VFS FIFO: Add "fifo" KDL command

Prints information about a FIFO node and, optionally, its data buffer
content.

* Reorganized the FS interface a little:
- Moved most file_system_module_info hooks into separate structures.
Those that operate on mounted volumes to fs_volume_ops, those
operating on a vnode to fs_vnode_ops.
- Got rid of the fs_volume, fs_cookie, fs_vnode typedefs. We use void*
again.
- Instead of a void* volume and node cookie hooks are passed a
fs_volume and fs_vnode structure pointer, which contain the cookie
and an ops pointer (fs_volume a few more things).
- The VFS {new,publish,get,...}_vnode() functions take a fs_volume*
instead of the volume ID. So does vfs_get_fs_node_from_path().
- Added type and flags arguments to publish_vnode() and the
get_vnode() hook and removed the type argument from lookup() hook.
Added vnode::type using formerly unused bits to store the node type.
Simplified a few things in the VFS due to the now always available
node type.
- Added fs_volume_ops::{create,delete}_sub_vnode() and
fs_vnode_ops::get_super_vnode() hooks. They are used to support file
system layers, e.g. allowing to extend an FS not supporting BeOS
attribute with attribute support. Needs some more work in the VFS.
- Added fs_vnode_ops::create_special_node() hook for creating special
nodes (e.g. FIFOs).
* Adjusted the built-in file systems and BFS according to the interface
changes. Removed all other FSs from the image for the time being.
We'll see whether further API changes are necessary before porting
them.
* Adjusted the bfs_shell accordingly.
* Implemented create_special_node() in rootfs to support special nodes.
* Added support for FIFOs:
- Added syscall _kern_create_fifo() (used by mkfifo()), which creates
a special node (type S_IFIFO) in the respective file system.
- When a special node is published the VFS creates a respective sub
node. Currently only FIFOs are supported.
- Added a little support for FIFO subnodes by using functionality from
the pipefs.
- Added mkfifo to the image. It can create FIFOs in the rootfs, but
the FIFOs aren't really usable ATM, since they still work like
pipes, i.e. readers and writers need to have them open at the same
time.
* Some smaller changes in the VFS:
- Made the *_CALL macros nicer to use (vargs).
- Refactored FS entry lookup into new function lookup_dir_entry().
- create_vnode() no longer just calls the FS create() hook. First it
looks up the entry and uses open_vnode(), if it already exists. This
is necessary for two reasons: 1) The FS might not support create()
while still allowing to open() entries. 2) When the FS has other
layers on to of it (or the respective node) it might not be
responsible for opening the node.


git-svn-id: file:///srv/svn/repos/haiku/haiku/trunk@24816 a95241bf-73f2-0310-859d-f6bbb57e9c96

VFS FIFO: Add "fifo" KDL command

Prints information about a FIFO node and, optionally, its data buffer
content.

* Reorganized the FS interface a little:
- Moved most file_system_module_info hooks into separate structures.
Those that operate on mounted volumes to fs_volume_ops, those
operating on a vnode to fs_vnode_ops.
- Got rid of the fs_volume, fs_cookie, fs_vnode typedefs. We use void*
again.
- Instead of a void* volume and node cookie hooks are passed a
fs_volume and fs_vnode structure pointer, which contain the cookie
and an ops pointer (fs_volume a few more things).
- The VFS {new,publish,get,...}_vnode() functions take a fs_volume*
instead of the volume ID. So does vfs_get_fs_node_from_path().
- Added type and flags arguments to publish_vnode() and the
get_vnode() hook and removed the type argument from lookup() hook.
Added vnode::type using formerly unused bits to store the node type.
Simplified a few things in the VFS due to the now always available
node type.
- Added fs_volume_ops::{create,delete}_sub_vnode() and
fs_vnode_ops::get_super_vnode() hooks. They are used to support file
system layers, e.g. allowing to extend an FS not supporting BeOS
attribute with attribute support. Needs some more work in the VFS.
- Added fs_vnode_ops::create_special_node() hook for creating special
nodes (e.g. FIFOs).
* Adjusted the built-in file systems and BFS according to the interface
changes. Removed all other FSs from the image for the time being.
We'll see whether further API changes are necessary before porting
them.
* Adjusted the bfs_shell accordingly.
* Implemented create_special_node() in rootfs to support special nodes.
* Added support for FIFOs:
- Added syscall _kern_create_fifo() (used by mkfifo()), which creates
a special node (type S_IFIFO) in the respective file system.
- When a special node is published the VFS creates a respective sub
node. Currently only FIFOs are supported.
- Added a little support for FIFO subnodes by using functionality from
the pipefs.
- Added mkfifo to the image. It can create FIFOs in the rootfs, but
the FIFOs aren't really usable ATM, since they still work like
pipes, i.e. readers and writers need to have them open at the same
time.
* Some smaller changes in the VFS:
- Made the *_CALL macros nicer to use (vargs).
- Refactored FS entry lookup into new function lookup_dir_entry().
- create_vnode() no longer just calls the FS create() hook. First it
looks up the entry and uses open_vnode(), if it already exists. This
is necessary for two reasons: 1) The FS might not support create()
while still allowing to open() entries. 2) When the FS has other
layers on to of it (or the respective node) it might not be
responsible for opening the node.


git-svn-id: file:///srv/svn/repos/haiku/haiku/trunk@24816 a95241bf-73f2-0310-859d-f6bbb57e9c96