librbd: trim header update not using AIO

The original trim header update code was using blocking IO to
update the header.  After migrating to an asynchronous trim
which performs all work in librados callbacks, it exposed a
potential deadlock in the librados_test_stub when attempting
to do blocking IO within a librados callback.  This commit
changes the header update to use AIO.

Fixes: #10637
Signed-off-by: Jason Dillaman <dillaman@redhat.com>

diff --git a/src/librbd/internal.cc b/src/librbd/internal.cc
index 23a94b77e24434260afb806d3af9ab74ef58500b..7c51b5c36580a2a1cde59abde323cb8e708e2df0 100644 (file)
--- a/src/librbd/internal.cc
+++ b/src/librbd/internal.cc
@@ -1684,13 +1684,19 @@ reprotect_and_return_err:
        ldout(m_ictx->cct, 2) << "async_resize_helper finished ("
                              << r << ")" << dendl;
 
-       RWLock::WLocker l(m_ictx->md_lock);
-        if (r < 0 && m_ictx->size == m_new_size) {
-         m_ictx->size = m_original_size;
-        }
-        m_ctx->complete(r);
+       if (r < 0) {
+         RWLock::WLocker l(m_ictx->md_lock);
+         if (m_ictx->size == m_new_size) {
+           m_ictx->size = m_original_size;
+         }
+         m_ctx->complete(r);
+       }
       } BOOST_SCOPE_EXIT_END
 
+      if (r < 0) {
+       return;
+      }
+
       RWLock::RLocker l(m_ictx->owner_lock);
       if (m_ictx->image_watcher->is_lock_supported() &&
           !m_ictx->image_watcher->is_lock_owner()) {
@@ -1700,24 +1706,29 @@ reprotect_and_return_err:
 
       RWLock::WLocker l2(m_ictx->md_lock);
       m_ictx->size = m_new_size;
+
+      librados::ObjectWriteOperation op;
       if (m_ictx->old_format) {
        // rewrite header
        bufferlist bl;
        m_ictx->header.image_size = m_new_size;
        bl.append((const char *)&m_ictx->header, sizeof(m_ictx->header));
-       r = m_ictx->md_ctx.write(m_ictx->header_oid, bl, bl.length(), 0);
+       op.write(0, bl);
       } else {
-       librados::ObjectWriteOperation op;
         if (m_ictx->image_watcher->is_lock_supported()) {
          m_ictx->image_watcher->assert_header_locked(&op);
         }
        cls_client::set_size(&op, m_new_size);
-       r = m_ictx->md_ctx.operate(m_ictx->header_oid, &op);
       }
 
+      librados::AioCompletion *rados_completion =
+       librados::Rados::aio_create_completion(m_ctx, NULL, rados_ctx_cb);
+      r = m_ictx->md_ctx.aio_operate(m_ictx->header_oid, rados_completion, &op);
+      rados_completion->release();
       if (r < 0) {
        lderr(m_ictx->cct) << "error writing header: " << cpp_strerror(r)
                           << dendl;
+       return;
       }
     }