Received-SPF: pass (google.com: domain of linux-kernel+bounces-186395-linux.lists.archive=gmail.com@vger.kernel.org designates 147.75.48.161 as permitted sender) client-ip=147.75.48.161;
Date: Wed, 22 May 2024 07:59:35 -0700
From: Christoph Hellwig <hch@infradead.org>
To: "Darrick J. Wong" <djwong@kernel.org>
Cc: Sukrit Bhatnagar <Sukrit.Bhatnagar@sony.com>,
	"Rafael J. Wysocki" <rafael@kernel.org>,
	Pavel Machek <pavel@ucw.cz>, Christian Brauner <brauner@kernel.org>,
	Andrew Morton <akpm@linux-foundation.org>,
	linux-xfs@vger.kernel.org, linux-pm@vger.kernel.org,
	linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org,
	linux-mm@kvack.org
Subject: Re: [PATCH 2/2] mm: swap: print starting physical block offset in
 swapon
Message-ID: <Zk4IV53Q_fyx9Vx4@infradead.org>
References: <20240522074658.2420468-1-Sukrit.Bhatnagar@sony.com>
 <20240522074658.2420468-3-Sukrit.Bhatnagar@sony.com>
 <20240522145637.GV25518@frogsfrogsfrogs>
Precedence: bulk
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <20240522145637.GV25518@frogsfrogsfrogs>

On Wed, May 22, 2024 at 07:56:37AM -0700, Darrick J. Wong wrote:
> On Wed, May 22, 2024 at 04:46:58PM +0900, Sukrit Bhatnagar wrote:
> > When a swapfile is created for hibernation purposes, we always need
> > the starting physical block offset, which is usually determined using
> > userspace commands such as filefrag.
> 
> If you always need this value, then shouldn't it be exported via sysfs
> or somewhere so that you can always get to it?  The kernel ringbuffer
> can overwrite log messages, swapfiles can get disabled, etc.

Scraping a block address from anything is just broken.

Wher is the code using this?  It needs a proper kernel interface.

Same about the warning crap in patch 1.