EXT3-fs: error loading journal

有一块U盘，做两个分区，第一个是fat的，第二个是ext3，分区时都很正常没有报错，但是mount的时候就出问题了，
错误如下：
sudo mount -t ext3 /dev/sdb2 /mnt/sd_ext/
mount: wrong fs type, bad option, bad superblock on /dev/sdb2,
missing codepage or helper program, or other error
In some cases useful info is found in syslog - try
dmesg | tail or so
使用dmesg | tail 查看log如下：
[ 59.856459] sd 3:0:0:0: [sdb] Assuming drive cache: write through
[ 59.882191] sd 3:0:0:0: [sdb] 1989120 512-byte hardware sectors: (1.01 GB/971 MiB)
[ 59.891505] sd 3:0:0:0: [sdb] Write Protect is off
[ 59.891510] sd 3:0:0:0: [sdb] Mode Sense: 0b 00 00 08
[ 59.891514] sd 3:0:0:0: [sdb] Assuming drive cache: write through
[ 59.891520] sdb: sdb1 sdb2
[ 59.907087] sd 3:0:0:0: [sdb] Attached SCSI removable disk
[ 59.907168] sd 3:0:0:0: Attached scsi generic sg2 type 0
[ 100.981954] JBD: no valid journal superblock found
[ 100.981960] EXT3-fs: error loading journal.