do not create _data dir without checking first

[bergwolf]

container_populate_volume() checks _data existance to determine if it
should populate old data. We only need to create new _data with 0777
mode if there is no existing one. That includes two cases:

1. before populating old data in container_populate_volume()
2. mount an empty volume for the fist time

For file volume case, we need to chmod it instead, to make sure any user
is able to read/write the file.

[gao-feng]

free list in error path.

[bergwolf]

fixed. Thanks.

[bergwolf]

Before patch:

[~]$hyper run -d --size=l1 neo4j
7f7cc4d3cebb5d2a4fa2eeab207e467d322d4130d6cc53693678c9be2b21320d
[~]$hyper exec 7f7cc4d3cebb5d2a4fa2eeab207e467d322d4130d6cc53693678c9be2b21320d ls -l /data
total 0

After patch:

[lear@master]$mypkt run -d --size=l1 neo4j
f9f9040359cf586b18d3c3393123b870a371081fbe9b1e3cef9ad1fcaa128e75
[lear@master]$mypkt exec f9f9040359cf586b18d3c3393123b870a371081fbe9b1e3cef9ad1fcaa128e75 ls -l /data
total 8
drwxr-xr-x 3  112 nogroup 4096 Aug 14 06:16 databases
drwxr-xr-x 2 root root    4096 Aug 14 06:16 dbms

[bergwolf]

Normal empty volume works as usual.

[lear@master]$mypkt run -d -v vol1:/data busybox
f2e1c8372de9117c8f1686efc34f8e3cddd7b68c634bdb12d3493e3c947b9b0c
[lear@master]$mypkt exec f2e1c8372de9117c8f1686efc34f8e3cddd7b68c634bdb12d3493e3c947b9b0c df
Filesystem           1K-blocks      Used Available Use% Mounted on
/dev/sdb              10190100     38060   9611368   0% /
devtmpfs                250392         0    250392   0% /dev
tmpfs                   253336         0    253336   0% /dev/shm
/dev/sda                999320      2568    927940   0% /data
share_dir                 1024         4      1020   0% /etc/hosts