Bem, acontece que realmente foi um problema de hardware, mas foi corrigido com fsck
:
$ sudo fsck /dev/sdc6
fsck from util-linux 2.20.1
e2fsck 1.42 (29-Nov-2011)
fsck.ext2: Group descriptors look bad... trying backup blocks...
MYDISK2 was not cleanly unmounted, check forced.
Resize inode not valid. Recreate<y>? yes
Pass 1: Checking inodes, blocks, and sizes
Root inode is not a directory. Clear<y>? yes
Inode 8, i_blocks is 0, should be 262408. Fix<y>? yes
Inode 10 has a bad extended attribute block 806. Clear<y>? yes
Pass 2: Checking directory structure
Entry '..' in ??? (130049) has deleted/unused inode 2. Clear<y>? yes
Entry '..' in ??? (186945) has deleted/unused inode 2. Clear<y>? yes
...
Directories count wrong for group #24 (0, counted=18).
Fix<y>? yes
Free inodes count wrong (300724, counted=293111).
Fix<y>? yes
MYDISK2: ***** FILE SYSTEM WAS MODIFIED *****
MYDISK2: 7625/300736 files (8.7% non-contiguous), 127567/1202859 blocks
Em seguida, executar fsck
pela segunda vez é bom:
$ sudo fsck /dev/sdc6
fsck from util-linux 2.20.1
e2fsck 1.42 (29-Nov-2011)
MYDISK2: clean, 7625/300736 files, 127567/1202859 blocks
E então eu posso montar:
$ sudo udisks --mount /dev/sdc6
Mounted /org/freedesktop/UDisks/devices/sdc6 at /media/MYDISK2