vfs: add rcu argument to ->get_acl() callback

mainline inclusion
from mainline-v5.15-rc1
commit 0cad6246
category: perf
bugzilla: https://gitee.com/openeuler/kernel/issues/I6ZCW0
CVE: NA

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=0cad6246621b5887d5b33fea84219d2a71f2f99a



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Add a rcu argument to the ->get_acl() callback to allow
get_cached_acl_rcu() to call the ->get_acl() method in the next patch.

Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
[chengzhihao: rename get_acl to get_acl2 to prevent KABI changes, and
 only backport(realize) overlayfs]
Conflicts:
	fs/overlayfs/dir.c
	fs/overlayfs/inode.c
	fs/overlayfs/overlayfs.h
	fs/posix_acl.c
	include/linux/fs.h
Signed-off-by: Zhihao Cheng <chengzhihao1@huawei.com>
Reviewed-by: Zhang Yi <yi.zhang@huawei.com>
Signed-off-by: Jialin Zhang <zhangjialin11@huawei.com>