Re: [PATCH 2/2] btrfs-progs: ins: dump-tree: Print tree name for tree block backref

[Misono Tomohiro <misono.tomohiro@jp.fujitsu.com>]

On 2018/05/30 15:28, Nikolay Borisov wrote:
> 
> 
> On 30.05.2018 07:55, Misono Tomohiro wrote:
>> Print tree name instead of number to make output more readable.
>>
>> Signed-off-by: Misono Tomohiro <misono.tomohiro@jp.fujitsu.com>
>> ---
>>  print-tree.c | 5 +++--
>>  1 file changed, 3 insertions(+), 2 deletions(-)
>>
>> diff --git a/print-tree.c b/print-tree.c
>> index 90173c2b..8d551d09 100644
>> --- a/print-tree.c
>> +++ b/print-tree.c
>> @@ -470,8 +470,9 @@ void print_extent_item(struct extent_buffer *eb, int slot, int metadata)
>>  		offset = btrfs_extent_inline_ref_offset(eb, iref);
>>  		switch (type) {
>>  		case BTRFS_TREE_BLOCK_REF_KEY:
>> -			printf("\t\ttree block backref root %llu\n",
>> -			       (unsigned long long)offset);
>> +			printf("\t\ttree block backref root ");
>> +			print_objectid(stdout, offset, 0);
>> +			printf("\n");
> 
> So this is a good change, yet one thing I'd like to know is if I'm
> inspecting the extent tree with say "btrfs inspect-internal dump-tree -t
> 2" and I see a record :
> 
>         item 14 key (14540800 EXTENT_ITEM 4096) itemoff 15488 itemsize 53
>                 refs 1 gen 12 flags DATA
>                 extent data backref root 5 objectid 479 offset 0 count 1
> 
> it will in fact be "root FS_TREE" or some such.

I overlooked it. So I will update the patch.

So the question is will
> I bee able to use the printed string as an argument to -t ? Because on
> one hand I as a user would like to make sense of the output I'm seeing
> (hence the string is welcomed) at the same time I'd like to know that i
> can reference the tree with -t option without having to go and figure
> out what's the numeric id?

I looked the code and just now realized that we can already use tree name
for -t like "btrfs ins dump-tree -t EXTNET $DEV".
Please see treeid_from_string() in inspect-dump-tree.c.

> 
>>  			break;
>>  		case BTRFS_SHARED_BLOCK_REF_KEY:
>>  			printf("\t\tshared block backref parent %llu\n",
>>
> 
>