[libvirt] [PATCH 3/3] qemu: support metadata-cache-size for blockdev

[Nikolay Shirokovskiy]

Just set l2-cache-size to INT64_MAX for all format nodes of
qcow2 type in block node graph.

AFAIK this is sane because *actual* cache size depends on size
of data being referenced in image and thus the total size of
all cache sizes for all images in disk backing chain will not
exceed the cache size that covers just one full image as in
case of no backing chain.

Signed-off-by: Nikolay Shirokovskiy <nshirokovskiy at virtuozzo.com>
---
 src/qemu/qemu_block.c     | 5 ++++-
 src/qemu/qemu_domain.c    | 1 +
 src/util/virstoragefile.c | 1 +
 src/util/virstoragefile.h | 1 +
 4 files changed, 7 insertions(+), 1 deletion(-)

diff --git a/src/qemu/qemu_block.c b/src/qemu/qemu_block.c
index 5321dda..8771cc1 100644
--- a/src/qemu/qemu_block.c
+++ b/src/qemu/qemu_block.c
@@ -1322,7 +1322,6 @@ qemuBlockStorageSourceGetFormatQcow2Props(virStorageSourcePtr src,
      * 'pass-discard-snapshot'
      * 'pass-discard-other'
      * 'overlap-check'
-     * 'l2-cache-size'
      * 'l2-cache-entry-size'
      * 'refcount-cache-size'
      * 'cache-clean-interval'
@@ -1331,6 +1330,10 @@ qemuBlockStorageSourceGetFormatQcow2Props(virStorageSourcePtr src,
     if (qemuBlockStorageSourceGetFormatQcowGenericProps(src, "qcow2", props) < 0)
         return -1;
 
+    if (src->metadata_cache_size == VIR_DOMAIN_DISK_METADATA_CACHE_SIZE_MAXIMUM &&
+        virJSONValueObjectAdd(props, "I:l2-cache-size", INT64_MAX, NULL) < 0)
+        return -1;
+
     return 0;
 }
 
diff --git a/src/qemu/qemu_domain.c b/src/qemu/qemu_domain.c
index 896adf3..f87cfd2 100644
--- a/src/qemu/qemu_domain.c
+++ b/src/qemu/qemu_domain.c
@@ -13245,6 +13245,7 @@ qemuDomainPrepareDiskSourceData(virDomainDiskDefPtr disk,
     src->iomode = disk->iomode;
     src->cachemode = disk->cachemode;
     src->discard = disk->discard;
+    src->metadata_cache_size = disk->metadata_cache_size;
 
     if (disk->device == VIR_DOMAIN_DISK_DEVICE_FLOPPY)
         src->floppyimg = true;
diff --git a/src/util/virstoragefile.c b/src/util/virstoragefile.c
index 94c32d8..9089e2f 100644
--- a/src/util/virstoragefile.c
+++ b/src/util/virstoragefile.c
@@ -2210,6 +2210,7 @@ virStorageSourceCopy(const virStorageSource *src,
     ret->cachemode = src->cachemode;
     ret->discard = src->discard;
     ret->detect_zeroes = src->detect_zeroes;
+    ret->metadata_cache_size = src->metadata_cache_size;
 
     /* storage driver metadata are not copied */
     ret->drv = NULL;
diff --git a/src/util/virstoragefile.h b/src/util/virstoragefile.h
index 3ff6c4f..8b57399 100644
--- a/src/util/virstoragefile.h
+++ b/src/util/virstoragefile.h
@@ -331,6 +331,7 @@ struct _virStorageSource {
     int cachemode; /* enum virDomainDiskCache */
     int discard; /* enum virDomainDiskDiscard */
     int detect_zeroes; /* enum virDomainDiskDetectZeroes */
+    int metadata_cache_size; /* enum virDomainDiskImageMetadataCacheSize */
 
     bool floppyimg; /* set to true if the storage source is going to be used
                        as a source for floppy drive */
-- 
1.8.3.1