libgfapi: Added support to fetch volume info from glusterd and store in glfs object.

Defined new APIs in the libgfapi module, given a glfs object,
 * to send handshake RPC call to glusterd process to fetch UUID of the volume
 * store it in the glusterfs_context linked to the glfs object.
 * to parse UUID from its cannonical string format into 16-byte array
   before sending it to the libgfapi users.

Defined a RPC call in glusterd which can be used to query volume related
info by other processes using 'clnt_handshake_procs'.

Note - Currently this RPC call to glusterd process is used only to fetch UUID.
But it can be extended to get other volume related structures as well.

In addition to the above, defined a new variable to keep track of such handshake
RPCs still in progress to make sure all the corresponding RPC callbacks have been
processed before libgfapi returns the glfs object initialized.

Also bumping up the GFAPI current version number since there is a new API
"glfs_get_volume_id" defined and exposed by libgfapi as part of these changes.

Change-Id: I303f76d7177d32d25bdb301b1dbcf5cd73f42807
BUG: 1090363
Signed-off-by: Soumya Koduri <skoduri@redhat.com>
Reviewed-on: http://review.gluster.org/7218
Reviewed-by: Anand Avati <avati@redhat.com>
Reviewed-by: Harshavardhana <harsha@harshavardhana.net>
Tested-by: Gluster Build System <jenkins@build.gluster.com>
Reviewed-by: Vijay Bellur <vbellur@redhat.com>

1 files changed, 32 insertions, 0 deletions

diff --git a/api/src/glfs.h b/api/src/glfs.h
index 4344df24dc7..8f1d09d1094 100644
--- a/api/src/glfs.h
+++ b/api/src/glfs.h
@@ -285,6 +285,38 @@ int glfs_fini (glfs_t *fs) __THROW;
 
 ssize_t glfs_get_volfile (glfs_t *fs, void *buf, size_t len) __THROW;
 
+
+/*
+  SYNOPSIS
+
+       glfs_get_volumeid: Copy the Volume UUID stored in the glfs object fs.
+
+  DESCRIPTION
+
+       This function when invoked for the first time sends RPC call to the
+       the management server (glusterd) to fetch volume uuid and stores it
+       in the glusterfs_context linked to the glfs object fs which can be used
+       in the subsequent calls. Later it parses that UUID to convert it from
+       cannonical string format into an opaque byte array and copy it into
+       the volid array. Incase if either of the input parameters, volid or size,
+       is NULL, number of bytes required to copy the volume UUID is returned.
+
+  PARAMETERS
+
+       @fs: The 'virtual mount' object to be used to retrieve and store
+            volume's UUID.
+       @volid: Pointer to a place for the volume UUID to be stored
+       @size: Length of @volid
+
+  RETURN VALUES
+
+       -1 : Failure. @errno will be set with the type of failure.
+        Others : length of the volume UUID stored.
+*/
+
+int glfs_get_volumeid (struct glfs *fs, char *volid, size_t size);
+
+
 /*
  * FILE OPERATION
  *