[PATCH 06/26] loop: also use the default block size from an underlying block device

[Damien Le Moal]

On 6/11/24 2:19 PM, Christoph Hellwig wrote:
> Fix the code in loop_reconfigure_limits to pick a default block size for
> O_DIRECT file descriptors to also work when the loop device sits on top
> of a block device and not just on a regular file on a block device based
> file system.
> 
> Signed-off-by: Christoph Hellwig <hch at lst.de>
> ---
>  drivers/block/loop.c | 8 +++++++-
>  1 file changed, 7 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/block/loop.c b/drivers/block/loop.c
> index 4f6d8514d19bd6..d7cf6bbbfb1b86 100644
> --- a/drivers/block/loop.c
> +++ b/drivers/block/loop.c
> @@ -988,10 +988,16 @@ static int loop_reconfigure_limits(struct loop_device *lo, unsigned short bsize)
>  {
>  	struct file *file = lo->lo_backing_file;
>  	struct inode *inode = file->f_mapping->host;
> +	struct block_device *backing_bdev = NULL;
>  	struct queue_limits lim;
>  
> +	if (S_ISBLK(inode->i_mode))
> +		backing_bdev = I_BDEV(inode);
> +	else if (inode->i_sb->s_bdev)
> +		backing_bdev = inode->i_sb->s_bdev;
> +

Why not move this hunk inside the below "if" ? (backing_dev declaration can go
there too).

>  	if (!bsize)
> -		bsize = loop_default_blocksize(lo, inode->i_sb->s_bdev);
> +		bsize = loop_default_blocksize(lo, backing_bdev);
>  
>  	lim = queue_limits_start_update(lo->lo_queue);
>  	lim.logical_block_size = bsize;

-- 
Damien Le Moal
Western Digital Research