On 2017年12月20日 16:37, Qu Wenruo wrote:
>
>
> On 2017年12月20日 16:21, Su Yue wrote:
>>
>>
>> On 12/20/2017 01:41 PM, Qu Wenruo wrote:
>>>
>>>
>>> On 2017年12月20日 12:57, Su Yue wrote:
>>>> Introduce create_chunk_and_block_block_group() to allocate new chunk
>>>> and corresponding block group.
>>>>
>>>> The new function force_cow_in_new_chunk() first allocates new chunk
>>>> and records its start.
>>>> Then it modifies all metadata block groups cached and full.
>>>> Finally it marks the new block group uncached and unfree.
>>>> In the next CoW, extents states will be updated automatically by
>>>> cache_block_group().
>>>>
>>>> Suggested-by: Qu Wenruo <wqu@xxxxxxxx>
>>>> Signed-off-by: Su Yue <suy.fnst@xxxxxxxxxxxxxx>
>>>> ---
>>>> cmds-check.c | 80
>>>> ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
>>>> 1 file changed, 80 insertions(+)
>>>>
>>>> diff --git a/cmds-check.c b/cmds-check.c
>>>> index d98d4bda7357..311c8a9f45e8 100644
>>>> --- a/cmds-check.c
>>>> +++ b/cmds-check.c
>>>> @@ -10911,6 +10911,86 @@ out:
>>>> return ret;
>>>> }
>>>> +static int create_chunk_and_block_group(struct btrfs_fs_info
>>>> *fs_info,
>>>> + u64 flags, u64 *start, u64 *nbytes)
>>>> +{
>>>> + struct btrfs_trans_handle *trans;
>>>> + struct btrfs_root *root = fs_info->extent_root;
>>>> + int ret;
>>>> +
>>>> + if ((flags & BTRFS_BLOCK_GROUP_TYPE_MASK) == 0)
>>>> + return -EINVAL;
>>>> +
>>>> + trans = btrfs_start_transaction(root, 1);
>>>> + if (IS_ERR(trans)) {
>>>> + ret = PTR_ERR(trans);
>>>> + error("error starting transaction %s", strerror(-ret));
>>>> + return ret;
>>>> + }
>>>> + ret = btrfs_alloc_chunk(trans, fs_info, start, nbytes, flags);
>>>> + if (ret) {
>>>> + error("fail to allocate new chunk %s", strerror(-ret));
>>>> + goto out;
>>>> + }
>>>> + ret = btrfs_make_block_group(trans, fs_info, 0, flags,
>>>> + BTRFS_FIRST_CHUNK_TREE_OBJECTID, *start, *nbytes);
>>>> + if (ret) {
>>>> + error("fail to make block group for chunk %llu %llu %s",
>>>> + *start, *nbytes, strerror(-ret));
>>>> + goto out;
>>>> + }
>>>> +out:
>>>> + btrfs_commit_transaction(trans, root);
>>>> + return ret;
>>>> +}
>>>> +
>>>> +static int force_cow_in_new_chunk(struct btrfs_fs_info *fs_info)
>>>> +{
>>>> + struct btrfs_block_group_cache *bg;
>>>> + u64 start;
>>>> + u64 nbytes;
>>>> + u64 alloc_profile;
>>>> + u64 flags;
>>>> + int ret;
>>>> +
>>>> + alloc_profile = (fs_info->avail_metadata_alloc_bits &
>>>> + fs_info->metadata_alloc_profile);
>>>> + flags = BTRFS_BLOCK_GROUP_METADATA | alloc_profile;
>>>> + if (btrfs_fs_incompat(fs_info, MIXED_GROUPS))
>>>> + flags |= BTRFS_BLOCK_GROUP_DATA;
>>>> +
>>>> + ret = create_chunk_and_block_group(fs_info, flags, &start,
>>>> &nbytes);
>>>
>>> Why bother allocating a new chunk by yourself?
>>>
>>> Just mark all block groups full and that's all.
>>>
>>> Any later tree block allocation like btrfs_search_slot() with @cow = 1
>>> will trigger chunk allocation automatically.
>>>
>>
>> Tried to let it happen but BUG_ON with -ENOSPC.
>
> Then fix it.
>
> It's not a normal behavior in this case.
>
> Thanks,
> Qu
And I think the fix to allow btrfs_reserve_extent() to allocate new
chunk will solve a lot of strange BUG_ON().
it just occurred to me that, a lot of use cases relies on the assumption
that btrfs_reserve_extent() will try to allocate new chunks.
Especially for case like convert, certain btrfs check --repair, some
rescue tools.
So this would be a quite nice start point for such fix.
Thanks,
Qu
>
>> Do you mean do_chunk_alloc() in btrfs_reserve_extent() which is called
>> while doing CoW?> In progs, allocation of new chunk during CoW depends @root->ref_cows.
>> However, @root->ref_cows should be set only if @root is root of a fs
>> trees.
>>
>> Thanks,
>> Su
>>
>>> Thanks,
>>> Qu
>>>
>>>> + if (!ret)
>>>> + printf("Create new chunk %llu %llu\n", start, nbytes);
>>>> + else
>>>> + goto err;
>>>> +
>>>> + flags = BTRFS_BLOCK_GROUP_METADATA;
>>>> + /* Mark all metadata block groups cached and full in free space*/
>>>> + ret = modify_block_groups_cache(fs_info, flags, 1);
>>>> + if (ret)
>>>> + goto clear_bg_cache;
>>>> +
>>>> + bg = btrfs_lookup_block_group(fs_info, start);
>>>> + if (!bg) {
>>>> + ret = -ENOENT;
>>>> + error("fail to look up block group %llu %llu", start, nbytes);
>>>> + goto clear_bg_cache;
>>>> + }
>>>> +
>>>> + /* Clear block group cache just allocated */
>>>> + ret = modify_block_group_cache(fs_info, bg, 0);
>>>> + if (ret)
>>>> + goto clear_bg_cache;
>>>> +
>>>> + return 0;
>>>> +
>>>> +clear_bg_cache:
>>>> + modify_block_groups_cache(fs_info, flags, 0);
>>>> +err:
>>>> + return ret;
>>>> +}
>>>> +
>>>> static int check_extent_refs(struct btrfs_root *root,
>>>> struct cache_tree *extent_cache)
>>>> {
>>>>
>>>
>>
>>
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