DAFS: DFlushVolume outside of vol glock

DFlushVolume may traverse a long list of directory objects, and can
even hit the disk, so we should drop the glock for it. This should be
safe in DAFS, since we already transition the volume to an exclusive
state before doing this, and DFlushVolume only deals with structures
internal to the directory package and maintains its own locking.

Change-Id: I6493042c8f36614b55d4dc40d97639e56b34fabd
Reviewed-on: http://gerrit.openafs.org/4242
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Derrick Brashear <shadow@dementia.org>

diff --git a/src/vol/volume.c b/src/vol/volume.c
index 0c4f359..978c8e1 100644 (file)
--- a/src/vol/volume.c
+++ b/src/vol/volume.c
@@ -4726,15 +4726,17 @@ VCloseVolumeHandles_r(Volume * vp)
     VolState state_save;
 
     state_save = VChangeState_r(vp, VOL_STATE_OFFLINING);
+
+    VOL_UNLOCK;
 #endif
 
-    /* demand attach fs
-     *
-     * XXX need to investigate whether we can perform
-     * DFlushVolume outside of vol_glock_mutex...
-     *
-     * VCloseVnodeFiles_r drops the glock internally */
     DFlushVolume(vp->hashid);
+
+#ifdef AFS_DEMAND_ATTACH_FS
+    VOL_LOCK;
+#endif
+
+    /* DAFS: VCloseVnodeFiles_r drops the glock internally */
     VCloseVnodeFiles_r(vp);
 
 #ifdef AFS_DEMAND_ATTACH_FS
@@ -4778,13 +4780,17 @@ VReleaseVolumeHandles_r(Volume * vp)
     VolState state_save;
 
     state_save = VChangeState_r(vp, VOL_STATE_DETACHING);
+
+    VOL_UNLOCK;
 #endif
 
-    /* XXX need to investigate whether we can perform
-     * DFlushVolume outside of vol_glock_mutex... */
     DFlushVolume(vp->hashid);
 
-    VReleaseVnodeFiles_r(vp); /* releases the glock internally */
+#ifdef AFS_DEMAND_ATTACH_FS
+    VOL_LOCK;
+#endif
+
+    VReleaseVnodeFiles_r(vp); /* DAFS: releases the glock internally */
 
 #ifdef AFS_DEMAND_ATTACH_FS
     VOL_UNLOCK;