[PATCH v3 17/26] DAX: virtiofsd: Perform an unmap on destroy

["Dr. David Alan Gilbert (git)" <dgilbert@redhat.com>]

From: "Dr. David Alan Gilbert" <dgilbert@redhat.com>

Force unmap all remaining dax cache entries on a destroy.

Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
---
 tools/virtiofsd/passthrough_ll.c | 14 ++++++++++++++
 1 file changed, 14 insertions(+)

diff --git a/tools/virtiofsd/passthrough_ll.c b/tools/virtiofsd/passthrough_ll.c
index ed5b6c9e2d..600e102839 100644
--- a/tools/virtiofsd/passthrough_ll.c
+++ b/tools/virtiofsd/passthrough_ll.c
@@ -3129,6 +3129,20 @@ static void lo_destroy(void *userdata, struct fuse_session *se)
 {
     struct lo_data *lo = (struct lo_data *)userdata;
 
+    if (fuse_lowlevel_is_virtio(se)) {
+        VhostUserFSSlaveMsg *msg = g_malloc0(sizeof(VhostUserFSSlaveMsg) +
+                                             sizeof(VhostUserFSSlaveMsgEntry));
+
+        msg->count = 0;
+        msg->entries[0].len = ~(uint64_t)0; /* Special: means 'all' */
+        msg->entries[0].c_offset = 0;
+        if (fuse_virtio_unmap(se, msg)) {
+            fuse_log(FUSE_LOG_ERR, "%s: unmap during destroy failed\n",
+                     __func__);
+        }
+        g_free(msg);
+    }
+
     pthread_mutex_lock(&lo->mutex);
     while (true) {
         GHashTableIter iter;
-- 
2.31.1