Add default udev rules.

Update dm-ioctl.h comments.

1 files changed, 44 insertions, 0 deletions

diff --git a/udev/10-dm.rules.in b/udev/10-dm.rules.in
new file mode 100644
index 000000000..e0de5d3ee
--- /dev/null
+++ b/udev/10-dm.rules.in
@@ -0,0 +1,44 @@
+# Udev rules for device-mapper devices.
+#
+# These rules create a DM control node in /dev/(DM_DIR) directory.
+# The rules also create nodes named dm-x (x is a number) in /dev
+# directory and symlinks to these nodes with names given by
+# the actual DM names. Some udev environment variables are set
+# for use in later rules:
+#   DM_NAME - actual DM device's name
+#   DM_UUID - UUID set for DM device (blank if not specified)
+#   DM_SUSPENDED - suspended state of DM device (0 or 1)
+
+KERNEL=="device-mapper", NAME="(DM_DIR)/control"
+
+SUBSYSTEM!="block", GOTO="dm_end"
+KERNEL!="dm-[0-9]*", GOTO="dm_end"
+ACTION!="add|change", GOTO="dm_end"
+
+# Normally, we operate on "change" events only. But when
+# coldplugging, there's an "add" event present. We have to
+# recognize this and do our actions in this particular
+# situation, too. Also, we don't want the nodes to be
+# created prematurely on "add" events while not coldplugging.
+ACTION=="add", ENV{STARTUP}!="1", NAME="", GOTO="dm_end"
+
+# "dm" sysfs subdirectory is available in newer versions of DM
+# only (kernels >= 2.6.29). We have to check for its existence
+# and use dmsetup tool instead to get the DM name, uuid and 
+# suspended state if the "dm" subdirectory is not present.
+# The "suspended" item was added even later (kernels >= ???),
+# so we also have to call dmsetup if the kernel version used
+# is in between these releases.
+TEST=="dm", ENV{DM_NAME}="$attr{dm/name}", ENV{DM_UUID}="$attr{dm/uuid}", ENV{DM_SUSPENDED}="$attr{dm/suspended}"
+TEST!="dm", IMPORT{program}="/sbin/dmsetup info -j %M -m %m -c --nameprefixes --noheadings --rows -o name,uuid,suspended"
+ENV{DM_SUSPENDED}!="?*", IMPORT{program}="/sbin/dmsetup info -j %M -m %m -c --nameprefixes --noheadings --rows -o suspended"
+
+# dmsetup tool provides suspended state information in textual
+# form with values "Suspended"/"Active". We translate it to
+# 0/1 respectively to be consistent with sysfs values.
+ENV{DM_SUSPENDED}=="Active", ENV{DM_SUSPENDED}="0"
+ENV{DM_SUSPENDED}=="Suspended", ENV{DM_SUSPENDED}="1"
+
+ENV{DM_NAME}=="?*", NAME="$kernel", SYMLINK+="(DM_DIR)/$env{DM_NAME}"
+
+LABEL="dm_end"