linux-kernel - [PATCH] fs/netfs: Remove redundant use of smp

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Message-Id: <20241207021952.2978530-1-zilin@seu.edu.cn>
Date: Sat,  7 Dec 2024 02:19:52 +0000
From: Zilin Guan <zilin@....edu.cn>
To: dhowells@...hat.com
Cc: jlayton@...nel.org,
	linux-fsdevel@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	netfs@...ts.linux.dev,
	jianhao.xu@....edu.cn,
	zilin@....edu.cn
Subject: [PATCH] fs/netfs: Remove redundant use of smp_rmb()

The function netfs_unbuffered_write_iter_locked() in
fs/netfs/direct_write.c contains an unnecessary smp_rmb() call after
wait_on_bit(). Since wait_on_bit() already incorporates a memory barrier
that ensures the flag update is visible before the function returns, the
smp_rmb() provides no additional benefit and incurs unnecessary overhead.

This patch removes the redundant barrier to simplify and optimize the code.

Signed-off-by: Zilin Guan <zilin@....edu.cn>
---
 fs/netfs/direct_write.c | 1 -
 1 file changed, 1 deletion(-)

diff --git a/fs/netfs/direct_write.c b/fs/netfs/direct_write.c
index 88f2adfab75e..173e8b5e6a93 100644
--- a/fs/netfs/direct_write.c
+++ b/fs/netfs/direct_write.c
@@ -104,7 +104,6 @@ ssize_t netfs_unbuffered_write_iter_locked(struct kiocb *iocb, struct iov_iter *
 		trace_netfs_rreq(wreq, netfs_rreq_trace_wait_ip);
 		wait_on_bit(&wreq->flags, NETFS_RREQ_IN_PROGRESS,
 			    TASK_UNINTERRUPTIBLE);
-		smp_rmb(); /* Read error/transferred after RIP flag */
 		ret = wreq->error;
 		if (ret == 0) {
 			ret = wreq->transferred;
-- 
2.34.1