diff mbox series

[06/10] netfs: Remove redundant use of smp_rmb()

Message ID 20241213135013.2964079-7-dhowells@redhat.com
State New
Headers show
Series netfs, ceph, nfs, cachefiles: Miscellaneous fixes/changes | expand

Commit Message

David Howells Dec. 13, 2024, 1:50 p.m. UTC 
From: Zilin Guan <zilin@seu.edu.cn>

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@seu.edu.cn>
Signed-off-by: David Howells <dhowells@redhat.com>
cc: Akira Yokosawa <akiyks@gmail.com>
cc: Jeff Layton <jlayton@kernel.org>
cc: netfs@lists.linux.dev
cc: linux-fsdevel@vger.kernel.org
Link: https://lore.kernel.org/r/20241207021952.2978530-1-zilin@seu.edu.cn/
---
 fs/netfs/direct_write.c | 1 -
 1 file changed, 1 deletion(-)

Comments

Akira Yokosawa Dec. 16, 2024, 10:13 a.m. UTC | #1 
David Howells wrote:
> From: Zilin Guan <zilin@seu.edu.cn>
> 
> 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@seu.edu.cn>
> Signed-off-by: David Howells <dhowells@redhat.com>
> cc: Akira Yokosawa <akiyks@gmail.com>

Reviewed-by: Akira Yokosawa <akiyks@gmail.com>

> cc: Jeff Layton <jlayton@kernel.org>
> cc: netfs@lists.linux.dev
> cc: linux-fsdevel@vger.kernel.org
> Link: https://lore.kernel.org/r/20241207021952.2978530-1-zilin@seu.edu.cn/
> ---
>  fs/netfs/direct_write.c | 1 -
>  1 file changed, 1 deletion(-)
>
diff mbox series

Patch

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;