Subject: Re: Run mkfs.ext4 on an already existing ext4 filesystem. Seeking
 professional help or programming hints for the recovery.
To:     Andrea Lo Pumo <alopumo@movia.biz>, linux-ext4@vger.kernel.org
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From:   Reindl Harald <h.reindl@thelounge.net>
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Date:   Thu, 11 Apr 2019 11:42:57 +0200
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Am 11.04.19 um 11:37 schrieb Andrea Lo Pumo:
> Sorry for writing on this development mailing list, we are seeking an
> expert in ext4, we are also willing to offer a professional contract
> to solve this issue.
> 
> On /dev/sda1(*) there was an ext4 file system with a lot of large
> files. Now, by mistake, mkfs.ext4 has been run on /dev/sda1. The
> result is that now /dev/sda1 is "empty": mounting it shows no files.
> 
> Note *: actually, it is /dev/mapper/secure_storage, an encrypted
> volume opened with LUKS: cryptsetup luksOpen /dev/sda1 secure_storage
> 
> This is my current understanding:
> 
> - Originally, /dev/sda1 was created with "mkfs.ext4 /dev/sda1"
> - Now, the second "mkfs.ext4 /dev/sda1" has overwritten the
> superblock, and all backups of the superblock (because it has created
> the backups of the NEW superblock at the exact same locations of the
> previous superblock backups)

no

you said you had a LUKS volume on /dev/sda1 which means by directly
create a fs on /dev/sda1 you have overwritten parts of the encryption
layer *and* at the same time the filesystem *on top* of it

in other words: you are done, can stop seek solutions and start restore
your backups