* Implement poll support. Patch by Tejun Heo

4 files changed, 115 insertions, 2 deletions

diff --git a/include/fuse.h b/include/fuse.h
index 2016ccc..e1b863c 100644
--- a/include/fuse.h
+++ b/include/fuse.h
@@ -469,11 +469,30 @@ struct fuse_operations {
 	 * _IOC_READ in area and if both are set in/out area.  In all
 	 * non-NULL cases, the area is of _IOC_SIZE(@cmd) bytes.
 	 *
-	 * Introduced in version 2.9
+	 * Introduced in version 2.8
 	 */
 	int (*ioctl) (const char *, int cmd, void *arg,
 		      struct fuse_file_info *, unsigned int flags, void *data);
 
+	/**
+	 * Poll for IO readiness events
+	 *
+	 * Note: If @ph is non-NULL, the client should notify
+	 * when IO readiness events occur by calling
+	 * fuse_notify_poll() with the specified @ph.
+	 *
+	 * Regardless of the number of times poll with a non-NULL @ph
+	 * is received, single notification is enough to clear all.
+	 * Notifying more times incurs overhead but doesn't harm
+	 * correctness.
+	 *
+	 * The callee is responsible for destroying @ph with
+	 * fuse_pollhandle_destroy() when no longer in use.
+	 *
+	 * Introduced in version 2.8
+	 */
+	int (*poll) (const char *, struct fuse_file_info *,
+		     struct fuse_pollhandle *ph, unsigned *reventsp);
 };
 
 /** Extra context that may be needed by some filesystems
@@ -708,9 +727,14 @@ int fuse_fs_bmap(struct fuse_fs *fs, const char *path, size_t blocksize,
 		 uint64_t *idx);
 int fuse_fs_ioctl(struct fuse_fs *fs, const char *path, int cmd, void *arg,
 		  struct fuse_file_info *fi, unsigned int flags, void *data);
+int fuse_fs_poll(struct fuse_fs *fs, const char *path,
+		 struct fuse_file_info *fi, struct fuse_pollhandle *ph,
+		 unsigned *reventsp);
 void fuse_fs_init(struct fuse_fs *fs, struct fuse_conn_info *conn);
 void fuse_fs_destroy(struct fuse_fs *fs);
 
+int fuse_notify_poll(struct fuse_pollhandle *ph);
+
 /**
  * Create a new fuse filesystem object
  *
diff --git a/include/fuse_common.h b/include/fuse_common.h
index fb18b61..b05ed21 100644
--- a/include/fuse_common.h
+++ b/include/fuse_common.h
@@ -159,6 +159,7 @@ struct fuse_conn_info {
 
 struct fuse_session;
 struct fuse_chan;
+struct fuse_pollhandle;
 
 /**
  * Create a FUSE mountpoint
@@ -219,6 +220,13 @@ int fuse_daemonize(int foreground);
  */
 int fuse_version(void);
 
+/**
+ * Destroy poll handle
+ *
+ * @param ph the poll handle
+ */
+void fuse_pollhandle_destroy(struct fuse_pollhandle *ph);
+
 /* ----------------------------------------------------------- *
  * Signal handling					       *
  * ----------------------------------------------------------- */
diff --git a/include/fuse_kernel.h b/include/fuse_kernel.h
index eb28a35..df558e3 100644
--- a/include/fuse_kernel.h
+++ b/include/fuse_kernel.h
@@ -49,6 +49,8 @@
  *
  * 7.11
  *  - add IOCTL message
+ *  - add unsolicited notification support
+ *  - add POLL message and NOTIFY_POLL notification
  */
 
 #ifndef _LINUX_FUSE_H
@@ -191,6 +193,13 @@ struct fuse_file_lock {
 
 #define FUSE_IOCTL_MAX_IOV	256
 
+/**
+ * Poll flags
+ *
+ * FUSE_POLL_SCHEDULE_NOTIFY: request poll notify
+ */
+#define FUSE_POLL_SCHEDULE_NOTIFY (1 << 0)
+
 enum fuse_opcode {
 	FUSE_LOOKUP	   = 1,
 	FUSE_FORGET	   = 2,  /* no reply */
@@ -229,6 +238,12 @@ enum fuse_opcode {
 	FUSE_BMAP          = 37,
 	FUSE_DESTROY       = 38,
 	FUSE_IOCTL         = 39,
+	FUSE_POLL          = 40,
+};
+
+enum fuse_notify_code {
+	FUSE_NOTIFY_POLL   = 1,
+	FUSE_NOTIFY_CODE_MAX,
 };
 
 /* The read buffer is required to be at least 8k, but may be much larger */
@@ -445,6 +460,22 @@ struct fuse_ioctl_out {
 	__u32	out_iovs;
 };
 
+struct fuse_poll_in {
+	__u64	fh;
+	__u64	kh;
+	__u32	flags;
+	__u32   padding;
+};
+
+struct fuse_poll_out {
+	__u32	revents;
+	__u32	padding;
+};
+
+struct fuse_notify_poll_wakeup_out {
+	__u64	kh;
+};
+
 struct fuse_in_header {
 	__u32	len;
 	__u32	opcode;
diff --git a/include/fuse_lowlevel.h b/include/fuse_lowlevel.h
index e17274f..0b83214 100644
--- a/include/fuse_lowlevel.h
+++ b/include/fuse_lowlevel.h
@@ -817,7 +817,7 @@ struct fuse_lowlevel_ops {
 	 * restricted ioctls, kernel prepares in/out data area
 	 * according to the information encoded in @cmd.
 	 *
-	 * Introduced in version 2.9
+	 * Introduced in version 2.8
 	 *
 	 * Valid replies:
 	 *   fuse_reply_ioctl_retry
@@ -837,6 +837,35 @@ struct fuse_lowlevel_ops {
 	void (*ioctl) (fuse_req_t req, fuse_ino_t ino, int cmd, void *arg,
 		       struct fuse_file_info *fi, unsigned *flagsp,
 		       const void *in_buf, size_t in_bufsz, size_t out_bufszp);
+
+	/**
+	 * Poll for IO readiness
+	 *
+	 * Introduced in version 2.8
+	 *
+	 * Note: If @ph is non-NULL, the client should notify
+	 * when IO readiness events occur by calling
+	 * fuse_lowelevel_notify_poll() with the specified @ph.
+	 *
+	 * Regardless of the number of times poll with a non-NULL @ph
+	 * is received, single notification is enough to clear all.
+	 * Notifying more times incurs overhead but doesn't harm
+	 * correctness.
+	 *
+	 * The callee is responsible for destroying @ph with
+	 * fuse_pollhandle_destroy() when no longer in use.
+	 *
+	 * Valid replies:
+	 *   fuse_reply_poll
+	 *   fuse_reply_err
+	 *
+	 * @param req request handle
+	 * @param ino the inode number
+	 * @param fi file information
+	 * @param ph poll handle to be used for notification
+	 */
+	void (*poll) (fuse_req_t req, fuse_ino_t ino, struct fuse_file_info *fi,
+		      struct fuse_pollhandle *ph);
 };
 
 /**
@@ -1084,6 +1113,27 @@ int fuse_reply_ioctl_retry(fuse_req_t req,
  */
 int fuse_reply_ioctl(fuse_req_t req, int result, const void *buf, size_t size);
 
+/**
+ * Reply with poll result event mask
+ *
+ * @param req request handle
+ * @param revents poll result event mask
+ */
+int fuse_reply_poll(fuse_req_t req, unsigned revents);
+
+/* ----------------------------------------------------------- *
+ * Notification						       *
+ * ----------------------------------------------------------- */
+
+/**
+ * Notify IO readiness event
+ *
+ * For more information, please read comment for poll operation.
+ *
+ * @param ph poll handle to notify IO readiness event for
+ */
+int fuse_lowlevel_notify_poll(struct fuse_pollhandle *ph);
+
 /* ----------------------------------------------------------- *
  * Utility functions					       *
  * ----------------------------------------------------------- */