linux-kernel - [PATCH] mm/filemap.c: minor optimization in write

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Date:   Sun, 18 Nov 2018 20:02:18 +0800
From:   Yafang Shao <laoar.shao@...il.com>
To:     willy@...radead.org, akpm@...ux-foundation.org,
        darrick.wong@...cle.com
Cc:     linux-mm@...ck.org, linux-kernel@...r.kernel.org,
        Yafang Shao <laoar.shao@...il.com>
Subject: [PATCH] mm/filemap.c: minor optimization in write_iter file operation

This little adjustment on bitwise operation could make the code a little
faster.
As write_iter is used in lots of critical path, so this code change is
useful for performance.

Signed-off-by: Yafang Shao <laoar.shao@...il.com>
---
 mm/filemap.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/mm/filemap.c b/mm/filemap.c
index 81adec8..a65056ea 100644
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -2881,7 +2881,8 @@ inline ssize_t generic_write_checks(struct kiocb *iocb, struct iov_iter *from)
 	if (iocb->ki_flags & IOCB_APPEND)
 		iocb->ki_pos = i_size_read(inode);
 
-	if ((iocb->ki_flags & IOCB_NOWAIT) && !(iocb->ki_flags & IOCB_DIRECT))
+	if ((iocb->ki_flags & (IOCB_NOWAIT | IOCB_DIRECT)) ==
+	    IOCB_NOWAIT)
 		return -EINVAL;
 
 	count = iov_iter_count(from);
-- 
1.8.3.1