Re: [bug] balance BUG at fs/btrfs/relocation.c:886

[Liu Bo <bo.li.liu@oracle.com>]

On Wed, Jul 31, 2013 at 05:53:29PM +0800, Anand Jain wrote:
> 
> 3.11.0-rc3+
> 
> 
> ------------------
> [  225.586356] kernel BUG at fs/btrfs/relocation.c:886!
> [  225.586362] invalid opcode: 0000 [#1] SMP
> ::
> [  225.586431] Call Trace:
> [  225.586440]  [<ffffffffa0055cd1>] ?
> btree_read_extent_buffer_pages.clone.4+0xd1/0x120 [btrfs]
> [  225.586447]  [<ffffffffa00a9123>]
> relocate_tree_blocks+0x363/0x6d0 [btrfs]
> [  225.586454]  [<ffffffffa00a242c>] ? tree_insert+0x4c/0x60 [btrfs]
> [  225.586461]  [<ffffffffa00a97b3>]
> relocate_block_group+0x323/0x640 [btrfs]
> [  225.586469]  [<ffffffffa00aa14f>]
> btrfs_relocate_block_group+0x19f/0x2c0 [btrfs]
> [  225.586477]  [<ffffffffa0081768>] btrfs_relocate_chunk+0x88/0x770 [btrfs]
> [  225.586485]  [<ffffffffa0076211>] ? read_extent_buffer+0xb1/0x110 [btrfs]
> [  225.586493]  [<ffffffffa00724bf>] ? btrfs_get_token_64+0x5f/0xf0 [btrfs]
> [  225.586500]  [<ffffffffa0082c51>] btrfs_balance+0x891/0xe40 [btrfs]
> [  225.586508]  [<ffffffffa008c3ff>] ? kzalloc+0xf/0x20 [btrfs]
> [  225.586552]  [<ffffffff8113d445>] ? __kmalloc+0xf5/0x170
> [  225.586560]  [<ffffffffa008cfca>] btrfs_ioctl_balance+0x21a/0x330 [btrfs]
> [  225.586568]  [<ffffffffa008fd95>] btrfs_ioctl+0x585/0x1660 [btrfs]
> [  225.586575]  [<ffffffff8111d9eb>] ? handle_mm_fault+0x12b/0x230
> [  225.586590]  [<ffffffff811556d4>] do_vfs_ioctl+0x84/0x4c0
> [  225.586616]  [<ffffffff812867cd>] ? inode_has_perm.clone.0+0x2d/0x30
> [  225.586618]  [<ffffffff8128891a>] ? file_has_perm+0x8a/0xa0
> [  225.586625]  [<ffffffff8114ec71>] ? final_putname+0x21/0x50
> [  225.586627]  [<ffffffff81155ba1>] SyS_ioctl+0x91/0xa0
> [  225.586670]  [<ffffffff8181fed2>] system_call_fastpath+0x16/0x1b
> -------------------
> 
> 
>                 if (btrfs_root_level(&root->root_item) == cur->level) {
>                         /* tree root */
>                         BUG_ON(btrfs_root_bytenr(&root->root_item) !=
>                                cur->bytenr);
>                         if (should_ignore_root(root))
>                                 list_add(&cur->list, &useless);
>                         else
>                                 cur->root = root;
>                         break;
>                 }
> 
> 
> 
> reproducer:
> 
> ---------------------
> # mkfs.btrfs /dev/sdb -f
> 
> # btrfsck --init-csum /dev/sdb
> Creating a new CRC tree
> Checking filesystem on /dev/sdb
> UUID: 51576f7d-af1d-458b-b3c5-02eda4b3c39f
> checking extents
> Reinit crc root
> found 0 bytes used err is 0
> total csum bytes: 0
> total tree bytes: 0
> total fs tree bytes: 0
> total extent tree bytes: 0
> btree space waste bytes: 0
> file data blocks allocated: 0
>  referenced 0
> Btrfs v0.20-rc1-413-g3f4deb0-dirty
> 
> # mount /dev/sdb /btrfs
> 
> # btrfs fi bal /btrfs
> Segmentation fault
> #
> ---------------------
> 
>  Any idea how do we fix this ?
>  ( other than don't run --init-csum :-) )

This looks like a problem of --init-csum, so I guess btrfsck --init-csum
changes fs root by accident.  Could you please show the version of btrfs-progs?

-liubo