path: root/drivers/md/dm-log-userspace-transfer.h
diff options
authorJonthan Brassow <jbrassow@redhat.com>2009-06-22 10:12:35 +0100
committerAlasdair G Kergon <agk@redhat.com>2009-06-22 10:12:35 +0100
commitf5db4af466e2dca0fe822019812d586ca910b00c (patch)
tree1bbaaa36509df9f7eecc19ccffa434048cf4b555 /drivers/md/dm-log-userspace-transfer.h
parent754c5fc7ebb417b23601a6222a6005cc2e7f2913 (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 'drivers/md/dm-log-userspace-transfer.h')
1 files changed, 18 insertions, 0 deletions
diff --git a/drivers/md/dm-log-userspace-transfer.h b/drivers/md/dm-log-userspace-transfer.h
new file mode 100644
index 00000000000..c26d8e4e271
--- /dev/null
+++ b/drivers/md/dm-log-userspace-transfer.h
@@ -0,0 +1,18 @@
+ * Copyright (C) 2006-2009 Red Hat, Inc.
+ *
+ * This file is released under the LGPL.
+ */
+#define DM_MSG_PREFIX "dm-log-userspace"
+int dm_ulog_tfr_init(void);
+void dm_ulog_tfr_exit(void);
+int dm_consult_userspace(const char *uuid, int request_type,
+ char *data, size_t data_size,
+ char *rdata, size_t *rdata_size);