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[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] [Xen-devel] [PATCH 02 of 13 v5] blktap3/libblktapctl: Introduce tapdisk message types and structures
This patch introduces function prototypes and structures that are implemented
by libblktapctl (the library that allows libxl, tap-ctl, and the tapback daemon
to manage a running tapdisk process). This file is based on the existing
blktap2 file, with some changes coming from blktap2.5 (the STATS message,
support for mirroring).
tapdisk_message_name is now neater and uses a look up table instead of a big
switch.
blktap3 introduces the following messages:
- DISK_INFO: used by the tapback daemon to communicate to blkfront via
XenStore the number of sectors and the sector size so that it can create
the virtual block device.
- XENBLKIF_CONNECT/DISCONNECT: used by the tapback daemon to instruct a
running tapdisk process to connect to the ring. The
tapdisk_message_blkif structure is used to convey such messages.
Signed-off-by: Thanos Makatos <thanos.makatos@xxxxxxxxxx>
---
Changed since v2:
* Include TAPDISK_MESSAGE_MAX in the enum.
* Updated comment regarding the proto member in struct tapdisk_message
blkif.
* Rearranged enum tapdisk_message_id in such a way that messages requiring a
response belong to a "group". Introduce self-explanatory function
tapdisk_message_is_rsp_paired.
Changed since v3:
* Use the correct name for the back-end daemon in the description of this
patch (tapback instead of the obsolete xenio).
* Removed erroneous statement in the patch description stating that
attach/detach is obsolete.
Changed since v4:
* Remove the minor numbers from struct tapdisk_message_params and
tapdisk_message_list.
* Add the VDI type:/path/to/file into struct tapdisk_message_blkif as this is
what uniquely identifies a VBD now that the minor number has been removed.
* Remove the cookie from struct tapdisk_message as it was used for storing
the minor number, which has been removed.
* Remove attach/detach messages.
diff --git a/tools/blktap2/include/tapdisk-message.h
b/tools/blktap3/include/tapdisk-message.h
copy from tools/blktap2/include/tapdisk-message.h
copy to tools/blktap3/include/tapdisk-message.h
--- a/tools/blktap2/include/tapdisk-message.h
+++ b/tools/blktap3/include/tapdisk-message.h
@@ -36,29 +36,33 @@
#define TAPDISK_MESSAGE_MAX_MINORS \
((TAPDISK_MESSAGE_MAX_PATH_LENGTH / sizeof(int)) - 1)
-#define TAPDISK_MESSAGE_FLAG_SHARED 0x01
-#define TAPDISK_MESSAGE_FLAG_RDONLY 0x02
-#define TAPDISK_MESSAGE_FLAG_ADD_CACHE 0x04
-#define TAPDISK_MESSAGE_FLAG_VHD_INDEX 0x08
-#define TAPDISK_MESSAGE_FLAG_LOG_DIRTY 0x10
+#define TAPDISK_MESSAGE_FLAG_SHARED 0x001
+#define TAPDISK_MESSAGE_FLAG_RDONLY 0x002
+#define TAPDISK_MESSAGE_FLAG_ADD_CACHE 0x004
+#define TAPDISK_MESSAGE_FLAG_VHD_INDEX 0x008
+#define TAPDISK_MESSAGE_FLAG_LOG_DIRTY 0x010
+#define TAPDISK_MESSAGE_FLAG_ADD_LCACHE 0x020
+#define TAPDISK_MESSAGE_FLAG_REUSE_PRT 0x040
+#define TAPDISK_MESSAGE_FLAG_SECONDARY 0x080
+#define TAPDISK_MESSAGE_FLAG_STANDBY 0x100
typedef struct tapdisk_message tapdisk_message_t;
-typedef uint8_t tapdisk_message_flag_t;
+typedef uint32_t tapdisk_message_flag_t;
typedef struct tapdisk_message_image tapdisk_message_image_t;
typedef struct tapdisk_message_params tapdisk_message_params_t;
typedef struct tapdisk_message_string tapdisk_message_string_t;
typedef struct tapdisk_message_response tapdisk_message_response_t;
typedef struct tapdisk_message_minors tapdisk_message_minors_t;
typedef struct tapdisk_message_list tapdisk_message_list_t;
+typedef struct tapdisk_message_stat tapdisk_message_stat_t;
+typedef struct tapdisk_message_blkif tapdisk_message_blkif_t;
struct tapdisk_message_params {
tapdisk_message_flag_t flags;
-
- uint8_t storage;
- uint32_t devnum;
uint32_t domid;
- uint16_t path_len;
char path[TAPDISK_MESSAGE_MAX_PATH_LENGTH];
+ char
prt_path[TAPDISK_MESSAGE_MAX_PATH_LENGTH];
+ char
secondary[TAPDISK_MESSAGE_MAX_PATH_LENGTH];
};
struct tapdisk_message_image {
@@ -83,14 +87,69 @@ struct tapdisk_message_minors {
struct tapdisk_message_list {
int count;
- int minor;
int state;
char path[TAPDISK_MESSAGE_MAX_PATH_LENGTH];
};
+struct tapdisk_message_stat {
+ uint16_t type;
+ uint16_t cookie;
+ size_t length;
+};
+
+/**
+ * Tapdisk message containing all the necessary information required for the
+ * tapdisk to connect to a guest's blkfront.
+ */
+struct tapdisk_message_blkif {
+ /**
+ * The domain ID of the guest to connect to.
+ */
+ uint32_t domid;
+
+ /**
+ * The device ID of the virtual block device.
+ */
+ uint32_t devid;
+
+ /**
+ * Grant references for the shared ring.
+ * TODO Why 8 specifically?
+ */
+ uint32_t gref[8];
+
+ /**
+ * Number of pages in the ring, expressed as a page order.
+ */
+ uint32_t order;
+
+ /**
+ * Protocol to use: native, 32 bit, or 64 bit. Used for supporting a
+ * 32-bit domU talking to a 64-bit dom0/domU and vice versa.
+ */
+ uint32_t proto;
+
+ /**
+ * TODO Page pool? Can be NULL.
+ */
+ char pool[TAPDISK_MESSAGE_STRING_LENGTH];
+
+ /**
+ * The event channel port.
+ */
+ uint32_t port;
+
+ /**
+ * type:/path/to/file
+ */
+ char params[TAPDISK_MESSAGE_MAX_PATH_LENGTH];
+};
+
struct tapdisk_message {
+ /**
+ * TAPDISK_MESSAGE_???
+ */
uint16_t type;
- uint16_t cookie;
union {
pid_t tapdisk_pid;
@@ -100,16 +159,31 @@ struct tapdisk_message {
tapdisk_message_minors_t minors;
tapdisk_message_response_t response;
tapdisk_message_list_t list;
+ tapdisk_message_stat_t info;
+ tapdisk_message_blkif_t blkif;
} u;
};
-enum tapdisk_message_id {
+/**
+ * Messages that are paired with a response (e.g. TAPDISK_MESSAGE_FOO goes
+ * hand in hand with message TAPDISK_MESSAGE_FOO_RSP) should be placed within
+ * a contiguous range in the enum in order to be able to easily identify
+ * whether a given message requires a response. Also, a message's response
+ * must follow the message in the enum so that their values differ by 1.
+ */
+typedef enum tapdisk_message_id {
+ /*
+ * TODO Why start from 1 and not from 0?
+ */
TAPDISK_MESSAGE_ERROR = 1,
TAPDISK_MESSAGE_RUNTIME_ERROR,
- TAPDISK_MESSAGE_PID,
+
+ /*
+ * Begin of messages paired with a response.
+ */
+ TAPDISK_MESSAGE_REQS_RSP_START, /* not an actual message */
+ TAPDISK_MESSAGE_PID = TAPDISK_MESSAGE_REQS_RSP_START,
TAPDISK_MESSAGE_PID_RSP,
- TAPDISK_MESSAGE_ATTACH,
- TAPDISK_MESSAGE_ATTACH_RSP,
TAPDISK_MESSAGE_OPEN,
TAPDISK_MESSAGE_OPEN_RSP,
TAPDISK_MESSAGE_PAUSE,
@@ -118,86 +192,90 @@ enum tapdisk_message_id {
TAPDISK_MESSAGE_RESUME_RSP,
TAPDISK_MESSAGE_CLOSE,
TAPDISK_MESSAGE_CLOSE_RSP,
- TAPDISK_MESSAGE_DETACH,
- TAPDISK_MESSAGE_DETACH_RSP,
- TAPDISK_MESSAGE_LIST_MINORS,
- TAPDISK_MESSAGE_LIST_MINORS_RSP,
+ TAPDISK_MESSAGE_LIST_MINORS, /* TODO still valid? */
+ TAPDISK_MESSAGE_LIST_MINORS_RSP, /* TODO still valid? */
TAPDISK_MESSAGE_LIST,
TAPDISK_MESSAGE_LIST_RSP,
+ TAPDISK_MESSAGE_STATS,
+ TAPDISK_MESSAGE_STATS_RSP,
+ TAPDISK_MESSAGE_DISK_INFO,
+ TAPDISK_MESSAGE_DISK_INFO_RSP,
+ TAPDISK_MESSAGE_XENBLKIF_CONNECT,
+ TAPDISK_MESSAGE_XENBLKIF_CONNECT_RSP,
+ TAPDISK_MESSAGE_XENBLKIF_DISCONNECT,
+ TAPDISK_MESSAGE_XENBLKIF_DISCONNECT_RSP,
+ TAPDISK_MESSAGE_REQS_RSP_END = TAPDISK_MESSAGE_XENBLKIF_DISCONNECT_RSP,
+ /*
+ * End of messages requiring a response.
+ */
+
TAPDISK_MESSAGE_FORCE_SHUTDOWN,
TAPDISK_MESSAGE_EXIT,
-};
+ TAPDISK_MESSAGE_MAX
+} td_msg_id_t;
-static inline char *
-tapdisk_message_name(enum tapdisk_message_id id)
-{
- switch (id) {
- case TAPDISK_MESSAGE_ERROR:
- return "error";
+/**
+ * Tells whether a request message is paired with a reply message or vice
+ * versa.
+ *
+ * @param id the message ID
+ * @returns 1 if the request message is paired with a response (or vice versa),
+ * 0 otherwise
+ */
+static inline int tapdisk_message_is_rsp_paired(const td_msg_id_t id) {
+ return id >= TAPDISK_MESSAGE_REQS_RSP_START
+ && id <= TAPDISK_MESSAGE_REQS_RSP_END;
+}
- case TAPDISK_MESSAGE_PID:
- return "pid";
+/**
+ * Retrieves a message's human-readable representation.
+ *
+ * @param id the message ID to translate
+ * @return the name of the message
+ *
+ * @note If the message type is unknown the function simply returns 'unknown',
+ * so the information regarding the erroneous message type is lost. We could
+ * include the number of the message in the returned string but we would then
+ * have to allocate it, forcing the user to release each string this function
+ * would return, something that users of this function would probably forget
+ * to do.
+ */
+static inline char const *
+tapdisk_message_name(const td_msg_id_t id) {
+ static char const *msg_names[TAPDISK_MESSAGE_MAX] = {
+ [TAPDISK_MESSAGE_ERROR] = "error",
+ [TAPDISK_MESSAGE_RUNTIME_ERROR] = "runtime error",
+ [TAPDISK_MESSAGE_PID] = "pid",
+ [TAPDISK_MESSAGE_PID_RSP] = "pid response",
+ [TAPDISK_MESSAGE_OPEN] = "open",
+ [TAPDISK_MESSAGE_OPEN_RSP] = "open response",
+ [TAPDISK_MESSAGE_PAUSE] = "pause",
+ [TAPDISK_MESSAGE_PAUSE_RSP] = "pause response",
+ [TAPDISK_MESSAGE_RESUME] = "resume",
+ [TAPDISK_MESSAGE_RESUME_RSP] = "resume response",
+ [TAPDISK_MESSAGE_CLOSE] = "close",
+ [TAPDISK_MESSAGE_FORCE_SHUTDOWN] = "force shutdown",
+ [TAPDISK_MESSAGE_CLOSE_RSP] = "close response",
+ [TAPDISK_MESSAGE_LIST_MINORS] = "list minors",
+ [TAPDISK_MESSAGE_LIST_MINORS_RSP] = "list minors response",
+ [TAPDISK_MESSAGE_LIST] = "list",
+ [TAPDISK_MESSAGE_LIST_RSP] = "list response",
+ [TAPDISK_MESSAGE_STATS] = "stats",
+ [TAPDISK_MESSAGE_STATS_RSP] = "stats response",
+ [TAPDISK_MESSAGE_DISK_INFO] = "disk info",
+ [TAPDISK_MESSAGE_DISK_INFO_RSP] = "disk info response",
+ [TAPDISK_MESSAGE_XENBLKIF_CONNECT] = "blkif connect",
+ [TAPDISK_MESSAGE_XENBLKIF_CONNECT_RSP] = "blkif connect
response",
+ [TAPDISK_MESSAGE_XENBLKIF_DISCONNECT] = "blkif disconnect",
+ [TAPDISK_MESSAGE_XENBLKIF_DISCONNECT_RSP]
+ = "blkif disconnect response",
+ [TAPDISK_MESSAGE_EXIT] = "exit"
+ };
- case TAPDISK_MESSAGE_PID_RSP:
- return "pid response";
-
- case TAPDISK_MESSAGE_OPEN:
- return "open";
-
- case TAPDISK_MESSAGE_OPEN_RSP:
- return "open response";
-
- case TAPDISK_MESSAGE_PAUSE:
- return "pause";
-
- case TAPDISK_MESSAGE_PAUSE_RSP:
- return "pause response";
-
- case TAPDISK_MESSAGE_RESUME:
- return "resume";
-
- case TAPDISK_MESSAGE_RESUME_RSP:
- return "resume response";
-
- case TAPDISK_MESSAGE_CLOSE:
- return "close";
-
- case TAPDISK_MESSAGE_FORCE_SHUTDOWN:
- return "force shutdown";
-
- case TAPDISK_MESSAGE_CLOSE_RSP:
- return "close response";
-
- case TAPDISK_MESSAGE_ATTACH:
- return "attach";
-
- case TAPDISK_MESSAGE_ATTACH_RSP:
- return "attach response";
-
- case TAPDISK_MESSAGE_DETACH:
- return "detach";
-
- case TAPDISK_MESSAGE_DETACH_RSP:
- return "detach response";
-
- case TAPDISK_MESSAGE_LIST_MINORS:
- return "list minors";
-
- case TAPDISK_MESSAGE_LIST_MINORS_RSP:
- return "list minors response";
-
- case TAPDISK_MESSAGE_LIST:
- return "list";
-
- case TAPDISK_MESSAGE_LIST_RSP:
- return "list response";
-
- case TAPDISK_MESSAGE_EXIT:
- return "exit";
-
- default:
+ if (id < 1 || id >= TAPDISK_MESSAGE_MAX) {
return "unknown";
}
+ return msg_names[id];
}
-#endif
+#endif /* _TAPDISK_MESSAGE_H_ */
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