Do not lookup sysfs devices in cache for 'add' eventssles10-sp4

For 'add' events the same devpath might point to a different
device, so we really shouldn't lookup the device in the cache.
Rather we should omit the cache altogether and use a new one.
For any sane operation the stale device should have received
a 'remove' event, so the cache should've been cleaned up.

References: bnc#719838

Signed-off-by: Hannes Reinecke <hare@suse.de>

5 files changed, 21 insertions, 13 deletions

diff --git a/libmultipath/discovery.c b/libmultipath/discovery.c
index f4bdbef..d7354b0 100644
--- a/libmultipath/discovery.c
+++ b/libmultipath/discovery.c
@@ -612,7 +612,7 @@ struct sysfs_device *sysfs_device_from_path(struct path *pp)
 	strlcpy(sysdev,"/block/", FILE_NAME_SIZE);
 	strlcat(sysdev,pp->dev, FILE_NAME_SIZE);
 
-	return sysfs_device_get(sysdev);
+	return sysfs_device_get(sysdev, 0);
 }
 
 extern int
diff --git a/libmultipath/sysfs.c b/libmultipath/sysfs.c
index b9621ac..576368c 100644
--- a/libmultipath/sysfs.c
+++ b/libmultipath/sysfs.c
@@ -150,7 +150,7 @@ int sysfs_resolve_link(char *devpath, size_t size)
 	return 0;
 }
 
-struct sysfs_device *sysfs_device_get(const char *devpath)
+struct sysfs_device *sysfs_device_get(const char *devpath, int add_event)
 {
 	char path[PATH_SIZE];
 	char devpath_real[PATH_SIZE];
@@ -172,9 +172,13 @@ struct sysfs_device *sysfs_device_get(const char *devpath)
 	if (lstat(path, &statbuf) != 0) {
 		/* if stat fails look in the cache */
 		dbg("stat '%s' failed: %s", path, strerror(errno));
+		/* For 'add' events the path always has to exist */
+		if (add_event)
+			return NULL;
 		list_for_each_entry(sysdev_loop, &sysfs_dev_list, node) {
 			if (strcmp(sysdev_loop->dev.devpath, devpath_real) == 0) {
-				dbg("found vanished dev in cache '%s'", sysdev_loop->dev.devpath);
+				dbg("found vanished dev in cache '%s'",
+				    sysdev_loop->dev.devpath);
 				return &sysdev_loop->dev;
 			}
 		}
@@ -183,16 +187,19 @@ struct sysfs_device *sysfs_device_get(const char *devpath)
 	if (S_ISLNK(statbuf.st_mode)) {
 		if (sysfs_resolve_link(devpath_real, sizeof(devpath_real)) != 0)
 			return NULL;
-
 	}
 
-	list_for_each_entry(sysdev_loop, &sysfs_dev_list, node) {
-		if (strcmp(sysdev_loop->dev.devpath, devpath_real) == 0) {
-			dbg("found dev in cache '%s'", sysdev_loop->dev.devpath);
+	if (!add_event) {
+		list_for_each_entry(sysdev_loop, &sysfs_dev_list, node) {
+			if (!strcmp(sysdev_loop->dev.devpath, devpath_real)) {
+				dbg("found dev in cache '%s'",
+				    sysdev_loop->dev.devpath);
 				dev = &sysdev_loop->dev;
+			}
 		}
 	}
-	if(!dev) {
+
+	if (!dev) {
 		/* it is a new device */
 		dbg("new device '%s'", devpath_real);
 		sysdev = malloc(sizeof(struct sysfs_dev));
@@ -315,7 +322,7 @@ struct sysfs_device *sysfs_device_get_parent(struct sysfs_device *dev)
 	}
 
 	/* get parent and remember it */
-	dev->parent = sysfs_device_get(parent_devpath);
+	dev->parent = sysfs_device_get(parent_devpath, 0);
 	return dev->parent;
 
 device_link:
@@ -325,7 +332,7 @@ device_link:
 		return NULL;
 
 	/* get parent and remember it */
-	dev->parent = sysfs_device_get(parent_devpath);
+	dev->parent = sysfs_device_get(parent_devpath, 0);
 	return dev->parent;
 }
 
diff --git a/libmultipath/sysfs.h b/libmultipath/sysfs.h
index e7fa3e7..aee7b2c 100644
--- a/libmultipath/sysfs.h
+++ b/libmultipath/sysfs.h
@@ -15,7 +15,7 @@ int sysfs_init(char *path, size_t len);
 void sysfs_cleanup(void);
 void sysfs_device_set_values(struct sysfs_device *dev, const char *devpath,
 			     const char *subsystem, const char *driver);
-struct sysfs_device *sysfs_device_get(const char *devpath);
+struct sysfs_device *sysfs_device_get(const char *devpath, int add_event);
 struct sysfs_device *sysfs_device_get_parent(struct sysfs_device *dev);
 struct sysfs_device *sysfs_device_get_parent_with_subsystem(struct sysfs_device *dev, const char *subsystem);
 void sysfs_device_put(struct sysfs_device *dev);
diff --git a/multipathd/cli_handlers.c b/multipathd/cli_handlers.c
index 2f36592..add716d 100644
--- a/multipathd/cli_handlers.c
+++ b/multipathd/cli_handlers.c
@@ -331,7 +331,7 @@ cli_add_map (void * v, char ** reply, int * len, void * data)
 		return 0;
 	}
 	sprintf(dev_path,"/block/dm-%d", minor);
-	sysdev = sysfs_device_get(dev_path);
+	sysdev = sysfs_device_get(dev_path, 1);
 	if (!sysdev) {
 		condlog(2, "%s: not found in sysfs", param);
 		return 0;
diff --git a/multipathd/main.c b/multipathd/main.c
index adc2d95..9ad6a44 100644
--- a/multipathd/main.c
+++ b/multipathd/main.c
@@ -629,7 +629,8 @@ uev_trigger (struct uevent * uev, void * trigger_data)
 	if (uev_discard(uev->devpath))
 		return 0;
 
-	sysdev = sysfs_device_get(uev->devpath);
+	sysdev = sysfs_device_get(uev->devpath,
+				  !strncmp(uev->action, "add", 3));
 	if(!sysdev)
 		return 0;