[LU-11695] disabling the xattr cache on client for LSOM

• Type: Improvement
• Resolution: Fixed
• Priority: Major
• Fix Version/s: Lustre 2.16.0, Lustre 2.15.3
• Assignee: Qian Yingjin
• Reporter: Qian Yingjin

Description

Currently, to get uptodate LSOM data, we need to set llite.*.xattr_cache=0 to disable the xattr cache on client completely. This may lead that other kind of xattr can not be cached on client too.

This ticket mainly focues on the heavy-weight solution to disable caching only for LSOM xattr data ("trusted.som") on client.

Issue Links

• is related to: LU-15431 read may return stale data from replicated file
• is related to: LU-15609 Client should not assume RDONLY implies SOM
• is related to: LU-15593 add a param to disable the use of som for size
• is related to: LU-12332 Add a liblustreapi call for IOC_MDC_GETFILEINFO

Comments

[Gerrit Updater]

"Oleg Drokin <[e-mail]>" merged in patch https://review.whamcloud.com/c/fs/lustre-release/+/49952/
Subject: LU-11695 som: disabling xattr cache for LSOM on client
Project: fs/lustre-release
Branch: b2_15
Current Patch Set:
Commit: dcd842e870a099e18a9afcb817f382648c96bed0

[Gerrit Updater]

"Jian Yu <[e-mail]>" uploaded a new patch: https://review.whamcloud.com/c/fs/lustre-release/+/49952
Subject: LU-11695 som: disabling xattr cache for LSOM on client
Project: fs/lustre-release
Branch: b2_15
Current Patch Set: 1
Commit: e32b3e958a1210c8b082668a7afc936c3e5f16fe

[Peter Jones]

Landed for 2.16

[Gerrit Updater]

"Oleg Drokin <[e-mail]>" merged in patch https://review.whamcloud.com/33711/
Subject: LU-11695 som: disabling xattr cache for LSOM on client
Project: fs/lustre-release
Branch: master
Current Patch Set:
Commit: 192902851d73ec246af92a2ff7be8f23b08c4343

[Andreas Dilger]

It turns out that the trusted.som xattr is not used directly on the client for anything except "lfs getsom", so keeping it in the xattr cache doesn't help any real workload, and only serves to confuse tests that are using getsom and see a cached value that is stale.

I've un-abandoned patch https://review.whamcloud.com/33711 "LU-11695 som: disabling xattr cache for LSOM on client", but it will need to be rebased to resolve conflicts.

[Andreas Dilger]

Now that the statx() patch is landing, I think this patch should be abandoned, and this ticket closed.

[Li Xi]

I think at least currently, there is no requirement to use the client side interface to acess the LSOM. So, I'd suggest to delay the implement of this API until we started to see some real requirement for it. After all, LSOM is designed for MDT scanning, not client side accessment. And I think Yingjin's patch is enough to fix the test problem for now.