +0530, Kanchan Joshi wrote:
> If AGs are fewer than write streams, write streams are distributed into
> available AGs in round robin fashion.

I think we should just limit the number of available write streams
to the number of AG, as otherwise we'll get into a bit of a mess.

And for the case of the hardware write streams query them in mkfs
to align the AG geometry to that.

> +	uint32_t		nr_streams = xfs_inode_max_write_streams(ip);
> +	uint32_t		stream_id = ip->i_write_stream;
> +	uint32_t		nr_ags = mp->m_sb.sb_agcount;
> +	xfs_agnumber_t		set_size;
> +
> +
> +	if (!nr_streams)

Double empty line.