[PATCH 4.14 48/74] block: unalign call_single_data in struct request

From: Greg Kroah-Hartman
Date: Wed Dec 27 2017 - 11:52:25 EST


4.14-stable review patch. If anyone has any objections, please let me know.

------------------

From: Jens Axboe <axboe@xxxxxxxxx>

commit 4ccafe032005e9b96acbef2e389a4de5b1254add upstream.

A previous change blindly added massive alignment to the
call_single_data structure in struct request. This ballooned it in size
from 296 to 320 bytes on my setup, for no valid reason at all.

Use the unaligned struct __call_single_data variant instead.

Fixes: 966a967116e69 ("smp: Avoid using two cache lines for struct call_single_data")
Signed-off-by: Jens Axboe <axboe@xxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
include/linux/blkdev.h | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

--- a/include/linux/blkdev.h
+++ b/include/linux/blkdev.h
@@ -135,7 +135,7 @@ typedef __u32 __bitwise req_flags_t;
struct request {
struct list_head queuelist;
union {
- call_single_data_t csd;
+ struct __call_single_data csd;
u64 fifo_time;
};