dm ioctl: allow message to return data

This patch introduces enhanced message support that allows the device-mapper core to recognise messages that are common to all devices, and for messages to return data to userspace. Core messages are processed by the function "message_for_md". If the device mapper doesn't support the message, it is passed to the target driver. If the message returns data, the kernel sets the flag DM_MESSAGE_OUT_FLAG.

Mikulas Patocka committed 13 years ago

Commit a2606241 parent 02cde502 files · +40 −1Browse files

Showing the changes to include/uapi (1 of 2 files). Show all

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include/uapi/linux/dm-ioctl.h+5−0

@@ -336,4 +336,9 @@ enum { · 335 unmodified lines
336	336	*/
337	337	#define DM_SECURE_DATA_FLAG (1 << 15) /* In */
338	338
	339	+/*
	340	+ * If set, a message generated output data.
	341	+ */
	342	+#define DM_DATA_OUT_FLAG (1 << 16) /* Out */
	343	+
339	344	#endif /* _LINUX_DM_IOCTL_H */