From: Hitoshi Mitake <mitake.hito...@lab.ntt.co.jp>
Now the area isn't used and clients (QEMU and tgt) don't care about
it, we can recycle it for storing the btree_counter.
Cc: MORITA Kazutaka <morita.kazut...@lab.ntt.co.jp>
Tested-by: Valerio Pachera <siri...@gmail.com>
Cc: Alessandro Bolgia <alessan...@extensys.it>
Signed-off-by: Hitoshi Mitake <mitake.hito...@lab.ntt.co.jp>
---
include/sheepdog_proto.h | 20 +++++++++++++++++---
1 file changed, 17 insertions(+), 3 deletions(-)
diff --git a/include/sheepdog_proto.h b/include/sheepdog_proto.h
index 70563cd..8b5834b 100644
--- a/include/sheepdog_proto.h
+++ b/include/sheepdog_proto.h
@@ -101,7 +101,6 @@
#define LEDGER_BIT (UINT64_C(1) << 59)
#define OLD_MAX_DATA_OBJS (1ULL << 20)
#define MAX_DATA_OBJS (1ULL << 32)
-#define MAX_CHILDREN 1024U
#define SD_MAX_VDI_LEN 256U
#define SD_MAX_VDI_TAG_LEN 256U
#define SD_MAX_VDI_ATTR_KEY_LEN 256U
@@ -224,6 +223,19 @@ struct sd_rsp {
};
};
+/*
+ * Historical notes: previous version of sheepdog (< v0.9.0) has a limit of
+ * maximum number of children which can be created from single VDI. So the
inode
+ * object has an array for storing the IDs of the child VDIs. The constant
+ * OLD_MAX_CHILDREN represents it. Current sheepdog doesn't have the
limitation,
+ * so we are recycling the area (4 * OLD_MAX_CHILDREN = 4KB) for storing new
+ * metadata.
+ *
+ * users of the released area:
+ * - uint32_t btree_counter
+ */
+#define OLD_MAX_CHILDREN 1024U
+
struct generation_reference {
int32_t generation;
int32_t count;
@@ -244,9 +256,11 @@ struct sd_inode {
uint32_t snap_id;
uint32_t vdi_id;
uint32_t parent_vdi_id;
- uint32_t __unused[MAX_CHILDREN];
- uint32_t data_vdi_id[SD_INODE_DATA_INDEX];
+
uint32_t btree_counter;
+ uint32_t __unused[OLD_MAX_CHILDREN - 1];
+
+ uint32_t data_vdi_id[SD_INODE_DATA_INDEX];
struct generation_reference gref[SD_INODE_DATA_INDEX];
};
--
1.9.1
--
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