From e26f0b939df49d17bda8d5faa4813a255734e8c8 Mon Sep 17 00:00:00 2001 From: Barry Song Date: Wed, 21 Feb 2024 22:10:28 +1300 Subject: [PATCH] mm/swapfile:__swap_duplicate: drop redundant WRITE_ONCE on swap_map for err cases 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@linux-foundation.org: avoid using goto] Link: https://lkml.kernel.org/r/20240221091028.123122-1-21cnbao@gmail.com Signed-off-by: Barry Song Signed-off-by: Andrew Morton --- mm/swapfile.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/mm/swapfile.c b/mm/swapfile.c index d1bd8d1e17bd..2b3a2d85e350 100644 --- a/mm/swapfile.c +++ b/mm/swapfile.c @@ -3335,7 +3335,8 @@ static int __swap_duplicate(swp_entry_t entry, unsigned char usage) } 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);