[HDDS-6682] Validate Bucket ID of bucket associated with in-flight requests.

• Type: Sub-task
• Status: Reopened
• Priority: Major
• Resolution: Unresolved
• Labels: pull-request-available
• Assignee: Jyotinder Singh
• Reporter: Jyotinder Singh
• Created: 01/May/22 16:39
• Updated: 21/Feb/23 00:17

Description

In high concurrency scenarios (which will become more common once we introduced prefix-based locking), there is a possibility of the following race condition:
Take for instance the following scenario and 3 concurrent write requests:
Bucket vol/buck1 exists with LEGACY layout.

Request 1: CreateKey by an older client (pre- bucket layout) on a bucket vol/buck1.
Request 2: DeleteBucket by a new client on the bucket vol/buck1.
Request 3: CreateBucket by a new client on the bucket vol/buck1 with layout FILE_SYSTEM_OPTIMIZED.

Let's say that these requests are processed in the following order:

1. Request 1 is picked up by one of the threads, which proceeds to run the PRE_PROCESS validations on this request. The validator we are interested in is called blockCreateKeyWithBucketLayoutFromOldClient. This validator will make sure that the bucket associated with this request is a LEGACY bucket - which is the pre-defined behavior in the case of old client/new cluster interactions since we do not want an old client operating on buckets using a new metadata layout.

One thing to know here is that at this stage, the OM does not hold a bucket lock (which only happens inside the updateAndValidateCache method associated with the write request's handler class).

1. While Request 1 was being processed, another thread was processing Request 2. Let's say `Request2' managed to get hold of the bucket lock and successfully completed the bucket deletion.

1. Now before Request 1 got a chance to acquire the bucket lock, Request 3 manages to acquire it. It proceeds with the bucket creation and creates a new bucket vol/buck1 with FILE_SYSTEM_OPTIMIZED bucket layout.

1. Finally, Request 1 is able to acquire the bucket lock and proceeds to enter its validateAndUpdateCache method. However, even though it is able to find the bucket it is looking for, this is not the same bucket that was validated in its pre-processing hook. This new bucket has the same name, but a different bucket layout. The request ends up modifying a bucket that it should not be allowed to touch.

This race condition can lead to undefined behavior of the Ozone cluster, where older clients might be modifying information they do not understand.

This PR aims to add bucket ID validation to the request processing flow, which would make sure that the bucket that ends up being processed is the same one that was validated.

Issue Links

• links to: GitHub Pull Request #3508