guestfs: Per-user storage pools

I'd like to be able to run more than one instance of kdevops per
physical host. Currently the kdevops guestfs set-up steers all
storage pool activity into ${STORAGE_POOL}/kdevops/guestfs, which
means there's a good chance that two different logged-in users will
create virtual machines whose names (and block devices) conflict.

So far I haven't been able to get the other storage pool-related
settings to add sufficient uniqueness to prevent this conflict.

Instead, optionally replace the "kdevops" string in the storage pool
path with the name of the user account running kdevops. Default
behavior is to continue using "kdevops".

Suggested-by: Luis Chamberlain <mcgrof@kernel.org>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>

Author: chucklever

kconfigs/Kconfig.libvirt

@@ -1124,10 +1124,47 @@ config LIBVIRT_GDB_BASEPORT
 	  /scripts/get_gdb_base_port.sh file and use the last 4 digits of the md5sum
 	  of the file to assign to libvirt_gdb_baseport.
 
+choice
+	prompt "Storage pool user name to use"
+	default KDEVOPS_STORAGE_POOL_USER_DEFAULT
+	help
+	  The storage pool user is name of the local user ID that has
+	  access to the libvirt storage pool to be used by kdevops.
+
+	  When there is only one user running kdevops on a system,
+	  the default setting should work. To enable multiple users
+	  to run kdevops on the same system, select
+	  KDEVOPS_STORAGE_POOL_USER_AUTO.
+
+config KDEVOPS_STORAGE_POOL_USER_DEFAULT
+	bool "default"
+	help
+	  The default storage pool user name is always "kdevops".
+
+config KDEVOPS_STORAGE_POOL_USER_AUTO
+	bool "auto"
+	help
+	  Kdevops selects the storage pool user name.
+
+config KDEVOPS_STORAGE_POOL_USER_CUSTOM
+	bool "custom"
+	help
+	  Set a fixed custom storage pool user name.
+
+endchoice
+
+config KDEVOPS_STORAGE_POOL_USER_CUSTOM_NAME
+	string "Storage pool user name"
+	depends on KDEVOPS_STORAGE_POOL_USER_CUSTOM
+	help
+	  Set the name of the storage pool user.
+
 config KDEVOPS_STORAGE_POOL_USER
 	string
 	output yaml
-	default "kdevops"
+	default "kdevops" if KDEVOPS_STORAGE_POOL_USER_DEFAULT
+	default $(shell, echo $USER) if KDEVOPS_STORAGE_POOL_USER_AUTO
+	default KDEVOPS_STORAGE_POOL_USER_CUSTOM_NAME if KDEVOPS_STORAGE_POOL_USER_CUSTOM
 
 config KDEVOPS_STORAGE_POOL_PATH
 	string