crash in btrfsck, btrfs-debug-tree, etc

crash in btrfsck, btrfs-debug-tree, etc

[Vladimir G. Ivanovic]

I overwrote some part of the first 195641856 bytes of a 1TB (nominal)
btrfs volume (I CTRL-C'd out
before dd finished.) OK, OK, you may stop laughing now. Surely something
similar has happened to
you. No? Then it will, someday.

First things first: A huge congratulations to the btrfs team because the
btrfs volume is still
usable. I do get many errors similar to:

    kernel: btrfs bad tree block start 3050544144921548175 12056985

but for many of my files, I don't get errors.

Now, onto my problems. My first thought was to btrfsck the unmount
volume, but btrfsck crashes:

    # btrfsck /dev/sdc1
    btrfsck: disk-io.c:723: open_ctree_fd: Assertion
`!(!chunk_root->node)' failed.
    Aborted (core dumped)

So does btrfs-debug-tree, and I suspect other utilities will as well. I
tried the latest utilities
from btrfs-progs-unstable, but they too crash with the same error. (I'm
on a Athlon64-powered
netbook running Fedora 12. btrfs's version is 0.19.) In particular, so
does btrfs-image, so I can't
share the volume's metadata.

So, until the utilities are fixed, what are my options?

* Can I create a snapshot of the root volume? Would I end up with
everything that could be read in
  the snapshot, or would it also have errors? If this is a good idea,
would these commands work?

      btrfsctl -s snapshot_of_root /mnt/chopin1
      mount.btrfs -o subvol=snapshot_of_root /dev/sdc1 /mnt/snap

  do the trick, assuming that btrfsctl doesn't also crash? Then what?
Copy the snapshot to another
  disk? Somehow make the new snapshot the new root, allowing me to
delete the old root?

* Should I just try and copy the data to another disk and reformat my
current volume?

* Is there a way of testing whether a particular file is good other than
(slowly) going through
  each and every file while watching syslog? cat, for example, doesn't
return an error when the
  file is bad, so I don't think I can write a shell script to copy good
files to another volume.

Are there other options that I haven't considered?

Thanks for all help.

--- Vladimir

-- 
Vladimir G. Ivanovic                            http://www.leonora.org
+1 650 450 4101                                       vladimir@acm.org

Re: crash in btrfsck, btrfs-debug-tree, etc

[Vladimir G. Ivanovic]

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No help, eh? At the minimum, it would be nice if btrfsck were fixed...

Unfortunately, now btrfs will NOT mount the drive, so I am now
completely without data. The mount error is:

    kernel: device fsid c64b56bd1c869bb3-e85f95a29c7dd3ad devid 1
transid 21547 /dev/sdc1
    kernel: btrfs bad tree block start 14052438117991321731 20971520
    kernel: btrfs bad tree block start 14052438117991321731 20971520
    kernel: btrfs bad tree block start 8532476744452893537 20971520
    kernel: btrfs: failed to read chunk root on sdc1
    kernel: btrfs: open_ctree failed

--- Vladimir

Vladimir G. Ivanovic                            http://www.leonora.org
+1 650 450 4101                                       vladimir@acm.org


on 04/28/2010 01:03 PM Vladimir G. Ivanovic said the following:
> I overwrote some part of the first 195641856 bytes of a 1TB (nominal)
> btrfs volume (I CTRL-C'd out
> before dd finished.) OK, OK, you may stop laughing now. Surely something
> similar has happened to
> you. No? Then it will, someday.
>
> First things first: A huge congratulations to the btrfs team because the
> btrfs volume is still
> usable. I do get many errors similar to:
>
>     kernel: btrfs bad tree block start 3050544144921548175 12056985
>
> but for many of my files, I don't get errors.
>
> Now, onto my problems. My first thought was to btrfsck the unmount
> volume, but btrfsck crashes:
>
>     # btrfsck /dev/sdc1
>     btrfsck: disk-io.c:723: open_ctree_fd: Assertion
> `!(!chunk_root->node)' failed.
>     Aborted (core dumped)
>
> So does btrfs-debug-tree, and I suspect other utilities will as well. I
> tried the latest utilities
> from btrfs-progs-unstable, but they too crash with the same error. (I'm
> on a Athlon64-powered
> netbook running Fedora 12. btrfs's version is 0.19.) In particular, so
> does btrfs-image, so I can't
> share the volume's metadata.
>
> So, until the utilities are fixed, what are my options?
>
> * Can I create a snapshot of the root volume? Would I end up with
> everything that could be read in
>   the snapshot, or would it also have errors? If this is a good idea,
> would these commands work?
>
>       btrfsctl -s snapshot_of_root /mnt/chopin1
>       mount.btrfs -o subvol=snapshot_of_root /dev/sdc1 /mnt/snap
>
>   do the trick, assuming that btrfsctl doesn't also crash? Then what?
> Copy the snapshot to another
>   disk? Somehow make the new snapshot the new root, allowing me to
> delete the old root?
>
> * Should I just try and copy the data to another disk and reformat my
> current volume?
>
> * Is there a way of testing whether a particular file is good other than
> (slowly) going through
>   each and every file while watching syslog? cat, for example, doesn't
> return an error when the
>   file is bad, so I don't think I can write a shell script to copy good
> files to another volume.
>
> Are there other options that I haven't considered?
>
> Thanks for all help.
>
> --- Vladimir
>
>   


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Re: crash in btrfsck, btrfs-debug-tree, etc

[Wayne Scott]

> on 04/28/2010 01:03 PM Vladimir G. Ivanovic said the following:
> > I overwrote some part of the first 195641856 bytes of a 1TB (nominal)
> > btrfs volume (I CTRL-C'd out
> > before dd finished.) OK, OK, you may stop laughing now. Surely something
> > similar has happened to
> > you. No? Then it will, someday.
> >
> > Now, onto my problems. My first thought was to btrfsck the unmount
> > volume, but btrfsck crashes:
> >
> >     # btrfsck /dev/sdc1
> >     btrfsck: disk-io.c:723: open_ctree_fd: Assertion
> > `!(!chunk_root->node)' failed.
> >     Aborted (core dumped)

I have the same fsck error and mount just says "wrong fs type...".

But as far as I know, I never corrupted the drive...

This is Ubuntu Natty.

Just thought I would share that.

-Wayne

Re: crash in btrfsck, btrfs-debug-tree, etc

[liubo]

On 05/04/2010 05:28 AM, Vladimir G. Ivanovic wrote:
> No help, eh? At the minimum, it would be nice if btrfsck were fixed...
> 

Not sure if the following one will help you to show the metadata, but you
can give it a try and go on using btrfs-debug-tree.

diff --git a/disk-io.c b/disk-io.c
index a6e1000..90f2831 100644
--- a/disk-io.c
+++ b/disk-io.c
@@ -204,12 +204,8 @@ struct extent_buffer *read_tree_block(struct btrfs_root *root, u64 bytenr,
 		eb->dev_bytenr = multi->stripes[0].physical;
 		kfree(multi);
 		ret = read_extent_from_disk(eb);
-		if (ret == 0 && check_tree_block(root, eb) == 0 &&
-		    csum_tree_block(root, eb, 1) == 0 &&
-		    verify_parent_transid(eb->tree, eb, parent_transid) == 0) {
-			btrfs_set_buffer_uptodate(eb);
+		if (ret == 0)
 			return eb;
-		}
 		num_copies = btrfs_num_copies(&root->fs_info->mapping_tree,
 					      eb->start, eb->len);
 		if (num_copies == 1) {


thanks,
liubo.

> Unfortunately, now btrfs will NOT mount the drive, so I am now
> completely without data. The mount error is:
> 
>     kernel: device fsid c64b56bd1c869bb3-e85f95a29c7dd3ad devid 1
> transid 21547 /dev/sdc1
>     kernel: btrfs bad tree block start 14052438117991321731 20971520
>     kernel: btrfs bad tree block start 14052438117991321731 20971520
>     kernel: btrfs bad tree block start 8532476744452893537 20971520
>     kernel: btrfs: failed to read chunk root on sdc1
>     kernel: btrfs: open_ctree failed
> 
> --- Vladimir
> 
> Vladimir G. Ivanovic                            http://www.leonora.org
> +1 650 450 4101                                       vladimir@acm.org
> 
> 
> on 04/28/2010 01:03 PM Vladimir G. Ivanovic said the following:
>> I overwrote some part of the first 195641856 bytes of a 1TB (nominal)
>> btrfs volume (I CTRL-C'd out
>> before dd finished.) OK, OK, you may stop laughing now. Surely something
>> similar has happened to
>> you. No? Then it will, someday.
>>
>> First things first: A huge congratulations to the btrfs team because the
>> btrfs volume is still
>> usable. I do get many errors similar to:
>>
>>     kernel: btrfs bad tree block start 3050544144921548175 12056985
>>
>> but for many of my files, I don't get errors.
>>
>> Now, onto my problems. My first thought was to btrfsck the unmount
>> volume, but btrfsck crashes:
>>
>>     # btrfsck /dev/sdc1
>>     btrfsck: disk-io.c:723: open_ctree_fd: Assertion
>> `!(!chunk_root->node)' failed.
>>     Aborted (core dumped)
>>
>> So does btrfs-debug-tree, and I suspect other utilities will as well. I
>> tried the latest utilities
>> from btrfs-progs-unstable, but they too crash with the same error. (I'm
>> on a Athlon64-powered
>> netbook running Fedora 12. btrfs's version is 0.19.) In particular, so
>> does btrfs-image, so I can't
>> share the volume's metadata.
>>
>> So, until the utilities are fixed, what are my options?
>>
>> * Can I create a snapshot of the root volume? Would I end up with
>> everything that could be read in
>>   the snapshot, or would it also have errors? If this is a good idea,
>> would these commands work?
>>
>>       btrfsctl -s snapshot_of_root /mnt/chopin1
>>       mount.btrfs -o subvol=snapshot_of_root /dev/sdc1 /mnt/snap
>>
>>   do the trick, assuming that btrfsctl doesn't also crash? Then what?
>> Copy the snapshot to another
>>   disk? Somehow make the new snapshot the new root, allowing me to
>> delete the old root?
>>
>> * Should I just try and copy the data to another disk and reformat my
>> current volume?
>>
>> * Is there a way of testing whether a particular file is good other than
>> (slowly) going through
>>   each and every file while watching syslog? cat, for example, doesn't
>> return an error when the
>>   file is bad, so I don't think I can write a shell script to copy good
>> files to another volume.
>>
>> Are there other options that I haven't considered?
>>
>> Thanks for all help.
>>
>> --- Vladimir
>>
>>   
>