diff mbox

[2/4] loop: set physical block size to PAGE_SIZE

Message ID 378ae3760bd37441fd60a5188eae75f39babb6aa.1503558155.git.osandov@fb.com (mailing list archive)
State New, archived
Headers show

Commit Message

Omar Sandoval Aug. 24, 2017, 7:03 a.m. UTC 
From: Omar Sandoval <osandov@fb.com>

The physical block size is "the lowest possible sector size that the
hardware can operate on without reverting to read-modify-write
operations" (from the comment on blk_queue_physical_block_size()). Since
loop does buffered I/O on the backing file by default, the RMW unit is a
page. This isn't the case for direct I/O mode, but let's keep it simple.

Signed-off-by: Omar Sandoval <osandov@fb.com>
---
 drivers/block/loop.c | 2 ++
 1 file changed, 2 insertions(+)

Comments

Hannes Reinecke Aug. 24, 2017, 12:23 p.m. UTC | #1 
On 08/24/2017 09:03 AM, Omar Sandoval wrote:
> From: Omar Sandoval <osandov@fb.com>
> 
> The physical block size is "the lowest possible sector size that the
> hardware can operate on without reverting to read-modify-write
> operations" (from the comment on blk_queue_physical_block_size()). Since
> loop does buffered I/O on the backing file by default, the RMW unit is a
> page. This isn't the case for direct I/O mode, but let's keep it simple.
> 
> Signed-off-by: Omar Sandoval <osandov@fb.com>
> ---
>  drivers/block/loop.c | 2 ++
>  1 file changed, 2 insertions(+)
> 
> diff --git a/drivers/block/loop.c b/drivers/block/loop.c
> index 54e091887199..1a5b4ecf54ec 100644
> --- a/drivers/block/loop.c
> +++ b/drivers/block/loop.c
> @@ -1764,6 +1764,8 @@ static int loop_add(struct loop_device **l, int i)
>  	}
>  	lo->lo_queue->queuedata = lo;
>  
> +	blk_queue_physical_block_size(lo->lo_queue, PAGE_SIZE);
> +
>  	/*
>  	 * It doesn't make sense to enable merge because the I/O
>  	 * submitted to backing file is handled page by page.
> 
Let's see it this one goes through ...

Reviewed-by: Hannes Reinecke <hare@suse.com>

Cheers,

Hannes
diff mbox

Patch

diff --git a/drivers/block/loop.c b/drivers/block/loop.c
index 54e091887199..1a5b4ecf54ec 100644
--- a/drivers/block/loop.c
+++ b/drivers/block/loop.c
@@ -1764,6 +1764,8 @@  static int loop_add(struct loop_device **l, int i)
 	}
 	lo->lo_queue->queuedata = lo;
 
+	blk_queue_physical_block_size(lo->lo_queue, PAGE_SIZE);
+
 	/*
 	 * It doesn't make sense to enable merge because the I/O
 	 * submitted to backing file is handled page by page.