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

From: Jia Zhu
Date: Tue Oct 11 2022 - 09:18:06 EST


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

Suggested-by: Xin Yin <yinxin.x@xxxxxxxxxxxxx>
Signed-off-by: Jia Zhu <zhujia.zj@xxxxxxxxxxxxx>
---
fs/cachefiles/daemon.c | 13 +++++++++++--
fs/cachefiles/internal.h | 12 ++++++++++++
2 files changed, 23 insertions(+), 2 deletions(-)

diff --git a/fs/cachefiles/daemon.c b/fs/cachefiles/daemon.c
index aa4efcabb5e3..c74bd1f4ecf5 100644
--- a/fs/cachefiles/daemon.c
+++ b/fs/cachefiles/daemon.c
@@ -355,14 +355,23 @@ 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)) {
+ xa_for_each_marked(xa, index, req, CACHEFILES_REQ_NEW) {
+ if (!cachefiles_ondemand_is_reopening_read(req)) {
+ mask |= EPOLLIN;
+ break;
+ }
+ }
+ }
} else {
if (test_bit(CACHEFILES_STATE_CHANGED, &cache->flags))
mask |= EPOLLIN;
diff --git a/fs/cachefiles/internal.h b/fs/cachefiles/internal.h
index a9f45972945d..4655b8a14a60 100644
--- a/fs/cachefiles/internal.h
+++ b/fs/cachefiles/internal.h
@@ -340,6 +340,13 @@ cachefiles_ondemand_set_object_##_state(struct cachefiles_object *object) \
CACHEFILES_OBJECT_STATE_FUNCS(open);
CACHEFILES_OBJECT_STATE_FUNCS(close);
CACHEFILES_OBJECT_STATE_FUNCS(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)
@@ -367,6 +374,11 @@ static inline int cachefiles_ondemand_init_obj_info(struct cachefiles_object *ob
{
return 0;
}
+
+static inline bool cachefiles_ondemand_is_reopening_read(struct cachefiles_req *req)
+{
+ return false;
+}
#endif

/*
--
2.20.1