librbd: invalidating the cache shouldn't hold write lock

This can cause deadlock when readahead is in-progress since neither
can make forward progress.

Fixes: http://tracker.ceph.com/issues/22131
Signed-off-by: Jason Dillaman <dillaman@redhat.com>
(cherry picked from commit 6a335481d20c6a765c84d561a01fb52172eccba4)

diff --git a/src/librbd/internal.cc b/src/librbd/internal.cc
index acbe336629ccd4c52aee6ed94e4e06a533865b30..d2695f57416007eff4c56341f8180d7cd9d81c67 100644 (file)
--- a/src/librbd/internal.cc
+++ b/src/librbd/internal.cc
@@ -2244,7 +2244,6 @@ int validate_pool(IoCtx &io_ctx, CephContext *cct) {
     }
 
     RWLock::RLocker owner_locker(ictx->owner_lock);
-    RWLock::WLocker md_locker(ictx->md_lock);
     r = ictx->invalidate_cache(false);
     ictx->perfcounter->inc(l_librbd_invalidate_cache);
     return r;