[dm-devel] [PATCH RFC 0/1] async path-selector initialization

[Mike Christie <michaelc cs wisc edu>]

01-ps-args.patch - enables a path-selector to be able to get selector
wide arguments - vs path level args. (the interface for the status function
still needs work)

diffstat 01-ps-args.patch
 dm-mpath.c         |   65 ++++++++++++++++++++++++++++++++++++-----------------
 dm-path-selector.c |   59 ++++++++++++++++++++++++++++++++----------------
 dm-path-selector.h |   17 ++++++++-----
 3 files changed, 96 insertions(+), 45 deletions(-)

diff -arup linux-2.6.5-orig/drivers/md/dm-mpath.c linux-2.6.5-psargs/drivers/md/dm-mpath.c
--- linux-2.6.5-orig/drivers/md/dm-mpath.c	2004-04-18 20:34:44.000000000 -0700
+++ linux-2.6.5-psargs/drivers/md/dm-mpath.c	2004-04-18 22:29:27.991470346 -0700
@@ -324,8 +324,8 @@ static void trigger_event(void *data)
 
 /*-----------------------------------------------------------------
  * Constructor/argument parsing:
- * <num priority groups> [<selector>
- * <num paths> <num selector args> [<path> [<arg>]* ]+ ]+
+ * <num priority groups> [<selector> <num selector args> [<arg>]*
+ * <num path args> <num paths> [<path> [<arg>]* ]+ ]+
  *---------------------------------------------------------------*/
 struct param {
 	unsigned min;
@@ -420,7 +420,7 @@ static struct priority_group *parse_prio
 	};
 
 	int r;
-	unsigned i, nr_selector_args, nr_params;
+	unsigned i, nr_args;
 	struct priority_group *pg;
 	struct path_selector_type *pst;
 
@@ -443,34 +443,47 @@ static struct priority_group *parse_prio
 		goto bad;
 	}
 
-	r = pst->ctr(pg->ps);
+	/*
+	 * nr selector args
+	 */
+	r = read_param(_params + 1, shift(as), &nr_args, &ti->error);
+	if (r)
+		goto bad;
+	if (as->argc < nr_args)
+		goto bad;
+
+	r = pst->ctr(pg->ps, nr_args, as->argv, &ti->error);
 	if (r) {
 		/* FIXME: need to put the pst ? fix after
 		 * factoring out the register */
 		goto bad;
 	}
 	pg->ps->type = pst;
+	consume(as, nr_args);
 
 	/*
-	 * read the paths
+	 * nr path args
 	 */
-	r = read_param(_params, shift(as), &pg->nr_paths, &ti->error);
+	r = read_param(_params + 1, shift(as), &nr_args, &ti->error);
 	if (r)
 		goto bad;
 
-	r = read_param(_params + 1, shift(as), &nr_selector_args, &ti->error);
+	/*
+	 * read the paths
+	 */
+	r = read_param(_params, shift(as), &pg->nr_paths, &ti->error);
 	if (r)
 		goto bad;
 
-	nr_params = 1 + nr_selector_args;
+	nr_args += 1;
 	for (i = 0; i < pg->nr_paths; i++) {
 		struct path *path;
 		struct arg_set path_args;
 
-		if (as->argc < nr_params)
+		if (as->argc < nr_args)
 			goto bad;
 
-		path_args.argc = nr_params;
+		path_args.argc = nr_args;
 		path_args.argv = as->argv;
 
 		path = parse_path(&path_args, pg->ps, ti);
@@ -479,7 +492,7 @@ static struct priority_group *parse_prio
 
 		path->pg = pg;
 		list_add_tail(&path->list, &pg->paths);
-		consume(as, nr_params);
+		consume(as, nr_args);
 	}
 
 	return pg;
@@ -617,10 +630,11 @@ static int multipath_end_io(struct dm_ta
 
 /*
  * Info string has the following format:
- * num_groups [num_paths num_selector_args [path_dev A|F fail_count [selector_args]* ]+ ]+
+ * num_groups [[selector_args]* num_paths [path_dev A|F fail_count [path_args]* ]+ ]+
  *
  * Table string has the following format (identical to the constructor string):
- * num_groups [priority selector-name num_paths num_selector_args [path_dev [selector_args]* ]+ ]+
+ * num_groups [selector-name num_selector_args [selector_args]* num_path_args num_paths
+ * [path_dev [path_args]* ]+ ]+
  */
 static int multipath_status(struct dm_target *ti, status_type_t type,
 			    char *result, unsigned int maxlen)
@@ -630,6 +644,7 @@ static int multipath_status(struct dm_ta
 	struct priority_group *pg;
 	struct path *p;
 	char buffer[32];
+	struct path_selector_type *pst;
 
 #define EMIT(x...) sz += ((sz >= maxlen) ? \
 			  0 : scnprintf(result + sz, maxlen - sz, x))
@@ -639,13 +654,18 @@ static int multipath_status(struct dm_ta
 		EMIT("%u ", m->nr_priority_groups);
 
 		list_for_each_entry(pg, &m->priority_groups, list) {
-			EMIT("%u %u ", pg->nr_paths, pg->ps->type->info_args);
+			pst = pg->ps->type;
+
+			sz += pst->ps_status(pg->ps, type, result + sz,
+					     maxlen - sz);
+			EMIT("%u ", pg->nr_paths);
 
 			list_for_each_entry(p, &pg->paths, list) {
 				format_dev_t(buffer, p->dev->bdev->bd_dev);
 				EMIT("%s ", buffer);
-				sz += pg->ps->type->status(pg->ps, p, type,
-						     result + sz, maxlen - sz);
+				sz += pst->path_status(pg->ps, p, type,
+						       result + sz,
+						       maxlen - sz);
 			}
 		}
 		break;
@@ -654,14 +674,19 @@ static int multipath_status(struct dm_ta
 		EMIT("%u ", m->nr_priority_groups);
 
 		list_for_each_entry(pg, &m->priority_groups, list) {
-			EMIT("%s %u %u ", pg->ps->type->name,
-			     pg->nr_paths, pg->ps->type->table_args);
+		        pst = pg->ps->type;
+
+			EMIT("%s ", pst->name);
+			sz += pst->ps_status(pg->ps, type, result + sz,
+					     maxlen - sz);
+			EMIT("%u ", pg->nr_paths);
 
 			list_for_each_entry(p, &pg->paths, list) {
 				format_dev_t(buffer, p->dev->bdev->bd_dev);
 				EMIT("%s ", buffer);
-				pg->ps->type->status(pg->ps, p, type,
-						     result + sz, maxlen - sz);
+				sz += pst->path_status(pg->ps, p, type,
+						       result + sz,
+						       maxlen - sz);
 
 			}
 		}
diff -arup linux-2.6.5-orig/drivers/md/dm-path-selector.c linux-2.6.5-psargs/drivers/md/dm-path-selector.c
--- linux-2.6.5-orig/drivers/md/dm-path-selector.c	2004-04-18 20:34:44.000000000 -0700
+++ linux-2.6.5-psargs/drivers/md/dm-path-selector.c	2004-04-18 22:15:13.867049131 -0700
@@ -174,10 +174,17 @@ static struct selector *alloc_selector(v
 }
 
 /* Path selector constructor */
-static int rr_ctr(struct path_selector *ps)
+static int rr_ctr(struct path_selector *ps, int argc, char **argv,
+		  char **error)
 {
 	struct selector *s;
 
+	/* parse the path-selector arguments */
+	if (argc != 0) {
+		*error = "round-robin ps: incorrect number of arguments";
+		return -EINVAL;
+	}
+
 	s = alloc_selector();
 	if (!s)
 		return -ENOMEM;
@@ -273,8 +280,8 @@ static struct path *rr_select_path(struc
 }
 
 /* Path status */
-static int rr_status(struct path_selector *ps, struct path *path,
-		     status_type_t type, char *result, unsigned int maxlen)
+static int rr_path_status(struct path_selector *ps, struct path *path,
+			  status_type_t type, char *result, unsigned int maxlen)
 {
 	unsigned long flags;
 	struct path_info *pi;
@@ -282,26 +289,39 @@ static int rr_status(struct path_selecto
 	struct selector *s = (struct selector *) ps->context;
 	int sz = 0;
 
-	if (type == STATUSTYPE_TABLE)
-		return 0;
+	if (type == STATUSTYPE_INFO) {
 
-	spin_lock_irqsave(&s->lock, flags);
+		spin_lock_irqsave(&s->lock, flags);
 
-	/*
-	 * Is status called often for testing or something?
-	 * If so maybe a ps's info should be allocated w/ path
-	 * so a simple container_of can be used.
-	 */
-	pi = path_lookup(&s->valid_paths, path);
-	if (!pi) {
-		failed = 1;
-		pi = path_lookup(&s->invalid_paths, path);
+		/*
+		 * Is status called often for testing or something?
+		 * If so maybe a ps's info should be allocated w/ path
+		 * so a simple container_of can be used.
+		 */
+		pi = path_lookup(&s->valid_paths, path);
+		if (!pi) {
+			failed = 1;
+			pi = path_lookup(&s->invalid_paths, path);
+		}
+		
+		sz = scnprintf(result, maxlen, "%s %u ", failed ? "F" : "A",
+			       pi->fail_count);
+		
+		spin_unlock_irqrestore(&s->lock, flags);
 	}
 
-	sz = scnprintf(result, maxlen, "%s %u ", failed ? "F" : "A",
-		       pi->fail_count);
+	return sz;
+}
 
-	spin_unlock_irqrestore(&s->lock, flags);
+/* path selector status */
+static int rr_ps_status(struct path_selector *ps, status_type_t type,
+			char *result, unsigned int maxlen)
+{
+	int sz = 0;
+
+	if (type == STATUSTYPE_TABLE)
+		/* <num selector args> [<arg>]* <num path args> */
+		sz = scnprintf(result, maxlen, "0 0 ");
 
 	return sz;
 }
@@ -315,7 +335,8 @@ static struct path_selector_type rr_ps =
 	.add_path = rr_add_path,
 	.update_path = rr_update_path,
 	.select_path = rr_select_path,
-	.status = rr_status,
+	.ps_status = rr_ps_status,
+	.path_status = rr_path_status,
 };
 
 /*
diff -arup linux-2.6.5-orig/drivers/md/dm-path-selector.h linux-2.6.5-psargs/drivers/md/dm-path-selector.h
--- linux-2.6.5-orig/drivers/md/dm-path-selector.h	2004-04-18 20:34:44.000000000 -0700
+++ linux-2.6.5-psargs/drivers/md/dm-path-selector.h	2004-04-18 22:13:27.980742649 -0700
@@ -31,7 +31,8 @@ struct path_selector {
 /*
  * Constructs a path selector object, takes custom arguments
  */
-typedef int (*ps_ctr_fn) (struct path_selector *ps);
+typedef int (*ps_ctr_fn) (struct path_selector *ps, int argc, char **argv,
+			  char **error);
 typedef void (*ps_dtr_fn) (struct path_selector *ps);
 
 /*
@@ -69,10 +70,13 @@ typedef	void (*ps_update_path_fn) (struc
  * Table content based on parameters added in ps_add_path_fn
  * or path selector status
  */
-typedef	int (*ps_status_fn) (struct path_selector *ps,
-			     struct path *path,
-			     status_type_t type,
-			     char *result, unsigned int maxlen);
+typedef	int (*ps_path_status_fn) (struct path_selector *ps,
+				  struct path *path,
+				  status_type_t type,
+				  char *result, unsigned int maxlen);
+typedef	int (*ps_selector_status_fn) (struct path_selector *ps,
+				      status_type_t type,
+				      char *result, unsigned int maxlen);
 
 /* Information about a path selector type */
 struct path_selector_type {
@@ -86,7 +90,8 @@ struct path_selector_type {
 	ps_add_path_fn add_path;
 	ps_update_path_fn update_path;
 	ps_select_path_fn select_path;
-	ps_status_fn status;
+	ps_path_status_fn path_status;
+	ps_selector_status_fn ps_status;
 };
 
 /*