fs: add support for LOOKUP_CACHED

stable inclusion
from stable-v5.10.162
commit c1fe7bd3e1aa85865396b464b31f28b094a4353c
category: bugfix
bugzilla: https://gitee.com/src-openeuler/kernel/issues/I6BTWC

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?h=v5.10.167&id=c1fe7bd3e1aa85865396b464b31f28b094a4353c



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[ Upstream commit 6c6ec2b0 ]

io_uring always punts opens to async context, since there's no control
over whether the lookup blocks or not. Add LOOKUP_CACHED to support
just doing the fast RCU based lookups, which we know will not block. If
we can do a cached path resolution of the filename, then we don't have
to always punt lookups for a worker.

During path resolution, we always do LOOKUP_RCU first. If that fails and
we terminate LOOKUP_RCU, then fail a LOOKUP_CACHED attempt as well.

Cc: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Conflict:
  fs/namei.c

Signed-off-by: Li Lingfeng <lilingfeng3@huawei.com>
Reviewed-by: Zhang Yi <yi.zhang@huawei.com>
Reviewed-by: Wang Weiyang <wangweiyang2@huawei.com>
Signed-off-by: Jialin Zhang <zhangjialin11@huawei.com>