[sheepdog] [PATCH v1] sheep/http: fix error in bucket_delete

[Bingpeng Zhu]

From: NankaiZBP <nkuzbp at foxmail.com>

In current implementation, When we create a bucket, we decide
the bnode's location in account VDI using sd_hash(bucket_name)
as key. We handle hash conflict by linear probing hash table.
Here is the bug:
When we delete a bucket, we can't discard its bnode. Because
bnode_lookup() need it to find if some bucket exists or not
by checking adjacent bnodes. Therefore, we just zero its
bnode.name when client want to delete a bucket. When we create
a bucket later, we can reuse the deleted bnode if they hash to
the same location in account VDI.

Signed-off-by: Yu Fang <bingpeng.zbp at alibaba-inc.com>
---
 sheep/http/kv.c |   37 +++++++++++++++++++++++++++++--------
 1 files changed, 29 insertions(+), 8 deletions(-)

diff --git a/sheep/http/kv.c b/sheep/http/kv.c
index 5c4b386..2060bb1 100644
--- a/sheep/http/kv.c
+++ b/sheep/http/kv.c
@@ -247,18 +247,21 @@ int kv_delete_account(struct http_request *req, const char *account)
  */
 
 static int bnode_do_create(struct kv_bnode *bnode, struct sd_inode *inode,
-			   uint32_t idx)
+			   uint32_t idx, bool create)
 {
 	uint32_t vid = inode->vdi_id;
 	uint64_t oid = vid_to_data_oid(vid, idx);
 	int ret;
 
 	bnode->oid = oid;
-	ret = sd_write_object(oid, (char *)bnode, sizeof(*bnode), 0, true);
+	ret = sd_write_object(oid, (char *)bnode, sizeof(*bnode), 0, create);
 	if (ret != SD_RES_SUCCESS) {
 		sd_err("failed to create object, %" PRIx64, oid);
 		goto out;
 	}
+	if (!create)
+		goto out;
+
 	sd_inode_set_vid(inode, idx, vid);
 	ret = sd_inode_write_vid(inode, idx, vid, vid, 0, false, false);
 	if (ret != SD_RES_SUCCESS) {
@@ -276,6 +279,7 @@ static int bnode_create(struct kv_bnode *bnode, uint32_t account_vid)
 	uint32_t tmp_vid, idx;
 	uint64_t hval, i;
 	int ret;
+	bool create = true;
 
 	ret = sd_read_object(vid_to_vdi_oid(account_vid), (char *)inode,
 			     sizeof(*inode), 0);
@@ -289,16 +293,27 @@ static int bnode_create(struct kv_bnode *bnode, uint32_t account_vid)
 	for (i = 0; i < MAX_DATA_OBJS; i++) {
 		idx = (hval + i) % MAX_DATA_OBJS;
 		tmp_vid = sd_inode_get_vid(inode, idx);
-		if (tmp_vid)
-			continue;
-		else
+		if (tmp_vid) {
+			uint64_t oid = vid_to_data_oid(account_vid, idx);
+			char name[SD_MAX_BUCKET_NAME] = { };
+
+			ret = sd_read_object(oid, name, sizeof(name), 0);
+			if (ret != SD_RES_SUCCESS)
+				goto out;
+			if (name[0] == 0) {
+				create = false;
+				goto create;
+			}
+		} else
 			break;
 	}
 	if (i == MAX_DATA_OBJS) {
 		ret = SD_RES_NO_SPACE;
 		goto out;
 	}
-	ret = bnode_do_create(bnode, inode, idx);
+
+create:
+	ret = bnode_do_create(bnode, inode, idx, create);
 out:
 	free(inode);
 	return ret;
@@ -423,6 +438,7 @@ static int bucket_delete(const char *account, uint32_t avid, const char *bucket)
 	struct kv_bnode bnode;
 	char onode_name[SD_MAX_VDI_LEN];
 	char alloc_name[SD_MAX_VDI_LEN];
+	char name[SD_MAX_BUCKET_NAME] = {};
 	int ret;
 
 	snprintf(onode_name, SD_MAX_VDI_LEN, "%s/%s", account, bucket);
@@ -436,9 +452,14 @@ static int bucket_delete(const char *account, uint32_t avid, const char *bucket)
 	if (bnode.object_count > 0)
 		return SD_RES_VDI_NOT_EMPTY;
 
-	ret = sd_discard_object(bnode.oid);
+	/*
+	 * We can't discard bnode because bnode_lookup() need it to find
+	 * if some bucket exists or not by checking adjacent bnodes.
+	 * So we just zero bnode.name to indicate a deleted bucket.
+	 */
+	ret = sd_write_object(bnode.oid, name, sizeof(name), 0, false);
 	if (ret != SD_RES_SUCCESS) {
-		sd_err("failed to discard bnode for %s", bucket);
+		sd_err("failed to zero bnode for %s", bucket);
 		return ret;
 	}
 	sd_delete_vdi(onode_name);
-- 
1.7.1