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>