need_inc_gen         1
    dirty_sectors        32
    stripe_sectors       0
    cached_sectors       0
    stripe               0
    stripe_redundancy    0
    io_time[READ]        1
    io_time[WRITE]       384
    fragmentation     0
    bp_start          8
  , fixing
bcachefs (loop0): hole in alloc btree missing in freespace btree
  device 0 buckets 140-143, fixing
bcachefs (loop0): hole in alloc btree at 0:140 with nonzero gen in bucket_gens btree (1), fixing
bcachefs (loop0): hole in alloc btree at 0:142 with nonzero gen in bucket_gens btree (1), fixing
bcachefs (loop0): hole in alloc btree missing in freespace btree
  device 0 buckets 144-145, fixing
bcachefs (loop0): hole in alloc btree at 0:144 with nonzero gen in bucket_gens btree (1), fixing
bcachefs (loop0): hole in alloc btree missing in freespace btree
  device 0 buckets 147-148, fixing
bcachefs (loop0): hole in alloc btree at 0:147 with nonzero gen in bucket_gens btree (1), fixing
bcachefs (loop0): hole in alloc btree missing in freespace btree
  device 0 buckets 161-162, fixing
bcachefs (loop0): hole in alloc btree at 0:161 with nonzero gen in bucket_gens btree (1), fixing
bcachefs (loop0): hole in alloc btree at 0:172 with nonzero gen in bucket_gens btree (1), fixing
bcachefs (loop0): hole in alloc btree missing in freespace btree
  device 0 buckets 174-175, fixing
bcachefs (loop0): hole in alloc btree missing in freespace btree
  device 0 buckets 176-177, fixing
bcachefs (loop0): hole in alloc btree missing in freespace btree
  device 0 buckets 178-179, fixing
bcachefs (loop0): hole in alloc btree at 0:184 with nonzero gen in bucket_gens btree (4), fixing
bcachefs (loop0): hole in alloc btree missing in freespace btree
  device 0 buckets 185-186, fixing
 done
bcachefs (loop0): check_lrus... done
bcachefs (loop0): check_backpointers_to_extents... done
bcachefs (loop0): check_extents_to_backpointers...
bcachefs (loop0): scanning for missing backpointers in 1/512 buckets
 done
bcachefs (loop0): check_inodes... done
bcachefs (loop0): resume_logged_ops... done
bcachefs (loop0): delete_dead_inodes... done
bcachefs (loop0): Fixed errors, running fsck a second time to verify fs is clean
bcachefs (loop0): check_extents_to_backpointers... done
bcachefs (loop0): check_inodes... done
bcachefs (loop0): resume_logged_ops... done
bcachefs (loop0): delete_dead_inodes... done
bcachefs (loop0): done starting filesystem
------------[ cut here ]------------
WARNING: CPU: 0 PID: 5352 at fs/bcachefs/fs-io.c:361 __bch2_truncate_folio+0x179c/0x1a30 fs/bcachefs/fs-io.c:361
Modules linked in:
CPU: 0 UID: 0 PID: 5352 Comm: syz.0.0 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2~bpo12+1 04/01/2014
RIP: 0010:__bch2_truncate_folio+0x179c/0x1a30 fs/bcachefs/fs-io.c:361
Code: 5f 5d c3 cc cc cc cc cc e8 01 5d 7e fd 48 c7 c7 b7 b6 a3 8d e8 85 61 e9 ff 89 05 ff 33 85 15 e9 49 ea ff ff e8 e5 5c 7e fd 90 <0f> 0b 90 e9 26 f9 ff ff e8 97 38 3a 07 e8 d2 5c 7e fd be 00 10 00
RSP: 0018:ffffc9000d39f9e0 EFLAGS: 00010287
RAX: ffffffff84415e4b RBX: 0000000000000000 RCX: 0000000000100000
RDX: ffffc9000e09a000 RSI: 000000000000158f RDI: 0000000000001590
RBP: ffffc9000d39fbb0 R08: ffffea00010a9507 R09: 1ffffd40002152a0
R10: dffffc0000000000 R11: fffff940002152a1 R12: 1ffff1100a4ad8fd
R13: dffffc0000000000 R14: ffff88805256c7e8 R15: 0000000000000000
FS:  00007f328e28f6c0(0000) GS:ffff88808d210000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f58cf74b000 CR3: 0000000042b5e000 CR4: 0000000000352ef0
Call Trace:
 <TASK>
 bch2_truncate_folios fs/bcachefs/fs-io.c:400 [inline]
 bchfs_fallocate+0x233/0x680 fs/bcachefs/fs-io.c:777
 bch2_fallocate_dispatch+0x28a/0x410 fs/bcachefs/fs-io.c:836
 vfs_fallocate+0x669/0x7e0 fs/open.c:342
 ksys_fallocate fs/open.c:366 [inline]
 __do_sys_fallocate fs/open.c:371 [inline]
 __se_sys_fallocate fs/open.c:369 [inline]
 __x64_sys_fallocate+0xc0/0x110 fs/open.c:369
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xfa/0x3b0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f328d38ebe9
Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 a8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f328e28f038 EFLAGS: 00000246 ORIG_RAX: 000000000000011d
RAX: ffffffffffffffda RBX: 00007f328d5b5fa0 RCX: 00007f328d38ebe9
RDX: 0000000000000062 RSI: 0000000000000010 RDI: 0000000000000005
RBP: 00007f328d411e19 R08: 0000000000000000 R09: 0000000000000000
R10: 000000000001000c R11: 0000000000000246 R12: 0000000000000000
R13: 00007f328d5b6038 R14: 00007f328d5b5fa0 R15: 00007ffee1f6b888
 </TASK>