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sjox

Member

Registered: 2025-09-16

Posts: 4  

Inode No. 12

With the new update (Debian 13.2) an updated Cups is also included!
This installs a file "dnssd" in the directory "/usr/lib/cups/backend-available/" and two further hard links
in the directory "/usr/lib/cups/backend"! (dnssd and mdns). The Inode was 12!
Of course you can view these files or directories using "ls -li"!
But that changes after a reboot!
If I try to list this directory on my PC using "ls -l" I get the message: "The structure must be cleaned up"!
(dnssd is only displayed with ? and the file system is shot!!)
Then I get the message for each following command: "input/output error"
A following "fsck.ext4 -y -f /dev/nvme0n1p3" reports "invalid inode 12".

(I noticed this problem due to an AIDE check - after this check the filesystem was shot!)

The question now is how a simple "ls -l" can shoot the whole file system?
(It must be because of the Inode 12!)
I helped myself by simply reinstalling cups using "--reinstall".
This gave the file (and the two hardlinks) another inode!
However, if I install Cups a third time - Inode 12 is active again!
Therefore, 12 is always preferred - except for this inode is already in use!
I was also able to replicate this with other files.
For example, as soon as I copy a normal text file into this directory, this file had the inode 12!
With the command "find / -inum 12" I also found other system files!

Now my questions:
Why is it that Inode 12 is awarded?
Apparently, this is only intended for system-related files!
Also, this behavior occurs in others or I am the only one

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He who asks is a fool for five minutes. He who does not ask remains a fool forever.
- Chinese proverb

g4sra

Member

Registered: 2018-12-12

Posts: 76  

Re: Inode No. 12

find / -xdev -inum 12

stultumanto

Member

Registered: 2023-12-12

Posts: 105  

Re: Inode No. 12

OK, I have no idea what this is really about, but you have me curious. I checked three different Linux installations on ext4, and none had inodes 3-10 or 12. In every case, / was inode 2, /lost+found was inode 11, and everything else was inodes 13 & up. I can't find anything about this subject with any search engine.

sjox

Member

Registered: 2025-09-16

Posts: 4  

Re: Inode No. 12

As it looks, not many should have this problem!
I'm probably the only one...

Thanks to "g4sra" and "stultumanto"!

The result of "find":

find / -xdev -inum 12
/usr/lib/cups/backend-available/Hello_No12.txt

It's the only with Inode 12!

or:

find / -inum 12
/dev/console
/sys/hypervisor
/sys/fs/cgroup/memory.pressure
/usr/lib/cups/backend-available/Hello_No12.txt
/run/user/1000/at-spi/bus_0

Then I rebooted and started immediately from the "Devuan-Excalibur-Live-System" (Ventoy)!
(so it was NOT booted from the built-in SSD)

The result:

fsck.ext4 -n -f /dev/nvme0n1p3
e2fsck 1.47.2 (1-Jan-2025)
Pass 1: Checking inodes, blocks, and sizes
Orphan file inode 12 is not in use, but contains data.  Clear? no

Pass 2: Checking directory structure
Entry 'Hello_No12.txt' in /usr/lib/cups/backend-available (26756) has invalid inode #: 12.
Clear? no

Pass 3: 

and so on...

The SSD was shot down already when driving down!

The result is always the same - no matter what directory - as soon as Inode number 12 is assigned anywhere,
then the file system is shot.

That's why I've also asked the artificial intelligence (https://you.com/?chatMode default)

I have shortened the answer:

Summary:
    • Inodes 1–11 are reserved for special purposes in ext4.
    • Inode assignment is automatic and based on the first available inode.
    • You cannot directly control inode numbers during file creation.
    • Consistent problems with inode 12 suggest underlying file system corruption or hardware issues .
    • Inode 12 corresponds to one specific file or directory at a time.
    • The inode stores metadata, not the filename.
    • Filenames are directory entries that point to inode numbers.
    • Multiple filenames can share the same inode (hard links).
    • When a file is deleted, its inode number (like 12) can be reused for new files.

This explains why your copied file often gets inode 12:
it is the first free inode available after the reserved ones, and inode 12 is assigned to the new
file until it is deleted or the file system changes.

Recommendation:
Consider running a thorough fsck and, if possible, reformatting the file system to ensure there is no
persistent corruption. If the problem persists, it may be a hardware issue or a bug in the file system implementation.

This sounds plausible - so I will format the SSD and reset the system!

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He who asks is a fool for five minutes. He who does not ask remains a fool forever.
- Chinese proverb