bueno, en este rato, he borrado la carpeta efs y la he vuelto a crear como me dijistes y al montar me da el mismo error que antes...
~ # busybox mke2fs /dev/block/mmcblk0p3
busybox mke2fs /dev/block/mmcblk0p3
Filesystem label=
OS type: Linux
Block size=1024 (log=0)
Fragment size=1024 (log=0)
5136 inodes, 20480 blocks
1024 blocks (5%) reserved for the super user
First data block=1
Maximum filesystem blocks=262144
3 block groups
8192 blocks per group, 8192 fragments per group
1712 inodes per group
Superblock backups stored on blocks:
8193
~ # busybox mount -w -t ext4 /dev/block/mmcblk0p3 /efs
busybox mount -w -t ext4 /dev/block/mmcblk0p3 /efs
mount: mounting /dev/block/mmcblk0p3 on /efs failed: File too large
estoy desesperado, espero poder arreglarlo...