[dm-devel] Re: patch to CLARiiON path checker to handle inactive snapshhots

[Christophe Varoqui <christophe varoqui free fr>]

Le vendredi 10 novembre 2006 à 18:02 -0500, Edward Goggin a écrit :
...

Ok, I aknowledge this approach is far more complex than your 1st
attempt.

If I read correctly the two candidate patches, the clariion checker need
to share information with the other path chechers attached to the same
multipath to decide for a state to return.

If so, let's pretend another checker might one day stress the same
need :)

What do you think of a facility like the following (completely untested
and surely semi-bogus) patch sketches ? Would it make your patch as
straight as your first attempt ?

It seems to take care of our griefs with "container_of" and the
clariion-centric additions to "struct multipath".

Anyway, I'm sorry for keeping you walking in circles there.
Regards,
cvaroqui




diff --git a/libcheckers/checkers.c b/libcheckers/checkers.c
index 53770a6..ee4d7fb 100644
--- a/libcheckers/checkers.c
+++ b/libcheckers/checkers.c
@@ -75,8 +75,9 @@ struct checker * checker_lookup (char * 
 	return NULL;
 }
 
-int checker_init (struct checker * c)
+int checker_init (struct checker * c, void * mpctxt)
 {
+	c->mpcontext = mpctxt;
 	return c->init(c);
 }
 
diff --git a/libcheckers/checkers.h b/libcheckers/checkers.h
index 15bac1a..7b49b7a 100644
--- a/libcheckers/checkers.h
+++ b/libcheckers/checkers.h
@@ -46,6 +46,8 @@ struct checker {
 	char name[CHECKER_NAME_LEN];
 	char message[CHECKER_MSG_LEN];       /* comm with callers */
 	void * context;                      /* store for persistent data */
+	void * mpcontext;                    /* store for persistent data */
+                                             /* shared multipath-wide */
 	int (*check)(struct checker *);
 	int (*init)(struct checker *);       /* to allocate the context */
 	void (*free)(struct checker *);      /* to free the context */
@@ -53,7 +55,7 @@ struct checker {
 
 #define MSG(c, a) snprintf((c)->message, CHECKER_MSG_LEN, a);
 
-int checker_init (struct checker *);
+int checker_init (struct checker *, void *);
 void checker_put (struct checker *);
 void checker_reset (struct checker * c);
 void checker_set_fd (struct checker *, int);
diff --git a/libmultipath/discovery.c b/libmultipath/discovery.c
index 69c9bc3..1893851 100644
--- a/libmultipath/discovery.c
+++ b/libmultipath/discovery.c
@@ -610,13 +610,16 @@ static int
 get_state (struct path * pp)
 {
 	struct checker * c = &pp->checker;
+	void * mpctxt = NULL;
 
 	if (!checker_selected(c)) {
 		select_checker(pp);
 		if (!checker_selected(c))
 			return 1;
 		checker_set_fd(c, pp->fd);
-		if (checker_init(c))
+		if (pp->mpp)
+			mpctxt = pp->mpp->mpcontext;
+		if (checker_init(c, mpctxt))
 			return 1;
 	}
 	pp->state = checker_check(c);
diff --git a/libmultipath/structs.h b/libmultipath/structs.h
index faa2b8f..45dbf85 100644
--- a/libmultipath/structs.h
+++ b/libmultipath/structs.h
@@ -151,6 +151,9 @@ struct multipath {
 	unsigned int stat_map_loads;
 	unsigned int stat_total_queueing_time;
 	unsigned int stat_queueing_timeouts;
+
+	/* checkers shared data */
+	void * mpcontext;
 };
 
 struct pathgroup {