Re: [PATCH 4.19 091/175] loop: Remove sector_t truncation checks

[Ben Hutchings <ben@decadent.org.uk>]

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On Thu, 2024-04-11 at 11:55 +0200, Greg Kroah-Hartman wrote:
> 4.19-stable review patch.  If anyone has any objections, please let me know.
> 
> ------------------
> 
> From: Martijn Coenen <maco@android.com>
> 
> [ Upstream commit 083a6a50783ef54256eec3499e6575237e0e3d53 ]
> 
> sector_t is now always u64, so we don't need to check for truncation.

This needs to be reverted for 4.19, because sector_t wasn't always u64
until 5.2.

Ben.

> Signed-off-by: Martijn Coenen <maco@android.com>
> Reviewed-by: Christoph Hellwig <hch@lst.de>
> Signed-off-by: Jens Axboe <axboe@kernel.dk>
> Signed-off-by: Genjian Zhang <zhanggenjian@kylinos.cn>
> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
> ---
>  drivers/block/loop.c |   21 +++++++--------------
>  1 file changed, 7 insertions(+), 14 deletions(-)
> 
> --- a/drivers/block/loop.c
> +++ b/drivers/block/loop.c
> @@ -225,24 +225,20 @@ static void __loop_update_dio(struct loo
>  	blk_mq_unfreeze_queue(lo->lo_queue);
>  }
>  
> -static int
> +static void
>  figure_loop_size(struct loop_device *lo, loff_t offset, loff_t sizelimit)
>  {
>  	loff_t size = get_size(offset, sizelimit, lo->lo_backing_file);
> -	sector_t x = (sector_t)size;
>  	struct block_device *bdev = lo->lo_device;
>  
> -	if (unlikely((loff_t)x != size))
> -		return -EFBIG;
>  	if (lo->lo_offset != offset)
>  		lo->lo_offset = offset;
>  	if (lo->lo_sizelimit != sizelimit)
>  		lo->lo_sizelimit = sizelimit;
> -	set_capacity(lo->lo_disk, x);
> +	set_capacity(lo->lo_disk, size);
>  	bd_set_size(bdev, (loff_t)get_capacity(bdev->bd_disk) << 9);
>  	/* let user-space know about the new size */
>  	kobject_uevent(&disk_to_dev(bdev->bd_disk)->kobj, KOBJ_CHANGE);
> -	return 0;
>  }
>  
>  static inline int
> @@ -972,10 +968,8 @@ static int loop_set_fd(struct loop_devic
>  	    !file->f_op->write_iter)
>  		lo_flags |= LO_FLAGS_READ_ONLY;
>  
> -	error = -EFBIG;
>  	size = get_loop_size(lo, file);
> -	if ((loff_t)(sector_t)size != size)
> -		goto out_unlock;
> +
>  	error = loop_prepare_queue(lo);
>  	if (error)
>  		goto out_unlock;
> @@ -1280,10 +1274,7 @@ loop_set_status(struct loop_device *lo,
>  				lo->lo_device->bd_inode->i_mapping->nrpages);
>  			goto out_unfreeze;
>  		}
> -		if (figure_loop_size(lo, info->lo_offset, info->lo_sizelimit)) {
> -			err = -EFBIG;
> -			goto out_unfreeze;
> -		}
> +		figure_loop_size(lo, info->lo_offset, info->lo_sizelimit);
>  	}
>  
>  	memcpy(lo->lo_file_name, info->lo_file_name, LO_NAME_SIZE);
> @@ -1486,7 +1477,9 @@ static int loop_set_capacity(struct loop
>  	if (unlikely(lo->lo_state != Lo_bound))
>  		return -ENXIO;
>  
> -	return figure_loop_size(lo, lo->lo_offset, lo->lo_sizelimit);
> +	figure_loop_size(lo, lo->lo_offset, lo->lo_sizelimit);
> +
> +	return 0;
>  }
>  
>  static int loop_set_dio(struct loop_device *lo, unsigned long arg)
> 
> 
> 

-- 
Ben Hutchings
Everything should be made as simple as possible, but not simpler.
                                                      - Albert Einstein


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