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Date: Thu, 25 Jun 2026 23:13:18 -0700
From: Christoph Hellwig <hch@infradead.org>
To: "Matthew Wilcox (Oracle)" <willy@infradead.org>
Cc: Christian Brauner <brauner@kernel.org>,
	"Darrick J. Wong" <djwong@kernel.org>, Jens Axboe <axboe@kernel.dk>,
	Namjae Jeon <linkinjeon@kernel.org>,
	Sungjong Seo <sj1557.seo@samsung.com>,
	Yuezhang Mo <yuezhang.mo@sony.com>,
	Miklos Szeredi <miklos@szeredi.hu>,
	Andreas Gruenbacher <agruenba@redhat.com>,
	Hyunchul Lee <hyc.lee@gmail.com>,
	Konstantin Komarov <almaz.alexandrovich@paragon-software.com>,
	Carlos Maiolino <cem@kernel.org>,
	Damien Le Moal <dlemoal@kernel.org>,
	Naohiro Aota <naohiro.aota@wdc.com>,
	Johannes Thumshirn <jth@kernel.org>, linux-xfs@vger.kernel.org,
	linux-fsdevel@vger.kernel.org, linux-block@vger.kernel.org,
	fuse-devel@lists.linux.dev, gfs2@lists.linux.dev,
	ntfs3@lists.linux.dev
Subject: Re: [PATCH] iomap: Remove FGP_NOFS from iomap_get_folio()
Message-ID: <aj4YfvFKTMl-b_PZ@infradead.org>
References: <20260624174228.2015893-1-willy@infradead.org>
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On Wed, Jun 24, 2026 at 06:42:26PM +0100, Matthew Wilcox (Oracle) wrote:
> FGP_NOFS is legacy; filesystems should be using memalloc_nofs_save/restore
> instead.  We have it here in iomap because it was buried in
> grab_cache_page_write_begin() and we didn't want to change this behaviour
> as part of the folio transition.
> 
> I have tested this with XFS and see no issues.  Other filesystems (cc'd)
> may need to make adjustments.  Please test with lockdep enabled.

I think the most interesting one to test here would be gfs2 as it has
rather alaborate locking in the write path.