* 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/os/drivers/fs_interface.h

@@ -21,6 +21,9 @@ struct stat;
 struct fs_info;
 struct select_sync;
 
+typedef struct IORequest io_request;
+
+
 /* additional flags passed to write_stat() (see NodeMonitor.h for the others) */
 // NOTE: Changing the constants here or in NodeMonitor.h will break
 // src/kits/storage/LibBeAdapter.cpp:_kern_write_stat().
@@ -124,6 +127,12 @@ struct fs_vnode_ops {
 				void *cookie, off_t pos, const iovec *vecs, size_t count,
 				size_t *_numBytes);
 
+	/* asynchronous I/O */
+	status_t (*io)(fs_volume *volume, fs_vnode *vnode, void *cookie,
+				io_request *request);
+	status_t (*cancel_io)(fs_volume *volume, fs_vnode *vnode, void *cookie,
+				io_request *request);
+
 	/* cache file access */
 	status_t (*get_file_map)(fs_volume *volume, fs_vnode *vnode, off_t offset,
 				size_t size, struct file_io_vec *vecs, size_t *_count);
@@ -284,6 +293,14 @@ typedef struct file_system_module_info {
 
 
 /* file system add-ons only prototypes */
+
+// callbacks for do_iterative_fd_io()
+typedef status_t (*iterative_io_get_vecs)(void *cookie, io_request* request,
+				off_t offset, size_t size, struct file_io_vec *vecs,
+				size_t *_count);
+typedef status_t (*iterative_io_finished)(void* cookie, io_request* request,
+				status_t status);
+
 extern status_t new_vnode(fs_volume *volume, ino_t vnodeID, void *privateNode,
 					fs_vnode_ops *ops);
 extern status_t publish_vnode(fs_volume *volume, ino_t vnodeID,
@@ -309,6 +326,10 @@ extern status_t write_file_io_vec_pages(int fd,
 					const struct file_io_vec *fileVecs, size_t fileVecCount,
 					const struct iovec *vecs, size_t vecCount,
 					uint32 *_vecIndex, size_t *_vecOffset, size_t *_bytes);
+extern status_t do_fd_io(int fd, io_request *request);
+extern status_t do_iterative_fd_io(int fd, io_request *request,
+					iterative_io_get_vecs getVecs,
+					iterative_io_finished finished, void *cookie);
 
 extern status_t notify_entry_created(dev_t device, ino_t directory,
 					const char *name, ino_t node);

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,

headers/private/kernel/vfs.h

@@ -97,6 +97,10 @@ status_t vfs_read_pages(struct vnode *vnode, void *cookie, off_t pos,
 			const iovec *vecs, size_t count, size_t *_numBytes);
 status_t vfs_write_pages(struct vnode *vnode, void *cookie, off_t pos,
 			const iovec *vecs, size_t count, size_t *_numBytes);
+status_t vfs_synchronous_io(io_request* request,
+			status_t (*doIO)(void* cookie, off_t offset, void* buffer,
+				size_t length),
+			void* cookie);
 status_t vfs_get_vnode_cache(struct vnode *vnode, struct VMCache **_cache,
 			bool allocate);
 status_t vfs_get_file_map(struct vnode *vnode, off_t offset, size_t size,