MFC r287621: Reimplement CTL High Availability.

CTL HA functionality was originally implemented by Copan many years ago,
but large part of the sources was never published.  This change includes
clean room implementation of the missing code and fixes for many bugs.

This code supports dual-node HA with ALUA in four modes:
 - Active/Unavailable without interlink between nodes;
 - Active/Standby with second node handling only basic LUN discovery and
reservation, synchronizing with the first node through the interlink;
 - Active/Active with both nodes processing commands and accessing the
backing storage, synchronizing with the first node through the interlink;
 - Active/Active with second node working as proxy, transfering all
commands to the first node for execution through the interlink.

Unlike original Copan's implementation, depending on specific hardware,
this code uses simple custom TCP-based protocol for interlink.  It has
no authentication, so it should never be enabled on public interfaces.

The code may still need some polishing, but generally it is functional.

Relnotes:       yes
Sponsored by:   iXsystems, Inc.

1 files changed, 33 insertions, 3 deletions

diff --git a/sys/cam/ctl/ctl_backend_ramdisk.c b/sys/cam/ctl/ctl_backend_ramdisk.c
index c39d1b6..c7e1803 100644
--- a/sys/cam/ctl/ctl_backend_ramdisk.c
+++ b/sys/cam/ctl/ctl_backend_ramdisk.c
@@ -56,14 +56,18 @@ __FBSDID("$FreeBSD$");
 #include <sys/conf.h>
 #include <sys/ioccom.h>
 #include <sys/module.h>
+#include <sys/sysctl.h>
 
 #include <cam/scsi/scsi_all.h>
+#include <cam/scsi/scsi_da.h>
 #include <cam/ctl/ctl_io.h>
 #include <cam/ctl/ctl.h>
 #include <cam/ctl/ctl_util.h>
 #include <cam/ctl/ctl_backend.h>
 #include <cam/ctl/ctl_debug.h>
 #include <cam/ctl/ctl_ioctl.h>
+#include <cam/ctl/ctl_ha.h>
+#include <cam/ctl/ctl_private.h>
 #include <cam/ctl/ctl_error.h>
 
 typedef enum {
@@ -101,6 +105,7 @@ struct ctl_be_ramdisk_softc {
 };
 
 static struct ctl_be_ramdisk_softc rd_softc;
+extern struct ctl_softc *control_softc;
 
 int ctl_backend_ramdisk_init(void);
 void ctl_backend_ramdisk_shutdown(void);
@@ -546,7 +551,13 @@ ctl_backend_ramdisk_create(struct ctl_be_ramdisk_softc *softc,
 	else
 		cbe_lun->lun_type = T_DIRECT;
 	be_lun->flags = CTL_BE_RAMDISK_LUN_UNCONFIGURED;
-	cbe_lun->flags = CTL_LUN_FLAG_PRIMARY;
+	cbe_lun->flags = 0;
+	value = ctl_get_opt(&cbe_lun->options, "ha_role");
+	if (value != NULL) {
+		if (strcmp(value, "primary") == 0)
+			cbe_lun->flags |= CTL_LUN_FLAG_PRIMARY;
+	} else if (control_softc->flags & CTL_FLAG_ACTIVE_SHELF)
+		cbe_lun->flags |= CTL_LUN_FLAG_PRIMARY;
 
 	if (cbe_lun->lun_type == T_DIRECT) {
 		if (params->blocksize_bytes != 0)
@@ -717,7 +728,9 @@ ctl_backend_ramdisk_modify(struct ctl_be_ramdisk_softc *softc,
 	struct ctl_be_ramdisk_lun *be_lun;
 	struct ctl_be_lun *cbe_lun;
 	struct ctl_lun_modify_params *params;
+	char *value;
 	uint32_t blocksize;
+	int wasprim;
 
 	params = &req->reqdata.modify;
 
@@ -739,15 +752,32 @@ ctl_backend_ramdisk_modify(struct ctl_be_ramdisk_softc *softc,
 	if (params->lun_size_bytes != 0)
 		be_lun->params.lun_size_bytes = params->lun_size_bytes;
 	ctl_update_opts(&cbe_lun->options, req->num_be_args, req->kern_be_args);
-	blocksize = be_lun->cbe_lun.blocksize;
 
+	wasprim = (cbe_lun->flags & CTL_LUN_FLAG_PRIMARY);
+	value = ctl_get_opt(&cbe_lun->options, "ha_role");
+	if (value != NULL) {
+		if (strcmp(value, "primary") == 0)
+			cbe_lun->flags |= CTL_LUN_FLAG_PRIMARY;
+		else
+			cbe_lun->flags &= ~CTL_LUN_FLAG_PRIMARY;
+	} else if (control_softc->flags & CTL_FLAG_ACTIVE_SHELF)
+		cbe_lun->flags |= CTL_LUN_FLAG_PRIMARY;
+	else
+		cbe_lun->flags &= ~CTL_LUN_FLAG_PRIMARY;
+	if (wasprim != (cbe_lun->flags & CTL_LUN_FLAG_PRIMARY)) {
+		if (cbe_lun->flags & CTL_LUN_FLAG_PRIMARY)
+			ctl_lun_primary(cbe_lun);
+		else
+			ctl_lun_secondary(cbe_lun);
+	}
+
+	blocksize = be_lun->cbe_lun.blocksize;
 	if (be_lun->params.lun_size_bytes < blocksize) {
 		snprintf(req->error_str, sizeof(req->error_str),
 			"%s: LUN size %ju < blocksize %u", __func__,
 			be_lun->params.lun_size_bytes, blocksize);
 		goto bailout_error;
 	}
-
 	be_lun->size_blocks = be_lun->params.lun_size_bytes / blocksize;
 	be_lun->size_bytes = be_lun->size_blocks * blocksize;
 	be_lun->cbe_lun.maxlba = be_lun->size_blocks - 1;