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Feature #9754

A 'fence and evict' client eviction command

Added by John Spray almost 3 years ago. Updated about 2 months ago.

Status:
Resolved
Priority:
Normal
Assignee:
-
Category:
Correctness/Safety
Target version:
-
Start date:
10/13/2014
Due date:
% Done:

0%

Source:
other
Tags:
Backport:
Reviewed:
User Impact:
Affected Versions:
Release:
Component(FS):
Common/Protocol, MDS, MDSMonitor
Needs Doc:
No

Description

Currently the "session evict" operation on the MDS admin socket will terminate the session, and release any capabilities held by that client. Other clients are then free to operate on the files that the evicted client might have been operating on.

This is unsafe if the evicted client is in the middle of doing some I/O: a new client might open a file, write some data to it, and have that data overwritten by the evicted client who hasn't yet relealised that he was evicted.

The correct procedure is:

  • Blacklist the client
  • Wait til the MDSs have all got the new post-blacklist-OSDMap
  • Instruct all MDSs to terminate the client session
  • Ensure that all other clients do not use any new caps until they have seen the post-blacklist OSDMap.

Can implement this in MDSMonitor using MCommands to the MDSs, on top of the OSD epoch barrier stuff built for #7317


Related issues

Related to fs - Feature #9940: uclient: be more robust when dealing with outstanding RADOS IO and stale caps New 10/29/2014
Related to fs - Feature #17980: MDS should reject connections from OSD-blacklisted clients Resolved 11/21/2016

History

#1 Updated by Greg Farnum about 1 year ago

  • Category set to Correctness/Safety
  • Component(FS) Common/Protocol, MDS, MDSMonitor added

#2 Updated by John Spray 8 months ago

  • Related to Feature #17980: MDS should reject connections from OSD-blacklisted clients added

#3 Updated by John Spray 5 months ago

  • Status changed from New to In Progress

#4 Updated by John Spray 5 months ago

Underway on jcsp/wip-17980 along with #17980

#5 Updated by John Spray 3 months ago

  • Status changed from In Progress to Need Review

See #17980 patch

#6 Updated by John Spray about 2 months ago

  • Status changed from Need Review to Resolved

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