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Date:   Tue, 27 Jun 2023 18:48:20 +0100
From:   Matthew Wilcox <willy@infradead.org>
To:     Sumitra Sharma <sumitraartsy@gmail.com>
Cc:     Hans de Goede <hdegoede@redhat.com>, linux-fsdevel@vger.kernel.org,
        linux-kernel@vger.kernel.org, Ira Weiny <ira.weiny@intel.com>,
        Fabio <fmdefrancesco@gmail.com>, Deepak R Varma <drv@mailo.com>
Subject: Re: [PATCH] fs/vboxsf: Replace kmap() with kmap_local_{page, folio}()
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References: <20230627135115.GA452832@sumitra.com>
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On Tue, Jun 27, 2023 at 06:51:15AM -0700, Sumitra Sharma wrote:
> +++ b/fs/vboxsf/file.c
> @@ -234,7 +234,7 @@ static int vboxsf_read_folio(struct file *file, struct folio *folio)
>  	u8 *buf;
>  	int err;
>  
> -	buf = kmap(page);
> +	buf = kmap_local_folio(folio, off);

Did you test this?  'off' is the offset in the _file_.  Whereas
kmap_local_folio() takes the offset within the _folio_.  They have
different types (loff_t vs size_t) to warn you that they're different
things.