discover: Mount snapshots for all eligible disk devices

Device-mapper snapshots are created for all disk devices prior to
being mounted. If explicit writes are made to the snapshot they are
merged back to the disk once write access is released.

Signed-off-by: Samuel Mendoza-Jonas <sam.mj@au1.ibm.com>

1 files changed, 18 insertions, 2 deletions

diff --git a/discover/udev.c b/discover/udev.c
index 6ccb8d4..75393d5 100644
--- a/discover/udev.c
+++ b/discover/udev.c
@@ -25,6 +25,7 @@
 #include "pb-discover.h"
 #include "device-handler.h"
 #include "cdrom.h"
+#include "devmapper.h"
 
 /* We set a default monitor buffer size, as we may not process monitor
  * events while performing device discvoery. systemd uses a 128M buffer, so
@@ -94,12 +95,16 @@ static int udev_handle_block_add(struct pb_udev *udev, struct udev_device *dev,
 
 	node = udev_device_get_devnode(dev);
 	path = udev_device_get_devpath(dev);
-	if (path && (strstr(path, "virtual/block/loop")
-			|| strstr(path, "virtual/block/ram"))) {
+	if (path && strstr(path, "virtual/block/loop")) {
 		pb_log("SKIP: %s: ignored (path=%s)\n", name, path);
 		return 0;
 	}
 
+	if (path && strstr(path, "virtual/block/ram")) {
+		device_handler_add_ramdisk(udev->handler, node);
+		return 0;
+	}
+
 	cdrom = node && !!udev_device_get_property_value(dev, "ID_CDROM");
 	if (cdrom) {
 		/* CDROMs require a little initialisation, to get
@@ -111,6 +116,14 @@ static int udev_handle_block_add(struct pb_udev *udev, struct udev_device *dev,
 		}
 	}
 
+	/* If our environment's udev can recognise them explictly skip any
+	 * device mapper devices we encounter */
+	const char *devname = udev_device_get_property_value(dev, "DM_NAME");
+	if (devname) {
+		pb_log("SKIP: dm-device %s\n", devname);
+		return 0;
+	}
+
 	type = udev_device_get_property_value(dev, "ID_FS_TYPE");
 	if (!type) {
 		pb_log("SKIP: %s: no ID_FS_TYPE property\n", name);
@@ -142,6 +155,9 @@ static int udev_handle_block_add(struct pb_udev *udev, struct udev_device *dev,
 
 	udev_setup_device_params(dev, ddev);
 
+	if (ddev->device->type == DEVICE_TYPE_DISK)
+		devmapper_init_snapshot(udev->handler, ddev);
+
 	device_handler_discover(udev->handler, ddev);
 
 	return 0;