[LU-5549] cl_default_mds_easize not refreshed

• Status: Resolved
• Project: Lustre
• Fix Version/s: Lustre 2.7.0
• Type: Bug
• Priority: Major
• Reporter: Ned Bass
• Assignee: Lai Siyao
• Resolution: Fixed
• Labels: llnl, patch
• Severity: 3

Description

The client_obd::cl_default_mds_easize field should be maintained to
reflect the largest EA size seen by the MDT. The MDC uses
cl_default_mds_easize to size request buffers appropriately to avoid
unnecessary memory reallocations. In the current code, the value is
only updated if client_obd::cl_max_mds_easize is strictly less than
mdt_body::mbo_max_mdsize. This condition is almost never met, because
client_obd::cl_max_mds_easize is computed at client mount-time based
on the number of OSTs in the filesystem, so the MDT won't ever see a
EA size larger than that.

As a result, client_obd::cl_default_mds_easize indefinitely retains
its initial value, which is computed at client mount-time based on
the filesystem's default stripe width. Any getattr() requests for
more widely striped files will consequently allocate a request buffer
that is too small, forcing reallocations on both the client and
server side. To avoid this, update client_obd::cl_default_mds_easize
independently of the value of client_obd::cl_max_mds_easize.

Issue Links

• is related to: LU-3338 IOC_MDC_GETFILESTRIPE can abuse vmall...

Comments

[Ned Bass]

Please see http://review.whamcloud.com/#/c/11614/

[Peter Jones]

Lai

Could you please take care of this patch?

Thanks

Peter

[Christopher Morrone]

Did http://review.whamcloud.com/#/c/11614 hit a known issue in testing? Does it just need testing relaunched?

[Lai Siyao]

Test relaunch is not authorised to all now, so I've asked Yujian to relaunch it. I'll watch its status.

[Gerrit Updater]

Ned Bass ([e-mail]) uploaded a new patch: http://review.whamcloud.com/13112
Subject: LU-5549 llite: make default_easize writeable in /proc
Project: fs/lustre-release
Branch: master
Current Patch Set: 1
Commit: 047c8acbdbaf60b5513ce1f9bc9d621814780882

[Gerrit Updater]

Oleg Drokin ([e-mail]) merged in patch http://review.whamcloud.com/13112/
Subject: LU-5549 llite: make default_easize writeable in /proc
Project: fs/lustre-release
Branch: master
Current Patch Set:
Commit: 9d9db87afc80ed3e98e1fc05b3ad97a89ebf577a

[Gerrit Updater]

Oleg Drokin ([e-mail]) merged in patch http://review.whamcloud.com/11614/
Subject: LU-5549 mdc: cl_default_mds_easize not refreshed
Project: fs/lustre-release
Branch: master
Current Patch Set:
Commit: e709e661395af42471f5ecf3c87f2fa1d3031fbb

[Peter Jones]

Landed for 2.7