storage: dir: adapt .refreshVol and .refreshPool for ploop volumes

Refreshes meta-information such as allocation, capacity, format, etc.
Ploop volumes differ from other volume types. Path to volume is the path
to directory with image file root.hds and DiskDescriptor.xml.
https://openvz.org/Ploop/format
Due to this fact, operations of opening the volume have to be done once
again. get the information.

To decide whether the given volume is ploops one, it is necessary to check
the presence of root.hds and DiskDescriptor.xml files in volumes' directory.
Only in this case the volume can be manipulated as the ploops one.
Such strategy helps us to resolve problems that might occure, when we
upload some other volume type from ploop source.

Signed-off-by: Olga Krishtal <okrishtal@virtuozzo.com>
Signed-off-by: Ján Tomko <jtomko@redhat.com>

src/storage/storage_backend.c

@@ -1703,6 +1703,56 @@ virStorageBackendVolOpen(const char *path, struct stat *sb,
     return fd;
 }
 
+/* virStorageIsPloop function checks whether given directory is ploop volume's
+ * directory.
+ */
+bool
+virStorageBackendIsPloopDir(char *path)
+{
+    bool ret = false;
+    char *root = NULL;
+    char *desc = NULL;
+    if (virAsprintf(&root, "%s/root.hds", path) < 0)
+        return ret;
+    if (!virFileExists(root))
+        goto cleanup;
+    if (virAsprintf(&desc, "%s/DiskDescriptor.xml", path) < 0)
+        goto cleanup;
+    if (!virFileExists(desc))
+        goto cleanup;
+
+    ret = true;
+ cleanup:
+    VIR_FREE(root);
+    VIR_FREE(desc);
+    return ret;
+}
+
+/* In case of ploop volumes, path to volume is the path to the ploop
+ * directory. To get information about allocation, header information
+ * and etc. we need to perform virStorageBackendVolOpen and
+ * virStorageBackendUpdateVolTargetFd once again.
+ */
+int
+virStorageBackendRedoPloopUpdate(virStorageSourcePtr target, struct stat *sb,
+                                 int *fd, unsigned int flags)
+{
+    char *path = NULL;
+    int ret = -1;
+
+    if (virAsprintf(&path, "%s/root.hds", target->path) < 0)
+        return -1;
+    VIR_FORCE_CLOSE(*fd);
+    if ((*fd = virStorageBackendVolOpen(path, sb, flags)) < 0)
+        goto cleanup;
+    ret = virStorageBackendUpdateVolTargetInfoFD(target, *fd, sb);
+
+ cleanup:
+
+    VIR_FREE(path);
+    return ret;
+}
+
 /*
  * virStorageBackendUpdateVolTargetInfo
  * @target: target definition ptr of volume to update
@@ -1738,8 +1788,15 @@ virStorageBackendUpdateVolTargetInfo(virStorageSourcePtr target,
     if (target->type == VIR_STORAGE_VOL_FILE &&
         target->format != VIR_STORAGE_FILE_NONE) {
         if (S_ISDIR(sb.st_mode)) {
-            ret = 0;
-            goto cleanup;
+            if (virStorageBackendIsPloopDir(target->path)) {
+                if ((ret = virStorageBackendRedoPloopUpdate(target, &sb, &fd,
+                                                            openflags)) < 0)
+                    goto cleanup;
+                target->format = VIR_STORAGE_FILE_PLOOP;
+            } else {
+                ret = 0;
+                goto cleanup;
+            }
         }
 
         if (lseek(fd, 0, SEEK_SET) == (off_t)-1) {

src/storage/storage_backend.h

@@ -118,6 +118,11 @@ int virStorageBackendCreatePloop(virConnectPtr conn,
 int virStoragePloopResize(virStorageVolDefPtr vol,
                           unsigned long long capacity);
 
+int virStorageBackendRedoPloopUpdate(virStorageSourcePtr target,
+                                     struct stat *sb, int *fd,
+                                     unsigned int flags);
+bool virStorageBackendIsPloopDir(char *path);
+
 virStorageBackendBuildVolFrom
 virStorageBackendGetBuildVolFromFunction(virStorageVolDefPtr vol,
                                          virStorageVolDefPtr inputvol);

src/storage/storage_backend_fs.c

@@ -84,9 +84,15 @@ virStorageBackendProbeTarget(virStorageSourcePtr target,
         goto cleanup;
 
     if (S_ISDIR(sb.st_mode)) {
-        target->format = VIR_STORAGE_FILE_DIR;
-        ret = 0;
-        goto cleanup;
+        if (virStorageBackendIsPloopDir(target->path)) {
+            if (virStorageBackendRedoPloopUpdate(target, &sb, &fd,
+                                                 VIR_STORAGE_VOL_FS_PROBE_FLAGS) < 0)
+                goto cleanup;
+        } else {
+            target->format = VIR_STORAGE_FILE_DIR;
+            ret = 0;
+            goto cleanup;
+        }
     }
 
     if (!(meta = virStorageFileGetMetadataFromFD(target->path,
@@ -949,6 +955,9 @@ virStorageBackendFileSystemRefresh(virConnectPtr conn ATTRIBUTE_UNUSED,
         if (vol->target.format == VIR_STORAGE_FILE_DIR)
             vol->type = VIR_STORAGE_VOL_DIR;
 
+        if (vol->target.format == VIR_STORAGE_FILE_PLOOP)
+            vol->type = VIR_STORAGE_VOL_PLOOP;
+
         if (vol->target.backingStore) {
             ignore_value(virStorageBackendUpdateVolTargetInfo(vol->target.backingStore,
                                                               false,

src/util/virstoragefile.c

@@ -184,6 +184,8 @@ qedGetBackingStore(char **, int *, const char *, size_t);
 #define QED_F_BACKING_FILE 0x01
 #define QED_F_BACKING_FORMAT_NO_PROBE 0x04
 
+#define PLOOP_IMAGE_SIZE_OFFSET 36
+#define PLOOP_SIZE_MULTIPLIER 512
 
 static struct FileTypeInfo const fileTypeInfo[] = {
     [VIR_STORAGE_FILE_NONE] = { 0, NULL, NULL, LV_LITTLE_ENDIAN,
@@ -236,8 +238,9 @@ static struct FileTypeInfo const fileTypeInfo[] = {
                                -1, {0}, 0, 0, 0, 0, NULL, NULL },
     [VIR_STORAGE_FILE_VHD] = { 0, NULL, NULL, LV_LITTLE_ENDIAN,
                                -1, {0}, 0, 0, 0, 0, NULL, NULL },
-    [VIR_STORAGE_FILE_PLOOP] = { 0, NULL, NULL, LV_LITTLE_ENDIAN,
-                               -1, {0}, 0, 0, 0, 0, NULL, NULL },
+    [VIR_STORAGE_FILE_PLOOP] = { 0, "WithouFreSpacExt", NULL, LV_LITTLE_ENDIAN,
+                                 -2, {0}, PLOOP_IMAGE_SIZE_OFFSET, 0,
+                                 PLOOP_SIZE_MULTIPLIER, -1, NULL, NULL },
 
     /* All formats with a backing store probe below here */
     [VIR_STORAGE_FILE_COW] = {