Re: [ANNOUNCE] Btrfs: a copy on write, snapshotting FS

[Chris Mason <chris.mason@oracle.com>]

On Fri, Jun 15, 2007 at 09:08:38PM +0200, Florian D. wrote:
> Chris Mason wrote:
> > 
> >> is it possible to test it on top of LVM2 on RAID at this stage?
> > 
> > Yes, I haven't done much multi-spindle testing yet, so I'm definitely
> > interested in these numbers.
> > 
> > -chris
> > 
> > 
> 
> I did not get very far:
> 
> 
> # insmod btrfs.ko
> # mkfs.btrfs /dev/brain_volume_group/btrfstest
> on close 0 blocks are allocated
> fs created on /dev/brain_volume_group/btrfstest blocksize 4096 blocks
> 4980736
> 
> (/dev/brain_volume_group/btrfstest is a 20GB logical volume on top of
> RAID6)
> 
> # mount /dev/brain_volume_group/btrfstest /mnt/temp/
> (this gives these kernel-msgs:
> [  385.980358] btrfs: dm-6 checksum verify failed on 4
> [  385.980462] btrfs: dm-6 checksum verify failed on 12
> [  385.980559] btrfs: dm-6 checksum verify failed on 11

These are normal on the first mount, the mkfs doesn't set the csums on
the blocks it creates (will fix ;)

> )
> 
> # touch /mnt/temp/default/testfile.txt
> [  445.445638] btrfs: dm-6 checksum verify failed on 10
> 
> 
> # umount /mnt/temp/
> 
> [  457.980372] ------------[ cut here ]------------
> [  457.980377] kernel BUG at fs/buffer.c:2644!

Whoops.  Please try this:

diff -r 38b36aaaa731 disk-io.c
--- a/disk-io.c	Fri Jun 15 13:50:20 2007 -0400
+++ b/disk-io.c	Fri Jun 15 15:12:26 2007 -0400
@@ -541,6 +541,7 @@ int write_ctree_super(struct btrfs_trans
 	else
 		ret = submit_bh(WRITE, bh);
 	if (ret == -EOPNOTSUPP) {
+		lock_buffer(bh);
 		set_buffer_uptodate(bh);
 		root->fs_info->do_barriers = 0;
 		ret = submit_bh(WRITE, bh);