Obtain device list from udev by default if LVM2 is compiled with udev support.

Also, add a new 'obtain_device_list_from_udev' setting to lvm.conf with which
we can turn this feature on or off if needed.

If set, the cache of block device nodes with all associated symlinks
will be constructed out of the existing udev database content.
This avoids using and opening any inapplicable non-block devices or
subdirectories found in the device directory. This setting is applied
to udev-managed device directory only, other directories will be scanned
fully. LVM2 needs to be compiled with udev support for this setting to
take effect. N.B. Any device node or symlink not managed by udev in
udev directory will be ignored with this setting on.

1 files changed, 10 insertions, 0 deletions

diff --git a/doc/example.conf.in b/doc/example.conf.in
index dfc2c701..7f22a666 100644
--- a/doc/example.conf.in
+++ b/doc/example.conf.in
@@ -19,6 +19,16 @@ devices {
     # to use with LVM2.
     scan = [ "/dev" ]
 
+    # If set, the cache of block device nodes with all associated symlinks
+    # will be constructed out of the existing udev database content.
+    # This avoids using and opening any inapplicable non-block devices or
+    # subdirectories found in the device directory. This setting is applied
+    # to udev-managed device directory only, other directories will be scanned
+    # fully. LVM2 needs to be compiled with udev support for this setting to
+    # take effect. N.B. Any device node or symlink not managed by udev in
+    # udev directory will be ignored with this setting on.
+    # obtain_device_list_from_udev = 1
+
     # If several entries in the scanned directories correspond to the
     # same block device and the tools need to display a name for device,
     # all the pathnames are matched against each item in the following