linux-kernel - Re: [dm-devel] [PATCH stable 3/3] dm: do not forward ioctls from logical volumes to the underlying device

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Message-ID: <Pine.LNX.4.64.1201161926190.26607@hs20-bc2-1.build.redhat.com>
Date:	Mon, 16 Jan 2012 19:32:19 -0500 (EST)
From:	Mikulas Patocka <mpatocka@...hat.com>
To:	Paolo Bonzini <pbonzini@...hat.com>
cc:	linux-kernel@...r.kernel.org, dm-devel@...hat.com,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	stable@...nel.org, Alasdair G Kergon <agk@...hat.com>,
	linux-scsi@...r.kernel.org
Subject: Re: [dm-devel] [PATCH stable 3/3] dm: do not forward ioctls from
 logical volumes to the underlying device

Hi

You should put this test to a function or macro. Don't copy the same logic 
to three different places. Think what happens if someone needs to change 
it after few years --- it will be hard to find out what was copied where.

Mikulas

On Mon, 16 Jan 2012, Paolo Bonzini wrote:

> A logical volume can map to just part of underlying physical volume.
> In this case, it must be treated like a partition.
> 
> Based on a patch from Alasdair G Kergon.
> 
> [ Cherry picked from 95113a17a2a1eb06151dc698dca9bcc4a29e4fbb ]
> 
> Cc: stable@...nel.org
> Cc: Alasdair G Kergon <agk@...hat.com>
> Cc: dm-devel@...hat.com
> Cc: linux-scsi@...r.kernel.org
> Signed-off-by: Paolo Bonzini <pbonzini@...hat.com>
> Signed-off-by: Linus Torvalds <torvalds@...ux-foundation.org>
> ---
>  drivers/md/dm-flakey.c |   11 ++++++++++-
>  drivers/md/dm-linear.c |   12 +++++++++++-
>  drivers/md/dm-mpath.c  |    6 ++++++
>  3 files changed, 27 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/md/dm-flakey.c b/drivers/md/dm-flakey.c
> index f84c080..9fb18c1 100644
> --- a/drivers/md/dm-flakey.c
> +++ b/drivers/md/dm-flakey.c
> @@ -368,8 +368,17 @@ static int flakey_status(struct dm_target *ti, status_type_t type,
>  static int flakey_ioctl(struct dm_target *ti, unsigned int cmd, unsigned long arg)
>  {
>  	struct flakey_c *fc = ti->private;
> +	struct dm_dev *dev = fc->dev;
> +	int r = 0;
>  
> -	return __blkdev_driver_ioctl(fc->dev->bdev, fc->dev->mode, cmd, arg);
> +	/*
> +	 * Only pass ioctls through if the device sizes match exactly.
> +	 */
> +	if (fc->start ||
> +	    ti->len != i_size_read(dev->bdev->bd_inode) >> SECTOR_SHIFT)
> +		r = scsi_verify_blk_ioctl(NULL, cmd);
> +
> +	return r ? : __blkdev_driver_ioctl(dev->bdev, dev->mode, cmd, arg);
>  }
>  
>  static int flakey_merge(struct dm_target *ti, struct bvec_merge_data *bvm,
> diff --git a/drivers/md/dm-linear.c b/drivers/md/dm-linear.c
> index 3921e3b..9728839 100644
> --- a/drivers/md/dm-linear.c
> +++ b/drivers/md/dm-linear.c
> @@ -116,7 +116,17 @@ static int linear_ioctl(struct dm_target *ti, unsigned int cmd,
>  			unsigned long arg)
>  {
>  	struct linear_c *lc = (struct linear_c *) ti->private;
> -	return __blkdev_driver_ioctl(lc->dev->bdev, lc->dev->mode, cmd, arg);
> +	struct dm_dev *dev = lc->dev;
> +	int r = 0;
> +
> +	/*
> +	 * Only pass ioctls through if the device sizes match exactly.
> +	 */
> +	if (lc->start ||
> +	    ti->len != i_size_read(dev->bdev->bd_inode) >> SECTOR_SHIFT)
> +		r = scsi_verify_blk_ioctl(NULL, cmd);
> +
> +	return r ? : __blkdev_driver_ioctl(dev->bdev, dev->mode, cmd, arg);
>  }
>  
>  static int linear_merge(struct dm_target *ti, struct bvec_merge_data *bvm,
> diff --git a/drivers/md/dm-mpath.c b/drivers/md/dm-mpath.c
> index 5e0090e..801d92d 100644
> --- a/drivers/md/dm-mpath.c
> +++ b/drivers/md/dm-mpath.c
> @@ -1520,6 +1520,12 @@ static int multipath_ioctl(struct dm_target *ti, unsigned int cmd,
>  
>  	spin_unlock_irqrestore(&m->lock, flags);
>  
> +	/*
> +	 * Only pass ioctls through if the device sizes match exactly.
> +	 */
> +	if (!r && ti->len != i_size_read(bdev->bd_inode) >> SECTOR_SHIFT)
> +		r = scsi_verify_blk_ioctl(NULL, cmd);
> +
>  	return r ? : __blkdev_driver_ioctl(bdev, mode, cmd, arg);
>  }
>  
> -- 
> 1.7.7.1
> 
> --
> dm-devel mailing list
> dm-devel@...hat.com
> https://www.redhat.com/mailman/listinfo/dm-devel
> 
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