The quilt patch titled
Subject: mm/swapfile:__swap_duplicate: drop redundant WRITE_ONCE on swap_map for err cases
has been removed from the -mm tree. Its filename was
mm-swapfile-__swap_duplicate-drop-redundant-write_once-on-swap_map-for-err-cases.patch
This patch was dropped because it was merged into the mm-stable branch
of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
------------------------------------------------------
From: Barry Song <21cnbao@xxxxxxxxx>
Subject: mm/swapfile:__swap_duplicate: drop redundant WRITE_ONCE on swap_map for err cases
Date: Wed, 21 Feb 2024 22:10:28 +1300
From: Barry Song <v-songbaohua@xxxxxxxx>
The code is quite hard to read, we are still writing swap_map after
errors happen. Though the written value is as before,
has_cache = count & SWAP_HAS_CACHE;
count &= ~SWAP_HAS_CACHE;
[snipped]
WRITE_ONCE(p->swap_map[offset], count | has_cache);
It would be better to entirely drop the WRITE_ONCE for both
performance and readability.
[akpm@xxxxxxxxxxxxxxxxxxxx: avoid using goto]
Link: https://lkml.kernel.org/r/20240221091028.123122-1-21cnbao@xxxxxxxxx
Signed-off-by: Barry Song <v-songbaohua@xxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/swapfile.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
--- a/mm/swapfile.c~mm-swapfile-__swap_duplicate-drop-redundant-write_once-on-swap_map-for-err-cases
+++ a/mm/swapfile.c
@@ -3335,7 +3335,8 @@ static int __swap_duplicate(swp_entry_t
} else
err = -ENOENT; /* unused swap entry */
- WRITE_ONCE(p->swap_map[offset], count | has_cache);
+ if (!err)
+ WRITE_ONCE(p->swap_map[offset], count | has_cache);
unlock_out:
unlock_cluster_or_swap_info(p, ci);
_
Patches currently in -mm which might be from 21cnbao@xxxxxxxxx are
