Commit bd5b0ab7 authored by Baokun Li's avatar Baokun Li Committed by Zizhi Wo
Browse files

cachefiles: make on-demand read killable 

mainline inclusion
from mainline-v6.10-rc4
commit bc9dde6155464e906e630a0a5c17a4cab241ffbb
category: feature
bugzilla: https://gitee.com/openeuler/kernel/issues/IA6I1T

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=bc9dde6155464e906e630a0a5c17a4cab241ffbb



--------------------------------

Replacing wait_for_completion() with wait_for_completion_killable() in
cachefiles_ondemand_send_req() allows us to kill processes that might
trigger a hunk_task if the daemon is abnormal.

But now only CACHEFILES_OP_READ is killable, because OP_CLOSE and OP_OPEN
is initiated from kworker context and the signal is prohibited in these
kworker.

Note that when the req in xas changes, i.e. xas_load(&xas) != req, it
means that a process will complete the current request soon, so wait
again for the request to be completed.

In addition, add the cachefiles_ondemand_finish_req() helper function to
simplify the code.

Suggested-by: default avatarHou Tao <houtao1@huawei.com>
Signed-off-by: default avatarBaokun Li <libaokun1@huawei.com>
Link: https://lore.kernel.org/r/20240522114308.2402121-13-libaokun@huaweicloud.com


Acked-by: default avatarJeff Layton <jlayton@kernel.org>
Reviewed-by: default avatarJia Zhu <zhujia.zj@bytedance.com>
Signed-off-by: default avatarChristian Brauner <brauner@kernel.org>
Signed-off-by: default avatarZizhi Wo <wozizhi@huawei.com>
parent 53b8fd79

fs/cachefiles/ondemand.c

+28 −12
Original line number Diff line number Diff line
@@ -380,6 +380,20 @@ static struct cachefiles_req *cachefiles_ondemand_select_req(struct xa_state *xa 
	return NULL;

}



static inline bool cachefiles_ondemand_finish_req(struct cachefiles_req *req,

						  struct xa_state *xas, int err)

{

	if (unlikely(!xas || !req))

		return false;



	if (xa_cmpxchg(xas->xa, xas->xa_index, req, NULL, 0) != req)

		return false;



	req->error = err;

	complete(&req->done);

	return true;

}



ssize_t cachefiles_ondemand_daemon_read(struct cachefiles_cache *cache,

					char __user *_buffer, size_t buflen)

{
@@ -443,16 +457,8 @@ ssize_t cachefiles_ondemand_daemon_read(struct cachefiles_cache *cache, 
out:

	cachefiles_put_object(req->object, cachefiles_obj_put_read_req);

	/* Remove error request and CLOSE request has no reply */

	if (ret || msg->opcode == CACHEFILES_OP_CLOSE) {

		xas_reset(&xas);

		xas_lock(&xas);

		if (xas_load(&xas) == req) {

			req->error = ret;

			complete(&req->done);

			xas_store(&xas, NULL);

		}

		xas_unlock(&xas);

	}

	if (ret || msg->opcode == CACHEFILES_OP_CLOSE)

		cachefiles_ondemand_finish_req(req, &xas, ret);

	cachefiles_req_put(req);

	return ret ? ret : n;

}
@@ -544,8 +550,18 @@ static int cachefiles_ondemand_send_req(struct cachefiles_object *object, 
		goto out;



	wake_up_all(&cache->daemon_pollwq);

	wait_for_completion(&req->done);

wait:

	ret = wait_for_completion_killable(&req->done);

	if (!ret) {

		ret = req->error;

	} else {

		ret = -EINTR;

		if (!cachefiles_ondemand_finish_req(req, &xas, ret)) {

			/* Someone will complete it soon. */

			cpu_relax();

			goto wait;

		}

	}

	cachefiles_req_put(req);

	return ret;

out: