Gesendet: Montag, 29. März 2021 um 01:02 Uhr
Von: "Chris Murphy" [off-list ref]
An: "B A" [off-list ref]
Cc: "Btrfs BTRFS" <redacted>
Betreff: Re: Help needed with filesystem errors: parent transid verify failed

On Sun, Mar 28, 2021 at 9:41 AM B A [off-list ref] wrote:

quoted

Dear btrfs experts,


On my desktop PC, I have 1 btrfs partition on a single SSD device with 3 subvolumes (/, /home, /var). Whenever I boot my PC, after logging in to GNOME, the btrfs partition is being remounted as ro due to errors. This is the dmesg output at that time:

quoted

[ 616.155392] BTRFS error (device dm-0): parent transid verify failed on 1144783093760 wanted 2734307 found 2734305
[ 616.155650] BTRFS error (device dm-0): parent transid verify failed on 1144783093760 wanted 2734307 found 2734305
[ 616.155657] BTRFS: error (device dm-0) in __btrfs_free_extent:3054: errno=-5 IO failure
[ 616.155662] BTRFS info (device dm-0): forced readonly
[ 616.155665] BTRFS: error (device dm-0) in btrfs_run_delayed_refs:2124: errno=-5 IO failure

transid error usually means something below Btrfs got the write
ordering wrong and one or more writes dropped, but the problem isn't
detected until later which means it's an older problem. What's the
oldest kernel this file system has been written with? That is, is it a
new Fedora 33 file system? Or older? Fedora 33 came with 5.8.15.

This is a very old BTRFS filesystem created with Fedora *23* i.e. a linux kernel and btrfs-progs around version 4.2. It was probably created 2015-10-31 with Fedora 23 beta and kernel 4.2.4 or 4.2.5.

I ran `btrfs scrub` about a month ago without issues. I ran `btrfs check` maybe a year ago without issues. I also run `btrfs filesystem balance` from time to time (~once a year). None of these have shown the issue before. Does that mean that the issue has not been present for a long time (>1 year)?

ERROR: child eb corrupted: parent bytenr=1144783093760 item=14 parent
level=1 child level=2
ERROR: child eb corrupted: parent bytenr=1144881201152 item=14 parent
level=1 child level=2

Can you post the output from both:

btrfs insp dump-t -b 1144783093760 /dev/dm-0

See attached file "btrfs_insp_dump-t_[…]x60.txt"

btrfs insp dump-t -b 1144881201152 /dev/dm-0

See attached file "btrfs_insp_dump-t_[…]x52.txt"

quoted

What shall I do now? Do I need any of the invasive methods (`btrfs rescue` or `btrfs check --repair`) and if yes, which method do I choose?

No repairs yet until we know what's wrong and if it's safe to try to repair it.

In the meantime I highly recommend refreshing backups of /home in case
this can't be repaired. It might be easier to do this with a Live USB
boot of Fedora 33, and use 'mount -o ro,subvol=home /dev/dm-0
/mnt/home' to mount your home read-only to get a backup. Live
environment will be more cooperative.
--
Chris Murphy

Thanks for your help so far!

Kind regards,
Chris