On Wed, Mar 22, 2017 at 11:29:25PM +0400, Dmitry Monakhov wrote:
> It is reasonable drop page cache on discard, otherwise that pages may
> be written by writeback second later, so thin provision devices will
> not be happy. This seems to be a security leak in case of secure discard
> case.
>
> Also add check for queue_discard flag on early stage.
>
> Signed-off-by: Dmitry Monakhov <dmonak...@openvz.org>
> Reviewed-by: Christoph Hellwig <h...@lst.de>
>
> ---
> block/ioctl.c | 14 ++++++++++----
> 1 file changed, 10 insertions(+), 4 deletions(-)
>
> diff --git a/block/ioctl.c b/block/ioctl.c
> index 7b88820..336610d 100644
> --- a/block/ioctl.c
> +++ b/block/ioctl.c
> @@ -202,10 +202,16 @@ static int blk_ioctl_discard(struct block_device *bdev,
> fmode_t mode,
> {
> uint64_t range[2];
> uint64_t start, len;
> + struct request_queue *q = bdev_get_queue(bdev);
> + struct address_space *mapping = bdev->bd_inode->i_mapping;
> +
>
> if (!(mode & FMODE_WRITE))
> return -EBADF;
>
> + if (!blk_queue_discard(q))
> + return -EOPNOTSUPP;
> +
> if (copy_from_user(range, (void __user *)arg, sizeof(range)))
> return -EFAULT;
>
> @@ -216,12 +222,12 @@ static int blk_ioctl_discard(struct block_device *bdev,
> fmode_t mode,
> return -EINVAL;
> if (len & 511)
> return -EINVAL;
> - start >>= 9;
> - len >>= 9;
>
> - if (start + len > (i_size_read(bdev->bd_inode) >> 9))
> + if (start + len > i_size_read(bdev->bd_inode))
> return -EINVAL;
> - return blkdev_issue_discard(bdev, start, len, GFP_KERNEL, flags);
> + truncate_inode_pages_range(mapping, start, start + len);
> + return blkdev_issue_discard(bdev, start >> 9, len >> 9,
> + GFP_KERNEL, flags);
> }
>
> static int blk_ioctl_zeroout(struct block_device *bdev, fmode_t mode,
> --
> 2.9.3
>
Hey, Jens, Dmitry didn't send this patch to linux-block so looks like
you missed it. Christoph reviewed it and Nishita sent up a blktest for
it so we should probably pull it in.
