[LU-8371] Optimize open of known negative dentry

• Type: Bug
• Resolution: Fixed
• Priority: Minor
• Fix Version/s: Lustre 2.9.0
• Severity: 3
• Assignee: Oleg Drokin
• Reporter: Oleg Drokin

Description

While working with Al Viro on some corner cases in atomic open, I noticed that we are doing a lot more work than necessary there.

If we were called with a negative dentry - that means just now we revalidated that dentry so there's no point in contacting MDS to open that file (unless it's a create request), we can just return ENOENT and be done with it which speeds up 99.9% of all usecases and the remaining 0.15 where it's a valid race, we just resolve it the other way as is perfectly fine for us to do.

Comments

[Peter Jones]

Landed for 2.9

[Gerrit Updater]

Oleg Drokin ([e-mail]) merged in patch http://review.whamcloud.com/21168/
Subject: LU-8371 llite: Trust creates in revalidate too.
Project: fs/lustre-release
Branch: master
Current Patch Set:
Commit: 9573911bfb4a2c3d7e2047c9d5f5440d9c7e7db5

[Gerrit Updater]

Oleg Drokin ([e-mail]) merged in patch http://review.whamcloud.com/21161/
Subject: LU-8371 llite: optimize atomic_open of negative dentry.
Project: fs/lustre-release
Branch: master
Current Patch Set:
Commit: 7334a2d33cc4cf4cda0c81b126c4cb8ab28a888d

[Gerrit Updater]

Oleg Drokin ([e-mail]) uploaded a new patch: http://review.whamcloud.com/21168
Subject: LU-8371 llite: Trust creates in revalidate too.
Project: fs/lustre-release
Branch: master
Current Patch Set: 1
Commit: 2852d1a30a7778c233b22ad477e85ff75e5097d0

[Gerrit Updater]

Oleg Drokin ([e-mail]) uploaded a new patch: http://review.whamcloud.com/21161
Subject: LU-8371: llite: optimize atomic_open of negative dentry.
Project: fs/lustre-release
Branch: master
Current Patch Set: 1
Commit: 34867f1a3a4f8f2cbb622b0b5b4ccbd88f679249