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Date: Mon, 17 Feb 2025 10:12:59 +0100
From: Christoph Hellwig <hch@lst.de>
To: Ming Lei <ming.lei@redhat.com>
Cc: Christoph Hellwig <hch@lst.de>, Jens Axboe <axboe@kernel.dk>,
	linux-block@vger.kernel.org, Nilay Shroff <nilay@linux.ibm.com>,
	Shinichiro Kawasaki <shinichiro.kawasaki@wdc.com>
Subject: Re: [PATCH 1/7] block: remove hctx->debugfs_dir
Message-ID: <20250217091259.GA28866@lst.de>
References: <20250209122035.1327325-1-ming.lei@redhat.com> <20250209122035.1327325-2-ming.lei@redhat.com> <20250213064146.GA20494@lst.de> <Z66lWy5Yf4T_4mlg@fedora>
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User-Agent: Mutt/1.5.17 (2007-11-01)

On Fri, Feb 14, 2025 at 10:07:23AM +0800, Ming Lei wrote:
> On Thu, Feb 13, 2025 at 07:41:46AM +0100, Christoph Hellwig wrote:
> > On Sun, Feb 09, 2025 at 08:20:25PM +0800, Ming Lei wrote:
> > > For each hctx, its debugfs path is fixed, which can be queried from
> > > its parent dentry and hctx queue num, so it isn't necessary to cache
> > > it in hctx structure because it isn't used in fast path.
> > 
> > It's not needed, but it's also kinda convenient.  What is the argument
> > that speaks for recalculating the path?
> 
> q->debugfs_lock will be not necessary if these cached entries are removed,
> please see the last patch.

Please document the reasoning (and tradeoff if there are any) in the
commit log.  No one will see your cover letter when bisecting a bug
down to this commit in the future.