librbd: use unique error code for image removal failures

This allows the rbd tool to provide a useful error message, instead of
compounding more possible causes into one error code.

Signed-off-by: Josh Durgin <josh.durgin@dreamhost.com>

2 files changed, 10 insertions, 3 deletions

diff --git a/src/librbd.cc b/src/librbd.cc
index 0a2264bda68..bb7043682aa 100644
--- a/src/librbd.cc
+++ b/src/librbd.cc
@@ -1025,7 +1025,7 @@ int remove(IoCtx& io_ctx, const char *imgname, ProgressContext& prog_ctx)
   if (r >= 0) {
     if (has_snaps(io_ctx, md_oid)) {
       lderr(cct) << "image has snapshots - not removing" << dendl;
-      return -EBUSY;
+      return -ENOTEMPTY;
     }
     trim_image(io_ctx, header, 0, prog_ctx);
     ldout(cct, 2) << "removing header..." << dendl;
diff --git a/src/rbd.cc b/src/rbd.cc
index cb82f9cc70f..1c43fb544be 100644
--- a/src/rbd.cc
+++ b/src/rbd.cc
@@ -1193,14 +1193,21 @@ int main(int argc, const char **argv)
   case OPT_RM:
     r = do_delete(rbd, io_ctx, imgname);
     if (r < 0) {
-      if (r == -EBUSY) {
+      if (r == -ENOTEMPTY) {
 	cerr << "delete error: image has snapshots - these must be deleted"
 	     << " with 'rbd snap purge' before the image can be removed."
 	     << std::endl;
+      } else if (r == -EBUSY) {
+	cerr << "delete error: image still has watchers"
+	     << std::endl
+	     << "This means the image is still open or the client using "
+	     << "it crashed. Try again after closing/unmapping it or "
+	     << "waiting 30s for the crashed client to timeout."
+	     << std::endl;
       } else {
 	cerr << "delete error: " << cpp_strerror(-r) << std::endl;
       }
-      exit(1);
+      exit(-r);
     }
     break;