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Bug #37368

mds: directories pinned keep being replicated back and forth between exporting mds and importing mds

Added by Xuehan Xu 25 days ago. Updated 4 days ago.

Status:
Pending Backport
Priority:
High
Assignee:
Category:
Correctness/Safety
Target version:
Start date:
Due date:
% Done:

0%

Source:
Community (dev)
Tags:
Backport:
mimic,luminous
Regression:
No
Severity:
3 - minor
Reviewed:
Affected Versions:
ceph-qa-suite:
Component(FS):
MDS
Labels (FS):
Pull request ID:

Description

Recently, when developing the rstat propagation function, we found that when pinning some directory to a specific rank, there exists chances that the directory pinned keep being replicated back and forth between exporting mds and importing mds.

After a series of debugging, we believe this is due to the fact that exporting mds put the inode into "export_pin_queue" before the journaling of "setattr" request and, during the migration, "projected inode" is not replicated. So, when the migration happens before the completion of the "setattr" request's journaling, the importing mds would receive an inode whose export_pin is -1. So, when the importing mds does MDBalancer::tick, it would find that the inode just imported should be pinned to the rank that some of its parent belongs to, which is the exporting mds by a large chance. So there goes a export back from the importing mds to the exporting mds.


Related issues

Copied to fs - Backport #37606: luminous: mds: directories pinned keep being replicated back and forth between exporting mds and importing mds In Progress
Copied to fs - Backport #37607: mimic: mds: directories pinned keep being replicated back and forth between exporting mds and importing mds In Progress

History

#1 Updated by Patrick Donnelly 20 days ago

  • Status changed from New to Need Review
  • Assignee set to Xuehan Xu
  • Priority changed from Normal to High
  • Start date deleted (11/22/2018)
  • Backport set to mimic,luminous
  • Pull request ID set to 25220
  • ceph-qa-suite deleted (fs)

#2 Updated by Patrick Donnelly 9 days ago

  • Status changed from Need Review to Pending Backport

#3 Updated by Nathan Cutler 5 days ago

  • Copied to Backport #37606: luminous: mds: directories pinned keep being replicated back and forth between exporting mds and importing mds added

#4 Updated by Nathan Cutler 5 days ago

  • Copied to Backport #37607: mimic: mds: directories pinned keep being replicated back and forth between exporting mds and importing mds added

#5 Updated by Patrick Donnelly 4 days ago

Not sure why I marked this Pending Backport but I've now merged the PR into master.

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