linux-kernel - Re: [PATCH v5-fix 1/5] block: Don't invalidate pagecache for invalid falloc modes

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

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

- Sarthak

On Thu, Apr 20, 2023 at 10:28 AM Sarthak Kukreti
<sarthakkukreti@...omium.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 devices")
> Cc: stable@...r.kernel.org
> Reported-by: Darrick J. Wong <djwong@...nel.org>
> Signed-off-by: Sarthak Kukreti <sarthakkukreti@...omium.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 = 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 = truncate_bdev_range(bdev, file->f_mode, start, end);
> +               if (error)
> +                       goto fail;
> +
>                 error = blkdev_issue_zeroout(bdev, start >> SECTOR_SHIFT,
>                                              len >> SECTOR_SHIFT, GFP_KERNEL,
>                                              BLKDEV_ZERO_NOUNMAP);
>                 break;
>         case FALLOC_FL_PUNCH_HOLE | FALLOC_FL_KEEP_SIZE:
> +               error = truncate_bdev_range(bdev, file->f_mode, start, end);
> +               if (error)
> +                       goto fail;
> +
>                 error = blkdev_issue_zeroout(bdev, start >> SECTOR_SHIFT,
>                                              len >> SECTOR_SHIFT, GFP_KERNEL,
>                                              BLKDEV_ZERO_NOFALLBACK);
>                 break;
>         case FALLOC_FL_PUNCH_HOLE | FALLOC_FL_KEEP_SIZE | FALLOC_FL_NO_HIDE_STALE:
> +               error = truncate_bdev_range(bdev, file->f_mode, start, end);
> +               if (!error)
> +                       goto fail;
> +
>                 error = blkdev_issue_discard(bdev, start >> SECTOR_SHIFT,
>                                              len >> SECTOR_SHIFT, GFP_KERNEL);
>                 break;
> --
> 2.40.0.396.gfff15efe05-goog
>