From 6c6b6f28b3335fd85ec833ee0005d9c9dca6c003 Mon Sep 17 00:00:00 2001 From: Omar Sandoval Date: Thu, 24 Aug 2017 00:03:42 -0700 Subject: [PATCH] loop: set physical block size to PAGE_SIZE 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. Reviewed-by: Ming Lei Reviewed-by: Hannes Reinecke Signed-off-by: Omar Sandoval Signed-off-by: Jens Axboe --- drivers/block/loop.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/drivers/block/loop.c b/drivers/block/loop.c index efad2d46a018..e3f190016d4f 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. -- 2.20.1