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References: <ZEFmS9h81Wwlv9+/@redhat.com> <20230420172807.323150-1-sarthakkukreti@chromium.org>
In-Reply-To: <20230420172807.323150-1-sarthakkukreti@chromium.org>
From:   Sarthak Kukreti <sarthakkukreti@chromium.org>
Date:   Thu, 20 Apr 2023 11:17:15 -0700
Message-ID: <CAG9=OMO7LtYRMurR4t4P5Tcb00-ob21eg4jm0aUXry2mcgOMfw@mail.gmail.com>
Subject: Re: [PATCH v5-fix 1/5] block: Don't invalidate pagecache for invalid
 falloc modes
To:     dm-devel@redhat.com, linux-block@vger.kernel.org,
        linux-ext4@vger.kernel.org, linux-kernel@vger.kernel.org,
        linux-fsdevel@vger.kernel.org
Cc:     Jens Axboe <axboe@kernel.dk>,
        "Michael S. Tsirkin" <mst@redhat.com>,
        Jason Wang <jasowang@redhat.com>,
        Stefan Hajnoczi <stefanha@redhat.com>,
        Alasdair Kergon <agk@redhat.com>,
        Mike Snitzer <snitzer@kernel.org>,
        Christoph Hellwig <hch@infradead.org>,
        Brian Foster <bfoster@redhat.com>,
        "Theodore Ts'o" <tytso@mit.edu>,
        Andreas Dilger <adilger.kernel@dilger.ca>,
        Bart Van Assche <bvanassche@google.com>,
        Daniil Lunev <dlunev@google.com>,
        "Darrick J. Wong" <djwong@kernel.org>, stable@vger.kernel.org
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Precedence: bulk

This patch had a slight typo; fixed in the most recent patch.

- Sarthak

On Thu, Apr 20, 2023 at 10:28=E2=80=AFAM Sarthak Kukreti
<sarthakkukreti@chromium.org> wrote:
>
> Only call truncate_bdev_range() if the fallocate mode is
> supported. This fixes a bug where data in the pagecache
> could be invalidated if the fallocate() was called on the
> block device with an invalid mode.
>
> Fixes: 25f4c41415e5 ("block: implement (some of) fallocate for block devi=
ces")
> Cc: stable@vger.kernel.org
> Reported-by: Darrick J. Wong <djwong@kernel.org>
> Signed-off-by: Sarthak Kukreti <sarthakkukreti@chromium.org>
> ---
>  block/fops.c | 21 ++++++++++++++++-----
>  1 file changed, 16 insertions(+), 5 deletions(-)
>
> diff --git a/block/fops.c b/block/fops.c
> index d2e6be4e3d1c..20b1eddcbe25 100644
> --- a/block/fops.c
> +++ b/block/fops.c
> @@ -648,24 +648,35 @@ static long blkdev_fallocate(struct file *file, int=
 mode, loff_t start,
>
>         filemap_invalidate_lock(inode->i_mapping);
>
> -       /* Invalidate the page cache, including dirty pages. */
> -       error =3D truncate_bdev_range(bdev, file->f_mode, start, end);
> -       if (error)
> -               goto fail;
> -
> +       /*
> +        * Invalidate the page cache, including dirty pages, for valid
> +        * de-allocate mode calls to fallocate().
> +        */
>         switch (mode) {
>         case FALLOC_FL_ZERO_RANGE:
>         case FALLOC_FL_ZERO_RANGE | FALLOC_FL_KEEP_SIZE:
> +               error =3D truncate_bdev_range(bdev, file->f_mode, start, =
end);
> +               if (error)
> +                       goto fail;
> +
>                 error =3D blkdev_issue_zeroout(bdev, start >> SECTOR_SHIF=
T,
>                                              len >> SECTOR_SHIFT, GFP_KER=
NEL,
>                                              BLKDEV_ZERO_NOUNMAP);
>                 break;
>         case FALLOC_FL_PUNCH_HOLE | FALLOC_FL_KEEP_SIZE:
> +               error =3D truncate_bdev_range(bdev, file->f_mode, start, =
end);
> +               if (error)
> +                       goto fail;
> +
>                 error =3D blkdev_issue_zeroout(bdev, start >> SECTOR_SHIF=
T,
>                                              len >> SECTOR_SHIFT, GFP_KER=
NEL,
>                                              BLKDEV_ZERO_NOFALLBACK);
>                 break;
>         case FALLOC_FL_PUNCH_HOLE | FALLOC_FL_KEEP_SIZE | FALLOC_FL_NO_HI=
DE_STALE:
> +               error =3D truncate_bdev_range(bdev, file->f_mode, start, =
end);
> +               if (!error)
> +                       goto fail;
> +
>                 error =3D blkdev_issue_discard(bdev, start >> SECTOR_SHIF=
T,
>                                              len >> SECTOR_SHIFT, GFP_KER=
NEL);
>                 break;
> --
> 2.40.0.396.gfff15efe05-goog
>