osdc/Objecter: unwatch is a mutation, not a read

This was causing librados to unblock after the ACK on unwatch, which meant
that librbd users raced and tried to delete the image before the unwatch
change was committed..and got EBUSY.  See #3958.

The watch operation has a similar problem.

Signed-off-by: Sage Weil <sage@inktank.com>

1 files changed, 9 insertions, 9 deletions

diff --git a/src/librados/IoCtxImpl.cc b/src/librados/IoCtxImpl.cc
index 800e27f90b6..5f09dd47248 100644
--- a/src/librados/IoCtxImpl.cc
+++ b/src/librados/IoCtxImpl.cc
@@ -1392,7 +1392,7 @@ void librados::IoCtxImpl::set_sync_op_version(eversion_t& ver)
 int librados::IoCtxImpl::watch(const object_t& oid, uint64_t ver,
 			       uint64_t *cookie, librados::WatchCtx *ctx)
 {
-  ::ObjectOperation rd;
+  ::ObjectOperation wr;
   Mutex mylock("IoCtxImpl::watch::mylock");
   Cond cond;
   bool done;
@@ -1404,11 +1404,11 @@ int librados::IoCtxImpl::watch(const object_t& oid, uint64_t ver,
 
   WatchContext *wc = new WatchContext(this, oid, ctx);
   client->register_watcher(wc, cookie);
-  prepare_assert_ops(&rd);
-  rd.watch(*cookie, ver, 1);
+  prepare_assert_ops(&wr);
+  wr.watch(*cookie, ver, 1);
   bufferlist bl;
   wc->linger_id = objecter->linger(
-    oid, oloc, rd, snap_seq, bl, NULL,
+    oid, oloc, wr, snap_seq, bl, NULL,
     CEPH_OSD_FLAG_WRITE,
     NULL, onfinish, &objver);
   lock->Unlock();
@@ -1452,16 +1452,16 @@ int librados::IoCtxImpl::unwatch(const object_t& oid, uint64_t cookie)
   Cond cond;
   bool done;
   int r;
-  Context *onack = new C_SafeCond(&mylock, &cond, &done, &r);
+  Context *oncommit = new C_SafeCond(&mylock, &cond, &done, &r);
   eversion_t ver;
   lock->Lock();
 
   client->unregister_watcher(cookie);
 
-  ::ObjectOperation rd;
-  prepare_assert_ops(&rd);
-  rd.watch(cookie, 0, 0);
-  objecter->read(oid, oloc, rd, snap_seq, &outbl, 0, onack, &ver);
+  ::ObjectOperation wr;
+  prepare_assert_ops(&wr);
+  wr.watch(cookie, 0, 0);
+  objecter->mutate(oid, oloc, wr, snapc, ceph_clock_now(client->cct), 0, NULL, oncommit, &ver);
   lock->Unlock();
 
   mylock.Lock();