* Extracted file_map API out of the file cache - it's now an optional service

that can be used by file systems.
* Changed the way the file cache works: instead of reading/writing to the
  underlying device directly, it can now be used for any data source, ie.
  also network file systems.
* As a result, the former pages_io() moved to the VFS layer, and can now be
  called by a file system via {read|write}_file_io_vec_pages() (naming
  suggestions are always welcomed :-)). It now gets an FD, and uses that to
  communicate with the device (via its fs_{read|write}_pages() hooks).
* The file_cache_{read|write}() functions must now be called without holding
  an I/O relevant file system lock. That allows the file cache to prepare the
  pages without colliding with the page writer, IOW the "mayBlock" flag can
  go into the attic again (yay!).
* This also results in a much better performance when the system does I/O and
  is low on memory, as the page writer can now finally write back some pages,
  and that even without maxing out the CPU :)
* The API changes put slightly more burden on the fs_{read|write}_pages()
  hooks, but in combination with the file_map it's still pretty straight
  forward. It just will have to dispatch the call to the underlying device
  directly, usually it will just call its fs_{read|write}_pages() hooks
  via the above mentioned calls.
* Ported BFS and FAT to the new API, the latter has not been tested, though.
* Also ported the API changes to the fs_shell. I also completely removed its
  file cache level page handling - the downside is that device access is no
  longer cached (ie. depends on the host OS now), the upside is that the code
  is greatly simplified.


git-svn-id: file:///srv/svn/repos/haiku/haiku/trunk@22886 a95241bf-73f2-0310-859d-f6bbb57e9c96

headers/os/drivers/fs_interface.h

@@ -92,10 +92,10 @@ typedef struct file_system_module_info {
 	bool (*can_page)(fs_volume fs, fs_vnode vnode, fs_cookie cookie);
 	status_t (*read_pages)(fs_volume fs, fs_vnode vnode, fs_cookie cookie,
 				off_t pos, const iovec *vecs, size_t count, size_t *_numBytes,
-				bool mayBlock, bool reenter);
+				bool reenter);
 	status_t (*write_pages)(fs_volume fs, fs_vnode vnode, fs_cookie cookie,
 				off_t pos, const iovec *vecs, size_t count, size_t *_numBytes,
-				bool mayBlock, bool reenter);
+				bool reenter);
 
 	/* cache file access */
 	status_t (*get_file_map)(fs_volume fs, fs_vnode vnode, off_t offset,
@@ -251,6 +251,18 @@ extern status_t remove_vnode(dev_t mountID, ino_t vnodeID);
 extern status_t unremove_vnode(dev_t mountID, ino_t vnodeID);
 extern status_t get_vnode_removed(dev_t mountID, ino_t vnodeID,
 					bool* removed);
+extern status_t read_pages(int fd, off_t pos, const struct iovec *vecs,
+					size_t count, size_t *_numBytes, bool fsReenter);
+extern status_t write_pages(int fd, off_t pos, const struct iovec *vecs,
+					size_t count, size_t *_numBytes, bool fsReenter);
+extern status_t read_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 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);
 
 // Deprecated! Will disappear soon!
 extern status_t notify_listener(int op, dev_t device, ino_t parentNode,