Added all files

6 files changed, 941 insertions, 0 deletions

diff --git a/scheduler/rr/Makefile.am b/scheduler/rr/Makefile.am
new file mode 100644
index 00000000000..d471a3f9243
--- /dev/null
+++ b/scheduler/rr/Makefile.am
@@ -0,0 +1,3 @@
+SUBDIRS = src
+
+CLEANFILES = 
diff --git a/scheduler/rr/src/Makefile.am b/scheduler/rr/src/Makefile.am
new file mode 100644
index 00000000000..7e911c0eda8
--- /dev/null
+++ b/scheduler/rr/src/Makefile.am
@@ -0,0 +1,13 @@
+sched_LTLIBRARIES = rr.la
+scheddir = $(libdir)/glusterfs/$(PACKAGE_VERSION)/scheduler
+
+rr_la_LDFLAGS = -module -avoidversion
+
+rr_la_LIBADD = $(top_builddir)/libglusterfs/src/libglusterfs.la
+rr_la_SOURCES = rr.c rr-options.c
+noinst_HEADERS = rr.h rr-options.h
+
+AM_CFLAGS = -fPIC -D_FILE_OFFSET_BITS=64 -D_GNU_SOURCE -Wall -D$(GF_HOST_OS) \
+	-I$(top_srcdir)/libglusterfs/src -shared -nostartfiles $(GF_CFLAGS)
+
+CLEANFILES = 
diff --git a/scheduler/rr/src/rr-options.c b/scheduler/rr/src/rr-options.c
new file mode 100644
index 00000000000..3f0ffcaf2e9
--- /dev/null
+++ b/scheduler/rr/src/rr-options.c
@@ -0,0 +1,256 @@
+/*
+  Copyright (c) 2008 Z RESEARCH, Inc. <http://www.zresearch.com>
+  This file is part of GlusterFS.
+
+  GlusterFS is free software; you can redistribute it and/or modify
+  it under the terms of the GNU General Public License as published
+  by the Free Software Foundation; either version 3 of the License,
+  or (at your option) any later version.
+
+  GlusterFS is distributed in the hope that it will be useful, but
+  WITHOUT ANY WARRANTY; without even the implied warranty of
+  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+  General Public License for more details.
+
+  You should have received a copy of the GNU General Public License
+  along with this program.  If not, see
+  <http://www.gnu.org/licenses/>.
+*/
+
+#include "scheduler.h"
+#include "rr-options.h"
+
+#define RR_LIMITS_MIN_FREE_DISK_OPTION_STRING  "scheduler.limits.min-free-disk"
+#define RR_LIMITS_MIN_FREE_DISK_VALUE_DEFAULT  15
+#define RR_LIMITS_MIN_FREE_DISK_VALUE_MIN      0
+#define RR_LIMITS_MIN_FREE_DISK_VALUE_MAX      100
+
+#define RR_REFRESH_INTERVAL_OPTION_STRING      "scheduler.refresh-interval"
+#define RR_REFRESH_INTERVAL_VALUE_DEFAULT      10
+
+#define RR_READ_ONLY_SUBVOLUMES_OPTION_STRING  "scheduler.read-only-subvolumes"
+
+#define LOG_ERROR(args...)      gf_log ("rr-options", GF_LOG_ERROR, ##args)
+#define LOG_WARNING(args...)    gf_log ("rr-options", GF_LOG_WARNING, ##args)
+
+static int 
+_rr_options_min_free_disk_validate (const char *value_string, uint32_t *n)
+{
+	uint32_t value = 0;
+  
+	if (value_string == NULL)
+	{
+		return -1;
+	}
+  
+	if (gf_string2percent (value_string, &value) != 0)
+	{
+		gf_log ("rr", 
+			GF_LOG_ERROR, 
+			"invalid number format [%s] of option [%s]", 
+			value_string, 
+			RR_LIMITS_MIN_FREE_DISK_OPTION_STRING);
+		return -1;
+	}
+  
+	if ((value <= RR_LIMITS_MIN_FREE_DISK_VALUE_MIN) || 
+	    (value >= RR_LIMITS_MIN_FREE_DISK_VALUE_MAX))
+	{
+		gf_log ("rr", 
+			GF_LOG_ERROR, 
+			"out of range [%d] of option [%s].  Allowed range is 0 to 100.", 
+			value, 
+			RR_LIMITS_MIN_FREE_DISK_OPTION_STRING);
+		return -1;
+	}
+  
+	*n = value;
+  
+	return 0;
+}
+
+static int 
+_rr_options_refresh_interval_validate (const char *value_string, uint32_t *n)
+{
+	uint32_t value = 0;
+  
+	if (value_string == NULL)
+	{
+		return -1;
+	}
+  
+	if (gf_string2time (value_string, &value) != 0)
+	{
+		gf_log ("rr", 
+			GF_LOG_ERROR, 
+			"invalid number format [%s] of option [%s]", 
+			value_string, 
+			RR_REFRESH_INTERVAL_OPTION_STRING);
+		return -1;
+	}
+  
+	*n = value;
+  
+	return 0;
+}
+
+static int 
+_rr_options_read_only_subvolumes_validate (const char *value_string, 
+					   char ***volume_list, 
+					   uint64_t *volume_count)
+{
+	char **vlist = NULL;
+	int vcount = 0;
+	int i = 0;
+  
+	if (value_string == NULL || volume_list == NULL || volume_count)
+	{
+		return -1;
+	}
+  
+	if (gf_strsplit (value_string, 
+			 ", ", 
+			 &vlist, 
+			 &vcount) != 0)
+	{
+		gf_log ("rr", 
+			GF_LOG_ERROR, 
+			"invalid subvolume list [%s] of option [%s]", 
+			value_string, 
+			RR_READ_ONLY_SUBVOLUMES_OPTION_STRING);
+		return -1;
+	}
+  
+	for (i = 0; i < vcount; i++)
+	{
+		if (gf_volume_name_validate (vlist[i]) != 0)
+		{
+			gf_log ("rr", 
+				GF_LOG_ERROR, 
+				"invalid subvolume name [%s] in [%s] of option [%s]", 
+				vlist[i], 
+				value_string, 
+				RR_READ_ONLY_SUBVOLUMES_OPTION_STRING);
+			goto free_exit;
+		}
+	}
+  
+	*volume_list = vlist;
+	*volume_count = vcount;
+  
+	return 0;
+  
+ free_exit:
+	for (i = 0; i < vcount; i++)
+	{
+		free (vlist[i]);
+	}
+	free (vlist);
+  
+	return -1;
+}
+
+int 
+rr_options_validate (dict_t *options, rr_options_t *rr_options)
+{
+	char *value_string = NULL;
+  
+	if (options == NULL || rr_options == NULL)
+	{
+		return -1;
+	}
+  
+	if (dict_get (options, RR_LIMITS_MIN_FREE_DISK_OPTION_STRING))
+		if (data_to_str (dict_get (options, RR_LIMITS_MIN_FREE_DISK_OPTION_STRING)))
+			value_string = data_to_str (dict_get (options, 
+							      RR_LIMITS_MIN_FREE_DISK_OPTION_STRING));
+	if (value_string != NULL)
+	{
+		if (_rr_options_min_free_disk_validate (value_string, 
+							&rr_options->min_free_disk) != 0)
+		{
+			return -1;
+		}
+      
+		gf_log ("rr", 
+			GF_LOG_WARNING, 
+			"using %s = %d", 
+			RR_LIMITS_MIN_FREE_DISK_OPTION_STRING, 
+			rr_options->min_free_disk);
+	}
+	else 
+	{
+		rr_options->min_free_disk = RR_LIMITS_MIN_FREE_DISK_VALUE_DEFAULT;
+      
+		gf_log ("rr", GF_LOG_DEBUG, 
+			"using %s = %d [default]", 
+			RR_LIMITS_MIN_FREE_DISK_OPTION_STRING, 
+			rr_options->min_free_disk);
+	}
+  
+	value_string = NULL;
+	if (dict_get (options, RR_REFRESH_INTERVAL_OPTION_STRING))
+		value_string = data_to_str (dict_get (options, 
+						      RR_REFRESH_INTERVAL_OPTION_STRING));
+	if (value_string != NULL)
+	{
+		if (_rr_options_refresh_interval_validate (value_string, 
+							   &rr_options->refresh_interval) != 0)
+		{
+			return -1;
+		}
+      
+		gf_log ("rr", 
+			GF_LOG_WARNING, 
+			"using %s = %d", 
+			RR_REFRESH_INTERVAL_OPTION_STRING, 
+			rr_options->refresh_interval);
+	}
+	else 
+	{
+		rr_options->refresh_interval = RR_REFRESH_INTERVAL_VALUE_DEFAULT;
+      
+		gf_log ("rr", GF_LOG_DEBUG, 
+			"using %s = %d [default]", 
+			RR_REFRESH_INTERVAL_OPTION_STRING, 
+			rr_options->refresh_interval);
+	}
+  
+	value_string = NULL;
+	if (dict_get (options, RR_READ_ONLY_SUBVOLUMES_OPTION_STRING))
+		value_string = data_to_str (dict_get (options, 
+						      RR_READ_ONLY_SUBVOLUMES_OPTION_STRING));
+	if (value_string != NULL)
+	{
+		if (_rr_options_read_only_subvolumes_validate (value_string, 
+							       &rr_options->read_only_subvolume_list, 
+							       &rr_options->read_only_subvolume_count) != 0)
+		{
+			return -1;
+		}
+      
+		gf_log ("rr", 
+			GF_LOG_WARNING, 
+			"using %s = [%s]", 
+			RR_READ_ONLY_SUBVOLUMES_OPTION_STRING, 
+			value_string);
+	}
+  
+	return 0;
+}
+
+struct volume_options options[] = {
+	{ .key   = { "scheduler.refresh-interval", 
+		     "rr.refresh-interval" },  
+	  .type  = GF_OPTION_TYPE_TIME
+	},
+	{ .key   = { "scheduler.limits.min-free-disk", 
+		     "rr.limits.min-free-disk" },  
+	  .type  = GF_OPTION_TYPE_PERCENT
+	},
+	{ .key   = { "scheduler.read-only-subvolumes", 
+		     "rr.read-only-subvolumes" },  
+	  .type  = GF_OPTION_TYPE_ANY
+	},
+	{ .key = {NULL} }
+};
diff --git a/scheduler/rr/src/rr-options.h b/scheduler/rr/src/rr-options.h
new file mode 100644
index 00000000000..4818c7d491c
--- /dev/null
+++ b/scheduler/rr/src/rr-options.h
@@ -0,0 +1,34 @@
+/*
+   Copyright (c) 2008 Z RESEARCH, Inc. <http://www.zresearch.com>
+   This file is part of GlusterFS.
+
+   GlusterFS is free software; you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published
+   by the Free Software Foundation; either version 3 of the License,
+   or (at your option) any later version.
+
+   GlusterFS is distributed in the hope that it will be useful, but
+   WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program.  If not, see
+   <http://www.gnu.org/licenses/>.
+*/
+
+#ifndef _RR_OPTIONS_H
+#define _RR_OPTIONS_H
+
+struct rr_options
+{
+  uint32_t min_free_disk;
+  uint32_t refresh_interval;
+  char     **read_only_subvolume_list;
+  uint64_t read_only_subvolume_count;
+};
+typedef struct rr_options rr_options_t;
+
+int rr_options_validate (dict_t *options, rr_options_t *rr_options);
+
+#endif
diff --git a/scheduler/rr/src/rr.c b/scheduler/rr/src/rr.c
new file mode 100644
index 00000000000..3e54ff5e1b6
--- /dev/null
+++ b/scheduler/rr/src/rr.c
@@ -0,0 +1,565 @@
+/*
+  Copyright (c) 2006, 2007, 2008 Z RESEARCH, Inc. <http://www.zresearch.com>
+  This file is part of GlusterFS.
+
+  GlusterFS is free software; you can redistribute it and/or modify
+  it under the terms of the GNU General Public License as published
+  by the Free Software Foundation; either version 3 of the License,
+  or (at your option) any later version.
+
+  GlusterFS is distributed in the hope that it will be useful, but
+  WITHOUT ANY WARRANTY; without even the implied warranty of
+  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+  General Public License for more details.
+
+  You should have received a copy of the GNU General Public License
+  along with this program.  If not, see
+  <http://www.gnu.org/licenses/>.
+*/
+
+#ifndef _CONFIG_H
+#define _CONFIG_H
+#include "config.h"
+#endif
+
+#include <sys/time.h>
+#include <stdlib.h>
+
+#include <stdint.h>
+
+#include "scheduler.h"
+
+#include "rr-options.h"
+#include "rr.h"
+
+#define RR_MIN_FREE_DISK_NOT_REACHED    0
+#define RR_MIN_FREE_DISK_REACHED        1
+
+#define RR_SUBVOLUME_OFFLINE    0
+#define RR_SUBVOLUME_ONLINE     1
+
+#define LOG_ERROR(args...)      gf_log ("rr", GF_LOG_ERROR, ##args)
+#define LOG_WARNING(args...)    gf_log ("rr", GF_LOG_WARNING, ##args)
+#define LOG_CRITICAL(args...)    gf_log ("rr", GF_LOG_CRITICAL, ##args)
+
+#define ROUND_ROBIN(index, count)    ((index + 1) % count)
+
+static int 
+_cleanup_rr (rr_t *rr)
+{
+	int i;
+  
+	if (rr == NULL)
+	{
+		return -1;
+	}
+  
+	if (rr->options.read_only_subvolume_list != NULL)
+	{
+		for (i = 0; i < rr->options.read_only_subvolume_count; i++)
+		{
+			free (rr->options.read_only_subvolume_list[i]);
+		}
+		free (rr->options.read_only_subvolume_list);
+	}
+  
+	free (rr->subvolume_list);
+  
+	free (rr);
+  
+	return 0;
+}
+
+int 
+rr_init (xlator_t *this_xl)
+{
+	rr_t *rr = NULL;
+	dict_t *options = NULL;
+	xlator_list_t *children = NULL;
+	uint64_t children_count = 0;
+	int i = 0;
+	int j = 0;
+  
+	if (this_xl == NULL)
+	{
+		return -1;
+	}
+  
+	if ((options = this_xl->options) == NULL)
+	{
+		return -1;
+	}
+  
+	if ((children = this_xl->children) == NULL)
+	{
+		return -1;
+	}
+  
+	if ((rr = CALLOC (1, sizeof (rr_t))) == NULL)
+	{
+		return -1;
+	}
+  
+	if (rr_options_validate (options, &rr->options) != 0)
+	{
+		free (rr);
+		return -1;
+	}
+  
+	for (i = 0; i < rr->options.read_only_subvolume_count; i++)
+	{
+		char found = 0;
+      
+		for (children = this_xl->children; 
+		     children != NULL; 
+		     children = children->next)
+		{
+			if (strcmp (rr->options.read_only_subvolume_list[i], 
+				    children->xlator->name) == 0)
+			{
+				found = 1;
+				break;
+			}
+		}
+      
+		if (!found)
+		{
+			LOG_ERROR ("read-only subvolume [%s] not found in volume list", 
+				   rr->options.read_only_subvolume_list[i]);
+			_cleanup_rr (rr);
+			return -1;
+		}
+	}
+  
+	for (children = this_xl->children; 
+	     children != NULL; 
+	     children = children->next)
+	{
+		children_count++;
+	}
+  
+	/* bala: excluding read_only_subvolumes */
+	if ((rr->subvolume_count = children_count - 
+	     rr->options.read_only_subvolume_count) == 0)
+	{
+		LOG_ERROR ("no writable volumes found for scheduling");
+		_cleanup_rr (rr);
+		return -1;
+	}
+  
+	if ((rr->subvolume_list = CALLOC (rr->subvolume_count, 
+					  sizeof (rr_subvolume_t))) == NULL)
+	{
+		_cleanup_rr (rr);
+		return -1;
+	}
+  
+	i = 0;
+	j = 0;
+	for (children = this_xl->children; 
+	     children != NULL; 
+	     children = children->next)
+	{
+		char found = 0;
+      
+		for (j = 0; j < rr->options.read_only_subvolume_count; j++)
+		{
+			if (strcmp (rr->options.read_only_subvolume_list[i], 
+				    children->xlator->name) == 0)
+			{
+				found = 1;
+				break;
+			}
+		}
+      
+		if (!found)
+		{
+			rr_subvolume_t *subvolume = NULL;
+	  
+			subvolume = &rr->subvolume_list[i];
+	  
+			subvolume->xl = children->xlator;
+			subvolume->free_disk_status = RR_MIN_FREE_DISK_NOT_REACHED;
+			subvolume->status = RR_SUBVOLUME_ONLINE;
+	  
+			i++;
+		}
+	}
+  
+	rr->schedule_index = UINT64_MAX;
+	rr->last_stat_fetched_time.tv_sec = 0;
+	rr->last_stat_fetched_time.tv_usec = 0;
+	pthread_mutex_init (&rr->mutex, NULL);
+  
+	*((long *)this_xl->private) = (long)rr;
+  
+	return 0;
+}
+
+void 
+rr_fini (xlator_t *this_xl)
+{
+	rr_t *rr = NULL;
+  
+	if (this_xl == NULL)
+	{
+		return;
+	}
+  
+	if ((rr = (rr_t *) *((long *)this_xl->private)) != NULL)
+	{
+		pthread_mutex_destroy (&rr->mutex);
+		_cleanup_rr (rr);
+		this_xl->private = NULL;
+	}
+  
+	return;
+}
+
+xlator_t *
+rr_schedule (xlator_t *this_xl, const void *path)
+{
+	rr_t *rr = NULL;
+	uint64_t next_schedule_index = 0;
+	int i = 0;
+  
+	if (this_xl == NULL || path == NULL)
+	{
+		return NULL;
+	}
+  
+	rr = (rr_t *) *((long *)this_xl->private);
+	next_schedule_index = ROUND_ROBIN (rr->schedule_index, 
+					   rr->subvolume_count);
+  
+	rr_update (this_xl);
+  
+	for (i = next_schedule_index; i < rr->subvolume_count; i++)
+	{
+		if (rr->subvolume_list[i].status == RR_SUBVOLUME_ONLINE && 
+		    rr->subvolume_list[i].status == RR_MIN_FREE_DISK_NOT_REACHED)
+		{
+			pthread_mutex_lock (&rr->mutex);
+			rr->schedule_index = i;
+			pthread_mutex_unlock (&rr->mutex);
+			return rr->subvolume_list[i].xl;
+		}
+	}
+  
+	for (i = 0; i < next_schedule_index; i++)
+	{
+		if (rr->subvolume_list[i].status == RR_SUBVOLUME_ONLINE && 
+		    rr->subvolume_list[i].status == RR_MIN_FREE_DISK_NOT_REACHED)
+		{
+			pthread_mutex_lock (&rr->mutex);
+			rr->schedule_index = i;
+			pthread_mutex_unlock (&rr->mutex);
+			return rr->subvolume_list[i].xl;
+		}
+	}
+  
+	for (i = next_schedule_index; i < rr->subvolume_count; i++)
+	{
+		if (rr->subvolume_list[i].status == RR_SUBVOLUME_ONLINE)
+		{
+			pthread_mutex_lock (&rr->mutex);
+			rr->schedule_index = i;
+			pthread_mutex_unlock (&rr->mutex);
+			return rr->subvolume_list[i].xl;
+		}
+	}
+  
+	for (i = 0; i < next_schedule_index; i++)
+	{
+		if (rr->subvolume_list[i].status == RR_SUBVOLUME_ONLINE)
+		{
+			pthread_mutex_lock (&rr->mutex);
+			rr->schedule_index = i;
+			pthread_mutex_unlock (&rr->mutex);
+			return rr->subvolume_list[i].xl;
+		}
+	}
+  
+	return NULL;
+}
+
+void
+rr_update (xlator_t *this_xl)
+{
+	rr_t *rr = NULL;
+	struct timeval ctime = {0, 0};
+	int i = 0;
+  
+	if (this_xl == NULL)
+	{
+		return ;
+	}
+  
+	if ((rr = (rr_t *) *((long *)this_xl->private)) == NULL)
+	{
+		return ;
+	}
+  
+	if (gettimeofday (&ctime, NULL) != 0)
+	{
+		return ;
+	}
+  
+	if (ctime.tv_sec > (rr->options.refresh_interval + 
+			    rr->last_stat_fetched_time.tv_sec))
+	{
+		pthread_mutex_lock (&rr->mutex);
+		rr->last_stat_fetched_time = ctime;
+		pthread_mutex_unlock (&rr->mutex);
+      
+		for (i = 0; i < rr->subvolume_count; i++)
+		{
+			xlator_t *subvolume_xl = NULL;
+			call_frame_t *frame = NULL;
+			call_pool_t *pool = NULL;
+	  
+			subvolume_xl = rr->subvolume_list[i].xl;
+	  
+			pool = this_xl->ctx->pool;
+	  
+			frame = create_frame (this_xl, pool);
+
+			STACK_WIND_COOKIE (frame,
+					   rr_update_cbk, 
+					   subvolume_xl->name, 
+					   subvolume_xl, 
+					   subvolume_xl->mops->stats, 
+					   0);
+		}
+	}
+  
+	return ;
+}
+
+int 
+rr_update_cbk (call_frame_t *frame, 
+	       void *cookie, 
+	       xlator_t *this_xl, 
+	       int32_t op_ret, 
+	       int32_t op_errno, 
+	       struct xlator_stats *stats)
+{
+	rr_t *rr = NULL;
+	rr_subvolume_t *subvolume = NULL;
+	uint8_t free_disk_percent = 0;
+	int i = 0;
+  
+	if (frame == NULL)
+	{
+		return -1;
+	}
+  
+	if (cookie == NULL || this_xl == NULL)
+	{
+		STACK_DESTROY (frame->root);
+		return -1;
+	}
+  
+	if (op_ret == 0 && stats == NULL)
+	{
+		LOG_CRITICAL ("fatal! op_ret is 0 and stats is NULL.  "
+			      "Please report this to <gluster-devel@nongnu.org>");
+		STACK_DESTROY (frame->root);
+		return -1;
+	}
+  
+	if ((rr = (rr_t *) *((long *)this_xl->private)) == NULL)
+	{
+		STACK_DESTROY (frame->root);
+		return -1;
+	}
+  
+	for (i = 0; i < rr->subvolume_count; i++)
+	{
+		if (rr->subvolume_list[i].xl->name == (char *) cookie)
+		{
+			subvolume = &rr->subvolume_list[i];
+			break;
+		}
+	}
+  
+	if (subvolume == NULL)
+	{
+		LOG_ERROR ("unknown cookie [%s]", (char *) cookie);
+		STACK_DESTROY (frame->root);
+		return -1;
+	}
+  
+	if (op_ret == 0)
+	{
+		free_disk_percent = (stats->free_disk * 100) / stats->total_disk_size;
+		if (free_disk_percent > rr->options.min_free_disk)
+		{
+			if (subvolume->free_disk_status != RR_MIN_FREE_DISK_NOT_REACHED)
+			{
+				pthread_mutex_lock (&rr->mutex);
+				subvolume->free_disk_status = RR_MIN_FREE_DISK_NOT_REACHED;
+				pthread_mutex_unlock (&rr->mutex);
+				LOG_WARNING ("subvolume [%s] is available with free space for scheduling", 
+					     subvolume->xl->name);
+			}
+		}
+		else
+		{
+			if (subvolume->free_disk_status != RR_MIN_FREE_DISK_REACHED)
+			{
+				pthread_mutex_lock (&rr->mutex);
+				subvolume->free_disk_status = RR_MIN_FREE_DISK_REACHED;
+				pthread_mutex_unlock (&rr->mutex);
+				LOG_WARNING ("subvolume [%s] reached minimum disk space requirement", 
+					     subvolume->xl->name);
+			}
+		}
+	}
+	else 
+	{
+		pthread_mutex_lock (&rr->mutex);
+		subvolume->status = RR_SUBVOLUME_OFFLINE;
+		pthread_mutex_unlock (&rr->mutex);
+		LOG_ERROR ("unable to get subvolume [%s] status information and "
+			   "scheduling is disabled", 
+			   subvolume->xl->name);
+	}
+  
+	STACK_DESTROY (frame->root);
+	return 0;
+}
+
+void
+rr_notify (xlator_t *this_xl, int32_t event, void *data)
+{
+	rr_t *rr = NULL;
+	rr_subvolume_t *subvolume = NULL;
+	xlator_t *subvolume_xl = NULL;
+	int i = 0, ret = 0;
+	call_frame_t *frame = NULL;
+	call_pool_t *pool = NULL;
+	dict_t *xattr = get_new_dict ();
+	int32_t version[1] = {1};
+
+	if (this_xl == NULL || data == NULL) {
+		return ;
+	}
+  
+	if ((rr = (rr_t *) *((long *)this_xl->private)) == NULL) {
+		return ;
+	}
+  
+	subvolume_xl = (xlator_t *) data;
+  
+	for (i = 0; i < rr->subvolume_count; i++) {
+		if (rr->subvolume_list[i].xl == subvolume_xl) {
+			subvolume = &rr->subvolume_list[i];
+			break;
+		}
+	}
+  
+	switch (event) {
+	case GF_EVENT_CHILD_UP:
+		/* Seeding, to be done only once */
+		if (rr->first_time && (i == rr->subvolume_count)) {
+			loc_t loc = {0,};
+			xlator_t *trav = NULL;
+
+			pool = this_xl->ctx->pool;
+			frame = create_frame (this_xl, pool);
+			ret = dict_set_bin (xattr, "trusted.glusterfs.scheduler.rr",
+					    version, sizeof (int32_t));
+			if (-1 == ret) {
+				gf_log (this_xl->name, GF_LOG_ERROR, "rr seed setting failed");
+			}
+			if (xattr)
+				dict_ref (xattr);
+			
+			loc.path = strdup ("/");
+			for (trav = this_xl->parents->xlator; trav; trav = trav->parents->xlator) {
+				if (trav->itable) {
+					loc.inode = trav->itable->root;
+					break;
+				}
+			}
+			STACK_WIND (frame,
+				    rr_notify_cbk,
+				    (xlator_t *)data,
+				    ((xlator_t *)data)->fops->xattrop,
+				    &loc,
+				    GF_XATTROP_ADD_ARRAY,
+				    xattr);
+	  
+			if (xattr)
+				dict_unref (xattr);
+
+			rr->first_time = 0;
+		}
+		if (subvolume) {
+			pthread_mutex_lock (&rr->mutex);
+			subvolume->status = RR_SUBVOLUME_ONLINE;
+			pthread_mutex_unlock (&rr->mutex);
+		}
+		break;
+	case GF_EVENT_CHILD_DOWN:
+		if (subvolume) {
+			pthread_mutex_lock (&rr->mutex);
+			subvolume->status = RR_SUBVOLUME_OFFLINE;
+			pthread_mutex_unlock (&rr->mutex);
+		}
+		break;
+	}
+  
+	return ;
+}
+
+int 
+rr_notify_cbk (call_frame_t *frame, 
+	       void *cookie, 
+	       xlator_t *this_xl, 
+	       int32_t op_ret, 
+	       int32_t op_errno,
+	       dict_t *xattr)
+{
+	rr_t *rr = NULL;
+	int32_t *index = NULL;
+	int32_t ret = -1;
+	void *tmp_index_ptr = NULL;
+
+	if (frame == NULL) 
+	{
+		return -1;
+	}
+  
+	if ((this_xl == NULL) || (op_ret == -1))
+	{
+		STACK_DESTROY (frame->root);
+		return -1;
+	}
+  
+	if ((rr = (rr_t *) *((long *)this_xl->private)) == NULL)
+	{
+		STACK_DESTROY (frame->root);
+		return -1;
+	}
+  
+	ret = dict_get_bin (xattr, "trusted.glusterfs.scheduler.rr", &tmp_index_ptr);
+	index = tmp_index_ptr;
+	if (ret == 0)
+		rr->schedule_index = (index[0] % rr->subvolume_count);
+	else
+		rr->schedule_index = 0;
+
+	STACK_DESTROY (frame->root);
+	return 0;
+}
+
+struct sched_ops sched = {
+	.init     = rr_init,
+	.fini     = rr_fini,
+	.update   = rr_update,
+	.schedule = rr_schedule,
+	.notify   = rr_notify
+};
+
diff --git a/scheduler/rr/src/rr.h b/scheduler/rr/src/rr.h
new file mode 100644
index 00000000000..baa471209e8
--- /dev/null
+++ b/scheduler/rr/src/rr.h
@@ -0,0 +1,70 @@
+/*
+   Copyright (c) 2006, 2007, 2008 Z RESEARCH, Inc. <http://www.zresearch.com>
+   This file is part of GlusterFS.
+
+   GlusterFS is free software; you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published
+   by the Free Software Foundation; either version 3 of the License,
+   or (at your option) any later version.
+
+   GlusterFS is distributed in the hope that it will be useful, but
+   WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program.  If not, see
+   <http://www.gnu.org/licenses/>.
+*/
+
+#ifndef _RR_H
+#define _RR_H
+
+#ifndef _CONFIG_H
+#define _CONFIG_H
+#include "config.h"
+#endif
+
+#include "scheduler.h"
+#include <stdint.h>
+#include <sys/time.h>
+
+struct rr_subvolume
+{
+  xlator_t  *xl;
+  uint8_t   free_disk_status;
+  uint8_t   status;
+};
+typedef struct rr_subvolume rr_subvolume_t;
+
+struct rr
+{
+  rr_options_t    options;
+  rr_subvolume_t  *subvolume_list;
+  uint64_t        subvolume_count;
+  uint64_t        schedule_index;
+  struct timeval  last_stat_fetched_time;
+  pthread_mutex_t mutex;
+  char            first_time;
+};
+typedef struct rr rr_t;
+
+int rr_init (xlator_t *this_xl);
+void rr_fini (xlator_t *this_xl);
+xlator_t *rr_schedule (xlator_t *this_xl, const void *path);
+void rr_update (xlator_t *this_xl);
+int rr_update_cbk (call_frame_t *frame, 
+		   void *cookie, 
+		   xlator_t *this_xl, 
+		   int32_t op_ret, 
+		   int32_t op_errno, 
+		   struct xlator_stats *stats);
+void rr_notify (xlator_t *this_xl, int32_t event, void *data);
+int rr_notify_cbk (call_frame_t *frame, 
+		   void *cookie, 
+		   xlator_t *this_xl, 
+		   int32_t op_ret, 
+		   int32_t op_errno,
+		   dict_t *xattr);
+
+#endif /* _RR_H */