[sheepdog] [PATCH v4 5/9] sheep: remove max children limit

[Hitoshi Mitake]

We no longer need it.  This also reduces the vdi header size.

Cc: MORITA Kazutaka <morita.kazutaka at lab.ntt.co.jp>
Cc: Valerio Pachera <sirio81 at gmail.com>
Cc: Alessandro Bolgia <alessandro at extensys.it>
Signed-off-by: Hitoshi Mitake <mitake.hitoshi at lab.ntt.co.jp>
---
v3: Keep SD_INODE_HEADER_SIZE as offsetof(struct sd_inode, data_vdi_id), not
    offsetof(struct sd_inode, __unused). Because hypervolume code depends on the
    old value.

 include/sheepdog_proto.h |  7 ++++++-
 sheep/gateway.c          |  4 ++--
 sheep/vdi.c              | 46 +++-------------------------------------------
 3 files changed, 11 insertions(+), 46 deletions(-)

diff --git a/include/sheepdog_proto.h b/include/sheepdog_proto.h
index a1db359..de746d8 100644
--- a/include/sheepdog_proto.h
+++ b/include/sheepdog_proto.h
@@ -238,7 +238,7 @@ struct sd_inode {
 	uint32_t snap_id;
 	uint32_t vdi_id;
 	uint32_t parent_vdi_id;
-	uint32_t child_vdi_id[MAX_CHILDREN];
+	uint32_t __unused[MAX_CHILDREN];
 	uint32_t data_vdi_id[SD_INODE_DATA_INDEX];
 	uint32_t btree_counter;
 	struct generation_reference data_ref[SD_INODE_DATA_INDEX];
@@ -499,4 +499,9 @@ static inline uint64_t data_oid_to_ledger_oid(uint64_t oid)
 	return LEDGER_BIT | oid;
 }
 
+static inline uint64_t data_vid_offset(int idx)
+{
+	return offsetof(struct sd_inode, data_vdi_id[idx]);
+}
+
 #endif
diff --git a/sheep/gateway.c b/sheep/gateway.c
index 5a3d333..7066f81 100644
--- a/sheep/gateway.c
+++ b/sheep/gateway.c
@@ -645,9 +645,9 @@ static int update_obj_refcnt(const struct sd_req *hdr, uint32_t *vids,
 static bool is_data_vid_update(const struct sd_req *hdr)
 {
 	return is_vdi_obj(hdr->obj.oid) &&
-		SD_INODE_HEADER_SIZE <= hdr->obj.offset &&
+		data_vid_offset(0) <= hdr->obj.offset &&
 		hdr->obj.offset + hdr->data_length <=
-			offsetof(struct sd_inode, data_ref);
+			data_vid_offset(SD_INODE_DATA_INDEX);
 }
 
 int gateway_read_obj(struct request *req)
diff --git a/sheep/vdi.c b/sheep/vdi.c
index f8a5a0b..65896c5 100644
--- a/sheep/vdi.c
+++ b/sheep/vdi.c
@@ -255,17 +255,6 @@ static struct sd_inode *alloc_inode(const struct vdi_iocb *iocb,
 	return new;
 }
 
-/* Find the first zeroed index to be used for a child vid. */
-static int find_free_idx(uint32_t *vdi_id, size_t max_idx)
-{
-	for (int i = 0; i < max_idx; i++) {
-		if (vdi_id[i] == 0)
-			return i;
-	}
-
-	return -1;
-}
-
 /* Create a fresh vdi */
 static int create_vdi(const struct vdi_iocb *iocb, uint32_t new_snapid,
 		      uint32_t new_vid)
@@ -309,7 +298,7 @@ static int clone_vdi(const struct vdi_iocb *iocb, uint32_t new_snapid,
 		     uint32_t new_vid, uint32_t base_vid)
 {
 	struct sd_inode *new = NULL, *base = xzalloc(sizeof(*base));
-	int ret, idx;
+	int ret;
 
 	sd_debug("%s: size %" PRIu64 ", vid %" PRIx32 ", base %" PRIx32 ", "
 		 "copies %d, snapid %" PRIu32, iocb->name, iocb->size, new_vid,
@@ -322,12 +311,6 @@ static int clone_vdi(const struct vdi_iocb *iocb, uint32_t new_snapid,
 		goto out;
 	}
 
-	idx = find_free_idx(base->child_vdi_id, ARRAY_SIZE(base->child_vdi_id));
-	if (idx < 0) {
-		ret = SD_RES_FULL_VDI;
-		goto out;
-	}
-
 	/* TODO: multiple sd_write_object should be performed atomically */
 
 	for (int i = 0; i < ARRAY_SIZE(base->data_ref); i++)
@@ -375,7 +358,7 @@ static int snapshot_vdi(const struct vdi_iocb *iocb, uint32_t new_snapid,
 			uint32_t new_vid, uint32_t base_vid)
 {
 	struct sd_inode *new = NULL, *base = xzalloc(sizeof(*base));
-	int ret, idx;
+	int ret;
 	uint32_t saved_count[SD_INODE_DATA_INDEX];
 
 	sd_debug("%s: size %" PRIu64 ", vid %" PRIx32 ", base %" PRIx32 ", "
@@ -389,17 +372,10 @@ static int snapshot_vdi(const struct vdi_iocb *iocb, uint32_t new_snapid,
 		goto out;
 	}
 
-	idx = find_free_idx(base->child_vdi_id, ARRAY_SIZE(base->child_vdi_id));
-	if (idx < 0) {
-		ret = SD_RES_FULL_VDI;
-		goto out;
-	}
-
 	/* TODO: multiple sd_write_object should be performed atomically */
 
 	/* update a base vdi */
 	base->snap_ctime = iocb->time;
-	base->child_vdi_id[idx] = new_vid;
 
 	for (int i = 0; i < ARRAY_SIZE(base->data_ref); i++) {
 		base->data_ref[i].generation++;
@@ -454,7 +430,7 @@ static int rebase_vdi(const struct vdi_iocb *iocb, uint32_t new_snapid,
 		      uint32_t new_vid, uint32_t base_vid, uint32_t cur_vid)
 {
 	struct sd_inode *new = NULL, *base = xzalloc(sizeof(*base));
-	int ret, idx;
+	int ret;
 
 	sd_debug("%s: size %" PRIu64 ", vid %" PRIx32 ", base %" PRIx32 ", "
 		 "cur %" PRIx32 ", copies %d, snapid %" PRIu32, iocb->name,
@@ -468,12 +444,6 @@ static int rebase_vdi(const struct vdi_iocb *iocb, uint32_t new_snapid,
 		goto out;
 	}
 
-	idx = find_free_idx(base->child_vdi_id, ARRAY_SIZE(base->child_vdi_id));
-	if (idx < 0) {
-		ret = SD_RES_FULL_VDI;
-		goto out;
-	}
-
 	/* TODO: multiple sd_write_object should be performed atomically */
 
        ret = sd_write_object(vid_to_vdi_oid(cur_vid), (char *)&iocb->time,
@@ -495,16 +465,6 @@ static int rebase_vdi(const struct vdi_iocb *iocb, uint32_t new_snapid,
 		goto out;
 	}
 
-	/* update base vdi */
-	ret = sd_write_object(vid_to_vdi_oid(base_vid), (char *)&new_vid,
-			      sizeof(new_vid),
-			      offsetof(struct sd_inode, child_vdi_id[idx]),
-			      false);
-	if (ret != SD_RES_SUCCESS) {
-		ret = SD_RES_BASE_VDI_WRITE;
-		goto out;
-	}
-
 	/* create a new vdi */
 	new = alloc_inode(iocb, new_snapid, new_vid, base->data_vdi_id,
 			  base->data_ref);
-- 
1.8.3.2