[RFC PATCH v2 1/4] md: add uapi definitions for the md control device

[Abd-Alrhman Masalkhi]

Add the ioctl commands and structures for /dev/md-control, a misc device
that manages md arrays without opening the md block device. The device
itself is added in the next patch.

Every command except MD_RAID_VERSION takes a struct mdu_ioctl, which
names the array by name, UUID or device number, carries a flags field,
and points to the command's payload. The commands mirror the existing
block device ioctls and use the MD_MAJOR ioctl type, with numbers
starting at 0x40, grouped like the old ones: status at 0x40,
configuration at 0x50 and usage at 0x60.

The payload structures are new versions of the old ones with fixed-size
types and explicit padding, so they have the same layout on 32-bit and
64-bit systems. Fields that overflow in the old structures are 64-bit
now: size, ctime and utime in struct mdu_array_info64.
struct mdu_array_info64 also reports the number of journal disks.

STOP_ARRAY_RO has no separate command: MD_STOP_ARRAY with MD_RO_FLAG
set switches the array to read-only mode instead of stopping it.

Signed-off-by: Abd-Alrhman Masalkhi <abd.masalkhi@xxxxxxxxx>
---
 include/uapi/linux/raid/md_u.h | 119 +++++++++++++++++++++++++++++++++
 1 file changed, 119 insertions(+)

diff --git a/include/uapi/linux/raid/md_u.h b/include/uapi/linux/raid/md_u.h
index a893010735fb..adc62b5e50ec 100644
--- a/include/uapi/linux/raid/md_u.h
+++ b/include/uapi/linux/raid/md_u.h
@@ -12,6 +12,8 @@
 #ifndef _UAPI_MD_U_H
 #define _UAPI_MD_U_H
 
+#include <linux/types.h>
+
 /*
  * Different major versions are not compatible.
  * Different minor versions are only downward compatible.
@@ -30,6 +32,10 @@
  */
 #define MD_PATCHLEVEL_VERSION           3
 
+#define MD_NAME_LEN                     32
+#define MD_UUID_LEN                     16
+#define MD_CTL_NODE                     "md-control"
+
 /* ioctls */
 
 /* status */
@@ -61,6 +67,29 @@
 #define RESTART_ARRAY_RW	_IO (MD_MAJOR, 0x34)
 #define CLUSTERED_DISK_NACK	_IO (MD_MAJOR, 0x35)
 
+/* ioctl commands for the MD misc control driver */
+/* status */
+#define MD_RAID_VERSION		_IOR(MD_MAJOR, 0x40, struct mdu_version64)
+#define MD_GET_ARRAY_INFO	_IOWR(MD_MAJOR, 0x41, struct mdu_ioctl)
+#define MD_GET_DISK_INFO	_IOWR(MD_MAJOR, 0x42, struct mdu_ioctl)
+#define MD_RAID_AUTORUN		_IOWR(MD_MAJOR, 0x43, struct mdu_ioctl)
+#define MD_GET_BITMAP_FILE	_IOWR(MD_MAJOR, 0x44, struct mdu_ioctl)
+
+/* configuration */
+#define MD_ADD_NEW_DISK		_IOWR(MD_MAJOR, 0x50, struct mdu_ioctl)
+#define MD_HOT_ADD_DISK		_IOWR(MD_MAJOR, 0x51, struct mdu_ioctl)
+#define MD_HOT_REMOVE_DISK	_IOWR(MD_MAJOR, 0x52, struct mdu_ioctl)
+#define MD_SET_ARRAY_INFO	_IOWR(MD_MAJOR, 0x53, struct mdu_ioctl)
+#define MD_SET_DISK_INFO	_IOWR(MD_MAJOR, 0x54, struct mdu_ioctl)
+#define MD_SET_DISK_FAULTY	_IOWR(MD_MAJOR, 0x55, struct mdu_ioctl)
+#define MD_SET_BITMAP_FILE	_IOWR(MD_MAJOR, 0x56, struct mdu_ioctl)
+
+/* usage */
+#define MD_RUN_ARRAY		_IOWR(MD_MAJOR, 0x60, struct mdu_ioctl)
+#define MD_STOP_ARRAY		_IOWR(MD_MAJOR, 0x61, struct mdu_ioctl)
+#define MD_RESTART_ARRAY_RW	_IOWR(MD_MAJOR, 0x62, struct mdu_ioctl)
+#define MD_CLUSTERED_DISK_NACK	_IOWR(MD_MAJOR, 0x63, struct mdu_ioctl)
+
 /* 63 partitions with the alternate major number (mdp) */
 #define MdpMinorShift 6
 
@@ -146,4 +175,94 @@ typedef struct mdu_param_s
 	int			max_fault;	/* unused for now */
 } mdu_param_t;
 
+/* structures for the MD misc control driver */
+struct mdu_version64 {
+	__u32 major;
+	__u32 minor;
+	__u32 patchlevel;
+	__u32 padding;
+};
+
+struct mdu_array_info64 {
+	/*
+	 * Generic constant information
+	 */
+	__u32 major_version;
+	__u32 minor_version;
+	__u32 patch_version;
+	__s32 level;
+
+	__u64 ctime;
+	__s64 size;
+
+	__u32 nr_disks;
+	__u32 raid_disks;
+	__u32 md_minor;
+	__u32 not_persistent;
+
+	/*
+	 * Generic state information
+	 */
+	__u64 utime;		/*  0 Superblock update time		      */
+
+	__u32 state;		/*  1 State bits (clean, ...)		      */
+	__u32 active_disks;	/*  2 Number of currently active disks	      */
+	__u32 working_disks;	/*  3 Number of working disks		      */
+	__u32 failed_disks;	/*  4 Number of failed disks		      */
+	__u32 spare_disks;	/*  5 Number of spare disks		      */
+	__u32 journal_disks;    /*  6 Number of disks used for journaling     */
+
+	/*
+	 * Personality information
+	 */
+	__s32 layout;		/*  0 the array's physical layout	      */
+	__u32 chunk_size;	/*  1 chunk size in bytes		      */
+
+};
+
+struct mdu_disk_info64 {
+	/*
+	 * configuration/status of one particular disk
+	 */
+	__u32 state;
+	__u32 major;
+	__u32 minor;
+	__u32 padding;
+
+	__s32 number;
+	__s32 raid_disk;
+};
+
+struct mdu_bitmap_file64 {
+	char pathname[4096];
+};
+
+struct mdu_param64 {
+	__s32 personality;	/* 1,2,3,4 */
+	__u32 max_fault;	/* unused for now */
+	__u32 chunk_size;	/* in bytes */
+	__u32 padding;
+};
+
+struct mdu_ioctl {
+	char name[MD_NAME_LEN];
+	char uuid[MD_UUID_LEN];
+	__u64 dev;
+	__u32 flags;
+	__u32 padding;
+	union {
+		__u64 array;
+		__u64 disk;
+		__u64 param;
+		__u64 bitmap_file;
+		__u64 arg;
+	};
+};
+
+/*
+ * If set, MD_STOP_ARRAY will switch the array to read-only mode instead
+ * of fully stopping it.
+ */
+#define MD_RO_FLAG              (1u << 0)
+
 #endif /* _UAPI_MD_U_H */
-- 
2.43.0