Implement list, clear locks REST API w/ pkg/madmin support (#3491)

* Filter lock info based on bucket, prefix and time since lock was held
* Implement list and clear locks REST API
* madmin: Add list and clear locks API
* locks: Clear locks matching bucket, prefix, relTime.
* Gather lock information across nodes for both list and clear locks admin REST API.
* docs: Add lock API to management APIs

docs/admin-api/management-api.md

@@ -0,0 +1,82 @@
+# Management REST API
+
+## Authentication
+- AWS signatureV4
+- We use "minio" as region. Here region is set only for signature calculation.
+
+## List of management APIs
+- Service
+  - Stop
+  - Restart
+  - Status
+
+- Locks
+  - List
+  - Clear
+
+- Healing
+
+### Service Management APIs
+* Stop
+  - POST /?service
+  - x-minio-operation: stop
+  - Response: On success 200
+
+* Restart
+  - POST /?service
+  - x-minio-operation: restart
+  - Response: On success 200
+
+* Status
+  - GET /?service
+  - x-minio-operation: status
+  - Response: On success 200, return json formatted StorageInfo object.
+
+### Lock Management APIs
+* ListLocks
+  - GET /?lock&bucket=mybucket&prefix=myprefix&older-than=rel_time
+  - x-minio-operation: list
+  - Response: On success 200, json encoded response containing all locks held, older than rel_time. e.g, older than 3 hours.
+  - Possible error responses
+    - ErrInvalidBucketName
+    <Error>
+        <Code>InvalidBucketName</Code>
+        <Message>The specified bucket is not valid.</Message>
+        <Key></Key>
+        <BucketName></BucketName>
+        <Resource>/</Resource>
+        <RequestId>3L137</RequestId>
+        <HostId>3L137</HostId>
+    </Error>
+
+    - ErrInvalidObjectName
+    <Error>
+        <Code>XMinioInvalidObjectName</Code>
+        <Message>Object name contains unsupported characters. Unsupported characters are `^*|\&#34;</Message>
+        <Key></Key>
+        <BucketName></BucketName>
+        <Resource>/</Resource>
+        <RequestId>3L137</RequestId>
+        <HostId>3L137</HostId>
+    </Error>
+
+    - ErrInvalidDuration
+      <Error>
+          <Code>InvalidDuration</Code>
+          <Message>Relative duration provided in the request is invalid.</Message>
+          <Key></Key>
+          <BucketName></BucketName>
+          <Resource>/</Resource>
+          <RequestId>3L137</RequestId>
+          <HostId>3L137</HostId>
+      </Error>
+
+
+* ClearLocks
+  - POST /?lock&bucket=mybucket&prefix=myprefix&older-than=rel_time
+  - x-minio-operation: clear
+  - Response: On success 200, json encoded response containing all locks cleared, older than rel_time. e.g, older than 3 hours.
+  - Possible error responses, similar to errors listed in ListLocks.
+    - ErrInvalidBucketName
+    - ErrInvalidObjectName
+    - ErrInvalidDuration

docs/admin-api/service.md

@@ -1,33 +0,0 @@
-# Service REST API
-
-## Authentication
-- AWS signatureV4
-- We use "minio" as region. Here region is set only for signature calculation.
-
-## List of management APIs
-- Service
-  - Stop
-  - Restart
-  - Status
-
-- Locks
-  - List
-  - Clear
-
-- Healing
-
-### Service Management APIs
-* Stop
-  - POST /?service
-  - x-minio-operation: stop
-  - Response: On success 200
-
-* Restart
-  - POST /?service
-  - x-minio-operation: restart
-  - Response: On success 200
-
-* Status
-  - GET /?service
-  - x-minio-operation: status
-  - Response: On success 200, return json formatted StorageInfo object.