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    SubjectRe: Multidevice f2fs mount after disk rearrangement
    On 01/04, Oleksandr Natalenko wrote:
    > Hi.
    >
    > On 04.01.2020 17:29, Oleksandr Natalenko wrote:
    > > I was brave enough to create f2fs filesystem spanning through 2
    > > physical device using this command:
    > >
    > > # mkfs.f2fs -t 0 /dev/sdc -c /dev/sdd
    > >
    > > It worked fine until I removed /dev/sdb from my system, so f2fs devices
    > > became:
    > >
    > > /dev/sdc -> /dev/sdb
    > > /dev/sdd -> /dev/sdc
    > >
    > > Now, when I try to mount it, I get the following:
    > >
    > > # mount -t f2fs /dev/sdb /mnt/fs
    > > mount: /mnt/fs: mount(2) system call failed: No such file or directory.
    > >
    > > In dmesg:
    > >
    > > [Jan 4 17:25] F2FS-fs (sdb): Mount Device [ 0]: /dev/sdc,
    > > 59063, 0 - 1cd6fff
    > > [ +0,000024] F2FS-fs (sdb): Failed to find devices
    > >
    > > fsck also fails with the following assertion:
    > >
    > > [ASSERT] (init_sb_info: 908) !strcmp((char *)sb->devs[i].path, (char
    > > *)c.devices[i].path)
    > >
    > > Am I doing something obviously stupid, and the device path can be
    > > (somehow) changed so that the mount succeeds, or this is unfixable,
    > > and f2fs relies on persistent device naming?
    > >
    > > Please suggest.
    > >
    > > Thank you.
    >
    > Erm, fine. I studied f2fs-tools code a little bit and discovered that
    > superblock indeed had /dev/sdX paths saved as strings. So I fired up hexedit
    > and just changed the superblock directly on the first device, substituting
    > sdc with sdb and sdd with sdc (I did it twice; I guess there are 2 copies of
    > superblock), and after this the mount worked.
    >
    > Am I really supposed to do this manually ;)?

    Thank you for investigating this ahead of me. :) Yes, the device list is stored
    in superblock, so hacking it manually should work.

    Let me think about a tool to tune that.

    Thanks,

    >
    > --
    > Oleksandr Natalenko (post-factum)

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