1) Only one tag with a particular name can be attached to a device
at a time. This significantly simplifies the library, and was needed
to allow the cache file to be re-read and changes integrated into the
in-core version of the data structure in a simpler fashion than earlier
versions of the library.
2) To accomodate this, the ext2/ext3 filesystems are now always tagged
as "ext2" type filesystems. Ext3 filesystems are tagged with a
SEC_TYPE tag with the value ext3.
3) The new blkid_read_cache() function checks the mod time of the
cache file, and if the file has been changed since the last time the
cache file was read into memory, it is re-read. This function is now
called before probing all of the devices in the system or searching
all devices in the cache for a specific tag value.
4) After probing all devices, blkid_flush_cache() is called to write
out the cache file. This assures that all of the hard work involved
in doing a blkid_probe_all() is saved to disk.
Theodore Ts'o