From: Caleb Sander Mateos <csander@purestorage.com>
Date: Fri, 20 Jun 2025 15:10:08 +0000 (-0600)
Subject: ublk: cache-align struct ublk_io
X-Git-Tag: v6.17-rc1~205^2~55
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=857f431824aacb22bd051c0f4c44c708659028b1;p=thirdparty%2Flinux.git

ublk: cache-align struct ublk_io

struct ublk_io is already 56 bytes on 64-bit architectures, so round it
up to a full cache line (typically 64 bytes). This ensures a single
ublk_io doesn't span multiple cache lines and prevents false sharing if
consecutive ublk_io's are accessed by different daemon tasks.

Signed-off-by: Caleb Sander Mateos <csander@purestorage.com>
Reviewed-by: Ming Lei <ming.lei@redhat.com>
Link: https://lore.kernel.org/r/20250620151008.3976463-15-csander@purestorage.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
---

diff --git a/drivers/block/ublk_drv.c b/drivers/block/ublk_drv.c
index eec3abb78ce5c..e52c2d1cb8383 100644
--- a/drivers/block/ublk_drv.c
+++ b/drivers/block/ublk_drv.c
@@ -188,7 +188,7 @@ struct ublk_io {
 	/* auto-registered buffer, valid if UBLK_IO_FLAG_AUTO_BUF_REG is set */
 	u16 buf_index;
 	void *buf_ctx_handle;
-};
+} ____cacheline_aligned_in_smp;
 
 struct ublk_queue {
 	int q_id;