Hi Kent, As far as I can see, I have found a mount issue. I believe that it’s a mkfs tool issue. ENVIRONMENT: Linux ssdfs-test-0070 6.10.0 #15 SMP PREEMPT_DYNAMIC Mon Aug 5 19:00:55 MSK 2024 x86_64 x86_64 x86_64 GNU/Linux I am not sure how to share the mkfs.bcachefs tool version because this tool doesn’t show the version. REPRODUCTION PATH: (1) Format partition by mkfs tool of any file system (for example, NILFS2) (2) Mount the prepared volume (3) Execute any file system operations on the volume (4) Unmount the volume (5) Format partition by mkfs.bcachefs tool (6) Try to mount the prepared bcachefs volume (7) The bcachefs logic fails too mount the formatted volume sudo mkfs.nilfs2 -f -b 4096 /dev/sda1 mkfs.nilfs2 (nilfs-utils 2.2.8) Start writing file system initial data to the device Blocksize:4096 Device:/dev/sda1 Device Size:999292928 File system initialization succeeded !! sudo mount /dev/sda1 /mnt/test/ mount <skipped> /dev/sda1 on /mnt/test type nilfs2 (rw,relatime) Aug 5 19:14:40 ssdfs-test-0070 kernel: [ 520.066975] NILFS (sda1): segctord starting. Construction interval = 5 seconds, CP frequency < 30 seconds Aug 5 19:14:40 ssdfs-test-0070 nilfs_cleanerd[3854]: start Aug 5 19:14:40 ssdfs-test-0070 nilfs_cleanerd[3854]: pause (clean check) sudo umount /mnt/test Aug 5 19:15:18 ssdfs-test-0070 nilfs_cleanerd[3854]: shutdown sudo mkfs.bcachefs -f --block_size=4096 /dev/sda1 External UUID: 483fb669-63aa-4f41-b0ba-61eb2446c2fe Internal UUID: 43527890-f6c8-43f1-bdd9-1c4936f71a8d Device index: 0 Label: Version: 14 Oldest version on disk: 14 Created: Mon Aug 5 19:20:32 2024 Squence number: 0 Block_size: 4.0K Btree node size: 128.0K Error action: ro Clean: 0 Features: new_siphash,new_extent_overwrite,btree_ptr_v2,extents_above_btree_updates,btree_updates_journalled,new_varint,journal_no_flush,alloc_v2,extents_across_btree_nodes Compat features: Metadata replicas: 1 Data replicas: 1 Metadata checksum type: crc32c (1) Data checksum type: crc32c (1) Compression type: none (0) Foreground write target: none Background write target: none Promote target: none Metadata target: none String hash type: siphash (2) 32 bit inodes: 1 GC reserve percentage: 8% Root reserve percentage: 0% Devices: 1 live, 1 total Sections: members Superblock size: 816 Members (size 64): Device 0: UUID: 2c54ddfc-f50c-4d15-aa80-7d23474de3e6 Size: 953.0M Bucket size: 128.0K First bucket: 0 Buckets: 7624 Last mount: (never) State: rw Group: (none) Data allowed: journal,btree,user Has data: (none) Replacement policy: lru Discard: 0 initializing new filesystem going read-write mounted with opts: (null) sudo mount /dev/sda1 /mnt/test/ mount <skipped> /dev/sda1 on /mnt/test type nilfs2 (rw,relatime) <— completely unexpected Aug 5 19:21:13 ssdfs-test-0070 kernel: [ 912.678991] NILFS (sda1): broken superblock, retrying with spare superblock (blocksize = 1024) Aug 5 19:21:13 ssdfs-test-0070 kernel: [ 912.679835] NILFS (sda1): broken superblock, retrying with spare superblock (blocksize = 4096) Aug 5 19:21:13 ssdfs-test-0070 kernel: [ 912.706795] NILFS (sda1): segctord starting. Construction interval = 5 seconds, CP frequency < 30 seconds Aug 5 19:21:13 ssdfs-test-0070 nilfs_cleanerd[4751]: start Aug 5 19:21:13 ssdfs-test-0070 nilfs_cleanerd[4751]: pause (clean check) sudo umount /mnt/test sudo mount -t bcachefs /dev/sda1 /mnt/test/ mount: /mnt/test: wrong fs type, bad option, bad superblock on /dev/sda1, missing codepage or helper program, or other error. Aug 5 19:23:01 ssdfs-test-0070 kernel: [ 1020.311715] bcachefs (sda1): mounting version 0.14: btree_ptr_sectors_written opts=noshard_inode_numbers,journal_reclaim_delay=1000,nojournal_transaction_names Aug 5 19:23:01 ssdfs-test-0070 kernel: [ 1020.311753] bcachefs (sda1): recovering from clean shutdown, journal seq 4 Aug 5 19:23:01 ssdfs-test-0070 kernel: [ 1020.311782] bcachefs (sda1): Version upgrade required: Aug 5 19:23:01 ssdfs-test-0070 kernel: [ 1020.311782] Doing incompatible version upgrade from 0.14: btree_ptr_sectors_written to 1.7: mi_btree_bitmap Aug 5 19:23:01 ssdfs-test-0070 kernel: [ 1020.311782] running recovery passes: check_allocations,check_alloc_info,check_lrus,check_btree_backpointers,check_backpointers_to_extents,check_extents_to_backpointers,check_alloc_to_lru_refs,bucket_gens_init,check_snapshot_trees,check_snapshots,check_subvols,check_subvol_children,delete_dead_snapshots,check_inodes,check_extents,check_indirect_extents,check_dirents,check_xattrs,check_root,check_subvolume_structure,check_directory_structure,check_nlinks,delete_dead_inodes,set_fs_needs_rebalance Aug 5 19:23:01 ssdfs-test-0070 kernel: [ 1020.431462] bcachefs (sda1): alloc_read... done Aug 5 19:23:01 ssdfs-test-0070 kernel: [ 1020.431675] bcachefs (sda1): stripes_read... done Aug 5 19:23:01 ssdfs-test-0070 kernel: [ 1020.431688] bcachefs (sda1): snapshots_read... done Aug 5 19:23:01 ssdfs-test-0070 kernel: [ 1020.431702] bcachefs (sda1): check_allocations... Aug 5 19:23:01 ssdfs-test-0070 kernel: [ 1020.469609] dev 0 has wrong free buckets: got 0, should be 7537, fixing Aug 5 19:23:01 ssdfs-test-0070 kernel: [ 1020.469683] done Aug 5 19:23:01 ssdfs-test-0070 kernel: [ 1020.471013] bcachefs (sda1): going read-write Aug 5 19:23:01 ssdfs-test-0070 kernel: [ 1020.471766] bcachefs (sda1): journal_replay... done Aug 5 19:23:01 ssdfs-test-0070 kernel: [ 1020.471794] bcachefs (sda1): check_alloc_info... done Aug 5 19:23:01 ssdfs-test-0070 kernel: [ 1020.472921] bcachefs (sda1): check_lrus... done Aug 5 19:23:01 ssdfs-test-0070 kernel: [ 1020.473309] bcachefs (sda1): check_btree_backpointers... done Aug 5 19:23:01 ssdfs-test-0070 kernel: [ 1020.473960] bcachefs (sda1): check_backpointers_to_extents... done Aug 5 19:23:01 ssdfs-test-0070 kernel: [ 1020.474483] bcachefs (sda1): check_extents_to_backpointers... Aug 5 19:23:01 ssdfs-test-0070 kernel: [ 1020.474582] missing backpointer for btree=inodes l=1 u64s 11 type btree_ptr_v2 SPOS_MAX len 0 ver 0: seq d7dbe59ccc0e54fa written 24 min_key POS_MIN durability: 1 ptr: 0:78:0 gen 1 Aug 5 19:23:01 ssdfs-test-0070 kernel: [ 1020.474590] got: u64s 5 type deleted 0:20447232:0 len 0 ver 0 Aug 5 19:23:01 ssdfs-test-0070 kernel: [ 1020.474595] want: u64s 9 type backpointer 0:20447232:0 len 0 ver 0: bucket=0:78:0 btree=inodes l=1 offset=0:0 len=256 pos=SPOS_MAX, shutting down Aug 5 19:23:01 ssdfs-test-0070 kernel: [ 1020.474645] bcachefs (sda1): inconsistency detected - emergency read only at journal seq 4 Aug 5 19:23:01 ssdfs-test-0070 kernel: [ 1020.474664] bcachefs (sda1): bch2_check_extents_to_backpointers(): error fsck_errors_not_fixed Aug 5 19:23:01 ssdfs-test-0070 kernel: [ 1020.474682] bcachefs (sda1): bch2_fs_recovery(): error fsck_errors_not_fixed Aug 5 19:23:01 ssdfs-test-0070 kernel: [ 1020.474692] bcachefs (sda1): bch2_fs_start(): error starting filesystem fsck_errors_not_fixed Aug 5 19:23:01 ssdfs-test-0070 kernel: [ 1020.474842] bcachefs (sda1): unshutdown complete, journal seq 4 Aug 5 19:23:01 ssdfs-test-0070 kernel: [ 1020.595522] bcachefs: bch2_mount() error: fsck_errors_not_fixed Thanks, Slava.