我有一台运行Ubuntu 16.04.1的Samba服务器，提供一些btrfs子卷。这些卷的btrfs配额设置为btrfs qgroup。
为了向客户反映配额，我想使用custom dfree command。
我的问题是Samba似乎从不调用my dfree command，而只是显示btrfs文件系统的可用空间。
username@NAS:~$ smbd --version
Version 4.3.11-Ubuntu
我的smb.conf：
[global]
max log size = 1000
usershare allow guests = yes
dns proxy = no
pam password change = yes
workgroup = WORKGROUP
map to guest = bad user
obey pam restrictions = yes
server role = standalone server
passwd chat = *Enter\snew\s*\spassword:* %n\n *Retype\snew\s*\spassword:* %n\n *password\supdated\ssuccessfully* .
passwd program = /usr/bin/passwd %u
passdb backend = tdbsam
encrypt passwords = yes
server string = %h server (Samba, Ubuntu)
panic action = /usr/share/samba/panic-action %d
log file = /var/log/samba/log.%m
log level = 10
syslog = 0
dfree cache time = 0
[printers]
comment = All Printers
browseable = no
path = /var/spool/samba
printable = yes
guest ok = no
read only = yes
create mask = 0700
# Windows clients look for this share name as a source of downloadable
# printer drivers
[print$]
comment = Printer Drivers
path = /var/lib/samba/printers
browseable = yes
read only = yes
guest ok = no
[username_backup]
path = /backup_tank/username
browsable = yes
force group = username
directory mode = 750
force user = username
guest ok = no
valid users = username
create mode = 650
writable = yes
security = user
dfree command = /usr/local/bin/df_btrfs
usr / local / bin / df_btrfs（所有者根：root和700个权限）：
#!/bin/bash
STR=$(/bin/btrfs qgroup show -rF --raw /backup_tank/username/ | /usr/bin/tail -1)
SIZE=$(/usr/bin/expr `/bin/echo $STR | /usr/bin/cut -d \ -f 4` / 1024)
USED=$(/usr/bin/expr `/bin/echo $STR | /usr/bin/cut -d \ -f 2` / 1024)
AVAIL=$(/usr/bin/expr $SIZE - $USED)
/bin/echo $SIZE $AVAIL
当我运行此脚本时（由于使用btrfs命令而成为root用户），它以Samba期望的格式为我提供了正确的数字：
username@NAS:~$ sudo /usr/local/bin/df_btrfs
734003200 196187016
我尝试失败的内容（Samba不断给我相同的数字，日志显示没有错误或脚本正在运行的迹象）：
chmod 777 /usr/local/bin/df_btrfs将
/usr/local/bin/df_btrfs内容替换为：#!/bin/bash /bin/echo "734003200 196187016"将
dfree command设置替换为dfree command = 734003200 196187016用
dfree command不存在的文件路径替换设置dfree command = /usr/local/bin/df_btrfs_nonexistant（即使此文件不存在，日志中仍然没有错误）
- 使用
dfree commandin 尝试上述操作[global]
在每次尝试之间，甚至服务器和客户端计算机之间，我都重新启动了smbd服务。
dfree command或/usr/local/bin/df_btrfssmbd日志中的唯一标志是：
[2016/12/27 12:16:52.059912, 5, pid=23203, effective(0, 0), real(0, 0)] ../source3/param/loadparm.c:1325(free_param_opts)
doing parameter dfree command = /usr/local/bin/df_btrfs
doing parameter dfree cache time = 0