storage_driver: Mark volume as 'in use' for some operations

There are few operations in the storage driver that read/write
data onto volumes. Such operations can take very long time to
finish. During that time the storage pool object is locked which
has bad performance impacts (other threads can't fetch its XML
for instance). This commit prepares the storage driver for
releasing the lock during those operations (downloadVol,
uploadVol, wipeVol).
Signed-off-by: NMichal Privoznik <mprivozn@redhat.com>
Reviewed-by: NJohn Ferlan <jferlan@redhat.com>

src/storage/storage_driver.c

@@ -2176,8 +2176,13 @@ storageVolDownload(virStorageVolPtr vol,
         goto cleanup;
     }
 
-    ret = backend->downloadVol(obj, voldef, stream,
-                               offset, length, flags);
+    virStoragePoolObjIncrAsyncjobs(obj);
+    voldef->in_use++;
+
+    ret = backend->downloadVol(obj, voldef, stream, offset, length, flags);
+
+    voldef->in_use--;
+    virStoragePoolObjDecrAsyncjobs(obj);
 
  cleanup:
     virStoragePoolObjEndAPI(&obj);
@@ -2326,6 +2331,7 @@ storageVolUpload(virStorageVolPtr vol,
     virStoragePoolDefPtr def;
     virStorageVolDefPtr voldef = NULL;
     virStorageVolStreamInfoPtr cbdata = NULL;
+    int rc;
     int ret = -1;
 
     virCheckFlags(VIR_STORAGE_VOL_UPLOAD_SPARSE_STREAM, -1);
@@ -2370,8 +2376,15 @@ storageVolUpload(virStorageVolPtr vol,
         VIR_STRDUP(cbdata->vol_path, voldef->target.path) < 0)
         goto cleanup;
 
-    if ((ret = backend->uploadVol(obj, voldef, stream,
-                                  offset, length, flags)) < 0)
+    virStoragePoolObjIncrAsyncjobs(obj);
+    voldef->in_use++;
+
+    rc = backend->uploadVol(obj, voldef, stream, offset, length, flags);
+
+    voldef->in_use--;
+    virStoragePoolObjDecrAsyncjobs(obj);
+
+    if (rc < 0)
         goto cleanup;
 
     /* Add cleanup callback - call after uploadVol since the stream
@@ -2381,7 +2394,7 @@ storageVolUpload(virStorageVolPtr vol,
                                   virStorageVolFDStreamCloseCb,
                                   cbdata, NULL);
     cbdata = NULL;
-
+    ret = 0;
  cleanup:
     virStoragePoolObjEndAPI(&obj);
     if (cbdata)
@@ -2499,6 +2512,7 @@ storageVolWipePattern(virStorageVolPtr vol,
     virStorageBackendPtr backend;
     virStoragePoolObjPtr obj = NULL;
     virStorageVolDefPtr voldef = NULL;
+    int rc;
     int ret = -1;
 
     virCheckFlags(0, -1);
@@ -2538,7 +2552,15 @@ storageVolWipePattern(virStorageVolPtr vol,
         goto cleanup;
     }
 
-    if (backend->wipeVol(obj, voldef, algorithm, flags) < 0)
+    virStoragePoolObjIncrAsyncjobs(obj);
+    voldef->in_use++;
+
+    rc = backend->wipeVol(obj, voldef, algorithm, flags);
+
+    voldef->in_use--;
+    virStoragePoolObjDecrAsyncjobs(obj);
+
+    if (rc < 0)
         goto cleanup;
 
     /* Instead of using the refreshVol, since much changes on the target