[PATCH 1/9] eventpoll: abstract out main epoll reaper into a function

[Jens Axboe <axboe@kernel.dk>]

Add epoll_wait(), which takes a struct file and the number of events
etc to reap. This can then be called by do_epoll_wait(), and used
by io_uring as well.

No intended functional changes in this patch.

Signed-off-by: Jens Axboe <axboe@kernel.dk>
---
 fs/eventpoll.c            | 31 ++++++++++++++++++-------------
 include/linux/eventpoll.h |  4 ++++
 2 files changed, 22 insertions(+), 13 deletions(-)

diff --git a/fs/eventpoll.c b/fs/eventpoll.c
index 7c0980db77b3..73b639caed3d 100644
--- a/fs/eventpoll.c
+++ b/fs/eventpoll.c
@@ -2445,12 +2445,8 @@ SYSCALL_DEFINE4(epoll_ctl, int, epfd, int, op, int, fd,
 	return do_epoll_ctl(epfd, op, fd, &epds, false);
 }
 
-/*
- * Implement the event wait interface for the eventpoll file. It is the kernel
- * part of the user space epoll_wait(2).
- */
-static int do_epoll_wait(int epfd, struct epoll_event __user *events,
-			 int maxevents, struct timespec64 *to)
+int epoll_wait(struct file *file, struct epoll_event __user *events,
+	       int maxevents, struct timespec64 *to)
 {
 	struct eventpoll *ep;
 
@@ -2462,28 +2458,37 @@ static int do_epoll_wait(int epfd, struct epoll_event __user *events,
 	if (!access_ok(events, maxevents * sizeof(struct epoll_event)))
 		return -EFAULT;
 
-	/* Get the "struct file *" for the eventpoll file */
-	CLASS(fd, f)(epfd);
-	if (fd_empty(f))
-		return -EBADF;
-
 	/*
 	 * We have to check that the file structure underneath the fd
 	 * the user passed to us _is_ an eventpoll file.
 	 */
-	if (!is_file_epoll(fd_file(f)))
+	if (!is_file_epoll(file))
 		return -EINVAL;
 
 	/*
 	 * At this point it is safe to assume that the "private_data" contains
 	 * our own data structure.
 	 */
-	ep = fd_file(f)->private_data;
+	ep = file->private_data;
 
 	/* Time to fish for events ... */
 	return ep_poll(ep, events, maxevents, to);
 }
 
+/*
+ * Implement the event wait interface for the eventpoll file. It is the kernel
+ * part of the user space epoll_wait(2).
+ */
+static int do_epoll_wait(int epfd, struct epoll_event __user *events,
+			 int maxevents, struct timespec64 *to)
+{
+	/* Get the "struct file *" for the eventpoll file */
+	CLASS(fd, f)(epfd);
+	if (!fd_empty(f))
+		return epoll_wait(fd_file(f), events, maxevents, to);
+	return -EBADF;
+}
+
 SYSCALL_DEFINE4(epoll_wait, int, epfd, struct epoll_event __user *, events,
 		int, maxevents, int, timeout)
 {
diff --git a/include/linux/eventpoll.h b/include/linux/eventpoll.h
index 0c0d00fcd131..f37fea931c44 100644
--- a/include/linux/eventpoll.h
+++ b/include/linux/eventpoll.h
@@ -25,6 +25,10 @@ struct file *get_epoll_tfile_raw_ptr(struct file *file, int tfd, unsigned long t
 /* Used to release the epoll bits inside the "struct file" */
 void eventpoll_release_file(struct file *file);
 
+/* Use to reap events */
+int epoll_wait(struct file *file, struct epoll_event __user *events,
+	       int maxevents, struct timespec64 *to);
+
 /*
  * This is called from inside fs/file_table.c:__fput() to unlink files
  * from the eventpoll interface. We need to have this facility to cleanup
-- 
2.47.2