From abd3c16d13ad3e7d13cb96e17d5ff903363fb253 Mon Sep 17 00:00:00 2001
From: Christophe Varoqui <christophe.varoqui@free.fr>
Date: Tue, 19 Jun 2007 00:49:36 +0200
Subject: [PATCH] [libchecker] restore synchronous checker operation to
 async-capable checkers

Add a "sync" flag the struct checker to inform the checker the caller wants a synchronous or asynchronous answer to path status request.

Default value is "synchronous" to kept legacy code unchanged.

Set async mode in the daemon checker loop.
---
 libcheckers/checkers.c | 19 ++++++++++++++++++-
 libcheckers/checkers.h |  3 +++
 libcheckers/directio.c | 11 ++++++++---
 multipathd/main.c      |  7 ++++++-
 4 files changed, 35 insertions(+), 5 deletions(-)

diff --git a/libcheckers/checkers.c b/libcheckers/checkers.c
index a49ad59..d7728a5 100644
--- a/libcheckers/checkers.c
+++ b/libcheckers/checkers.c
@@ -13,6 +13,7 @@
 static struct checker checkers[] = {
 	{
 		.fd         = 0,
+		.sync       = 1,
 		.name       = DIRECTIO,
 		.message    = "",
 		.context    = NULL,
@@ -22,6 +23,7 @@ static struct checker checkers[] = {
 	},
 	{
 		.fd         = 0,
+		.sync       = 1,
 		.name       = TUR,
 		.message    = "",
 		.context    = NULL,
@@ -31,6 +33,7 @@ static struct checker checkers[] = {
 	},
 	{
 		.fd         = 0,
+		.sync       = 1,
 		.name       = HP_SW,
 		.message    = "",
 		.context    = NULL,
@@ -40,6 +43,7 @@ static struct checker checkers[] = {
 	},
 	{
 		.fd         = 0,
+		.sync       = 1,
 		.name       = EMC_CLARIION,
 		.message    = "",
 		.context    = NULL,
@@ -49,6 +53,7 @@ static struct checker checkers[] = {
 	},
 	{
 		.fd         = 0,
+		.sync       = 1,
 		.name       = RDAC,
 		.message    = "",
 		.context    = NULL,
@@ -58,6 +63,7 @@ static struct checker checkers[] = {
 	},
 	{
 		.fd         = 0,
+		.sync       = 1,
 		.name       = READSECTOR0,
 		.message    = "",
 		.context    = NULL,
@@ -65,7 +71,7 @@ static struct checker checkers[] = {
 		.init       = readsector0_init,
 		.free       = readsector0_free
 	},
-	{0, "", "", NULL, NULL, NULL, NULL},
+	{0, 1, "", "", NULL, NULL, NULL, NULL},
 };
 
 void checker_set_fd (struct checker * c, int fd)
@@ -73,6 +79,16 @@ void checker_set_fd (struct checker * c, int fd)
 	c->fd = fd;
 }
 
+void checker_set_sync (struct checker * c)
+{
+	c->sync = 1;
+}
+
+void checker_set_async (struct checker * c)
+{
+	c->sync = 0;
+}
+
 struct checker * checker_lookup (char * name)
 {
 	struct checker * c = &checkers[0];
@@ -134,6 +150,7 @@ struct checker * checker_default (void)
 void checker_get (struct checker * dst, struct checker * src)
 {
 	dst->fd = src->fd;
+	dst->sync = src->sync;
 	strncpy(dst->name, src->name, CHECKER_NAME_LEN);
 	strncpy(dst->message, src->message, CHECKER_MSG_LEN);
 	dst->check = src->check;
diff --git a/libcheckers/checkers.h b/libcheckers/checkers.h
index b0e2a62..482ffb8 100644
--- a/libcheckers/checkers.h
+++ b/libcheckers/checkers.h
@@ -86,6 +86,7 @@
 
 struct checker {
 	int fd;
+	int sync;
 	char name[CHECKER_NAME_LEN];
 	char message[CHECKER_MSG_LEN];       /* comm with callers */
 	void * context;                      /* store for persistent data */
@@ -101,6 +102,8 @@ struct checker {
 int checker_init (struct checker *, void **);
 void checker_put (struct checker *);
 void checker_reset (struct checker * c);
+void checker_set_sync (struct checker * c);
+void checker_set_async (struct checker * c);
 void checker_set_fd (struct checker *, int);
 struct checker * checker_lookup (char *);
 int checker_check (struct checker *);
diff --git a/libcheckers/directio.c b/libcheckers/directio.c
index db19881..ee09af7 100644
--- a/libcheckers/directio.c
+++ b/libcheckers/directio.c
@@ -118,7 +118,7 @@ void directio_free (struct checker * c)
 }
 
 static int
-check_state(int fd, struct directio_context *ct)
+check_state(int fd, struct directio_context *ct, int sync)
 {
 	struct timespec	timeout = { .tv_nsec = 5 };
 	struct io_event event;
@@ -129,6 +129,11 @@ check_state(int fd, struct directio_context *ct)
 	if (fstat(fd, &sb) == 0) {
 		LOG(4, "called for %x", (unsigned) sb.st_rdev);
 	}
+	if (sync) {
+		LOG(4, "called in synchronous mode");
+		timeout.tv_sec  = ASYNC_TIMEOUT_SEC;
+		timeout.tv_nsec = 0;
+	}
 
 	if (!ct->running) {
 		struct iocb *ios[1] = { &ct->io };
@@ -147,7 +152,7 @@ check_state(int fd, struct directio_context *ct)
 	LOG(3, "async io getevents returns %li (errno=%s)", r, strerror(errno));
 
 	if (r < 1L) {
-		if (ct->running > ASYNC_TIMEOUT_SEC) {
+		if (ct->running > ASYNC_TIMEOUT_SEC || sync) {
 			LOG(3, "abort check on timeout");
 			rc = PATH_DOWN;
 		} else
@@ -169,7 +174,7 @@ int directio (struct checker * c)
 	if (!ct)
 		return PATH_UNCHECKED;
 
-	ret = check_state(c->fd, ct);
+	ret = check_state(c->fd, ct, c->sync);
 
 	switch (ret)
 	{
diff --git a/multipathd/main.c b/multipathd/main.c
index a574bee..5f98c33 100644
--- a/multipathd/main.c
+++ b/multipathd/main.c
@@ -888,11 +888,16 @@ checkerloop (void *ap)
 				pathinfo(pp, conf->hwtable, DI_SYSFS);
 				select_checker(pp);
 			}
-
 			if (!checker_selected(&pp->checker)) {
 				condlog(0, "%s: checker is not set", pp->dev);
 				continue;
 			}
+			/*
+			 * Set checker in async mode.
+			 * Honored only by checker implementing the said mode.
+			 */
+			checker_set_async(&pp->checker);
+
 			newstate = checker_check(&pp->checker);
 			
 			if (newstate < 0) {
-- 
2.7.4