eventfd is using ->read() as it's file_operations read handler, but
this prevents passing in information about whether a given IO operation
is blocking or not. We can only use the file flags for that. To support
async (-EAGAIN/poll based) retries for io_uring, we need ->read_iter()
support. Convert eventfd to using ->read_iter().
Signed-off-by: Jens Axboe <axboe@xxxxxxxxx>
---
diff --git a/fs/eventfd.c b/fs/eventfd.c
index 78e41c7c3d05..a4507424e80c 100644
--- a/fs/eventfd.c
+++ b/fs/eventfd.c
@@ -216,10 +216,11 @@ int eventfd_ctx_remove_wait_queue(struct eventfd_ctx *ctx, wait_queue_entry_t *w
}
EXPORT_SYMBOL_GPL(eventfd_ctx_remove_wait_queue);
-static ssize_t eventfd_read(struct file *file, char __user *buf, size_t count,
- loff_t *ppos)
+static ssize_t eventfd_read(struct kiocb *iocb, struct iov_iter *iov)
{
+ struct file *file = iocb->ki_filp;
struct eventfd_ctx *ctx = file->private_data;
+ size_t count = iov_iter_count(iov);
ssize_t res;
__u64 ucnt = 0;
DECLARE_WAITQUEUE(wait, current);
@@ -231,7 +232,8 @@ static ssize_t eventfd_read(struct file *file, char __user *buf, size_t count,
res = -EAGAIN;
if (ctx->count > 0)
res = sizeof(ucnt);
- else if (!(file->f_flags & O_NONBLOCK)) {
+ else if (!(file->f_flags & O_NONBLOCK) &&
+ !(iocb->ki_flags & IOCB_NOWAIT)) {
__add_wait_queue(&ctx->wqh, &wait);
for (;;) {
set_current_state(TASK_INTERRUPTIBLE);
@@ -257,7 +259,7 @@ static ssize_t eventfd_read(struct file *file, char __user *buf, size_t count,
}
spin_unlock_irq(&ctx->wqh.lock);
- if (res > 0 && put_user(ucnt, (__u64 __user *)buf))
+ if (res > 0 && copy_to_iter(&ucnt, res, iov) < res)
return -EFAULT;
return res;
@@ -329,7 +331,7 @@ static const struct file_operations eventfd_fops = {
#endif
.release = eventfd_release,
.poll = eventfd_poll,
- .read = eventfd_read,
+ .read_iter = eventfd_read,
.write = eventfd_write,
.llseek = noop_llseek,
};
--
Jens Axboe
