From: Palmer Dabbelt palmerdabbelt@google.com
dm-user is a device mapper target that allows a userspace process to handle each incoming BIO. Communication with userspace consists of a stream of messages proxied over a misc device, the structure of each message is defined in this header.
Signed-off-by: Palmer Dabbelt palmerdabbelt@google.com
---
As it currently stands this isn't really sufficient to be a stable user ABI. These are probably best discussed in the context of the dm-user implementation, though, where they're largely called out as FIXMEs. --- include/uapi/linux/dm-user.h | 67 ++++++++++++++++++++++++++++++++++++ 1 file changed, 67 insertions(+) create mode 100644 include/uapi/linux/dm-user.h
diff --git a/include/uapi/linux/dm-user.h b/include/uapi/linux/dm-user.h new file mode 100644 index 000000000000..1806109518f4 --- /dev/null +++ b/include/uapi/linux/dm-user.h @@ -0,0 +1,67 @@ +/* SPDX-License-Identifier: LGPL-2.0+ WITH Linux-syscall-note */ +/* + * Copyright (C) 2020 Palmer Dabbelt palmerdabbelt@google.com + */ + +#ifndef _LINUX_DM_USER_H +#define _LINUX_DM_USER_H + +#include <linux/types.h> + +/* + * dm-user proxies device mapper ops between the kernel and userspace. It's + * essentially just an RPC mechanism: all kernel calls create a request, + * userspace handles that with a response. Userspace obtains requests via + * read() and provides responses via write(). + * + * See Documentation/block/dm-user.rst for more information. + */ + +#define DM_USER_REQ_MAP_READ 0 +#define DM_USER_REQ_MAP_WRITE 1 +#define DM_USER_REQ_MAP_FLUSH 2 +#define DM_USER_REQ_MAP_DISCARD 3 +#define DM_USER_REQ_MAP_SECURE_ERASE 4 +#define DM_USER_REQ_MAP_WRITE_SAME 5 +#define DM_USER_REQ_MAP_WRITE_ZEROES 6 +#define DM_USER_REQ_MAP_ZONE_OPEN 7 +#define DM_USER_REQ_MAP_ZONE_CLOSE 8 +#define DM_USER_REQ_MAP_ZONE_FINISH 9 +#define DM_USER_REQ_MAP_ZONE_APPEND 10 +#define DM_USER_REQ_MAP_ZONE_RESET 11 +#define DM_USER_REQ_MAP_ZONE_RESET_ALL 12 + +#define DM_USER_REQ_MAP_FLAG_FAILFAST_DEV 0x00001 +#define DM_USER_REQ_MAP_FLAG_FAILFAST_TRANSPORT 0x00002 +#define DM_USER_REQ_MAP_FLAG_FAILFAST_DRIVER 0x00004 +#define DM_USER_REQ_MAP_FLAG_SYNC 0x00008 +#define DM_USER_REQ_MAP_FLAG_META 0x00010 +#define DM_USER_REQ_MAP_FLAG_PRIO 0x00020 +#define DM_USER_REQ_MAP_FLAG_NOMERGE 0x00040 +#define DM_USER_REQ_MAP_FLAG_IDLE 0x00080 +#define DM_USER_REQ_MAP_FLAG_INTEGRITY 0x00100 +#define DM_USER_REQ_MAP_FLAG_FUA 0x00200 +#define DM_USER_REQ_MAP_FLAG_PREFLUSH 0x00400 +#define DM_USER_REQ_MAP_FLAG_RAHEAD 0x00800 +#define DM_USER_REQ_MAP_FLAG_BACKGROUND 0x01000 +#define DM_USER_REQ_MAP_FLAG_NOWAIT 0x02000 +#define DM_USER_REQ_MAP_FLAG_CGROUP_PUNT 0x04000 +#define DM_USER_REQ_MAP_FLAG_NOUNMAP 0x08000 +#define DM_USER_REQ_MAP_FLAG_HIPRI 0x10000 +#define DM_USER_REQ_MAP_FLAG_DRV 0x20000 +#define DM_USER_REQ_MAP_FLAG_SWAP 0x40000 + +#define DM_USER_RESP_SUCCESS 0 +#define DM_USER_RESP_ERROR 1 +#define DM_USER_RESP_UNSUPPORTED 2 + +struct dm_user_message { + __u64 seq; + __u64 type; + __u64 flags; + __u64 sector; + __u64 len; + __u8 buf[]; +}; + +#endif