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 <[email protected]> >>>> Signed-off-by: Su Yue <[email protected]> >>>> --- >>>> 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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>
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