USB flash drive opens read only -- how to fix?

[Ken Heard <ken@heard.name>]

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Messieurs et mesdames:

Command 'mount' returns among other things the following two lines:

/dev/mapper/fde on /media/fde type ext2\
(rw,nosuid,nodev,noexec,noatime,block_validity,barrier,user_xattr,acl)

/dev/mapper/fdc on /media/fdc type ext2\
(ro,nosuid,nodev,noexec,noatime,block_validity,barrier,user_xattr,acl)

The first line above (divided into two here) is what 'mount' shows for
all my encrypted USB flash drives when opened -- they are all opened
with 'rw'.

The second lino above is what is shown for only one of my incrypted
USB flash drives; it opens with 'ro'.  When this drive is opened and
mounted the message returned is 'mount: /dev/mapper/fdc is
write-protected, mounting read-only'.

This situation is very strange.  Something somewhere causes this drive
to be opened 'ro' instead of the 'rw' specified for this mount point
in file /etc/fstab.

Not only can I not find out where I cannot find a way make this drive
'rw'. It is consequently useless.  Among the workarounds I tried are:

- - the commands 'sudo chmod' to change permissions.  (I own the
  directories and files in the drive.)

- - after dismounting the drive but keeping the encryption open running
 'sudo mount -o remount,rw /media/fdc' which returns the same message
  mentioned above: 'mount: /dev/mapper/fdc is write-protected, mounting
  read-only'.

- - after unmounting and closing encryption running as root 'wipefs -a -f
  /dev/sdd' returns 'wipefs: error: /dev/sdd: probing initialization
  failed: Read-only file system'.

- - 'sudo luksformat -t ext2' /dev/sdd after going through the
  preliminaries returns 'Could not create LUKS device /dev/sdd
  at /usr/sbin/luksformat line 91, <MOUNTS> line 30'

- - 'sudo mkfs.ext2 /dev/sdd' after asking if I really want to go ahead
   with this command returns '/dev/sdd: Read-only file system while
   setting up superblock'.

After some on line searches it appears that to regain use of this
flash drive (it contains no essential data) I will have to go through
several steps to erase LUKS and then use the 'dd' command to wipe the
drive clean.  I am still afraid to use that command because of the
potential damage that can be caused by one or more bad 'if' and 'of'
settings if there is not an easier way.  Does anyone here know of one?
 In any event I would surely know how this situation would arise in
the first place.

Regards, Ken Heard

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