Track Linux filesystem id (FSID) for quiesced (frozen) filesystems

Track Linux filesystem id (FSID) for quiesced (frozen) filesystems

Tracking the filesystem FSID along with each file descriptor (FD)
as the ioctl FIFREEZE is done.  An EBUSY could be seen because of
an attempt to freeze the same superblock more than once depending
on the OS configuration (e.g. usage of bind mounts).  An EBUSY could
also mean another process has locked or frozen that filesystem.

When an EBUSY is received, the filesyste FSID is checked against the
list of filesystems that have already be quiesced.  If not previously
seen, a warning that the filesystem is controlled by another process
is logged and the quiesced snapshot request will be rejected.