From: Chris Murphy <lists@colorremedies.com>
To: Shapranov Vladimir <equidamoid@gmail.com>
Cc: Btrfs BTRFS <linux-btrfs@vger.kernel.org>,
Qu Wenruo <quwenruo.btrfs@gmx.com>
Subject: Re: Recovery options for damaged beginning of the filesystem
Date: Wed, 10 Oct 2018 20:40:45 -0600 [thread overview]
Message-ID: <CAJCQCtSUWe6sFLQr2JnEQPfRjSC4KBhMTY_ko1wt2pGJ3PMxow@mail.gmail.com> (raw)
In-Reply-To: <1a39748c-19de-5fdc-f8ee-efdced880df4@gmail.com>
On Tue, Oct 9, 2018 at 10:47 PM, Shapranov Vladimir
<equidamoid@gmail.com> wrote:
> Hi,
>
> I've got a filesystem with first ~50Mb accidentally dd'ed.
>
> "btrfs check" fails with a following error (regardless of "-s"):
> checksum verify failed on 21037056 found FC8A6557 wanted 2F51D090
> checksum verify failed on 21037056 found FC8A6557 wanted 2F51D090
> checksum verify failed on 21037056 found 1EDD5E47 wanted 222F7E7F
> checksum verify failed on 21037056 found 1EDD5E47 wanted 222F7E7F
> bytenr mismatch, want=21037056, have=13515002166904211737
> ERROR: cannot read chunk root
> ERROR: cannot open file system
>
> "mount -o ro /dev/sdf1 /mnt/tmp" fails, while "mount -o ro,subvol=X /mnt/tmp" succeeds for "/" and couple subvolumes.
What do you get for 'btrfs rescue super -v /dev/sdf1' ?
I thought the kernel code will not mount a Btrfs if the first super is
not present or valid (checksum match)?
--
Chris Murphy
prev parent reply other threads:[~2018-10-11 2:40 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-10-10 4:47 Recovery options for damaged beginning of the filesystem Shapranov Vladimir
2018-10-10 23:50 ` Qu Wenruo
2018-10-11 2:40 ` Chris Murphy [this message]
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