devcache: do not insert devices without device node

When not obtaining device from udev, we are doing deep devdir scan,
and at the same time we try to insert everything what /sys/dev/block
knows about. However in case  lvm2 is configured to use nonstardard
devdir this way it will see (and scan) devices from a real system.

lvm2 test suite is using its own test devdir with its
own device nodes. To avoid touching real /dev  devices, validate
the device node exist in give dir and do not insert such device
into a cache.

With obtain list from udev this patch has no effect
(the normal user path).

2 files changed, 10 insertions, 0 deletions

diff --git a/WHATS_NEW b/WHATS_NEW
index 777c44ee3..f4eb6ad5f 100644
--- a/WHATS_NEW
+++ b/WHATS_NEW
@@ -1,5 +1,6 @@
 Version 2.02.151
 =================================
+  When not obtaining devs from udev, check they exist before caching them.
   Detect device mismatch also when compiling without udev support.
 
 Version 2.02.150 - 9th April 2016
diff --git a/lib/device/dev-cache.c b/lib/device/dev-cache.c
index 84471ab41..6abb6a7f7 100644
--- a/lib/device/dev-cache.c
+++ b/lib/device/dev-cache.c
@@ -433,6 +433,8 @@ static struct dm_list *_get_or_add_list_by_index_key(struct dm_hash_table *idx,
 
 static struct device *_insert_sysfs_dev(dev_t devno, const char *devname)
 {
+	static struct device _fake_dev = { .flags = DEV_USED_FOR_LV };
+	struct stat stat0;
 	char path[PATH_MAX];
 	char *path_copy;
 	struct device *dev;
@@ -442,6 +444,13 @@ static struct device *_insert_sysfs_dev(dev_t devno, const char *devname)
 		return NULL;
 	}
 
+	if (lstat(path, &stat0) < 0) {
+		/* When device node does not exist return fake entry.
+		 * This may happen when i.e. lvm2 device dir != /dev */
+		log_debug("%s: Not available device node", path);
+		return &_fake_dev;
+	}
+
 	if (!(dev = _dev_create(devno)))
 		return_NULL;