btrfs-progs: qgroup show: add json output
Support json for 'qgroup show' with values printed by "btrfs qgroup
-pcre", the accounted size and the limits. It's implemented as a
separate call and not sharing the printing routines so any visible
changes need to by synchronized.
Formatter updates: don't print key name if .out_json is NULL.
Example output:
# btrfs --format json qgroup show /mnt/path
{
"__header": {
"version": "1"
},
"qgroup-show": [
{
"qgroupid": "0/5",
"referenced": "8831393792",
"max_referenced": "none",
"exclusive": "8224075776",
"max_exclusive": "none",
"path": "",
"parents": [
],
"children": [
]
},
{
"qgroupid": "0/361",
"referenced": "611459072",
"max_referenced": "none",
"exclusive": "65536",
"max_exclusive": "none",
"path": "subv1",
"parents": [
"1/1"
],
"children": [
]
},
{
"qgroupid": "0/362",
"referenced": "611459072",
"max_referenced": "none",
"exclusive": "65536",
"max_exclusive": "none",
"path": "snap1-r",
"parents": [
],
"children": [
]
},
{
"qgroupid": "1/1",
"referenced": "611459072",
"max_referenced": "none",
"exclusive": "65536",
"max_exclusive": "none",
"path": "",
"parents": [
],
"children": [
"0/361"
]
}
]
}
Issue: #555
Signed-off-by: David Sterba <dsterba@suse.com>
6ecaa3ee4f