[libvirt] [PATCH] storage: Don't hold storage pool locked during wipeVol

[Michal Privoznik]

Currently the way virStorageVolWipe() works is it looks up
pool containing given volume and hold it locked throughout while
API execution. This is suboptimal because wiping a volume means
writing data to it which can take ages. And if the whole pool is
locked during that operation no other API can be issued (nor
pool-list).

Signed-off-by: Michal Privoznik <mprivozn at redhat.com>
---
 src/storage/storage_backend_iscsi_direct.c | 5 +++++
 src/storage/storage_backend_rbd.c          | 7 ++++++-
 src/storage/storage_util.c                 | 8 +++++++-
 3 files changed, 18 insertions(+), 2 deletions(-)

diff --git a/src/storage/storage_backend_iscsi_direct.c b/src/storage/storage_backend_iscsi_direct.c
index 1624066e9c..58d25557f1 100644
--- a/src/storage/storage_backend_iscsi_direct.c
+++ b/src/storage/storage_backend_iscsi_direct.c
@@ -691,6 +691,9 @@ virStorageBackenISCSIDirectWipeVol(virStoragePoolObjPtr pool,
     if (!(iscsi = virStorageBackendISCSIDirectSetConnection(pool, NULL)))
         return -1;
 
+    vol->in_use++;
+    virObjectUnlock(pool);
+
     switch ((virStorageVolWipeAlgorithm) algorithm) {
     case VIR_STORAGE_VOL_WIPE_ALG_ZERO:
         if (virStorageBackendISCSIDirectVolWipeZero(vol, iscsi) < 0) {
@@ -719,6 +722,8 @@ virStorageBackenISCSIDirectWipeVol(virStoragePoolObjPtr pool,
  cleanup:
     virISCSIDirectDisconnect(iscsi);
     iscsi_destroy_context(iscsi);
+    virObjectLock(pool);
+    vol->in_use--;
     return ret;
 }
 
diff --git a/src/storage/storage_backend_rbd.c b/src/storage/storage_backend_rbd.c
index 642cacb673..30c94c109b 100644
--- a/src/storage/storage_backend_rbd.c
+++ b/src/storage/storage_backend_rbd.c
@@ -1212,7 +1212,10 @@ virStorageBackendRBDVolWipe(virStoragePoolObjPtr pool,
     VIR_DEBUG("Wiping RBD image %s/%s", def->source.name, vol->name);
 
     if (!(ptr = virStorageBackendRBDNewState(pool)))
-        goto cleanup;
+        return -1;
+
+    vol->in_use++;
+    virObjectUnlock(pool);
 
     if ((r = rbd_open(ptr->ioctx, vol->name, &image, NULL)) < 0) {
         virReportSystemError(-r, _("failed to open the RBD image %s"),
@@ -1271,6 +1274,8 @@ virStorageBackendRBDVolWipe(virStoragePoolObjPtr pool,
         rbd_close(image);
 
     virStorageBackendRBDFreeState(&ptr);
+    virObjectLock(pool);
+    vol->in_use--;
 
     return ret;
 }
diff --git a/src/storage/storage_util.c b/src/storage/storage_util.c
index 42a9b6abf0..5c1fb7b7d3 100644
--- a/src/storage/storage_util.c
+++ b/src/storage/storage_util.c
@@ -2750,7 +2750,7 @@ storageBackendVolWipePloop(virStorageVolDefPtr vol,
 
 
 int
-virStorageBackendVolWipeLocal(virStoragePoolObjPtr pool ATTRIBUTE_UNUSED,
+virStorageBackendVolWipeLocal(virStoragePoolObjPtr pool,
                               virStorageVolDefPtr vol,
                               unsigned int algorithm,
                               unsigned int flags)
@@ -2759,6 +2759,9 @@ virStorageBackendVolWipeLocal(virStoragePoolObjPtr pool ATTRIBUTE_UNUSED,
 
     virCheckFlags(0, -1);
 
+    vol->in_use++;
+    virObjectUnlock(pool);
+
     VIR_DEBUG("Wiping volume with path '%s' and algorithm %u",
               vol->target.path, algorithm);
 
@@ -2769,6 +2772,9 @@ virStorageBackendVolWipeLocal(virStoragePoolObjPtr pool ATTRIBUTE_UNUSED,
                                              vol->target.allocation, false);
     }
 
+    virObjectLock(pool);
+    vol->in_use--;
+
     return ret;
 }
 
-- 
2.16.4