diff options
| author | Jonthan Brassow <jbrassow@redhat.com> | 2009-06-22 10:12:35 +0100 |
|---|---|---|
| committer | Alasdair G Kergon <agk@redhat.com> | 2009-06-22 10:12:35 +0100 |
| commit | f5db4af466e2dca0fe822019812d586ca910b00c (patch) | |
| tree | 1bbaaa36509df9f7eecc19ccffa434048cf4b555 /include/linux/connector.h | |
| parent | 754c5fc7ebb417b23601a6222a6005cc2e7f2913 (diff) | |
dm raid1: add userspace log
This patch contains a device-mapper mirror log module that forwards
requests to userspace for processing.
The structures used for communication between kernel and userspace are
located in include/linux/dm-log-userspace.h. Due to the frequency,
diversity, and 2-way communication nature of the exchanges between
kernel and userspace, 'connector' was chosen as the interface for
communication.
The first log implementations written in userspace - "clustered-disk"
and "clustered-core" - support clustered shared storage. A userspace
daemon (in the LVM2 source code repository) uses openAIS/corosync to
process requests in an ordered fashion with the rest of the nodes in the
cluster so as to prevent log state corruption. Other implementations
with no association to LVM or openAIS/corosync, are certainly possible.
(Imagine if two machines are writing to the same region of a mirror.
They would both mark the region dirty, but you need a cluster-aware
entity that can handle properly marking the region clean when they are
done. Otherwise, you might clear the region when the first machine is
done, not the second.)
Signed-off-by: Jonathan Brassow <jbrassow@redhat.com>
Cc: Evgeniy Polyakov <johnpol@2ka.mipt.ru>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
Diffstat (limited to 'include/linux/connector.h')
| -rw-r--r-- | include/linux/connector.h | 4 |
1 files changed, 3 insertions, 1 deletions
diff --git a/include/linux/connector.h b/include/linux/connector.h index b9966e64604e..b68d27850d51 100644 --- a/include/linux/connector.h +++ b/include/linux/connector.h @@ -41,8 +41,10 @@ #define CN_IDX_BB 0x5 /* BlackBoard, from the TSP GPL sampling framework */ #define CN_DST_IDX 0x6 #define CN_DST_VAL 0x1 +#define CN_IDX_DM 0x7 /* Device Mapper */ +#define CN_VAL_DM_USERSPACE_LOG 0x1 -#define CN_NETLINK_USERS 7 +#define CN_NETLINK_USERS 8 /* * Maximum connector's message size. |