[PATCH 3/4] logical: Add thin-pool look-aside list

[John Ferlan <jferlan@xxxxxxxxxx>]

During processing of the extents found in a pool, we have historically
ignored the thin-pool which means any thin lv found in the pool would
also be ignored. This can start to change now - we can save aside the
name and capacity of any thin-pool's found so that we can use that when
we find a thin lv and fill in the thin-pool capacity value on output.

The result will end up being the following for a vol-dumpxml:

  <source>
    <thinpool name='thinmints'/>
      <capacity unit='bytes'>20971520</capacity>
    </thinpool>
  </source>

instead of an empty <source> </source> pair.

An upcoming patch will allow a thin lv to be seen

Signed-off-by: John Ferlan <jferlan@xxxxxxxxxx>
---
 src/conf/storage_conf.h               | 12 +++++++++
 src/storage/storage_backend_logical.c | 51 +++++++++++++++++++++++++++++++++--
 2 files changed, 61 insertions(+), 2 deletions(-)

diff --git a/src/conf/storage_conf.h b/src/conf/storage_conf.h
index f19cb59..a9a1288 100644
--- a/src/conf/storage_conf.h
+++ b/src/conf/storage_conf.h
@@ -47,6 +47,18 @@ struct _virStorageVolSourceExtent {
     unsigned long long end;
 };
 
+/*
+ * How to represent thin-pool's for a logical volume. Used by the
+ * logical parsing code
+ */
+typedef struct _virStorageVolSourceThinPool virStorageVolSourceThinPool;
+typedef virStorageVolSourceThinPool *virStorageVolSourceThinPoolPtr;
+struct _virStorageVolSourceThinPool {
+    char *name;
+    unsigned long long capacity;
+};
+
+
 typedef struct _virStorageVolSource virStorageVolSource;
 typedef virStorageVolSource *virStorageVolSourcePtr;
 struct _virStorageVolSource {
diff --git a/src/storage/storage_backend_logical.c b/src/storage/storage_backend_logical.c
index 3044853..d7990e2 100644
--- a/src/storage/storage_backend_logical.c
+++ b/src/storage/storage_backend_logical.c
@@ -72,6 +72,8 @@ virStorageBackendLogicalSetActive(virStoragePoolObjPtr pool,
 struct virStorageBackendLogicalPoolVolData {
     virStoragePoolObjPtr pool;
     virStorageVolDefPtr vol;
+    size_t nthinpools;
+    virStorageVolSourceThinPoolPtr thinpools;
 };
 
 static int
@@ -221,12 +223,38 @@ virStorageBackendLogicalMakeVol(char **const groups,
         return 0;
 
     /*
-     * Skip thin pools(t). These show up in normal lvs output
+     * Save the thin pools(t). These show up in normal lvs output
      * but do not have a corresponding /dev/$vg/$lv device that
      * is created by udev. This breaks assumptions in later code.
+     * The thin pools are the "capacity container" for all the thin
+     * lv's found in the pool. A thin lv provides a virtual size upon
+     * creation and can appear to over subscribe the pool capacity.
+     * Although usually thin pools are listed before thin lv's in the
+     * output, we'll just wait until all volumes are processed and
+     * then match the name saved here with thin_pool name we saved
+     * earlier to get the capacity value of thin-pool into the volume.
+     * It's expected that there is more than 1 thin lv per thin-pool.
+     * There can be more than 1 thin-pool per volume group.
      */
-    if (attrs[0] == 't')
+    if (attrs[0] == 't') {
+        virStorageVolSourceThinPool thin;
+
+        memset(&thin, 0, sizeof(thin));
+        if (VIR_STRDUP(thin.name, groups[0]) < 0)
+            goto cleanup;
+        if (virStrToLong_ull(groups[8], NULL, 10, &thin.capacity) < 0) {
+            VIR_FREE(thin.name);
+            virReportError(VIR_ERR_INTERNAL_ERROR,
+                           "%s", _("malformed thin pool capacity value"));
+            goto cleanup;
+        }
+        if (VIR_APPEND_ELEMENT(data->thinpools, data->nthinpools, thin) < 0) {
+            VIR_FREE(thin.name);
+            goto cleanup;
+        }
+
         return 0;
+    }
 
     /* See if we're only looking for a specific volume */
     if (data->vol != NULL) {
@@ -389,7 +417,10 @@ virStorageBackendLogicalFindLVs(virStoragePoolObjPtr pool,
     struct virStorageBackendLogicalPoolVolData cbdata = {
         .pool = pool,
         .vol = vol,
+        .nthinpools = 0,
+        .thinpools = NULL,
     };
+    size_t i, j;
 
     cmd = virCommandNewArgList(LVS,
                                "--separator", "#",
@@ -410,9 +441,25 @@ virStorageBackendLogicalFindLVs(virStoragePoolObjPtr pool,
                            "lvs") < 0)
         goto cleanup;
 
+    /* If we find some thin-pools during processing, let's see if we
+     * need information from them for any thin lv's in the pool
+     */
+    for (i = 0; i < cbdata.nthinpools; i++) {
+        for (j = 0; j < pool->volumes.count; j++) {
+            if (STREQ_NULLABLE(pool->volumes.objs[j]->source.thin_pool,
+                               cbdata.thinpools[i].name)) {
+                pool->volumes.objs[j]->source.thin_capacity =
+                    cbdata.thinpools[i].capacity;
+            }
+        }
+    }
+
     ret = 0;
  cleanup:
     virCommandFree(cmd);
+    for (i = 0; i < cbdata.nthinpools; i++)
+        VIR_FREE(cbdata.thinpools[i].name);
+    VIR_FREE(cbdata.thinpools);
     return ret;
 }
 
-- 
2.5.0

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