Actually i had the same error but using idevicerestore on linux (only got a ubuntu XD) the error message is very clear:
BlockFindAll: found 926 blocks but needed 28996
Disk full error
* The volume Data could not be repaired.
volume type is pure HFS+
primary MDB is at block 0 0x00
alternate MDB is at block 0 0x00
primary VHB is at block 2 0x02
alternate VHB is at block 25380774 0x18347a6
sector size = 512 0x200
VolumeObject flags = 0x07
total sectors for volume = 25380776 0x18347a8
total sectors for embedded volume = 0 0x00
CheckHFS returned 8, fsmodified = 0
fsck failed on /dev/disk0s1s2
leaving fsck_filesystems, returning 26
Looks like this error indicates a broken filesystem...