xen/patches/linux-2.6.16.29/blktap-aio-16_03_06.patch

diff -pruN ../orig-linux-2.6.16.29/fs/aio.c ./fs/aio.c
--- ../orig-linux-2.6.16.29/fs/aio.c	2006-09-12 19:02:10.000000000 +0100
+++ ./fs/aio.c	2006-09-19 13:58:49.000000000 +0100
@@ -34,6 +34,11 @@
 #include <asm/uaccess.h>
 #include <asm/mmu_context.h>
 
+#ifdef CONFIG_EPOLL
+#include <linux/poll.h>
+#include <linux/eventpoll.h>
+#endif
+
 #if DEBUG > 1
 #define dprintk		printk
 #else
@@ -1016,6 +1021,10 @@ put_rq:
 	if (waitqueue_active(&ctx->wait))
 		wake_up(&ctx->wait);
 
+#ifdef CONFIG_EPOLL
+	if (ctx->file && waitqueue_active(&ctx->poll_wait))
+		wake_up(&ctx->poll_wait);
+#endif
 	if (ret)
 		put_ioctx(ctx);
 
@@ -1025,6 +1034,8 @@ put_rq:
 /* aio_read_evt
  *	Pull an event off of the ioctx's event ring.  Returns the number of 
  *	events fetched (0 or 1 ;-)
+ *	If ent parameter is 0, just returns the number of events that would
+ *	be fetched.
  *	FIXME: make this use cmpxchg.
  *	TODO: make the ringbuffer user mmap()able (requires FIXME).
  */
@@ -1047,13 +1058,18 @@ static int aio_read_evt(struct kioctx *i
 
 	head = ring->head % info->nr;
 	if (head != ring->tail) {
-		struct io_event *evp = aio_ring_event(info, head, KM_USER1);
-		*ent = *evp;
-		head = (head + 1) % info->nr;
-		smp_mb(); /* finish reading the event before updatng the head */
-		ring->head = head;
-		ret = 1;
-		put_aio_ring_event(evp, KM_USER1);
+		if (ent) { /* event requested */
+			struct io_event *evp =
+				aio_ring_event(info, head, KM_USER1);
+			*ent = *evp;
+			head = (head + 1) % info->nr;
+			/* finish reading the event before updatng the head */
+			smp_mb();
+			ring->head = head;
+			ret = 1;
+			put_aio_ring_event(evp, KM_USER1);
+		} else /* only need to know availability */
+			ret = 1;
 	}
 	spin_unlock(&info->ring_lock);
 
@@ -1236,9 +1252,78 @@ static void io_destroy(struct kioctx *io
 
 	aio_cancel_all(ioctx);
 	wait_for_all_aios(ioctx);
+#ifdef CONFIG_EPOLL
+	/* forget the poll file, but it's up to the user to close it */
+	if (ioctx->file) {
+		ioctx->file->private_data = 0;
+		ioctx->file = 0;
+	}
+#endif
 	put_ioctx(ioctx);	/* once for the lookup */
 }
 
+#ifdef CONFIG_EPOLL
+
+static int aio_queue_fd_close(struct inode *inode, struct file *file)
+{
+	struct kioctx *ioctx = file->private_data;
+	if (ioctx) {
+		file->private_data = 0;
+		spin_lock_irq(&ioctx->ctx_lock);
+		ioctx->file = 0;
+		spin_unlock_irq(&ioctx->ctx_lock);
+	}
+	return 0;
+}
+
+static unsigned int aio_queue_fd_poll(struct file *file, poll_table *wait)
+{	unsigned int pollflags = 0;
+	struct kioctx *ioctx = file->private_data;
+
+	if (ioctx) {
+
+		spin_lock_irq(&ioctx->ctx_lock);
+		/* Insert inside our poll wait queue */
+		poll_wait(file, &ioctx->poll_wait, wait);
+
+		/* Check our condition */
+		if (aio_read_evt(ioctx, 0))
+			pollflags = POLLIN | POLLRDNORM;
+		spin_unlock_irq(&ioctx->ctx_lock);
+	}
+
+	return pollflags;
+}
+
+static struct file_operations aioq_fops = {
+	.release	= aio_queue_fd_close,
+	.poll		= aio_queue_fd_poll
+};
+
+/* make_aio_fd:
+ *  Create a file descriptor that can be used to poll the event queue.
+ *  Based and piggybacked on the excellent epoll code.
+ */
+
+static int make_aio_fd(struct kioctx *ioctx)
+{
+	int error, fd;
+	struct inode *inode;
+	struct file *file;
+
+	error = ep_getfd(&fd, &inode, &file, NULL, &aioq_fops);
+	if (error)
+		return error;
+
+	/* associate the file with the IO context */
+	file->private_data = ioctx;
+	ioctx->file = file;
+	init_waitqueue_head(&ioctx->poll_wait);
+	return fd;
+}
+#endif
+
+
 /* sys_io_setup:
  *	Create an aio_context capable of receiving at least nr_events.
  *	ctxp must not point to an aio_context that already exists, and
@@ -1251,18 +1336,30 @@ static void io_destroy(struct kioctx *io
  *	resources are available.  May fail with -EFAULT if an invalid
  *	pointer is passed for ctxp.  Will fail with -ENOSYS if not
  *	implemented.
+ *
+ *	To request a selectable fd, the user context has to be initialized
+ *	to 1, instead of 0, and the return value is the fd.
+ *	This keeps the system call compatible, since a non-zero value
+ *	was not allowed so far.
  */
 asmlinkage long sys_io_setup(unsigned nr_events, aio_context_t __user *ctxp)
 {
 	struct kioctx *ioctx = NULL;
 	unsigned long ctx;
 	long ret;
+	int make_fd = 0;
 
 	ret = get_user(ctx, ctxp);
 	if (unlikely(ret))
 		goto out;
 
 	ret = -EINVAL;
+#ifdef CONFIG_EPOLL
+	if (ctx == 1) {
+		make_fd = 1;
+		ctx = 0;
+	}
+#endif
 	if (unlikely(ctx || nr_events == 0)) {
 		pr_debug("EINVAL: io_setup: ctx %lu nr_events %u\n",
 		         ctx, nr_events);
@@ -1273,8 +1370,12 @@ asmlinkage long sys_io_setup(unsigned nr
 	ret = PTR_ERR(ioctx);
 	if (!IS_ERR(ioctx)) {
 		ret = put_user(ioctx->user_id, ctxp);
-		if (!ret)
-			return 0;
+#ifdef CONFIG_EPOLL
+		if (make_fd && ret >= 0)
+			ret = make_aio_fd(ioctx);
+#endif
+		if (ret >= 0)
+			return ret;
 
 		get_ioctx(ioctx); /* io_destroy() expects us to hold a ref */
 		io_destroy(ioctx);
diff -pruN ../orig-linux-2.6.16.29/fs/eventpoll.c ./fs/eventpoll.c
--- ../orig-linux-2.6.16.29/fs/eventpoll.c	2006-09-12 19:02:10.000000000 +0100
+++ ./fs/eventpoll.c	2006-09-19 13:58:49.000000000 +0100
@@ -235,8 +235,6 @@ struct ep_pqueue {
 
 static void ep_poll_safewake_init(struct poll_safewake *psw);
 static void ep_poll_safewake(struct poll_safewake *psw, wait_queue_head_t *wq);
-static int ep_getfd(int *efd, struct inode **einode, struct file **efile,
-		    struct eventpoll *ep);
 static int ep_alloc(struct eventpoll **pep);
 static void ep_free(struct eventpoll *ep);
 static struct epitem *ep_find(struct eventpoll *ep, struct file *file, int fd);
@@ -266,7 +264,7 @@ static int ep_events_transfer(struct eve
 static int ep_poll(struct eventpoll *ep, struct epoll_event __user *events,
 		   int maxevents, long timeout);
 static int eventpollfs_delete_dentry(struct dentry *dentry);
-static struct inode *ep_eventpoll_inode(void);
+static struct inode *ep_eventpoll_inode(struct file_operations *fops);
 static struct super_block *eventpollfs_get_sb(struct file_system_type *fs_type,
 					      int flags, const char *dev_name,
 					      void *data);
@@ -525,7 +523,7 @@ asmlinkage long sys_epoll_create(int siz
 	 * Creates all the items needed to setup an eventpoll file. That is,
 	 * a file structure, and inode and a free file descriptor.
 	 */
-	error = ep_getfd(&fd, &inode, &file, ep);
+	error = ep_getfd(&fd, &inode, &file, ep, &eventpoll_fops);
 	if (error)
 		goto eexit_2;
 
@@ -710,8 +708,8 @@ eexit_1:
 /*
  * Creates the file descriptor to be used by the epoll interface.
  */
-static int ep_getfd(int *efd, struct inode **einode, struct file **efile,
-		    struct eventpoll *ep)
+int ep_getfd(int *efd, struct inode **einode, struct file **efile,
+		    struct eventpoll *ep, struct file_operations *fops)
 {
 	struct qstr this;
 	char name[32];
@@ -727,7 +725,7 @@ static int ep_getfd(int *efd, struct ino
 		goto eexit_1;
 
 	/* Allocates an inode from the eventpoll file system */
-	inode = ep_eventpoll_inode();
+	inode = ep_eventpoll_inode(fops);
 	error = PTR_ERR(inode);
 	if (IS_ERR(inode))
 		goto eexit_2;
@@ -758,7 +756,7 @@ static int ep_getfd(int *efd, struct ino
 
 	file->f_pos = 0;
 	file->f_flags = O_RDONLY;
-	file->f_op = &eventpoll_fops;
+	file->f_op = fops;
 	file->f_mode = FMODE_READ;
 	file->f_version = 0;
 	file->private_data = ep;
@@ -1574,7 +1572,7 @@ static int eventpollfs_delete_dentry(str
 }
 
 
-static struct inode *ep_eventpoll_inode(void)
+static struct inode *ep_eventpoll_inode(struct file_operations *fops)
 {
 	int error = -ENOMEM;
 	struct inode *inode = new_inode(eventpoll_mnt->mnt_sb);
@@ -1582,7 +1580,7 @@ static struct inode *ep_eventpoll_inode(
 	if (!inode)
 		goto eexit_1;
 
-	inode->i_fop = &eventpoll_fops;
+	inode->i_fop = fops;
 
 	/*
 	 * Mark the inode dirty from the very beginning,
diff -pruN ../orig-linux-2.6.16.29/include/linux/aio.h ./include/linux/aio.h
--- ../orig-linux-2.6.16.29/include/linux/aio.h	2006-09-12 19:02:10.000000000 +0100
+++ ./include/linux/aio.h	2006-09-19 13:58:49.000000000 +0100
@@ -191,6 +191,11 @@ struct kioctx {
 	struct aio_ring_info	ring_info;
 
 	struct work_struct	wq;
+#ifdef CONFIG_EPOLL
+	// poll integration
+	wait_queue_head_t       poll_wait;
+	struct file		*file;
+#endif
 };
 
 /* prototypes */
diff -pruN ../orig-linux-2.6.16.29/include/linux/eventpoll.h ./include/linux/eventpoll.h
--- ../orig-linux-2.6.16.29/include/linux/eventpoll.h	2006-09-12 19:02:10.000000000 +0100
+++ ./include/linux/eventpoll.h	2006-09-19 13:58:49.000000000 +0100
@@ -86,6 +86,12 @@ static inline void eventpoll_release(str
 }
 
 
+/*
+ * called by aio code to create fd that can poll the  aio event queueQ
+ */
+struct eventpoll;
+int ep_getfd(int *efd, struct inode **einode, struct file **efile,
+             struct eventpoll *ep, struct file_operations *fops);
 #else
 
 static inline void eventpoll_init_file(struct file *file) {}