Btrfs-progs: restructure show_qgroups

The current show_qgroups() just shows a little information, and it is hard to
add some functions which the users need in the future, so i restructure it, make
it easy to add new functions.

In order to improve the scalability of show_qgroups(), i add some important
structures:

	struct qgroup_lookup {
		struct rb_root root;
	}
 	/*
	*store qgroup's information
	*/
	struct btrfs_qgroup {
		struct rb_node  rb_node;
		u64 qgroupid;

		u64 generation;
		u64 rfer;
		u64 rfer_cmpr;
		u64 excl_cmpr;

		u64 flags;
		u64 max_rfer;
		u64 max_excl;
		u64 rsv_rfer;
		u64 rsv_excl;

		struct list_head qgroups;
		struct list_head members;
	}
	/*
	*glue structure to represent the relations
	*between qgroups
	*/
	struct btrfs_qgroup_list {
		struct list_head next_qgroups;
		struct list_head next_member;
		struct btrfs_qgroup *qgroup;
		struct btrfs_qgroup *member;
	}
The above 3 structures are used to manage all the information
of qgroups.

	struct {
		char *name;
		char *column_name;
		int need_print;
	} btrfs_qgroup_columns[]

We define a arrary to manage all the columns that can be
outputed, and use a member variant(->need_print) to control
the output of the relative column. Some columns are outputed
by default. But we can change it according to the requirement
of the users.

For example:
	if outputing max referenced size of qgroup is needed,the function
'btrfs_qgroup_setup_column()' will be called, and the parameter 'BTRFS_QGROUP_MAX_RFER'
(extend in the future) will be passsed to the function. After the function is done,
when showing qgroups, max referenced size of qgroup will be output.

Signed-off-by: Wang Shilong <wangsl-fnst@cn.fujitsu.com>
Signed-off-by: Miao Xie <miaox@cn.fujitsu.com>
Btrfs-progs: introduces '-p' option to print the ID of the parent qgroups

This patch introduces '-p' option to print the ID of the parent qgroups.
You may use it like:

	btrfs qgroup show -p <path>
For Example:
                qgroupid(2/0)
                /         \
               /           \
              /             \
        qgroupid(1/0)  qgroupid(1/1)
              \              /
               \            /
                qgroupid(0/1)

If we use the command:

	btrfs qgroup show -p <path>
The result will output
	0/1 -- -- 1/0,1/1
	1/0 -- -- 2/0
	1/1 -- -- 2/0
	2/0 -- -- --

Signed-off-by: Wang Shilong <wangsl-fnst@cn.fujitsu.com>
Signed-off-by: Miao Xie <miaox@cn.fujitsu.com>
Btrfs-progs: introduces '-c' option to print the ID of the child qgroups

This patch introduces '-c' option to print the ID of the child qgroups.
You may use it like:
	btrfs qgroup show -c <path>

For Example:

                qgroupid(2/0)
                 /       \
                /         \
               /           \
            qgroupid(1/0) qgroupid(1/1)
               \            /
                \          /
		 qgroupid(0/1)

If we use the command:

	btrfs qgroup show -c <path>
The result will output
	0/1 -- -- --
	1/0 -- -- 0/1
	1/1 -- -- 0/1
	2/0 -- -- 1/0,1/1

Signed-off-by: Wang Shilong <wangsl-fnst@cn.fujitsu.com>
Signed-off-by: Miao Xie <miaox@cn.fujitsu.com>
Btrfs-progs: introduce '-l' option to print max referenced size of qgroups

This patch introduces '-l' option to print max referenced size of qgroups.
You may use it like:

		btrfs qgroup show -l <path>

Signed-off-by: Wang Shilong <wangsl-fnst@cn.fujitsu.com>
Signed-off-by: Miao Xie <miaox@cn.fujitsu.com>
Btrfs-progs: introduce '-e' option to print max exclusive size of qgroups

This patch introduce '-e' option to print max exclusive size of qgroups.
You may use it like this:
		btrfs qgroup -e <path>

Signed-off-by: Wang Shilong <wangsl-fnst@cn.fujitsu.com>
Signed-off-by: Miao Xie <miaox@cn.fujitsu.com>
Btrfs-progs: list all qgroups impact given path(include ancestral qgroups)

This patch introduces '-F' option which can help you filter the qgroups
by the path name, you may use it like:

	btrfs qgroup show -F <path>
For example:

                         qgroupid(2/0)
                          /     \
                         /       \
                        qgroupid(1/0)
                        /         \
                       /           \
                      /             \
                  qgroupid(0/1)   qgroupid(0/2)
                  sub1              sub2
                  /  \
                 /    \
		dir1  file1

If we use the command:
	btrfs qgroup show -F sub1/dir1
The result will output
	0/1	--	--
	1/0	--	--
	2/0	--	--

'-F' option help you list all qgroups impact given path.
(include ancestral qgroups).

Signed-off-by: Wang shilong <wangsl-fnst@cn.fujitsu.com>
Signed-off-by: Miao Xie <miaox@cn.fujitsu.com>
Btrfs-progs: list all qgroups impact given path(exclude ancestral qgroups)

This patch introduces '-f' option which can help you filter the qgroups
by the path name, you may use it like:

	btrfs qgroup show -f <path>
For example:

                         qgroupid(2/0)
                          /     \
                         /       \
                        qgroupid(1/0)
                        /         \
                       /           \
                      /             \
                  qgroupid(0/1)   qgroupid(0/2)
                  sub1              sub2
                  /  \
                 /    \
		dir1  file1

If we use the command:
	btrfs qgroup show -f sub1/dir1
The result will output
	0/1	--	--

'-f' option helps you list all qgroups impact given path.
(exclude ancestral qgroups)

Signed-off-by: Wang shilong <wangsl-fnst@cn.fujitsu.com>
Signed-off-by: Miao Xie <miaox@cn.fujitsu.com>
Btrfs-progs: enhance btrfs qgroup show to sort qgroups

You might want to list qgroups in order of some items, such as 'qgroupid', 'rfer'
and so on, you can use '--sort'. Now you can sort the qgroups by 'qgroupid',
'rfer','excl','max_rfer' and 'max_excl'.

For example:
	If you want to list qgroups in order of 'qgroupid'.
You can use the option like that:

	btrfs qgroup show --sort=+/-qgroupid <path>
Here, '+' means the result is sorted by ascending order. '-' is by descending
order. If you don't specify either '+' nor '-', the result is sorted by
default - ascending order.

If you want to combine sort items, you do it like that:
	btrfs qgroup show  --sort=-qgroupid,+rfer,max_rfer,excl <path>

Signed-off-by: Wang Shilong <wangsl-fnst@cn.fujitsu.com>
Signed-off-by: Miao Xie <miaox@cn.fujitsu.com>
Btrfs-progs: enhance btrfs qgroup to print the result as a table

This patch introduce '-t' option which can help you print the result
as a table.

You can use it like:
	btrfs qgroup show -t <path>
However, to table the result better, we make '-p' and '-c' not present
at the same time.If you still want to show both of them at the same time,
you may print the result without '-t' option.

For example:

	btrfs qgroup show -tpl <path>
The result will output as the follow format:

qgroupid rfer       excl       max_excl       parent
-------- ----       ----       --------       ------
0/265    1289752576 1289752576 0              ---
1/0      0          0          10999511627776 2/0,3/0
2/0      0          0          0              ---
3/0      0          0          0              ---

Signed-off-by: Wang shilong <wangsl-fnst@cn.fujitsu.com>
Signed-off-by: Miao Xie <miaox@cn.fujitsu.com>