I don't see how that happened. /dev/sdc has a partition table at the
beginning of the disk. That partition table contains the definition
of /dev/sdc1.
So if you ran "fsck.ext4 /dev/sdc" instead of "fsck.ext4 /dev/sdc1",
you should have gotten something like this:
root@xfstests:~# fsck.ext4 /dev/sdb
e2fsck 1.47.2-rc1 (28-Nov-2024)
ext2fs_open2: Bad magic number in super-block
fsck.ext4: Superblock invalid, trying backup blocks...
fsck.ext4: Bad magic number in super-block while trying to open /dev/sdb
The superblock could not be read or does not describe a valid ext2/ext3/ext4
filesystem. If the device is valid and it really contains an ext2/ext3/ext4
filesystem (and not swap or ufs or something else), then the superblock
is corrupt, and you might try running e2fsck with an alternate superblock:
e2fsck -b 8193 <device>
or
e2fsck -b 32768 <device>
Found a gpt partition table in /dev/sdb
In any case, fsck.ext4 will not make any changes unless you give it
permission by answering "yes". For example (do not try this at home,
kids):
root@xfstests:~# debugfs -w -R "clri <2>" /dev/sdb1 ; debugfs -w -R "ssv state 2" /dev/sdb1
debugfs 1.47.2-rc1 (28-Nov-2024)
debugfs 1.47.2-rc1 (28-Nov-2024)
root@xfstests:~# fsck.ext4 /dev/sdb1
e2fsck 1.47.2-rc1 (28-Nov-2024)
/dev/sdb1 contains a file system with errors, check forced.
Pass 1: Checking inodes, blocks, and sizes
Root inode is not a directory. Clear<y>? yes
Pass 2: Checking directory structure
Entry '..' in <2>/<11> (11) has deleted/unused inode 2. Clear<y>? yes
Pass 3: Checking directory connectivity
Root inode not allocated. Allocate<y>? yes
Unconnected directory inode 11 (was in /)
Connect to /lost+found<y>? yes
/lost+found not found. Create<y>? yes
Pass 3A: Optimizing directories
Pass 4: Checking reference counts
Inode 11 ref count is 3, should be 2. Fix<y>? yes
Pass 5: Checking group summary information
/dev/sdb1: ***** FILE SYSTEM WAS MODIFIED *****
/dev/sdb1: 13/655360 files (0.0% non-contiguous), 67263/2620928 blocks
See how fsck.ext4 asks for permission before it makes any change to
the filesystem?
