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@seu.edu.cn>
Signed-off-by: David Howells <dhowells@redhat.com>
Link: https://lore.kernel.org/r/20241207021952.2978530-1-zilin@seu.edu.cn/
Link: https://lore.kernel.org/r/20241213135013.2964079-7-dhowells@redhat.com
Reviewed-by: Akira Yokosawa <akiyks@gmail.com>
cc: Akira Yokosawa <akiyks@gmail.com>
cc: Jeff Layton <jlayton@kernel.org>
cc: netfs@lists.linux.dev
cc: linux-fsdevel@vger.kernel.org
Signed-off-by: Christian Brauner <brauner@kernel.org>

diff --git a/fs/netfs/direct_write.c b/fs/netfs/direct_write.c
index 88f2adfab75e926969a8fae3c4bf65051644f0ed..173e8b5e6a93038570c092b7ec5947177a8b8d1b 100644 (file)
--- 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;