linux-ext4 - Re: [PATCH 1/1] iomap: allow NULL swap info bdev when activating swapfile

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Message-ID: <20251107180507.GW196362@frogsfrogsfrogs>
Date: Fri, 7 Nov 2025 10:05:07 -0800
From: "Darrick J. Wong" <djwong@...nel.org>
To: Jan Engelhardt <ej@...i.de>
Cc: Christoph Hellwig <hch@....de>, miklos@...redi.hu, brauner@...nel.org,
	linux-ext4@...r.kernel.org, linux-fsdevel@...r.kernel.org
Subject: Re: [PATCH 1/1] iomap: allow NULL swap info bdev when activating
 swapfile

On Fri, Nov 07, 2025 at 10:23:23AM +0100, Jan Engelhardt wrote:
> 
> On Thursday 2025-10-30 07:00, Christoph Hellwig wrote:
> >
> >> "Already does" in the sense that fuse already supports swapfiles(!) if
> >> your filesystem implements FUSE_BMAP and attaches via fuseblk (aka
> >> ntfs3g).
> >
> >Yikes.  This is just such an amazingly bad idea.
> 
> And even if a fuse does not support swapfiles, "problems in computer
> science can be solved by another level of indirection". Not that they
> should - but this sequence succeeds already:
> 
> mount -t sshfs root@...alhost:/ /mnt
> losetup /dev/loop7 /mnt/swapfile
> swapon /dev/loop7

Amazing.

--D