linux-kernel - Re: [PATCH 06/12] mm/truncate: add folio_unmap

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Message-ID: <Z1gkNiD2wJbAdOfr@infradead.org>
Date: Tue, 10 Dec 2024 03:21:26 -0800
From: Christoph Hellwig <hch@...radead.org>
To: Jens Axboe <axboe@...nel.dk>
Cc: linux-mm@...ck.org, linux-fsdevel@...r.kernel.org, hannes@...xchg.org,
	clm@...a.com, linux-kernel@...r.kernel.org, willy@...radead.org,
	kirill@...temov.name, bfoster@...hat.com
Subject: Re: [PATCH 06/12] mm/truncate: add folio_unmap_invalidate() helper

On Tue, Dec 03, 2024 at 08:31:42AM -0700, Jens Axboe wrote:
> Add a folio_unmap_invalidate() helper, which unmaps and invalidates a
> given folio. The caller must already have locked the folio. Use this
> new helper in invalidate_inode_pages2_range(), rather than duplicate
> the code there.

This new helper ends up the only caller of invalidate_complete_folio2,
so you might as well merge the two instead of having yet another
invalidate/unmap helper, which are getting impossible to track of.

Also it is only used in mm/, so add the prototype to mm/internal.h
insead of the public pagemap.h.  And a little comment what the function
does would be pretty useful as well.

> In preparation for using this elsewhere as well, have it take a gfp_t
> mask rather than assume GFP_KERNEL is the right choice. This bubbles
> back to invalidate_complete_folio2() as well.

Looking at the callers the gfp_t looks a bit odd to me, as it is
either GFP_KERNEL or 0 which is a valid but rather unusuable gfp_t
value, but I guess this comes form filemap_release_folio which
works similarly.