Re: BTRFS discard crash: failed to run delayed ref for logical 15506102321152 num_bytes 16384 type 182 action 2 ref_mod 1: -2 6.11.2)

[Marc MERLIN <marc@merlins.org>]

One last ditch effort from Gemini:

moremagic:~# btrfs rescue zero-log /dev/mapper/crypt_bcache0
Clearing log on /dev/mapper/crypt_bcache0, previous log_root 0, level 0
moremagic:~# mount -o rw,clear_cache,skip_balance /dev/mapper/crypt_bcache0 /mnt/btrfs_bigbackup
mount: /mnt/btrfs_bigbackup: fsconfig() failed: No such file or directory.
       dmesg(1) may have more information after failed mount system call.
moremagic:~# mount -wno remount,skip_balance /mnt/btrfs_bigbackup/
^^^ works, filesystem is still there:

Read/write still failing :-/

Gemini says the following, whether it's right or wrong about the
details, it would be nice to have a way to btrfs --repair or force
cleanup/revert/delete on read-write mount to recover to a working state.
Coping 22TB off from r/o FS is pointless, it's an offsite backup, never mind
that I have nowhere to copy that too anyway, I really would like to
get it back to read/write if there isn't massive corruption, and there
does not seem to be.

Btrfs operates on a strict "clean up your mess first" policy.
Read-Only: The kernel simply reads the B-trees as they currently exist
on the disk. It completely ignores the Btrfs "to-do" list (the delayed
refs and the aborted relocation tree).
Read-Write: The kernel refuses to let you write new data until it
finishes the aborted relocation from when the system crashed days
ago. It tries to execute that "to-do" list, hits the corrupted Extent
Tree/Squota bug (ENOENT), and instantly panics and aborts the mount to
prevent further corruption.

Because there is no skip_relocation mount option in the Linux kernel,
you cannot force this filesystem to mount Read-Write without clearing
that broken tree. And because standard tools cannot clear a broken
relocation tree offline, the RW mount is effectively bricked.


moremagic:~# mount -wno remount,skip_balance /mnt/btrfs_bigbackup/
kernel: usb 2-1: reset SuperSpeed USB device number 3 using xhci-hcd
kernel: ------------[ cut here ]------------
kernel: BTRFS: Transaction aborted (error -2)
kernel: WARNING: CPU: 1 PID: 325244 at fs/btrfs/extent-tree.c:2996 __btrfs_free_extent.isra.0+0x13a0/0x14a0 [btrfs]
kernel: Modules linked in: dm_crypt dm_mod bcache raid456 async_raid6_recov async_memcpy async_pq async_xor async_tx xt_MASQUERADE ipt_REJECT nf_reject_ipv4 xt_tcpudp xt_conntrack xt_LOG nf_log_syslog nft_compat nft_chain_nat nf_nat nf_conntrack nf_defrag_ipv6 nf_defrag_ipv4 nf_tables rfcomm algif_hash algif_skcipher af_alg bnep cp210x brcmfmac_wcc binfmt_misc usbserial hci_uart brcmfmac btbcm vc4 snd_soc_hdmi_codec brcmutil bluetooth drm_display_helper cfg80211 cec drm_dma_helper rpi_hevc_dec ecdh_generic v4l2_mem2mem ecc snd_soc_core pisp_be videobuf2_dma_contig v3d videobuf2_memops videobuf2_v4l2 gpu_sched rfkill videodev drm_shmem_helper snd_compress snd_pcm_dmaengine snd_pcm videobuf2_common rp1_pio snd_timer snd drm_kms_helper mc raspberrypi_gpiomem rp1_fw sg sch_fq_codel ecryptfs fuse drm drm_panel_orientation_quirks backlight nfnetlink ip_tables x_tables raid1 aes_ce_blk aes_ce_cipher ghash_ce gf128mul libaes sha2_ce spidev sha256_arm64 sha1_ce raspberrypi_hwmon sha1_generic ahci i2c_brcmstb spi_bcm2835
kernel:  md_mod gpio_keys libahci pwm_fan rp1_adc libata rp1_mailbox nvmem_rmem uio_pdrv_genirq uio btrfs blake2b_generic xor xor_neon raid6_pq zram lz4_compress ipv6
kernel: CPU: 1 UID: 0 PID: 325244 Comm: mount Tainted: G        W          6.12.47+rpt-rpi-2712 #1  Debian 1:6.12.47-1+rpt1
kernel: Tainted: [W]=WARN
kernel: Hardware name: Raspberry Pi 5 Model B Rev 1.1 (DT)
kernel: pstate: 60400009 (nZCv daif +PAN -UAO -TCO -DIT -SSBS BTYPE=--)
kernel: pc : __btrfs_free_extent.isra.0+0x13a0/0x14a0 [btrfs]
kernel: lr : __btrfs_free_extent.isra.0+0x13a0/0x14a0 [btrfs]
kernel: sp : ffffc0008a843820
kernel: x29: ffffc0008a8438c0 x28: 0000000000000000 x27: 0000000000002f02
kernel: x26: 000000000000007f x25: ffff80011fbbae60 x24: 0000000000004000
kernel: x23: 0000000000000000 x22: ffff8001033a9068 x21: 0000000000004000
kernel: x20: 00000e1a4bb88000 x19: 00000000fffffffe x18: 0000000000000000
kernel: x17: 0000000000000000 x16: 0000000000000000 x15: 0000000000000000
kernel: x14: 0000000000000000 x13: 0000000000000000 x12: 0000000000000000
kernel: x11: 00000000000000c0 x10: 0000000000001a40 x9 : ffffd06fce4e06c0
kernel: x8 : ffff80011e5a9ea0 x7 : ffffc0008293bc30 x6 : 0000000000000043
kernel: x5 : 0000000000000001 x4 : 0000000000001ab0 x3 : 0000000000000804
kernel: x2 : 0000000000000000 x1 : 0000000000000000 x0 : ffff80011e5a8400
kernel: Call trace:
kernel:  __btrfs_free_extent.isra.0+0x13a0/0x14a0 [btrfs]
kernel:  __btrfs_run_delayed_refs+0x508/0xec0 [btrfs]
kernel:  btrfs_run_delayed_refs+0x48/0x198 [btrfs]
kernel:  btrfs_commit_transaction+0x88/0xe20 [btrfs]
kernel:  btrfs_recover_relocation+0x55c/0x5d0 [btrfs]
kernel:  btrfs_start_pre_rw_mount+0x1d4/0x470 [btrfs]
kernel:  btrfs_reconfigure+0x198/0x6d8 [btrfs]
kernel:  reconfigure_super+0xc8/0x260
kernel:  __arm64_sys_fsconfig+0x510/0x5b8
kernel:  invoke_syscall+0x50/0x120
kernel:  el0_svc_common.constprop.0+0x48/0xf0
kernel:  do_el0_svc+0x24/0x38
kernel:  el0_svc+0x30/0xf8
kernel:  el0t_64_sync_handler+0x120/0x130
kernel:  el0t_64_sync+0x190/0x198
kernel: ---[ end trace 0000000000000000 ]---
kernel: BTRFS: error (device dm-0 state MA) in do_free_extent_accounting:2996: errno=-2 No such entry
kernel: BTRFS error (device dm-0 state EMA): failed to run delayed ref for logical 15506102321152 num_bytes 16384 type 182 action 2 ref_mod 1: -2
kernel: BTRFS: error (device dm-0 state EMA) in btrfs_run_delayed_refs:2215: errno=-2 No such entry
kernel: BTRFS warning (device dm-0 state EMA): failed to recover relocation: -2
mount: /mnt/btrfs_bigbackup: fsconfig() failed: No such file or directory.
       dmesg(1) may have more information after failed mount system call.



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Home page: http://marc.merlins.org/                       | PGP 7F55D5F27AAF9D08