[libvirt] [PATCH] storage_backend_rbd: always call rados_conf_read_file when connect a rbd pool

[Chen Hanxiao]

From: Chen Hanxiao <chenhanxiao at gmail.com>

This patch fix a dead lock when try to read a rbd image

When trying to connect a rbd server
(ceph-0.94.7-1.el7.centos.x86_64),

rbd_list/rbd_open enter a dead lock state.

Backtrace:
Thread 30 (Thread 0x7fdb342d0700 (LWP 12105)):
#0  0x00007fdb40b16705 in pthread_cond_wait@@GLIBC_2.3.2 () from /lib64/libpthread.so.0
#1  0x00007fdb294273f1 in librados::IoCtxImpl::operate_read(object_t const&, ObjectOperation*, ceph::buffer::list*, int) () from /lib64/librados.so.2
#2  0x00007fdb29429fcc in librados::IoCtxImpl::read(object_t const&, ceph::buffer::list&, unsigned long, unsigned long) () from /lib64/librados.so.2
#3  0x00007fdb293e850c in librados::IoCtx::read(std::string const&, ceph::buffer::list&, unsigned long, unsigned long) () from /lib64/librados.so.2
#4  0x00007fdb2b9dd15e in librbd::list(librados::IoCtx&, std::vector<std::string, std::allocator<std::string> >&) () from /lib64/librbd.so.1
#5  0x00007fdb2b98c089 in rbd_list () from /lib64/librbd.so.1
#6  0x00007fdb2e1a8052 in virStorageBackendRBDRefreshPool (conn=<optimized out>, pool=0x7fdafc002d50) at storage/storage_backend_rbd.c:366
#7  0x00007fdb2e193833 in storagePoolCreate (obj=0x7fdb1c1fd5a0, flags=<optimized out>) at storage/storage_driver.c:876
#8  0x00007fdb43790ea1 in virStoragePoolCreate (pool=pool at entry=0x7fdb1c1fd5a0, flags=0) at libvirt-storage.c:695
#9  0x00007fdb443becdf in remoteDispatchStoragePoolCreate (server=0x7fdb45fb2ab0, msg=0x7fdb45fb3db0, args=0x7fdb1c0037d0, rerr=0x7fdb342cfc30, client=<optimized out>) at remote_dispatch.h:14383
#10 remoteDispatchStoragePoolCreateHelper (server=0x7fdb45fb2ab0, client=<optimized out>, msg=0x7fdb45fb3db0, rerr=0x7fdb342cfc30, args=0x7fdb1c0037d0, ret=0x7fdb1c1b3260) at remote_dispatch.h:14359
#11 0x00007fdb437d9c42 in virNetServerProgramDispatchCall (msg=0x7fdb45fb3db0, client=0x7fdb45fd1a80, server=0x7fdb45fb2ab0, prog=0x7fdb45fcd670) at rpc/virnetserverprogram.c:437
#12 virNetServerProgramDispatch (prog=0x7fdb45fcd670, server=server at entry=0x7fdb45fb2ab0, client=0x7fdb45fd1a80, msg=0x7fdb45fb3db0) at rpc/virnetserverprogram.c:307
#13 0x00007fdb437d4ebd in virNetServerProcessMsg (msg=<optimized out>, prog=<optimized out>, client=<optimized out>, srv=0x7fdb45fb2ab0) at rpc/virnetserver.c:135
#14 virNetServerHandleJob (jobOpaque=<optimized out>, opaque=0x7fdb45fb2ab0) at rpc/virnetserver.c:156
#15 0x00007fdb436cfb35 in virThreadPoolWorker (opaque=opaque at entry=0x7fdb45fa7650) at util/virthreadpool.c:145
#16 0x00007fdb436cf058 in virThreadHelper (data=<optimized out>) at util/virthread.c:206
#17 0x00007fdb40b12df5 in start_thread () from /lib64/libpthread.so.0
#18 0x00007fdb408401ad in clone () from /lib64/libc.so.6

366             len = rbd_list(ptr.ioctx, names, &max_size);
(gdb) n
[New Thread 0x7fdb20758700 (LWP 22458)]
[New Thread 0x7fdb20556700 (LWP 22459)]
[Thread 0x7fdb20758700 (LWP 22458) exited]
[New Thread 0x7fdb20455700 (LWP 22460)]
[Thread 0x7fdb20556700 (LWP 22459) exited]
[New Thread 0x7fdb20556700 (LWP 22461)]

infinite loop...

Signed-off-by: Chen Hanxiao <chenhanxiao at gmail.com>
---
 src/storage/storage_backend_rbd.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/src/storage/storage_backend_rbd.c b/src/storage/storage_backend_rbd.c
index b1c51ab..233737b 100644
--- a/src/storage/storage_backend_rbd.c
+++ b/src/storage/storage_backend_rbd.c
@@ -95,6 +95,9 @@ virStorageBackendRBDOpenRADOSConn(virStorageBackendRBDStatePtr ptr,
             goto cleanup;
         }
 
+        /* try default location, but ignore failure */
+        rados_conf_read_file(ptr->cluster, NULL);
+
         if (!conn) {
             virReportError(VIR_ERR_INTERNAL_ERROR, "%s",
                            _("'ceph' authentication not supported "
@@ -124,6 +127,10 @@ virStorageBackendRBDOpenRADOSConn(virStorageBackendRBDStatePtr ptr,
                            _("failed to create the RADOS cluster"));
             goto cleanup;
         }
+
+        /* try default location, but ignore failure */
+        rados_conf_read_file(ptr->cluster, NULL);
+
         if (virStorageBackendRBDRADOSConfSet(ptr->cluster,
                                              "auth_supported", "none") < 0)
             goto cleanup;
-- 
2.7.4