Upcall/gfapi: Return ENOTSUP when upcall feature is disabled

Changes to detect the list of upcall events enabled using GF_FOP_IPC
and return ENOTSUP to applications in case if they poll for any of
the events disabled.

Change-Id: Icc748054ef903598288119dbe99b1e337174662a
BUG: 1231132
Signed-off-by: Niels de Vos <ndevos@redhat.com>
Signed-off-by: Soumya Koduri <skoduri@redhat.com>
Reviewed-on: http://review.gluster.org/11196
Reviewed-by: Kaleb KEITHLEY <kkeithle@redhat.com>
Tested-by: Kaleb KEITHLEY <kkeithle@redhat.com>

4 files changed, 72 insertions, 1 deletions

diff --git a/api/src/glfs-handleops.c b/api/src/glfs-handleops.c
index c010f0c9a0f..f458cb4bd58 100644
--- a/api/src/glfs-handleops.c
+++ b/api/src/glfs-handleops.c
@@ -1881,6 +1881,18 @@ pub_glfs_h_poll_upcall (struct glfs *fs, struct callback_arg *up_arg)
 
         __GLFS_ENTRY_VALIDATE_FS (fs, err);
 
+        /* check if upcalls are enabled */
+        if (!fs->upcall_features) {
+                errno = ENOTSUP;
+                goto restore;
+        }
+
+        /* check if GF_UPCALL_CACHE_INVALIDATION is supported */
+        if (!(fs->upcall_features & (1 << GF_UPCALL_CACHE_INVALIDATION))) {
+                errno = ENOTSUP;
+                goto restore;
+        }
+
         /* get the active volume */
         subvol = glfs_active_subvol (fs);
 
diff --git a/api/src/glfs-handles.h b/api/src/glfs-handles.h
index 19c4e8f7a62..ddb11bf0bd5 100644
--- a/api/src/glfs-handles.h
+++ b/api/src/glfs-handles.h
@@ -293,6 +293,7 @@ glfs_h_access (struct glfs *fs, struct glfs_object *object, int mask) __THROW
 
   0   : Success.
   -1  : Error condition, mostly due to out of memory.
+        'errno' is set to ENOTSUP if upcall feature is not enabled.
 
 */
 
diff --git a/api/src/glfs-internal.h b/api/src/glfs-internal.h
index 71c83755ec3..5eb57d4b8e4 100644
--- a/api/src/glfs-internal.h
+++ b/api/src/glfs-internal.h
@@ -199,6 +199,7 @@ struct glfs {
 
 	gf_boolean_t        migration_in_progress;
 
+        uint32_t            upcall_features; /* supported upcall events */
         struct list_head    upcall_list;
         pthread_mutex_t     upcall_list_mutex; /* mutex for upcall entry list */
 
diff --git a/api/src/glfs.c b/api/src/glfs.c
index fc392947e1e..7b9f1ed6d01 100644
--- a/api/src/glfs.c
+++ b/api/src/glfs.c
@@ -253,6 +253,58 @@ get_volfp (struct glfs *fs)
 }
 
 
+static int
+detect_upcall_features (struct glfs *fs)
+{
+        xlator_t        *subvol   = NULL;
+        int              ret      = -1;
+        dict_t          *dict     = NULL;
+        uint32_t         features = 0;
+
+        DECLARE_OLD_THIS;
+        __GLFS_ENTRY_VALIDATE_FS (fs, invalid_fs);
+
+        subvol = glfs_active_subvol (fs);
+        if (!subvol) {
+                ret = -1;
+                errno = EIO;
+                goto out;
+        }
+
+        ret = syncop_ipc (subvol, GF_IPC_UPCALL_FEATURES, NULL, &dict);
+        DECODE_SYNCOP_ERR (ret);
+
+        if (ret)
+                /* some real error occured */
+                goto out;
+
+        if (!dict) {
+                /* unavailable upcalls should not be an error */
+                ret = 0;
+                goto out;
+        }
+
+        ret = dict_get_uint32 (dict, GF_UPCALL_FEATURES, &features);
+        if (ret) {
+                /* unavailable upcalls should not be an error */
+                ret = 0;
+                goto out;
+        }
+
+        fs->upcall_features = features;
+
+out:
+        if (dict)
+                dict_unref (dict);
+
+        glfs_subvol_done (fs, subvol);
+        __GLFS_EXIT_FS;
+
+invalid_fs:
+        return ret;
+}
+
+
 int
 glfs_volumes_init (struct glfs *fs)
 {
@@ -267,7 +319,7 @@ glfs_volumes_init (struct glfs *fs)
 
 	if (cmd_args->volfile_server) {
 		ret = glfs_mgmt_init (fs);
-		goto out;
+		goto finish;
 	}
 
 	fp = get_volfp (fs);
@@ -284,6 +336,11 @@ glfs_volumes_init (struct glfs *fs)
 	if (ret)
 		goto out;
 
+finish:
+        ret = detect_upcall_features (fs);
+        if (ret)
+                goto out;
+
 out:
 	return ret;
 }