switch translator added

switch translator is a wrapper around distribute to work for a
pattern based scheduling.

Signed-off-by: Amar Tumballi <amar@gluster.com>
Signed-off-by: Anand V. Avati <avati@dev.gluster.com>

BUG: 409 (implement a switch scheduler)
URL: http://bugs.gluster.com/cgi-bin/bugzilla3/show_bug.cgi?id=409

3 files changed, 1059 insertions, 1 deletions

diff --git a/xlators/cluster/dht/src/Makefile.am b/xlators/cluster/dht/src/Makefile.am
index f87212699c9..70b89521e17 100644
--- a/xlators/cluster/dht/src/Makefile.am
+++ b/xlators/cluster/dht/src/Makefile.am
@@ -1,5 +1,5 @@
 
-xlator_LTLIBRARIES = dht.la nufa.la
+xlator_LTLIBRARIES = dht.la nufa.la switch.la
 xlatordir = $(libdir)/glusterfs/$(PACKAGE_VERSION)/xlator/cluster
 
 
@@ -9,6 +9,7 @@ dht_common_source = dht-layout.c dht-helper.c dht-linkfile.c \
 dht_la_SOURCES = $(dht_common_source) dht.c 
 
 nufa_la_SOURCES = $(dht_common_source) nufa.c
+switch_la_SOURCES = $(dht_common_source) switch.c
 
 dht_la_LDFLAGS = -module -avoidversion
 dht_la_LIBADD = $(top_builddir)/libglusterfs/src/libglusterfs.la
@@ -16,6 +17,9 @@ dht_la_LIBADD = $(top_builddir)/libglusterfs/src/libglusterfs.la
 nufa_la_LDFLAGS = -module -avoidversion
 nufa_la_LIBADD = $(top_builddir)/libglusterfs/src/libglusterfs.la
 
+switch_la_LDFLAGS = -module -avoidversion
+switch_la_LIBADD = $(top_builddir)/libglusterfs/src/libglusterfs.la
+
 noinst_HEADERS = dht-common.h dht-common.c
 
 AM_CFLAGS = -fPIC -D_FILE_OFFSET_BITS=64 -D_GNU_SOURCE -Wall -D$(GF_HOST_OS) \
diff --git a/xlators/cluster/dht/src/dht-common.h b/xlators/cluster/dht/src/dht-common.h
index 0666e0ea612..bdaf7b084d1 100644
--- a/xlators/cluster/dht/src/dht-common.h
+++ b/xlators/cluster/dht/src/dht-common.h
@@ -131,6 +131,8 @@ struct dht_conf {
         gf_boolean_t   unhashed_sticky_bit;
 	struct timeval last_stat_fetch;
         gf_lock_t      layout_lock;
+        void          *private;     /* Can be used by wrapper xlators over
+                                       dht */
 };
 typedef struct dht_conf dht_conf_t;
 
diff --git a/xlators/cluster/dht/src/switch.c b/xlators/cluster/dht/src/switch.c
new file mode 100644
index 00000000000..6670f0e3b3b
--- /dev/null
+++ b/xlators/cluster/dht/src/switch.c
@@ -0,0 +1,1052 @@
+/*
+   Copyright (c) 2009 Gluster, Inc. <http://www.gluster.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 "dht-common.c"
+
+#include <sys/time.h>
+#include <stdlib.h>
+#include <fnmatch.h>
+#include <string.h>
+
+struct switch_sched_array {
+	xlator_t *xl;
+	int32_t   eligible;
+	int32_t   considered;
+};
+
+/* Select one of this struct based on the path's pattern match */
+struct switch_struct {
+	struct switch_struct      *next;
+        struct switch_sched_array *array;
+	int32_t                    node_index; /* Index of the node in
+                                                  this pattern. */
+	int32_t                    num_child;  /* Total num of child nodes
+                                                  with this pattern. */
+	char                       path_pattern[256];
+};
+
+/* TODO: all 'TODO's in dht.c holds good */
+/* This function should return child node as '*:subvolumes' is inserterd */
+
+static int32_t
+gf_switch_valid_child (xlator_t *this, const char *child)
+{
+        xlator_list_t *children = NULL;
+        int32_t        ret = 0;
+
+        children = this->children;
+        while (children) {
+                if (!strcmp (child, children->xlator->name)) {
+                        ret = 1;
+                        break;
+                }
+                children = children->next;
+        }
+
+        return ret;
+}
+
+static xlator_t *
+get_switch_matching_subvol (const char *path, dht_conf_t *conf,
+                            xlator_t *hashed_subvol)
+{
+        struct switch_struct *cond      = NULL;
+	struct switch_struct *trav      = NULL;
+	char                 *pathname  = NULL;
+	int                   idx     = 0;
+
+        cond = conf->private;
+        if (!cond)
+                return hashed_subvol;
+
+        trav = cond;
+        pathname = strdup (path);
+	while (trav) {
+		if (fnmatch (trav->path_pattern,
+			     pathname, FNM_NOESCAPE) == 0) {
+                        for (idx = 0; idx < trav->num_child; idx++) {
+                                if (trav->array[idx].xl == hashed_subvol)
+                                        return hashed_subvol;
+                        }
+                        idx = trav->node_index++;
+                        trav->node_index %= trav->num_child;
+                        return trav->array[idx].xl;
+		}
+		trav = trav->next;
+	}
+	free (pathname);
+	return hashed_subvol;
+}
+
+
+int
+switch_local_lookup_cbk (call_frame_t *frame, void *cookie, xlator_t *this,
+                         int op_ret, int op_errno,
+                         inode_t *inode, struct stat *stbuf, dict_t *xattr,
+                         struct stat *postparent)
+{
+        xlator_t     *subvol      = NULL;
+        char          is_linkfile = 0;
+        char          is_dir      = 0;
+        dht_conf_t   *conf        = NULL;
+        dht_local_t  *local       = NULL;
+        loc_t        *loc         = NULL;
+        int           i           = 0;
+        call_frame_t *prev        = NULL;
+	int           call_cnt    = 0;
+        int           ret         = 0;
+
+        conf  = this->private;
+
+        prev  = cookie;
+        local = frame->local;
+        loc   = &local->loc;
+
+	if (ENTRY_MISSING (op_ret, op_errno)) {
+		if (conf->search_unhashed) {
+			local->op_errno = ENOENT;
+			dht_lookup_everywhere (frame, this, loc);
+			return 0;
+		}
+	}
+
+        if (op_ret == -1)
+                goto out;
+
+        is_linkfile = check_is_linkfile (inode, stbuf, xattr);
+        is_dir      = check_is_dir (inode, stbuf, xattr);
+
+        if (!is_dir && !is_linkfile) {
+                /* non-directory and not a linkfile */
+
+		dht_itransform (this, prev->this, stbuf->st_ino,
+				&stbuf->st_ino);
+
+		ret = dht_layout_preset (this, prev->this, inode);
+		if (ret < 0) {
+			gf_log (this->name, GF_LOG_DEBUG,
+				"could not set pre-set layout for subvol %s",
+				prev->this->name);
+			op_ret   = -1;
+			op_errno = EINVAL;
+			goto err;
+		}
+
+                goto out;
+        }
+
+        if (is_dir) {
+                call_cnt        = conf->subvolume_cnt;
+		local->call_cnt = call_cnt;
+
+                local->inode = inode_ref (inode);
+                local->xattr = dict_ref (xattr);
+
+		local->op_ret = 0;
+		local->op_errno = 0;
+
+		local->layout = dht_layout_new (this, conf->subvolume_cnt);
+		if (!local->layout) {
+			op_ret   = -1;
+			op_errno = ENOMEM;
+			gf_log (this->name, GF_LOG_DEBUG,
+				"memory allocation failed :(");
+			goto err;
+		}
+
+                for (i = 0; i < call_cnt; i++) {
+                        STACK_WIND (frame, dht_lookup_dir_cbk,
+                                    conf->subvolumes[i],
+                                    conf->subvolumes[i]->fops->lookup,
+                                    &local->loc, local->xattr_req);
+                }
+        }
+
+        if (is_linkfile) {
+                subvol = dht_linkfile_subvol (this, inode, stbuf, xattr);
+
+                if (!subvol) {
+                        gf_log (this->name, GF_LOG_DEBUG,
+                                "linkfile not having link subvolume. path=%s",
+                                loc->path);
+			dht_lookup_everywhere (frame, this, loc);
+			return 0;
+                }
+
+		STACK_WIND (frame, dht_lookup_linkfile_cbk,
+			    subvol, subvol->fops->lookup,
+			    &local->loc, local->xattr_req);
+        }
+
+        return 0;
+
+out:
+	if (!local->hashed_subvol) {
+		gf_log (this->name, GF_LOG_DEBUG,
+			"no subvolume in layout for path=%s",
+			local->loc.path);
+		op_errno = EINVAL;
+		goto err;
+	}
+
+	STACK_WIND (frame, dht_lookup_cbk,
+		    local->hashed_subvol, local->hashed_subvol->fops->lookup,
+		    &local->loc, local->xattr_req);
+
+	return 0;
+
+ err:
+        DHT_STACK_UNWIND (lookup, frame, op_ret, op_errno,
+                          inode, stbuf, xattr, NULL);
+        return 0;
+}
+
+int
+switch_lookup (call_frame_t *frame, xlator_t *this,
+	     loc_t *loc, dict_t *xattr_req)
+{
+        xlator_t     *hashed_subvol = NULL;
+        xlator_t     *cached_subvol = NULL;
+        xlator_t     *subvol = NULL;
+        dht_local_t  *local  = NULL;
+	dht_conf_t   *conf = NULL;
+        int           ret    = -1;
+        int           op_errno = -1;
+	dht_layout_t *layout = NULL;
+	int           i = 0;
+	int           call_cnt = 0;
+
+
+        VALIDATE_OR_GOTO (frame, err);
+        VALIDATE_OR_GOTO (this, err);
+        VALIDATE_OR_GOTO (loc, err);
+        VALIDATE_OR_GOTO (loc->inode, err);
+        VALIDATE_OR_GOTO (loc->path, err);
+
+	conf = this->private;
+
+        local = dht_local_init (frame);
+	if (!local) {
+		op_errno = ENOMEM;
+		gf_log (this->name, GF_LOG_ERROR,
+			"Out of memory");
+		goto err;
+	}
+
+        ret = loc_dup (loc, &local->loc);
+        if (ret == -1) {
+                op_errno = errno;
+                gf_log (this->name, GF_LOG_DEBUG,
+                        "copying location failed for path=%s",
+                        loc->path);
+                goto err;
+        }
+
+	if (xattr_req) {
+		local->xattr_req = dict_ref (xattr_req);
+	} else {
+		local->xattr_req = dict_new ();
+	}
+
+	hashed_subvol = dht_subvol_get_hashed (this, &local->loc);
+	cached_subvol = dht_subvol_get_cached (this, local->loc.inode);
+
+	local->cached_subvol = cached_subvol;
+	local->hashed_subvol = hashed_subvol;
+
+        if (is_revalidate (loc)) {
+		local->layout = layout = dht_layout_get (this, loc->inode);
+
+                if (!layout) {
+                        gf_log (this->name, GF_LOG_DEBUG,
+                                "revalidate without cache. path=%s",
+                                loc->path);
+                        op_errno = EINVAL;
+                        goto err;
+                }
+
+		if (layout->gen && (layout->gen < conf->gen)) {
+			gf_log (this->name, GF_LOG_DEBUG,
+				"incomplete layout failure for path=%s",
+				loc->path);
+                        dht_layout_unref (this, local->layout);
+			goto do_fresh_lookup;
+		}
+
+		local->inode    = inode_ref (loc->inode);
+		local->st_ino   = loc->inode->ino;
+
+		local->call_cnt = layout->cnt;
+		call_cnt = local->call_cnt;
+
+		/* NOTE: we don't require 'trusted.glusterfs.dht.linkto'
+                 * attribute, revalidates directly go to the cached-subvolume.
+		 */
+		ret = dict_set_uint32 (local->xattr_req,
+				       "trusted.glusterfs.dht", 4 * 4);
+
+		for (i = 0; i < layout->cnt; i++) {
+			subvol = layout->list[i].xlator;
+
+			STACK_WIND (frame, dht_revalidate_cbk,
+				    subvol, subvol->fops->lookup,
+				    loc, local->xattr_req);
+
+			if (!--call_cnt)
+				break;
+		}
+	} else {
+        do_fresh_lookup:
+		ret = dict_set_uint32 (local->xattr_req,
+				       "trusted.glusterfs.dht", 4 * 4);
+
+		ret = dict_set_uint32 (local->xattr_req,
+				       "trusted.glusterfs.dht.linkto", 256);
+
+                if (!hashed_subvol) {
+			gf_log (this->name, GF_LOG_DEBUG,
+				"no subvolume in layout for path=%s, "
+				"checking on all the subvols to see if "
+				"it is a directory", loc->path);
+ 			call_cnt        = conf->subvolume_cnt;
+ 			local->call_cnt = call_cnt;
+
+ 			local->layout = dht_layout_new (this,
+                                                        conf->subvolume_cnt);
+ 			if (!local->layout) {
+ 				op_errno = ENOMEM;
+ 				gf_log (this->name, GF_LOG_ERROR,
+ 					"Out of memory");
+ 				goto err;
+ 			}
+
+			for (i = 0; i < call_cnt; i++) {
+ 				STACK_WIND (frame, dht_lookup_dir_cbk,
+ 					    conf->subvolumes[i],
+ 					    conf->subvolumes[i]->fops->lookup,
+ 					    &local->loc, local->xattr_req);
+ 			}
+ 			return 0;
+                }
+
+		/*  */
+                cached_subvol = get_switch_matching_subvol (loc->path, conf,
+                                                            hashed_subvol);
+                if (cached_subvol == hashed_subvol) {
+                        STACK_WIND (frame, dht_lookup_cbk,
+                                    hashed_subvol,
+                                    hashed_subvol->fops->lookup,
+                                    loc, local->xattr_req);
+                } else {
+                        STACK_WIND (frame, switch_local_lookup_cbk,
+                                    cached_subvol,
+                                    cached_subvol->fops->lookup,
+                                    loc, local->xattr_req);
+                }
+        }
+
+        return 0;
+
+err:
+	op_errno = (op_errno == -1) ? errno : op_errno;
+        DHT_STACK_UNWIND (lookup, frame, -1, op_errno, NULL, NULL, NULL, NULL);
+	return 0;
+}
+
+int
+switch_create_linkfile_create_cbk (call_frame_t *frame, void *cookie,
+				 xlator_t *this, int op_ret, int op_errno,
+                                 inode_t *inode, struct stat *stbuf,
+                                 struct stat *preparent,
+                                 struct stat *postparent)
+{
+	dht_local_t  *local = NULL;
+	call_frame_t *prev = NULL;
+	dht_conf_t   *conf  = NULL;
+
+	local = frame->local;
+	prev  = cookie;
+	conf  = this->private;
+
+	if (op_ret == -1)
+		goto err;
+
+	STACK_WIND (frame, dht_create_cbk,
+		    local->cached_subvol, local->cached_subvol->fops->create,
+		    &local->loc, local->flags, local->mode, local->fd);
+
+	return 0;
+
+ err:
+	DHT_STACK_UNWIND (create, frame, -1, op_errno,
+                          NULL, NULL, NULL, NULL, NULL);
+	return 0;
+}
+
+int
+switch_create (call_frame_t *frame, xlator_t *this,
+	     loc_t *loc, int32_t flags, mode_t mode, fd_t *fd)
+{
+	dht_local_t *local = NULL;
+	dht_conf_t  *conf  = NULL;
+	xlator_t    *subvol = NULL;
+        xlator_t    *avail_subvol = NULL;
+	int          op_errno = -1;
+	int          ret = -1;
+
+	VALIDATE_OR_GOTO (frame, err);
+	VALIDATE_OR_GOTO (this, err);
+	VALIDATE_OR_GOTO (loc, err);
+
+	conf  = this->private;
+
+        dht_get_du_info (frame, this, loc);
+
+        local = dht_local_init (frame);
+	if (!local) {
+		op_errno = ENOMEM;
+		gf_log (this->name, GF_LOG_ERROR,
+			"Out of memory");
+		goto err;
+	}
+
+	subvol = dht_subvol_get_hashed (this, loc);
+	if (!subvol) {
+		gf_log (this->name, GF_LOG_DEBUG,
+			"no subvolume in layout for path=%s",
+			loc->path);
+		op_errno = ENOENT;
+		goto err;
+	}
+
+        avail_subvol = get_switch_matching_subvol (loc->path, conf, subvol);
+        if (dht_is_subvol_filled (this, avail_subvol)) {
+                avail_subvol =
+                        dht_free_disk_available_subvol (this, avail_subvol);
+        }
+
+        if (subvol != avail_subvol) {
+                /* create a link file instead of actual file */
+                ret = loc_copy (&local->loc, loc);
+                if (ret == -1) {
+                                gf_log (this->name, GF_LOG_ERROR,
+                                        "Out of memory");
+                                op_errno = ENOMEM;
+                                goto err;
+                }
+
+                local->fd = fd_ref (fd);
+                local->mode = mode;
+                local->flags = flags;
+
+                local->cached_subvol = avail_subvol;
+                dht_linkfile_create (frame,
+                                     switch_create_linkfile_create_cbk,
+                                     avail_subvol, subvol, loc);
+                return 0;
+        }
+
+        gf_log (this->name, GF_LOG_TRACE,
+                "creating %s on %s", loc->path, subvol->name);
+
+        STACK_WIND (frame, dht_create_cbk,
+                    subvol, subvol->fops->create,
+                    loc, flags, mode, fd);
+
+        return 0;
+
+err:
+	op_errno = (op_errno == -1) ? errno : op_errno;
+	DHT_STACK_UNWIND (create, frame, -1, op_errno,
+                          NULL, NULL, NULL, NULL, NULL);
+
+	return 0;
+}
+
+int
+switch_mknod_linkfile_cbk (call_frame_t *frame, void *cookie, xlator_t *this,
+                         int op_ret, int op_errno, inode_t *inode,
+                         struct stat *stbuf, struct stat *preparent,
+                         struct stat *postparent)
+{
+	dht_local_t  *local = NULL;
+	call_frame_t *prev = NULL;
+	dht_conf_t   *conf  = NULL;
+
+	local = frame->local;
+	prev  = cookie;
+	conf  = this->private;
+
+	if (op_ret >= 0) {
+		STACK_WIND (frame, dht_newfile_cbk,
+			    local->cached_subvol,
+			    local->cached_subvol->fops->mknod,
+			    &local->loc, local->mode, local->rdev);
+
+		return 0;
+	}
+
+	DHT_STACK_UNWIND (link, frame, op_ret, op_errno,
+                          inode, stbuf, preparent, postparent);
+	return 0;
+}
+
+
+int
+switch_mknod (call_frame_t *frame, xlator_t *this,
+	    loc_t *loc, mode_t mode, dev_t rdev)
+{
+	dht_local_t *local = NULL;
+	dht_conf_t  *conf  = NULL;
+	xlator_t    *subvol = NULL;
+        xlator_t    *avail_subvol = NULL;
+	int          op_errno = -1;
+	int          ret = -1;
+
+	VALIDATE_OR_GOTO (frame, err);
+	VALIDATE_OR_GOTO (this, err);
+	VALIDATE_OR_GOTO (loc, err);
+
+	conf  = this->private;
+
+        dht_get_du_info (frame, this, loc);
+
+        local = dht_local_init (frame);
+	if (!local) {
+		op_errno = ENOMEM;
+		gf_log (this->name, GF_LOG_ERROR,
+			"Out of memory");
+		goto err;
+	}
+
+	subvol = dht_subvol_get_hashed (this, loc);
+	if (!subvol) {
+		gf_log (this->name, GF_LOG_DEBUG,
+			"no subvolume in layout for path=%s",
+			loc->path);
+		op_errno = ENOENT;
+		goto err;
+	}
+
+        /* Consider the disksize in consideration */
+        avail_subvol = get_switch_matching_subvol (loc->path, conf, subvol);
+        if (dht_is_subvol_filled (this, avail_subvol)) {
+                avail_subvol =
+                        dht_free_disk_available_subvol (this, avail_subvol);
+        }
+
+	if (avail_subvol != subvol) {
+		/* Create linkfile first */
+		ret = loc_copy (&local->loc, loc);
+		if (ret == -1) {
+			gf_log (this->name, GF_LOG_ERROR,
+				"Out of memory");
+			op_errno = ENOMEM;
+			goto err;
+		}
+
+		local->mode = mode;
+		local->rdev = rdev;
+		local->cached_subvol = avail_subvol;
+
+		dht_linkfile_create (frame, switch_mknod_linkfile_cbk,
+                                     avail_subvol, subvol, loc);
+		return 0;
+	}
+
+	gf_log (this->name, GF_LOG_TRACE,
+		"creating %s on %s", loc->path, subvol->name);
+
+	STACK_WIND (frame, dht_newfile_cbk,
+		    subvol, subvol->fops->mknod,
+		    loc, mode, rdev);
+
+	return 0;
+
+err:
+	op_errno = (op_errno == -1) ? errno : op_errno;
+	DHT_STACK_UNWIND (mknod, frame, -1, op_errno,
+                          NULL, NULL, NULL, NULL);
+
+	return 0;
+}
+
+
+int
+notify (xlator_t *this, int event, void *data, ...)
+{
+	int ret = -1;
+
+	ret = dht_notify (this, event, data);
+
+	return ret;
+}
+
+void
+fini (xlator_t *this)
+{
+        int                   i = 0;
+        dht_conf_t           *conf = NULL;
+        struct switch_struct *trav = NULL;
+        struct switch_struct *prev = NULL;
+
+	conf = this->private;
+
+        if (conf) {
+                trav = (struct switch_struct *)conf->private;
+                conf->private = NULL;
+                while (trav) {
+                        if (trav->array)
+                                FREE (trav->array);
+                        prev = trav;
+                        trav = trav->next;
+                        FREE (prev);
+                }
+
+                if (conf->file_layouts) {
+                        for (i = 0; i < conf->subvolume_cnt; i++) {
+                                FREE (conf->file_layouts[i]);
+                        }
+                        FREE (conf->file_layouts);
+                }
+
+                if (conf->default_dir_layout)
+                        FREE (conf->default_dir_layout);
+
+                if (conf->subvolumes)
+                        FREE (conf->subvolumes);
+
+		if (conf->subvolume_status)
+			FREE (conf->subvolume_status);
+
+                FREE (conf);
+        }
+
+	return;
+}
+
+int
+set_switch_pattern (xlator_t *this, dht_conf_t *conf,
+                    const char *pattern_str)
+{
+        int                         flag = 0;
+        int                         idx = 0;
+        int                         index = 0;
+        int                         child_count = 0;
+        char                       *tmp = NULL;
+        char                       *tmp1 = NULL;
+        char                       *child = NULL;
+        char                       *tmp_str = NULL;
+        char                       *tmp_str1 = NULL;
+        char                       *dup_str = NULL;
+        char                       *dup_childs = NULL;
+        char                       *switch_str = NULL;
+        char                       *pattern = NULL;
+        char                       *childs = NULL;
+        char                       *option_string = NULL;
+        struct switch_struct        *switch_buf = NULL;
+        struct switch_struct        *switch_opt = NULL;
+        struct switch_struct        *trav = NULL;
+	struct switch_sched_array  *switch_buf_array = NULL;
+	xlator_list_t              *trav_xl = NULL;
+
+        trav_xl = this->children;
+	while (trav_xl) {
+		index++;
+		trav_xl = trav_xl->next;
+	}
+	child_count = index;
+	switch_buf_array = CALLOC ((index + 1),
+                                   sizeof (struct switch_sched_array));
+        if (!switch_buf_array)
+                goto err;
+
+	trav_xl = this->children;
+	index = 0;
+
+	while (trav_xl) {
+		switch_buf_array[index].xl = trav_xl->xlator;
+		switch_buf_array[index].eligible = 1;
+		trav_xl = trav_xl->next;
+		index++;
+	}
+
+	/*  *jpg:child1,child2;*mpg:child3;*:child4,child5,child6 */
+
+        /* Get the pattern for considering switch case.
+           "option block-size *avi:10MB" etc */
+        option_string = strdup (pattern_str);
+        switch_str = strtok_r (option_string, ";", &tmp_str);
+        while (switch_str) {
+                dup_str = strdup (switch_str);
+                switch_opt = CALLOC (1, sizeof (struct switch_struct));
+                if (!switch_opt)
+                        goto err;
+
+                pattern = strtok_r (dup_str, ":", &tmp_str1);
+                childs = strtok_r (NULL, ":", &tmp_str1);
+                if (strncmp (pattern, "*", 2) == 0) {
+                        gf_log ("switch", GF_LOG_NORMAL,
+                                "'*' pattern will be taken by default "
+                                "for all the unconfigured child nodes,"
+                                " hence neglecting current option");
+                        switch_str = strtok_r (NULL, ";", &tmp_str);
+                        free (dup_str);
+                        continue;
+                }
+                memcpy (switch_opt->path_pattern, pattern, strlen (pattern));
+                if (childs) {
+                        dup_childs = strdup (childs);
+                        child = strtok_r (dup_childs, ",", &tmp);
+                        while (child) {
+                                if (gf_switch_valid_child (this, child)) {
+                                        idx++;
+                                        child = strtok_r (NULL, ",", &tmp);
+                                } else {
+                                        gf_log (this->name, GF_LOG_ERROR,
+                                                "%s is not a subvolume of %s. "
+                                                "pattern can only be scheduled "
+                                                "only to a subvolume of %s",
+                                                child, this->name, this->name);
+                                        goto err;
+                                }
+                        }
+                        free (dup_childs);
+                        child = strtok_r (childs, ",", &tmp1);
+                        switch_opt->num_child = idx;
+                        switch_opt->array = CALLOC (1, (idx *
+                                                        sizeof (struct switch_sched_array)));
+                        if (!switch_opt->array)
+                                goto err;
+                        idx = 0;
+                        while (child) {
+                                for (index = 0; index < child_count; index++) {
+                                        if (strcmp (switch_buf_array[index].xl->name,
+                                                    child) == 0) {
+                                                gf_log ("switch", GF_LOG_DEBUG,
+                                                        "'%s' pattern will be "
+                                                        "scheduled to \"%s\"",
+                                                        switch_opt->path_pattern, child);
+                                                /*
+                                                  if (switch_buf_array[index-1].considered) {
+                                                  gf_log ("switch", GF_LOG_DEBUG,
+                                                  "ambiguity found, exiting");
+                                                  return -1;
+                                                  }
+                                                */
+                                                switch_opt->array[idx].xl = switch_buf_array[index].xl;
+                                                switch_buf_array[index].considered = 1;
+                                                idx++;
+                                                break;
+                                        }
+                                }
+                                child = strtok_r (NULL, ",", &tmp1);
+                        }
+                } else {
+                        /* error */
+                        gf_log ("switch", GF_LOG_ERROR,
+                                "Check \"scheduler.switch.case\" "
+                                "option in unify volume. Exiting");
+                        goto err;
+                }
+                free (dup_str);
+                
+                /* Link it to the main structure */
+                if (switch_buf) {
+                        /* there are already few entries */
+                        trav = switch_buf;
+                        while (trav->next)
+                                trav = trav->next;
+                        trav->next = switch_opt;
+                } else {
+                        /* First entry */
+                        switch_buf = switch_opt;
+                }
+                switch_str = strtok_r (NULL, ";", &tmp_str);
+        }
+
+	/* Now, all the pattern based considerations done, so for all the
+	 * remaining pattern, '*' to all the remaining child nodes
+	 */
+	{
+		for (index=0; index < child_count; index++) {
+			/* check for considered flag */
+			if (switch_buf_array[index].considered)
+				continue;
+			flag++;
+		}
+		if (!flag) {
+			gf_log ("switch", GF_LOG_ERROR,
+				"No nodes left for pattern '*'. Exiting");
+			goto err;
+		}
+		switch_opt = CALLOC (1, sizeof (struct switch_struct));
+                if (!switch_opt)
+                        goto err;
+
+		/* Add the '*' pattern to the array */
+		memcpy (switch_opt->path_pattern, "*", 2);
+		switch_opt->num_child = flag;
+		switch_opt->array =
+			CALLOC (1, flag * sizeof (struct switch_sched_array));
+                if (!switch_opt->array)
+                        goto err;
+		flag = 0;
+		for (index=0; index < child_count; index++) {
+			/* check for considered flag */
+			if (switch_buf_array[index].considered)
+				continue;
+			gf_log ("switch", GF_LOG_DEBUG,
+				"'%s' pattern will be scheduled to \"%s\"",
+				switch_opt->path_pattern,
+				switch_buf_array[index].xl->name);
+			switch_opt->array[flag].xl =
+				switch_buf_array[index].xl;
+			switch_buf_array[index].considered = 1;
+			flag++;
+                }
+		if (switch_buf) {
+			/* there are already few entries */
+			trav = switch_buf;
+			while (trav->next)
+				trav = trav->next;
+			trav->next = switch_opt;
+		} else {
+			/* First entry */
+			switch_buf = switch_opt;
+		}
+	}
+        /* */
+        conf->private = switch_buf;
+
+        return 0;
+err:
+        if (switch_buf) {
+                if (switch_buf_array)
+                        FREE (switch_buf_array);
+                trav = switch_buf;
+                while (trav) {
+                        if (trav->array)
+                                FREE (trav->array);
+                        switch_opt = trav;
+                        trav = trav->next;
+                        FREE (switch_opt);
+                }
+        }
+        return -1;
+}
+
+
+int
+init (xlator_t *this)
+{
+        dht_conf_t            *conf = NULL;
+	data_t                *data = NULL;
+	char                  *temp_str = NULL;
+        int                    ret = -1;
+        int                    i = 0;
+	uint32_t               temp_free_disk = 0;
+
+	if (!this->children) {
+		gf_log (this->name, GF_LOG_CRITICAL,
+			"SWITCH needs more than one subvolume");
+		return -1;
+	}
+
+	if (!this->parents) {
+		gf_log (this->name, GF_LOG_WARNING,
+			"dangling volume. check volfile");
+	}
+
+        conf = CALLOC (1, sizeof (*conf));
+        if (!conf) {
+                gf_log (this->name, GF_LOG_ERROR,
+                        "Out of memory");
+                goto err;
+        }
+
+	conf->search_unhashed = 1;
+	if (dict_get_str (this->options, "lookup-unhashed", &temp_str) == 0) {
+		gf_string2boolean (temp_str, &conf->search_unhashed);
+	}
+
+	conf->unhashed_sticky_bit = 0;
+	if (dict_get_str (this->options, "unhashed-sticky-bit",
+                          &temp_str) == 0) {
+	        gf_string2boolean (temp_str, &conf->unhashed_sticky_bit);
+	}
+
+        conf->min_free_disk = 10;
+        conf->disk_unit = 'p';
+
+        if (dict_get_str (this->options, "min-free-disk",
+                          &temp_str) == 0) {
+                if (gf_string2percent (temp_str,
+                                       &temp_free_disk) == 0) {
+                        if (temp_free_disk > 100) {
+                                gf_string2bytesize (temp_str,
+                                                        &conf->min_free_disk);
+                                conf->disk_unit = 'b';
+                        } else {
+                                conf->min_free_disk = (uint64_t)temp_free_disk;
+                                conf->disk_unit = 'p';
+                        }
+                } else {
+                        gf_string2bytesize (temp_str,
+                                                &conf->min_free_disk);
+                        conf->disk_unit = 'b';
+                }
+        }
+
+	data = dict_get (this->options, "pattern.switch.case");
+	if (data) {
+                /* TODO: */
+                ret = set_switch_pattern (this, conf, data->data);
+                if (ret) {
+                        goto err;
+                }
+	}
+
+        ret = dht_init_subvolumes (this, conf);
+        if (ret == -1) {
+                goto err;
+        }
+
+        ret = dht_layouts_init (this, conf);
+        if (ret == -1) {
+                goto err;
+        }
+
+	LOCK_INIT (&conf->subvolume_lock);
+	LOCK_INIT (&conf->layout_lock);
+
+	conf->gen = 1;
+
+        conf->du_stats = CALLOC (conf->subvolume_cnt, sizeof (dht_du_t));
+        if (!conf->du_stats) {
+                gf_log (this->name, GF_LOG_ERROR,
+                        "Out of memory");
+                goto err;
+        }
+
+        this->private = conf;
+
+        return 0;
+
+err:
+        if (conf) {
+                if (conf->file_layouts) {
+                        for (i = 0; i < conf->subvolume_cnt; i++) {
+                                FREE (conf->file_layouts[i]);
+                        }
+                        FREE (conf->file_layouts);
+                }
+
+                if (conf->default_dir_layout)
+                        FREE (conf->default_dir_layout);
+
+                if (conf->subvolumes)
+                        FREE (conf->subvolumes);
+
+		if (conf->subvolume_status)
+			FREE (conf->subvolume_status);
+
+                if (conf->du_stats)
+                        FREE (conf->du_stats);
+
+                FREE (conf);
+        }
+
+        return -1;
+}
+
+
+struct xlator_fops fops = {
+	.lookup      = switch_lookup,
+	.create      = switch_create,
+	.mknod       = switch_mknod,
+
+	.stat        = dht_stat,
+	.fstat       = dht_fstat,
+	.truncate    = dht_truncate,
+	.ftruncate   = dht_ftruncate,
+	.access      = dht_access,
+	.readlink    = dht_readlink,
+	.setxattr    = dht_setxattr,
+	.getxattr    = dht_getxattr,
+	.removexattr = dht_removexattr,
+	.open        = dht_open,
+	.readv       = dht_readv,
+	.writev      = dht_writev,
+	.flush       = dht_flush,
+	.fsync       = dht_fsync,
+	.statfs      = dht_statfs,
+	.lk          = dht_lk,
+	.opendir     = dht_opendir,
+	.readdir     = dht_readdir,
+	.readdirp    = dht_readdirp,
+	.fsyncdir    = dht_fsyncdir,
+	.symlink     = dht_symlink,
+	.unlink      = dht_unlink,
+	.link        = dht_link,
+	.mkdir       = dht_mkdir,
+	.rmdir       = dht_rmdir,
+	.rename      = dht_rename,
+	.inodelk     = dht_inodelk,
+	.finodelk    = dht_finodelk,
+	.entrylk     = dht_entrylk,
+	.fentrylk    = dht_fentrylk,
+	.xattrop     = dht_xattrop,
+	.fxattrop    = dht_fxattrop,
+        .setattr     = dht_setattr,
+#if 0
+	.setdents    = dht_setdents,
+	.getdents    = dht_getdents,
+	.checksum    = dht_checksum,
+#endif
+};
+
+
+struct xlator_mops mops = {
+};
+
+
+struct xlator_cbks cbks = {
+	.forget     = dht_forget
+};
+
+
+struct volume_options options[] = {
+	{ .key  = {"pattern.switch.case"},
+	  .type = GF_OPTION_TYPE_ANY
+	},
+        { .key  = {"lookup-unhashed"},
+	  .type = GF_OPTION_TYPE_BOOL
+	},
+        { .key  = {"min-free-disk"},
+          .type = GF_OPTION_TYPE_PERCENT_OR_SIZET,
+        },
+	{ .key  = {NULL} },
+};