cachefiles,netfs: sunset ondemand mode

It was an effort to enhance fscache as a kernel cache for lazy
pulling (at least according to previous Incremental FS discussion [1])
and EROFS over fscache was the in-tree user of this mode.

fscache has since evolved to be netfslib-oriented, serving network
filesystem inodes via the netfs library, but EROFS never acts as a
network filesystem and we need to cache golden filesystem images rather
than individual EROFS inodes.

Since EROFS over fscache is now removed, clean up netfs/fscache/
cachefiles upstream too.

[1] https://lore.kernel.org/r/CAOQ4uxi4dzxArY24YO=+kBCK2gGoq3Ptb8WkzCqSogPgU_R3dQ@mail.gmail.com

[dh] Fixed up comments on:
https://sashiko.dev/#/patchset/20260716103030.3065561-1-dhowells%40redhat.com
https://sashiko.dev/#/patchset/20260722130218.78958-1-dhowells%40redhat.com

Signed-off-by: Gao Xiang <xiang@kernel.org>
Signed-off-by: David Howells <dhowells@redhat.com>
Link: https://patch.msgid.link/1046393.1786544127@warthog.procyon.org.uk
cc: Paulo Alcantara <pc@manguebit.org>
cc: netfs@lists.linux.dev
cc: linux-erofs@lists.ozlabs.org
cc: bpf@vger.kernel.org
cc: linux-fsdevel@vger.kernel.org
Signed-off-by: Christian Brauner (Amutable) <brauner@kernel.org>

1 files changed, 0 insertions, 68 deletions

diff --git a/include/uapi/linux/cachefiles.h b/include/uapi/linux/cachefiles.h
deleted file mode 100644
index 78caa73e5343..000000000000
--- a/include/uapi/linux/cachefiles.h
+++ /dev/null
@@ -1,68 +0,0 @@
-/* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */
-#ifndef _LINUX_CACHEFILES_H
-#define _LINUX_CACHEFILES_H
-
-#include <linux/types.h>
-#include <linux/ioctl.h>
-
-/*
- * Fscache ensures that the maximum length of cookie key is 255. The volume key
- * is controlled by netfs, and generally no bigger than 255.
- */
-#define CACHEFILES_MSG_MAX_SIZE	1024
-
-enum cachefiles_opcode {
-	CACHEFILES_OP_OPEN,
-	CACHEFILES_OP_CLOSE,
-	CACHEFILES_OP_READ,
-};
-
-/*
- * Message Header
- *
- * @msg_id	a unique ID identifying this message
- * @opcode	message type, CACHEFILE_OP_*
- * @len		message length, including message header and following data
- * @object_id	a unique ID identifying a cache file
- * @data	message type specific payload
- */
-struct cachefiles_msg {
-	__u32 msg_id;
-	__u32 opcode;
-	__u32 len;
-	__u32 object_id;
-	__u8  data[];
-};
-
-/*
- * @data contains the volume_key followed directly by the cookie_key. volume_key
- * is a NUL-terminated string; @volume_key_size indicates the size of the volume
- * key in bytes. cookie_key is binary data, which is netfs specific;
- * @cookie_key_size indicates the size of the cookie key in bytes.
- *
- * @fd identifies an anon_fd referring to the cache file.
- */
-struct cachefiles_open {
-	__u32 volume_key_size;
-	__u32 cookie_key_size;
-	__u32 fd;
-	__u32 flags;
-	__u8  data[];
-};
-
-/*
- * @off		indicates the starting offset of the requested file range
- * @len		indicates the length of the requested file range
- */
-struct cachefiles_read {
-	__u64 off;
-	__u64 len;
-};
-
-/*
- * Reply for READ request
- * @arg for this ioctl is the @id field of READ request.
- */
-#define CACHEFILES_IOC_READ_COMPLETE	_IOW(0x98, 1, int)
-
-#endif