cachefiles: narrow the scope of triggering EPOLLIN events in ondemand mode

Don't trigger EPOLLIN when there are only reopening read requests in
xarray.

Suggested-by: Xin Yin <[email protected]>
Signed-off-by: Jia Zhu <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Reviewed-by: Jingbo Xu <[email protected]>
Reviewed-by: David Howells <[email protected]>
Signed-off-by: Christian Brauner <[email protected]>

diff --git a/fs/cachefiles/daemon.c b/fs/cachefiles/daemon.c
index aa4efcabb5e37b155407e724d22572c34fde1d3f..70caa1946207dce70c228e3282fd2c2c9f612c94 100644 (file)
--- a/fs/cachefiles/daemon.c
+++ b/fs/cachefiles/daemon.c
@@ -355,14 +355,24 @@ static __poll_t cachefiles_daemon_poll(struct file *file,
                                           struct poll_table_struct *poll)
 {
        struct cachefiles_cache *cache = file->private_data;
+       XA_STATE(xas, &cache->reqs, 0);
+       struct cachefiles_req *req;
        __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(&cache->reqs)) {
+                       rcu_read_lock();
+                       xas_for_each_marked(&xas, req, ULONG_MAX, 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 b9a90f1a0c015d472cc5bcb337fd02b19eb1d618..26e5f8f123ef17e4fdb4785862f4fd52cd6f236f 100644 (file)
--- 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
 
 /*