linux-kernel - Re: [PATCH v14 08/17] splice: Do splice read from a file without using ITER

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Date:   Sat, 18 Feb 2023 09:29:11 +0100
From:   Alexander Egorenkov <egorenar@...ux.ibm.com>
To:     David Howells <dhowells@...hat.com>
Cc:     dhowells@...hat.com, axboe@...nel.dk, david@...hat.com,
        hch@...radead.org, hch@....de, hdanton@...a.com, jack@...e.cz,
        jgg@...dia.com, jhubbard@...dia.com, jlayton@...nel.org,
        linux-block@...r.kernel.org, linux-fsdevel@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-mm@...ck.org,
        logang@...tatee.com, viro@...iv.linux.org.uk, willy@...radead.org,
        Marc Hartmayer <mhartmay@...ux.ibm.com>
Subject: Re: [PATCH v14 08/17] splice: Do splice read from a file without
 using ITER_PIPE

Hi David,


David Howells <dhowells@...hat.com> writes:

> Does the attached fix the problem for you?  The data being written into the
> pipe needs to be limited to the size of the file.
>
> David
>
> diff --git a/mm/filemap.c b/mm/filemap.c
> index c01bbcb9fa92..6362ac697a70 100644
> --- a/mm/filemap.c
> +++ b/mm/filemap.c
> @@ -2948,7 +2948,8 @@ ssize_t filemap_splice_read(struct file *in, loff_t *ppos,
>  			if (writably_mapped)
>  				flush_dcache_folio(folio);
>  
> -			n = splice_folio_into_pipe(pipe, folio, *ppos, len);
> +			n = min_t(loff_t, len, isize - *ppos);
> +			n = splice_folio_into_pipe(pipe, folio, *ppos, n);
>  			if (!n)
>  				goto out;
>  			len -= n;

Yes, this change fixed the problem.

Thanks
Regards
Alex