Re: nocow 'C' flag ignored after balance

["Kyle Gates" <kylegates@hotmail.com>]

On Tue, May 28, 2013, Liu Bo wrote:
> On Tue, May 28, 2013 at 09:22:11AM -0500, Kyle Gates wrote:
>> >From: Liu Bo <bo.li.liu@oracle.com>
>> >
>> >Subject: [PATCH] Btrfs: fix broken nocow after a normal balance
>> >
>>[...]
>>
>> Sorry for the long wait in replying.
>> This patch was unsuccessful in fixing the problem (on my 3.8 Ubuntu
>> Raring kernel). I can probably try again on a newer version if you
>> think it will help.
>> This was my first kernel compile so I patched by hand and waited (10
>> hours on my old 32 bit single core machine).
>>
>> I did move some of the files off and back on to the filesystem to
>> start fresh and compare but all seem to exhibit the same behavior
>> after a balance.
>>
>
> Thanks for testing the patch although it didn't help you.
> Actually I tested it to be sure that it fixed the problems in my 
> reproducer.
>
> So anyway can you please apply this debug patch in order to nail it down?
>
> thanks,
> liubo
>
>
> diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c
> index df472ab..c12a11c 100644
> --- a/fs/btrfs/extent-tree.c
> +++ b/fs/btrfs/extent-tree.c
> @@ -2857,8 +2857,12 @@ static noinline int check_committed_ref(struct 
> btrfs_trans_handle *trans,
>  goto out;
>
>  if (btrfs_extent_generation(leaf, ei) <=
> -     btrfs_root_last_snapshot(&root->root_item))
> +     btrfs_root_last_snapshot(&root->root_item)) {
> + printk("extent gen %llu last_snap %llu\n",
> + btrfs_extent_generation(leaf, ei),
> + btrfs_root_last_snapshot(&root->root_item));
>  goto out;
> + }
>
>  iref = (struct btrfs_extent_inline_ref *)(ei + 1);
>  if (btrfs_extent_inline_ref_type(leaf, iref) !=
> diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
> index 23c596c..8cad6ee 100644
> --- a/fs/btrfs/inode.c
> +++ b/fs/btrfs/inode.c
> @@ -1317,16 +1317,24 @@ next_slot:
>  goto out_check;
>  if (btrfs_file_extent_compression(leaf, fi) ||
>      btrfs_file_extent_encryption(leaf, fi) ||
> -     btrfs_file_extent_other_encoding(leaf, fi))
> +     btrfs_file_extent_other_encoding(leaf, fi)) {
> + printk("special encoding\n");
>  goto out_check;
> - if (extent_type == BTRFS_FILE_EXTENT_REG && !force)
> + }
> + if (extent_type == BTRFS_FILE_EXTENT_REG && !force) {
> + printk("BTRFS_FILE_EXTENT_REF\n");
>  goto out_check;
> - if (btrfs_extent_readonly(root, disk_bytenr))
> + }
> + if (btrfs_extent_readonly(root, disk_bytenr)) {
> + printk("ro\n");
>  goto out_check;
> + }
>  if (btrfs_cross_ref_exist(trans, root, ino,
>    found_key.offset -
> -   extent_offset, disk_bytenr))
> +   extent_offset, disk_bytenr)) {
> + printk("cross ref\n");
>  goto out_check;
> + }
>  disk_bytenr += extent_offset;
>  disk_bytenr += cur_offset - found_key.offset;
>  num_bytes = min(end + 1, extent_end) - cur_offset;
>
In another email Miao Xie suggests this patch won't help, so I'll wait for 
more comments/suggestions.
Thanks,
Kyle