linux-kernel - Re: [RFC PATCH 1/1] block/ioctl: Add an ioctl to enable large folios for block buffered IO path

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Message-ID: <Z0gDCxiv2VLQkCR_@infradead.org>
Date: Wed, 27 Nov 2024 21:43:39 -0800
From: Christoph Hellwig <hch@...radead.org>
To: Bharata B Rao <bharata@....com>
Cc: Christoph Hellwig <hch@...radead.org>, linux-block@...r.kernel.org,
	linux-kernel@...r.kernel.org, linux-fsdevel@...r.kernel.org,
	linux-mm@...ck.org, nikunj@....com, willy@...radead.org,
	vbabka@...e.cz, david@...hat.com, akpm@...ux-foundation.org,
	yuzhao@...gle.com, mjguzik@...il.com, axboe@...nel.dk,
	viro@...iv.linux.org.uk, brauner@...nel.org, jack@...e.cz,
	joshdon@...gle.com, clm@...a.com
Subject: Re: [RFC PATCH 1/1] block/ioctl: Add an ioctl to enable large folios
 for block buffered IO path

On Wed, Nov 27, 2024 at 04:07:02PM +0530, Bharata B Rao wrote:
> I believe you are referring to the patchset that enables bs > ps for block
> devices - https://lore.kernel.org/linux-fsdevel/20241113094727.1497722-1-mcgrof@kernel.org/

I actually thought of:

https://www.spinics.net/lists/linux-ext4/msg98151.html

but yes, the one you pointed to is more relevant.

> In fact I was trying to see if it is possible to advertise large folio
> support in bdev mapping only for those block devices which don't have FS
> mounted on them. But apparently it was not so straight forward and my
> initial attempt at this resulted in FS corruption. Hence I resorted to the
> current ioctl approach as a way to showcase the problem and the potential
> benefit.

Well, if you use the ioctl and then later mount a file system, you'll
still see the same corruption.