rbd: create pool_id device attribute

Add an entry under /sys/bus/rbd/devices/<N>/ named "pool_id" that
provides the id for the pool the rbd image is assocatied with.  This
is in addition to the pool name already provided.

Rename the "poolid" field in struct rbd_device  to be "pool_id".

Update the documentation to reflect the addition of this new entry.

Signed-off-by: Alex Elder <elder@inktank.com>
Reviewed-by: Josh Durgin <josh.durgin@inktank.com>

1 files changed, 8 insertions, 2 deletions

diff --git a/Documentation/ABI/testing/sysfs-bus-rbd b/Documentation/ABI/testing/sysfs-bus-rbd
index bcd88eb7ebc..3c17b62899f 100644
--- a/Documentation/ABI/testing/sysfs-bus-rbd
+++ b/Documentation/ABI/testing/sysfs-bus-rbd
@@ -35,8 +35,14 @@ name
 
 pool
 
-        The pool where this rbd image resides. The pool-name pair is unique
-        per rados system.
+        The name of the storage pool where this rbd image resides.
+        An rbd image name is unique within its pool.
+
+pool_id
+
+        The unique identifier for the rbd image's pool.  This is
+        a permanent attribute of the pool.  A pool's id will never
+        change.
 
 size