@@ -5,6 +5,7 @@
* Implements an efficient asynchronous io interface.
*
* Copyright 2000, 2001, 2002 Red Hat, Inc. All Rights Reserved.
+ * Copyright 2018 Christoph Hellwig.
*
* See ../COPYING for licensing terms.
*/
@@ -162,10 +163,18 @@ struct fsync_iocb {
bool datasync;
};
+struct poll_iocb {
+ struct file *file;
+ __poll_t events;
+ struct wait_queue_head *head;
+ struct wait_queue_entry wait;
+};
+
struct aio_kiocb {
union {
struct kiocb rw;
struct fsync_iocb fsync;
+ struct poll_iocb poll;
};
struct kioctx *ki_ctx;
@@ -1577,7 +1586,6 @@ static int aio_fsync(struct fsync_iocb *req, struct iocb *iocb, bool datasync)
return -EINVAL;
if (iocb->aio_offset || iocb->aio_nbytes || iocb->aio_rw_flags)
return -EINVAL;
-
req->file = fget(iocb->aio_fildes);
if (unlikely(!req->file))
return -EBADF;
@@ -1596,6 +1604,91 @@ static int aio_fsync(struct fsync_iocb *req, struct iocb *iocb, bool datasync)
return ret;
}
+static void aio_complete_poll(struct poll_iocb *req, __poll_t mask)
+{
+ struct aio_kiocb *iocb = container_of(req, struct aio_kiocb, poll);
+ struct file *file = req->file;
+
+ if (aio_complete(iocb, mangle_poll(mask), 0, 0))
+ fput(file);
+}
+
+static int aio_poll_cancel(struct kiocb *rw)
+{
+ struct aio_kiocb *iocb = container_of(rw, struct aio_kiocb, rw);
+ struct file *file = iocb->poll.file;
+
+ remove_wait_queue(iocb->poll.head, &iocb->poll.wait);
+ if (aio_complete(iocb, 0, 0, AIO_COMPLETE_CANCEL))
+ fput(file);
+ return 0;
+}
+
+static int aio_poll_wake(struct wait_queue_entry *wait, unsigned mode, int sync,
+ void *key)
+{
+ struct poll_iocb *req = container_of(wait, struct poll_iocb, wait);
+ struct file *file = req->file;
+ __poll_t mask = key_to_poll(key);
+
+ assert_spin_locked(&req->head->lock);
+
+ /* for instances that support it check for an event match first: */
+ if (mask && !(mask & req->events))
+ return 0;
+
+ mask = vfs_poll_mask(file, req->events);
+ if (!mask)
+ return 0;
+
+ __remove_wait_queue(req->head, &req->wait);
+ aio_complete_poll(req, mask);
+ return 1;
+}
+
+static ssize_t aio_poll(struct aio_kiocb *aiocb, struct iocb *iocb)
+{
+ struct poll_iocb *req = &aiocb->poll;
+ unsigned long flags;
+ __poll_t mask;
+
+ /* reject any unknown events outside the normal event mask. */
+ if ((u16)iocb->aio_buf != iocb->aio_buf)
+ return -EINVAL;
+ /* reject fields that are not defined for poll */
+ if (iocb->aio_offset || iocb->aio_nbytes || iocb->aio_rw_flags)
+ return -EINVAL;
+
+ req->events = demangle_poll(iocb->aio_buf) | POLLERR | POLLHUP;
+ req->file = fget(iocb->aio_fildes);
+ if (unlikely(!req->file))
+ return -EBADF;
+
+ req->head = vfs_get_poll_head(req->file, req->events);
+ if (!req->head) {
+ fput(req->file);
+ return -EINVAL; /* same as no support for IOCB_CMD_POLL */
+ }
+ if (IS_ERR(req->head)) {
+ mask = PTR_TO_POLL(req->head);
+ goto done;
+ }
+
+ init_waitqueue_func_entry(&req->wait, aio_poll_wake);
+
+ spin_lock_irqsave(&req->head->lock, flags);
+ mask = vfs_poll_mask(req->file, req->events);
+ if (!mask) {
+ __kiocb_set_cancel_fn(aiocb, aio_poll_cancel);
+ __add_wait_queue(req->head, &req->wait);
+ }
+ spin_unlock_irqrestore(&req->head->lock, flags);
+done:
+ if (mask)
+ aio_complete_poll(req, mask);
+ return -EIOCBQUEUED;
+}
+
static int io_submit_one(struct kioctx *ctx, struct iocb __user *user_iocb,
struct iocb *iocb, bool compat)
{
@@ -1664,6 +1757,8 @@ static int io_submit_one(struct kioctx *ctx, struct iocb __user *user_iocb,
break;
case IOCB_CMD_FDSYNC:
ret = aio_fsync(&req->fsync, iocb, true);
+ case IOCB_CMD_POLL:
+ ret = aio_poll(req, iocb);
break;
default:
pr_debug("invalid aio operation %d\n", iocb->aio_lio_opcode);
@@ -39,10 +39,8 @@ enum {
IOCB_CMD_PWRITE = 1,
IOCB_CMD_FSYNC = 2,
IOCB_CMD_FDSYNC = 3,
- /* These two are experimental.
- * IOCB_CMD_PREADX = 4,
- * IOCB_CMD_POLL = 5,
- */
+ /* 4 was the experimental IOCB_CMD_PREADX */
+ IOCB_CMD_POLL = 5,
IOCB_CMD_NOOP = 6,
IOCB_CMD_PREADV = 7,
IOCB_CMD_PWRITEV = 8,