Mount with Umask Not Working – Troubleshooting

mountnvmepermissionsumask

I tried to run

mount /home/user/nvme0n1 -U 8da513ec-20ce-4a2d-863d-978b60089ad3 -t ext4 -o umask=0000

and the response is:

mount: /home/user/nvme0n1: wrong fs type, bad option, bad superblock
on /dev/nvme0n1, missing codepage or helper program, or other error.

However, when I remove the umask option, the SSD is mounted as desired.
What should I do? How can I start debugging the problem? I want the device to have mode=777.

Best Answer

You're mounting an ext4 filesystem:

... -t ext4 -o umask=0000

Per the ext4(5) man page, the ext4 filesystem does not have a umask mount option.

I want the device to have mode=777.

If you need different permissions on files and/or directories, you can set file/directory permissions on the files/directories themselves. See What are the different ways to set file permissions etc on gnu/linux.

1. blkid

Works whether device is mounted or not.

$ blkid
/dev/sda1: UUID="XXXX" TYPE="ext4" 
/dev/sda2: UUID="XXXX" TYPE="LVM2_member"

2. mount

This is only useful once the block device has been mounted.

$ sudo mount | grep /dev/sda1
/dev/sda1 on /boot type ext4 (rw,relatime,seclabel,data=ordered)

3. lsblk

Shows drive topologies, but not the filesystem types on the devices.

$ sudo lsblk -a
NAME                      MAJ:MIN RM   SIZE RO TYPE MOUNTPOINT
sda                         8:0    0 465.8G  0 disk 
├─sda1                      8:1    0   500M  0 part /boot
└─sda2                      8:2    0 465.3G  0 part

tune2fs

$ tune2fs -l /dev/sda1 | grep magic
Filesystem magic number:  0xEF53

Shows the magic number associated with the device, you can look these up on this site, Linux Magic Numbers. It's also in a file, often here, /usr/share/magic. You can locate it using locate /magic.

dumpe2fs

$ sudo dumpe2fs /dev/sda1 | grep magic
dumpe2fs 1.42.7 (21-Jan-2013)
Filesystem magic number:  0xEF53

Same things apply as in tune2fs.

/dev/mounts

This is the "file" maintained by the kernel that's used to display devices that have been mounted. NOTE: many of the tools on this list are typically using the contents of this file.

$ sudo cat /proc/mounts | grep /dev/sda1
/dev/sda1 /boot ext4 rw,seclabel,relatime,data=ordered 0 0

file

You can also use the file command to display info about unmounted filesystems.

$ sudo file -s /dev/sda1
/dev/sda1: Linux rev 1.0 ext4 filesystem data, UUID=XXXX (needs journal recovery) (extents) (huge files)

An alternative syntax (as root):

$ file - </dev/sda1
/dev/stdin: Linux rev 1.0 ext4 filesystem data, UUID=XXXX (needs journal recovery) (extents) (huge files)

Your mounting issue

I'd suspect that the filesystem you're attempting to mount is not what you think it is. Either the entire device was formatted with a filesystem (/dev/sda), in which case you'd be mounting the entire drive. You can test this hypothesis like this:

$ sudo mount /dev/sda /mnt

Of if you need to explicitly tell what filesystem to use:

$ sudo mount -o ext2 /dev/sda /mnt

NOTE: This is generally not the case that an entire filesystem is laid down on the entire device, /dev/sda, rather they're partitioned into /dev/sda1, etc.

Or perhaps the drive has been partitioned. In this case you'd see these partitions with the above command lsblk, where they'd show up as /dev/sda1, /dev/sda2, etc. If that's the case for you then you'll need to mount the partition instead like so:

$ sudo mount /dev/sda1 /mnt

Again pay special attention to the formatting used on the filesystem of the device, you'll occasionally have to specify it literally to mount.

Since your output from fdisk shows that you have /dev/sda1 I'd be inclined to think that you have your filesystem on the 1st partition.

Device Boot      Start         End      Blocks   Id  System
/dev/sda1              63  1953520064   976760001   83  Linux

So mounting it like this should do the trick:

$ sudo mount -o ext2 /dev/sda1 /mnt

/etc/fstab

If the above mounting commands work then you can add this to your /etc/fstab file.

/dev/sda1 /media/HDD ext2 defaults 0 2