* Added FS interface hooks io() and cancel_io(). The former is supposed

to provide asynchrounous (or only synchronous, if asynchronous is not
  supported) I/O request support. It will eventually replace
  {read,write}_pages(). None of the FS implementations implement them
  yet.
* Implemented some support functions for request-based I/O. File system
  implementations can use do_fd_io() which passes an I/O request to the
  layer responsible for a given FD, and do_iterative_fd_io(), which
  translates a request for a file to subrequests for the underlying
  device and passes them on. Both fall back to synchrounous processing
  when the io() hook is not supported.
  Furthermore added vfs_synchronous_io() which should be handy for the
  devfs to perform io_requests synchronously for devices that don't
  support the io() hook.


git-svn-id: file:///srv/svn/repos/haiku/haiku/trunk@26655 a95241bf-73f2-0310-859d-f6bbb57e9c96

headers/private/fs_shell/fssh_fs_interface.h

@@ -26,6 +26,8 @@ typedef fssh_ino_t fssh_vnode_id;
 /* the file system's private data structures */
 typedef void *fssh_fs_cookie;
 
+typedef struct FSSHIORequest fssh_io_request;
+
 /* additional flags passed to write_stat() */
 #define FSSH_B_STAT_SIZE_INSECURE	0x2000
 
@@ -142,6 +144,12 @@ struct fssh_fs_vnode_ops {
 				fssh_fs_cookie cookie, fssh_off_t pos, const fssh_iovec *vecs,
 				fssh_size_t count, fssh_size_t *_numBytes);
 
+	/* asynchronous I/O */
+	fssh_status_t (*io)(fssh_fs_volume *volume, fssh_fs_vnode *vnode,
+				void *cookie, fssh_io_request *request);
+	fssh_status_t (*cancel_io)(fssh_fs_volume *volume, fssh_fs_vnode *vnode,
+				void *cookie, fssh_io_request *request);
+
 	/* cache file access */
 	fssh_status_t (*get_file_map)(fssh_fs_volume *volume, fssh_fs_vnode *vnode,
 				fssh_off_t offset, fssh_size_t size,