diff mbox series

[V5,4/5] cachefiles: narrow the scope of triggering EPOLLIN events in ondemand mode

Message ID 20230329140155.53272-5-zhujia.zj@bytedance.com
State New
Headers
Series Introduce daemon failover mechanism to recover from crashing |

Commit Message

Jia Zhu March 29, 2023, 2:01 p.m. UTC 
  Don't trigger EPOLLIN when there are only reopening read requests in
xarray.

Suggested-by: Xin Yin <yinxin.x@bytedance.com>
Signed-off-by: Jia Zhu <zhujia.zj@bytedance.com>
---
 fs/cachefiles/daemon.c   | 15 +++++++++++++--
 fs/cachefiles/internal.h | 12 ++++++++++++
 2 files changed, 25 insertions(+), 2 deletions(-)

Comments

David Howells April 14, 2023, 1:48 p.m. UTC | #1 
Jia Zhu <zhujia.zj@bytedance.com> wrote:

>  	if (cachefiles_in_ondemand_mode(cache)) {
> -		if (!xa_empty(&cache->reqs))
> -			mask |= EPOLLIN;
> +		if (!xa_empty(xa)) {
> +			rcu_read_lock();
> +			xa_for_each_marked(xa, index, req, CACHEFILES_REQ_NEW) {
> +				if (!cachefiles_ondemand_is_reopening_read(req)) {
> +					mask |= EPOLLIN;
> +					break;
> +				}
> +			}
> +			rcu_read_unlock();

You should probably use xas_for_each_marked() instead of xa_for_each_marked()
as the former should perform better.

David
Jia Zhu April 14, 2023, 2:13 p.m. UTC | #2 
在 2023/4/14 21:48, David Howells 写道:
> Jia Zhu <zhujia.zj@bytedance.com> wrote:
> 
>>   	if (cachefiles_in_ondemand_mode(cache)) {
>> -		if (!xa_empty(&cache->reqs))
>> -			mask |= EPOLLIN;
>> +		if (!xa_empty(xa)) {
>> +			rcu_read_lock();
>> +			xa_for_each_marked(xa, index, req, CACHEFILES_REQ_NEW) {
>> +				if (!cachefiles_ondemand_is_reopening_read(req)) {
>> +					mask |= EPOLLIN;
>> +					break;
>> +				}
>> +			}
>> +			rcu_read_unlock();
> 
> You should probably use xas_for_each_marked() instead of xa_for_each_marked()
> as the former should perform better.
> 
> David

Hi David,

Thanks for your advice. I'll revise it in next version.

Jia
>
diff mbox series

Patch

diff --git a/fs/cachefiles/daemon.c b/fs/cachefiles/daemon.c
index aa4efcabb5e37..86892f471e761 100644
--- a/fs/cachefiles/daemon.c
+++ b/fs/cachefiles/daemon.c
@@ -355,14 +355,25 @@  static __poll_t cachefiles_daemon_poll(struct file *file,
 					   struct poll_table_struct *poll)
 {
 	struct cachefiles_cache *cache = file->private_data;
+	struct xarray *xa = &cache->reqs;
+	struct cachefiles_req *req;
+	unsigned long index;
 	__poll_t mask;
 
 	poll_wait(file, &cache->daemon_pollwq, poll);
 	mask = 0;
 
 	if (cachefiles_in_ondemand_mode(cache)) {
-		if (!xa_empty(&cache->reqs))
-			mask |= EPOLLIN;
+		if (!xa_empty(xa)) {
+			rcu_read_lock();
+			xa_for_each_marked(xa, index, req, CACHEFILES_REQ_NEW) {
+				if (!cachefiles_ondemand_is_reopening_read(req)) {
+					mask |= EPOLLIN;
+					break;
+				}
+			}
+			rcu_read_unlock();
+		}
 	} else {
 		if (test_bit(CACHEFILES_STATE_CHANGED, &cache->flags))
 			mask |= EPOLLIN;
diff --git a/fs/cachefiles/internal.h b/fs/cachefiles/internal.h
index b9a90f1a0c015..26e5f8f123ef1 100644
--- a/fs/cachefiles/internal.h
+++ b/fs/cachefiles/internal.h
@@ -329,6 +329,13 @@  cachefiles_ondemand_set_object_##_state(struct cachefiles_object *object) \
 CACHEFILES_OBJECT_STATE_FUNCS(open, OPEN);
 CACHEFILES_OBJECT_STATE_FUNCS(close, CLOSE);
 CACHEFILES_OBJECT_STATE_FUNCS(reopening, REOPENING);
+
+static inline bool cachefiles_ondemand_is_reopening_read(struct cachefiles_req *req)
+{
+	return cachefiles_ondemand_object_is_reopening(req->object) &&
+			req->msg.opcode == CACHEFILES_OP_READ;
+}
+
 #else
 static inline ssize_t cachefiles_ondemand_daemon_read(struct cachefiles_cache *cache,
 					char __user *_buffer, size_t buflen)
@@ -359,6 +366,11 @@  static inline int cachefiles_ondemand_init_obj_info(struct cachefiles_object *ob
 static inline void cachefiles_ondemand_deinit_obj_info(struct cachefiles_object *obj)
 {
 }
+
+static inline bool cachefiles_ondemand_is_reopening_read(struct cachefiles_req *req)
+{
+	return false;
+}
 #endif
 
 /*