Description of problem:
If the user does not add proper number of bricks to an add-brick operation, then it should suggest valid number of bricks that can be added, like before.

Example:
root@Dagobah:~/nfs/hearya# gluster volume info str
 
Volume Name: str
Type: Distributed-Stripe
Status: Started
Number of Bricks: 2 x 2 = 4
Transport-type: tcp
Bricks:
Brick1: dagobah:/data/export20
Brick2: dagobah:/data/export21
Brick3: dagobah:/data/export22
Brick4: dagobah:/data/export23
root@Dagobah:~/nfs/hearya# gluster volume add-brick
Usage: volume add-brick <VOLNAME> [<stripe|replica> <COUNT>] <NEW-BRICK> ...
root@Dagobah:~/nfs/hearya# gluster volume add-brick str replica 2 dagobah:/data/export24
Operation failed
root@Dagobah:~/nfs/hearya# gluster volume add-brick str replica 2 dagobah:/data/export24 dagobah:/data/export25
Operation failed
root@Dagobah:~/nfs/hearya# gluster volume add-brick str replica 2 dagobah:/data/export24 dagobah:/data/export25 dagobah:/data/export26
Operation failed
root@Dagobah:~/nfs/hearya# gluster volume add-brick str replica 2 dagobah:/data/export24 dagobah:/data/export25 dagobah:/data/export26 dagobah:/data/export27
Add Brick successful
root@Dagobah:~/nfs/hearya# gluster volume info str
 
Volume Name: str
Type: Distributed-Striped-Replicate
Status: Started
Number of Bricks: 2 x 2 x 2 = 8
Transport-type: tcp
Bricks:
Brick1: dagobah:/data/export20
Brick2: dagobah:/data/export24
Brick3: dagobah:/data/export21
Brick4: dagobah:/data/export25
Brick5: dagobah:/data/export22
Brick6: dagobah:/data/export26
Brick7: dagobah:/data/export23
Brick8: dagobah:/data/export27

Version-Release number of selected component (if applicable):


How reproducible:


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Actual results:


Expected results:


Additional info: