Re: Crash on btrfs check

[Qu Wenruo <quwenruo@cn.fujitsu.com>]

cheater00 . wrote on 2016/01/15 03:25 +0100:
> Hi guys,
> I have a particularly full btrfs (nearly all of 6TB used on a disk).
> This is different than the fs I've experienced the resize bug on
> recently.
>
> btrfs check crashes on it:
>
> # btrfs check /dev/sdb1
> Checking filesystem on /dev/sdb1
> UUID: 95db96b3-96fe-4a12-810c-27c1dbd30b0d
> checking extents
> extent_io.c:543: __alloc_extent_buffer: Assertion failed.
> btrfs[0x80558a3]
> btrfs[0x8092971]
> btrfs(alloc_extent_buffer+0xb7)[0x8093494]
> btrfs(btrfs_find_create_tree_block+0x2b)[0x8083785]
> btrfs(read_tree_block+0x32)[0x808503f]
> btrfs(read_node_slot+0x63)[0x807f430]
> btrfs(btrfs_search_slot+0xb47)[0x8081a28]
> btrfs(btrfs_lookup_extent_info+0xd6)[0x808a0df]
> btrfs[0x806c13a]
> btrfs[0x806d95e]
> btrfs[0x806e5cb]
> btrfs(cmd_check+0x10f8)[0x8070fee]
> btrfs(main+0x14d)[0x8055acb]
> /lib/i386-linux-gnu/libc.so.6(__libc_start_main+0xf3)[0xb74f0a83]
> btrfs[0x8055af8]
>
>
>
> $ uname -a
> Linux SX20S 4.4.0-040400-generic #201601101930 SMP Mon Jan 11 00:49:33
> UTC 2016 i686 i686 i686 GNU/Linux
>
> $ btrfs --version
> btrfs-progs v4.3
>
> # btrfs fi show /dev/sdb1
> Label: 'A'  uuid: 95db96b3-96fe-4a12-810c-27c1dbd30b0d
>      Total devices 1 FS bytes used 5.41TiB
>      devid    1 size 5.46TiB used 5.46TiB path /dev/sdb1
>
> # btrfs-show-super /dev/sdb1
> superblock: bytenr=65536, device=/dev/sdb1
> ---------------------------------------------------------
> csum            0x116b97f0 [match]
> bytenr            65536
> flags            0x1
>              ( WRITTEN )
> magic            _BHRfS_M [match]
> fsid            95db96b3-96fe-4a12-810c-27c1dbd30b0d
> label            P
> generation        128737
> root            43384832
> sys_array_size        226
> chunk_root_generation    106809
> root_level        1
> chunk_root        20971520
> chunk_root_level    1
> log_root        0
> log_root_transid    0
> log_root_level        0
> total_bytes        6001173463040
> bytes_used        5948325072896
> sectorsize        4096
> nodesize        16384
> leafsize        16384
> stripesize        4096
> root_dir        6
> num_devices        1
> compat_flags        0x0
> compat_ro_flags        0x0
> incompat_flags        0x61
>              ( MIXED_BACKREF |
>                BIG_METADATA |
>                EXTENDED_IREF )
> csum_type        0
> csum_size        4
> cache_generation    128737
> uuid_tree_generation    128737
> dev_item.uuid        e2a8e731-b28c-437b-8cb9-583bb96aea5f
> dev_item.fsid        95db96b3-96fe-4a12-810c-27c1dbd30b0d [match]
> dev_item.type        0
> dev_item.total_bytes    6001173463040
> dev_item.bytes_used    6001173463040
> dev_item.io_align    4096
> dev_item.io_width    4096
> dev_item.sector_size    4096
> dev_item.devid        1
> dev_item.dev_group    0
> dev_item.seek_speed    0
> dev_item.bandwidth    0
> dev_item.generation    0
>
> # btrfs fi usage A
> Overall:
>      Device size:           5.46TiB
>      Device allocated:           5.46TiB
>      Device unallocated:             0.00B
>      Device missing:             0.00B
>      Used:               5.42TiB
>      Free (estimated):          35.41GiB    (min: 35.41GiB)
>      Data ratio:                  1.00
>      Metadata ratio:              2.00
>      Global reserve:         512.00MiB    (used: 0.00B)
>
> Data,single: Size:5.43TiB, Used:5.40TiB
>     /dev/sdb1       5.43TiB
>
> Metadata,single: Size:8.00MiB, Used:0.00B
>     /dev/sdb1       8.00MiB
>
> Metadata,DUP: Size:12.50GiB, Used:11.22GiB
>     /dev/sdb1      25.00GiB
>
> System,single: Size:4.00MiB, Used:0.00B
>     /dev/sdb1       4.00MiB
>
> System,DUP: Size:8.00MiB, Used:608.00KiB
>     /dev/sdb1      16.00MiB
>
> Unallocated:
>     /dev/sdb1         0.00B
>
> dmesg is showing a lot of stuff like this, but it only started doing
> this when I upgraded to linux 4.4, whereas before on 4.3 this didn't
> happen:
>
> [56319.486446] BTRFS critical (device sdb1): entry offset
> 6102519574528, bytes 20480, bitmap no
> [56319.486447] BTRFS critical (device sdb1): entry offset
> 6102527688704, bytes 24576, bitmap no
> [56319.486448] BTRFS critical (device sdb1): entry offset
> 6102528040960, bytes 8192, bitmap no
> [56319.486450] BTRFS critical (device sdb1): entry offset
> 6102536241152, bytes 8192, bitmap no
> [56319.486451] BTRFS critical (device sdb1): entry offset
> 6102561120256, bytes 8192, bitmap no
> [56319.486452] BTRFS critical (device sdb1): entry offset
> 6102590480384, bytes 4096, bitmap no
> [56319.486453] BTRFS critical (device sdb1): entry offset
> 6102620999680, bytes 12288, bitmap no
> [56319.486454] BTRFS critical (device sdb1): entry offset
> 6102633365504, bytes 16384, bitmap no
> [56319.486455] BTRFS info (device sdb1): block group has cluster?: no
> [56319.486456] BTRFS info (device sdb1): 1 blocks of free space at or
> bigger than bytes is

And this dmesg is not a big problem, just means space cache is wrong.

Normally mount it with clear_cache should be able to make it disappear.

Thanks,
Qu

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