Marc MERLIN wrote on 2015/08/23 21:28 -0700:

On Mon, Aug 24, 2015 at 09:10:30AM +0800, Qu Wenruo wrote:

quoted

Would you please take the following output?

1) btrfs check output
With error message if it happens.

myth:~# btrfs check /dev/mapper/crypt_sdd1
Checking filesystem on /dev/mapper/crypt_sdd1
UUID: 024ba4d0-dacb-438d-9f1b-eeb34083fe49
checking extents
cmds-check.c:4486: add_data_backref: Assertion `back->bytes != max_size` failed.
btrfs[0x8066a73]
btrfs[0x8066aa4]
btrfs[0x8067991]
btrfs[0x806b4ab]
btrfs[0x806b9a3]
btrfs[0x806c5b2]
btrfs(cmd_check+0x1088)[0x806eddf]
btrfs(main+0x153)[0x80557c6]
/lib/i386-linux-gnu/libc.so.6(__libc_start_main+0xf3)[0xb753a4d3]
btrfs[0x80557ec]

quoted

2) btrfs check --repair output
Full output until segfault.

myth:~# btrfs check --repair /dev/mapper/crypt_sdd1
enabling repair mode
Checking filesystem on /dev/mapper/crypt_sdd1
UUID: 024ba4d0-dacb-438d-9f1b-eeb34083fe49
checking extents
cmds-check.c:4486: add_data_backref: Assertion `back->bytes != max_size` failed.
btrfs[0x8066a73]
btrfs[0x8066aa4]
btrfs[0x8067991]
btrfs[0x806b4ab]
btrfs[0x806b9a3]
btrfs[0x806c5b2]
btrfs(cmd_check+0x1088)[0x806eddf]
btrfs(main+0x153)[0x80557c6]
/lib/i386-linux-gnu/libc.so.6(__libc_start_main+0xf3)[0xb75114d3]
btrfs[0x80557ec]

Strangely I'm not getting a segfault anymore.

It seems that the tree block's backref has something wrong.

quoted

3) btrfs-debug-tree output
With assert output.

The full output is multi gigabyte. Do you need this and if so, do I need to
upload it somewhere and will you download the multi gigabyte file?

The errors and assert, I already posted here:

quoted

quoted

quoted

Sure thing:
btrfs-debug-tree /dev/mapper/crypt_sdd1 > /tmp/tree.out
parent transid verify failed on 2968115101696 wanted 34855 found 39533
parent transid verify failed on 2968115101696 wanted 34855 found 39533
parent transid verify failed on 2968115101696 wanted 34855 found 39533
parent transid verify failed on 2968115101696 wanted 34855 found 39533
Ignoring transid failure
parent transid verify failed on 2968115134464 wanted 34855 found 39533
parent transid verify failed on 2968115134464 wanted 34855 found 39533
parent transid verify failed on 2968115134464 wanted 34855 found 39533
parent transid verify failed on 2968115134464 wanted 34855 found 39533
Ignoring transid failure
parent transid verify failed on 2968115150848 wanted 34855 found 39533
parent transid verify failed on 2968115150848 wanted 34855 found 39533
parent transid verify failed on 2968115150848 wanted 34855 found 39533
parent transid verify failed on 2968115150848 wanted 34855 found 39533
Ignoring transid failure
parent transid verify failed on 2968115691520 wanted 34855 found 39533
parent transid verify failed on 2968115691520 wanted 34855 found 39533
parent transid verify failed on 2968115691520 wanted 34855 found 39533
parent transid verify failed on 2968115691520 wanted 34855 found 39533
Ignoring transid failure
parent transid verify failed on 1291597152256 wanted 35830 found 39530
parent transid verify failed on 1291597152256 wanted 35830 found 39530
parent transid verify failed on 1291597152256 wanted 35830 found 39530
parent transid verify failed on 1291597152256 wanted 35830 found 39530
Ignoring transid failure
parent transid verify failed on 2968116592640 wanted 34855 found 39533
parent transid verify failed on 2968116592640 wanted 34855 found 39533
parent transid verify failed on 2968116592640 wanted 34855 found 39533
parent transid verify failed on 2968116592640 wanted 34855 found 39533
Ignoring transid failure
parent transid verify failed on 2968116609024 wanted 34855 found 39533
parent transid verify failed on 2968116609024 wanted 34855 found 39533
parent transid verify failed on 2968116609024 wanted 34855 found 39533
parent transid verify failed on 2968116609024 wanted 34855 found 39533
Ignoring transid failure
print-tree.c:1094: btrfs_print_tree: Assertion failed.
btrfs-debug-tree[0x805ce93]
btrfs-debug-tree(btrfs_print_tree+0x26d)[0x805eb51]
btrfs-debug-tree(btrfs_print_tree+0x279)[0x805eb5d]
btrfs-debug-tree(main+0x8b5)[0x804dfb7]
/lib/i386-linux-gnu/libc.so.6(__libc_start_main+0xf3)[0xb757c4d3]
btrfs-debug-tree[0x804e221]

Oh, sorry for ignoring the existing output.

And the last assert info should be enough. No need to upload it.

The b-tree seems to be hugely damaged, or at least one leaf tree block 
is referred by higher level node.
It maybe something wrong happened when level of a btree is reduced.

Normally, I have no idea on how to fix such huge problem in btrfsck.
But there is still some clue.

In your debug-tree output, the transid difference between wanted and 
found is quite huge. I suppose there would be a much much newer root 
tree, but not recorded in superblock.

So, my last bet will be, using "btrfs-find-root -a" to find the root 
with highest generation, and use the new root to exec "btrfsck -b 
<bytenr of highest gen root>".

The latest btrfs-find-root would output possible tree root by descending 
order of its generation. You'll find proper bytenr quite easy.
But be prepared as "btrfs-find-root -a" will iterate all metadata space, 
so it will takes a long long time to finish.
And until it scanned all the space, it won't output anything.

Thanks,
Qu

Thanks,
Marc