From 86a54a4802df10d23ccd655e2083e812fe990243 Mon Sep 17 00:00:00 2001 From: Jonathan Brassow Date: Thu, 13 Jan 2011 19:59:52 +0000 Subject: dm log userspace: add version number to comms This patch adds a 'version' field to the 'dm_ulog_request' structure. The 'version' field is taken from a portion of the unused 'padding' field in the 'dm_ulog_request' structure. This was done to avoid changing the size of the structure and possibly disrupting backwards compatibility. The version number will help notify user-space daemons when a change has been made to the kernel/userspace log API. Signed-off-by: Jonathan Brassow Signed-off-by: Mike Snitzer Signed-off-by: Alasdair G Kergon --- include/linux/dm-log-userspace.h | 13 ++++++++++++- 1 file changed, 12 insertions(+), 1 deletion(-) (limited to 'include') diff --git a/include/linux/dm-log-userspace.h b/include/linux/dm-log-userspace.h index 0c3c3a2110c4..eeace7d3ff15 100644 --- a/include/linux/dm-log-userspace.h +++ b/include/linux/dm-log-userspace.h @@ -370,6 +370,16 @@ #define DM_ULOG_REQUEST_TYPE(request_type) \ (DM_ULOG_REQUEST_MASK & (request_type)) +/* + * DM_ULOG_REQUEST_VERSION is incremented when there is a + * change to the way information is passed between kernel + * and userspace. This could be a structure change of + * dm_ulog_request or a change in the way requests are + * issued/handled. Changes are outlined here: + * version 1: Initial implementation + */ +#define DM_ULOG_REQUEST_VERSION 1 + struct dm_ulog_request { /* * The local unique identifier (luid) and the universally unique @@ -383,8 +393,9 @@ struct dm_ulog_request { */ uint64_t luid; char uuid[DM_UUID_LEN]; - char padding[7]; /* Padding because DM_UUID_LEN = 129 */ + char padding[3]; /* Padding because DM_UUID_LEN = 129 */ + uint32_t version; /* See DM_ULOG_REQUEST_VERSION */ int32_t error; /* Used to report back processing errors */ uint32_t seq; /* Sequence number for request */ -- cgit v1.2.3