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Date: Mon, 2 Jun 2025 16:24:05 +0200
From: Christoph Hellwig <hch@lst.de>
To: Kundan Kumar <kundan.kumar@samsung.com>
Cc: jaegeuk@kernel.org, chao@kernel.org, viro@zeniv.linux.org.uk,
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	Anuj Gupta <anuj20.g@samsung.com>
Subject: Re: [PATCH 04/13] writeback: affine inode to a writeback ctx
 within a bdi
Message-ID: <20250602142405.GA22563@lst.de>
References: <20250529111504.89912-1-kundan.kumar@samsung.com> <CGME20250529113232epcas5p4e6f3b2f03d3a5f8fcaace3ddd03298d0@epcas5p4.samsung.com> <20250529111504.89912-5-kundan.kumar@samsung.com>
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User-Agent: Mutt/1.5.17 (2007-11-01)

On Thu, May 29, 2025 at 04:44:55PM +0530, Kundan Kumar wrote:
> @@ -157,7 +157,7 @@ fetch_bdi_writeback_ctx(struct inode *inode)
>  {
>  	struct backing_dev_info *bdi = inode_to_bdi(inode);
>  
> -	return bdi->wb_ctx_arr[0];
> +	return bdi->wb_ctx_arr[inode->i_ino % bdi->nr_wb_ctx];

Most modern file systems use 64-bit inode numbers, while i_ino sadly
still is only an ino_t that can be 32-bits wide.  So we'll either need
an ugly fs hook here, or maybe convince Linus that it finally is time
for a 64-bit i_ino (which would also clean up a lot of mess in the
file systems and this constant source of confusion).