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From:   =?UTF-8?Q?Andreas_Gr=C3=BCnbacher?= <andreas.gruenbacher@gmail.com>
Date:   Mon, 17 Aug 2020 21:55:55 +0200
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Subject: Re: [PATCH 5.7 188/393] iomap: Make sure iomap_end is called after iomap_begin
To:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc:     Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        stable@vger.kernel.org, Andreas Gruenbacher <agruenba@redhat.com>,
        Christoph Hellwig <hch@lst.de>,
        "Darrick J. Wong" <darrick.wong@oracle.com>,
        Sasha Levin <sashal@kernel.org>
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Greg,

Am Mo., 17. Aug. 2020 um 21:01 Uhr schrieb Greg Kroah-Hartman
<gregkh@linuxfoundation.org>:
> From: Andreas Gruenbacher <agruenba@redhat.com>
>
> [ Upstream commit 856473cd5d17dbbf3055710857c67a4af6d9fcc0 ]
>
> Make sure iomap_end is always called when iomap_begin succeeds.
>
> Without this fix, iomap_end won't be called when a filesystem's
> iomap_begin operation returns an invalid mapping, bypassing any
> unlocking done in iomap_end.  With this fix, the unlocking will still
> happen.
>
> This bug was found by Bob Peterson during code review.  It's unlikely
> that such iomap_begin bugs will survive to affect users, so backporting
> this fix seems unnecessary.

this doesn't need to be backported.

Thanks,
Andreas


> Fixes: ae259a9c8593 ("fs: introduce iomap infrastructure")
> Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>
> Reviewed-by: Christoph Hellwig <hch@lst.de>
> Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>
> Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
> Signed-off-by: Sasha Levin <sashal@kernel.org>
> ---
>  fs/iomap/apply.c | 13 +++++++++----
>  1 file changed, 9 insertions(+), 4 deletions(-)
>
> diff --git a/fs/iomap/apply.c b/fs/iomap/apply.c
> index 76925b40b5fd2..26ab6563181fc 100644
> --- a/fs/iomap/apply.c
> +++ b/fs/iomap/apply.c
> @@ -46,10 +46,14 @@ iomap_apply(struct inode *inode, loff_t pos, loff_t length, unsigned flags,
>         ret = ops->iomap_begin(inode, pos, length, flags, &iomap, &srcmap);
>         if (ret)
>                 return ret;
> -       if (WARN_ON(iomap.offset > pos))
> -               return -EIO;
> -       if (WARN_ON(iomap.length == 0))
> -               return -EIO;
> +       if (WARN_ON(iomap.offset > pos)) {
> +               written = -EIO;
> +               goto out;
> +       }
> +       if (WARN_ON(iomap.length == 0)) {
> +               written = -EIO;
> +               goto out;
> +       }
>
>         trace_iomap_apply_dstmap(inode, &iomap);
>         if (srcmap.type != IOMAP_HOLE)
> @@ -80,6 +84,7 @@ iomap_apply(struct inode *inode, loff_t pos, loff_t length, unsigned flags,
>         written = actor(inode, pos, length, data, &iomap,
>                         srcmap.type != IOMAP_HOLE ? &srcmap : &iomap);
>
> +out:
>         /*
>          * Now the data has been copied, commit the range we've copied.  This
>          * should not fail unless the filesystem has had a fatal error.
> --
> 2.25.1
>
>
>