crash in btrfsck, btrfs-debug-tree, etc

DISCUSSION Vladimir G. Ivanovic 3 participants 4 messages Apr 28, 2010 – May 16, 2011 Btrfs file system

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Vladimir G. Ivanovic

author

2010-04-28 20:03 UTC #0 lore raw

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

Signature · 2 lines

Vladimir G. Ivanovic                            http://www.leonora.org
+1 650 450 4101                                       [email protected]

Vladimir G. Ivanovic

author

2010-05-03 21:28 UTC #1 lore raw

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 [email protected]

on 04/28/2010 01:03 PM Vladimir G. Ivanovic said the following:

Quoted 62 lines

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

Wayne Scott

2011-05-15 23:03 UTC #2 lore raw

Quoted 14 lines

on 04/28/2010 01:03 PM Vladimir G. Ivanovic said the following:
Quoted 13 lines
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

liubo

2011-05-16 08:08 UTC #3 lore raw

In reply to Vladimir G. Ivanovic

Quoted 2 lines · Vladimir G. Ivanovic

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.

disk-io.c +1 -5

index a6e1000..90f2831 100644
@@ -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.

Quoted 81 lines

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 [email protected]
on 04/28/2010 01:03 PM Vladimir G. Ivanovic said the following:
Quoted 62 lines
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