The storage pool code now attempts to disable COW by default on btrfs,
but management applications may wish to override this behaviour. Thus we
introduce a concept of storage pool features:
If the feature policy is set, it will be enforced. It will always
return an hard error if COW cannot be explicitly set or unset.
Signed-off-by: Daniel P. Berrangé
---
docs/formatstorage.html.in | 25 ++
docs/schemas/storagepool.rng | 30
src/conf/storage_conf.c | 49
src/conf/storage_conf.h | 8
src/storage/storage_util.c | 2 +-
tests/storagepoolxml2xmlin/pool-dir-cow.xml | 10
tests/storagepoolxml2xmlout/pool-dir-cow.xml | 15 ++
tests/storagepoolxml2xmltest.c | 1 +
8 files changed, 139 insertions(+), 1 deletion(-)
create mode 100644 tests/storagepoolxml2xmlin/pool-dir-cow.xml
create mode 100644 tests/storagepoolxml2xmlout/pool-dir-cow.xml
diff --git a/docs/formatstorage.html.in b/docs/formatstorage.html.in
index 2a7604d136..7493714c5c 100644
--- a/docs/formatstorage.html.in
+++ b/docs/formatstorage.html.in
@@ -67,6 +67,31 @@
pool. Since 0.4.1
+Features
+
+
+ Some pools support optional features:
+
+
+
+...
+features
+ cow state='no'
+/features
+...
+
+
+ Valid features are:
+
+
+ cow
+ Controls whether the filesystem performs copy-on-write (COW) for
+images in the pool. This may only be set for directory / filesystem
+pools on the btrfs filesystem. If not set then libvirt
+will attempt to disable COW on any btrfs filesystems.
+Since 6.6.0.
+
+
Source elements
diff --git a/docs/schemas/storagepool.rng b/docs/schemas/storagepool.rng
index ff0d3c836c..f5cf6769c8 100644
--- a/docs/schemas/storagepool.rng
+++ b/docs/schemas/storagepool.rng
@@ -37,6 +37,7 @@
+
@@ -49,6 +50,7 @@
+
@@ -64,6 +66,7 @@
+
@@ -79,6 +82,7 @@
+
@@ -91,6 +95,7 @@
+
@@ -103,6 +108,7 @@
+
@@ -117,6 +123,7 @@
+
@@ -128,6 +135,7 @@
+
@@ -140,6 +148,7 @@
+
@@ -154,6 +163,7 @@
+
@@ -169,6 +179,7 @@
+
@@ -180,6 +191,7 @@
+
@@ -191,6 +203,7 @@
+
@@ -205,6 +218,7 @@
+
@@ -277,6 +291,22 @@
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
diff --git a/src/conf/storage_conf.c b/src/conf/storage_conf.c
index 65d9b33049..4e63865b39 100644
--- a/src/conf/storage_conf.c
+++ b/src/conf/storage_conf.c
@@ -839,6 +839,33 @@ virStoragePoolDefRefreshFormat(virBufferPtr buf,
}
+static int
+virStoragePoolDefParseFeatures(virStoragePoolDefPtr def,
+ xmlXPathContextPtr ctxt)
+{
+g_autofree char *cow = virXPathString("string(./features/cow/@state)",
ctxt);
+
+if (cow) {
+int val;
+if (def->type != VIR_STORAGE_POOL_FS &&
+def->type != VIR_STORAGE_POOL_DIR) {
+virReportError(VIR_ERR_NO_SUPPORT, "%s",
+ _("cow feature may only be used for 'fs' and 'dir'
pools"));
+return -1;
+}
+if ((val = virTristateBoolTypeFromString(cow)) < 0) {
+virReportError(VIR_ERR_XML_ERROR,
+ _("invalid storage pool cow feature state '%s'"),
+ cow);
+return -1;
+}
+def->features.cow = val;
+}
+
+return 0;
+}
+
+
virStoragePoolDefPtr
virStoragePoolDefParseXML(xmlXPathContextPtr ctxt)
{
@@ -910,6 +937,9 @@ virStoragePoolDefParseXML(xmlXPathContextPtr ctxt)
}
}
+if (virStoragePoolDefParseFeatures(def, ctxt) < 0)
+return NULL;
+
if (options->flags & VIR_STORAGE_POOL_SOURCE_HOST) {
if (!def->source.nhost) {
virReportError(VIR_ERR_XML_ERROR, "%s",
@@ -1131,6 +1161,23 @@ virStoragePoolSourceFormat(virBufferPtr buf,
}
+static void
+virStoragePoolDefFormatFeatures(virBufferPtr buf,
+virStoragePoolDefPtr def)
+{
+if (!def->features.cow)
+return;
+
+virBufferAddLit(buf, "\n");
+virBufferAdjustIndent(buf, 2);
+if (def->features.cow)
+
