[求助] openwrt 挂载， 只能一个分区，挂载另一个分区一直报错，求大神给个建议

路由器上插了个 8 G U 盘，格式化 ext4 类型，之前创建了两个分区，sda1 1G，用来安装程序
sda2 2G 做交换分区，都没有问题

还剩下 4G 一直没用，想着做个 samba 或者 NFS 放点东西试试，于是剩下的存储创建了 sda3，
但是一直挂载不成功，提示

root@OpenWrt:~# mount /dev/sda3 /mnt/sdc3
mount: mounting /dev/sda3 on /mnt/sdc3 failed: Invalid argument

root@OpenWrt:~# dmesg|grep sda
[ 9.140000] sd 0:0:0:0: [sda] 15144960 512-byte logical blocks: (7.75 GB/7.22 GiB)
[ 9.150000] sd 0:0:0:0: [sda] Write Protect is off
[ 9.150000] sd 0:0:0:0: [sda] Mode Sense: 2f 00 00 00
[ 9.150000] sd 0:0:0:0: [sda] Write cache: disabled, read cache: enabled, doesn't support DPO or FUA
[ 9.170000] sda: sda1 sda2 sda3
[ 9.200000] sd 0:0:0:0: [sda] Attached SCSI removable disk
[ 12.600000] EXT4-fs (sda): no journal found
[ 12.620000] EXT4-fs (sda1): warning: maximal mount count reached, running e2fsck is recommended
[ 12.640000] EXT4-fs (sda1): mounted filesystem with ordered data mode. Opts:

root@OpenWrt:~# df
Filesystem 1K-blocks Used Available Use% Mounted on
rootfs 4928 4824 104 98% /
/dev/root 2048 2048 0 100% /rom
tmpfs 30704 596 30108 2% /tmp
/dev/mtdblock3 4928 4824 104 98% /overlay
overlayfs:/overlay 4928 4824 104 98% /
tmpfs 512 0 512 0% /dev
/dev/sda1 1010016 120316 820344 13% /mnt/sdc1

谢谢